MURINE NIMA-RELATED KINASES ARE EXPRESSED IN PATTERNS SUGGESTING DISTINCT FUNCTIONS IN GAMETOGENESIS AND A ROLE IN THE NERVOUS-SYSTEM

NIMA protein kinase is a major regulator of progression into mitosis i n Aspergillus nidulans. Dominant negative forms of NIMA protein preven t entrance into mitosis in HeLa cells, suggesting that mammals have a similar pathway, We have reported previously the isolation of a murine NIMA-related kinase, designated Nek1, and more recently several addit ional NIMA-related human kinases have been cloned. The existence of se veral mammalian NIMA-related genes raises the questions of whether the different mammalian members have redundant, overlapping or distinct f unctions, and whether these functions are related to the role of NIMA in controlling mitosis. To address these questions we have studied the expression patterns of the different murine nek genes. To this end, w e isolated a murine nek2 cDNA and compared its patterns of expression, during both gametogenesis and embryogenesis, to those of nek1. Both g enes were highly expressed in developing germ cells, albeit in distinc t patterns. In both females and males, nek1 is expressed much earlier than nek2, suggesting only limited ability for functional redundancy. Surprisingly, a striking specificity of nek1 expression was found: hig h levels of nek1 RNA were observed in distinct regions of the nervous system, most notably in neurons of the peripheral ganglia, These patte rns suggest that the different mammalian NIMA-related kinases particip ate in different phases of the meiotic process and may also have funct ions other than cell cycle control.