PDF(Pubmed)
Abstract：
BACKGROUND: Obesity is well-established as a significant contributor to the development of insulin resistance (IR) and diabetes, partially due to elevated plasma saturated free fatty acids like palmitic acid (PA). Grb10-interacting GYF Protein 2 (GIGYF2), an RNA-binding protein, is widely expressed in various tissues including the liver, and has been implicated in diabetes-induced cognitive impairment. Whereas, its role in obesity-related IR remains uninvestigated.
METHODS: In this study, we employed palmitic acid (PA) exposure to establish an in vitro IR model in the human liver cancer cell line HepG2 with high-dose chronic PA treatment. The cells were stained with fluorescent dye 2-NBDG to evaluate cell glucose uptake. The mRNA expression levels of genes were determined by real-time qRT-PCR (RT-qPCR). Western blotting was employed to examine the protein expression levels. The RNA immunoprecipitation (RIP) was used to investigate the binding between protein and mRNA. Lentivirus-mediated gene knockdown and overexpression were employed for gene manipulation. In mice, an IR model induced by a high-fat diet (HFD) was established to validate the role and action mechanisms of GIGYF2 in the modulation of HFD-induced IR in vivo.
RESULTS: In hepatocytes, high levels of PA exposure strongly trigger the occurrence of hepatic IR evidenced by reduced glucose uptake and elevated extracellular glucose content, which is remarkably accompanied by up-regulation of GIGYF2. Silencing GIGYF2 ameliorated PA-induced IR and enhanced glucose uptake. Conversely, GIGYF2 overexpression promoted IR, PTEN upregulation, and AKT inactivation. Additionally, PA-induced hepatic IR caused a notable increase in STAU1, which was prevented by depleting GIGYF2. Notably, silencing STAU1 prevented GIGYF2-induced PTEN upregulation, PI3K/AKT pathway inactivation, and IR. STAU1 was found to stabilize PTEN mRNA by binding to its 3\'UTR. In liver cells, tocopherol treatment inhibits GIGYF2 expression and mitigates PA-induced IR. In the in vivo mice model, GIGYF2 knockdown and tocopherol administration alleviate high-fat diet (HFD)-induced glucose intolerance and IR, along with the suppression of STAU1/PTEN and restoration of PI3K/AKT signaling.
CONCLUSIONS: Our study discloses that GIGYF2 mediates obesity-related IR by disrupting the PI3K/AKT signaling axis through the up-regulation of STAU1/PTEN. Targeting GIGYF2 may offer a potential strategy for treating obesity-related metabolic diseases, including type 2 diabetes.
METHODS: In this study, we employed palmitic acid (PA) exposure to establish an in vitro IR model in the human liver cancer cell line HepG2 with high-dose chronic PA treatment. The cells were stained with fluorescent dye 2-NBDG to evaluate cell glucose uptake. The mRNA expression levels of genes were determined by real-time qRT-PCR (RT-qPCR). Western blotting was employed to examine the protein expression levels. The RNA immunoprecipitation (RIP) was used to investigate the binding between protein and mRNA. Lentivirus-mediated gene knockdown and overexpression were employed for gene manipulation. In mice, an IR model induced by a high-fat diet (HFD) was established to validate the role and action mechanisms of GIGYF2 in the modulation of HFD-induced IR in vivo.
RESULTS: In hepatocytes, high levels of PA exposure strongly trigger the occurrence of hepatic IR evidenced by reduced glucose uptake and elevated extracellular glucose content, which is remarkably accompanied by up-regulation of GIGYF2. Silencing GIGYF2 ameliorated PA-induced IR and enhanced glucose uptake. Conversely, GIGYF2 overexpression promoted IR, PTEN upregulation, and AKT inactivation. Additionally, PA-induced hepatic IR caused a notable increase in STAU1, which was prevented by depleting GIGYF2. Notably, silencing STAU1 prevented GIGYF2-induced PTEN upregulation, PI3K/AKT pathway inactivation, and IR. STAU1 was found to stabilize PTEN mRNA by binding to its 3\'UTR. In liver cells, tocopherol treatment inhibits GIGYF2 expression and mitigates PA-induced IR. In the in vivo mice model, GIGYF2 knockdown and tocopherol administration alleviate high-fat diet (HFD)-induced glucose intolerance and IR, along with the suppression of STAU1/PTEN and restoration of PI3K/AKT signaling.
CONCLUSIONS: Our study discloses that GIGYF2 mediates obesity-related IR by disrupting the PI3K/AKT signaling axis through the up-regulation of STAU1/PTEN. Targeting GIGYF2 may offer a potential strategy for treating obesity-related metabolic diseases, including type 2 diabetes.
