title: Homocysteine Induces Hepatic Steatosis Involving ER Stress Response in High Methionine Diet-Fed Mice.
abstract: Elevated circulating homocysteine (Hcy) has been proposed to be associated with non-alcoholic fatty liver disease (NAFLD). It is also reported that Hcy causes protein misfolding in the endoplasmic reticulum (ER). In this study, we used a high methionine diet (HMD)-fed mouse model and cultured primary hepatocytes to investigate the effects of Hcy on hepatic lipids metabolism. C57BL/6J mice received either standard chow diet (CT,n= 10) or diet supplemented with 2% methionine (MET,n= 10) for 16 weeks. In in vitro experiments, cultured mouse primary hepatocytes were treated with Hcy, or Hcy combined with 4-phenylbutyric acid (4-PBA), or tunicamycin (TM), respectively. HMD-fed mice exhibited a mild increase in plasma Hcy level. There was no significant difference of body weight gain between the two groups. Nevertheless, HMD feeding increased epididymal fat/body weight ratio, elevated plasma triglyceride (TG) level, and decreased high-density lipoprotein cholesterol (HDL) level. Similarly, mice on HMD displayed higher liver/body weight ratio, plasma aspartate aminotransferase (AST) and its ratio to alanine aminotransferase (ALT), which was supported by the morphological observations of hepatic triglyceride accumulation in liver tissue as well as primary hepatocytes. Activation of the sterol response element-binding protein 1c (SREBP1c) in Hcy-treated hepatocytes with increased expression of genes involved in hepatic de novo lipogenesis was partially reduced by pretreatment of 4-PBA. Hcy-induced ER stress was also ameliorated by 4-PBA pretreatment, thus demonstrating an important role of Hcy-induced ER stress response in hepatic steatosis. These findings suggest that elevated Hcy was a critical factor in the pathogenesis of NAFLD. Activation of the ER stress response may be involved in Hcy-induced hepatic steatosis.
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health and Management, Chongqing Medical University, Chongqing 400016, China. aiyanbiao1992@163.com.
authors.forename: Yanbiao
authors.initials: Y
authors.lastname: Ai
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health and Management, Chongqing Medical University, Chongqing 400016, China. lipglucolabszz@163.com.
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Laboratory of Lipid & Glucose Metabolism, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China. 13527441813@163.com.
authors.forename: Chuan
authors.initials: C
authors.lastname: Peng
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health and Management, Chongqing Medical University, Chongqing 400016, China. liulingli0_0@163.com.
authors.forename: Lingli
authors.initials: L
authors.lastname: Liu
authors.affiliation: Laboratory of Lipid & Glucose Metabolism, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China. bshaw2001@163.com.
authors.forename: Xiaoqiu
authors.initials: X
authors.lastname: Xiao
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health and Management, Chongqing Medical University, Chongqing 400016, China. 100091@cqmu.edu.cn.
authors.forename: Jibin
authors.initials: J
authors.lastname: Li
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D002478:Cells, Cultured; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006710:Homocysteine / Q000009:adverse effects / Q000097:blood; D020138:Hyperhomocysteinemia / Q000097:blood / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D050155:Lipogenesis / Q000187:drug effects; D008099:Liver / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008715:Methionine / Q000009:adverse effects; D051379:Mice; D008810:Mice, Inbred C57BL; D065626:Non-alcoholic Fatty Liver Disease / Q000209:etiology*; D009929:Organ Size; D010654:Phenylbutyrates / Q000494:pharmacology; D011897:Random Allocation; D014415:Tunicamycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000970:Antineoplastic Agents; D010654:Phenylbutyrates; D006710:Homocysteine; D014415:Tunicamycin; C075773:4-phenylbutyric acid; D008715:Methionine
keywords: ER stress; NAFLD; homocysteine; methionine