微小RNA-33在动脉粥样硬化中调节巨噬细胞自噬
microRNA-33 Regulates Macrophage Autophagy in Atherosclerosis.
作者信息
Ouimet Mireille, Ediriweera Hasini, Afonso Milessa Silva, Ramkhelawon Bhama, Singaravelu Ragunath, Liao Xianghai, Bandler Rachel C, Rahman Karishma, Fisher Edward A, Rayner Katey J, Pezacki John P, Tabas Ira, Moore Kathryn J
机构信息
From the Marc and Ruti Bell Vascular Biology and Disease Program, Leon H. Charney Division of Cardiology, Department of Medicine (M.O., H.E., M.S.A., R.C.B., K.R., E.A.F., K.J.M.) and Division of Vascular Surgery, Department of Surgery (B.R.), New York University Medical Center; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Canada (R.S., K.J.R., J.P.P.); National Research Council of Canada, Ottawa, Ontario (R.S., J.P.P.); Departments of Medicine, Pathology and Cell Biology, Columbia University, New York (X.L., I.T.); and University of Ottawa Heart Institute, Ontario, Canada (K.J.R.).
出版信息
Arterioscler Thromb Vasc Biol. 2017 Jun;37(6):1058-1067. doi: 10.1161/ATVBAHA.116.308916. Epub 2017 Apr 20.
OBJECTIVE
Defective autophagy in macrophages leads to pathological processes that contribute to atherosclerosis, including impaired cholesterol metabolism and defective efferocytosis. Autophagy promotes the degradation of cytoplasmic components in lysosomes and plays a key role in the catabolism of stored lipids to maintain cellular homeostasis. microRNA-33 (miR-33) is a post-transcriptional regulator of genes involved in cholesterol homeostasis, yet the complete mechanisms by which miR-33 controls lipid metabolism are unknown. We investigated whether miR-33 targeting of autophagy contributes to its regulation of cholesterol homeostasis and atherogenesis.
APPROACH AND RESULTS
Using coherent anti-Stokes Raman scattering microscopy, we show that miR-33 drives lipid droplet accumulation in macrophages, suggesting decreased lipolysis. Inhibition of neutral and lysosomal hydrolysis pathways revealed that miR-33 reduced cholesterol mobilization by a lysosomal-dependent mechanism, implicating repression of autophagy. Indeed, we show that miR-33 targets key autophagy regulators and effectors in macrophages to reduce lipid droplet catabolism, an essential process to generate free cholesterol for efflux. Notably, miR-33 regulation of autophagy lies upstream of its known effects on ABCA1 (ATP-binding cassette transporter A1)-dependent cholesterol efflux, as miR-33 inhibitors fail to increase efflux upon genetic or chemical inhibition of autophagy. Furthermore, we find that miR-33 inhibits apoptotic cell clearance via an autophagy-dependent mechanism. Macrophages treated with anti-miR-33 show increased efferocytosis, lysosomal biogenesis, and degradation of apoptotic material. Finally, we show that treating atherosclerotic mice with anti-miR-33 restores defective autophagy in macrophage foam cells and plaques and promotes apoptotic cell clearance to reduce plaque necrosis.
CONCLUSIONS
Collectively, these data provide insight into the mechanisms by which miR-33 regulates cellular cholesterol homeostasis and atherosclerosis.
目的
巨噬细胞中自噬缺陷会导致促成动脉粥样硬化的病理过程，包括胆固醇代谢受损和吞噬作用缺陷。自噬促进溶酶体中细胞质成分的降解，并在储存脂质的分解代谢中起关键作用，以维持细胞内稳态。微小RNA-33（miR-33）是参与胆固醇稳态的基因的转录后调节因子，但其控制脂质代谢的完整机制尚不清楚。我们研究了miR-33对自噬的靶向作用是否有助于其对胆固醇稳态和动脉粥样硬化的调节。
方法与结果
使用相干反斯托克斯拉曼散射显微镜，我们发现miR-33会促使巨噬细胞中脂滴积累，提示脂解作用降低。对中性和溶酶体水解途径的抑制表明，miR-33通过溶酶体依赖性机制减少胆固醇动员，这意味着自噬受到抑制。实际上，我们发现miR-33靶向巨噬细胞中的关键自噬调节因子和效应器，以减少脂滴分解代谢，这是产生用于流出的游离胆固醇的重要过程。值得注意的是，miR-33对自噬的调节作用位于其对ABCA1（ATP结合盒转运蛋白A1）依赖性胆固醇流出的已知作用的上游，因为在对自噬进行基因或化学抑制后，miR-33抑制剂无法增加流出。此外，我们发现miR-33通过自噬依赖性机制抑制凋亡细胞清除。用抗miR-33处理的巨噬细胞显示出吞噬作用增加、溶酶体生物合成增加以及凋亡物质降解增加。最后，我们表明用抗miR-33治疗动脉粥样硬化小鼠可恢复巨噬细胞泡沫细胞和斑块中缺陷的自噬，并促进凋亡细胞清除以减少斑块坏死。
结论
总体而言，这些数据为miR-33调节细胞胆固醇稳态和动脉粥样硬化的机制提供了见解。
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