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1
Yoza, B. K., and R. G. Roeder. "Identification of a novel factor that interacts with an immunoglobulin heavy-chain promoter and stimulates transcription in conjunction with the lymphoid cell-specific factor OTF2." Molecular and Cellular Biology 10, no. 5 (May 1990): 2145–53. http://dx.doi.org/10.1128/mcb.10.5.2145.
Full textAbstract:
The tissue-specific expression of the MOPC 141 immunoglobulin heavy-chain gene was studied by using in vitro transcription. B-cell-specific transcription of this gene was dependent on the octamer element 5'-ATGCAAAG-3', located in the upstream region of this promoter and in the promoters of all other immunoglobulin heavy- and light-chain genes. The interaction of purified octamer transcription factors 1 and 2 (OTF1 and OTF2) with the MOPC 141 promoter was studied by using electrophoretic mobility shift assays and DNase I footprinting. Purified OTF1 from HeLa cells and OTF1 and OTF2 from B cells bound to identical sequences within the heavy-chain promoter. The OTF interactions we observed extended over the heptamer element 5'-CTCAGGA-3', and it seems likely that the binding of the purified factors involves cooperation between octamer and heptamer sites in this promoter. In addition to these elements, we identified a second regulatory element, the N element with the sequence 5'-GGAACCTCCCCC-3'. The N element could independently mediate low levels of transcription in both B-cell and HeLa-cell extracts, and, in conjunction with the octamer element, it can promote high levels of transcription in B-cell extracts. The N element bound a transcription factor, NTF, that is ubiquitous in cell-type distribution, and NTF was distinct from any of the previously described proteins that bind to similar sequences. Based on these results, we propose that NTF and OTF2 interactions (both with their cognate DNA elements and possibly at the protein-protein level) may be critical to B-cell-specific expression and that these interactions provide additional pathways for regulating gene expression.
2
Yoza, B. K., and R. G. Roeder. "Identification of a novel factor that interacts with an immunoglobulin heavy-chain promoter and stimulates transcription in conjunction with the lymphoid cell-specific factor OTF2." Molecular and Cellular Biology 10, no. 5 (May 1990): 2145–53. http://dx.doi.org/10.1128/mcb.10.5.2145-2153.1990.
Full textAbstract:
The tissue-specific expression of the MOPC 141 immunoglobulin heavy-chain gene was studied by using in vitro transcription. B-cell-specific transcription of this gene was dependent on the octamer element 5'-ATGCAAAG-3', located in the upstream region of this promoter and in the promoters of all other immunoglobulin heavy- and light-chain genes. The interaction of purified octamer transcription factors 1 and 2 (OTF1 and OTF2) with the MOPC 141 promoter was studied by using electrophoretic mobility shift assays and DNase I footprinting. Purified OTF1 from HeLa cells and OTF1 and OTF2 from B cells bound to identical sequences within the heavy-chain promoter. The OTF interactions we observed extended over the heptamer element 5'-CTCAGGA-3', and it seems likely that the binding of the purified factors involves cooperation between octamer and heptamer sites in this promoter. In addition to these elements, we identified a second regulatory element, the N element with the sequence 5'-GGAACCTCCCCC-3'. The N element could independently mediate low levels of transcription in both B-cell and HeLa-cell extracts, and, in conjunction with the octamer element, it can promote high levels of transcription in B-cell extracts. The N element bound a transcription factor, NTF, that is ubiquitous in cell-type distribution, and NTF was distinct from any of the previously described proteins that bind to similar sequences. Based on these results, we propose that NTF and OTF2 interactions (both with their cognate DNA elements and possibly at the protein-protein level) may be critical to B-cell-specific expression and that these interactions provide additional pathways for regulating gene expression.
3
Miller, C. P., J. C. Lin, and J. F. Habener. "Transcription of the rat glucagon gene by the cyclic AMP response element-binding protein CREB is modulated by adjacent CREB-associated proteins." Molecular and Cellular Biology 13, no. 11 (November 1993): 7080–90. http://dx.doi.org/10.1128/mcb.13.11.7080.
Full textAbstract:
The cyclic AMP (cAMP) response element (CRE) of the rat glucagon gene (Glu-CRE, 5'-TGACGTCA-3') mediates transcriptional responses to 8-bromo-cAMP and protein kinase A (PKA) in a glucagon-producing hamster islet cell line (InR1G9). By several different DNA-protein binding assays, we show that the transcription factor CREB binds to the CRE octamer and that additional nuclear proteins bind to sequences adjacent to the CRE. Mutation of the Glu-CRE octamer attenuates both the binding of CREB and cAMP-dependent PKA-stimulated transcriptional activity in transient transfection experiments but does not affect the binding of adjacent CREB-associated proteins. Progressive deletions and clustered point mutations of the sequences flanking the Glu-CRE identify sequences (5'-TCATT-3') located both 5' and 3' to the core CRE octamer that bind several proteins. Two proteins with molecular masses of 80 and 100 kDa bind to each of the 5' and 3' TCATT sites. Formation of additional protein-DNA complexes containing 45- and 20-kDa proteins depends upon the integrity of both TCATT sequences. Deletion or point mutation of the TCATT motif located on the 3' side of the CRE octamer results in enhanced transcriptional responses to PKA, suggesting that the CREB-associated proteins decrease the ability of CREB to mediate PKA-stimulated transcription. Results from these studies demonstrate that nucleotides flanking the core CRE octamer can influence the activity of the CRE by serving as binding sites for proteins that modulate the function of CREB and suggest a mechanism to explain why some consensus palindromic CREs are less responsive to cAMP stimulation than others.
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Miller, C. P., J. C. Lin, and J. F. Habener. "Transcription of the rat glucagon gene by the cyclic AMP response element-binding protein CREB is modulated by adjacent CREB-associated proteins." Molecular and Cellular Biology 13, no. 11 (November 1993): 7080–90. http://dx.doi.org/10.1128/mcb.13.11.7080-7090.1993.
Full textAbstract:
The cyclic AMP (cAMP) response element (CRE) of the rat glucagon gene (Glu-CRE, 5'-TGACGTCA-3') mediates transcriptional responses to 8-bromo-cAMP and protein kinase A (PKA) in a glucagon-producing hamster islet cell line (InR1G9). By several different DNA-protein binding assays, we show that the transcription factor CREB binds to the CRE octamer and that additional nuclear proteins bind to sequences adjacent to the CRE. Mutation of the Glu-CRE octamer attenuates both the binding of CREB and cAMP-dependent PKA-stimulated transcriptional activity in transient transfection experiments but does not affect the binding of adjacent CREB-associated proteins. Progressive deletions and clustered point mutations of the sequences flanking the Glu-CRE identify sequences (5'-TCATT-3') located both 5' and 3' to the core CRE octamer that bind several proteins. Two proteins with molecular masses of 80 and 100 kDa bind to each of the 5' and 3' TCATT sites. Formation of additional protein-DNA complexes containing 45- and 20-kDa proteins depends upon the integrity of both TCATT sequences. Deletion or point mutation of the TCATT motif located on the 3' side of the CRE octamer results in enhanced transcriptional responses to PKA, suggesting that the CREB-associated proteins decrease the ability of CREB to mediate PKA-stimulated transcription. Results from these studies demonstrate that nucleotides flanking the core CRE octamer can influence the activity of the CRE by serving as binding sites for proteins that modulate the function of CREB and suggest a mechanism to explain why some consensus palindromic CREs are less responsive to cAMP stimulation than others.
5
Rosfjord, E., B. Scholtz, R. Lewis, and A. Rizzino. "Phosphorylation and DNA Binding of the Octamer Binding Transcription Factor OCT-3." Biochemical and Biophysical Research Communications 212, no. 3 (July 1995): 847–53. http://dx.doi.org/10.1006/bbrc.1995.2046.
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Roebuck, K. A., D. P. Szeto, K. P. Green, Q. N. Fan, and W. E. Stumph. "Octamer and SPH motifs in the U1 enhancer cooperate to activate U1 RNA gene expression." Molecular and Cellular Biology 10, no. 1 (January 1990): 341–52. http://dx.doi.org/10.1128/mcb.10.1.341.
Full textAbstract:
The transcriptional enhancer of a chicken U1 small nuclear RNA gene has been shown to extend over approximately 50 base pairs of DNA sequence located 180 to 230 base pairs upstream of the U1 transcription initiation site. It is composed of multiple functional motifs, including a GC box, an octamer motif, and a novel SPH motif. The contributions of these three distinct sequence motifs to enhancer function were studied with an oocyte expression assay. Under noncompetitive conditions in oocytes, the SPH motif is capable of stimulating U1 RNA transcription in the absence of the other functional motifs, whereas the octamer motif by itself lacks this ability. However, to form a transcription complex that is stable to challenge by a second competing small nuclear RNA transcription unit, both the octamer and SPH motifs are required. The GC box, although required for full enhancer activity, is not essential for stable complex formation in oocytes. Site-directed mutagenesis was used to study the DNA sequence requirements of the SPH motif. Functional activity of the SPH motif is spread throughout a 24-base-pair region 3' of the octamer but is particularly dependent upon sequences near an SphI restriction site located at the center of the SPH motif. Using embryonic chicken tissue as a source material, we identified and partially purified a factor, termed SBF, that binds sequence specifically to the SPH motif of the U1 enhancer. The ability of this factor to recognize and bind to mutant enhancer DNA fragments in vitro correlates with the functional activity of the corresponding enhancer sequences in vivo.
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Roebuck, K. A., D. P. Szeto, K. P. Green, Q. N. Fan, and W. E. Stumph. "Octamer and SPH motifs in the U1 enhancer cooperate to activate U1 RNA gene expression." Molecular and Cellular Biology 10, no. 1 (January 1990): 341–52. http://dx.doi.org/10.1128/mcb.10.1.341-352.1990.
Full textAbstract:
The transcriptional enhancer of a chicken U1 small nuclear RNA gene has been shown to extend over approximately 50 base pairs of DNA sequence located 180 to 230 base pairs upstream of the U1 transcription initiation site. It is composed of multiple functional motifs, including a GC box, an octamer motif, and a novel SPH motif. The contributions of these three distinct sequence motifs to enhancer function were studied with an oocyte expression assay. Under noncompetitive conditions in oocytes, the SPH motif is capable of stimulating U1 RNA transcription in the absence of the other functional motifs, whereas the octamer motif by itself lacks this ability. However, to form a transcription complex that is stable to challenge by a second competing small nuclear RNA transcription unit, both the octamer and SPH motifs are required. The GC box, although required for full enhancer activity, is not essential for stable complex formation in oocytes. Site-directed mutagenesis was used to study the DNA sequence requirements of the SPH motif. Functional activity of the SPH motif is spread throughout a 24-base-pair region 3' of the octamer but is particularly dependent upon sequences near an SphI restriction site located at the center of the SPH motif. Using embryonic chicken tissue as a source material, we identified and partially purified a factor, termed SBF, that binds sequence specifically to the SPH motif of the U1 enhancer. The ability of this factor to recognize and bind to mutant enhancer DNA fragments in vitro correlates with the functional activity of the corresponding enhancer sequences in vivo.
