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Morton GM, Toledo MP, Zheng Y, Zheng C, Megraw TL. A distinct isoform of Msp300/Nesprin organizes the perinuclear microtubule organizing center in adipose cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.28.601268. [PMID: 38979285 PMCID: PMC11230431 DOI: 10.1101/2024.06.28.601268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
In many cell types, disparate non-centrosomal microtubule-organizing centers (ncMTOCs) replace functional centrosomes and serve the unique needs of the cell types in which they are formed. In Drosophila fat body cells (adipocytes), an ncMTOC is organized on the nuclear surface. This perinuclear ncMTOC is anchored by Msp300, encoded by one of two Nesprin-encoding genes in Drosophila. Msp300 and the spectraplakin short stop (shot) are co-dependent for localization to the nuclear envelope to generate the ncMTOC where they recruit the microtubule minus-end stabilizer Patronin (CAMSAP). The fat body perinuclear ncMTOC requires Patronin, Ninein, and Msps (ortholog of ch-TOG), but does not require γ-tubulin for MT assembly. The Msp300 gene is complex, encoding at least eleven isoforms. Here we show that two Msp300 isoforms, Msp300-PE and -PG, are required and only one, Msp300-PE, appears sufficient for generation of the ncMTOC. Loss of Msp300-PE,-PG retains the presence of the other isoforms at the nuclear surface, indicating that they are not sufficient to generate the ncMTOC. Loss of Msp300-PE,-PG results in severe loss of localization of shot and Patronin, and disruption of the MT array. This results in nuclear mispositioning and loss of endosomal trafficking. Msp300-PE has an unusual domain structure including a lack of a KASH domain and very few spectrin repeats and appears therefore to have a highly derived function suited to generating an ncMTOC on the nuclear surface.
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Affiliation(s)
- Garret M Morton
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Maria Pilar Toledo
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Yiming Zheng
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiang'an Hospital of Xiamen University, Xiamen University, Xiamen, China, 361102, and Shenzhen Research Institute of Xiamen University, Shenzhen, China, 518057
| | - Chunfeng Zheng
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
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2
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van der Graaf K, Srivastav S, Nishad R, Stern M, McNew JA. The Drosophila Nesprin-1 homolog MSP300 is required for muscle autophagy and proteostasis. J Cell Sci 2024; 137:jcs262096. [PMID: 38757366 PMCID: PMC11213522 DOI: 10.1242/jcs.262096] [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: 03/06/2024] [Accepted: 05/13/2024] [Indexed: 05/18/2024] Open
Abstract
Nesprin proteins, which are components of the linker of nucleoskeleton and cytoskeleton (LINC) complex, are located within the nuclear envelope and play prominent roles in nuclear architecture. For example, LINC complex proteins interact with both chromatin and the cytoskeleton. Here, we report that the Drosophila Nesprin MSP300 has an additional function in autophagy within larval body wall muscles. RNAi-mediated MSP300 knockdown in larval body wall muscles resulted in defects in the contractile apparatus, muscle degeneration and defective autophagy. In particular, MSP300 knockdown caused accumulation of cytoplasmic aggregates that contained poly-ubiquitylated cargo, as well as the autophagy receptor ref(2)P (the fly homolog of p62 or SQSTM) and Atg8a. Furthermore, MSP300 knockdown larvae expressing an mCherry-GFP-tagged Atg8a transgene exhibited aberrant persistence of the GFP signal within these aggregates, indicating failure of autophagosome maturation. These autophagy deficits were similar to those exhibited by loss of the endoplasmic reticulum (ER) fusion protein Atlastin (Atl), raising the possibility that Atl and MSP300 might function in the same pathway. In support of this possibility, we found that a GFP-tagged MSP300 protein trap exhibited extensive localization to the ER. Alteration of ER-directed MSP300 might abrogate important cytoskeletal contacts necessary for autophagosome completion.
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Affiliation(s)
| | | | - Rajkishor Nishad
- Department of BioSciences, Rice University, Houston, TX 77005, USA
| | - Michael Stern
- Department of BioSciences, Rice University, Houston, TX 77005, USA
| | - James A. McNew
- Department of BioSciences, Rice University, Houston, TX 77005, USA
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3
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Bernas T, Seo J, Wilson ZT, Tan BH, Deschenes I, Carter C, Liu J, Tseng GN. Persistent PKA activation redistributes NaV1.5 to the cell surface of adult rat ventricular myocytes. J Gen Physiol 2024; 156:e202313436. [PMID: 38226948 PMCID: PMC10791559 DOI: 10.1085/jgp.202313436] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 09/15/2023] [Accepted: 12/08/2023] [Indexed: 01/17/2024] Open
Abstract
During chronic stress, persistent activation of cAMP-dependent protein kinase (PKA) occurs, which can contribute to protective or maladaptive changes in the heart. We sought to understand the effect of persistent PKA activation on NaV1.5 channel distribution and function in cardiomyocytes using adult rat ventricular myocytes as the main model. PKA activation with 8CPT-cAMP and okadaic acid (phosphatase inhibitor) caused an increase in Na+ current amplitude without altering the total NaV1.5 protein level, suggesting a redistribution of NaV1.5 to the myocytes' surface. Biotinylation experiments in HEK293 cells showed that inhibiting protein trafficking from intracellular compartments to the plasma membrane prevented the PKA-induced increase in cell surface NaV1.5. Additionally, PKA activation induced a time-dependent increase in microtubule plus-end binding protein 1 (EB1) and clustering of EB1 at myocytes' peripheral surface and intercalated discs (ICDs). This was accompanied by a decrease in stable interfibrillar microtubules but an increase in dynamic microtubules along the myocyte surface. Imaging and coimmunoprecipitation experiments revealed that NaV1.5 interacted with EB1 and β-tubulin, and both interactions were enhanced by PKA activation. We propose that persistent PKA activation promotes NaV1.5 trafficking to the peripheral surface of myocytes and ICDs by providing dynamic microtubule tracks and enhanced guidance by EB1. Our proposal is consistent with an increase in the correlative distribution of NaV1.5, EB1, and β-tubulin at these subcellular domains in PKA-activated myocytes. Our study suggests that persistent PKA activation, at least during the initial phase, can protect impulse propagation in a chronically stressed heart by increasing NaV1.5 at ICDs.
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Affiliation(s)
- Tytus Bernas
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, USA
| | - John Seo
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - Zachary T. Wilson
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - Bi-hua Tan
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Isabelle Deschenes
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Christiane Carter
- Massey Center Bioinformatics Shared Resource, Virginia Commonwealth University, Richmond, VA, USA
| | - Jinze Liu
- Massey Center Bioinformatics Shared Resource, Virginia Commonwealth University, Richmond, VA, USA
| | - Gea-Ny Tseng
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
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4
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Castellano L, Gache V. [Microtubular network and functionality of the striated skeletal muscle]. Med Sci (Paris) 2023; 39 Hors série n° 1:54-57. [PMID: 37975771 DOI: 10.1051/medsci/2023146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023] Open
Abstract
Striated skeletal muscles are made of post-mitotic and multinucleated cells: muscle fibers, in which nuclei are regularly spaced and positioned at their periphery. The specific positioning of nuclei, necessary for the proper functioning of the muscle, is mainly regulated by the microtubule network and partner proteins. Many muscular pathologies present alterations in both the organization of the microtubule network and nuclear positioning, as observed in Duchenne Muscular Dystrophy, centronuclear myopathies or various neuromuscular diseases. The importance of the microtubule interactome and its influence in the maintenance of skeletal muscle homeostasis is a key issue in understanding muscle diseases.
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Affiliation(s)
- Léa Castellano
- Institut NeuroMyoGène, CNRS UMR 5261 - Inserm U1315, Université Claude Bernard Lyon 1, France
| | - Vincent Gache
- Institut NeuroMyoGène, CNRS UMR 5261 - Inserm U1315, Université Claude Bernard Lyon 1, France
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5
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Brener A, Lorber D, Reuveny A, Toledano H, Porat-Kuperstein L, Lebenthal Y, Weizman E, Olender T, Volk T. Sedentary Behavior Impacts on the Epigenome and Transcriptome: Lessons from Muscle Inactivation in Drosophila Larvae. Cells 2023; 12:2333. [PMID: 37830547 PMCID: PMC10571804 DOI: 10.3390/cells12192333] [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] [Received: 08/31/2023] [Revised: 09/18/2023] [Accepted: 09/19/2023] [Indexed: 10/14/2023] Open
Abstract
The biological mechanisms linking sedentary lifestyles and metabolic derangements are incompletely understood. In this study, temporal muscle inactivation in Drosophila larvae carrying a temperature-sensitive mutation in the shibire (shi1) gene was induced to mimic sedentary behavior during early life and study its transcriptional outcome. Our findings indicated a significant change in the epigenetic profile, as well as the genomic profile, of RNA Pol II binding in the inactive muscles relative to control, within a relatively short time period. Whole-genome analysis of RNA-Pol II binding to DNA by muscle-specific targeted DamID (TaDa) protocol revealed that muscle inactivity altered Pol II binding in 121 out of 2010 genes (6%), with a three-fold enrichment of genes coding for lncRNAs. The suppressed protein-coding genes included genes associated with longevity, DNA repair, muscle function, and ubiquitin-dependent proteostasis. Moreover, inducing muscle inactivation exerted a multi-level impact upon chromatin modifications, triggering an altered epigenetic balance of active versus inactive marks. The downregulated genes in the inactive muscles included genes essential for muscle structure and function, carbohydrate metabolism, longevity, and others. Given the multiple analogous genes in Drosophila for many human genes, extrapolating our findings to humans may hold promise for establishing a molecular link between sedentary behavior and metabolic diseases.
