1
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Tillery MML, Zheng C, Zheng Y, Megraw TL. Ninein domains required for its localization, association with partners dynein and ensconsin, and microtubule organization. Mol Biol Cell 2024; 35:ar116. [PMID: 39024292 DOI: 10.1091/mbc.e23-06-0245] [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: 07/20/2024] Open
Abstract
Ninein (Nin) is a microtubule (MT) anchor at the subdistal appendages of mother centrioles and the pericentriolar material (PCM) of centrosomes that also functions to organize MTs at noncentrosomal MT-organizing centers (ncMTOCs). In humans, the NIN gene is mutated in Seckel syndrome, an inherited developmental disorder. Here, we dissect the protein domains involved in Nin's localization and interactions with dynein and ensconsin (ens/MAP7) and show that the association with ens cooperatively regulates MT assembly in Drosophila fat body cells. We define domains of Nin responsible for its localization to the ncMTOC on the fat body cell nuclear surface, localization within the nucleus, and association with Dynein light intermediate chain (Dlic) and ens, respectively. We show that Nin's association with ens synergistically regulates MT assembly. Together, these findings reveal novel features of Nin function and its regulation of a ncMTOC.
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Affiliation(s)
- Marisa M L Tillery
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, 32306-4300
| | - Chunfeng Zheng
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, 32306-4300
| | - 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
- Shenzhen Research Institute of Xiamen University, Shenzhen, China, 518057
| | - Timothy L Megraw
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, 32306-4300
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2
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Wherley TJ, Thomas S, Millay DP, Saunders T, Roy S. Molecular regulation of myocyte fusion. Curr Top Dev Biol 2024; 158:53-82. [PMID: 38670716 DOI: 10.1016/bs.ctdb.2024.01.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
Myocyte fusion is a pivotal process in the development and regeneration of skeletal muscle. Failure during fusion can lead to a range of developmental as well as pathological consequences. This review aims to comprehensively explore the intricate processes underlying myocyte fusion, from the molecular to tissue scale. We shed light on key players, such as the muscle-specific fusogens - Myomaker and Myomixer, in addition to some lesser studied molecules contributing to myocyte fusion. Conserved across vertebrates, Myomaker and Myomixer play a crucial role in driving the merger of plasma membranes of fusing myocytes, ensuring the formation of functional muscle syncytia. Our multiscale approach also delves into broader cell and tissue dynamics that orchestrate the timing and positioning of fusion events. In addition, we explore the relevance of muscle fusogens to human health and disease. Mutations in fusogen genes have been linked to congenital myopathies, providing unique insights into the molecular basis of muscle diseases. We conclude with a discussion on potential therapeutic avenues that may emerge from manipulating the myocyte fusion process to remediate skeletal muscle disorders.
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Affiliation(s)
- Tanner J Wherley
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Serena Thomas
- Warwick Medical School, University of Warwick, Coventry, United Kingdom; Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore, Singapore
| | - Douglas P Millay
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
| | - Timothy Saunders
- Warwick Medical School, University of Warwick, Coventry, United Kingdom; Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore, Singapore.
| | - Sudipto Roy
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore, Singapore; Department of Pediatrics, National University of Singapore, Singapore, Singapore.
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3
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Kalbfuss N, Gönczy P. Towards understanding centriole elimination. Open Biol 2023; 13:230222. [PMID: 37963546 PMCID: PMC10645514 DOI: 10.1098/rsob.230222] [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: 07/11/2023] [Accepted: 09/14/2023] [Indexed: 11/16/2023] Open
Abstract
Centrioles are microtubule-based structures crucial for forming flagella, cilia and centrosomes. Through these roles, centrioles are critical notably for proper cell motility, signalling and division. Recent years have advanced significantly our understanding of the mechanisms governing centriole assembly and architecture. Although centrioles are typically very stable organelles, persisting over many cell cycles, they can also be eliminated in some cases. Here, we review instances of centriole elimination in a range of species and cell types. Moreover, we discuss potential mechanisms that enable the switch from a stable organelle to a vanishing one. Further work is expected to provide novel insights into centriole elimination mechanisms in health and disease, thereby also enabling scientists to readily manipulate organelle fate.
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Affiliation(s)
- Nils Kalbfuss
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), 1015 Lausanne, Switzerland
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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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Kalbfuss N, Berger A, Gönczy P. Mapping of centriolar proteins onto the post-embryonic lineage of C. elegans. Dev Biol 2023; 502:68-76. [PMID: 37414202 DOI: 10.1016/j.ydbio.2023.07.001] [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: 04/25/2023] [Revised: 06/22/2023] [Accepted: 07/03/2023] [Indexed: 07/08/2023]
Abstract
Centrioles, together with the surrounding peri-centriolar material (PCM), constitute the centrosome, a major microtubule-organizing center of animal cells. Despite being critical in many cells for signaling, motility and division, centrioles can be eliminated in some systems, including in the vast majority of differentiating cells during embryogenesis in Caenorhabditis elegans. Whether the cells retaining centrioles in the resulting L1 larvae do so because they lack an activity that eliminates centrioles in the other cells is not known. Moreover, the extent to which centrioles and PCM remain present in later stages of worm development, when all cells but those of the germ line are terminally differentiated, is not known. Here, by fusing cells that lack centrioles with cells that retain them, we established that L1 larvae do not possess a diffusible elimination activity sufficient to remove centrioles. Moreover, analyzing PCM core proteins in L1 larval cells that retain centrioles, we found that some such proteins, but not all, are present as well. Furthermore, we uncovered that foci of centriolar proteins remain present in specific terminally differentiated cells of adult hermaphrodites and males, in particular in the somatic gonad. Correlating the time at which cells were born with the fate of their centrioles revealed that it is not cell age, but instead cell fate, that determines whether and when centrioles are eliminated. Overall, our work maps the localization of centriolar and PCM core proteins in the post-embryonic C. elegans lineage, thereby providing an essential blueprint for uncovering mechanisms modulating their presence and function.
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Affiliation(s)
- Nils Kalbfuss
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, CH-1015, Switzerland
| | - Antonin Berger
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, CH-1015, Switzerland
| | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, CH-1015, Switzerland.
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6
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Kalbfuss N, Gönczy P. Extensive programmed centriole elimination unveiled in C. elegans embryos. SCIENCE ADVANCES 2023; 9:eadg8682. [PMID: 37256957 PMCID: PMC10413642 DOI: 10.1126/sciadv.adg8682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 04/25/2023] [Indexed: 06/02/2023]
Abstract
Centrioles are critical for fundamental cellular processes, including signaling, motility, and division. The extent to which centrioles are present after cell cycle exit in a developing organism is not known. The stereotypical lineage of Caenorhabditis elegans makes it uniquely well-suited to investigate this question. Using notably lattice light-sheet microscopy, correlative light electron microscopy, and lineage assignment, we found that ~88% of cells lose centrioles during embryogenesis. Our analysis reveals that centriole elimination is stereotyped, occurring invariably at a given time in a given cell type. Moreover, we established that experimentally altering cell fate results in corresponding changes in centriole fate. Overall, we uncovered the existence of an extensive centriole elimination program, which we anticipate to be paradigmatic for a broad understanding of centriole fate regulation.
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Affiliation(s)
- Nils Kalbfuss
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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7
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Atmakuru PS, Dhawan J. The cilium-centrosome axis in coupling cell cycle exit and cell fate. J Cell Sci 2023; 136:308872. [PMID: 37144419 DOI: 10.1242/jcs.260454] [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] [Indexed: 05/06/2023] Open
Abstract
The centrosome is an evolutionarily conserved, ancient organelle whose role in cell division was first described over a century ago. The structure and function of the centrosome as a microtubule-organizing center, and of its extracellular extension - the primary cilium - as a sensory antenna, have since been extensively studied, but the role of the cilium-centrosome axis in cell fate is still emerging. In this Opinion piece, we view cellular quiescence and tissue homeostasis from the vantage point of the cilium-centrosome axis. We focus on a less explored role in the choice between distinct forms of mitotic arrest - reversible quiescence and terminal differentiation, which play distinct roles in tissue homeostasis. We outline evidence implicating the centrosome-basal body switch in stem cell function, including how the cilium-centrosome complex regulates reversible versus irreversible arrest in adult skeletal muscle progenitors. We then highlight exciting new findings in other quiescent cell types that suggest signal-dependent coupling of nuclear and cytoplasmic events to the centrosome-basal body switch. Finally, we propose a framework for involvement of this axis in mitotically inactive cells and identify future avenues for understanding how the cilium-centrosome axis impacts central decisions in tissue homeostasis.
