For studying the effect of
integrin on the [Ca(2+)](i) of mouse eggs and its transmembrane signaling mechanism,
zona-free mouse eggs were loaded with
calcium probe
Fluo-3/AM and the intensity of fluorescence of the eggs treated with different factors was measured through
laser confocal microscopy. The results showed that the [Ca(2+)](i) of
zona-free mouse eggs was increased when the eggs were treated with
RGD peptide,
fibronectin (Fn) and anti-mouse
integrin subunit alpha(6) and beta(1)
monoclonal antibodies, respectively. The [Ca(2+)](i) of the mouse eggs was also increased when the eggs were placed in
calcium-free medium and treated with
RGD peptide or Fn. The changes in the mouse egg [Ca(2+)](i) caused by RGD and Fn were similar to those caused by sperm. However, the concentration of Ca(2+) of the
zona-free mouse eggs pretreated with
tyrosine kinase inhibitor was not increased when the eggs were treated in the same way, and, neither was the intracellular
calcium increased in those eggs pretreated with PKC inhibitor when the eggs were treated with
RGD peptide. It is therefore suggested that the occupancy of
integrins on the membrane of mouse eggs by their
ligands mediates the release of Ca(2+) and then the increase in the [Ca(2+)](i) of eggs, which is one of the early events of egg activation. The
tyrosine kinase signaling pathway and PKC are involved in this process as well.