Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.22.54 (calpain 3)
 430 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Premature visual impairment due to lens opacification is a debilitating characteristic of untreated diabetes. Lens opacification is primarily due to the insolubilization of crystallins, proteins essential for lens optical properties, and recent studies have suggested that a major cause of this insolubilization may be the unregulated proteolysis of crystallins by calpains. These are intracellular cysteine proteases whose activation requires the presence of calcium (Ca2+) and elevated levels of lens Ca2+ is a condition associated with both diabetic cataractogenesis and other forms of the disorder. A number of calpains have been identified in the lens, including calpain 2, calpain 10 and two isozymes of calpain 3: Lp82 and Lp85. The use of animal hereditary cataract models have suggested that calpain 2 and/or Lp82 may be the major calpains involved in murine cataractogenesis with contributions from calpain 10 and Lp85. However, calpain 2 appears to be the major calpain involved in murine diabetic cataractogenesis and the strongest candidate of the calpains for a role in human types of cataractogenesis. Here, we present an overview of recent evidence on which these observations are based with an emphasis on the ability of calpains to proteolyse lens crystallins and calpain structural features, which appear to be involved in the Ca2+-mediated activation of these enzymes.
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PMID:Role of calpains in diabetes mellitus-induced cataractogenesis: a mini review. 1536 98

The calpains are a family of cysteine proteases with closely related amino acid sequences, but a wide range of Ca(2+) requirements (K(d)). For m-calpain, K(d) is approximately 325microM, for mu-calpain it is approximately 50microM, and for calpain 3 it is not strictly known but may be approximately 0.1microM. On the basis of previous structure determination of m-calpain we postulated that two regions of the calpain large subunits, the N-terminal peptide (residues 1-20) and a domain III-IV linker peptide (residues 514-530 in m-calpain) were important in defining K(d). The mutations Lys10Thr in the N-terminal peptide, and Glu517Pro in the domain linker peptide, reduced K(d) of m-calpain by 30% and 42%, respectively, revealing that these two regions are functionally important. The increased Ca(2+)-sensitivity of these mutants demonstrate that the Lys10-Asp148 salt link and the short beta-sheet interaction involving Glu517 are factors contributing to the high K(d) of m-calpain. Though these two regions are physically remote from the active site and Ca(2+)-binding site, they play significant roles in regulating the response of calpain to Ca(2+). Differences in these interactions in mu-calpain and in calpain 3 are also consistent with their progressively lower K(d) values.
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PMID:Activation of calpain by Ca2+: roles of the large subunit N-terminal and domain III-IV linker peptides. 1547 20

A calpain 3 (Capn3) deficiency model was created by targeted disruption of the mouse Capn3 gene through homologous recombination in ES cells. Analysis of the genotype of pups from heterozygous crosses revealed a transmission ratio distortion (TRD) in favor of homozygous Capn3-deficient mice. This TRD was not observed in a second model of Capn3 deficiency, ruling out a possible involvement of Capn3 deficiency in this phenotype. The molecular nature of the TRD was investigated by quantitative RT-PCR and RACE-PCR analyses. We observed the presence in testis and ovaries of abundant, novel transcripts of the Capn3 gene arising from the antisense strand of the Pgk1-neomycin cassette. Although we could not detect corresponding translation products, our results suggest that the activity of the Pgk1 promoter could be the causative factor of TRD. This first example of TRD induced by an introduced cassette further emphasizes the care that should be taken in interpreting phenotypes of animal models, especially when dealing with reproductive functions, and further supports the rationale of using excisable cassettes in inactivation strategies.
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PMID:Bidirectional transcriptional activity of the Pgk1 promoter and transmission ratio distortion in Capn3-deficient mice. 1549 66

Diseases due to mutations in the lamin A/C gene (LMNA) are highly heterogeneous, including neuromuscular and cardiac dystrophies, lipodystrophies, and premature ageing syndromes. In this study we characterized the neuromuscular and cardiac phenotypes of patients bearing the heterozygous LMNA R482W mutation, which is the most frequent genotype associated with the familial partial lipodystrophy of the Dunnigan type (FPLD). Fourteen patients from two unrelated families, including 10 affected subjects, were studied. The two probands had been referred for lipoatrophy and/or diabetes. Lipodystrophy, exclusively observed in LMNA-mutated patients, was of variable severity and limited to postpubertal subjects. Lipodystrophy and metabolic disturbances were more severe in women, even if an enlarged neck was a constant finding. The severity of hypertriglyceridemia and hirsutism in females was related to that of insulin resistance. Clinical muscular alterations were only present in LMNA-mutated patients. Clinical and histological examination showed an invalidating, progressive limb-girdle muscular dystrophy in a 42-yr-old woman that had been present since childhood, associated with a typical postpubertal FPLD phenotype. Six of eight adults presented the association of calf hypertrophy, perihumeral muscular atrophy, and a rolling gait due to proximal lower limb weakness. Muscular histology was compatible with muscular dystrophy in one of them and/or showed a nonspecific excess of lipid droplets (in three cases). Immunostaining of lamin A/C was normal in the six muscular biopsies. Surprisingly, calpain 3 expression was undetectable in the patient with the severe limb-girdle muscular dystrophy, although the gene did not reveal any molecular alterations. At the cardiac level, cardiac septal hypertrophy and atherosclerosis were frequent in FPLD patients. In addition, a 24-yr-old FPLD patient had a symptomatic second degree atrioventricular block. In conclusion, we showed that most lipodystrophic patients affected by the FPLD-linked LMNA R482W mutation show muscular and cardiac abnormalities. The occurrence and severity of the myopathic and lipoatrophic phenotypes varied and were not related. The muscular phenotype was evocative of limb girdle muscular dystrophy. Cardiac hypertrophy and advanced atherosclerosis were frequent. FPLD patients should receive careful neuromuscular and cardiac examination whatever the underlying LMNA mutation.
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PMID:Patients with familial partial lipodystrophy of the Dunnigan type due to a LMNA R482W mutation show muscular and cardiac abnormalities. 1553 79

