calpain and Muscular-Dystrophy--Duchenne

Although the exact nature of the relationship between calcium and the pathogenesis of Duchenne muscular dystrophy (DMD) is not fully understood, this is an important issue which has been addressed in several recent reviews (Alderton and Steinhardt, 2000a, Gailly, 2002, Allen et al., 2005). A key question when trying to understand the cellular basis of DMD is how the absence or low level of expression of dystrophin, a cytoskeletal protein, results in the slow but progressive necrosis of muscle fibres. Although loss of cytoskeletal and sarcolemmal integrity which results from the absence of dystrophin clearly plays a key role in the pathogenesis associated with DMD, a number of lines of evidence also establish a role for misregulation of calcium ions in the DMD pathology, particularly in the cytoplasmic space just under the sarcolemma. A number of calcium-permeable channels have been identified which can exhibit greater activity in dystrophic muscle cells, and exIsting evidence suggests that these may represent different variants of the same channel type (perhaps the transient receptor potential channel, TRPC). In addition, a prominent role for calcium-activated proteases in the DMD pathology has been established, as well as modulation of other intracellular regulatory proteins and signaling pathways. Whether dystrophin and its associated proteins have a direct role in the regulation of calcium ions, calcium channels or intracellular calcium stores, or indirectly alters calcium regulation through enhancement of membrane tearing, remains unclear. Here we focus on areas of consensus or divergence amongst the existing literature, and propose areas where future research would be especially valuable.

Topics: Animals; Calcium; Calcium Channels; Calpain; Dystrophin; Humans; Muscle, Skeletal; Muscular Dystrophy, Animal; Muscular Dystrophy, Duchenne; Sarcolemma

Skeletal muscle is the largest single organ of the body. Skeletal muscle damage may lead to loss of muscle function, and widespread muscle damage may have serious systemic implications due to leakage of intracellular constituents to the circulation. Ca2+ acts as a second messenger in all muscle and may activate a whole range of processes ranging from activation of contraction to degradation of the muscle cell. It is therefore of vital importance for the muscle cell to control [Ca2+] in the cytoplasm ([Ca2+]c). If the permeability of the sarcolemma for Ca2+ is increased, the muscle cell may suffer Ca2+ overload, defined as an inability to control [Ca2+]c. This could lead to the activation of calpains, resulting in proteolysis of cellular constituents, activation of phospholipase A2 (PLA2), affecting membrane integrity, an increased production of reactive oxygen species (ROS), causing lipid peroxidation, and possibly mitochondrial Ca2+ overload, all of which may further worsen the damage in a self-reinforcing process. An increased influx of Ca2+ leading to Ca2+ overload in muscle may occur in a range of situations such as exercise, mechanical and electrical trauma, prolonged ischemia, Duchenne muscular dystrophy, and cachexia. Counteractions include membrane stabilizing agents, Ca2+ channel blockers, calpain inhibitors, PLA2 inhibitors, and ROS scavengers.

Topics: Calcium; Calpain; Exercise; Humans; Ischemia; Mitochondria; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Phospholipases A; Phospholipases A2; Reactive Oxygen Species

Duchenne muscular dystrophy patients lack the protein dystrophin which is an essential link in the complex of proteins that connect the cytoskeleton to the extracellular matrix. In mechanically stressed tissues such as muscle, transient sarcolemmal microdisruptions are normal, but in dystrophic muscle cells the frequency of these microdisruptions is greatly increased. Although both normal and dystrophic cells are able to actively repair these microdisruptions, calcium entry through the more frequent sarcolemmal microdisruptions of dystrophic cells results in an increased calcium-dependent proteolysis that alters the activity of the calcium leak channel. The accumulation of abnormally active calcium leak channels over time results in a gradual loss of calcium homeostasis and eventual cell death.