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Affiliation(s)
- Priti S Atmakuru
- CSIR Centre for Cellular and Molecular Biology, Hyderabad 500 007, India
| | - Jyotsna Dhawan
- CSIR Centre for Cellular and Molecular Biology, Hyderabad 500 007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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8
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Lucas L, Cooper TA. Insights into Cell-Specific Functions of Microtubules in Skeletal Muscle Development and Homeostasis. Int J Mol Sci 2023; 24:ijms24032903. [PMID: 36769228 PMCID: PMC9917663 DOI: 10.3390/ijms24032903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/17/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023] Open
Abstract
The contractile cells of skeletal muscles, called myofibers, are elongated multinucleated syncytia formed and maintained by the fusion of proliferative myoblasts. Human myofibers can be hundreds of microns in diameter and millimeters in length. Myofibers are non-mitotic, obviating the need for microtubules in cell division. However, microtubules have been adapted to the unique needs of these cells and are critical for myofiber development and function. Microtubules in mature myofibers are highly dynamic, and studies in several experimental systems have demonstrated the requirements for microtubules in the unique features of muscle biology including myoblast fusion, peripheral localization of nuclei, assembly of the sarcomere, transport and signaling. Microtubule-binding proteins have also been adapted to the needs of the skeletal muscle including the expression of skeletal muscle-specific protein isoforms generated by alternative splicing. Here, we will outline the different roles microtubules play in skeletal muscle cells, describe how microtubule abnormalities can lead to muscle disease and discuss the broader implications for microtubule function.
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Affiliation(s)
- Lathan Lucas
- Chemical, Physical, Structural Biology Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Thomas A. Cooper
- Chemical, Physical, Structural Biology Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
- Correspondence:
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9
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Divergent Contribution of the Golgi Apparatus to Microtubule Organization in Related Cell Lines. Int J Mol Sci 2022; 23:ijms232416178. [PMID: 36555819 PMCID: PMC9782006 DOI: 10.3390/ijms232416178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022] Open
Abstract
Membrane trafficking in interphase animal cells is accomplished mostly along the microtubules. Microtubules are often organized radially by the microtubule-organizing center to coordinate intracellular transport. Along with the centrosome, the Golgi often serves as a microtubule-organizing center, capable of nucleating and retaining microtubules. Recent studies revealed the role of a special subset of Golgi-derived microtubules, which facilitates vesicular traffic from this central transport hub of the cell. However, proteins essential for microtubule organization onto the Golgi might be differentially expressed in different cell lines, while many potential participants remain undiscovered. In the current work, we analyzed the involvement of the Golgi complex in microtubule organization in related cell lines. We studied two cell lines, both originating from green monkey renal epithelium, and found that they relied either on the centrosome or on the Golgi as a main microtubule-organizing center. We demonstrated that the difference in their Golgi microtubule-organizing activity was not associated with the well-studied proteins, such as CAMSAP3, CLASP2, GCC185, and GMAP210, but revealed several potential candidates involved in this process.
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10
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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] [Key Words] [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
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11
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Nadkarni AV, Heald R. Reconstitution of muscle cell microtubule organization in vitro. Cytoskeleton (Hoboken) 2022; 78:492-502. [PMID: 35666041 DOI: 10.1002/cm.21710] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 05/31/2022] [Accepted: 06/01/2022] [Indexed: 11/06/2022]
Abstract
Skeletal muscle differentiation occurs as muscle precursor cells (myoblasts) elongate and fuse to form multinucleated syncytial myotubes in which the highly-organized actomyosin sarcomeres of muscle fibers assemble. Although less well characterized, the microtubule cytoskeleton also undergoes dramatic rearrangement during myogenesis. The centrosome-nucleated microtubule array found in myoblasts is lost as the nuclear membrane acquires microtubule nucleating activity and microtubules emerge from multiple sites in the cell, eventually rearranging into a grid-like pattern in myotubes. In order to characterize perinuclear microtubule organization using a biochemically tractable system, we isolated nuclei from mouse C2C12 skeletal muscle cells during the course of differentiation and incubated them in cytoplasmic extracts prepared from eggs of the frog Xenopus laevis. Whereas centrosomes associated with myoblast nuclei gave rise to radial microtubule arrays in extracts, myotube nuclei produced a sun-like pattern with microtubules transiently nucleating from the entire nuclear envelope. Perinuclear microtubule growth was suppressed by inhibition of Aurora A kinase or by degradation of RNA, treatments that also inhibited microtubule growth from sperm centrosomes. Myotube nuclei displayed microtubule motor-based movements leading to their separation, as occurs in myotubes. This in vitro assay therefore recapitulates key features of microtubule organization and nuclear movement observed during muscle cell differentiation. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Ambika V Nadkarni
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, USA
| | - Rebecca Heald
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, USA
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12
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Philip R, Fiorino C, Harrison RE. Terminally differentiated osteoclasts organize centrosomes into large clusters for microtubule nucleation and bone resorption. Mol Biol Cell 2022; 33:ar68. [PMID: 35511803 DOI: 10.1091/mbc.e22-03-0098] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Osteoclasts are highly specialized, multinucleated cells responsible for the selective resorption of the dense, calcified bone matrix. Microtubules (MTs) contribute to the polarization and trafficking events involved in bone resorption by osteoclasts, however the origin of these elaborate arrays is less clear. Osteoclasts arise through cell fusion of precursor cells. Previous studies have suggested that centrosome MT nucleation is lost during this process, with the nuclear membrane and its surrounding Golgi serving as the major microtubule organizing centres (MTOCs) in these cells. Here we reveal that precursor cell centrosomes are maintained and functional in the multinucleated osteoclast and interestingly form large MTOC clusters, with the clusters organizing significantly more MTs, compared to individual centrosomes. MTOC cluster formation requires dynamic microtubules and minus-end directed MT motor activity. Inhibition of these centrosome clustering elements had a marked impact on both F-actin ring formation and bone resorption. Together these findings show that multinucleated osteoclasts employ unique centrosomal clusters to organize the extensive microtubules during bone attachment and resorption. [Media: see text].
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Affiliation(s)
- Reuben Philip
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.,Lunenfeld-Tanenbaum Research Institute, Toronto, Ontario, Canada, M5G 1 × 5
| | - Cara Fiorino
- Department of Cell & Systems Biology and the Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4
| | - Rene E Harrison
- Department of Cell & Systems Biology and the Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4
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13
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Vineethakumari C, Lüders J. Microtubule Anchoring: Attaching Dynamic Polymers to Cellular Structures. Front Cell Dev Biol 2022; 10:867870. [PMID: 35309944 PMCID: PMC8927778 DOI: 10.3389/fcell.2022.867870] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 02/11/2022] [Indexed: 01/01/2023] Open
Abstract
Microtubules are dynamic, filamentous polymers composed of α- and β-tubulin. Arrays of microtubules that have a specific polarity and distribution mediate essential processes such as intracellular transport and mitotic chromosome segregation. Microtubule arrays are generated with the help of microtubule organizing centers (MTOC). MTOCs typically combine two principal activities, the de novo formation of microtubules, termed nucleation, and the immobilization of one of the two ends of microtubules, termed anchoring. Nucleation is mediated by the γ-tubulin ring complex (γTuRC), which, in cooperation with its recruitment and activation factors, provides a template for α- and β-tubulin assembly, facilitating formation of microtubule polymer. In contrast, the molecules and mechanisms that anchor newly formed microtubules at MTOCs are less well characterized. Here we discuss the mechanistic challenges underlying microtubule anchoring, how this is linked with the molecular activities of known and proposed anchoring factors, and what consequences defective microtubule anchoring has at the cellular and organismal level.
