Anchors the extracellular matrix to the cytoskeleton via F-actin. Ligand for dystroglycan. Component of the dystrophin-associated glycoprotein complex which accumulates at the neuromuscular junction (NMJ) and at a variety of synapses in the peripheral and central nervous systems and has a structural function in stabilizing the sarcolemma. Also implicated in signaling events and synaptic transmission.
The dystrophin glycoprotein complex (DGC) is a multimeric protein assembly associated with either the X-linked cytoskeletal protein dystrophin or its autosomal homologue utrophin. In striated muscle cells, the DGC links the extracellular matrix to the actin cytoskeleton and mediates three major functions: structural stability of the plasma membrane, ion homeostasis, and transmembrane signaling. Mutations affecting the DGC underlie major forms of congenital muscle dystrophies. The DGC is prominent also in the central and peripheral nervous system and in tissues with a secretory function or which form barriers between functional compartments, such as the blood-brain barrier, choroid plexus, or kidney. A considerable molecular heterogeneity arises from cell-specific expression of its constituent proteins, notably short C-terminal isoforms of dystrophin. Experimentally, the generation of mice carrying targeted gene deletions affecting the DGC has clarified the interdependence of DGC proteins for assembly of the complex and revealed its importance for brain development and regulation of the 'milieu intérieur. Here, we focus on recent studies of the DGC in brain, blood-brain barrier and choroid plexus, retina, and kidney and discuss the role of dystrophin isoforms and utrophin for assembly of the complex in these tissues.
J. Cell. Sci. 115, 4215-4225 (2002)[PubMed:12376554]
Recent studies have characterised a family of giant cytoskeletal crosslinkers encoded by the short stop gene in Drosophila and the dystonin/BPAG1 and MACF1 genes in mammals. We refer to the products of these genes as spectraplakins to highlight the fact that they share features with both the spectrin and plakin superfamilies. These genes produce a variety of large proteins, up to almost 9000 residues long, which can potentially extend 0.4 micro m across a cell. Spectraplakins can interact with all three elements of the cytoskeleton: actin, microtubules and intermediate filaments. The analysis of mutant phenotypes in BPAG1 in mouse and short stop in Drosophila demonstrates that spectraplakins have diverse roles. These include linking the plasma membrane and the cytoskeleton, linking together different elements of the cytoskeleton and organising membrane domains.
Platelets are crucial at the site of vascular injury, adhering to the sub-endothelial matrix through receptors on their surface, leading to cell activation and aggregation to form a haemostatic plug. Platelets display focal adhesions as well as stress fibres to contract and facilitate expulsion of growth and pro-coagulant factors contained in the granules and to constrict the clot. The interaction of F-actin with different actin-binding proteins determines the properties and composition of the focal adhesions. Recently, we demonstrated the presence of dystrophin-associated protein complex corresponding to short dystrophin isoforms (Dp71d and Dp71) and the uthophin gene family (Up400 and Up71), which promote shape change, adhesion, aggregation, and granule centralisation. To elucidate participation of both complexes during the platelet adhesion process, their potential association with integrin beta-1 fraction and the focal adhesion system (alpha-actinin, vinculin and talin) was evaluated by immunofluorescence and immunoprecipitation assays. It was shown that the short dystrophin-associated protein complex participated in stress fibre assembly and in centralisation of cytoplasmic granules, while the utrophin-associated protein complex assembled and regulated focal adhesions. The simultaneous presence of dystrophin and utrophin complexes indicates complementary structural and signalling mechanisms to the actin network, improving the platelet haemostatic role.
Interacting selectively and non-covalently with dystroglycan. Dystroglycan is glycoprotein found in non-muscle tissues as well as in muscle tissues, often in association with dystrophin. The native dystroglycan cleaved into two non-covalently associated subunits, alpha (N-terminal) and beta (C-terminal).
Evidence
1:
Inferred from Physical InteractionUniProtKB
J. Biol. Chem. 270, 27305-27310 (1995)[PubMed:7592992]
Dystrophin, the product of the Duchenne muscular dystrophy gene, is tightly associated with the sarcolemmal membrane to a large glycoprotein complex. One function of the dystrophin-glycoprotein complex is to link the cytoskeleton to the extracellular matrix in skeletal muscle. However, the molecular interactions of dystrophin with the membrane components of the dystrophin-glycoprotein complex are still elusive. Here, we demonstrate and characterize a specific interaction between beta-dystroglycan and dystrophin. We show that skeletal muscle and brain dystrophin as well as brain dystrophin isoforms specifically bind to beta-dystroglycan. To localize and characterize the dystrophin and beta-dystroglycan interaction domains, we reconstituted the interaction in vitro using dystrophin fusion proteins and in vitro translated beta-dystroglycan. We demonstrated that the 15 C-terminal amino acids of beta-dystroglycan constituted a unique binding site for the second half of the hinge 4 and the cysteine-rich domain of dystrophin (amino acids 3054-3271). This dystrophin binding site is located in a proline-rich environment of beta-dystroglycan within amino acids 880-895. The identification of the interaction sites in dystrophin and beta-dystroglycan provides further insight into the structure and the molecular organization of the dystrophin-glycoprotein complex at the sarcolemma membrane and will be helpful for studying the pathogenesis of Duchenne muscular dystrophy.
Interacting selectively and non-covalently with any part of a myosin complex; myosins are any of a superfamily of molecular motor proteins that bind to actin and use the energy of ATP hydrolysis to generate force and movement along actin filaments.
Platelets are crucial at the site of vascular injury, adhering to the sub-endothelial matrix through receptors on their surface, leading to cell activation and aggregation to form a haemostatic plug. Platelets display focal adhesions as well as stress fibres to contract and facilitate expulsion of growth and pro-coagulant factors contained in the granules and to constrict the clot. The interaction of F-actin with different actin-binding proteins determines the properties and composition of the focal adhesions. Recently, we demonstrated the presence of dystrophin-associated protein complex corresponding to short dystrophin isoforms (Dp71d and Dp71) and the uthophin gene family (Up400 and Up71), which promote shape change, adhesion, aggregation, and granule centralisation. To elucidate participation of both complexes during the platelet adhesion process, their potential association with integrin beta-1 fraction and the focal adhesion system (alpha-actinin, vinculin and talin) was evaluated by immunofluorescence and immunoprecipitation assays. It was shown that the short dystrophin-associated protein complex participated in stress fibre assembly and in centralisation of cytoplasmic granules, while the utrophin-associated protein complex assembled and regulated focal adhesions. The simultaneous presence of dystrophin and utrophin complexes indicates complementary structural and signalling mechanisms to the actin network, improving the platelet haemostatic role.