Topics: Animals; Calcium; Calcium Channels; Calpain; Cells, Cultured; Cytoplasm; Dystrophin; Homeostasis; Humans; Hydrolysis; Muscle Fibers, Skeletal; Muscle Proteins; Muscular Dystrophy, Duchenne; Sarcolemma

Duchenne muscular dystrophy (DMD) is a devastating genetic disorder that leads to compromised cellular membranes, caused by the absence of membrane-bound dystrophin protein. Muscle membrane leakage results in disrupted intracellular homeostasis, protein degradation, and muscle wasting. Improving muscle membrane integrity may delay disease progression and extend the lifespan of DMD patients. Here, we demonstrate that exosomes, membranous extracellular vesicles, can elicit functional improvements in dystrophic mice by improving muscle membrane integrity. Systemic administration of exosomes from different sources induced phenotypic rescue and mitigated pathological progression in dystrophic mice without detectable toxicity. Improved membrane integrity conferred by exosomes inhibited intracellular calcium influx and calcium-dependent activation of calpain proteases, preventing the degradation of the destabilized dystrophin-associated protein complex. We show that exosomes, particularly myotube-derived exosomes, induced functional improvements and alleviated muscle deterioration by stabilizing damaged muscle membrane in dystrophic mice. Our findings suggest that exosomes may have therapeutic implications for DMD and other diseases with compromised membranes.

Topics: Animals; Calcium; Calpain; Cell Membrane; Disease Models, Animal; Dystrophin; Exosomes; Humans; Mice; Mice, Inbred mdx; Muscle Fibers, Skeletal; Muscle, Skeletal; Muscular Dystrophy, Animal; Muscular Dystrophy, Duchenne; Peptide Hydrolases

Duchenne muscular dystrophy (DMD) induces sarcolemmal mechanical instability and rupture, hyperactivity of intracellular calpains, and proteolytic breakdown of muscle structural proteins. Here we identify the two sarcomeric tropomodulin (Tmod) isoforms, Tmod1 and Tmod4, as novel proteolytic targets of m-calpain, with Tmod1 exhibiting ∼10-fold greater sensitivity to calpain-mediated cleavage than Tmod4 in situ. In mdx mice, increased m-calpain levels in dystrophic soleus muscle are associated with loss of Tmod1 from the thin filament pointed ends, resulting in ∼11% increase in thin filament lengths. In mdx/mTR mice, a more severe model of DMD, Tmod1 disappears from the thin filament pointed ends in both tibialis anterior (TA) and soleus muscles, whereas Tmod4 additionally disappears from soleus muscle, resulting in thin filament length increases of ∼10 and ∼12% in TA and soleus muscles, respectively. In both mdx and mdx/mTR mice, both TA and soleus muscles exhibit normal localization of α-actinin, the nebulin M1M2M3 domain, Tmod3, and cytoplasmic γ-actin, indicating that m-calpain does not cause wholesale proteolysis of other sarcomeric and actin cytoskeletal proteins in dystrophic skeletal muscle. These results implicate Tmod proteolysis and resultant thin filament length misspecification as novel mechanisms that may contribute to DMD pathology, affecting muscles in a use- and disease severity-dependent manner.

Topics: Actin Cytoskeleton; Actinin; Actins; Animals; Calpain; Disease Models, Animal; Mice; Mice, Inbred mdx; Muscle Proteins; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Protein Structure, Tertiary; Proteolysis; Tropomodulin

Duchenne muscular dystrophy (DMD) is a neuromuscular-degenerative fatal disorder caused by mutations in the dystrophin gene. The incidence rate is one in 3300 live male births in every part of the world. A study into the detection of true carriers of DMD has been performed using gene deletion and non-deletion cases to devise a reliable and cost-effective diagnosis of DMD. The study uses a sample of 130 people (70 males and 60 females), consisting of 105 risk patients (60 male and 45 female) and 25 patients from normal carrying families, analyzed by CPK, M-PCR, Q-PCR and STR. This study aims to perform diagnosis of non-deletional and true carriers of DMD by enzyme-linked immunosorbent assay (ELISA), assessing the amount of m-calpain in the platelets of participants. In order to diagnose DMD patients, true carriers and controls, an ELISA has been standardized using polyclonal antibodies raised against m-calpain purified from human placenta. From the sample group, 45 at risk females were analyzed for m-calpain by quantitative ELISA. It was found that 90% of tests were informative, showing enhanced levels of m-calpain when compared to controls. The quantitative ELISA has proved to be an accurate, reliable, rapid and cost-effective test for DMD patients and true carriers, and also useful for the prenatal diagnosis.

