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Familial neonatal isolated cardiomyopathy caused by a mutation in the flavoprotein subunit of succinate dehydrogenase.

ABSTRACT: Cardiomyopathies are common disorders resulting in heart failure; the most frequent form is dilated cardiomyopathy (DCM), which is characterized by dilatation of the left or both ventricles and impaired systolic function. DCM causes considerable morbidity and mortality, and is one of the major causes of sudden cardiac death. Although about one-third of patients are reported to have a genetic form of DCM, reported mutations explain only a minority of familial DCM. Moreover, the recessive neonatal isolated form of DCM has rarely been associated with a mutation. In this study, we present the association of a mutation in the SDHA gene with recessive neonatal isolated DCM in 15 patients of two large consanguineous Bedouin families. The cardiomyopathy is presumably caused by the significant tissue-specific reduction in SDH enzymatic activity in the heart muscle, whereas substantial activity is retained in the skeletal muscle and lymphoblastoid cells. Notably, the same mutation was previously reported to cause a multisystemic failure leading to neonatal death and Leigh's syndrome. This study contributes to the molecular characterization of a severe form of neonatal cardiomyopathy and highlights extreme phenotypic variability resulting from a specific missense mutation in a nuclear gene encoding a protein of the mitochondrial respiratory chain.

SUBMITTER: Levitas A

PROVIDER: S-EPMC2987458 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature

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Familial neonatal isolated cardiomyopathy caused by a mutation in the flavoprotein subunit of succinate dehydrogenase.

Levitas Aviva A Muhammad Emad E Harel Gali G Saada Ann A Caspi Vered Chalifa VC Manor Esther E Beck John C JC Sheffield Val V Parvari Ruti R

European journal of human genetics : EJHG 20100616 10

Cardiomyopathies are common disorders resulting in heart failure; the most frequent form is dilated cardiomyopathy (DCM), which is characterized by dilatation of the left or both ventricles and impaired systolic function. DCM causes considerable morbidity and mortality, and is one of the major causes of sudden cardiac death. Although about one-third of patients are reported to have a genetic form of DCM, reported mutations explain only a minority of familial DCM. Moreover, the recessive neonatal ...[more]

PMID: 20551992

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Project description:Background/aimDysregulation of mitochondrial pathways is implicated in several diseases, including cancer. Notably, mitochondrial respiration and mitochondrial biogenesis are favored in some invasive cancer cells, such as osteosarcoma. Hence, the aim of the current work was to investigate the effects of 2-methoxyestradiol (2-ME), a potent anticancer agent, on the mitochondrial biogenesis of osteosarcoma cells.Materials and methodsHighly metastatic osteosarcoma 143B cells were treated with 2-ME separately or in combination with L-lactate, or with the solvent (non-treated control cells). Protein levels of α-syntrophin and peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PGC-1α) were determined by western blotting. Impact of 2-ME on mitochondrial mass, regulation of cytochrome c oxidase I (COXI) expression, and succinate dehydrogenase complex flavoprotein subunit A (SDHA) was determined by immunofluorescence analyses. Inhibition of sirtuin 3 (SIRT3) activity by 2-ME was investigated by fluorescence assay and also, using molecular docking and molecular dynamics simulations.ResultsL-lactate induced mitochondrial biogenesis pathway via up-regulation of COXI. 2-ME inhibited mitochondrial biogenesis via regulation of PGC-1α, COXI, and SIRT3 in a concentration-dependent manner as a consequence of nuclear recruitment of neuronal nitric oxide synthase and nitric oxide generation. It was also proved that 2-ME inhibited SIRT3 activity by binding to both the canonical and allosteric inhibitor binding sites. Moreover, regardless of the mitochondrial biogenesis pathway, 2-ME affected the expression of SDHA.ConclusionHerein, mitochondrial biogenesis pathway regulation and SDHA were presented as novel targets of 2-ME, and moreover, 2-ME was demonstrated as a potent inhibitor of SIRT3. L-lactate was confirmed to exert pro-carcinogenic effects on osteosarcoma cells via the induction of the mitochondrial biogenesis pathway. Thus, L-lactate level may be considered as a prognostic biomarker for osteosarcoma.

