51
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Masterson J, Yıldırım B, Gökkaya E, Tokgöz Yılmaz S, Tekin M. A Novel Variant in SYNE4 Confirms its Causative Role in Sensorineural Hearing Loss. Balkan Med J 2017; 35:196-198. [PMID: 28958982 PMCID: PMC5863260 DOI: 10.4274/balkanmedj.2017.0946] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Background: Hearing loss is the most common sensory deficit with many genetic and environmental underpinnings. While causative DNA variants have been identified in over 100 genes, most deafness-causing variants are rare, apart from a few exceptions. A single SYNE4 variant co-segregating with hearing loss has recently been reported in two Middle-Eastern families. Case Report: In this report we present two members of a family with non-syndromic high frequency sensorineural hearing loss who are homozygous for a novel pathogenic SYNE4 variant c.129-1G>T. Conclusion: This case report provides supportive evidence for the causative role of SYNE4 variants in hearing loss by presenting an additional family with a novel DNA variant.
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Affiliation(s)
- John Masterson
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, USA
| | - Busegül Yıldırım
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, USA
| | - Ece Gökkaya
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, USA
| | - Suna Tokgöz Yılmaz
- Department of Audiology, Ankara University School of Medicine, Ankara, Turkey
| | - Mustafa Tekin
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, USA.,Dr. John T. Macdonald Foundation, University of Miami Miller School of Medicine, Miami, USA
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52
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Ding ZY, Wang YH, Huang YC, Lee MC, Tseng MJ, Chi YH, Huang ML. Outer nuclear membrane protein Kuduk modulates the LINC complex and nuclear envelope architecture. J Cell Biol 2017; 216:2827-2841. [PMID: 28716842 PMCID: PMC5584142 DOI: 10.1083/jcb.201606043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 05/25/2017] [Accepted: 06/15/2017] [Indexed: 11/25/2022] Open
Abstract
LINC complexes connect the inner and outer nuclear membrane (ONM) to transduce nucleocytoskeletal force. Ding et al. identify an ONM protein, Kuduk/TMEM258, which modulates the quality of LINC complexes and regulates the nuclear envelope architecture, nuclear positioning, and the development of ovarian follicles. Linker of nucleoskeleton and cytoskeleton (LINC) complexes spanning the nuclear envelope (NE) contribute to nucleocytoskeletal force transduction. A few NE proteins have been found to regulate the LINC complex. In this study, we identify one, Kuduk (Kud), which can reside at the outer nuclear membrane and is required for the development of Drosophila melanogaster ovarian follicles and NE morphology of myonuclei. Kud associates with LINC complex components in an evolutionarily conserved manner. Loss of Kud increases the level but impairs functioning of the LINC complex. Overexpression of Kud suppresses NE targeting of cytoskeleton-free LINC complexes. Thus, Kud acts as a quality control mechanism for LINC-mediated nucleocytoskeletal connections. Genetic data indicate that Kud also functions independently of the LINC complex. Overexpression of the human orthologue TMEM258 in Drosophila proved functional conservation. These findings expand our understanding of the regulation of LINC complexes and NE architecture.
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Affiliation(s)
- Zhao-Ying Ding
- Department of Life Science, National Chung-Cheng University, Chiayi, Taiwan
| | - Ying-Hsuan Wang
- Department of Life Science, National Chung-Cheng University, Chiayi, Taiwan
| | - Yu-Cheng Huang
- Department of Life Science, National Chung-Cheng University, Chiayi, Taiwan
| | - Myong-Chol Lee
- Department of Life Science, National Chung-Cheng University, Chiayi, Taiwan
| | - Min-Jen Tseng
- Department of Life Science, National Chung-Cheng University, Chiayi, Taiwan
| | - Ya-Hui Chi
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli, Taiwan
| | - Min-Lang Huang
- Department of Life Science, National Chung-Cheng University, Chiayi, Taiwan
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53
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Janin A, Bauer D, Ratti F, Millat G, Méjat A. Nuclear envelopathies: a complex LINC between nuclear envelope and pathology. Orphanet J Rare Dis 2017; 12:147. [PMID: 28854936 PMCID: PMC5577761 DOI: 10.1186/s13023-017-0698-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 08/22/2017] [Indexed: 12/11/2022] Open
Abstract
Since the identification of the first disease causing mutation in the gene coding for emerin, a transmembrane protein of the inner nuclear membrane, hundreds of mutations and variants have been found in genes encoding for nuclear envelope components. These proteins can be part of the inner nuclear membrane (INM), such as emerin or SUN proteins, outer nuclear membrane (ONM), such as Nesprins, or the nuclear lamina, such as lamins A and C. However, they physically interact with each other to insure the nuclear envelope integrity and mediate the interactions of the nuclear envelope with both the genome, on the inner side, and the cytoskeleton, on the outer side. The core of this complex, called LINC (LInker of Nucleoskeleton to Cytoskeleton) is composed of KASH and SUN homology domain proteins. SUN proteins are INM proteins which interact with lamins by their N-terminal domain and with the KASH domain of nesprins located in the ONM by their C-terminal domain.Although most of these proteins are ubiquitously expressed, their mutations have been associated with a large number of clinically unrelated pathologies affecting specific tissues. Moreover, variants in SUN proteins have been found to modulate the severity of diseases induced by mutations in other LINC components or interactors. For these reasons, the diagnosis and the identification of the molecular explanation of "nuclear envelopathies" is currently challenging.The aim of this review is to summarize the human diseases caused by mutations in genes coding for INM proteins, nuclear lamina, and ONM proteins, and to discuss their potential physiopathological mechanisms that could explain the large spectrum of observed symptoms.
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Affiliation(s)
- Alexandre Janin
- University Lyon, Université Claude Bernard Lyon 1, Institut NeuroMyoGène, F-69622, Villeurbanne, France.,CNRS UMR 5310, F-69622, Villeurbanne, France.,INSERM U1217, F-69622, Villeurbanne, France.,Laboratoire de Cardiogénétique Moléculaire, Centre de Biologie et Pathologie Est, Hospices Civils de Lyon, Lyon, France
| | - Delphine Bauer
- University Lyon, Université Claude Bernard Lyon 1, Institut NeuroMyoGène, F-69622, Villeurbanne, France.,CNRS UMR 5310, F-69622, Villeurbanne, France.,INSERM U1217, F-69622, Villeurbanne, France
| | - Francesca Ratti
- University Lyon, Université Claude Bernard Lyon 1, Institut NeuroMyoGène, F-69622, Villeurbanne, France.,CNRS UMR 5310, F-69622, Villeurbanne, France.,INSERM U1217, F-69622, Villeurbanne, France
| | - Gilles Millat
- University Lyon, Université Claude Bernard Lyon 1, Institut NeuroMyoGène, F-69622, Villeurbanne, France.,CNRS UMR 5310, F-69622, Villeurbanne, France.,INSERM U1217, F-69622, Villeurbanne, France.,Laboratoire de Cardiogénétique Moléculaire, Centre de Biologie et Pathologie Est, Hospices Civils de Lyon, Lyon, France
| | - Alexandre Méjat
- University Lyon, Université Claude Bernard Lyon 1, Institut NeuroMyoGène, F-69622, Villeurbanne, France. .,CNRS UMR 5310, F-69622, Villeurbanne, France. .,INSERM U1217, F-69622, Villeurbanne, France. .,Nuclear Architecture Team, Institut NeuroMyoGène, CNRS UMR 5310 - INSERM U1217 - Université de Lyon - Université Claude Bernard Lyon 1, Lyon, France. .,Groupement Hospitalier Est - Centre de Biologie Est - Laboratoire de Cardiogénétique, 59 Boulevard Pinel, 69677, Bron, France.
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54
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Abstract
Moving the nucleus to a specific position within the cell is an important event during many cell and developmental processes. Several different molecular mechanisms exist to position nuclei in various cell types. In this Commentary, we review the recent progress made in elucidating mechanisms of nuclear migration in a variety of important developmental models. Genetic approaches to identify mutations that disrupt nuclear migration in yeast, filamentous fungi, Caenorhabditis elegans, Drosophila melanogaster and plants led to the identification of microtubule motors, as well as Sad1p, UNC-84 (SUN) domain and Klarsicht, ANC-1, Syne homology (KASH) domain proteins (LINC complex) that function to connect nuclei to the cytoskeleton. We focus on how these proteins and various mechanisms move nuclei during vertebrate development, including processes related to wound healing of fibroblasts, fertilization, developing myotubes and the developing central nervous system. We also describe how nuclear migration is involved in cells that migrate through constricted spaces. On the basis of these findings, it is becoming increasingly clear that defects in nuclear positioning are associated with human diseases, syndromes and disorders.
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Affiliation(s)
- Courtney R Bone
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
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55
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Monis WJ, Faundez V, Pazour GJ. BLOC-1 is required for selective membrane protein trafficking from endosomes to primary cilia. J Cell Biol 2017; 216:2131-2150. [PMID: 28576874 PMCID: PMC5496619 DOI: 10.1083/jcb.201611138] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 03/24/2017] [Accepted: 05/03/2017] [Indexed: 11/30/2022] Open
Abstract
Monis et al. demonstrate that the BLOC-1 protein complex is required for trafficking polycystin-2, but not fibrocystin or smoothened, from endosomes to primary cilia. This is the first demonstration of a role for BLOC-1 in ciliary assembly and emphasizes the complexity of distinct ciliary membrane protein trafficking routes. Primary cilia perceive the extracellular environment through receptors localized in the ciliary membrane, but mechanisms directing specific proteins to this domain are poorly understood. To address this question, we knocked down proteins potentially important for ciliary membrane targeting and determined how this affects the ciliary trafficking of fibrocystin, polycystin-2, and smoothened. Our analysis showed that fibrocystin and polycystin-2 are dependent on IFT20, GMAP210, and the exocyst complex, while smoothened delivery is largely independent of these components. In addition, we found that polycystin-2, but not smoothened or fibrocystin, requires the biogenesis of lysosome-related organelles complex-1 (BLOC-1) for ciliary delivery. Consistent with the role of BLOC-1 in sorting from the endosome, we find that disrupting the recycling endosome reduces ciliary polycystin-2 and causes its accumulation in the recycling endosome. This is the first demonstration of a role for BLOC-1 in ciliary assembly and highlights the complexity of pathways taken to the cilium.
