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Jean-pierre Tassan - One of the best experts on this subject based on the ideXlab platform.
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Tight junction-associated protein GEF-H1 in the neighbours of dividing epithelial cells is essential for adaptation of cell-cell membrane during Cytokinesis
Experimental Cell Research, 2018Co-Authors: Guillaume Hatte, Claude Prigent, Jean-pierre TassanAbstract:Animal cells divide by a process called Cytokinesis which relies on the constriction of a contractile actomyosin ring leading to the production of two daughter cells. Cytokinesis is an intrinsic property of cells which occurs even for artificially isolated cells. During division, isolated cells undergo dramatic changes in shape such as rounding and membrane deformation as the division furrow ingresses. However, cells are often embedded in tissues and thus are surrounded by neighbouring cells. How these neighbours might influence, or might themselves be influenced by, the shape changes of Cytokinesis is poorly understood in vertebrates. Here, we show that during Cytokinesis of epithelial cells in the Xenopus embryo, lateral cell-cell contacts remain almost perpendicular to the epithelial plane. Depletion of the tight junction-associated protein GEF-H1 leads to a transient and stereotyped deformation of cell-cell contacts. Although, this deformation occurs only during Cytokinesis, we show that it originates from immediate neighbours of the dividing cell. Moreover, we show that exocyst and recycling endosome regulation by GEF-H1 are involved in adaptation of cell-cell contacts to deformation. Our results highlight the crucial role of tight junctions and GEF-H1 in cell-cell contact adaptation when cells are exposed to a mechanical stress such as Cytokinesis.
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Tight junctions negatively regulate mechanical forces applied to adherens junctions in vertebrate epithelial tissue
Journal of Cell Science, 2018Co-Authors: Guillaume Hatte, Claude Prigent, Jean-pierre TassanAbstract:Epithelia are layers of polarised cells tightly bound to each other by adhesive contacts. Epithelia act as barriers between an organism and its external environment. Understanding how epithelia maintain their essential integrity while remaining sufficiently plastic to allow events such as Cytokinesis to take place is a key biological problem. In vertebrates, the remodelling and reinforcement of adherens junctions maintains epithelial integrity during Cytokinesis. The involvement of tight junctions in cell division, however, has remained unexplored. Here, we examine the role of tight junctions during Cytokinesis in the epithelium of the Xenopus laevis embryo. Depletion of the tight junction-associated proteins ZO-1 and GEF-H1 leads to altered Cytokinesis duration and contractile ring geometry. Using a tension biosensor, we show that Cytokinesis defects originate from misregulation of tensile forces applied to adherens junctions. Our results reveal that tight junctions regulate mechanical tension applied to adherens junctions, which in turn impacts Cytokinesis.
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Cortical localization of maternal embryonic leucine zipper kinase (MELK) implicated in Cytokinesis in early xenopus embryos.
Communicative and Integrative Biology, 2011Co-Authors: Jean-pierre TassanAbstract:MELK has been implicated in a large variety of functions. Because its level is elevated in cancer tissues and it is involved in cell proliferation, MELK is considered as a potential therapeutic target for cancers. In a recent, study we have shown that MELK is involved in Cytokinesis in early Xenopus laevis embryos. MELK dynamically accumulates at the cell cortex including a narrow band corresponding to the presumptive division furrow shortly before Cytokinesis onset. MELK co-localizes and interacts with anillin an important regulator of Cytokinesis. In addition, MELK overexpression interferes with accumulation at the cleavage furrow of activated Rho GTPase another crucial regulator of Cytokinesis. Interestingly, our study also revealed that a transition implying a change in the direction of asymmetric furrow ingression occurs during early development. After this transition, MELK, as well as other proteins involved in Cytokinesis, do not localize anymore as a band at the equatorial cortex but still localizes at the cell cortex. Our results indicate that cortical localization is an important feature of MELK in X. laevis embryos.
