Journal articles: 'Vpr extracellulaire'

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Lupescu, Adrian, C. Thomas Bock, Philipp A. Lang, Susanne Aberle, Heike Kaiser, Reinhard Kandolf, and Florian Lang. "Phospholipase A2 Activity-Dependent Stimulation of Ca2+ Entry by Human Parvovirus B19 Capsid Protein VP1." Journal of Virology 80, no. 22 (September 6, 2006): 11370–80. http://dx.doi.org/10.1128/jvi.01041-06.

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ABSTRACT Recent reports demonstrated an association of human parvovirus B19 with inflammatory cardiomyopathy (iCMP), which is accompanied by endothelial dysfunction. As intracellular Ca2+ activity is a key regulator of cell function and participates in mechanisms leading to endothelial dysfunction, the present experiments explored the effects of the B19 capsid proteins VP1 and VP2. A secreted phospholipase A2 (PLA2)-like activity has been located in the VP1 unique region of the B19 minor capsid protein. As PLA2 has recently been shown to activate the store-operated or capacitative Ca2+ channel ICRAC, we analyzed the impact of the viral PLA2 motif on Ca2+ entry. We cloned the VP1 and VP2 genes isolated from a patient suffering from fatal B19 iCMP into eukaryotic expression vectors. We also generated a B19 replication-competent plasmid to demonstrate PLA2 activity under the control of the complete B19 genome. After the transfection of human endothelial cells (HMEC-1), cytosolic Ca2+ activity was determined by utilizing Fura-2 fluorescence. VP1 and VP2 expression did not significantly modify basal cytosolic Ca2+ activity or the decline of cytosolic Ca2+ activity following the removal of extracellular Ca2+. However, expression of VP1 and of the full-length B19 clone, but not of VP2, significantly accelerated the increase of cytosolic Ca2+ activity following the readdition of extracellular Ca2+ in the presence of thapsigargin, indicating an activation of ICRAC. The effect of VP1 was mimicked by the PLA2 product lysophosphatidylcholine and abolished by an inactivating mutation of the PLA2-encoding region of the VP1 gene. Our observations point to the activation of Ca2+ entry by VP1 PLA2 activity, an effect likely participating in the pathophysiology of B19 infection.

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Dieye, Yakhya, Arjan J. W. Hoekman, Florence Clier, Vincent Juillard, Hein J. Boot, and Jean-Christophe Piard. "Ability of Lactococcus lactis To Export Viral Capsid Antigens: a Crucial Step for Development of Live Vaccines." Applied and Environmental Microbiology 69, no. 12 (December 2003): 7281–88. http://dx.doi.org/10.1128/aem.69.12.7281-7288.2003.

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ABSTRACT Thefood grade bacterium Lactococcus lactis is a potential vehicle for protein delivery in the gastrointestinal tract. As a model, we constructed lactococcal strains producing antigens of infectious bursal disease virus (IBDV). IBDV infects chickens and causes depletion of B-lymphoid cells in the bursa of Fabricius and subsequent immunosuppression, morbidity, or acute mortality. The two major IBDV antigens, i.e., VP2 and VP3, that form the viral capsid were expressed and targeted to the cytoplasm, the cell wall, or the extracellular compartment of L. lactis. Whereas VP3 was successfully targeted to the three compartments by the use of relevant expression and export vectors, VP2 was recalcitrant to export, thus confirming the difficulty of translocating naturally nonsecreted proteins across the bacterial membrane. This defect could be partly overcome by fusing VP2 to a naturally secreted protein (the staphylococcal nuclease Nuc) that carried VP2 through the membrane. Lactococcal strains producing Nuc-VP2 and VP3 in various bacterial compartments were administered orally to chickens. The chickens did not develop any detectable immune response against VP2 and VP3 but did exhibit an immune response against Nuc when Nuc-VP2 was anchored to the cell wall of lactococci.

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Sankovich, Sonia E., Daniela Koleski, Jonathan Baell, Barry Matthews, Ahmed A. Azad, and Ian G. Macreadie. "Design and Assay of Inhibitors of HIV-1 Vpr Cell Killing and Growth Arrest Activity Using Microbial Assay Systems." Journal of Biomolecular Screening 3, no. 4 (June 1998): 299–304. http://dx.doi.org/10.1177/108705719800300409.

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Viral protein R (Vpr), one of the accessory gene products encoded by the human immunodeficiency virus type 1 (HIV-1) genome, has a number of functions, including causing a growth arrest of HIV-1-infected cells and possibly the death of uninfected bystander cells. In microbial assay systems, the C-terminal portion of Vpr can cause cell death when added externally, and when expressed in yeast it causes growth arrest. In this study we have sought to obtain inhibitors of the Vpr functions that affect the microbial systems. Our first approach employed peptide display, which identified a number of sequences, including a heptapeptide sequence, GETRAPL, involved in binding to the C-terminus of Vpr. To determine whether GETRAPL could block the extracellular cytocidal activity of Vpr, the heptapeptide was synthesized and found to have some blocking activity in microbial assays. A second approach led to the finding that melittin inhibitors had activity against Vpr extracellular activities. In a third approach, compounds were tested against the Vpr-induced growth arrest. A number of compounds were found to abrogate the growth arrest, and some also inhibited Vpr's extracellular activity.

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Piller, SC. "Effect of extracellular HIV-1 Vpr protein in vitro." Journal of Neurovirology 7, no. 2 (January 2001): 183–84. http://dx.doi.org/10.1080/13550280152058843.

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Huang, VC Bond, M.-B. "Effect of extracellular HIV-1 Vpr protein in vitro." Journal of Neurovirology 7, no. 2 (January 2001): 184–85. http://dx.doi.org/10.1080/13550280152058852.

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Lee, Woonghee, Ronnie O. Frederick, Marco Tonelli, and Ann C. Palmenberg. "Solution NMR Determination of the CDHR3 Rhinovirus-C Binding Domain, EC1." Viruses 13, no. 2 (January 22, 2021): 159. http://dx.doi.org/10.3390/v13020159.

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Cadherin Related Family Member 3 (CDHR3) is the identified and required cellular receptor for all virus isolates in the rhinovirus-C species (RV-C). Cryo-EM determinations recently resolved the atomic structure of RV-C15a, and subsequently, a complex of this virus bound to CDHR3 extracellular domain 1 (EC1), the N-terminal portion of this receptor responsible for virus interactions. The EC1 binds to a hypervariable sequence footprint on the virus surface, near the 3-fold axis of icosahedral symmetry. The key contacts involve discontinuous residues from 3 viral proteins, VP1, VP2 and VP3. That single cryo-EM EC1 structure, however, could not resolve whether the virus-receptor interface was structurally adaptable to accommodate multiple virus sequences. We now report the solution NMR determination of CDHR3 EC1, showing that this protein, in fact, is mostly inflexible, particularly in the virus-binding face. The new, higher resolution dataset identifies 3 cis-Pro residues in important loop regions, where they can influence both rigidity and overall protein conformation. The data also provide clarification about the residues involved in essential calcium ion binding, and a potential CDHR3 surface groove feature that may be involved in native protein interactions with cellular partners.

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Sun, Yingyuan, Kelly Watters, Marchel G. Hill, Qianglin Fang, Yue Liu, Richard J. Kuhn, Thomas Klose, Michael G. Rossmann, and Ann C. Palmenberg. "Cryo-EM structure of rhinovirus C15a bound to its cadherin-related protein 3 receptor." Proceedings of the National Academy of Sciences 117, no. 12 (March 9, 2020): 6784–91. http://dx.doi.org/10.1073/pnas.1921640117.

