Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026850 (muscular dystrophy)
 5,870 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calpain 3 is known as the skeletal muscle-specific member of the calpains, a family of intracellular nonlysosomal cysteine proteases. It was previously shown that defects in the human calpain 3 gene are responsible for limb girdle muscular dystrophy type 2A (LGMD2A), an inherited disease affecting predominantly the proximal limb muscles. To better understand the function of calpain 3 and the pathophysiological mechanisms of LGMD2A and also to develop an adequate model for therapy research, we generated capn3-deficient mice by gene targeting. capn3-deficient mice are fully fertile and viable. Allele transmission in intercross progeny demonstrated a statistically significant departure from Mendel's law. capn3-deficient mice show a mild progressive muscular dystrophy that affects a specific group of muscles. The age of appearance of myopathic features varies with the genetic background, suggesting the involvement of modifier genes. Affected muscles manifest a similar apoptosis-associated perturbation of the IkappaBalpha/nuclear factor kappaB pathway as seen in LGMD2A patients. In addition, Evans blue staining of muscle fibers reveals that the pathological process due to calpain 3 deficiency is associated with membrane alterations.
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PMID:Loss of calpain 3 proteolytic activity leads to muscular dystrophy and to apoptosis-associated IkappaBalpha/nuclear factor kappaB pathway perturbation in mice. 1113 85

The ex vivo effects of passive mechanical stretch on the activation of nuclear factor-kappaB (NF-kappaB) pathways in skeletal muscles from normal and mdx mouse, a model of Duchenne muscular dystrophy (DMD), were investigated. The NF-kappaB/DNA binding activity of the diaphragm muscle was increased by the application of axial mechanical stretch in a time-dependent manner. The increased activation of NF-kappaB was associated with a concomitant increase in I-kappaB (IkappaB) kinase activity and the degradation of IkappaBalpha protein. Pretreatment of the muscles with nifedipine (a Ca2+ channel blocker) and gadolinium(III) chloride (a stretch-activated channel blocker) did not alter the level of activation of NF-kappaB, ruling out involvement of Ca2+ influx through these channels. Furthermore, N-acetyl cysteine, a free radical inhibitor, blocked the mechanical stretch-induced NF-kappaB activation, suggesting the involvement of free radicals. Compared with normal diaphragm, the basal level of NF-kappaB activity was higher in muscles from mdx mice, and it was further enhanced in mechanically stretched muscles. Furthermore, activation of NF-kappaB and increased expression of inflammatory cytokines IL-1beta and tumor necrosis factor alpha in the mdx mouse precede the onset of muscular dystrophy. Our results show that mechanical stretch activates the classical NF-kappaB pathway and this pathway could be predominately active in DMD.
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PMID:Mechanical stress activates the nuclear factor-kappaB pathway in skeletal muscle fibers: a possible role in Duchenne muscular dystrophy. 1263 78

The limb-girdle muscular dystrophies are a diverse group of muscle-wasting disorders characteristically affecting the large muscles of the pelvic and shoulder girdles. Molecular genetic analyses have demonstrated causative mutations in the genes encoding a disparate collection of proteins involved in all aspects of muscle cell biology. Muscular dystrophy includes a spectrum of disorders caused by loss of the linkage between the extracellular matrix and the actin cytoskeleton. Within this are the forms of limb-girdle muscular dystrophy caused by deficiencies of the sarcoglycan complex and by aberrant glycosylation of alpha-dystroglycan caused by mutations in the fukutin-related protein gene. However, other forms of this disease have distinct pathophysiological mechanisms. For example, deficiency of dysferlin disrupts sarcolemmal membrane repair, whilst loss of calpain-3 may exert its pathological influence either by perturbation of the IkappaBalpha/NF-kappaB pathway, or through calpain-dependent cytoskeletal remodelling. Caveolin-3 is implicated in numerous cell-signalling pathways and involved in the biogenesis of the T-tubule system. Alterations in the nuclear lamina caused by mutations in laminA/C, sarcomeric changes in titin, telethonin or myotilin at the Z-disc, and subtle changes in the extracellular matrix proteins laminin-alpha2 or collagen VI can all lead to a limb-girdle muscular dystrophy phenotype, although the specific pathological mechanisms remain obscure. Differential diagnosis of these disorders requires the careful application of a broad range of disciplines: clinical assessment, immunohistochemistry and immunoblotting using a panel of antibodies and extensive molecular genetic analyses.
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PMID:Limb-girdle muscular dystrophies--from genetics to molecular pathology. 1504 7

Defensins comprise a family of cationic antimicrobial peptides characterized by conserved cysteine residues. They are produced in various organs including skeletal muscle and are identified as key elements in the host defense system as potent effectors. At the same time, defensins have potential roles in the regulation of inflammation and, furthermore, can exert cytotoxic effects on several mammalian cells. Here, we developed transgenic mice overexpressing mouse beta-defensin-6 to explore the pathophysiological roles of the defensin family as a novel mediator of inflammatory tissue injury. Unexpectedly, the transgenic mice showed short lifespan, poor growth, and progressive myofiber degeneration with functional muscle impairment, predominant centronucleated myofibers, and elevated serum creatine kinase activity, as seen in human muscular dystrophy. Furthermore, some of the transgenic myofibers showed IkappaBalpha accumulation, which would be related to the myofiber apoptosis of limb-girdle muscular dystrophy type 2A. The present findings may unravel a concealed linkage between the innate immune system and the pathophysiology of degenerative diseases.
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PMID:Beta-defensin overexpression induces progressive muscle degeneration in mice. 1721 27