CELL-SPECIFIC EXPRESSION OF THE ZPK GENE IN ADULT-MOUSE TISSUES

ZPK is a recently identified human putative protein kinase gene that e ncodes an unusual serine/threonine kinase containing two potential leu cine zipper motifs similar to those found in transcription factors as well as in members of the newly discovered mixed-lineage family of pro tein kinases, To study the normal biological function of ZPK, me have isolated a mouse ZPK cDNA and examined the pattern of ZPK mRNA express ion in adult mouse tissues by Northern blot and in situ hybridization analyses, The predicted open reading frame of this cDNA encodes an 888 -amino-acid protein that shares 95% overall identity with its human co unterpart, By Northern blot analysis, we detected expression of ZPK mR NA in the brain of adult mice, but not in any other tissue tested, In situ hybridization analysis of mouse brain sections revealed specific association of ZPK mRNA with neuronal cell populations, primarily in t he hippocampus, the cerebral cortex, and the Purkinje cell layer of th e cerebellum, Interestingly, a remarkable pattern of cell-type-specifi c expression was also found in the epithelial compartment of various o rgan systems, including stomach, small intestine, liver, and pancreas, as well as in the seminiferous tubules of mature testes, Taken togeth er, these observations suggest that ZPK could play a role in developme nt, function, and maintenance of a variety of specialized cells.