scholarly journals Mechanical stress impairs pheromone signaling via Pkc1-mediated regulation of the MAPK scaffold Ste5

2019 ◽  
Vol 218 (9) ◽  
pp. 3117-3133 ◽  
Author(s):  
Frank van Drogen ◽  
Ranjan Mishra ◽  
Fabian Rudolf ◽  
Michal J. Walczak ◽  
Sung Sik Lee ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Cell Fusion ◽  
Polarized Growth ◽  
Conserved Residues ◽  
Cellular Processes ◽  
Pheromone Signaling ◽  
Stress Signals ◽  
Cell Cell

Cells continuously adapt cellular processes by integrating external and internal signals. In yeast, multiple stress signals regulate pheromone signaling to prevent mating under unfavorable conditions. However, the underlying crosstalk mechanisms remain poorly understood. Here, we show that mechanical stress activates Pkc1, which prevents lysis of pheromone-treated cells by inhibiting polarized growth. In vitro Pkc1 phosphorylates conserved residues within the RING-H2 domains of the scaffold proteins Far1 and Ste5, which are also phosphorylated in vivo. Interestingly, Pkc1 triggers dispersal of Ste5 from mating projections upon mechanically induced stress and during cell–cell fusion, leading to inhibition of the MAPK Fus3. Indeed, RING phosphorylation interferes with Ste5 membrane association by preventing binding to the receptor-linked Gβγ protein. Cells expressing nonphosphorylatable Ste5 undergo increased lysis upon mechanical stress and exhibit defects in cell–cell fusion during mating, which is exacerbated by simultaneous expression of nonphosphorylatable Far1. These results uncover a mechanical stress–triggered crosstalk mechanism modulating pheromone signaling, polarized growth, and cell–cell fusion during mating.

scholarly journals Pheromone-induced polarization is dependent on the Fus3p MAPK acting through the formin Bni1p

2004 ◽  
Vol 165 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Dina Matheos ◽  
Metodi Metodiev ◽  
Eric Muller ◽  
David Stone ◽  
Mark D. Rose
Keyword(s):  
Cell Fusion ◽  
Cell Polarization ◽  
Yeast Cells ◽  
Cortical Actin ◽  
Cytoplasmic Microtubule ◽  
Multiple Phenotypes ◽  
Pheromone Signaling ◽  
Mutant Phenotypes

During mating, budding yeast cells reorient growth toward the highest concentration of pheromone. Bni1p, a formin homologue, is required for this polarized growth by facilitating cortical actin cable assembly. Fus3p, a pheromone-activated MAP kinase, is required for pheromone signaling and cell fusion. We show that Fus3p phosphorylates Bni1p in vitro, and phosphorylation of Bni1p in vivo during the pheromone response is dependent on Fus3p. fus3 mutants exhibited multiple phenotypes similar to bni1 mutants, including defects in actin and cell polarization, as well as Kar9p and cytoplasmic microtubule localization. Disruption of the interaction between Fus3p and the receptor-associated Gα subunit caused similar mutant phenotypes. After pheromone treatment, Bni1p-GFP and Spa2p failed to localize to the cortex of fus3 mutants, and cell wall growth became completely unpolarized. Bni1p overexpression suppressed the actin assembly, cell polarization, and cell fusion defects. These data suggest a model wherein activated Fus3p is recruited back to the cortex, where it activates Bni1p to promote polarization and cell fusion.

scholarly journals CD13 is a critical regulator of cell–cell fusion in osteoclastogenesis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mallika Ghosh ◽  
Tomislav Kelava ◽  
Ivana Vrhovac Madunic ◽  
Ivo Kalajzic ◽  
Linda H. Shapiro
Keyword(s):  
Bone Marrow ◽  
Cell Fusion ◽  
Regulatory Proteins ◽  
Cytoskeletal Organization ◽  
Receptor Endocytosis ◽  
The Stability ◽  
Deficient Mice ◽  
Cell Cell

