Clinical Anatomy and Reproductive Medicine Application Institute, University of South China, Hengyang, China.
Clinical Medical Research Institute of the First Affiliated Hospital, University of South China, Hengyang, China.
Acta Biochim Biophys Sin (Shanghai). 2019 May 23;51(5):471-483. doi: 10.1093/abbs/gmz029.
Sortilin is closely associated with hyperlipidemia and the risk of atherosclerosis (AS). The role of sortilin and the underlying mechanism in peripheral macrophage are not fully understood. In this study, we investigated the effect of macrophage sortilin on ATP-binding cassette transporter A1 (ABCA1) expression, ABCA1-mediated cholesterol efflux, and aortic AS. Macrophage sortilin expression was upregulated by oxidized low-density lipoproteins (ox-LDLs) in both concentration- and time-dependent manners. Its expression reached the peak level when cells were incubated with 50 μg/ml ox-LDL for 24 h. Overexpression of sortilin in macrophage reduced cholesterol efflux, leading to an increase in intracellular total cholesterol, free cholesterol, and cholesterol ester. Sortilin was found to bind with ABCA1 protein and suppress macrophage ABCA1 expression, resulting in a decrease in cholesterol efflux from macrophages. The inhibitory effect of sortilin in cholesterol efflux was partially reversed by treatment with chloroquine, a lysosomal inhibitor. On the contrary, the ABCA1 protein level and ABCA1-mediated cholesterol efflux is increased by sortilin short hairpin RNA transfection. The fecal and biliary cholesterol 3H-sterol from cholesterol-laden mouse peritoneal macrophage was reduced by sortilin overexpression through lentivirus vector (LV)-sortilin in low-density lipoprotein receptor knockout mice, which was prevented by co-treatment with chloroquine. Treatment with LV-sortilin reduced plasma high-density lipoprotein and increased plasma ox-LDL levels. Accordingly, aortic lipid deposition and plaque area were exacerbated, and ABCA1 expression was reduced in mice in response to infection with LV-sortilin alone. These effects of LV-sortilin were partially reversed by chloroquine. Sortilin enhances lysosomal degradation of ABCA1 protein and suppresses ABCA1-mediated cholesterol efflux from macrophages, leading to foam cell formation and AS development.
Sortilin 与高血脂和动脉粥样硬化(AS)的风险密切相关。Sortilin 在周围巨噬细胞中的作用及其潜在机制尚未完全阐明。在这项研究中,我们研究了巨噬细胞 Sortilin 对 ATP 结合盒转运体 A1(ABCA1)表达、ABCA1 介导的胆固醇流出和主动脉 AS 的影响。氧化低密度脂蛋白(ox-LDL)以浓度和时间依赖性方式上调巨噬细胞 Sortilin 的表达。当细胞用 50μg/ml ox-LDL 孵育 24 小时时,其表达达到峰值。巨噬细胞 Sortilin 的过表达降低了胆固醇流出,导致细胞内总胆固醇、游离胆固醇和胆固醇酯增加。Sortilin 被发现与 ABCA1 蛋白结合并抑制巨噬细胞 ABCA1 表达,导致胆固醇从巨噬细胞中流出减少。用溶酶体抑制剂氯喹处理可部分逆转 Sortilin 在胆固醇流出中的抑制作用。相反,Sortilin 短发夹 RNA 转染可增加 ABCA1 蛋白水平和 ABCA1 介导的胆固醇流出。通过慢病毒载体(LV)-Sortilin 在低密度脂蛋白受体敲除小鼠中过表达 Sortilin,可减少载脂蛋白胆固醇小鼠腹腔巨噬细胞中的粪便和胆汁 3H-胆固醇,并用氯喹共同处理可预防这种情况。Sortilin 的治疗降低了血浆高密度脂蛋白并增加了血浆 ox-LDL 水平。因此,LV-sortilin 单独感染可降低小鼠血浆中的 ABCA1 表达,同时加剧主动脉脂质沉积和斑块面积,并减轻 ABCA1 表达。LV-sortilin 的这些作用部分被氯喹逆转。Sortilin 增强了 ABCA1 蛋白的溶酶体降解,并抑制了巨噬细胞中 ABCA1 介导的胆固醇流出,导致泡沫细胞形成和 AS 发展。