Novel putative SREBP and LXR target genes identified by microarray analysis in liver of cholesterol-fed mice

Kara N Maxwell,Raymond E Soccio,Elizabeth M Duncan,Ephraim Sehayek,Jan L Breslow

doi:10.1194/jlr.m300203-jlr200

Abstract

High-cholesterol diets elicit changes in gene expression via such transcription factors as sterol-regulatory element binding proteins (SREBPs) and liver X receptors (LXRs). We used Affymetrix microarrays to identify genes in mouse liver regulated by dietary cholesterol (0.0% vs. 0.5% cholesterol wt/wt). Three independent experiments were performed, and data were analyzed with Affymetrix Microarray Suite and ANOVA statistical software. There were 69 unique Unigene clusters consistently regulated by dietary cholesterol (37 downregulated and 32 upregulated). The array results were confirmed by quantitative RT-PCR (Q-PCR) for seven of nine downregulated genes and five of six upregulated genes. A time course of dietary cholesterol feeding over 1 week revealed different temporal patterns of gene regulation for these confirmed genes. Six downregulated genes were examined in transgenic mice overexpressing truncated nuclear forms of SREBP-1a and SREBP-2, and all were induced in these mice. A second microarray analysis of mice treated with the LXR agonist TO901317 confirmed that 13 of the 32 cholesterol upregulated genes were also LXR-activated. This array result was confirmed by Q-PCR for three of three genes. In summary, these studies identified and confirmed six novel dietary cholesterol-regulated genes, three putative SREBP target genes (calcium/calmodulin-dependent protein kinase 1D, fatty acid binding protein 5, and proprotein convertase subtilisin/kexin 9), and three putative LXR target genes (a disintegrin and metalloprotease domain 11, apoptosis-inhibitory 6, and F-box-only protein 3).

Highlights

High-cholesterol diets elicit changes in gene expression via such transcription factors as sterol-regulatory element binding proteins (SREBPs) and liver X receptors (LXRs)
Studies with mice overexpressing truncated nuclear forms of SREBP-1a, -1c, and -2 have revealed that SREBP-2 preferentially activates genes involved in cholesterol biosynthesis and metabolism, such as HMG-CoA synthase (HMGCS) and HMG-CoA reductase (HMGCR), whereas SREBP-1c and -1a preferentially activate genes involved in fatty acid biosynthesis, such as acetyl-CoA carboxylase (Acac) and ATP citrate lyase (Acly) [9,10,11,12]
We have established a model for examining the effects of dietary cholesterol on liver gene expression

Summary

Introduction

High-cholesterol diets elicit changes in gene expression via such transcription factors as sterol-regulatory element binding proteins (SREBPs) and liver X receptors (LXRs). This array result was confirmed by Q-PCR for three of three genes These studies identified and confirmed six novel dietary cholesterolregulated genes, three putative SREBP target genes (calcium/calmodulin-dependent protein kinase 1D, fatty acid binding protein 5, and proprotein convertase subtilisin/ kexin 9), and three putative LXR target genes (a disintegrin and metalloprotease domain 11, apoptosis-inhibitory 6, and F-box-only protein 3).—Maxwell, K. Studies with mice overexpressing truncated nuclear forms of SREBP-1a, -1c, and -2 have revealed that SREBP-2 preferentially activates genes involved in cholesterol biosynthesis and metabolism, such as HMG-CoA synthase (HMGCS) and HMGCR, whereas SREBP-1c and -1a preferentially activate genes involved in fatty acid biosynthesis, such as acetyl-CoA carboxylase (Acac) and ATP citrate lyase (Acly) [9,10,11,12]

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