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Affiliation(s)
- William J Monis
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Victor Faundez
- Department of Cell Biology, Emory University, Atlanta, GA
| | - Gregory J Pazour
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
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56
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The Nucleoporin Nup2 Contains a Meiotic-Autonomous Region that Promotes the Dynamic Chromosome Events of Meiosis. Genetics 2017; 206:1319-1337. [PMID: 28455351 DOI: 10.1534/genetics.116.194555] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 04/17/2017] [Indexed: 11/18/2022] Open
Abstract
Meiosis is a specialized cellular program required to create haploid gametes from diploid parent cells. Homologous chromosomes pair, synapse, and recombine in a dynamic environment that accommodates gross chromosome reorganization and significant chromosome motion, which are critical for normal chromosome segregation. In Saccharomyces cerevisiae, Ndj1 is a meiotic telomere-associated protein required for physically attaching telomeres to proteins embedded in the nuclear envelope. In this study, we identified additional proteins that act at the nuclear periphery from meiotic cell extracts, including Nup2, a nonessential nucleoporin with a known role in tethering interstitial chromosomal loci to the nuclear pore complex. We found that deleting NUP2 affects meiotic progression and spore viability, and gives increased levels of recombination intermediates and products. We identified a previously uncharacterized 125 aa region of Nup2 that is necessary and sufficient for its meiotic function, thus behaving as a meiotic autonomous region (MAR). Nup2-MAR forms distinct foci on spread meiotic chromosomes, with a subset overlapping with Ndj1 foci. Localization of Nup2-MAR to meiotic chromosomes does not require Ndj1, nor does Ndj1 localization require Nup2, suggesting these proteins function in different pathways, and their interaction is weak or indirect. Instead, several severe synthetic phenotypes are associated with the nup2Δ ndj1Δ double mutant, including delayed turnover of recombination joint molecules, and a failure to undergo nuclear divisions without also arresting the meiotic program. These data suggest Nup2 and Ndj1 support partially overlapping functions that promote two different levels of meiotic chromosome organization necessary to withstand a dynamic stage of the eukaryotic life cycle.
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57
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Abstract
Stem cells are characterized by their self-renewal and multi-lineage differentiation potential. Stem cell differentiation is a prerequisite for the application of stem cells in regenerative medicine and clinical therapy. In addition to chemical stimulation, mechanical cues play a significant role in regulating stem cell differentiation. The integrity of mechanical sensors is necessary for the ability of cells to respond to mechanical signals. The nucleus, the largest and stiffest cellular organelle, interacts with the cytoskeleton as a key mediator of cell mechanics. Nuclear mechanics are involved in the complicated interactions of lamins, chromatin and nucleoskeleton-related proteins. Thus, stem cell differentiation is intimately associated with nuclear mechanics due to its indispensable role in mechanotransduction and mechanical response. This paper reviews several main contributions of nuclear mechanics, highlights the hallmarks of the nuclear mechanics of stem cells, and provides insight into the relationship between nuclear mechanics and stem cell differentiation, which may guide clinical applications in the future.
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58
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Vogl C, Panou I, Yamanbaeva G, Wichmann C, Mangosing SJ, Vilardi F, Indzhykulian AA, Pangršič T, Santarelli R, Rodriguez-Ballesteros M, Weber T, Jung S, Cardenas E, Wu X, Wojcik SM, Kwan KY, Del Castillo I, Schwappach B, Strenzke N, Corey DP, Lin SY, Moser T. Tryptophan-rich basic protein (WRB) mediates insertion of the tail-anchored protein otoferlin and is required for hair cell exocytosis and hearing. EMBO J 2016; 35:2536-2552. [PMID: 27458190 DOI: 10.15252/embj.201593565] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 05/29/2016] [Accepted: 06/10/2016] [Indexed: 12/21/2022] Open
Abstract
The transmembrane recognition complex (TRC40) pathway mediates the insertion of tail-anchored (TA) proteins into membranes. Here, we demonstrate that otoferlin, a TA protein essential for hair cell exocytosis, is inserted into the endoplasmic reticulum (ER) via the TRC40 pathway. We mutated the TRC40 receptor tryptophan-rich basic protein (Wrb) in hair cells of zebrafish and mice and studied the impact of defective TA protein insertion. Wrb disruption reduced otoferlin levels in hair cells and impaired hearing, which could be restored in zebrafish by transgenic Wrb rescue and otoferlin overexpression. Wrb-deficient mouse inner hair cells (IHCs) displayed normal numbers of afferent synapses, Ca2+ channels, and membrane-proximal vesicles, but contained fewer ribbon-associated vesicles. Patch-clamp of IHCs revealed impaired synaptic vesicle replenishment. In vivo recordings from postsynaptic spiral ganglion neurons showed a use-dependent reduction in sound-evoked spiking, corroborating the notion of impaired IHC vesicle replenishment. A human mutation affecting the transmembrane domain of otoferlin impaired its ER targeting and caused an auditory synaptopathy. We conclude that the TRC40 pathway is critical for hearing and propose that otoferlin is an essential substrate of this pathway in hair cells.
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Affiliation(s)
- Christian Vogl
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Iliana Panou
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Göttingen Graduate School for Neurosciences, Biophysics and Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Gulnara Yamanbaeva
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Auditory Systems Physiology Group and InnerEarLab, Department of Otolaryngology, University of Göttingen Medical Center, Göttingen, Germany
| | - Carolin Wichmann
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Sara J Mangosing
- Otolaryngology Division, Department of Surgery, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Fabio Vilardi
- Institute of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Artur A Indzhykulian
- Howard Hughes Medical Institute and Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Tina Pangršič
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Synaptic Physiology of Mammalian Vestibular Hair Cells Junior Research Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Rosamaria Santarelli
- Department of Neurosciences, University of Padova, Padova, Italy.,Audiology and Phoniatrics Service, Treviso Regional Hospital, Treviso, Italy
| | | | - Thomas Weber
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Sangyong Jung
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Elena Cardenas
- Otolaryngology Division, Department of Surgery, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Xudong Wu
- Howard Hughes Medical Institute and Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Sonja M Wojcik
- Department of Molecular Neurobiology, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
| | - Kelvin Y Kwan
- W. M. Keck Center for Collaborative Neuroscience, Nelson Lab-D250, Rutgers University, Piscataway, NJ, USA
| | - Ignacio Del Castillo
- Servicio de Genetica, Hospital Universitario Ramon y Cajal, IRYCIS, Madrid, Spain.,Centro de Investigacion Biomedica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Blanche Schwappach
- Institute of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Nicola Strenzke
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Auditory Systems Physiology Group and InnerEarLab, Department of Otolaryngology, University of Göttingen Medical Center, Göttingen, Germany
| | - David P Corey
- Howard Hughes Medical Institute and Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Shuh-Yow Lin
- Otolaryngology Division, Department of Surgery, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany .,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
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59
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Jahed Z, Shams H, Mofrad MRK. A Disulfide Bond Is Required for the Transmission of Forces through SUN-KASH Complexes. Biophys J 2016; 109:501-9. [PMID: 26244732 DOI: 10.1016/j.bpj.2015.06.057] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 06/08/2015] [Accepted: 06/29/2015] [Indexed: 11/28/2022] Open
Abstract
Numerous biological functions of a cell, including polarization, differentiation, division, and migration, rely on its ability to endure mechanical forces generated by the cytoskeleton on the nucleus. Coupling of the cytoskeleton and nucleoskeleton is ultimately mediated by LINC complexes that are formed via a strong interaction between SUN- and KASH-domain-containing proteins in the nuclear envelope. These complexes are mechanosensitive and essential for the transmission of forces between the cytoskeleton and nucleoskeleton, and the progression of cellular mechanotransduction. Herein, using molecular dynamics, we examine the effect of tension on the human SUN2-KASH2 complex and show that it is remarkably stable under physiologically relevant tensile forces and large strains. However, a covalent disulfide bond between two highly conserved cysteine residues of SUN2 and KASH2 is crucial for the stability of this interaction and the transmission of forces through the complex.
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Affiliation(s)
- Zeinab Jahed
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California Berkeley, Berkeley, California
| | - Hengameh Shams
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California Berkeley, Berkeley, California
| | - Mohammad R K Mofrad
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California Berkeley, Berkeley, California; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California.
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60
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Mechanotransduction and nuclear function. Curr Opin Cell Biol 2016; 40:98-105. [PMID: 27018929 DOI: 10.1016/j.ceb.2016.03.006] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 02/16/2016] [Accepted: 03/08/2016] [Indexed: 12/23/2022]
Abstract
Many signaling pathways converge on the nucleus to regulate crucial nuclear events such as transcription, DNA replication and cell cycle progression. Although the vast majority of research in this area has focused on signals generated in response to hormones or other soluble factors, the nucleus also responds to mechanical forces. During the past decade or so, much has been learned about how mechanical force can affect transcription, as well as the growth and differentiation of cells. Much has also been learned about how force is transmitted via the cytoskeleton to the nucleus and then across the nuclear envelope to the nuclear lamina and chromatin. In this brief review, we focus on some of the key proteins that transmit mechanical signals across the nuclear envelope.