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Infection byRhinovirus-C(RV-C), a species of PicornaviridaeEnterovirus, is strongly associated with childhood asthma exacerbations. Cellular binding and entry by all RV-C, which trigger these episodes, is mediated by the first extracellular domain (EC1) of cadherin-related protein 3 (CDHR3), a surface cadherin-like protein expressed primarily on the apical surfaces of ciliated airway epithelial cells. Although recombinant EC1 is a potent inhibitor of viral infection, there is no molecular description of this protein or its binding site on RV-C. Here we present cryo-electron microscopy (EM) data resolving the EC1 and EC1+2 domains of human CDHR3 complexed with viral isolate C15a. Structure-suggested residues contributing to required interfaces on both EC1 and C15a were probed and identified by mutagenesis studies with four different RV-C genotypes. In contrast to most other rhinoviruses, which bind intercellular adhesion molecule 1 receptors via a capsid protein VP1-specific fivefold canyon feature, the CDHR3 EC1 contacts C15a, and presumably all RV-Cs, in a unique cohesive footprint near the threefold vertex, encompassing residues primarily from viral protein VP3, but also from VP1 and VP2. The EC1+2 footprint on C15a is similar to that of EC1 alone but shows that steric hindrance imposed by EC2 would likely prevent multiprotein binding by the native receptor at any singular threefold vertex. Definition of the molecular interface between the RV-Cs and their receptors provides new avenues that can be explored for potential antiviral therapies.

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Patel, Charvi A., Muhammad Mukhtar, and Roger J. Pomerantz. "Human Immunodeficiency Virus Type 1 Vpr Induces Apoptosis in Human Neuronal Cells." Journal of Virology 74, no. 20 (October 15, 2000): 9717–26. http://dx.doi.org/10.1128/jvi.74.20.9717-9726.2000.

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ABSTRACT Human immunodeficiency virus type 1 (HIV-1) infection of the central nervous system (CNS) causes AIDS dementia complex (ADC) in certain infected individuals. Recent studies have suggested that patients with ADC have an increased incidence of neuronal apoptosis leading to neuronal dropout. Of note, a higher level of the HIV-1 accessory protein Vpr has been detected in the cerebrospinal fluid of AIDS patients with neurological disorders. Moreover, extracellular Vpr has been shown to form ion channels, leading to cell death of cultured rat hippocampal neurons. Based on these previous findings, we first investigated the apoptotic effects of the HIV-1 Vpr protein on the human neuronal precursor NT2 cell line at a range of concentrations. These studies demonstrated that apoptosis induced by both Vpr and the envelope glycoprotein, gp120, occurred in a dose-dependent manner compared to protein treatment with HIV-1 integrase, maltose binding protein (MBP), and MBP-Vpr in the undifferentiated NT2 cells. For mature, differentiated neurons, apoptosis was also induced in a dose-dependent manner by both Vpr and gp120 at concentrations ranging from 1 to 100 ng/ml, as demonstrated by both the terminal deoxynucleotidyltransferase (Tdt)-mediated dUTP-biotin nick end labeling and Annexin V assays for apoptotic cell death. In order to clarify the intracellular pathways and molecular mechanisms involved in Vpr- and gp120-induced apoptosis in the NT2 cell line and differentiated mature human neurons, we then examined the cellular lysates for caspase-8 activity in these studies. Vpr and gp120 treatments exhibited a potent increase in activation of caspase-8 in both mature neurons and undifferentiated NT2 cells. This suggests that Vpr may be exerting selective cytotoxicity in a neuronal precursor cell line and in mature human neurons through the activation of caspase-8. These data represent a characterization of Vpr-induced apoptosis in human neuronal cells, and suggest that extracellular Vpr, along with other lentiviral proteins, may increase neuronal apoptosis in the CNS. Also, identification of the intracellular activation of caspase-8 in Vpr-induced apoptosis of human neuronal cells may lead to therapeutic approaches which can be used to combat HIV-1-induced neuronal apoptosis in AIDS patients with ADC.

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Ghosh, Abhrajyoti, Krishanu Chakrabarti, and Dhrubajyoti Chattopadhyay. "Cloning of feather-degrading minor extracellular protease from Bacillus cereus DCUW: dissection of the structural domains." Microbiology 155, no. 6 (June 1, 2009): 2049–57. http://dx.doi.org/10.1099/mic.0.027573-0.

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Bacterial extracellular proteases play an important role in cell survival and cell–cell communication. A high-molecular-mass minor extracellular protease (Vpr) from a feather-degrading bacterium, Bacillus cereus DCUW, has been reported by our laboratory. In the present study, we cloned and expressed Vpr in Escherichia coli. Complete nucleotide sequencing of this gene predicted that the protease is a member of the serine protease family, and smart domain analysis revealed that the protease consists of an N-terminal signal sequence for secretion, a subtilisin_N sequence that is a signature for N-terminal processing, a catalytic S_8 peptidase domain, and finally a long C-terminal protease-associated (PA) region containing nine intrinsically disordered subdomains. Four truncated constructs of the Vpr protease were cloned and expressed in E. coli. We found that the catalytic domain (amino acid residues 172–583) is sufficient for protease activity. Maturation of the Vpr protease needed both N-terminal and C-terminal processing. We have demonstrated that the oligomerization property is associated with the C-terminal protease-associated domain and also shown that the substrate-binding specificity to raw feather resides in this domain.

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Mishra, Sasmita, Jyoti P. Mishra, and Ashok Kumar. "Activation of JNK-dependent Pathway Is Required for HIV Viral Protein R-induced Apoptosis in Human Monocytic Cells." Journal of Biological Chemistry 282, no. 7 (December 11, 2006): 4288–300. http://dx.doi.org/10.1074/jbc.m608307200.

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Human immunodeficiency virus (HIV) accessory protein viral protein R (Vpr) plays a key role in virus replication and induces cell cycle arrest and apoptosis in various cell types including T cells and neuronal and tumor cells following infection with Vpr-expressing HIV isolates or exposure to the extracellular Vpr protein. The C-terminal Vpr peptide encompassing amino acids 52–96 (Vpr-(52–96)) is required for exerting the apoptotic effects, whereas the N-terminal Vpr-(1–45) peptide is responsible for virus transcription. We demonstrate that Vpr-(52–96) induced apoptosis in human promonocytic THP-1 cells and primary monocytes through the mitochondrial pathway in a caspase-dependent manner. To understand the regulation of Vpr-induced apoptosis, we investigated the signaling pathways, particularly the MAPKs, and the transcription factors involved. Although both Vpr-(52–96) and Vpr-(1–45) peptides induced phosphorylation of all the three members of the MAPKs, Vpr-(52–96)-activated JNK selectively induced apoptosis in monocytic cells through the mitochondrial pathway as determined by using JNK inhibitors SP60025, dexamethasone, curcumin, and JNK-specific small interfering RNAs. Furthermore Vpr-(52–96)-induced apoptosis was mediated by inhibition of downstream antiapoptotic Bcl2 and c-IAP1 genes whose expression could be restored following pretreatment with JNK-specific inhibitors. Overall the results suggest that Vpr-(52–96)-activated JNK plays a key role in inducing apoptosis through the down-regulation of antiapoptotic Bcl2 and c-IAP1 genes.

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Mortola, Eduardo, Rob Noad, and Polly Roy. "Bluetongue Virus Outer Capsid Proteins Are Sufficient To Trigger Apoptosis in Mammalian Cells." Journal of Virology 78, no. 6 (March 15, 2004): 2875–83. http://dx.doi.org/10.1128/jvi.78.6.2875-2883.2004.

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ABSTRACT Bluetongue virus (BTV) is transmitted by Culicoides sp. biting midges to livestock, causing severe hemorrhagic disease in sheep, but is asymptomatic in the insect host. Similarly, BTV causes rapid cell death in infected mammalian cells in culture, whereas infections of insect cells are long-term and unapparent, despite productive virus replication. To assess whether apoptosis plays any role in these two distinct cell responses, we have investigated apoptosis in cultured insect and mammalian cells. Three different mammalian cell lines and three different insect cell lines including Culicoides variipennis (KC) cells were infected with BTV serotype 10, and the key apoptosis indicators of cell morphology, chromosomal DNA fragmentation, and caspase-3 activation were monitored. BTV infection induced apoptosis with the activation of the transcription factor nuclear factor κB (NF-κB) in all three mammalian cell lines. In contrast, no evidence for apoptosis was detected in any of the three insect cell lines in response to BTV infection. Using inhibitors of endosomal acidification and UV-inactivated virus, we established that virus uncoating, but not productive virus replication, is necessary for BTV to trigger apoptosis in mammalian cells. Intracellular expression of the viral outer capsid proteins VP2 and VP5 or the two major nonstructural proteins NS1 and NS2 was not sufficient to trigger an apoptotic response. However, extracellular treatment with a combination of purified recombinant VP2 and VP5, but not with each protein used separately, resulted in an apoptotic response. Virus- and VP2-VP5-stimulated apoptotic responses were both inhibited by inhibitors of endosomal acidification. Thus, for BTV the viral outer capsid proteins alone are sufficient to trigger apoptosis.