Nitric oxide (NO) is synthesized in skeletal muscle by neuronal-type NO synthase (nNOS), which is localized to sarcolemma of fast-twitch fibers. Synthesis of NO in active muscle opposes contractile force. We show that nNOS partitions with skeletal muscle membranes owing to association of nNOS with dystrophin, the protein mutated in Duchenne muscular dystrophy (DMD). The dystrophin complex interacts with an N-terminal domain of nNOS that contains a GLGF motif. mdx mice and humans with DMD evince a selective loss of nNOS protein and catalytic activity from muscle membranes, demonstrating a novel role for dystrophin in localizing a signaling enzyme to the myocyte sarcolemma. Aberrant regulation of nNOS may contribute to preferential degeneration of fast-twitch muscle fibers in DMD.
Interacting selectively and non-covalently with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules).
Evidence
1:
Inferred from Physical InteractionIntAct
Evidence for Iso 5
beta-dystroglycan (DG) and the dystrophin-glycoprotein complex (DGC) are localized at costameres and neuromuscular junctions in the sarcolemma of skeletal muscle. We present evidence for an ankyrin-based mechanism for sarcolemmal localization of dystrophin and beta-DG. Dystrophin binds ankyrin-B and ankyrin-G, while beta-DG binds ankyrin-G. Dystrophin and beta-DG require ankyrin-G for retention at costameres but not delivery to the sarcolemma. Dystrophin and beta-DG remain intracellular in ankyrin-B-depleted muscle, where beta-DG accumulates in a juxta-TGN compartment. The neuromuscular junction requires ankyrin-B for localization of dystrophin/utrophin and beta-DG and for maintenance of its postnatal morphology. A Becker muscular dystrophy mutation reduces ankyrin binding and impairs sarcolemmal localization of dystrophin-Dp71. Ankyrin-B also binds to dynactin-4, a dynactin subunit. Dynactin-4 and a subset of microtubules disappear from sarcolemmal sites in ankyrin-B-depleted muscle. Ankyrin-B thus is an adaptor required for sarcolemmal localization of dystrophin, as well as dynactin-4.
Evidence
2:
Inferred from Physical InteractionUniProtKB
Synemin is a unique, very large intermediate filament (IF) protein present in all types of muscle cells, which forms heteropolymeric intermediate filaments (IFs) with the major IF proteins desmin and/or vimentin. We show herein that tissue-purified avian synemin directly interacts with both dystrophin and utrophin, and that specific expressed regions of both of the mammalian (human) synemin isoforms (alpha-synemin and beta-synemin) directly interact with specific expressed domains/regions of the dystrophin and utrophin molecules. Mammalian synemin is also shown to colocalize with dystrophin within muscle cell cultures. These results indicate that synemin is an important IF protein in muscle cells that helps fortify the linkage between the peripheral layer of cellular myofibrils and the costameric regions located along the sarcolemma and the sarcolemma region located within the neuromuscular and myotendinous junctions (NMJs and MTJs).
Evidence
3:
Inferred from Physical InteractionUniProtKB
Cytokeratins 8 and 19 concentrate at costameres of striated muscle and copurify with the dystrophin-glycoprotein complex, perhaps through the interaction of the cytokeratins with the actin-binding domain of dystrophin. We overexpressed dystrophin's actin-binding domain (Dys-ABD), K8 and K19, as well as closely related proteins, in COS-7 cells to assess the basis and specificity of their interaction. Dys-ABD alone associated with actin microfilaments. Expressed with K8 and K19, which form filaments, Dys-ABD associated preferentially with the cytokeratins. This interaction was specific, as the homologous ABD of betaI-spectrin failed to interact with K8/K19 filaments, and Dys-ABD did not associate with desmin or K8/K18 filaments. Studies in COS-7 cells and in vitro showed that Dys-ABD binds directly and specifically to K19. Expressed in muscle fibers in vivo, K19 accumulated in the myoplasm in structures that contained dystrophin and spectrin and disrupted the organization of the sarcolemma. K8 incorporated into sarcomeres, with no effect on the sarcolemma. Our results show that dystrophin interacts through its ABD with K19 specifically and are consistent with the idea that cytokeratins associate with dystrophin at the sarcolemma of striated muscle.
Evidence
4:
Inferred from Physical InteractionIntAct
Dystrophin, the protein product of the Duchenne muscular dystrophy locus, is a protein of the membrane cytoskeleton that associates with a complex of integral and membrane-associated proteins. Of these, the 58-kD intracellular membrane-associated protein, syntrophin, was recently shown to consist of a family of three related but distinct genes. We expressed the cDNA of human beta 1-syntrophin and the COOH terminus of human dystrophin in reticulocyte lysates using an in vitro transcription/translation system. Using antibodies to dystrophin we immunoprecipitated these two interacting proteins in a variety of salt and detergent conditions. We demonstrate that the 53 amino acids encoded on exon 74 of dystrophin, an alternatively spliced exon, are necessary and sufficient for interaction with translated beta 1-syntrophin in our assay. On the basis of its alternative splicing, dystrophin may thus be present in two functionally distinct populations. In this recombinant expression system, the dystrophin relatives, human dystrophin related protein (DRP or utrophin) and the 87K postsynaptic protein from Torpedo electric organ, also bind to translated beta 1-syntrophin. We have found a COOH-terminal 37-kD fragment of beta 1-syntrophin sufficient to interact with translated dystrophin and its homologues, suggesting that the dystrophin binding site on beta 1-syntrophin occurs on a region that is conserved among the three syntrophin homologues.
Evidence
5:
Inferred from Physical InteractionIntAct
J. Biol. Chem. 271, 2724-2730 (1996)[PubMed:8576247]
The syntrophins are a biochemically heterogeneous group of 58-kDa intracellular membrane-associated dystrophin-binding proteins. We have cloned and characterized human acidic (alpha 1-) syntrophin and a second isoform of human basic (beta 2-) syntrophin. Comparison of the deduced amino acid structure of the three human isoforms of syntrophin (together with the previously reported human beta 1-syntrophin) demonstrates their overall similarity. The deduced amino acid sequences of human alpha 1- and beta 2-syntrophin are nearly identical to their homologues in mouse, suggesting a strong functional conservation among the individual isoforms, Much like beta 1-syntrophin, human beta 2-syntrophin has multiple transcript classes and is expressed widely, although in a distinct pattern of relative abundance. In contrast, human alpha 1-syntrophin is most abundant in heart and skeletal muscle, and less so in other tissues. Somatic cell hybrids and fluorescent in situ hybridization were both used to determine their chromosomal locations: beta 2-syntrophin to chromosome 16q22-23 and alpha 1-syntrophin to chromosome 20q11.2. Finally, we used in vitro translated proteins in an immunoprecipitation assay to show that, like beta 1-syntrophin, both beta 2- and alpha 1-syntrophin interact with peptides encoding the syntrophin-binding region of dystrophin, utrophin/dystrophin related protein, and the Torpedo 87K protein.
The complete sequence of the human Duchenne muscular dystrophy (DMD) cDNA has been determined. The 3685 encoded amino acids of the protein product, dystrophin, can be separated into four domains. The 240 amino acid N-terminal domain has been shown to be conserved with the actin-binding domain of alpha-actinin. A large second domain is predicted to be rod-shaped and formed by the succession of 25 triple-helical segments similar to the repeat domains of spectrin. The repeat segment is followed by a cysteine-rich segment that is similar in part to the entire COOH domain of the Dictyostelium alpha-actinin, while the 420 amino acid C-terminal domain of dystrophin does not show any similarity to previously reported proteins. The functional significance of some of the domains is addressed relative to the phenotypic characteristics of some Becker muscular dystrophy patients. Dystrophin shares many features with the cytoskeletal protein spectrin and alpha-actinin and is a large structural protein that is likely to adopt a rod shape about 150 nm in length.
Duchenne muscular dystrophy (DMD) and its milder form, Becker muscular dystrophy (BMD), are allelic X-linked muscle disorders in man. The gene responsible for the disease has been cloned from knowledge of its map location at band Xp21 on the short arm of the X chromosome. The product of the DMD gene, a protein of relative molecular mass 400,000 (Mr 400K) recently named dystrophin, has been reported to co-purify with triads of mouse and rabbit skeletal muscle when assayed using polyclonal antibodies raised against fusion proteins encoded by regions of mouse DMD complementary DNA. Here we show that antibodies directed against synthetic peptides and fusion proteins derived from the N-terminal region of human DMD cDNA strongly react with an antigen present in skeletal muscle sarcolemma on cryostat sections of normal human muscle biopsies. This immunoreactivity is reduced or absent in muscle fibres from DMD patients but appears normal in muscle fibres from patients with other myopathic diseases. The same antibodies specifically react with a 400K protein in sodium dodecyl sulphate (SDS) extracts of normal human muscle subjected to Western blot analysis. We conclude that the product of the DMD gene is associated with the sarcolemma rather than with the triads and speculate that it strengthens the sarcolemma by anchoring elements of the internal cytoskeleton to the surface membrane.
Cytokeratins 8 and 19 concentrate at costameres of striated muscle and copurify with the dystrophin-glycoprotein complex, perhaps through the interaction of the cytokeratins with the actin-binding domain of dystrophin. We overexpressed dystrophin's actin-binding domain (Dys-ABD), K8 and K19, as well as closely related proteins, in COS-7 cells to assess the basis and specificity of their interaction. Dys-ABD alone associated with actin microfilaments. Expressed with K8 and K19, which form filaments, Dys-ABD associated preferentially with the cytokeratins. This interaction was specific, as the homologous ABD of betaI-spectrin failed to interact with K8/K19 filaments, and Dys-ABD did not associate with desmin or K8/K18 filaments. Studies in COS-7 cells and in vitro showed that Dys-ABD binds directly and specifically to K19. Expressed in muscle fibers in vivo, K19 accumulated in the myoplasm in structures that contained dystrophin and spectrin and disrupted the organization of the sarcolemma. K8 incorporated into sarcomeres, with no effect on the sarcolemma. Our results show that dystrophin interacts through its ABD with K19 specifically and are consistent with the idea that cytokeratins associate with dystrophin at the sarcolemma of striated muscle.
Interacting selectively and non-covalently with vinculin, a protein found in muscle, fibroblasts, and epithelial cells that binds actin and appears to mediate attachment of actin filaments to integral proteins of the plasma membrane.
Evidence
1:
Inferred from Physical InteractionBHF-UCL
Platelets are crucial at the site of vascular injury, adhering to the sub-endothelial matrix through receptors on their surface, leading to cell activation and aggregation to form a haemostatic plug. Platelets display focal adhesions as well as stress fibres to contract and facilitate expulsion of growth and pro-coagulant factors contained in the granules and to constrict the clot. The interaction of F-actin with different actin-binding proteins determines the properties and composition of the focal adhesions. Recently, we demonstrated the presence of dystrophin-associated protein complex corresponding to short dystrophin isoforms (Dp71d and Dp71) and the uthophin gene family (Up400 and Up71), which promote shape change, adhesion, aggregation, and granule centralisation. To elucidate participation of both complexes during the platelet adhesion process, their potential association with integrin beta-1 fraction and the focal adhesion system (alpha-actinin, vinculin and talin) was evaluated by immunofluorescence and immunoprecipitation assays. It was shown that the short dystrophin-associated protein complex participated in stress fibre assembly and in centralisation of cytoplasmic granules, while the utrophin-associated protein complex assembled and regulated focal adhesions. The simultaneous presence of dystrophin and utrophin complexes indicates complementary structural and signalling mechanisms to the actin network, improving the platelet haemostatic role.