8
Roebuck, K. A., R. J. Walker, and W. E. Stumph. "Multiple functional motifs in the chicken U1 RNA gene enhancer." Molecular and Cellular Biology 7, no. 12 (December 1987): 4185–93. http://dx.doi.org/10.1128/mcb.7.12.4185.
Full textAbstract:
The DNA sequence requirements of chicken U1 RNA gene expression have been examined in an oocyte transcription system. An enhancer region, which was required for efficient U1 RNA gene expression, is contained within a region of conserved DNA sequences spanning nucleotide positions -230 to -183, upstream of the transcriptional initiation site. These DNA sequences can be divided into at least two distinct subregions or domains that acted synergistically to provide a greater than 20-fold stimulation of U1 RNA synthesis. The first domain contains the octamer sequence ATGCAAAT and was recognized by a DNA-binding factor present in HeLa cell extracts. The second domain (the SPH domain) consists of conserved sequences immediately downstream of the octamer and is an essential component of the enhancer. In the oocyte, the DNA sequences of the SPH domain were able to enhance gene expression at least 10-fold in the absence of the octamer domain. In contrast, the octamer domain, although required for full U1 RNA gene activity, was unable to stimulate expression in the absence of the adjacent downstream DNA sequences. These findings imply that sequences 3' of the octamer play a major role in the function of the chicken U1 RNA gene enhancer. This concept was supported by transcriptional competition studies in which a cloned chicken U4B RNA gene was used to compete for limiting transcription factors in oocytes. Multiple sequence motifs that can function in a variety of cis-linked configurations may be a general feature of vertebrate small nuclear RNA gene enhancers.
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Roebuck, K. A., R. J. Walker, and W. E. Stumph. "Multiple functional motifs in the chicken U1 RNA gene enhancer." Molecular and Cellular Biology 7, no. 12 (December 1987): 4185–93. http://dx.doi.org/10.1128/mcb.7.12.4185-4193.1987.
Full textAbstract:
The DNA sequence requirements of chicken U1 RNA gene expression have been examined in an oocyte transcription system. An enhancer region, which was required for efficient U1 RNA gene expression, is contained within a region of conserved DNA sequences spanning nucleotide positions -230 to -183, upstream of the transcriptional initiation site. These DNA sequences can be divided into at least two distinct subregions or domains that acted synergistically to provide a greater than 20-fold stimulation of U1 RNA synthesis. The first domain contains the octamer sequence ATGCAAAT and was recognized by a DNA-binding factor present in HeLa cell extracts. The second domain (the SPH domain) consists of conserved sequences immediately downstream of the octamer and is an essential component of the enhancer. In the oocyte, the DNA sequences of the SPH domain were able to enhance gene expression at least 10-fold in the absence of the octamer domain. In contrast, the octamer domain, although required for full U1 RNA gene activity, was unable to stimulate expression in the absence of the adjacent downstream DNA sequences. These findings imply that sequences 3' of the octamer play a major role in the function of the chicken U1 RNA gene enhancer. This concept was supported by transcriptional competition studies in which a cloned chicken U4B RNA gene was used to compete for limiting transcription factors in oocytes. Multiple sequence motifs that can function in a variety of cis-linked configurations may be a general feature of vertebrate small nuclear RNA gene enhancers.
10
Ambrosetti, D. C., C. Basilico, and L. Dailey. "Synergistic activation of the fibroblast growth factor 4 enhancer by Sox2 and Oct-3 depends on protein-protein interactions facilitated by a specific spatial arrangement of factor binding sites." Molecular and Cellular Biology 17, no. 11 (November 1997): 6321–29. http://dx.doi.org/10.1128/mcb.17.11.6321.
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Octamer binding and Sox factors are thought to play important roles in development by potentiating the transcriptional activation of specific gene subsets. The proteins within these factor families are related by the presence of highly conserved DNA binding domains, the octamer binding protein POU domain or the Sox factors HMG domain. We have previously shown that fibroblast growth factor 4 (FGF-4) gene expression in embryonal carcinoma cells requires a synergistic interaction between Oct-3 and Sox2 on the FGF-4 enhancer. Sox2 and Oct-3 bind to adjacent sites within this enhancer to form a ternary protein-DNA complex (Oct-3*) whose assembly correlates with enhancer activity. We now demonstrate that increasing the distance between the octamer and Sox binding sites by base pair insertion results in a loss of enhancer function. Significantly, those enhancer "spacing mutants" which failed to activate transcription were also compromised in their ability to form the Oct* complexes even though they could still bind both Sox2 and the octamer binding proteins, suggesting that a direct interaction between Sox2 and Oct-3 is necessary for enhancer function. Consistent with this hypothesis, Oct-3 and Sox2 can participate in a direct protein-protein interaction in vitro in the absence of DNA, and both this interaction and assembly of the ternary Oct* complexes require only the octamer protein POU and Sox2 HMG domains. Assembly of the ternary complex by these two protein domains occurs in a cooperative manner on FGF-4 enhancer DNA, and the loss of this cooperative interaction contributes to the defect in Oct-3* formation observed for the enhancer spacing mutants. These observations indicate that Oct-3* assembly results from protein-protein interactions between the domains of Sox2 and Oct-3 that mediate their binding to DNA, but it also requires a specific arrangement of the binding sites within the FGF-4 enhancer DNA. Thus, these results define one parameter that is fundamental to synergistic activation by Sox2 and Oct-3 and further emphasize the critical role of enhancer DNA sequences in the proper assembly of functional activation complexes.
11
Dailey, L., H. Yuan, and C. Basilico. "Interaction between a novel F9-specific factor and octamer-binding proteins is required for cell-type-restricted activity of the fibroblast growth factor 4 enhancer." Molecular and Cellular Biology 14, no. 12 (December 1994): 7758–69. http://dx.doi.org/10.1128/mcb.14.12.7758.
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Understanding how diverse transcription patterns are achieved through common factor binding elements is a fundamental question that underlies much of developmental and cellular biology. One example is provided by the fibroblast growth factor 4 (FGF-4) gene, whose expression is restricted to specific embryonic tissues during development and to undifferentiated embryonal carcinoma cells in tissue culture. Analysis of the cis- and trans-acting elements required for the activity of the previously identified FGF-4 enhancer in F9 embryonal carcinoma cells showed that enhancer function depends on sequences that bind Sp1 and ubiquitous as well as F9-specific octamer-binding proteins. However, sequences immediately upstream of the octamer motif, which conform to a binding site for the high-mobility group (HMG) domain factor family, were also critical to enhancer function. We have identified a novel F9-specific factor, Fx, which specifically recognizes this motif. Fx formed complexes with either Oct-1 or Oct-3 in a template-dependent manner. The ability of different enhancer variants to form the Oct-Fx complexes correlated with enhancer activity, indicating that these complexes play an essential role in transcriptional activation of the FGF-4 gene. Thus, while FGF-4 enhancer function is octamer site dependent, its developmentally restricted activity is determined by the interaction of octamer-binding proteins with the tissue-specific factor Fx.
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Dailey, L., H. Yuan, and C. Basilico. "Interaction between a novel F9-specific factor and octamer-binding proteins is required for cell-type-restricted activity of the fibroblast growth factor 4 enhancer." Molecular and Cellular Biology 14, no. 12 (December 1994): 7758–69. http://dx.doi.org/10.1128/mcb.14.12.7758-7769.1994.
Full textAbstract:
Understanding how diverse transcription patterns are achieved through common factor binding elements is a fundamental question that underlies much of developmental and cellular biology. One example is provided by the fibroblast growth factor 4 (FGF-4) gene, whose expression is restricted to specific embryonic tissues during development and to undifferentiated embryonal carcinoma cells in tissue culture. Analysis of the cis- and trans-acting elements required for the activity of the previously identified FGF-4 enhancer in F9 embryonal carcinoma cells showed that enhancer function depends on sequences that bind Sp1 and ubiquitous as well as F9-specific octamer-binding proteins. However, sequences immediately upstream of the octamer motif, which conform to a binding site for the high-mobility group (HMG) domain factor family, were also critical to enhancer function. We have identified a novel F9-specific factor, Fx, which specifically recognizes this motif. Fx formed complexes with either Oct-1 or Oct-3 in a template-dependent manner. The ability of different enhancer variants to form the Oct-Fx complexes correlated with enhancer activity, indicating that these complexes play an essential role in transcriptional activation of the FGF-4 gene. Thus, while FGF-4 enhancer function is octamer site dependent, its developmentally restricted activity is determined by the interaction of octamer-binding proteins with the tissue-specific factor Fx.
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ARANBURU, Alaitz, Robert CARLSSON, Christine PERSSON, and Tomas LEANDERSON. "Transcription factor AP-4 is a ligand for immunoglobulin-κ promoter E-box elements." Biochemical Journal 354, no. 2 (February 22, 2001): 431–38. http://dx.doi.org/10.1042/bj3540431.
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Immunoglobulin (Ig)-κ promoters from humans and mice share conserved sequences. The octamer element is common to all Ig promoters and pivotal for their function. However, other conserved sequence motifs, that differ between Ig variable gene families, are required for normal promoter function. These conserved motifs do not stimulate transcription in the absence of an octamer. One example is an E-box of the E47/E12 type (5′-CAGCTG-3′), which is found in all promoters of the human and murine Ig-κ gene subgroups/families, with the exception of subgroups II and VI and their related murine families. In the present study we show that the ubiquitously expressed transcription factor AP-4, and not E47, interacts specifically with the κ promoter E-boxes when tested in electrophoretic mobility-shift assays using nuclear extracts derived from human and murine B-cell lines. Furthermore, AP-4, unlike E47, did not act as a transactivator, which is in agreement with previous studies on intact κ promoters, showing that transcription is absent when the octamer element has been mutated. Based on these data, and the conservation of the 5′-CAGCTG-3′ motif among human and murine κ promoters, we propose that AP-4 is the major ligand for Ig-κ promoter E-boxes.
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Neumann, M., H. W. Fries, C. Scheicher, P. Keikavoussi, A. Kolb-Mäurer, E. B. Bröcker, E. Serfling, and E. Kämpgen. "Differential expression of Rel/NF-κB and octamer factors is a hallmark of the generation and maturation of dendritic cells." Blood 95, no. 1 (January 1, 2000): 277–85. http://dx.doi.org/10.1182/blood.v95.1.277.
