Adhesion proteins expressed on human gamete surfaces and egg activation

The initiation and propagation of a Ca2+ signal through the egg seems to be the pivotal event in triggering of meiosis resumption. Over the past decad e evidence has accumulated suggesting that sperm contact is essential for t his phenomenon to occur in most physiological groups. Given their ability t o transduce signals, adhesive proteins which are involved in various bindin g mechanisms such as cell migration, lymphocyte activation, phagocytosis an d virus fusion may play a similar role in fertilization. They have been the subject of serious investigation in non-human mammals and some emerging da ta indicate that they are active in humans as well. Our goal is to review t he presence of such molecules on human gametes and their relevant physiolog ical role, i.e., integrins and their ligands, selectins, IgG Fc receptors a nd leucocyte differentiation markers. We will discuss how they might trigge r egg activation through signaling pathways in light of their identified fu nctions in other adhesion systems. The putative participation of specific h uman sperm proteins will also be evaluated. (C) 2000 Editions scientifiques et medicales Elsevier SAS.