Electrocardiogram abnormalities are reported to be complicated in Duchenne muscular dystrophy. Although Duchenne muscular dystrophy can be genetically diagnosed in young patients, extensive electrocardiogram studies have not been reported. Here, electrocardiogram abnormalities were examined in Duchenne muscular dystrophy cases with dystrophin gene mutations. Sixty-nine patients, aged </=18 years, received 136 electrocardiogram examinations. Sixty-four patients (91.3%) displayed one or more abnormalities. Furthermore, patients adolescent <10 years (84.8% of patients) displayed electrocardiogram abnormalities, and the most common abnormality was deep Q-waves. Remarkably, the abnormality incidence of both deep Q-waves and low RV5 + SV1 (R-wave V5 + S-wave V1) were significantly high in adolescent patients. Although the patterns or positions of dystrophin gene mutations were compared with electrocardiogram abnormalities, no predisposing mutation was disclosed. These results indicate that electrocardiogram abnormalities in Duchenne muscular dystrophy are a result of dystrophin deficiency, regardless of types of gene mutations. The disease can be divided into two types: age-dependent and age-independent. Deep Q-waves and low RV5 + SV1 are proposed as markers of age-dependent cardiac complications.
Patients with Duchenne muscular dystrophy (DMD) have a progressive dilated cardiomyopathy associated with fatal cardiac arrhythmias. Electrical and functional abnormalities have been attributed to cardiac fibrosis; however, electrical abnormalities may occur in the absence of overt cardiac histopathology. Here we show that structural and functional remodeling of the cardiac sarcoplasmic reticulum (SR) Ca(2+) release channel/ryanodine receptor (RyR2) occurs in the mdx mouse model of DMD. RyR2 from mdx hearts were S-nitrosylated and depleted of calstabin2 (FKBP12.6), resulting in "leaky" RyR2 channels and a diastolic SR Ca(2+) leak. Inhibiting the depletion of calstabin2 from the RyR2 complex with the Ca(2+) channel stabilizer S107 ("rycal") inhibited the SR Ca(2+) leak, inhibited aberrant depolarization in isolated cardiomyocytes, and prevented arrhythmias in vivo. This suggests that diastolic SR Ca(2+) leak via RyR2 due to S-nitrosylation of the channel and calstabin2 depletion from the channel complex likely triggers cardiac arrhythmias. Normalization of the RyR2-mediated diastolic SR Ca(2+) leak prevents fatal sudden cardiac arrhythmias in DMD.
Evidence
2:
Inferred from Sequence or Structural SimilarityBHF-UCL
Duchenne muscular dystrophy is characterized by progressive muscle weakness and early death resulting from dystrophin deficiency. Loss of dystrophin results in disruption of a large dystrophin glycoprotein complex, leading to pathological calcium (Ca2+)-dependent signals that damage muscle cells. We have identified a structural and functional defect in the ryanodine receptor (RyR1), a sarcoplasmic reticulum Ca2+ release channel, in the mdx mouse model of muscular dystrophy that contributes to altered Ca2+ homeostasis in dystrophic muscles. RyR1 isolated from mdx skeletal muscle showed an age-dependent increase in S-nitrosylation coincident with dystrophic changes in the muscle. RyR1 S-nitrosylation depleted the channel complex of FKBP12 (also known as calstabin-1, for calcium channel stabilizing binding protein), resulting in 'leaky' channels. Preventing calstabin-1 depletion from RyR1 with S107, a compound that binds the RyR1 channel and enhances the binding affinity of calstabin-1 to the nitrosylated channel, inhibited sarcoplasmic reticulum Ca2+ leak, reduced biochemical and histological evidence of muscle damage, improved muscle function and increased exercise performance in mdx mice. On the basis of these findings, we propose that sarcoplasmic reticulum Ca2+ leak via RyR1 due to S-nitrosylation of the channel and calstabin-1 depletion contributes to muscle weakness in muscular dystrophy, and that preventing the RyR1-mediated sarcoplasmic reticulum Ca2+ leak may provide a new therapeutic approach.
Any process in which a protein is transported to, and/or maintained in, a specific location at the level of a cell. Localization at the cellular level encompasses movement within the cell, from within the cell to the cell surface, or from one location to another at the surface of a cell.
Nitric oxide (NO) is synthesized in skeletal muscle by neuronal-type NO synthase (nNOS), which is localized to sarcolemma of fast-twitch fibers. Synthesis of NO in active muscle opposes contractile force. We show that nNOS partitions with skeletal muscle membranes owing to association of nNOS with dystrophin, the protein mutated in Duchenne muscular dystrophy (DMD). The dystrophin complex interacts with an N-terminal domain of nNOS that contains a GLGF motif. mdx mice and humans with DMD evince a selective loss of nNOS protein and catalytic activity from muscle membranes, demonstrating a novel role for dystrophin in localizing a signaling enzyme to the myocyte sarcolemma. Aberrant regulation of nNOS may contribute to preferential degeneration of fast-twitch muscle fibers in DMD.
The establishment of the barrier between the perineurium of peripheral nerves and the vascular endothelium of endoneurial capillaries. The perineurium acts as a diffusion barrier, but ion permeability at the blood-nerve barrier is still higher than at the blood-brain barrier.
Establishment of the glial barrier between the blood and the brain. The glial cells in the brain are packed tightly together preventing the passage of most molecules from the blood into the brain. Only lipid soluble molecules or those that are actively transported can pass through the blood-brain barrier.
The assembly of a flagellum. In bacteria, this is a whiplike motility appendage present on the surface of some species; in eukaryotes, flagella are threadlike protoplasmic extensions used to propel flagellates and sperm. Flagella are composed of flagellin and have the same basic structure as cilia but are longer in proportion to the cell and present in much smaller numbers.
