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Pinello JF, Loidl J, Seltzer ES, Cassidy-Hanley D, Kolbin D, Abdelatif A, Rey FA, An R, Newberger NJ, Bisharyan Y, Papoyan H, Byun H, Aguilar HC, Lai AL, Freed JH, Maugel T, Cole ES, Clark TG. Novel requirements for HAP2/GCS1-mediated gamete fusion in Tetrahymena. iScience 2024; 27:110146. [PMID: 38904066 PMCID: PMC11187246 DOI: 10.1016/j.isci.2024.110146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 04/29/2024] [Accepted: 05/27/2024] [Indexed: 06/22/2024] Open
Abstract
The ancestral gamete fusion protein, HAP2/GCS1, plays an essential role in fertilization in a broad range of taxa. To identify factors that may regulate HAP2/GCS1 activity, we screened mutants of the ciliate Tetrahymena thermophila for behaviors that mimic Δhap2/gcs1 knockout phenotypes in this species. Using this approach, we identified two new genes, GFU1 and GFU2, whose products are necessary for membrane pore formation following mating type recognition and adherence. GFU2 is predicted to be a single-pass transmembrane protein, while GFU1, though lacking obvious transmembrane domains, has the potential to interact directly with membrane phospholipids in the cytoplasm. Like Tetrahymena HAP2/GCS1, expression of GFU1 is required in both cells of a mating pair for efficient fusion to occur. To explain these bilateral requirements, we propose a model that invokes cooperativity between the fusion machinery on apposed membranes of mating cells and accounts for successful fertilization in Tetrahymena's multiple mating type system.
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Affiliation(s)
- Jennifer F. Pinello
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Josef Loidl
- Department of Chromosome Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Ethan S. Seltzer
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Donna Cassidy-Hanley
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Daniel Kolbin
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Anhar Abdelatif
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Félix A. Rey
- Unité de Virologie Structurale, Institut Pasteur, 75724 Paris, France
- CNRS UMR 3569, 75724 Paris, France
| | - Rocky An
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Nicole J. Newberger
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Yelena Bisharyan
- Office of Technology Development, Harvard University, Cambridge, MA 02138, USA
| | - Hayk Papoyan
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Haewon Byun
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Hector C. Aguilar
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Alex L. Lai
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Jack H. Freed
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Timothy Maugel
- Department of Biology, Laboratory for Biological Ultrastructure, University of Maryland, College Park, MD 20742, USA
| | - Eric S. Cole
- Biology Department, St. Olaf College, Northfield, MN 55057, USA
| | - Theodore G. Clark
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
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2
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Mansat M, Kpotor AO, Chicanne G, Picot M, Mazars A, Flores-Flores R, Payrastre B, Hnia K, Viaud J. MTM1-mediated production of phosphatidylinositol 5-phosphate fuels the formation of podosome-like protrusions regulating myoblast fusion. Proc Natl Acad Sci U S A 2024; 121:e2217971121. [PMID: 38805272 PMCID: PMC11161799 DOI: 10.1073/pnas.2217971121] [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: 10/21/2022] [Accepted: 04/10/2024] [Indexed: 05/30/2024] Open
Abstract
Myogenesis is a multistep process that requires a spatiotemporal regulation of cell events resulting finally in myoblast fusion into multinucleated myotubes. Most major insights into the mechanisms underlying fusion seem to be conserved from insects to mammals and include the formation of podosome-like protrusions (PLPs) that exert a driving force toward the founder cell. However, the machinery that governs this process remains poorly understood. In this study, we demonstrate that MTM1 is the main enzyme responsible for the production of phosphatidylinositol 5-phosphate, which in turn fuels PI5P 4-kinase α to produce a minor and functional pool of phosphatidylinositol 4,5-bisphosphate that concentrates in PLPs containing the scaffolding protein Tks5, Dynamin-2, and the fusogenic protein Myomaker. Collectively, our data reveal a functional crosstalk between a PI-phosphatase and a PI-kinase in the regulation of PLP formation.
