Academic literature on the topic 'TGFbeta pathway'

In C. elegans, the TGFbeta-like type II receptor daf-4 is required for two distinct signaling pathways. In association with the type I receptor daf-1, it functions in the dauer pathway. In addition, it is also required for body size determination and male tail patterning, roles which do not require daf-1. In an effort to determine how two different signals are transmitted through daf-4, we looked for other potential signaling partners for DAF-4. We have cloned and characterized a novel type I receptor and show that it is encoded by sma-6. Mutations in sma-6 generate the reduced body size (Sma) and abnormal mail tail (Mab) phenotypes identical to those observed in daf-4 and sma-2, sma-3, sma-4 mutants (C. elegans Smads), indicating that they function in a common signaling pathway. However, mutations in sma-6, sma-2, sma-3, or sma-4 do not produce constitutive dauers, which demonstrates that the unique biological functions of daf-4 are mediated by distinct type I receptors functioning in parallel pathways. We propose that the C. elegans model for TGFbeta-like signaling, in which distinct type I receptors determine specificity, may be a general mechanism of achieving specificity in other organisms. These findings distinguish between the manner in which signaling specificity is achieved in TGFbeta-like pathways and receptor tyrosine-kinase (RTK) pathways.

Abstract Pluripotent stem cells derived from patients, including embryonic stem (ES) cells and “induced pluripotent stem” (iPS) cells, are a promising area of regenerative medical research. A major roadblock toward human clinical therapies using ES cells or iPS cells is to define the factors that direct ES cell differentiation into lineage specific cells. We previously established a simple and efficient human embryonic stem cell (hESC) differentiation system to generate CD34+/CD31+ progenitor cells that gave rise to hematopoietic and endothelial cells (Nat Biotech.25:317, 2007). To advance potential clinical application and to define the effects of growth factors on hematopoietic and vascular differentiation, we assessed hESC differentiation on human feeder cells in serum-free condition without intermediate embryoid body (EB) formation. We investigated the roles of BMPs, TGFbeta, VEGF, and FGF2 in directing hESC differentiation. Growth factors were added into culture at different time points to test their stage specific roles. Our study demonstrated that BMP proteins, including BMP2, BMP4, and BMP7, but not BMP9, had synergic effects to VEGF and FGF-2 on hESC differentiation to CD34+/CD31+ progenitor cells. BMP4 was essential to initial CD34+/CD31+ cell development, whereas VEGF and FGF2 promoted the differentiation in later stage, suggesting the sequential roles of BMP4, VEGF and FGF2 in directing hESC differentiation to CD34+/CD31+ progenitor cells. TGFbeta or activin promoted hESC differentiation into CD34+/CD31− cells that were unable to give rise to hematopoietic, endothelial, and smooth muscle cells. Furthermore, TGFbeta or activin activated Smad2/3 signaling, and suppressed BMP4-induced CD34+/CD31+ cells. Microarray analysis revealed that BMP4-induced CD34+ cells expressed hematopoietic, endothelial and smooth muscle genes, including GATA2, gamma globins, VE-Cad, KDR, CD31, Tie2, and aortic smooth muscle actin, whereas TGFbeta-induced CD34+ cells expressed pluripotent markers and endoderm markers, including Oct3/4, Sox2, and Nanog, HHEX, GATA6, and FoxA2. Both canonical BMP signaling (Smad1/5/8-dependent) and non-canonical BMP signaling (p38 MAPK and p42 ERK pathway) were activated by BMP4 in hESCs. Dorsomorphin specifically inhibited BMP4-mediated phosphorylation of Smad1/5/8, and blocked hESC differentiation into CD34+/CD31+ cells. In summary, BMPs and TGFbeta regulate distinct populations of CD34+ cells in hESCs. BMP-Smad1/5/8 pathway is critical for hematopoietic and vascular progenitor development.

Abstract Intro: Mutations in TGFbR1, TGFbR2 and SMAD3 are associated with familial thoracic aortic aneurysms and aortic dissections (TAAD). These patients offer an opportunity to study their immune development. Methods: PBMC from TAAD (n=9) and controls (CT, n=8) were analyzed by FACS. Th1 (IFNg) and Th17 (IL17A) were determined with intracellular cytokine staining. Foxp3+ Tregs were detected with anti-Foxp3. CD19+ were analyzed for naive (IgD+CD27-), unswitched (IgD+CD27+) and switched memory (IgD-CD27+). Plasmacytoid (CD303+pDC) and myeloid (CD1c+mDC) were defined within lineage-1 negative population. Results: %CD3-CD16+NK, CD3+CD16+NKT, CD4+, CD8+ and CD4+CD45RA+ in TAAD were similar to HC. Average %CD19+ (20.8vs7.3, p=0.006) and naive B cells (81.3vs66.6, p=0.004) were higher in TAADvsCT. The unswitched were similar but the switched B cells were lower (8.6vs15.5, p=0.01). While the %Tregs were similar, there was a remarkable reduction (1/2-3 folds, p<0.05) in Foxp3 concentration based on median fluorescence intensity of Foxp3 in TAAD. There was a significant reduction of %Th17 (0.14vs0.61, p=0.01), while the Th1 were similar. %pDC (9.4vs24.1, p=0.009) and %mDC (11.4vs17.9, p=0.01) were also lower in TAAD. Conclusions: These results demonstrate the involvement of TGFbeta signaling in B cells, DCs, Th17 and Treg development. Further studies and monitoring of the clinical effects of these immunological perturbations are needed to appreciate the impact of their underlying disease.

