Functional and structural correlates of PCSK9 association with lipoproteins

PCSK9 与脂蛋白关联的功能和结构相关性

• 批准号: 9335438
• 负责人: SERGIO FAZIO
• 金额: $ 53.38万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9335438
• 关键词: ANGPTL3 gene; Amino Acids; Apolipoproteins B; Binding; Binding Proteins; Biological Assay; Blocking Antibodies; Cardiovascular system; Catalytic Domain; Cholesterol; Cleaved cell; Clinical; Complex; Dyslipidemias; Enzymes; Epidermal Growth Factor; Europe; Event; Hepatocyte; Hour; Inherited; Interruption; LDL Cholesterol Lipoproteins; Laboratories; Lipoprotein (a); Lipoproteins; Low Density Lipoprotein Receptor; Low-Density Lipoproteins; Mediating; Methods; Molecular; Mutation; Myocardial Infarction; N-terminal; Pathway interactions; Physiological; Plasma; Play; Process; Production; Property; Proprotein Convertases; Proteins; Recycling; Regulation; Rest; Role; Route; Subtilisins; Surface; Syndrome; Therapeutic; Time; Work; base; cholesterol control; cholesterol trafficking; clinically relevant; cohort; inhibitor/antagonist; mutation carrier; neutralizing antibody; particle; prevent; receptor binding; receptor expression; targeted treatment; therapeutic target; uptake

Summary Proprotein convertase subtilisin kexin type 9 (PCSK9) is a circulatory protein that binds to the low-density lipoprotein receptor (LDLR), induces its degradation, and increases LDL-cholesterol (LDL-C) levels. Thus, PCSK9 is a therapeutic target to increase LDLR expression and reduce plasma LDL-C levels, and PCSK9 inhibitors have recently been approved for use in the US and Europe. Plasma PCSK9 levels are highly correlated to LDL-C levels, both because elevated PCSK9 levels increase plasma LDL levels by decreasing LDLR and because up to 40% of plasma PCSK9 is physically associated with LDL, a discovery initially made in our laboratory and later confirmed by others. Plasma PCSK9 is found in two main forms, an intact form (62 kDa) and a furin-cleaved form (55 kDa). We show that PCSK9 associated with LDL is mainly in the intact 62- kDa form, whereas the rest of plasma PCSK9 is mainly as the 55 kDa furin-cleaved fragment. The intact, LDL- associated PCSK9 seems to have an increased capacity to bind and degrade LDLR. Our preliminary results also suggest that LDL protects PCSK9 from cleavage by furin. However, it is still unclear what drives the compartmentalization of the molecular forms of circulating PCSK9, and whether there are functional correlates to this compartmentalization. Thus, we propose studies to clarify the connection between plasma PCSK9 forms, molecular drivers of their lipoprotein association, and LDLR degradation activity. Moreover, we propose to develop a high-throughput method to detect LDL-bound PCSK9 in plasma and to study PCSK9 association with other apoB-containing lipoproteins, such as Lp(a), and with intracellular apoB. Finally, we will study the mechanisms leading to the unexpectedly large time delay between the initial PCSK9-LDLR contact and the eventual degradation of the LDLR, as this seems to be due to a complex intracellular routing of PCSK9 which includes a re-secretion/recycling step. The central hypothesis of this proposal is that LDL carries a significant portion of the intact plasma PCSK9 form (62 kDa), which may behave differently in LDLR binding and degradation compared with the other major form of plasma PCSK9 (55 kDa). The results from these studies will enhance our understanding of both the physiologic role of PCSK9 association with lipoproteins and the mechanism by which PCSK9 inhibition produces therapeutic gains, and may inform alternative strategies to inhibit the effect of PCSK9 on LDLR through interruption of PCSK9 association with lipoproteins. .

概括 前蛋白转化酶枯草杆菌蛋白酶 kexin 9 型 (PCSK9) 是一种循环蛋白，可结合低密度 脂蛋白受体（LDLR），诱导其降解，并增加低密度脂蛋白胆固醇（LDL-C）水平。因此， PCSK9 是增加 LDLR 表达并降低血浆 LDL-C 水平的治疗靶点，PCSK9 抑制剂最近已被批准在美国和欧洲使用。血浆 PCSK9 水平很高 与 LDL-C 水平相关，这都是因为 PCSK9 水平升高通过降低 LDL-C 水平来增加血浆 LDL 水平 LDLR，并且由于高达 40% 的血浆 PCSK9 与 LDL 物理相关，这一发现最初是在 我们的实验室后来得到了其他人的证实。血浆 PCSK9 有两种主要形式，一种是完整形式 (62 kDa）和弗林蛋白酶切割形式（55 kDa）。我们发现与 LDL 相关的 PCSK9 主要存在于完整的 62- kDa 形式，而血浆 PCSK9 的其余部分主要是 55 kDa 弗林蛋白酶切割片段。完整的 LDL- 相关的 PCSK9 似乎具有增强的结合和降解 LDLR 的能力。我们的初步结果 还表明 LDL 可以保护 PCSK9 免受弗林蛋白酶的裂解。然而，目前尚不清楚是什么推动了 循环 PCSK9 分子形式的划分，以及是否存在功能相关性 到这种划分。因此，我们提出研究来阐明血浆 PCSK9 之间的联系 形式、脂蛋白关联的分子驱动因素以及 LDLR 降解活性。此外，我们建议 开发一种高通量方法来检测血浆中 LDL 结合的 PCSK9 并研究 PCSK9 关联 与其他含 apoB 的脂蛋白，例如 Lp(a) 以及细胞内 apoB。最后，我们将研究 导致初始 PCSK9-LDLR 接触和 LDLR 最终降解，因为这似乎是由于 PCSK9 的复杂细胞内路由所致 包括再分泌/回收步骤。该提案的中心假设是 LDL 具有显着的 完整血浆 PCSK9 形式 (62 kDa) 的一部分，其在 LDLR 结合和 与血浆 PCSK9 (55 kDa) 的其他主要形式相比的降解。这些研究的结果 将增强我们对 PCSK9 与脂蛋白关联的生理作用和 PCSK9 抑制产生治疗效果的机制，并可能为替代策略提供信息 通过中断 PCSK9 与脂蛋白的关联来抑制 PCSK9 对 LDLR 的影响。 。