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Interaction between CHOP and FoxO6 promotes hepatic lipid accumulation

BACKGROUND & AIMS: Endoplasmic reticulum (ER) stress is one of the major causes of hepatic insulin resistance through increasing de novo lipogenesis. Forkhead box O6 (FoxO6) is a transcription factor mediating insulin signalling to glucose and lipid metabolism, therefore, dysregulated FoxO6 is i...

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Autores principales: Kim, Dae Hyun, Kim, Byeong Moo, Chung, Ki Wung, Choi, Yeon Ja, Yu, Byung Pal, Chung, Hae Young
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2020
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Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7689817/
https://www.ncbi.nlm.nih.gov/pubmed/32639626
http://dx.doi.org/10.1111/liv.14594
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author Kim, Dae Hyun
Kim, Byeong Moo
Chung, Ki Wung
Choi, Yeon Ja
Yu, Byung Pal
Chung, Hae Young
author_facet Kim, Dae Hyun
Kim, Byeong Moo
Chung, Ki Wung
Choi, Yeon Ja
Yu, Byung Pal
Chung, Hae Young
author_sort Kim, Dae Hyun
collection PubMed
description BACKGROUND & AIMS: Endoplasmic reticulum (ER) stress is one of the major causes of hepatic insulin resistance through increasing de novo lipogenesis. Forkhead box O6 (FoxO6) is a transcription factor mediating insulin signalling to glucose and lipid metabolism, therefore, dysregulated FoxO6 is involved in hepatic insulin resistance. In this study, we elucidated the role of FoxO6 in ER stress‐induced hepatic lipogenesis. METHODS: Hepatic ER stress responses and lipogenesis were monitored in mice overexpressed with constitutively active FoxO6 allele and FoxO6‐null mice. In the in vitro study, HepG2 cells overexpressing constitutively active FoxO6 were treated with palmitate, and then alterations in ER stress and lipid metabolism were measured. RESULTS: FoxO6 activation induced hepatic lipogenesis and the expression of ER stress‐inducible genes. The expression and transcriptional activity of peroxisome proliferator‐activated receptor γ (PPARγ) were significantly increased in constitutively active FoxO6 allele. Interestingly, we found that the active FoxO6 physically interacted with C/EBP homologous protein (CHOP), an ER stress‐inducible transcription factor, which was responsible for PPARγ expression. Palmitate treatment caused the expression of ER stress‐inducible genes, which was deteriorated by FoxO6 activation in HepG2 cells. Palmitate‐induced ER stress led to PPARγ expression through interactions between CHOP and FoxO6 corresponding to findings in the in vivo study. On the other hand, the expression of PPARα and β‐oxidation were decreased in constitutively active FoxO6 allele which implied that lipid catabolism is also regulated by FoxO6. CONCLUSION: Our data present significant evidence demonstrating that CHOP and FoxO6 interact to induce hepatic lipid accumulation through PPARγ expression during ER stress.
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spelling pubmed-76898172020-12-08 Interaction between CHOP and FoxO6 promotes hepatic lipid accumulation Kim, Dae Hyun Kim, Byeong Moo Chung, Ki Wung Choi, Yeon Ja Yu, Byung Pal Chung, Hae Young Liver Int Metabolic & Toxic Liver Diseases BACKGROUND & AIMS: Endoplasmic reticulum (ER) stress is one of the major causes of hepatic insulin resistance through increasing de novo lipogenesis. Forkhead box O6 (FoxO6) is a transcription factor mediating insulin signalling to glucose and lipid metabolism, therefore, dysregulated FoxO6 is involved in hepatic insulin resistance. In this study, we elucidated the role of FoxO6 in ER stress‐induced hepatic lipogenesis. METHODS: Hepatic ER stress responses and lipogenesis were monitored in mice overexpressed with constitutively active FoxO6 allele and FoxO6‐null mice. In the in vitro study, HepG2 cells overexpressing constitutively active FoxO6 were treated with palmitate, and then alterations in ER stress and lipid metabolism were measured. RESULTS: FoxO6 activation induced hepatic lipogenesis and the expression of ER stress‐inducible genes. The expression and transcriptional activity of peroxisome proliferator‐activated receptor γ (PPARγ) were significantly increased in constitutively active FoxO6 allele. Interestingly, we found that the active FoxO6 physically interacted with C/EBP homologous protein (CHOP), an ER stress‐inducible transcription factor, which was responsible for PPARγ expression. Palmitate treatment caused the expression of ER stress‐inducible genes, which was deteriorated by FoxO6 activation in HepG2 cells. Palmitate‐induced ER stress led to PPARγ expression through interactions between CHOP and FoxO6 corresponding to findings in the in vivo study. On the other hand, the expression of PPARα and β‐oxidation were decreased in constitutively active FoxO6 allele which implied that lipid catabolism is also regulated by FoxO6. CONCLUSION: Our data present significant evidence demonstrating that CHOP and FoxO6 interact to induce hepatic lipid accumulation through PPARγ expression during ER stress. John Wiley and Sons Inc. 2020-07-26 2020-11 /pmc/articles/PMC7689817/ /pubmed/32639626 http://dx.doi.org/10.1111/liv.14594 Text en © 2020 The Authors. Liver International published by John Wiley & Sons Ltd This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc-nd/4.0/ License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.
spellingShingle Metabolic & Toxic Liver Diseases
Kim, Dae Hyun
Kim, Byeong Moo
Chung, Ki Wung
Choi, Yeon Ja
Yu, Byung Pal
Chung, Hae Young
Interaction between CHOP and FoxO6 promotes hepatic lipid accumulation
title Interaction between CHOP and FoxO6 promotes hepatic lipid accumulation
title_full Interaction between CHOP and FoxO6 promotes hepatic lipid accumulation
title_fullStr Interaction between CHOP and FoxO6 promotes hepatic lipid accumulation
title_full_unstemmed Interaction between CHOP and FoxO6 promotes hepatic lipid accumulation
title_short Interaction between CHOP and FoxO6 promotes hepatic lipid accumulation
title_sort interaction between chop and foxo6 promotes hepatic lipid accumulation
topic Metabolic & Toxic Liver Diseases
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7689817/
https://www.ncbi.nlm.nih.gov/pubmed/32639626
http://dx.doi.org/10.1111/liv.14594
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