The Experts below are selected from a list of 17529 Experts worldwide ranked by ideXlab platform
Anthony Bretscher - One of the best experts on this subject based on the ideXlab platform.
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rhoa effectors lok slk activate erm proteins to locally inhibit rhoa and define apical morphology
bioRxiv, 2020Co-Authors: Riasat Zaman, Cécile Sauvanet, Raghuvir Viswanatha, Andrew T Lombardo, Valerie Awad, Locke Ezraros Bonomo, David J Mcdermitt, Anthony BretscherAbstract:Abstract Activated Ezrin-Radixin-Moesin (ERM) proteins link the plasma membrane to the actin cytoskeleton to generate apical structures, including Microvilli. Among many kinases implicated in ERM activation are the homologs LOK and SLK. CRISPR/Cas9 was used to knockout all ERM proteins or LOK/SLK in human cells. LOK/SLK knockout eliminates all ERM activating phosphorylation. The apical domain of cells lacking LOK/SLK or ERMs is strikingly similar and selectively altered, with loss of microvill, and junctional actin replaced by ectopic myosin-II containing apical stress-fiber-like structures. Constitutively active ezrin can reverse the phenotypes of either ERMs or LOK/SLK knockouts, showing that the major function of LOK/SLK is to activate ERMs. Both knockout lines have elevated active RhoA with concomitant enhanced myosin light chain phosphorylation, revealing that active ERMs are negative regulators of RhoA. As RhoA-GTP activates LOK/SLK to activate ERM proteins, the ability of active ERMs to negatively regulate RhoA-GTP represents a novel local feedback loop necessary for the proper apical morphology of epithelial cells.
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regulation of actin based apical structures on epithelial cells
Journal of Cell Science, 2018Co-Authors: Thaher Pelaseyed, Anthony BretscherAbstract:Cells of transporting epithelia are characterized by the presence of abundant F-actin-based Microvilli on their apical surfaces. Likewise, auditory hair cells have highly reproducible rows of apical stereocilia (giant Microvilli) that convert mechanical sound into an electrical signal. Analysis of mutations in deaf patients has highlighted the critical components of tip links between stereocilia, and related structures that contribute to the organization of Microvilli on epithelial cells have been found. Ezrin/radixin/moesin (ERM) proteins, which are activated by phosphorylation, provide a critical link between the plasma membrane and underlying actin cytoskeleton in surface structures. Here, we outline recent insights into how Microvilli and stereocilia are built, and the roles of tip links. Furthermore, we highlight how ezrin is locally regulated by phosphorylation, and that this is necessary to maintain polarity. Localized phosphorylation is achieved through an intricate coincidence detection mechanism that requires the membrane lipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and the apically localized ezrin kinase, lymphocyte-oriented kinase (LOK, also known as STK10) or Ste20-like kinase (SLK). We also discuss how ezrin-binding scaffolding proteins regulate Microvilli and how, despite these significant advances, it remains to be discovered how the cell polarity program ultimately interfaces with these processes.
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Structure, Regulation, and Functional Diversity of Microvilli on the Apical Domain of Epithelial Cells
Annual review of cell and developmental biology, 2015Co-Authors: Cécile Sauvanet, Jessica Wayt, Thaher Pelaseyed, Anthony BretscherAbstract:Microvilli are actin-based structures found on the apical aspect of many epithelial cells. In this review, we discuss different types of Microvilli, as well as comparisons with actin-based sensory stereocilia and filopodia. Much is known about the actin-bundling proteins of these structures; we summarize recent studies that focus on the components of the microvillar membrane. We pay special attention to mechanisms of membrane microfilament attachment by the ezrin/radixin/moesin family and regulation of this protein family. We also discuss the NHERF family of scaffolding proteins that are found in Microvilli and their role in Microvilli regulation. Microvilli on cultured cells are not static structures, and their dynamics and those of their components are discussed. Finally, we mention diseases related to Microvilli and outline questions that our current knowledge will allow the field to address in the near future.
