Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.69 (APC)
16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In recent years, the striking development of molecular biology and molecular genetic has brought completely new insights into the understanding of heart failure. Two aspects for which significant progress has been made in 1995 are discussed in this review: the genetic mechanisms of inherited cardiomyopathies and the molecular basis of heart failure due to chronic hemodynamic overload. In familial hypertrophic cardiomyopathy, a novel disease gene was found. It encodes myosin binding protein C, whose structure and function are poorly understood. Contractile deficits associated with the myosin mutations were demonstrated, and all this strengthened the hypothesis that hypertrophy is a compensatory mechanism that occurs in presence of a sarcomeric defect. These studies have important prognostic and clinical implications, but new and unexpected concerns have arisen, because a widespread difference in phenotype can be seen in patients harboring similar genotypes. In familial dilated cardiomyopathy, the main findings were the identification of four disease loci, but the genes are still unknown. With respect to the consequences of chronic hemodynamic overload on myocyte function and phenotype, recent data gave rise to lively discussions in the fields of reexpression of fetal troponin T isoforms and of decreased function and expression of the sarco(endo)plasmic reticulum Ca2+ ATPase in the failing human heart; at the moment it is difficult to draw definitive conclusions. Interestingly, three new concepts emerged in the understanding of the pathogenesis of heart failure: the increased contribution of the Na(+)-Ca2+ exchange, the possible recruitment of an inositol phosphate-sensitive calcium pool for myofibrillar activation, and the involvement of apoptotic myocyte and nonmyocyte cell death in myocardial remodeling.
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PMID:Molecular and cellular biology of heart failure. 883 64

Mutations in the gene for the cardiac isoform of myosin binding protein C (MyBP-C) have been identified as the cause of chromosome 11-associated autosomal-dominant familial hypertrophic cardiomyopathy (FHC). Most mutations produce a truncated polypeptide that lacks the sarcomeric binding region. We have now investigated the expression pattern of the cardiac and skeletal isoforms of cMyBP-C in mice and humans by in situ hybridization and immunofluorescence microscopy using specific antibodies and probes. We demonstrate that the cardiac isoform is expressed only in cardiac muscle throughout development. The slow and fast isoforms of MyBP-C remain specific for skeletal muscle, where they can be coexpressed. Immunological evidence also suggests that an embryonic isoform of MyBP-C precedes the expression of slow MyBP-C in developing skeletal muscle. This suggests that transcomplementation of MyBP-C isoforms is possible in skeletal but not cardiac muscle.
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PMID:Isoform transitions of the myosin binding protein C family in developing human and mouse muscles: lack of isoform transcomplementation in cardiac muscle. 944 Jul 11

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease caused by mutations in sarcomeric proteins. The disease is characterized by left ventricular hypertrophy in the absence of an increased external load, and myofibrillar disarray. A large number of mutations in genes coding for the beta-myosin heavy chain (beta-MyHC), cardiac troponin T (cTnT), cardiac troponin I, alpha-tropomyosin, myosin binding protein C (MyBP-C), and myosin light chain 1 and 2 in patients with HCM have been identified. Genotype-phenotype correlation studies have shown that mutations carry prognostic significance. The Gly256Glu, Val606Met, and Leu908Val mutations in the beta-MyHC are associated with a benign prognosis. In contrast, Arg403Gln, Arg719Trp, and Arg453Cys mutations are associated with a high incidence of sudden cardiac death (SCD). Mutations in cTnT are associated with a mild degree of hypertrophy, but a high incidence of SCD. Mutations in MyBP-C are associated with mild hypertrophy and a benign prognosis. However, it has become evident that factors other than the underlying mutations, such as genetic background and possibly environmental factors, also modulate phenotypic expression of HCM.
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PMID:Molecular genetic basis of hypertrophic cardiomyopathy: genetic markers for sudden cardiac death. 947 82