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14
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Rolls MM. Principles of microtubule polarity in linear cells. Dev Biol 2022; 483:112-117. [PMID: 35016908 PMCID: PMC10071391 DOI: 10.1016/j.ydbio.2022.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 01/06/2022] [Indexed: 01/30/2023]
Abstract
The microtubule cytoskeleton is critical for maintenance of long and long-lived neurons. The overlapping array of microtubules extends from the major site of synthesis in the cell body to the far reaches of axons and dendrites. New materials are transported from the cell body along these neuronal roads by motor proteins, and building blocks and information about the state of affairs in other parts of the cell are returned by motors moving in the opposite direction. As motor proteins walk only in one direction along microtubules, the combination of correct motor and correctly oriented microtubules is essential for moving cargoes in the right direction. In this review, we focus on how microtubule polarity is established and maintained in neurons. At first thought, it seems that figuring out how microtubules are organized in neurons should be simple. After all, microtubules are essentially sticks with a slow-growing minus end and faster-growing plus end, and arranging sticks within the constrained narrow tubes of axons and dendrites should be straightforward. It is therefore quite surprising how many mechanisms contribute to making sure they are arranged in the correct polarity. Some of these mechanisms operate to generate plus-end-out polarity of axons, and others control mixed or minus-end-out dendrites.
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Affiliation(s)
- Melissa M Rolls
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
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15
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Collins MA, Coon LA, Thomas R, Mandigo TR, Wynn E, Folker ES. Ensconsin-dependent changes in microtubule organization and LINC complex-dependent changes in nucleus-nucleus interactions result in quantitatively distinct myonuclear positioning defects. Mol Biol Cell 2021; 32:ar27. [PMID: 34524872 PMCID: PMC8693964 DOI: 10.1091/mbc.e21-06-0324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Nuclear movement is a fundamental process of eukaryotic cell biology. Skeletal muscle presents an intriguing model to study nuclear movement because its development requires the precise positioning of multiple nuclei within a single cytoplasm. Furthermore, there is a high correlation between aberrant nuclear positioning and poor muscle function. Although many genes that regulate nuclear movement have been identified, the mechanisms by which these genes act are not known. Using Drosophila melanogaster muscle development as a model system and a combination of live-embryo microscopy and laser ablation of nuclei, we have found that clustered nuclei encompass at least two phenotypes that are caused by distinct mechanisms. Specifically, Ensconsin is necessary for productive force production to drive any movement of nuclei, whereas Bocksbeutel and Klarsicht are necessary to form distinct populations of nuclei that move to different cellular locations. Mechanistically, Ensconsin regulates the number of growing microtubules that are used to move nuclei, whereas Bocksbeutel and Klarsicht regulate interactions between nuclei.
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Affiliation(s)
| | - L Alexis Coon
- Department of Biology, Boston College, Chestnut Hill, MA 02467
| | - Riya Thomas
- Department of Biology, Boston College, Chestnut Hill, MA 02467
| | | | - Elizabeth Wynn
- Department of Biology, Boston College, Chestnut Hill, MA 02467
| | - Eric S Folker
- Department of Biology, Boston College, Chestnut Hill, MA 02467
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16
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Hinz BE, Walker SG, Xiong A, Gogal RA, Schnieders MJ, Wallrath LL. In Silico and In Vivo Analysis of Amino Acid Substitutions That Cause Laminopathies. Int J Mol Sci 2021; 22:ijms222011226. [PMID: 34681887 PMCID: PMC8536974 DOI: 10.3390/ijms222011226] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/07/2021] [Accepted: 10/11/2021] [Indexed: 01/08/2023] Open
Abstract
Mutations in the LMNA gene cause diseases called laminopathies. LMNA encodes lamins A and C, intermediate filaments with multiple roles at the nuclear envelope. LMNA mutations are frequently single base changes that cause diverse disease phenotypes affecting muscles, nerves, and fat. Disease-associated amino acid substitutions were mapped in silico onto three-dimensional structures of lamin A/C, revealing no apparent genotype–phenotype connections. In silico analyses revealed that seven of nine predicted partner protein binding pockets in the Ig-like fold domain correspond to sites of disease-associated amino acid substitutions. Different amino acid substitutions at the same position within lamin A/C cause distinct diseases, raising the question of whether the nature of the amino acid replacement or genetic background differences contribute to disease phenotypes. Substitutions at R249 in the rod domain cause muscular dystrophies with varying severity. To address this variability, we modeled R249Q and R249W in Drosophila Lamin C, an orthologue of LMNA. Larval body wall muscles expressing mutant Lamin C caused abnormal nuclear morphology and premature death. When expressed in indirect flight muscles, R249W caused a greater number of adults with wing posturing defects than R249Q, consistent with observations that R249W and R249Q cause distinct muscular dystrophies, with R249W more severe. In this case, the nature of the amino acid replacement appears to dictate muscle disease severity. Together, our findings illustrate the utility of Drosophila for predicting muscle disease severity and pathogenicity of variants of unknown significance.
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Affiliation(s)
- Benjamin E. Hinz
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA; (B.E.H.); (S.G.W.); (A.X.); (M.J.S.)
| | - Sydney G. Walker
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA; (B.E.H.); (S.G.W.); (A.X.); (M.J.S.)
| | - Austin Xiong
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA; (B.E.H.); (S.G.W.); (A.X.); (M.J.S.)
| | - Rose A. Gogal
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA;
| | - Michael J. Schnieders
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA; (B.E.H.); (S.G.W.); (A.X.); (M.J.S.)
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA;
| | - Lori L. Wallrath
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA; (B.E.H.); (S.G.W.); (A.X.); (M.J.S.)
- Correspondence: ; Tel.: +1-319-335-7920
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17
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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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18
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Ng DCH, Ho UY, Grounds MD. Cilia, Centrosomes and Skeletal Muscle. Int J Mol Sci 2021; 22:9605. [PMID: 34502512 PMCID: PMC8431768 DOI: 10.3390/ijms22179605] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 08/30/2021] [Accepted: 09/01/2021] [Indexed: 12/13/2022] Open
Abstract
Primary cilia are non-motile, cell cycle-associated organelles that can be found on most vertebrate cell types. Comprised of microtubule bundles organised into an axoneme and anchored by a mature centriole or basal body, primary cilia are dynamic signalling platforms that are intimately involved in cellular responses to their extracellular milieu. Defects in ciliogenesis or dysfunction in cilia signalling underlie a host of developmental disorders collectively referred to as ciliopathies, reinforcing important roles for cilia in human health. Whilst primary cilia have long been recognised to be present in striated muscle, their role in muscle is not well understood. However, recent studies indicate important contributions, particularly in skeletal muscle, that have to date remained underappreciated. Here, we explore recent revelations that the sensory and signalling functions of cilia on muscle progenitors regulate cell cycle progression, trigger differentiation and maintain a commitment to myogenesis. Cilia disassembly is initiated during myoblast fusion. However, the remnants of primary cilia persist in multi-nucleated myotubes, and we discuss their potential role in late-stage differentiation and myofiber formation. Reciprocal interactions between cilia and the extracellular matrix (ECM) microenvironment described for other tissues may also inform on parallel interactions in skeletal muscle. We also discuss emerging evidence that cilia on fibroblasts/fibro-adipogenic progenitors and myofibroblasts may influence cell fate in both a cell autonomous and non-autonomous manner with critical consequences for skeletal muscle ageing and repair in response to injury and disease. This review addresses the enigmatic but emerging role of primary cilia in satellite cells in myoblasts and myofibers during myogenesis, as well as the wider tissue microenvironment required for skeletal muscle formation and homeostasis.
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Affiliation(s)
- Dominic C. H. Ng
- School of Biomedical Science, Faculty of Medicine, University of Queensland, St Lucia, Brisbane, QLD 4072, Australia;
| | - Uda Y. Ho
- School of Biomedical Science, Faculty of Medicine, University of Queensland, St Lucia, Brisbane, QLD 4072, Australia;
| | - Miranda D. Grounds
- School of Human Sciences, Faculty of Medicine, University of Western Australia, Perth, WA 6009, Australia
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19
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Pinheiro H, Pimentel MR, Sequeira C, Oliveira LM, Pezzarossa A, Roman W, Gomes ER. mRNA distribution in skeletal muscle is associated with mRNA size. J Cell Sci 2021; 134:jcs256388. [PMID: 34297126 PMCID: PMC7611476 DOI: 10.1242/jcs.256388] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 06/18/2021] [Indexed: 12/30/2022] Open
Abstract
Skeletal muscle myofibers are large and elongated cells with multiple and evenly distributed nuclei. Nuclear distribution suggests that each nucleus influences a specific compartment within the myofiber and implies a functional role for nuclear positioning. Compartmentalization of specific mRNAs and proteins has been reported at the neuromuscular and myotendinous junctions, but mRNA distribution in non-specialized regions of the myofibers remains largely unexplored. We report that the bulk of mRNAs are enriched around the nucleus of origin and that this perinuclear accumulation depends on recently transcribed mRNAs. Surprisingly, mRNAs encoding large proteins - giant mRNAs - are spread throughout the cell and do not exhibit perinuclear accumulation. Furthermore, by expressing exogenous transcripts with different sizes we found that size contributes to mRNA spreading independently of mRNA sequence. Both these mRNA distribution patterns depend on microtubules and are independent of nuclear dispersion, mRNA expression level and stability, and the characteristics of the encoded protein. Thus, we propose that mRNA distribution in non-specialized regions of skeletal muscle is size selective to ensure cellular compartmentalization and simultaneous long-range distribution of giant mRNAs.