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cordon bleu serves as a platform at the basal region of Microvilli where it regulates microvillar length through its wh2 domains
Molecular Biology of the Cell, 2014Co-Authors: Jessica Wayt, Anthony BretscherAbstract:Cordon Bleu (Cobl) is a WH2-containing protein believed to act as an actin nucleator. We show that it has a very specific localization in epithelial cells at the basal region of Microvilli, a localization unlikely to be involved in actin nucleation. The protein is localized by a central region between the N-terminal COBL domain and the three C-terminal WH2 domains. Ectopic expression of Cobl shortens apical Microvilli, and this requires functional WH2 domains. Proteomic studies reveal that the COBL domain binds several BAR-containing proteins, including SNX9, PACSIN 2/syndapin 2, and ASAP1. ASAP1 is recruited to the base of Microvilli by binding the COBL domain through its SH3. We propose that Cobl is localized to the basal region of Microvilli both to participate in length regulation and to recruit BAR proteins that associate with the curved membrane found at the microvillar base.
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dynamics of ezrin and ebp50 in regulating Microvilli on the apical aspect of epithelial cells
Biochemical Society Transactions, 2014Co-Authors: Raghuvir Viswanatha, Anthony Bretscher, Damien GarbettAbstract:Microvilli are found on the apical surface of epithelial cells. Recent studies on the microvillar proteins ezrin and EBP50 (ezrin/radixin/moesin-binding phosphoprotein of 50 kDa) have revealed both the dynamics and the regulation of microvillar components, and how a dynamic ezrin phosphocycle is necessary to confine Microvilli to the apical membrane. In the present review, we first summarize the background to allow us to place these advances in context.
Matthew J Tyska - One of the best experts on this subject based on the ideXlab platform.
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mitotic spindle positioning misp is an actin bundler that selectively stabilizes the rootlets of epithelial Microvilli
Social Science Research Network, 2021Co-Authors: Angelo E Morales, Cayetana Arnaiz, Evan S Krystofiak, Marija Zanic, Matthew J TyskaAbstract:Microvilli are conserved actin-based surface protrusions that have been repurposed throughout evolution to fulfill diverse cell functions. In the case of transporting epithelia, Microvilli are supported by a core of actin filaments bundled in parallel by villin, fimbrin, and espin. Remarkably, Microvilli biogenesis persists in mice lacking all three of these factors, suggesting the existence of unknown bundlers. We identified Mitotic Spindle Positioning (MISP) as an actin binding factor that localizes specifically to the rootlet end of the microvillus. MISP promotes rootlet elongation in cells, and purified MISP exhibits potent filament bundling activity in vitro. MISP-bundled filaments also recruit fimbrin, which further elongates and stabilizes bundles. MISP confinement to the rootlet is enforced by ezrin, which prevents decoration of the membrane-wrapped distal end of the core bundle. These discoveries reveal how epithelial cells optimize apical membrane surface area and offer insight on the remarkable robustness of Microvilli biogenesis.
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direct visualization of epithelial Microvilli biogenesis
Current Biology, 2021Co-Authors: Isabella M Gaeta, Leslie M Meenderink, Meagan M Postema, Caroline S Cencer, Matthew J TyskaAbstract:Microvilli are actin-bundle-supported surface protrusions that play essential roles in diverse epithelial functions. To develop our understanding of Microvilli biogenesis, we used live imaging to directly visualize protrusion growth at early stages of epithelial differentiation. Time-lapse data revealed that specific factors, including epidermal growth factor pathway substrate 8 (EPS8) and insulin-receptor tyrosine kinase substrate (IRTKS) (also known as BAIAP2L1), appear in diffraction-limited puncta at the cell surface and mark future sites of microvillus growth. New core actin bundles elongate from these puncta in parallel with the arrival of ezrin and subsequent plasma membrane encapsulation. In addition to de novo growth, we also observed that new Microvilli emerge from pre-existing protrusions. Moreover, we found that nascent Microvilli can also collapse, characterized first by loss of membrane wrapping and ezrin enrichment, followed by a sharp decrease in distal tip EPS8 and IRTKS levels, and ultimately disassembly of the core actin bundle itself. These studies are the first to offer a temporally resolved microvillus growth mechanism and highlight factors that participate in this process; they also provide important insights on the growth of apical specializations that will likely apply to diverse epithelial contexts.
