Correlation Engine 2.0
Clear Search sequence regions


Sizes of these terms reflect their relevance to your search.

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. 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 Ldlr-/- mice with anti-miR-33 restores defective autophagy in macrophage foam cells and plaques and promotes apoptotic cell clearance to reduce plaque necrosis. Collectively, these data provide insight into the mechanisms by which miR-33 regulates cellular cholesterol homeostasis and atherosclerosis. © 2017 American Heart Association, Inc.

Citation

Mireille Ouimet, Hasini Ediriweera, Milessa Silva Afonso, Bhama Ramkhelawon, Ragunath Singaravelu, Xianghai Liao, Rachel C Bandler, Karishma Rahman, Edward A Fisher, Katey J Rayner, John P Pezacki, Ira Tabas, Kathryn J Moore. microRNA-33 Regulates Macrophage Autophagy in Atherosclerosis. Arteriosclerosis, thrombosis, and vascular biology. 2017 Jun;37(6):1058-1067

Expand section icon Mesh Tags

Expand section icon Substances


PMID: 28428217

View Full Text