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Affiliation(s)
- Helena Pinheiro
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa. Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Mafalda Ramos Pimentel
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa. Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Catarina Sequeira
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa. Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Luís Manuel Oliveira
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa. Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Anna Pezzarossa
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa. Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - William Roman
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa. Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
- Experimental and Health Sciences (DCEXS), Universitat Pompeu Fabra (UPF), 08002 Barcelona, Spain
| | - Edgar R. Gomes
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa. Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
- Instituto de Histologia e Biologia do Desenvolvimento, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
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20
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Ide K, Muko M, Hayashi K. The Golgi apparatus is the main microtubule-organizing center in differentiating skeletal muscle cells. Histochem Cell Biol 2021; 156:273-281. [PMID: 34110464 DOI: 10.1007/s00418-021-01999-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2021] [Indexed: 10/21/2022]
Abstract
Studies in differentiating skeletal muscle cells in vitro have revealed that the microtubule-organizing center shifts from the centrosome to the perinuclear sites. As the Golgi apparatus surrounds the nucleus in a myotube, it is unclear whether microtubules are nucleated at the nuclear envelope or at the surrounding Golgi apparatus. In this study, we investigated the positional relationship between the microtubule nucleating sites and the Golgi apparatus in C2C12 myotubes and in primary cultured mouse skeletal myotubes. We focused on gaps in the perinuclear Golgi apparatus where the nuclear envelope was not covered with the Golgi apparatus. In microtubule regrowth assay, microtubule regrowth after cold-nocodazole depolymerization of preexisting microtubules was not found at the gap of the perinuclear Golgi apparatus. Most of the microtubule regrowth was detected at the CDK5RAP2 (CDK5 regulatory subunit-associated protein 2)-rich spots on the perinuclear Golgi apparatus. Disruption of the perinuclear Golgi apparatus with brefeldin A treatment eliminated the perinuclear microtubule regrowth. The Golgi apparatus of undifferentiated myoblasts and those at the cytoplasm of myotubes were also the microtubule nucleating sites. From these observations, we concluded that most of the perinuclear microtubule nucleation occurs on the Golgi apparatus surrounding the nucleus.
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Affiliation(s)
- Koyo Ide
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo, Japan
| | - Mika Muko
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo, Japan
| | - Kensuke Hayashi
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo, Japan.
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21
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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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22
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Zupa E, Liu P, Würtz M, Schiebel E, Pfeffer S. The structure of the γ-TuRC: a 25-years-old molecular puzzle. Curr Opin Struct Biol 2020; 66:15-21. [PMID: 33002806 DOI: 10.1016/j.sbi.2020.08.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 08/26/2020] [Accepted: 08/28/2020] [Indexed: 10/23/2022]
Abstract
The nucleation of microtubules from αβ-tubulin dimers is an essential cellular process dependent on γ-tubulin complexes. Mechanistic understanding of the nucleation reaction was hampered by the lack of γ-tubulin complex structures at sufficiently high resolution. The recent technical developments in cryo-electron microscopy have allowed resolving the vertebrate γ-tubulin ring complex (γ-TuRC) structure at near-atomic resolution. These studies clarified the arrangement and stoichiometry of gamma-tubulin complex proteins in the γ-TuRC, characterized the surprisingly versatile integration of the small proteins MZT1/2 into the complex, and identified actin as an integral component of the γ-TuRC. In this review, we summarize the structural insights into the molecular architecture, the assembly pathway, and the regulation of the microtubule nucleation reaction.
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Affiliation(s)
- Erik Zupa
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Peng Liu
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Martin Würtz
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
| | - Stefan Pfeffer
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
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23
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de Andrade Rosa I, Corrêa S, Costa ML, Mermelstein C. The scaffolding protein calpain-3 has multiple distributions in embryonic chick muscle cells and it is essential for the formation of muscle fibers. Tissue Cell 2020; 67:101436. [PMID: 32932207 DOI: 10.1016/j.tice.2020.101436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/28/2020] [Accepted: 08/29/2020] [Indexed: 12/21/2022]
Abstract
CAPN3 is a muscle-specific and an intrinsically disordered protein. Thus, as a scaffolding protein CAPN3 could play a role during early stages of myogenesis. To test this hypothesis, we studied the distribution and function of CAPN3 during myogenesis using embryonic chick muscle cells grown in vitro. Super-resolution microscopy showed CAPN3 distribution in (i) amorphous patches in myoblasts, (ii) a region near the nuclei of myotubes; (iii) adhesion plaques in myotubes, (iv) stress fiber-like structures in myotubes, and (v) filaments in fibroblasts. Downregulation of CAPN3 induced a decrease in the number of muscle cells and in the size of myotubes formed. These data show a diverse intracellular distribution of CAPN3, compatible with a scaffolding protein, and suggest a multitude of different interactions of CAPN3 with other partners during muscle formation.
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Affiliation(s)
- Ivone de Andrade Rosa
- Laboratório de Diferenciação Muscular e Citoesqueleto, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | | | - Manoel Luis Costa
- Laboratório de Diferenciação Muscular e Citoesqueleto, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Claudia Mermelstein
- Laboratório de Diferenciação Muscular e Citoesqueleto, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
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24
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Valenzuela A, Meservey L, Nguyen H, Fu MM. Golgi Outposts Nucleate Microtubules in Cells with Specialized Shapes. Trends Cell Biol 2020; 30:792-804. [PMID: 32863092 DOI: 10.1016/j.tcb.2020.07.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/11/2020] [Accepted: 07/15/2020] [Indexed: 12/16/2022]
Abstract
Classically, animal cells nucleate or form new microtubules off the perinuclear centrosome. In recent years, the Golgi outpost has emerged as a satellite organelle that can function as an acentrosomal microtubule-organizing center (MTOC), nucleating new microtubules at distances far from the nucleus or cell body. Golgi outposts can nucleate new microtubules in specialized cells with unique cytoarchitectures, including Drosophila neurons, mouse muscle cells, and rodent oligodendrocytes. This review compares and contrasts topics of functional relevance, including Golgi outpost heterogeneity, formation and transport, as well as regulation of microtubule polarity and branching. Golgi outposts have also been implicated in the pathology of diseases including muscular dystrophy, and neurodegenerative diseases, such as Parkinson's disease (PD). Since Golgi outposts are relatively understudied, many outstanding questions regarding their function and roles in disease remain.
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Affiliation(s)
- Alex Valenzuela
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Lindsey Meservey
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Huy Nguyen
- Department of Neurology, Stanford University School of Medicine, Stanford, CA, USA
| | - Meng-Meng Fu
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA, USA; National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
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25
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Dhanyasi N, VijayRaghavan K, Shilo BZ, Schejter ED. Microtubules provide guidance cues for myofibril and sarcomere assembly and growth. Dev Dyn 2020; 250:60-73. [PMID: 32725855 DOI: 10.1002/dvdy.227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 04/09/2020] [Accepted: 06/20/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Muscle myofibrils and sarcomeres present exceptional examples of highly ordered cytoskeletal filament arrays, whose distinct spatial organization is an essential aspect of muscle cell functionality. We utilized ultra-structural analysis to investigate the assembly of myofibrils and sarcomeres within developing myotubes of the indirect flight musculature of Drosophila. RESULTS A temporal sequence composed of three major processes was identified: subdivision of the unorganized cytoplasm of nascent, multi-nucleated myotubes into distinct organelle-rich and filament-rich domains; initial organization of the filament-rich domains into myofibrils harboring nascent sarcomeric units; and finally, maturation of the highly-ordered pattern of sarcomeric thick (myosin-based) and thin (microfilament-based) filament arrays in parallel to myofibril radial growth. Significantly, organized microtubule arrays were present throughout these stages and exhibited dynamic changes in their spatial patterns consistent with instructive roles. Genetic manipulations confirm these notions, and imply specific and critical guidance activities of the microtubule-based cytoskeleton, as well as structural interdependence between the myosin- and actin-based filament arrays. CONCLUSIONS Our observations highlight a surprisingly significant, behind-the-scenes role for microtubules in establishment of myofibril and sarcomere spatial patterns and size, and provide a detailed account of the interplay between major cytoskeletal elements in generating these essential contractile myogenic units.
