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

Muscular dystrophy with myositis (mdm) is a recessive mouse mutation that is caused by a small deletion in the giant elastic muscle protein titin. Homozygous mdm/mdm mice develop a progressive muscular dystrophy, leading to death at approximately 2 months of age. We surveyed the transcriptomes of skeletal muscles from 24 day old homozygous mdm/mdm and +/+ wild-type mice, an age when MDM animals have normal passive and active tensions and sarcomeric structure. Of the 12488 genes surveyed (U74 affymetrix array), 75 genes were twofold to 30-fold differentially expressed, including CARP (cardiac ankyrin repeat protein), ankrd2/Arpp (a CARP-like protein) and MLP (muscle LIM protein), all of which associate with the titin filament system. The four genes most strongly affected (eightfold to 30-fold change) were all members of the CARP-regulated Nkx-2.5-dependent signal pathway, and CARP mRNA level was 30-fold elevated in MDM skeletal muscle tissues. The CARP protein overexpressed in MDM became associated with the I-band region of the sarcomere. The mdm mutation excises the C-terminal portion of titin's N2A region, abolishing its interaction with p94/calpain-3 protease. Thus, the composition of the titin N2A protein complex is altered in MDM by incorporation of CARP and loss of p94/calpain-3. These changes were absent from the following control tissues (1). cardiac muscles from homozygous mdm/mdm animals, (2). skeletal and cardiac muscle from heterozygous mdm/+ animals, and (3). dystrophic muscles from MDX mice. Thus, the altered composition of the titin N2A complex is specific for the titin-based skeletal muscular dystrophy in MDM.
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PMID:Induction and myofibrillar targeting of CARP, and suppression of the Nkx2.5 pathway in the MDM mouse with impaired titin-based signaling. 1474 Dec 10

In this study, we generated three SAGE libraries from melanoma tissues. Using bioinformatics tools usually applied to microarray data, we identified several genes, including novel transcripts, which are preferentially expressed in melanoma. SAGE results converged with previous microarray analysis on the importance of intracellular calcium and G-protein signaling, and the Wnt/Frizzled family. We also examined the expression of CD74, which was specifically, albeit not abundantly, expressed in the melanoma libraries using a melanoma progression tissue microarray, and demonstrate that this protein is expressed by melanoma cells but not by benign melanocytes. Many genes involved in intracellular calcium and G-protein signaling were highly expressed in melanoma, results we had observed earlier from microarray studies (Bittner et al., 2000). One of the genes most highly expressed in our melanoma SAGE libraries was a calcium-regulated gene, calpain 3 (p94). Immunohistochemical analysis demonstrated that calpain 3 moves from the nuclei of non-neoplastic cells to the cytoplasm of malignant cells, suggesting activation of this intracellular proteinase. Our SAGE results and the clinical validation data demonstrate how SAGE profiles can highlight specific links between signaling pathways as well as associations with tumor progression. This may provide insights into new genes that may be useful for the diagnosis and therapy of melanoma.
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PMID:Generation and analysis of melanoma SAGE libraries: SAGE advice on the melanoma transcriptome. 1475 46

The physiological role of the skeletal muscle-specific calpain 3, p94, is presently unknown, but defects in its gene cause limb girdle muscular dystrophy type 2A. This calcium-dependent cysteine protease resembles the large subunit of m-calpain but with three unique additional sequences: an N-terminal region (NS), and two insertions (IS1 and IS2). The latter two insertions have been linked to the chronic instability of the whole enzyme both in vivo and in vitro. We have shown previously that the core of p94 comprising NS, domains I and II, and IS1 is stable as a recombinant protein in the absence of Ca(2+) and undergoes autolysis in its presence. Here we show that p94I-II cannot hydrolyze an exogenous substrate before autolysis but is increasingly able to do so when autolysis proceeds for several hours. This gain in activity is caused by cleavage of IS1 during autolysis because a deletion mutant lacking the NS region (p94I-II DeltaNS) shows the same activation profile. Similarly, the calpain inhibitors E-64 and leupeptin have almost no inhibitory effect on substrate hydrolysis by p94I-II soon after calcium addition but cause complete inhibition when autolysis progresses for several hours. As autolysis proceeds, there is release of the internal IS1 peptide, but the two portions of the core remain tightly associated. Modeling of p94I-II suggests that IS1 contains an amphipathic alpha-helix flanked by extended loops. The latter are the targets of autolysis and limited digestion by exogenous proteases. The presence and location of the alpha-helix in recombinant IS1 were confirmed by circular dichroism and by the introduction of a L286P helix-disrupting mutation. Within p94I-II, L286P caused premature autoproteolysis of the enzyme. IS1 is an elaboration of a loop in domain II near the active site, and it acts as an internal autoinhibitory propeptide, blocking the active site of p94 from substrates and inhibitors.
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PMID:Insertion sequence 1 of muscle-specific calpain, p94, acts as an internal propeptide. 1507 71