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A functional analysis of MELK in cell division reveals a transition in the mode of Cytokinesis during Xenopus development.
Journal of Cell Science, 2011Co-Authors: Yann Le Page, Isabelle Chartrain, Caroline Badouel, Jean-pierre TassanAbstract:MELK is a serine/threonine kinase involved in several cell processes, including the cell cycle, proliferation, apoptosis and mRNA processing. However, its function remains elusive. Here, we explored its role in the Xenopus early embryo and show by knockdown that xMELK (Xenopus MELK) is necessary for completion of cell division. Consistent with a role in cell division, endogenous xMELK accumulates at the equatorial cortex of anaphase blastomeres. Its relocalization is highly dynamic and correlates with a conformational rearrangement in xMELK. Overexpression of xMELK leads to failure of Cytokinesis and impairs accumulation at the division furrow of activated RhoA - a pivotal regulator of Cytokinesis. Furthermore, endogenous xMELK associates and colocalizes with the Cytokinesis organizer anillin. Unexpectedly, our study reveals a transition in the mode of Cytokinesis correlated to cell size and that implicates xMELK. Collectively, our findings disclose the importance of xMELK in Cytokinesis during early development and show that the mechanism of Cytokinesis changes during Xenopus early development.
Guillaume Hatte - One of the best experts on this subject based on the ideXlab platform.
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Tight junctions negatively regulate mechanical forces applied to adherens junctions in vertebrate epithelial tissue
Journal of Cell Science, 2018Co-Authors: Guillaume Hatte, Claude Prigent, Jean-pierre TassanAbstract:Epithelia are layers of polarised cells tightly bound to each other by adhesive contacts. Epithelia act as barriers between an organism and its external environment. Understanding how epithelia maintain their essential integrity while remaining sufficiently plastic to allow events such as Cytokinesis to take place is a key biological problem. In vertebrates, the remodelling and reinforcement of adherens junctions maintains epithelial integrity during Cytokinesis. The involvement of tight junctions in cell division, however, has remained unexplored. Here, we examine the role of tight junctions during Cytokinesis in the epithelium of the Xenopus laevis embryo. Depletion of the tight junction-associated proteins ZO-1 and GEF-H1 leads to altered Cytokinesis duration and contractile ring geometry. Using a tension biosensor, we show that Cytokinesis defects originate from misregulation of tensile forces applied to adherens junctions. Our results reveal that tight junctions regulate mechanical tension applied to adherens junctions, which in turn impacts Cytokinesis.
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Tight junction-associated protein GEF-H1 in the neighbours of dividing epithelial cells is essential for adaptation of cell-cell membrane during Cytokinesis
Experimental Cell Research, 2018Co-Authors: Guillaume Hatte, Claude Prigent, Jean-pierre TassanAbstract:Animal cells divide by a process called Cytokinesis which relies on the constriction of a contractile actomyosin ring leading to the production of two daughter cells. Cytokinesis is an intrinsic property of cells which occurs even for artificially isolated cells. During division, isolated cells undergo dramatic changes in shape such as rounding and membrane deformation as the division furrow ingresses. However, cells are often embedded in tissues and thus are surrounded by neighbouring cells. How these neighbours might influence, or might themselves be influenced by, the shape changes of Cytokinesis is poorly understood in vertebrates. Here, we show that during Cytokinesis of epithelial cells in the Xenopus embryo, lateral cell-cell contacts remain almost perpendicular to the epithelial plane. Depletion of the tight junction-associated protein GEF-H1 leads to a transient and stereotyped deformation of cell-cell contacts. Although, this deformation occurs only during Cytokinesis, we show that it originates from immediate neighbours of the dividing cell. Moreover, we show that exocyst and recycling endosome regulation by GEF-H1 are involved in adaptation of cell-cell contacts to deformation. Our results highlight the crucial role of tight junctions and GEF-H1 in cell-cell contact adaptation when cells are exposed to a mechanical stress such as Cytokinesis.