AbstractThe transmembrane aminopeptidase CD13 is highly expressed in cells of the myeloid lineage, regulates dynamin-dependent receptor endocytosis and recycling and is a necessary component of actin cytoskeletal organization. Here, we show that CD13-deficient mice present a low bone density phenotype with increased numbers of osteoclasts per bone surface, but display a normal distribution of osteoclast progenitor populations in the bone marrow and periphery. In addition, the bone formation and mineral apposition rates are similar between genotypes, indicating a defect in osteoclast-specific function in vivo. Lack of CD13 led to exaggerated in vitro osteoclastogenesis as indicated by significantly enhanced fusion of bone marrow-derived multinucleated osteoclasts in the presence of M-CSF and RANKL, resulting in abnormally large cells containing remarkably high numbers of nuclei. Mechanistically, while expression levels of the fusion-regulatory proteins dynamin and DC-STAMP1 must be downregulated for fusion to proceed, these are aberrantly sustained at high levels even in CD13-deficient mature multi-nucleated osteoclasts. Further, the stability of fusion-promoting proteins is maintained in the absence of CD13, implicating CD13 in protein turnover mechanisms. Together, we conclude that CD13 may regulate cell–cell fusion by controlling the expression and localization of key fusion regulatory proteins that are critical for osteoclast fusion.

scholarly journals CD13 is a Critical Regulator of Cell-cell Fusion in Osteoclastogenesis

2020 ◽  
Author(s):  
Mallika Ghosh ◽  
Ivo Kalajzic ◽  
Hector Leonardo Aguila ◽  
Linda H Shapiro
Keyword(s):  
Bone Marrow ◽  
Bone Formation ◽  
Progenitor Cells ◽  
Cell Fusion ◽  
Formation Rate ◽  
Giant Cells ◽  
Bone Formation Rate ◽  
Cell Cell

AbstractIn vertebrates, bone formation is dynamically controlled by the activity of two specialized cell types: the bone-generating osteoblasts and bone-degrading osteoclasts. Osteoblasts produce the soluble receptor activator of NFκB ligand (RANKL) that binds to its receptor RANK on the surface of osteoclast precursor cells to promote osteoclastogenesis, a process that involves cell-cell fusion and assembly of molecular machinery to ultimately degrade the bone. CD13 is a transmembrane aminopeptidase that is highly expressed in cells of myeloid lineage has been shown to regulate dynamin-dependent receptor endocytosis and recycling and is a necessary component of actin cytoskeletal organization. In the present study, we show that CD13-deficient mice display a normal distribution of osteoclast progenitor populations in the bone marrow, but present a low bone density phenotype. Further, the endosteal bone formation rate is similar between genotypes, indicating a defect in osteoclast-specific function in vivo. Loss of CD13 led to exaggerated in vitro osteoclastogenesis as indicated by significantly enhanced fusion of bone marrow-derived multinucleated osteoclasts in the presence of M-CSF and RANKL, resulting in abnormally large cells with remarkably high numbers of nuclei with a concomitant increase in bone resorption activity. Similarly, we also observed increased formation of multinucleated giant cells (MGC) in CD13KO bone marrow progenitor cells stimulated with IL-4 and IL-13, suggesting that CD13 may regulate cell-cell fusion events via a common pathway, independent of RANKL signaling. Mechanistically, while expression levels of the fusion-regulatory proteins dynamin and DC-STAMP are normally downregulated as fusion progresses in fusion-competent mononucleated progenitor cells, in the absence of CD13 they are uniformly sustained at high levels, even in mature multi-nucleated osteoclasts. Taken together, we conclude that CD13 may regulate cell-cell fusion by controlling expression and localization of key fusion proteins that are critical for both osteoclast and MGC fusion.

scholarly journals ARHGEF18/p114RhoGEF coordinates PKA/CREB signaling and actomyosin remodeling to drive trophoblast cell-cell fusion during placenta morphogenesis

