Crosstalk between protein kinases A and C regulates sea urchin sperm motility

Abstract

Summary Fertilization, a crucial event for species preservation, in sea urchins, as in many other organisms, requires sperm motility regulation. In Strongylocentrotus purpuratus sea urchins, speract, a sperm chemoattractant component released to seawater from the outer egg layer, attracts sperm after binding to its receptor in the sperm flagellum. Previous experiments performed in demembranated sperm indicated that motility regulation in these cells involved protein phosphorylation mainly due to the cAMP-dependent protein kinase (PKA). However, little information is known about the involvement of protein kinase C (PKC) in this process. In this work, using intact S. purpuratus sea urchin sperm, we show that: (i) the levels of both phosphorylated PKA (PKA substrates) and PKC (PKC substrates) substrates change between immotile, motile and speract-stimulated sperm, and (ii) the non-competitive PKA (H89) and PKC (chelerythrine) inhibitors diminish the circular velocity of sperm and alter the phosphorylation levels of PKA substrates and PKC substrates, while the competitive inhibitors Rp-cAMP and bisindolylmaleimide (BIM) do not. Altogether, our results show that both PKA and PKC participate in sperm motility regulation through a crosstalk in the signalling pathway. These results contribute to a better understanding of the mechanisms that govern motility in sea urchin sperm.

De Novo Assembly of the Genome of the Sea Urchin Paracentrotus lividus (Lamarck 1816)

“…White et al [32] demonstrated the existence of a correlation between motility and the level of phospho-PKC substrates, so PKC activation and phosphorylation of its target proteins represent a significant requirement for the maintenance of motility in the spermatozoa of intact sea urchins. In S. purpuratus, the levels of PKC substrates contribute to the production of immotile and motile spermatozoa, and non-competitive PKC inhibitors are involved in diminishing the circular velocity of spermatozoa [36].…”