Cholesterol-metabolizing P450s and Alzheimer's disease

描述（由申请人提供）：这是一个独立科学家奖（K 02）的申请 最近的研究结果表明，胆固醇代谢在阿尔茨海默病（AD）的病理生理学提供了一个理论基础，研究蛋白质参与维持胆固醇稳态。已知有四种细胞色素P450（P450）酶催化不同器官中胆固醇降解的第一步和关键步骤：脑中的P450 46 A1，肝中的P450 7A 1，类固醇生成组织和脑中的P450 11 A1，以及所有其他肝外组织中的P450 27 A1。该实验室的长期目标是：1）确定具有<= 25%序列同一性的四种酶如何结合非常相同的底物胆固醇，但产生不同的产物，以及2）确定它们非常不同的催化效率的分子基础，使P450 7A 1每天代谢600 mg胆固醇，而P450 46 A1每天仅代谢6-7 mg。这些结果将提供如何调节体内胆固醇代谢P450的活性，从而使外周和大脑中的胆固醇保持在正常水平的见解。我们目前的GM 62882专注于P450的7A 1和27 A1，这两种酶对大脑外的胆固醇代谢至关重要。在K 02的研究计划中，我们建议扩展我们的结构/功能研究，并研究P450的46 A1和11 A1，这些酶调节大脑中多余胆固醇的消除。职业发展计划包括与西奈山医学院阿尔茨海默病研究中心的研究人员进行合作研究，其中将涉及两项对P.I.的研究计划。将使用气相色谱-质谱法定量正常和AD受试者的人脑样本中的胆固醇代谢物水平，并使用免疫细胞化学法研究相同脑样本中P450 46 A1和11 A1以及淀粉样蛋白前体和β 3蛋白的表达。新的方法和合作研究将有助于在发展一个新的方向在P.I.的研究计划，并促进基础科学知识的应用，以预防和治疗与胆固醇代谢失衡有关的疾病。如果得到资助，释放时间和工资支持将大大提高P.I.的职业生涯中的基础科学研究，使之更医学导向。

DESCRIPTION (provided by applicant): THIS IS AN APPLICATION FOR AN INDEPENDENT SCIENTIST AWARD (K02) Recent results implicating cholesterol metabolism in the pathophysiology of Alzheimer's disease (AD) provide a rationale for studying the proteins involved in maintenance of cholesterol homeostasis. Four cytochrome P450 (P450) enzymes are known to catalyze the first and key steps in cholesterol degradation in different organs: P450 46A1 in the brain, P450 7A1 in the liver, P450 11A1 in steroidogenic tissues and the brain, and P450 27A1 in all other extrahepatic tissues. The long-term goals of this laboratory are: 1) to establish how the four enzymes that share <= 25% sequence identity bind the very same substrate, cholesterol, yet produce a different product, and 2) to determine the molecular basis for their very different catalytic efficiencies allowing P450 7A1 to metabolize 600 mg of cholesterol every day and P450 46A1 only 6-7 mg. The results will provide insight into how to modulate the activity of cholesterol-metabolizing P450s in vivo and thus maintain cholesterol at normal levels in the periphery and the brain. Our current GM62882 is focused on P450s 7A1 and 27A1, enzymes that are crucial for cholesterol catabolism outside the brain. In the Research Plan of this K02 we propose to expand our structure/function studies and investigate P450s 46A1 and 11A1, enzymes that regulate the elimination of excess cholesterol in the brain. The Career Development plan includes collaborative studies with investigators from the Alzheimer's Disease Research Center at Mount Sinai School of Medicine that will involve two techniques new to the P.I.'s research program. Gas chromatography-mass spectrometry will be used to quantify cholesterol metabolite levels in human brain samples of normal and AD-affected subjects, and immunocytochemistry to study the expression of P450s 46A1 and 11A1, as well as amyloid precursor and (3 proteins in the same brain samples. The new methodologies and collaborative studies will help in developing a new direction in the P.I.'s research program and foster application of the basic science knowledge to prevention and treatment of diseases associated with imbalances in cholesterol metabolism. If funded, the release time and salary support will significantly enhance the P.I.'s career in basic science research and make it more medically oriented.