肝酰基辅酶 A 去饱和酶 1 缺乏症通过 PGC-1α-FGF21 轴部分增加脂肪组织中的葡萄糖摄取。

Hepatic stearoyl CoA desaturase 1 deficiency increases glucose uptake in adipose tissue partially through the PGC-1α-FGF21 axis in mice.

机构信息

Endocrinology and Reproductive Physiology Graduate Training Program, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53706.

College of Science and Health Professions, King Saud bin Abdulaziz University for Health Sciences, Riyadh 11481, Saudi Arabia.

出版信息

J Biol Chem. 2019 Dec 20;294(51):19475-19485. doi: 10.1074/jbc.RA119.009868. Epub 2019 Nov 5.

Abstract

Increased carbohydrate consumption increases hepatic lipogenesis, which has been linked to the development of chronic metabolic diseases, including obesity, hepatic steatosis, and insulin resistance. Stearoyl CoA desaturase 1 (SCD1) is a critical lipogenic enzyme that catalyzes the synthesis of two monounsaturated fatty acids, oleate and palmitoleate, from the saturated fatty acids stearate and palmitate, respectively. SCD1-deficient mouse models are protected against diet-induced adiposity, hepatic steatosis, and hyperglycemia. However, the mechanism of this protection by SCD1 deficiency is unclear. Using liver-specific SCD1 knockout (LKO) mice fed a high-carbohydrate, low-fat diet, we show that hepatic SCD1 deficiency increases systemic glucose uptake. Hepatic SCD1 deficiency enhanced glucose transporter type 1 (GLUT1) expression in the liver and also up-regulated GLUT4 and adiponectin expression in adipose tissue. The enhanced glucose uptake correlated with increased liver expression and elevated plasma levels of fibroblast growth factor 21 (FGF21), a hepatokine known to increase systemic insulin sensitivity and regulate whole-body lipid metabolism. Feeding LKO mice a triolein-supplemented but not tristearin-supplemented high-carbohydrate, low-fat diet reduced FGF21 expression and plasma levels. Consistently, SCD1 inhibition in primary hepatocytes induced FGF21 expression, which was repressed by treatment with oleate but not palmitoleate. Moreover, deletion of the transcriptional coactivator PPARγ coactivator 1α (PGC-1α) reduced hepatic and plasma FGF21 and white adipocyte tissue-specific GLUT4 expression and raised plasma glucose levels in LKO mice. These results suggest that hepatic oleate regulates glucose uptake in adipose tissue either directly or partially by modulating the hepatic PGC-1α-FGF21 axis.

摘要

碳水化合物摄入增加会促进肝内脂肪生成,这与慢性代谢性疾病的发展有关,包括肥胖、肝脂肪变性和胰岛素抵抗。硬脂酰辅酶 A 去饱和酶 1(SCD1)是一种关键的脂肪生成酶,它催化从饱和脂肪酸硬脂酸和棕榈酸分别合成两种单不饱和脂肪酸油酸和棕榈油酸。SCD1 缺陷型小鼠模型可防止饮食诱导的肥胖、肝脂肪变性和高血糖。然而,SCD1 缺乏对这种保护的机制尚不清楚。使用肝特异性 SCD1 敲除(LKO)小鼠喂食高碳水化合物、低脂肪饮食,我们表明肝 SCD1 缺乏会增加全身葡萄糖摄取。肝 SCD1 缺乏会增加肝脏中葡萄糖转运蛋白 1(GLUT1)的表达,还会上调脂肪组织中 GLUT4 和脂联素的表达。增强的葡萄糖摄取与肝脏中纤维母细胞生长因子 21(FGF21)的表达增加相关,已知这种肝源激素可增加全身胰岛素敏感性并调节全身脂质代谢。用三油酸甘油酯而不是三硬脂酸甘油酯补充的高碳水化合物、低脂肪饮食喂养 LKO 小鼠会降低 FGF21 的表达和血浆水平。一致地,SCD1 抑制原代肝细胞诱导 FGF21 表达,而油酸但不是棕榈油酸处理可抑制其表达。此外,转录共激活因子过氧化物酶体增殖物激活受体 γ 共激活因子 1α(PGC-1α)的缺失降低了 LKO 小鼠肝脏和血浆 FGF21 以及白色脂肪组织特异性 GLUT4 的表达,并升高了血浆葡萄糖水平。这些结果表明,肝油酸通过调节肝 PGC-1α-FGF21 轴直接或部分调节脂肪组织中的葡萄糖摄取。

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