Abstract Hepsin (encoded by HPN gene) is a type II transmembrane serine protease, which is commonly overexpressed in carcinomas of prostate and breast. Hepsin protein is known to be stabilized by Ras-MAPK pathway signaling, and downstream, this protease regulates the degradation of extracellular matrix (ECM) components and activates growth factor pathways, including hepatocyte growth factor (HGF) and transforming growth factor beta (TGF beta) pathway. However, the impact of the hepsin-dependent signaling on cell proliferation and tumor growth is not well-understood. Therefore, we sought to clarify the role of hepsin during these events using engineered breast cancer cell lines, Hpn CRISPR knockout mouse model crossed with Wap-Myc breast cancer mouse model, and patient-derived explant cultures (PDEC)s from human breast tumors. We isolated Wap-Myc; Hpn-/- mammary tumor cells and made orthotopic transplantation into syngeneic wild-type recipient mice. The resulting Wap-Myc tumors that lack hepsin had reduced size both in primary and metastatic site compared to tumors derived from Wap-Myc; Hpn+/+ tumor cells. This decrease in growth was accompanied by downregulation in TGF beta and EGFR signaling as well as substantial reduction in total EGFR protein level. We further demonstrated that in 3D culture conditions overexpression of hepsin induced cell proliferation, which was TGF beta 1 and EGFR signaling-dependent, while PDECs treated with hepsin inhibitory antibodies and small molecules had decreased EGFR and TGF beta signaling activity and reduction in proliferation marker expression. Taken together, this study demonstrates a role for hepsin as a regulator of cell proliferation and tumor growth through TGF beta and EGFR pathways and may provide an interesting druggable upstream target to inhibit TGF beta and EGFR pathways in breast cancer. Citation Format: Topi A. Tervonen, Denis Belitškin, Pauliina Munne, Shishir M. Pant, Ilida Suleymanova, Kati Belitškina, Jeroen Pouwels, Juha Klefström. Serine protease hepsin regulates tumor growth via TGFbeta-EGFR signaling axis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 834.

TGFbeta-related factors are critical regulators of vertebrate mesoderm development. However, the signalling cascades required for their function during this developmental process are poorly defined. Tlx-2 is a homeobox gene expressed in the primitive streak of mouse embryos. Exogenous BMP-2 rapidly activates Tlx-2 expression in the epiblast of E6.5 embryos. A Tlx-2 promoter element responds to BMP-2 signals in P19 cells, and this response is mediated by BMP type I receptors and Smad1. These results suggest that Tlx-2 is a downstream target gene for BMP signalling in the primitive streak where BMP-4 and other TGFbeta-related factors are expressed. Furthermore, disruption of Tlx-2 function leads to early embryonic lethality. Similar to BMP4 and ALK3 mutants, the mutant embryos display severe defects in primitive streak and mesoderm formation. These experiments thus define a BMP/Tlx-2 signalling pathway that is required during early mammalian gastrulation.

Gene expression in the pharyngeal muscles of Caenorhabditis elegans is controlled in part by organ-specific signals, which in the myo-2 gene target a short DNA sequence termed the C subelement. To identify genes contributing to these signals, we performed a yeast one-hybrid screen for cDNAs encoding factors that bind the C subelement. One clone recovered was from daf-3, which encodes a Smad most closely related to vertebrate Smad4. We demonstrated that DAF-3 binds C subelement DNA directly and specifically using gel mobility shift and DNase1 protection assays. Mutation of any base in the sequence GTCTG interfered with binding in the gel mobility shift assay, demonstrating that this pentanucleotide is a core recognition sequence for DAF-3 binding. daf-3 is known to promote formation of dauer larvae and this activity is negatively regulated by TGFbeta-like signaling. To determine how daf-3 affects C subelement enhancer activity in vivo, we examined expression a gfp reporter controlled by a concatenated C subelement oligonucleotide in daf-3 mutants and other mutants affecting the TGFbeta-like signaling pathway controlling dauer formation. Our results demonstrate that wild-type daf-3 can repress C subelement enhancer activity during larval development and, like its dauer-promoting activity, daf-3's repressor activity is negatively regulated by TGFbeta-like signaling. We have examined expression of this gfp reporter in dauer larvae and have observed no daf-3-dependent repression of C activity. These results suggest daf-3 directly regulates pharyngeal gene expression during non-dauer development.