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Abstract A key feature of maturation of dendritic cells is the down-regulation of antigen-processing and up-regulation of immunostimulatory capacities. To study the differential expression of transcription factors in this process, we investigated the nuclear translocation and DNA binding of Rel/NF-κB and octamer factors during in vitro generation and maturation of dendritic cells compared with macrophage development. RelB was the only factor strongly up-regulated during the generation of both immature dendritic cells and macrophages. Cytokine-induced maturation of dendritic cells resulted in an increase in nuclear RelB, p50, p52, and especially c-Rel, whereas cytokine-treated macrophages responded poorly. This up-regulation of NF-κB factors did not correlate with lower levels of cytosolic NF-κB inhibitors, the IκBs. One IκB, Bcl-3, was strongly expressed only in mature dendritic cells. Furthermore, generation and maturation of dendritic cells led to a continuous down-regulation of the octamer factor Oct-2, whereas monocytes and macrophages displayed high Oct-2 levels. A similar pattern of maturation-induced changes in transcription factor levels was found in cultured murine epidermal Langerhans cells, suggesting a general physiological significance of these findings. Finally, this pattern of differential activation of Rel and octamer factors appears to be suitable in determining the maturation stage of dendritic cells generated by treatment with different cytokine combinations in vitro. (Blood. 2000;95:277-285)
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Neumann, M., H. W. Fries, C. Scheicher, P. Keikavoussi, A. Kolb-Mäurer, E. B. Bröcker, E. Serfling, and E. Kämpgen. "Differential expression of Rel/NF-κB and octamer factors is a hallmark of the generation and maturation of dendritic cells." Blood 95, no. 1 (January 1, 2000): 277–85. http://dx.doi.org/10.1182/blood.v95.1.277.001k45_277_285.
Full textAbstract:
A key feature of maturation of dendritic cells is the down-regulation of antigen-processing and up-regulation of immunostimulatory capacities. To study the differential expression of transcription factors in this process, we investigated the nuclear translocation and DNA binding of Rel/NF-κB and octamer factors during in vitro generation and maturation of dendritic cells compared with macrophage development. RelB was the only factor strongly up-regulated during the generation of both immature dendritic cells and macrophages. Cytokine-induced maturation of dendritic cells resulted in an increase in nuclear RelB, p50, p52, and especially c-Rel, whereas cytokine-treated macrophages responded poorly. This up-regulation of NF-κB factors did not correlate with lower levels of cytosolic NF-κB inhibitors, the IκBs. One IκB, Bcl-3, was strongly expressed only in mature dendritic cells. Furthermore, generation and maturation of dendritic cells led to a continuous down-regulation of the octamer factor Oct-2, whereas monocytes and macrophages displayed high Oct-2 levels. A similar pattern of maturation-induced changes in transcription factor levels was found in cultured murine epidermal Langerhans cells, suggesting a general physiological significance of these findings. Finally, this pattern of differential activation of Rel and octamer factors appears to be suitable in determining the maturation stage of dendritic cells generated by treatment with different cytokine combinations in vitro. (Blood. 2000;95:277-285)
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Theil, Jan, Helmut Laumen, Theresa Marafioti, Michael Hummel, Georg Lenz, Thomas Wirth, and Harald Stein. "Defective octamer-dependent transcription is responsible for silenced immunoglobulin transcription in Reed-Sternberg cells." Blood 97, no. 10 (May 15, 2001): 3191–96. http://dx.doi.org/10.1182/blood.v97.10.3191.
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Abstract The absence of immunoglobulin (Ig) expression in B-cell–derived Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin disease (cHD) was initially suggested to be caused by crippling mutations in the Ig promoter or coding region. More recent investigations have, however, challenged this concept. This study addressed the role of mutations in the Ig promoter region in HRS cells. Nine cases of cHD and 3 B-cell–derived HD lines were analyzed for mutations in the TATA box and octamer motif of the Ig promoter. Mutations in the octamer motif were found in only 1 of the 9 cases and in 1 of the 3 HD cell lines (L1236). Furthermore, in all cases either a complete lack or strong reduction in the expression of the Oct2 transcription factor and the BOB.1/OBF.1 coactivator were found. The relevance of the rare promoter mutations was investigated by assaying the activity of Ig promoter reporter constructs transfected into the HD cell line L1236, which harbors a mutated octamer motif. These Ig reporter constructs were completely inactive in L1236 cells; however, their activity could be reconstituted by the cotransfection of a BOB.1/OBF.1 expression vector. The additional transfection with an Oct2 expression vector did not further enhance the Ig promoter activity. The conclusions drawn from these results are that crippling mutations in the Ig promoter and coding region are not the sole cause for the lack of Ig expression in HRS cells and that defects in the transcription machinery such as absence of BOB.1/OBF.1 are more important for this phenomenon.
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Ushmorov, Alexey, Olga Ritz, Michael Hummel, Frank Leithäuser, Peter Möller, Harald Stein, and Thomas Wirth. "Epigenetic silencing of the immunoglobulin heavy-chain gene in classical Hodgkin lymphoma-derived cell lines contributes to the loss of immunoglobulin expression." Blood 104, no. 10 (November 15, 2004): 3326–34. http://dx.doi.org/10.1182/blood-2003-04-1197.
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Abstract Immunoglobulin production is impaired in Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL) in spite of functional clonal rearrangements. The presence of “crippling” mutations in coding and regulatory regions, as well as down-regulation of B-cell-specific transcription factors, has been suggested as a potential reason for the lack of immunoglobulin (Ig) chain gene transcription. We have investigated the impact of epigenetic silencing in suppressing Ig heavy (H)-chain expression. Chromatin immunoprecipitation (ChIP) was used to analyze transcription factor binding to octamer motifs present in the IgH regulatory regions. Transcription factors were bound to these motifs in control cell lines, however, they were absent in the cHL-derived cell lines KMH2, L1236, and L428. Ectopic expression of octamer-binding transcription factor (Oct2) and/or B-cell Oct binding protein/Oct-binding factor (BOB.1/OBF.1) did not result in any measurable binding to these sites. Increased histone 3 Lysine 9 (H3-K9) methylation was observed in the promoter region of the IgH locus in L428 and L1236 cells. This is a typical feature of heterochromatic, transcriptionally silent regions. Treatment of cHL-derived cell lines with the DNA demethylating agent 5-aza-2′-deoxycytidine (5-aza-dC) partially reactivated IgH transcription and affected chromatin modifications. Our results suggest an important role of epigenetic silencing in the inhibition of IgH transcription in HRS cells. (Blood. 2004;104:3326-3334)
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Nishimoto, Masazumi, Akiko Fukushima, Akihiko Okuda, and Masami Muramatsu. "The Gene for the Embryonic Stem Cell Coactivator UTF1 Carries a Regulatory Element Which Selectively Interacts with a Complex Composed of Oct-3/4 and Sox-2." Molecular and Cellular Biology 19, no. 8 (August 1, 1999): 5453–65. http://dx.doi.org/10.1128/mcb.19.8.5453.
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ABSTRACT UTF1 is a transcriptional coactivator which has recently been isolated and found to be expressed mainly in pluripotent embryonic stem (ES) cells (A. Okuda, A. Fukushima, M. Nishimoto, et al., EMBO J. 17:2019–2032, 1998). To gain insight into the regulatory network of gene expression in ES cells, we have characterized the regulatory elements governing UTF1 gene expression. The results indicate that the UTF1 gene is one of the target genes of an embryonic octamer binding transcription factor, Oct-3/4. UTF1 expression is, like the FGF-4 gene, regulated by the synergistic action of Oct-3/4 and another embryonic factor, Sox-2, implying that the requirement for Sox-2 by Oct-3/4 is not limited to the FGF-4 enhancer but is rather a general mechanism of activation for Oct-3/4. Our biochemical analyses, however, also reveal one distinct difference between these two regulatory elements: unlike the FGF-4 enhancer, the UTF1 regulatory element can, by its one-base difference from the canonical octamer-binding sequence, selectively recruit the complex comprising Oct-3/4 and Sox-2 and preclude the binding of the transcriptionally inactive complex containing Oct-1 or Oct-6. Furthermore, our analyses reveal that these properties are dictated by the unique ability of the Oct-3/4 POU-homeodomain that recognizes a variant of the Octamer motif in the UTF1 regulatory element.
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Sawaya, P. L., B. R. Stripp, J. A. Whitsett, and D. S. Luse. "The lung-specific CC10 gene is regulated by transcription factors from the AP-1, octamer, and hepatocyte nuclear factor 3 families." Molecular and Cellular Biology 13, no. 7 (July 1993): 3860–71. http://dx.doi.org/10.1128/mcb.13.7.3860.
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We have shown that a large fragment (-2339 to +57) from the rat CC10 gene directed lung-specific expression of a reporter construct in transgenic animals. Upon transfection, a smaller fragment (-165 to +57) supported reporter gene expression exclusively in the Clara cell-like NCI-H441 cell line, suggesting that a Clara cell-specific transcriptional element resided on this fragment (B. R. Stripp, P. L. Sawaya, D. S. Luse, K. A. Wikenheiser, S. E. Wert, J. A. Huffman, D. L. Lattier, G. Singh, S. L. Katyal, and J. A. Whitsett, J. Biol. Chem. 267:14703-14712, 1992). The interactions of nuclear proteins with a particular segment of the CC10 promoter which extends from 79 to 128 bp upstream of the CC10 transcription initiation site (CC10 region I) have now been studied. This sequence can stimulate both in vitro transcription in H441 nuclear extract and transient expression of reporter constructs in H441 cells. Electrophoretic mobility shift assays using extracts from H441, HeLa, rat liver, and fetal sheep lung cells were used to demonstrate that members of the AP-1, octamer, and HNF-3 families bind to CC10 region I. Transcription factors from H441 cells which are capable of binding to CC10 region I are either absent in HeLa, rat liver, and fetal sheep lung extracts or enriched in H441 extracts relative to extracts from non-Clara cells.
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Sawaya, P. L., B. R. Stripp, J. A. Whitsett, and D. S. Luse. "The lung-specific CC10 gene is regulated by transcription factors from the AP-1, octamer, and hepatocyte nuclear factor 3 families." Molecular and Cellular Biology 13, no. 7 (July 1993): 3860–71. http://dx.doi.org/10.1128/mcb.13.7.3860-3871.1993.
