Identification of Primate-Specific Regulatory Elements of Cholesterol Homeostasis

描述（由申请人提供）：尽管小鼠和其他非灵长类脊椎动物在研究人类脂质代谢中具有实用性，但许多人类代谢特征最好在灵长类动物中建模，特别是我们对膳食胆固醇的反应。人类和小鼠中参与胆固醇稳态的基因的差异调节被认为是这些物种之间对饮食胆固醇反应的差异的重要原因。我们以前已经表明，多个灵长类物种的序列比较是成功的，在确定灵长类动物的功能元件和补充传统的序列比较与非灵长类哺乳动物，如人类和小鼠之间。因此，本提案的目标是将多个灵长类动物序列比较与功能研究相结合，以发现影响脂质代谢的灵长类动物特异性调控元件。这将包括参与脂质代谢的几个基因的分析，重点是对核激素受体LXR-a及其靶基因的转录网络的解剖，这些基因是胆固醇稳态的关键调节因子，似乎在人类和小鼠中具有差异调节。我们将：1）通过对含有已知“脂质”基因的大基因组间隔的比较分析，鉴定和功能性表征在灵长类谱系中优先保守的调节序列; 2）鉴定和功能性表征在灵长类和非灵长类哺乳动物之间共享的已知和计算预测的调节元件中的灵长类特异性转录因子结合位点;和3）在细胞培养和体内研究中研究灵长类动物特异性调节序列对其邻近人类基因的功能，并确定它们对灵长类动物特异性表型的贡献。这些研究将为胆固醇稳态的临床相关调节提供基因组学来源的见解，并有助于我们理解灵长类动物对环境刺激的特异性反应。 小鼠虽然是人类疾病（如导致动脉粥样硬化的血脂紊乱）的有价值的模型，但与人类有许多不同之处，其直接后果是许多首次在小鼠中成功测试的药物在后来的人类临床研究中失败。在这项提案中，我们计划确定人类基因组的片段，这些片段决定了人类和小鼠之间血浆脂质代谢的差异。这种分子基因组结构的发现将为导致人类脂质紊乱的致病机制提供新的线索，有望为这种重要的人类疾病设计更好的小鼠模型。

DESCRIPTION (provided by applicant): Despite the utility of the mouse and other non-primate vertebrates in studying human lipid metabolism, many human metabolic features are best modeled in primates, particularly our response to dietary cholesterol. The differential regulation of genes involved in cholesterol homeostasis in humans and mice is believed to significantly contribute to differences in response to dietary cholesterol between these species. We have previously shown that sequence comparisons of multiple primate species are successful at identifying functional elements specific to primates and complement traditional sequence comparisons with non-primate mammals, such as between human and mouse. Accordingly, the goal of this proposal is to couple multiple primate sequence comparisons with functional studies to discover primate-specific regulatory elements impacting on lipid metabolism. This will include the analysis of several genes participating in lipid metabolism, with an emphasis on the dissection of the transcriptional network of the nuclear hormone receptor LXR-a and its target genes, crucial regulators of cholesterol homeostasis which appear to have differential regulation in human and mouse. We will: 1) identify and functionally characterize regulatory sequences preferentially conserved in the primate lineage through the comparative analysis of large genomic intervals containing known "lipid" genes; 2) identify and functionally characterize primate specific transcription factor binding sites in both known and computationally predicted regulatory elements shared between primates and non-primate mammals; and 3) investigate the function of primate-specific regulatory sequences on their neighboring human genes in cell culture and in vivo studies and determine their contribution to primate-specific phenotypes. These studies will provide genomically derived insights into the clinically relevant regulation of cholesterol homeostasis and contribute to our understanding of primate-specific responses to environmental stimuli. The mouse, while a valuable model of human diseases such as plasma lipid disorders leading to atherosclerosis, has many differences from human, with the immediate consequence that many drugs first tested successfully in mice fail in later clinical studies in humans. In this proposal, we plan to identify segments of the human genome which determine differences in plasma lipid metabolism between human and mouse. Discovery of this kind of molecular genomic structures will shed new light into the pathogenic mechanisms leading to human lipid disorders, promising to lead to the engineering of better mouse models for this important human disease.