Home  |   Archive  |   Online Submission  |   News & Events  |   Subscribe  |   APFA  |   Society  |   Contact Us  |   中文版

Ahead of print
Authors' Accepted
Current Issue
Special Issues
Browse by Category

Manuscript Submission

Online Submission
Online Review
Instruction for Authors
Instruction for Reviewers
English Corner new!

About AJA

About AJA
Editorial Board
Contact Us

Resources & Services

Email alert

Download area

Copyright licence
EndNote style file
Manuscript word template
Guidance for AJA figures
    preparation (in English)

Guidance for AJA figures
    preparation (in Chinese)

Proof-reading for the

AJA Club (in English)
AJA Club (in Chinese)


Volume 21, Issue 4 (July 2019) 21, 337–344; 10.4103/aja.aja_99_18

Protein kinase A inhibition induces EPAC-dependent acrosomal exocytosis in human sperm

Diana Itzhakov1, Yeshayahu Nitzan2, Haim Breitbart1

1 The Mina and Everard Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
2 Department of Clinical Laboratory Science, Zefat Academic College, Zefat 1320611, Israel

Correspondence: Dr. H Breitbart (haim.breitbart@biu.ac.il)



To interact with the egg, the spermatozoon must undergo several biochemical and motility modifications in the female reproductive tract, collectively called capacitation. Only capacitated sperm can undergo acrosomal exocytosis, near or on the egg, a process that allows the sperm to penetrate and fertilize the egg. In the present study, we investigated the involvement of cyclic adenosine monophosphate (cAMP)-dependent processes on acrosomal exocytosis. Inhibition of protein kinase A (PKA) at the end of capacitation induced acrosomal exocytosis. This process is cAMP-dependent; however, the addition of relatively high concentration of the membrane-permeable 8-bromo-cAMP (8Br-cAMP, 0.1 mmol l−1) analog induced significant inhibition of the acrosomal exocytosis. The induction of acrosomal exocytosis by PKA inhibition was significantly inhibited by an exchange protein directly activated by cAMP (EPAC) ESI09 inhibitor. The EPAC selective substrate activated AE at relatively low concentrations (0.02–0.1 μmol l−1), whereas higher concentrations (>5 μmol l−1) were inhibitory to the AE induced by PKA inhibition. Inhibition of PKA revealed about 50% increase in intracellular cAMP levels, conditions under which EPAC can be activated to induce the AE. Induction of AE by activating the actin severing-protein, gelsolin, which causes F-actin dispersion, was inhibited by the EPAC inhibitor. The AE induced by PKA inhibition was mediated by phospholipase C activity but not by the Ca2+-channel, CatSper. Thus, inhibition of PKA at the end of the capacitation process induced EPAC/phospholipase C-dependent acrosomal exocytosis. EPAC mediates F-actin depolymerization and/or activation of effectors downstream to F-actin breakdown that lead to acrosomal exocytosis.

Keywords: acrosomal exocytosis; exchange protein directly activated by cyclic adenosine monophosphate; protein kinase A; sperm

Full Text | PDF |

Browse:  440
Copyright 1999-2017  Shanghai Materia Medica, Shanghai Jiao Tong University.  All rights reserved