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Barbieri, Giulia, Birgit Voigt, Dirk Albrecht, Michael Hecker, Alessandra M. Albertini, Abraham L. Sonenshein, Eugenio Ferrari, and Boris R. Belitsky. "CodY Regulates Expression of the Bacillus subtilis Extracellular Proteases Vpr and Mpr." Journal of Bacteriology 197, no. 8 (February 9, 2015): 1423–32. http://dx.doi.org/10.1128/jb.02588-14.

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ABSTRACTCodY is a global transcriptional regulator in low-G+C Gram-positive bacteria that is responsive to GTP and branched-chain amino acids. By interacting with its two cofactors, it is able to sense the nutritional and energetic status of the cell and respond by regulating expression of adaptive genetic programs. InBacillus subtilis, more than 200 genes, including those for peptide transporters, intracellular proteolytic enzymes, and amino acid degradative pathways, are controlled by CodY. In this study, we demonstrated that expression of two extracellular proteases, Vpr and Mpr, is negatively controlled by CodY. By gel mobility shift and DNase I footprinting assays, we showed that CodY binds to the regulatory regions of both genes, in the vicinity of their transcription start points. Themprgene is also characterized by the presence of a second, higher-affinity CodY-binding site located at the beginning of its coding sequence. Using strains carryingvpr- ormpr-lacZtranscriptional fusions in which CodY-binding sites were mutated, we demonstrated that repression of both protease genes is due to the direct effect by CodY and that themprinternal site is required for regulation. Thevprpromoter is a rare example of a sigma H-dependent promoter that is regulated by CodY. In acodYnull mutant, Vpr became one of the more abundant proteins of theB. subtilisexoproteome.IMPORTANCECodY is a global transcriptional regulator of metabolism and virulence in low-G+C Gram-positive bacteria. InB. subtilis, more than 200 genes, including those for peptide transporters, intracellular proteolytic enzymes, and amino acid degradative pathways, are controlled by CodY. However, no role forB. subtilisCodY in regulating expression of extracellular proteases has been established to date. In this work, we demonstrate that by binding to the regulatory regions of the corresponding genes,B. subtilisCodY negatively controls expression of Vpr and Mpr, two extracellular proteases. Thus, inB. subtilis, CodY can now be seen to regulate the entire protein utilization pathway.

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Lobanov, Vladislav A., Sheryl L. Maher-Sturgess, Marlene G. Snider, Zoe Lawman, Lorne A. Babiuk, and Sylvia van Drunen Littel-van den Hurk. "A UL47 Gene Deletion Mutant of Bovine Herpesvirus Type 1 Exhibits Impaired Growth in Cell Culture and Lack of Virulence in Cattle." Journal of Virology 84, no. 1 (October 28, 2009): 445–58. http://dx.doi.org/10.1128/jvi.01544-09.

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ABSTRACT Tegument protein VP8 encoded by the UL47 gene of bovine herpesvirus type 1 (BHV-1) is the most abundant constituent of mature virions. In the present report, we describe the characterization of UL47 gene-deleted BHV-1 in cultured cells and its natural host. The UL47 deletion mutant exhibited reduced plaque size and more than 100-fold decrease in intracellular and extracellular viral titers in cultured cells. Ultrastructural observations of infected cells showed normal maturation of BHV-1 virions in the absence of VP8. There was no evidence for a change in immediate-early gene activator function of VP16 in the UL47 deletion mutant virus-infected cells, since bovine ICP4 mRNA and protein levels were similar to those in the wild-type and revertant virus-infected cells throughout the course of infection. Whereas VP16, glycoprotein C (gC), gB, and VP5 were expressed to wild-type levels in the UL47 deletion mutant-infected cells, the gD and VP22 protein levels were significantly reduced. The reduction in gD protein was associated with increased turnover of the protein. Furthermore, some of the analyzed early and late proteins were expressed with earlier kinetics in the absence of VP8. Extracellular virions of the UL47 deletion mutant contained reduced amounts of gD, gB, gC, and VP22 but similar amounts of VP16 compared to those of wild-type or revertant virus particles. In addition, the UL47 gene product was indispensable for BHV-1 replication in vivo, since no clinical manifestations or viral shedding were detected in the UL47 deletion mutant-infected calves, and the virus failed to induce significant levels of humoral and cellular immunity.

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Monedero, Vicente, JesÃ¯Â¿Â½s RodrÃ¯Â¿Â½guez-DÃ¯Â¿Â½az, Rosa Viana, Javier Buesa, and Gaspar PÃ¯Â¿Â½rez-MartÃ¯Â¿Â½nez. "Selection of Single-Chain Antibodies against the VP8* Subunit of Rotavirus VP4 Outer Capsid Protein and Their Expression in Lactobacillus casei." Applied and Environmental Microbiology 70, no. 11 (November 2004): 6936–39. http://dx.doi.org/10.1128/aem.70.11.6936-6939.2004.

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ABSTRACT Single-chain antibodies (scFv) recognizing the VP8* fraction of rotavirus outer capsid and blocking rotavirus infection in vitro were isolated by phage display. Vectors for the extracellular expression in Lactobacillus casei of one of the scFv were constructed. L. casei was able to secrete active scFv to the growth medium, showing the potential of probiotic bacteria to be engineered to express molecules suitable for in vivo antirotavirus therapies.

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Ponce-Hornos, J. E., E. A. Musi, and P. Bonazzola. "Role of extracellular calcium on heart muscle energetics: effects of verapamil." American Journal of Physiology-Heart and Circulatory Physiology 258, no. 1 (January 1, 1990): H64—H72. http://dx.doi.org/10.1152/ajpheart.1990.258.1.h64.

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The mechanical and energetic effects of verapamil (VER) and reduction of extracellular Ca concentration ([Ca]o) were studied in the interventricular rabbit septa and the dog papillary muscle. Even though the negative inotropic effects of VER [i.e., decrease in developed tension (T), maximal rates of contraction (+T) and relaxation (-T), and tension time integral] qualitatively resemble [Ca]o reduction, VER also elicited an anti-relaxant effect (decrease in -T/T and prolongation of the last phase of relaxation) that was not found with [Ca]o reduction. Resting heat production was similar in both preparations and remained unaffected either by changes in [Ca]o or by the presence of VER. The ratio between T and active heat production per beat (H'a) under constant fiber length decreased with VER, and this decreased economy of contraction was more marked with the increase in contraction frequency. Conversely, the T/H'a remained unaltered with changes in [Ca]o. Tension-independent heat decreased in the presence of VER and, although muscle economy can be improved by increasing muscle length in a VER-treated muscle, it is not possible to achieve either the maximal T or the maximal contraction economy that can be obtained by stretching a nontreated muscle. It may be concluded that at constant fiber length and frequency of contraction VER decreases myocardial contractile force, impairs relaxation, and decreases contraction economy. Neither the mechanical nor the energetic effects of VER can be explained solely on the basis of a reduced extracellular Ca availability, so that either the density of the Ca that enters through the channel is different from that of other sources of Ca or VER has an effect on the cross-bridge cycling mechanism.

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Kulkosky, Joseph, Alexey Laptev, Shubhra Shetty, Alagarsamy Srinivasan, Mohamad BouHamdan, Darwin J. Prockop, and Roger J. Pomerantz. "Human Immunodeficiency Virus Type 1 Vpr Alters Bone Marrow Cell Function." Blood 93, no. 6 (March 15, 1999): 1906–15. http://dx.doi.org/10.1182/blood.v93.6.1906.406k11_1906_1915.

