Role of oocyte integrins in fertilization-induced signal transduction in Bufo arenarum

MOUGUELAR, V. S.; CABADA, M. O.; COUX, G

San Miguel de Tucumán- Tucumán

Congreso; XLV Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Celular; 2009

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

We previously demonstrated the presence of the integrin b1 subunit in the plasma membrane of B. arenarum oocytes and provided evidence for a role of integrins in fertilization. Our aims now were to: a) determine the a subunits that form, together with the b1 subunit, the integrin heterodimer, and b) study the involvement of integrin b1 subunit in the signaling cascade triggered in fertilization. We performed immunoprecipitation with an anti-b1 integrin antibody in plasma membrane samples from crosslinked oocytes. We evaluated the presence of integrin subunits a5 and a6 among the co-immunoprecipitating proteins. We found that both a5b1 and a6b1 heterodimers are present in B.arenarum oocytes. We also analyzed the phosphorylation state of the proteins that co-immunoprecipitated with the integrin b1 subunit before and after fertilization. We found that different proteins, some of them phosphorylated in serine/threonine and others in tyrosine, not only co-immunoprecipitate with this subunit but also change their phosphorylation state due to fertilization. None of the detected bands had the molecular ratio of integrins. In conclusion, our results suggest that an integrin formed by the b1 subunit (probably as a5b1 and/or a6b1 integrin heterodimer) is involved in the fertilization-induced signal transduction, even when this protein does not change its phosphorylation state during this process.