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Affiliation(s)
- Nagaraju Dhanyasi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.,National Centre for Biological Sciences, TIFR, Bangalore, India
| | - K VijayRaghavan
- National Centre for Biological Sciences, TIFR, Bangalore, India
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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26
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Liu W, Zheng F, Wang Y, Fu C. Alp7-Mto1 and Alp14 synergize to promote interphase microtubule regrowth from the nuclear envelope. J Mol Cell Biol 2020; 11:944-955. [PMID: 31087092 PMCID: PMC6927237 DOI: 10.1093/jmcb/mjz038] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 03/15/2019] [Accepted: 04/26/2019] [Indexed: 01/02/2023] Open
Abstract
Microtubules grow not only from the centrosome but also from various noncentrosomal microtubule-organizing centers (MTOCs), including the nuclear envelope (NE) and pre-existing microtubules. The evolutionarily conserved proteins Mto1/CDK5RAP2 and Alp14/TOG/XMAP215 have been shown to be involved in promoting microtubule nucleation. However, it has remained elusive as to how the microtubule nucleation promoting factors are specified to various noncentrosomal MTOCs, particularly the NE, and how these proteins coordinate to organize microtubule assembly. Here, we demonstrate that in the fission yeast Schizosaccharomyces pombe, efficient interphase microtubule growth from the NE requires Alp7/TACC, Alp14/TOG/XMAP215, and Mto1/CDK5RAP2. The absence of Alp7, Alp14, or Mto1 compromises microtubule regrowth on the NE in cells undergoing microtubule repolymerization. We further demonstrate that Alp7 and Mto1 interdependently localize to the NE in cells without microtubules and that Alp14 localizes to the NE in an Alp7 and Mto1-dependent manner. Tethering Mto1 to the NE in cells lacking Alp7 partially restores microtubule number and the efficiency of microtubule generation from the NE. Hence, our study delineates that Alp7, Alp14, and Mto1 work in concert to regulate interphase microtubule regrowth on the NE.
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Affiliation(s)
- Wenyue Liu
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei, China
| | - Fan Zheng
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei, China
| | - Yucai Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Chuanhai Fu
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei, China
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27
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Turn RE, East MP, Prekeris R, Kahn RA. The ARF GAP ELMOD2 acts with different GTPases to regulate centrosomal microtubule nucleation and cytokinesis. Mol Biol Cell 2020; 31:2070-2091. [PMID: 32614697 PMCID: PMC7543072 DOI: 10.1091/mbc.e20-01-0012] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
ELMOD2 is a ∼32 kDa protein first purified by its GTPase-activating protein (GAP) activity toward ARL2 and later shown to have uniquely broad specificity toward ARF family GTPases in in vitro assays. To begin the task of defining its functions in cells, we deleted ELMOD2 in immortalized mouse embryonic fibroblasts and discovered a number of cellular defects, which are reversed upon expression of ELMOD2-myc. We show that these defects, resulting from the loss of ELMOD2, are linked to two different pathways and two different GTPases: with ARL2 and TBCD to support microtubule nucleation from centrosomes and with ARF6 in cytokinesis. These data highlight key aspects of signaling by ARF family GAPs that contribute to previously underappreciated sources of complexity, including GAPs acting from multiple sites in cells, working with multiple GTPases, and contributing to the spatial and temporal control of regulatory GTPases by serving as both GAPs and effectors.
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Affiliation(s)
- Rachel E Turn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322.,Biochemistry, Cell & Developmental Biology Graduate Program, Laney Graduate School, Emory University, Atlanta, GA 30307
| | - Michael P East
- Department of Pharmacology, University of North Carolina Chapel Hill, Chapel Hill, NC 27599
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, University of Colorado, Aurora, CO 80045
| | - Richard A Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322
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28
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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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29
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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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30
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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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31
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Nayak SC, Radha V. C3G localizes to mother centriole dependent on cenexin, and regulates centrosome duplication and primary cilia length. J Cell Sci 2020; 133:jcs.243113. [DOI: 10.1242/jcs.243113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 04/06/2020] [Indexed: 01/01/2023] Open
Abstract
C3G (RapGEF1) plays a role in cell differentiation and is essential for early embryonic development in mice. In this study, we identify C3G as a centrosomal protein colocalizing with cenexin at the mother centriole in interphase cells. C3G interacts through its catalytic domain with cenexin, and they show interdependence for localization to the centrosome. C3G depletion caused a decrease in cellular cenexin levels. Centrosomal localization is lost as myocytes differentiate to form myotubes. Stable clone of cells depleted of C3G by CRISPR/Cas9 showed the presence of supernumerary centrioles. Overexpression of C3G, or a catalytically active deletion construct inhibited centrosome duplication. Cilia length is longer in C3G knockout cells, and the phenotype could be reverted upon reintroduction of C3G or its catalytic domain. Association of C3G with the basal body is dynamic, decreasing upon serum starvation, and increasing upon reentry into the cell cycle. C3G inhibits cilia formation and length dependent on its catalytic activity. We conclude that C3G inhibits centrosome duplication and maintains ciliary homeostasis, properties that may be important for its role in embryonic development.
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Affiliation(s)
- Sanjeev Chavan Nayak
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad – 500 007, India
| | - Vegesna Radha
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad – 500 007, India
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32
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Lin YT, Deel MD, Linardic CM. RASSF4 is required for skeletal muscle differentiation. Cell Biol Int 2019; 44:381-390. [PMID: 31508857 DOI: 10.1002/cbin.11238] [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] [Received: 03/08/2019] [Accepted: 09/08/2019] [Indexed: 12/12/2022]
Abstract
RASSF4, a member of the classical RASSF family of scaffold proteins, is associated with alveolar rhabdomyosarcoma, an aggressive pediatric cancer of muscle histogenesis. However, the role of RASSF4 in normal myogenesis is unknown. We demonstrate here that RASSF4 is necessary for early in vitro myogenesis. Using primary human myoblasts, we show that RASSF4 expression is dramatically increased during in vitro myogenic differentiation, and conversely that RASSF4-deficient myoblasts cannot differentiate, potentially because of a lack of upregulation of myogenin. In microscopy studies, we show that RASSF4 protein co-localizes with proteins of the myogenic microtubule-organizing center (MTOC) both before and after myogenic differentiation. RASSF4-deficient cells subject to differentiation conditions demonstrate a lack of shape change, suggesting that RASSF4 plays a role in promoting microtubule reorganization and myoblast elongation. In biochemical studies of myotubes, RASSF4 associates with MST1, suggesting that RASSF4 signals to MST1 in the myogenic differentiation process. Expression of MST1 in myoblasts partially reversed the effect of RASSF4 knockdown on differentiation, suggesting that RASSF4 and MST1 coordinately support myogenic differentiation. These data show that RASSF4 is critical for the early steps of myogenic differentiation.
