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Derek J. Blake - One of the best experts on this subject based on the ideXlab platform.
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Different Dystrophin-like Complexes Are Expressed in Neurons and Glia
2013Co-Authors: Derek J. Blake, Richard Hawkes, Matthew A. Benson, Phillip W. BeesleyAbstract:Abstract. Duchenne muscular dystrophy is a fatal muscle disease that is often associated with cognitive impairment. Accordingly, dystrophin is found at the muscle sarcolemma and at postsynaptic sites in neurons. In muscle, dystrophin forms part of a membrane-spanning complex, the dystrophin-associated protein complex (DPC). Whereas the composition of the DPC in muscle is well documented, the existence of a similar complex in brain remains largely unknown. To determine the composition of DPC-like complexes in brain, we have examined the molecular associations and distribution of the Dystrobrevins, a widely expressed family of dystrophin-associated proteins, some of which are components of the muscle DPC. �-Dystrobrevin is found in neurons and is highly enriched in postsynaptic densitie
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Differential spatio-temporal expression of alpha-Dystrobrevin-1 during mouse development.
Gene Expression Patterns, 2004Co-Authors: Chun-fu Lien, Derek J. Blake, Christina Vlachouli, J. Paul Simons, Dariusz C. GóreckiAbstract:Dystrobrevins are a family of dystrophin-related and dystrophin-associated proteins. α-Dystrobrevin-1 knockout mice suffer from skeletal and cardiac myopathies. It has been suggested that the pathology is caused by the loss of signalling functions but the exact role of Dystrobrevins is largely unknown. We have analysed the spatial and temporal expression of α-Dystrobrevin-1 during mouse embryogenesis and found striking developmental regulation and distribution patterns. During development this protein was expressed not only in muscle but also in the CNS, sensory organs, epithelia and skeleton. Particularly interesting was the correlation of α-Dystrobrevin-1 expression with the induction of various differentiation processes in the developing eye, inner ear, pituitary, blood-brain barrier, stomach epithelium and areas of the brain, dorsal root ganglia and spinal cord. In contrast, this specific expression at the induction phase decreased/disappeared at later stages of development.
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Dystrobrevin dynamics in muscle-cell signalling: a possible target for therapeutic intervention in Duchenne muscular dystrophy?
Neuromuscular Disorders, 2002Co-Authors: Derek J. BlakeAbstract:Abstract The dystrophin-protein complex forms one of the connections between the extracellular matrix and the cytoskeleton of muscle. This link is disrupted in patients with Duchenne and Becker muscular dystrophies. Dystrobrevin is a component of the dystrophin-protein complex that binds to the C-terminus of dystrophin and also to syntrophin. As its name suggests, Dystrobrevin is a relative of dystrophin participating in similar intermolecular interactions. Dystrobrevin-deficient mice have a form of muscular dystrophy that leaves the sarcolemma and dystrophin-protein complex intact but affects an as yet unidentified signalling pathway in muscle. Given that the up-regulation of several genes has a beneficial effect on the muscle in some dystrophic mouse models, α-Dystrobrevin has a number of properties that might be protective in muscular dystrophy. This article discusses the function of Dystrobrevin in muscle and reviews its suitability as a therapeutic target for treating patients with Duchenne and Becker muscular dystrophies.
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Role of beta-Dystrobrevin in nonmuscle dystrophin-associated protein complex-like complexes in kidney and liver.