Cardiomyopathies (CMP) clinically and genetically belong to the heterogeneous group of myocardial diseases. Among them, three major clinical forms (hypertrophic, dilated, and restricted) are distinguished. Genetic factors play a substantial role in the etiology of dilated and hypertrophic CMP; family cases constitute more than 20% of these forms. Most familial cases of CMP are inherited as an autosomal dominant character. Autosomal recessive and X-linked forms are rare. Genetic basis for rare familial forms of restricted CMP is unclear. There are forms with strict maternal inheritance, which suggests the involvement of the mitochondrial genome. The nature of several CMP forms was determined and a number of genetic loci for this disease was revealed by modern methods of genetic mapping. In familial hypertrophic cardiomyopathy (FHC), four genes have been identified (those of beta-myosin heavy chain, alpha-tropomyosin, cardiac troponin T, and myosin-binding protein C), all of which encode sarcomeric proteins. Maternally inherited forms of FHC are associated with mutations in the mitochondrial tRNA genes. Linkage analysis in familial dilated CMP revealed at least five genetic loci on chromosomes 1, 3, 9, and X. X-linked forms of dilated CMP are caused by mutations in dystrophin gene, but the nature of autosomal forms is unclear. A recently recognized form of dilated CMP, arrhythmogenic CMP/right ventricular dysplasia (ARVD) is linked to two actinin gene loci on chromosomes 1 and 14. Genomic studies of CMP provided a basis for a new stage of "genetic cardiology", genetic mapping, which at present includes the quest of candidate genes for many other human cardiovascular diseases.
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PMID:[Genomic studies of hereditary cardiomyopathies]. 958 60

Recent developments in molecular genetics have allowed to identify mutations in seven genes coding the beta myosin heavy chain, troponin T, alpha tropomyosin, myosin binding protein C, essential and regulatory myosin light chains and troponin I causing hypertrophic cardiomyopathy. These mutations affect critical, evolutionary conserved nucleotides of these genes and influence vital functions of the encoded proteins. As all seven genes encodes sarcomeric proteins in the heart muscle, hypertrophic cardiomyopathy is regarded these days as a disease of the sarcomer. Recent data indicate that some mutations are associated with "malignant" clinical picture, with rapidly developing, severe symptoms of the disease and increased risk of sudden cardiac death while other mutations bear a more favourable prognosis. Apart of the disease causing mutation other factors, including disease modifier genes, are likely to make an impact on the clinical appearance of hypertrophic cardiomyopathy. The knowledge provided by molecular genetics influences the clinical management of the disease even today and based on the investigation of mutation carrying patients new diagnostic criteria was proposed for hypertrophic cardiomyopathy. The challenge for the future is the establishment of routine genetic diagnostics and the development of possible gene therapy.
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PMID:[Clinical and molecular genetics of hypertrophic cardiomyopathy]. 973 14

Familial hypertrophic cardiomyopathy can be caused by mutations in genes encoding sarcomeric proteins, including the cardiac isoform of myosin binding protein C (MyBP-C), and multiple mutations which cause truncated forms of the protein to be made are linked to the disease. We have created transgenic mice in which varying amounts of a mutated MyBP-C, lacking the myosin and titin binding domains, are expressed in the heart. The transgenically encoded, truncated protein is stable but is not incorporated efficiently into the sarcomere. The transgenic muscle fibers showed a leftward shift in the pCa2+-force curve and, importantly, their power output was reduced. Additionally, expression of the mutant protein leads to decreased levels of endogenous MyBP-C, resulting in a striking pattern of sarcomere disorganization and dysgenesis.
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PMID:A mouse model of myosin binding protein C human familial hypertrophic cardiomyopathy. 976 21

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease caused by mutations in sarcomeric proteins. It is characterized by left ventricular hypertrophy in the absence of an increased external load, and myofibrillar disarray. While hypertrophy is a common cardiac response to injury, disarray is the pathological hallmark of HCM. A large number of mutations in genes coding for sarcomeric proteins, ie the beta-myosin heavy chain (beta-MyHC), cardiac troponin (cTn)T, cTnI, alpha-tropomyosin, myosin-binding protein C (MyBP-C), and essential and regulatory myosin light chains in patients with HCM have been identified. Genotype-phenotype correlation studies have shown that mutations carry prognostic significance. Unlike mutations in the beta-MyHC gene, the prognostic significance of which reflect their hypertrophic expressivity, cTnT mutations are associated with a mild degree of hypertrophy, but a high incidence of sudden cardiac death. Mutations in MyBP-C are associated with mild hypertrophy, and a benign prognosis. However, the genetic background in which the mutations occur, and possibly environmental factors also, modulate phenotypic expression of HCM. Functional studies of mutations causing HCM have shed significant light into the pathogenesis of HCM and have led to the hypothesis that mutant sarcomeric proteins function as 'poison peptides' exerting a dominant-negative effect on the function of the cardiac myocytes, followed by structural changes and a compensatory hypertrophy.
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PMID:Familial hypertrophic cardiomyopathy: a paradigm of the cardiac hypertrophic response to injury. 980 Aug 80

