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Marshall-Burghardt S, Migueles-Ramírez RA, Lin Q, El Baba N, Saada R, Umar M, Mavalwala K, Hayer A. Excitable Rho dynamics control cell shape and motility by sequentially activating ERM proteins and actomyosin contractility. SCIENCE ADVANCES 2024; 10:eadn6858. [PMID: 39241071 PMCID: PMC11378911 DOI: 10.1126/sciadv.adn6858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 07/31/2024] [Indexed: 09/08/2024]
Abstract
Migration of endothelial and many other cells requires spatiotemporal regulation of protrusive and contractile cytoskeletal rearrangements that drive local cell shape changes. Unexpectedly, the small GTPase Rho, a crucial regulator of cell movement, has been reported to be active in both local cell protrusions and retractions, raising the question of how Rho activity can coordinate cell migration. Here, we show that Rho activity is absent in local protrusions and active during retractions. During retractions, Rho rapidly activated ezrin-radixin-moesin proteins (ERMs) to increase actin-membrane attachment, and, with a delay, nonmuscle myosin 2 (NM2). Rho activity was excitable, with NM2 acting as a slow negative feedback regulator. Strikingly, inhibition of SLK/LOK kinases, through which Rho activates ERMs, caused elongated cell morphologies, impaired Rho-induced cell contractions, and reverted Rho-induced blebbing. Together, our study demonstrates that Rho activity drives retractions by sequentially enhancing ERM-mediated actin-membrane attachment for force transmission and NM2-dependent contractility.
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Affiliation(s)
- Seph Marshall-Burghardt
- Department of Biology, Stewart Biology Building, McGill University, Montréal, Québec H3A 1B1, Canada
- Graduate Program in Biology, McGill University, Montréal, Québec, Canada
| | - Rodrigo A Migueles-Ramírez
- Department of Biology, Stewart Biology Building, McGill University, Montréal, Québec H3A 1B1, Canada
- PhD Program in Quantitative Life Sciences, McGill University, Montréal, Québec, Canada
| | - Qiyao Lin
- Department of Biology, Stewart Biology Building, McGill University, Montréal, Québec H3A 1B1, Canada
- Graduate Program in Biology, McGill University, Montréal, Québec, Canada
| | - Nada El Baba
- Department of Biology, Stewart Biology Building, McGill University, Montréal, Québec H3A 1B1, Canada
- Graduate Program in Biology, McGill University, Montréal, Québec, Canada
| | - Rayan Saada
- Department of Biology, Stewart Biology Building, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Mustakim Umar
- Department of Biology, Stewart Biology Building, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Kian Mavalwala
- Department of Biology, Stewart Biology Building, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Arnold Hayer
- Department of Biology, Stewart Biology Building, McGill University, Montréal, Québec H3A 1B1, Canada
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Dufrancais O, Verdys P, Plozza M, Métais A, Juzans M, Sanchez T, Bergert M, Halper J, Panebianco CJ, Mascarau R, Gence R, Arnaud G, Neji MB, Maridonneau-Parini I, Cabec VL, Boerckel JD, Pavlos NJ, Diz-Muñoz A, Lagarrigue F, Blin-Wakkach C, Carréno S, Poincloux R, Burkhardt JK, Raynaud-Messina B, Vérollet C. Moesin controls cell-cell fusion and osteoclast function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.13.593799. [PMID: 38798563 PMCID: PMC11118517 DOI: 10.1101/2024.05.13.593799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Cell-cell fusion is an evolutionarily conserved process that is essential for many functions, including fertilisation and the formation of placenta, muscle and osteoclasts, multinucleated cells that are unique in their ability to resorb bone. The mechanisms of osteoclast multinucleation involve dynamic interactions between the actin cytoskeleton and the plasma membrane that are still poorly characterized. Here, we found that moesin, a cytoskeletal linker protein member of the Ezrin/Radixin/Moesin (ERM) protein family, is activated during osteoclast maturation and plays an instrumental role in both osteoclast fusion and function. In mouse and human osteoclast precursors, moesin inhibition favors their ability to fuse into multinucleated osteoclasts. Accordingly, we demonstrated that moesin depletion decreases membrane-to-cortex attachment and enhances the formation of tunneling nanotubes (TNTs), F-actin-based intercellular bridges that we reveal here to trigger cell-cell fusion. Moesin also controls HIV-1- and inflammation-induced cell fusion. In addition, moesin regulates the formation of the sealing zone, the adhesive structure determining osteoclast bone resorption area, and thus controls bone degradation, via a β3-integrin/RhoA/SLK pathway. Supporting our results, moesin - deficient mice present a reduced density of trabecular bones and increased osteoclast abundance and activity. These findings provide a better understanding of the regulation of cell-cell fusion and osteoclast biology, opening new opportunities to specifically target osteoclast activity in bone disease therapy.
