ApoA-I Helical Domains and Cardiovascular Aging

ApoA-I 螺旋结构域与心血管衰老

• 批准号: 6829522
• 负责人: JOHN K BIELICKI
• 金额: $ 7.82万
• 依托单位: UNIVERSITY OF CALIF-LAWRENC BERKELEY LAB
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6829522
• 关键词: aging; antiatherogenic agent; antioxidants; apolipoproteins; atherosclerosis; atherosclerotic plaque; cardiovascular function; cell line; cholesterol; clinical research; genetically modified animals; human tissue; immunocytochemistry; inflammation; intermolecular interaction; laboratory mouse; lipid transport; membrane transport proteins; molecular pathology; protein isoforms; protein structure function

DESCRIPTION (provided by applicant): Cardiovascular and Cerebrovascular aging. Aging is associated with the development of atherosclerosis resulting from the deposition of cholesterol in the artery wall and the induction of oxidative events that sustain vascular inflammation. Apolipoprotein (apo) A-I, the major plasma apolipoprotein, is equipped to combat atherosclerosis by mediating the efflux of cholesterol from macrophage foam-cells. The process of cellular cholesterol efflux constitutes the rate-limiting step in the anti-atherogenic reverse cholesterol transport (RCT) pathway. It is not known whether stimulation of RCT is sufficient to attenuate the chronic induction of key mediators that sustain vascular inflammation and atherosclerosis during aging. This issue is important for devising new strategies for the treatment of cardiovascular disease. The development of new therapeutic strategies requires the identification of the helical segments of apoA-I that initiate RCT by mediating cellular cholesterol efflux. Cellular cholesterol efflux mediated by apoA-I is dependent on the ATP-binding cassette transporter A1 (ABCA1) which is down regulated via a degradation pathway. One goal of the proposed studies is to identify the helical structural elements of apoA-I that prevent ABCA1 degradation and mediate cholesterol efflux in an ABCA1-dependent manner. This will be achieved using synthetic peptides based on apoA-I amphipathic or alpha-helices. Recently, a cysteine-bearing variant of apoA-I, i.e. apoA-I(Milano), was found to be a potent inhibitor of lipid peroxidation; thus, the cysteine mutation endows the cholesterol efflux mediating apoA-I with antioxidant capability. The mechanistic basis for the antioxidant activity of apoA-I(Milano) will be elucidated in proposed studies. It is hypothesized that apoA-I(Milano) possesses chain-breaking antioxidant on phospholipid surfaces due to the presence of a free thiol located at the lipid-water interface of an amphipathic alpha-helix. Synthetic peptides that mediate cholesterol efflux and stabilize ABCA1 will be developed with and without apoA-I(Milano)-like antioxidant activity. In vivo studies will be conducted to test whether a peptide with antioxidant activity plus cholesterol efflux-mediating properties is more effective than a peptide that mediates cholesterol efflux alone in preventing the induction of key mediators that sustain vascular inflammation and atherosclemsis in aging mice. These studies are relevant for devising novel strategies to combat cardiovascular aging.

描述（由申请人提供）：心血管和脑血管衰老。衰老与动脉粥样硬化的发生有关，动脉粥样硬化是由于胆固醇在动脉壁上的沉积以及维持血管炎症的氧化事件的诱导而引起的。载脂蛋白 (apo) A-I 是主要的血浆载脂蛋白，能够通过介导巨噬细胞泡沫细胞中胆固醇的流出来对抗动脉粥样硬化。细胞胆固醇流出过程构成抗动脉粥样硬化反向胆固醇转运（RCT）途径中的限速步骤。目前尚不清楚 RCT 的刺激是否足以减弱衰老过程中维持血管炎症和动脉粥样硬化的关键介质的慢性诱导。这个问题对于制定治疗心血管疾病的新策略非常重要。新治疗策略的开发需要鉴定 apoA-I 的螺旋片段，该螺旋片段通过介导细胞胆固醇流出来启动 RCT。 apoA-I 介导的细胞胆固醇流出依赖于 ATP 结合盒转运蛋白 A1 (ABCA1)，该蛋白通过降解途径下调。拟议研究的一个目标是确定 apoA-I 的螺旋结构元件，这些元件可防止 ABCA1 降解并以 ABCA1 依赖性方式介导胆固醇流出。这将通过使用基于 apoA-I 两亲性或 α 螺旋的合成肽来实现。最近，apoA-I 的半胱氨酸变体，即 apoA-I(Milano)，被发现是脂质过氧化的有效抑制剂；因此，半胱氨酸突变赋予介导apoA-I的胆固醇流出具有抗氧化能力。 apoA-I(Milano) 的抗氧化活性的机制基础将在拟议的研究中得到阐明。据推测，由于位于两亲性 α 螺旋的脂质-水界面处存在游离硫醇，apoA-I(Milano) 在磷脂表面具有断链抗氧化剂。将开发具有或不具有 apoA-I(Milano) 样抗氧化活性的合成肽，以介导胆固醇流出并稳定 ABCA1。将进行体内研究，以测试具有抗氧化活性和胆固醇流出介导特性的肽是否比单独介导胆固醇流出的肽更有效地预防衰老小鼠中维持血管炎症和动脉粥样硬化的关键介质的诱导。这些研究对于制定对抗心血管衰老的新策略相关。