Effects of A1AT on PCSK9 expression and function

项目摘要 心脏病是美国男性和女性死亡和残疾的主要原因 占每年死亡人数的40%高胆固醇水平，尤其是低密度脂蛋白（LDL），是众所周知的 这种疾病的危险因素。LDL颗粒的关键致动脉粥样硬化特性涉及 动脉粥样硬化斑块由于肝脏LDL受体是血浆LDL-胆固醇的主要决定因素， 水平，更好地了解控制LDL受体表达的调节机制， 具有本质意义前蛋白转化酶枯草杆菌蛋白酶/kexin-9（PCSK-9）是一种众所周知的血浆LDL的间接调节剂 通过控制在质膜上表达的LDL受体分子的数量来降低LDL水平。初步 我们实验室的研究表明，α-1-抗胰蛋白酶（A1 AT）在培养基中直接与PCSK 9相互作用， 细胞，并阻止体外PCSK 9/LDL受体复合物的形成。A1 AT还促进了 从细胞培养基中去除PCSK 9，但这种去除的机制目前尚不清楚。长期 本研究项目的目的是描述A1 AT依赖性的分子机制， PCSK 9的表达和功能。该项目的主要影响将是确定一个 内源性PCSK 9抑制剂可能导致诊断测试的发展，以识别患者并提供 为他们提供最好和最安全的治疗方案。此外，这种抑制剂可能成为一种替代治疗， 对目前可用的抗胆固醇血症药物不耐受的患者。在此基础上 假设LDL受体蛋白的水平可以结合LDL并将其从循环中清除 被调节为A1 AT和PCSK 9之间的比率。在本研究提案中，我们将检验这一假设 通过以下具体目的：目的I：寻找A1 AT和PCSK 9表达的共同调节因子;目的 II：检测A1 AT中影响PCSK 9表达/功能的关键蛋白区域; 参与PCSK 9/A1 AT复合物内化的途径。

PROJECT SUMMARY Heart disease is the principal cause of death and disability for both men and women in the US accounting for 40% of all annual deaths. A high cholesterol level, especially of low density lipoprotein (LDL), is a well-known risk factor for this disease. The key atherogenic property of LDL particles involves the formation of atherosclerotic plaques. Since the hepatic LDL receptor is the major determinant of plasma LDL-cholesterol levels, a greater understanding of the regulatory mechanisms that control the expression of the LDL receptor is essential. Proprotein convertase subtilisin/kexin-9 (PCSK9) is a well-known indirect regulator of plasma LDL levels by controlling the number of LDL receptor molecules expressed at the plasma membrane. Preliminary studies in our laboratory suggest that alpha-1-antitrypsin (A1AT) directly interacts with PCSK9 in the medium of cells and prevents the formation of PCSK9/LDL receptor complexes in vitro. A1AT also promotes the removal of PCSK9 from the medium of the cells, but the mechanism for this removal is currently unknown. The long-term objective of this research project is to characterize the molecular mechanisms involved in the A1AT-dependent regulation of PCSK9 expression and function. The major impact of this project will be the identification of an endogenous inhibitor of PCSK9 could lead to the development of diagnostic tests to identify patients and provide them with the best and safest treatment options. Also, this inhibitor could become an alternative treatment for patients that develop intolerance to currently available anticholesterolemic drugs. Based on this, we hypothesized that the levels of LDL receptor protein that is available to bind and remove LDL from the circulation are conditioned to the ratio between A1AT and PCSK9. In this research proposal, we will test this hypothesis through the following specific aims: Aim I: To find common regulators of A1AT and PCSK9 expression; Aim II: To detect critical protein regions in A1AT that influences PCSK9 expression/function; Aim III: To identify the pathway(s) involved in the internalization of PCSK9/A1AT complexes.