title: Over-expression of GATA-6 in Xenopus embryos blocks differentiation of heart precursors.
abstract: Xenopus GATA-6 transcripts are first detected at the beginning of gastrulation in the mesoderm, and subsequent domains of expression include the field of cells shown to have heart-forming potential. In this region, GATA-6 expression continues only in those cells that go on to form the heart; however, a decrease occurs prior to terminal differentiation. Artificial elevation of GATA-6, but not GATA-1, prevents expression of both cardiac actin and heart-specific myosin light chain. This effect is heart-specific because cardiac actin expression is unaffected in somites. Expression of the earlier marker XNkx-2.5 was unaffected and morphological development of the heart was initiated independently of the establishment of the contractile machinery. We conclude that a reduction in the level of GATA-6 is important for the progression of the cardiomyogenic differentiation programme and that GATA-6 may act to maintain heart cells in the precursor state. At later stages, when the elevated GATA-6 levels had decayed, differentiation ensued but the number of cells contributing to the myocardium had increased, suggesting either that the blocked cells had proliferated or that additional cells had been recruited.
authors.affiliation: Developmental Biology Research Centre, The Randall Institute, King's College London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Gove
authors.forename: M
authors.initials: M
authors.lastname: Walmsley
authors.forename: S
authors.initials: S
authors.lastname: Nijjar
authors.forename: D
authors.initials: D
authors.lastname: Bertwistle
authors.forename: M
authors.initials: M
authors.lastname: Guille
authors.forename: G
authors.initials: G
authors.lastname: Partington
authors.forename: A
authors.initials: A
authors.lastname: Bomford
authors.forename: R
authors.initials: R
authors.lastname: Patient
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D002454:Cell Differentiation; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins; D050993:GATA6 Transcription Factor; D006321:Heart / Q000196:embryology*; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors; D014981:Xenopus; D029867:Xenopus Proteins; D016335:Zinc Fingers
chemical_list: D004268:DNA-Binding Proteins; D050993:GATA6 Transcription Factor; C494758:GATA6 protein, Xenopus; D012333:RNA, Messenger; D014157:Transcription Factors; D029867:Xenopus Proteins; D004247:DNA