2020 ◽  
Author(s):  
Robert Beal ◽  
Ana Alonso-Carriazo Fernandez ◽  
Dimitris K. Grammatopoulos ◽  
Karl Matter ◽  
Maria S. Balda
Keyword(s):  
Gene Expression ◽  
Cell Fusion ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Trophoblast Cell ◽  
Cell Junctions ◽  
Nucleotide Exchange ◽  
Cell Cell

SUMMARYCoordination of cell-cell adhesion, actomyosin dynamics and gene expression is crucial for morphogenetic processes underlying tissue and organ development. Rho GTPases are main regulators of the cytoskeleton and adhesion. They are activated by guanine nucleotide exchange factors in a spatially and temporally controlled manner. However, the roles of these Rho GTPase activators during complex developmental processes are still poorly understood. ARHGEF18/p114RhoGEF is a tight junction-associated RhoA activator that forms complexes with myosin II, and regulates actomyosin contractility. Here we show that p114RhoGEF/ ARHGEF18 is required for mouse syncytiotrophoblast differentiation and placenta development. In vitro and in vivo experiments identify that p114RhoGEF controls expression of AKAP12, a protein regulating PKA signalling, and is required for PKA-induced actomyosin remodelling, CREB-driven gene expression of proteins required for trophoblast differentiation, and, hence, trophoblast cell-cell fusion. Our data thus indicate that p114RhoGEF links actomyosin dynamics and cell-cell junctions to PKA/CREB signalling, gene expression and cell-cell fusion.

scholarly journals Human immunodeficiency virus 1 (HIV-1) envelope-dependent cell–cell fusion modulation by HIV-positive sera is related to disease progression

2005 ◽  
Vol 86 (7) ◽  
pp. 1961-1966 ◽  
Author(s):  
L. Huerta ◽  
G. Gómez-Icazbalceta ◽  
L. Soto-Ramírez ◽  
M. Viveros-Rogel ◽  
R. Rodríguez ◽  
...  
Keyword(s):  
Cell Fusion ◽  
Cell Damage ◽  
Hiv Positive ◽  
Immunodeficiency Virus ◽  
Load Removal ◽  
Dependent Cell ◽  
Hiv 1 ◽  
Cell Cell

Fusion of CD4+ cells by HIV-1 envelope proteins (Env) is a mechanism of virus spread and cell damage. Production of antibodies able to influence cell–cell fusion in vivo may affect the course of the infection. The effect of sera from 49 HIV-1-positive patients was tested on an in vitro fusion assay using Env-expressing and normal Jurkat T cells labelled with DiI and DiO dyes, and flow cytometry for quantification of cell–cell fusion. Sera varied in their activity on fusion: 69·4 % inhibited, 24·5 % had no effect and 6·1 % enhanced cell fusion. Fusion activity correlated positively with the CD4+ T-cell count and inversely with the viral load. Removal of IgG or IgM from sera reduced or eliminated inhibition and enhancing activities, respectively. Antibodies with inhibitory activity predominate in early and intermediate stages of infection, whereas loss of inhibition or enhancement of fusion correlates with progression to AIDS.

scholarly journals BST2/Tetherin Overexpression Modulates Morbillivirus Glycoprotein Production to Inhibit Cell–Cell Fusion

Viruses ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 692 ◽  
Author(s):  
James T. Kelly ◽  
Stacey Human ◽  
Joseph Alderman ◽  
Fatoumatta Jobe ◽  
Leanne Logan ◽  
...  
Keyword(s):  
Cell Fusion ◽  
Measles Virus ◽  
Viral Fusion ◽  
Large Reduction ◽  
Glycosyl Phosphatidylinositol ◽  
Species Specific ◽  
Syncytia Formation ◽  
Cell Cell

