NEURONAL LOCALIZATION IN THE RAT-BRAIN OF THE MESSENGER-RNA ENCODING CALCYPHOSINE, A NEW CALCIUM-BINDING PROTEIN

The CDNA encoding calcyphosine, a new calcium-binding protein of the c almodulin superfamily which is regulated by cAMP, has been cloned in t he dog thyroid (EMBO J., 8 (1989) 111-116). By in situ hybridization w ith synthetic oligonucleotides, we here demonstrate for the first time its neuronal localization in the rat brain. Hybridization signal was detected in all the olfactory areas; in pyramidal and non pyramidal-sh aped neurons in the different layers of the cerebral cortex, especiall y the superficial ones; in the pyramidal cells of the different sector s of the Ammon's horn and in the granule cells of the dentate gyrus of the hippocampus; in the subiculum; in the medium-sized and large neur ons of the different quadrants of the caudate-putamen and accumbens an d in the cerebellar Purkinje cells. Hybridization was also observed to a lesser extent in the majority of the neurons in the basal areas of the forebrain, including septum, nucleus of the diagonal band and amyg dala; in the globus pallidus, entopeduncular nucleus, substantia nigra pars reticulata and compacta, ventral tegmental area; in the subthala mic nucleus; in the thalamus; in the hypothalamus; in the brainstem an d in the upper cervical spinal cord. In addition to its neuronal local ization, calcyphosine mRNA was also found in ependymal cells. The non- detection of positive cells in the white matter was not in favor of pr ominent glial localization, although it does not exclude it.