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Vpr, a 96 amino acid protein, encoded by the human immunodeficiency virus type I (HIV-1), is important for efficient infection of mononuclear phagocytic cells. These cells are abundant in whole bone marrow, which can easily be cultured in vitro to support hematopoiesis. Our experiments indicate that Vpr plays a role in the potent activation of murine and human mononuclear phagocytic cells within a hematopoietic microenvironment. In murine cultures, avid erythrophagocytosis is triggered by transduction of marrow cells with supernatant derived from PA317 cells transfected with a murine retroviral delivery vector bearing a Vpr expression cassette. Supernatants derived from cells transfected with the same vector carrying sequences for the expression of other relevant viral and nonviral proteins do not induce erythrophagocytosis to any marked degree. The effect on human marrow cells is similar, where treatment promotes adhesion of mononuclear phagocytic cells to culture plates in association with other nucleated and nonnucleated cells that undergo subsequent engulfment. The differential effects of Vpr point and deletion mutants in both marrow culture systems fortify the view that the effect is specific to HIV-1 Vpr. Addition of low molar quantities of purified Vpr to marrow cultures is also capable of promoting cell adhesion and phagocytosis, suggesting that extracellular Vpr is the effector of the phenomenon. Accelerated phagocytosis is a hallmark of promonocyte, monocyte, and macrophage activation and its occurrence within a hematopoietic microenvironment may account for critical in vivo pathogenic features of HIV-1 infection. First, activation of mononuclear phagocytes may promote productive viral infection; and second, premature phagocytosis could provide, at least in part, a molecular explanation for the induction of the idiopathic cytopenias that are typical of individuals infected with HIV-1.

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Kho, Chang Won, Sung Goo Park, Sayeon Cho, Do Hee Lee, Pyung Keun Myung, and Byoung Chul Park. "Confirmation of Vpr as a fibrinolytic enzyme present in extracellular proteins of Bacillus subtilis." Protein Expression and Purification 39, no. 1 (January 2005): 1–7. http://dx.doi.org/10.1016/j.pep.2004.08.008.

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Xiao, Yong, Gang Chen, Jonathan Richard, Nicole Rougeau, Hongshan Li, Nabil G. Seidah, and Éric A. Cohen. "Cell-surface processing of extracellular human immunodeficiency virus type 1 Vpr by proprotein convertases." Virology 372, no. 2 (March 2008): 384–97. http://dx.doi.org/10.1016/j.virol.2007.10.036.

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Corvey, Carsten, Torsten Stein, Stefanie Düsterhus, Michael Karas, and Karl-Dieter Entian. "Activation of subtilin precursors by Bacillus subtilis extracellular serine proteases subtilisin (AprE), WprA, and Vpr." Biochemical and Biophysical Research Communications 304, no. 1 (April 2003): 48–54. http://dx.doi.org/10.1016/s0006-291x(03)00529-1.

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Lainšček, Duško, Lucija Kadunc, Mateja Manček Keber, Iva Hafner Bratkovič, Rok Romih, and Roman Jerala. "Delivery of an Artificial Transcription Regulator dCas9-VPR by Extracellular Vesicles for Therapeutic Gene Activation." ACS Synthetic Biology 7, no. 12 (December 4, 2018): 2715–25. http://dx.doi.org/10.1021/acssynbio.8b00192.

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Choi, Nack-Shick, Dong-Min Chung, Chan-Sun Park, Keug-Hyun Ahn, Joong Su Kim, Jae Jun Song, Seung-Ho Kim, Byung-Dae Yoon, and Min-Soo Kim. "Expression and identification of a minor extracellular fibrinolytic enzyme (Vpr) from Bacillus subtilis KCTC 3014." Biotechnology and Bioprocess Engineering 15, no. 3 (June 2010): 446–52. http://dx.doi.org/10.1007/s12257-009-0191-z.

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Singer, I. I., S. Scott, D. W. Kawka, D. M. Kazazis, J. Gailit, and E. Ruoslahti. "Cell surface distribution of fibronectin and vitronectin receptors depends on substrate composition and extracellular matrix accumulation." Journal of Cell Biology 106, no. 6 (June 1, 1988): 2171–82. http://dx.doi.org/10.1083/jcb.106.6.2171.

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We used antibodies against the alpha subunits of the human fibronectin receptor (FNR) and vitronectin receptor (VNR) to localize simultaneously FNR and VNR at major substrate adhesion sites of fibroblasts and melanoma cells with double-label immunofluorescence microscopy. In early (2-6-h) serum-containing cultures, both FNR and VNR coaccumulated in focal contacts detected by interference reflection microscopy. Under higher resolution immunoscanning electron microscopy, FNR and VNR were also observed to be distributed randomly on the dorsal cell surface. As fibronectin-containing extracellular matrix fibers accumulated beneath the cells at 24 h, FNR became concentrated at contacts with these fibers and was no longer detected at focal contacts. VNR was not observed at matrix contacts but remained strikingly localized in focal contacts of the 24-h cells. Since focal contacts represent the sites of strongest cell-to-substrate adhesion, these results suggest that FNR and VNR together play critical roles in the maintenance of stable contacts between the cell and its substrate. In addition, the accumulation of FNR at extracellular matrix contacts implies that this receptor might also function in the process of cellular migration along fibronectin-containing matrix cables. To define the factors governing accumulation of FNR and VNR at focal contacts, fibroblasts in serum-free media were plated on substrates coated with purified ligands. Fibronectin-coated surfaces fostered accumulation of FNR but not VNR at focal contacts. On vitronectin-coated surfaces, or substrata derivatized with a tridecapeptide containing the cell attachment sequence Arg-Gly-Asp, both FNR and VNR became concentrated at focal contacts. These observations suggest that the availability of ligand is critical to the accumulation of FNR and VNR at focal contacts, and that FNR might also recognize substrate-bound vitronectin.

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Huang, Ming-Bo, Ophelia Weeks, Ling-Jun Zhao, Mary Saltarelli, and Vincent C. Bond. "Effects of extracellular human immunodeficiency virus type 1 Vpr protein in primary rat cortical cell cultures." Journal of Neurovirology 6, no. 3 (January 2000): 202–20. http://dx.doi.org/10.3109/13550280009015823.

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Levy, D. N., Y. Refaeli, and D. B. Weiner. "Extracellular Vpr protein increases cellular permissiveness to human immunodeficiency virus replication and reactivates virus from latency." Journal of virology 69, no. 2 (1995): 1243–52. http://dx.doi.org/10.1128/jvi.69.2.1243-1252.1995.

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Cañadillas, Sagrario, Rocio Canalejo, Maria Encarnacion Rodriguez-Ortiz, Julio Manuel Martinez-Moreno, Jose Carlos Estepa, Rafael Zafra, Jose Perez, et al. "Upregulation of parathyroid VDR expression by extracellular calcium is mediated by ERK1/2-MAPK signaling pathway." American Journal of Physiology-Renal Physiology 298, no. 5 (May 2010): F1197—F1204. http://dx.doi.org/10.1152/ajprenal.00529.2009.

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We have previously demonstrated that the activation of rat parathyroid calcium-sensing receptor (CaSR) upregulates VDR expression in vivo (Garfia B, Cañadillas S, Luque F, Siendones E, Quesada M, Almadén Y, Aguilera-Tejero E, Rodríguez M. J Am Soc Nephrol 13: 2945–2952, 2002; Rodriguez ME, Almaden Y, Cañadillas S, Canalejo A, Siendones E, Lopez I, Aguilera-Tejero E, Martin D, Rodriguez M. Am J Physiol Renal Physiol 292: F1390–F1395, 2007). The present study was designed to characterize the signaling system that mediates the stimulation of parathyroid VDR gene expression by extracellular calcium. Experiments were performed in vitro by the incubation of rat parathyroid glands and in vivo with normal and uremic (Nx) rats receiving injections of CaCl2or EDTA to obtain hypercalcemic or hypocalcemic clamps. A high calcium concentration increased VDR expression. The addition of arachidonic acid (AA) to the low-calcium medium produced an increase in VDR mRNA of the same magnitude as that observed with high calcium. The addition of ionophore to the low-calcium medium also increased VDR mRNA expression. High calcium or the addition of AA to the low-calcium medium induced the activation (phosphorylation) of ERK1/2-MAPK. The specific inhibition of the ERK1/2-MAPK activity prevented the stimulation of VDR expression by high calcium or AA. These results suggest that AA regulates parathyroid VDR gene expression through the activation of the ERK1/2-MAPK. CaSR activation induced the activation of transcription factor Sp1, but not of NF-κB p50 or p65 or activator protein-1. The addition of AA to the low-calcium medium increased specific DNA-binding activity of Sp1 to almost the same level as high calcium, which was prevented by the inhibition of ERK1/2. Furthermore, mithramycin A (a Sp1 inhibitor) prevented the upregulation of VDR mRNA by high calcium. Finally, both sham and Nx hypercalcemic rats showed similar increased levels of VDR mRNA compared with sham and Nx hypocalcemic rats. Our results demonstrate that extracellular calcium stimulates VDR expression in parathyroid glands through the elevation of the cytosolic calcium level and the stimulation of the PLA2-AA-dependent ERK1/2-pathway. Furthermore, the transcription factor Sp1 mediates this effect.

