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 普罗蛋白转化酶枯草蛋白Kexin型9（PCSK9）是一种循环蛋白，与低密度结合 脂蛋白受体（LDLR）诱导其降解，并增加LDL-胆固醇（LDL-C）水平。因此， PCSK9是增加LDLR表达并降低等离子体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。等离子PCSK9水平高度 与LDL-C水平相关，这两者都是因为升高PCSK9水平通过降低来增加血浆LDL水平 LDLR，并且由于高达40％的等离子PCSK9与LDL物理相关，这是最初做出的发现 我们的实验室和后来得到了其他人的确认。等离子PCSK9以两种主要形式发现完整形式（62 kDa）和弗林裂开的形式（55 kDa）。我们表明，与LDL相关的PCSK9主要在完整的62-中 KDA形式，而等离子体PCSK9的其余部分主要是55 kDa furin旋转的片段。完整的LDL- 相关的PCSK9似乎具有增加和降解LDLR的能力。我们的初步结果 还表明LDL可以保护PCSK9免受Furin的裂解。但是，目前尚不清楚什么驱动 循环PCSK9的分子形式的分区化以及是否有功能相关 对此分室化。因此，我们提出的研究阐明了等离子体PCSK9之间的联系 形式，其脂蛋白关联的分子驱动因素和LDLR降解活性。而且，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）和细胞内APOB）。最后，我们将研究 导致初始PCSK9-LDLR接触与 LDLR的最终降解，因为这似乎是由于PCSK9的复杂细胞内路由 包括重新分销/回收步骤。该提议的核心假设是LDL具有重要的 完整等离子PCSK9形式（62 kDa）的一部分，在LDLR结合和 与其他主要形式的等离子PCSK9（55 kDa）相比，降解。这些研究的结果 将增强我们对PCSK9与脂蛋白的生理作用的理解 PCSK9抑制会产生治疗成就的机制，并可能为替代策略提供信息 通过中断PCSK9与脂蛋白的关联，抑制PCSK9对LDLR的影响。 。