The expression and organization patterns of several myofibrillar proteins were analysed in the putative myofibroblast cell line BHK-21/C13. Although this cell line originates from renal tissue, the majority of the cells express titin. In these cells, titin is, under standard culture conditions, detected in myofibril-like structures (MLSs), where it alternates with non-muscle myosin (NMM). Expression of sarcomeric myosin heavy chain (sMyHC) is observed in a small minority of cells, while other sarcomeric proteins, such as nebulin, myosin binding protein C (MyBP-C), myomesin and M-protein are not expressed at all. By changing the culture conditions in a way equal to conditions that induce differentiation of skeletal muscle cells, a process reminiscent of sarcomerogenesis in vitro is induced. Within one day after the switch to a low-nutrition medium, myofibrillar proteins can be detected in a subset of cells, and after two to five days, all myofibrillar proteins examined are organized in typical sarcomeric patterns. Frequently, cross-striations are visible with phase contrast optics. Transfection of these cells with truncated myomesin fragments showed that a specific part of the myomesin molecule, known to contain a titin-binding site, binds to MLSs, whereas other parts do not. These results demonstrate that this cell line could serve as a powerful model to study the assembly of myofibrils. At the same time, its transfectability offers an invaluable tool for in vivo studies concerning binding properties of sarcomeric proteins.
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PMID:Expression of sarcomeric proteins and assembly of myofibrils in the putative myofibroblast cell line BHK-21/C13. 983 47

Myosin binding protein C (MyBP-C) is one of a group of myosin binding proteins that are present in the myofibrils of all striated muscle. The protein is found at 43-nm repeats along 7 to 9 transverse lines in a portion of the A band where crossbridges are found (C zone). MyBP-C contains myosin and titin binding sites at the C terminus of the molecule in all 3 of the isoforms (slow skeletal, fast skeletal, and cardiac). The cardiac isoform also includes a series of residues that contain 3 phosphorylatable sites and an additional immunoglobulin module at the N terminus that are not present in skeletal isoforms. The following 2 major functions of MyBP-C have been suggested: (1) a role in the formation of the sarcomeric myofibril as a result of binding to myosin and titin and (2) in the case of the cardiac isoform, regulation of contraction through phosphorylation. The first is supported by the demonstrated effect of MyBP-C on the packing of myosin in the thick filament, the coincidence of appearance of sarcomeres and MyBP-C during myofibrillogenesis, and the defective formation of sarcomeres when the titin and/or myosin binding sites of MyBP-C are missing. The second is supported by the specific phosphorylation sites in cardiac MyBP-C, the presence in the thick filament of an enzyme specific for MyBP-C phosphorylation, the alteration of thick filament structure by MyBP-C phosphorylation, and the accompaniment of MyBP-C phosphorylation with all major physiological mechanisms of modulation of inotropy in the heart.
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PMID:Cardiac myosin binding protein C. 1034 86

Myosin binding protein C (MyBP-C) is an integral part of the striated muscle sarcomere. As is the case for other sarcomeric genes in human populations, multiple mutations within the gene have been linked to familial hypertrophic cardiomyopathy. Although some MyBP-C lesions are the result of missense mutations, most show truncated polypeptides lacking either the myosin or myosin and titin binding sites. Previously, we generated transgenic (TG) mice with cardiac-specific expression of a MyBP-C mutant lacking the myosin and titin binding domains. Surprisingly, the mutant protein was stable and made up a majority of the MyBP-C species, with concomitant reductions in endogenous MyBP-C such that overall MyBP-C stoichiometry was conserved. In the present study, we created a second series of TG mice that express, in the heart, a mutant MyBP-C lacking only the myosin binding site. In contrast to the previous data for the MyBP-C lacking both titin and myosin binding sites, only very modest levels of protein were found, consistent with data obtained from human biopsies in which mutated MyBP-C could not be detected. Despite normal levels of wild-type MyBP-C, there were significant changes in the structure and ultrastructure of the heart. Fiber mechanics showed decreased unloading shortening velocity, maximum shortening velocity, and relative maximal power output.
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PMID:In vivo modeling of myosin binding protein C familial hypertrophic cardiomyopathy. 1053 52


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