CARNITINE TRANSPORTER IN HUMAN DISEASE

描述（摘自申请人摘要）：（摘自申请书 原发性肉毒碱缺乏症是一种常染色体隐性遗传疾病 是由肉毒碱运输缺陷引起的肉毒碱是必需的脂肪酸 氧化，其缺乏导致低酮性低血糖，骨骼和 可通过膳食肉毒碱预防心肌病。有机阳离子 具有核苷结合位点的转运蛋白（OCTN2）是一种高亲和力的肉毒碱 转运蛋白，其是基于其与OCTN1的同源性克隆的（其不 运输肉毒碱）。它在肉毒碱缺乏症中的作用得到了证实， 早期乳腺癌患者OCTN2无义突变的鉴定 原发性肉毒碱缺乏症。主要研究者 建议测试的假设，家庭与原发性肉毒碱缺乏症 在有机阳离子转运蛋白OCTN2中有一系列突变， 由这些引起的转运蛋白功能损害的程度 突变与临床表现的严重程度相关。测试 根据这一假设，将追求以下具体目标：1）识别 OCTN2基因在原发性肉毒碱缺乏症家族中的突变。 2)中国人错义突变的表达 检测卵巢（CHO）细胞，以确认其致病作用并表征 它们对肉毒碱运输的影响。将在以下之间建立相关性 先证者的表型和残留的肉毒碱转运蛋白活性 相对突变体3)肉毒碱相关OCTN2结构域的定义 通过评估嵌合体中肉毒碱转运的识别和转移 转运蛋白，通过在OCTNI的同源部分之间交换结构域而产生 OCTN2 4)在关键结构域中的定点突变的构建 OCTN2肉毒碱转运蛋白及其对肉毒碱作用测定 运输这项研究将描述导致原发性肝癌的突变。 肉毒碱缺乏症和阐明一类新膜的功能 转运蛋白的改变可能导致其他类型的人类疾病。

DESCRIPTION (Adapted from applicant's abstract): (From the application abstract) Primary carnitine deficiency is an autosomal recessive disorder caused by defective carnitine transport. Carnitine is essential for fatty acid oxidation, and its deficiency results in hypoketotic hypoglycemia, skeletal and heart myopathy which are preventable by dietary carnitine. The Organic Cation Transporter with Nucleoside binding site (OCTN2) is a high-affinity carnitine transporter, which was cloned based on its homology with OCTN1 (which does not transport carnitine). Its role in carnitine deficiency was confirmed by the identification of nonsense mutations in OCTN2 in patients with early presentation of primary carnitine deficiency. The principal investigator proposes to test the hypothesis that families with primary carnitine deficiency have a spectrum of mutations in the organic cation transporter OCTN2, and that the degree of functional impairment of the transporter caused by these mutations correlates with the severity of the clinical presentation. To test this hypothesis, the following specific aims will be pursued: 1) Identification of mutations in the OCTN2 gene in families with primary carnitine deficiency. 2) Expression of missense mutations identified in these patients in Chinese Hamster Ovary (CHO) cells to confirm their causative role and to characterize their effect on carnitine transport. A correlation will be established between phenotype of the proband and residual carnitine transporter activity of the relative mutant. 3) Definition of domains of OCTN2 involved in carnitine recognition and transfer by evaluating carnitine transport in chimeric transporters, created by swapping domains between homologous portions of OCTNI and OCTN2. 4) Construction of site-directed mutations in critical domains of the OCTN2 carnitine transporter and determination of their effect on carnitine transport. This research will characterize mutations responsible for primary carnitine deficiency and clarify the function of a new class of membrane transporters whose alteration may cause other types of human diseases.