Dystrophin Dp71 is expressed in all tissues, with the exception of skeletal muscle, and is the main Duchenne muscular dystrophy (DMD) gene product in brain. As full-length dystrophin does in skeletal muscle, Dp71 associates with dystroglycans, sarcoglycans, dystrobrevins, syntrophins, and accessory proteins to form the dystrophin-associated protein complex (DAPC) in non-muscle tissues. Although it has been nearly 20 years since the discovery of Dp71, its study has become relevant only recently due to its direct involvement with the two main DMD non-muscular phenotypes: cognitive impairment and abnormal retinal physiology. In this review, we describe the historical background of Dp71 and the experimental models developed for its study. Additionally, we present and discuss the experimental evidence supporting the participation of Dp71 in different cellular processes, including cell adhesion, water homeostasis, cell division, and nuclear architecture. The functional diversity of Dp71 is attributed to the formation of Dp71-containing DAPC in numerous cell types and different subcellular compartments, including in plasma membrane and nucleus, as well as to the capability of Dp71-containing DAPC to work as the scaffold for proper clustering and anchoring of structural and signaling proteins to the plasma membrane and of nuclear envelope proteins to the inner nuclear membrane.
The process whose specific outcome is the progression of the muscle fiber over time, from its formation to the mature structure. Muscle fibers are formed by the maturation of myotubes. They can be classed as slow, intermediate/fast or fast.
The process whose specific outcome is the progression of the muscle over time, from its formation to the mature structure. The muscle is an organ consisting of a tissue made up of various elongated cells that are specialized to contract and thus to produce movement and mechanical work.
Duchenne's muscular dystrophy (DMD) is an X-linked progressive myopathy caused by a defect in the DMD gene locus. The gene corresponding to the DMD locus produces a 14-kilobase (kb) messenger RNA that codes for a large cytoskeletal membrane protein, dystrophin. DMD and Becker's muscular dystrophy are the consequences of dystrophin mutations. The exact biological function of dystrophin remains unknown but it has been demonstrated that it is localized to the cytoplasmic face of the cell membrane and has direct interaction with several other membrane proteins. We report here the synthesis of a 14-kb full-length complementary DNA for the mouse muscle dystrophin mRNA and the expression of this cDNA in COS cells. The recombinant dystrophin is indistinguishable from mouse muscle dystrophin by western blot analysis with anti-dystrophin antibodies and was shown by an immunofluorescent technique to be localized in the cell membrane. Our successful construction of a functional full-length cDNA opens opportunities for the study of structure and function of dystrophin and provides an opportunity to initiate gene therapy studies.
The process aimed at the progression of a myotube cell over time, from initial commitment of the cell to a specific fate, to the fully functional differentiated cell. Myotubes are multinucleated cells that are formed when proliferating myoblasts exit the cell cycle, differentiate and fuse.
AIMS: Duchenne muscular dystrophy (DMD) is a muscle disease with serious cardiac complications. Changes in Ca(2+) homeostasis and oxidative stress were recently associated with cardiac deterioration, but the cellular pathophysiological mechanisms remain elusive. We investigated whether the activity of ryanodine receptor (RyR) Ca(2+) release channels is affected, whether changes in function are cause or consequence and which post-translational modifications drive disease progression. METHODS AND RESULTS: Electrophysiological, imaging, and biochemical techniques were used to study RyRs in cardiomyocytes from mdx mice, an animal model of DMD. Young mdx mice show no changes in cardiac performance, but do so after ∼8 months. Nevertheless, myocytes from mdx pups exhibited exaggerated Ca(2+) responses to mechanical stress and 'hypersensitive' excitation-contraction coupling, hallmarks of increased RyR Ca(2+) sensitivity. Both were normalized by antioxidants, inhibitors of NAD(P)H oxidase and CaMKII, but not by NO synthases and PKA antagonists. Sarcoplasmic reticulum Ca(2+) load and leak were unchanged in young mdx mice. However, by the age of 4-5 months and in senescence, leak was increased and load was reduced, indicating disease progression. By this age, all pharmacological interventions listed above normalized Ca(2+) signals and corrected changes in ECC, Ca(2+) load, and leak. CONCLUSION: Our findings suggest that increased RyR Ca(2+) sensitivity precedes and presumably drives the progression of dystrophic cardiomyopathy, with oxidative stress initiating its development. RyR oxidation followed by phosphorylation, first by CaMKII and later by PKA, synergistically contributes to cardiac deterioration.
The process that contributes to the act of creating the structural organization of the oculomotor nerve. This process pertains to the physical shaping of a rudimentary structure. The olfactory nerve is a collection of sensory nerve rootlets that extend down from the olfactory bulb to the olfactory mucosa of the upper parts of the nasal cavity. This nerve conducts odor information to the brainstem.
The chemical reactions and pathways resulting in the formation of peptides, compounds of 2 or more (but usually less than 100) amino acids where the alpha carboxyl group of one is bound to the alpha amino group of another. This may include the translation of a precursor protein and its subsequent processing into a functional peptide.
Cytokeratins 8 and 19 concentrate at costameres of striated muscle and copurify with the dystrophin-glycoprotein complex, perhaps through the interaction of the cytokeratins with the actin-binding domain of dystrophin. We overexpressed dystrophin's actin-binding domain (Dys-ABD), K8 and K19, as well as closely related proteins, in COS-7 cells to assess the basis and specificity of their interaction. Dys-ABD alone associated with actin microfilaments. Expressed with K8 and K19, which form filaments, Dys-ABD associated preferentially with the cytokeratins. This interaction was specific, as the homologous ABD of betaI-spectrin failed to interact with K8/K19 filaments, and Dys-ABD did not associate with desmin or K8/K18 filaments. Studies in COS-7 cells and in vitro showed that Dys-ABD binds directly and specifically to K19. Expressed in muscle fibers in vivo, K19 accumulated in the myoplasm in structures that contained dystrophin and spectrin and disrupted the organization of the sarcolemma. K8 incorporated into sarcomeres, with no effect on the sarcolemma. Our results show that dystrophin interacts through its ABD with K19 specifically and are consistent with the idea that cytokeratins associate with dystrophin at the sarcolemma of striated muscle.
