title: An Ebox element in the proximal Gata4 promoter is required for Gata4 expression in vivo.
abstract: GATA4 is an essential transcription factor required for the development and function of multiple tissues, including a major role in gonadogenesis. Despite its crucial role, the molecular mechanisms that regulate Gata4 expression in vivo remain poorly understood. We recently found that the Gata4 gene is expressed as multiple transcripts with distinct 5' origins. These co-expressed alternative transcripts are generated by different non-coding first exons with transcripts E1a and E1b being the most prominent. Moreover, we previously showed that an Ebox element, located in Gata4 5' flanking sequences upstream of exon 1a, is important for the promoter activity of these sequences in cell lines. To confirm the importance of this element in vivo, we generated and characterized Gata4 Ebox knockout mice. Quantitative PCR analyses realized on gonads, heart and liver at three developmental stages (embryonic, pre-pubertal and adult) revealed that the Ebox mutation leads to a robust and specific decrease (up to 89%) of Gata4 E1a transcript expression in all tissues and stages examined. However, a detailed characterization of the gonads revealed normal morphology and GATA4 protein levels in these mutants. Our qPCR data further indicate that this outcome is most likely due to the presence of Gata4 E1b mRNA, whose expression levels were not decreased by the Ebox mutation. In conclusion, our work clearly confirms the importance of the proximal Ebox element and suggests that adequate GATA4 protein expression is likely protected by a compensation mechanism between Gata4 E1a and E1b transcripts operating at the translational level.
authors.affiliation: Department of Biological Sciences and BioMed Research Center, Faculty of Sciences, University of Quebec at Montreal, Quebec, Canada.
authors.forename: Alain
authors.initials: A
authors.lastname: Boulende Sab
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Bouchard
authors.forename: Mélanie
authors.initials: M
authors.lastname: Béland
authors.forename: Bruno
authors.initials: B
authors.lastname: Prud'homme
authors.forename: Ouliana
authors.initials: O
authors.lastname: Souchkova
authors.forename: Robert S
authors.initials: RS
authors.lastname: Viger
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pilon
mesh_terms: D000818:Animals; D005091:Exons / Q000235:genetics; D005260:Female; D005298:Fertility; D050991:GATA4 Transcription Factor / Q000235:genetics*; D005786:Gene Expression Regulation; D018390:Gene Targeting; D007438:Introns / Q000235:genetics; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation / Q000235:genetics; D059372:Nucleotide Motifs / Q000235:genetics; D010053:Ovary / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013737:Testis / Q000378:metabolism / Q000473:pathology; D014158:Transcription, Genetic
chemical_list: D050991:GATA4 Transcription Factor; C484171:Gata4 protein, mouse; D012333:RNA, Messenger