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Affiliation(s)
- Mélanie Mansat
- INSERM UMR1297, University of Toulouse 3, Institute of Metabolic and Cardiovascular Diseases (I2MC)31432, Toulouse Cedex 04, France
| | - Afi Oportune Kpotor
- INSERM UMR1297, University of Toulouse 3, Institute of Metabolic and Cardiovascular Diseases (I2MC)31432, Toulouse Cedex 04, France
| | - Gaëtan Chicanne
- INSERM UMR1297, University of Toulouse 3, Institute of Metabolic and Cardiovascular Diseases (I2MC)31432, Toulouse Cedex 04, France
| | - Mélanie Picot
- INSERM UMR1297, University of Toulouse 3, Institute of Metabolic and Cardiovascular Diseases (I2MC)31432, Toulouse Cedex 04, France
| | - Anne Mazars
- INSERM UMR1297, University of Toulouse 3, Institute of Metabolic and Cardiovascular Diseases (I2MC)31432, Toulouse Cedex 04, France
| | - Rémy Flores-Flores
- INSERM UMR1297, University of Toulouse 3, Institute of Metabolic and Cardiovascular Diseases (I2MC)31432, Toulouse Cedex 04, France
| | - Bernard Payrastre
- INSERM UMR1297, University of Toulouse 3, Institute of Metabolic and Cardiovascular Diseases (I2MC)31432, Toulouse Cedex 04, France
- Hematology Laboratory, University Hospital of Toulouse31059, Toulouse Cedex 03, France
| | - Karim Hnia
- INSERM UMR1297, University of Toulouse 3, Institute of Metabolic and Cardiovascular Diseases (I2MC)31432, Toulouse Cedex 04, France
| | - Julien Viaud
- INSERM UMR1297, University of Toulouse 3, Institute of Metabolic and Cardiovascular Diseases (I2MC)31432, Toulouse Cedex 04, France
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3
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Wherley TJ, Thomas S, Millay DP, Saunders T, Roy S. Molecular regulation of myocyte fusion. Curr Top Dev Biol 2024; 158:53-82. [PMID: 38670716 DOI: 10.1016/bs.ctdb.2024.01.016] [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] [Indexed: 04/28/2024]
Abstract
Myocyte fusion is a pivotal process in the development and regeneration of skeletal muscle. Failure during fusion can lead to a range of developmental as well as pathological consequences. This review aims to comprehensively explore the intricate processes underlying myocyte fusion, from the molecular to tissue scale. We shed light on key players, such as the muscle-specific fusogens - Myomaker and Myomixer, in addition to some lesser studied molecules contributing to myocyte fusion. Conserved across vertebrates, Myomaker and Myomixer play a crucial role in driving the merger of plasma membranes of fusing myocytes, ensuring the formation of functional muscle syncytia. Our multiscale approach also delves into broader cell and tissue dynamics that orchestrate the timing and positioning of fusion events. In addition, we explore the relevance of muscle fusogens to human health and disease. Mutations in fusogen genes have been linked to congenital myopathies, providing unique insights into the molecular basis of muscle diseases. We conclude with a discussion on potential therapeutic avenues that may emerge from manipulating the myocyte fusion process to remediate skeletal muscle disorders.
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Affiliation(s)
- Tanner J Wherley
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Serena Thomas
- Warwick Medical School, University of Warwick, Coventry, United Kingdom; Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore, Singapore
| | - Douglas P Millay
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
| | - Timothy Saunders
- Warwick Medical School, University of Warwick, Coventry, United Kingdom; Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore, Singapore.
| | - Sudipto Roy
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore, Singapore; Department of Pediatrics, National University of Singapore, Singapore, Singapore.
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4
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Shakarchy A, Zarfati G, Hazak A, Mealem R, Huk K, Ziv T, Avinoam O, Zaritsky A. Machine learning inference of continuous single-cell state transitions during myoblast differentiation and fusion. Mol Syst Biol 2024; 20:217-241. [PMID: 38238594 PMCID: PMC10912675 DOI: 10.1038/s44320-024-00010-3] [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: 03/02/2023] [Revised: 12/19/2023] [Accepted: 01/04/2024] [Indexed: 03/06/2024] Open
Abstract
Cells modify their internal organization during continuous state transitions, supporting functions from cell division to differentiation. However, tools to measure dynamic physiological states of individual transitioning cells are lacking. We combined live-cell imaging and machine learning to monitor ERK1/2-inhibited primary murine skeletal muscle precursor cells, that transition rapidly and robustly from proliferating myoblasts to post-mitotic myocytes and then fuse, forming multinucleated myotubes. Our models, trained using motility or actin intensity features from single-cell tracking data, effectively tracked real-time continuous differentiation, revealing that differentiation occurs 7.5-14.5 h post induction, followed by fusion ~3 h later. Co-inhibition of ERK1/2 and p38 led to differentiation without fusion. Our model inferred co-inhibition leads to terminal differentiation, indicating that p38 is specifically required for transitioning from terminal differentiation to fusion. Our model also predicted that co-inhibition leads to changes in actin dynamics. Mass spectrometry supported these in silico predictions and suggested novel fusion and maturation regulators downstream of differentiation. Collectively, this approach can be adapted to various biological processes to uncover novel links between dynamic single-cell states and their functional outcomes.
