Localization of PKN mRNA in the rat brain

Distribution of mRNA encoding PKN, a fatty acid and RhoA-activated serine/threonine protein kinase with a catalytic domain highly homologous to that of protein kinase C, was investigated in the rat brain using in situ hybridization histochemistry. PKN mRNA proved to be heterogenously distributed. The highest signals were observed in the cerebellum, in limbic systems such as olfactory bulb, hippocampal formation and limbic cortex, and in regions involved in central autonomic and neuroendocrine functions, such as hypothalamic ventromedial, dorsomedial, lateroanterior and arcuate nuclei, paraventricular hypothalamic nucleus and locus coeruleus. PKN mRNA was also highly expressed in dopaminergic neurons such as the ventral tegmental area and substantia nigra pars compacta, in serotonergic raphe neurons, and in cholinergic neurons such as nucleus diagonal band, nucleus basalis, and lateral dorsal tegmental nucleus. The distribution of PKN mRNA differed from that for PKC isoforms. As the localization of PKN mRNA is heterogeneous, PKN may have a specific role in distinct populations of nerve cells.