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61
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Uzer G, Thompson WR, Sen B, Xie Z, Yen SS, Miller S, Bas G, Styner M, Rubin CT, Judex S, Burridge K, Rubin J. Cell Mechanosensitivity to Extremely Low-Magnitude Signals Is Enabled by a LINCed Nucleus. Stem Cells 2016; 33:2063-76. [PMID: 25787126 DOI: 10.1002/stem.2004] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 01/19/2015] [Accepted: 02/19/2015] [Indexed: 12/21/2022]
Abstract
A cell's ability to recognize and adapt to the physical environment is central to its survival and function, but how mechanical cues are perceived and transduced into intracellular signals remains unclear. In mesenchymal stem cells (MSCs), high-magnitude substrate strain (HMS, ≥2%) effectively suppresses adipogenesis via induction of focal adhesion (FA) kinase (FAK)/mTORC2/Akt signaling generated at FAs. Physiologic systems also rely on a persistent barrage of low-level signals to regulate behavior. Exposing MSC to extremely low-magnitude mechanical signals (LMS) suppresses adipocyte formation despite the virtual absence of substrate strain (<0.001%), suggesting that LMS-induced dynamic accelerations can generate force within the cell. Here, we show that MSC response to LMS is enabled through mechanical coupling between the cytoskeleton and the nucleus, in turn activating FAK and Akt signaling followed by FAK-dependent induction of RhoA. While LMS and HMS synergistically regulated FAK activity at the FAs, LMS-induced actin remodeling was concentrated at the perinuclear domain. Preventing nuclear-actin cytoskeleton mechanocoupling by disrupting linker of nucleoskeleton and cytoskeleton (LINC) complexes inhibited these LMS-induced signals as well as prevented LMS repression of adipogenic differentiation, highlighting that LINC connections are critical for sensing LMS. In contrast, FAK activation by HMS was unaffected by LINC decoupling, consistent with signal initiation at the FA mechanosome. These results indicate that the MSC responds to its dynamic physical environment not only with "outside-in" signaling initiated by substrate strain, but vibratory signals enacted through the LINC complex enable matrix independent "inside-inside" signaling.
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Affiliation(s)
- Gunes Uzer
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - William R Thompson
- School of Physical Therapy, Indiana University, Indianapolis, Indiana, USA
| | - Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Sherwin S Yen
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Sean Miller
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Guniz Bas
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Clinton T Rubin
- Department of Biomedical Engineering, State University of New York, Stony Brook, New York, USA
| | - Stefan Judex
- Department of Biomedical Engineering, State University of New York, Stony Brook, New York, USA
| | - Keith Burridge
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
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62
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Uzer G, Fuchs RK, Rubin J, Thompson WR. Concise Review: Plasma and Nuclear Membranes Convey Mechanical Information to Regulate Mesenchymal Stem Cell Lineage. Stem Cells 2016; 34:1455-63. [PMID: 26891206 DOI: 10.1002/stem.2342] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 12/14/2015] [Accepted: 12/29/2015] [Indexed: 12/21/2022]
Abstract
Numerous factors including chemical, hormonal, spatial, and physical cues determine stem cell fate. While the regulation of stem cell differentiation by soluble factors is well-characterized, the role of mechanical force in the determination of lineage fate is just beginning to be understood. Investigation of the role of force on cell function has largely focused on "outside-in" signaling, initiated at the plasma membrane. When interfaced with the extracellular matrix, the cell uses integral membrane proteins, such as those found in focal adhesion complexes to translate force into biochemical signals. Akin to these outside-in connections, the internal cytoskeleton is physically linked to the nucleus, via proteins that span the nuclear membrane. Although structurally and biochemically distinct, these two forms of mechanical coupling influence stem cell lineage fate and, when disrupted, often lead to disease. Here we provide an overview of how mechanical coupling occurs at the plasma and nuclear membranes. We also discuss the role of force on stem cell differentiation, with focus on the biochemical signals generated at the cell membrane and the nucleus, and how those signals influence various diseases. While the interaction of stem cells with their physical environment and how they respond to force is complex, an understanding of the mechanical regulation of these cells is critical in the design of novel therapeutics to combat diseases associated with aging, cancer, and osteoporosis. Stem Cells 2016;34:1455-1463.
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Affiliation(s)
- Gunes Uzer
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Robyn K Fuchs
- School of Health and Rehabilitation Sciences, Department of Physical Therapy, Indiana University, Indianapolis, Indiana, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - William R Thompson
- School of Health and Rehabilitation Sciences, Department of Physical Therapy, Indiana University, Indianapolis, Indiana, USA
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63
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Depletion of the LINC complex disrupts cytoskeleton dynamics and meiotic resumption in mouse oocytes. Sci Rep 2016; 6:20408. [PMID: 26842404 PMCID: PMC4740751 DOI: 10.1038/srep20408] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 01/04/2016] [Indexed: 01/17/2023] Open
Abstract
The SUN (Sad-1/UNC-84) and KASH (Klarsicht/ANC-1/Syne/homology) proteins constitute the linker of nucleoskeleton and cytoskeleton (LINC) complex on the nuclear envelope. To date, the SUN1/KASH5 complex is known to function as meiotic-specific factors. In this study, gene-silencing methods were used to explore the roles of SUN1 and KASH5 in mouse oocytes after prophase. SUN1 was detected throughout the nucleus; however, KASH5 was dispersed through the cell. After germinal vesicle breakdown (GVBD), SUN1 and KASH5 migrated during spindle formation and localized to the spindle poles at the MII stage. Most oocytes were arrested at the germinal vesicle (GV) stage after depletion of either SUN1 or KASH5. The DNA damage response was triggered in SUN1-depleted oocytes and thus gave rise to the G2/M checkpoint protein, p-CHK1. Oocytes that underwent GVBD had relatively small and abnormal spindles and lower levels of cytoplasm F-actin mesh. Immunofluorescence results also indicated the dislocation of pericentrin and P150Glued after SUN1 or KASH5 depletion. Furthermore, KASH5 localized exclusively near the oocyte cortex after SUN1 depletion, but SUN1 localization was unaffected in KASH5-depleted oocytes. Taken together, the results suggest that SUN1 and KASH5 are essential factors in the regulation of meiotic resumption and spindle formation.
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Abstract
Mechanoresponses in mesenchymal stem cells (MSCs) guide both differentiation and function. In this review, we focus on advances in0 our understanding of how the cytoplasmic cytoskeleton, nuclear envelope and nucleoskeleton, which are connected via LINC (Linker of Nucleoskeleton and Cytoskeleton) complexes, are emerging as an integrated dynamic signaling platform to regulate MSC mechanobiology. This dynamic interconnectivity affects mechanical signaling and transfer of signals into the nucleus. In this way, nuclear and LINC-mediated cytoskeletal connectivity play a critical role in maintaining mechanical signaling that affects MSC fate by serving as both mechanosensory and mechanoresponsive structures. We review disease and age related compromises of LINC complexes and nucleoskeleton that contribute to the etiology of musculoskeletal diseases. Finally we invite the idea that acquired dysfunctions of LINC might be a contributing factor to conditions such as aging, microgravity and osteoporosis and discuss potential mechanical strategies to modulate LINC connectivity to combat these conditions.
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65
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The role of endothelial mechanosensitive genes in atherosclerosis and omics approaches. Arch Biochem Biophys 2015; 591:111-31. [PMID: 26686737 DOI: 10.1016/j.abb.2015.11.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/29/2015] [Accepted: 11/04/2015] [Indexed: 12/24/2022]
Abstract
Atherosclerosis is the leading cause of morbidity and mortality in the U.S., and is a multifactorial disease that preferentially occurs in regions of the arterial tree exposed to disturbed blood flow. The detailed mechanisms by which d-flow induces atherosclerosis involve changes in the expression of genes, epigenetic patterns, and metabolites of multiple vascular cells, especially endothelial cells. This review presents an overview of endothelial mechanobiology and its relation to the pathogenesis of atherosclerosis with special reference to the anatomy of the artery and the underlying fluid mechanics, followed by a discussion of a variety of experimental models to study the role of fluid mechanics and atherosclerosis. Various in vitro and in vivo models to study the role of flow in endothelial biology and pathobiology are discussed in this review. Furthermore, strategies used for the global profiling of the genome, transcriptome, miR-nome, DNA methylome, and metabolome, as they are important to define the biological and pathophysiological mechanisms of atherosclerosis. These "omics" approaches, especially those which derive data based on a single animal model, provide unprecedented opportunities to not only better understand the pathophysiology of atherosclerosis development in a holistic and integrative manner, but also to identify novel molecular and diagnostic targets.
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66
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Bhonker Y, Abu-Rayyan A, Ushakov K, Amir-Zilberstein L, Shivatzki S, Yizhar-Barnea O, Elkan-Miller T, Tayeb-Fligelman E, Kim SM, Landau M, Kanaan M, Chen P, Matsuzaki F, Sprinzak D, Avraham KB. The GPSM2/LGN GoLoco motifs are essential for hearing. Mamm Genome 2015; 27:29-46. [PMID: 26662512 DOI: 10.1007/s00335-015-9614-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/17/2015] [Indexed: 11/24/2022]
Abstract
The planar cell polarity (PCP) pathway is responsible for polarizing and orienting cochlear hair cells during development through movement of a primary cilium, the kinocilium. GPSM2/LGN, a mitotic spindle-orienting protein associated with deafness in humans, is a PCP effector involved in kinocilium migration. Here, we link human and mouse truncating mutations in the GPSM2/LGN gene, both leading to hearing loss. The human variant, p.(Trp326*), was identified by targeted genomic enrichment of genes associated with deafness, followed by massively parallel sequencing. Lgn (ΔC) mice, with a targeted deletion truncating the C-terminal GoLoco motifs, are profoundly deaf and show misorientation of the hair bundle and severe malformations in stereocilia shape that deteriorates over time. Full-length protein levels are greatly reduced in mutant mice, with upregulated mRNA levels. The truncated Lgn (ΔC) allele is translated in vitro, suggesting that mutant mice may have partially functioning Lgn. Gαi and aPKC, known to function in the same pathway as Lgn, are dependent on Lgn for proper localization. The polarization of core PCP proteins is not affected in Lgn mutants; however, Lgn and Gαi are misoriented in a PCP mutant, supporting the role of Lgn as a PCP effector. The kinocilium, previously shown to be dependent on Lgn for robust localization, is essential for proper localization of Lgn, as well as Gαi and aPKC, suggesting that cilium function plays a role in positioning of apical proteins. Taken together, our data provide a mechanism for the loss of hearing found in human patients with GPSM2/LGN variants.