The measles virus (MeV), a member of the genus Morbillivirus, is an established pathogen of humans. A key feature of morbilliviruses is their ability to spread by virus–cell and cell–cell fusion. The latter process, which leads to syncytia formation in vitro and in vivo, is driven by the viral fusion (F) and haemagglutinin (H) glycoproteins. In this study, we demonstrate that MeV glycoproteins are sensitive to inhibition by bone marrow stromal antigen 2 (BST2/Tetherin/CD317) proteins. BST2 overexpression causes a large reduction in MeV syncytia expansion. Using quantitative cell–cell fusion assays, immunolabeling, and biochemistry we further demonstrate that ectopically expressed BST2 directly inhibits MeV cell–cell fusion. This restriction is mediated by the targeting of the MeV H glycoprotein, but not other MeV proteins. Using truncation mutants, we further establish that the C-terminal glycosyl-phosphatidylinositol (GPI) anchor of BST2 is required for the restriction of MeV replication in vitro and cell–cell fusion. By extending our study to the ruminant morbillivirus peste des petits ruminants virus (PPRV) and its natural host, sheep, we also confirm this is a broad and cross-species specific phenotype.

scholarly journals Cell Fusion and Syncytium Formation in Betaherpesvirus Infection

Viruses ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1973
Author(s):  
Jiajia Tang ◽  
Giada Frascaroli ◽  
Xuan Zhou ◽  
Jan Knickmann ◽  
Wolfram Brune
Keyword(s):  
Cell Fusion ◽  
Neutralizing Antibodies ◽  
Plasma Membranes ◽  
Cancer Metastasis ◽  
Syncytium Formation ◽  
Tissue Growth ◽  
Viral Envelope ◽  
Cell Cell

Cell–cell fusion is a fundamental and complex process that occurs during reproduction, organ and tissue growth, cancer metastasis, immune response, and infection. All enveloped viruses express one or more proteins that drive the fusion of the viral envelope with cellular membranes. The same proteins can mediate the fusion of the plasma membranes of adjacent cells, leading to the formation of multinucleated syncytia. While cell–cell fusion triggered by alpha- and gammaherpesviruses is well-studied, much less is known about the fusogenic potential of betaherpesviruses such as human cytomegalovirus (HCMV) and human herpesviruses 6 and 7 (HHV-6 and HHV-7). These are slow-growing viruses that are highly prevalent in the human population and associated with several diseases, particularly in individuals with an immature or impaired immune system such as fetuses and transplant recipients. While HHV-6 and HHV-7 are strictly lymphotropic, HCMV infects a very broad range of cell types including epithelial, endothelial, mesenchymal, and myeloid cells. Syncytia have been observed occasionally for all three betaherpesviruses, both during in vitro and in vivo infection. Since cell–cell fusion may allow efficient spread to neighboring cells without exposure to neutralizing antibodies and other host immune factors, viral-induced syncytia may be important for viral dissemination, long-term persistence, and pathogenicity. In this review, we provide an overview of the viral and cellular factors and mechanisms identified so far in the process of cell–cell fusion induced by betaherpesviruses and discuss the possible consequences for cellular dysfunction and pathogenesis.

scholarly journals ARHGEF18/p114RhoGEF Coordinates PKA/CREB Signaling and Actomyosin Remodeling to Promote Trophoblast Cell-Cell Fusion During Placenta Morphogenesis

2021 ◽  
Vol 9 ◽  
Author(s):  
Robert Beal ◽  
Ana Alonso-Carriazo Fernandez ◽  
Dimitris K. Grammatopoulos ◽  
Karl Matter ◽  
Maria S. Balda
Keyword(s):  
Gene Expression ◽  
Cell Fusion ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Trophoblast Cell ◽  
Cell Junctions ◽  
Nucleotide Exchange ◽  
Cell Cell