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We have shown that a large fragment (-2339 to +57) from the rat CC10 gene directed lung-specific expression of a reporter construct in transgenic animals. Upon transfection, a smaller fragment (-165 to +57) supported reporter gene expression exclusively in the Clara cell-like NCI-H441 cell line, suggesting that a Clara cell-specific transcriptional element resided on this fragment (B. R. Stripp, P. L. Sawaya, D. S. Luse, K. A. Wikenheiser, S. E. Wert, J. A. Huffman, D. L. Lattier, G. Singh, S. L. Katyal, and J. A. Whitsett, J. Biol. Chem. 267:14703-14712, 1992). The interactions of nuclear proteins with a particular segment of the CC10 promoter which extends from 79 to 128 bp upstream of the CC10 transcription initiation site (CC10 region I) have now been studied. This sequence can stimulate both in vitro transcription in H441 nuclear extract and transient expression of reporter constructs in H441 cells. Electrophoretic mobility shift assays using extracts from H441, HeLa, rat liver, and fetal sheep lung cells were used to demonstrate that members of the AP-1, octamer, and HNF-3 families bind to CC10 region I. Transcription factors from H441 cells which are capable of binding to CC10 region I are either absent in HeLa, rat liver, and fetal sheep lung extracts or enriched in H441 extracts relative to extracts from non-Clara cells.
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Ben-Shushan, Etti, James R. Thompson, Lorraine J. Gudas, and Yehudit Bergman. "Rex-1, a Gene Encoding a Transcription Factor Expressed in the Early Embryo, Is Regulated via Oct-3/4 and Oct-6 Binding to an Octamer Site and a Novel Protein, Rox-1, Binding to an Adjacent Site." Molecular and Cellular Biology 18, no. 4 (April 1, 1998): 1866–78. http://dx.doi.org/10.1128/mcb.18.4.1866.
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ABSTRACT The Rex-1 (Zfp-42) gene, which encodes an acidic zinc finger protein, is expressed at high levels in embryonic stem (ES) and F9 teratocarcinoma cells. Prior analysis identified an octamer motif in the Rex-1 promoter which is required for promoter activity in undifferentiated F9 cells and is involved in retinoic acid (RA)-associated reduction in expression. We show here that the Oct-3/4 transcription factor, but not Oct-1, can either activate or repress the Rex-1 promoter, depending on the cellular environment. Rex-1 repression is enhanced by E1A. The protein domain required for Oct-3/4 activation was mapped to amino acids 1 to 35, whereas the domain required for Oct-3/4 repression was mapped to amino acids 61 to 126, suggesting that the molecular mechanisms underlying transcriptional activation and repression differ. Like Oct-3/4, Oct-6 can also lower the expression of theRex-1 promoter via the octamer site, and the amino-terminal portion of Oct-6 mediates this repression. In addition to the octamer motif, a novel positive regulatory element, located immediately 5′ of the octamer motif, was identified in the Rex-1 promoter. Mutations in this element greatly reduce Rex-1 promoter activity in F9 cells. High levels of a binding protein(s), designated Rox-1, recognize this novel DNA element in F9 cells, and this binding activity is reduced following RA treatment. Taken together, these results indicate that the Rex-1 promoter is regulated by specific octamer family members in early embryonic cells and that a novel element also contributes to Rex-1 expression.
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Ben-Shushan, E., E. Pikarsky, A. Klar, and Y. Bergman. "Extinction of Oct-3/4 gene expression in embryonal carcinoma x fibroblast somatic cell hybrids is accompanied by changes in the methylation status, chromatin structure, and transcriptional activity of the Oct-3/4 upstream region." Molecular and Cellular Biology 13, no. 2 (February 1993): 891–901. http://dx.doi.org/10.1128/mcb.13.2.891.
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In this study we evaluate, for the first time, the molecular mechanism that underlies the extinction of a tissue-specific transcription factor, Oct-3/4, in somatic cell hybrids and compared it with its down-regulation in retinoic acid (RA)-treated embryonal carcinoma (EC) cells. The Oct-3/4 gene, which belongs to the POU family of transcription factors and is abundantly expressed in EC (OTF9-63) cells, provides an excellent model system with which to study the extinction phenomenon. Unlike other genes whose expression has been repressed in hybrid cells but not during in vivo differentiation, Oct-3/4 expression is dramatically repressed in OTF9-63 x fibroblast hybrids and also during embryogenesis. The ectopic expression of Oct-3/4 in hybrid cells under a constitutive promoter is sufficient for transcriptional activation of an octamer-dependent promoter. These results argue against the possibility that fibroblasts contain a direct repressor which binds directly to the octamer sequence and prevents Oct-3/4 protein from binding. The extinction of Oct-3/4 binding activity in the hybrid cells occurs at the level of mRNA transcription, similarly to the repression of Oct-3/4 transcription during in vivo differentiation. This shutdown of Oct-3/4 transcription in hybrid cells and in RA-treated EC cells is accompanied by de novo methylation of its 1.3-kb upstream region. In contrast to EC cells, in which this region is sensitive to MspI digestion, in hybrid cells and in RA-treated EC cells, the Oct-3/4 upstream region is resistant to MspI digestion, which suggests a change in its chromatin structure. Furthermore, extinction is not restricted to the endogenous Oct-3/4 gene but is also exerted upon a transiently transfected reporter gene driven by the Oct-3/4 upstream region. Thus, changes in the cellular activity of trans-acting factors acting on the upstream region also contribute to the inability of the hybrid and RA-treated EC cells to generate Oct-3/4 transcripts. In conclusion, this study draws a connection between the shutdown of Oct-3/4 expression in RA-differentiated EC cells and its extinction in hybrid cells. In both systems, repression of Oct-3/4 expression is achieved through changes in the methylation status, chromatin structure, and transcriptional activity of the Oct-3/4 upstream regulatory region.
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Ben-Shushan, E., E. Pikarsky, A. Klar, and Y. Bergman. "Extinction of Oct-3/4 gene expression in embryonal carcinoma x fibroblast somatic cell hybrids is accompanied by changes in the methylation status, chromatin structure, and transcriptional activity of the Oct-3/4 upstream region." Molecular and Cellular Biology 13, no. 2 (February 1993): 891–901. http://dx.doi.org/10.1128/mcb.13.2.891-901.1993.
Full textAbstract:
In this study we evaluate, for the first time, the molecular mechanism that underlies the extinction of a tissue-specific transcription factor, Oct-3/4, in somatic cell hybrids and compared it with its down-regulation in retinoic acid (RA)-treated embryonal carcinoma (EC) cells. The Oct-3/4 gene, which belongs to the POU family of transcription factors and is abundantly expressed in EC (OTF9-63) cells, provides an excellent model system with which to study the extinction phenomenon. Unlike other genes whose expression has been repressed in hybrid cells but not during in vivo differentiation, Oct-3/4 expression is dramatically repressed in OTF9-63 x fibroblast hybrids and also during embryogenesis. The ectopic expression of Oct-3/4 in hybrid cells under a constitutive promoter is sufficient for transcriptional activation of an octamer-dependent promoter. These results argue against the possibility that fibroblasts contain a direct repressor which binds directly to the octamer sequence and prevents Oct-3/4 protein from binding. The extinction of Oct-3/4 binding activity in the hybrid cells occurs at the level of mRNA transcription, similarly to the repression of Oct-3/4 transcription during in vivo differentiation. This shutdown of Oct-3/4 transcription in hybrid cells and in RA-treated EC cells is accompanied by de novo methylation of its 1.3-kb upstream region. In contrast to EC cells, in which this region is sensitive to MspI digestion, in hybrid cells and in RA-treated EC cells, the Oct-3/4 upstream region is resistant to MspI digestion, which suggests a change in its chromatin structure. Furthermore, extinction is not restricted to the endogenous Oct-3/4 gene but is also exerted upon a transiently transfected reporter gene driven by the Oct-3/4 upstream region. Thus, changes in the cellular activity of trans-acting factors acting on the upstream region also contribute to the inability of the hybrid and RA-treated EC cells to generate Oct-3/4 transcripts. In conclusion, this study draws a connection between the shutdown of Oct-3/4 expression in RA-differentiated EC cells and its extinction in hybrid cells. In both systems, repression of Oct-3/4 expression is achieved through changes in the methylation status, chromatin structure, and transcriptional activity of the Oct-3/4 upstream regulatory region.
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Pfisterer, P., H. König, J. Hess, G. Lipowsky, B. Haendler, W. D. Schleuning, and T. Wirth. "CRISP-3, a protein with homology to plant defense proteins, is expressed in mouse B cells under the control of Oct2." Molecular and Cellular Biology 16, no. 11 (November 1996): 6160–68. http://dx.doi.org/10.1128/mcb.16.11.6160.
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The Oct2 transcription factor is expressed throughout the B-lymphoid lineage and plays an essential role during the terminal phase of B-cell differentiation. Several genes specifically expressed in B lymphocytes have been identified that contain a functional octamer motif in their regulatory elements. However, expression of only a single gene, the murine CD36 gene, has been shown to date to be dependent on Oct2. Here, we present the identification and characterization of a further gene, coding for cysteine-rich secreted protein 3 (CRISP-3), whose expression in B cells is regulated by Oct2. We show that CRISP-3 is expressed in the B-lymphoid lineage specifically at the pre-B-cell stage. By using different experimental strategies, including nuclear run-on experiments, we demonstrate that this gene is transcriptionally activated by Oct2. Furthermore, analysis of CRISP-3 expression in primary B cells derived from either wild-type or Oct2-deficient mice demonstrates the dependence on Oct2. Two variant octamer motifs were identified in the upstream promoter region of the crisp-3 gene, and Oct2 interacts with both of them in vitro. Cotransfection experiments with expression vectors for Oct1 and Oct2 together with a reporter driven by the crisp-3 promoter showed that transcriptional activation of this promoter can only be achieved with Oct2. The C-terminal transactivation domain of Oct2 is required for this activation. Finally, introducing specific mutations in the two variant octamer motifs revealed that both of them are important for full transcriptional activation by Oct2.
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Misra, V., S. Walter, P. Yang, S. Hayes, and P. O'Hare. "Conformational alteration of Oct-1 upon DNA binding dictates selectivity in differential interactions with related transcriptional coactivators." Molecular and Cellular Biology 16, no. 8 (August 1996): 4404–13. http://dx.doi.org/10.1128/mcb.16.8.4404.
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VP16 (termed VP16-H here) of herpes simplex virus (HSV) belongs to a family of related regulatory proteins which includes VP16-B of bovine herpesvirus (BHV). We show that VP16-B, while also being a powerful transactivator of transcription dependent on Oct-1 binding sites in its target promoters, has virtually no activity on a defined VP16-H-responsive, octamer-containing target promoter. While Oct-1 binds equally well to the VP16-B-responsive and -nonresponsive sites, VP16-B interacts with Oct-1 only when Oct-1 is bound to the BHV octamer site and not when it is bound to the HSV site. We show from the analysis of chimeric proteins that the ability of VP16-B to discriminate between the Oct-1 forms depends on features of its N-terminal region. We also show from an analysis of chimeric DNA motifs that sequences that lie 3' to the POU domain-contacting region of the HSV octamer site play a role in making it unresponsive to VP16-B. Finally, we show by high-resolution hydroxyl radical footprint analysis that the conformation of Oct-l is different on the two sites. These results augment our previous report on an allosteric effect of DNA signals on the conformation of bound proteins and indicate that different conformations of the same DNA binding protein can be recognized selectively by related members of interacting regulatory proteins. The possible implications of our observations for selective gene regulation by Oct-1, a ubiquitous transcription factor, and other multimember transcription families are discussed.