Molecular and Cellular Biology, 2001Co-Authors: Nellie Y. Loh, Derek J. Blake, Daniela Nebenius-oosthuizen, Andrew J.h. Smith, Kay E. DaviesAbstract:β-Dystrobrevin is a dystrophin-related and -associated protein that is highly expressed in brain, kidney, and liver. Recent studies with the kidneys of the mdx3Cv mouse, which lacks all dystrophin isoforms, suggest that β-Dystrobrevin, and not the dystrophin isoforms, may be the key component in the assembly of complexes similar to the muscle dystrophin-associated protein complexes (DPC) in nonmuscle tissues. To understand the role of β-Dystrobrevin in the function of nonmuscle tissues, we generated β-Dystrobrevin-deficient (dtnb−/−) mice by gene targeting. dtnb−/− mice are healthy, fertile, and normal in appearance. No β-Dystrobrevin was detected in these mice by Western blotting or immunocytochemistry. In addition, the levels of several β-Dystrobrevin-interacting proteins, namely Dp71 isoforms and the syntrophins, were greatly reduced from the basal membranes of kidney tubules and liver sinusoids and on Western blots of crude kidney and liver microsomes of β-Dystrobrevin-deficient mice. However, no abnormality was detected in the ultrastructure of membranes of kidney and liver cells or in the renal function of these mice. β-Dystrobrevin may therefore be an anchor or scaffold for Dp71 and syntrophin isoforms, as well as other associating proteins at the basal membranes of kidney and liver, but is not necessary for the normal function of these mice.
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dysbindin a novel coiled coil containing protein that interacts with the Dystrobrevins in muscle and brain
Journal of Biological Chemistry, 2001Co-Authors: Matthew A. Benson, Richard Hawkes, Sarah E. Newey, Enca Martinrendon, Derek J. BlakeAbstract:The dystrophin-associated protein complex (DPC) is required for the maintenance of muscle integrity during the mechanical stresses of contraction and relaxation. In addition to providing a membrane scaffold, members of the DPC such as the α-Dystrobrevin protein family are thought to play an important role in intracellular signal transduction. To gain additional insights into the function of the DPC, we performed a yeast two-hybrid screen for Dystrobrevin-interacting proteins. Here we describe the identification of a dysbindin, a novel Dystrobrevin-binding protein. Dysbindin is an evolutionary conserved 40-kDa coiled-coil-containing protein that binds to α- and β-Dystrobrevin in muscle and brain. Dystrophin and α-Dystrobrevin are co-immunoprecipitated with dysbindin, indicating that dysbindin is DPC-associated in muscle. Dysbindin co-localizes with α-Dystrobrevin at the sarcolemma and is up-regulated in dystrophin-deficient muscle. In the brain, dysbindin is found primarily in axon bundles and especially in certain axon terminals, notably mossy fiber synaptic terminals in the cerebellum and hippocampus. These findings have implications for the molecular pathology of Duchenne muscular dystrophy and may provide an alternative route for anchoring Dystrobrevin and the DPC to the muscle membrane.
Stanley C. Froehner - One of the best experts on this subject based on the ideXlab platform.
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611. Alpha-Dystrobrevin-3 Prevents Myopathy and Restores Diaphragm Function in the Alpha-Dystrobrevin Null Mouse
Molecular Therapy, 2015Co-Authors: Guy L. Odom, Marvin E Adams, Stanley C. Froehner, Glen B. Banks, Kenneth L. Bible, Jeffrey S. ChamberlainAbstract:The dystrophin-glycoprotein complex (DGC) primarily functions as a structural element enabling a linkage between the cytoskeleton and the extracellular matrix. Alpha-Dystrobrevin (α-Db), a dystrophin subfamily member, is a component of the DGC within striated muscles. Decreasing amounts of α-Db from the sarcolemma contributes to severity of disease in several muscular dystrophies including Duchenne muscular dystrophy (DMD). The functional roles of α-Db1 and α-Db2 in muscle have been well studied. However, the role of a-Db3 has largely been ignored because it lacks many of the known functional domains present in α-Db1 and α-Db2. Importantly, we demonstrate by whole-body adeno-associated viral vector gene transfer into α-Dystrobrevin-null mice, that α-DB3 becomes integrated within the DGC, localizes to costameres, prevents muscle degeneration, synapse fragmentation, myotendinous junction defects and corrects diaphragm functional capacity. Further, we demonstrate α-Db3 can bind the sarcoglycan complex in vitro. Thus, the association of α-Db3 within the DGC appears essential for its function, providing a direct link similar to dystrophin, with transmembrane and cytoplasmic DGC components whose absence likely contributes to sarcolemma fragility and/or disruption of signaling pathways in multiple muscular dystrophies. View Large Image | Download PowerPoint Slide