Calpains 1 and 2 are heterodimeric proteases in which large (relative molecular mass M(r) 80000) and small (M(r) 28000) subunits are linked through their respective PEF (penta-EF-hand) domains. The skeletal muscle-specific calpain 3 is believed not to form a heterodimer with the small subunit but might homodimerize through its PEF domain. Size-exclusion chromatography and analytical ultracentrifugation of the recombinant PEF domain of calpain 3 show that it forms a stable homodimer that does not dissociate on dilution. Molecular modelling suggests that there would be no barriers to the dimerization of the whole enzyme through the PEF domains. This orientation would place the catalytic centres at opposite ends of the dimer.
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PMID:Homodimerization of calpain 3 penta-EF-hand domain. 1566 May 30

We present here the clinical, molecular and biochemical findings from 238 limb-girdle muscular dystrophy type 2A (LGMD2A) patients, representing approximately 50% (238 out of 484) of the suspected calpainopathy cases referred for the molecular study of the calpain 3 (CAPN3) gene. The mean age at onset of LGMD2A patients was approximately 14 years, and the first symptoms occurred between 6 and 18 years of age in 71% of patients. The mean age at which the patients became wheelchair bound was 32.2 years, with 84% requiring the use of a wheelchair between the age of 21 and 40 years. There was no correlation between the age at onset and the time at which the patient became wheelchair bound, nor between the sex of the patient and the risk of becoming wheelchair bound. Of the cases where the CAPN3 gene was not affected, approximately 20% were diagnosed as LGMD2I muscular dystrophy, while facioscapulohumeral muscular dystrophy (FSHD) was uncommon in this sample. We identified 105 different mutations in the CAPN3 gene of which 50 have not been described previously. These were distributed throughout the coding region of the gene, although some exons remained free of mutations. The most frequent mutation was 2362AG-->TCATCT (exon 22), which was present in 30.7% of the chromosomes analysed (146 chromosomes). Other recurrent mutations described were N50S, 550DeltaA, G222R, IVS6-1G-->A, A483D, IVS17+1G-->T, 2069-2070DeltaAC, R748Q and R748X, each of which was found in >5 chromosomes. The type of mutation in the CAPN3 gene does not appear to be a risk factor for becoming dependent on a wheelchair at a determined age. However, in the cases with two null mutations, there were significantly fewer patients that were able to walk than in the group of patients with at least one missense mutation. Despite the fact that the results of phenotyping and western blot might be biased due to multiple referral centres, producing a diagnosis on the basis of the classical phenotype is neither sufficiently sensitive (86.7%) nor specific (69.3%), although western blot proved to be even less sensitive (52.5%) yet more specific (87.8%). In this case LGMD2I was a relevant cause of false-positive diagnoses. Considering both the clinical phenotype and the biochemical information together, the probability of correctly diagnosing a calpainopathy is very high (90.8%). However, if one of the analyses is lacking, the probability varies from 78.3 to 73.7% depending on the information available. When both tests are negative, the probability that the sample comes from a patient with LGMD2A was 12.2%.
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PMID:LGMD2A: genotype-phenotype correlations based on a large mutational survey on the calpain 3 gene. 1568 61