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3
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Verdys P, Rey Barroso J, Girel A, Vermeil J, Bergert M, Sanchez T, Métais A, Mangeat T, Bellard E, Bigot C, Astarie-Dequeker C, Labrousse A, Girard JP, Maridonneau-Parini I, Vérollet C, Lagarrigue F, Diz-Muñoz A, Heuvingh J, Piel M, du Roure O, Le Cabec V, Carréno S, Poincloux R. Ezrin, radixin, and moesin are dispensable for macrophage migration and cellular cortex mechanics. EMBO J 2024:10.1038/s44318-024-00173-7. [PMID: 39026000 DOI: 10.1038/s44318-024-00173-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 06/17/2024] [Accepted: 07/01/2024] [Indexed: 07/20/2024] Open
Abstract
The cellular cortex provides crucial mechanical support and plays critical roles during cell division and migration. The proteins of the ERM family, comprised of ezrin, radixin, and moesin, are central to these processes by linking the plasma membrane to the actin cytoskeleton. To investigate the contributions of the ERM proteins to leukocyte migration, we generated single and triple ERM knockout macrophages. Surprisingly, we found that even in the absence of ERM proteins, macrophages still form the different actin structures promoting cell migration, such as filopodia, lamellipodia, podosomes, and ruffles. Furthermore, we discovered that, unlike every other cell type previously investigated, the single or triple knockout of ERM proteins does not affect macrophage migration in diverse contexts. Finally, we demonstrated that the loss of ERMs in macrophages does not affect the mechanical properties of their cortex. These findings challenge the notion that ERMs are universally essential for cortex mechanics and cell migration and support the notion that the macrophage cortex may have diverged from that of other cells to allow for their uniquely adaptive cortical plasticity.
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Affiliation(s)
- Perrine Verdys
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Canada
| | - Javier Rey Barroso
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Adeline Girel
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Joseph Vermeil
- PMMH, ESPCI Paris, PSL University, CNRS, Université Paris Cité, Sorbonne Université, Paris, France
| | - Martin Bergert
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Thibaut Sanchez
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Arnaud Métais
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Thomas Mangeat
- LITC Core Facility, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 31062, Toulouse, France
| | - Elisabeth Bellard
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Equipe Labellisée Ligue Contre le Cancer, Paris, France
| | - Claire Bigot
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Catherine Astarie-Dequeker
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Arnaud Labrousse
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Jean-Philippe Girard
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Equipe Labellisée Ligue Contre le Cancer, Paris, France
| | - Isabelle Maridonneau-Parini
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Christel Vérollet
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Frédéric Lagarrigue
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Alba Diz-Muñoz
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Julien Heuvingh
- PMMH, ESPCI Paris, PSL University, CNRS, Université Paris Cité, Sorbonne Université, Paris, France
| | - Matthieu Piel
- Institut Curie and Institut Pierre Gilles de Gennes, PSL University, CNRS, Paris, France
| | - Olivia du Roure
- PMMH, ESPCI Paris, PSL University, CNRS, Université Paris Cité, Sorbonne Université, Paris, France
| | - Véronique Le Cabec
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France.
| | - Sébastien Carréno
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Canada.
| | - Renaud Poincloux
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France.