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Affiliation(s)
- Avivit Brener
- Pediatric Endocrinology and Diabetes Institute, Dana-Dwek Children’s Hospital, Tel Aviv Sourasky Medical Center, Affiliated with the Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; (A.B.); (Y.L.)
| | - Dana Lorber
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel; (D.L.); (A.R.); (T.O.)
| | - Adriana Reuveny
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel; (D.L.); (A.R.); (T.O.)
| | - Hila Toledano
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel; (H.T.); (L.P.-K.)
| | - Lilach Porat-Kuperstein
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel; (H.T.); (L.P.-K.)
| | - Yael Lebenthal
- Pediatric Endocrinology and Diabetes Institute, Dana-Dwek Children’s Hospital, Tel Aviv Sourasky Medical Center, Affiliated with the Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; (A.B.); (Y.L.)
| | - Eviatar Weizman
- G-INCPM, Weizmann Institute of Science, Rehovot 7610001, Israel;
| | - Tsviya Olender
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel; (D.L.); (A.R.); (T.O.)
| | - Talila Volk
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel; (D.L.); (A.R.); (T.O.)
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De Silva S, Fan Z, Kang B, Shanahan CM, Zhang Q. Nesprin-1: novel regulator of striated muscle nuclear positioning and mechanotransduction. Biochem Soc Trans 2023; 51:1331-1345. [PMID: 37171063 PMCID: PMC10317153 DOI: 10.1042/bst20221541] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 04/20/2023] [Accepted: 04/20/2023] [Indexed: 05/13/2023]
Abstract
Nesprins (nuclear envelope spectrin repeat proteins) are multi-isomeric scaffolding proteins. Giant nesprin-1 and -2 localise to the outer nuclear membrane, interact with SUN (Sad1p/UNC-84) domain-containing proteins at the inner nuclear membrane to form the LInker of Nucleoskeleton and Cytoskeleton (LINC) complex, which, in association with lamin A/C and emerin, mechanically couples the nucleus to the cytoskeleton. Despite ubiquitous expression of nesprin giant isoforms, pathogenic mutations in nesprin-1 and -2 are associated with tissue-specific disorders, particularly related to striated muscle such as dilated cardiomyopathy and Emery-Dreifuss muscular dystrophy. Recent evidence suggests this muscle-specificity might be attributable in part, to the small muscle specific isoform, nesprin-1α2, which has a novel role in striated muscle function. Our current understanding of muscle-specific functions of nesprin-1 and its isoforms will be summarised in this review to provide insight into potential pathological mechanisms of nesprin-related muscle disease and may inform potential targets of therapeutic modulation.
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Affiliation(s)
- Shanelle De Silva
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London SE5 9NU, U.K
| | - Zhijuan Fan
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London SE5 9NU, U.K
- Clinical Laboratory, Tianjin Third Central Hospital, Tianjin 300170, China
| | - Baoqiang Kang
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London SE5 9NU, U.K
| | - Catherine M. Shanahan
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London SE5 9NU, U.K
| | - Qiuping Zhang
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London SE5 9NU, U.K
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7
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Amiad Pavlov D, Unnikannan CP, Lorber D, Bajpai G, Olender T, Stoops E, Reuveny A, Safran S, Volk T. The LINC Complex Inhibits Excessive Chromatin Repression. Cells 2023; 12:cells12060932. [PMID: 36980273 PMCID: PMC10047284 DOI: 10.3390/cells12060932] [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: 01/16/2023] [Revised: 03/15/2023] [Accepted: 03/16/2023] [Indexed: 03/30/2023] Open
Abstract
The Linker of Nucleoskeleton and Cytoskeleton (LINC) complex transduces nuclear mechanical inputs suggested to control chromatin organization and gene expression; however, the underlying mechanism is currently unclear. We show here that the LINC complex is needed to minimize chromatin repression in muscle tissue, where the nuclei are exposed to significant mechanical inputs during muscle contraction. To this end, the genomic binding profiles of Polycomb, Heterochromatin Protein1 (HP1a) repressors, and of RNA-Pol II were studied in Drosophila larval muscles lacking functional LINC complex. A significant increase in the binding of Polycomb and parallel reduction of RNA-Pol-II binding to a set of muscle genes was observed. Consistently, enhanced tri-methylated H3K9 and H3K27 repressive modifications and reduced chromatin activation by H3K9 acetylation were found. Furthermore, larger tri-methylated H3K27me3 repressive clusters, and chromatin redistribution from the nuclear periphery towards nuclear center, were detected in live LINC mutant larval muscles. Computer simulation indicated that the observed dissociation of the chromatin from the nuclear envelope promotes growth of tri-methylated H3K27 repressive clusters. Thus, we suggest that by promoting chromatin-nuclear envelope binding, the LINC complex restricts the size of repressive H3K27 tri-methylated clusters, thereby limiting the binding of Polycomb transcription repressor, directing robust transcription in muscle fibers.
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Affiliation(s)
- Daria Amiad Pavlov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | | | - Dana Lorber
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Gaurav Bajpai
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tsviya Olender
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Elizabeth Stoops
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Adriana Reuveny
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Samuel Safran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Talila Volk
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
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8
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Padilla JR, Ferreira LM, Folker ES. Nuclear movement in multinucleated cells. Development 2022; 149:dev200749. [PMID: 36305464 PMCID: PMC10655921 DOI: 10.1242/dev.200749] [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: 06/16/2023]
Abstract
Nuclear movement is crucial for the development of many cell types and organisms. Nuclear movement is highly conserved, indicating its necessity for cellular function and development. In addition to mononucleated cells, there are several examples of cells in which multiple nuclei exist within a shared cytoplasm. These multinucleated cells and syncytia have important functions for development and homeostasis. Here, we review a subset of the developmental contexts in which the regulation of the movement and positioning of multiple nuclei are well understood, including pronuclear migration, the Drosophila syncytial blastoderm, the Caenorhabditis elegans hypodermis, skeletal muscle and filamentous fungi. We apply the principles learned from these models to other systems.
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Affiliation(s)
- Jorel R. Padilla
- Biology Department, Boston College, Chestnut Hill, MA 02467, USA
| | | | - Eric S. Folker
- Biology Department, Boston College, Chestnut Hill, MA 02467, USA
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9
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Shaw NM, Rios-Monterrosa JL, Fedorchak GR, Ketterer MR, Coombs GS, Lammerding J, Wallrath LL. Effects of mutant lamins on nucleo-cytoskeletal coupling in Drosophila models of LMNA muscular dystrophy. Front Cell Dev Biol 2022; 10:934586. [PMID: 36120560 PMCID: PMC9471154 DOI: 10.3389/fcell.2022.934586] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 07/20/2022] [Indexed: 11/13/2022] Open
Abstract
The nuclei of multinucleated skeletal muscles experience substantial external force during development and muscle contraction. Protection from such forces is partly provided by lamins, intermediate filaments that form a scaffold lining the inner nuclear membrane. Lamins play a myriad of roles, including maintenance of nuclear shape and stability, mediation of nuclear mechanoresponses, and nucleo-cytoskeletal coupling. Herein, we investigate how disease-causing mutant lamins alter myonuclear properties in response to mechanical force. This was accomplished via a novel application of a micropipette harpooning assay applied to larval body wall muscles of Drosophila models of lamin-associated muscular dystrophy. The assay enables the measurement of both nuclear deformability and intracellular force transmission between the cytoskeleton and nuclear interior in intact muscle fibers. Our studies revealed that specific mutant lamins increase nuclear deformability while other mutant lamins cause nucleo-cytoskeletal coupling defects, which were associated with loss of microtubular nuclear caging. We found that microtubule caging of the nucleus depended on Msp300, a KASH domain protein that is a component of the linker of nucleoskeleton and cytoskeleton (LINC) complex. Taken together, these findings identified residues in lamins required for connecting the nucleus to the cytoskeleton and suggest that not all muscle disease-causing mutant lamins produce similar defects in subcellular mechanics.
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Affiliation(s)
- Nicholas M. Shaw
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Jose L. Rios-Monterrosa
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Gregory R. Fedorchak
- The Nancy E. and Peter C. Meinig School of Biomedical Engineering, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States
| | - Margaret R. Ketterer
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Gary S. Coombs
- Biology Department, Waldorf University, Forest City, IA, United States
| | - Jan Lammerding
- The Nancy E. and Peter C. Meinig School of Biomedical Engineering, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States
| | - Lori L. Wallrath
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- *Correspondence: Lori L. Wallrath,
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10
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Rossi D, Pierantozzi E, Amadsun DO, Buonocore S, Rubino EM, Sorrentino V. The Sarcoplasmic Reticulum of Skeletal Muscle Cells: A Labyrinth of Membrane Contact Sites. Biomolecules 2022; 12:488. [PMID: 35454077 PMCID: PMC9026860 DOI: 10.3390/biom12040488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/14/2022] [Accepted: 03/18/2022] [Indexed: 12/17/2022] Open
Abstract
The sarcoplasmic reticulum of skeletal muscle cells is a highly ordered structure consisting of an intricate network of tubules and cisternae specialized for regulating Ca2+ homeostasis in the context of muscle contraction. The sarcoplasmic reticulum contains several proteins, some of which support Ca2+ storage and release, while others regulate the formation and maintenance of this highly convoluted organelle and mediate the interaction with other components of the muscle fiber. In this review, some of the main issues concerning the biology of the sarcoplasmic reticulum will be described and discussed; particular attention will be addressed to the structure and function of the two domains of the sarcoplasmic reticulum supporting the excitation-contraction coupling and Ca2+-uptake mechanisms.
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Affiliation(s)
- Daniela Rossi
- Department of Molecular and Developmental Medicine, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy; (E.P.); (D.O.A.); (S.B.); (E.M.R.); (V.S.)
