The Experts below are selected from a list of 1104 Experts worldwide ranked by ideXlab platform
Angelika A. Noegel - One of the best experts on this subject based on the ideXlab platform.
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Nesprin-1 impact on tumorigenic cell phenotypes
Molecular Biology Reports, 2020Co-Authors: Ilknur Sur-erdem, Muhammed Sajid Hussain, Maria Asif, Nareg Pınarbası, Ali Cenk Aksu, Angelika A. NoegelAbstract:The largest protein of the nuclear envelope (NE) is Nesprin-1 which forms a network along the NE interacting with actin, Emerin, Lamin, and SUN proteins. Mutations in the SYNE1 gene and reduction in Nesprin-1 protein levels have been reported to correlate with several age related diseases and cancer. In the present study, we tested whether Nesprin-1 overexpression can reverse the malignant phenotype of Huh7 cells, a human liver cancer cell line, which carries a mutation in the SYNE1 gene resulting in reduced Nesprin-1 protein levels, has altered nuclear shape, altered amounts and localization of NE components, centrosome localization and genome stability. Ectopic expression of a mini-Nesprin-1 led to an improvement of the nuclear shape, corrected the mislocalization of NE proteins, the centrosome positioning, and the alterations in the DNA damage response network. Additionally, Nesprin-1 had a profound effect on cellular senescence. These findings suggest that Nesprin-1 may be effective in tumorigenic cell phenotype correction of human liver cancer.
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Depletion of Nesprin-2 is associated with an embryonic lethal phenotype in mice
2018Co-Authors: Carmen Mroß, Martina Munck, Angelika A. Noegel, Ludwig Eichinger, Vivek S Peche, Gernot Glockner, Marija Marko, Susanne Motameny, Janine Altmüller, Sascha NeumannAbstract:Nesprin-2 is a nuclear envelope component and provides a link between cytoskeletal components of the cytoplasm and the nucleoplasm. Several isoforms are generated from its gene Syne2. Loss of the largest isoform Nesprin-2 Giant in mice is associated with a skin phenotype and altered wound healing, loss of C-terminal isoforms in mice leads to cardiomyopathies and neurological defects. Here we attempted to establish mice with an inducible knockout of all Nesprin-2 isoforms by inserting shRNA encoding sequences targeting the N- and C-terminus into the ROSA26 locus of mice. This caused early embryonic death of the animals harboring the mutant allele, which was presumably due to leaky expression of the shRNAs. Mutant embryos were only observed before E13. They had an altered appearance and were smaller in size than their wild type littermates. From this we conclude that the Nesprin-2 gene function is crucial during embryonic growth, differentiation and organogenesis.
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Nesprin-2 Interacts with Condensin Component SMC2.
International Journal of Cell Biology, 2017Co-Authors: Xin Xing, Carmen Mroß, Linlin Hao, Martina Munck, Alexandra Herzog, Clara Mohr, C. P. Unnikannan, Pranav Kelkar, Angelika A. Noegel, Ludwig EichingerAbstract:The nuclear envelope proteins, Nesprins, have been primarily studied during interphase where they function in maintaining nuclear shape, size, and positioning. We analyze here the function of Nesprin-2 in chromatin interactions in interphase and dividing cells. We characterize a region in the rod domain of Nesprin-2 that is predicted as SMC domain (aa 1436-1766). We show that this domain can interact with itself. It furthermore has the capacity to bind to SMC2 and SMC4, the core subunits of condensin. The interaction was observed during all phases of the cell cycle; it was particularly strong during S phase and persisted also during mitosis. Nesprin-2 knockdown did not affect condensin distribution; however we noticed significantly higher numbers of chromatin bridges in Nesprin-2 knockdown cells in anaphase. Thus, Nesprin-2 may have an impact on chromosomes which might be due to its interaction with condensins or to indirect mechanisms provided by its interactions at the nuclear envelope.
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Nesprin 2 mediated nuclear trafficking and its clinical implications
Nucleus, 2015Co-Authors: Pranav Kelkar, Martina Munck, Anna Walter, Symeon Papadopoulos, Carmen Mros, Vivek S Peche, Angelika A. NoegelAbstract:Nuclear translocation of proteins has a crucial role in the pathogenesis of cancer, Alzheimer disease and viral infections. A complete understanding of nuclear trafficking mechanisms is therefore necessary in order to establish effective intervention strategies. Here we elucidate the role of Nesprin-2 in Ca(2+)/Calmodulin mediated nuclear transport. Nesprin-2 is an actin-binding nuclear envelope (NE) protein with roles in maintaining nuclear structure and location, regulation of transcription and mechanotransduction. Upon depletion of Nesprin-2 using shRNA, HaCaT cells show abnormal localization of the shuttling proteins BRCA1 and NF-κB. We show that their nuclear transport is unlikely due to the canonical RAN mediated nuclear import, but rather to a RAN independent Ca(2+)/Calmodulin driven mechanism involving Nesprin-2. We report novel interactions between the actin-binding domain of Nesprin-2 and Calmodulin and between the NLS containing region of BRCA1 and Calmodulin. Strikingly, displacing Nesprins from the NE resulted in increased steady state Ca(2+) concentrations in the cytoplasm suggesting a previously unidentified role of Nesprins in Ca(2+) regulation. On comparing Nesprin-2 and BRCA1 localization in the ovarian cancer cell lines SKOV-3 and Caov-3, Nesprin-2 and BRCA1 were localized to the NE envelope and the nucleus in SKOV-3, respectively, and to the cytoplasm in Caov-3 cells. Fibroblasts obtained from EDMD5 (Emery Dreifuss muscular dystrophy) patients showed loss of Nesprin-2 from the nuclear envelope, corresponding reduced nuclear localization of BRCA1 and enhanced cytoplasmic Ca(2+). Taken together, the data suggests a novel role of Nesprin-2 in Ca(2+)/Calmodulin mediated nuclear trafficking and provides new insights which can guide future therapies.
