%0 Journal Article %J Molecular human reproduction %D 2006 %T Evidence for the involvement of proline-directed serine/threonine phosphorylation in sperm capacitation. %A Jha, K N %A Salicioni, A M %A Arcelay, E %A Chertihin, O %A Kumari, S %A Herr, J C %A Visconti, P E %K 1-Methyl-3-isobutylxanthine %K Amino Acid Motifs %K Animals %K Antibodies, Monoclonal %K beta-Cyclodextrins %K Blotting, Western %K Bucladesine %K Butadienes %K Cattle %K Cholesterol %K Cyclic AMP %K Flavonoids %K Humans %K Male %K Mice %K Mitogen-Activated Protein Kinase 1 %K Mitogen-Activated Protein Kinase 3 %K Mitosis %K Nitriles %K Phosphoproteins %K Phosphorylation %K Proline %K Protein Processing, Post-Translational %K Protein-Serine-Threonine Kinases %K Serum Albumin, Bovine %K Sodium Bicarbonate %K Sperm Capacitation %K Spermatozoa %X

To become fertilization competent, mammalian sperm undergo changes in the female reproductive tract termed capacitation. Capacitation correlates with an increase in tyrosine phosphorylation; however, less is known about the role of serine/threonine phosphorylation in this process. Proline-directed phosphorylation is one of the major regulatory phosphorylation events in many cellular processes such as cell proliferation and differentiation. Using mitotic phosphoprotein monoclonal-2 (MPM-2) antibody in this study, we observed that several mouse sperm proteins in the range of 70-250 kDa underwent increased serine/threonine-proline phosphorylation during capacitation. In contrast to the time course of tyrosine phosphorylation, proline-directed phosphorylation could be observed at shorter time points of sperm incubation, and it was found to be independent of NaHCO(3) and adenosine 3'5'-cyclic monophosphate (cAMP). Similar to the regulation of the increase in tyrosine phosphorylation, cholesterol acceptors such as bovine serum albumin (BSA) or 2-hydroxypropyl-beta-cyclodextrin (2-OH-propyl-beta-CD) were essential for the regulation of proline-directed phosphorylation in mouse sperm. Furthermore, it was also found to be BSA dependent in human sperm. Among proline-directed kinases, extracellular signal-regulated kinase 1/2 (ERK1/2) is present in mammalian sperm; nevertheless, U0126 and PD098059, two inhibitors of the ERK pathway, did not block this phosphorylation in mouse sperm. In conclusion, capacitation is associated with an increase in proline-directed phosphorylation linked to cholesterol efflux in the sperm.

%B Molecular human reproduction %V 12 %P 781-9 %8 2006 Dec %G eng %N 12 %1 http://www.ncbi.nlm.nih.gov/pubmed/17050774?dopt=Abstract