The long-term objective of this proposed research is to understand the hormonal control of a developmentally regulated gene. The Drosophila larval serum protein gene, LSP-2, will serve as a model system since its transcription occurs only in the fat body tissue during the last stage of larval development and is stimulated by high titers of the arthropod hormone, ecdysterone. The two major objectives of this project will be to identify and characterize 1) the cis-acting regulatory DNA sequences and 2) LSP-2-specific transcription factors required for both initiation and ecdysterone stimulation of LSP-2 transcription. The specific aims of this proposal are 1) Identification of cis-acting and LSP-2 regulatory sequences by gene transfer of LSP-2- hybrid genes into cultured Drosophila cells, 2) Mapping of DNase- hypersensitive sites surrounding LSP-2 genes in transformed cell lines and larval fat body tissue to determine changes in chromatin associated with gene activity, 3) Demonstration and characterization of non-histone chromosomal proteins bound to cis-acting LSP-2 regulatory sequences during expression in cultured cells and larval fat body tissue. This study will serve to elucidate at the molecular level mechanisms by which gene expression can be regulated in terms of tissue, hormone and stage of development.
