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Kracklauer MP, Wiora HM, Deery WJ, Chen X, Bolival B, Romanowicz D, Simonette RA, Fuller MT, Fischer JA, Beckingham KM. The Drosophila SUN protein Spag4 cooperates with the coiled-coil protein Yuri Gagarin to maintain association of the basal body and spermatid nucleus. J Cell Sci 2010; 123:2763-72. [PMID: 20647369 PMCID: PMC2915878 DOI: 10.1242/jcs.066589] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2010] [Indexed: 11/20/2022] Open
Abstract
Maintaining the proximity of centrosomes to nuclei is important in several cellular contexts, and LINC complexes formed by SUN and KASH proteins are crucial in this process. Here, we characterize the presumed Drosophila ortholog of the mammalian SUN protein, sperm-associated antigen 4 (Spag4, previously named Giacomo), and demonstrate that Spag4 is required for centriole and nuclear attachment during spermatogenesis. Production of spag4 mRNA is limited to the testis, and Spag4 protein shows a dynamic pattern of association with the germline nuclei, including a concentration of protein at the site of attachment of the single spermatid centriole. In the absence of Spag4, nuclei and centrioles or basal bodies (BBs) dissociate from each other after meiosis. This role of Spag4 in centriolar attachment does not involve either of the two KASH proteins of the Drosophila genome (Klarsicht and MSP-300), but does require the coiled-coil protein Yuri Gagarin. Yuri shows an identical pattern of localization at the nuclear surface to Spag4 during spermatogenesis, and epistasis studies show that the activities of Yuri and dynein-dynactin are downstream of spag4 in this centriole attachment pathway. The later defects in spermatogenesis seen for yuri and spag4 mutants are similar, suggesting they could be secondary to initial disruption of events at the nuclear surface.
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Affiliation(s)
- Martin P. Kracklauer
- Institute for Cell and Molecular Biology and Section of Cell and Developmental Biology, The University of Texas at Austin, 1 University Station A4800, Austin, TX 78712, USA
- Department of Pediatrics, The University of Michigan Medical School, Ann Arbor, MI 48109-5652, USA
| | - Heather M. Wiora
- Institute for Cell and Molecular Biology and Section of Cell and Developmental Biology, The University of Texas at Austin, 1 University Station A4800, Austin, TX 78712, USA
| | - William J. Deery
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005, USA
| | - Xin Chen
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Benjamin Bolival
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Dwight Romanowicz
- Institute for Cell and Molecular Biology and Section of Cell and Developmental Biology, The University of Texas at Austin, 1 University Station A4800, Austin, TX 78712, USA
| | - Rebecca A. Simonette
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005, USA
| | - Margaret T. Fuller
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Janice A. Fischer
- Institute for Cell and Molecular Biology and Section of Cell and Developmental Biology, The University of Texas at Austin, 1 University Station A4800, Austin, TX 78712, USA
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102
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Göb E, Schmitt J, Benavente R, Alsheimer M. Mammalian sperm head formation involves different polarization of two novel LINC complexes. PLoS One 2010; 5:e12072. [PMID: 20711465 PMCID: PMC2919408 DOI: 10.1371/journal.pone.0012072] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Accepted: 07/14/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND LINC complexes are nuclear envelope bridging protein structures formed by interaction of SUN and KASH proteins. They physically connect the nucleus with the peripheral cytoskeleton and are critically involved in a variety of dynamic processes, such as nuclear anchorage, movement and positioning and meiotic chromosome dynamics. Moreover, they are shown to be essential for maintaining nuclear shape. FINDINGS Based on detailed expression analysis and biochemical approaches, we show here that during mouse sperm development, a terminal cell differentiation process characterized by profound morphogenic restructuring, two novel distinctive LINC complexes are established. They consist either of spermiogenesis-specific Sun3 and Nesprin1 or Sun1eta, a novel non-nuclear Sun1 isoform, and Nesprin3. We could find that these two LINC complexes specifically polarize to opposite spermatid poles likely linking to sperm-specific cytoskeletal structures. Although, as shown in co-transfection/immunoprecipitation experiments, SUN proteins appear to arbitrarily interact with various KASH partners, our study demonstrates that they actually are able to confine their binding to form distinct LINC complexes. CONCLUSIONS Formation of the mammalian sperm head involves assembly and different polarization of two novel spermiogenesis-specific LINC complexes. Together, our findings suggest that theses LINC complexes connect the differentiating spermatid nucleus to surrounding cytoskeletal structures to enable its well-directed shaping and elongation, which in turn is a critical parameter for male fertility.
