Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, China.
Department of inspection and certification, China Certification and Inspection Group Hubei Co., Ltd., Wuhan 430030, China.
Nutrients. 2022 Feb 4;14(3):658. doi: 10.3390/nu14030658.
Chronic alcohol consumption retards lipophagy, which contributes to the pathogenesis of liver steatosis. Lipophagy-related Rab7 has been presumed as a crucial regulator in the progression of alcohol liver disease despite elusive mechanisms. More importantly, whether or not hepatoprotective quercetin targets Rab7-associated lipophagy disorder is unknown. Herein, alcoholic fatty liver induced by chronic-plus-single-binge ethanol feeding to male C57BL/6J mice was manifested by hampering autophagosomes formation with lipid droplets and fusion with lysosomes compared with the normal control, which was normalized partially by quercetin. The GST-RILP pulldown assay of Rab7 indicated an improved GTP-Rab7 as the quercetin treatment for ethanol-feeding mice. HepG2 cells transfected with CYP2E1 showed similar lipophagy dysfunction when exposed to ethanol, which was blocked when cells were transfected with siRNA-Rab7 in advance. Ethanol-induced steatosis and autophagic flux disruption were aggravated by the Rab7-specific inhibitor CID1067700 while alleviated by transfecting with the Rab7 plasmid, which was visualized by immunofluorescence co-localization analysis and mCherry-GFP-LC3 transfection. Furthermore, TBC1D5, a Rab GTPase-activating protein for the subsequent normal circulation of Rab7, was downregulated after alcohol administration but regained by quercetin. Rab7 circulation retarded by ethanol and corrected by quercetin was further revealed by fluorescence recovery after photobleaching (FRAP). Altogether, quercetin attenuates hepatic steatosis by normalizing ethanol-imposed Rab7 turnover disorders and subsequent lipophagy disturbances, highlighting a novel mechanism and the promising prospect of quercetin-like phytochemicals against the crucial first hit from alcohol.
慢性酒精摄入会延缓脂噬作用，这有助于肝脂肪变性的发病机制。尽管机制尚不清楚，但与脂噬作用相关的 Rab7 被认为是酒精性肝病进展的关键调节因子。更重要的是，是否具有肝保护作用的槲皮素针对 Rab7 相关的脂噬作用紊乱尚不清楚。本文中，通过慢性加单次 binge 乙醇喂养雄性 C57BL/6J 小鼠诱导的酒精性脂肪肝，与正常对照组相比，自噬体形成受到阻碍，与溶酶体融合的脂质滴减少，而槲皮素部分恢复了这种现象。GST-RILP 下拉实验表明 Rab7 的 GTP-Rab7 增加，这是由于乙醇喂养的小鼠用槲皮素处理所致。转染 CYP2E1 的 HepG2 细胞在暴露于乙醇时也表现出类似的脂噬作用障碍，当细胞预先转染 Rab7 的 siRNA 时，这种障碍被阻断。Rab7 特异性抑制剂 CID1067700 加重了乙醇诱导的脂肪变性和自噬流破坏，而 Rab7 质粒的转染则减轻了这种破坏，这通过免疫荧光共定位分析和 mCherry-GFP-LC3 转染得到证实。此外，Rab GTPase 激活蛋白 TBC1D5 在酒精给药后下调，但被槲皮素恢复。乙醇延缓 Rab7 循环并被槲皮素纠正的现象进一步通过光漂白后荧光恢复（FRAP）得到揭示。总之，槲皮素通过恢复乙醇引起的 Rab7 周转率紊乱和随后的脂噬作用紊乱来减轻肝脂肪变性，突出了一种新的机制，以及槲皮素类植物化学物质对酒精关键首次打击的有希望的前景。
