TRANSCRIPTIONAL REGULATION OF BLOOD FORMATION DURING XENOPUS DEVELOPMENT

Hematopoiesis is the generation, proliferation and differentiation of hematopoietic stem cells (HSCs) into the erythroid, myeloid and lympho id lineages. The HSC is a ventral mesodermal derivative that arises du e to inductive and patterning processes triggered by bone morphogeneti c protein 4 (BMP-4). Recent studies in Xenopus laevis have identified fled families of transcription factors that participate in hematopoiet ic development. Transcription factor families, such as the SMADs, Mixs and Vents pattern mesoderm to a ventral fate which ultimately results in the expression of hematopoietic-specific transcription factors suc h as GATA-1 and SCL. This transcriptional regulatory network enforces the correct temporal and spatial expression of the blood program.