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Affiliation(s)
- Yoni Bhonker
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Amal Abu-Rayyan
- Department of Biological Sciences, Bethlehem University, Bethlehem, Palestine
| | - Kathy Ushakov
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Liat Amir-Zilberstein
- Department of Biochemistry and Molecular Biology, Weiss Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Shaked Shivatzki
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Ofer Yizhar-Barnea
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Tal Elkan-Miller
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Einav Tayeb-Fligelman
- Department of Biology, Technion-Israel Institute of Technology, 32000, Haifa, Israel
| | - Sun Myoung Kim
- Department of Cell Biology, Emory University, Atlanta, GA, 30322, USA
| | - Meytal Landau
- Department of Biology, Technion-Israel Institute of Technology, 32000, Haifa, Israel
| | - Moien Kanaan
- Department of Biological Sciences, Bethlehem University, Bethlehem, Palestine
| | - Ping Chen
- Department of Cell Biology, Emory University, Atlanta, GA, 30322, USA
| | - Fumio Matsuzaki
- Laboratory of Cell Asymmetry, Center for Developmental Biology, Riken, Kobe, 650-0047, Japan
| | - David Sprinzak
- Department of Biochemistry and Molecular Biology, Weiss Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Karen B Avraham
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel.
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67
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Kim DI, Birendra KC, Roux KJ. Making the LINC: SUN and KASH protein interactions. Biol Chem 2015; 396:295-310. [PMID: 25720065 DOI: 10.1515/hsz-2014-0267] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/20/2015] [Indexed: 01/15/2023]
Abstract
Cell nuclei are physically integrated with the cytoskeleton through the linker of nucleoskeleton and cytoskeleton (LINC) complex, a structure that spans the nuclear envelope to link the nucleoskeleton and cytoskeleton. Outer nuclear membrane KASH domain proteins and inner nuclear membrane SUN domain proteins interact to form the core of the LINC complex. In this review, we provide a comprehensive analysis of the reported protein-protein interactions for KASH and SUN domain proteins. This critical structure, directly connecting the genome with the rest of the cell, contributes to a myriad of cellular functions and, when perturbed, is associated with human disease.
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Almeida FV, Walko G, McMillan JR, McGrath JA, Wiche G, Barber AH, Connelly JT. The cytolinker plectin regulates nuclear mechanotransduction in keratinocytes. J Cell Sci 2015; 128:4475-86. [PMID: 26527396 DOI: 10.1242/jcs.173435] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Accepted: 10/26/2015] [Indexed: 01/14/2023] Open
Abstract
The transmission of mechanical forces to the nucleus is important for intracellular positioning, mitosis and cell motility, yet the contribution of specific components of the cytoskeleton to nuclear mechanotransduction remains unclear. In this study, we examine how crosstalk between the cytolinker plectin and F-actin controls keratin network organisation and the 3D nuclear morphology of keratinocytes. Using micro-patterned surfaces to precisely manipulate cell shape, we find that cell adhesion and spreading regulate the size and shape of the nucleus. Disruption of the keratin cytoskeleton through loss of plectin facilitated greater nuclear deformation, which depended on acto-myosin contractility. Nuclear morphology did not depend on direct linkage of the keratin cytoskeleton with the nuclear membrane, rather loss of plectin reduced keratin filament density around the nucleus. We further demonstrate that keratinocytes have abnormal nuclear morphologies in the epidermis of plectin-deficient, epidermolysis bullosa simplex patients. Taken together, our data demonstrate that plectin is an essential regulator of nuclear morphology in vitro and in vivo and protects the nucleus from mechanical deformation.
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Affiliation(s)
- Filipe V Almeida
- School of Engineering and Materials Science, Queen Mary, University of London, London, E1 4NS UK Centre for Cell Biology and Cutaneous Research, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, London, E1 2AT UK
| | - Gernot Walko
- Centre for Stem Cells and Regenerative Medicine, King's College London, London, SE1 9RT UK
| | - James R McMillan
- The National Diagnostic EB Laboratory, Viapath, St Thomas' Hospital, London, SE1 7EH UK
| | - John A McGrath
- St John's Institute of Dermatology, King's College London (Guy's Campus), London, SE1 9RT UK
| | - Gerhard Wiche
- Max F. Perutz Laboratories, Department of Biochemistry and Cell Biology, University of Vienna, 1030 Vienna, Austria
| | - Asa H Barber
- School of Engineering and Materials Science, Queen Mary, University of London, London, E1 4NS UK
| | - John T Connelly
- Centre for Cell Biology and Cutaneous Research, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, London, E1 2AT UK
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69
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Abstract
Molecular tethers span the nuclear envelope to mechanically connect the cytoskeleton and nucleoskeleton. These bridge-like tethers, termed linkers of nucleoskeleton and cytoskeleton (LINC) complexes, consist of SUN proteins at the inner nuclear membrane and KASH proteins at the outer nuclear membrane. LINC complexes are central to a variety of cell activities including nuclear positioning and mechanotransduction, and LINC-related abnormalities are associated with a spectrum of tissue-specific diseases, termed laminopathies or envelopathies. Protocols used to study the biochemical and structural characteristics of core elements of SUN-KASH complexes are described here to facilitate further studies in this new field of cell biology.
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70
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Mattout A, Cabianca DS, Gasser SM. Chromatin states and nuclear organization in development--a view from the nuclear lamina. Genome Biol 2015; 16:174. [PMID: 26303512 PMCID: PMC4549078 DOI: 10.1186/s13059-015-0747-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The spatial distribution of chromatin domains in interphase nuclei changes dramatically during development in multicellular organisms. A crucial question is whether nuclear organization is a cause or a result of differentiation. Genetic perturbation of lamina–heterochromatin interactions is helping to reveal the cross-talk between chromatin states and nuclear organization.
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Affiliation(s)
- Anna Mattout
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058, Basel, Switzerland.
| | - Daphne S Cabianca
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058, Basel, Switzerland.
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058, Basel, Switzerland. .,University of Basel, Faculty of Natural Sciences, Klingelbergstrasse 50, CH-4056, Basel, Switzerland.
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71
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Dahmani M, Ammar-Khodja F, Bonnet C, Lefèvre GM, Hardelin JP, Ibrahim H, Mallek Z, Petit C. EPS8L2 is a new causal gene for childhood onset autosomal recessive progressive hearing loss. Orphanet J Rare Dis 2015; 10:96. [PMID: 26282398 PMCID: PMC4539681 DOI: 10.1186/s13023-015-0316-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 08/03/2015] [Indexed: 12/21/2022] Open
Abstract
Background More than 70 % of the cases of congenital deafness are of genetic origin, of which approximately 80 % are non-syndromic and show autosomal recessive transmission (DFNB forms). To date, 60 DFNB genes have been identified, most of which cause congenital, severe to profound deafness, whereas a few cause delayed progressive deafness in childhood. We report the study of two Algerian siblings born to consanguineous parents, and affected by progressive hearing loss. Method After exclusion of GJB2 (the gene most frequently involved in non-syndromic deafness in Mediterranean countries), we performed whole-exome sequencing in one sibling. Results A frame-shift variant (c.1014delC; p.Ser339Alafs*15) was identified in EPS8L2, encoding Epidermal growth factor receptor Pathway Substrate 8 L2, a protein of hair cells’ stereocilia previously implicated in progressive deafness in the mouse. This variant predicts a truncated, inactive protein, or no protein at all owing to nonsense-mediated mRNA decay. It was detected at the homozygous state in the two clinically affected siblings, and at the heterozygous state in the unaffected parents and one unaffected sibling, whereas it was never found in a control population of 150 Algerians with normal hearing or in the Exome Variant Server database. Conclusion Whole-exome sequencing allowed us to identify a new gene responsible for childhood progressive hearing loss transmitted on the autosomal recessive mode.
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Affiliation(s)
- Malika Dahmani
- Equipe de Génétique, Laboratoire de Biologie Cellulaire et Moléculaire, Faculté des Sciences Biologiques, Université des Sciences et de la Technologie Houari Boumédiène (USTHB), El Alia, Bab-Ezzouar, Algiers, Algeria.
| | - Fatima Ammar-Khodja
- Equipe de Génétique, Laboratoire de Biologie Cellulaire et Moléculaire, Faculté des Sciences Biologiques, Université des Sciences et de la Technologie Houari Boumédiène (USTHB), El Alia, Bab-Ezzouar, Algiers, Algeria.
| | - Crystel Bonnet
- Syndrome de Usher et autres Atteintes Rétino-Cochléaires, Institut de la vision, 75012, Paris, France. .,UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France. .,Sorbonne Universités, UPMC Université Paris 06, Complexité du Vivant, Paris, 75252 Cedex 05, France.
| | - Gaelle M Lefèvre
- Syndrome de Usher et autres Atteintes Rétino-Cochléaires, Institut de la vision, 75012, Paris, France. .,UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France. .,Sorbonne Universités, UPMC Université Paris 06, Complexité du Vivant, Paris, 75252 Cedex 05, France.
| | - Jean-Pierre Hardelin
- UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France. .,Sorbonne Universités, UPMC Université Paris 06, Complexité du Vivant, Paris, 75252 Cedex 05, France. .,Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015, Paris, France.
| | - Hassina Ibrahim
- Service d'otorhinolaryngologie, Centre Hospitalier Universitaire Mustapha Pacha, Algiers, Algeria.
| | - Zahia Mallek
- Service d'otorhinolaryngologie, Centre Hospitalier Universitaire Bab El Oued, Algiers, Algeria.
| | - Christine Petit
- Syndrome de Usher et autres Atteintes Rétino-Cochléaires, Institut de la vision, 75012, Paris, France. .,UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France. .,Sorbonne Universités, UPMC Université Paris 06, Complexité du Vivant, Paris, 75252 Cedex 05, France. .,Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015, Paris, France. .,Collège de France, 75005, Paris, France.
