Developmental changes in expression and self-editing of adenosine deaminase type 2 pre-mRNA and mRNA in rat brain and cultured cortical neurons.

Adenosine deaminase-1 and -2 (ADAR-1 and -2) are double-stranded RNA-specific enzymes involved in the editing of genes including serotonin 2C receptor (5-HT2CR) mRNA and ADAR-2 pre-mRNA. We reported that the editing efficacy of 5-HT2CR mRNA altered during brain development in rats. The present study aimed to clarify if changes in the expression of ADAR genes and the editing of ADAR-2 pre-mRNA occur during development. The expression level of ADAR-1 mRNA was constant during development, whereas the expression levels of ADAR-2 mRNA and ADAR-2 pre-mRNA markedly increased during development. ADAR-2 pre-mRNA possesses six editing sites. Editing of these sites did not occur during the embryonic period; however, the number of edited sites and the editing frequency at these sites increased after birth and cultivation period. These results suggest that the increases in ADAR-2 pre-mRNA editing and mRNA expression of the enzyme may play a role in development. We also discuss the relationship between 5-HT2CR mRNA editing and the expression/RNA editing of ADAR-1 and ADAR-2 mRNA.