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:1.3.5.1 (succinate dehydrogenase)
8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Paraganglioma are rare tumours, which develop in the paraganglionic sites of the head and the neck, and around the medulla of the adrenal gland and the sympathetic ganglions of the thoracoabdominal and pelvic regions. Their morbidity-mortality is due to the local and regional spread to the adjacent nervous and vascular structures, their hypervascularisation, the major cardiovascular complications when they are secreting tumours and the risk of recurrences and metastases. Paraganglioma can secrete catecholamines. The only curative treatment is surgical exeresis. The hereditary paraganglioma are more often multifocal, recurrent, sometimes malignant, and with an earlier occurrence than the sporadic forms. The genes responsible for the familial syndromes are the coding genes for the three sub-units of succinate dehydrogenase (SDHD, SDHB and SDHC) or mitochondrial complex II. Recent discoveries show that these genes are truly implicated in the sporadic forms of the illness and that the research for a germline mutation of a SDH gene is essential for managing patients with paraganglioma and/or pheochromocytoma and their families.
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PMID:[Hereditary paragangliomas and pheochromocytomas]. 1737 14

The mitochondrial succinate dehydrogenase (SDH) is an essential component of the electron transport chain and of the tricarboxylic acid cycle. Also known as complex II, this tetrameric enzyme catalyzes the oxidation of succinate to fumarate and reduces ubiquinone. Mutations in the human SDHB, SDHC, and SDHD genes are tumorigenic, leading to the development of several types of tumors, including paraganglioma and pheochromocytoma. The mechanisms linking SDH mutations to oncogenesis are still unclear. In this work, we used the yeast SDH to investigate the molecular and catalytic effects of tumorigenic or related mutations. We mutated Arg(47) of the Sdh3p subunit to Cys, Glu, and Lys and Asp(88) of the Sdh4p subunit to Asn, Glu, and Lys. Both Arg(47) and Asp(88) are conserved residues, and Arg(47) is a known site of cancer causing mutations in humans. All of the mutants examined have reduced ubiquinone reductase activities. The SDH3 R47K, SDH4 D88E, and SDH4 D88N mutants are sensitive to hyperoxia and paraquat and have elevated rates of superoxide production in vitro and in vivo. We also observed the accumulation and secretion of succinate. Succinate can inhibit prolyl hydroxylase enzymes, which initiate a proliferative response through the activation of hypoxia-inducible factor 1alpha. We suggest that SDH mutations can promote tumor formation by contributing to both reactive oxygen species production and to a proliferative response normally induced by hypoxia via the accumulation of succinate.
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PMID:Ubiquinone-binding site mutations in the Saccharomyces cerevisiae succinate dehydrogenase generate superoxide and lead to the accumulation of succinate. 1763 59

Gastrointestinal stromal tumors (GISTs) may be caused by germline mutations of the KIT and platelet-derived growth factor receptor-alpha (PDGFRA) genes and treated by Imatinib mesylate (STI571) or other protein tyrosine kinase inhibitors. However, not all GISTs harbor these genetic defects and several do not respond to STI571 suggesting that other molecular mechanisms may be implicated in GIST pathogenesis. In a subset of patients with GISTs, the lesions are associated with paragangliomas; the condition is familial and transmitted as an autosomal-dominant trait. We investigated 11 patients with the dyad of 'paraganglioma and gastric stromal sarcoma'; in eight (from seven unrelated families), the GISTs were caused by germline mutations of the genes encoding subunits B, C, or D (the SDHB, SDHC and SDHD genes, respectively). In this report, we present the molecular effects of these mutations on these genes and the clinical information on the patients. We conclude that succinate dehydrogenase deficiency may be the cause of a subgroup of GISTs and this offers a therapeutic target for GISTs that may not respond to STI571 and its analogs.
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PMID:Clinical and molecular genetics of patients with the Carney-Stratakis syndrome and germline mutations of the genes coding for the succinate dehydrogenase subunits SDHB, SDHC, and SDHD. 1766 67