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Shen J, Scheffer DI, Kwan KY, Corey DP. SHIELD: an integrative gene expression database for inner ear research. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2015. [PMID: 26209310 PMCID: PMC4513695 DOI: 10.1093/database/bav071] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The inner ear is a highly specialized mechanosensitive organ responsible for hearing and balance. Its small size and difficulty in harvesting sufficient tissue has hindered the progress of molecular studies. The protein components of mechanotransduction, the molecular biology of inner ear development and the genetic causes of many hereditary hearing and balance disorders remain largely unknown. Inner-ear gene expression data will help illuminate each of these areas. For over a decade, our laboratories and others have generated extensive sets of gene expression data for different cell types in the inner ear using various sample preparation methods and high-throughput genome-wide approaches. To facilitate the study of genes in the inner ear by efficient presentation of the accumulated data and to foster collaboration among investigators, we have developed the Shared Harvard Inner Ear Laboratory Database (SHIELD), an integrated resource that seeks to compile, organize and analyse the genomic, transcriptomic and proteomic knowledge of the inner ear. Five datasets are currently available. These datasets are combined in a relational database that integrates experimental data and annotations relevant to the inner ear. The SHIELD has a searchable web interface with two data retrieval options: viewing the gene pages online or downloading individual datasets as data tables. Each retrieved gene page shows the gene expression data and detailed gene information with hyperlinks to other online databases with up-to-date annotations. Downloadable data tables, for more convenient offline data analysis, are derived from publications and are current as of the time of publication. The SHIELD has made published and some unpublished data freely available to the public with the hope and expectation of accelerating discovery in the molecular biology of balance, hearing and deafness. Database URL:https://shield.hms.harvard.edu
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Affiliation(s)
- Jun Shen
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School Center for Hereditary Deafness,
| | | | - Kelvin Y Kwan
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA and
| | - David P Corey
- Harvard Medical School Center for Hereditary Deafness, Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
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73
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Worman HJ, Schirmer EC. Nuclear membrane diversity: underlying tissue-specific pathologies in disease? Curr Opin Cell Biol 2015; 34:101-12. [PMID: 26115475 PMCID: PMC4522394 DOI: 10.1016/j.ceb.2015.06.003] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 06/05/2015] [Accepted: 06/10/2015] [Indexed: 11/16/2022]
Abstract
Human 'laminopathy' diseases result from mutations in genes encoding nuclear lamins or nuclear envelope (NE) transmembrane proteins (NETs). These diseases present a seeming paradox: the mutated proteins are widely expressed yet pathology is limited to specific tissues. New findings suggest tissue-specific pathologies arise because these widely expressed proteins act in various complexes that include tissue-specific components. Diverse mechanisms to achieve NE tissue-specificity include tissue-specific regulation of the expression, mRNA splicing, signaling, NE-localization and interactions of potentially hundreds of tissue-specific NETs. New findings suggest these NETs underlie tissue-specific NE roles in cytoskeletal mechanics, cell-cycle regulation, signaling, gene expression and genome organization. This view of the NE as 'specialized' in each cell type is important to understand the tissue-specific pathology of NE-linked diseases.
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Affiliation(s)
- Howard J Worman
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, USA; Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, USA
| | - Eric C Schirmer
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, UK.
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74
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Wang JY, Yu IS, Huang CC, Chen CY, Wang WP, Lin SW, Jeang KT, Chi YH. Sun1 deficiency leads to cerebellar ataxia in mice. Dis Model Mech 2015; 8:957-67. [PMID: 26035387 PMCID: PMC4527285 DOI: 10.1242/dmm.019240] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 04/23/2015] [Indexed: 01/22/2023] Open
Abstract
Migration and organization of the nucleus are essential for the proliferation and differentiation of cells, including neurons. However, the relationship between the positioning of the nucleus and cellular morphogenesis remains poorly understood. Inherited recessive cerebellar ataxia has been attributed to mutations in SYNE1, a component of the linker of nucleoskeleton and cytoskeleton (LINC) complex. Regardless, Syne1-mutant mice present with normal cerebellar development. The Sad1-Unc-84 homology (SUN)-domain proteins are located at the inner nuclear membrane and recruit Syne proteins through the KASH domain to the outer nuclear membrane. Here, we report an unrecognized contribution of Sun1 and Sun2 to the postnatal development of murine cerebellum. Mice depleted of Sun1 showed a marked reduction in the cerebellar volume, and this phenotype is exacerbated with additional loss of a Sun2 allele. Consistent with these histological changes, Sun1(-/-) and Sun1(-/-)Sun2(+/-) mice exhibited defective motor coordination. Results of immunohistochemical analyses suggested that Sun1 is highly expressed in Purkinje cells and recruits Syne2 to the periphery of the nucleus. Approximately 33% of Purkinje cells in Sun1(-/-) mice and 66% of Purkinje cells in Sun1(-/-)Sun2(+/-) mice were absent from the surface of the internal granule layer (IGL), whereas the proliferation and migration of granule neurons were unaffected. Furthermore, the Sun1(-/-)Sun2(+/-) Purkinje cells exhibited retarded primary dendrite specification, reduced dendritic complexity and aberrant patterning of synapses. Our findings reveal a cell-type-specific role for Sun1 and Sun2 in nucleokinesis during cerebellar development, and we propose the use of Sun-deficient mice as a model for studying cerebellar ataxia that is associated with mutation of human SYNE genes or loss of Purkinje cells.
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Affiliation(s)
- Jing-Ya Wang
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan, Miaoli County 35053, Taiwan
| | - I-Shing Yu
- Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University Hospital, Taipei 10048, Taiwan Center of Genomic Medicine, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei 10048, Taiwan
| | - Chien-Chi Huang
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County 35053, Taiwan
| | - Chia-Yen Chen
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wan-Ping Wang
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan, Miaoli County 35053, Taiwan
| | - Shu-Wha Lin
- Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University Hospital, Taipei 10048, Taiwan Center of Genomic Medicine, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei 10048, Taiwan Department of Laboratory Medicine, National Taiwan University Hospital, Taipei 10048, Taiwan
| | - Kuan-Teh Jeang
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ya-Hui Chi
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan, Miaoli County 35053, Taiwan Graduate Institute of Basic Medical Science, China Medical University, Taichung 40402, Taiwan
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Abstract
Next-generation sequencing (NGS) technologies have played a central role in the genetic revolution. These technologies, especially whole-exome sequencing, have become the primary tool of geneticists to identify the causative DNA variants in Mendelian disorders, including hereditary deafness. Current research estimates that 1% of all human genes have a function in hearing. To date, mutations in over 80 genes have been reported to cause nonsyndromic hearing loss (NSHL). Strikingly, more than a quarter of all known genes related to NSHL were discovered in the past 5 years via NGS technologies. In this article, we review recent developments in the usage of NGS for hereditary deafness, with an emphasis on whole-exome sequencing.
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76
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Suzuki S, Ishikawa M, Ueda T, Ohshiba Y, Miyasaka Y, Okumura K, Yokohama M, Taya C, Matsuoka K, Kikkawa Y. Quantitative trait loci on chromosome 5 for susceptibility to frequency-specific effects on hearing in DBA/2J mice. Exp Anim 2015; 64:241-51. [PMID: 25765874 PMCID: PMC4547997 DOI: 10.1538/expanim.14-0110] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The DBA/2J strain is a model for early-onset, progressive hearing loss in humans, as
confirmed in the present study. DBA/2J mice showed progression of hearing loss to
low-frequency sounds from ultrasonic-frequency sounds and profound hearing loss at all
frequencies before 7 months of age. It is known that the early-onset hearing loss of
DBA/2J mice is caused by affects in the ahl
(Cdh23ahl) and ahl8
(Fscn2ahl8) alleles of the cadherin 23 and fascin 2 genes,
respectively. Although the strong contributions of the
Fscn2ahl8 allele were detected in hearing loss at 8- and
16-kHz stimuli with LOD scores of 5.02 at 8 kHz and 8.84 at 16 kHz, hearing loss effects
were also demonstrated for three new quantitative trait loci (QTLs) for the intervals of
50.3–54.5, 64.6–119.9, and 119.9–137.0 Mb, respectively, on chromosome 5, with significant
LOD scores of 2.80–3.91 for specific high-frequency hearing loss at 16 kHz by quantitative
trait loci linkage mapping using a (DBA/2J × C57BL/6J) F1 × DBA/2J backcross
mice. Moreover, we showed that the contribution of Fscn2ahl8
to early-onset hearing loss with 32-kHz stimuli is extremely low and raised the
possibility of effects from the Cdh23ahl allele and another
dominant quantitative trait locus (loci) for hearing loss at this ultrasonic frequency.
Therefore, our results suggested that frequency-specific QTLs control early-onset hearing
loss in DBA/2J mice.
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Affiliation(s)
- Sari Suzuki
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
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Chang W, Worman HJ, Gundersen GG. Accessorizing and anchoring the LINC complex for multifunctionality. ACTA ACUST UNITED AC 2015; 208:11-22. [PMID: 25559183 PMCID: PMC4284225 DOI: 10.1083/jcb.201409047] [Citation(s) in RCA: 210] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The linker of nucleoskeleton and cytoskeleton (LINC) complex, composed of outer and inner nuclear membrane Klarsicht, ANC-1, and Syne homology (KASH) and Sad1 and UNC-84 (SUN) proteins, respectively, connects the nucleus to cytoskeletal filaments and performs diverse functions including nuclear positioning, mechanotransduction, and meiotic chromosome movements. Recent studies have shed light on the source of this diversity by identifying factors associated with the complex that endow specific functions as well as those that differentially anchor the complex within the nucleus. Additional diversity may be provided by accessory factors that reorganize the complex into higher-ordered arrays. As core components of the LINC complex are associated with several diseases, understanding the role of accessory and anchoring proteins could provide insights into pathogenic mechanisms.
