Developmental changes in distribution of death-associated protein kinase mRNAs

Death-associated protein kinase (DAP-kinase) is Ca2+/calmodulin-dependent s erine/threonine kinase that contains ankyrin repeats and the death domain. It has been isolated as a positive mediator of interferon-gamma-induced apo ptotic cell death of HeLa cells. In order to reveal the physiological role of DAP-kinase, the tissue distribution and developmental changes in mRNA ex pression of DAP-kinase were investigated by Northern blot and in situ hybri dization analyses, DAP-kinase mRNA was predominantly expressed in brain and lung, In brain, DAP-kinase mRNA had already appeared at embryonic day 13 ( E13) and was, thereafter, detected throughout the entire embryonic period. High levels of expression were detected in proliferative and postmitotic re gions within cerebral cortex, hippocampus, and cerebellar Purkinje cells. T hese findings suggest that DAP-kinase may play an important role in neuroge nesis where a physiological type of cell death takes place. The overall exp ression of DAP-kinase mRNA in the brain gradually declined at postnatal sta ges, and the expression became restricted to hippocampus, in which differen t expression patterns were observed among rostral, central, and caudal coro nal sections, suggesting that DAP-kinase may be implicated in some neuronal functions. Furthermore, it was found that the expression of DAP-kinase mRN A was increased prior to a certain cell death induced by transient forebrai n ischemia, indicating a possible relationship between DAP-kinase and neuro nal cell death. (C) 1999 Wiley-Liss, Inc.