Prostaglandins are emerging as key lipid signals that regulate actin cytoskeletal remodeling. There are five well-characterized types of prostaglandins, each initiating one or more signaling cascades, and modulating actin dynamics in a cell-type specific manner. Actin is the most abundant protein in cells and generates polarized filaments that are further organized into a variety of structures to mediate basic biological functions such as cell shape, adhesion, division, and migration. Such remodeling, or rearrangement, of the actin cytoskeleton is mediated by the coordinated efforts of greater than 100 known actin binding proteins, and is tightly regulated by numerous signaling pathways. While it is clear that prostaglandins are signals that regulate actin remodeling, how they do so is poorly understood. To elucidate the molecular mechanisms utilized by prostaglandins to regulate actin dynamics in vivo, Drosophila oogenesis was established as a new model for studying prostaglandin signaling. Both pharmacologic and genetic perturbations of prostaglandin signaling result in the loss of the actin structures necessary for the contractile process by which the cytoplasmic contents of the support or nurse cells are dumped into the oocyte. The project exploits Drosophila's short generation time, the use of a non-essential adult tissue, the well-characterized process of nurse cell dumping, available genetic mutations in genes encoding cytoskeletal regulators, and the ability to perform pharmacologic and live-imaging studies on cultured follicles (eggs). Using this follicle maturation system, the mechanism by which signaling by two prostaglandins regulates actin dynamics in a normal, physiological context - where cells must interact with and respond to a number of other cell types - will be elucidated . Using high-resolution confocal microscopy of fixed and living samples those aspects of actin cytoskeletal dynamics that are regulated by prostaglandins will be determined. The distinct, and likely opposing, roles of the two prostaglandins during cytoskeletal remodeling will then be determined. Furthermore, a screen will be performed to identify the actin binding proteins that mediate prostaglandin-dependent actin remodeling. The proteins utilized to directly mediate such remodeling are conserved from Drosophila to humans; therefore, the mechanistic insights resulting from the proposed work will be widely applicable. Thus, the Drosophila follicle maturation system is uniquely positioned to provide critical insights into conserved mechanisms by which two specific prostaglandins differentially regulate actin cytoskeletal remodeling.
Broader Impacts This project will provide research and educational opportunities for students, and will lead to the development of novel tools and methodologies. Undergraduates from both the University of Iowa and other institutions will contribute in this research. Additionally, this project will provide Ph.D thesis projects for graduate students. The research will be presented by both the undergraduate and graduate students at the University's monthly Drosophila research meeting, which was started by the PI. The project will also contribute to graduate education through a Genetics course, where the PI teaches Drosophila genetic methods; a Cell Migration course, where the PI teaches Drosophila methods, image methods/analyses, and cell biology, and a Biochemistry course, where the PI teaches lipid biology and analysis techniques. The research will also lead to the development of new tools for imaging actin dynamics in vivo and quantitative methods of 3D and 4D image analysis.