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11
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Mechanobiology of muscle and myofibril morphogenesis. Cells Dev 2021; 168:203760. [PMID: 34863916 DOI: 10.1016/j.cdev.2021.203760] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/22/2021] [Accepted: 11/22/2021] [Indexed: 01/05/2023]
Abstract
Muscles generate forces for animal locomotion. The contractile apparatus of muscles is the sarcomere, a highly regular array of large actin and myosin filaments linked by gigantic titin springs. During muscle development many sarcomeres assemble in series into long periodic myofibrils that mechanically connect the attached skeleton elements. Thus, ATP-driven myosin forces can power movement of the skeleton. Here we review muscle and myofibril morphogenesis, with a particular focus on their mechanobiology. We describe recent progress on the molecular structure of sarcomeres and their mechanical connections to the skeleton. We discuss current models predicting how tension coordinates the assembly of key sarcomeric components to periodic myofibrils that then further mature during development. This requires transcriptional feedback mechanisms that may help to coordinate myofibril assembly and maturation states with the transcriptional program. To fuel the varying energy demands of muscles we also discuss the close mechanical interactions of myofibrils with mitochondria and nuclei to optimally support powerful or enduring muscle fibers.
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12
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Becker R, Vergarajauregui S, Billing F, Sharkova M, Lippolis E, Mamchaoui K, Ferrazzi F, Engel FB. Myogenin controls via AKAP6 non-centrosomal microtubule-organizing center formation at the nuclear envelope. eLife 2021; 10:65672. [PMID: 34605406 PMCID: PMC8523159 DOI: 10.7554/elife.65672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 10/01/2021] [Indexed: 12/22/2022] Open
Abstract
Non-centrosomal microtubule-organizing centers (MTOCs) are pivotal for the function of multiple cell types, but the processes initiating their formation are unknown. Here, we find that the transcription factor myogenin is required in murine myoblasts for the localization of MTOC proteins to the nuclear envelope. Moreover, myogenin is sufficient in fibroblasts for nuclear envelope MTOC (NE-MTOC) formation and centrosome attenuation. Bioinformatics combined with loss- and gain-of-function experiments identified induction of AKAP6 expression as one central mechanism for myogenin-mediated NE-MTOC formation. Promoter studies indicate that myogenin preferentially induces the transcription of muscle- and NE-MTOC-specific isoforms of Akap6 and Syne1, which encodes nesprin-1α, the NE-MTOC anchor protein in muscle cells. Overexpression of AKAP6β and nesprin-1α was sufficient to recruit endogenous MTOC proteins to the nuclear envelope of myoblasts in the absence of myogenin. Taken together, our results illuminate how mammals transcriptionally control the switch from a centrosomal MTOC to an NE-MTOC and identify AKAP6 as a novel NE-MTOC component in muscle cells.
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Affiliation(s)
- Robert Becker
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Silvia Vergarajauregui
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Florian Billing
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Maria Sharkova
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Eleonora Lippolis
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Kamel Mamchaoui
- Sorbonne Universités UPMC Université Paris 06, INSERM U974, CNRS FRE3617, Center for Research in Myology, GH Pitié Salpêtrière, 47 Boulevard de l'Hôpital, Paris, France
| | - Fulvia Ferrazzi
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.,Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Felix B Engel
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.,Muscle Research Center Erlangen (MURCE), Erlangen, Germany
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13
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Ghasemizadeh A, Christin E, Guiraud A, Couturier N, Abitbol M, Risson V, Girard E, Jagla C, Soler C, Laddada L, Sanchez C, Jaque-Fernandez FI, Jacquemond V, Thomas JL, Lanfranchi M, Courchet J, Gondin J, Schaeffer L, Gache V. MACF1 controls skeletal muscle function through the microtubule-dependent localization of extra-synaptic myonuclei and mitochondria biogenesis. eLife 2021; 10:e70490. [PMID: 34448452 PMCID: PMC8500715 DOI: 10.7554/elife.70490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 08/10/2021] [Indexed: 01/02/2023] Open
Abstract
Skeletal muscles are composed of hundreds of multinucleated muscle fibers (myofibers) whose myonuclei are regularly positioned all along the myofiber's periphery except the few ones clustered underneath the neuromuscular junction (NMJ) at the synaptic zone. This precise myonuclei organization is altered in different types of muscle disease, including centronuclear myopathies (CNMs). However, the molecular machinery regulating myonuclei position and organization in mature myofibers remains largely unknown. Conversely, it is also unclear how peripheral myonuclei positioning is lost in the related muscle diseases. Here, we describe the microtubule-associated protein, MACF1, as an essential and evolutionary conserved regulator of myonuclei positioning and maintenance, in cultured mammalian myotubes, in Drosophila muscle, and in adult mammalian muscle using a conditional muscle-specific knockout mouse model. In vitro, we show that MACF1 controls microtubules dynamics and contributes to microtubule stabilization during myofiber's maturation. In addition, we demonstrate that MACF1 regulates the microtubules density specifically around myonuclei, and, as a consequence, governs myonuclei motion. Our in vivo studies show that MACF1 deficiency is associated with alteration of extra-synaptic myonuclei positioning and microtubules network organization, both preceding NMJ fragmentation. Accordingly, MACF1 deficiency results in reduced muscle excitability and disorganized triads, leaving voltage-activated sarcoplasmic reticulum Ca2+ release and maximal muscle force unchanged. Finally, adult MACF1-KO mice present an improved resistance to fatigue correlated with a strong increase in mitochondria biogenesis.
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Affiliation(s)
- Alireza Ghasemizadeh
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Emilie Christin
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Alexandre Guiraud
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Nathalie Couturier
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Marie Abitbol
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
- Université Marcy l’Etoile, VetAgro SupLyonFrance
| | - Valerie Risson
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Emmanuelle Girard
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Christophe Jagla
- GReD Laboratory, Clermont-Auvergne University, INSERM U1103, CNRSClermont-FerrandFrance
| | - Cedric Soler
- GReD Laboratory, Clermont-Auvergne University, INSERM U1103, CNRSClermont-FerrandFrance
| | - Lilia Laddada
- GReD Laboratory, Clermont-Auvergne University, INSERM U1103, CNRSClermont-FerrandFrance
| | - Colline Sanchez
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Francisco-Ignacio Jaque-Fernandez
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Vincent Jacquemond
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Jean-Luc Thomas
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Marine Lanfranchi
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Julien Courchet
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Julien Gondin
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Laurent Schaeffer
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
| | - Vincent Gache
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon ILyon CedexFrance
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14
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Dondi C, Bertin B, Da Ponte JP, Wojtowicz I, Jagla K, Junion G. A polarized nucleus-cytoskeleton-ECM connection in migrating cardioblasts controls heart tube formation in Drosophila. Development 2021; 148:271094. [PMID: 34323270 DOI: 10.1242/dev.192146] [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: 04/30/2020] [Accepted: 06/29/2021] [Indexed: 11/20/2022]
Abstract
The formation of the cardiac tube is a remarkable example of complex morphogenetic processes conserved from invertebrates to humans. It involves coordinated collective migration of contralateral rows of cardiac cells. The molecular processes underlying the specification of cardioblasts (CBs) prior to migration are well established and significant advances have been made in understanding the process of lumen formation. However, the mechanisms of collective cardiac cells migration remain elusive. Here, we have identified CAP and MSP300 as novel actors involved during CB migration. They both exhibit highly similar temporal and spatial expression patterns in Drosophila migrating cardiac cells, and are necessary for the correct number and alignment of CBs, a prerequisite for the coordination of their collective migration. Our data suggest that CAP and MSP300 are part of a protein complex linking focal adhesion sites to nuclei via the actin cytoskeleton that maintains post-mitotic state and correct alignment of CBs.
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Affiliation(s)
- Cristiana Dondi
- Université Clermont Auvergne, CNRS 6293, Inserm 1103, GReD institute, F-63000 Clermont-Ferrand, France
| | - Benjamin Bertin
- Université Clermont Auvergne, CNRS 6293, Inserm 1103, GReD institute, F-63000 Clermont-Ferrand, France
| | - Jean-Philippe Da Ponte
- Université Clermont Auvergne, CNRS 6293, Inserm 1103, GReD institute, F-63000 Clermont-Ferrand, France
| | - Inga Wojtowicz
- Université Clermont Auvergne, CNRS 6293, Inserm 1103, GReD institute, F-63000 Clermont-Ferrand, France
| | - Krzysztof Jagla
- Université Clermont Auvergne, CNRS 6293, Inserm 1103, GReD institute, F-63000 Clermont-Ferrand, France
| | - Guillaume Junion
- Université Clermont Auvergne, CNRS 6293, Inserm 1103, GReD institute, F-63000 Clermont-Ferrand, France
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15
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Meiler A, Marchiano F, Haering M, Weitkunat M, Schnorrer F, Habermann BH. AnnoMiner is a new web-tool to integrate epigenetics, transcription factor occupancy and transcriptomics data to predict transcriptional regulators. Sci Rep 2021; 11:15463. [PMID: 34326396 PMCID: PMC8322331 DOI: 10.1038/s41598-021-94805-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 07/14/2021] [Indexed: 11/23/2022] Open
Abstract
Gene expression regulation requires precise transcriptional programs, led by transcription factors in combination with epigenetic events. Recent advances in epigenomic and transcriptomic techniques provided insight into different gene regulation mechanisms. However, to date it remains challenging to understand how combinations of transcription factors together with epigenetic events control cell-type specific gene expression. We have developed the AnnoMiner web-server, an innovative and flexible tool to annotate and integrate epigenetic, and transcription factor occupancy data. First, AnnoMiner annotates user-provided peaks with gene features. Second, AnnoMiner can integrate genome binding data from two different transcriptional regulators together with gene features. Third, AnnoMiner offers to explore the transcriptional deregulation of genes nearby, or within a specified genomic region surrounding a user-provided peak. AnnoMiner’s fourth function performs transcription factor or histone modification enrichment analysis for user-provided gene lists by utilizing hundreds of public, high-quality datasets from ENCODE for the model organisms human, mouse, Drosophila and C. elegans. Thus, AnnoMiner can predict transcriptional regulators for a studied process without the strict need for chromatin data from the same process. We compared AnnoMiner to existing tools and experimentally validated several transcriptional regulators predicted by AnnoMiner to indeed contribute to muscle morphogenesis in Drosophila. AnnoMiner is freely available at http://chimborazo.ibdm.univ-mrs.fr/AnnoMiner/.