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Yamamoto, Kenta, Tsunao Kishida, Yoshiki Sato, Keisuke Nishioka, Akika Ejima, Hiroyoshi Fujiwara, Toshikazu Kubo, Toshiro Yamamoto, Narisato Kanamura, and Osam Mazda. "Direct conversion of human fibroblasts into functional osteoblasts by defined factors." Proceedings of the National Academy of Sciences 112, no. 19 (April 27, 2015): 6152–57. http://dx.doi.org/10.1073/pnas.1420713112.
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Osteoblasts produce calcified bone matrix and contribute to bone formation and remodeling. In this study, we established a procedure to directly convert human fibroblasts into osteoblasts by transducing some defined factors and culturing in osteogenic medium. Osteoblast-specific transcription factors, Runt-related transcription factor 2 (Runx2), and Osterix, in combination with Octamer-binding transcription factor 3/4 (Oct4) and L-Myc (RXOL) transduction, converted ∼80% of the fibroblasts into osteocalcin-producing cells. The directly converted osteoblasts (dOBs) induced by RXOL displayed a similar gene expression profile as normal human osteoblasts and contributed to bone repair after transplantation into immunodeficient mice at artificial bone defect lesions. The dOBs expressed endogenous Runx2 and Osterix, and did not require continuous expression of the exogenous genes to maintain their phenotype. Another combination, Oct4 plus L-Myc (OL), also induced fibroblasts to produce bone matrix, but the OL-transduced cells did not express Osterix and exhibited a more distant gene expression profile to osteoblasts compared with RXOL-transduced cells. These findings strongly suggest successful direct reprogramming of fibroblasts into functional osteoblasts by RXOL, a technology that may provide bone regeneration therapy against bone disorders.
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Baek, Kwang-Hyun, Jihye Choi, and Chang-Zhu Pei. "Cellular Functions of OCT-3/4 Regulated by Ubiquitination in Proliferating Cells." Cancers 12, no. 3 (March 12, 2020): 663. http://dx.doi.org/10.3390/cancers12030663.
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Octamer-binding transcription factor 3/4 (OCT-3/4), which is involved in the tumorigenesis of somatic cancers, has diverse functions during cancer development. Overexpression of OCT-3/4 has been detected in various human somatic tumors, indicating that OCT-3/4 activation may contribute to the development and progression of cancers. Stem cells can undergo self-renewal, pluripotency, and reprogramming with the help of at least four transcription factors, OCT-3/4, SRY box-containing gene 2 (SOX2), Krüppel-like factor 4 (KLF4), and c-MYC. Of these, OCT-3/4 plays a critical role in maintenance of undifferentiated state of embryonic stem cells (ESCs) and in production of induced pluripotent stem cells (iPSCs). Stem cells can undergo partitioning through mitosis and separate into specific cell types, three embryonic germ layers: the endoderm, the mesoderm, and the trophectoderm. It has been demonstrated that the stability of OCT-3/4 is mediated by the ubiquitin-proteasome system (UPS), which is one of the key cellular mechanisms for cellular homeostasis. The framework of the mechanism is simple, but the proteolytic machinery is complicated. Ubiquitination promotes protein degradation, and ubiquitination of OCT-3/4 leads to regulation of cellular proliferation and differentiation. Therefore, it is expected that OCT-3/4 may play a key role in proliferation and differentiation of proliferating cells.
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Kwon, Jeongwoo, Ying-Hua Li, Yu-Jin Jo, YoungJin Oh, Suk Namgoong, and Nam-Hyung Kim. "Inhibition of MEK1/2 and GSK3 (2i system) affects blastocyst quality and early differentiation of porcine parthenotes." PeerJ 6 (January 7, 2019): e5840. http://dx.doi.org/10.7717/peerj.5840.
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Inhibition of both MEK1/2 and glycogen synthase kinase-3 (GSK3; 2i system) facilitates the maintenance of naïve stemness for embryonic stem cells in various mammalian species. However, the effect of the inhibition of the 2i system on porcine early embryogenesis is unknown. We investigated the effect of the 2i system on early embryo development, expression of pluripotency-related genes, and epigenetic modifications. Inhibition of MEK1/2 (by PD0325901) and/or GSK3 (by CHIR99021) did not alter the developmental potential of porcine parthenogenetic embryos, but improved blastocyst quality, as judged by the blastocyst cell number, diameter, and reduction in the number of apoptotic cells. The expression levels of octamer-binding transcription factor 4 and SOX2, the primary transcription factors that maintain embryonic pluripotency, were significantly increased by 2i treatments. Epigenetic modification-related gene expression was altered upon 2i treatment. The collective results indicate that the 2i system in porcine embryos improved embryo developmental potential and blastocyst quality by regulating epigenetic modifications and pluripotency-related gene expression.
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Wang, Victoria E. H., Tara Schmidt, Jianzhu Chen, Phillip A. Sharp, and Dean Tantin. "Embryonic Lethality, Decreased Erythropoiesis, and Defective Octamer-Dependent Promoter Activation in Oct-1-Deficient Mice." Molecular and Cellular Biology 24, no. 3 (February 1, 2004): 1022–32. http://dx.doi.org/10.1128/mcb.24.3.1022-1032.2004.
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ABSTRACT Oct-1 is a sequence-specific DNA binding transcription factor that is believed to regulate a large group of tissue-specific and ubiquitous genes. Both Oct-1 and the related but tissue-restricted Oct-2 protein bind to a DNA sequence termed the octamer motif (5′-ATGCAAAT-3′) with equal affinity in vitro. To address the role of Oct-1 in vivo, an Oct-1-deficient mouse strain was generated by gene targeting. Oct-1-deficient embryos died during gestation, frequently appeared anemic, and suffered from a lack of Ter-119-positive erythroid precursor cells. This defect was cell intrinsic. Fibroblasts derived from these embryos displayed a dramatic decrease in Oct-1 DNA binding activity and a lack of octamer-dependent promoter activity in transient transfection assays. Interestingly, several endogenous genes thought to be regulated by Oct-1 showed no change in expression. When crossed to Oct-2 +/− animals, transheterozygotes were recovered at a very low frequency. These findings suggest a critical role for Oct-1 during development and a stringent gene dosage effect with Oct-2 in mediating postnatal survival.
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Schreiber, Edgar, Andreas Tobler, Ursula Malipiero, Walter Schaffner, and Adriano Fontana. "cDNA cloning of human N-Oct 3, a nervous-system specific POU domain transcription factor binding to the octamer DNA motif." Nucleic Acids Research 21, no. 2 (1993): 253–58. http://dx.doi.org/10.1093/nar/21.2.253.
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Nishimoto, Masazumi, Satoru Miyagi, Toshiyuki Yamagishi, Takehisa Sakaguchi, Hitoshi Niwa, Masami Muramatsu, and Akihiko Okuda. "Oct-3/4 Maintains the Proliferative Embryonic Stem Cell State via Specific Binding to a Variant Octamer Sequence in the Regulatory Region of the UTF1 Locus." Molecular and Cellular Biology 25, no. 12 (June 15, 2005): 5084–94. http://dx.doi.org/10.1128/mcb.25.12.5084-5094.2005.
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ABSTRACT The POU transcription factor Oct-3/4 has been shown to be critical for maintaining embryonic stem (ES) cell character. However, the molecular mechanisms underlying its function remain elusive. We have previously shown that among the POU transcription factor family of proteins, Oct-3/4 alone is able to bind to the regulatory region of the UTF1 gene bearing a variant octamer sequence together with Sox-2. Here, we demonstrate using Oct-3/4-Oct-6 chimeras that there is a precise correlation between the ability of proteins to form a complex on the UTF1 enhancer with Sox-2 and the ability to maintain the stem cell state in ES cells. Different chimeric proteins show differential abilities to form a Sox-2-containing complex on the UTF1 regulatory region, with a decrease in efficiency of the complex formation accompanied by a decrease in the level of UTF1 expression and the rate of cell proliferation. Overexpression of UTF1 in these slow-growing cells was able to restore their proliferation rate to wild-type levels. Moreover, UTF1 was also observed to have an effect on teratoma formation. These results suggest a molecular pathway by which Oct-3/4 induces rapid proliferation and tumorigenic properties of ES cells through activation of the UTF1 gene.
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Kang, S. M., W. Tsang, S. Doll, P. Scherle, H. S. Ko, A. C. Tran, M. J. Lenardo, and L. M. Staudt. "Induction of the POU domain transcription factor Oct-2 during T-cell activation by cognate antigen." Molecular and Cellular Biology 12, no. 7 (July 1992): 3149–54. http://dx.doi.org/10.1128/mcb.12.7.3149.
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Oct-2 is a transcription factor that binds specifically to octamer DNA motifs in the promoters of immunoglobulin and interleukin-2 genes. All tumor cell lines from the B-cell lineage and a few from the T-cell lineage express Oct-2. To address the role of Oct-2 in the T-cell lineage, we studied the expression of Oct-2 mRNA and protein in nontransformed human and mouse T cells. Oct-2 was found in CD4+ and CD8+ T cells prepared from human peripheral blood and in mouse lymph node T cells. In a T-cell clone specific for pigeon cytochrome c in the context of I-Ek, Oct-2 was induced by antigen stimulation, with the increase in Oct-2 protein seen first at 3 h after activation and continuing for at least 24 h. Oct-2 mRNA induction during antigen-driven T-cell activation was blocked by cyclosporin A, as well as by protein synthesis inhibitors. These results suggest that Oct-2 participates in transcriptional regulation during T-cell activation. The relatively delayed kinetics of Oct-2 induction suggests that Oct-2 mediates the changes in gene expression which occur many hours or days following antigen stimulation of T lymphocytes.
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Kang, S. M., W. Tsang, S. Doll, P. Scherle, H. S. Ko, A. C. Tran, M. J. Lenardo, and L. M. Staudt. "Induction of the POU domain transcription factor Oct-2 during T-cell activation by cognate antigen." Molecular and Cellular Biology 12, no. 7 (July 1992): 3149–54. http://dx.doi.org/10.1128/mcb.12.7.3149-3154.1992.