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Affiliation(s)
- Eva Göb
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Johannes Schmitt
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Ricardo Benavente
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Manfred Alsheimer
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
- * E-mail:
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103
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Abstract
Cell migration is a fundamental process that is necessary for the development and survival of multicellular organisms. Here, we show that cell migration is contingent on global condensation of the chromatin fiber. Induction of directed cell migration by the scratch-wound assay leads to decreased DNaseI sensitivity, alterations in the chromatin binding of architectural proteins and elevated levels of H4K20me1, H3K27me3 and methylated DNA. All these global changes are indicative of increased chromatin condensation in response to induction of directed cell migration. Conversely, chromatin decondensation inhibited the rate of cell migration, in a transcription-independent manner. We suggest that global chromatin condensation facilitates nuclear movement and reshaping, which are important for cell migration. Our results support a role for the chromatin fiber that is distinct from its known functions in genetic processes.
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Affiliation(s)
- Gabi Gerlitz
- Protein Section, Laboratory of Metabolism, National Cancer Institute, US National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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104
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The nucleoporin Nup153 maintains nuclear envelope architecture and is required for cell migration in tumor cells. FEBS Lett 2010; 584:3013-20. [PMID: 20561986 DOI: 10.1016/j.febslet.2010.05.038] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 05/12/2010] [Accepted: 05/13/2010] [Indexed: 02/05/2023]
Abstract
Nucleoporin 153 (Nup153), a component of the nuclear pore complex (NPC), has been implicated in the interaction of the NPC with the nuclear lamina. Here we show that depletion of Nup153 by RNAi results in alteration of the organization of the nuclear lamina and the nuclear lamin-binding protein Sun1. More striking, Nup153 depletion induces a dramatic cytoskeletal rearrangement that impairs cell migration in human breast carcinoma cells. Our results point to a very prominent role of Nup153 in connection to cell motility that could be exploited in order to develop novel anti-cancer therapy.
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105
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Carvou N, Holic R, Li M, Futter C, Skippen A, Cockcroft S. Phosphatidylinositol- and phosphatidylcholine-transfer activity of PITPbeta is essential for COPI-mediated retrograde transport from the Golgi to the endoplasmic reticulum. J Cell Sci 2010; 123:1262-73. [PMID: 20332109 PMCID: PMC2848114 DOI: 10.1242/jcs.061986] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2010] [Indexed: 11/20/2022] Open
Abstract
Vesicles formed by the COPI complex function in retrograde transport from the Golgi to the endoplasmic reticulum (ER). Phosphatidylinositol transfer protein beta (PITPbeta), an essential protein that possesses phosphatidylinositol (PtdIns) and phosphatidylcholine (PtdCho) lipid transfer activity is known to localise to the Golgi and ER but its role in these membrane systems is not clear. To examine the function of PITPbeta at the Golgi-ER interface, RNA interference (RNAi) was used to knockdown PITPbeta protein expression in HeLa cells. Depletion of PITPbeta leads to a decrease in PtdIns(4)P levels, compaction of the Golgi complex and protection from brefeldin-A-mediated dispersal to the ER. Using specific transport assays, we show that anterograde traffic is unaffected but that KDEL-receptor-dependent retrograde traffic is inhibited. This phenotype can be rescued by expression of wild-type PITPbeta but not by mutants defective in docking, PtdIns transfer and PtdCho transfer. These data demonstrate that the PtdIns and PtdCho exchange activity of PITPbeta is essential for COPI-mediated retrograde transport from the Golgi to the ER.