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direct visualization of epithelial Microvilli biogenesis
bioRxiv, 2020Co-Authors: Isabella M Gaeta, Leslie M Meenderink, Meagan M Postema, Caroline S Cencer, Matthew J TyskaAbstract:Microvilli are actin bundle supported surface protrusions that play essential roles in diverse epithelial cell functions. To develop our understanding of Microvilli biogenesis, we used live imaging to directly visualize protrusion growth at early stages of epithelial differentiation. Time-lapse data revealed that an 9initiation complex9 enriched in EPS8 and IRTKS appears at future sites of microvillus growth minutes before core actin bundle assembly. Elongation of a new core bundle occurs in parallel with the arrival of EZRIN and plasma membrane encapsulation. In addition to de novo growth, we also observed that new Microvilli emerge from pre-existing protrusions. Additionally, we found that new Microvilli can also collapse, characterized first by loss of membrane wrapping and Ezrin enrichment, followed by a sharp decrease in distal tip EPS8 and IRTKS. These studies are the first to offer a temporally resolved microvillus growth mechanism and highlight critical factors that drive this process.
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brush border protocadherin cdhr2 promotes the elongation and maximized packing of Microvilli in vivo
Molecular Biology of the Cell, 2019Co-Authors: Julia A Pinette, Evan S Krystofiak, Suli Mao, Bryan A Millis, James J Faust, Matthew J TyskaAbstract:Transporting epithelial cells optimize their morphology for solute uptake by building an apical specialization: a dense array of Microvilli that serves to increase membrane surface area. In the intestinal tract, individual cells build thousands of Microvilli, which pack tightly to form the brush border. Recent studies implicate adhesion molecule CDHR2 in the regulation of microvillar packing via the formation of adhesion complexes between the tips of adjacent protrusions. To gain insight on how CDHR2 contributes to brush border morphogenesis and enterocyte function under native in vivo conditions, we generated mice lacking CDHR2 expression in the intestinal tract. Although CDHR2 knockout (KO) mice are viable, body weight trends lower and careful examination of tissue, cell, and brush border morphology revealed several perturbations that likely contribute to reduced functional capacity of KO intestine. In the absence of CDHR2, Microvilli are significantly shorter, and exhibit disordered packing and a 30% decrease in packing density. These structural perturbations are linked to decreased levels of key solute processing and transporting factors in the brush border. Thus, CDHR2 functions to elongate Microvilli and maximize their numbers on the apical surface, which together serve to increase the functional capacity of enterocyte.
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irtks baiap2l1 elongates epithelial Microvilli using eps8 dependent and independent mechanisms
Current Biology, 2018Co-Authors: Meagan M Postema, Nathan E Gregalarson, Abigail C Neininger, Matthew J TyskaAbstract:Transporting epithelial cells like those that line the gut build large arrays of actin-supported protrusions called Microvilli, which extend from the apical surface into luminal spaces to increase functional surface area. Although critical for maintaining physiological homeostasis, mechanisms controlling the formation of Microvilli remain poorly understood. Here, we report that the inverse-bin-amphiphysin-Rvs (I-BAR)-domain-containing protein insulin receptor tyrosine kinase substrate (IRTKS) (also known as BAIAP2L1) promotes the growth of epithelial Microvilli. Super-resolution microscopy and live imaging of differentiating epithelial cells revealed that IRTKS localizes to the distal tips of actively growing Microvilli via a mechanism that requires its N-terminal I-BAR domain. At microvillar tips, IRTKS promotes elongation through a mechanism involving its C-terminal actin-binding WH2 domain. IRTKS can also drive microvillar elongation using its SH3 domain to recruit the bundling protein EPS8 to microvillar tips. These results provide new insight on mechanisms that control microvillar growth during the differentiation of transporting epithelial cells and help explain why IRTKS is targeted by enteric pathogens that disrupt microvillar structure during infection of the intestinal epithelium.