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Affiliation(s)
- Amit Shakarchy
- Department of Software and Information Systems Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel
| | - Giulia Zarfati
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, 761001, Israel
| | - Adi Hazak
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, 761001, Israel
| | - Reut Mealem
- Department of Software and Information Systems Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel
| | - Karina Huk
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, 761001, Israel
| | - Tamar Ziv
- The Smoler Proteomics Center, Lorry I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion Israel Institute of Technology, Haifa, 3200003, Israel
| | - Ori Avinoam
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, 761001, Israel.
| | - Assaf Zaritsky
- Department of Software and Information Systems Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel.
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5
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Kloc M, Tworzydło W, Szklarzewicz T. Germline and Somatic Cell Syncytia in Insects. Results Probl Cell Differ 2024; 71:47-63. [PMID: 37996672 DOI: 10.1007/978-3-031-37936-9_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Syncytia are common in the animal and plant kingdoms both under normal and pathological conditions. They form through cell fusion or division of a founder cell without cytokinesis. A particular type of syncytia occurs in invertebrate and vertebrate gametogenesis when the founder cell divides several times with partial cytokinesis producing a cyst (nest) of germ line cells connected by cytoplasmic bridges. The ultimate destiny of the cyst's cells differs between animal groups. Either all cells of the cyst become the gametes or some cells endoreplicate or polyploidize to become the nurse cells (trophocytes). Although many types of syncytia are permanent, the germ cell syncytium is temporary, and eventually, it separates into individual gametes. In this chapter, we give an overview of syncytium types and focus on the germline and somatic cell syncytia in various groups of insects. We also describe the multinuclear giant cells, which form through repetitive nuclear divisions and cytoplasm hypertrophy, but without cell fusion, and the accessory nuclei, which bud off the oocyte nucleus, migrate to its cortex and become included in the early embryonic syncytium.
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Affiliation(s)
- Malgorzata Kloc
- The Houston Methodist Research Institute, Houston, TX, USA.
- The Houston Methodist Hospital, Department of Surgery, Houston, TX, USA.
- Department of Genetics, MD Anderson Cancer Center, The University of Texas, Houston, TX, USA.
| | - Wacław Tworzydło
- Department of Developmental Biology and Invertebrate Morphology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
| | - Teresa Szklarzewicz
- Department of Developmental Biology and Invertebrate Morphology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
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6
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Wu P, Yong P, Zhang Z, Xu R, Shang R, Shi J, Zhang J, Bi P, Chen E, Du S. Loss of Myomixer Results in Defective Myoblast Fusion, Impaired Muscle Growth, and Severe Myopathy in Zebrafish. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2022; 24:1023-1038. [PMID: 36083384 PMCID: PMC10112271 DOI: 10.1007/s10126-022-10159-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 08/25/2022] [Indexed: 06/15/2023]
Abstract
The development and growth of fish skeletal muscles require myoblast fusion to generate multinucleated myofibers. While zebrafish fast-twitch muscle can fuse to generate multinucleated fibers, the slow-twitch muscle fibers remain mononucleated in zebrafish embryos and larvae. The mechanism underlying the fiber-type-specific control of fusion remains elusive. Recent genetic studies using mice identified a long-sought fusion factor named Myomixer. To understand whether Myomixer is involved in the fiber-type specific fusion, we analyzed the transcriptional regulation of myomixer expression and characterized the muscle growth phenotype upon genetic deletion of myomixer in zebrafish. The data revealed that overexpression of Sonic Hedgehog (Shh) drastically inhibited myomixer expression and blocked myoblast fusion, recapitulating the phenotype upon direct genetic deletion of myomixer from zebrafish. The fusion defect in myomixer mutant embryos could be faithfully rescued upon re-expression of zebrafish myomixer gene or its orthologs from shark or human. Interestingly, myomixer mutant fish survived to adult stage though were notably smaller than wildtype siblings. Severe myopathy accompanied by the uncontrolled adipose infiltration was observed in both fast and slow muscle tissues of adult myomixer mutants. Collectively, our data highlight an indispensable role of myomixer gene for cell fusion during both embryonic muscle development and post-larval muscle growth.
