Characterisation and role of integrins during gametic interaction and egg activation

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Abstract
Summary: It has recently been proposed that some of the processes induced by fertilisation in mammals may be mediated by integrins. By peforming immunofluorescence labelling and Western blots with antibodies directed against some of the α and β subunits of integrins, we show here the presence of some of these proteins in human and hamster oocytes. Among them, α2 and α5 were also present onin vitropreparations of sea urchin egg cortices. In addition, antibodies raised against these two proteins were the most effective at inhibiting attachment and fusion of human spermatozoa with hamster oocytes. We suggest that α2 and α5 integrin chains may be common mediators in adhesion-fusion mechanisms triggered by fertilisation. Using similar techniques, we show that eggs are rich three cytoskeletal proteins known to be linked to the β chain of integrins: talin, vinculin and α-actinin. Moreover, we found that talin and α-actinin were associated with proteins phosphorylated on tyrosine after fertilisation in sea urchin eggs. We suggest that integrins might be involved during fertilisation and trigger egg activation through cytoskeletal structures.