Much attention has been focused on the hypothesis that oxidative damage plays a part in cellular and organismal aging. Oxygen is initially converted to superoxide anion (O2), one of the reactive oxygen species (ROS), by electrons mainly leaked from complex III in the electron transport system present in mitochondria, where it is the major endogenous source of ROS. We have shown that a mutation in a subunit, cytochrome b large subunit (SDHC), of complex II, also results in increasing O2 production and therefore leads to apoptosis and precocious aging in Caenorhabditis elegans. Recently, individuals with an inherited propensity for vascularized head and neck tumors (ie, paragangliomas) have been shown to possess one of several mutations in complex II. To further explore the role of oxidative stress from mitochondria on apoptosis and cancer, we established a transgenic cell line with a point mutation at the ubiquinone binding region in the SDHC gene. As expected, this mutation increased O2 production from complex II and led to excess apoptosis. Moreover, a significant fraction of the surviving cells from the apoptosis were transformed, as evidenced by increased tumor formation, after injection into mice. Oxidative stress results in damage to the cellular components including mitochondria and therefore leads to apoptosis. Furthermore, oxidative stress seems to cause mutations in DNA and leads to cancer. It is suggested that oxidative stress from mitochondria plays an important role in apoptosis, which leads to precocious aging and cancer.
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PMID:Role of oxidative stress from mitochondria on aging and cancer. 1788 13

To evaluate the prevalence of succinate dehydrogenase (SDH) B, C, and D germline mutations in a surgical series of cervical paragangliomas and to precise the characteristics of patients presenting with familial form. Among 29 patients operated on cervical paragangliomas (carotid or vagal body) at our institution between 1994 and 2007, 23 could be asked for a genetic analysis and a familial study. Clinical characteristics of patients harboring a germline SDH mutation were studied and compared with those presenting without mutation. Mutations were found in 8/23 (35%) patients, mostly in SDHD gene (6 cases), and in SDHB and SDHC gene, respectively, in one case each. Mean age at onset was significantly lower for patients with mutation (34 vs. 51.5 years, P = 0.01). In patients presenting with a mutation, 50% had a family history of paraganglioma compared with 0% for others (P = 0.008) and 87.5% had a multifocal form of paragangliomas versus 0% for others (P = 0.001). No difference was found concerning malignant forms between the two groups (12.5 vs. 13.3%). In the 16 patients who had an apparently sporadic paraganglioma, 6% had mutations in the SDH gene. A positive family history of paraganglioma and/or the presence of bilateral or multiple paragangliomas and/or an early age of onset are the main parameters associated with SDH mutations. Genetic testing should be considered for all patients with a cervical paraganglioma, even for those presenting with an apparently sporadic tumor as familial form may be such identified in 6% of cases.
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PMID:Cervical paragangliomas: is SDH genetic analysis systematically required? 1798 8

Pheochromocytomas (PHEOs) are rare neoplasms that produce catecholamines and usually arise from the adrenal medulla and are considered to be an adrenal paraganglioma (PGL). Closely related tumors of extraadrenal sympathetic and parasympathetic paraganglia are classified as extraadrenal PGLs. Most PHEOs are sporadic, but a significant percentage (approximately 25%) may be found in patients with germline mutations of genes predisposing to the development of von Hippel-Lindau disease, neurofibromatosis 1, multiple endocrine neoplasia type 1 (MEN1) and 2 (MEN2), and the PGL/PHEOs syndrome, based on the described mutations of the genes for succinate dehydrogenase subunit D (SDHD), B (SDHB), and C (SDHC). As one out of four PHEOs turns out to be a hereditary clinical entity, screening for genetic alterations is important, as it provides useful information for a rational diagnostic approach and management. This review discusses the genetics, the pathophysiology of hypertension, the clinical picture, the biochemical and imaging diagnosis, and the preferred therapeutic approach for PGLs/PHEOs. Furthermore, it emphasizes the need for genetic testing in cases with apparently sporadic PHEOs.
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PMID:Pheochromocytoma: an update on genetics and management. 1804 48

Recently, enzymes of the tricarboxylic acid (TCA) cycle have emerged as novel tumor suppressors. In particular, mutations in the nuclear-encoded subunits of succinate dehydrogenase (SDHB, SDHC, and SDHD) cause paragangliomas and pheochromocytomas. Although the mechanism(s) by which disruption of mitochondrial metabolism leads to neoplasia is largely unknown, increasing evidence points to an activation of pseudohypoxia. In this study, we have shown that silencing of SDHB using DNA-based small interfering RNA resulted in major impairments in cellular proliferation, respiration, and a corresponding shift to glycolysis. The levels of reactive oxygen species, however, were unchanged. As expected, hypoxia-inducible factor-1 alpha (HIF-1 alpha) and HIF-2alpha were up-regulated in chronically silenced cells, suggesting that a pseudohypoxic state was attained. In addition, the c-Jun amino-terminal kinase and p38 kinase stress signaling proteins were hyperphosphorylated in SDHB-silenced cells. Microarray analysis showed that >400 genes were influenced (6-fold or more up-regulation or down-regulation) by silencing of SDHB, confirming the importance of the TCA cycle in cellular metabolism. Examples of dysregulated genes included those involved in proliferation, adhesion, and the hypoxia pathway. Of interest, SDHB-silenced cells had a greater capacity to adhere to extracellular matrix components, including fibronectin and laminin, than control cells, thus suggesting a possible mechanism of tumor initiation. Although transient silencing of the HIF-1 alpha transcription factor in SDHB-silenced cells had little effect on the expression of a subset of up-regulated genes, it partially reversed the adhesion phenotype to fibronectin, pointing to a potentially important role for HIF-1 in this process.
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PMID:Cells silenced for SDHB expression display characteristic features of the tumor phenotype. 1851 64