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Affiliation(s)
- Wakam Chang
- Department of Pathology and Cell Biology and Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Howard J Worman
- Department of Pathology and Cell Biology and Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032 Department of Pathology and Cell Biology and Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Gregg G Gundersen
- Department of Pathology and Cell Biology and Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032
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78
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Wilson MH, Holzbaur ELF. Nesprins anchor kinesin-1 motors to the nucleus to drive nuclear distribution in muscle cells. Development 2015; 142:218-28. [PMID: 25516977 DOI: 10.1242/dev.114769] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During skeletal muscle development, nuclei move dynamically through myotubes in a microtubule-dependent manner, driven by the microtubule motor protein kinesin-1. Loss of kinesin-1 leads to improperly positioned nuclei in culture and in vivo. Two models have been proposed to explain how kinesin-1 functions to move nuclei in myotubes. In the cargo model, kinesin-1 acts directly from the surface of the nucleus, whereas in an alternative model, kinesin-1 moves nuclei indirectly by sliding anti-parallel microtubules. Here, we test the hypothesis that an ensemble of Kif5B motors acts from the nuclear envelope to distribute nuclei throughout the length of syncytial myotubes. First, using an inducible dimerization system, we show that controlled recruitment of truncated, constitutively active kinesin-1 motors to the nuclear envelope is sufficient to prevent the nuclear aggregation resulting from depletion of endogenous kinesin-1. Second, we identify a conserved kinesin light chain (KLC)-binding motif in the nuclear envelope proteins nesprin-1 and nesprin-2, and show that recruitment of the motor complex to the nucleus via this LEWD motif is essential for nuclear distribution. Together, our findings demonstrate that the nucleus is a kinesin-1 cargo in myotubes and that nesprins function as nuclear cargo adaptors. The importance of achieving and maintaining proper nuclear position is not restricted to muscle fibers, suggesting that the nesprin-dependent recruitment of kinesin-1 to the nuclear envelope through the interaction of a conserved LEWD motif with kinesin light chain might be a general mechanism for cell-type-specific nuclear positioning during development.
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Affiliation(s)
- Meredith H Wilson
- Department of Physiology and the Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology and the Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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79
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Abstract
Mutations in genes encoding nuclear envelope proteins cause a wide range of inherited diseases, many of which are neurological. We review the genetic causes and what little is known about pathogenesis of these nuclear envelopathies that primarily affect striated muscle, peripheral nerve and the central nervous system. We conclude by providing examples of experimental therapeutic approaches to these rare but important neuromuscular diseases.
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Affiliation(s)
- Howard J. Worman
- />Department of Medicine and Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032 USA
| | - William T. Dauer
- />Department of Neurology and Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109 USA
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80
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Rajgor D, Mellad JA, Soong D, Rattner JB, Fritzler MJ, Shanahan CM. Mammalian microtubule P-body dynamics are mediated by nesprin-1. ACTA ACUST UNITED AC 2014; 205:457-75. [PMID: 24862572 PMCID: PMC4033771 DOI: 10.1083/jcb.201306076] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Nesprins are a multi-isomeric family of spectrin-repeat (SR) proteins, predominantly known as nuclear envelope scaffolds. However, isoforms that function beyond the nuclear envelope remain poorly examined. Here, we characterize p50(Nesp1), a 50-kD isoform that localizes to processing bodies (PBs), where it acts as a microtubule-associated protein capable of linking mRNP complexes to microtubules. Overexpression of dominant-negative p50(Nesp1) caused Rck/p54, but not GW182, displacement from microtubules, resulting in reduced PB movement and cross talk with stress granules (SGs). These cells disassembled canonical SGs induced by sodium arsenite, but not those induced by hydrogen peroxide, leading to cell death and revealing PB-microtubule attachment is required for hydrogen peroxide-induced SG anti-apoptotic functions. Furthermore, p50(Nesp1) was required for miRNA-mediated silencing and interacted with core miRISC silencers Ago2 and Rck/p54 in an RNA-dependent manner and with GW182 in a microtubule-dependent manner. These data identify p50(Nesp1) as a multi-functional PB component and microtubule scaffold necessary for RNA granule dynamics and provides evidence for PB and SG micro-heterogeneity.
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Affiliation(s)
- Dipen Rajgor
- Cardiovascular Division, BHF Centre of Excellence, James Black Centre, King's College London, London SE5 9NU, England, UK
| | - Jason A Mellad
- Cardiovascular Division, BHF Centre of Excellence, James Black Centre, King's College London, London SE5 9NU, England, UK
| | - Daniel Soong
- Cardiovascular Division, BHF Centre of Excellence, James Black Centre, King's College London, London SE5 9NU, England, UK
| | - Jerome B Rattner
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary T2N 4N1, Alberta, Canada
| | - Marvin J Fritzler
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary T2N 4N1, Alberta, Canada
| | - Catherine M Shanahan
- Cardiovascular Division, BHF Centre of Excellence, James Black Centre, King's College London, London SE5 9NU, England, UK
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81
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Abstract
The nucleus is the defining feature of eukaryotic cells and often represents the largest organelle. Over the past decade, it has become apparent that the nucleus is tightly integrated into the structural network of the cell through so-called LINC (linker of the nucleoskeleton and cytoskeleton) complexes, which enable transmission of forces between the nucleus and cytoskeleton. This physical connection between the nucleus and the cytoskeleton is essential for a broad range of cellular functions, including intracellular nuclear movement and positioning, cytoskeletal organization, cell polarization, and cell migration. Recent reports further indicate that forces transmitted from the extracellular matrix to the nucleus via the cytoskeleton may also directly contribute to the cell's ability to probe its mechanical environment by triggering force-induced changes in nuclear structures. In addition, it is now emerging that the physical properties of the nucleus play a crucial role during cell migration in three-dimensional (3D) environments, where cells often have to transit through narrow constrictions that are smaller than the nuclear diameter, e.g., during development, wound healing, or cancer metastasis. In this review, we provide a brief overview of how LINC complex proteins and lamins facilitate nucleo-cytoskeletal coupling, highlight recent findings regarding the role of the nucleus in cellular mechanotransduction and cell motility in 3D environments, and discuss how mutations and/or changes in the expression of these nuclear envelope proteins can result in a broad range of human diseases, including muscular dystrophy, dilated cardiomyopathy, and premature aging.
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82
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Imtiaz A, Kohrman DC, Naz S. A frameshift mutation in GRXCR2 causes recessively inherited hearing loss. Hum Mutat 2014; 35:618-24. [PMID: 24619944 DOI: 10.1002/humu.22545] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 03/04/2014] [Indexed: 01/06/2023]
Abstract
More than 360 million humans are affected with some degree of hearing loss, either early or later in life. A genetic cause for the disorder is present in a majority of the cases. We mapped a locus (DFNB101) for hearing loss in humans to chromosome 5q in a consanguineous Pakistani family. Exome sequencing revealed an insertion mutation in GRXCR2 as the cause of moderate-to-severe and likely progressive hearing loss in the affected individuals of the family. The frameshift mutation is predicted to affect a conserved, cysteine-rich region of GRXCR2, and to result in an abnormal extension of the C-terminus. Functional studies by cell transfections demonstrated that the mutant protein is unstable and mislocalized relative to wild-type GRXCR2, consistent with a loss-of-function mutation. Targeted disruption of Grxcr2 is concurrently reported to cause hearing loss in mice. The structural abnormalities in this animal model suggest a role for GRXCR2 in the development of stereocilia bundles, specialized structures on the apical surface of sensory cells in the cochlea that are critical for sound detection. Our results indicate that GRXCR2 should be considered in differential genetic diagnosis for individuals with early onset, moderate-to-severe and progressive hearing loss.
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Affiliation(s)
- Ayesha Imtiaz
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
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83
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Luxton GWG, Starr DA. KASHing up with the nucleus: novel functional roles of KASH proteins at the cytoplasmic surface of the nucleus. Curr Opin Cell Biol 2014; 28:69-75. [PMID: 24704701 DOI: 10.1016/j.ceb.2014.03.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 03/05/2014] [Accepted: 03/08/2014] [Indexed: 10/25/2022]
Abstract
Nuclear-cytoskeletal connections are central to fundamental cellular processes, including nuclear positioning and chromosome movements in meiosis. The cytoskeleton is coupled to the nucleoskeleton through conserved KASH-SUN bridges, or LINC complexes, that span the nuclear envelope. KASH proteins localize to the outer nuclear membrane where they connect the nucleus to the cytoskeleton. New findings have expanded the functional diversity of KASH proteins, showing that they interact with microtubule motors, actin, intermediate filaments, a nonconventional myosin, RanGAP, and each other. The role of KASH proteins in cellular mechanics is discussed. Genetic mutations in KASH proteins are associated with autism, hearing loss, cancer, muscular dystrophy and other diseases.
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Affiliation(s)
- G W Gant Luxton
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, United States.
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, United States.
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84
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Stroud MJ, Banerjee I, Veevers J, Chen J. Linker of nucleoskeleton and cytoskeleton complex proteins in cardiac structure, function, and disease. Circ Res 2014; 114:538-48. [PMID: 24481844 DOI: 10.1161/circresaha.114.301236] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The linker of nucleoskeleton and cytoskeleton (LINC) complex, composed of proteins within the inner and the outer nuclear membranes, connects the nuclear lamina to the cytoskeleton. The importance of this complex has been highlighted by the discovery of mutations in genes encoding LINC complex proteins, which cause skeletal or cardiac myopathies. Herein, this review summarizes structure, function, and interactions of major components of the LINC complex, highlights how mutations in these proteins may lead to cardiac disease, and outlines future challenges in the field.