Ziyin Li - One of the best experts on this subject based on the ideXlab platform.
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functional analyses of Cytokinesis regulators in bloodstream stage trypanosoma brucei parasites identify functions and regulations specific to the life cycle stage
mSphere, 2019Co-Authors: Tai An, Kieu T M Pham, Xuan Zhang, Ziyin LiAbstract:ABSTRACT The early divergent protozoan parasite Trypanosoma brucei alternates between the insect vector and the mammalian hosts during its life cycle and proliferates through binary cell fission. The cell cycle control system in T. brucei differs substantially from that in its mammalian hosts and possesses distinct mitosis-Cytokinesis checkpoint controls between two life cycle stages, the procyclic form and the bloodstream form. T. brucei undergoes an unusual mode of Cytokinesis, which is controlled by a novel signaling cascade consisting of evolutionarily conserved protein kinases and trypanosome-specific regulatory proteins in the procyclic form. However, given the distinct mitosis-Cytokinesis checkpoints between the two forms, it is unclear whether the Cytokinesis regulatory pathway discovered in the procyclic form also operates in a similar manner in the bloodstream form. Here, we showed that the three regulators of Cytokinesis initiation, Cytokinesis initiation factor 1 (CIF1), CIF2, and CIF3, are interdependent for subcellular localization but not for protein stability as in the procyclic form. Further, we demonstrated that KLIF, a regulator of Cytokinesis completion in the procyclic form, plays limited roles in Cytokinesis in the bloodstream form. Finally, we showed that the cleavage furrow-localizing protein FRW1 is required for Cytokinesis initiation in the bloodstream form but is nonessential for Cytokinesis in the procyclic form. Together, these results identify conserved and life cycle-specific functions of Cytokinesis regulators, highlighting the distinction in the regulation of Cytokinesis between different life cycle stages of T. brucei. IMPORTANCE The early divergent protozoan parasite Trypanosoma brucei is the causative agent of sleeping sickness in humans and nagana in cattle in sub-Saharan Africa. This parasite has a complex life cycle by alternating between the insect vector and the mammalian hosts and proliferates by binary cell fission. The control of cell division in trypanosomes appears to be distinct from that in its human host and differs substantially between two life cycle stages, the procyclic (insect) form and the bloodstream form. Cytokinesis, the final step of binary cell fission, is regulated by a novel signaling cascade consisting of two evolutionarily conserved protein kinases and a cohort of trypanosome-specific regulators in the procyclic form, but whether this signaling pathway operates in a similar manner in the bloodstream form is unclear. In this report, we performed a functional analysis of multiple Cytokinesis regulators and discovered their distinct functions and regulations in the bloodstream form.
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an ef hand containing protein in trypanosoma brucei regulates Cytokinesis initiation by maintaining the stability of the Cytokinesis initiation factor cif1
Journal of Biological Chemistry, 2016Co-Authors: Qing Zhou, Huiqing Hu, Ziyin LiAbstract:: Trypanosoma brucei undergoes Cytokinesis uni-directionally from the anterior tip of the new flagellum attachment zone (FAZ) toward the posterior end of the cell. We recently delineated a novel signaling pathway composed of polo-like kinase, Cytokinesis initiation factor 1 (CIF1), and aurora B kinase that acts in concert at the new FAZ tip to regulate Cytokinesis initiation. To identify new Cytokinesis regulators, we carried out proximity-dependent biotin identification and identified many CIF1 binding partners and near neighbors. Here we report a novel CIF1-binding protein, named CIF2, and its mechanistic role in Cytokinesis initiation. CIF2 interacts with CIF1 in vivo and co-localizes with CIF1 at the new FAZ tip during early cell cycle stages. RNAi of CIF2 inhibited the normal, anterior-to-posterior Cytokinesis but activated an alternative, posterior-to-anterior Cytokinesis. CIF2 depletion destabilized CIF1 and disrupted the localization of polo-like kinase and aurora B kinase to the new FAZ tip, thus revealing the mechanistic role of CIF2 in Cytokinesis initiation. Surprisingly, overexpression of CIF2 also inhibited the normal, anterior-to-posterior Cytokinesis and triggered the alternative, posterior-to-anterior Cytokinesis, suggesting a tight control of CIF2 protein abundance. These results identified a new regulator in the Cytokinesis regulatory pathway and reiterated that a backup Cytokinesis pathway is activated by inhibiting the normal Cytokinesis pathway.