Head and neck paragangliomas are usually asymptomatic and benign tumours arising mainly from the carotid body and the vagal, tympanic or jugular glomus. The majority of patients develop sporadic masses, and around 30% of cases harbour germline mutations in one of the succinate dehydrogenase genes: SDHB, SDHC or SDHD. In these hereditary cases, the presence of familial antecedents of the disease, multiplicity/bilaterality, young age at onset, and more recently, presence of gastrointestinal stromal tumours, are main factors to be considered. Here we describe a new mutation (c.256-257insTTT) affecting the SDHC gene in a 60-year-old-patient with a single head and neck paraganglioma, and without familial antecedents of the disease. In silico splice site analysis showed that this variant created a cryptic splice acceptor site and loss of heterozygosity (LOH) supported the pathogenic role of the mutation. Control population analyses did not detect this variant but revealed a novel SDHC polymorphism that exhibited a frequency of 0.3% (3/1020). This latter finding highlights the importance of assessing the clinical relevance of variants of unknown significance by means of analysing sufficient controls. Despite having found a germline mutation in an older, apparently sporadic patient, we consider that the high costs of analysing all susceptibility genes related to the disease support the recommendation of screening for mutations only in patients fulfilling the above criteria.
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PMID:SDHC mutation in an elderly patient without familial antecedents. 1868 55

Familial renal cell carcinoma (RCC) is a heterogeneous disorder that is most commonly caused by germline mutations in the VHL, MET, and FLCN genes or by constitutional chromosome 3 translocations. However, for many patients with familial RCC, the genetic basis of the disease is undefined. We investigated whether germline mutations in fumarate hydratase (FH) or succinate dehydrogenase subunit genes (SDHB, SDHC, SDHD) were associated with RCC susceptibility in 68 patients with no clinical evidence of an RCC susceptibility syndrome. No mutations in FH, SDHC, or SDHD were identified in probands, but 3 of the 68 (4.4%) probands had a germline SDHB mutation. Patients with a germline SDHB mutation presented with familial RCC (n = 1) or bilateral RCC (n = 2) and no personal or family history of pheochromocytoma or head and neck paraganglioma. Age at diagnosis of RCC in SDHB mutation carriers ranged from 24 to 73 years. These findings 1) demonstrate that patients with suspected inherited RCC should be examined for germline SDHB mutations, 2) suggest that all identified SDHB mutation carriers should be offered surveillance for RCC, and 3) provide a further link between familial RCC and activation of hypoxic-gene response pathways.
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PMID:Germline SDHB mutations and familial renal cell carcinoma. 1872 80

Hereditary paraganglioma (PGL) is characterised by genetic predisposition to the development of highly vascular tumours of the paraganglionic tissues and caused by germ line inactivating mutations in the SDHB, SDHC and SDHD subunits of mitochondrial succinate dehydrogenase enzyme complex (SDH; mitochondrial complex II). Recent studies have demonstrated that SDH gene mutations in germ line occur in at least 11% of non-familial head and neck paragangliomas, 8% of non-familial pheochromocytomas, 28% of malignant pheochromocytomas and 33% of extra-adrenal pheochromocytomas. An increasing amount of data suggest that PGL mutations lead to constitutive activation of hypoxia signalling pathways. Genetic and structural models suggest that SDH mutations cause an accumulation of succinate and reactive oxygen species (ROS) which might act as downstream signalling molecules that activate hypoxia inducible pathways. However, many fundamental aspects of PGL pathogenesis, including the mechanism of ROS accumulation, the imprinted transmission pattern of SDHD mutations, and the precise role of SDH in regulation of oxygen homeostasis, remain poorly understood.
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PMID:Clinical and molecular progress in hereditary paraganglioma. 1897 32


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