Yanyan Jing1, Wei Liu1, Hongchao Cao2, Duo Zhang2, Xuan Yao2, Shengjie Zhang2, Hongfeng Xia2, Dan Li3, Yu-cheng Wang4, Jun Yan5, Lijian Hui3, Hao Ying6. 1. Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China; Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing 100021, China. 2. Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. 3. Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China. 4. Clinical Research Center of Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; Department of Nutrition, Shanghai Xuhui Central Hospital, Shanghai 200031, China. 5. Model Animal Research Center, and MOE Key Laboratory of Model Animals for Disease Study, Nanjing University, Nanjing 210061, China. 6. Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China; Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing 100021, China; Clinical Research Center of Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China. Electronic address: yinghao@sibs.ac.cn.
Abstract
BACKGROUND & AIMS: It is proposed that p38 is involved in gluconeogenesis, however, the genetic evidence is lacking and precise mechanisms remain poorly understood. We sought to delineate the role of hepatic p38α in gluconeogenesis during fasting by applying a loss-of-function genetic approach. METHODS: We examined fasting glucose levels, performed pyruvate tolerance test, imaged G6Pase promoter activity, as well as determined the expression of gluconeogenic genes in mice with a targeted deletion of p38α in liver. Results were confirmed both in vivo and in vitro by using an adenoviral dominant-negative form of p38α (p38α-AF) and the constitutively active mitogen-activated protein kinase 6, respectively. Adenoviral dominant-negative form of AMP-activated protein kinase α (DN-AMPKα) was employed to test our proposed model. RESULTS: Mice lacking hepatic p38α exhibited reduced fasting glucose level and impaired gluconeogenesis. Interestingly, hepatic deficiency of p38α did not result in an alteration in CREB phosphorylation, but led to an increase in AMPKα phosphorylation. Adenoviral DN-AMPKα could abolish the effect of p38α-AF on gluconeogenesis. Knockdown of up-steam transforming growth factor β-activated kinase 1 decreased the AMPKα phosphorylation induced by p38α-AF, suggesting a negative feedback loop. Consistently, inverse correlations between p38 and AMPKα phosphorylation were observed during fasting and in diabetic mouse models. Importantly, adenoviral p38α-AF treatment ameliorated hyperglycemia in diabetic mice. CONCLUSIONS: Our study provides evidence that hepatic p38α functions as a negative regulator of AMPK signaling in maintaining gluconeogenesis, dysregulation of this regulatory network contributes to unrestrained gluconeogenesis in diabetes, and hepatic p38α could be a drug target for hyperglycemia.
BACKGROUND & AIMS: It is proposed that p38 is involved in gluconeogenesis, however, the genetic evidence is lacking and precise mechanisms remain poorly understood. We sought to delineate the role of hepatic p38α in gluconeogenesis during fasting by applying a loss-of-function genetic approach. METHODS: We examined fasting glucose levels, performed pyruvate tolerance test, imaged G6Pase promoter activity, as well as determined the expression of gluconeogenic genes in mice with a targeted deletion of p38α in liver. Results were confirmed both in vivo and in vitro by using an adenoviral dominant-negative form of p38α (p38α-AF) and the constitutively active mitogen-activated protein kinase 6, respectively. Adenoviral dominant-negative form of AMP-activated protein kinase α (DN-AMPKα) was employed to test our proposed model. RESULTS:Mice lacking hepatic p38α exhibited reduced fasting glucose level and impaired gluconeogenesis. Interestingly, hepatic deficiency of p38α did not result in an alteration in CREB phosphorylation, but led to an increase in AMPKα phosphorylation. Adenoviral DN-AMPKα could abolish the effect of p38α-AF on gluconeogenesis. Knockdown of up-steam transforming growth factor β-activated kinase 1 decreased the AMPKα phosphorylation induced by p38α-AF, suggesting a negative feedback loop. Consistently, inverse correlations between p38 and AMPKα phosphorylation were observed during fasting and in diabeticmouse models. Importantly, adenoviral p38α-AF treatment ameliorated hyperglycemia in diabeticmice. CONCLUSIONS: Our study provides evidence that hepatic p38α functions as a negative regulator of AMPK signaling in maintaining gluconeogenesis, dysregulation of this regulatory network contributes to unrestrained gluconeogenesis in diabetes, and hepatic p38α could be a drug target for hyperglycemia.
Authors: Suraj J Patel; Nan Liu; Sam Piaker; Anton Gulko; Maynara L Andrade; Frankie D Heyward; Tyler Sermersheim; Nufar Edinger; Harini Srinivasan; Margo P Emont; Gregory P Westcott; Jay Luther; Raymond T Chung; Shuai Yan; Manju Kumari; Reeby Thomas; Yann Deleye; André Tchernof; Phillip J White; Guido A Baselli; Marica Meroni; Dario F De Jesus; Rasheed Ahmad; Rohit N Kulkarni; Luca Valenti; Linus Tsai; Evan D Rosen Journal: Sci Transl Med Date: 2022-03-23 Impact factor: 19.319