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Myogenin promotes myocyte fusion to balance fibre number and size. Nat Commun 2018; 9:4232. [PMID: 30315160 PMCID: PMC6185967 DOI: 10.1038/s41467-018-06583-6] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 08/31/2018] [Indexed: 01/01/2023] Open
Abstract
Each skeletal muscle acquires its unique size before birth, when terminally differentiating myocytes fuse to form a defined number of multinucleated myofibres. Although mice in which the transcription factor Myogenin is mutated lack most myogenesis and die perinatally, a specific cell biological role for Myogenin has remained elusive. Here we report that loss of function of zebrafish myog prevents formation of almost all multinucleated muscle fibres. A second, Myogenin-independent, fusion pathway in the deep myotome requires Hedgehog signalling. Lack of Myogenin does not prevent terminal differentiation; the smaller myotome has a normal number of myocytes forming more mononuclear, thin, albeit functional, fast muscle fibres. Mechanistically, Myogenin binds to the myomaker promoter and is required for expression of myomaker and other genes essential for myocyte fusion. Adult myog mutants display reduced muscle mass, decreased fibre size and nucleation. Adult-derived myog mutant myocytes show persistent defective fusion ex vivo. Myogenin is therefore essential for muscle homeostasis, regulating myocyte fusion to determine both muscle fibre number and size. Loss of the transcription factor Myogenin in mice reduces skeletal myogenesis and leads to perinatal death but how Myogenin regulates muscle formation is unclear. Here, the authors show that zebrafish Myogenin enhances Myomaker expression, muscle cell fusion and myotome size, yet decreases fast muscle fibre number.
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Valer FB, Machado MCR, Silva-Junior RMP, Ramos RGP. Expression of Hbs, Kirre, and Rst during Drosophila ovarian development. Genesis 2018; 56:e23242. [PMID: 30114331 DOI: 10.1002/dvg.23242] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 07/22/2018] [Accepted: 07/23/2018] [Indexed: 12/16/2022]
Abstract
The Irre cell-recognition module (IRM) is a group of evolutionarily conserved and structurally related transmembrane glycoproteins of the immunoglobulin superfamily. In Drosophila melanogaster, it comprises the products of the genes roughest (rst; also known as irreC-rst), kin-of-irre (kirre; also known as duf), sticks-and-stones (sns), and hibris (hbs). In this model organism, the behavior of this group of proteins as a partly redundant functional unit mediating selective cell recognition was demonstrated in a variety of developmental contexts, but their possible involvement in ovarian development and oogenesis has not been investigated, notwithstanding the fact that some rst mutant alleles are also female sterile. Here, we show that IRM genes are dynamically and, to some extent, coordinately transcribed in both pupal and adult ovaries. Additionally, the spatial distribution of Hbs, Kirre, and Rst proteins indicates that they perform cooperative, although largely nonredundant, functions. Finally, phenotypical characterization of three different female sterile rst alleles uncovered two temporally separated and functionally distinct requirements for this locus in ovarian development: one in pupa, essential for the organization of peritoneal and epithelial sheaths that maintain the structural integrity of the adult organ and another, in mature ovarioles, needed for the progression of oogenesis beyond stage 10.
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Affiliation(s)
- Felipe Berti Valer
- Department of Cellular and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Maiaro Cabral Rosa Machado
- Department of Cellular and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
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Leikina E, Gamage DG, Prasad V, Goykhberg J, Crowe M, Diao J, Kozlov MM, Chernomordik LV, Millay DP. Myomaker and Myomerger Work Independently to Control Distinct Steps of Membrane Remodeling during Myoblast Fusion. Dev Cell 2018; 46:767-780.e7. [PMID: 30197239 DOI: 10.1016/j.devcel.2018.08.006] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 06/27/2018] [Accepted: 08/08/2018] [Indexed: 02/03/2023]
Abstract
Classic mechanisms for membrane fusion involve transmembrane proteins that assemble into complexes and dynamically alter their conformation to bend membranes, leading to mixing of membrane lipids (hemifusion) and fusion pore formation. Myomaker and Myomerger govern myoblast fusion and muscle formation but are structurally divergent from traditional fusogenic proteins. Here, we show that Myomaker and Myomerger independently mediate distinct steps in the fusion pathway, where Myomaker is involved in membrane hemifusion and Myomerger is necessary for fusion pore formation. Mechanistically, we demonstrate that Myomerger is required on the cell surface where its ectodomains stress membranes. Moreover, we show that Myomerger drives fusion completion in a heterologous system independent of Myomaker and that a Myomaker-Myomerger physical interaction is not required for function. Collectively, our data identify a stepwise cell fusion mechanism in myoblasts where different proteins are delegated to perform unique membrane functions essential for membrane coalescence.
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Affiliation(s)
- Evgenia Leikina
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dilani G Gamage
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Vikram Prasad
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Joanna Goykhberg
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Michael Crowe
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45229, USA
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45229, USA
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Leonid V Chernomordik
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Douglas P Millay
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.
