Kim E, Rath E M, Tsang V H M, Duff A P, Robinson B G, Church W B, Benn D E, Dwight T, Clifton-Bligh R J
Cancer GeneticsKolling Institute of Medical Research, Royal North Shore Hospital, and University of Sydney, Sydney, New South Wales, AustraliaDepartment of EndocrinologyRoyal North Shore Hospital, Sydney, New South Wales, AustraliaFaculty of PharmacyUniversity of Sydney, Sydney, New South Wales, AustraliaAustralian Nuclear Science and Technology OrganisationLucas Heights, New South Wales, Australia
Cancer GeneticsKolling Institute of Medical Research, Royal North Shore Hospital, and University of Sydney, Sydney, New South Wales, AustraliaDepartment of EndocrinologyRoyal North Shore Hospital, Sydney, New South Wales, AustraliaFaculty of PharmacyUniversity of Sydney, Sydney, New South Wales, AustraliaAustralian Nuclear Science and Technology OrganisationLucas Heights, New South Wales, Australia.
Endocr Relat Cancer. 2015 Jun;22(3):387-97. doi: 10.1530/ERC-15-0099.
Mitochondrial dysfunction, due to mutations of the gene encoding succinate dehydrogenase (SDH), has been implicated in the development of adrenal phaeochromocytomas, sympathetic and parasympathetic paragangliomas, renal cell carcinomas, gastrointestinal stromal tumours and more recently pituitary tumours. Underlying mechanisms behind germline SDH subunit B (SDHB) mutations and their associated risk of disease are not clear. To investigate genotype-phenotype correlation of SDH subunit B (SDHB) variants, a homology model for human SDH was developed from a crystallographic structure. SDHB mutations were mapped, and biochemical effects of these mutations were predicted in silico. Results of structural modelling indicated that many mutations within SDHB are predicted to cause either failure of functional SDHB expression (p.Arg27*, p.Arg90*, c.88delC and c.311delAinsGG), or disruption of the electron path (p.Cys101Tyr, p.Pro197Arg and p.Arg242His). GFP-tagged WT SDHB and mutant SDHB constructs were transfected (HEK293) to determine biological outcomes of these mutants in vitro. According to in silico predictions, specific SDHB mutations resulted in impaired mitochondrial localisation and/or SDH enzymatic activity. These results indicated strong genotype-functional correlation for SDHB variants. This study reveals new insights into the effects of SDHB mutations and the power of structural modelling in predicting biological consequences. We predict that our functional assessment of SDHB mutations will serve to better define specific consequences for SDH activity as well as to provide a much needed assay to distinguish pathogenic mutations from benign variants.
由于编码琥珀酸脱氢酶（SDH）的基因突变导致的线粒体功能障碍，与肾上腺嗜铬细胞瘤、交感和副交感神经节瘤、肾细胞癌、胃肠道间质瘤以及最近发现的垂体瘤的发生有关。种系SDH亚基B（SDHB）突变背后的潜在机制及其相关疾病风险尚不清楚。为了研究SDH亚基B（SDHB）变体的基因型-表型相关性，基于晶体结构开发了人类SDH的同源模型。对SDHB突变进行定位，并在计算机上预测这些突变的生化效应。结构建模结果表明，SDHB内的许多突变预计会导致功能性SDHB表达失败（p.Arg27*、p.Arg90*、c.88delC和c.311delAinsGG），或电子路径中断（p.Cys101Tyr、p.Pro197Arg和p.Arg242His）。将绿色荧光蛋白（GFP）标记的野生型SDHB和突变型SDHB构建体转染到HEK293细胞中，以确定这些突变体在体外的生物学结果。根据计算机预测，特定的SDHB突变导致线粒体定位受损和/或SDH酶活性受损。这些结果表明SDHB变体具有很强的基因型-功能相关性。本研究揭示了SDHB突变效应的新见解以及结构建模在预测生物学后果方面的作用。我们预测，我们对SDHB突变的功能评估将有助于更好地定义SDH活性的具体后果，并提供一种急需的检测方法，以区分致病突变和良性变体。