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Affiliation(s)
- Arno Meiler
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Fabio Marchiano
- Aix-Marseille University, CNRS, IBDM UMR 7288, The Turing Centre for Living systems (CENTURI), Aix-Marseille University, Parc Scientifique de Luminy Case 907, 163, Avenue de Luminy, 13009, Marseille, France
| | - Margaux Haering
- Aix-Marseille University, CNRS, IBDM UMR 7288, The Turing Centre for Living systems (CENTURI), Aix-Marseille University, Parc Scientifique de Luminy Case 907, 163, Avenue de Luminy, 13009, Marseille, France
| | - Manuela Weitkunat
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Frank Schnorrer
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.,Aix-Marseille University, CNRS, IBDM UMR 7288, The Turing Centre for Living systems (CENTURI), Aix-Marseille University, Parc Scientifique de Luminy Case 907, 163, Avenue de Luminy, 13009, Marseille, France
| | - Bianca H Habermann
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany. .,Aix-Marseille University, CNRS, IBDM UMR 7288, The Turing Centre for Living systems (CENTURI), Aix-Marseille University, Parc Scientifique de Luminy Case 907, 163, Avenue de Luminy, 13009, Marseille, France.
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16
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Lu W, Lakonishok M, Gelfand VI. Gatekeeper function for Short stop at the ring canals of the Drosophila ovary. Curr Biol 2021; 31:3207-3220.e4. [PMID: 34089646 DOI: 10.1016/j.cub.2021.05.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 03/15/2021] [Accepted: 05/04/2021] [Indexed: 02/06/2023]
Abstract
Growth of the Drosophila oocyte requires transport of cytoplasmic materials from the interconnected sister cells (nurse cells) through ring canals, the cytoplasmic bridges that remained open after incomplete germ cell division. Given the open nature of the ring canals, it is unclear how the direction of transport through the ring canal is controlled. In this work, we show that a single Drosophila spectraplakin Short stop (Shot) controls the direction of flow from nurse cells to the oocyte. Knockdown of shot changes the direction of transport through the ring canals from unidirectional (toward the oocyte) to bidirectional. After shot knockdown, the oocyte stops growing, resulting in a characteristic small oocyte phenotype. In agreement with this transport-directing function of Shot, we find that it is localized at the asymmetric actin baskets on the nurse cell side of the ring canals. In wild-type egg chambers, microtubules localized in the ring canals have uniform polarity (minus ends toward the oocyte), while in the absence of Shot, these microtubules have mixed polarity. Together, we propose that Shot functions as a gatekeeper directing transport from nurse cells to the oocyte via the organization of microtubule tracks to facilitate the transport driven by the minus-end-directed microtubule motor cytoplasmic dynein. VIDEO ABSTRACT.
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Affiliation(s)
- Wen Lu
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Margot Lakonishok
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Vladimir I Gelfand
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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17
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Hao H, Kalra S, Jameson LE, Guerrero LA, Cain NE, Bolivar J, Starr DA. The Nesprin-1/-2 ortholog ANC-1 regulates organelle positioning in C. elegans independently from its KASH or actin-binding domains. eLife 2021; 10:e61069. [PMID: 33860766 PMCID: PMC8139857 DOI: 10.7554/elife.61069] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 04/11/2021] [Indexed: 12/15/2022] Open
Abstract
KASH proteins in the outer nuclear membrane comprise the cytoplasmic half of linker of nucleoskeleton and cytoskeleton (LINC) complexes that connect nuclei to the cytoskeleton. Caenorhabditis elegans ANC-1, an ortholog of Nesprin-1/2, contains actin-binding and KASH domains at opposite ends of a long spectrin-like region. Deletion of either the KASH or calponin homology (CH) domains does not completely disrupt nuclear positioning, suggesting neither KASH nor CH domains are essential. Deletions in the spectrin-like region of ANC-1 led to significant defects, but only recapitulated the null phenotype in combination with mutations in the transmembrane (TM) span. In anc-1 mutants, the endoplasmic reticulum ER, mitochondria, and lipid droplets were unanchored, moving throughout the cytoplasm. The data presented here support a cytoplasmic integrity model where ANC-1 localizes to the ER membrane and extends into the cytoplasm to position nuclei, ER, mitochondria, and other organelles in place.
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Affiliation(s)
- Hongyan Hao
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Shilpi Kalra
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Laura E Jameson
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Leslie A Guerrero
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Natalie E Cain
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Jessica Bolivar
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
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18
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Van De Bor V, Loreau V, Malbouyres M, Cerezo D, Placenti A, Ruggiero F, Noselli S. A dynamic and mosaic basement membrane controls cell intercalation in Drosophila ovaries. Development 2021; 148:dev.195511. [PMID: 33526583 DOI: 10.1242/dev.195511] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 01/13/2021] [Indexed: 12/18/2022]
Abstract
Basement membranes (BM) are extracellular matrices assembled into complex and highly organized networks essential for organ morphogenesis and function. However, little is known about the tissue origin of BM components and their dynamics in vivo Here, we unravel the assembly and role of the BM main component, Collagen type IV (ColIV), in Drosophila ovarian stalk morphogenesis. Stalks are short strings of cells assembled through cell intercalation that link adjacent follicles and maintain ovarian integrity. We show that stalk ColIV has multiple origins and is assembled following a regulated pattern leading to a unique BM organisation. Absence of ColIV leads to follicle fusion, as observed upon ablation of stalk cells. ColIV and integrins are both required to trigger cell intercalation and maintain mechanically strong cell-cell attachment within the stalk. These results show how the dynamic assembly of a mosaic BM controls complex tissue morphogenesis and integrity.
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Affiliation(s)
| | | | - Marilyne Malbouyres
- Institut de Génomique Fonctionnelle de Lyon, ENS de Lyon - CNRS UMR 5242 - INRA USC 1370, 46, allée d'Italie, 69364 Lyon cedex 07, France
| | | | | | - Florence Ruggiero
- Institut de Génomique Fonctionnelle de Lyon, ENS de Lyon - CNRS UMR 5242 - INRA USC 1370, 46, allée d'Italie, 69364 Lyon cedex 07, France
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19
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Jabre S, Hleihel W, Coirault C. Nuclear Mechanotransduction in Skeletal Muscle. Cells 2021; 10:cells10020318. [PMID: 33557157 PMCID: PMC7913907 DOI: 10.3390/cells10020318] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/11/2022] Open
Abstract
Skeletal muscle is composed of multinucleated, mature muscle cells (myofibers) responsible for contraction, and a resident pool of mononucleated muscle cell precursors (MCPs), that are maintained in a quiescent state in homeostatic conditions. Skeletal muscle is remarkable in its ability to adapt to mechanical constraints, a property referred as muscle plasticity and mediated by both MCPs and myofibers. An emerging body of literature supports the notion that muscle plasticity is critically dependent upon nuclear mechanotransduction, which is transduction of exterior physical forces into the nucleus to generate a biological response. Mechanical loading induces nuclear deformation, changes in the nuclear lamina organization, chromatin condensation state, and cell signaling, which ultimately impacts myogenic cell fate decisions. This review summarizes contemporary insights into the mechanisms underlying nuclear force transmission in MCPs and myofibers. We discuss how the cytoskeleton and nuclear reorganizations during myogenic differentiation may affect force transmission and nuclear mechanotransduction. We also discuss how to apply these findings in the context of muscular disorders. Finally, we highlight current gaps in knowledge and opportunities for further research in the field.
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Affiliation(s)
- Saline Jabre
- Sorbonne Université, INSERM UMRS-974 and Institut de Myologie, 75013 Paris, France;
- Department of Biology, Faculty of Arts and Sciences, Holy Spirit University of Kasik (USEK), Jounieh 446, Lebanon;
| | - Walid Hleihel
- Department of Biology, Faculty of Arts and Sciences, Holy Spirit University of Kasik (USEK), Jounieh 446, Lebanon;
- Department of Basic Health Sciences, Faculty of Medicine, Holy Spirit University of Kaslik (USEK), Jounieh 446, Lebanon
| | - Catherine Coirault
- Sorbonne Université, INSERM UMRS-974 and Institut de Myologie, 75013 Paris, France;
- Correspondence:
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20
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Actin on and around the Nucleus. Trends Cell Biol 2020; 31:211-223. [PMID: 33376040 DOI: 10.1016/j.tcb.2020.11.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/15/2020] [Accepted: 11/19/2020] [Indexed: 12/14/2022]
Abstract
Actin plays roles in many important cellular processes, including cell motility, organelle movement, and cell signaling. The discovery of transmembrane actin-binding proteins at the outer nuclear membrane (ONM) raises the exciting possibility that actin can play a role in direct force transmission to the nucleus and the genome at its interior. Actin-dependent nucleus displacement was first described a decade ago. We are now gaining a more detailed understanding of its mechanisms, as well as new roles for actin during mitosis and meiosis, for gene expression, and in the cell's response to mechanical stimuli. Here we review these recent developments, the actin-binding proteins involved, the tissue specificity of these mechanisms, and methods developed to reconstitute and study this interaction in vitro.
