GATA-1 inhibits the formation of notochord and neural tissue in Xenopus embryo.
The expression of GATA-1, which encodes for a hemopoietic transcription factor, initiates at gastrula stage in the Xenopus embryo (1). In order to examine a possible function of GATA-1 in dorso-ventral patterning of mesoderm and ectoderm derivatives, the synthesized RNA of GATA-1 was overexpressed in embryonic cells to assess its biological effects. In the embryos injected with GATA-1 RNA in the dorsal marginal zone at 4-cell stage, dorsal epidermis did not cover the vegetal cells so that the gastrulation was not completed. The same dose of GATA-1 RNA injected into ventral marginal zone did not influence the development, and GATA-2 RNA transcribed from the same vector had little effect, suggesting that this phenomenon is physiologically important. The morphological and immunohistochemical studies revealed that notochord and neural tissue were mostly eliminated in the embryos or the dorsal marginal zone explants after injection of GATA-1 RNA. GATA-1 also inhibited neurogenesis in animal cap explants, which was induced by the injection with noggin RNA. Northern blot analysis using dorsal marginal zone explants showed, however, that only a slight amount of alpha-globin message was induced, and cardiac alpha-actin message was retained. Therefore, GATA-1 did not convert completely the dorsal phenotype to the ventral one. Furthermore, the injection of GATA-1 RNA didnot alter the expression of early dorsal and ventral markers at the onset of gastrulation. These results suggest that GATA-1 is an potential inhibitor of the dorsalization and the neurogenesis, but it affects on the specification of dorsal tissues in relatively later steps.
Shibata
K
K
Department of Biology, Faculty of Science, Niigata University, Ikarashi, Niigata, 950-2181, Japan.
Ishimura
A
A
Maéno
M
M
D000199:Actins / Q000235:genetics; D000818:Animals; D019521:Body Patterning; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004475:Ectoderm / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000502:physiology*; D004627:Embryonic Induction / Q000502:physiology*; D004817:Epidermis / Q000502:physiology; D050981:Erythroid-Specific DNA-Binding Factors; D005775:Gastrula / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D008648:Mesoderm / Q000502:physiology; D009420:Nervous System / Q000196:embryology*; D009672:Notochord / Q000502:physiology*; D009687:Nuclear Proteins / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D014981:Xenopus / Q000196:embryology*
D000199:Actins; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D009687:Nuclear Proteins; D014157:Transcription Factors