Role of phosphatidylinositol-4-phosphate 5′ kinase (ppk-1) in ovulation of Caenorhabditis elegans

During Caenorhabditis elegans ovulation, the somatic gonad integrates signals from germ cells and propels a mature oocyte into the spermatheca for fertilization. Previous work suggests that phosphoinositide signaling plays important roles in C. elegans fertility. To fully understand inositol-1,4,5-trisphosphate (IP3) signaling in ovulation, we have examined the function of phosphatidylinositol-4-phosphate 5′ kinase (PIP5K) in C. elegans. Our results show that the C. elegans PIP5K homolog, ppk-1, is essential for ovulation in C. elegans; ppk-1 is mainly expressed in somatic gonad, and depletion of ppk-1 expression causes defective ovulation, reduced gonad sheath contractility, and sterility. Increased IP3 signaling compensates for ppk-1 (RNAi)-induced sterility, suggesting that ppk-1 is linked to IP3 signaling. These results demonstrate that ppk-1 plays an essential role in IP3 signaling and cytoskeleton organization in somatic gonad.