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Nesprin 1 role in dna damage response
Nucleus, 2014Co-Authors: Ilknur Sur, Sascha Neumann, Angelika A. NoegelAbstract:Nuclear envelope (NE) proteins have fundamental roles in maintaining nuclear structure, cell signaling, chromatin organization, and gene regulation, and mutations in genes encoding NE components were identified as primary cause of a number of age associated diseases and cancer. Nesprin-1 belongs to a family of multi-isomeric NE proteins that are characterized by spectrin repeats. We analyzed NE components in various tumor cell lines and found that Nesprin-1 levels were strongly reduced associated with alterations in further NE components. By reducing the amounts of Nesprin-1 by RNAi mediated knockdown, we could reproduce those alterations in mouse and human cell lines. In a search for novel Nesprin-1 binding proteins, we identified MSH2 and MSH6, proteins of the DNA damage response pathway, as interactors and found alterations in the corresponding pathways in cells with lower Nesprin-1 levels. We also noticed increased number of γH2AX foci in the absence of exogenous DNA damage as was seen in tumor cells. The levels of phosphorylated kinases Chk1 and 2 were altered in a manner resembling tumor cells and the levels of Ku70 were low and the protein was not recruited to the DNA after hydroxyurea (HU) treatment. Our findings indicate a role for Nesprin-1 in the DNA damage response pathway and propose Nesprin-1 as novel player in tumorigenesis and genome instability.
Catherine M Shanahan - One of the best experts on this subject based on the ideXlab platform.
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Nesprin 1 2 roles in nuclear envelope organisation myogenesis and muscle disease
Biochemical Society Transactions, 2018Co-Authors: Li Rao, Catherine M Shanahan, Can Zhou, Qiuping ZhangAbstract:Nesprins (nuclear envelope spectrin repeat proteins) are multi-isomeric scaffolding proteins. Nesprin-1 and -2 are highly expressed in skeletal and cardiac muscles and together with SUN (Sad1p/UNC84) domain-containing proteins form the LInker of Nucleoskeleton and Cytoskeleton (LINC) complex at the nuclear envelope in association with lamin A/C and emerin. Mutations in Nesprin-1/2 have been found in patients with autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD) as well as dilated cardiomyopathy (DCM). Several lines of evidence indicate that compromised LINC complex function is the critical step leading to muscle disease. Here, we review recent advances in our understanding of the functions of Nesprin-1/2 in the LINC complex and mechanistic insights into how mutations in Nesprin-1/2 lead to Nesprin-related muscle diseases, in particular DCM and EDMD.
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identification of novel Nesprin 1 binding partners and cytoplasmic matrin 3 in processing bodies
Molecular Biology of the Cell, 2016Co-Authors: Dipen Rajgor, Jonathan G Hanley, Catherine M ShanahanAbstract:Nesprins are highly conserved spectrin repeat-containing scaffold proteins predominantly known to function at the nuclear envelope (NE). However, Nesprin isoforms are emerging with localizations and scaffolding functions at sites away from the NE, suggesting their functions are more diverse than originally thought. In this study, we combined Nesprin-1 coimmunoprecipitations with mass spectrometry to identify novel Nesprin-1 binding partners for isoforms that localize to subcellular compartments beyond the NE. We show that one of these interactors, matrin-3 (matr3), localizes to mRNA processing bodies (PBs), where we have previously shown a Nesprin-1 isoform to localize. Furthermore, we show that Matr3 is part of PB mRNP complexes, is a regulator of miRNA-mediated gene silencing, and possibly shuttles to stress granules in stressed cells. More importantly, we identify a new C-terminally truncated Matr3 isoform that is likely to be involved in these functions and PB localization. This study highlights several novel Nesprin-1 binding partners and a new function and localization for Matr3 in cytoplasmic RNA granules.
