MOLECULAR GENETICS OF THERMOGENESIS

描述（由申请人提供）：对啮齿动物的调查令人信服地表明，增加非寒颤产热（NTS）对减少肥胖非常有效。然而，我们对动物模型或人类体内调节体重的产热机制知之甚少。虽然儿童有活跃的NTS，但它并不被认为对成人的产热有显著贡献。寻找替代产热机制的主要障碍是NTS在啮齿动物模型中的主导和普遍作用。由于其高表达，NTS阻碍了对其他产热机制的独立分析。本研究旨在通过在NTS必需的解偶联蛋白（UCP1）失活的小鼠中创建的遗传模型来确定替代的产热机制。与预期相反，这些小鼠对饮食肥胖表现出更强的抵抗力，这表明其他产热机制比NTS消耗更多的卡路里来调节体温。本课题将利用这些小鼠的特点来指导实验，以确定不依赖于ucp1的产热机制。Specific Aim 1将使用基因表达的微阵列分析和线粒体蛋白的蛋白质组学来寻找在UCP1缺陷小鼠对寒冷的缓慢适应过程中表达改变的基因。Specific Aim 2将把UCP1缺陷与引起瘦素、儿茶酚胺和脂肪酸氧化缺陷的突变结合起来，通过测量脂肪、能量消耗和已知反映脂肪酸氧化状态的基因表达的变化，确定这些系统是否参与了产热的替代机制。特异性目的3旨在定位导致杂交小鼠产热杂种优势的遗传位点，目的是确定替代产热基因。这一目标依赖于在缺乏UCP1的杂交后代中使用单核苷酸多态性标记的高通量定位策略。因此，三种独立的实验方法专注于识别可能对儿童和成人肥胖发展产生重大影响的产热基因。在基因鉴定的同时，实验将提供这些基因如何影响过度肥胖发展的表型信息。

DESCRIPTION (provided by applicant): Investigations in rodents have convincingly shown that increases in non-shivering thermogenesis (NTS) are extremely effective in reducing obesity. However, we know very little about alternative mechanisms of thermogenesis that regulate body weight in either animal models or in humans. Although children have active NTS, it is not thought to contribute significantly to thermogenesis in the adult human. A major obstacle to finding alternative thermogenic mechanisms has been the dominant and pervasive effects of NTS in rodent models. Because of its high expression NTS prevents the independent analysis of alternative thermogenic mechanisms. This proposal seeks to identify alternative thermogenic mechanisms by making use of a genetic model created in mice in which the uncoupling protein (UCP1), which is essential for NTS, has been inactivated. Contrary to expectations these mice show increased resistance to dietary obesity, suggesting that alternative mechanisms of thermogenesis consume more calories to regulate body temperature than does NTS. This proposal will take advantage of characteristics of these mice to guide experiments to identify UCP1-independent thermogenic mechanisms. Specific Aim 1 will use microarray analysis of gene expression and proteomics of mitochondrial proteins to find genes with altered expression during the slow adaptation of UCP1 deficient mice to the cold. Specific Aim 2 will combine UCP1 deficiency with mutants causing leptin, catecholamine and fatty acid oxidation deficiency to determine whether these systems are involved in alternative mechanisms of thermogenesis by measuring adiposity, energy expenditure and changes in the expression of genes known to reflect the state of fatty acid oxidation. Specific Aim 3 seeks to map genetic loci that cause thermogenic heterosis in hybrid mice with the goal of identifying alternative thermogenic genes. This aim depends on the high throughput mapping strategies with single nucleotide polymorphic markers in intercross progeny that are deficient in UCP1. Thus, three independent experimental approaches are focused on identifying thermogenic genes that could have a significant impact on the development of obesity in both children and adults. Concurrent with gene identification, the experiments will provide phenotypic information on how these genes affect the development of excessive adiposity.