Microrna-451 Negatively Regulates Hepatic Glucose Production and Glucose Homeostasis by Targeting Glycerol Kinase–Mediated Gluconeogenesis
Total Page:16
File Type:pdf, Size:1020Kb
3276 Diabetes Volume 65, November 2016 Shu Zhuo,1,2 Mengmei Yang,1 Yanan Zhao,1 Xiaofang Chen,1 Feifei Zhang,3 Na Li,1 Pengle Yao,1 Tengfei Zhu,1 Hong Mei,1 Shanshan Wang,1 Yu Li,3 Shiting Chen,1,2 and Yingying Le1,2 MicroRNA-451 Negatively Regulates Hepatic Glucose Production and Glucose Homeostasis by Targeting Glycerol Kinase–Mediated Gluconeogenesis Diabetes 2016;65:3276–3288 | DOI: 10.2337/db16-0166 MicroRNAs (miRNAs) are a new class of regulatory mole- Type 2 diabetes (T2D) is characterized by insulin re- cules implicated in type 2 diabetes, which is charac- sistance and abnormally elevated hepatic glucose pro- terized by insulin resistance and hepatic glucose duction primarily from sustained gluconeogenesis (1–3), overproduction. We show that miRNA-451 (miR-451) is but the underlying mechanisms are poorly understood. elevated in the liver tissues of dietary and genetic mouse Hepatic gluconeogenesis is induced by glucagon and gluco- models of diabetes. Through an adenovirus-mediated corticoids and inhibited by insulin through the tran- gain- and loss-of-function study, we found that miR-451 scriptional regulation of glucose-6-phosphatase (G6Pase) negatively regulates hepatic gluconeogenesis and blood and PEPCK, two rate-limiting gluconeogenic enzymes fi glucose levels in normal mice and identi ed glycerol (3,4). CREB, FOXO1, and peroxisome proliferator– kinase (Gyk) as a direct target of miR-451. We demon- activated receptor g coactivator 1a (PGC-1a) are major METABOLISM strate that miR-451 and Gyk regulate hepatic glucose transcription factors and transcriptional coactivators that production, the glycerol gluconeogenesis axis, and the mediate hormonal regulation of hepatic gluconeogenic AKT-FOXO1-PEPCK/G6Pase pathway in an opposite enzyme expression (3,5–7). The expression or activity of manner; Gyk could reverse the effect of miR-451 on gluconeogenic enzymes and transcriptional factors/ hepatic gluconeogenesis and AKT-FOXO1-PEPCK/ G6Pase pathway. Moreover, overexpression of miR-451 coactivators are increased in the livers of humans with or knockdown of Gyk in diabetic mice significantly diabetes and diabetic rodents (8,9); knockdown or inhibi- fi inhibited hepatic gluconeogenesis, alleviated hypergly- tion of these molecules signi cantly improves hyperglyce- – cemia, and improved glucose tolerance. Further studies mia in diabetic mouse models (10 12). Thus, inhibition of showed that miR-451 is upregulated by glucose and the gluconeogenic pathway in the liver could be a poten- insulin in hepatocytes; the elevation of hepatic miR-451 tial strategy for combating diabetic hyperglycemia. in diabetic mice may contribute to inhibiting Gyk expres- MicroRNAs (miRNAs) are small endogenous noncoding sion. This study provides the first evidence that miR-451 RNAs that regulate gene expression through transla- and Gyk regulate the AKT-FOXO1-PEPCK/G6Pase path- tional repression or degradation of target mRNAs. Recent way and play critical roles in hepatic gluconeogenesis and studies of liver samples from diabetic animal models glucose homeostasis and identifies miR-451 and Gyk and humans with diabetes suggest that dysregulation of as potential therapeutic targets against hyperglycemia hepaticmiRNAsmayleadtoT2D.SeveralmiRNAs in diabetes. contribute to insulin resistance in vivo (13–17), but 1Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Received 3 February 2016 and accepted 19 July 2016. Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Uni- This article contains Supplementary Data online at http://diabetes versity of the Chinese Academy of Sciences, Shanghai, China .diabetesjournals.org/lookup/suppl/doi:10.2337/db16-0166/-/DC1. 2Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing, © 2016 by the American Diabetes Association. Readers may use this article as China long as the work is properly cited, the use is educational and not for profit, and the 3Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, work is not altered. More information is available at http://www.diabetesjournals Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Uni- .org/content/license. versity of Chinese Academy of Sciences, Shanghai, China Corresponding author: Yingying Le, [email protected]. diabetes.diabetesjournals.org Zhuo and Associates 3277 very few are involved in gluconeogenesis and T2D miR-451 sponges (Anti-451), Gyk (Ad-Gyk), or green (17–19). miRNA-451 (miR-451) is dysregulated in multi- fluorescent protein (Ad-GFP) were prepared by using the ple types of cancers and contributes to tumorigenesis, AdEasy Adenoviral Vector System (Agilent) according to tumor progression, and metastasis