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Affiliation(s)
- Yi-Tzu Lin
- Department of Pediatrics, Division of Hematology-Oncology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Michael D Deel
- Department of Pediatrics, Division of Hematology-Oncology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Corinne M Linardic
- Department of Pediatrics, Division of Hematology-Oncology, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Pharmacology & Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA
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33
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Oddoux S, Randazzo D, Kenea A, Alonso B, Zaal KJM, Ralston E. Misplaced Golgi Elements Produce Randomly Oriented Microtubules and Aberrant Cortical Arrays of Microtubules in Dystrophic Skeletal Muscle Fibers. Front Cell Dev Biol 2019; 7:176. [PMID: 31620435 PMCID: PMC6759837 DOI: 10.3389/fcell.2019.00176] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 08/13/2019] [Indexed: 12/14/2022] Open
Abstract
Differentiated mammalian cells and tissues, such as skeletal muscle fibers, acquire an organization of Golgi complex and microtubules profoundly different from that in proliferating cells and still poorly understood. In adult rodent skeletal muscle, the multinucleated muscle fibers have hundreds of Golgi elements (GE), small stacks of cisternae that serve as microtubule-organizing centers. We are interested in the role of the GE in organizing a peculiar grid of microtubules located in the fiber cortex, against the sarcolemma. Modifications of this grid in the mdx mouse model of Duchenne muscular dystrophy have led to identifying dystrophin, the protein missing in both human disease and mouse model, as a microtubule guide. Compared to wild-type (WT), mdx microtubules are disordered and more dense and they have been linked to the dystrophic pathology. GE themselves are disordered in mdx. Here, to identify the causes of GE and microtubule alterations in the mdx muscle, we follow GFP-tagged microtubule markers in live mdx fibers and investigate the recovery of GE and microtubules after treatment with nocodazole. We find that mdx microtubules grow 10% faster but in 30% shorter bouts and that they begin to form a tangled network, rather than an orthogonal grid, right after nucleation from GE. Strikingly, a large fraction of microtubules in mdx muscle fibers seem to dissociate from GE after nucleation. Moreover, we report that mdx GE are mispositioned and increased in number and size. These results were replicated in WT fibers overexpressing the beta-tubulin tubb6, which is elevated in Duchenne muscular dystrophy, in mdx and in regenerating muscle. Finally, we examine the association of GE with ER exit sites and ER-to-Golgi intermediate compartment, which starts during muscle differentiation, and find it persisting in mdx and tubb6 overexpressing fibers. We conclude that GE are full, small, Golgi complexes anchored, and positioned through ER Exit Sites. We propose a model in which GE mispositioning, together with the absence of microtubule guidance due to the lack of dystrophin, determines the differences in GE and microtubule organization between WT and mdx muscle fibers.
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Affiliation(s)
- Sarah Oddoux
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Davide Randazzo
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Aster Kenea
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Bruno Alonso
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Kristien J M Zaal
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Evelyn Ralston
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, United States
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34
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Caporizzo MA, Chen CY, Prosser BL. Cardiac microtubules in health and heart disease. Exp Biol Med (Maywood) 2019; 244:1255-1272. [PMID: 31398994 DOI: 10.1177/1535370219868960] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cardiomyocytes are large (∼40,000 µm3), rod-shaped muscle cells that provide the working force behind each heartbeat. These highly structured cells are packed with dense cytoskeletal networks that can be divided into two groups—the contractile (i.e. sarcomeric) cytoskeleton that consists of filamentous actin-myosin arrays organized into myofibrils, and the non-sarcomeric cytoskeleton, which is composed of β- and γ-actin, microtubules, and intermediate filaments. Together, microtubules and intermediate filaments form a cross-linked scaffold, and these networks are responsible for the delivery of intracellular cargo, the transmission of mechanical signals, the shaping of membrane systems, and the organization of myofibrils and organelles. Microtubules are extensively altered as part of both adaptive and pathological cardiac remodeling, which has diverse ramifications for the structure and function of the cardiomyocyte. In heart failure, the proliferation and post-translational modification of the microtubule network is linked to a number of maladaptive processes, including the mechanical impediment of cardiomyocyte contraction and relaxation. This raises the possibility that reversing microtubule alterations could improve cardiac performance, yet therapeutic efforts will strongly benefit from a deeper understanding of basic microtubule biology in the heart. The aim of this review is to summarize the known physiological roles of the cardiomyocyte microtubule network, the consequences of its pathological remodeling, and to highlight the open and intriguing questions regarding cardiac microtubules. Impact statement Advancements in cell biological and biophysical approaches and super-resolution imaging have greatly broadened our view of tubulin biology over the last decade. In the heart, microtubules and microtubule-based transport help to organize and maintain key structures within the cardiomyocyte, including the sarcomere, intercalated disc, protein clearance machinery and transverse-tubule and sarcoplasmic reticulum membranes. It has become increasingly clear that post translational regulation of microtubules is a key determinant of their sub-cellular functionality. Alterations in microtubule network density, stability, and post-translational modifications are hallmarks of pathological cardiac remodeling, and modified microtubules can directly impede cardiomyocyte contractile function in various forms of heart disease. This review summarizes the functional roles and multi-leveled regulation of the cardiac microtubule cytoskeleton and highlights how refined experimental techniques are shedding mechanistic clarity on the regionally specified roles of microtubules in cardiac physiology and pathophysiology.
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Affiliation(s)
- Matthew A Caporizzo
- Department of Physiology, Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Christina Yingxian Chen
- Department of Physiology, Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Benjamin L Prosser
- Department of Physiology, Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.,Penn Cardiovascular Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
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35
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Yamada M, Hayashi K. Microtubule nucleation in the cytoplasm of developing cortical neurons and its regulation by brain‐derived neurotrophic factor. Cytoskeleton (Hoboken) 2019; 76:339-345. [DOI: 10.1002/cm.21550] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 06/25/2019] [Accepted: 06/27/2019] [Indexed: 01/06/2023]
Affiliation(s)
- Mimori Yamada
- Department of Materials and Life SciencesFaculty of Science and Technology, Sophia University Tokyo Japan
| | - Kensuke Hayashi
- Department of Materials and Life SciencesFaculty of Science and Technology, Sophia University Tokyo Japan
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36
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Abstract
Microtubule-organizing centers move from centrosomes to the nuclear envelope during muscle development. The KASH protein Nesprin-1α recruits pericentriolar material to the surface of myotube nuclei, where it nucleates microtubules to ensure even spacing of nuclei within the developing myotube.
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Affiliation(s)
- Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, Davis, USA.
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37
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Abstract
Microtubules are cytoskeletal filaments essential for numerous aspects of cell physiology. They are polarized polymeric tubes with a fast growing plus end and a slow growing minus end. In this Cell Science at a Glance article and the accompanying poster, we review the current knowledge on the dynamics and organization of microtubule minus ends. Several factors, including the γ-tubulin ring complex, CAMSAP/Patronin, ASPM/Asp, SPIRAL2 (in plants) and the KANSL complex recognize microtubule minus ends and regulate their nucleation, stability and interactions with partners, such as microtubule severing enzymes, microtubule depolymerases and protein scaffolds. Together with minus-end-directed motors, these microtubule minus-end targeting proteins (-TIPs) also control the formation of microtubule-organizing centers, such as centrosomes and spindle poles, and mediate microtubule attachment to cellular membrane structures, including the cell cortex, Golgi complex and the cell nucleus. Structural and functional studies are starting to reveal the molecular mechanisms by which dynamic -TIP networks control microtubule minus ends.
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Affiliation(s)
- Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland .,University of Basel, Biozentrum, CH-4056 Basel, Switzerland
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38
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Huang T, Xiao J, Wang S, Liao Z, Huang T, Gu R, Li J, Wu G, Liao H. The thickness of poly-phenoxyethyl methacrylate brush interferes with cellular behavior and function of myofibers. J Biomed Mater Res A 2019; 107:1264-1272. [PMID: 30724032 DOI: 10.1002/jbm.a.36636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 12/19/2018] [Accepted: 12/30/2018] [Indexed: 11/07/2022]
Abstract
Introducing or grafting molecules onto biomaterial surfaces to regulate muscle cell destination via biophysical cues is one of the important steps for biomaterial design in muscle tissue engineering. Therefore, it is important to understand the interaction between myoblasts and myofibers with substrates modified by biomimetic layer with different thicknesses. In this study, we used a surface-induced atom transfer radical polymerization method to synthetize and graft poly-phenoxyethyl methacrylate (PHEMA) brushes having different lengths on the glass substrates. C2C12 myoblasts were seeded on the PHEMA brushes and differentiated using horse serum, for analyzing the sensibility of muscle cells to feel environment changing, and further investigating whether the depths of grafting layer on the biomaterial surface are important factors in regulating muscle cell behaviors. Our results demonstrated that on the thicker PHEMA brushes surface (200 and 450 nm), C2C12 myoblasts showed a better survival and proliferation and were favorable for cell fusion and myotube formation. Furthermore, myofibers survived on the thicker brushes were more functional and upregulated cytoskeleton proteins (tubulin, vimentin, and vinculin) and FAK levels, and enhanced the expression levels for mechanical stress molecules (HGF, NOS-1, and c-Met). These results suggest that grafting thickness of PHEMA layer on the substrate led to the myoblasts/myofiber behavior change, which would be valuable for the design and preparation of the modified layer on muscle tissue engineering scaffolds. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1264-1272, 2019.