Ankrd2 may be a link between the sarcomere and the nucleus; a similar role has recently been proposed for CARP that has a high level of structural and functional conservation with Ankrd2. Both Ankrd2 and CARP are involved in striated muscle hypertrophy. The mechanism by which muscle stretch is sensed and signals are transduced is still unknown; however, Ankrd2 and CARP could play similar roles in pathways leading to hypertrophy, the triggering mechanisms being heart pressure overload monitored by CARP and mechanical stretch in skeletal muscle monitored by Ankrd2. Recently Ankrd2 and CARP have been proposed as members of a family of muscle ankyrin repeat proteins (MARPs) that form a complex with titin, myopalladin and calpain protease p94, involved in signaling and regulation of gene expression in response to muscle stress. Here, we show that Ankrd2 is able to interact with the Z-disc protein telethonin as well as being able to interact with three transcription factors: YB-1, PML and p53. Ankrd2 binding to the ubiquitous transcription factor YB-1 can be demonstrated both in vitro and in vivo; this is not very surprising, since a similar interaction was previously described for CARP. However, the interactions with PML and p53 are unexpected new findings, with interesting implications in the Ankrd2 signaling cascade. Ankrd2 co-localizes with the transcriptional co-activator and co-repressor PML in nuclear bodies (NBs) in human myoblasts as detected by confocal immunofluorescence. Interestingly, we show that Ankrd2 not only binds the tumor suppressor protein p53 both in vitro and in vivo but also enhances the up-regulation of the p21(WAFI/CIPI) promoter by p53. Therefore, our findings strengthen the hypothesis that Ankrd2 may be involved in sensing stress signals and linking these to muscle gene regulation.
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PMID:The Ankrd2 protein, a link between the sarcomere and the nucleus in skeletal muscle. 1513 35

Calpain3 (CAPN3, p94) is a muscle-specific nonlysosomal cysteine proteinase. Loss of proteolytic function or change of other properties of this enzyme (such as stability or ability to interact with other muscular proteins) is manifested as limb girdle muscular dystrophy type 2A (LGMD2A, calpainopathy). These pathological changes in properties of calpain3 are caused by mutations in the calpain3 gene. The fact that the human gene for calpain3 is quite long led us to analyse its coding sequence by reverse transcription-PCR followed by sequence analysis. This study reports nine mutations that we found by analysing mRNA of seven unrelated LGMD patients in the Czech Republic. Three of these mutations were novel, not described on the Leiden muscular dystrophy pages so far. Further, we observed a reduction of dysferlin in muscle membrane in five of our seven LGMD2A patients by immunohistochemical analysis of muscle sections.
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PMID:Mutations in Czech LGMD2A patients revealed by analysis of calpain3 mRNA and their phenotypic outcome. 1535 23

It was hypothesised that diaphragm injury activates a time-based programme of gene expression in muscle repair. Gene expression of different substances, such as proteases (calpain 94 (p94)), transcription factors (myogenin and cFos), growth factors (both basic fibroblast growth factor (bFGF) and insulin-like growth factor (IGF)-II), and structural proteins (myosin heavy chain (MHC) and titin), was quantified by RT-PCR in rat diaphragms exposed to caffeine-induced injury. Injured and noninjured (control) rat hemidiaphragms were excised at different time points (1-240 h). In injured hemidiaphragms, in comparison with control muscles, p94 expression levels peaked at 1 h post-injury (PI), cFos mRNA levels began to rise, after an initial dip, and peaked at 96 h PI, while myogenin mRNA levels started to increase as early as 12 h PI, IGF-II mRNA levels initially decreased until 48 h PI and increased thereafter, peaking at 72 h PI, bFGF mRNA levels rose to a maximum at 96 h PI, and MHC and titin mRNA levels were significantly elevated at 72 h PI. Caffeine-induced diaphragm injury is followed by a time-based expression programme of different genes tailored to meet muscle repair needs.
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PMID:Time-based gene expression programme following diaphragm injury in a rat model. 1573 84

We previously reported that serum deprivation stimulates myofibrillar proteolysis in chick myotubes. In the present study, we examined the effect of serum deprivation on expression of the proteolytic-related genes (ubiquitin, proteasome, calpains, and cathepsin B) by real-time PCR of cDNA in chick myotubes. Myotubes were incubated with serum-free medium for 24 h. Ubiquitin and proteasome subunits (C1 and C2) and calpains (m-, mu-, and p94/calpain-3) but not cathepsin B mRNA expression were increased by serum deprivation. These results indicate that serum deprivation stimulates ubiquitin-proteasome and calpain proteolytic pathways, resulting in an increase in myofibrillar proteolysis in chick myotubes.
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PMID:Effects of serum deprivation on expression of proteolytic-related genes in chick myotube cultures. 1578 93

