MOLECULAR GENETICS OF THERMOGENESIS

描述(申请人提供)：对啮齿动物的研究令人信服地表明，增加非颤抖产热(NTS)在减少肥胖方面非常有效。然而，无论是在动物模型中还是在人类中，我们对调节体重的另一种生热机制知之甚少。虽然儿童有活跃的NTS，但它不被认为对成年人的产热有显著贡献。寻找替代生热机制的一个主要障碍是NTS在啮齿动物模型中的主导和普遍影响。由于其高表达，NTS阻碍了对替代生热机制的独立分析。这项提议试图通过利用在小鼠中创建的遗传模型来确定替代的生热机制，在该模型中，对NTS至关重要的解偶联蛋白(UCP1)已经失活。与预期相反，这些小鼠对饮食肥胖的抵抗力增强，这表明替代的生热机制比NTS消耗更多的卡路里来调节体温。这项提议将利用这些小鼠的特性来指导实验，以确定UCP1非依赖的生热机制。特定目的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发生变化的基因。具体目标2将UCP1缺乏症与导致瘦素、儿茶酚胺和脂肪酸氧化缺乏症的突变相结合，通过测量脂肪、能量消耗和反映脂肪酸氧化状态的基因表达的变化来确定这些系统是否参与了替代的产热机制。具体目标3试图定位导致杂交小鼠产热杂种优势的遗传位点，目的是识别替代的产热基因。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的发展产生重大影响的产热基因。在基因鉴定的同时，这些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.