1. Liver Pyruvate Kinase Promotes NAFLD/NASH in Both Mice and Humans in a Sex-Specific Manner
- Author
-
Aldons J. Lusis, Raquel Floyd, Simon Sabir, Miklós Péterfy, Paola León-Mimila, Anthony E. Jones, Linsey Stiles, Dulshan W. Jayasekera, Samuel Canizales-Quinteros, Adriana Huertas-Vazquez, Varun Shravah, Angel A. Cortez, Karthickeyan Chella Krishnan, and Ajit S. Divakaruni
- Subjects
0301 basic medicine ,HMDP, Hybrid Mouse Diversity Panel ,Male ,OXPHOS, oxidative phosphorylation ,Mitochondrion ,HF/HS diet, diet rich in fat and sucrose ,CDAHFD, choline-deficient, L-amino acid-defined, high-fat diet with 0.1% methionine ,Oral and gastrointestinal ,Hepatitis ,LPK, liver pyruvate kinase ,Mice ,0302 clinical medicine ,GGT, gamma-glutamyl transpeptidase ,Fibrosis ,Loss of Function Mutation ,Non-alcoholic Fatty Liver Disease ,Nonalcoholic fatty liver disease ,2.1 Biological and endogenous factors ,Aetiology ,scrRNA, scrambled RNA ,Original Research ,CE, cholesteryl ester ,TG, triglyceride ,Liver Disease ,NAS, NAFLD Activity Score ,Gastroenterology ,Middle Aged ,Up-Regulation ,Liver ,Gain of Function Mutation ,Lipogenesis ,Mitochondrial Dysfunction ,shRNA, short hairpin RNA ,Liver Fibrosis ,qPCR, quantitative polymerase chain reaction ,030211 gastroenterology & hepatology ,Female ,NASH, nonalcoholic steatohepatitis ,ITT, insulin tolerance tests ,L/PTT, lactate/pyruvate tolerance tests ,Adult ,medicine.medical_specialty ,DEGs, differentially expressed genes ,Chronic Liver Disease and Cirrhosis ,ETC, electron transport chain ,HDL, high-density lipoprotein ,Pyruvate Kinase ,DNL, de novo lipogenesis ,SEM, standard error of the mean ,03 medical and health sciences ,Insulin resistance ,ROS, reactive oxygen species ,Sex Factors ,Liver Pyruvate Kinase ,Internal medicine ,NAFLD ,AAV8, adeno-associated virus serotype 8 ,FFA, free fatty acid ,Genetics ,medicine ,Animals ,Humans ,Genetic Predisposition to Disease ,Obesity ,Gene Silencing ,Sex Differences ,Metabolic and endocrine ,TBG, thyroxine binding globulin ,Nutrition ,Hepatology ,Animal ,business.industry ,Gene Expression Profiling ,medicine.disease ,TC, total cholesterol ,Disease Models, Animal ,030104 developmental biology ,Endocrinology ,siRNA, small interfering RNA ,Disease Models ,NAFLD, nonalcoholic fatty liver disease ,Steatosis ,Digestive Diseases ,business ,Dyslipidemia ,Pyruvate kinase ,GTT, glucose tolerance tests - Abstract
Background & Aims The etiology of nonalcoholic fatty liver disease (NAFLD) is poorly understood, with males and certain populations exhibiting markedly increased susceptibility. Using a systems genetics approach involving multi-omic analysis of ∼100 diverse inbred strains of mice, we recently identified several candidate genes driving NAFLD. We investigated the role of one of these, liver pyruvate kinase (L-PK or Pklr), in NAFLD by using patient samples and mouse models. Methods We examined L-PK expression in mice of both sexes and in a cohort of bariatric surgery patients. We used liver-specific loss- and gain-of-function strategies in independent animal models of diet-induced steatosis and fibrosis. After treatment, we measured several metabolic phenotypes including obesity, insulin resistance, dyslipidemia, liver steatosis, and fibrosis. Liver tissues were used for gene expression and immunoblotting, and liver mitochondria bioenergetics was characterized. Results In both mice and humans, L-PK expression is up-regulated in males via testosterone and is strongly associated with NAFLD severity. In a steatosis model, L-PK silencing in male mice improved glucose tolerance, insulin sensitivity, and lactate/pyruvate tolerance compared with controls. Furthermore, these animals had reduced plasma cholesterol levels and intrahepatic triglyceride accumulation. Conversely, L-PK overexpression in male mice resulted in augmented disease phenotypes. In contrast, female mice overexpressing L-PK were unaffected. Mechanistically, L-PK altered mitochondrial pyruvate flux and its incorporation into citrate, and this, in turn, increased liver triglycerides via up-regulated de novo lipogenesis and increased PNPLA3 levels accompanied by mitochondrial dysfunction. Also, L-PK increased plasma cholesterol levels via increased PCSK9 levels. On the other hand, L-PK silencing reduced de novo lipogenesis and PNPLA3 and PCSK9 levels and improved mitochondrial function. Finally, in fibrosis model, we demonstrate that L-PK silencing in male mice reduced both liver steatosis and fibrosis, accompanied by reduced de novo lipogenesis and improved mitochondrial function. Conclusions L-PK acts in a male-specific manner in the development of liver steatosis and fibrosis. Because NAFLD/nonalcoholic steatohepatitis exhibit sexual dimorphism, our results have important implications for the development of personalized therapeutics., Graphical abstract
- Published
- 2020