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The FASEB Journal • FJ Express Full-Length Article Biglycan regulates the expression and sarcolemmal localization of Dystrobrevin, syntrophin, and nNOS
2013Co-Authors: Mary Lynn Mercado, Stanley C. Froehner, Alison R. Amenta, Hiroki Hagiwara, Michael S. Rafii, Beatrice E. Lechner, Rick T. Owens, David J. Mcquillan, Justin R. FallonAbstract:ABSTRACT The dystrophin-associated protein complex (DAPC) provides a linkage between the cytoskeleton and the extracellular matrix (ECM) and is also a scaffold for a host of signaling molecules. The constituents of the DAPC must be targeted to the sarcolemma in order to properly function. Biglycan is an ECM molecule that associates with the DAPC. Here, we show that biglycan null mice exhibit a mild dystrophic phenotype and display a selective reduction in the localization of �-Dystrobrevin-1 and-2, �- and �1-syntrophin, and nNOS at the sarcolemma. Purified biglycan induces nNOS redistribution to the plasma membrane in cultured muscle cells. Biglycan protein injected into muscle becomes stably associated with the sarcolemma and ECM for at least 2 wk. This injected biglycan restores the sarcolemmal expression of �-Dystrobrevin-1 and-2, and �1- and �2-syntrophin in biglycan null mice. We conclude that biglycan is important for the maintenance of muscle cell integrity and plays a direct role in regulating the expression and sarcolemmal localization of the intracellular signaling proteins Dystrobrevin-1 and-2, �- and �1-syntrophin and nNOS.
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Differences in α-Dystrobrevin splice variants between cardiac and skeletal muscle DAPC.
2012Co-Authors: Eric K. Johnson, Marvin E Adams, Stanley C. Froehner, Liwen Zhang, Alistair Phillips, Michael A. Freitas, Kari B. Green-church, Federica MontanaroAbstract:(A) Western blot analysis of α-Dystrobrevins in mouse cardiac (C) and skeletal (S) muscle total protein lysates, DYS-IPs and IgG-IPs. α3-Dystrobrevin associates with dystrophin in the heart. Fold differences in α-Dystrobrevin abundance in cardiac vs. skeletal muscle DYS-IPs relative to dystrophin are shown (averages ±SD, N = 3). (B) Immunolabeling of wild type cardiac sections for α1 and α2-Dystrobrevins. Scale bar: 50 µm. (C) Immunolabeling of mdx cardiac tissue section for β-sarcoglycan. Scale bar: 50 µm. (D) Western blot analysis of α-Dystrobrevins in heart protein lysates from wild type (WT) and mdx mice. Fold differences in α-Dystrobrevin abundance in WT vs. mdx cardiac lysates relative to GAPDH are shown (averages ±SD, N = 3) (E) Western blot analysis of α-Dystrobrevins in DYS-IPs from human (H) and mouse (M) cardiac samples. Additional α-Dystrobrevin isoforms (arrow heads) are detected in human cardiac lysates and DYS-IP.
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Dystrophin-Associated Protein Scaffolding in Brain Requires α-Dystrobrevin
NeuroReport, 2010Co-Authors: April D. Bragg, Sonal S. Das, Stanley C. FroehnerAbstract:Dystrophin and the α-Dystrobrevins bind directly to the adaptor protein syntrophin to form membrane-associated scaffolds. At the blood-brain barrier, α-syntrophin co-localizes with dystrophin and the α-Dystrobrevins in perivascular glial endfeet and is required for localization of the water channel aquaporin-4. We have previously shown that localization of the scaffolding proteins γ2-syntrophin, α-Dystrobrevin-2, and dystrophin to glial endfeet is also dependent upon the presence of α-syntrophin. In the present study, we show that the expression levels of α-syntrophin, γ2-syntrophin, and dystrophin at the blood-brain barrier are reduced in α-Dystrobrevin-null mice. This is the first demonstration that assembly of an astroglial protein scaffold containing syntrophin and dystrophin in perivascular astrocytes is dependent upon the presence of α-Dystrobrevin.