Topics: Blood Platelets; Calpain; Carrier State; DNA; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Microsatellite Repeats; Muscular Dystrophy, Duchenne; Pedigree; Polymerase Chain Reaction; Polymorphism, Genetic

Limb girdle muscular dystrophy (LGMD) type 2A is caused by mutations in the CAPN3 gene and complete lack of functional calpain 3 leads to the most severe muscle wasting. Calpain 3 is suggested to be involved in maturation of contractile elements after muscle degeneration. The aim of this study was to investigate how mutations in the four functional domains of calpain 3 affect muscle regeneration.. We studied muscle regeneration in 22 patients with LGMD2A with calpain 3 deficiency, in five patients with LGMD2I, with a secondary reduction in calpain 3, and in five patients with Becker muscular dystrophy (BMD) with normal calpain 3 levels. Regeneration was assessed by using the developmental markers neonatal myosin heavy chain (nMHC), vimentin, MyoD and myogenin and counting internally nucleated fibers.. We found that the recent regeneration as determined by the number of nMHC/vimentin-positive fibers was greatly diminished in severely affected LGMD2A patients compared to similarly affected patients with LGMD2I and BMD. Whorled fibers, a sign of aberrant regeneration, was highly elevated in patients with a complete lack of calpain 3 compared to patients with residual calpain 3. Regeneration is not affected by location of the mutation in the CAPN3 gene.. Our findings suggest that calpain 3 is needed for the regenerative process probably during sarcomere remodeling as the complete lack of functional calpain 3 leads to the most severe phenotypes.

Topics: Adolescent; Adult; Apoptosis; Biomarkers; Biopsy; Blotting, Western; Calpain; Denmark; Dystrophin; Female; Genetic Predisposition to Disease; Humans; Immunohistochemistry; Linear Models; Male; Middle Aged; Muscle Proteins; Muscle, Skeletal; Muscular Dystrophies, Limb-Girdle; Muscular Dystrophy, Duchenne; Mutation; MyoD Protein; Myogenin; Myosin Heavy Chains; Pentosyltransferases; Phenotype; Proteins; Regeneration; Severity of Illness Index; Vimentin; Young Adult

Calpain-3, a Ca [2]+ -dependent protease has been implicated in the pathology of neuromuscular disorders (NMDs). The current study aimed to analyze calpain-3 expression in cases diagnosed as muscular dystrophy from the Indian population.. Calpain-3 Western blot analysis in muscle biopsies of immunohistochemically confirmed cases of Duchenne muscular dystrophy (DMD) (n=10), dysferlinopathy (n=30) and sarcoglycanopathy (n=8) was carried out. Calpain-3 Western blotting was also used in a blinded study to identify cases of calpain-3 deficiency in 28 NMD patients with potential muscular dystrophy.. Calpain-3 appeared as a full length 94 kDa band with an autolytic product (~60 kDa) on Western blots with antibody NCL-CALP-12A2 (Ab-2). Eight of the 10 DMD samples showed absence of 94 kDa band but presence of 60 kDa band while one case of sarcoglycanopathy showed absence of both. Twenty one of the 30 dysferlinopathy samples showed both bands while six showed only the 60 kDa band and three showed absence of both. In the blinded study, five NMD cases with potential muscular dystrophy that showed complete absence of both bands in retrospect exhibited clinical features of limb girdle muscular dystrophy 2A (LGMD2A).. While the study revealed a consistent pattern of calpain-3 in DMD, one sarcoglycanopathy and three dysferlinopathy samples exhibited secondary reduction in calpain-3. It was recognized that both calpain-3 bands should be considered to confirm calpain deficiency. Further, western blot offers an economical and fast preliminary screening method for LGMD2A especially in cases of complete absence of calpain-3 prior to conclusive diagnosis by genetic testing.

Topics: Adolescent; Adult; Calpain; Child; Child, Preschool; Female; Gene Expression; Humans; India; Infant; Male; Middle Aged; Muscle Proteins; Muscle, Skeletal; Muscular Dystrophies, Limb-Girdle; Muscular Dystrophy, Duchenne; Sarcoglycanopathies

Calpain activation has been implicated in the disease pathology of Duchenne muscular dystrophy. Inhibition of calpain has been proposed as a promising therapeutic target, which could lessen the protein degradation and prevent progressive fibrosis. At the same time, there are conflicting reports as to whether elevation of calpastatin, an endogenous calpain inhibitor, alters pathology. We compared the effects of pharmacological calpain inhibition in the mdx mouse using leupeptin and a proprietary compound (C101) that linked the inhibitory portion of leupeptin to carnitine (to increase uptake into muscle). Administration of C101 for 4 wk did not improve muscle histology, function, or serum creatine kinase levels in mdx mice. Mdx mice injected daily with leupeptin (36 mg/kg) for 6 mo also failed to show improved muscle function, histology, or creatine kinase levels. Biochemical analysis revealed that leupeptin administration caused an increase in m-calpain autolysis and proteasome activity, yet calpastatin levels were similar between treated and untreated mdx mice. These data demonstrate that pharmacological inhibition of calpain is not a promising intervention for the treatment of Duchenne muscular dystrophy due to the ability of skeletal muscle to counter calpain inhibitors by increasing multiple degradative pathways.