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Ma, Yongsheng, Amy E. Bryant, Dan B. Salmi, Eric McIndoo, and Dennis L. Stevens. "vfr, a Novel Locus Affecting Cysteine Protease Production in Streptococcus pyogenes." Journal of Bacteriology 191, no. 9 (March 6, 2009): 3189–94. http://dx.doi.org/10.1128/jb.01771-08.

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ABSTRACT A gene unique to Streptococcus pyogenes, called vfr, that negatively regulates speB, an important extracellular proteinase, has been identified. Disruption of vfr markedly increased SpeB production in a clinical strain of S. pyogenes and relieved its growth phase dependency. These findings may provide important insights into the pathogenesis of invasive S. pyogenes infections.

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Wang, Xiaoxin X., Tao Jiang, Yan Shen, Hannah Santamaria, Nathaniel Solis, Cynthia Arbeeny, and Moshe Levi. "Vitamin D receptor agonist doxercalciferol modulates dietary fat-induced renal disease and renal lipid metabolism." American Journal of Physiology-Renal Physiology 300, no. 3 (March 2011): F801—F810. http://dx.doi.org/10.1152/ajprenal.00338.2010.

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Diet-induced obesity (DIO) and insulin resistance in mice are associated with proteinuria, renal mesangial expansion, accumulation of extracellular matrix proteins, and activation of oxidative stress, proinflammatory cytokines, profibrotic growth factors, and the sterol regulatory element binding proteins, SREBP-1 and SREBP-2, that mediate increases in fatty acid and cholesterol synthesis. The purpose of the present study was to determine whether treatment of DIO mice with the vitamin D receptor (VDR) agonist doxercalciferol (1α-hydroxyvitamin D2) prevents renal disease. Our results indicate that treatment of DIO mice with the VDR agonist decreases proteinuria, podocyte injury, mesangial expansion, and extracellular matrix protein accumulation. The VDR agonist also decreases macrophage infiltration, oxidative stress, proinflammatory cytokines, and profibrotic growth factors. Furthermore, the VDR agonist also prevents the activation of the renin-angiotensin-aldosterone system including the angiotensin II type 1 receptor and the mineralocorticoid receptor. An additional novel finding of our study is that activation of VDR results in decreased accumulation of neutral lipids (triglycerides and cholesterol) and expression of adipophilin in the kidney by decreasing SREBP-1 and SREBP-2 expression and target enzymes that mediate fatty acid and cholesterol synthesis and increasing expression of the farnesoid X receptor. This study therefore demonstrates multiple novel effects of VDR activation in the kidney which prevent renal manifestations of DIO in the kidney.

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Matulová, Mária, Nadežda Kolarova, and Peter Capek. "AN EXTRACELLULAR GALACTOGLUCOXYLOMANNAN PROTEIN FROM THE YEAST Cryptococcus laurentii VAR. laurentii." Journal of Carbohydrate Chemistry 21, no. 6 (2002): 521–37. http://dx.doi.org/10.1081/car-120016851.

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Pereira, Marita Gimenez, Luis Henrique Souza Guimarães, Rosa Prazeres Melo Furriel, Maria de Lourdes Teixeira de Moraes Polizeli, Hector Francisco Terenzi, and João Atílio Jorge. "Biochemical properties of an extracellular trehalase from Malbranchea pulchella var. Sulfurea." Journal of Microbiology 49, no. 5 (October 2011): 809–15. http://dx.doi.org/10.1007/s12275-011-0532-4.

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Fortier, Pierre A., Gary K. Bedford, and Miguel A. Chiong. "Influence of low extracellular Ca2+ ions on the cardiac function changes induced by verapamil in the perfused rabbit heart." Canadian Journal of Physiology and Pharmacology 63, no. 11 (November 1, 1985): 1429–34. http://dx.doi.org/10.1139/y85-235.

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We tested the hypothesis that the myocardial effects of verapamil (VER) could be enhanced by decreasing the extracellular Ca2+ concentration ([Ca2+]o) in the isolated rabbit heart at 37 °C. After perfusion with standard Krebs–bicarbonate solution containing 1.27 mM Ca2+, for a 30-min period of stabilization and 15 min of control, groups of hearts were perfused for an additional 60 min with solutions containing one of the following: 1.27 mM Ca2+ (control group), 0.23 mM Ca2+ (low [Ca2+]o group), 1.27 mM Ca2+ plus 10− M VER (VER group), or 0.23 mM Ca2+ plus 10−7 M VER (combination, CBN group). These concentrations of [Ca2+]o and VER produce submaximal responses in our preparation. We found that the heart rate – LV pressure product (RPP) in the CBN group fell rapidly to 0 in the first 2–3 min of perfusion, this response being significantly lower than in the other two groups for the first 15 min. Electromechanical dissociation (EMD) appeared in one of six hearts at 60 min and in four of six hearts at 30 min in the low [Ca2+]o and VER groups, respectively, whereas it occurred in the CBN group in all hearts at 3 min. Depolarization rate (DR) fell by 10% in the low [Ca2+]o and VER groups versus a reduction of 45% in the CBN group (P < 0.05) during the last 45 min of perfusion. The PR interval increased by 300% in the CBN group, a much greater and significant change (P < 0.05) than in the hearts exposed to VER or low [Ca2+]o. The QT interval, however, increased by 50% in the low [Ca2+]o group (P < 0.05) and decreased by 20–30% in the VER and CBN groups (P < 0.05). On the other hand there were no differences in the changes in coronary sinus flow, O2 uptake, enzyme release, or energy stores among the groups. We conclude that low [Ca2+]o enhanced the effects of VER in relation only to RPP, DR, PR interval, and possibly EMD, but had no influence on metabolism.

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Si, Yingnan, JiaShiung Guan, Yuanxin Xu, Kai Chen, Seulhee Kim, Lufang Zhou, Renata Jaskula-Sztul, and X. Margaret Liu. "Dual-Targeted Extracellular Vesicles to Facilitate Combined Therapies for Neuroendocrine Cancer Treatment." Pharmaceutics 12, no. 11 (November 11, 2020): 1079. http://dx.doi.org/10.3390/pharmaceutics12111079.

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Neuroendocrine (NE) cancers arise from cells within the neuroendocrine system. Chemotherapies and endoradiotherapy have been developed, but their clinical efficacy is limited. The objective of this study was to develop a dual-targeted extracellular vesicles (EV)-delivered combined therapies to treat NE cancer. Specifically, we produced EV in stirred-tank bioreactors and surface tagged both anti-somatostatin receptor 2 (SSTR 2) monoclonal antibody (mAb) and anti-C-X-C motif chemokine receptor 4 (CXCR4) mAb to generate mAbs-EV. Both live-cell confocal microscopy imaging and In Vivo Imaging System (IVIS) imaging confirmed that mAbs-EV specifically targeted and accumulated in NE cancer cells and NE tumor xenografts. Then the highly potent natural cytotoxic marine compound verrucarin A (Ver-A) with IC50 of 2.2–2.8 nM and microtubule polymerization inhibitor mertansine (DM1) with IC50 of 3.1–4.2 nM were packed into mAbs-EV. The in vivo maximum tolerated dose study performed in non-tumor-bearing mice indicated minimal systemic toxicity of mAbs-EV-Ver-A/DM1. Finally, the in vivo anticancer efficacy study demonstrated that the SSTR2/CXCR4 dual-targeted EV-Ver-A/DM1 is more effective to inhibit NE tumor growth than the single targeting and single drug. The results from this study could expand the application of EV to targeting deliver the combined potent chemotherapies for cancer treatment.