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differential targeting of nnos and aqp4 to dystrophin deficient sarcolemma by membrane directed α Dystrobrevin
Journal of Cell Science, 2008Co-Authors: Marvin E Adams, Yan Tesch, Justin M Percival, Douglas E Albrecht, Jay I Conhaim, Kendra N Anderson, Stanley C. FroehnerAbstract:α-Dystrobrevin associates with and is a homologue of dystrophin, the protein linked to Duchenne and Becker muscular dystrophies. We used a transgenic approach to restore α-Dystrobrevin to the sarcolemma in mice that lack dystrophin (mdx mice) to study two interrelated functions: (1) the ability of α-Dystrobrevin to rescue components of the dystrophin complex in the absence of dystrophin and (2) the ability of sarcolemmal α-Dystrobrevin to ameliorate the dystrophic phenotype. We generated transgenic mice expressing α-Dystrobrevin-2a linked to a palmitoylation signal sequence and bred them onto the α-Dystrobrevin-null and mdx backgrounds. Expression of palmitoylated α-Dystrobrevin prevented the muscular dystrophy observed in the α-Dystrobrevin-null mice, demonstrating that the altered form of α-Dystrobrevin was functional. On the mdx background, the palmitoylated form of α-Dystrobrevin was expressed on the sarcolemma but did not significantly ameliorate the muscular dystrophy phenotype. Palmitoylated Dystrobrevin restored α-syntrophin and aquaporin-4 (AQP4) to the mdx sarcolemma but was unable to recruit β-dystroglycan or the sarcoglycans. Despite restoration of sarcolemmal α-syntrophin, neuronal nitric oxide synthase (nNOS) was not localized to the sarcolemma, suggesting that nNOS requires both dystrophin and α-syntrophin for correct localization. Thus, although nNOS and AQP4 both require interaction with the PDZ domain of α-syntrophin for sarcolemmal association, their localization is regulated differentially.
Kay E. Davies - One of the best experts on this subject based on the ideXlab platform.
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Role of beta-Dystrobrevin in nonmuscle dystrophin-associated protein complex-like complexes in kidney and liver.
Molecular and Cellular Biology, 2001Co-Authors: Nellie Y. Loh, Derek J. Blake, Daniela Nebenius-oosthuizen, Andrew J.h. Smith, Kay E. DaviesAbstract:β-Dystrobrevin is a dystrophin-related and -associated protein that is highly expressed in brain, kidney, and liver. Recent studies with the kidneys of the mdx3Cv mouse, which lacks all dystrophin isoforms, suggest that β-Dystrobrevin, and not the dystrophin isoforms, may be the key component in the assembly of complexes similar to the muscle dystrophin-associated protein complexes (DPC) in nonmuscle tissues. To understand the role of β-Dystrobrevin in the function of nonmuscle tissues, we generated β-Dystrobrevin-deficient (dtnb−/−) mice by gene targeting. dtnb−/− mice are healthy, fertile, and normal in appearance. No β-Dystrobrevin was detected in these mice by Western blotting or immunocytochemistry. In addition, the levels of several β-Dystrobrevin-interacting proteins, namely Dp71 isoforms and the syntrophins, were greatly reduced from the basal membranes of kidney tubules and liver sinusoids and on Western blots of crude kidney and liver microsomes of β-Dystrobrevin-deficient mice. However, no abnormality was detected in the ultrastructure of membranes of kidney and liver cells or in the renal function of these mice. β-Dystrobrevin may therefore be an anchor or scaffold for Dp71 and syntrophin isoforms, as well as other associating proteins at the basal membranes of kidney and liver, but is not necessary for the normal function of these mice.
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A novel mechanism for modulating synaptic gene expression: differential localization of alpha-Dystrobrevin transcripts in skeletal muscle.
