Studies of Galactose Toxicity in Yeast and Human Cells

描述（由申请人提供）：人类的基本问题之一 遗传学关注的是一种特定基因的丢失或改变的机制， 疾病相关的基因产物导致疾病的病理生理学。 典型半乳糖血症（MIM #230400）是一种潜在的致命性先天性缺陷， 由于人体酶受损而导致的代谢 半乳糖-1-磷酸尿苷酰转移酶（GALT，E.C.2.7.7.10）。尽管 半乳糖的终身饮食限制，这是目前的标准， 尽管如此，大多数典型半乳糖血症患者仍会经历 学习障碍，原发性卵巢功能衰竭，以及异常的语言，生长， 和/或运动功能;这种病理学的生化基础仍然未知。 此外，尽管GALT缺乏的小鼠模型显示代谢性 异常，这些动物未能重现任何表型 观察患者的并发症。相比之下，酿酒酵母 GALT缺失表明代谢和明确的表型异常 半乳糖的影响。该项目的长期目标是定义 半乳糖血症病理生理学的潜在机制。的短期目标 所提出的工作是开发酵母的遗传和生物化学设施， 和培养的人成纤维细胞的生化设施，以确定 这些模型系统中半乳糖毒性的机制。的具体目标 这些建议是：（1）鉴定和表征参与该疾病的新基因， GALT缺陷型酵母中半乳糖毒性和抗性的途径，（2） 确定特定候选基因和代谢物在半乳糖 GALT缺陷酵母的毒性和抗性，以及（3）确定作用 特定的候选基因和代谢物的半乳糖毒性， 培养物中GALT受损的人成纤维细胞。这些研究的结果将 不仅验证了现有的假设，扩展了我们对半乳糖的基本知识， 在酵母和人类成纤维细胞的代谢，他们将确定新的候选人 并使新的假设的制定，以指导未来的研究， 半乳糖毒性在更复杂的系统，包括患者。

DESCRIPTION (provided by applicant): One of the fundamental questions in human genetics concerns the mechanism by which loss or change of a given disease-related gene product results in the pathophysiology of the disorder. Classic galactosemia (MIM# 230400) is a potentially lethal inborn error of metabolism that results from impairment of the human enzyme galactose-1-phosphate uridylyltransferase (GALT, E.C.2.7.7.10). Despite lifelong dietary restriction of galactose, which is the current standard of care, a majority of patients with classic galactosemia nonetheless experience learning disabilities, primary ovarian failure, and abnormal speech, growth, and/or motor function; the biochemical basis of this pathology remains unknown. Furthermore, although a mouse model of GALT-deficiency demonstrates metabolic abnormality, these animals have failed to recapitulate any of the phenotypic complications observed in patients. In contrast, Saccharomyces cerevisiae deleted for GALT demonstrate both metabolic and clear phenotypic abnormalities upon exposure to galactose. The long-term goal of this project is to define the underlying mechanism of pathophysiology in galactosemia. The short-term goal of the proposed work is to exploit the genetic and biochemical facility of yeast, and the biochemical facility of human fibroblasts in culture, to determine the mechanism(s) of galactose toxicity in these model systems. The Specific Aims of this proposal are: (1) to identify and characterize novel genes involved in the pathway(s) of galactose toxicity and resistance in GALT-deficient yeast, (2) to determine the roles of specific candidate genes and metabolites in galactose toxicity and resistance in GALT-deficient yeast, and (3) to determine the roles of specific candidate genes and metabolites in galactose toxicity in GALT-impaired human fibroblasts in culture. The results of these studies will not only test existing hypotheses and expand our basic knowledge of galactose metabolism in yeast and human fibroblasts, they will identify novel candidates and enable the formulation of novel hypotheses to direct future studies of galactose toxicity in more complex systems, including patients.