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Affiliation(s)
- Nicolas Carvou
- Lipid Signalling Group, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St, London, WC1E 6BT, UK
| | - Roman Holic
- Lipid Signalling Group, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St, London, WC1E 6BT, UK
| | - Michelle Li
- Lipid Signalling Group, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St, London, WC1E 6BT, UK
| | - Clare Futter
- Department of Cell Biology, Institute of Ophthalmology, University College London, Gower St, London, WC1E 6BT, UK
| | - Alison Skippen
- Lipid Signalling Group, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St, London, WC1E 6BT, UK
| | - Shamshad Cockcroft
- Lipid Signalling Group, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St, London, WC1E 6BT, UK
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106
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Abstract
A- and B-type lamins are the major intermediate filaments of the nucleus. Lamins engage in a plethora of stable and transient interactions, near the inner nuclear membrane and throughout the nucleus. Lamin-binding proteins serve an amazingly diverse range of functions. Numerous inner-membrane proteins help anchor lamin filaments to the nuclear envelope, serving as part of the nuclear "lamina" network that is essential for nuclear architecture and integrity. Certain lamin-binding proteins of the inner membrane bind partners in the outer membrane and mechanically link lamins to the cytoskeleton. Inside the nucleus, lamin-binding proteins appear to serve as the "adaptors" by which the lamina organizes chromatin, influences gene expression and epigenetic regulation, and modulates signaling pathways. Transient interactions of lamins with key components of the transcription and replication machinery may provide an additional level of regulation or support to these essential events.
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Affiliation(s)
- Katherine L Wilson
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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107
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Abstract
The giant isoforms of nesprins 1 and 2 are emerging as important players in cellular organization, particularly in the positioning of nuclei, and possibly other organelles, within the cytoplasm. The experimental evidence suggests that nesprins also occur at the inner nuclear membrane, where they interact with the nuclear lamina. In this paper, we consider whether this is consistent with current ideas about nesprin anchorage and about mechanisms for nuclear import of membrane proteins.
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108
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Tung SM, Ünal C, Ley A, Peña C, Tunggal B, Noegel AA, Krut O, Steinert M, Eichinger L. Loss of Dictyostelium ATG9 results in a pleiotropic phenotype affecting growth, development, phagocytosis and clearance and replication of Legionella pneumophila. Cell Microbiol 2010; 12:765-80. [DOI: 10.1111/j.1462-5822.2010.01432.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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109
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Warren DT, Tajsic T, Mellad JA, Searles R, Zhang Q, Shanahan CM. Novel nuclear nesprin-2 variants tether active extracellular signal-regulated MAPK1 and MAPK2 at promyelocytic leukemia protein nuclear bodies and act to regulate smooth muscle cell proliferation. J Biol Chem 2010; 285:1311-20. [PMID: 19861416 PMCID: PMC2801258 DOI: 10.1074/jbc.m109.032557] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 10/05/2009] [Indexed: 11/06/2022] Open
Abstract
Nuclear and cytoplasmic scaffold proteins have been shown to be essential for temporal and spatial organization, as well as the fidelity, of MAPK signaling pathways. In this study we show that nesprin-2 is a novel extracellular signal-regulated MAPK1 and 2 (ERK1/2) scaffold protein that serves to regulate nuclear signaling by tethering these kinases at promyelocytic leukemia protein nuclear bodies (PML NBs). Using immunofluorescence microscopy, GST pull-down and immunoprecipitation, we show that nesprin-2, ERK1/2, and PML colocalize and bind to form a nuclear complex. Interference of nesprin-2 function, by either siRNA-mediated knockdown or overexpression of a dominant negative nesprin-2 fragment, augmented ERK1/2 nuclear signaling shown by increased SP1 activity and ELK1 phosphorylation. The functional outcome of nesprin-2 disruption and the resultant sustained ERK1/2 signal was increased proliferation. Importantly, these activities were not induced by previously identified nuclear envelope (NE)-targeted nesprin-2 isoforms but rather were mediated by novel nuclear isoforms that lacked the KASH domain. Taken together, this study suggests that nesprin-2 is a novel intranuclear scaffold, essential for nuclear ERK1/2 signaling fidelity and cell cycle progression.
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Affiliation(s)
- Derek T Warren
- British Heart Foundation Centre, Division of Cardiovascular Medicine, King's College London, London SE5 9NU, United Kingdom.