Molecular and Cellular Neuroscience, 2001Co-Authors: Sarah E. Newey, Kay E. Davies, Anthony O. Gramolini, Paul J. Holzfeind, Bernard J. Jasmin, Derek J. BlakeAbstract:α-Dystrobrevin is a dystrophin-related and -associated protein that is involved in synapse maturation and is required for normal muscle function. There are three protein isoforms in skeletal muscle, α-Dystrobrevin-1, -2, and -3 that are encoded by the single α-Dystrobrevin gene. To understand the role of these proteins in muscle we have investigated the localisation and transcript distribution of the different α-Dystrobrevin isoforms. α-Dystrobrevin-1 and -2 are concentrated at the neuromuscular junction and are both recruited into agrin-induced acetylcholine receptor clusters in cultured myotubes. We also demonstrate that all α-Dystrobrevin mRNAs are transcribed from a single promoter in skeletal muscle. However, only transcripts encoding α-Dystrobrevin-1 are preferentially accumulated at postsynaptic sites. These data suggest that the synaptic accumulation of α-Dystrobrevin-1 mRNA occurs posttranscriptionally, identifying a novel mechanism for synaptic gene expression. Taken together, these results indicate that different isoforms possess distinct roles in synapse formation and possibly in the pathogenesis of muscular dystrophy.
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Syncoilin, a novel member of the intermediate filament superfamily that interacts with alpha-Dystrobrevin in skeletal muscle.
Journal of Biological Chemistry, 2000Co-Authors: Sarah E. Newey, Ralph Nawrotzki, Nellie Y. Loh, Kay E. Davies, Matthew A. Benson, Emily V. Howman, Chris P. Ponting, Derek J. BlakeAbstract:Dystrophin coordinates the assembly of a complex of structural and signaling proteins that are required for normal muscle function. A key component of the dystrophin protein complex is alpha-Dystrobrevin, a dystrophin-associated protein whose absence results in neuromuscular junction defects and muscular dystrophy. To gain further insights into the role of alpha-Dystrobrevin in skeletal muscle, we used the yeast two-hybrid system to identify a novel alpha-Dystrobrevin-binding partner called syncoilin. Syncoilin is a new member of the intermediate filament superfamily and is highly expressed in skeletal and cardiac muscle. In normal skeletal muscle, syncoilin is concentrated at the neuromuscular junction, where it colocalizes and coimmunoprecipitates with alpha-Dystrobrevin-1. Expression studies in mammalian cells demonstrate that, while alpha-Dystrobrevin and syncoilin associate directly, overexpression of syncoilin does not result in the self-assembly of intermediate filaments. Finally, unlike many components of the dystrophin protein complex, we show that syncoilin expression is up-regulated in dystrophin-deficient muscle. These data suggest that alpha-Dystrobrevin provides a link between the dystrophin protein complex and the intermediate filament network at the neuromuscular junction, which may be important for the maintenance and maturation of the synapse.
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Assembly of multiple Dystrobrevin-containing complexes in the kidney
Journal of Cell Science, 2000Co-Authors: Nellie Y. Loh, Kay E. Davies, Sarah E. Newey, Derek J. BlakeAbstract:Dystrophin is the key component in the assembly and maintenance of the dystrophin-associated protein complex (DPC) in skeletal muscle. In kidney, dystroglycan, an integral component of the DPC, is involved in kidney epithelial morphogenesis, suggesting that the DPC is important in linking the extracellular matrix to the internal cytoskeleton of kidney epithelia. Here, we have investigated the molecular architecture of dystrophin-like protein complexes in kidneys from normal and dystrophin-deficient mice. Using isoform-specific antibodies, we show that the different cell types that make up the kidney maintain different dystrophin-like complexes. These complexes can be broadly grouped according to their Dystrobrevin content: beta-Dystrobrevin containing complexes are present at the basal region of renal epithelial cells, whilst alpha-Dystrobrevin-1 containing complexes are found in endothelial and smooth muscle cells. Furthermore, these complexes are maintained even in the absence of all dystrophin isoforms. Thus our data suggest that the functions and assembly of the dystrophin-like complexes in kidney differ from those in skeletal muscle and implicate a protein other than dystrophin as the primary molecule in the assembly and maintenance of kidney complexes. Our findings also provide a possible explanation for the lack of kidney pathology in Duchenne muscular dystrophy patients and mice lacking all dystrophin isoforms.
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Alternative splicing of Dystrobrevin regulates the stoichiometry of syntrophin binding to the dystrophin protein complex.
