Dataset Information

Conditional Gata4 deletion in mice induces bile acid absorption in the proximal small intestine.

ABSTRACT: The transcription factor GATA4 is expressed throughout most of the small intestine except distal ileum, and restricts expression of the apical sodium-dependent bile acid transporter (ASBT), the rate-limiting intestinal bile acid transporter, to distal ileum. The hypothesis was tested that reduction of GATA4 activity in mouse small intestine results in an induction of bile acid transport in proximal small intestine sufficient to restore bile acid absorption and homeostasis after ileocaecal resection (ICR).Bile acid homeostasis was characterised in non-surgical, sham or ICR mice using two recombinant Gata4 models in which Asbt expression is induced to different levels.Reduction of intestinal GATA4 activity resulted in an induction of ASBT expression, bile acid absorption and expression of bile acid-responsive genes in proximal small intestine, and a reduction of luminal bile acids in distal small intestine. While faecal bile acid excretion and bile acid pool size remained unchanged, the bile acid pool became more hydrophilic due to a relative increase in tauro-beta-muricholate absorption. Furthermore, proximal induction of Asbt in both Gata4 mutant models corrected ICR-associated bile acid malabsorption, reversing the decrease in bile acid pool size and increase in faecal bile acid excretion and hepatic cholesterol 7alpha-hydroxylase expression.Reduction of intestinal GATA4 activity induces bile acid absorption in proximal small intestine without inducing major changes in bile acid homeostasis. This induction is sufficient to correct bile acid malabsorption caused by ICR in mice.

SUBMITTER: Beuling E

PROVIDER: S-EPMC2981798 | biostudies-literature | 2010 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Conditional Gata4 deletion in mice induces bile acid absorption in the proximal small intestine.

Beuling Eva E Kerkhof Ilona M IM Nicksa Grace A GA Giuffrida Michael J MJ Haywood Jamie J aan de Kerk Daniel J DJ Piaseckyj Christina M CM Pu William T WT Buchmiller Terry L TL Dawson Paul A PA Krasinski Stephen D SD

Gut 20100701 7

<h4>Background and aims</h4>The transcription factor GATA4 is expressed throughout most of the small intestine except distal ileum, and restricts expression of the apical sodium-dependent bile acid transporter (ASBT), the rate-limiting intestinal bile acid transporter, to distal ileum. The hypothesis was tested that reduction of GATA4 activity in mouse small intestine results in an induction of bile acid transport in proximal small intestine sufficient to restore bile acid absorption and homeost ...[more]

PMID: 20581237

Similar Datasets

Project description:Background and Aims: Although the zinc finger transcription factor GATA4 has been implicated in regulating jejunal gene expression, the contribution of GATA4 in controlling jejunal physiology has not been addressed. Methods: We generated mice in which the Gata4 gene was specifically deleted in the small intestinal epithelium. Measurements of plasma cholesterol and phospholipids, intestinal absorption of dietary fat and cholesterol, and gene expression were performed on these animals. Results: Mice lacking GATA4 in the intestine displayed a dramatic block in their ability to absorb cholesterol and dietary fat. Comparison of the global gene expression profiles of control jejunum, control ileum, and GATA4 null jejunum by gene array analysis demonstrated that GATA4 null jejunum lost expression of 53% of the jejunal-specific gene set and gained expression of 47% of the set of genes unique to the ileum. These alterations in gene expression included a decrease in mRNAs encoding lipid and cholesterol transporters as well as an increase in mRNAs encoding proteins involved in bile acid absorption. Conclusion: Our data demonstrate that GATA4 is essential for jejunal function including fat and cholesterol absorption and confirm that GATA4 plays a pivotal role in determining jejunal versus ileal identity. Experiment Overall Design: Total RNA was harvested from the following sources and used to Affymetrix array analysis following manufacturer defined protocols: Experiment Overall Design: control jejunum (Gata4loxP/+VilCre), 3 male mice, adult (6-8 wk) Experiment Overall Design: mutant jejunum (Gata4loxP/-VilCre), 3 male mice, adult (6-8 wk) Experiment Overall Design: control ileum (Gata4loxP/+VilCre), 3 male mice, adult (6-8 wk). Experiment Overall Design: A total of nine Mouse Genome 430_2.0 arrays were hybridized for this study. Experiment Overall Design: Jejunum was defined as 10 cm from the pyloric sphincter, and ileum was defined as 1 cm from the cecum. The animals used to harvest control jejunum and ileum were independent of each other.