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Umlauf, Benjamin J., Paul A. Clark, Jason M. Lajoie, Julia V. Georgieva, Samantha Bremner, Brantley R. Herrin, John S. Kuo, and Eric V. Shusta. "Identification of variable lymphocyte receptors that can target therapeutics to pathologically exposed brain extracellular matrix." Science Advances 5, no. 5 (May 2019): eaau4245. http://dx.doi.org/10.1126/sciadv.aau4245.

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Diseases that lead to blood-brain barrier (BBB) disruption will pathologically expose normally inaccessible brain extracellular matrix (ECM) to circulating blood components. Therefore, we hypothesized that brain ECM-targeting moieties could specifically target the disrupted BBB and potentially deliver therapies. Variable lymphocyte receptors (VLRs) that preferentially associate with brain ECM were identified from an immune VLR library via yeast surface display biopanning coupled with a moderate throughput ECM screen. Brain ECM binding of VLR clones to murine and human brain tissue sections was confirmed. After systemic administration, P1C10, the lead brain ECM-targeting VLR candidate, specifically accumulated in brains with mannitol-disrupted BBB and at disrupted BBB regions in two different intracranial glioblastoma models. We also demonstrate P1C10’s ability to deliver doxorubicin-loaded liposomes, leading to significantly improved survival in glioblastoma-bearing mice. Thus, VLRs can be used to selectively target pathologically exposed brain ECM and deliver drug payloads.

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O'Connor, Paul M., and Allen W. Cowley. "Vasopressin-induced nitric oxide production in rat inner medullary collecting duct is dependent on V2 receptor activation of the phosphoinositide pathway." American Journal of Physiology-Renal Physiology 293, no. 2 (August 2007): F526—F532. http://dx.doi.org/10.1152/ajprenal.00052.2007.

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We previously reported that arginine vasopressin (AVP) stimulates the production of nitric oxide (NO) in inner medullary collecting duct (IMCD) via activation of V2 receptors (V2R) and the mobilization of intracellular Ca2+. The aim of this study was to determine the pathway(s) through which this response is mediated. IMCDs were dissected from male Sprague-Dawley rats and intracellular Ca2+ concentration ([Ca2+]i) and NO production were measured using a fluorescence imaging system. AVP (100 nmol/l) produced a rapid increase [Ca2+]i of 381 ± 78 nmol/l that was followed by a significant increase of NO production (166 ± 61%). The specific nonpeptide V2R antagonist OPC31260 (1 μM), but not the V1R antagonist OPC21268 (1 μM), inhibited the increase in [Ca2+]i (up to 91 ± 5%) and abolished the NO response to AVP. Both the phospholipase C inhibitor U73112 (3 μM) and the inositol ( 1 , 4 , 5 ) tri-phosphate 3 receptor blocker 2-APB (75 μM) reduced the peak [Ca2+]i response to AVP (by 65 ± 9 and 59 ± 15%, respectively) and abolished the NO response. Although forskolin (100 μM; an activator of adenylyl cyclase) elicited a moderate increase in [Ca2+]i, neither preincubation with the adenylyl cyclase inhibitor 2′-5′-dideoxyadenosine (50 μM) nor the protein kinase A (PKA) inhibitor PKA14-22 (100 μM) significantly inhibited peak [Ca2+]i in response to AVP. IMCD [Ca2+]i responses to AVP were reduced by 72 ± 8% when incubated in Ca2+-free media and could be completely abolished by preincubation with the Ca2+-ATPase inhibitor thapsigargin. We conclude that AVP-induced NO production in IMCD is dependent on V2R activation of the phosphoinositide pathway and the mobilization of Ca2+ from both intracellular and extracellular pools.

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Lanigan-Gerdes, Sara, Alek N. Dooley, Kym F. Faull, and Beth A. Lazazzera. "Identification of subtilisin, Epr and Vpr as enzymes that produce CSF, an extracellular signalling peptide of Bacillus subtilis." Molecular Microbiology 65, no. 5 (September 2007): 1321–33. http://dx.doi.org/10.1111/j.1365-2958.2007.05869.x.

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Chi Mai, Nguyen, Pham Thi Hoe, Vu Huong Giang, Le Quynh Lien, Nguyen Tuong Van, and Tran My Linh. "ISOLATE ENDOPHYTIC FUNGI FROM LOCAL CATHARANTHUS ROSEUS AND ANALYZE THEIR EXTRACELLULAR ENZYME ACTIVITIES." International Journal of Advanced Research 9, no. 5 (May 31, 2021): 702–8. http://dx.doi.org/10.21474/ijar01/12896.

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Endophytic microbia are known as natural sources for producing valuable enzymes. In this study, four endophytic fungi were isolated from roots of local Catharanthus roseus (L.) G. Don var. roseus (purple flower) and C. roseus var. ocellatus (red stamens white flower) widely grown in Nha Trang. They were identified as Fusarium solani RN1, Chaetomium funicola RN3, Penicillium rugulosum RN4 and Chaetomium homopilatum WN1 based on morphologies colonies and spores. The activity analysis of their extracellular enzymes indicted all isolated endophytic fungi are able to produce protease, cellulose, xylanase as well as amylase. This is the first report on the endophytic fungi inhabited in C. roseus plant growing in the coastal regions of Vietnam, which could provide an attractive source for bioactive enzyme exploitation.

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Zhang, Kuan, Robert Brownlie, Marlene Snider, and Sylvia van Drunen Littel-van den Hurk. "Phosphorylation of Bovine Herpesvirus 1 VP8 Plays a Role in Viral DNA Encapsidation and Is Essential for Its Cytoplasmic Localization and Optimal Virion Incorporation." Journal of Virology 90, no. 9 (February 17, 2016): 4427–40. http://dx.doi.org/10.1128/jvi.00219-16.

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ABSTRACTVP8 is a major tegument protein of bovine herpesvirus 1 (BoHV-1) and is essential for viral replication in cattle. The protein undergoes phosphorylation after transcription through cellular casein kinase 2 (CK2) and a viral kinase, US3. In this study, a virus containing a mutated VP8 protein that is not phosphorylated by CK2 and US3 (BoHV-1-YmVP8) was constructed by homologous recombination in mammalian cells. When BoHV-1-YmVP8-infected cells were observed by transmission electron microscopy, blocking phosphorylation of VP8 was found to impair viral DNA encapsidation, resulting in release of incomplete viral particles to the extracellular environment. Consequently, less infectious virus was produced by the mutant virus than by wild-type (WT) virus. A comparison of mutant and WT VP8 by confocal microscopy revealed that mutant VP8 is nuclear throughout infection while WT VP8 is nuclear early during infection and is associated with the Golgi apparatus at later stages. This, together with the observation that mutant VP8 is present in virions, albeit in smaller amounts, suggests that the incorporation of VP8 may occur at two stages. The first takes place without the need for phosphorylation and before or during nuclear egress of capsids, whereas the second occurs in the Golgi apparatus and requires phosphorylation of VP8. The results indicate that phosphorylated VP8 plays a role in viral DNA encapsidation and in the secondary virion incorporation of VP8. To perform these functions, the cellular localization of VP8 is adjusted based on the phosphorylation status.IMPORTANCEIn this study, phosphorylation of VP8 was shown to have a function in BoHV-1 replication. A virus containing a mutated VP8 protein that is not phosphorylated by CK2 and US3 (BoHV-1-YmVP8) produced smaller numbers of infectious virions than wild-type (WT) virus. The maturation and egress of WT and mutant BoHV-1 were studied, showing a process similar to that reported for other alphaherpesviruses. Interestingly, lack of phosphorylation of VP8 by CK2 and US3 resulted in reduced incorporation of viral DNA into capsids during mutant BoHV-1 infection, as well as lower numbers of extracellular virions. Furthermore, mutant VP8 remained nuclear throughout infection, in contrast to WT VP8, which is nuclear at early stages and Golgi apparatus associated late during infection. This correlates with smaller amounts of mutant VP8 in virions and suggests for the first time that VP8 may be assembled into the virions at two stages, with the latter dependent on phosphorylation.