Current Biology, 2000Co-Authors: Sarah E. Newey, Kay E. Davies, Matthew A. Benson, Chris P. Ponting, Derek J. BlakeAbstract:Dystrophin coordinates the assembly of a complex of structural and signalling proteins that is required for normal muscle function. A key component of the dystrophin-associated protein complex (DPC) is ?-Dystrobrevin, a dystrophin-related and -associated protein whose absence results in muscular dystrophy and neuromuscular junction defects. The current model of the DPC predicts that dystrophin and Dystrobrevin each bind a single syntrophin molecule. The syntrophins are PDZ-domain-containing proteins that facilitate the recruitment of signalling proteins such as nNOS (neuronal nitric oxide synthase) to the DPC. Here we show, using yeast two-hybrid analysis and biochemical binding studies, that ?-Dystrobrevin in fact contains two independent syntrophin-binding sites in tandem. The previously undescribed binding site is situated within an alternatively spliced exon of ?-Dystrobrevin, termed the variable region-3 (vr3) sequence, which is specifically expressed in skeletal and cardiac muscle. Analysis of the syntrophin-binding region of Dystrobrevin reveals a tandem pair of predicted ? helices with significant sequence similarity. These ? helices, each termed a syntrophin-binding motif, are also highly conserved in dystrophin and utrophin. Together these data show that there are four potential syntrophin-binding sites per dystrophin complex in skeletal muscle: two on Dystrobrevin and two on dystrophin or utrophin. Furthermore, alternative splicing of Dystrobrevin provides a mechanism for regulating the stoichiometry of syntrophin association with the DPC. This is likely to have important consequences for the recruitment of specific signalling molecules to the DPC and ultimately for its function.
Louis M Kunkel - One of the best experts on this subject based on the ideXlab platform.
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Deficiency of the syntrophins and α-Dystrobrevin in patients with inherited myopathy
Neuromuscular Disorders, 2003Co-Authors: Kristi J Jones, Stanley C. Froehner, Louis M Kunkel, Matthew F. Peters, Alison G. Compton, Nan Yang, M.a Mills, David Mowat, Kathryn N. NorthAbstract:Abstract The syntrophins and Dystrobrevins are members of the dystrophin-associated protein complex, and are thought to function as modular adaptors for signalling proteins recruited to the sarcolemmal membrane. We have characterised the expression of the syntrophins (α-, β1-, and β2-) and α-Dystrobrevin by immunohistochemistry in normal human muscle and in biopsies from 162 patients with myopathies of unknown aetiology (with normal staining for dystrophin and other dystrophin-associated proteins). Unlike mice, β2-syntrophin is expressed at the sarcolemma in post-natal human skeletal muscle. Deficiency of α-Dystrobrevin +/− β2-syntrophin was present in 16/162 (10%) patients, compared to age-matched controls. All patients presented with congenital-onset hypotonia and weakness, although there was variability in clinical severity. Two major clinical patterns emerged: patients with deficiency of β2-syntrophin and α-Dystrobrevin presented with severe congenital weakness and died in the first year of life, and two patients with deficiency of α-Dystrobrevin had congenital muscular dystrophy with complete external ophthalmoplegia. We have sequenced the coding regions of α-Dystrobrevin and β2-syntrophin in these patients, and identified a new isoform of Dystrobrevin, but have not identified any mutations. This suggests that disease causing mutations occur outside the coding region of these genes, in gene(s) encoding other components of the syntrophin–Dystrobrevin subcomplex, or in gene(s) responsible for their post-translational modification and normal localisation.