by targeting various the manufacturer’s instructions and the literature (35). molecules (20–22). Recent studies have indicated that Recombinant adenoviruses expressing Gyk shRNA and miR-451 may be involved in metabolic disorders. miR- control scrambled shRNA were generated by using the 451 is decreased in liver tissues of patients with nonalco- BLOCK-iT Adenoviral RNAi Expression System (Thermo holic steatohepatitis and the corresponding mouse model. Fisher Scientific). Eight- to 10-week-old C57BL/6 mice, It negatively regulates fatty acid–induced inflammation HFD-induced diabetic mice, or db/db mice were injected through the LKB1/AMPK/AKT pathway by targeting with adenoviruses through the tail vein at 1 3 109 plaque- CAB39, a component of the LKB1-STRAD-CAB39 complex forming units in 0.2 mL of PBS. All experiments were (23). Microarray analysis has shown that miR-451 levels carried out within 1 week after injection. are elevated in the livers of diabetic and obese animal Glucose Metabolism Test models (13,24). We also found that hepatic miR-451 is For glucose tolerance test (GTT), pyruvate tolerance test elevated in high-fat diet (HFD)–induced diabetic mice and (PTT), and glycerol tolerance test (GlyTT), mice fasted for db/db mice by real-time PCR (S. Zhuo, unpublished obser- 6 h were intraperitoneally injected with glucose, pyruvate, vation). However, whether miR-451 contributes to diabetes is unclear. We speculate that miR-451 might be involved or glycerol, respectively, at 2 g/kg body weight. For the insulin tolerance test (ITT), mice fasted for 4 h were injected in the regulation of hepatic glucose metabolism and T2D with insulin intraperitoneally at 0.75 or 1 unit/kg body because miR-451 has been reported to be upregulated by weight. Blood glucose concentrations were measured before glucose in glioma cells, and some target molecules and and after injection with a glucometer (FreeStyle; Abbott). signaling pathways that mediate the effects of miR-451 on cancer cell growth and migration, such as 14-3-3 pro- Blood and Liver Biochemical Analysis teins, CAB39, and LKB1/AMPK and PI3K/AKT (25–28), Serum insulin and glycerol levels were determined by an are critical regulators of hepatic glucose metabolism and ELISA kit (Millipore) and an enzymatic glycerol assay kit therapeutic targets of T2D (29–34). (Applygen, Beijing, China), respectively. Liver glycogen In this study, we show that miR-451 is elevated in content was measured as previously described (36). livers of HFD-induced diabetic mice and db/db mice and identified glycerol kinase (Gyk) as a target of miR-451. Quantitative Real-Time PCR Through adenovirus-mediated gain- and loss-of-function Total RNA was extracted from tissues or cells using TRIzol studies, we demonstrate that miR-451 negatively regu- reagent (Invitrogen) and treated with RNase-free DNase lates hepatic gluconeogenesis and glucose homeostasis. We to degrade contaminating genomic DNA. cDNA was further explored the signaling pathways involved in the reg- synthesized with 2 mg of total RNA using Moloney mu- ulation of hepatic gluconeogenesis by miR-451 and Gyk and rine leukemia virus reverse transcriptase and oligo (dT) examined the regulation of hepatic miR-451 and/or Gyk primers; 500 ng of total RNA was reverse-transcribed – fi 9 in vitro and in HFD-fed mice. Finally, we checked the effect by using an miR-451 speci c stem-loop primer (5 - of overexpression of miR-451 or knockdown of Gyk on CTCAACTGGTGTCGTGGAGTCGGCAATTCAGTTGAGAACT 9 glucose metabolism in the diabetic mouse models. CAGT-3 ). Quantitative real-time PCR (qRT-PCR) was per- formed by using an ABI Prism 7900 sequence detection RESEARCH DESIGN AND METHODS system (Applied Biosystems) with SYBR Green PCR Master Animals and Treatment Mix (Applied Biosystems). Transcriptional levels for mRNA Male C57BL/6 and db/db mice were obtained from Shanghai and miR-451 were normalized to 36B4 and U6,respectively. Laboratory Animal Co. (Shanghai, China) and the Model The relative expression of mRNA or miR-451 was calculated Animal Research Center of Nanjing University (Nanjing, using the 2-DDCT method. Primer sequences used for qRT- China), respectively. Eight-week-old mice were fed an HFD PCR are listed in the Supplementary Table 1. (D12492; Research Diets) or control chow (D12450J; Re- Western Blotting search Diets) for the same period. All animals were killed Western blotting was carried out according to standard under an anesthetic condition, serum was stored at 280°C, protocols. Target proteins were detected with SuperSignal and livers were collected and snap-frozen in liquid nitrogen West Pico Chemiluminescent Substrate (Thermo Fisher for further analysis. Animal experiments were performed in Scientific), quantified with Adobe Photoshop CS5, and accordance with the guidelines of the