The liver plays an important role in production and metabolism of homocysteine (Hcy), which has been reported to be involved in liver injury. In our previous work, we confirm that Hcy can induce liver injury by activating endoplasmic reticulum (ER) stress. However, the underlying mechanisms remain largely unknown. In present study, we established the Hcy-induced liver injury model by feeding cbs+/− mice with high methionine diet, and found that a considerable mass of disordered arrangement of hepatocytes and enlarged space between hepatocytes were frequently occurred in the liver of cbs+/− mice, accompanied with elevated expression levels of apoptosis-related proteins. In addition, Hcy could activate ER stress both in cbs+/− mice and hepatocytes. Mechanistically, Hcy promoted the expression levels of proteasome 26S subunit non-ATPase 10 (PSMD10) in hepatocytes; and the expression of ER stress indicators and apoptosis-associated proteins were significantly suppressed when PSMD10 was silenced in hepatocytes under Hcy treatment. Moreover, bioinformatics analysis and luciferase reporter assay demonstrated that PSMD10 was a target gene of miR-212-5p. Consistently, miR-212-5p overexpression could inhibit ER stress-mediated apoptosis of hepatocytes under Hcy treatment. With the help of co-immunoprecipitation assay, we identified that the interaction between PSMD10 and GRP78 accelerated ER stress-mediated hepatic apoptosis induced by Hcy. Our findings indicate that miR-212-5p directly targets PSMD10 and subsequently activates ER stress to promote Hcy-induced apoptosis of hepatocytes. We propose that endogenous PSMD10 physically interacts with GRP78 to regulate ER stress. Our study may provide the therapeutic target for the liver injury induced by Hcy.

中文翻译：

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PSMD10和GRP78相互作用加速同型半胱氨酸诱导的内质网应激介导的肝细胞凋亡

肝脏在同型半胱氨酸 (Hcy) 的产生和代谢中起重要作用，据报道，Hcy 与肝损伤有关。在我们之前的工作中，我们证实 Hcy 可以通过激活内质网 (ER) 应激来诱导肝损伤。然而，潜在的机制在很大程度上仍然未知。在本研究中，我们通过高蛋氨酸饮食喂养cbs+/-小鼠建立Hcy诱导的肝损伤模型，发现cbs+/-肝脏中经常出现大量肝细胞排列紊乱和肝细胞间隙扩大的现象。小鼠，伴随着凋亡相关蛋白的表达水平升高。此外，Hcy 可以激活 cbs +/- 小鼠和肝细胞中的内质网应激。从机制上讲，Hcy促进了蛋白酶体26S亚基非ATP酶10（PSMD10）在肝细胞中的表达水平；在 Hcy 处理下，当 PSMD10 在肝细胞中沉默时，内质网应激指标和凋亡相关蛋白的表达受到显着抑制。此外，生物信息学分析和荧光素酶报告基因分析表明，PSMD10 是 miR-212-5p 的靶基因。一致地，miR-212-5p 过表达可以抑制 Hcy 处理下内质网应激介导的肝细胞凋亡。在免疫共沉淀试验的帮助下，我们发现 PSMD10 和 GRP78 之间的相互作用加速了 Hcy 诱导的内质网应激介导的肝细胞凋亡。我们的研究结果表明 miR-212-5p 直接靶向 PSMD10 并随后激活 ER 应激以促进 Hcy 诱导的肝细胞凋亡。我们建议内源性 PSMD10 与 GRP78 物理相互作用以调节内质网应激。我们的研究可能为Hcy诱导的肝损伤提供治疗靶点。