Project description:BackgroundGATA transcription factors are essential for self-renewal of the small intestinal epithelium. Gata4 is expressed in the proximal 85% of small intestine while Gata6 is expressed throughout the length of small intestine. Deletion of intestinal Gata4 and Gata6 results in an altered proliferation/differentiation phenotype, and an up-regulation of SAM pointed domain containing ETS transcription factor (Spdef), a transcription factor recently shown to act as a tumor suppressor. The goal of this study is to determine to what extent SPDEF mediates the downstream functions of GATA4/GATA6 in the small intestine. The hypothesis to be tested is that intestinal GATA4/GATA6 functions through SPDEF by repressing Spdef gene expression. To test this hypothesis, we defined the functions most likely regulated by the overlapping GATA6/SPDEF target gene set in mouse intestine, delineated the relationship between GATA6 chromatin occupancy and Spdef gene regulation in Caco-2 cells, and determined the extent to which prevention of Spdef up-regulation by Spdef knockout rescues the GATA6 phenotype in conditional Gata6 knockout mouse ileum.ResultsUsing publicly available profiling data, we found that 83% of GATA6-regulated genes are also regulated by SPDEF, and that proliferation/cancer is the function most likely to be modulated by this overlapping gene set. In human Caco-2 cells, GATA6 knockdown results in an up-regulation of Spdef gene expression, modeling our mouse Gata6 knockout data. GATA6 occupies a genetic locus located 40 kb upstream of the Spdef transcription start site, consistent with direct regulation of Spdef gene expression by GATA6. Prevention of Spdef up-regulation in conditional Gata6 knockout mouse ileum by the additional deletion of Spdef rescued the crypt cell proliferation defect, but had little effect on altered lineage differentiation or absorptive enterocytes gene expression.ConclusionSPDEF is a key, immediate downstream effecter of the crypt cell proliferation function of GATA4/GATA6 in the small intestine.

Project description:Background & aimsPatterning of the small intestinal epithelium along its cephalocaudal axis establishes three functionally distinct regions: duodenum, jejunum, and ileum. Efficient nutrient assimilation and growth depend on the proper spatial patterning of specialized digestive and absorptive functions performed by duodenal, jejunal, and ileal enterocytes. When enterocyte function is disrupted by disease or injury, intestinal failure can occur. One approach to alleviate intestinal failure would be to restore lost enterocyte functions. The molecular mechanisms determining regionally defined enterocyte functions, however, are poorly delineated. We previously showed that GATA binding protein 4 (GATA4) is essential to define jejunal enterocytes. The goal of this study was to test the hypothesis that GATA4 is sufficient to confer jejunal identity within the intestinal epithelium.MethodsTo test this hypothesis, we generated a novel Gata4 conditional knock-in mouse line and expressed GATA4 in the ileum, where it is absent.ResultsWe found that GATA4-expressing ileum lost ileal identity. The global gene expression profile of GATA4-expressing ileal epithelium aligned more closely with jejunum and duodenum rather than ileum. Focusing on jejunal vs ileal identity, we defined sets of jejunal and ileal genes likely to be regulated directly by GATA4 to suppress ileal identity and promote jejunal identity. Furthermore, our study implicates GATA4 as a transcriptional repressor of fibroblast growth factor 15 (Fgf15), which encodes an enterokine that has been implicated in an increasing number of human diseases.ConclusionsOverall, this study refines our understanding of an important GATA4-dependent molecular mechanism to pattern the intestinal epithelium along its cephalocaudal axis by elaborating on GATA4's function as a crucial dominant molecular determinant of jejunal enterocyte identity. Microarray data from this study have been deposited into NCBI Gene Expression Omnibus (http://www.ncbi.nlm.nih.gov/geo) and are accessible through GEO series accession number GSE75870.

Dataset Information

Conditional Gata4 deletion in mice induces bile acid absorption in the proximal small intestine.

Publications

Conditional Gata4 deletion in mice induces bile acid absorption in the proximal small intestine.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets