Subcellular Localization of RNA in Drosophila Development

Columbia University, New York NY

Investigators

Abstract

The generation of cellular asymmetry is a key event in many developmental processes. One important mechanism that cells use to achieve asymmetry is subcellular localization of RNA. In the case of an mRNA, localization to a specific site within a cell efficiently targets its protein product to that site. In the Drosophila oocyte, localization of distinct mRNAs to the poles is an essential step in generating the anterior-posterior pattern of the future embryo. This research examines components of a ribonucleoprotein (RNP) complex identified previously because of its role in RNA localization: these components are the Exuperantia (Exu) and Ypsilon Schachtel (Yps) proteins, and oskar (osk) mRNA. An important hypothesis of the project is that this RNP complex functions to both transport mRNAs (including osk mRNA) in the cytoplasm to their sites of localization in the oocyte, and to regulate the translation of these transported mRNAs. This research also addresses the role played by the microtubule cytoskeleton in transporting localized mRNAs. Yps is a member of the Y-Box family of proteins; other Y-Box proteins are known to bind RNA and regulate translation. Preliminary results indicate that the yps gene expresses more than one transcript. These transcripts and any alternatively encoded protein isoforms will be characterized, and their expression patterns determined. Genetic and biochemical experiments will determine if Yps acts as a translational repressor of osk mRNA. The Exu protein is a novel protein that plays an essential role in RNA localization, and interacts directly with Yps. A domain analysis of the Exu protein will address the roles played by this protein in mediating mRNA localization, and the association of the complex with microtubules.