IN-SITU HYBRIDIZATION ANALYSIS OF ZPK GENE-EXPRESSION DURING MURINE EMBRYOGENESIS

ZPK is a recently described protein serine/threonine kinase that has b een originally identified from a human teratocarcinoma cell line by th e polymerase chain reaction and whose function in signal transduction has not yet been elucidated. To investigate the potential role of this protein kinase in developmental processes, we have analyzed the spati al and temporal patterns of expression of the ZPK gene in mouse embryo s of different gestational ages. Northern blot analysis revealed a sin gle mRNA species of about 3.5 KB from Day 11 of gestation onwards. In situ hybridization studies demonstrated strong expression of ZPK mRNA in brain and in a variety of embryonic organs that rely on epitheliome senchymal interactions for their development, including skin, intestin e, pancreas, and kidney. In these tissues, the ZPK mRNA was localized primarily in areas composed of specific types of differentiating cells , and this expression appeared to be upregulated at a time concomitant with the onset of terminal differentiation. Taken together, these obs ervations raise the possibility that the ZPK gene product is involved in the establishment and/or maintenance of a fully cytodifferentiated state in a variety of cell lineages.