Zhejiang University School of Medicine, Hangzhou, 310058, China.
Key Laboratory of Integrated Oncology and Intelligent Medicine of Zhejiang Province, Hangzhou, 310006, China.
J Transl Med. 2023 Oct 19;21(1):739. doi: 10.1186/s12967-023-04564-y.
Hepatic ischemia-reperfusion (IR) injury is the primary reason for complications following hepatectomy and liver transplantation (LT). Insulin-induced gene 2 (Insig2) is one of several proteins that anchor the reticulum in the cytoplasm and is essential for metabolism and inflammatory responses. However, its function in IR injury remains ambiguous.
Insig2 global knock-out (KO) mice and mice with adeno-associated-virus8 (AAV8)-delivered Insig2 hepatocyte-specific overexpression were subjected to a 70% hepatic IR model. Liver injury was assessed by monitoring hepatic histology, inflammatory responses, and apoptosis. Hypoxia/reoxygenation stimulation (H/R) of primary hepatocytes and hypoxia model induced by cobalt chloride (CoCl) were used for in vitro experiments. Multi-omics analysis of transcriptomics, proteomics, and metabolomics was used to investigate the molecular mechanisms underlying Insig2.
Hepatic Insig2 expression was significantly reduced in clinical samples undergoing LT and the mouse IR model. Our findings showed that Insig2 depletion significantly aggravated IR-induced hepatic inflammation, cell death and injury, whereas Insig2 overexpression caused the opposite phenotypes. The results of in vitro H/R experiments were consistent with those in vivo. Mechanistically, multi-omics analysis revealed that Insig2 is associated with increased antioxidant pentose phosphate pathway (PPP) activity. The inhibition of glucose-6-phosphate-dehydrogenase (G6PD), a rate-limiting enzyme of PPP, rescued the protective effect of Insig2 overexpression, exacerbating liver injury. Finally, our findings indicated that mouse IR injury could be attenuated by developing a nanoparticle delivery system that enables liver-targeted delivery of substrate of PPP (glucose 6-phosphate).
Insig2 has a protective function in liver IR by upregulating the PPP activity and remodeling glucose metabolism. The supplementary glucose 6-phosphate (G6P) salt may serve as a viable therapeutic target for alleviating hepatic IR.
肝缺血再灌注（IR）损伤是肝切除术和肝移植（LT）后并发症的主要原因。胰岛素诱导基因 2（Insig2）是几种将内质网锚定在细胞质中的蛋白质之一，对代谢和炎症反应至关重要。然而，其在 IR 损伤中的作用仍不清楚。
Insig2 全局敲除（KO）小鼠和腺相关病毒 8（AAV8）介导的 Insig2 肝细胞特异性过表达小鼠接受 70%肝 IR 模型。通过监测肝组织学、炎症反应和细胞凋亡来评估肝损伤。使用原代肝细胞缺氧/复氧刺激（H/R）和氯化钴（CoCl）诱导的缺氧模型进行体外实验。采用转录组学、蛋白质组学和代谢组学的多组学分析来研究 Insig2 的分子机制。
在接受 LT 和小鼠 IR 模型的临床样本中，肝 Insig2 表达明显降低。我们的研究结果表明，Insig2 耗竭显著加重了 IR 诱导的肝炎症、细胞死亡和损伤，而 Insig2 过表达则导致相反的表型。体外 H/R 实验的结果与体内结果一致。机制上，多组学分析表明 Insig2 与增加抗氧化戊糖磷酸途径（PPP）活性有关。葡萄糖-6-磷酸脱氢酶（G6PD），PPP 的限速酶的抑制剂，挽救了 Insig2 过表达的保护作用，加重了肝损伤。最后，我们的研究结果表明，通过开发一种能够实现 PPP （葡萄糖 6-磷酸）的肝靶向递药的纳米颗粒递药系统，可以减轻小鼠 IR 损伤。
Insig2 通过上调 PPP 活性和重塑葡萄糖代谢在肝 IR 中发挥保护作用。补充葡萄糖 6-磷酸（G6P）盐可能是缓解肝 IR 的可行治疗靶点。
