Hepatocyte-derived MANF mitigates ethanol-induced liver steatosis in mice via enhancing ASS1 activity and activating AMPK pathway
Hepatocyte-derived MANF mitigates ethanol-induced liver steatosis in mice via enhancing ASS1 activity and activating AMPK pathway
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DOI：
10.1038/s41401-022-00920-8
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发表时间：
2022-06
影响因子：
8.2
通讯作者：
Han-yang Xu;Yan-Hong Jiao;Shi-yu Li;Xu-Hong Zhu;Sheng Wang;Yu-Yang Zhang;Yi-jun Wei;Yu-jun Shen;Wei Wang;Yu-xian Shen;Jun-Tang Shao
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文献类型：
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作者：
Han-yang Xu;Yan-Hong Jiao;Shi-yu Li;Xu-Hong Zhu;Sheng Wang;Yu-Yang Zhang;Yi-jun Wei;Yu-jun Shen;Wei Wang;Yu-xian Shen;Jun-Tang Shao
肝脏脂肪变性在酒精性肝病(ALD)的发生和发展中起着不利的作用。中脑星形胶质细胞源性神经营养因子(MANF)是一种与未折叠蛋白反应相关的进化保守蛋白。最近的研究表明，MANF在肝脏疾病中起着重要作用。在这项研究中，我们研究了MANF在乙醇诱导的脂肪变性中的作用及其潜在的机制。结果表明，慢性+单次饮酒可显著上调ALD模型小鼠肝脏MANF的表达。此外，在长期大量饮酒后，肝细胞特异性MANF基因敲除(HKO)小鼠比野生型(WT)对照组小鼠表现出更严重的肝脏脂肪变性和肝损伤。免疫沉淀-MS蛋白质组学分析表明，精氨酸琥珀酸合成酶1(ASS1)是尿素循环中的限速酶，与MANF存在于同一免疫沉淀复合体中。肝细胞特异性MANF基因敲除导致ASS1活性降低，而MANF过表达有助于增强ASS1活性。此外，HKO小鼠表现出独特的尿素循环代谢产物在肝脏中的模式，在酒精喂养后氨积累增加。已知ASS1通过在尿素循环中产生细胞内的AMP池来激活AMPK。我们还发现，在体内和体外，补充MANF显著改善了乙醇诱导的脂肪变性，这是通过激活AMPK信号通路而实现的，该通路部分依赖于ASS1。这项研究揭示了MANF通过增强ASS1活性作为维持肝脏脂质平衡的关键分子的新机制，并揭示了过量酒精暴露下脂代谢与肝脏尿素循环之间的有趣联系。
Hepatic steatosis plays a detrimental role in the onset and progression of alcohol-associated liver disease (ALD). Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an evolutionarily conserved protein related to the unfolded protein response. Recent studies have demonstrated that MANF plays an important role in liver diseases. In this study, we investigated the role of MANF in ethanol-induced steatosis and the underlying mechanisms. We showed that the hepatic MANF expression was markedly upregulated in mouse model of ALD by chronic-plus-single-binge ethanol feeding. Moreover, after chronic-plus-binge ethanol feeding, hepatocyte-specific MANF knockout (HKO) mice displayed more severe hepatic steatosis and liver injury than wild-type (WT) control mice. Immunoprecipitation-coupled MS proteomic analysis revealed that arginosuccinate synthase 1 (ASS1), a rate-limiting enzyme in the urea cycle, resided in the same immunoprecipitated complex with MANF. Hepatocyte-specific MANF knockout led to decreased ASS1 activity, whereas overexpression of MANF contributed to enhanced ASS1 activity in vitro. In addition, HKO mice displayed unique urea cycle metabolite patterns in the liver with elevated ammonia accumulation after ethanol feeding. ASS1 is known to activate AMPK by generating an intracellular pool of AMP from the urea cycle. We also found that MANF supplementation significantly ameliorated ethanol-induced steatosis in vivo and in vitro by activating the AMPK signaling pathway, which was partly ASS1 dependent. This study demonstrates a new mechanism in which MANF acts as a key molecule in maintaining hepatic lipid homeostasis by enhancing ASS1 activity and uncovers an interesting link between lipid metabolism and the hepatic urea cycle under excessive alcohol exposure.