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Desmuslin, an intermediate filament protein that interacts with α-Dystrobrevin and desmin
Proceedings of the National Academy of Sciences, 2001Co-Authors: Yuji Mizuno, Michihiro Imamura, Eijiro Ozawa, Terri G. Thompson, Jeffrey Robert Guyon, Hart G.w. Lidov, Melissa Brosius, Simon C. Watkins, Louis M KunkelAbstract:Abstract Dystrobrevin is a component of the dystrophin-associated protein complex and has been shown to interact directly with dystrophin, α1-syntrophin, and the sarcoglycan complex. The precise role of α-Dystrobrevin in skeletal muscle has not yet been determined. To study α-Dystrobrevin's function in skeletal muscle, we used the yeast two-hybrid approach to look for interacting proteins. Three overlapping clones were identified that encoded an intermediate filament protein we subsequently named desmuslin (DMN). Sequence analysis revealed that DMN has a short N-terminal domain, a conserved rod domain, and a long C-terminal domain, all common features of type 6 intermediate filament proteins. A positive interaction between DMN and α-Dystrobrevin was confirmed with an in vitro coimmunoprecipitation assay. By Northern blot analysis, we find that DMN is expressed mainly in heart and skeletal muscle, although there is some expression in brain. Western blotting detected a 160-kDa protein in heart and skeletal muscle. Immunofluorescent microscopy localizes DMN in a stripe-like pattern in longitudinal sections and in a mosaic pattern in cross sections of skeletal muscle. Electron microscopic analysis shows DMN colocalized with desmin at the Z-lines. Subsequent coimmunoprecipitation experiments confirmed an interaction with desmin. Our findings suggest that DMN may serve as a direct linkage between the extracellular matrix and the Z-discs (through plectin) and may play an important role in maintaining muscle cell integrity.
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Differential Membrane Localization and Intermolecular Associations of α-Dystrobrevin Isoforms in Skeletal Muscle
Journal of Cell Biology, 1998Co-Authors: Matthew F. Peters, Louis M Kunkel, Joshua R. Sanes, Hélène M. Sadoulet-puccio, R. Mark Grady, Neal R. Kramarcy, Robert Sealock, Stanley C. FroehnerAbstract:α-Dystrobrevin is both a dystrophin homologue and a component of the dystrophin protein complex. Alternative splicing yields five forms, of which two predominate in skeletal muscle: full-length α-Dystrobrevin-1 (84 kD), and COOH-terminal truncated α-Dystrobrevin-2 (65 kD). Using isoform-specific antibodies, we find that α-Dystrobrevin-2 is localized on the sarcolemma and at the neuromuscular synapse, where, like dystrophin, it is most concentrated in the depths of the postjunctional folds. α-Dystrobrevin-2 preferentially copurifies with dystrophin from muscle extracts. In contrast, α-Dystrobrevin-1 is more highly restricted to the synapse, like the dystrophin homologue utrophin, and preferentially copurifies with utrophin. In yeast two-hybrid experiments and coimmunoprecipitation of in vitro–translated proteins, α-Dystrobrevin-2 binds dystrophin, whereas α-Dystrobrevin-1 binds both dystrophin and utrophin. α-Dystrobrevin-2 was lost from the nonsynaptic sarcolemma of dystrophin-deficient mdx mice, but was retained on the perisynaptic sarcolemma even in mice lacking both utrophin and dystrophin. In contrast, α-Dystrobrevin-1 remained synaptically localized in mdx and utrophin-negative muscle, but was absent in double mutants. Thus, the distinct distributions of α-Dystrobrevin-1 and -2 can be partly explained by specific associations with utrophin and dystrophin, but other factors are also involved. These results show that alternative splicing confers distinct properties of association on the α-Dystrobrevins.
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β-Dystrobrevin, a New Member of the Dystrophin Family IDENTIFICATION, CLONING, AND PROTEIN ASSOCIATIONS
Journal of Biological Chemistry, 1997Co-Authors: Matthew F. Peters, Marvin E Adams, Louis M Kunkel, Kristine F. O’brien, Hélène M. Sadoulet-puccio, Stanley C. FroehnerAbstract:Abstract Dystrophin, the protein disrupted in Duchenne muscular dystrophy, is one of several related proteins that are key components of the submembrane cytoskeleton. Three dystrophin-related proteins (utrophin, dystrophin-related protein-2 (DRP2), and Dystrobrevin) have been described. Here, we identify a human gene on chromosome 2p22–23 that encodes a novel protein, β-Dystrobrevin, with significant homology to the other known Dystrobrevin (now termed α-Dystrobrevin). Sequence alignments including this second Dystrobrevin strongly support the concept that two distinct subfamilies exist within the dystrophin family, one composed of dystrophin, utrophin, and DRP2 and the other composed of α- and β-Dystrobrevin. The possibility that members of each subfamily form distinct protein complexes was examined by immunopurifying Dystrobrevins and dystrophin. A β-Dystrobrevin antibody recognized a protein of the predicted size (71 kDa) that copurified with the dystrophin short form, Dp71. Thus, like α-Dystrobrevin, β-Dystrobrevin is likely to associate directly with dystrophin. α- and β-Dystrobrevins failed to copurify with each other, however. These results suggest that members of the Dystrobrevin subfamily form heterotypic associations with dystrophin and raise the possibility that pairing of a particular Dystrobrevin with dystrophin may be regulated, thereby providing a mechanism for assembly of distinct submembrane protein complexes.