Shigenori Miura - One of the best experts on this subject based on the ideXlab platform.
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fluid shear triggers Microvilli formation via mechanosensitive activation of trpv6
Nature Communications, 2015Co-Authors: Shigenori Miura, Koji Sato, Midori Katonegishi, Tetsuhiko Teshima, Shoji TakeuchiAbstract:Microvilli are cellular membrane protrusions present on differentiated epithelial cells, which can sense and interact with the surrounding fluid environment. Biochemical and genetic approaches have identified a set of factors involved in Microvilli formation; however, the underlying extrinsic regulatory mechanism of Microvilli formation remains largely unknown. Here we demonstrate that fluid shear stress (FSS), an external mechanical cue, serves as a trigger for Microvilli formation in human placental trophoblastic cells. We further reveal that the transient receptor potential, vanilloid family type-6 (TRPV6) calcium ion channel plays a critical role in flow-induced Ca2+ influx and Microvilli formation. TRPV6 regulates phosphorylation of Ezrin via a Ca2+-dependent phosphorylation of Akt; this molecular event is necessary for microvillar localization of Ezrin in response to FSS. Our findings provide molecular insight into the Microvilli-mediated mechanoresponsive cellular functions, such as epithelial absorption, signal perception and mechanotransduction. Microvilli on epithelial cells can sense the surrounding fluid environment, but the regulatory mechanism behind their formation is mostly unknown. Here Miura et al.show that fluid shear stress serves as a trigger for Microvilli formation via activation of the calcium ion channel TRPV6.
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fluid shear triggers Microvilli formation via mechanosensitive activation of trpv6
Nature Communications, 2015Co-Authors: Shigenori Miura, Koji Sato, Midori Katonegishi, Tetsuhiko Teshima, Shoji TakeuchiAbstract:Microvilli are cellular membrane protrusions present on differentiated epithelial cells, which can sense and interact with the surrounding fluid environment. Biochemical and genetic approaches have identified a set of factors involved in Microvilli formation; however, the underlying extrinsic regulatory mechanism of Microvilli formation remains largely unknown. Here we demonstrate that fluid shear stress (FSS), an external mechanical cue, serves as a trigger for Microvilli formation in human placental trophoblastic cells. We further reveal that the transient receptor potential, vanilloid family type-6 (TRPV6) calcium ion channel plays a critical role in flow-induced Ca(2+) influx and Microvilli formation. TRPV6 regulates phosphorylation of Ezrin via a Ca(2+)-dependent phosphorylation of Akt; this molecular event is necessary for microvillar localization of Ezrin in response to FSS. Our findings provide molecular insight into the Microvilli-mediated mechanoresponsive cellular functions, such as epithelial absorption, signal perception and mechanotransduction.
Shoji Takeuchi - One of the best experts on this subject based on the ideXlab platform.
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fluid shear triggers Microvilli formation via mechanosensitive activation of trpv6
Nature Communications, 2015Co-Authors: Shigenori Miura, Koji Sato, Midori Katonegishi, Tetsuhiko Teshima, Shoji TakeuchiAbstract:Microvilli are cellular membrane protrusions present on differentiated epithelial cells, which can sense and interact with the surrounding fluid environment. Biochemical and genetic approaches have identified a set of factors involved in Microvilli formation; however, the underlying extrinsic regulatory mechanism of Microvilli formation remains largely unknown. Here we demonstrate that fluid shear stress (FSS), an external mechanical cue, serves as a trigger for Microvilli formation in human placental trophoblastic cells. We further reveal that the transient receptor potential, vanilloid family type-6 (TRPV6) calcium ion channel plays a critical role in flow-induced Ca2+ influx and Microvilli formation. TRPV6 regulates phosphorylation of Ezrin via a Ca2+-dependent phosphorylation of Akt; this molecular event is necessary for microvillar localization of Ezrin in response to FSS. Our findings provide molecular insight into the Microvilli-mediated mechanoresponsive cellular functions, such as epithelial absorption, signal perception and mechanotransduction. Microvilli on epithelial cells can sense the surrounding fluid environment, but the regulatory mechanism behind their formation is mostly unknown. Here Miura et al.show that fluid shear stress serves as a trigger for Microvilli formation via activation of the calcium ion channel TRPV6.
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fluid shear triggers Microvilli formation via mechanosensitive activation of trpv6
Nature Communications, 2015Co-Authors: Shigenori Miura, Koji Sato, Midori Katonegishi, Tetsuhiko Teshima, Shoji TakeuchiAbstract:Microvilli are cellular membrane protrusions present on differentiated epithelial cells, which can sense and interact with the surrounding fluid environment. Biochemical and genetic approaches have identified a set of factors involved in Microvilli formation; however, the underlying extrinsic regulatory mechanism of Microvilli formation remains largely unknown. Here we demonstrate that fluid shear stress (FSS), an external mechanical cue, serves as a trigger for Microvilli formation in human placental trophoblastic cells. We further reveal that the transient receptor potential, vanilloid family type-6 (TRPV6) calcium ion channel plays a critical role in flow-induced Ca(2+) influx and Microvilli formation. TRPV6 regulates phosphorylation of Ezrin via a Ca(2+)-dependent phosphorylation of Akt; this molecular event is necessary for microvillar localization of Ezrin in response to FSS. Our findings provide molecular insight into the Microvilli-mediated mechanoresponsive cellular functions, such as epithelial absorption, signal perception and mechanotransduction.
Tetsuhiko Teshima - One of the best experts on this subject based on the ideXlab platform.
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fluid shear triggers Microvilli formation via mechanosensitive activation of trpv6
Nature Communications, 2015Co-Authors: Shigenori Miura, Koji Sato, Midori Katonegishi, Tetsuhiko Teshima, Shoji TakeuchiAbstract:Microvilli are cellular membrane protrusions present on differentiated epithelial cells, which can sense and interact with the surrounding fluid environment. Biochemical and genetic approaches have identified a set of factors involved in Microvilli formation; however, the underlying extrinsic regulatory mechanism of Microvilli formation remains largely unknown. Here we demonstrate that fluid shear stress (FSS), an external mechanical cue, serves as a trigger for Microvilli formation in human placental trophoblastic cells. We further reveal that the transient receptor potential, vanilloid family type-6 (TRPV6) calcium ion channel plays a critical role in flow-induced Ca2+ influx and Microvilli formation. TRPV6 regulates phosphorylation of Ezrin via a Ca2+-dependent phosphorylation of Akt; this molecular event is necessary for microvillar localization of Ezrin in response to FSS. Our findings provide molecular insight into the Microvilli-mediated mechanoresponsive cellular functions, such as epithelial absorption, signal perception and mechanotransduction. Microvilli on epithelial cells can sense the surrounding fluid environment, but the regulatory mechanism behind their formation is mostly unknown. Here Miura et al.show that fluid shear stress serves as a trigger for Microvilli formation via activation of the calcium ion channel TRPV6.
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fluid shear triggers Microvilli formation via mechanosensitive activation of trpv6
Nature Communications, 2015Co-Authors: Shigenori Miura, Koji Sato, Midori Katonegishi, Tetsuhiko Teshima, Shoji TakeuchiAbstract:Microvilli are cellular membrane protrusions present on differentiated epithelial cells, which can sense and interact with the surrounding fluid environment. Biochemical and genetic approaches have identified a set of factors involved in Microvilli formation; however, the underlying extrinsic regulatory mechanism of Microvilli formation remains largely unknown. Here we demonstrate that fluid shear stress (FSS), an external mechanical cue, serves as a trigger for Microvilli formation in human placental trophoblastic cells. We further reveal that the transient receptor potential, vanilloid family type-6 (TRPV6) calcium ion channel plays a critical role in flow-induced Ca(2+) influx and Microvilli formation. TRPV6 regulates phosphorylation of Ezrin via a Ca(2+)-dependent phosphorylation of Akt; this molecular event is necessary for microvillar localization of Ezrin in response to FSS. Our findings provide molecular insight into the Microvilli-mediated mechanoresponsive cellular functions, such as epithelial absorption, signal perception and mechanotransduction.