Abstract
Epidermal growth factor receptor (EGFR) signaling is precisely regulated in space and time during Drosophila development. In the Drosophila ovary, both the anterior-posterior and dorsal-ventral axes of the egg chamber are established by cellular interations between germline cells and somatic follicle cells, and EGFR signaling is involved in the processes. Kekkon-1 (kek1), an EGFR targeted gene, acts in a negative feedback loop to regulate the activity of the EGF receptor, yet the detailed mechanisms of how EGFR signaling regulates the expression of kek1 during oogenesis remain unclear. To screen molecules required for kek1 expression, we need to identify the minimal kek1 enhancer. Here, we analyzed the kek1 locus, finding that 3.2kb region upstream of the kek1 transcriptional start is sufficient for kek1 expression, which is observed in the posterior follicle cells at early stages and in a triangle of dorsal-anterior follicle cells at stage 10B. We then dissect the 3.2kb region into three fragments: F1, F2, and F3, finding that only the F3 fragment (879 nucleotides) could provide the similar kek1 expression. The result suggests that the kek1 regulatory elements might be located in the F3 fragment. Later, further deletion analyses narrow the kek1 regulatory elements down.