{"title":"Endoplasmic reticulum stress induces hepatic steatosis through interaction between PPARα and FoxO6 in vivo and in vitro.","authors":"Dae Hyun Kim","doi":"10.1007/s00109-024-02480-2","DOIUrl":null,"url":null,"abstract":"<p><p>Endoplasmic reticulum (ER) stress is a major cause of hepatic steatosis through increasing de novo lipogenesis. Forkhead box O6 (FoxO6) is a transcription factor mediating insulin signaling to glucose and lipid metabolism. Therefore, dysregulated FoxO6 is involved in hepatic lipogenesis. This study elucidated the role of FoxO6 in ER stress-induced hepatic steatosis in vivo and in vitro. Hepatic ER stress responses and β-oxidation were monitored in mice overexpressed with constitutively active FoxO6 allele and FoxO6-null mice. For the in vitro study, liver cells overexpressing constitutively active FoxO6 and FoxO6-siRNA were treated with high glucose, and lipid metabolism alterations were measured. ER stress-induced FoxO6 activation suppressed hepatic β-oxidation in vivo. The expression and transcriptional activity of peroxisome proliferator-activated receptor α (PPARα) were significantly decreased in the constitutively active FoxO6 allele. Otherwise, inhibiting β-oxidation genes were reduced in the FoxO6-siRNA and FoxO6-KO mice. Our data showed that the FoxO6-induced hepatic lipid accumulation was negatively regulated by insulin signaling. High glucose treatment as a hyperglycemia condition caused the expression of ER stress-inducible genes, which was deteriorated by FoxO6 activation in liver cells. However, high glucose-mediated ER stress suppressed β-oxidation gene expression through interactions between PPARα and FoxO6 corresponding to findings in the in vivo study-lipid catabolism is also regulated by FoxO6. Furthermore, insulin resistance suppressed b-oxidation through the interaction between FoxO6 and PPARα promotes hepatic steatosis, which, due to hyperglycemia-induced ER stress, impairs insulin signaling. KEY MESSAGES: Our original aims were to delineate the interrelation between the regulation of PPARα and the transcription factor FoxO6 pathway in relation to lipid metabolism at molecular levels. Evidence on high glucose promoted FoxO6 activation induced lipid accumulation in liver cells. The effect of PPARα activation of the insulin signaling. FoxO6 plays a pivotal role in hepatic lipid accumulation through inactivation of PPARα in FoxO6-overexpression mice.</p>","PeriodicalId":50127,"journal":{"name":"Journal of Molecular Medicine-Jmm","volume":" ","pages":"1267-1284"},"PeriodicalIF":4.8000,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11416408/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Molecular Medicine-Jmm","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1007/s00109-024-02480-2","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/8/28 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"GENETICS & HEREDITY","Score":null,"Total":0}
引用次数: 0
Abstract
Endoplasmic reticulum (ER) stress is a major cause of hepatic steatosis through increasing de novo lipogenesis. Forkhead box O6 (FoxO6) is a transcription factor mediating insulin signaling to glucose and lipid metabolism. Therefore, dysregulated FoxO6 is involved in hepatic lipogenesis. This study elucidated the role of FoxO6 in ER stress-induced hepatic steatosis in vivo and in vitro. Hepatic ER stress responses and β-oxidation were monitored in mice overexpressed with constitutively active FoxO6 allele and FoxO6-null mice. For the in vitro study, liver cells overexpressing constitutively active FoxO6 and FoxO6-siRNA were treated with high glucose, and lipid metabolism alterations were measured. ER stress-induced FoxO6 activation suppressed hepatic β-oxidation in vivo. The expression and transcriptional activity of peroxisome proliferator-activated receptor α (PPARα) were significantly decreased in the constitutively active FoxO6 allele. Otherwise, inhibiting β-oxidation genes were reduced in the FoxO6-siRNA and FoxO6-KO mice. Our data showed that the FoxO6-induced hepatic lipid accumulation was negatively regulated by insulin signaling. High glucose treatment as a hyperglycemia condition caused the expression of ER stress-inducible genes, which was deteriorated by FoxO6 activation in liver cells. However, high glucose-mediated ER stress suppressed β-oxidation gene expression through interactions between PPARα and FoxO6 corresponding to findings in the in vivo study-lipid catabolism is also regulated by FoxO6. Furthermore, insulin resistance suppressed b-oxidation through the interaction between FoxO6 and PPARα promotes hepatic steatosis, which, due to hyperglycemia-induced ER stress, impairs insulin signaling. KEY MESSAGES: Our original aims were to delineate the interrelation between the regulation of PPARα and the transcription factor FoxO6 pathway in relation to lipid metabolism at molecular levels. Evidence on high glucose promoted FoxO6 activation induced lipid accumulation in liver cells. The effect of PPARα activation of the insulin signaling. FoxO6 plays a pivotal role in hepatic lipid accumulation through inactivation of PPARα in FoxO6-overexpression mice.
期刊介绍:
The Journal of Molecular Medicine publishes original research articles and review articles that range from basic findings in mechanisms of disease pathogenesis to therapy. The focus includes all human diseases, including but not limited to:
Aging, angiogenesis, autoimmune diseases as well as other inflammatory diseases, cancer, cardiovascular diseases, development and differentiation, endocrinology, gastrointestinal diseases and hepatology, genetics and epigenetics, hematology, hypoxia research, immunology, infectious diseases, metabolic disorders, neuroscience of diseases, -omics based disease research, regenerative medicine, and stem cell research.
Studies solely based on cell lines will not be considered. Studies that are based on model organisms will be considered as long as they are directly relevant to human disease.