Abstract: | Ceramide, a product of sphingomyelin turnover, is a lipid secondmessenger that mediates diverse signaling pathways, including thoseleading to cell cycle arrest and differentiation. The mechanism(s) bywhich ceramide signals downstream events have not been fully elucidated. Here we show that, in Xenopuslaevis oocytes, ceramide-induced maturation isassociated with the release of intracellular calcium stores. Ceramidecaused a dose-dependent elevation in the second messenger inositol1,4,5-trisphosphate (IP3) viaactivation of Gq/11 andphospholipase C- X. Elevation ofIP3, in turn, activated theIP3 receptor calcium releasechannel on the endoplasmic reticulum, resulting in a rise incytoplasmic calcium. Thus our study demonstrates that cross talkbetween the ceramide and phosphoinositide signaling pathways modulatesintracellular calcium homeostasis. |