Dexamethasone-induced Krüppel-like factor 9 expression promotes hepatic gluconeogenesis and hyperglycemia
Anfang Cui, Heng Fan, Yinliang Zhang, Yujie Zhang, Dong Niu, Shuainan Liu, Quan Liu, Wei Ma, Zhufang Shen, Lian Shen, Yanling Liu, Huabing Zhang, Yuan Xue, Ying Cui, Qinghua Wang, Xinhua Xiao, Fude Fang, Jichun Yang, Qinghua Cui, Yongsheng Chang
Anfang Cui, Heng Fan, Yinliang Zhang, Yujie Zhang, Dong Niu, Shuainan Liu, Quan Liu, Wei Ma, Zhufang Shen, Lian Shen, Yanling Liu, Huabing Zhang, Yuan Xue, Ying Cui, Qinghua Wang, Xinhua Xiao, Fude Fang, Jichun Yang, Qinghua Cui, Yongsheng Chang
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Research Article Endocrinology Metabolism

Dexamethasone-induced Krüppel-like factor 9 expression promotes hepatic gluconeogenesis and hyperglycemia

Abstract

Chronic glucocorticoid therapy has serious side effects, including diabetes and fatty liver. However, the molecular mechanisms responsible for steroid-induced diabetes remain largely enigmatic. Here, we show that hepatic Krüppel-like factor 9 (Klf9) gene expression is induced by dexamethasone and fasting. The overexpression of Klf9 in primary hepatocytes strongly stimulated Pgc1a gene expression through direct binding to its promoter, thereby activating the gluconeogenic program. However, Klf9 mutation abolished the stimulatory effect of dexamethasone on cellular glucose output. Adenovirus-mediated overexpression of KLF9 in the mouse liver markedly increased blood glucose levels and impaired glucose tolerance. Conversely, both global Klf9-mutant mice and liver-specific Klf9-deleted mice displayed fasting hypoglycemia. Moreover, the knockdown of Klf9 in the liver in diabetic mouse models, including ob/ob and db/db mice, markedly lowered fasting blood glucose levels. Notably, hepatic Klf9 deficiency in mice alleviated hyperglycemia induced by chronic dexamethasone treatment. These results suggest a critical role for KLF9 in the regulation of hepatic glucose metabolism and identify hepatic induction of KLF9 as a mechanism underlying glucocorticoid therapy–induced diabetes.

Authors

Anfang Cui, Heng Fan, Yinliang Zhang, Yujie Zhang, Dong Niu, Shuainan Liu, Quan Liu, Wei Ma, Zhufang Shen, Lian Shen, Yanling Liu, Huabing Zhang, Yuan Xue, Ying Cui, Qinghua Wang, Xinhua Xiao, Fude Fang, Jichun Yang, Qinghua Cui, Yongsheng Chang

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Figure 2

KLF9 activates the gluconeogenic program in primary hepatocytes through PGC1α.

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KLF9 activates the gluconeogenic program in primary hepatocytes through ...
(A) Quantitative PCR analysis showing mRNA levels of Pgc1a, G6pc, Pck1, and Glut2 in mouse primary hepatocytes infected with Ad-GFP or Ad-Klf9. Cells were harvested for further analysis 48 hours after infection. (B) Western blot analysis of KLF9 and PGC1α in primary hepatocytes treated as described in A. (C) Glucose output assay showing the effects of Klf9 overexpression on glucose production in primary hepatocytes as described in A. (D) ChIP assay performed as described in Methods, showing that both fasting (top panel) and Dex treatment (bottom panel) promote endogenous KLF9 binding to the proximal region of the Pgc1a gene promoter, but not the distal region (as a negative control). (E) Glucose output assay showing glucose production in primary hepatocytes isolated from global Klf9-mutant and WT C57BL/6 mice treated with Dex (100 nM) or saline for 12 hours. (F) Quantitative PCR analysis (left) of Pgc1a, G6pc, Pck1, and Glut2 in the primary hepatocytes described in E. (G) Representative Western blot analysis of hepatic KLF9 and PGC1α in the primary hepatocytes described in E. (H) Quantitative PCR analysis of G6pc and Pck1 in primary hepatocytes infected with the indicated adenoviruses. (I) Glucose output assay showing glucose production in the primary hepatocytes described in H. Data are represented as mean ± SEM. *P < 0.05; **P < 0.01, 2-tailed Student’s t test (A, C), 2-way ANOVA (E, F), or 1-way ANOVA (H, I).