LOCALIZATION OF TRANSCRIPTION FACTOR GATA-4 TO REGIONS OF THE MOUSE EMBRYO INVOLVED IN CARDIAC DEVELOPMENT

To clarify the role of transcription factor GATA-4 in mammalian develo pment, we have determined the pattern of expression of GATA-4 in early postimplantation mouse embryos. Using in situ hybridization and immun ohistochemistry, we find that GATA-4 RNA and protein are expressed in cells associated with heart development. Intraembryonic expression of GATA-4 RNA is first apparent in coelomic epithelial cells of the primi tive streak embryo (approximate to 7.0-7.5 days postcoitum). During fo rmation and bending of the heart tube (approximate to 8 days postcoitu m), GATA-4 RNA and protein are expressed in endocardium, myocardium, a nd embryonic structures containing precardiac mesoderm such as the sep tum transversum and intraembryonic coelomic epithelium. By the onset o f cardiac septation (approximate to 9 days postcoitum), abundant GATA- 4 RNA expression is evident in endocardium, endocardial cushion tissue , and myocardium. Expression of GATA-4 by the myocardium continues thr ough gestation and after birth. The temporal and spacial patterns of G ATA-4 expression support a role for this factor in the regulation of c ardiac differentiation, analogous to the established role of transcrip tion factor GATA-1 in the regulation of hematopoiesis. (C) 1994 Academ ic Press Inc.