Molecular cloning and developmental expression of a rat homologue of death-associated protein kinase in the nervous system

Death-associated protein kinase (DAP kinase) has been recently identified as a novel Ca2+/calmodulin-dependent protein kinase and as a potential mediator of gamma interferon-induced cell death of Hela cells, which has cytological characteristics of the programmed cell death. In order to elucidate its functional roles in the rat brain where the programmed cell death is an essential mechanism in the organization of postmitotic neurons during development, we cloned a rat homologue of the human DAP kinase from the rat embryonic brain cDNA library. The deduced amino acid sequence was highly conserved between the two species (93.6%). By in situ hybridization histochemistry, the expression of DAP kinase mRNA was observed in the mantle and ventricular zones of the entire neuraxis on embryonic day 15. However, the overall expression in the brain decreased markedly after birth and the expression was maintained at substantial levels in several restricted mature neuronal populations, such as olfactory bulb, hippocampal formation and cerebellar Purkinje and granule cells. Its wide expression during development and its maintained expression in the restricted mature neuronal population suggest that DAP kinase might be involved in some neuronal functions beyond simply executing the developmental neuronal cell death. (C) 1997 Elsevier Science B.V.