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Affiliation(s)
- Tao Huang
- Department of Neurosurgery, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine (Guangdong Provincial Hospital of Chinese Medicine), Guangzhou, 510120, China
| | - Jiangwei Xiao
- Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Shuhao Wang
- School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510641, China
| | - Zhaohong Liao
- Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Tao Huang
- Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Ruicai Gu
- Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Junhua Li
- Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Gang Wu
- School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510641, China
| | - Hua Liao
- Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
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39
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Braz CU, Taylor JF, Bresolin T, Espigolan R, Feitosa FLB, Carvalheiro R, Baldi F, de Albuquerque LG, de Oliveira HN. Sliding window haplotype approaches overcome single SNP analysis limitations in identifying genes for meat tenderness in Nelore cattle. BMC Genet 2019; 20:8. [PMID: 30642245 PMCID: PMC6332854 DOI: 10.1186/s12863-019-0713-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 01/02/2019] [Indexed: 12/30/2022] Open
Abstract
Background Traditional single nucleotide polymorphism (SNP) genome-wide association analysis (GWAA) can be inefficient because single SNPs provide limited genetic information about genomic regions. On the other hand, using haplotypes in the statistical analysis may increase the extent of linkage disequilibrium (LD) between haplotypes and causal variants and may also potentially capture epistastic interactions between variants within a haplotyped locus, providing an increase in the power and robustness of the association studies. We performed GWAA (413,355 SNP markers) using haplotypes based on variable-sized sliding windows and compared the results to a single-SNP GWAA using Warner-Bratzler shear force measured in the longissimus thorasis muscle of 3161 Nelore bulls to ascertain the optimal window size for identifying the genomic regions that influence meat tenderness. Results The GWAA using single SNPs identified eight variants influencing meat tenderness on BTA 3, 4, 9, 10 and 11. However, thirty-three putative meat tenderness QTL were detected on BTA 1, 3, 4, 5, 8, 9, 10, 11, 15, 17, 18, 24, 25, 26 and 29 using variable-sized sliding haplotype windows. Analyses using sliding window haplotypes of 3, 5, 7, 9 and 11 SNPs identified 57, 61, 42, 39, and 21% of all thirty-three putative QTL regions, respectively; however, the analyses using the 3 and 5 SNP haplotypes, cumulatively detected 88% of the putative QTL. The genes associated with variation in meat tenderness participate in myogenesis, neurogenesis, lipid and fatty acid metabolism and skeletal muscle structure or composition processes. Conclusions GWAA using haplotypes based on variable-sized sliding windows allowed the detection of more QTL than traditional single-SNP GWAA. Analyses using smaller haplotypes (3 and 5 SNPs) detected a higher proportion of the putative QTL. Electronic supplementary material The online version of this article (10.1186/s12863-019-0713-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Camila U Braz
- Animal Science Department, São Paulo State University (Unesp), Jaboticabal, SP, 144884-900, Brazil.
| | - Jeremy F Taylor
- Division of Animal Sciences, University of Missouri, Columbia, MO, 65211, USA
| | - Tiago Bresolin
- Animal Science Department, São Paulo State University (Unesp), Jaboticabal, SP, 144884-900, Brazil
| | - Rafael Espigolan
- Animal Science Department, São Paulo State University (Unesp), Jaboticabal, SP, 144884-900, Brazil
| | - Fabieli L B Feitosa
- Animal Science Department, São Paulo State University (Unesp), Jaboticabal, SP, 144884-900, Brazil
| | - Roberto Carvalheiro
- Animal Science Department, São Paulo State University (Unesp), Jaboticabal, SP, 144884-900, Brazil
| | - Fernando Baldi
- Animal Science Department, São Paulo State University (Unesp), Jaboticabal, SP, 144884-900, Brazil
| | - Lucia G de Albuquerque
- Animal Science Department, São Paulo State University (Unesp), Jaboticabal, SP, 144884-900, Brazil
| | - Henrique N de Oliveira
- Animal Science Department, São Paulo State University (Unesp), Jaboticabal, SP, 144884-900, Brazil.
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40
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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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41
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Bao XX, Spanos C, Kojidani T, Lynch EM, Rappsilber J, Hiraoka Y, Haraguchi T, Sawin KE. Exportin Crm1 is repurposed as a docking protein to generate microtubule organizing centers at the nuclear pore. eLife 2018; 7:e33465. [PMID: 29809148 PMCID: PMC6008054 DOI: 10.7554/elife.33465] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 05/21/2018] [Indexed: 01/04/2023] Open
Abstract
Non-centrosomal microtubule organizing centers (MTOCs) are important for microtubule organization in many cell types. In fission yeast Schizosaccharomyces pombe, the protein Mto1, together with partner protein Mto2 (Mto1/2 complex), recruits the γ-tubulin complex to multiple non-centrosomal MTOCs, including the nuclear envelope (NE). Here, we develop a comparative-interactome mass spectrometry approach to determine how Mto1 localizes to the NE. Surprisingly, we find that Mto1, a constitutively cytoplasmic protein, docks at nuclear pore complexes (NPCs), via interaction with exportin Crm1 and cytoplasmic FG-nucleoporin Nup146. Although Mto1 is not a nuclear export cargo, it binds Crm1 via a nuclear export signal-like sequence, and docking requires both Ran in the GTP-bound state and Nup146 FG repeats. In addition to determining the mechanism of MTOC formation at the NE, our results reveal a novel role for Crm1 and the nuclear export machinery in the stable docking of a cytoplasmic protein complex at NPCs.
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Affiliation(s)
- Xun X Bao
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Christos Spanos
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Tomoko Kojidani
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Department of Chemical and Biological Sciences, Faculty of ScienceJapan Women’s UniversityTokyoJapan
| | - Eric M Lynch
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
- Department of BioanalyticsInstitute of Biotechnology, Technische Universität BerlinBerlinGermany
| | - Yasushi Hiraoka
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Graduate School of Frontier BiosciencesOsaka UniversitySuitaJapan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Graduate School of Frontier BiosciencesOsaka UniversitySuitaJapan
| | - Kenneth E Sawin
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
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Muroyama A, Lechler T. Microtubule organization, dynamics and functions in differentiated cells. Development 2017; 144:3012-3021. [PMID: 28851722 DOI: 10.1242/dev.153171] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Over the past several decades, numerous studies have greatly expanded our knowledge about how microtubule organization and dynamics are controlled in cultured cells in vitro However, our understanding of microtubule dynamics and functions in vivo, in differentiated cells and tissues, remains under-explored. Recent advances in generating genetic tools and imaging technologies to probe microtubules in situ, coupled with an increased interest in the functions of this cytoskeletal network in differentiated cells, are resulting in a renaissance. Here, we discuss the lessons learned from such approaches, which have revealed that, although some differentiated cells utilize conserved strategies to remodel microtubules, there is considerable diversity in the underlying molecular mechanisms of microtubule reorganization. This highlights a continued need to explore how differentiated cells regulate microtubule geometry in vivo.
