The expression and stage-specific localization of protein kinase C isotypes during mouse preimplantation development

Signaling events mediate many processes that act during embryogenesis to in itiate the program of early development. within the cell many of these chan ges are mediated through the activation or inactivation of kinases and phos phatases. Protein kinase C (PKC) is one kinase that has been shown to be in volved in at least two developmental transitions during early development, fertilization and embryonic compaction. PKC is a family of kinases whose va rious isotypes have differing requirements for activation of the kinase tha t include the availability of calcium, diacylglycerol, and negatively charg ed phospholipids. The presence of more than one isotype in an egg or blasto mere of the embryo would provide the possibility that different isotypes me diate distinct signaling pathways in the cells. To address this possibility the different isotypes of PKC were examined at the mRNA and protein levels during preimplantation development in the mouse. Our results demonstrate t hat seven isotypes of PKC are present during preimplantation development in mouse, some are of maternal origin and others appear after fertilization. Two isotypes have a stage-dependent nuclear localization. In addition, with in each blastomere PKC isotypes occupy different subcellular locations in a stage-dependent fashion. (C) 2000 Academic Press.