A DROSOPHILA GATA FAMILY MEMBER THAT BINDS TO ADH REGULATORY SEQUENCES IS EXPRESSED IN THE DEVELOPING FAT-BODY

We have identified a Drosophila transcription factor that binds a sequ ence element found in the larval promoters of all known alcohol dehydr ogenase (Adh) genes. DNA sequence analysis of cDNA clones encoding thi s protein, box A-binding factor (ABF), reveals that it is a member of the GATA family of transcriptional regulatory factors. ABF-binding sit es within the D. mulleri and D. melanogaster larval Adh promoters func tion as positive regulatory elements and in cotransfection experiments , ABF functions as a transcriptional activator. In further support of a role for ABF in the regulation of Adh expression, ABF mRNA is expres sed in the embryonic fat body, a tissue that contains high levels of A dh mRNA. Our studies demonstrate that the fat body develops from segme ntally repeated clusters of mesodermal cells, which later expand and c oalesce to form the mature fat body. These observations establish ABF as the earliest known fat body precursor marker in the Drosophila embr yo. Together with the established role of GATA factors during mammalia n development, these results suggest that ABF may play a key role in t he organogenesis of the fat body.