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21
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Unnikannan CP, Reuveny A, Grunberg D, Volk T. Recruitment of BAF to the nuclear envelope couples the LINC complex to endoreplication. Development 2020; 147:dev.191304. [PMID: 33168584 PMCID: PMC7758627 DOI: 10.1242/dev.191304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 10/29/2020] [Indexed: 12/21/2022]
Abstract
DNA endoreplication has been implicated as a cell strategy for cell growth and in tissue injury. Here, we demonstrate that barrier-to-autointegration factor (BAF) represses endoreplication in Drosophila myofibers. We show that BAF localization at the nuclear envelope is eliminated in flies with mutations of the linker of nucleoskeleton and cytoskeleton (LINC) complex in which the LEM-domain protein Otefin is excluded, or after disruption of the nucleus-sarcomere connections. Furthermore, BAF localization at the nuclear envelope requires the activity of the BAF kinase VRK1/Ball, and, consistently, non-phosphorylatable BAF-GFP is excluded from the nuclear envelope. Importantly, removal of BAF from the nuclear envelope correlates with increased DNA content in the myonuclei. E2F1, a key regulator of endoreplication, overlaps BAF localization at the myonuclear envelope, and BAF removal from the nuclear envelope results in increased E2F1 levels in the nucleoplasm and subsequent elevated DNA content. We suggest that LINC-dependent and phosphosensitive attachment of BAF to the nuclear envelope, through its binding to Otefin, tethers E2F1 to the nuclear envelope thus inhibiting its accumulation in the nucleoplasm. Summary: Localization of BAF at the nuclear envelope of myonuclei depends on a functional LINC complex and on nucleus-sarcomere connections, and is shown to restrict E2F1 levels in the nucleoplasm.
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Affiliation(s)
- C P Unnikannan
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Adriana Reuveny
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Dvorah Grunberg
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Talila Volk
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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22
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Vergarajauregui S, Becker R, Steffen U, Sharkova M, Esser T, Petzold J, Billing F, Kapiloff MS, Schett G, Thievessen I, Engel FB. AKAP6 orchestrates the nuclear envelope microtubule-organizing center by linking golgi and nucleus via AKAP9. eLife 2020; 9:61669. [PMID: 33295871 PMCID: PMC7725499 DOI: 10.7554/elife.61669] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 12/03/2020] [Indexed: 12/31/2022] Open
Abstract
The switch from centrosomal microtubule-organizing centers (MTOCs) to non-centrosomal MTOCs during differentiation is poorly understood. Here, we identify AKAP6 as key component of the nuclear envelope MTOC. In rat cardiomyocytes, AKAP6 anchors centrosomal proteins to the nuclear envelope through its spectrin repeats, acting as an adaptor between nesprin-1α and Pcnt or AKAP9. In addition, AKAP6 and AKAP9 form a protein platform tethering the Golgi to the nucleus. Both Golgi and nuclear envelope exhibit MTOC activity utilizing either AKAP9, or Pcnt-AKAP9, respectively. AKAP6 is also required for formation and activity of the nuclear envelope MTOC in human osteoclasts. Moreover, ectopic expression of AKAP6 in epithelial cells is sufficient to recruit endogenous centrosomal proteins. Finally, AKAP6 is required for cardiomyocyte hypertrophy and osteoclast bone resorption activity. Collectively, we decipher the MTOC at the nuclear envelope as a bi-layered structure generating two pools of microtubules with AKAP6 as a key organizer.
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Affiliation(s)
- Silvia Vergarajauregui
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Robert Becker
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Ulrike Steffen
- Department of Internal Medicine 3 - Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Maria Sharkova
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Tilman Esser
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Jana Petzold
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Florian Billing
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Michael S Kapiloff
- Departments of Ophthalmology and Medicine, Stanford Cardiovascular Institute, Stanford University, Palo Alto, United States
| | - George Schett
- Department of Internal Medicine 3 - Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Ingo Thievessen
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Muscle Research Center Erlangen (MURCE), Erlangen, Germany
| | - Felix B Engel
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.,Muscle Research Center Erlangen (MURCE), Erlangen, Germany
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23
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Titlow J, Robertson F, Järvelin A, Ish-Horowicz D, Smith C, Gratton E, Davis I. Syncrip/hnRNP Q is required for activity-induced Msp300/Nesprin-1 expression and new synapse formation. J Cell Biol 2020; 219:133707. [PMID: 32040548 PMCID: PMC7055005 DOI: 10.1083/jcb.201903135] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 08/21/2019] [Accepted: 12/12/2019] [Indexed: 01/09/2023] Open
Abstract
Memory and learning involve activity-driven expression of proteins and cytoskeletal reorganization at new synapses, requiring posttranscriptional regulation of localized mRNA a long distance from corresponding nuclei. A key factor expressed early in synapse formation is Msp300/Nesprin-1, which organizes actin filaments around the new synapse. How Msp300 expression is regulated during synaptic plasticity is poorly understood. Here, we show that activity-dependent accumulation of Msp300 in the postsynaptic compartment of the Drosophila larval neuromuscular junction is regulated by the conserved RNA binding protein Syncrip/hnRNP Q. Syncrip (Syp) binds to msp300 transcripts and is essential for plasticity. Single-molecule imaging shows that msp300 is associated with Syp in vivo and forms ribosome-rich granules that contain the translation factor eIF4E. Elevated neural activity alters the dynamics of Syp and the number of msp300:Syp:eIF4E RNP granules at the synapse, suggesting that these particles facilitate translation. These results introduce Syp as an important early acting activity-dependent regulator of a plasticity gene that is strongly associated with human ataxias.
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Affiliation(s)
- Joshua Titlow
- Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Aino Järvelin
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - David Ish-Horowicz
- Department of Biochemistry, University of Oxford, Oxford, UK.,Medical Research Council Lab for Molecular Cell Biology, University College London, London, UK
| | - Carlas Smith
- Centre for Neural Circuits and Behaviour, University of Oxford, Oxford, UK
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, University of California Irvine, Irvine, CA
| | - Ilan Davis
- Department of Biochemistry, University of Oxford, Oxford, UK
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24
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Poovathumkadavil P, Jagla K. Genetic Control of Muscle Diversification and Homeostasis: Insights from Drosophila. Cells 2020; 9:cells9061543. [PMID: 32630420 PMCID: PMC7349286 DOI: 10.3390/cells9061543] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/19/2020] [Accepted: 06/23/2020] [Indexed: 12/13/2022] Open
Abstract
In the fruit fly, Drosophila melanogaster, the larval somatic muscles or the adult thoracic flight and leg muscles are the major voluntary locomotory organs. They share several developmental and structural similarities with vertebrate skeletal muscles. To ensure appropriate activity levels for their functions such as hatching in the embryo, crawling in the larva, and jumping and flying in adult flies all muscle components need to be maintained in a functionally stable or homeostatic state despite constant strain. This requires that the muscles develop in a coordinated manner with appropriate connections to other cell types they communicate with. Various signaling pathways as well as extrinsic and intrinsic factors are known to play a role during Drosophila muscle development, diversification, and homeostasis. In this review, we discuss genetic control mechanisms of muscle contraction, development, and homeostasis with particular emphasis on the contractile unit of the muscle, the sarcomere.
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25
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Lorber D, Rotkopf R, Volk T. A minimal constraint device for imaging nuclei in live Drosophila contractile larval muscles reveals novel nuclear mechanical dynamics. LAB ON A CHIP 2020; 20:2100-2112. [PMID: 32432302 DOI: 10.1039/d0lc00214c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Muscle contractions produce reiterated cytoplasmic mechanical variations, which potentially influence nuclear mechanotransduction, however information regarding the dynamics of muscle nuclei (myonuclei) in the course of muscle contraction is still missing. Towards that end, a minimal constraint device was designed in which intact live Drosophila larva is imaged, while its muscles still contract. The device is placed under spinning disc confocal microscope enabling imaging of fluorescently labeled sarcomeres and nuclei during muscle contraction, without any external stimulation. As a proof of principle we studied myonuclei dynamics in wild-type, as well as in Nesprin/klar mutant larvae lacking proper nuclear-cytoskeletal connections. Myonuclei in control larvae exhibited comparable dynamics in the course of multiple contractile events, independent of their position along the muscle fiber. In contrast, myonuclei of mutant larvae displayed differential dynamics at distinct positions along individual myofibers. Moreover, we identified a linear link between myonuclear volume and its acceleration values during muscle contraction which, in Nesprin/klar mutants exhibited an opposite tendency relative to control. Estimation of the drag force applied on individual myonuclei revealed that force fluctuations in time, but not the average force, differed significantly between control and Nesprin/klar mutant, and were considerably higher in the mutant myonuclei. Taken together these results imply significant alterations in the mechanical dynamics of individual myonuclei in the Nesprin/klar myonuclei relative to control. Such differences provide novel mechanical insight into Nesprin function in contractile muscles, and might reveal the mechanical basis underlying Nesprin-related human diseases.
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Affiliation(s)
- Dana Lorber
- Department of Molecular Genetics, Weizmann Institute of Science, Israel.
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26
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Microtubule Organization in Striated Muscle Cells. Cells 2020; 9:cells9061395. [PMID: 32503326 PMCID: PMC7349303 DOI: 10.3390/cells9061395] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 05/25/2020] [Accepted: 05/28/2020] [Indexed: 12/13/2022] Open
Abstract
Distinctly organized microtubule networks contribute to the function of differentiated cell types such as neurons, epithelial cells, skeletal myotubes, and cardiomyocytes. In striated (i.e., skeletal and cardiac) muscle cells, the nuclear envelope acts as the dominant microtubule-organizing center (MTOC) and the function of the centrosome—the canonical MTOC of mammalian cells—is attenuated, a common feature of differentiated cell types. We summarize the mechanisms known to underlie MTOC formation at the nuclear envelope, discuss the significance of the nuclear envelope MTOC for muscle function and cell cycle progression, and outline potential mechanisms of centrosome attenuation.