摘要：
背景：肥胖是胰岛素抵抗（IR）和糖尿病发展的重要因素，部分是由于血浆饱和游离脂肪酸如棕榈酸（PA）升高。Grb10相互作用GYF蛋白2（GIGYF2），一种RNA结合蛋白，在包括肝脏在内的各种组织中广泛表达，并与糖尿病引起的认知障碍有关。然而,其在肥胖相关IR中的作用仍未研究。
方法：在本研究中，我们使用棕榈酸（PA）暴露在高剂量慢性PA治疗的人肝癌细胞系HepG2中建立了体外IR模型。用荧光染料2-NBDG对细胞进行染色以评估细胞葡萄糖摄取。通过实时qRT-PCR(RT-qPCR)测定基因的mRNA表达水平。采用蛋白质印迹法检查蛋白质表达水平。RNA免疫沉淀（RIP）用于研究蛋白质和mRNA之间的结合。慢病毒介导的基因敲低和过表达用于基因操作。在老鼠身上,建立了高脂饮食（HFD）诱导的IR模型，以验证GIGYF2在体内调节HFD诱导的IR中的作用和作用机制。
结果：在肝细胞中，高水平的PA暴露强烈触发肝脏IR的发生，表现为葡萄糖摄取减少和细胞外葡萄糖含量升高。这明显伴随着GIGYF2的上调。沉默GIGYF2改善PA诱导的IR并增强葡萄糖摄取。相反，GIGYF2过表达促进IR,PTEN上调,和AKT失活。此外,PA诱导的肝IR引起STAU1的显着增加，这可以通过消耗GIGYF2来防止。值得注意的是,沉默STAU1可防止GIGYF2诱导的PTEN上调，PI3K/AKT通路失活,和IR。发现STAU1通过结合其3'UTR来稳定PTENmRNA。在肝细胞中，生育酚治疗抑制GIGYF2表达并减轻PA诱导的IR。在体内小鼠模型中，GIGYF2敲低和生育酚给药缓解高脂饮食（HFD）诱导的葡萄糖不耐受和IR，随着STAU1/PTEN的抑制和PI3K/AKT信号的恢复。
结论：我们的研究表明，GIGYF2通过上调STAU1/PTEN来破坏PI3K/AKT信号轴，从而介导肥胖相关的IR。靶向GIGYF2可能为肥胖相关代谢性疾病的治疗提供潜在的策略。包括2型糖尿病。
方法：在本研究中，我们使用棕榈酸（PA）暴露在高剂量慢性PA治疗的人肝癌细胞系HepG2中建立了体外IR模型。用荧光染料2-NBDG对细胞进行染色以评估细胞葡萄糖摄取。通过实时qRT-PCR(RT-qPCR)测定基因的mRNA表达水平。采用蛋白质印迹法检查蛋白质表达水平。RNA免疫沉淀（RIP）用于研究蛋白质和mRNA之间的结合。慢病毒介导的基因敲低和过表达用于基因操作。在老鼠身上,建立了高脂饮食（HFD）诱导的IR模型，以验证GIGYF2在体内调节HFD诱导的IR中的作用和作用机制。
结果：在肝细胞中，高水平的PA暴露强烈触发肝脏IR的发生，表现为葡萄糖摄取减少和细胞外葡萄糖含量升高。这明显伴随着GIGYF2的上调。沉默GIGYF2改善PA诱导的IR并增强葡萄糖摄取。相反，GIGYF2过表达促进IR,PTEN上调,和AKT失活。此外,PA诱导的肝IR引起STAU1的显着增加，这可以通过消耗GIGYF2来防止。值得注意的是,沉默STAU1可防止GIGYF2诱导的PTEN上调，PI3K/AKT通路失活,和IR。发现STAU1通过结合其3'UTR来稳定PTENmRNA。在肝细胞中，生育酚治疗抑制GIGYF2表达并减轻PA诱导的IR。在体内小鼠模型中，GIGYF2敲低和生育酚给药缓解高脂饮食（HFD）诱导的葡萄糖不耐受和IR，随着STAU1/PTEN的抑制和PI3K/AKT信号的恢复。
结论：我们的研究表明，GIGYF2通过上调STAU1/PTEN来破坏PI3K/AKT信号轴，从而介导肥胖相关的IR。靶向GIGYF2可能为肥胖相关代谢性疾病的治疗提供潜在的策略。包括2型糖尿病。
