title: Dietary Macronutrient Composition Directs ChREBP Isoform Expression and Glucose Metabolism in Mice.
abstract: Carbohydrate response element binding protein (ChREBP) is a lipogenic transcription factor that is thought to be involved in the development of hepatic steatosis and insulin resistance. Increased ChREBP expression in liver results in increased hepatic steatosis, and the isoform ChREBPβ in adipose tissue can predict insulin sensitivity in obese humans. As ChREBP is activated by glucose, it was postulated that the composition of diet would regulate ChREBP isoform expression in metabolically relevant tissues. We compared the effects of diets with high complex carbohydrate, high fat, or a normal chow on ChREBP expression and metabolic parameters in C57BL/6 mice. We found that diets high in fat decrease ChREBP expression in adipose tissue, but isocaloric diets high in carbohydrate have no effect. Interestingly, this decrease in adipose ChREBP was associated with increased inflammatory markers. In the same animals a high carbohydrate diet induced a robust increase in hepatic ChREBPβ expression (≈2-fold; p = 0.0002), but little detectable change in the more abundant ChREBPα transcript. This change was accompanied by increased expression of target genes liver pyruvate kinase (p<0.0001), acetyl-CoA carboxylase (p = 0.0191) and stearoyl-CoA desaturase-1 (p = 0.0045). This increase in ChREBP expression was associated with increased hepatic steatosis, despite no changes in body weight or body fat when compared to chow-fed mice. Unexpectedly, mice fed a high carbohydrate diet displayed enhanced sensitivity to exogenous insulin, despite having mild glucose intolerance and increased liver steatosis. In summary, we have shown the composition of diet can selectively regulate ChREBP isoform expression in a tissue specific manner. Furthermore, we have shown a high complex carbohydrate diet selectively increases hepatic ChREBPβ expression, which associates with hepatic steatosis but not insulin resistance. In contrast, a high fat diet reduces adipose ChREBP, which associates with inflammation and insulin resistance.
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: Tara
authors.identifier: http://orcid.org/0000-0001-9111-2574
authors.initials: T
authors.lastname: Jois
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: Victor
authors.initials: V
authors.lastname: Howard
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: Kristina
authors.initials: K
authors.lastname: Youngs
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.|Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Cowley
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.|Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.|Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Sleeman
mesh_terms: D000818:Animals; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004040:Dietary Carbohydrates / Q000009:adverse effects / Q000494:pharmacology*; D005234:Fatty Liver / Q000139:chemically induced / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism; D007333:Insulin Resistance; D008099:Liver / Q000378:metabolism*; D051379:Mice; D009687:Nuclear Proteins / Q000096:biosynthesis*; D020033:Protein Isoforms / Q000096:biosynthesis; D011770:Pyruvate Kinase / Q000096:biosynthesis; D014157:Transcription Factors / Q000096:biosynthesis*
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004040:Dietary Carbohydrates; C506001:Mlxipl protein, mouse; D009687:Nuclear Proteins; D020033:Protein Isoforms; D014157:Transcription Factors; D011770:Pyruvate Kinase; D005947:Glucose