Claude Prigent - One of the best experts on this subject based on the ideXlab platform.
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Tight junctions negatively regulate mechanical forces applied to adherens junctions in vertebrate epithelial tissue
Journal of Cell Science, 2018Co-Authors: Guillaume Hatte, Claude Prigent, Jean-pierre TassanAbstract:Epithelia are layers of polarised cells tightly bound to each other by adhesive contacts. Epithelia act as barriers between an organism and its external environment. Understanding how epithelia maintain their essential integrity while remaining sufficiently plastic to allow events such as Cytokinesis to take place is a key biological problem. In vertebrates, the remodelling and reinforcement of adherens junctions maintains epithelial integrity during Cytokinesis. The involvement of tight junctions in cell division, however, has remained unexplored. Here, we examine the role of tight junctions during Cytokinesis in the epithelium of the Xenopus laevis embryo. Depletion of the tight junction-associated proteins ZO-1 and GEF-H1 leads to altered Cytokinesis duration and contractile ring geometry. Using a tension biosensor, we show that Cytokinesis defects originate from misregulation of tensile forces applied to adherens junctions. Our results reveal that tight junctions regulate mechanical tension applied to adherens junctions, which in turn impacts Cytokinesis.
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Tight junction-associated protein GEF-H1 in the neighbours of dividing epithelial cells is essential for adaptation of cell-cell membrane during Cytokinesis
Experimental Cell Research, 2018Co-Authors: Guillaume Hatte, Claude Prigent, Jean-pierre TassanAbstract:Animal cells divide by a process called Cytokinesis which relies on the constriction of a contractile actomyosin ring leading to the production of two daughter cells. Cytokinesis is an intrinsic property of cells which occurs even for artificially isolated cells. During division, isolated cells undergo dramatic changes in shape such as rounding and membrane deformation as the division furrow ingresses. However, cells are often embedded in tissues and thus are surrounded by neighbouring cells. How these neighbours might influence, or might themselves be influenced by, the shape changes of Cytokinesis is poorly understood in vertebrates. Here, we show that during Cytokinesis of epithelial cells in the Xenopus embryo, lateral cell-cell contacts remain almost perpendicular to the epithelial plane. Depletion of the tight junction-associated protein GEF-H1 leads to a transient and stereotyped deformation of cell-cell contacts. Although, this deformation occurs only during Cytokinesis, we show that it originates from immediate neighbours of the dividing cell. Moreover, we show that exocyst and recycling endosome regulation by GEF-H1 are involved in adaptation of cell-cell contacts to deformation. Our results highlight the crucial role of tight junctions and GEF-H1 in cell-cell contact adaptation when cells are exposed to a mechanical stress such as Cytokinesis.
Michael Glotzer - One of the best experts on this subject based on the ideXlab platform.
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The Molecular Requirements for Cytokinesis
Science, 2005Co-Authors: Michael GlotzerAbstract:After anaphase onset, animal cells build an actomyosin contractile ring that constricts the plasma membrane to generate two daughter cells connected by a cytoplasmic bridge. The bridge is ultimately severed to complete Cytokinesis. Myriad techniques have been used to identify proteins that participate in Cytokinesis in vertebrates, insects, and nematodes. A conserved core of about 20 proteins are individually involved with Cytokinesis in most animal cells. These components are found in the contractile ring, on the central spindle, within the RhoA pathway, and on vesicles that expand the membrane and sever the bridge. Cytokinesis involves additional proteins, but they, or their requirement in Cytokinesis, are not conserved among animal cells.
