title: Cooperation between GATA4 and TGF-beta signaling regulates intestinal epithelial gene expression.
abstract: Members of the transforming growth factor-beta (TGF-beta) family have been shown to play an important role in the regulation of gut epithelial gene expression. We have used the intestinal alkaline phosphatase (IAP) and intestinal fatty acid binding protein (IFABP) promoters to dissect the mechanisms by which TGF-beta1 signaling regulates gut epithelial gene expression. TGF-beta signaling alone was not sufficient for activation of IAP and IFABP promoters. However, TGF-beta signaling cooperated with the gut epithelial transcription factor GATA4 to synergistically activate IAP and IFABP promoters. Coexpression of GATA4 along with the TGF-beta1 signal transducing downstream effectors such as Smad2, 3, and 4 resulted in synergistic activation of both IAP and IFABP promoters. This synergistic activation was reduced by simultaneous expression of dominant-negative Smad4. -40 and -89 GATA binding sites in the IFABP promoter were required for the synergistic activation by Smad2, 3, and 4 and GATA4. GATA4 and Smad2, 3, and 4 physically associated with each other and this interaction was mediated through the MH2 domain of Smad2, 3, and 4 and the second zinc finger and the COOH-terminal basic domain of GATA4. The COOH-terminal activation domain and the Smad-interacting second zinc finger domain of GATA4 were required for the synergistic activation of the IFABP promoter. Naturally occurring oncogenic mutations within the GATA4-interacting MH2 domain of Smad2 reduced the coactivation of IFABP promoter by Smad2 and GATA4. Our results suggest that the TGF-beta signaling regulates gut epithelial gene expression by targeting GATA4.
authors.affiliation: Michael E. DeBakey Dept. of Surgery, Michael E. DeBakey VA Medical Center, Baylor College of Medicine, 2002 Holcombe Blvd., Houston, Texas 77030, USA. elaguli@bcm.tmc.edu
authors.forename: Narasimhaswamy S
authors.initials: NS
authors.lastname: Belaguli
authors.forename: Mao
authors.initials: M
authors.lastname: Zhang
authors.forename: Mohammed
authors.initials: M
authors.lastname: Rigi
authors.forename: Muhammad
authors.initials: M
authors.lastname: Aftab
authors.forename: David H
authors.initials: DH
authors.lastname: Berger
mesh_terms: D030201:Activin Receptors, Type I / Q000378:metabolism; D000469:Alkaline Phosphatase; D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D050556:Fatty Acid-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D050991:GATA4 Transcription Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D058851:GPI-Linked Proteins; D015870:Gene Expression; D017930:Genes, Reporter; D045325:HCT116 Cells; D000882:Haplorhini; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D008156:Luciferases; D009154:Mutation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism; D051901:Smad4 Protein / Q000378:metabolism; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*; D016335:Zinc Fingers
chemical_list: D000951:Antigens, Neoplasm; D050556:Fatty Acid-Binding Proteins; D050991:GATA4 Transcription Factor; C484170:GATA4 protein, human; D058851:GPI-Linked Proteins; D034741:RNA, Small Interfering; D018125:Receptors, Transforming Growth Factor beta; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; C497796:SMAD4 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein; D051901:Smad4 Protein; D053773:Transforming Growth Factor beta1; D008156:Luciferases; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; C063088:ALPI protein, human; D000469:Alkaline Phosphatase