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n terminal Nesprin 2 variants regulate β catenin signalling
Experimental Cell Research, 2016Co-Authors: Qiuping Zhang, Dipen Rajgor, Flavia Autore, Can Zhou, Rosemarie Minaisah, Elisa Ferraro, Lauren J Porter, Fang Gao, Junyi Zhang, Catherine M ShanahanAbstract:The spatial compartmentalisation of biochemical signalling pathways is essential for cell function. Nesprins are a multi-isomeric family of proteins that have emerged as signalling scaffolds, herein, we investigate the localisation and function of novel Nesprin-2 N-terminal variants. We show that these Nesprin-2 variants display cell specific distribution and reside in both the cytoplasm and nucleus. Immunofluorescence microscopy revealed that Nesprin-2 N-terminal variants colocalised with β-catenin at cell-cell junctions in U2OS cells. Calcium switch assays demonstrated that Nesprin-2 and β-catenin are lost from cell-cell junctions in low calcium conditions whereas emerin localisation at the NE remained unaltered, furthermore, an N-terminal fragment of Nesprin-2 was sufficient for cell-cell junction localisation and interacted with β-catenin. Disruption of these N-terminal Nesprin-2 variants, using siRNA depletion resulted in loss of β-catenin from cell-cell junctions, nuclear accumulation of active β-catenin and augmented β-catenin transcriptional activity. Importantly, we show that U2OS cells lack Nesprin-2 giant, suggesting that the N-terminal Nesprin-2 variants regulate β-catenin signalling independently of the NE. Together, these data identify N-terminal Nesprin-2 variants as novel regulators of β-catenin signalling that tether β-catenin to cell-cell contacts to inhibit β-catenin transcriptional activity.
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Specific localization of Nesprin-1-α2, the short isoform of Nesprin-1 with a KASH domain, in developing, fetal and regenerating muscle, using a new monoclonal antibody
BMC cell biology, 2016Co-Authors: Ian Holt, Qiuping Zhang, Catherine M Shanahan, Caroline Sewry, Kamel Mamchaoui, Nguyen Thuy Duong, Le Thanh Lam, Glenn E. MorrisAbstract:Nesprin-1-giant (1008kD) is a protein of the outer nuclear membrane that links nuclei to the actin cytoskeleton via amino-terminal calponin homology domains. The short Nesprin-1 isoform, Nesprin-1-α2, is present only in skeletal and cardiac muscle and several pathogenic mutations occur within it, but the functions of this short isoform without calponin homology domains are unclear. The aim of this study was to determine mRNA levels and protein localization of Nesprin-1-α2 at different stages of muscle development in order to shed light on its functions. mRNA levels of all known Nesprin-1 isoforms with a KASH domain were determined by quantitative PCR. The mRNA for the 111 kD muscle-specific short isoform, Nesprin-1-α2, was not detected in pre-differentiation human myoblasts but was present at significant levels in multinucleate myotubes. We developed a monoclonal antibody against the unique amino-terminal sequence of Nesprin-1-α2, enabling specific immunolocalization for the first time. Nesprin-1-α2 protein was undetectable in pre-differentiation myoblasts but appeared at the nuclear rim in post-mitotic, multinucleate myotubes and reached its highest levels in fetal muscle. In muscle from a Duchenne muscular dystrophy biopsy, Nesprin-1-α2 protein was detected mainly in regenerating fibres expressing neonatal myosin. Nesprin-1-giant was present at all developmental stages, but was also highest in fetal and regenerating fibres. In fetal muscle, both isoforms were present in the cytoplasm, as well as at the nuclear rim. A pathogenic early stop codon (E7854X) in Nesprin-1 caused reduced mRNA levels and loss of protein levels of both Nesprin-1-giant and (unexpectedly) Nesprin-1-α2, but did not affect myogenesis in vitro. Nesprin-1-α2 mRNA and protein expression is switched on during myogenesis, alongside other known markers of muscle differentiation. The results show that Nesprin-1-α2 is dynamically controlled and may be involved in some process occurring during early myofibre formation, such as re-positioning of nuclei.
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identification and validation of putative Nesprin variants
Springer US, 2016Co-Authors: Flavia Autore, Catherine M Shanahan, Qiuping ZhangAbstract:Nesprins are a family of multi-isomeric scaffolding proteins that were originally identified at the nuclear envelope (NE), where they bind to lamin A/C, emerin, and SUN-domain containing proteins, to form the LInker of Nucleoskeleton-and-Cytoskeleton (LINC) complex that connects the NE to the actin cytoskeleton. However, Nesprin genes also give rise to a variety of tissue-specific variants of different sizes with potential roles beyond the NE. These variants are generated through alternative initiation, termination, and splicing, which makes Nesprin biology very complex to study due to the difficulty in generating specific antibodies and/or short interfering RNAs (siRNA) to particular isoforms. In order to distinguish genuine Nesprin variants and eliminate confusion with degradation products of larger Nesprin isoforms, in this chapter we discuss methods including 5' and 3' Rapid Amplification of cDNA Ends (RACE) and RT-PCR in combination with EST database searching, for identifying and validating putative Nesprin isoforms. This information is essential to allow a better understanding of Nesprin functions in different cell types.
Qiuping Zhang - One of the best experts on this subject based on the ideXlab platform.
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Nesprin 1 2 roles in nuclear envelope organisation myogenesis and muscle disease
Biochemical Society Transactions, 2018Co-Authors: Li Rao, Catherine M Shanahan, Can Zhou, Qiuping ZhangAbstract:Nesprins (nuclear envelope spectrin repeat proteins) are multi-isomeric scaffolding proteins. Nesprin-1 and -2 are highly expressed in skeletal and cardiac muscles and together with SUN (Sad1p/UNC84) domain-containing proteins form the LInker of Nucleoskeleton and Cytoskeleton (LINC) complex at the nuclear envelope in association with lamin A/C and emerin. Mutations in Nesprin-1/2 have been found in patients with autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD) as well as dilated cardiomyopathy (DCM). Several lines of evidence indicate that compromised LINC complex function is the critical step leading to muscle disease. Here, we review recent advances in our understanding of the functions of Nesprin-1/2 in the LINC complex and mechanistic insights into how mutations in Nesprin-1/2 lead to Nesprin-related muscle diseases, in particular DCM and EDMD.
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n terminal Nesprin 2 variants regulate β catenin signalling
Experimental Cell Research, 2016Co-Authors: Qiuping Zhang, Dipen Rajgor, Flavia Autore, Can Zhou, Rosemarie Minaisah, Elisa Ferraro, Lauren J Porter, Fang Gao, Junyi Zhang, Catherine M ShanahanAbstract:The spatial compartmentalisation of biochemical signalling pathways is essential for cell function. Nesprins are a multi-isomeric family of proteins that have emerged as signalling scaffolds, herein, we investigate the localisation and function of novel Nesprin-2 N-terminal variants. We show that these Nesprin-2 variants display cell specific distribution and reside in both the cytoplasm and nucleus. Immunofluorescence microscopy revealed that Nesprin-2 N-terminal variants colocalised with β-catenin at cell-cell junctions in U2OS cells. Calcium switch assays demonstrated that Nesprin-2 and β-catenin are lost from cell-cell junctions in low calcium conditions whereas emerin localisation at the NE remained unaltered, furthermore, an N-terminal fragment of Nesprin-2 was sufficient for cell-cell junction localisation and interacted with β-catenin. Disruption of these N-terminal Nesprin-2 variants, using siRNA depletion resulted in loss of β-catenin from cell-cell junctions, nuclear accumulation of active β-catenin and augmented β-catenin transcriptional activity. Importantly, we show that U2OS cells lack Nesprin-2 giant, suggesting that the N-terminal Nesprin-2 variants regulate β-catenin signalling independently of the NE. Together, these data identify N-terminal Nesprin-2 variants as novel regulators of β-catenin signalling that tether β-catenin to cell-cell contacts to inhibit β-catenin transcriptional activity.
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Specific localization of Nesprin-1-α2, the short isoform of Nesprin-1 with a KASH domain, in developing, fetal and regenerating muscle, using a new monoclonal antibody
BMC cell biology, 2016Co-Authors: Ian Holt, Qiuping Zhang, Catherine M Shanahan, Caroline Sewry, Kamel Mamchaoui, Nguyen Thuy Duong, Le Thanh Lam, Glenn E. MorrisAbstract:Nesprin-1-giant (1008kD) is a protein of the outer nuclear membrane that links nuclei to the actin cytoskeleton via amino-terminal calponin homology domains. The short Nesprin-1 isoform, Nesprin-1-α2, is present only in skeletal and cardiac muscle and several pathogenic mutations occur within it, but the functions of this short isoform without calponin homology domains are unclear. The aim of this study was to determine mRNA levels and protein localization of Nesprin-1-α2 at different stages of muscle development in order to shed light on its functions. mRNA levels of all known Nesprin-1 isoforms with a KASH domain were determined by quantitative PCR. The mRNA for the 111 kD muscle-specific short isoform, Nesprin-1-α2, was not detected in pre-differentiation human myoblasts but was present at significant levels in multinucleate myotubes. We developed a monoclonal antibody against the unique amino-terminal sequence of Nesprin-1-α2, enabling specific immunolocalization for the first time. Nesprin-1-α2 protein was undetectable in pre-differentiation myoblasts but appeared at the nuclear rim in post-mitotic, multinucleate myotubes and reached its highest levels in fetal muscle. In muscle from a Duchenne muscular dystrophy biopsy, Nesprin-1-α2 protein was detected mainly in regenerating fibres expressing neonatal myosin. Nesprin-1-giant was present at all developmental stages, but was also highest in fetal and regenerating fibres. In fetal muscle, both isoforms were present in the cytoplasm, as well as at the nuclear rim. A pathogenic early stop codon (E7854X) in Nesprin-1 caused reduced mRNA levels and loss of protein levels of both Nesprin-1-giant and (unexpectedly) Nesprin-1-α2, but did not affect myogenesis in vitro. Nesprin-1-α2 mRNA and protein expression is switched on during myogenesis, alongside other known markers of muscle differentiation. The results show that Nesprin-1-α2 is dynamically controlled and may be involved in some process occurring during early myofibre formation, such as re-positioning of nuclei.
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identification and validation of putative Nesprin variants
Springer US, 2016Co-Authors: Flavia Autore, Catherine M Shanahan, Qiuping ZhangAbstract:Nesprins are a family of multi-isomeric scaffolding proteins that were originally identified at the nuclear envelope (NE), where they bind to lamin A/C, emerin, and SUN-domain containing proteins, to form the LInker of Nucleoskeleton-and-Cytoskeleton (LINC) complex that connects the NE to the actin cytoskeleton. However, Nesprin genes also give rise to a variety of tissue-specific variants of different sizes with potential roles beyond the NE. These variants are generated through alternative initiation, termination, and splicing, which makes Nesprin biology very complex to study due to the difficulty in generating specific antibodies and/or short interfering RNAs (siRNA) to particular isoforms. In order to distinguish genuine Nesprin variants and eliminate confusion with degradation products of larger Nesprin isoforms, in this chapter we discuss methods including 5' and 3' Rapid Amplification of cDNA Ends (RACE) and RT-PCR in combination with EST database searching, for identifying and validating putative Nesprin isoforms. This information is essential to allow a better understanding of Nesprin functions in different cell types.
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Nesprin 2 dependent erk1 2 compartmentalisation regulates the dna damage response in vascular smooth muscle cell ageing
Cell Death & Differentiation, 2015Co-Authors: Derek T Warren, Qiuping Zhang, Dipen Rajgor, Rosemarie Minaisah, Lauren J Porter, Tamara Tajsic, Andrew M Cobb, Anne P Jacob, Catherine M ShanahanAbstract:Prelamin A accumulation and persistent DNA damage response (DDR) are hallmarks of vascular smooth muscle cell (VSMC) ageing and dysfunction. Although prelamin A is proposed to interfere with DNA repair, our understanding of the crosstalk between prelamin A and the repair process remains limited. The extracellular signal-regulated kinases 1 and 2 (ERK1/2) have emerged as key players in the DDR and are known to enhance ataxia telangiectasia-mutated protein (ATM) activity at DNA lesions, and in this study, we identified a novel relationship between prelamin A accumulation and ERK1/2 nuclear compartmentalisation during VSMC ageing. We show both prelamin A accumulation and increased DNA damage occur concomitantly, before VSMC replicative senescence, and induce the localisation of ERK1/2 to promyelocytic leukaemia protein nuclear bodies (PML NBs) at the sites of DNA damage via Nesprin-2 and lamin A interactions. Importantly, VSMCs treated with DNA damaging agents also displayed prelamin A accumulation and ERK compartmentalisation at PML NBs, suggesting that prelamin A and Nesprin-2 are novel components of the DDR. In support of this, disruption of ERK compartmentalisation at PML NBs, by either depletion of Nesprin-2 or lamins A/C, resulted in the loss of ATM from DNA lesions. However, ATM signalling and DNA repair remained intact after lamins A/C depletion, whereas Nesprin-2 disruption ablated downstream Chk2 activation and induced genomic instability. We conclude that lamins A/C and PML act as scaffolds to organise DNA-repair foci and compartmentalise Nesprin-2/ERK signalling. However, Nesprin-2/ERK signalling fidelity, but not their compartmentalisation at PML NBs, is essential for efficient DDR in VSMCs.
Sascha Neumann - One of the best experts on this subject based on the ideXlab platform.
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Depletion of Nesprin-2 is associated with an embryonic lethal phenotype in mice
2018Co-Authors: Carmen Mroß, Martina Munck, Angelika A. Noegel, Ludwig Eichinger, Vivek S Peche, Gernot Glockner, Marija Marko, Susanne Motameny, Janine Altmüller, Sascha NeumannAbstract:Nesprin-2 is a nuclear envelope component and provides a link between cytoskeletal components of the cytoplasm and the nucleoplasm. Several isoforms are generated from its gene Syne2. Loss of the largest isoform Nesprin-2 Giant in mice is associated with a skin phenotype and altered wound healing, loss of C-terminal isoforms in mice leads to cardiomyopathies and neurological defects. Here we attempted to establish mice with an inducible knockout of all Nesprin-2 isoforms by inserting shRNA encoding sequences targeting the N- and C-terminus into the ROSA26 locus of mice. This caused early embryonic death of the animals harboring the mutant allele, which was presumably due to leaky expression of the shRNAs. Mutant embryos were only observed before E13. They had an altered appearance and were smaller in size than their wild type littermates. From this we conclude that the Nesprin-2 gene function is crucial during embryonic growth, differentiation and organogenesis.