Full textAbstract:
Oct-2 is a transcription factor that binds specifically to octamer DNA motifs in the promoters of immunoglobulin and interleukin-2 genes. All tumor cell lines from the B-cell lineage and a few from the T-cell lineage express Oct-2. To address the role of Oct-2 in the T-cell lineage, we studied the expression of Oct-2 mRNA and protein in nontransformed human and mouse T cells. Oct-2 was found in CD4+ and CD8+ T cells prepared from human peripheral blood and in mouse lymph node T cells. In a T-cell clone specific for pigeon cytochrome c in the context of I-Ek, Oct-2 was induced by antigen stimulation, with the increase in Oct-2 protein seen first at 3 h after activation and continuing for at least 24 h. Oct-2 mRNA induction during antigen-driven T-cell activation was blocked by cyclosporin A, as well as by protein synthesis inhibitors. These results suggest that Oct-2 participates in transcriptional regulation during T-cell activation. The relatively delayed kinetics of Oct-2 induction suggests that Oct-2 mediates the changes in gene expression which occur many hours or days following antigen stimulation of T lymphocytes.
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Pereckova, Jana, Michaela Pekarova, Nikoletta Szamecova, Zuzana Hoferova, Kristyna Kamarytova, Martin Falk, and Tomas Perecko. "Nitro-Oleic Acid Inhibits Stemness Maintenance and Enhances Neural Differentiation of Mouse Embryonic Stem Cells via STAT3 Signaling." International Journal of Molecular Sciences 22, no. 18 (September 15, 2021): 9981. http://dx.doi.org/10.3390/ijms22189981.
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Nitro-oleic acid (NO2-OA), pluripotent cell-signaling mediator, was recently described as a modulator of the signal transducer and activator of transcription 3 (STAT3) activity. In our study, we discovered new aspects of NO2-OA involvement in the regulation of stem cell pluripotency and differentiation. Murine embryonic stem cells (mESC) or mESC-derived embryoid bodies (EBs) were exposed to NO2-OA or oleic acid (OA) for selected time periods. Our results showed that NO2-OA but not OA caused the loss of pluripotency of mESC cultivated in leukemia inhibitory factor (LIF) rich medium via the decrease of pluripotency markers (NANOG, sex-determining region Y-box 1 transcription factor (SOX2), and octamer-binding transcription factor 4 (OCT4)). The effects of NO2-OA on mESC correlated with reduced phosphorylation of STAT3. Subsequent differentiation led to an increase of the ectodermal marker orthodenticle homolog 2 (Otx2). Similarly, treatment of mESC-derived EBs by NO2-OA resulted in the up-regulation of both neural markers Nestin and β-Tubulin class III (Tubb3). Interestingly, the expression of cardiac-specific genes and beating of EBs were significantly decreased. In conclusion, NO2-OA is able to modulate pluripotency of mESC via the regulation of STAT3 phosphorylation. Further, it attenuates cardiac differentiation on the one hand, and on the other hand, it directs mESC into neural fate.
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Fang, Wenjia, Meilin Ni, Mingming Zhang, and Hanqing Chen. "Prognostic value of OCT4 in colorectal cancer: analysis using immunohistochemistry and bioinformatics validation." Biomarkers in Medicine 14, no. 15 (October 2020): 1473–84. http://dx.doi.org/10.2217/bmm-2020-0069.
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Aim: This study was first performed to investigate the role of octamer-binding transcription factor 4 (OCT4) in colorectal cancer (CRC). Methods: The electronic databases were searched for the eligible studies. Odds ratios and hazard ratios were calculated. Functional analysis of OCT4 was examined. Results: Eight studies with 1480 CRC cases were identified. OCT4 expression was correlated with advanced clinical stage, tumor grade, lymph node metastasis, lymphatic invasion, and distal metastasis. OCT4 was an independent prognostic biomarker for predicting worse disease-specific survival and overall survival in CRC. The functional analyses demonstrated that OCT4 was involved in multiple functions, such as cell adhesion, phosphoinositide 3-kinase/Akt signaling, and regulating pluripotency of stem cells. Conclusion: OCT4 may be correlated with disease progression and metastasis, and could predict prognosis in CRC.
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Ko, Young, Trojan Rugira, Hana Jin, Sang Park, and Hye Kim. "Oleandrin and Its Derivative Odoroside A, Both Cardiac Glycosides, Exhibit Anticancer Effects by Inhibiting Invasion via Suppressing the STAT-3 Signaling Pathway." International Journal of Molecular Sciences 19, no. 11 (October 26, 2018): 3350. http://dx.doi.org/10.3390/ijms19113350.
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The cardiac glycosides oleandrin and odoroside A, polyphenolic monomer compounds extracted from Nerium oleander, have been found to have antitumor effects on various tumors at low doses. However, the mechanisms of anticancer effects of oleandrin and odoroside A are not well known. Therefore, in this study, we aimed to investigate the anticancer effects of oleandrin and odoroside A and their associated mechanisms in highly metastatic MDA-MB-231 breast cancer cells and radiotherapy-resistant (RT-R) MDA-MB-231 cells. Our results showed that oleandrin and odoroside A dose-dependently decreased the colony formation and the invasion of both cell lines at nanomolar ranges. Furthermore, oleandrin (50 nM) and odoroside A (100 nM) reduced octamer-binding transcription factor 3/4 (OCT3/4) and β-catenin levels and matrix metalloproteinase-9 (MMP-9) activity. Finally, we found that phospho-STAT-3 levels were increased in MDA-MB-231 and RT-R-MDA-MB-231, but not in endothelial cells (ECs), and that the levels were significantly decreased by oleandrin (50 nM) and odoroside A (100 nM). Inhibition of phospho-signal transducer and activator of transcription (STAT)-3 significantly reduced OCT3/4 and β-catenin levels and MMP-9 activity, ultimately resulting in reduced invasion. These results suggest that the anticancer effects of oleandrin and odoroside A might be due to the inhibition of invasion through of phospho-STAT-3-mediated pathways that are involved in the regulation of invasion-related molecules.
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Pai, Shin, Oluwaseun Adebayo Bamodu, Yen-Kuang Lin, Chun-Shu Lin, Pei-Yi Chu, Ming-Hsien Chien, Liang-Shun Wang, Michael Hsiao, Chi-Tai Yeh, and Jo-Ting Tsai. "CD47-SIRPα Signaling Induces Epithelial-Mesenchymal Transition and Cancer Stemness and Links to a Poor Prognosis in Patients with Oral Squamous Cell Carcinoma." Cells 8, no. 12 (December 17, 2019): 1658. http://dx.doi.org/10.3390/cells8121658.
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Background: Oral squamous cell carcinoma (OSCC), with high mortality rates, is one of the most diagnosed head and neck cancers. Epithelial-to-mesenchymal transition (EMT) and the generation of cancer stem cells (CSCs) are two keys for therapy-resistance, relapse, and distant metastasis. Accumulating evidence indicates that aberrantly expressed cluster of differentiation (CD)47 is associated with cell-death evasion and metastasis; however, the role of CD47 in the generation of CSCs in OSCC is not clear. Methods: We investigated the functional roles of CD47 in OSCC cell lines SAS, TW2.6, HSC-3, and FaDu using the bioinformatics approach, immunoblotting, immunofluorescence staining, and assays for cellular migration, invasion, colony, and orosphere formation, as well as radiosensitivity. Results: We demonstrated increased expression of CD47 in OSCC patients was associated with an estimated poorly survival disadvantage (p = 0.0391) and positively correlated with the expression of pluripotency factors. Silencing CD47 significantly suppressed cell viability and orosphere formation, accompanied by a downregulated expression of CD133, SRY-Box transcription factor 2 (SOX2), octamer-binding transcription factor 4 (OCT4), and c-Myc. In addition, CD47-silenced OSCC cells showed reduced EMT, migration, and clonogenicity reflected by increased E-cadherin and decreased vimentin, Slug, Snail, and N-cadherin expression. Conclusion: Of therapeutic relevance, CD47 knockdown enhanced the anti-OSCC effect of radiotherapy. Collectively, we showed an increased CD47 expression promoted the generation of CSCs and malignant OSCC phenotypes. Silencing CD47, in combination with radiation, could provide an alternative and improved therapeutic efficacy for OSCC patients.
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Huang, Xian-Ju, Xueshan Ma, Xuguang Wang, Xiaolong Zhou, Juan Li, Shao-Chen Sun, and Honglin Liu. "Involvement of G9A-like protein (GLP) in the development of mouse preimplantation embryos in vitro." Reproduction, Fertility and Development 28, no. 11 (2016): 1733. http://dx.doi.org/10.1071/rd14341.
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G9A-like protein (GLP) plays an important role in mouse early embryonic development. Glp-deficient embryos exhibit severe growth retardation and defects that lead to lethality at approximately Embryonic Day 9.5. In the present study we investigated the effect of microinjection of Glp-specific short interference (si) RNA into mouse zygotes on in vitro embryonic development. Knockdown of Glp induced abnormal embryonic development and reduced blastocyst formation. Expression of the pluripotency markers octamer-binding transcription factor 4 (Oct4), SRY (sex determining region Y)-box 2 (Sox2) and Nanog was also significantly decreased in Glp-deficient embryos. The apoptotic index and expression of two pro-apoptotic genes, namely Caspase 3 and Caspase 9, were increased in Glp-deficient embryos. Moreover, methylation levels of dimethylated H3K9 (H3K9me2) were decreased in Glp-knockdown embryos. In conclusion, the results of the present study suggest that Glp deficiency suppresses H3K9me2 modification and hinders mouse embryo development in vitro.
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Hosoe, Misa, Tadashi Furusawa, Ken-Go Hayashi, Toru Takahashi, Yutaka Hashiyada, Keiichiro Kizaki, Kazuyoshi Hashizume, Tomoyuki Tokunaga, Shuichi Matsuyama, and Ryosuke Sakumoto. "Characterisation of bovine embryos following prolonged culture in embryonic stem cell medium containing leukaemia inhibitory factor." Reproduction, Fertility and Development 31, no. 6 (2019): 1157. http://dx.doi.org/10.1071/rd18343.
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In order to help elucidate the process of epiblast and trophoblast cell differentiation in bovine embryos invitro, we attempted to develop a suitable culture medium to allow extended embryo culture. Day 7 bovine blastocysts developed in conventional medium were cultured further in embryonic stem cell medium with or without leukaemia inhibitory factor (LIF) until Day 23. At Day 14, the expression of octamer-binding transcription factor 3/4 (OCT3/4) and VIMENTIN was significantly higher in embryos cultured with than without LIF, but embryonic disc formation was not observed. Although expression of SRY (sex determining region Y)-box 17 (SOX17) mRNA was significantly lower in Day 14 embryos cultured with and without LIF than in invivo embryos, hypoblast cells formed just inside the trophoblast cells of the invitro-cultured embryos. On Day 23, expression of placental lactogen (PL) and prolactin-related protein 1 (PRP1) was not affected by LIF in invitro-cultured embryos, levels of both genes were significantly lower in the invitro than invivo embryos. Similar to invivo embryos, binucleate cell clusters seen in Day 23invitro-cultured embryos were composed of PL-negative and -positive cells. These results suggest that our culture system partially reproduced the differentiation process of trophoblast cells invivo.