Topics: Animals; Biomarkers; Calcium-Binding Proteins; Calpain; Creatine Kinase; Cysteine Proteinase Inhibitors; Diaphragm; Disease Models, Animal; Dose-Response Relationship, Drug; Genotype; Leupeptins; Mice; Mice, Inbred mdx; Muscle Contraction; Muscle Strength; Muscular Dystrophy, Duchenne; Necrosis; Phenotype; Proteasome Endopeptidase Complex; Time Factors

Dystrophin deficiency is the underlying molecular cause of progressive muscle weakness observed in Duchenne muscular dystrophy (DMD). Loss of functional dystrophin leads to elevated levels of intracellular Ca(2+), a key step in the cellular pathology of DMD. The cysteine protease calpain is activated in dystrophin-deficient muscle, and its inhibition is regarded as a potential therapeutic approach. In addition, previous work has shown that the ubiquitin-proteasome system also contributes to muscle protein breakdown in dystrophic muscle and, therefore, also qualifies as a potential target for therapeutic intervention in DMD. The relative contribution of calpain- and proteasome-mediated proteolysis induced by increased Ca(2+) levels was characterized in cultured muscle cells and revealed initial Ca(2+) influx-dependent calpain activity and subsequent Ca(2+)-independent activity of the ubiquitin-proteasome system. We then set out to optimize novel small-molecule inhibitors that inhibit both calpain as well as the 20S proteasome in a cellular system with impaired Ca(2+) homeostasis. On administration of such inhibitors to mdx mice, quantitative histological parameters improved significantly, in particular with compounds strongly inhibiting the 20S proteasome. To investigate the role of calpain inhibition without interfering with the ubiquitin-proteasome system, we crossed mdx mice with transgenic mice, overexpressing the endogenous calpain inhibitor calpastatin. Although our data show that proteolysis by calpain is strongly inhibited in the transgenic mdx mouse, this calpain inhibition did not ameliorate muscle histology. Our results indicate that inhibition of the proteasome rather than calpain is required for histological improvement of dystrophin-deficient muscle. In conclusion, we have identified novel proteasome inhibitors that qualify as potential candidates for pharmacological intervention in muscular dystrophy.

Topics: Animals; Calcium; Calcium-Binding Proteins; Calpain; Cells, Cultured; Humans; Mice; Mice, Inbred mdx; Mice, Transgenic; Muscles; Muscular Dystrophy, Duchenne; Myoblasts; Oligopeptides; Protease Inhibitors; Proteasome Inhibitors

Calpains are Ca(2+)-activated proteases that are thought to be involved in muscle degenerative diseases such as Duchenne muscular dystrophy. Status and activity of calpains in adult muscle fibres are poorly documented. We report here in situ measurements of calpain activity in collagenase-isolated fibres from C57 mice and form two models of dystrophy: dystrophin-deficient mdx and calpain-3 knocked-out mice. Calpain activity was measured using a permeant, fluorogenic substrate and its Ca(2+) dependence was studied. A 30-fold change of activity was observed between the lowest and the highest steady-state Ca(2+) availability. Fast transient changes of [Ca(2+)](i) induced by electrical stimulation or KCl-dependent depolarization were ineffective in activating calpain. Slow [Ca(2+)] transients, as elicited during depletion of Ca(2+) stores, Ca(2+) store repletion and hypo-osmotic swelling were able to activate calpain. On return to resting conditions, calpain activity recovered its basal rate within 10 min. In resting intact muscle, mu-calpain was predominantly in the 80 kDa native form, with a small fraction in the 78 kDa autolysed form. The latter is thought to be responsible for the activity measured in our conditions. Calpain activity in mdx fibres showed an average 1.5-fold increase compared to activity in C57 fibres. This activity was reduced by a 10-fold lowering of [Ca(2+)](o). Calpain-3-deficient fibres showed about the same increase, thus calpain-3 did not contribute to the activity measured here and calpain activation is not specific to dystrophin deficiency. In fibres from transgenic mice over-expressing calpastatin, a 40-50% reduction of calpain activity was observed, as with synthetic drugs (Z-Leu-Leu-CHO and SNT198438). We provide novel information on the physiological factors that control calpain activity in situ, particularly the effect of intracellular Ca(2+) transients that occur in excitation-contraction coupling, Ca(2+) store depletion and refilling, and activation of mechanosensitive Ca(2+) channels.