This experiment was conducted to study the effects of fasting and refeeding on proteolytic-related gene expression in skeletal muscles of chicks. Chicks were fasted for 24 h, and refed for 2 h. Plasma Ntau-methylhistidine concentration, as an index of myofibrillar protein degradation, was increased by fasting, and that increment was reduced by refeeding. We also examined the expression of the protease mRNAs (calpain, proteasome, cathepsin and caspase-3) by real-time PCR of cDNA in skeletal muscles of fasting and refeeding chicks. Calpain (m-, mu-, and p94/calpain-3) mRNA expressions were also increased by fasting, and their increment was reduced by refeeding. Ubiquitin and 20S proteasome alpha subunit (alpha6 and alpha7) mRNA expressions as well as cathepsin B, and caspase-3 mRNA expression were likewise increased by fasting, with their increment also reduced by refeeding. These results indicate that fasting stimulates proteolytic-related gene expression, resulting in an increase in myofibrillar protein degradation, and that refeeding suppresses proteolytic-related gene expression, resulting in a decrease in myofibrillar protein degradation in chicks.
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PMID:Effects of fasting and refeeding on expression of proteolytic-related genes in skeletal muscle of chicks. 1626 96

Calpains are intracellular Ca2+ -requiring 'modulator proteases', which modulate cellular functions by limited and specific proteolysis. p94/calpain3, a skeletal-muscle specific calpain, has been one of the representative calpain species which indicates physiological importance of calpain proteolytic system; a defect of proteolytic activity of p94 causes limb girdle muscular dystrophy type2A (LGMD2A, also called 'calpainopathy'). Immunohistochemical studies on myofibrils showed that p94 localizes at the Z- and N2-line regions of sarcomeres. It was also identified by the yeast two hybrid studies that p94 binds to the N2A and M-line regions of connectin. Furthermore, genetic studies indicate that p94 is indispensable for skeletal muscles, although its precise functions are still unclear. Interestingly, connectin provides sarcomere not only with elasticity but also with binding sites to various multi-functional proteins such as muscle ankyrin repeat proteins (MARPs), muscle RING finger proteins (MURFs), titin-capping protein (T-cap/telethonin), sarcomeric-alpha-actinin, p94 etc. Binding sites for these proteins are not randomly placed along connectin but rather accumulated in the Z-, N2-, and/or M-line regions, indicating the existence of 'signal complexes' unique to each regions. The concept of these complexes are strongly supported by the facts that mutations of connectin or its binding proteins in these regions severely perturb muscle functions, as in the case of LGMD2A caused by mutations in the p94 gene. Therefore, it is hypothesized that the 'signal complexes' in the Z-, N2-, and M-lines modulate muscle cell homeostasis by transducing signals of external stimulations/stresses to trigger appropriate response at various different cellular events such as protein modification and gene expressions. In this article, we performed detailed immunohistochemical analyses of p94 on isolated single myofibers. Together with recent findings about p94, it is suggested that sarcomeric localization of p94, especially its M-line localization, is affected by the combination of cellular contexts such as contractile status of myofibrils, fiber type compositions, sarcomeric maturation, and the composition of the 'signal complexes' in each region.
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PMID:Possible functions of p94 in connectin-mediated signaling pathways in skeletal muscle cells. 1645 64

Calpain 3, commonly called p94 in the literature, is the abundant skeletal muscle-specific calpain that is genetically linked to limb girdle muscular dystrophy type 2A. Recently, we showed that p94's insertion sequence 1 (IS1) is a propeptide that must be autoproteolytically cleaved to provide access of substrates and inhibitors to the enzyme's active site. Removal of IS1 from the core of p94 by recombinant methods produced a fully active enzyme. Here we have resolved the discrepancies in the literature about the Ca(2+) requirement of p94 using the protease core. Even at substoichiometric levels of Ca(2+), and in competition with EDTA, autoproteolyzed enzyme slowly accumulated. Because the initial autoproteolytic cleavage is an intramolecular reaction, transient binding of two Ca(2+) ions to the core would be sufficient to promote the reaction that is facilitated by having the scissile peptide lying close to the active site cysteine. The second autolytic cleavage was much slower and required higher Ca(2+) levels, consistent with it being an intermolecular reaction. Other metal ions such as Na(+), K(+), and Mg(2+) cannot substitute for Ca(2+) in catalyzing the intramolecular autoproteolysis of the p94 core or in the subsequent hydrolysis of exogenous substrates. These metal ions increase moderately the activity of this enzyme but only at very high concentrations. Thus, the proteolytic activity of the core of p94 and its deletion mutant lacking NS and IS1 was shown to be strictly Ca(2+)-dependent. We propose a two-stage model of activation of the proteolytic core of p94.
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PMID:Ca2+ dependency of calpain 3 (p94) activation. 1653 54


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