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comparative analysis of Cytokinesis in budding yeast fission yeast and animal cells
Current Biology, 2004Co-Authors: Mohan K Balasubramanian, Michael GlotzerAbstract:Cytokinesis is a temporally and spatially regulated process through which the cellular constituents of the mother cell are partitioned into two daughter cells, permitting an increase in cell number. When Cytokinesis occurs in a polarized cell it can create daughters with distinct fates. In eukaryotes, Cytokinesis is carried out by the coordinated action of a cortical actomyosin contractile ring and targeted membrane deposition. Recent use of model organisms with facile genetics and improved light-microscopy methods has led to the identification and functional characterization of many proteins involved in Cytokinesis. To date, this analysis indicates that some of the basic components involved in Cytokinesis are conserved from yeast to humans, although their organization into functional machinery that drives Cytokinesis and the associated regulatory mechanisms bear species-specific features. Here, we briefly review the current status of knowledge of Cytokinesis in the budding yeast Saccharomyces cerevisiae, the fission yeast Schizosaccharomyces pombe and animal cells, in an attempt to highlight both the common and the unique features. Although these organisms diverged from a common ancestor about a billion years ago, there are eukaryotes that are far more divergent. To evaluate the overall evolutionary conservation of Cytokinesis, it will be necessary to include representatives of these divergent branches. Nevertheless, the three species discussed here provide substantial mechanistic diversity.
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cyk 4 a rho family gtpase activating protein gap required for central spindle formation and Cytokinesis
Journal of Cell Biology, 2000Co-Authors: Verena Jantschplunger, Anthony A. Hyman, Pierre Gonczy, Alper Romano, Heinke Schnabel, Danielle R Hamill, Ralf Schnabel, Michael GlotzerAbstract:During Cytokinesis of animal cells, the mitotic spindle plays at least two roles. Initially, the spindle positions the contractile ring. Subsequently, the central spindle, which is composed of microtubule bundles that form during anaphase, promotes a late step in Cytokinesis. How the central spindle assembles and functions in Cytokinesis is poorly understood. The cyk-4 gene has been identified by genetic analysis in Caenorhabditis elegans. Embryos from cyk-4(t1689ts) mutant hermaphrodites initiate, but fail to complete, Cytokinesis. These embryos also fail to assemble the central spindle. We show that the cyk-4 gene encodes a GTPase activating protein (GAP) for Rho family GTPases. CYK-4 activates GTP hydrolysis by RhoA, Rac1, and Cdc42 in vitro. RNA-mediated interference of RhoA, Rac1, and Cdc42 indicates that only RhoA is essential for Cytokinesis and, thus, RhoA is the likely target of CYK-4 GAP activity for Cytokinesis. CYK-4 and a CYK-4:GFP fusion protein localize to the central spindle and persist at cell division remnants. CYK-4 localization is dependent on the kinesin-like protein ZEN-4/CeMKLP1 and vice versa. These data suggest that CYK-4 and ZEN-4/CeMKLP1 cooperate in central spindle assembly. Central spindle localization of CYK-4 could accelerate GTP hydrolysis by RhoA, thereby allowing contractile ring disassembly and completion of Cytokinesis.
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The mechanism and control of Cytokinesis.
Current Opinion in Cell Biology, 1997Co-Authors: Michael GlotzerAbstract:Cytokinesis is under active investigation in each of the dominant experimental model systems. During 1996 and 1997, several developments necessitated the reassessment of the prevailing model for Cytokinesis. In addition, the inventory of proteins required for Cytokinesis has grown considerably. However, a molecular understanding of Cytokinesis still remains elusive.
