Effect of genistein on the temporal coordination of cleavage and compaction in mouse preimplantation embryos

Initially, we investigated the effect of genistein, an inhibitor of protein tyrosine kinases, on compaction of the mouse embryo since tyrosine phosphorylation of the cadherin-catenins complex was suggested to down-regulate its adhesive function. Genistein prevented cleavage from the 2- to the 4-cell stage in a concentration-dependent manner. The next cleavage is inhibited at all concentrations used. Time course of intercellular flattening is however identical for both control 8-cell embryos and 4-cell arrested embryos. This confirms that compaction takes place according to a biological clock that does not depend on completion of the third cell cycle. Our results also suggest that, since, in contrast to genistein, protein kinases C modulators are known to cause a premature compaction, diacylglycerol-dependent kinases but not protein tyrosine kinases might be upregulators of compaction.