Coordination of cell-cell adhesion, actomyosin dynamics and gene expression is crucial for morphogenetic processes underlying tissue and organ development. Rho GTPases are main regulators of the cytoskeleton and adhesion. They are activated by guanine nucleotide exchange factors in a spatially and temporally controlled manner. However, the roles of these Rho GTPase activators during complex developmental processes are still poorly understood. ARHGEF18/p114RhoGEF is a tight junction-associated RhoA activator that forms complexes with myosin II, and regulates actomyosin contractility. Here we show that p114RhoGEF/ARHGEF18 is required for mouse syncytiotrophoblast differentiation and placenta development. In vitro and in vivo experiments identify that p114RhoGEF controls expression of AKAP12, a protein regulating protein kinase A (PKA) signaling, and is required for PKA-induced actomyosin remodeling, cAMP-responsive element binding protein (CREB)-driven gene expression of proteins required for trophoblast differentiation, and, hence, trophoblast cell-cell fusion. Our data thus indicate that p114RhoGEF links actomyosin dynamics and cell-cell junctions to PKA/CREB signaling, gene expression and cell-cell fusion.

scholarly journals Exosomal Vimentin from Adipocyte Progenitors Protects Fibroblasts against Osmotic Stress and Inhibits Apoptosis to Enhance Wound Healing

2021 ◽  
Vol 22 (9) ◽  
pp. 4678
Author(s):  
Sepideh Parvanian ◽  
Hualian Zha ◽  
Dandan Su ◽  
Lifang Xi ◽  
Yaming Jiu ◽  
...  
Keyword(s):  
Wound Healing ◽  
Osmotic Stress ◽  
Mechanical Stress ◽  
Impaired Wound Healing ◽  
In Vivo Experiments ◽  
Adipocyte Progenitors ◽  
Osmotic Balance ◽  
Induced Apoptosis

Mechanical stress following injury regulates the quality and speed of wound healing. Improper mechanotransduction can lead to impaired wound healing and scar formation. Vimentin intermediate filaments control fibroblasts’ response to mechanical stress and lack of vimentin makes cells significantly vulnerable to environmental stress. We previously reported the involvement of exosomal vimentin in mediating wound healing. Here we performed in vitro and in vivo experiments to explore the effect of wide-type and vimentin knockout exosomes in accelerating wound healing under osmotic stress condition. Our results showed that osmotic stress increases the size and enhances the release of exosomes. Furthermore, our findings revealed that exosomal vimentin enhances wound healing by protecting fibroblasts against osmotic stress and inhibiting stress-induced apoptosis. These data suggest that exosomes could be considered either as a stress modifier to restore the osmotic balance or as a conveyer of stress to induce osmotic stress-driven conditions.

scholarly journals Bone marrow mesenchymal stem cells promote prostate cancer cell stemness via cell–cell contact to activate the Jagged1/Notch1 pathway

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ji-wen Cheng ◽  
Li-xia Duan ◽  
Yang Yu ◽  
Pu Wang ◽  
Jia-le Feng ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Western Blot ◽  
Cell Contact ◽  
Activity Levels ◽  
Tumor Resistance ◽  
Cell Cell

Abstract Background Mesenchymal stem cells (MSCs) play a crucial role in cancer development and tumor resistance to therapy in prostate cancer, but the influence of MSCs on the stemness potential of PCa cells by cell–cell contact remains unclear. In this study, we investigated the effect of direct contact of PCa cells with MSCs on the stemness of PCa and its mechanisms. Methods First, the flow cytometry, colony formation, and sphere formation were performed to determine the stemness of PCaMSCs, and the expression of stemness-related molecules (Sox2, Oct4, and Nanog) was investigated by western blot analysis. Then, we used western blot and qPCR to determine the activity levels of two candidate pathways and their downstream stemness-associated pathway. Finally, we verified the role of the significantly changed pathway by assessing the key factors in this pathway via in vitro and in vivo experiments. Results We established that MSCs promoted the stemness of PCa cells by cell–cell contact. We here established that the enhanced stemness of PCaMSCs was independent of the CCL5/CCR5 pathway. We also found that PCaMSCs up-regulated the expression of Notch signaling-related genes, and inhibition of Jagged1-Notch1 signaling in PCaMSCs cells significantly inhibited MSCs-induced stemness and tumorigenesis in vitro and in vivo. Conclusions Our results reveal a novel interaction between MSCs and PCa cells in promoting tumorigenesis through activation of the Jagged1/Notch1 pathway, providing a new therapeutic target for the treatment of PCa.

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