Phosphatidylinositol Metabolism and Trafficking in Atherosclerosis and Inflammation

PIP 2是一种微量磷脂（PL），在多种细胞功能中发挥重要作用，但PIP 2在动脉粥样硬化和Nlrp 3/ IL-1β炎性体通路中的作用尚不清楚。我以前已经表明，ABCA 1也作为磷脂酰肌醇4，5-二磷酸（PIP 2）flopppase，运输PIP 2从内到外小叶的质膜。ABCA 1是一种细胞胆固醇流出转运蛋白，通过从细胞中流出过量的脂质/胆固醇并阻断促炎途径，在预防动脉粥样硬化和炎症方面发挥着重要作用。具有Abca 1突变的人类患者患有过早的动脉粥样硬化，并且Ldlr KO小鼠中ABCA 1/G1的巨噬细胞特异性敲除促进动脉粥样硬化和斑块炎症。CANTOS试验强调了促炎性Nlrp 3/IL-1β通路在动脉粥样硬化中的作用，表明抗IL-1β治疗符合主要试验终点，即心脏病发作、卒中和心血管死亡复合终点的减少。Gasdermin D（GsdmD）是一种新发现的炎性小体底物，它与质膜上的PIP 2结合后发生寡聚化，形成释放成熟IL-1β的孔道。拟议的研究将揭示PIP 2在这些途径中的新作用，并可能为预防心血管疾病（CVD）的治疗干预打开新的窗口。该提案将进一步确立PIP 2作为细胞胆固醇流出的主要调节剂，并鉴定PIP 2翻转酶（将PIP 2从质膜的外叶转运到内叶的P4型ATP酶），其进而调节胆固醇流出和炎症。该提案将确定GsdmD在动脉粥样硬化，逆转胆固醇转运（RCT）和逆转炎症对RCT的负面影响中的作用。该提议的三个主要目标是：1）确定PIP 2作为主要的细胞胆固醇流出调节剂，2）鉴定和表征PIP 2翻转酶并确定P4型ATP酶在胆固醇流出和炎症中的作用，和3）确定Gasdermin D在动脉粥样硬化和RCT中的作用。

PIP2 is a minor phospholipid (PL) and plays a critical role in variety of cellular functions but the role of PIP2 in atherosclerosis and Nlrp3/ IL-1β inflammasome pathway is not well characterized. I have previously shown that ABCA1 also functions as a phosphatidylinositol 4, 5-bisphosphate (PIP2) floppase, transporting PIP2 from the inner to the outer leaflet of the plasma membrane. ABCA1, a cellular cholesterol efflux transporter, plays a major role in preventing atherosclerosis and inflammation by effluxing excess lipids/cholesterol from cells and by blocking pro-inflammatory pathways. Human patients with mutations in Abca1 suffer from premature atherosclerosis and macrophage specific knockout of ABCA1/G1 in Ldlr KO mice promotes atherosclerosis and plaque inflammation. The role of pro-inflammatory Nlrp3/IL-1β pathway in atherosclerosis was highlighted by CANTOS trial showing that anti-IL-1β therapy met the primary trial endpoint, a reduction in a composite of heart attack, stroke and cardiovascular death. Recent studies have shown that, Gasdermin D (GsdmD), a newly discovered substrate of inflammasome, binds to PIP2 on plasma membrane and oligomerize, generating pores for releasing mature IL-1β. The proposed studies will unravel the novel roles of PIP2 in these pathways and may open new windows for therapeutic intervention to prevent cardiovascular disease (CVD). This proposal will further establish PIP2 as a major regulator of cellular cholesterol efflux and identify the PIP2 flippases (P4-type ATPases that transport PIP2 from the outer to the inner leaflet of the plasma membrane) that in turn regulate cholesterol efflux and inflammation. The proposal will identify the role of GsdmD in atherosclerosis, reverse cholesterol transport (RCT), and in reversing the negative effects of inflammation on RCT. The three main goals of this proposal are; 1) to establish PIP2 as a major cellular cholesterol efflux regulator, 2) to identify and characterize the PIP2 flippase and determine role of P4-type ATPases in cholesterol efflux and inflammation, and 3) to determine role of Gasdermin D in atherosclerosis and RCT.