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27
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Zheng Y, Buchwalter RA, Zheng C, Wight EM, Chen JV, Megraw TL. A perinuclear microtubule-organizing centre controls nuclear positioning and basement membrane secretion. Nat Cell Biol 2020; 22:297-309. [PMID: 32066907 PMCID: PMC7161059 DOI: 10.1038/s41556-020-0470-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 01/17/2020] [Indexed: 12/22/2022]
Abstract
Non-centrosomal microtubule-organizing centres (ncMTOCs) have a variety of roles presumed to serve the diverse functions of the range of cell types in which they are found. ncMTOCs are diverse in their composition, subcellular localization, and function. Here we report a perinuclear MTOC in Drosophila fat body cells that is anchored by Msp300/Nesprin at the cytoplasmic surface of the nucleus. Msp300 recruits the MT minus-end protein Patronin/CAMSAP, which functions redundantly with Ninein to further recruit the MT polymerase Msps/XMAP215 to assemble non-centrosomal MTs and does so independently of the widespread MT nucleation factor γ-tubulin. Functionally, the fat body ncMTOC and the radial MT arrays it organizes is essential for nuclear positioning and for secretion of basement membrane components via retrograde dynein-dependent endosomal trafficking that restricts plasma membrane growth. Together, this study identifies a perinuclear ncMTOC with unique architecture and MT regulation properties that serves vital functions.
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Affiliation(s)
- Yiming Zheng
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA.
| | - Rebecca A Buchwalter
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Chunfeng Zheng
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Elise M Wight
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Jieyan V Chen
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA.,Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA.
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28
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Azevedo M, Baylies MK. Getting into Position: Nuclear Movement in Muscle Cells. Trends Cell Biol 2020; 30:303-316. [PMID: 32008895 DOI: 10.1016/j.tcb.2020.01.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 01/04/2020] [Accepted: 01/06/2020] [Indexed: 12/26/2022]
Abstract
The positioning of nuclei within the cell is a dynamic process that depends on the cell's fate and developmental stage and that is adjusted for optimal cell function. This is especially true in skeletal muscle cells, which contain hundreds of myonuclei distributed evenly along the periphery of the muscle cell. Mispositioned myonuclei are often associated with muscle dysfunction and disease. Different mechanisms governing myonuclear positioning are now emerging, with several of the new genes implicated in nuclear movement linked to human muscle disease. Here we discuss the recent advances in myonuclear positioning and its implications for muscle size and function from the view of Drosophila. Additionally, we highlight similarities and differences to mammalian systems and provide connections to human muscle disease.
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Affiliation(s)
- Mafalda Azevedo
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA; Graduate Program in Areas of Basic and Applied Biology (GABBA), Abel Salazar Biomedical Sciences Institute, University of Porto, Porto, Portugal
| | - Mary K Baylies
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA; Cell and Developmental Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, NY, USA.
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29
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Zhou J, Xu L, Duan X, Liu W, Zhao X, Wang X, Shang W, Fang X, Yang H, Jia L, Bai J, Zhao J, Wang L, Tong C. Large-scale RNAi screen identified Dhpr as a regulator of mitochondrial morphology and tissue homeostasis. SCIENCE ADVANCES 2019; 5:eaax0365. [PMID: 31555733 PMCID: PMC6750926 DOI: 10.1126/sciadv.aax0365] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 08/23/2019] [Indexed: 05/10/2023]
Abstract
Mitochondria are highly dynamic organelles. Through a large-scale in vivo RNA interference (RNAi) screen that covered around a quarter of the Drosophila melanogaster genes (4000 genes), we identified 578 genes whose knockdown led to aberrant shapes or distributions of mitochondria. The complex analysis revealed that knockdown of the subunits of proteasomes, spliceosomes, and the electron transport chain complexes could severely affect mitochondrial morphology. The loss of Dhpr, a gene encoding an enzyme catalyzing tetrahydrobiopterin regeneration, leads to a reduction in the numbers of tyrosine hydroxylase neurons, shorter lifespan, and gradual loss of muscle integrity and climbing ability. The affected mitochondria in Dhpr mutants are swollen and have fewer cristae, probably due to lower levels of Drp1 S-nitrosylation. Overexpression of Drp1, but not of S-nitrosylation-defective Drp1, rescued Dhpr RNAi-induced mitochondrial defects. We propose that Dhpr regulates mitochondrial morphology and tissue homeostasis by modulating S-nitrosylation of Drp1.
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Affiliation(s)
- Jia Zhou
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Lingna Xu
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xiuying Duan
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Wei Liu
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xiaocui Zhao
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xi Wang
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Weina Shang
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xuefei Fang
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Huan Yang
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Lijun Jia
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Jian Bai
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Jiayao Zhao
- The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, China
| | - Liquan Wang
- The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, China
| | - Chao Tong
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
- The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, China
- Corresponding author.
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30
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Castillo-Iglesias MS, Berciano MT, Narcis JO, Val-Bernal JF, Rodriguez-Rey JC, Tapia O, Lafarga M. Reorganization of the nuclear compartments involved in transcription and RNA processing in myonuclei of type I spinal muscular atrophy. Histochem Cell Biol 2019; 152:227-237. [PMID: 31183542 DOI: 10.1007/s00418-019-01792-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2019] [Indexed: 01/01/2023]
Abstract
Type I spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by the loss or mutation of the survival motor neuron 1 (SMN1) gene. The reduction in SMN protein levels in SMA leads to the degeneration of motor neurons and muscular atrophy. In this study, we analyzed the nuclear reorganization in human skeletal myofibers from a type I SMA patient carrying a deletion of exons 7 and 8 in the SMN1 gene and two SMN2 gene copies and showing reduced SMN protein levels in the muscle compared with those in control samples. The morphometric analysis of myofiber size revealed the coexistence of atrophic and hypertrophic myofibers in SMA samples. Compared with controls, both nuclear size and the nuclear shape factor were significantly reduced in SMA myonuclei. Nuclear reorganization in SMA myonuclei was characterized by extensive heterochromatinization, the aggregation of splicing factors in large interchromatin granule clusters, and nucleolar alterations with the accumulation of the granular component and a loss of fibrillar center/dense fibrillar component units. These nuclear alterations reflect a severe perturbation of global pre-mRNA transcription and splicing, as well as nucleolar dysfunction, in SMA myofibers. Moreover, the finding of similar nuclear reorganization in both atrophic and hypetrophic myofibers provides additional support that the SMN deficiency in SMA patients may primarily affect the skeletal myofibers.
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Affiliation(s)
- María S Castillo-Iglesias
- Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", Universidad de Cantabria-IDIVAL, Avd. Cardenal Herrera Oria s/n, 39011, Santander, Spain
| | - María T Berciano
- Departamento de Biología Molecular, Universidad de Cantabria-IDIVAL, Santander, Spain
| | - J Oriol Narcis
- Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", Universidad de Cantabria-IDIVAL, Avd. Cardenal Herrera Oria s/n, 39011, Santander, Spain
| | - J Fernando Val-Bernal
- Unidad de Patología, Departamento de Ciencias Médicas y Quirúrgicas, Universidad de Cantabria-IDIVAL, Santander, Spain
| | - José C Rodriguez-Rey
- Departamento de Biología Molecular, Universidad de Cantabria-IDIVAL, Santander, Spain
| | - Olga Tapia
- Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", Universidad de Cantabria-IDIVAL, Avd. Cardenal Herrera Oria s/n, 39011, Santander, Spain.
| | - Miguel Lafarga
- Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", Universidad de Cantabria-IDIVAL, Avd. Cardenal Herrera Oria s/n, 39011, Santander, Spain.
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31
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Sun T, Song Y, Dai J, Mao D, Ma M, Ni JQ, Liang X, Pastor-Pareja JC. Spectraplakin Shot Maintains Perinuclear Microtubule Organization in Drosophila Polyploid Cells. Dev Cell 2019; 49:731-747.e7. [DOI: 10.1016/j.devcel.2019.03.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 02/05/2019] [Accepted: 03/26/2019] [Indexed: 02/06/2023]
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32
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Oury J, Liu Y, Töpf A, Todorovic S, Hoedt E, Preethish-Kumar V, Neubert TA, Lin W, Lochmüller H, Burden SJ. MACF1 links Rapsyn to microtubule- and actin-binding proteins to maintain neuromuscular synapses. J Cell Biol 2019; 218:1686-1705. [PMID: 30842214 PMCID: PMC6504910 DOI: 10.1083/jcb.201810023] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 01/07/2019] [Accepted: 02/07/2019] [Indexed: 12/20/2022] Open
Abstract
Oury et al. show that the scaffolding protein MACF1 links Rapsyn, which binds acetylcholine receptors, to the microtubule- and actin-network at neuromuscular synapses. MACF1 thereby plays a role in synaptic maturation in mice, and mutations of MACF1 are associated with congenital myasthenia in humans. Complex mechanisms are required to form neuromuscular synapses, direct their subsequent maturation, and maintain the synapse throughout life. Transcriptional and post-translational pathways play important roles in synaptic differentiation and direct the accumulation of the neurotransmitter receptors, acetylcholine receptors (AChRs), to the postsynaptic membrane, ensuring for reliable synaptic transmission. Rapsyn, an intracellular peripheral membrane protein that binds AChRs, is essential for synaptic differentiation, but how Rapsyn acts is poorly understood. We screened for proteins that coisolate with AChRs in a Rapsyn-dependent manner and show that microtubule actin cross linking factor 1 (MACF1), a scaffolding protein with binding sites for microtubules (MT) and actin, is concentrated at neuromuscular synapses, where it binds Rapsyn and serves as a synaptic organizer for MT-associated proteins, EB1 and MAP1b, and the actin-associated protein, Vinculin. MACF1 plays an important role in maintaining synaptic differentiation and efficient synaptic transmission in mice, and variants in MACF1 are associated with congenital myasthenia in humans.
