Drosophila oogenesis: a model for studying nuclear actin

Tucker Hall, Room 111

A major focus of the Tootle Lab is to understand the cellular functions of prostaglandins, a class of short-range lipid signaling molecules, using Drosophila oogenesis as a model. One cellular function of prostaglandins is to regulate actin cytoskeletal dynamics to drive late-stage follicle morphogenesis. During our studies on the actin cytoskeleton, we attempted to employ numerous tools for imaging actin dynamics live. We found that most of these tools severely disrupt the actin cytoskeleton, but surprisingly, also result in the stage-specific accumulation of nuclear actin filaments or rods. This finding sparked a whole new direction in the lab, uncovering the roles of nuclear actin during oogenesis. We identified three tools that allow us to observe endogenous nuclear actin and find they label distinct pools of nuclear actin. But each tool also labels the nucleolus. Our finding that actin is enriched in the nucleolus was particularly intriguing to us because we had previously found prostaglandins regulate nucleolar morphology, a strong indication prostaglandins regulate nucleolar function. We find prostaglandins limit nuclear actin accumulation to restrict nucleolar activity and protein translation. We also found that nuclear actin is enriched in the early germline cells, including the germline stem cells. Our studies reveal polymeric nuclear actin is required for maintaining the germline stem cells. It likely does so by regulating the nucleolus, heterochromatin, and the nuclear lamina. Whether this nuclear actin function is modulated by prostaglandin signaling remains to be determined. Together these studies reveal nuclear actin is a critical regulator of Drosophila follicle development, and uncovers likely conserved roles of nuclear actin in both the nucleolus and the nucleoskeleton.

Speaker Information

Dr. Tina Tootle
Professor of Biology
University of Iowa