THE ROLE OF BMP-4 AND GATA-2 IN THE INDUCTION AND DIFFERENTIATION OF HEMATOPOIETIC MESODERM IN XENOPUS-LAEVIS

Vertebrate embryonic blood formation is regulated by factors that part icipate in dorsal-ventral patterning and mesoderm induction. The GATA- binding transcription factors are required for normal hematopoiesis an d are expressed during gastrulation when ventral mesoderm (VM) is indu ced to form blood. Based on the recent demonstration that bone morphog enetic protein (BMP-4) is a potent ventralizing factor and inducer of hematopoietic tissue, we hypothesized that GATA-2 could be induced or activated by BMP-4. Here we demonstrate that BMP-4 can stimulate GATA- 5 expression, and that expression of a dominant negative BMP-4 recepto r can suppress GATA-2 induction by BMP-4 in ventral mesoderm, Over-exp ression of GATA-2 in ventral mesoderm leads to increased globin produc tion and forced expression of GATA-2 in primitive ectoderm adjacent to ventral mesoderm also stimulates globin expression. Our results sugge st that BMP-4 and GATA-2 can function in two adjacent germ layers, mes oderm and ectoderm, to participate in blood cell formation during embr yogenesis. (C) 1996 by The American Society of Hematology.