血管生成素样蛋白3通过调节apoA-I代谢改善HDL功能的机制

Angiopoietin like protein 3 (ANGPTL3) is specifically produced by hypatocytes and then secreted into circulation. ANGPTL3 inhibits lipoprotein lipase to regulate lipid metabolism. High density lipoprotein (HDL) and apoA-I which is the main functional protein of HDL have multiple anti-atherosclerotic roles. HDL function and apoA-I level were decreased in T2DM patients compared with non-diabetic participants. We reported that the peripheral blood ANGPTL3 was positively correlated with apoA-I and HDL function in non-diabetic participants. Our previous study found that ANGPTL3 was present in HDL. ANGPTL3 combined with apoA-I by co-immunoprecipitation and mass spectrometry in HDL and hepatocyte. Taken together, we hypothesize that ANGPTL3 directly combined with apoA-I and regulates apoA-I metabolism to maintain HDL function. This study will verify the relationship of ANGPTL3 with apoA-I level, HDL metabolism and function in mice of over-expression and knock out ANGPTL3. We will clarify the binding sequence of ANGPTL3 and apoA-I, then construct regional sequence mutation of ANGPTL3 to verify ANGPTL3 regulating the metabolism of apoA-I through interacting with apoA-I in live. This study will reveal a new mechanism of the regulation of HDL function. This study will provide a basis for prevention and treatment of cardiovascular complications in T2DM patients.

血管生成素样蛋白3（ANGPTL3）由肝细胞分泌入血，抑制脂蛋白酯酶调节脂代谢。高密度脂蛋白（HDL）和其主要功能成分apoA-I具有抗动脉粥样硬化作用，在2型糖尿病（T2DM）患者apoA-I水平和HDL功能均下降。我们前期报道正常人外周血ANGPTL3与apoA-I和HDL功能均呈正相关。通过免疫共沉淀和质谱分析，我们发现ANGPTL3在肝细胞与HDL中都与apoA-I结合。由此提出假设：ANGPTL3通过与apoA-I结合并抑制apoA-I降解，进而维持HDL功能。本课题将在野生、ANGPTL3过表达和ANGPTL3-/-小鼠确认ANGPTL3与apoA-I代谢、HDL 功能的关系；明确ANGPTL3与apoA-I的结合序列，通过构建结合区域序列突变揭示在HDL和肝脏中ANGPTL3抑制apoA-I降解的机制。本研究将揭示HDL功能调节的新机制，为T2DM心血管并发症的防治提供依据。

2型糖尿病(type 2 diabetic mellitus, T2DM)患者的心血管病发生率比非糖尿病病人高2.5-4倍，死亡率高2-3倍，是糖尿病患者最主要的致死原因。与正常对照相比，T2DM患者的HDL-c和HDL功能都降低。因此，如何提高HDL水平和功能是T2DM患者心血管疾病预防和治疗的研究热点。血管生成素样蛋白3（ANGPTL3）由肝细胞分泌入血，抑制脂蛋白酯酶调节脂代谢。高密度脂蛋白（HDL）和其主要功能成分apoA-I具有抗动脉粥样硬化作用，在2型糖尿病（T2DM）患者apoA-I水平和HDL功能均下降。我们前期报道正常人外周血ANGPTL3与apoA-I和HDL功能均呈正相关。本研究在临床样本中进一步验证ANGPTL3是HDL组分之一， T2DM患者血浆HDL中apoA-I水平显著降低；HDL具有抑制TNF-α诱导的脐静脉内皮细胞ICAM-1和VCAM-1水平的作用，并且随着HDL浓度的升高，抑制ICAM-1和VCAM-1表达的能力越强；发现18周龄db/db小鼠与8周龄相比，血浆ANGPTL3水平降低，HDL中的ANGPTL3水平也相应的降低并且HDL中apoA-I水平降低，HDL胆固醇流出功能和抑制ICAM-1和VCAM-1表达的能力也随之减弱；过表达ANGPTL3促进HDL的胆固醇流出功能和抑制炎症功能，而敲减ANGPTL3后作用相反；在HepG2细胞中，过表达apoA-I和不同剂量的ANGPTL3，发现随着ANGPTL3表达越多，apoA-I水平也更高。本研究结果提示：ANGPTL3在糖尿病人群和小鼠中对HDL功能的调节。揭示了HDL功能调节的新机制，为糖尿病相关血管并发症的预防和治疗提供理论依据。该项目根据研究计划和研究内容顺利开展，受该项目的资助，申请人以一作或者通讯作者已经发表学术论文7篇，申请人完成副高晋升，培养研究生1名。

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