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Moulder, K., K. Roberts, E. M. Shevach, and J. E. Coligan. "The mouse vitronectin receptor is a T cell activation antigen." Journal of Experimental Medicine 173, no. 2 (February 1, 1991): 343–47. http://dx.doi.org/10.1084/jem.173.2.343.

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In this report, we demonstrate that the T cell activation antigen, recognized by monoclonal antibody H9.2B8, is the murine homologue of the vitronectin receptor (VNR) and, thereby, we provide initial evidence that VNR is expressed on lymphoid cells. VNR is expressed on a variety of T cell lines, tumors, and Con A-activated splenocytes, but not resting T cells, and is capable of binding to the extracellular matrix proteins fibronectin, fibrinogen, and vitronectin, via the tripeptide sequence RGD. There was no evidence of novel beta chains pairing with the VNR alpha chain, as has been demonstrated in some human cells. In view of recent studies demonstrating that this molecule functions as an accessory molecule in T cell activation, the VNR may play an important role in mouse T cell functions.

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Jing, Yu-Pu, Xinpeng Wen, Lunjie Li, Shanjing Zhang, Ci Zhang, and Shutang Zhou. "The vitellogenin receptor functionality of the migratory locust depends on its phosphorylation by juvenile hormone." Proceedings of the National Academy of Sciences 118, no. 37 (September 7, 2021): e2106908118. http://dx.doi.org/10.1073/pnas.2106908118.

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Vitellogenin receptor (VgR) plays a pivotal role in ovarian vitellogenin (Vg) uptake and vertical transmission of pathogenic microbes and Wolbachia symbionts. However, the regulatory mechanisms of VgR action as an endocytic receptor and translocation from oocyte cytoplasm to the membrane remain poorly understood. Here, by using the migratory locust Locusta migratoria as a model system, we report that juvenile hormone (JH) promotes VgR phosphorylation at Ser1361 in the second EGF-precursor homology domain. A signaling cascade including GPCR, PLC, extracellular calcium, and PKC-ι is involved in JH-stimulated VgR phosphorylation. This posttranslational regulation is a prerequisite for VgR binding to Vg on the external surface of the oocyte membrane and subsequent VgR/Vg endocytosis. Acidification, a condition in endosomes, induces VgR dephosphorylation along with the dissociation of Vg from VgR. Phosphorylation modification is also required for VgR recycling from oocyte cytoplasm to the membrane. Additionally, VgR phosphorylation and its requirement for Vg uptake and VgR recycling are evolutionarily conserved in other representative insects including the cockroach Periplaneta americana and the cotton bollworm Helicoverpa armigera. This study fills an important knowledge gap of low-density lipoprotein receptors in posttranslational regulation, endocytosis, and intracellular recycling.

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Stammen, Simon, Britta Katrin Müller, Claudia Korneli, Rebekka Biedendieck, Martin Gamer, Ezequiel Franco-Lara, and Dieter Jahn. "High-Yield Intra- and Extracellular Protein Production Using Bacillus megaterium." Applied and Environmental Microbiology 76, no. 12 (April 30, 2010): 4037–46. http://dx.doi.org/10.1128/aem.00431-10.

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ABSTRACT The Bacillus megaterium protein production system based on the inducible promoter of the xyl operon (P xylA ) was systematically optimized. Multiple changes in basic promoter elements, such as the −10 and −35 region and the ribosome-binding site, resulted in an 18-fold increase of protein production compared to the production of the previously established system. The production in shaking-flask culture of green fluorescent protein (Gfp) as a model product led to 82.5 mg per g cell dry weight (gCDW) or 124 mg liter−1. In fed-batch cultivation, the volumetric protein yield was increased 10-fold to 1.25 g liter−1, corresponding to 36.8 mg protein per gCDW. Furthermore, novel signal peptides for Sec-dependent protein secretion were predicted in silico using the B. megaterium genome. Subsequently, leader peptides of Vpr, NprM, YngK, YocH, and a computationally designed artificial peptide were analyzed experimentally for their potential to facilitate the secretion of the heterologous model protein Thermobifida fusca hydrolase (Tfh). The best extracellular protein production, 5,000 to 6,200 U liter−1 (5.3 to 6.6 mg liter−1), was observed for strains where the Tfh export was facilitated by a codon-optimized leader peptide of YngK and by the signal peptide of YocH. Further increases in extracellular protein production were achieved when leader peptides were used in combination with the optimized expression system. In this case, the greatest extracellular enzyme amount of 7,200 U liter−1, 7.7 mg liter−1, was achieved by YocH leader peptide-mediated protein export. Nevertheless, the observed principal limitations in protein export might be related to components of the Sec-dependent protein transport system.

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Davies, J., J. Warwick, N. Totty, R. Philp, M. Helfrich, and M. Horton. "The osteoclast functional antigen, implicated in the regulation of bone resorption, is biochemically related to the vitronectin receptor." Journal of Cell Biology 109, no. 4 (October 1, 1989): 1817–26. http://dx.doi.org/10.1083/jcb.109.4.1817.

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We have defined the structure of the Osteoclast Functional Antigen (OFA) by immunological and biochemical means. OFA is an abundant surface antigen in human and animal osteoclasts and has been characterized previously by monoclonal antibodies 13C2 and 23C6, one of which mimicks the inhibitory activity of calcitonin on osteoclastic bone resorption. By the following criteria we show that OFA is a member of the integrin family of extracellular matrix receptors and is identical, or at least highly related, to the vitronectin receptor (VNR) previously isolated from placenta and melanoma cells. Immunoprecipitation analysis demonstrates that OFA from osteoclasts and a monkey kidney cell line Vero is a heterodimeric molecule of 140 kD (alpha chain) and 85 kD (beta chain) under nonreducing conditions; on reduction at least one low molecular mass (alpha') species (of approximately 30-kD size) is released, resulting in a 120/100-kD dimer. Immunoblots of OFA isolated from osteoclasts and Vero cells and VNR purified from placenta and probed with heterosera to OFA and monoclonal antibodies to platelet gp111a (VNR beta chain) show immunological cross-reactivity between the alpha chains of OFA and VNR and the use of gp111a as a beta chain by both. OFA from Vero cells binds to an Arg-Gly-Asp containing peptide (GRGDSPPK) isolating a heterodimer recognized by anti-OFA monoclonal antibodies, 13C2 and 23C6. Immunohistochemical analysis showed a similar tissue distribution in humans for the antigen recognized by anti-OFA antibodies, a monoclonal antibody, LM142, raised to melanoma VNR, polyclonal antibodies to the placental VNR and a monoclonal antibody to the presumptive VNR beta chain, platelet glycoprotein 111a. Finally, NH2 terminal amino acid sequencing showed that the amino-terminus of the monkey alpha chain was identical in the 12 assigned residues to that of human VNR alpha chain. The beta chain sequence of OFA differed at least 1 (and up to 4) positions from platelet gp111a (VNR beta) in the first 18 amino acids sequenced. These, and other, data provide the first indication of a function for the VNR and suggest that cell-cell and cell-extracellular matrix interactions involving integrins may play an important role in bone physiology.

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Riteau, Béatrice, Christiane de Vaureix, and François Lefèvre. "Trypsin increases pseudorabies virus production through activation of the ERK signalling pathway." Journal of General Virology 87, no. 5 (May 1, 2006): 1109–12. http://dx.doi.org/10.1099/vir.0.81609-0.

