Role of sperm αvβ3 integrin in mouse fertilization

Abstract

Oocyte integrins have been described as essential for fertilization. But this concept has been challenged by deletion experiments. Recently, we have shown that sperm integrin a6b1 plays a determinant role in mouse gamete interaction. In this study, we demonstrate the presence of avb3 integrin by Western blot and immunofluorescence on the sperm membrane. Oocytes and/or sperm preincubations with anti-av or anti-b3 antibodies were performed before in vitro fertilization on cumulus-intact and zona-free egg assays. We observed inhibitory effects on the fusion process mostly by means of sperm function. An antibody directed against vitronectin inhibited gametes fusion, whereas the presence of exogenous vitronectin increased its efficiency. We suggest that vitronectin (on multimeric forms) can play a first nonspecific link corresponding to loosely bound spermatozoa to oocyte and that this link could be mediated by means of oocyte proteoglycans or integrins, and sperm avb3 integrin. Developmental Dynamics 239:773-783,

Membrane transfer from oocyte to sperm occurs in two CD9-independent ways that do not supply the fertilising ability of Cd9-deleted oocytes

“…This second hypothesis is supported by the sperm dynamic expression of some proteins. Indeed, some sperm proteins, like a6b1, avb3 integrins and Izumo 1, have been shown to appear gradually with capacitation and acrosome reaction (Inoue et al 2005, Barraud-Lange et al 2007b, Boissonnas et al 2010. The exchanges between the oocyte and sperm membranes are more important when the egg is not fertilised (Barraud-Lange et al 2007a) and the sperm acrosome reacted (this study), i.e.…”

Oviductosome-Sperm Membrane Interaction in Cargo Delivery

“…Effect of Anti-␣V Antibodies on OVS-Sperm Fusion-Acrosome-reacted sperm and OVS were separately pre-incubated in HTF medium supplemented with 50 g/ml anti-␣v antibodies for 40 min, as previously used to inhibit sperm-oocyte fusion (34). Sperm were then washed and OVS diluted 1:100 in HTF for co-incubation with untreated OVS and sperm, respectively.…”

“…To confirm the inhibitory effect of the RGD peptide on OVS-sperm fusion, exogenous ligands (with the RGD interaction motif) for two integrin receptors, ␣v␤3 known to be abundantly expressed on the head in acrosome-reacted mouse and human sperm (34,37) and ␣5␤1 in capacitated human sperm (37,38), were used to block receptorligand interaction in co-incubation assays. When acrosomereacted and capacitated sperm were co-incubated with exogenous VN and FN, respectively, there was a marked reduction in the number of microvesicles present on the sperm membrane.…”

The integrin-binding motif RGDS induces protein tyrosine phosphorylation without activation in Bufo arenarum (Amphibia) oocytes

“…With the exception of the aV integrin subunit, we did not detect their presence on sperm, suggesting that these cells do not express these integrin subunits. However, a5, b1 and b3 integrin subunits have been reported as present in mammalian sperm (Thys et al 2009, Boissonnas et al 2010. The possibility of a very low expression of these proteins to explain our results is lowered by the fact that the proteins extracted from 8!10 6 sperm cells were loaded onto each lane for the western blot studies.…”

“…Blobel et al (1992) suggested a model for sperm-egg plasma membrane (PM) interaction in the guinea pig, where the binding results from an integrin on the egg adhering to an integrin ligand (disintegrin) on the sperm. In mammalian sperm, the binding to the egg membrane integrins is believed to be mediated by A disintegrin and A metalloprotease domain (ADAM) proteins (also known as metalloprotease/disintegrin/cysteine-rich (MDC)), although other candidates also have been proposed (Boissonnas et al 2010, Yang et al 2010. In different mammals, the role of integrins in fertilization has been the subject of numerous, and some of them quite contradictory, reports (Almeida et al 1995, Linfor & Berger 2000, He et al 2003, Sessions et al 2006, Tatone & Carbone 2006.…”