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Safitri, Erma. "Effect of low oxygen tension on transcriptional factor OCT4 and SOX2 expression in New Zealand rabbit bone marrow-derived mesenchymal stem cells." November-2020 13, no. 11 (2020): 2469–76. http://dx.doi.org/10.14202/vetworld.2020.2469-2476.
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Background and Aim: Octamer-binding transcription factor 4 (OCT4) and sex-determining region Y-box 2 (SOX2) are transcription factors whose functions are essential to maintain the pluripotency of embryonic stem cells. The purpose of this study was to derive stem cells for in vitro culture and to maintain their viability and pluripotency, with the goal to obtain a cell line for transplantation in patients with degenerative diseases or injuries. This research focused on examining the effect of low oxygen tension on the ability of bone marrow-derived mesenchymal stem cells (BM-MSCs) to express OCT4 and SOX2 in vitro. Materials and Methods: BM-MSCs were obtained from femurs of 2000 to 3000 g New Zealand male rabbits. BM-MSCs were divided into three groups to test different culture conditions: A control group under hyperoxia condition (21% O2) and two treatment groups with low oxygen tension (1% and 3% O2). We characterized the BM-MSCs using flow cytometric measurement of cluster differentiation 44 (CD44) and cluster differentiation 90 (CD90) expression. The expression of OCT4 and SOX2 was measured by immunofluorescence staining after 48 h of incubation in chambers with normal or low oxygen tension with controlled internal atmosphere consisting of 95% N2, 5% CO2, and 1% O2 (T1) and 3% O2 (T2). We considered OCT4 and SOX2 as two markers of pluripotency induction. All immunofluorescence data were subjected to a post hoc normality Tukey's honestly significant difference test; all differences with p<5% were considered significant. Results: BM-MSCs were positive for CD44 and CD90 expression after isolation. Oxygen tension culture conditions of 1% and 3% O2 led to OCT4 and SOX2 expression on culture days 2 and 4 (p<0.05), respectively, as compared to the hyperoxia condition (21% O2). Conclusion: Based on the OCT4 and SOX2 immunofluorescence data, we conclude that the stem cells were pluripotent at low O2 tension (at 1% O2 on day 2 and at 3% O2 on day 4), whereas under 21% O2 the OCT4 and SOX2 were not expressed.
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Gottesfeld, J. M. "DNA sequence-directed nucleosome reconstitution on 5S RNA genes of Xenopus laevis." Molecular and Cellular Biology 7, no. 5 (May 1987): 1612–22. http://dx.doi.org/10.1128/mcb.7.5.1612.
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Nucleosomes were reconstituted in vitro with several singly end-labeled restriction fragments derived from a cloned somatic-type 5S RNA gene of Xenopus laevis and purified nucleosome core particles from Xenopus cultured cells or chicken erythrocytes. Nucleosome locations were determined by digestion of the reconstitutes with exonuclease III and DNase I and were the same for all fragments investigated, extending from 20 base pairs (bp) within the 5S gene to 80 bp beyond the 3' end of the gene. Both core particles and crude nuclear extracts gave equivalent results, suggesting that no factors other than the core histones are responsible for recognition of DNA sequence during reconstitution. The histone octamer and the 5S gene-specific transcription factor TFIIIA both bind to the same region and face of 5S DNA, and nucleosome reconstitution on the 5S gene excluded binding of TFIIIA. The helical repeat of somatic-type 5S DNA in solution was measured by the band shift method and was 10.5 to 10.6 bp per turn over the region of the TFIIIA-binding site. The difference in helical repeat between DNA in solution and on the surface of the nucleosome (10.0-bp spacing between DNase I cutting sites) may explain the linking number paradox.
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Gottesfeld, J. M. "DNA sequence-directed nucleosome reconstitution on 5S RNA genes of Xenopus laevis." Molecular and Cellular Biology 7, no. 5 (May 1987): 1612–22. http://dx.doi.org/10.1128/mcb.7.5.1612-1622.1987.
Full textAbstract:
Nucleosomes were reconstituted in vitro with several singly end-labeled restriction fragments derived from a cloned somatic-type 5S RNA gene of Xenopus laevis and purified nucleosome core particles from Xenopus cultured cells or chicken erythrocytes. Nucleosome locations were determined by digestion of the reconstitutes with exonuclease III and DNase I and were the same for all fragments investigated, extending from 20 base pairs (bp) within the 5S gene to 80 bp beyond the 3' end of the gene. Both core particles and crude nuclear extracts gave equivalent results, suggesting that no factors other than the core histones are responsible for recognition of DNA sequence during reconstitution. The histone octamer and the 5S gene-specific transcription factor TFIIIA both bind to the same region and face of 5S DNA, and nucleosome reconstitution on the 5S gene excluded binding of TFIIIA. The helical repeat of somatic-type 5S DNA in solution was measured by the band shift method and was 10.5 to 10.6 bp per turn over the region of the TFIIIA-binding site. The difference in helical repeat between DNA in solution and on the surface of the nucleosome (10.0-bp spacing between DNase I cutting sites) may explain the linking number paradox.
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Tan, Daisylyn Senna, Yanpu Chen, Ya Gao, Anastasia Bednarz, Yuanjie Wei, Vikas Malik, Derek Hoi-Hang Ho, et al. "Directed Evolution of an Enhanced POU Reprogramming Factor for Cell Fate Engineering." Molecular Biology and Evolution 38, no. 7 (March 15, 2021): 2854–68. http://dx.doi.org/10.1093/molbev/msab075.
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Abstract Transcription factor-driven cell fate engineering in pluripotency induction, transdifferentiation, and forward reprogramming requires efficiency, speed, and maturity for widespread adoption and clinical translation. Here, we used Oct4, Sox2, Klf4, and c-Myc driven pluripotency reprogramming to evaluate methods for enhancing and tailoring cell fate transitions, through directed evolution with iterative screening of pooled mutant libraries and phenotypic selection. We identified an artificially evolved and enhanced POU factor (ePOU) that substantially outperforms wild-type Oct4 in terms of reprogramming speed and efficiency. In contrast to Oct4, not only can ePOU induce pluripotency with Sox2 alone, but it can also do so in the absence of Sox2 in a three-factor ePOU/Klf4/c-Myc cocktail. Biochemical assays combined with genome-wide analyses showed that ePOU possesses a new preference to dimerize on palindromic DNA elements. Yet, the moderate capacity of Oct4 to function as a pioneer factor, its preference to bind octamer DNA and its capability to dimerize with Sox2 and Sox17 proteins remain unchanged in ePOU. Compared with Oct4, ePOU is thermodynamically stabilized and persists longer in reprogramming cells. In consequence, ePOU: 1) differentially activates several genes hitherto not implicated in reprogramming, 2) reveals an unappreciated role of thyrotropin-releasing hormone signaling, and 3) binds a distinct class of retrotransposons. Collectively, these features enable ePOU to accelerate the establishment of the pluripotency network. This demonstrates that the phenotypic selection of novel factor variants from mammalian cells with desired properties is key to advancing cell fate conversions with artificially evolved biomolecules.
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Rosa, Rafael B., Matheus V. Bianchi, Paula R. Ribeiro, Fernando F. Argenta, Andréia Vielmo, Felipe A. B. de Sousa, Manoela M. Piva, et al. "Comparison of immunohistochemical profiles of ovarian germ cells in dysgerminomas of a captive maned wolf and domestic dogs." Journal of Veterinary Diagnostic Investigation 33, no. 4 (May 28, 2021): 772–76. http://dx.doi.org/10.1177/10406387211019959.
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We characterized the immunohistochemical expression profiles of dysgerminomas from a 16-y-old maned wolf and 13 domestic dogs using the following biomarkers: Sal-like protein 4 (SALL4), octamer-binding transcription factor 3/4 (OCT3/4), placental alkaline phosphatase (PLAP), c-kit, and vimentin. The maned wolf had nonspecific and long-standing clinical signs of lethargy, anorexia, and weight loss, and was euthanized because of poor prognosis. At autopsy, the left ovary was effaced by a 12 × 8 × 6 cm mass, comprised of anaplastic cells with a mitotic count of 20 mitoses in 10 high power fields. Dysgerminomas from 7 of 13 domestic dogs had nuclear expression of SALL4. Dysgerminomas from the maned wolf and 2 domestic dogs had both nuclear and cytoplasmic expression of SALL4. Cytoplasmic expression of PLAP and OCT3/4 was present in dysgerminomas from the maned wolf and 3 (PLAP) or 4 (OCT3/4) domestic dogs. All dysgerminomas expressed vimentin. Membranous c-kit expression was rare in the dysgerminoma from the maned wolf, and variable in dysgerminomas from 4 domestic dogs. A dysgerminoma from a domestic dog had cytoplasmic expression of c-kit. SALL4 is a useful marker to confirm germ cell origin of dysgerminoma in canids.
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Tokuzawa, Yoshimi, Eiko Kaiho, Masayoshi Maruyama, Kazutoshi Takahashi, Kaoru Mitsui, Mitsuyo Maeda, Hitoshi Niwa, and Shinya Yamanaka. "Fbx15 Is a Novel Target of Oct3/4 but Is Dispensable for Embryonic Stem Cell Self-Renewal and Mouse Development." Molecular and Cellular Biology 23, no. 8 (April 15, 2003): 2699–708. http://dx.doi.org/10.1128/mcb.23.8.2699-2708.2003.
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ABSTRACT Embryonic stem (ES) cells are immortal and pluripotent cells derived from early mammalian embryos. Transcription factor Oct3/4 is essential for self-renewal of ES cells and early mouse development. However, only a few Oct3/4 target genes have been identified. In this study, we found that F-box-containing protein Fbx15 was expressed predominantly in mouse undifferentiated ES cells. Inactivation of Oct3/4 in ES cells led to rapid extinction of Fbx15 expression. Reporter gene analyses demonstrated that this ES cell-specific expression required an 18-bp enhancer element located approximately 500 nucleotides upstream from the transcription initiation site. The enhancer contained an octamer-like motif and an adjacent Sox-binding motif. Deletion or point mutation of either motif abolished the enhancer activity. The 18-bp fragment became active in NIH 3T3 cells when Oct3/4 and Sox2 were coexpressed. A gel mobility shift assay demonstrated cooperative binding of Oct3/4 and Sox2 to the enhancer sequence. In mice having a β-galactosidase gene knocked into the Fbx15 locus, 5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside staining was detected in ES cells, early embryos (two-cell to blastocyst stages), and testis tissue. Despite such specific expression of Fbx15, homozygous mutant mice showed no gross developmental defects and were fertile. Fbx15-null ES cells were normal in morphology, proliferation, and differentiation. These data demonstrate that Fbx15 is a novel target of Oct3/4 but is dispensable for ES cell self-renewal, development, and fertility.