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110
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Méjat A, Misteli T. LINC complexes in health and disease. Nucleus 2010; 1:40-52. [PMID: 21327104 PMCID: PMC3035119 DOI: 10.4161/nucl.1.1.10530] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 11/04/2009] [Accepted: 11/05/2009] [Indexed: 11/19/2022] Open
Abstract
The cell nucleus communicates with the rest of the cell via nucleo/cytoplasmic transport of proteins and RNA through the nuclear pores. Direct mechanical links between the nucleus and the cytoplasm have recently emerged in the form of LINC (Linkers of the nucleoskeleton to the cytoskeleton) protein complexes. A LINC complex consists of four components. At its core are an inner nuclear membrane (INM) transmembrane protein and an outer nuclear membrane (ONM) transmembrane protein which physically interact with each other in the lumen of the NE. The INM LINC component interacts on the nucleoplasmic side with either the lamina or with an INM-associated protein. The ONM LINC component on the other hand contacts on the cytoplasmatic side a component of the cytoskeleton. This review highlights the components of LINC complexes and their emerging roles in mechanotransduction, nuclear migration, chromosome positioning, signaling, meiosis, cytoskeletal organization and human disease.
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Affiliation(s)
- Alexandre Méjat
- National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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111
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Dauer WT, Worman HJ. The nuclear envelope as a signaling node in development and disease. Dev Cell 2009; 17:626-38. [PMID: 19922868 DOI: 10.1016/j.devcel.2009.10.016] [Citation(s) in RCA: 185] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The development of a membrane-bound structure separating DNA from other cellular components was the epochal evolutionary event that gave rise to eukaryotes, possibly occurring up to 2 billion years ago. Yet, this view of the nuclear envelope as a physical barrier greatly underestimates its fundamental impact on cellular organization and complexity, much of which is only beginning to be understood. Indeed, alterations of nuclear envelope structure and protein composition are essential to many aspects of metazoan development and cellular differentiation. Mutations in genes encoding nuclear envelope proteins cause a fascinating array of diseases referred to as "nuclear envelopathies" or "laminopathies" that affect different tissues and organ systems. We review recent work on the nuclear envelope, including insights derived from the study of nuclear envelopathies. These studies are uncovering new functions for nuclear envelope proteins and underlie an emerging view of the nuclear envelope as a critical signaling node in development and disease.
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Affiliation(s)
- William T Dauer
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI 48109 USA.
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112
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SUN1/2 and Syne/Nesprin-1/2 complexes connect centrosome to the nucleus during neurogenesis and neuronal migration in mice. Neuron 2009; 64:173-87. [PMID: 19874786 PMCID: PMC2788510 DOI: 10.1016/j.neuron.2009.08.018] [Citation(s) in RCA: 378] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Revised: 08/19/2009] [Accepted: 08/21/2009] [Indexed: 11/20/2022]
Abstract
Nuclear movement is critical during neurogenesis and neuronal migration, which are fundamental for mammalian brain development. Although dynein, Lis1, and other cytoplasmic proteins are known for their roles in connecting microtubules to the nucleus during interkinetic nuclear migration (INM) and nucleokinesis, the factors connecting dynein/Lis1 to the nuclear envelope (NE) remain to be determined. We report here that the SUN-domain proteins SUN1 and SUN2 and the KASH-domain proteins Syne-1/Nesprin-1 and Syne-2/Nesprin-2 play critical roles in neurogenesis and neuronal migration in mice. We show that SUN1 and SUN2 redundantly form complexes with Syne-2 to mediate the centrosome-nucleus coupling during both INM and radial neuronal migration in the cerebral cortex. Syne-2 is connected to the centrosome through interactions with both dynein/dynactin and kinesin complexes. Syne-2 mutants also display severe defects in learning and memory. These results fill an important gap in our understanding of the mechanism of nuclear movement during brain development.
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113
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Zhang J, Felder A, Liu Y, Guo LT, Lange S, Dalton ND, Gu Y, Peterson KL, Mizisin AP, Shelton GD, Lieber RL, Chen J. Nesprin 1 is critical for nuclear positioning and anchorage. Hum Mol Genet 2009; 19:329-41. [PMID: 19864491 DOI: 10.1093/hmg/ddp499] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Nesprin 1 is an outer nuclear membrane protein that is thought to link the nucleus to the actin cytoskeleton. Recent data suggest that mutations in Nesprin 1 may also be involved in the pathogenesis of Emery-Dreifuss muscular dystrophy. To investigate the function of Nesprin 1 in vivo, we generated a mouse model in which all isoforms of Nesprin 1 containing the C-terminal spectrin-repeat region with or without KASH domain were ablated. Nesprin 1 knockout mice are marked by decreased survival rates, growth retardation and increased variability in body weight. Additionally, nuclear positioning and anchorage are dysfunctional in skeletal muscle from knockout mice. Physiological testing demonstrated no significant reduction in stress production in Nesprin 1-deficient skeletal muscle in either neonatal or adult mice, but a significantly lower exercise capacity in knockout mice. Nuclear deformation testing revealed ineffective strain transmission to nuclei in muscle fibers lacking Nesprin 1. Overall, our data show that Nesprin 1 is essential for normal positioning and anchorage of nuclei in skeletal muscle.