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Affiliation(s)
- Matthew J Stroud
- From the Department of Cardiology, University of California San Diego School of Medicine, La Jolla, CA
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85
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Banerjee I, Zhang J, Moore-Morris T, Pfeiffer E, Buchholz KS, Liu A, Ouyang K, Stroud MJ, Gerace L, Evans SM, McCulloch A, Chen J. Targeted ablation of nesprin 1 and nesprin 2 from murine myocardium results in cardiomyopathy, altered nuclear morphology and inhibition of the biomechanical gene response. PLoS Genet 2014; 10:e1004114. [PMID: 24586179 PMCID: PMC3930490 DOI: 10.1371/journal.pgen.1004114] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 11/27/2013] [Indexed: 11/17/2022] Open
Abstract
Recent interest has focused on the importance of the nucleus and associated nucleoskeleton in regulating changes in cardiac gene expression in response to biomechanical load. Mutations in genes encoding proteins of the inner nuclear membrane and nucleoskeleton, which cause cardiomyopathy, also disrupt expression of a biomechanically responsive gene program. Furthermore, mutations in the outer nuclear membrane protein Nesprin 1 and 2 have been implicated in cardiomyopathy. Here, we identify for the first time a role for the outer nuclear membrane proteins, Nesprin 1 and Nesprin 2, in regulating gene expression in response to biomechanical load. Ablation of both Nesprin 1 and 2 in cardiomyocytes, but neither alone, resulted in early onset cardiomyopathy. Mutant cardiomyocytes exhibited altered nuclear positioning, shape, and chromatin positioning. Loss of Nesprin 1 or 2, or both, led to impairment of gene expression changes in response to biomechanical stimuli. These data suggest a model whereby biomechanical signals are communicated from proteins of the outer nuclear membrane, to the inner nuclear membrane and nucleoskeleton, to result in changes in gene expression required for adaptation of the cardiomyocyte to changes in biomechanical load, and give insights into etiologies underlying cardiomyopathy consequent to mutations in Nesprin 1 and 2.
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Affiliation(s)
- Indroneal Banerjee
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America
| | - Jianlin Zhang
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America
| | - Thomas Moore-Morris
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, La Jolla, California, United States of America
| | - Emily Pfeiffer
- Department of Bioengineering, University of California-San Diego, La Jolla, California, United States of America
| | - Kyle S Buchholz
- Department of Bioengineering, University of California-San Diego, La Jolla, California, United States of America
| | - Ao Liu
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America
| | - Kunfu Ouyang
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America ; Drug Discovery Center, Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Matthew J Stroud
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America
| | - Larry Gerace
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Sylvia M Evans
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, La Jolla, California, United States of America
| | - Andrew McCulloch
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America ; Department of Bioengineering, University of California-San Diego, La Jolla, California, United States of America
| | - Ju Chen
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America
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86
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Stewart CL, Burke B. The missing LINC: a mammalian KASH-domain protein coupling meiotic chromosomes to the cytoskeleton. Nucleus 2014; 5:3-10. [PMID: 24637401 DOI: 10.4161/nucl.27819] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Pairing of homologous chromosome is a unique event in meiosis that is essential for both haploidization of the genome and genetic recombination. Rapid chromosome movements during meiotic prophase are a key feature of the pairing process. This is usually telomere-led, and in metazoans is dependent upon microtubules and dynein. Chromosome movements culminate in the formation of a meiotic "bouquet" in which nuclear envelope-associated telomeres are clustered at the centrosomal pole of the nucleus. Bouquet formation is thought to facilitate homolog pairing. Recent studies reveal that coupling of telomeres to cytoplasmic dynein is mediated by SUN1 in the inner nuclear membrane (INM) and KASH5 a novel protein of the outer nuclear membrane (ONM). Together SUN1 and KASH5 assemble to form a transluminal LINC (linker of the nucleoskeleton and cytoskeleton) complex that spans both nuclear membranes. SUN1 forms attachment sites for telomeres at the INM while KASH5 functions as a dynein adaptor at the ONM. In mice deficient in KASH5, homologous chromosome pairing does not occur. The result is that meiosis is arrested at the leptotene/zygotene stage of meiotic prophase 1, and as a consequence both male and female mice are infertile. This study demonstrates an essential role for dynein directed telomere movement during meiotic prophase.
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Affiliation(s)
| | - Brian Burke
- Institute of Medical Biology; Immunos; Singapore
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87
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Connecting the nucleus to the cytoskeleton for nuclear positioning and cell migration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 773:505-20. [PMID: 24563363 DOI: 10.1007/978-1-4899-8032-8_23] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The position of the nucleus in the cytoplasm is a highly regulated process and is required for multiple cellular and developmental processes. Defects on different nuclear positioning events are associated with several pathologies such as muscle and nervous system disorders. In this chapter we describe the current knowledge on the mechanism of nuclear positioning. We discuss how the nucleus connects to the cytoskeleton by nesprins and SUN proteins, how this connection is regulated by Samp1, and how this connection is required for proper nuclear positioning. Furthermore, we discuss how nesprins, SUN, and Samp1 form transmembrane actin-associated nuclear (TAN) lines, novel nuclear envelope structures involved in force transduction during nuclear movement. Finally, we describe the recent evidences suggesting a role for the connection between the nucleus and the cytoskeleton in cancer.
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88
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Razafsky D, Wirtz D, Hodzic D. Nuclear envelope in nuclear positioning and cell migration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 773:471-90. [PMID: 24563361 PMCID: PMC4310828 DOI: 10.1007/978-1-4899-8032-8_21] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Hauling and anchoring the nucleus within immobile or motile cells, tissues, and/or syncytia represents a major challenge. In the past 15 years, Linkers of the Nucleoskeleton to the Cytoskeleton (LINC complexes) have emerged as evolutionary-conserved molecular devices that span the nuclear envelope and provide interacting interfaces for cytoskeletal networks and molecular motors to the nuclear envelope. Here, we review the molecular composition of LINC complexes and focus on how their genetic alteration in vivo has provided a wealth of information related to the relevance of nuclear positioning during tissue development and homeostasis with a special emphasis on the central nervous system. As it may be relevant for metastasis in a range of cancers, the involvement of LINC complexes in migration of nonneuronal cells via its interaction with the perinuclear actin cap will also be developed.
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Affiliation(s)
- David Razafsky
- Washington University School of Medicine, Department of Ophthalmology and Visual Sciences, 660 South Euclid Ave, St Louis, MO, 63110, USA
| | - Denis Wirtz
- The Johns Hopkins University, Department of Chemical and Biomolecular engineering, 3400 North Charles St., Baltimore, MD, 21218, USA
| | - Didier Hodzic
- Washington University School of Medicine, Department of Ophthalmology and Visual Sciences, 660 South Euclid Ave, St Louis, MO, 63110, USA
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89
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Alam S, Lovett DB, Dickinson RB, Roux KJ, Lele TP. Nuclear forces and cell mechanosensing. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 126:205-15. [PMID: 25081619 DOI: 10.1016/b978-0-12-394624-9.00008-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cells respond to mechanical signals, but the subcellular mechanisms are not well understood. The nucleus has recently emerged as an important mechanosensory organelle in the cell, as it is intimately connected to the cytoskeleton. Mechanical forces applied to cells that act on membrane-embedded receptors are transmitted through the cytoskeleton to the nuclear surface. Interfering with linkers of the nucleus to the cytoskeleton causes defects in cell mechanosensing and cell function. In this chapter, we discuss recent work in this area, highlighting the role that the nuclear linkages with the cytoskeleton play in cellular mechanotransduction.
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Affiliation(s)
- Samer Alam
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, USA
| | - David B Lovett
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, USA
| | - Richard B Dickinson
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, USA
| | - Kyle J Roux
- Sanford Children's Health Research Center, University of South Dakota, Sioux Falls, South Dakota, USA
| | - Tanmay P Lele
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, USA
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90
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Ferreira HC, Towbin BD, Jegou T, Gasser SM. The shelterin protein POT-1 anchors Caenorhabditis elegans telomeres through SUN-1 at the nuclear periphery. ACTA ACUST UNITED AC 2013; 203:727-35. [PMID: 24297748 PMCID: PMC3857485 DOI: 10.1083/jcb.201307181] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Telomere positioning near the nuclear envelope during Caenorhabditis elegans development requires the nuclear envelope protein SUN-1, the Shelterin component POT-1, and the SUMO ligase GEI-17. Telomeres are specialized protein–DNA structures that protect chromosome ends. In budding yeast, telomeres form clusters at the nuclear periphery. By imaging telomeres in embryos of the metazoan Caenorhabditis elegans, we found that telomeres clustered only in strains that had activated an alternative telomere maintenance pathway (ALT). Moreover, as in yeast, the unclustered telomeres in wild-type embryos were located near the nuclear envelope (NE). This bias for perinuclear localization increased during embryogenesis and persisted in differentiated cells. Telomere position in early embryos required the NE protein SUN-1, the single-strand binding protein POT-1, and the small ubiquitin-like modifier (SUMO) ligase GEI-17. However, in postmitotic larval cells, none of these factors individually were required for telomere anchoring, which suggests that additional mechanisms anchor in late development. Importantly, targeted POT-1 was sufficient to anchor chromatin to the NE in a SUN-1–dependent manner, arguing that its effect at telomeres is direct. This high-resolution description of telomere position within C. elegans extends our understanding of telomere organization in eukaryotes.
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Affiliation(s)
- Helder C Ferreira
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
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91
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Novel myosin mutations for hereditary hearing loss revealed by targeted genomic capture and massively parallel sequencing. Eur J Hum Genet 2013; 22:768-75. [PMID: 24105371 DOI: 10.1038/ejhg.2013.232] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Revised: 08/15/2013] [Accepted: 08/29/2013] [Indexed: 11/08/2022] Open
Abstract
Hereditary hearing loss is genetically heterogeneous, with a large number of genes and mutations contributing to this sensory, often monogenic, disease. This number, as well as large size, precludes comprehensive genetic diagnosis of all known deafness genes. A combination of targeted genomic capture and massively parallel sequencing (MPS), also referred to as next-generation sequencing, was applied to determine the deafness-causing genes in hearing-impaired individuals from Israeli Jewish and Palestinian Arab families. Among the mutations detected, we identified nine novel mutations in the genes encoding myosin VI, myosin VIIA and myosin XVA, doubling the number of myosin mutations in the Middle East. Myosin VI mutations were identified in this population for the first time. Modeling of the mutations provided predicted mechanisms for the damage they inflict in the molecular motors, leading to impaired function and thus deafness. The myosin mutations span all regions of these molecular motors, leading to a wide range of hearing phenotypes, reinforcing the key role of this family of proteins in auditory function. This study demonstrates that multiple mutations responsible for hearing loss can be identified in a relatively straightforward manner by targeted-gene MPS technology and concludes that this is the optimal genetic diagnostic approach for identification of mutations responsible for hearing loss.
