Exocytosis is triggered by Sphingosine 1-phosphate through the activation of S1P receptors type 1 and 3

SUHAIMAN, LAILA; DE BLAS, GERARDO A; OBEID, LINA M; DARSZON, ALBERTO; MAYORGA, LUIS S; BELMONTE, SILVIA A

Los Cocos, Córdoba

Simposio; First South American Spring Symposium in Signal Transduction and Molecular Medicine; 2010

First South American Spring Symposium in Signal Transduction and Molecular Medicine

Regulated secretion is a central issue for the function of cells; for instance, mammalian sperm acrosomal exocytosis (AE) is essential for egg fertilization. Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid that regulates crucial physiological processes. S1P triggers AE in human sperm by a mechanism involving a Gi-coupled receptor, PLC and PKC activity. Real-time imaging showed an increase of cytosolic Ca2+ upon activation with S1P and pharmacological experiments indicate that the process requires extracellular Ca2+ influx and efflux from intracellular stores. Sphingosine kinase 1, the enzyme that catalyzes S1P synthesis, is not only present in human sperm but active and required for phorbol ester induced AE. Western blot and immunofluorescence demonstrated that S1P receptors 1 and 3 are present in human sperm cells. Specific agonists and antagonists of these receptors affected the AE suggesting that they are involved in this process. We present here the first piece of evidence indicating that S1P receptors are present in human spermatozoa and involved in the signal transduction cascade triggered by S1P leading to the acrosomal exocytosis