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Affiliation(s)
- Jianlin Zhang
- Department of Medicine, University of California San Diego, La Jolla, CA 92093-0613, USA
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114
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Ostlund C, Folker ES, Choi JC, Gomes ER, Gundersen GG, Worman HJ. Dynamics and molecular interactions of linker of nucleoskeleton and cytoskeleton (LINC) complex proteins. J Cell Sci 2009; 122:4099-108. [PMID: 19843581 DOI: 10.1242/jcs.057075] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The linker of nucleoskeleton and cytoskeleton (LINC) complex is situated in the nuclear envelope and forms a connection between the lamina and cytoskeletal elements. Sun1, Sun2 and nesprin-2 are important components of the LINC complex. We expressed these proteins fused to green fluorescent protein in embryonic fibroblasts and studied their diffusional mobilities using fluorescence recovery after photobleaching. We show that they all are more mobile in embryonic fibroblasts from mice lacking A-type lamins than in cells from wild-type mice. Knockdown of Sun2 also increased the mobility of a short, chimeric form of nesprin-2 giant (mini-nesprin-2G), whereas the lack of emerin did not affect the mobility of Sun1, Sun2 or mini-nesprin-2G. Fluorescence resonance energy transfer experiments showed Sun1 to be more closely associated with lamin A than is Sun2. Sun1 and Sun2 had similar affinity for the nesprin-2 KASH domain in plasmon surface resonance (Biacore) experiments. This affinity was ten times higher than that previously reported between nesprin-2 and actin. Deletion of the actin-binding domain had no effect on mini-nesprin-2G mobility. Our data support a model in which A-type lamins and Sun2 anchor nesprin-2 in the outer nuclear membrane, whereas emerin, Sun1 and actin are dispensable for this anchoring.
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Affiliation(s)
- Cecilia Ostlund
- Department of Medicine, Columbia University, New York, NY 10032, USA
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115
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Blau-Wasser R, Euteneuer U, Xiong H, Gassen B, Schleicher M, Noegel AA. CP250, a novel acidic coiled-coil protein of the Dictyostelium centrosome, affects growth, chemotaxis, and the nuclear envelope. Mol Biol Cell 2009; 20:4348-61. [PMID: 19692569 DOI: 10.1091/mbc.e09-03-0180] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Dictyostelium centrosome is a nucleus associated body consisting of a box-shaped core surrounded by the corona, an amorphous matrix functionally equivalent to the pericentriolar material of animal centrosomes which is responsible for the nucleation and anchoring of microtubules. Here we describe CP250 a component of the corona, an acidic coiled coil protein that is present at the centrosome throughout interphase while disappearing during prophase and reappearing at the end of late telophase. Amino acids 756-1148 of the 2110 amino acids are sufficient for centrosomal targeting and cell cycle-dependent centrosome association. Mutant cells lacking CP250 are smaller in size, growth on bacteria is delayed, chemotaxis is altered, and development is affected, which, in general, are defects observed in cytoskeletal mutants. Furthermore, loss of CP250 affected the nuclear envelope and led to reduced amounts and altered distribution of Sun-1, a conserved nuclear envelope protein that connects the centrosome to chromatin.
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Affiliation(s)
- Rosemarie Blau-Wasser
- Center for Biochemistry, Medical Faculty, University of Cologne, 50931 Köln, Germany
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116
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Razafsky D, Hodzic D. Bringing KASH under the SUN: the many faces of nucleo-cytoskeletal connections. ACTA ACUST UNITED AC 2009; 186:461-72. [PMID: 19687252 PMCID: PMC2733748 DOI: 10.1083/jcb.200906068] [Citation(s) in RCA: 197] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nucleus is the most prominent cellular organelle, and its sharp boundaries suggest the compartmentalization of the nucleoplasm from the cytoplasm. However, the recent identification of evolutionarily conserved linkers of the nucleoskeleton to the cytoskeleton (LINC) complexes, a family of macromolecular assemblies that span the double membrane of the nuclear envelope, reveals tight physical connections between the two compartments. Here, we review the structure and evolutionary conservation of SUN and KASH domain–containing proteins, whose interaction within the perinuclear space forms the “nuts and bolts” of LINC complexes. Moreover, we discuss the function of these complexes in nuclear, centrosomal, and chromosome dynamics, and their connection to human disease.