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Affiliation(s)
- Julien Oury
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
| | - Yun Liu
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Slobodanka Todorovic
- Clinic for Neurology and Psychiatry for Children and Youth, Belgrade, Serbia and Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Esthelle Hoedt
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
| | | | - Thomas A Neubert
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
| | - Weichun Lin
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Centro Nacional de Análisis Genómico, Center for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain.,Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada
| | - Steven J Burden
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
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33
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Abstract
Nuclear positioning plays an essential role in defining cell architecture and behaviour in both development and disease, and nuclear location frequently adjusts according to internal and external cues. For instance, during periods of migration in many cell types, the nucleus may be actively repositioned behind the microtubule-organising centre. Nuclear movement, for the most part, is dependent upon coupling of the cytoskeleton to the nuclear periphery. This is accomplished largely through SUN and KASH domain proteins, which together assemble to form LINC (linker of the nucleoskeleton and cytoskeleton) complexes spanning the nuclear envelope. SUN proteins of the inner nuclear membrane provide a connection to nuclear structures while acting as a tether for outer nuclear membrane KASH proteins. The latter contain binding sites for diverse cytoskeletal components. Recent publications highlight new aspects of LINC complex regulation revealing that the interplay between SUN and KASH partners can strongly influence how the nucleus functionally engages with different branches of the cytoskeleton.
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Affiliation(s)
- Brian Burke
- Institute for Medical Biology, 8A Biomedical Grove, #06-06 Immunos , 138648, Singapore
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34
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Roman W, Gomes ER. Nuclear positioning in skeletal muscle. Semin Cell Dev Biol 2018; 82:51-56. [DOI: 10.1016/j.semcdb.2017.11.005] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/24/2017] [Accepted: 11/06/2017] [Indexed: 01/01/2023]
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35
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Tillery MML, Blake-Hedges C, Zheng Y, Buchwalter RA, Megraw TL. Centrosomal and Non-Centrosomal Microtubule-Organizing Centers (MTOCs) in Drosophila melanogaster. Cells 2018; 7:E121. [PMID: 30154378 PMCID: PMC6162459 DOI: 10.3390/cells7090121] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/19/2018] [Accepted: 08/20/2018] [Indexed: 12/14/2022] Open
Abstract
The centrosome is the best-understood microtubule-organizing center (MTOC) and is essential in particular cell types and at specific stages during Drosophila development. The centrosome is not required zygotically for mitosis or to achieve full animal development. Nevertheless, centrosomes are essential maternally during cleavage cycles in the early embryo, for male meiotic divisions, for efficient division of epithelial cells in the imaginal wing disc, and for cilium/flagellum assembly in sensory neurons and spermatozoa. Importantly, asymmetric and polarized division of stem cells is regulated by centrosomes and by the asymmetric regulation of their microtubule (MT) assembly activity. More recently, the components and functions of a variety of non-centrosomal microtubule-organizing centers (ncMTOCs) have begun to be elucidated. Throughout Drosophila development, a wide variety of unique ncMTOCs form in epithelial and non-epithelial cell types at an assortment of subcellular locations. Some of these cell types also utilize the centrosomal MTOC, while others rely exclusively on ncMTOCs. The impressive variety of ncMTOCs being discovered provides novel insight into the diverse functions of MTOCs in cells and tissues. This review highlights our current knowledge of the composition, assembly, and functional roles of centrosomal and non-centrosomal MTOCs in Drosophila.
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Affiliation(s)
- Marisa M L Tillery
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Caitlyn Blake-Hedges
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Yiming Zheng
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Rebecca A Buchwalter
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
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36
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Reuveny A, Shnayder M, Lorber D, Wang S, Volk T. Ma2/d promotes myonuclear positioning and association with the sarcoplasmic reticulum. Development 2018; 145:dev.159558. [PMID: 30093550 DOI: 10.1242/dev.159558] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 07/24/2018] [Indexed: 12/24/2022]
Abstract
The cytoplasm of striated myofibers contains a large number of membrane organelles, including sarcoplasmic reticulum (SR), T-tubules and the nuclear membrane. These organelles maintain a characteristic juxtaposition that appears to be essential for efficient inter-membranous exchange of RNA, proteins and ions. We found that the membrane-associated Muscle-specific α2/δ (Ma2/d) subunit of the Ca2+ channel complex localizes to the SR and T-tubules, and accumulates at the myonuclear surfaces. Furthermore, Ma2/d mutant larval muscles exhibit nuclear positioning defects, disruption of the nuclear-SR juxtapositioning, as well as impaired larval locomotion. Ma2/d localization at the nuclear membrane depends on the proper function of the nesprin ortholog Msp300 and the BAR domain protein Amphiphysin (Amph). Importantly, live imaging of muscle contraction in intact Drosophila larvae indicated altered distribution of Sarco/Endoplamic Reticulum Ca2+-ATPase (SERCA) around the myonuclei of Ma2/d mutant larvae. Co-immunoprecipitation analysis supports association between Ma2/d and Amph, and indirectly with Msp300. We therefore suggest that Ma2/d, in association with Msp300 and Amph, mediates interactions between the SR and the nuclear membrane.
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Affiliation(s)
- Adriana Reuveny
- Department of Molecular Genetics, Weizmann Institute, Rehovot 76100, Israel
| | - Marina Shnayder
- Department of Molecular Genetics, Weizmann Institute, Rehovot 76100, Israel
| | - Dana Lorber
- Department of Molecular Genetics, Weizmann Institute, Rehovot 76100, Israel
| | - Shuoshuo Wang
- Department of Molecular Genetics, Weizmann Institute, Rehovot 76100, Israel
| | - Talila Volk
- Department of Molecular Genetics, Weizmann Institute, Rehovot 76100, Israel
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37
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Pałka M, Tomczak A, Grabowska K, Machowska M, Piekarowicz K, Rzepecka D, Rzepecki R. Laminopathies: what can humans learn from fruit flies. Cell Mol Biol Lett 2018; 23:32. [PMID: 30002683 PMCID: PMC6034310 DOI: 10.1186/s11658-018-0093-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 06/05/2018] [Indexed: 01/01/2023] Open
Abstract
Lamin proteins are type V intermediate filament proteins (IFs) located inside the cell nucleus. They are evolutionarily conserved and have similar domain organization and properties to cytoplasmic IFs. Lamins provide a skeletal network for chromatin, the nuclear envelope, nuclear pore complexes and the entire nucleus. They are also responsible for proper connections between the karyoskeleton and structural elements in the cytoplasm: actin and the microtubule and cytoplasmic IF networks. Lamins affect transcription and splicing either directly or indirectly. Translocation of active genes into the close proximity of nuclear lamina is thought to result in their transcriptional silencing. Mutations in genes coding for lamins and interacting proteins in humans result in various genetic disorders, called laminopathies. Human genes coding for A-type lamin (LMNA) are the most frequently mutated. The resulting phenotypes include muscle, cardiac, neuronal, lipodystrophic and metabolic pathologies, early aging phenotypes, and combined complex phenotypes. The Drosophila melanogaster genome codes for lamin B-type (lamin Dm), lamin A-type (lamin C), and for LEM-domain proteins, BAF, LINC-complex proteins and all typical nuclear proteins. The fruit fly system is simpler than the vertebrate one since in flies there is only single lamin B-type and single lamin A-type protein, as opposed to the complex system of B- and A-type lamins in Danio, Xenopus and Mus musculus. This offers a unique opportunity to study laminopathies. Applying genetic tools based on Gal4 and in vitro nuclear assembly system to the fruit fly model may successfully advance knowledge of laminopathies. Here, we review studies of the laminopathies in the fly model system.
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Affiliation(s)
- Marta Pałka
- Laboratory of Nuclear Proteins, Faculty of Biotechnology, University of Wroclaw, Fryderyka Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Aleksandra Tomczak
- Laboratory of Nuclear Proteins, Faculty of Biotechnology, University of Wroclaw, Fryderyka Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Katarzyna Grabowska
- Laboratory of Nuclear Proteins, Faculty of Biotechnology, University of Wroclaw, Fryderyka Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Magdalena Machowska
- Laboratory of Nuclear Proteins, Faculty of Biotechnology, University of Wroclaw, Fryderyka Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Katarzyna Piekarowicz
- Laboratory of Nuclear Proteins, Faculty of Biotechnology, University of Wroclaw, Fryderyka Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Dorota Rzepecka
- Laboratory of Nuclear Proteins, Faculty of Biotechnology, University of Wroclaw, Fryderyka Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Ryszard Rzepecki
- Laboratory of Nuclear Proteins, Faculty of Biotechnology, University of Wroclaw, Fryderyka Joliot-Curie 14a, 50-383 Wroclaw, Poland
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Wang S, Stoops E, Cp U, Markus B, Reuveny A, Ordan E, Volk T. Mechanotransduction via the LINC complex regulates DNA replication in myonuclei. J Cell Biol 2018; 217:2005-2018. [PMID: 29650775 PMCID: PMC5987719 DOI: 10.1083/jcb.201708137] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 02/08/2018] [Accepted: 03/27/2018] [Indexed: 12/26/2022] Open
Abstract
Nuclear mechanotransduction has been implicated in the control of chromatin organization and gene expression. Wang et al. show that, in Drosophila myofibers, the LINC complex is required for the regulation of DNA replication and synchronized cell-cycle progression in myonuclei. Nuclear mechanotransduction has been implicated in the control of chromatin organization; however, its impact on functional contractile myofibers is unclear. We found that deleting components of the linker of nucleoskeleton and cytoskeleton (LINC) complex in Drosophila melanogaster larval muscles abolishes the controlled and synchronized DNA endoreplication, typical of nuclei across myofibers, resulting in increased and variable DNA content in myonuclei of individual myofibers. Moreover, perturbation of LINC-independent mechanical input after knockdown of β-Integrin in larval muscles similarly led to increased DNA content in myonuclei. Genome-wide RNA-polymerase II occupancy analysis in myofibers of the LINC mutant klar indicated an altered binding profile, including a significant decrease in the chromatin regulator barrier-to-autointegration factor (BAF) and the contractile regulator Troponin C. Importantly, muscle-specific knockdown of BAF led to increased DNA content in myonuclei, phenocopying the LINC mutant phenotype. We propose that mechanical stimuli transmitted via the LINC complex act via BAF to regulate synchronized cell-cycle progression of myonuclei across single myofibers.
