Alpha6beta1 integrin expressed by sperm is determinant in mouse fertilization.
BACKGROUND
Based on inhibition tests, the alpha6beta1 integrin was suggested to be a sperm receptor, but further experiments using gene deletion techniques have shown that neither oocyte alpha6, nor beta1 integrin subunits were essential for mouse fertilization.


RESULTS
Using Western blot analysis and immunofluorescence, we showed that the mouse sperm expresses the alpha6beta1 integrin. As for oocyte, binding of GoH3 anti-alpha6 antibody to sperm induces a specific inhibition of sperm fertilizing ability. Comparing zona-intact and zona-free eggs in fusion tests, we showed that the removal of the zona pellucida by acid treatment bypasses fertilizing oocyte alpha6beta1 integrin's function in the adhesion/fusion process.


CONCLUSIONS
These findings show that alpha6beta1 integrin is expressed by both gametes and is functional in their membranes interaction. These results and previous reports, about fertilization of alpha6 or beta1 integrin subunits deleted oocytes by wild type sperm, suggest that the presence of alpha6beta1 integrin on one of the two gamete membranes can rescue the fertilization process. This hypothesis is further supported by the exchange of membrane fragments occurring between gametes prior to fusion that we recently reported.
Barraud-Lange
Virginie
V
Biologie de la Reproduction, UFR SMBH, Université Paris 13, Bobigny, France, Service d'Histologie-Embryologie-Cytogénétique, Hôpital Jean Verdier (AP-HP), Bondy, France. raud@smbh.univ-paris13.fr
Naud-Barriant
Nathalie
N
Saffar
Line
L
Gattegno
Liliane
L
Ducot
Beatrice
B
Drillet
Anne-Sophie
AS
Bomsel
Morgane
M
Wolf
Jean-Philippe
JP
Ziyyat
Ahmed
A
D000818:Animals; D005260:Female; D005306:Fertilization / Q000235:genetics*; D005307:Fertilization in Vitro; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D039121:Integrin alpha6beta1 / Q000235:genetics*; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D009865:Oocytes / Q000378:metabolism; D013075:Sperm Capacitation; D013084:Sperm-Ovum Interactions / Q000235:genetics; D013094:Spermatozoa / Q000378:metabolism*; D015044:Zona Pellucida / Q000378:metabolism
D039121:Integrin alpha6beta1