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Malaver-Ortega, L. F., H. Sumer, and P. J. Verma. "210 DEFINING THE MINIMAL PROMOTER REGION OF BOVINE VASA HOMOLOGUE (Bvh) BY IN SILICO ANALYSIS." Reproduction, Fertility and Development 25, no. 1 (2013): 253. http://dx.doi.org/10.1071/rdv25n1ab210.
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The DEAD box polypeptide 4, DDX4 or VASA, is a highly conserved gene that encodes a putative RNA helicase with the motif DEAD (Asp-Glu-Ala-Asp). Although little is known about its role in germ cell genesis, VASA is one of the earliest, specialised markers of primordial germ cell (PGC) specification. Furthermore, this process of specification has been recapitulated to some degree in vitro using embryonic stem cells (ESC) and induced pluripotent stem cells (iPSC) in mice and humans, using VASA expression as one of the criteria for differentiation and sorting of the differentiated cells. In order to establish a system for isolation and tracking of bovine iPSC undergoing germ cell specification, we analysed all regulatory elements in the 5-kb upstream region [RC 5083564–5088564 Bos taurus (Hereford) chromosome 20 genomic scaffold: NW_003104511.1] of the bovine VASA homologue (Bvh) locus, which is thought to be the putative promoter region of Bvh, and in the in vivo validated promoter regions, for the corresponding homologous genes in human and mouse. We performed the analysis using 2 different approaches: at the sequence level, by orthologous promoter alignment of transcription factor (TF) binding sites (TFBS) using DiAling®, and at the functional level, by functional unit analysis (complex model) using Frameworker® (Genomatix, Munich, Germany). The initial DiAling® analysis did not produce similarities between the 3 analysed species. In contrast, using the complex analysis of functional units, we identified 85 single elements common to all 3, and 795, 482, and 129 models composed of 2, 3, and 4 elements, respectively. The number of models was reduced to 3 [M1, M2, and M3 (P = 4.8 × 10–11)] by increasing the number of TF (each model composed of 6 different elements). As a result, members of SOX/SRY-sex/testis determining and related HMG box factor family related with germ cell specification, pluripotent-related factors such as members of the octamer binding protein family, and TFs common to numerous vertebrate genes such as homeobox transcription factors were identified (Table 1). Based on these results, we determined a region of approximate 0.6 kb upstream of the Bvh gene, which encloses a core of TFBS conserved at the functional level between species. We propose that this sequence is the best candidate for driving the expression of reporter genes under Bvh promoter control. Table 1.Six element models
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WANG, Peixiang, Donald R. BRANCH, Meenakshi BALI, Gilbert A. SCHULTZ, Paul E. GOSS, and Tianru JIN. "The POU homeodomain protein OCT3 as a potential transcriptional activator for fibroblast growth factor-4 (FGF-4) in human breast cancer cells." Biochemical Journal 375, no. 1 (October 1, 2003): 199–205. http://dx.doi.org/10.1042/bj20030579.
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The POU (representing a homeodomain protein family of which the founder members are Pit-1, Oct-1/2 and Unc-86) homeodomain protein OCT3/Oct-3 (where OCT stands for octamer-binding protein) is an embryonic transcription factor expressed in oocytes, embryonic stem and embryonic carcinoma cells. We have demonstrated previously that human breast cancer cells regain the ability to express OCT3 mRNA [Jin, Branch, Zhang, Qi, Youngson and Goss (1999) Int. J. Cancer 81, 104–112]. Antibodies against human OCT3 were not available when this study was conducted. By using a human OCT3–glutathione S-transferase fusion protein to affinity purify a polyclonal antibody against the mouse Oct-3, we obtained an antibody that enabled us to detect OCT3 in human breast cancer cells by Western-blot analysis. Thus we have now confirmed that OCT3 is expressed in human breast cancer cells but not in normal human breasts and in three other organs. When breast cancer cell lines were treated with all-trans-retinoic acid, OCT3 expression was repressed, associated with decreased cell proliferation. Although another POU protein Brn-3 has been shown to be a repressor for BRCA1 (breast-cancer susceptibility gene 1), OCT3 does not repress human or mouse BRCA1/Brca-1 promoters. However, OCT3 is capable of activating a fusion promoter containing the fibroblast growth factor-4 (FGF-4) enhancer element. In addition, we documented for the first time that human breast cancer cells express FGF-4 protein, and its expression could be inhibited by all-trans-retinoic acid. Furthermore, overexpressing OCT3 stimulated endogenous FGF-4 expression in MCF7 breast cancer cell line. These observations indicate that OCT3 protein is selectively expressed in human breast cancer cells, and its expression may be implicated in mammary gland tumorigenesis via up-regulating FGF-4 expression.
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Jeon, Ryounghoon, Sungjo Park, Sung-Lim Lee, and Gyu-Jin Rho. "Subpopulations of miniature pig mesenchymal stromal cells with different differentiation potentials differ in the expression of octamer-binding transcription factor 4 and sex determining region Y-box 2." Asian-Australasian Journal of Animal Sciences 33, no. 3 (March 1, 2020): 515–24. http://dx.doi.org/10.5713/ajas.19.0416.
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Objective: Human mesenchymal stromal cells (MSCs) exhibit variable differentiation potential and can be divided accordingly into distinct subpopulations whose ratios vary with donor age. However, it is unknown whether the same is true in pigs. This study investigated MSC subpopulations in miniature pig and compared their characteristics in young (2 to 3 months) and adult (27 to 35 months) pigs.Methods: Osteogenic, chondrogenic, and adipogenic capacity of isolated MSCs was evaluated by von Kossa, Alcian blue, and oil red O staining, respectively. Cell surface antigen expression was determined by flow cytometry. Proliferative capacity was assessed with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Expression of marker genes was detected by quantitative real-time polymerase chain reaction.Results: Porcine MSCs comprised cells with trilineage and bilineage differentiation potential (tMSCs and bMSCs, respectively) and non-differentiating stromal cells (NDSCs). The tMSC and bMSC fractions were smaller in adult than in young pigs (63.0% vs 71.2% and 11.6% vs 24.0%, respectively, p<0.05); NDSCs showed the opposite trend (25.4% vs 4.8%; p<0.05). Subpopulations showed no differences in morphology, cell surface antigen expression, or proliferative capacity, but octamer-binding transcription factor 4 (OCT4) expression was higher in tMSCs than in bMSCs and NDSCs (p<0.05), whereas sex determining region Y-box 2 (SOX2) expression was higher in tMSCs and bMSCs than in NDSCs (p<0.05). Aging had no effect on these trends.Conclusion: Porcine MSCs comprise distinct subpopulations that differ in their differentiation potential and OCT4 and SOX2 expression. Aging does not affect the characteristics of each subpopulation but alters their ratios.
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Certel, K., M. G. Anderson, R. J. Shrigley, and W. A. Johnson. "Distinct variant DNA-binding sites determine cell-specific autoregulated expression of the Drosophila POU domain transcription factor drifter in midline glia or trachea." Molecular and Cellular Biology 16, no. 4 (April 1996): 1813–23. http://dx.doi.org/10.1128/mcb.16.4.1813.
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Transcriptional regulators utilizing the POU domain DNA-binding motif have been shown to form multi-protein complexes dependent on the POU domain itself and its flexible recognition of various octamer sequence elements. We have identified two variant POU domain recognition elements DFRE1 and DFRE2, which are found within a 514-bp autoregulatory enhancer of the Drosophila melanogaster POU domain gene drifter (dfr). Both elements are capable of binding bacterially produced full-length DFR protein with high affinity, although they differ in the 5'-to-3' orientation of POU-specific and POU homeodomain subelements. When placed in dfr loss-of-function genetic backgrounds, all expression of dfr-lacZ fusion genes under control of the autoregulatory enhancer is dependent on DFR activity levels. However, the complete enhancer sequence directs beta-galactosidase expression in only a subset of cells which normally express the endogenous DFR protein, including the middle pair of midline glias of the ventral nerve cord, the oenocyte clusters, and all tracheal cells. In addition, DFRE1 and DFRE2 exhibit separable tissue-specific functions when independently disrupted or deleted. Disruption of DFRE1 function specifically abolishes beta-galactosidase expression in the middle pair of midline glias. Deletion of DFRE causes a specific loss of tracheal expression, leaving oenocyte and midline glia expression intact. These results suggest that dfr cell-specific autoregulation is determined by the context of DFR POU domain binding within the enhancer, which is possibly mediated by the formation of recognition element-specific heteromultimeric complexes containing additional tissue-specific factors.
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Zhan, Jing, Liang-liang Shi, Yan Wang, Bai Wei, and Sheng-li Yang. "In Vivo Study on the Effects of Xiaoaiping on the Stemness of Hepatocellular Carcinoma Cells." Evidence-Based Complementary and Alternative Medicine 2019 (June 23, 2019): 1–10. http://dx.doi.org/10.1155/2019/4738243.
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Aims.The aim of this study was to examine the effects of Xiaoaiping on the stemness of hepatocellular carcinoma (HCC) cellsin vivoand to investigate the underlying molecular mechanism.Methods.A subcutaneous xenograft nude mouse model was established using Hep3B-derived HCC cells. The mice were randomly assigned to the 100 mg/kg Xiaoaiping or 100μL/20 g normal saline (control) groups (n =3/sex/group) for daily intragastric administration for 14 days. The tumor size was closely monitored during the dosing phase. After the treatment period, the tumor tissues were weighed and harvested for mRNA and protein isolation. qPCR and Western blotting were used to evaluate the expression of cancer stemness markers (epithelial cell adhesion molecule [EpCAM], cluster of differentiation [CD13], CD90, aldehyde dehydrogenase 1 [ALDH1], CD44, and CD45), totipotency factors (sex determining region Y-box 2 [Sox2], Nanog, and octamer-binding transcription factor 4 [Oct4]), and genes involved in the Notch, Wnt/β-catenin, Hedgehog, and Hippo signaling pathways.Key Findings.The tumor size and weight were significantly reduced in the nude mice treated with 100 mg/kg Xiaoaiping when compared with the controls. The Xiaoaiping effects on the stemness markers and totipotency factors included decreased expression of EpCAM, CD24, CD47, Sox2, Oct4, and sal-like protein 4 (SALL4), as well as increased expression of CD13 and ALDH1. In addition, Xiaoaiping inhibited the Hippo, Wnt, and Hedgehog signaling pathways.Conclusion.Xiaoaiping significantly inhibited the growth of HCC xenograft in nude mice. These antitumor effects may be mediated by modulating the expression of multiple stemness markers and totipotency factors and inhibition of the Hippo, Wnt, and Hedgehog signaling pathways.