Topics: Animals; Caffeine; Calcium; Calpain; Dystrophin; Electric Stimulation; Kinetics; Mice; Mice, Inbred C57BL; Mice, Inbred mdx; Muscle Fibers, Skeletal; Muscle Proteins; Muscle, Skeletal; Muscular Dystrophy, Duchenne

Muscular dystrophies are composed of a variety of genetic muscle disorders linked to different chromosomes and loci and associated with different gene mutations that lead to progressive muscle atrophy and weakness. Fukuyama congenital muscular dystrophy is frequently associated with partial and generalized epilepsy and congenital brain anomalies, including cobblestone complex and other neuronal migration defects. We report generalized convulsive epilepsy in a boy with normal brain magnetic resonance imaging and Duchenne muscular dystrophy with deletion of dystrophin gene, and we report absence epilepsy with normal brain magnetic resonance imaging in another boy with limb girdle muscular dystrophy with partial calpain deficiency. We, therefore, review coexisting muscular dystrophies and epilepsy in children. In addition to Fukuyama congenital muscular dystrophy, partial or generalized epilepsy has also been reported in the following types of muscular dystrophies, including Duchenne/Becker dystrophy, facioscapulohumeral dystrophy, congenital muscular dystrophy with partial and complete deficiency of laminin alpha2 (merosin) chain, and limb girdle muscular dystrophy with partial calpain deficiency.

Topics: Brain; Calpain; Child; Chromosome Deletion; Diagnosis, Differential; Dystrophin; Epilepsy, Generalized; Epilepsy, Tonic-Clonic; Follow-Up Studies; Humans; Magnetic Resonance Imaging; Male; Muscular Dystrophies, Limb-Girdle; Muscular Dystrophy, Duchenne; Neurologic Examination

Calpains are Ca2+ -dependent cytosolic cysteine proteases that participate in the pathology of Duchenne muscular dystrophy (DMD). Utrophin is a functional homolog of dystrophin that partially compensates for dystrophin deficiency in myofibers of mdx mice. In this study, we investigated the susceptibility of utrophin to cleavage by calpain in vitro and in muscle cells. We found that utrophin is a direct in vitro substrate of purified calpain I and II. Cleavage of utrophin by calpain I or II generates specific degradation products that are also found in cultured control and DMD myotubes under conditions with elevated intracellular Ca2+ levels. In addition, we showed that activation of cellular calpains by Ca2+ ionophore treatment reduces utrophin protein levels in muscle cells and that calpain inhibition prevents this Ca2+ -induced reduction in utrophin levels. These observations suggest that, beside its known effect on general muscle protein degradation, calpain contributes to DMD pathology by specifically degrading the compensatory protein utrophin.

Topics: Animals; Calpain; Cells, Cultured; Enzyme Inhibitors; Gene Expression; Humans; In Vitro Techniques; Ionophores; Kidney; Mice; Muscle Cells; Muscle Fibers, Skeletal; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Substrate Specificity; Utrophin

Calpain II is an calcium-dependent cysteine protease involved in essential regulatory or processing functions of the cell, mediated by physiological concentrations of Ca(2+). However, in an environment of abnormal intracellular calcium as in Duchenne muscular dystrophy (DMD), calpain is suggested to cause membrane alterations.. Twelve individuals with dystrophin gene deletion and an equal number of age and sex matched controls were chosen for the study. The expression pattern of calpain II (both at RNA and protein levels), its cellular location upon activation and its activity in lymphocytes were specifically assessed to know if our earlier report of increased calpain activity in DMD lymphocytes is a result of de novo synthesis or is due to basic defect in calcium handling.. We found a significant increase in the expression, alteration in calpain II distribution and increased activity of this enzyme.. Membrane abnormalities and altered signaling pathways observed in DMD lymphocytes may be due to increased association of calpain II onto membrane and cytosol.

