Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018799 (heart disease)
 34,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Loss of myofilaments has been observed in both adaptive cardiac responses (i.e., hypertrophy) as well as in chemotheraputic use of antineoplastic drugs with cardiotoxic side effects (i.e., doxorubicin). An understanding of the degenerative process is a prerequisite for determining approaches to limit the cardiomyopathic changes associated with chronic heart disease or long-term chemotheraputic treatments. However, little is known about the specific events and molecular changes that initiate the degenerative process. To study this process, neonatal rat cardiomyocytes were treated with doxorubicin, which induced rapid and widespread thin-filament degeneration as observed by fluorescence confocal microscopy. Which demonstrated deterioration of sarcomeric thin-filament structure. Changes in the spontaneous beating of cardiomyocytes corresponding with myofibrillar degeneration were apparent using differential interference contrast video microscopy. After finding induction of kinase activity by doxorubicin in cultured cardiomyocytes, the protective effects of specific inhibitors of kinase activity were assessed for their ability to inhibit doxorubicin-induced myofibrillar break-down. Doxorubicin-induced changes appeared similar to the degeneration observed after treatment with a protein kinase activator (phorbol 12-myristate 13-acetate) or a serine-threonine protein phosphatase inhibitor (okadaic acid). Collectively, these results indicate that activation of protein kinase is an important event in the initiation of myofibrillar degeneration by doxorubicin. Further analyses of myofibrillar proteins with respect to biochemical modifications will be necessary to determine if phosphorylation events transmit signal(s) to initiate degeneration.
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PMID:Involvement of phosphorylation in doxorubicin-mediated myofibril degeneration. An immunofluorescence microscopy analysis. 897 22

Congenital heart disease (CHD), cardiomyopathy, and vasculopathies are common causes of mortality and morbidity in pediatrics, including the perinatal period. This article reviews evidence that single gene defects cause many of the pediatric heart diseases. Vasculopathies discussed include Marfan's syndrome, supravalvar aortic stenosis and Williams' syndrome, Alagille's syndrome, and hereditary telangiectasia, the Osler-Weber-Rendu syndrome. Genetic causes of hypertrophic cardiomyopathy caused by sarcomeric protein mutations (beta-cardiac myosin heavy chain) and of dilated cardiomyopathy secondary to structural protein deficiencies (dystrophin) are presented. Defects in proteins essential for myocardial energy production such as oxidative phosphorylation proteins and fatty acid oxidation genes that cause cardiomyopathy or sudden death are described. Gene ablation models in mice, such as RXR alpha and homeobox gene knockouts, which result in cardiac phenotypes resembling human congenital heart disease, are described. Familial types of human CHD which are being investigated for genetic causes by positional cloning methods and known cytogenetic causes of CHD, including the CATCH-22 syndrome and monosomy at 22q11, are presented. General lessons and principles derived from these new and exciting discoveries in human cardiovascular development are surmised.
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PMID:The genetic basis of pediatric cardiovascular disease. 909 Jul 81

Hypertrophic cardiomyopathy is a human heart disease characterized by increased ventricular mass, focal areas of fibrosis, myocyte, and myofibrillar disorganization. This genetically dominant disease can be caused by mutations in any one of several contractile proteins, including beta cardiac myosin heavy chain (beta MHC). To determine whether point mutations in human beta MHC have direct effects on interfering with filament assembly and sarcomeric structure, full-length wild-type and mutant human beta MHC cDNAs were cloned and expressed in primary cultures of neonatal rat ventricular cardiomyocytes (NRC) under conditions that promote myofibrillogenesis. A lysine to arginine change at amino acid 184 in the consensus ATP binding sequence of human beta MHC resulted in abnormal subcellular localization and disrupted both thick and thin filament structure in transfected NRC. Diffuse beta MHC K184R protein appeared to colocalize with actin throughout the myocyte, suggesting a tight interaction of these two proteins. Human beta MHC with S472V mutation assembled normally into thick filaments and did not affect sarcomeric structure. Two mutant myosins previously described as causing human hypertrophic cardiomyopathy, R249Q and R403Q, were competent to assemble into thick filaments producing myofibrils with well defined I bands, A bands, and H zones. Coexpression and detection of wild-type beta MHC and either R249Q or R403Q proteins in the same myocyte showed these proteins are equally able to assemble into the sarcomere and provided no discernible differences in subcellular localization. Thus, human beta MHC R249Q and R403Q mutant proteins were readily incorporated into NRC sarcomeres and did not disrupt myofilament formation. This study indicates that the phenotype of myofibrillar disarray seen in HCM patients which harbor either of these two mutations may not be directly due to the failure of the mutant myosin heavy chain protein to assemble and form normal sarcomeres, but may rather be a secondary effect possibly resulting from the chronic stress of decreased beta MHC function.
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PMID:Point mutations in human beta cardiac myosin heavy chain have differential effects on sarcomeric structure and assembly: an ATP binding site change disrupts both thick and thin filaments, whereas hypertrophic cardiomyopathy mutations display normal assembly. 910 42