To determine the role of Dp71 in neuronal cells, we generated PC12 cell lines in which Dp71 protein levels were controlled by stable transfection with either antisense or sense constructs. Cells expressing the antisense Dp71 RNA (antisense-Dp71 cells) contained reduced amounts of the two endogenous Dp71 isoforms. Antisense-Dp71 cells exhibited a marked suppression of neurite outgrowth upon the induction with NGF or dibutyryl cyclic AMP. Early responses to NGF-induced neuronal differentiation, such as the cessation of cell division and the activation of ERK1/2 proteins, were normal in the antisense-Dp71 cells. On contrary, the induction of MAP2, a late differentiation marker, was disturbed in these cells. Additionally, the deficiency of Dp71 correlated with an altered expression of the dystrophin-associated protein complex (DAPC) members alpha and beta dystrobrevins. Our results indicate that normal expression of Dp71 is essential for neurite outgrowth in PC12 cells and constitute the first direct evidence implicating Dp71 in a neuronal function.
Any process that increases the rate, frequency or extent of neuron projection development. Neuron projection development is the process whose specific outcome is the progression of a neuron projection over time, from its formation to the mature structure. A neuron projection is any process extending from a neural cell, such as axons or dendrites (collectively called neurites).
To determine the role of Dp71 in neuronal cells, we generated PC12 cell lines in which Dp71 protein levels were controlled by stable transfection with either antisense or sense constructs. Cells expressing the antisense Dp71 RNA (antisense-Dp71 cells) contained reduced amounts of the two endogenous Dp71 isoforms. Antisense-Dp71 cells exhibited a marked suppression of neurite outgrowth upon the induction with NGF or dibutyryl cyclic AMP. Early responses to NGF-induced neuronal differentiation, such as the cessation of cell division and the activation of ERK1/2 proteins, were normal in the antisense-Dp71 cells. On contrary, the induction of MAP2, a late differentiation marker, was disturbed in these cells. Additionally, the deficiency of Dp71 correlated with an altered expression of the dystrophin-associated protein complex (DAPC) members alpha and beta dystrobrevins. Our results indicate that normal expression of Dp71 is essential for neurite outgrowth in PC12 cells and constitute the first direct evidence implicating Dp71 in a neuronal function.
Duchenne muscular dystrophy (DMD), caused by mutations in the dystrophin gene, is associated with severe cardiac complications including cardiomyopathy and cardiac arrhythmias. Recent research suggests that impaired voltage-gated ion channels in dystrophic cardiomyocytes accompany cardiac pathology. It is, however, unknown if the ion channel defects are primary effects of dystrophic gene mutations, or secondary effects of the developing cardiac pathology.
Any process that modulates the frequency, rate or extent of action potential creation, propagation or termination in a cardiac muscle cell. An action potential is a spike of membrane depolarization and repolarization that travels along the membrane of a cell.
Evidence
1:
Inferred from Sequence or Structural SimilarityBHF-UCL
Patients with Duchenne muscular dystrophy (DMD) have a progressive dilated cardiomyopathy associated with fatal cardiac arrhythmias. Electrical and functional abnormalities have been attributed to cardiac fibrosis; however, electrical abnormalities may occur in the absence of overt cardiac histopathology. Here we show that structural and functional remodeling of the cardiac sarcoplasmic reticulum (SR) Ca(2+) release channel/ryanodine receptor (RyR2) occurs in the mdx mouse model of DMD. RyR2 from mdx hearts were S-nitrosylated and depleted of calstabin2 (FKBP12.6), resulting in "leaky" RyR2 channels and a diastolic SR Ca(2+) leak. Inhibiting the depletion of calstabin2 from the RyR2 complex with the Ca(2+) channel stabilizer S107 ("rycal") inhibited the SR Ca(2+) leak, inhibited aberrant depolarization in isolated cardiomyocytes, and prevented arrhythmias in vivo. This suggests that diastolic SR Ca(2+) leak via RyR2 due to S-nitrosylation of the channel and calstabin2 depletion from the channel complex likely triggers cardiac arrhythmias. Normalization of the RyR2-mediated diastolic SR Ca(2+) leak prevents fatal sudden cardiac arrhythmias in DMD.
Evidence
2:
Inferred from Sequence or Structural SimilarityBHF-UCL
Duchenne muscular dystrophy (DMD), caused by mutations in the dystrophin gene, is associated with severe cardiac complications including cardiomyopathy and cardiac arrhythmias. Recent research suggests that impaired voltage-gated ion channels in dystrophic cardiomyocytes accompany cardiac pathology. It is, however, unknown if the ion channel defects are primary effects of dystrophic gene mutations, or secondary effects of the developing cardiac pathology.
Any process that modulates the frequency, rate or extent of cardiac muscle contraction via the regulation of the release of sequestered calcium ion by sarcoplasmic reticulum into cytosol. The sarcoplasmic reticulum is the endoplasmic reticulum of striated muscle, specialised for the sequestration of calcium ions that are released upon receipt of a signal relayed by the T tubules from the neuromuscular junction.
Evidence
1:
Inferred from Sequence or Structural SimilarityBHF-UCL
Patients with Duchenne muscular dystrophy (DMD) have a progressive dilated cardiomyopathy associated with fatal cardiac arrhythmias. Electrical and functional abnormalities have been attributed to cardiac fibrosis; however, electrical abnormalities may occur in the absence of overt cardiac histopathology. Here we show that structural and functional remodeling of the cardiac sarcoplasmic reticulum (SR) Ca(2+) release channel/ryanodine receptor (RyR2) occurs in the mdx mouse model of DMD. RyR2 from mdx hearts were S-nitrosylated and depleted of calstabin2 (FKBP12.6), resulting in "leaky" RyR2 channels and a diastolic SR Ca(2+) leak. Inhibiting the depletion of calstabin2 from the RyR2 complex with the Ca(2+) channel stabilizer S107 ("rycal") inhibited the SR Ca(2+) leak, inhibited aberrant depolarization in isolated cardiomyocytes, and prevented arrhythmias in vivo. This suggests that diastolic SR Ca(2+) leak via RyR2 due to S-nitrosylation of the channel and calstabin2 depletion from the channel complex likely triggers cardiac arrhythmias. Normalization of the RyR2-mediated diastolic SR Ca(2+) leak prevents fatal sudden cardiac arrhythmias in DMD.