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Hosawi MM, Cheng J, Fankhaenel M, Przewloka MR, Elias S. Interplay between the plasma membrane and cell-cell adhesion maintains epithelial identity for correct polarised cell divisions. J Cell Sci 2024; 137:jcs261701. [PMID: 37888135 PMCID: PMC10729819 DOI: 10.1242/jcs.261701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 10/17/2023] [Indexed: 10/28/2023] Open
Abstract
Polarised epithelial cell divisions represent a fundamental mechanism for tissue maintenance and morphogenesis. Morphological and mechanical changes in the plasma membrane influence the organisation and crosstalk of microtubules and actin at the cell cortex, thereby regulating the mitotic spindle machinery and chromosome segregation. Yet, the precise mechanisms linking plasma membrane remodelling to cell polarity and cortical cytoskeleton dynamics to ensure accurate execution of mitosis in mammalian epithelial cells remain poorly understood. Here, we manipulated the density of mammary epithelial cells in culture, which led to several mitotic defects. Perturbation of cell-cell adhesion formation impairs the dynamics of the plasma membrane, affecting the shape and size of mitotic cells and resulting in defects in mitotic progression and the generation of daughter cells with aberrant architecture. In these conditions, F- actin-astral microtubule crosstalk is impaired, leading to mitotic spindle misassembly and misorientation, which in turn contributes to chromosome mis-segregation. Mechanistically, we identify S100 Ca2+-binding protein A11 (S100A11) as a key membrane-associated regulator that forms a complex with E-cadherin (CDH1) and the leucine-glycine-asparagine repeat protein LGN (also known as GPSM2) to coordinate plasma membrane remodelling with E-cadherin-mediated cell adhesion and LGN-dependent mitotic spindle machinery. Thus, plasma membrane-mediated maintenance of mammalian epithelial cell identity is crucial for correct execution of polarised cell divisions, genome maintenance and safeguarding tissue integrity.
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Affiliation(s)
- Manal M. Hosawi
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Jiaoqi Cheng
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Maria Fankhaenel
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Marcin R. Przewloka
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Salah Elias
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
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5
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Bock F, Dong X, Li S, Viquez OM, Sha E, Tantengco M, Hennen EM, Plosa E, Ramezani A, Brown KL, Whang YM, Terker AS, Arroyo JP, Harrison DG, Fogo A, Brakebusch CH, Pozzi A, Zent R. Rac1 promotes kidney collecting duct repair by mechanically coupling cell morphology to mitotic entry. SCIENCE ADVANCES 2024; 10:eadi7840. [PMID: 38324689 PMCID: PMC10849615 DOI: 10.1126/sciadv.adi7840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 01/03/2024] [Indexed: 02/09/2024]
Abstract
Prolonged obstruction of the ureter, which leads to injury of the kidney collecting ducts, results in permanent structural damage, while early reversal allows for repair. Cell structure is defined by the actin cytoskeleton, which is dynamically organized by small Rho guanosine triphosphatases (GTPases). In this study, we identified the Rho GTPase, Rac1, as a driver of postobstructive kidney collecting duct repair. After the relief of ureteric obstruction, Rac1 promoted actin cytoskeletal reconstitution, which was required to maintain normal mitotic morphology allowing for successful cell division. Mechanistically, Rac1 restricted excessive actomyosin activity that stabilized the negative mitotic entry kinase Wee1. This mechanism ensured mechanical G2-M checkpoint stability and prevented premature mitotic entry. The repair defects following injury could be rescued by direct myosin inhibition. Thus, Rac1-dependent control of the actin cytoskeleton integrates with the cell cycle to mediate kidney tubular repair by preventing dysmorphic cells from entering cell division.
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Affiliation(s)
- Fabian Bock
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Veterans Affairs Hospital, Tennessee Valley Healthcare System, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Xinyu Dong
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Shensen Li
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Olga M. Viquez
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Eric Sha
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Matthew Tantengco
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Elizabeth M. Hennen
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Erin Plosa
- Division of Neonatology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alireza Ramezani
- Interdisciplinary Center for Quantitative Modeling in Biology, University of California, Riverside, CA, USA
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | - Kyle L. Brown
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Young Mi Whang
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Andrew S. Terker
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Juan Pablo Arroyo
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Veterans Affairs Hospital, Tennessee Valley Healthcare System, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, USA
| | - David G. Harrison
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Agnes Fogo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Cord H. Brakebusch
- Biotech Research Center, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Ambra Pozzi
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Veterans Affairs Hospital, Tennessee Valley Healthcare System, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Physiology and Molecular Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Roy Zent
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Veterans Affairs Hospital, Tennessee Valley Healthcare System, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
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6
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Morel A, Douat C, Blangy A, Vives V. Bone resorption by osteoclasts involves fine tuning of RHOA activity by its microtubule-associated exchange factor GEF-H1. Front Physiol 2024; 15:1342024. [PMID: 38312316 PMCID: PMC10834693 DOI: 10.3389/fphys.2024.1342024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/08/2024] [Indexed: 02/06/2024] Open
Abstract
Bone health is controlled by the balance between bone formation by osteoblasts and degradation by osteoclasts. A disequilibrium in favor of bone resorption leads to osteolytic diseases characterized by decreased bone density. Osteoclastic resorption is dependent on the assembly of an adhesion structure: the actin ring, also called podosome belt or sealing zone, which is composed of a unique patterning of podosomes stabilized by microtubules. A better understanding of the molecular mechanisms regulating the crosstalk between actin cytoskeleton and microtubules network is key to find new treatments to inhibit bone resorption. Evidence points to the importance of the fine tuning of the activity of the small GTPase RHOA for the formation and maintenance of the actin ring, but the underlying mechanism is not known. We report here that actin ring disorganization upon microtubule depolymerization is mediated by the activation of the RHOA-ROCK signaling pathway. We next show the involvement of GEF-H1, one of RHOA guanine exchange factor highly expressed in osteoclasts, which has the particularity of being negatively regulated by sequestration on microtubules. Using a CRISPR/Cas9-mediated GEF-H1 knock-down osteoclast model, we demonstrate that RHOA activation upon microtubule depolymerization is mediated by GEF-H1 release. Interestingly, although lower levels of GEF-H1 did not impact sealing zone formation in the presence of an intact microtubule network, sealing zone was smaller leading to impaired resorption. Altogether, these results suggest that a fine tuning of GEF-H1 through its association with microtubules, and consequently of RHOA activity, is essential for osteoclast sealing zone stability and resorption function.