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Nesprin 1 role in dna damage response
Nucleus, 2014Co-Authors: Ilknur Sur, Sascha Neumann, Angelika A. NoegelAbstract:Nuclear envelope (NE) proteins have fundamental roles in maintaining nuclear structure, cell signaling, chromatin organization, and gene regulation, and mutations in genes encoding NE components were identified as primary cause of a number of age associated diseases and cancer. Nesprin-1 belongs to a family of multi-isomeric NE proteins that are characterized by spectrin repeats. We analyzed NE components in various tumor cell lines and found that Nesprin-1 levels were strongly reduced associated with alterations in further NE components. By reducing the amounts of Nesprin-1 by RNAi mediated knockdown, we could reproduce those alterations in mouse and human cell lines. In a search for novel Nesprin-1 binding proteins, we identified MSH2 and MSH6, proteins of the DNA damage response pathway, as interactors and found alterations in the corresponding pathways in cells with lower Nesprin-1 levels. We also noticed increased number of γH2AX foci in the absence of exogenous DNA damage as was seen in tumor cells. The levels of phosphorylated kinases Chk1 and 2 were altered in a manner resembling tumor cells and the levels of Ku70 were low and the protein was not recruited to the DNA after hydroxyurea (HU) treatment. Our findings indicate a role for Nesprin-1 in the DNA damage response pathway and propose Nesprin-1 as novel player in tumorigenesis and genome instability.
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mutations in lmna modulate the lamin a Nesprin 2 interaction and cause linc complex alterations
PLOS ONE, 2013Co-Authors: Liu Yang, Martina Munck, Angelika A. Noegel, Karthic Swaminathan, Larisa E Kapinos, Sascha NeumannAbstract:In eukaryotes the genetic material is enclosed by a continuous membrane system, the nuclear envelope (NE). Along the NE specific proteins assemble to form meshworks and mutations in these proteins have been described in a group of human diseases called laminopathies. Laminopathies include lipodystrophies, muscle and cardiac diseases as well as metabolic or progeroid syndromes. Most laminopathies are caused by mutations in the LMNAgene encoding lamins A/C. Together with Nesprins (Nuclear Envelope Spectrin Repeat Proteins) they are core components of the LINC complex (Linker of Nucleoskeleton and Cytoskeleton). The LINC complex connects the nucleoskeleton and the cytoskeleton and plays a role in the transfer of mechanically induced signals along the NE into the nucleus, and its components have been attributed functions in maintaining nuclear and cellular organization as well as signal transduction.; Here we narrowed down the interaction sites between lamin A and Nesprin-2 to aa 403-425 in lamin A and aa 6146-6347 in Nesprin-2. Laminopathic mutations in and around the involved region of lamin A (R401C, G411D, G413C, V415I, R419C, L421P, R427G, Q432X) modulate the interaction with Nesprin-2 and this may contribute to the disease phenotype. The most notable mutation is the lamin A mutation Q432X that alters LINC complex protein assemblies and causes chromosomal and transcription factor rearrangements.; Mutations in Nesprin-2 and lamin A are characterised by complex genotype phenotype relations. Our data show that each mutation in LMNAanalysed here has a distinct impact on the interaction among both proteins that substantially explains how distinct mutations in widely expressed genes lead to the formation of phenotypically different diseases.
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Mutations in LMNA Modulate the Lamin A - Nesprin-2 Interaction and Cause LINC Complex Alterations
2013Co-Authors: Liu Yang, Martina Munck, Angelika A. Noegel, Karthic Swaminathan, Larisa E Kapinos, Sascha NeumannAbstract:BackgroundIn eukaryotes the genetic material is enclosed by a continuous membrane system, the nuclear envelope (NE). Along the NE specific proteins assemble to form meshworks and mutations in these proteins have been described in a group of human diseases called laminopathies. Laminopathies include lipodystrophies, muscle and cardiac diseases as well as metabolic or progeroid syndromes. Most laminopathies are caused by mutations in the LMNAgene encoding lamins A/C. Together with Nesprins (Nuclear Envelope Spectrin Repeat Proteins) they are core components of the LINC complex (Linker of Nucleoskeleton and Cytoskeleton). The LINC complex connects the nucleoskeleton and the cytoskeleton and plays a role in the transfer of mechanically induced signals along the NE into the nucleus, and its components have been attributed functions in maintaining nuclear and cellular organization as well as signal transduction.ResultsHere we narrowed down the interaction sites between lamin A and Nesprin-2 to aa 403–425 in lamin A and aa 6146–6347 in Nesprin-2. Laminopathic mutations in and around the involved region of lamin A (R401C, G411D, G413C, V415I, R419C, L421P, R427G, Q432X) modulate the interaction with Nesprin-2 and this may contribute to the disease phenotype. The most notable mutation is the lamin A mutation Q432X that alters LINC complex protein assemblies and causes chromosomal and transcription factor rearrangements.ConclusionMutations in Nesprin-2 and lamin A are characterised by complex genotype phenotype relations. Our data show that each mutation in LMNAanalysed here has a distinct impact on the interaction among both proteins that substantially explains how distinct mutations in widely expressed genes lead to the formation of phenotypically different diseases.