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Affiliation(s)
- David Razafsky
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
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117
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Dawe HR, Adams M, Wheway G, Szymanska K, Logan CV, Noegel AA, Gull K, Johnson CA. Nesprin-2 interacts with meckelin and mediates ciliogenesis via remodelling of the actin cytoskeleton. J Cell Sci 2009; 122:2716-26. [PMID: 19596800 DOI: 10.1242/jcs.043794] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Meckel-Gruber syndrome (MKS) is a severe autosomal recessively inherited disorder caused by mutations in genes that encode components of the primary cilium and basal body. Here we show that two MKS proteins, MKS1 and meckelin, that are required for centrosome migration and ciliogenesis interact with actin-binding isoforms of nesprin-2 (nuclear envelope spectrin repeat protein 2, also known as Syne-2 and NUANCE). Nesprins are important scaffold proteins for maintenance of the actin cytoskeleton, nuclear positioning and nuclear-envelope architecture. However, in ciliated-cell models, meckelin and nesprin-2 isoforms colocalized at filopodia prior to the establishment of cell polarity and ciliogenesis. Loss of nesprin-2 and nesprin-1 shows that both mediate centrosome migration and are then essential for ciliogenesis, but do not otherwise affect apical-basal polarity. Loss of meckelin (by siRNA and in a patient cell-line) caused a dramatic remodelling of the actin cytoskeleton, aberrant localization of nesprin-2 isoforms to actin stress-fibres and activation of RhoA signalling. These findings further highlight the important roles of the nesprins during cellular and developmental processes, particularly in general organelle positioning, and suggest that a mechanistic link between centrosome positioning, cell polarity and the actin cytoskeleton is required for centrosomal migration and is essential for early ciliogenesis.
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Affiliation(s)
- Helen R Dawe
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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118
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SUN1 and SUN2 play critical but partially redundant roles in anchoring nuclei in skeletal muscle cells in mice. Proc Natl Acad Sci U S A 2009; 106:10207-12. [PMID: 19509342 DOI: 10.1073/pnas.0812037106] [Citation(s) in RCA: 197] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
How the nuclei in mammalian skeletal muscle fibers properly position themselves relative to the cell body is an interesting and important cell biology question. In the syncytial skeletal muscle cells, more than 100 nuclei are evenly distributed at the periphery of each cell, with 3-8 nuclei anchored beneath the neuromuscular junction (NMJ). Our previous studies revealed that the KASH domain-containing Syne-1/Nesprin-1 protein plays an essential role in anchoring both synaptic and nonsynaptic myonuclei in mice. SUN domain-containing proteins (SUN proteins) have been shown to interact with KASH domain-containing proteins (KASH proteins) at the nuclear envelope (NE), but their roles in nuclear positioning in mice are unknown. Here we show that the synaptic nuclear anchorage is partially perturbed in Sun1, but not in Sun2, knockout mice. Disruption of 3 or all 4 Sun1/2 wild-type alleles revealed a gene dosage effect on synaptic nuclear anchorage. The organization of nonsynaptic nuclei is disrupted in Sun1/2 double-knockout (DKO) mice as well. We further show that the localization of Syne-1 to the NE of muscle cells is disrupted in Sun1/2 DKO mice. These results clearly indicate that SUN1 and SUN2 function critically in skeletal muscle cells for Syne-1 localization at the NE, which is essential for proper myonuclear positioning.
