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 situu 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 ofactory 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.