Author(s): Cohen G, Rubinstein S, Gur Y, Breitbart H
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Abstract Mammalian spermatozoa should reside in the female reproductive tract for a certain time before gaining the ability to fertilize. During this time, the spermatozoa undergo a series of biochemical processes collectively called capacitation. We recently demonstrated that actin polymerization is a necessary step in the cascade leading to capacitation. We demonstrate here for the first time a role for phospholipase D (PLD) in the induction of actin polymerization and capacitation in spermatozoa. The involvement of PLD is supported by specific inhibition of F-actin formation during sperm capacitation by PLD inhibitors and the stimulation of fast F-actin formation by exogenous PLD or phosphatidic acid (PA). Moreover, PLD activity is enhanced during capacitation before actin polymerization. Protein kinase A (PKA), known to be active in sperm capacitation, and protein kinase C (PKC), involved in the acrosome reaction, can both activate PLD and actin polymerization. We suggest that PKA- and PKC-dependent signal transduction pathways can potentially lead to PLD activation; however, under physiological conditions, actin polymerization depends primarily on PKA activity. Activation of PKA during capacitation causes inactivation of phospholipase C, and as a result, PKC activation is prevented. It appears that PKA activation promotes sperm capacitation whereas early activation of PKC during capacitation would jeopardize this process.
This article was published in Dev Biol
and referenced in Journal of Microbial & Biochemical Technology