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119
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Fridkin A, Penkner A, Jantsch V, Gruenbaum Y. SUN-domain and KASH-domain proteins during development, meiosis and disease. Cell Mol Life Sci 2009; 66:1518-33. [PMID: 19125221 PMCID: PMC6485414 DOI: 10.1007/s00018-008-8713-y] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
SUN-domain proteins interact directly with KASH-domain proteins to form protein complexes that connect the nucleus to every major cytoskeleton network. SUN-KASH protein complexes are also required for attaching centrosomes to the nuclear periphery and for alignment of homologous chromosomes, their pairing and recombination in meiosis. Other functions that require SUN-domain proteins include the regulation of apoptosis and maturation and survival of the germline. Laminopathic diseases affect the distribution of the SUN-KASH complexes, and mutations in KASH-domain proteins can cause Emery Dreifuss muscular dystrophy and recessive cerebellar ataxia. This review describes our current knowledge of the role of SUN-KASH domain protein complexes during development, meiosis and disease.
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Affiliation(s)
- A. Fridkin
- Department of Genetics, Hebrew University of Jerusalem, Jerusalem, 91904 Israel
| | - A. Penkner
- Department of Chromosome Biology, Max F. Perutz Laboratories University of Vienna, A-1030 Vienna, Austria
| | - V. Jantsch
- Department of Chromosome Biology, Max F. Perutz Laboratories University of Vienna, A-1030 Vienna, Austria
| | - Y. Gruenbaum
- Department of Genetics, Hebrew University of Jerusalem, Jerusalem, 91904 Israel
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Olins AL, Hoang TV, Zwerger M, Herrmann H, Zentgraf H, Noegel AA, Karakesisoglou I, Hodzic D, Olins DE. The LINC-less granulocyte nucleus. Eur J Cell Biol 2009; 88:203-14. [PMID: 19019491 PMCID: PMC2671807 DOI: 10.1016/j.ejcb.2008.10.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Revised: 10/03/2008] [Accepted: 10/06/2008] [Indexed: 01/18/2023] Open
Abstract
The major blood granulocyte (neutrophil) is rapidly recruited to sites of bacterial and fungal infections. It is a highly malleable cell, allowing it to squeeze out of blood vessels and migrate through tight tissue spaces. The human granulocyte nucleus is lobulated and exhibits a paucity of nuclear lamins, increasing its capability for deformation. The present study examined the existence of protein connections between the nuclear envelope and cytoskeletal elements (the LINC complex) in differentiated cell states (i.e. granulocytic, monocytic and macrophage) of the human leukemic cell line HL-60, as well as in human blood leukocytes. HL-60 granulocytes exhibited a deficiency of several LINC complex proteins (i.e. nesprin 1 giant, nesprin 2 giant, SUN1, plectin and vimentin); whereas, the macrophage state revealed nesprin 1 giant, plectin and vimentin. Both states possessed SUN2 in the nuclear envelope. Parallel differences were observed with some of the LINC complex proteins in isolated human blood leukocytes, including macrophage cells derived from blood monocytes. The present study documenting the paucity of LINC complex proteins in granulocytic forms, in combination with previous data on granulocyte nuclear shape and nuclear envelope composition, suggest the hypothesis that these adaptations evolved to facilitate granulocyte cellular malleability.
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Affiliation(s)
- Ada L Olins
- Department of Biology, Bowdoin College, Brunswick, ME 04011, USA.
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121
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KASH-domain proteins and the cytoskeletal landscapes of the nuclear envelope. Biochem Soc Trans 2009; 36:1368-72. [PMID: 19021557 DOI: 10.1042/bst0361368] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Over the last few years, several novel proteins have been identified that facilitate the physical integration of the nucleus with the cytoplasmic compartment. The majority belong to the evolutionarily conserved KASH [klarsicht/ANC-1 (anchorage 1)/SYNE (synaptic nuclear envelope protein) homology]-domain family, which function primarily as exclusive outer nuclear membrane scaffolds that associate with the cytoskeleton, the centrosome and the motor protein apparatus. In the present paper, we propose a novel model, which may explain why these proteins also determine nuclear architecture. Moreover, we discuss further nuclear membrane-tethering devices, which indicate collectively the presence of specific molecular mechanisms that organize the cytoplasmic-nuclear membrane interface in mammalian cells.
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122
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Lu W, Gotzmann J, Sironi L, Jaeger VM, Schneider M, Lüke Y, Uhlén M, Szigyarto CAK, Brachner A, Ellenberg J, Foisner R, Noegel AA, Karakesisoglou I. Sun1 forms immobile macromolecular assemblies at the nuclear envelope. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2415-26. [DOI: 10.1016/j.bbamcr.2008.09.001] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 09/03/2008] [Accepted: 09/05/2008] [Indexed: 10/25/2022]
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