Asymmetric regulation by estrogen at the cholinergic gene locus in differentiated NG108-15 neuronal cells

Abstract

Aims Estrogen acts as a neurogenerative and neuroprotective factor in the cholinergic system. Choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) are regarded as markers of cholinergic neurons. The genes coding these proteins are located at a common locus, the cholinergic gene locus. However, few details concerning activation of the locus have been obtained. We examined the effect of estrogen on the activation pattern of the locus using a cholinergic cell line. Main methods NG108-15 neuronal cells, as a model of cholinergic neurons, were used. Dose-dependent effects of estradiol (E 2) on the gene expression of ChAT and VAChT were quantitatively determined by a real-time RT-PCR. The expression of ChAT mRNA variants was qualitatively evaluated by RT-PCR using specific primers. Key findings The expression of ChAT and VAChT mRNA was strongly enhanced with the induction of differentiation. The enhanced expression of ChAT mRNA was further increased dose-dependently by E 2 (10 − 10 to 10 − 7 M), while that of VAChT mRNA did not respond to E 2. The up-regulation of ChAT mRNA expression by E 2 was abolished by co-treatment with a pure-antagonist of estrogen receptors. A qualitative analysis of ChAT mRNA variants revealed the R types, which share a common sequence with the VAChT gene, and type M ChAT mRNA to mainly be expressed, and that the appearance of these variants was not altered by E 2. Significance The cholinergic gene locus in differentiated NG108-15 neuronal cells is further activated by E 2, but the effect is restricted to the transcription of ChAT gene.