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Affiliation(s)
- Andrew Muroyama
- Departments of Dermatology and Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Terry Lechler
- Departments of Dermatology and Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
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43
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Nesprin-1α-Dependent Microtubule Nucleation from the Nuclear Envelope via Akap450 Is Necessary for Nuclear Positioning in Muscle Cells. Curr Biol 2017; 27:2999-3009.e9. [PMID: 28966089 PMCID: PMC5640514 DOI: 10.1016/j.cub.2017.08.031] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/08/2017] [Accepted: 08/15/2017] [Indexed: 11/20/2022]
Abstract
The nucleus is the main microtubule-organizing center (MTOC) in muscle cells due to the accumulation of centrosomal proteins and microtubule (MT) nucleation activity at the nuclear envelope (NE) [1, 2, 3, 4]. The relocalization of centrosomal proteins, including Pericentrin, Pcm1, and γ-tubulin, depends on Nesprin-1, an outer nuclear membrane (ONM) protein that connects the nucleus to the cytoskeleton via its N-terminal region [5, 6, 7]. Nesprins are also involved in the recruitment of kinesin to the NE and play a role in nuclear positioning in skeletal muscle cells [8, 9, 10, 11, 12]. However, a function for MT nucleation from the NE in nuclear positioning has not been established. Using the proximity-dependent biotin identification (BioID) method [13, 14], we found several centrosomal proteins, including Akap450, Pcm1, and Pericentrin, whose association with Nesprin-1α is increased in differentiated myotubes. We show that Nesprin-1α recruits Akap450 to the NE independently of kinesin and that Akap450, but not other centrosomal proteins, is required for MT nucleation from the NE. Furthermore, we demonstrate that this mechanism is disrupted in congenital muscular dystrophy patient myotubes carrying a nonsense mutation within the SYNE1 gene (23560 G>T) encoding Nesprin-1 [15, 16]. Finally, using computer simulation and cell culture systems, we provide evidence for a role of MT nucleation from the NE on nuclear spreading in myotubes. Our data thus reveal a novel function for Nesprin-1α/Nesprin-1 in nuclear positioning through recruitment of Akap450-mediated MT nucleation activity to the NE. BioID of Nesprin-1α identifies centrosomal proteins at myotube nuclear envelope Nesprin-1α-containing LINC complexes recruit Akap450 to myotube nuclear envelope Akap450 is required for microtubule nucleation at the nuclear envelope Microtubule nucleation at the nuclear envelope is involved in nuclear positioning
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44
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Fry AM, Sampson J, Shak C, Shackleton S. Recent advances in pericentriolar material organization: ordered layers and scaffolding gels. F1000Res 2017; 6:1622. [PMID: 29026530 PMCID: PMC5583744 DOI: 10.12688/f1000research.11652.1] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/01/2017] [Indexed: 12/11/2022] Open
Abstract
The centrosome is an unusual organelle that lacks a surrounding membrane, raising the question of what limits its size and shape. Moreover, while electron microscopy (EM) has provided a detailed view of centriole architecture, there has been limited understanding of how the second major component of centrosomes, the pericentriolar material (PCM), is organized. Here, we summarize exciting recent findings from super-resolution fluorescence imaging, structural biology, and biochemical reconstitution that together reveal the presence of ordered layers and complex gel-like scaffolds in the PCM. Moreover, we discuss how this is leading to a better understanding of the process of microtubule nucleation, how alterations in PCM size are regulated in cycling and differentiated cells, and why mutations in PCM components lead to specific human pathologies.
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Affiliation(s)
- Andrew M Fry
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Josephina Sampson
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Caroline Shak
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Sue Shackleton
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
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45
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Abstract
The organization of microtubule networks is crucial for controlling chromosome segregation during cell division, for positioning and transport of different organelles, and for cell polarity and morphogenesis. The geometry of microtubule arrays strongly depends on the localization and activity of the sites where microtubules are nucleated and where their minus ends are anchored. Such sites are often clustered into structures known as microtubule-organizing centers, which include the centrosomes in animals and spindle pole bodies in fungi. In addition, other microtubules, as well as membrane compartments such as the cell nucleus, the Golgi apparatus, and the cell cortex, can nucleate, stabilize, and tether microtubule minus ends. These activities depend on microtubule-nucleating factors, such as γ-tubulin-containing complexes and their activators and receptors, and microtubule minus end-stabilizing proteins with their binding partners. Here, we provide an overview of the current knowledge on how such factors work together to control microtubule organization in different systems.
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Affiliation(s)
- Jingchao Wu
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, The Netherlands; ,
| | - Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, The Netherlands; ,
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Sulimenko V, Hájková Z, Klebanovych A, Dráber P. Regulation of microtubule nucleation mediated by γ-tubulin complexes. PROTOPLASMA 2017; 254:1187-1199. [PMID: 28074286 DOI: 10.1007/s00709-016-1070-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/22/2016] [Indexed: 05/18/2023]
Abstract
The microtubule cytoskeleton is critically important for spatio-temporal organization of eukaryotic cells. The nucleation of new microtubules is typically restricted to microtubule organizing centers (MTOCs) and requires γ-tubulin that assembles into multisubunit complexes of various sizes. γ-Tubulin ring complexes (TuRCs) are efficient microtubule nucleators and are associated with large number of targeting, activating and modulating proteins. γ-Tubulin-dependent nucleation of microtubules occurs both from canonical MTOCs, such as spindle pole bodies and centrosomes, and additional sites such as Golgi apparatus, nuclear envelope, plasma membrane-associated sites, chromatin and surface of pre-existing microtubules. Despite many advances in structure of γ-tubulin complexes and characterization of γTuRC interacting factors, regulatory mechanisms of microtubule nucleation are not fully understood. Here, we review recent work on the factors and regulatory mechanisms that are involved in centrosomal and non-centrosomal microtubule nucleation.
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Affiliation(s)
- Vadym Sulimenko
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Zuzana Hájková
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Anastasiya Klebanovych
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Pavel Dráber
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic.
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47
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Nishita M, Satake T, Minami Y, Suzuki A. Regulatory mechanisms and cellular functions of non-centrosomal microtubules. J Biochem 2017; 162:1-10. [DOI: 10.1093/jb/mvx018] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 03/02/2017] [Indexed: 02/07/2023] Open
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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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49
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Sanchez AD, Feldman JL. Microtubule-organizing centers: from the centrosome to non-centrosomal sites. Curr Opin Cell Biol 2016; 44:93-101. [PMID: 27666167 DOI: 10.1016/j.ceb.2016.09.003] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/19/2016] [Accepted: 09/08/2016] [Indexed: 11/25/2022]
Abstract
The process of cellular differentiation requires the distinct spatial organization of the microtubule cytoskeleton, the arrangement of which is specific to cell type. Microtubule patterning does not occur randomly, but is imparted by distinct subcellular sites called microtubule-organizing centers (MTOCs). Since the discovery of MTOCs fifty years ago, their study has largely focused on the centrosome. All animal cells use centrosomes as MTOCs during mitosis. However in many differentiated cells, MTOC function is reassigned to non-centrosomal sites to generate non-radial microtubule organization better suited for new cell functions, such as mechanical support or intracellular transport. Here, we review the current understanding of non-centrosomal MTOCs (ncMTOCs) and the mechanisms by which they form in differentiating animal cells.
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Affiliation(s)
- Ariana D Sanchez
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA 94305, USA
| | - Jessica L Feldman
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA 94305, USA.
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50
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Zheng Y, Mennella V, Marks S, Wildonger J, Elnagdi E, Agard D, Megraw TL. The Seckel syndrome and centrosomal protein Ninein localizes asymmetrically to stem cell centrosomes but is not required for normal development, behavior, or DNA damage response in Drosophila. Mol Biol Cell 2016; 27:1740-52. [PMID: 27053665 PMCID: PMC4884065 DOI: 10.1091/mbc.e15-09-0655] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 03/28/2016] [Indexed: 12/21/2022] Open
Abstract
Ninein associates with the microtubule regulator γ-tubulin, regulates microtubule assembly, and localizes to centrosomes and noncentrosomal microtubule-organizing centers in Drosophila. Ninein localizes to stem cell centrosomes asymmetrically, with a bias for the daughter centrosome. Remarkably, Ninein is dispensable for development, fertility, or viability. Ninein (Nin) is a centrosomal protein whose gene is mutated in Seckel syndrome (SCKL, MIM 210600), an inherited recessive disease that results in primordial dwarfism, cognitive deficiencies, and increased sensitivity to genotoxic stress. Nin regulates neural stem cell self-renewal, interkinetic nuclear migration, and microtubule assembly in mammals. Nin is evolutionarily conserved, yet its role in cell division and development has not been investigated in a model organism. Here we characterize the single Nin orthologue in Drosophila. Drosophila Nin localizes to the periphery of the centrosome but not at centriolar structures as in mammals. However, Nin shares the property of its mammalian orthologue of promoting microtubule assembly. In neural and germline stem cells, Nin localizes asymmetrically to the younger (daughter) centrosome, yet it is not required for the asymmetric division of stem cells. In wing epithelia and muscle, Nin localizes to noncentrosomal microtubule-organizing centers. Surprisingly, loss of nin expression from a nin mutant does not significantly affect embryonic and brain development, fertility, or locomotor performance of mutant flies or their survival upon exposure to DNA-damaging agents. Although it is not essential, our data suggest that Nin plays a supportive role in centrosomal and extracentrosomal microtubule organization and asymmetric stem cell division.
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Affiliation(s)
- Yiming Zheng
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306-4300
| | - Vito Mennella
- Department of Biochemistry, University of Toronto, Toronto, M5G 0A4, Canada Cell Biology Program, The Hospital for Sick Children, Toronto, M5G 1X8, Canada
| | - Steven Marks
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306-4300
| | - Jill Wildonger
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706
| | - Esraa Elnagdi
- Department of Biochemistry, University of Toronto, Toronto, M5G 0A4, Canada Cell Biology Program, The Hospital for Sick Children, Toronto, M5G 1X8, Canada
| | - David Agard
- The Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143-2240
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306-4300
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