The Role of Oatp74D, an Ecdysone Importer, in the Drosophila ovary.

Abstract

Oogenesis is the progression of germ cells through mitotic expansion, differentiation into an oocyte, and successful completion of meiosis. Steroid hormones play critical roles in this process in diverse organisms. In Drosophila, the main steroid hormone, ecdysone, facilitates female fertility in part by promoting germline stem cell self-renewal and germ cell differentiation. Foundational studies demonstrated that ecdysone is synthesized primarily in egg chambers during mid-oogenesis; however, more recent data suggests that somatic escort cells, which support germline stem cell differentiation, may also produce ecdysone. Understanding how ecdysone is transported and received in the ovary would help resolve these disparate results. Recent studies support the hypothesis that ecdysone needs Oatp74D, a membrane transport protein, to import ecdysone into cells, challenging the popular assumption that steroids passively transport through membranes. Using multiple protein localization tools, and two different Oatp74D RNAi lines, my research provides new insights into the function of Oatp74D in the Drosophila ovary. Oatp74D works through intra-organ communication between the neurons and germarium but does not have any specific role in intracellular communication or protein localization within the ovary.