Genetic Screens for Mitochondrial Phenotypes in ES Cells

描述（由申请人提供）：线粒体肌病是骨骼肌疾病的重要原因，是许多线粒体疾病的常见临床特征。最近的流行病学证据表明，线粒体疾病的患病率可能高达1/8500。尽管对这些疾病的临床、生化和分子特征有重要的认识，但仅在少数病例中确定了特定的遗传病因，并且对潜在的分子发病机制仍然知之甚少。该项目的总体目标是通过在小鼠胚胎干细胞（ES）中进行遗传筛选来提供对线粒体生物学的新见解，这些细胞旨在识别对线粒体功能重要的基因，以及可能的线粒体肌病病因候选基因。通过启动子-陷阱策略诱变的ES细胞显示异常线粒体表型，将通过荧光激活细胞分选（FACS）使用线粒体质量和线粒体膜电位的荧光标记物来选择。然后通过5' RACE分析具有如FACS所指示的可再现的改变的线粒体质量和/或线粒体膜电位的克隆以鉴定改变的基因。然后将在生物化学、形态学和超微结构水平上进一步表征突变克隆。将通过候选基因cDNA转染的突变克隆的表型拯救来证明遗传特异性。通过将小鼠ES细胞的遗传易处理性与FACS的高通量表型分析能力相结合，该提议提供了一种新的、快速的方法来鉴定对哺乳动物系统中的线粒体功能非常重要的基因，该方法非常适合于研究肌肉生物学。进行本研究的环境非常适合支持申请人开发线粒体肌病和生物学研究项目。贝勒医学院以其哺乳动物遗传学而闻名，并提供最先进的流式细胞仪核心。

DESCRIPTION (provided by applicant): Mitochondrial myopathy is an important cause of skeletal muscle disease and is a common clinical feature of many mitochondrial disorders. Recent epidemiological evidence suggests that the prevalence of mitochondrial diseases may be as high as 1 in 8500. Despite important insights into the clinical, biochemical, and molecular characterization of these disorders, specific genetic etiologies have been identified in only a minority of cases, and the underlying molecular pathogenesis remains poorly understood. The overall goal of this project is to provide new insights into mitochondrial biology by performing genetic screens in mouse embryonic stem (ES) cells designed to identify genes that are important for mitochondrial function and that are possible etiological candidates for mitochondrial myopathies. ES cells mutagenized by a promoter-trap strategy that demonstrate an abnormal mitochondrial phenotype will be selected by fluorescence-activated cell sorting (FACS) using fluorescent markers for mitochondrial mass and mitochondrial membrane potential. Clones with reproducible altered mitochondrial mass and/or mitochondrial membrane potential as indicated by FACS will then be analyzed by 5' RACE to identify the altered gene. Mutant clones will then be further characterized on biochemical, morphological, and ultrastructural levels. Genetic specificity will be demonstrated by phenotypic rescue of mutant clones transfected by the cDNA of the candidate gene. By combining the genetic tractability of mouse ES cells with the high-throughput phenotyping capacity of FACS, this proposal offers a novel, rapid approach for identifying genes important for mitochondrial function in a mammalian system well-suited for studying muscle biology. The environment in which this study will be performed is uniquely suited for supporting the applicant's development of a research program in mitochondrial myopathy and biology. Baylor College of Medicine is renowned for its mammalian genetics and provides access to a state of the art FACS core.