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Affiliation(s)
- Ping Wu
- Department of Biochemistry and Molecular Biology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, USA
- Department of Bioengineering and Environmental Science, Changsha University, Changsha, China
| | - Pengzheng Yong
- Department of Biochemistry and Molecular Biology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, USA
| | - Zhanxiong Zhang
- Department of Biochemistry and Molecular Biology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, USA
| | - Rui Xu
- Department of Biochemistry and Molecular Biology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, USA
| | - Renjie Shang
- Center for Molecular Medicine & Department of Genetics, University of Georgia, Athens, USA
| | - Jun Shi
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, USA
- College of Marine Sciences, South China Agricultural University, Guangzhou, China
| | - Jianshe Zhang
- Department of Bioengineering and Environmental Science, Changsha University, Changsha, China
| | - Pengpeng Bi
- Center for Molecular Medicine & Department of Genetics, University of Georgia, Athens, USA
| | - Elizabeth Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, USA
| | - Shaojun Du
- Department of Biochemistry and Molecular Biology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, USA.
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7
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Phosphatidylserine orchestrates Myomerger membrane insertions to drive myoblast fusion. Proc Natl Acad Sci U S A 2022; 119:e2202490119. [PMID: 36095199 PMCID: PMC9499509 DOI: 10.1073/pnas.2202490119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Muscle cell fusion is a multistep process where the final step of the reaction drives progression beyond early hemifusion events to complete fusion. This step requires activity of the muscle-specific fusogen Myomerger, a single-pass transmembrane protein containing 84 amino acids with an ectodomain that includes two α-helices. Previous studies have demonstrated that Myomerger acts by destabilizing membranes through generation of elastic stresses in the outer leaflet of the plasma membrane. An obvious question is how such destabilizing activity might be regulated to avoid membrane and cellular damage, and how the two juxtaposed helices cooperate in fusion. Using cellular fusion assays and in vitro liposome assays, we report that the two helices possess unique characteristics, both of which are needed for full activity of the protein. We demonstrate that externalized phosphatidylserine (PS), a lipid previously implicated in myoblast fusion, has a determinant role in the regulation of Myomerger activity. The membrane-proximal, amphipathic Helix-1 is normally disordered and its α-helical structure is induced by PS, making membrane interactions more efficacious. The distal, more hydrophobic Helix-2 is intrinsically ordered, possesses an ability to insert into membranes, and augments the membrane-stressing effects of Helix-1. These data reveal that Myomerger fusogenic activity is an exquisitely orchestrated event involving its two ectodomain helices, which are controlled by membrane lipid composition, providing an explanation as to how its membrane-stressing activity is spatially and temporally regulated during the final step of myoblast fusion.
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8
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Mendieta-Serrano MA, Dhar S, Ng BH, Narayanan R, Lee JJY, Ong HT, Toh PJY, Röllin A, Roy S, Saunders TE. Slow muscles guide fast myocyte fusion to ensure robust myotome formation despite the high spatiotemporal stochasticity of fusion events. Dev Cell 2022; 57:2095-2110.e5. [PMID: 36027918 DOI: 10.1016/j.devcel.2022.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 06/07/2022] [Accepted: 08/05/2022] [Indexed: 11/03/2022]
Abstract
Skeletal myogenesis is dynamic, and it involves cell-shape changes together with cell fusion and rearrangements. However, the final muscle arrangement is highly organized with striated fibers. By combining live imaging with quantitative analyses, we dissected fast-twitch myocyte fusion within the zebrafish myotome in toto. We found a strong mediolateral bias in fusion timing; however, at a cellular scale, there was heterogeneity in cell shape and the relationship between initial position of fast myocytes and resulting fusion partners. We show that the expression of the fusogen myomaker is permissive, but not instructive, in determining the spatiotemporal fusion pattern. Rather, we observed a close coordination between slow muscle rearrangements and fast myocyte fusion. In mutants that lack slow fibers, the spatiotemporal fusion pattern is substantially noisier. We propose a model in which slow muscles guide fast myocytes by funneling them close together, enhancing fusion probability. Thus, despite fusion being highly stochastic, a robust myotome structure emerges at the tissue scale.
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Affiliation(s)
| | - Sunandan Dhar
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore; Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Boon Heng Ng
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Rachna Narayanan
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore; Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Jorge J Y Lee
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Hui Ting Ong
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Pearlyn Jia Ying Toh
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Adrian Röllin
- Department of Statistics and Data Science, National University of Singapore, Singapore 117546, Singapore
| | - Sudipto Roy
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore 138673, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore; Department of Paediatrics, National University of Singapore, Singapore 119228, Singapore.
| | - Timothy E Saunders
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore; Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK; Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore 138673, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore.
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