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Nesprin interchain associations control nuclear size
Cellular and Molecular Life Sciences, 2012Co-Authors: Wenshu Lu, Martina Munck, Surayya Taranum, Sascha Neumann, Maria Schneider, Verena-maren Jaeger, Sarah Cartwright, Christine Richardson, James Carthew, Martin GoldbergAbstract:Nesprins-1/-2/-3/-4 are nuclear envelope proteins, which connect nuclei to the cytoskeleton. The largest Nesprin-1/-2 isoforms (termed giant) tether F-actin through their N-terminal actin binding domain (ABD). Nesprin-3, however, lacks an ABD and associates instead to plectin, which binds intermediate filaments. Nesprins are integrated into the outer nuclear membrane via their C-terminal KASH-domain. Here, we show that Nesprin-1/-2 ABDs physically and functionally interact with Nesprin-3. Thus, both ends of Nesprin-1/-2 giant are integrated at the nuclear surface: via the C-terminal KASH-domain and the N-terminal ABD-Nesprin-3 association. Interestingly, Nesprin-2 ABD or KASH-domain overexpression leads to increased nuclear areas. Conversely, Nesprin-2 mini (contains the ABD and KASH-domain but lacks the massive Nesprin-2 giant rod segment) expression yields smaller nuclei. Nuclear shrinkage is further enhanced upon Nesprin-3 co-expression or microfilament depolymerization. Our findings suggest that multivariate intermolecular Nesprin interactions with the cytoskeleton form a lattice-like filamentous network covering the outer nuclear membrane, which determines nuclear size.
Martina Munck - One of the best experts on this subject based on the ideXlab platform.
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Depletion of Nesprin-2 is associated with an embryonic lethal phenotype in mice
2018Co-Authors: Carmen Mroß, Martina Munck, Angelika A. Noegel, Ludwig Eichinger, Vivek S Peche, Gernot Glockner, Marija Marko, Susanne Motameny, Janine Altmüller, Sascha NeumannAbstract:Nesprin-2 is a nuclear envelope component and provides a link between cytoskeletal components of the cytoplasm and the nucleoplasm. Several isoforms are generated from its gene Syne2. Loss of the largest isoform Nesprin-2 Giant in mice is associated with a skin phenotype and altered wound healing, loss of C-terminal isoforms in mice leads to cardiomyopathies and neurological defects. Here we attempted to establish mice with an inducible knockout of all Nesprin-2 isoforms by inserting shRNA encoding sequences targeting the N- and C-terminus into the ROSA26 locus of mice. This caused early embryonic death of the animals harboring the mutant allele, which was presumably due to leaky expression of the shRNAs. Mutant embryos were only observed before E13. They had an altered appearance and were smaller in size than their wild type littermates. From this we conclude that the Nesprin-2 gene function is crucial during embryonic growth, differentiation and organogenesis.
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Nesprin-2 Interacts with Condensin Component SMC2.
International Journal of Cell Biology, 2017Co-Authors: Xin Xing, Carmen Mroß, Linlin Hao, Martina Munck, Alexandra Herzog, Clara Mohr, C. P. Unnikannan, Pranav Kelkar, Angelika A. Noegel, Ludwig EichingerAbstract:The nuclear envelope proteins, Nesprins, have been primarily studied during interphase where they function in maintaining nuclear shape, size, and positioning. We analyze here the function of Nesprin-2 in chromatin interactions in interphase and dividing cells. We characterize a region in the rod domain of Nesprin-2 that is predicted as SMC domain (aa 1436-1766). We show that this domain can interact with itself. It furthermore has the capacity to bind to SMC2 and SMC4, the core subunits of condensin. The interaction was observed during all phases of the cell cycle; it was particularly strong during S phase and persisted also during mitosis. Nesprin-2 knockdown did not affect condensin distribution; however we noticed significantly higher numbers of chromatin bridges in Nesprin-2 knockdown cells in anaphase. Thus, Nesprin-2 may have an impact on chromosomes which might be due to its interaction with condensins or to indirect mechanisms provided by its interactions at the nuclear envelope.