Any process that modulates the rate, frequency, or extent of a change in state or activity of a cell (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a growth factor stimulus.
To determine the role of Dp71 in neuronal cells, we generated PC12 cell lines in which Dp71 protein levels were controlled by stable transfection with either antisense or sense constructs. Cells expressing the antisense Dp71 RNA (antisense-Dp71 cells) contained reduced amounts of the two endogenous Dp71 isoforms. Antisense-Dp71 cells exhibited a marked suppression of neurite outgrowth upon the induction with NGF or dibutyryl cyclic AMP. Early responses to NGF-induced neuronal differentiation, such as the cessation of cell division and the activation of ERK1/2 proteins, were normal in the antisense-Dp71 cells. On contrary, the induction of MAP2, a late differentiation marker, was disturbed in these cells. Additionally, the deficiency of Dp71 correlated with an altered expression of the dystrophin-associated protein complex (DAPC) members alpha and beta dystrobrevins. Our results indicate that normal expression of Dp71 is essential for neurite outgrowth in PC12 cells and constitute the first direct evidence implicating Dp71 in a neuronal function.
Electrocardiogram abnormalities are reported to be complicated in Duchenne muscular dystrophy. Although Duchenne muscular dystrophy can be genetically diagnosed in young patients, extensive electrocardiogram studies have not been reported. Here, electrocardiogram abnormalities were examined in Duchenne muscular dystrophy cases with dystrophin gene mutations. Sixty-nine patients, aged </=18 years, received 136 electrocardiogram examinations. Sixty-four patients (91.3%) displayed one or more abnormalities. Furthermore, patients adolescent <10 years (84.8% of patients) displayed electrocardiogram abnormalities, and the most common abnormality was deep Q-waves. Remarkably, the abnormality incidence of both deep Q-waves and low RV5 + SV1 (R-wave V5 + S-wave V1) were significantly high in adolescent patients. Although the patterns or positions of dystrophin gene mutations were compared with electrocardiogram abnormalities, no predisposing mutation was disclosed. These results indicate that electrocardiogram abnormalities in Duchenne muscular dystrophy are a result of dystrophin deficiency, regardless of types of gene mutations. The disease can be divided into two types: age-dependent and age-independent. Deep Q-waves and low RV5 + SV1 are proposed as markers of age-dependent cardiac complications.
Patients with Duchenne muscular dystrophy (DMD) have a progressive dilated cardiomyopathy associated with fatal cardiac arrhythmias. Electrical and functional abnormalities have been attributed to cardiac fibrosis; however, electrical abnormalities may occur in the absence of overt cardiac histopathology. Here we show that structural and functional remodeling of the cardiac sarcoplasmic reticulum (SR) Ca(2+) release channel/ryanodine receptor (RyR2) occurs in the mdx mouse model of DMD. RyR2 from mdx hearts were S-nitrosylated and depleted of calstabin2 (FKBP12.6), resulting in "leaky" RyR2 channels and a diastolic SR Ca(2+) leak. Inhibiting the depletion of calstabin2 from the RyR2 complex with the Ca(2+) channel stabilizer S107 ("rycal") inhibited the SR Ca(2+) leak, inhibited aberrant depolarization in isolated cardiomyocytes, and prevented arrhythmias in vivo. This suggests that diastolic SR Ca(2+) leak via RyR2 due to S-nitrosylation of the channel and calstabin2 depletion from the channel complex likely triggers cardiac arrhythmias. Normalization of the RyR2-mediated diastolic SR Ca(2+) leak prevents fatal sudden cardiac arrhythmias in DMD.
Evidence
2:
Inferred from Sequence or Structural SimilarityBHF-UCL
Duchenne muscular dystrophy is characterized by progressive muscle weakness and early death resulting from dystrophin deficiency. Loss of dystrophin results in disruption of a large dystrophin glycoprotein complex, leading to pathological calcium (Ca2+)-dependent signals that damage muscle cells. We have identified a structural and functional defect in the ryanodine receptor (RyR1), a sarcoplasmic reticulum Ca2+ release channel, in the mdx mouse model of muscular dystrophy that contributes to altered Ca2+ homeostasis in dystrophic muscles. RyR1 isolated from mdx skeletal muscle showed an age-dependent increase in S-nitrosylation coincident with dystrophic changes in the muscle. RyR1 S-nitrosylation depleted the channel complex of FKBP12 (also known as calstabin-1, for calcium channel stabilizing binding protein), resulting in 'leaky' channels. Preventing calstabin-1 depletion from RyR1 with S107, a compound that binds the RyR1 channel and enhances the binding affinity of calstabin-1 to the nitrosylated channel, inhibited sarcoplasmic reticulum Ca2+ leak, reduced biochemical and histological evidence of muscle damage, improved muscle function and increased exercise performance in mdx mice. On the basis of these findings, we propose that sarcoplasmic reticulum Ca2+ leak via RyR1 due to S-nitrosylation of the channel and calstabin-1 depletion contributes to muscle weakness in muscular dystrophy, and that preventing the RyR1-mediated sarcoplasmic reticulum Ca2+ leak may provide a new therapeutic approach.
Any process that modulates the rate, frequency or extent of release of sequestered calcium ion into cytosol by the sarcoplasmic reticulum, the process in which the release of sequestered calcium ion by sarcoplasmic reticulum into cytosol occurs via calcium release channels.
Evidence
1:
Inferred from Sequence or Structural SimilarityBHF-UCL
Patients with Duchenne muscular dystrophy (DMD) have a progressive dilated cardiomyopathy associated with fatal cardiac arrhythmias. Electrical and functional abnormalities have been attributed to cardiac fibrosis; however, electrical abnormalities may occur in the absence of overt cardiac histopathology. Here we show that structural and functional remodeling of the cardiac sarcoplasmic reticulum (SR) Ca(2+) release channel/ryanodine receptor (RyR2) occurs in the mdx mouse model of DMD. RyR2 from mdx hearts were S-nitrosylated and depleted of calstabin2 (FKBP12.6), resulting in "leaky" RyR2 channels and a diastolic SR Ca(2+) leak. Inhibiting the depletion of calstabin2 from the RyR2 complex with the Ca(2+) channel stabilizer S107 ("rycal") inhibited the SR Ca(2+) leak, inhibited aberrant depolarization in isolated cardiomyocytes, and prevented arrhythmias in vivo. This suggests that diastolic SR Ca(2+) leak via RyR2 due to S-nitrosylation of the channel and calstabin2 depletion from the channel complex likely triggers cardiac arrhythmias. Normalization of the RyR2-mediated diastolic SR Ca(2+) leak prevents fatal sudden cardiac arrhythmias in DMD.