The different functions of the ventricular- and atrial-specific essential myosin light chains are unknown. Using transgenesis, cardiac-specific overexpression of proteins can be accomplished. The transgenic paradigm is more useful than originally expected, in that the mammalian heart rigorously controls sarcomeric protein stoichiometries. In a clinical subpopulation suffering from heart disease caused by congenital malformations of the outflow tract, an ELC1v-->ELC1a isoform shift correlated with increases in cross-bridge cycling kinetics as measured in skinned fibers derived from the diseased muscle. We have used transgenesis to replace the ventricular isoform of the essential myosin light chain with the atrial isoform. The ELC1v--> ELC1a shift in the ventricle resulted in similar functional alterations. Unloaded velocities as measured by the ability of the myosin to translocate actin filaments in the in vitro motility assay were significantly increased as a result of the isoform substitution. Unloaded shortening velocity was also increased in skinned muscle fibers, and at the whole organ level, both contractility and relaxation were significantly increased. This increase in cardiac function occurred in the absence of a hypertrophic response. Thus, ELC1a expression in the ventricle appears to be advantageous to the heart, resulting in increased cardiac function.
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PMID:Functional significance of cardiac myosin essential light chain isoform switching in transgenic mice. 963 96

Mutations in multiple cardiac sarcomeric proteins including myosin heavy chain (MyHC) and cardiac troponin T (cTnT) cause a dominant genetic heart disease, familial hypertrophic cardiomyopathy (FHC). Patients with mutations in these two genes have quite distinct clinical characteristics. Those with MyHC mutations demonstrate more significant and uniform cardiac hypertrophy and a variable frequency of sudden death. Patients with cTnT mutations generally exhibit mild or no hypertrophy, but a high frequency of sudden death at an early age. To understand the basis for these distinctions and to study the pathogenesis of the disease, we have created transgenic mice expressing a truncated mouse cTnT allele analogous to one found in FHC patients. Mice expressing truncated cTnT at low (< 5%) levels develop cardiomyopathy and their hearts are significantly smaller (18-27%) than wild type. These animals also exhibit significant diastolic dysfunction and milder systolic dysfunction. Animals that express higher levels of transgene protein die within 24 h of birth. Transgenic mouse hearts demonstrate myocellular disarray and have a reduced number of cardiac myocytes that are smaller in size. These studies suggest that multiple cellular mechanisms result in the human disease, which is generally characterized by mild hypertrophy, but, also, frequent sudden death.
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PMID:A truncated cardiac troponin T molecule in transgenic mice suggests multiple cellular mechanisms for familial hypertrophic cardiomyopathy. 963 14

The impact of molecular genetics in the diagnosis and management of various forms of heritable cardiac or vascular disorders is continuously increasing thanks to the newly available laboratory tools. Familial hypertrophic cardiomyopathy (FHC), an autosomal dominant inherited disease characterized by unexplained left ventricular hypertrophy and a wide range of clinical symptoms, is the first cardiac disorder whose genetic bases have been elucidated. Linkage analysis studies have shown a statistically significant association between the disease status and at least seven genetic loci, all coding for sarcomeric proteins, in unrelated kindreds. A major challenge for physicians is to make an accurate and early diagnosis, not only on the basis of the traditional tools (i.e. physical examination and electro-echocardiography) but also to focus on the impact of genotype on clinical manifestations of FHC. In this review we present the more recent findings on the genetic basis of FHC and analyze the genotype-phenotype correlations of this disorder, whose expression may be modulated by additional factors (modifier genes, genetic background, environmental factors) other than mutations in any of the sarcometric proteins.
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PMID:Familial hypertrophic cardiomiopathy: molecular basis and genotype-phenotype correlations. 983 79

Aim of the study: To analyze the changes in DNA content, the percentage of apoptosis and the nuclear mitotic frequency of myocytes in transplanted human hearts. Methods: Twenty-three transplanted hearts were obtained from 22 patients. The mean interval between transplantation and death was 649 days (ranging from 13 to 2558 days). Ten control hearts were selected from individuals whose death was not due to primary heart disease. Tissue samples were obtained from the mid section of the lateral wall of left and right ventricles. DNA content was evaluated on isolated myocardial cells using image cytometry. In situ detection of apoptosis was performed by the terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling (TUNEL) technique. Mitotic figures were examined by staining the nuclear DNA with YOYO-1 iodide. Myocytes were distinguished from stromal cells by using antibodies reacting with a-sarcomeric actin. Results: Comparing with control hearts, the myocytic changes after cardiac transplantation are characterized by: 1) a decrease in mononucleated myocytes and an increase in binucleated and multinucleated myocytes; 2) a decrease in diploid myocytic nuclei and a distinct augmentation of intermediate ploidies; 3) an increase in myocytic nuclei in DNA ploidies higher than 4c; 4) a marked augmentation of percentage of apoptotic myocytes and 5) an increased frequency of nuclear mitosis of myocytes; this fact appears as a declining phenomenon after six months of cardiac transplantation. Conclusion: After cardiac transplantation the DNA content of myocytes shows two completely different aspects: 1) a distinct increase in subdiploidy and intermediate ploidies related to myocyte injury induced by apoptosis and necrosis; 2) an increase in multinucleation, polyploidization and mitotic proliferation. Both myocyte growth and myocyte injury alter the function of the allograft and contribute to adaptation or failure of the graft. Furthermore, a relevant difference of age between the recipient and the donor may lead to a more marked myocyte damage and a lower myocyte growth. This tendency provides an evidence that age matching could be an important aspect in selecting the donor for the recipient.
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PMID:DNA content, apoptosis and mitosis in transplanted human hearts. 1035 64