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Nesprin 2 mediated nuclear trafficking and its clinical implications
Nucleus, 2015Co-Authors: Pranav Kelkar, Martina Munck, Anna Walter, Symeon Papadopoulos, Carmen Mros, Vivek S Peche, Angelika A. NoegelAbstract:Nuclear translocation of proteins has a crucial role in the pathogenesis of cancer, Alzheimer disease and viral infections. A complete understanding of nuclear trafficking mechanisms is therefore necessary in order to establish effective intervention strategies. Here we elucidate the role of Nesprin-2 in Ca(2+)/Calmodulin mediated nuclear transport. Nesprin-2 is an actin-binding nuclear envelope (NE) protein with roles in maintaining nuclear structure and location, regulation of transcription and mechanotransduction. Upon depletion of Nesprin-2 using shRNA, HaCaT cells show abnormal localization of the shuttling proteins BRCA1 and NF-κB. We show that their nuclear transport is unlikely due to the canonical RAN mediated nuclear import, but rather to a RAN independent Ca(2+)/Calmodulin driven mechanism involving Nesprin-2. We report novel interactions between the actin-binding domain of Nesprin-2 and Calmodulin and between the NLS containing region of BRCA1 and Calmodulin. Strikingly, displacing Nesprins from the NE resulted in increased steady state Ca(2+) concentrations in the cytoplasm suggesting a previously unidentified role of Nesprins in Ca(2+) regulation. On comparing Nesprin-2 and BRCA1 localization in the ovarian cancer cell lines SKOV-3 and Caov-3, Nesprin-2 and BRCA1 were localized to the NE envelope and the nucleus in SKOV-3, respectively, and to the cytoplasm in Caov-3 cells. Fibroblasts obtained from EDMD5 (Emery Dreifuss muscular dystrophy) patients showed loss of Nesprin-2 from the nuclear envelope, corresponding reduced nuclear localization of BRCA1 and enhanced cytoplasmic Ca(2+). Taken together, the data suggests a novel role of Nesprin-2 in Ca(2+)/Calmodulin mediated nuclear trafficking and provides new insights which can guide future therapies.
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mutations in lmna modulate the lamin a Nesprin 2 interaction and cause linc complex alterations
PLOS ONE, 2013Co-Authors: Liu Yang, Martina Munck, Angelika A. Noegel, Karthic Swaminathan, Larisa E Kapinos, Sascha NeumannAbstract:In eukaryotes the genetic material is enclosed by a continuous membrane system, the nuclear envelope (NE). Along the NE specific proteins assemble to form meshworks and mutations in these proteins have been described in a group of human diseases called laminopathies. Laminopathies include lipodystrophies, muscle and cardiac diseases as well as metabolic or progeroid syndromes. Most laminopathies are caused by mutations in the LMNAgene encoding lamins A/C. Together with Nesprins (Nuclear Envelope Spectrin Repeat Proteins) they are core components of the LINC complex (Linker of Nucleoskeleton and Cytoskeleton). The LINC complex connects the nucleoskeleton and the cytoskeleton and plays a role in the transfer of mechanically induced signals along the NE into the nucleus, and its components have been attributed functions in maintaining nuclear and cellular organization as well as signal transduction.; Here we narrowed down the interaction sites between lamin A and Nesprin-2 to aa 403-425 in lamin A and aa 6146-6347 in Nesprin-2. Laminopathic mutations in and around the involved region of lamin A (R401C, G411D, G413C, V415I, R419C, L421P, R427G, Q432X) modulate the interaction with Nesprin-2 and this may contribute to the disease phenotype. The most notable mutation is the lamin A mutation Q432X that alters LINC complex protein assemblies and causes chromosomal and transcription factor rearrangements.; Mutations in Nesprin-2 and lamin A are characterised by complex genotype phenotype relations. Our data show that each mutation in LMNAanalysed here has a distinct impact on the interaction among both proteins that substantially explains how distinct mutations in widely expressed genes lead to the formation of phenotypically different diseases.
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Mutations in LMNA Modulate the Lamin A - Nesprin-2 Interaction and Cause LINC Complex Alterations
2013Co-Authors: Liu Yang, Martina Munck, Angelika A. Noegel, Karthic Swaminathan, Larisa E Kapinos, Sascha NeumannAbstract:BackgroundIn eukaryotes the genetic material is enclosed by a continuous membrane system, the nuclear envelope (NE). Along the NE specific proteins assemble to form meshworks and mutations in these proteins have been described in a group of human diseases called laminopathies. Laminopathies include lipodystrophies, muscle and cardiac diseases as well as metabolic or progeroid syndromes. Most laminopathies are caused by mutations in the LMNAgene encoding lamins A/C. Together with Nesprins (Nuclear Envelope Spectrin Repeat Proteins) they are core components of the LINC complex (Linker of Nucleoskeleton and Cytoskeleton). The LINC complex connects the nucleoskeleton and the cytoskeleton and plays a role in the transfer of mechanically induced signals along the NE into the nucleus, and its components have been attributed functions in maintaining nuclear and cellular organization as well as signal transduction.ResultsHere we narrowed down the interaction sites between lamin A and Nesprin-2 to aa 403–425 in lamin A and aa 6146–6347 in Nesprin-2. Laminopathic mutations in and around the involved region of lamin A (R401C, G411D, G413C, V415I, R419C, L421P, R427G, Q432X) modulate the interaction with Nesprin-2 and this may contribute to the disease phenotype. The most notable mutation is the lamin A mutation Q432X that alters LINC complex protein assemblies and causes chromosomal and transcription factor rearrangements.ConclusionMutations in Nesprin-2 and lamin A are characterised by complex genotype phenotype relations. Our data show that each mutation in LMNAanalysed here has a distinct impact on the interaction among both proteins that substantially explains how distinct mutations in widely expressed genes lead to the formation of phenotypically different diseases.