Kubota Naoto, Kubota Tetsuya, Kadowaki Takashi
Department of Metabolic Medicine, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
Division of Diabetes and Metabolism, The Institute of Medical Science, Asahi Life Foundation, Tokyo 103-0002, Japan.
Endocr J. 2025 Feb 3;72(2):149-159. doi: 10.1507/endocrj.EJ24-0192. Epub 2024 Sep 3.
The liver plays an important role in the control of glucose homeostasis. When insulin levels are low, such as in the fasting state, gluconeogenesis and glycogenolysis are stimulated to maintain the blood glucose levels. Conversely, in the presence of increased insulin levels, such as after a meal, synthesis of glycogen and lipid occurs to maintain the blood glucose levels within normal range. Insulin receptor signaling regulates glycogenesis, gluconeogenesis and lipogenesis through downstream pathways such as the insulin receptor substrate (IRS)-phosphoinositide 3 (PI3) kinase-Akt pathway. IRS-1 and IRS-2 are abundantly expressed in the liver and are thought to be responsible for transmitting the insulin signal from the insulin receptor to the intracellular effectors involved in the regulation of glucose and lipid homeostasis. Impaired insulin receptor signaling can cause hepatic insulin resistance and lead to type 2 diabetes. In the present study, we focus on a concept called "selective insulin resistance," which has received increasing attention recently: the frequent coexistence of hyperglycemia and hepatic steatosis in people with type 2 diabetes and obesity suggests that it is possible for the insulin signaling regulating gluconeogenesis to be impaired even while that regulating lipogenesis is preserved, suggestive of selective insulin resistance. In this review, we review the progress in research on the insulin actions and insulin signaling in the liver.
肝脏在葡萄糖稳态的调控中发挥着重要作用。当胰岛素水平较低时,如在空腹状态下,糖异生和糖原分解被刺激以维持血糖水平。相反,在胰岛素水平升高时,如进食后,糖原和脂质的合成发生以将血糖水平维持在正常范围内。胰岛素受体信号通过下游途径如胰岛素受体底物(IRS)-磷脂酰肌醇3(PI3)激酶-Akt途径调节糖原生成、糖异生和脂肪生成。IRS-1和IRS-2在肝脏中大量表达,被认为负责将胰岛素信号从胰岛素受体传递到参与葡萄糖和脂质稳态调节的细胞内效应器。胰岛素受体信号受损可导致肝脏胰岛素抵抗并引发2型糖尿病。在本研究中,我们关注一个最近受到越来越多关注的概念——“选择性胰岛素抵抗”:2型糖尿病和肥胖患者中高血糖和肝脂肪变性的频繁共存表明,即使调节脂肪生成的胰岛素信号得以保留,调节糖异生的胰岛素信号仍有可能受损,这提示了选择性胰岛素抵抗的存在。在这篇综述中,我们回顾了肝脏中胰岛素作用和胰岛素信号研究的进展。