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Duan R, Kim JH, Shilagardi K, Schiffhauer ES, Lee DM, Son S, Li S, Thomas C, Luo T, Fletcher DA, Robinson DN, Chen EH. Spectrin is a mechanoresponsive protein shaping fusogenic synapse architecture during myoblast fusion. Nat Cell Biol 2018; 20:688-698. [PMID: 29802406 PMCID: PMC6397639 DOI: 10.1038/s41556-018-0106-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 04/18/2018] [Indexed: 12/24/2022]
Abstract
Spectrin is a membrane skeletal protein best known for its structural role in maintaining cell shape and protecting cells from mechanical damage. Here, we report that α/βH-spectrin (βH is also called karst) dynamically accumulates and dissolves at the fusogenic synapse between fusing Drosophila muscle cells, where an attacking fusion partner invades its receiving partner with actin-propelled protrusions to promote cell fusion. Using genetics, cell biology, biophysics and mathematical modelling, we demonstrate that spectrin exhibits a mechanosensitive accumulation in response to shear deformation, which is highly elevated at the fusogenic synapse. The transiently accumulated spectrin network functions as a cellular fence to restrict the diffusion of cell-adhesion molecules and a cellular sieve to constrict the invasive protrusions, thereby increasing the mechanical tension of the fusogenic synapse to promote cell membrane fusion. Our study reveals a function of spectrin as a mechanoresponsive protein and has general implications for understanding spectrin function in dynamic cellular processes.
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Affiliation(s)
- Rui Duan
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Laboratory of Regenerative Medicine in Sports Science, School of Sports Science, South China Normal University, Guangzhou, China
| | - Ji Hoon Kim
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Khurts Shilagardi
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Eric S Schiffhauer
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Donghoon M Lee
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sungmin Son
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, USA
| | - Shuo Li
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Claire Thomas
- Departments of Biology and of Biochemistry and Molecular Biology, Penn State University, University Park, PA, USA
| | - Tianzhi Luo
- Department of Modern Mechanics, University of Science and Technology of China, Hefei, China
| | - Daniel A Fletcher
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, USA
| | - Douglas N Robinson
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Elizabeth H Chen
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX, USA.
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55
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André LM, Ausems CRM, Wansink DG, Wieringa B. Abnormalities in Skeletal Muscle Myogenesis, Growth, and Regeneration in Myotonic Dystrophy. Front Neurol 2018; 9:368. [PMID: 29892259 PMCID: PMC5985300 DOI: 10.3389/fneur.2018.00368] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 05/07/2018] [Indexed: 12/16/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) and 2 (DM2) are autosomal dominant degenerative neuromuscular disorders characterized by progressive skeletal muscle weakness, atrophy, and myotonia with progeroid features. Although both DM1 and DM2 are characterized by skeletal muscle dysfunction and also share other clinical features, the diseases differ in the muscle groups that are affected. In DM1, distal muscles are mainly affected, whereas in DM2 problems are mostly found in proximal muscles. In addition, manifestation in DM1 is generally more severe, with possible congenital or childhood-onset of disease and prominent CNS involvement. DM1 and DM2 are caused by expansion of (CTG•CAG)n and (CCTG•CAGG)n repeats in the 3' non-coding region of DMPK and in intron 1 of CNBP, respectively, and in overlapping antisense genes. This critical review will focus on the pleiotropic problems that occur during development, growth, regeneration, and aging of skeletal muscle in patients who inherited these expansions. The current best-accepted idea is that most muscle symptoms can be explained by pathomechanistic effects of repeat expansion on RNA-mediated pathways. However, aberrations in DNA replication and transcription of the DM loci or in protein translation and proteome homeostasis could also affect the control of proliferation and differentiation of muscle progenitor cells or the maintenance and physiological integrity of muscle fibers during a patient's lifetime. Here, we will discuss these molecular and cellular processes and summarize current knowledge about the role of embryonic and adult muscle-resident stem cells in growth, homeostasis, regeneration, and premature aging of healthy and diseased muscle tissue. Of particular interest is that also progenitor cells from extramuscular sources, such as pericytes and mesoangioblasts, can participate in myogenic differentiation. We will examine the potential of all these types of cells in the application of regenerative medicine for muscular dystrophies and evaluate new possibilities for their use in future therapy of DM.
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Affiliation(s)
- Laurène M André
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - C Rosanne M Ausems
- Department of Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, Netherlands
| | - Derick G Wansink
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Bé Wieringa
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
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Yadav R, Nisha, Sarkar S. Drosophila globin1 is required for maintenance of the integrity of F-actin based cytoskeleton during development. Exp Cell Res 2018. [PMID: 29524391 DOI: 10.1016/j.yexcr.2018.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Hemoglobins (Hbs) are evolutionarily conserved small globular proteins with characteristic 3-over-3 α-helical sandwich structure that is typically known as "globin fold". Hbs have been found to be involved in diverse biological functions and the characteristic property of oxygen transportation is relatively a recent adaptation. Drosophila genome possesses three globin genes (glob1, glob2, and glob3) and it was previously reported that adequate expression of glob1 is required for various aspects of development, and also to regulate the cellular level of reactive oxygen species (ROS). The present study illustrates the explicit role of glob1 gene in Drosophila development. We demonstrate a dynamic expression pattern of glob1 in larval tissues which largely concentrate around F-actin rich structures and also co-precipitate. Reduced expression of glob1 leads to developmental abnormalities which appeared to be largely mediated by inappropriately formed F-actin based cytoskeletal structures. Our subsequent analysis in FLP/FRT mediated somatic clones establishes specific role of Drosophila glob1 in maintenance of the integrity of F-actin based cytoskeleton during development. For the first time, we report interaction between Glob1 and actin, and propose a novel role of glob1 in maintenance of F-actin based cytoskeleton in Drosophila.
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Affiliation(s)
- Renu Yadav
- Department of Genetics, University of Delhi South Campus, Benito Juarez Road, Dhaula Kuan, New Delhi 110021, India
| | - Nisha
- Department of Genetics, University of Delhi South Campus, Benito Juarez Road, Dhaula Kuan, New Delhi 110021, India
| | - Surajit Sarkar
- Department of Genetics, University of Delhi South Campus, Benito Juarez Road, Dhaula Kuan, New Delhi 110021, India.
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