Project description:A subset (7% to 10%) of gastric gastrointestinal stromal tumors (GISTs) is notable for the immunohistochemical loss of succinate dehydrogenase (SDH) subunit B (SDHB), which signals the loss of function of the SDH complex consisting of mitochondrial inner membrane proteins. These SDH-deficient GISTs are known to be KIT/PDGFRA wild type, and most patients affected by this subset of GISTs are young. Some of these patients have germline mutations of SDH subunit genes SDHB, SDHC, or SDHD, known as Carney-Stratakis syndrome when combined with paraganglioma. More recently, germline mutations in SDH subunit A gene (SDHA) have also been reported in few patients with KIT/PDGFRA wild-type GISTs. In this study we immunohistochemically examined 127 SDHB-negative and 556 SDHB-positive gastric GISTs and 261 SDHB-positive intestinal GISTs for SDHA expression using a mouse monoclonal antibody 2E3 (Abcam). Cases with available DNA were tested for SDHA, SDHB, SDHC, and SDHD gene mutations using a hybridization-based custom capture next-generation sequencing assay. A total of 36 SDHA-negative GISTs (28%) were found among 127 SDHB-negative gastric GISTs. No SDHB-positive GIST was SDHA negative. Among 7 SDHA-negative tumors analyzed, there were 7 SDHA mutants, most germline. A second hit indicating biallelic inactivation of SDHA was present in 6 of those cases. These patients had no other SDH subunit gene mutations. Among the 25 SDHA-positive, SDHB-negative GISTs analyzed, we identified 3 SDHA mutations (1 germline), and 11 SDHB, SDHC, or SDHD mutations (mostly germline), and 11 patients with no SDH mutations. Compared with patients with SDHA-positive GISTs, those with SDHA-negative GISTs had an older median age (34 vs. 21 y), lower female to male ratio (1.8 vs. 3.1) but similar mitotic counts and median tumor sizes, with a slow course of disease in most cases, despite a slightly higher rate of liver metastases. SDHA-negative GISTs comprise approximately 30% of SDHB-negative/SDH-deficient GISTs, and SDHA loss generally correlates with SDHA mutations.

Project description:BackgroundSomatic cytidine mutations in normal mammalian nuclear genes occur during antibody diversification in B lymphocytes and generate an isoform of apolipoprotein B in intestinal cells by RNA editing. Here, I describe that succinate dehydrogenase (SDH; mitochondrial complex II) subunit B gene (SDHB) is somatically mutated at a cytidine residue in normal peripheral blood mononuclear cells (PBMCs) and T-cell acute leukemia. Germ line mutations in the SDHB, SDHC or SDHD genes cause hereditary paraganglioma (PGL) tumors which show constitutive activation of homeostatic mechanisms induced by oxygen deprivation (hypoxia).Principal findingsTo determine the prevalence of a mutation identified in the SDHB mRNA, 180 samples are tested. An SDHB stop-codon mutation c.136C>T (R46X) is present in a significant fraction (average = 5.8%, range = less than 1 to 30%, n = 52) of the mRNAs obtained from PBMCs. In contrast, the R46X mutation is present in the genomic DNA of PBMCs at very low levels. Examination of the PBMC cell-type subsets identifies monocytes and natural killer (NK) cells as primary sources of the mutant transcript, although lesser contributions also come from B and T lymphocytes. Transcript sequence analyses in leukemic cell lines derived from monocyte, NK, T and B cells indicate that the mutational mechanism targeting SDHB is operational in T-cell acute leukemia. Accordingly, substantial levels (more than 3%) of the mutant SDHB transcripts are detected in five of 20 primary childhood T-cell acute lymphoblastic leukemia (T-ALL) bone marrow samples, but in none of 20 B-ALL samples. In addition, distinct heterozygous SDHB missense DNA mutations are identified in Jurkat and TALL-104 cell lines which are derived from T-ALLs.ConclusionsThe identification of a recurrent, inactivating stop-codon mutation in the SDHB gene in normal blood cells suggests that SDHB is targeted by a cytidine deaminase enzyme. The SDHB mutations in normal PBMCs and leukemic T cells might play a role in cellular pre-adaptation to hypoxia.

Dataset Information

Familial neonatal isolated cardiomyopathy caused by a mutation in the flavoprotein subunit of succinate dehydrogenase.

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Familial neonatal isolated cardiomyopathy caused by a mutation in the flavoprotein subunit of succinate dehydrogenase.

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