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Dystrobrevin and dystrophin: An interaction through coiled-coil motifs
Proceedings of the National Academy of Sciences, 1997Co-Authors: Hélène M. Sadoulet-puccio, Michael Rajala, Louis M KunkelAbstract:Dystrobrevin, a dystrophin-related and -associated protein, has been proposed to be important in the formation and maintenance of the neuromuscular junction. Dystrobrevin coprecipitates with both the acetylcholine receptor complex as well as the dystrophin glycoprotein complex. Although the nature of Dystrobrevin’s association with the dystrophin glycoprotein complex remains unclear, it is known that Dystrobrevin binds directly to the syntrophins, a heterologous group of dystrophin-associated proteins. Using the yeast two-hybrid system to identify protein–protein interactions, we present evidence for the heterodimerization of Dystrobrevin directly with dystrophin. The C terminus of Dystrobrevin binds specifically to the C terminus of dystrophin. We further refined this site of interaction to these proteins’ homologous coiled-coil motifs that flank their respective syntrophin-binding sites. We also show that the interaction between the Dystrobrevin and dystrophin coiled-coil domains is specific and is not due to a nonspecific coiled-coil domain interaction. From the accumulated evidence of protein–protein interactions presented here and elsewhere, we propose a partially revised model of the organization of the dystrophin-associated glycoprotein complex.
K.h. Peterson - One of the best experts on this subject based on the ideXlab platform.
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A possible role for α-Dystrobrevin in the reorganization of tight junctions in epithelial cells
2013Co-Authors: A. Sjö, Karl-eric Magnusson, K.h. PetersonAbstract:Alpha-Dystrobrevin (α -DB) has been described primarily as a cytoplasmic component of the dystrophin-glycoprotein complex (DGC) in skeletal muscle cells. Isoforms of α -DB show different localizati ...
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Association of α-Dystrobrevin with Reorganizing Tight Junctions
The Journal of Membrane Biology, 2005Co-Authors: A. Sjö, K.e. Magnusson, K.h. PetersonAbstract:Alpha-Dystrobrevin (α-DB) has been described primarily as a cytoplasmic component of the dystrophin-glycoprotein complex in skeletal muscle cells. Isoforms of α-DB show different localization in cells and tissues; at basolateral membranes in epithelial cells, Dystrobrevins mediate contact with the extracellular matrix, peripheral and transmembrane proteins and the filamentous actin cytoskeleton. Beside their structural role, α-DBs are assumed to be important in cell signalling and cell differentiation. We have primarily assessed the role of α-DB in two epithelial cell lines (MDCK I, HT 29), which represent different developmental stages and exhibit distinct permeability characteristics. Using a polyclonal anti-α-DB antibody, we have investigated its expression, localization and association with tight junction (TJ)- associated proteins (ZO-1, occludin) before and after protein kinase C (PKC) activation with phorbol myristate acetate. Distinct subsets of α-DB isoforms were detected in the two cell lines by immunoblotting. In both cell lines there was submembranous localization of α-DB both apically and basolaterally, shown with confocal imaging. PKC activation caused a reorganization of TJ, which was parallel to increased localization of α-DB to TJ areas, most pronounced in MDCK I cells. Moreover, actin and ZO-1 co-immunoprecipitated with a-DB, as displayed with immunoblotting. Our findings suggest that a-Dystrobrevin specifically is associated with the tight junctions during their reorganization.