Limb girdle muscular dystrophy 2A is a common variant secondary to mutations in the calpain 3 gene. A proportion of patients has early and severe contractures, which can cause diagnostic difficulties with other conditions. We report clinical and muscle magnetic resonance imaging findings in seven limb girdle muscular dystrophy 2A patients (four sporadic and three familial) who had prominent and early contractures. All patients showed a striking involvement of the posterior thigh muscles. The involvement of the other thigh muscles was variable and was related to clinical severity. Young patients with minimal functional motor impairment showed a predominant involvement of the adductors and semimembranosus muscles while patients with restricted ambulation had a more diffuse involvement of the posterolateral muscles of the thigh and of the vastus intermedius with relative sparing of the vastus lateralis, sartorius and gracilis. At calf level all patients showed involvement of the soleus muscle and of the medial head of the gastrocnemius with relative sparing of the lateral head. MRI findings were correlated to those found in two patients with the phenotype of limb girdle muscular dystrophy 2A without early contractures and the pattern observed was quite similar. However, the pattern observed in limb girdle muscular dystrophy 2A is different from that reported in other muscle diseases such as Emery-Dreifuss muscular dystrophy and Bethlem myopathy which have a significant clinical overlap with limb girdle muscular dystrophy 2A once early contractures are present. Our results suggest that muscle MRI may help in recognising patients with limb girdle muscular dystrophy 2A even when the clinical presentation overlaps with other conditions, and may therefore, be used as an additional investigation to target the appropriate biochemical and genetic tests.
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PMID:Muscle MRI findings in patients with limb girdle muscular dystrophy with calpain 3 deficiency (LGMD2A) and early contractures. 1569 38

Mutations in dysferlin, a member of the fer1-like protein family that plays a role in membrane integrity and repair, can give rise to a spectrum of neuromuscular disorders with phenotypic variability including limb-girdle muscular dystrophy 2B, Myoshi myopathy and distal anterior compartment myopathy. To improve the tools available for understanding the pathogenesis of the dysferlinopathies, we have established a large source of highly specific antibody reagents against dysferlin by selection of heavy-chain antibody fragments originating from a nonimmune llama-derived phage-display library. By utilizing different truncated forms of recombinant dysferlin for selection and diverse selection methodologies, antibody fragments with specificity for two different dysferlin domains could be identified. The selected llama antibody fragments are functional in Western blotting, immunofluorescence microscopy and immunoprecipitation applications. Using these antibody fragments, we found that calpain 3, which shows a secondary reduction in the dysferlinopathies, interacts with dysferlin.
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PMID:Protein studies in dysferlinopathy patients using llama-derived antibody fragments selected by phage display. 1582 62

Previous family studies revealed a large number of calpain 3 ( CAPN3 ) mutations that cause recessive forms of limb girdle muscular dystrophy (LGMD2A) with selective atrophy of the proximal limb muscles. Correlations between the nature and site of a particular mutation and its corresponding phenotype, however, can only be established from homozygous mutations, which are particularly rare in the alternatively spliced NS, IS1 and IS2 regions of CAPN3. Here we identified a sibling pair with LGMD2A-type muscular dystrophy caused by a homozygous Ser606Leu (S606L) substitution in the IS2 linker domain. Normal protein levels, unaltered myofibrillar targeting and conserved calcium-induced autocatalytic activity of the mutated protein could be demonstrated in muscle biopsies from one patient. Despite this inconspicuous modification of the IS2 linker between domains III and IV, both patients developed signs and symptoms of the disease within their second decade of life. The unexpected severity of the clinical manifestation points to the high relevance of the calpain 3-specific IS2 segment between domains III and IV. We conclude that the structural motif around the Ser606 residue represents an important functional site that may regulate the transient activation and limited proteolysis of calpain 3.
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PMID:Limb girdle muscular dystrophy in a sibling pair with a homozygous Ser606Leu mutation in the alternatively spliced IS2 region of calpain 3. 1584 48

Studies on the correlation between expression and/or autolysis of calpain and postmortem proteolysis in muscle have provided conflicting evidence regarding the possible role of calpain 3 in postmortem tenderization of meat. Thus, the objective of this research was to test the effect of postmortem storage on proteolysis and structural changes in muscle from normal and calpain 3 knockout mice. Knockout mice (n = 6) were sacrificed along with control mice (n = 6). Hind limbs were removed and stored at 4 degrees C; muscles were dissected at 0, 1, and 3 d postmortem and subsequently analyzed individually for degradation of desmin. Pooled samples for each storage time and mouse type were analyzed for degradation of nebulin, dystrophin, vinculin, and troponin-T. In a separate experiment, hind-limb muscles from knockout (n = 4) and control mice (n = 4) were analyzed for structural changes at 0 and 7 d postmortem using light microscopy. As an index of structural changes, fiber detachment, cracked or broken fibers, and the appearance of space between sarcomeres were quantified. Cumulatively, the results of the first experiment indicated that postmortem proteolysis of muscle occurred similarly in control and in calpain 3 knockout mice. Desmin degradation did not differ (P > 0.99), and there were no indications that degradation of nebulin, dystrophin, vinculin, and troponin-T were affected by the absence of calpain 3 in postmortem muscle. Structural changes were affected by time postmortem (P < 0.05), but not by the absence of calpain 3 from the muscles. In conclusion, these results indicate that calpain 3 plays a minor role, if any, in postmortem proteolysis in muscle.
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PMID:Calpain 3/p94 is not involved in postmortem proteolysis. 1595 73


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