Zhao Qian, Xu Jun, Xia Ziqiang, Lv Xiangyin, Lou Yaling, Ye Nan, Zhu Dandan, Wang Yixiao, Zeng Yuan, Zhang Xiangting, Cai Weimin, Ying Huiya, Zhou Ruoru, Weng Tianhao, Yu Fujun
Department of Gastroenterology, Wenzhou Medical University Affiliated Dongyang Hospital, Dongyang 322100 Zhejiang, China.
Department of Gastroenterology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000 Zhejiang, China.
Biochem Pharmacol. 2025 Jun 26;240:117089. doi: 10.1016/j.bcp.2025.117089.
Metabolic dysfunction-associated steatotic liver disease (MASLD) encompasses a complex interplay of metabolic and cellular stress pathways. Disruptions in several metabolic processes, including endoplasmic reticulum (ER) stress, glutamine metabolism, and ferroptosis, are key in the initiation and progression of MASLD. Although ghrelin confers protective effects against MASLD, its mechanism of action remains unclear. This study aimed to investigate the role of ghrelin in MASLD management and lipid reduction. Male C57BL/6J mice were fed a high-fat diet (HFD) for 12 weeks to establish a chronic MASLD model. From weeks 7 to 12, the mice received intraperitoneal ghrelin (10 µg/kg) twice a week. Liver and serum samples were obtained for histological and biochemical analyses. In vitro analysis was performed using HepG2 cells. The findings revealed that ghrelin protected liver cells from oxidative stress and ferroptosis by stimulating stearoyl-CoA desaturase-1 (SCD1)-mediated lipogenesis and the ASCT2/glutaminase-1 (GLS1)/mTORC1 signaling pathway, mitigating HFD-induced hepatic injury. Notably, these protective effects of ghrelin against SCD1-mediated ferroptosis were inhibited by the GLS1-specific inhibitor, BPTES. Additionally, ghrelin exerted protective effects on liver cells in HFD-fed mice by suppressing IRE1α-XBP-1-mediated ER stress signaling. Conversely, the IRE1/XBP1s activator IXA4 diminished the protective effects of ghrelin on glutamine metabolism and ferroptosis. SCD1 deficiency resulted in mTORC1 activation, exacerbating ER stress. SCD1 modulates cellular metabolism and stress responses by regulating mTORC1 activity, forming an interactive closed-loop system. Collectively, ghrelin enhances ASCT2/mTORC1/SCD1 signaling to confer resistance to ferroptosis by inhibiting ER stress-mediated IRE1α-XBP-1 signaling, alleviating ferroptosis and lipid accumulation in the context of MASLD.
代谢功能障碍相关脂肪性肝病(MASLD)涉及代谢和细胞应激途径的复杂相互作用。包括内质网(ER)应激、谷氨酰胺代谢和铁死亡在内的几种代谢过程的紊乱是MASLD发生和发展的关键。尽管胃饥饿素对MASLD具有保护作用,但其作用机制仍不清楚。本研究旨在探讨胃饥饿素在MASLD管理和降脂中的作用。雄性C57BL/6J小鼠喂食高脂饮食(HFD)12周以建立慢性MASLD模型。从第7周到第12周,小鼠每周接受两次腹腔注射胃饥饿素(10µg/kg)。获取肝脏和血清样本进行组织学和生化分析。使用HepG2细胞进行体外分析。研究结果表明,胃饥饿素通过刺激硬脂酰辅酶A去饱和酶-1(SCD1)介导的脂肪生成和ASCT2/谷氨酰胺酶-1(GLS1)/mTORC1信号通路,保护肝细胞免受氧化应激和铁死亡,减轻HFD诱导的肝损伤。值得注意的是,胃饥饿素对SCD1介导的铁死亡的这些保护作用被GLS1特异性抑制剂BPTES抑制。此外,胃饥饿素通过抑制IRE1α-XBP-1介导的ER应激信号,对HFD喂养小鼠的肝细胞发挥保护作用。相反,IRE1/XBP1s激活剂IXA4减弱了胃饥饿素对谷氨酰胺代谢和铁死亡的保护作用。SCD1缺乏导致mTORC1激活,加剧ER应激。SCD1通过调节mTORC1活性来调节细胞代谢和应激反应,形成一个交互式闭环系统。总的来说,胃饥饿素通过抑制ER应激介导的IRE1α-XBP-1信号,增强ASCT2/mTORC1/SCD1信号,赋予对铁死亡的抗性,减轻MASLD背景下的铁死亡和脂质积累。
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