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Extracellular proteases that are expressed in primary and secondary foci of viral infection are potentially important mediators of infectious inflammatory processes. For some viruses, such as influenza virus and rotaviruses, proteases such as trypsin enhance infectivity by a direct proteolytic effect on some virion proteins. By using an in vitro model of herpesvirus infection, the possibility that proteases modulate the viral cycle through signalling delivered to the infected cell was investigated. It is reported that exposure of pseudorabies virus-infected cells to trypsin increased virus production. Moreover, this treatment induced synergistic and sustained activation of the extracellular signal-regulated kinase (ERK) 1/2 signalling pathway, which appeared to be necessary for this increased viral production. These results suggest that herpesviruses could take advantage of the inflammatory context and particularly of the presence of proteases to increase their replication. Thus, these data point to a potentially important role of extracellular proteases in herpesvirus infection.

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Yokoyama, K., A. Yamauchi, M. Izumi, T. Itoh, A. Ando, E. Imai, T. Kamada, and N. Ueda. "A low-affinity vasopressin V2-receptor gene in a kindred with X-linked nephrogenic diabetes insipidus." Journal of the American Society of Nephrology 7, no. 3 (March 1996): 410–14. http://dx.doi.org/10.1681/asn.v73410.

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In this study, a mutation in vasopressin Type 2 receptor (V2R) in a patient with hereditary nephrogenic diabetes insipidus (NDI) has been identified and characterized. The sequencing of the V2R gene from the patient revealed that there was a missense mutation (TAT to TGT) resulting in the substitution of 205Tyr for Cys in the putative third extracellular domain. The expression analysis in COS cells showed that the binding affinity of the mutant receptor (KD = 19.8 nM) for arginine vasopressin was much lower than that of the wild-type receptor (KD = 1.8 nM) so that intracellular cAMP production stimulated by arginine vasopressin was impaired in cells with the mutant V2R. From these results, it was concluded that the single amino-acid substitution of V2R is responsible for this familial disease.

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Okeke, C. N., and J. Müller. "Production of extracellular collagenolytic proteinases by Histoplasma capsulatum var. duboisii and Histoplasma capsulatum var. capsulatum in the yeast phase." Mycoses 34, no. 11-12 (April 24, 2009): 453–60. http://dx.doi.org/10.1111/j.1439-0507.1991.tb00860.x.

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McAndrew, Ryan, Rory N. Pruitt, Shizuo G. Kamita, Jose Henrique Pereira, Dipali Majumdar, Bruce D. Hammock, Paul D. Adams, and Pamela C. Ronald. "Structure of the OsSERK2 leucine-rich repeat extracellular domain." Acta Crystallographica Section D Biological Crystallography 70, no. 11 (October 29, 2014): 3080–86. http://dx.doi.org/10.1107/s1399004714021178.

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Somatic embryogenesis receptor kinases (SERKs) are leucine-rich repeat (LRR)-containing integral membrane receptors that are involved in the regulation of development and immune responses in plants. It has recently been shown that rice SERK2 (OsSERK2) is essential for XA21-mediated resistance to the pathogenXanthomonas oryzaepv.oryzae. OsSERK2 is also required for the BRI1-mediated, FLS2-mediated and EFR-mediated responses to brassinosteroids, flagellin and elongation factor Tu (EF-Tu), respectively. Here, crystal structures of the LRR domains of OsSERK2 and a D128N OsSERK2 mutant, expressed as hagfish variable lymphocyte receptor (VLR) fusions, are reported. These structures suggest that the aspartate mutation does not generate any significant conformational change in the protein, but instead leads to an altered interaction with partner receptors.

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Johnson, P. J., S. C. Tyagi, L. C. Katwa, V. K. Ganjam, L. A. Moore, J. M. Kreeger, and N. T. Messer. "Activation of extracellular matrix metalloproteinases in equine laminitis." Veterinary Record 142, no. 15 (April 11, 1998): 392–96. http://dx.doi.org/10.1136/vr.142.15.392.

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Carling, Tobias, Peter Ridefelt, Per Hellman, Jonas Rastad, and Göran Åkerström. "Vitamin D Receptor Polymorphisms Correlate to Parathyroid Cell Function in Primary Hyperparathyroidism1." Journal of Clinical Endocrinology & Metabolism 82, no. 6 (June 1, 1997): 1772–75. http://dx.doi.org/10.1210/jcem.82.6.4012.

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Abstract Calcitriol acts via its receptor (VDR) and inhibits PTH secretion and parathyroid cell proliferation. Increased prevalence of the polymorphic VDR alleles b, a, and T has been demonstrated in sporadic primary hyperparathyroidism. Sixty-two patients with primary hyperparathyroidism due to parathyroid adenoma (mean age, 69.5 ± 1.4 yr) were genotyped for these VDR polymorphisms. Dispersed cells of the adenomas were exposed to increasing concentrations of extracellular Ca2+ and analyzed for PTH release and cytoplasmic Ca2+ concentrations. Ca2+-mediated PTH inhibition exhibited higher ED50 and less suppression in the cells of patients who were homozygous for the b, a, and T alleles (P < 0.05–0.10). When analyzing haplotypes, the patients with baT demonstrated a ED50 of 1.81 ± 0.15 vs. 1.29 ± 0.10 for BAt (P < 0.05). As VDR alleles were unrelated to parathyroid intracellular Ca2+, influences of polymorphic VDR alleles on PTH secretion seem to involve mechanisms other than the Ca2+-sensing protein of the parathyroid cell surface.

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Law, Mansun, Michael Hollinshead, Han-Joo Lee, and Geoffrey L. Smith. "Yaba-like disease virus protein Y144R, a member of the complement control protein family, is present on enveloped virions that are associated with virus-induced actin tails." Journal of General Virology 85, no. 5 (May 1, 2004): 1279–90. http://dx.doi.org/10.1099/vir.0.79863-0.

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Yaba-like disease virus (YLDV) is a yatapoxvirus, a group of slow-growing poxviruses from primates. Analysis of the growth cycle of YLDV in tissue culture showed that maximum virus titres were reached 3 days post-infection and at this time only 3·3 % of infectious progeny was extracellular. The intracellular and extracellular virions have different buoyant densities and are separable on CsCl density gradients. They are also distinguishable by electron microscopy with the extracellular virions having an additional lipid envelope. In YLDV-infected cells, thick actin bundles with virions at their tips were seen protruding from the cell surface, despite the fact that YLDV lacks a protein comparable to Vaccinia virus A36R, which is required for VV-induced actin tail formation. In addition to these observations, the YLDV gene Y144R was characterized. This gene is predicted to encode a transmembrane protein containing three short consensus repeat (SCR) motifs common to members of the complement control protein family. Antibody generated against recombinant Y144R recognized products of 36, 41 and 48–55 kDa in YLDV-infected cells and purified extracellular enveloped virus (EEV) but not intracellular mature virus (IMV). Y144R protein is a glycoprotein with type I membrane topology that is synthesized early and late during infection. By immunoblot, indirect immunofluorescence and immuno-cryoelectron microscopy the Y144R protein was detected on the intracellular enveloped virus (IEV), cell-associated enveloped virus (CEV) and EEV. This represents the first study of a YLDV IEV, CEV and EEV protein at the molecular level.

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Kushi, R. T., R. Monti, and J. Contiero. "Production, purification and characterization of an extracellular inulinase from Kluyveromyces marxianus var. bulgaricus." Journal of Industrial Microbiology and Biotechnology 25, no. 2 (August 1, 2000): 63–69. http://dx.doi.org/10.1038/sj.jim.7000032.

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Gil-Serrano, Antonio, Angel Sanchez del Junco, Pilar Tejero-Mateo, Manuel Megias, and Miguel A. Caviedes. "Structure of the extracellular polysaccharide secreted by Rhizobium leguminosarum var. phaseoli CIAT 899." Carbohydrate Research 204 (September 1990): 103–7. http://dx.doi.org/10.1016/0008-6215(90)84025-p.

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Hamdy, Hossam S., and Medhat A. Abo-Tahon. "Extracellular lipase of Aspergillus terreus var. africanus (CBS 130.55): production, purification and characterisation." Annals of Microbiology 62, no. 4 (February 29, 2012): 1723–36. http://dx.doi.org/10.1007/s13213-012-0429-4.

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Journal articles on the topic 'Vpr extracellulaire'

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