Involvement of histone acetylation in the regulation of choline acetyltransferase gene in NG108-15 neuronal cells

Post-translational modification of histone such as acetylation of N-terminal of lysine residues influences gene expression by modulating the accessibility of specific transcription factors to the promoter region, and is essential for a wide variety of cellular processes in the development of individual tissues, including the brain. However, few details concerning the acquisition of specific neurotransmitter phenotype have been obtained. In the present study, we investigated the possible involvement of histone acetylation in the gene expression of choline acetyltransferase (ChAT), a specific marker for cholinergic neuron and its function, in NG108-15 neuronal cells as an in vitro model of cholinergic neuron. Treatment with the histone deacetylase (HDAC) inhibitor trichostatin A (TSA), which induces global histone hyper-acetylation of the cells, resulted in marked increase in the expression of ChAT gene in proliferating NG108-15 cells. Furthermore, RT-PCR analysis using primer pairs for individual variants of ChAT mRNA (R1-4, N1, and M type) revealed that M type, not R1-4 and N1 type, ChAT mRNA were mainly transcribed, and chromatin immunoprecipitation assay indicated that the promoter region of M type ChAT gene was highly acetylated, in the dibutyryl cyclic AMP-induced neuronal differentiation of NG108-15 cells. The present findings demonstrate that the acquisition of neurotransmitter phenotype is epigenetically, at least the hyper-acetylation on the core promoter region of ChAT gene, regulated in NG108-15 neuronal cells.