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Affiliation(s)
- Shuoshuo Wang
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Elizabeth Stoops
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Unnikannan Cp
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Barak Markus
- G-INCPM/Mantoux Institute for Bioinformatics, Weizmann Institute of Science, Rehovot, Israel
| | - Adriana Reuveny
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Elly Ordan
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Talila Volk
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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Lee YL, Burke B. LINC complexes and nuclear positioning. Semin Cell Dev Biol 2017; 82:67-76. [PMID: 29191370 DOI: 10.1016/j.semcdb.2017.11.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 11/06/2017] [Accepted: 11/06/2017] [Indexed: 12/14/2022]
Abstract
One of the characteristics of eukaryotic cells is their structural plasticity associated with the ability to carry out a broad range of complex functions, both autonomously and as components of tissues and organs. Major cellular rearrangements can be observed in various systems from meiosis in fission yeast, through dermal differentiation in nematodes, to muscle and neuronal development in vertebrates. Each of these processes involves oftentimes dramatic relocation of the nucleus within the cell. During the last decade it has become apparent that the nuclear periphery represents a nexus of cytoskeletal interactions that are involved not only in nuclear movement but also in the distribution and dissemination of mechanical forces throughout the cell. Nucleocytoskeletal coupling is mediated in large part by SUN- and KASH-domain proteins of the nuclear membranes, that together assemble to form LINC (Linker of the Nucleoskeleton and Cytoskeleton) complexes. In this review we will describe how the LINC complex repertoire contributes to nuclear positioning and chromosome dynamics in a variety of cellular contexts.
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Affiliation(s)
- Yin Loon Lee
- Laboratory of Nuclear Dynamics and Architecture, Institute of Medical Biology, 8A Biomedical Grove, Immunos, 138648, Singapore
| | - Brian Burke
- Laboratory of Nuclear Dynamics and Architecture, Institute of Medical Biology, 8A Biomedical Grove, Immunos, 138648, Singapore.
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Voelzmann A, Liew YT, Qu Y, Hahn I, Melero C, Sánchez-Soriano N, Prokop A. Drosophila Short stop as a paradigm for the role and regulation of spectraplakins. Semin Cell Dev Biol 2017; 69:40-57. [DOI: 10.1016/j.semcdb.2017.05.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/22/2017] [Accepted: 05/29/2017] [Indexed: 02/07/2023]
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Wang S, Volk T. Composite biopolymer scaffolds shape muscle nucleus: Insights and perspectives from Drosophila. BIOARCHITECTURE 2016; 5:35-43. [PMID: 26605802 DOI: 10.1080/19490992.2015.1106061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Contractile muscle fibers produce enormous intrinsic forces during contraction/relaxation waves. These forces are directly applied to their cytoplasmic organelles including mitochondria, sarcoplasmic reticulum, and multiple nuclei. Data from our analysis of Drosophila larval somatic muscle fibers suggest that an intricate network of organized microtubules (MT) intermingled with Spectrin-Repeat-Containing Proteins (SRCPs) are major structural elements that protect muscle organelles and maintain their structure and position during muscle contraction. Whereas the perinuclear MT network provides structural rigidity to the myonucleus, the SRCPs Nesprin and Spectraplakin form semiflexible filamentous biopolymer networks, providing nuclei with the elasticity required to resist the contractile cytoplasmic forces produced by the muscle. Spectrin repeats are domains found in numerous structural proteins, which are able to unfold under tension and are subject to mechanical stresses in the cell. This unique composite scaffold combines rigidity and resilience in order to neutralize the oscillating cellular forces occurring during muscle contraction/relaxation waves and thereby protect myonuclei. We suggest that the elastic properties of SRCPs are critical for nuclear protection and proper function in muscle fibers.
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Affiliation(s)
- Shuoshuo Wang
- a Department of Molecular Genetics ; Weizmann Institute of Science ; Rehovot , Israel
| | - Talila Volk
- a Department of Molecular Genetics ; Weizmann Institute of Science ; Rehovot , Israel
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Cadot B, Gache V, Gomes ER. Moving and positioning the nucleus in skeletal muscle - one step at a time. Nucleus 2016; 6:373-81. [PMID: 26338260 DOI: 10.1080/19491034.2015.1090073] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Nuclear movement and positioning within cells has become an area of great interest in the past few years due to the identification of different molecular mechanisms and functions in distinct organisms and contexts. One extreme example occurs during skeletal muscle development and regeneration. Skeletal muscles are composed of individual multinucleated myofibers with nuclei positioned at their periphery. Myofibers are formed by fusion of mononucleated myoblasts and during their development, successive nuclear movements and positioning events have been described. The position of the nuclei in myofibers is important for muscle function. Interestingly, during muscle regeneration and in some muscular diseases, nuclei are positioned in the center of the myofiber. In this review, we discuss the multiple mechanisms of nuclear positioning that occur during myofiber formation and regeneration. We also discuss the role of nuclear positioning for skeletal muscle function.
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Affiliation(s)
- Bruno Cadot
- a Center of Research in Myology; INSERM UPMC UMR974; CNRS FRE3617 ; Paris , France
| | - Vincent Gache
- b Ecole Normale Superieure de Lyon; CNRS UMR5239 ; Lyon , France
| | - Edgar R Gomes
- a Center of Research in Myology; INSERM UPMC UMR974; CNRS FRE3617 ; Paris , France.,c Instituto de Medicina Molecular; Faculdade de Medicina; Universidade de Lisboa ; Lisbon, Portugal
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Affiliation(s)
- Talila Volk
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Shuoshuo Wang
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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Navarro AP, Collins MA, Folker ES. The nucleus is a conserved mechanosensation and mechanoresponse organelle. Cytoskeleton (Hoboken) 2016; 73:59-67. [PMID: 26849407 DOI: 10.1002/cm.21277] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 01/22/2016] [Accepted: 01/22/2016] [Indexed: 11/05/2022]
Abstract
Cells in vivo exist in a dynamic environment where they experience variable mechanical influences. The precise mechanical environment influences cell-cell interactions, cell-extracellular matrix interactions, and in-turn, cell morphology and cell function. Therefore, the ability of each cell to constantly and rapidly alter their behavior in response to variations in their mechanical environment is essential for cell viability, development, and function. Mechanotransduction, the process by which mechanical force is translated into a biochemical signal to activate downstream cellular responses, is thus crucial to cell function during development and homeostasis. Although much research has focused on how protein complexes at the cell cortex respond to mechanical stress to initiate mechanotransduction, the nucleus has emerged as crucial to the ability of the cell to perceive and respond to changes in its mechanical environment. This additional method for mechanosensing allows for direct transmission of force through the cytoskeleton to the nucleus, which can increase the speed at which a cell changes its transcriptional profile. This review discusses recent work demonstrating the importance of the nucleus in mediating the cellular response to internal and external force, establishing the nucleus as an important mechanosensing organelle.
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Affiliation(s)
- Alexandra P Navarro
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02142
| | - Mary Ann Collins
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, 02467
| | - Eric S Folker
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, 02467
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Abstract
The cytoskeleton is a dynamic network of filamentous protein polymers required for virtually all cellular processes. It consists of three major classes, filamentous actin (F-actin), intermediate filaments, and microtubules, all displaying characteristic structural properties, functions, cellular distributions, and sets of interacting regulatory proteins. One unique class of proteins, the spectraplakins, bind, regulate, and integrate the functions of all three classes of cytoskeleton proteins. Spectraplakins are giant, evolutionary conserved multidomain proteins (spanning up to 9000 aa) that are true members of the plakin, spectrin, and Gas2-like protein families. They have OMIM-listed disease links to epidermolysis bullosa and hereditary sensory and autonomic neuropathy. Their role in disease is likely underrepresented since studies in model animal systems have revealed critical roles in polarity, morphogenesis, differentiation and maintenance, migration, signaling, and intracellular trafficking in a variety of tissues. This enormous diversity of spectraplakin function is consistent with the numerous isoforms produced from single genomic loci that combine different sets of functional domains in distinct cellular contexts. To study the broad range of functions and complexity of these proteins, Drosophila is a powerful model. Thus, the fly spectraplakin Short stop (Shot) acts as an actin-microtubule linker and plays important roles in many developmental processes, which provide experimentally amenable and relevant contexts in which to study spectraplakin functions. For these studies, a versatile range of relevant experimental resources that facilitate genetics and transgenic approaches, highly refined genomics tools, and an impressive set of spectraplakin-specific genetic and molecular tools are readily available. Here, we use the example of Shot to illustrate how the various tools and strategies available for Drosophila can be employed to decipher and dissect cellular roles and molecular mechanisms of spectraplakins.
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