Localization of mRNA for protein phosphatase 2C in the brain of adult rats.

Type 2C protein phosphatase (PP2C) is one of four major serine-threonine specific phosphoprotein phosphatases which modulate various intracellular activities. By in situ hybridization analysis of the adult rat, expression signals of mRNA for PP2C were observed most highly in the granule cells and Purkinje cells of the cerebellum, the pyramidal cells of the hippocampus and granule cells of the dentate gyrus, and plexus choroideus of the lateral ventricle, whereas moderate levels of its expression were observed in the medial habenula, piriform cortex and the pineal body. Several discrete nuclei of the brainstem including pars compacta of the substantia nigra, the pontine nuclei, and the locus ceruleus expressed the mRNA moderately. Weak expression of PP2C mRNA was observed in mitral and internal granule cells of the olfactory bulb, spinal cord gray matter, the cerebral neocortex, thalamic and hypothalamic nuclei. Only faint expression was detected in the caudate putamen. These patterns of expression are different from that of calcineurin/PP2B reported by other immunohistochemical studies and it is suggested that various neuronal proteins are differentially dephosphorylated by the different types of PP.