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Affiliation(s)
- Anne Morel
- CRBM (Montpellier cell Biology Research Center), Univ Montpellier, CNRS (National Center for Scientific Research), Montpellier, France
| | - Christophe Douat
- CRBM (Montpellier cell Biology Research Center), Univ Montpellier, CNRS (National Center for Scientific Research), Montpellier, France
| | - Anne Blangy
- CRBM (Montpellier cell Biology Research Center), Univ Montpellier, CNRS (National Center for Scientific Research), Montpellier, France
| | - Virginie Vives
- CRBM (Montpellier cell Biology Research Center), Univ Montpellier, CNRS (National Center for Scientific Research), Montpellier, France
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7
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Lade JM, Andrade MR, Undem C, Walker J, Jiang H, Yun X, Shimoda LA. Hypoxia enhances interactions between Na +/H + exchanger isoform 1 and actin filaments via ezrin in pulmonary vascular smooth muscle. Front Physiol 2023; 14:1108304. [PMID: 36926194 PMCID: PMC10011449 DOI: 10.3389/fphys.2023.1108304] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 01/24/2023] [Indexed: 03/08/2023] Open
Abstract
Exposure to hypoxia, due to high altitude or chronic lung disease, leads to structural changes in the pulmonary vascular wall, including hyperplasia and migration of pulmonary arterial smooth muscle cells (PASMCs). Previous studies showed that hypoxia upregulates the expression of Na+/H+ exchanger isoform 1 (NHE1) and that inhibition or loss of NHE1 prevents hypoxia-induced PASMC migration and proliferation. The exact mechanism by which NHE1 controls PASMC function has not been fully delineated. In fibroblasts, NHE1 has been shown to act as a membrane anchor for actin filaments, via binding of the adaptor protein, ezrin. Thus, in this study, we tested the role of ezrin and NHE1/actin interactions in controlling PASMC function. Using rat PASMCs exposed to in vitro hypoxia (4% O2, 24 h) we found that hypoxic exposure increased phosphorylation (activation) of ezrin, and promoted interactions between NHE1, phosphorylated ezrin and smooth muscle specific α-actin (SMA) as measured via immunoprecipitation and co-localization. Overexpression of wild-type human NHE1 in the absence of hypoxia was sufficient to induce PASMC migration and proliferation, whereas inhibiting ezrin phosphorylation with NSC668394 suppressed NHE1/SMA co-localization and migration in hypoxic PASMCs. Finally, overexpressing a version of human NHE1 in which amino acids were mutated to prevent NHE1/ezrin/SMA interactions was unable to increase PASMC migration and proliferation despite exhibiting normal Na+/H+ exchange activity. From these results, we conclude that hypoxic exposure increases ezrin phosphorylation in PASMCs, leading to enhanced ezrin/NHE1/SMA interaction. We further speculate that these interactions promote anchoring of the actin cytoskeleton to the membrane to facilitate the changes in cell movement and shape required for migration and proliferation.
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Affiliation(s)
- Julie M Lade
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
| | - Manuella R Andrade
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Clark Undem
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
| | - Jasmine Walker
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
| | - Haiyang Jiang
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
| | - Xin Yun
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
| | - Larissa A Shimoda
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
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