Any process that modulates the activity of a ryanodine-sensitive calcium-release channel. The ryanodine-sensitive calcium-release channel catalyzes the transmembrane transfer of a calcium ion by a channel that opens when a ryanodine class ligand has been bound by the channel complex or one of its constituent parts.
Evidence
1:
Inferred from Sequence or Structural SimilarityBHF-UCL
Patients with Duchenne muscular dystrophy (DMD) have a progressive dilated cardiomyopathy associated with fatal cardiac arrhythmias. Electrical and functional abnormalities have been attributed to cardiac fibrosis; however, electrical abnormalities may occur in the absence of overt cardiac histopathology. Here we show that structural and functional remodeling of the cardiac sarcoplasmic reticulum (SR) Ca(2+) release channel/ryanodine receptor (RyR2) occurs in the mdx mouse model of DMD. RyR2 from mdx hearts were S-nitrosylated and depleted of calstabin2 (FKBP12.6), resulting in "leaky" RyR2 channels and a diastolic SR Ca(2+) leak. Inhibiting the depletion of calstabin2 from the RyR2 complex with the Ca(2+) channel stabilizer S107 ("rycal") inhibited the SR Ca(2+) leak, inhibited aberrant depolarization in isolated cardiomyocytes, and prevented arrhythmias in vivo. This suggests that diastolic SR Ca(2+) leak via RyR2 due to S-nitrosylation of the channel and calstabin2 depletion from the channel complex likely triggers cardiac arrhythmias. Normalization of the RyR2-mediated diastolic SR Ca(2+) leak prevents fatal sudden cardiac arrhythmias in DMD.
Duchenne muscular dystrophy is characterized by progressive muscle weakness and early death resulting from dystrophin deficiency. Loss of dystrophin results in disruption of a large dystrophin glycoprotein complex, leading to pathological calcium (Ca2+)-dependent signals that damage muscle cells. We have identified a structural and functional defect in the ryanodine receptor (RyR1), a sarcoplasmic reticulum Ca2+ release channel, in the mdx mouse model of muscular dystrophy that contributes to altered Ca2+ homeostasis in dystrophic muscles. RyR1 isolated from mdx skeletal muscle showed an age-dependent increase in S-nitrosylation coincident with dystrophic changes in the muscle. RyR1 S-nitrosylation depleted the channel complex of FKBP12 (also known as calstabin-1, for calcium channel stabilizing binding protein), resulting in 'leaky' channels. Preventing calstabin-1 depletion from RyR1 with S107, a compound that binds the RyR1 channel and enhances the binding affinity of calstabin-1 to the nitrosylated channel, inhibited sarcoplasmic reticulum Ca2+ leak, reduced biochemical and histological evidence of muscle damage, improved muscle function and increased exercise performance in mdx mice. On the basis of these findings, we propose that sarcoplasmic reticulum Ca2+ leak via RyR1 due to S-nitrosylation of the channel and calstabin-1 depletion contributes to muscle weakness in muscular dystrophy, and that preventing the RyR1-mediated sarcoplasmic reticulum Ca2+ leak may provide a new therapeutic approach.
Any process that modulates the frequency, rate or extent of skeletal muscle contraction via the regulation of the release of sequestered calcium ion by sarcoplasmic reticulum into cytosol. The sarcoplasmic reticulum is the endoplasmic reticulum of striated muscle, specialised for the sequestration of calcium ions that are released upon receipt of a signal relayed by the T tubules from the neuromuscular junction.
Evidence
1:
Inferred from Sequence or Structural SimilarityBHF-UCL
Duchenne muscular dystrophy is characterized by progressive muscle weakness and early death resulting from dystrophin deficiency. Loss of dystrophin results in disruption of a large dystrophin glycoprotein complex, leading to pathological calcium (Ca2+)-dependent signals that damage muscle cells. We have identified a structural and functional defect in the ryanodine receptor (RyR1), a sarcoplasmic reticulum Ca2+ release channel, in the mdx mouse model of muscular dystrophy that contributes to altered Ca2+ homeostasis in dystrophic muscles. RyR1 isolated from mdx skeletal muscle showed an age-dependent increase in S-nitrosylation coincident with dystrophic changes in the muscle. RyR1 S-nitrosylation depleted the channel complex of FKBP12 (also known as calstabin-1, for calcium channel stabilizing binding protein), resulting in 'leaky' channels. Preventing calstabin-1 depletion from RyR1 with S107, a compound that binds the RyR1 channel and enhances the binding affinity of calstabin-1 to the nitrosylated channel, inhibited sarcoplasmic reticulum Ca2+ leak, reduced biochemical and histological evidence of muscle damage, improved muscle function and increased exercise performance in mdx mice. On the basis of these findings, we propose that sarcoplasmic reticulum Ca2+ leak via RyR1 due to S-nitrosylation of the channel and calstabin-1 depletion contributes to muscle weakness in muscular dystrophy, and that preventing the RyR1-mediated sarcoplasmic reticulum Ca2+ leak may provide a new therapeutic approach.
Duchenne muscular dystrophy (DMD), caused by mutations in the dystrophin gene, is associated with severe cardiac complications including cardiomyopathy and cardiac arrhythmias. Recent research suggests that impaired voltage-gated ion channels in dystrophic cardiomyocytes accompany cardiac pathology. It is, however, unknown if the ion channel defects are primary effects of dystrophic gene mutations, or secondary effects of the developing cardiac pathology.
The DMD gene is the largest known gene in humans. It is 2.4 million base-pairs in size, comprises 79 exons and takes over 16 hours to be transcribed and cotranscriptionally spliced.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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