Expression of pS2 gene in rat brain.

We have previously shown that the expression of pS2 mRNA, which encodes a secreted 60-amino acid protein of unknown function, is widely distributed throughout the entire body of the mouse including the brain. We report herein that pS2 mRNA is also expressed in the brain and in peripheral tissues of rats. In adult rat brain, pS2 mRNA was predominantly expressed in hippocampus, followed by the cerebral cortex and cerebellum. The developmental expression of pS2 mRNA in hippocampus, which region is known to mature after birth, showed a clear peak in 1- or 3-day-old rats, then gradually decreased by 7 weeks after birth. In midbrain, the maturation of which occurs at an early developmental stage, pS2 mRNA level was retained at a low level from postnatal 1 day to week 7. These results suggest that pS2 protein plays an important role in the development of central nervous system.