Localization of an endoplasmic reticulum calcium ATPase mRNA in rat brain by in situ hybridization.

SERCA-2 is an endoplasmic reticulum Ca2+ ATPase present in brain [Gunteski-Hamblin A.-M. et al. (1988) J. biol. Chem. 263, 15032-15040]. We sought to map the distribution of this pump in the rat brain and investigate its relationship to Ca2+ uptake by brain endoplasmic reticulum. Using in situ hybridization and Northern blots with antisense oligonucleotide probes, we found that SERCA-2 is concentrated most densely in the cerebellum, especially in Purkinje cells, and in the hippocampus, with heavy labeling also in cortex, thalamus, pontine nuclei and the mitral cell layer of the olfactory bulb. 45Ca2+ uptake displayed a similar pattern with heaviest accumulation in cerebellum, hippocampus, cortex, thalamus and olfactory bulb. In corpus striatum and substantia nigra, relative 45Ca2+ accumulation was greater than SERCA-2 mRNA. Thus, SERCA-2 appears to be involved in Ca2+ uptake into endoplasmic reticulum in brain for release by inositol 1,4,5-trisphosphate and other agents.