Hypertrophic cardiomyopathy (HCM), a common primary cardiac disorder with an increased risk of sudden death, affects all population groups in South Africa. Distinct causal mutations in multiple sarcomeric protein-encoding genes correlate with the risk of sudden death. Such genotype/phenotype correlations cannot be extrapolated geographically or ethnically, necessitating the generation of South African-specific data. We used DNA-based techniques to search for the causal mutations in a panel of South African HCM-affected subjects (37 with unequivocal HCM, 47 with HCM-like disease). Mutations detected were traced in family members and carriers assessed by echocardiography and electrocardiography. Nine different HCM-causing mutations (5 unique to South Africa, 3 showing a founder effect) were identified in 3 genes in 24 index cases (57% HCM group, 6% HCM-like group). The different mutations were associated with variable hypertrophy, independent of the risk of sudden death. The disease was generally familial and many at-risk mutation carriers did not meet clinical diagnostic criteria for HCM. Rigorous diagnosis of index cases facilitates detection of causal mutations, which allows for unequivocal DNA-based diagnosis of at-risk family members, regardless of age or clinical status. This permits focused patient management, informed prognostication and realistic counselling for this insidious disease, as well as time and cost savings.
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PMID:Hypertrophic cardiomyopathy repealing tenets in South Africa. 1144 80

The Z-line is a multifunctional macromolecular complex that anchors sarcomeric actin filaments, mediates interactions with intermediate filaments and costameres, and recruits signaling molecules. Antiparallel alpha-actinin homodimers, present at Z-lines, cross-link overlapping actin filaments and also bind other cytoskeletal and signaling elements. Two LIM domain containing proteins, alpha-actinin associated LIM protein (ALP) and muscle LIM protein (MLP), interact with alpha-actinin, distribute in vivo to Z-lines or costameres, respectively, and, when absent, are associated with heart disease. Here we describe the behavior of ALP and MLP during myofibrillogenesis in cultured embryonic chick cardiomyocytes. As myofibrils develop, ALP and MLP are observed in distinct distribution patterns in the cell. ALP is coincident with alpha-actinin from the first stage of myofibrillogenesis and co-distributes with alpha-actinin to Z-lines and intercalated discs in mature myofibrils. Interestingly, we also demonstrate using ALP-GFP transfection experiments and an in vitro binding assay that the ALP-alpha-actinin binding interaction is not required to target ALP to the Z-line. In contrast, MLP localization is not co-incident with that of alpha-actinin until late stages of myofibrillogenesis; however, it is present in premyofibrils and nascent myofibrils prior to the incorporation of other costameric components such as vinculin, vimentin, or desmin. Our observations support the view that ALP function is required specifically at actin anchorage sites. The subcellular distribution pattern of MLP during myofibrillogenesis suggests that it functions during differentiation prior to the establishment of costameres.
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PMID:ALP and MLP distribution during myofibrillogenesis in cultured cardiomyocytes. 1258 84

The muscle protein myosin binding protein C (MyBPC) is a large multi-domain protein whose role in the sarcomere is complex and not yet fully understood. Mutations in MyBPC are strongly associated with the heart disease familial hypertrophic cardiomyopathy (FHC) and these experiments of nature have provided some insight into the intricate workings of this protein in the heart. While some regions of the MyBPC molecule have been assigned a function in the regulation of muscle contraction, the interaction of other regions with various parts of the myosin molecule and the sarcomeric proteins, actin and titin, remain obscure. In addition, several intra-domain interactions between adjacent MyBPC molecules have been identified. Although the basic structure of the molecule (a series of immunoglobulin and fibronectin domains) has been elucidated, the assembly of MyBPC in the sarcomere is a topic for debate. By analysing the MyBPC sequence with respect to FHC-causing mutations it is possible to identify individual residues or regions of each domain that may be important either for binding or regulation. This review looks at the current literature, in concert with alignments and the structural models of MyBPC, in an attempt to understand how FHC mutations may lead to the disease state.
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PMID:Myosin binding protein C: structural abnormalities in familial hypertrophic cardiomyopathy. 1511 10


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