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92
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Horn HF, Kim DI, Wright GD, Wong ESM, Stewart CL, Burke B, Roux KJ. A mammalian KASH domain protein coupling meiotic chromosomes to the cytoskeleton. ACTA ACUST UNITED AC 2013; 202:1023-39. [PMID: 24062341 PMCID: PMC3787381 DOI: 10.1083/jcb.201304004] [Citation(s) in RCA: 167] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A complex of KASH5 and Sun1 is required for meiotic homologous chromosome pairing through the coupling of telomere attachment sites to cytoplasmic dynein and microtubules. Chromosome pairing is an essential meiotic event that ensures faithful haploidization and recombination of the genome. Pairing of homologous chromosomes is facilitated by telomere-led chromosome movements and formation of a meiotic bouquet, where telomeres cluster to one pole of the nucleus. In metazoans, telomere clustering is dynein and microtubule dependent and requires Sun1, an inner nuclear membrane protein. Here we provide a functional analysis of KASH5, a mammalian dynein-binding protein of the outer nuclear membrane that forms a meiotic complex with Sun1. This protein is related to zebrafish futile cycle (Fue), a nuclear envelope (NE) constituent required for pronuclear migration. Mice deficient in this Fue homologue are infertile. Males display meiotic arrest in which pairing of homologous chromosomes fails. These findings demonstrate that telomere attachment to the NE is insufficient to promote pairing and that telomere attachment sites must be coupled to cytoplasmic dynein and the microtubule system to ensure meiotic progression.
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Affiliation(s)
- Henning F Horn
- Laborotory of Nuclear Dynamics and Architecture, 2 Laboratory of Developmental and Regenerative Biology, and 3 IMB Microscopy Unit, Institute of Medical Biology, 8A Biomedical Grove, Immunos, Singapore 138648
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93
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Abstract
Nuclear envelope
spectrin-repeat
proteins (Nesprins), are a novel family of
nuclear and cytoskeletal proteins with rapidly expanding roles as intracellular scaffolds
and linkers. Originally described as proteins that localise to the nuclear envelope (NE)
and establish nuclear-cytoskeletal connections, nesprins have now been found to comprise a
diverse spectrum of tissue specific isoforms that localise to multiple sub-cellular
compartments. Here, we describe how nesprins are necessary in maintaining cellular
architecture by acting as essential scaffolds and linkers at both the NE and other
sub-cellular domains. More importantly, we speculate how nesprin mutations may disrupt
tissue specific nesprin scaffolds and explain the tissue specific nature of many
nesprin-associated diseases, including laminopathies.
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94
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Ketema M, Kreft M, Secades P, Janssen H, Sonnenberg A. Nesprin-3 connects plectin and vimentin to the nuclear envelope of Sertoli cells but is not required for Sertoli cell function in spermatogenesis. Mol Biol Cell 2013; 24:2454-66. [PMID: 23761073 PMCID: PMC3727937 DOI: 10.1091/mbc.e13-02-0100] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Nesprin-3 regulates perinuclear localization of plectin and vimentin in Sertoli cells but is dispensable for Sertoli cell function in spermatogenesis. In addition, nuclear positioning and anchorage are not disturbed in nesprin-3–knockout mice. Nesprin-3 is a nuclear envelope protein that connects the nucleus to intermediate filaments by interacting with plectin. To investigate the role of nesprin-3 in the perinuclear localization of plectin, we generated nesprin-3–knockout mice and examined the effects of nesprin-3 deficiency in different cell types and tissues. Nesprin-3 and plectin are coexpressed in a variety of tissues, including peripheral nerve and muscle. The expression level of nesprin-3 in skeletal muscle is very low and decreases during myoblast differentiation in vitro. Of interest, plectin was concentrated at the nuclear envelope in only a few cell types. This was most prominent in Sertoli cells of the testis, in which nesprin-3 is required for the localization of both plectin and vimentin at the nuclear perimeter. Testicular morphology and the position of the nucleus in Sertoli cells were normal, however, in the nesprin-3–knockout mice and the mice were fertile. Furthermore, nesprin-3 was not required for the polarization and migration of mouse embryonic fibroblasts. Thus, although nesprin-3 is critical for the localization of plectin to the nuclear perimeter of Sertoli cells, the resulting link between the nuclear envelope and the intermediate filament system seems to be dispensable for normal testicular morphology and spermatogenesis.
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Affiliation(s)
- Mirjam Ketema
- Division of Cell Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
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95
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Rothballer A, Kutay U. The diverse functional LINCs of the nuclear envelope to the cytoskeleton and chromatin. Chromosoma 2013; 122:415-29. [PMID: 23736899 PMCID: PMC3777164 DOI: 10.1007/s00412-013-0417-x] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 05/14/2013] [Accepted: 05/15/2013] [Indexed: 11/30/2022]
Abstract
The nuclear envelope (NE) is connected to the different types of cytoskeletal elements by linker of nucleoskeleton and cytoskeleton (LINC) complexes. LINC complexes exist from yeast to humans, and have preserved their general architecture throughout evolution. They are composed of SUN and KASH domain proteins of the inner and the outer nuclear membrane, respectively. These SUN–KASH bridges are used for the transmission of forces across the NE and support diverse biological processes. Here, we review the function of SUN and KASH domain proteins in various unicellular and multicellular species. Specifically, we discuss their influence on nuclear morphology and cytoskeletal organization. Further, emphasis is given on the role of LINC complexes in nuclear anchorage and migration as well as in genome organization.
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Affiliation(s)
- Andrea Rothballer
- Department of Biology, Institute of Biochemistry, ETH Zurich, Schafmattstrasse 18, 8093 Zurich, Switzerland
| | - Ulrike Kutay
- Department of Biology, Institute of Biochemistry, ETH Zurich, Schafmattstrasse 18, 8093 Zurich, Switzerland
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96
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Parzefall T, Shivatzki S, Lenz DR, Rathkolb B, Ushakov K, Karfunkel D, Shapira Y, Wolf M, Mohr M, Wolf E, Sabrautzki S, de Angelis MH, Frydman M, Brownstein Z, Avraham KB. Cytoplasmic mislocalization of POU3F4 due to novel mutations leads to deafness in humans and mice. Hum Mutat 2013; 34:1102-10. [PMID: 23606368 DOI: 10.1002/humu.22339] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 04/08/2013] [Indexed: 11/12/2022]
Abstract
POU3F4 is a POU domain transcription factor that is required for hearing. In the ear, POU3F4 is essential for mesenchymal remodeling of the bony labyrinth and is the causative gene for DFNX2 human nonsyndromic deafness. Ear abnormalities underlie this form of deafness, characterized previously in multiple spontaneous, radiation-induced and transgenic mouse mutants. Here, we report three novel mutations in the POU3F4 gene that result in profound hearing loss in both humans and mice. A p.Gln79* mutation was identified in a child from an Israeli family, revealed by massively parallel sequencing (MPS). This strategy demonstrates the strength of MPS for diagnosis with only one affected individual. A second mutation, p.Ile285Argfs*43, was identified by Sanger sequencing. A p.Cys300* mutation was found in an ENU-induced mutant mouse, schwindel (sdl), by positional cloning. The mutation leads to a predicted truncated protein, similar to the human mutations, providing a relevant mouse model. The p.Ile285Argfs*43 and p.Cys300* mutations lead to a shift of Pou3f4 nuclear localization to the cytoplasm, demonstrated in cellular localization studies and in the inner ears of the mutant mice. The discovery of these mutations facilitates a deeper comprehension of the molecular basis of inner ear defects due to mutations in the POU3F4 transcription factor.
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Affiliation(s)
- Thomas Parzefall
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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97
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Abstract
The nucleus is the largest organelle and is commonly depicted in the center of the cell. Yet during cell division, migration, and differentiation, it frequently moves to an asymmetric position aligned with cell function. We consider the toolbox of proteins that move and anchor the nucleus within the cell and how forces generated by the cytoskeleton are coupled to the nucleus to move it. The significance of proper nuclear positioning is underscored by numerous diseases resulting from genetic alterations in the toolbox proteins. Finally, we discuss how nuclear position may influence cellular organization and signaling pathways.
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Affiliation(s)
- Gregg G Gundersen
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
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98
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Structural insights into LINC complexes. Curr Opin Struct Biol 2013; 23:285-91. [PMID: 23597672 DOI: 10.1016/j.sbi.2013.03.005] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 02/21/2013] [Accepted: 03/23/2013] [Indexed: 11/21/2022]
Abstract
Communication between nucleus and cytoplasm extends past molecular exchange and critically includes mechanical wiring. Cytoskeleton and nucleoskeleton are connected via molecular tethers that span the nuclear envelope. Sad1, UNC84 (SUN)-domain proteins spanning the inner nuclear membrane and Klarsicht, ANC-1 and SYNE/Nesprin-1 and -2 Homology (KASH)-peptide bearing proteins residing in the outer nuclear membrane directly bind and constitute the core of the LInkers of Nucleoskeleton and Cytoskeleton (LINC) complex. These connections appear critical for a growing number of biological processes and aberrations are implicated in a host of diverse diseases, including muscular dystrophies, cardiomyopathies, and premature aging. We discuss recent developments in this vibrant research area, particularly in context of first structural insights into LINC complexes reported in the past year.
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99
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Abstract
The linker of nucleoskeleton and cytoskeleton (LINC) complex connects the nuclear lamina to the cytoskeleton, in part to aid in nuclear positioning. Mutations in genes encoding LINC complex and lamina components cause a range of human diseases. In this issue of the JCI, Horn et al. report that mutations in the gene SYNE4 encoding the LINC complex protein nesprin-4 lead to progressive high-frequency hearing loss. Further, in mice deficient in nesprin-4 and Sun1, another LINC complex component, outer hair cells of the cochlea form normally during development, but die in the early postnatal weeks. These results link improper nuclear positioning specifically to the death of outer hair cells in the organ of Corti and ultimately to deafness.
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Affiliation(s)
- Howard J Worman
- Department of Medicine, College of Physician and Surgeons, Columbia University, 630 West 168th Street, New York, New York 10032, USA.
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