Sperm chemotaxis is a cell guidance mechanism that orients spermatozoa towards the egg(1). Recently, we observed that: I) a concentration gradient of progesterone (P) is formed along the cumulus (2), II) a subpopulation (~10%) of capacitated spermatozoa chemotactically respond to pM P gradients(2), III) the steroid is probably the unique attractant secreted by the cumulus cells(3), and IV) the molecular pathways involved in the chemotactic response mediated by P are mAC-cAMP-PKA and sGC-cGMP-PKG, in addition to calcium mobilization(4). The aim of this work was to further study the sperm chemotaxis mediated by P by verifying at which step of the signal transduction pathway, tyr-protein phosphorylation (if any) takes place. Capacitated human spermatozoa were stuck to a chemotaxis chamber and then confronted to pM concentration of P. By means of immunohistochemistry, we observed that only acrosome intact capacitated spermatozoa expressed a specific pattern of tyr-protein phosphorylation in the sperm equatorial region and tail, which was activated during chemotaxis, by mAC-cAMP-PKA pathway. These results suggest that during sperm chemotaxis mediated by P, the proteins are phosphorylated in tyr in the sperm equatorial region and tail, at early steps of the signal transduction pathway.
(1). Eisenbach and Giojalas (2006). Nature Rev Mol Cell Biol,7:276-85.
(2). Teves, Barbano, Guidobaldi, Sanchez, Miska, Giojalas (2006) Fertil Steril, 86:745-49.
(3). Guidobaldi, Teves, Uñates, Anastasia, Giojalas (2008) PlosOne, 3:e3040.
(4). Teves, Guidobaldi, Uñates, Sanchez, Miska, Giojalas (2007) I Soc Biol Arg, Cba, Ago 2007.