Topics: Calpain; Cell Membrane; Cytosol; Gene Expression Profiling; Gene Expression Regulation, Enzymologic; Humans; Lymphocytes; Muscular Dystrophy, Duchenne; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Subcellular Fractions

To clarify the involvement of calpains in sarcolemmal remodeling, we examined the expression of calpains and their substrate, alpha-fodrin, in various disorders of muscle. Although immunohistological reactions for alpha-fodrin and calpains were weak in normal control muscles, intense immunoreactivity for alpha-fodrin at the sarcolemma and for calpains throughout the cytoplasm were detected in small muscle fibers from patients with inflammatory myositis (IM), rhabdomyolysis (Rhab), and Duchenne muscular dystrophy (DMD). Most of the calpain-alpha-fodrin double-positive muscle fibers in IM and Rhab also expressed the developmental form of myosin heavy chain. The sarcolemma of these small muscle fibers reacted with an antibody that specifically recognizes the 150-kDa fragments of alpha-fodrin (SBDP 150s) cleaved by calpain, but not caspase 3. Western blot analysis confirmed these results. These observations indicate that calpain is activated and reacts with alpha-fodrin as a substrate at the sarcolemma, and plays a key role in modulating sarcolemmal proteins to adapt to the specific conditions in each myopathy.

Topics: Adult; Aged; Antibody Specificity; Calpain; Carrier Proteins; Child; Child, Preschool; Female; Humans; Immunohistochemistry; Male; Microfilament Proteins; Middle Aged; Muscle, Skeletal; Muscular Diseases; Muscular Dystrophy, Duchenne; Myosin Heavy Chains; Myositis; Peptide Fragments; Rhabdomyolysis; Sarcolemma

Topics: Alleles; Calpain; Diagnosis, Differential; DNA Mutational Analysis; Female; Gene Frequency; Genetic Testing; Humans; Isoenzymes; Male; Muscle Proteins; Muscular Atrophy, Spinal; Muscular Dystrophies, Limb-Girdle; Muscular Dystrophy, Duchenne; Mutation; Mutation, Missense; Polymorphism, Genetic; Sequence Deletion

Topics: Animals; Calpain; Humans; Insulin-Like Growth Factor I; Muscle Development; Muscular Dystrophy, Duchenne; Myostatin; Transforming Growth Factor beta

NG2 is the rat homologue of the human melanoma chondroitin sulfate proteoglycan (MCSP) preferentially expressed in dividing progenitor cells of the glial and mesenchymal lineage but downregulated after differentiation. It has recently been demonstrated that MCSP/NG2 expression is not restricted to mitotic or malignant cells. We show that MCSP/NG2 expression is detectable in the sarcolemma, and in the neuromuscular junction of human postnatal skeletal muscle, and it gradually reduces with advancing age. In human and murine myogenic cell lines, we found no clear differences in MCSP/NG2 expression between myoblasts and myotubes. Reduced levels of the core protein were found in merosin-negative congenital muscular dystrophy (MDC1A). Duchenne muscular dystrophy patients muscles exhibited an overexpression of the MCSP/NG2 core protein. In gamma-sarcoglycanopathy and calpainopathy, MCSP/NG2 upregulation was restricted to regenerating myofibers. We demonstrate that MCSP/NG2 is expressed in differentiated myofibers, and appears to have a role in the pathogenesis of MDC1A and severe dystrophinopathies.

Topics: Adolescent; Adult; Aging; Animals; Antigens; Calpain; Cell Differentiation; Child; Child, Preschool; Chondroitin Sulfate Proteoglycans; Cytoskeletal Proteins; Down-Regulation; Gene Expression Regulation, Developmental; Humans; Infant; Infant, Newborn; Membrane Glycoproteins; Membrane Proteins; Mice; Middle Aged; Muscle Fibers, Skeletal; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Myoblasts; Neuromuscular Junction; Proteoglycans; Sarcoglycans; Sarcolemma; Tumor Cells, Cultured

Inhibition of muscle degeneration by the tripeptide calpain inhibitor, leupeptin, was tested in vivo in a dystrophin-deficient mdx murine model. In a short-term control study, intramuscular administration of leupeptin for 30 days inhibited muscle degeneration as assessed by histologic analysis. Calpain inhibition could be correlated with retention of myofiber size and our results suggest that this may be a promising treatment modality in human Duchenne muscular dystrophy.

Topics: Animals; Calpain; Cysteine Proteinase Inhibitors; Histocytochemistry; Leupeptins; Male; Mice; Mice, Inbred C57BL; Mice, Inbred mdx; Microscopy, Electron; Muscle Fibers, Skeletal; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Necrosis