Regulation of PNMT gene promoter constructs transfected into the TE 671 human medulloblastoma cell line.

The human medulloblastoma TE 671 cell line has been evaluated as a model for studying expression of transiently transfected phenylethanolamine N-methyltransferase (PNMT) promoter-fusion gene constructs. Because TE 671 cells are one of few continuous lines exhibiting a neuronal phenotype, possess both nicotinic and muscarinic ligand binding properties, and express PNMT mRNA, they represent a likely candidate system for study of cholinergic-regulated PNMT gene expression. When transfected with constructs containing from 0.1 to 3 kb of the region 5' to the initiation site for PNMT gene transcription, TE 671 cells express at detectable levels only those constructs containing the -391 to -863 bp portion of the rat PNMT promoter fused to the chloramphenicol acetyltransferase (CAT) gene. Both general and selective cholinergic agents regulate expression of the -863 to -391 bp PNMT region in a TK promoter-CAT reporter construct. With this construct, carbachol stimulates CAT expression 1.5-fold in transfected TE 671 cells. The selective agonists nicotine and muscarine each stimulate expression of the upstream TK-CAT constructs 2.8- and 1.9-fold respectively, while antagonists for these receptors block induction. Because TE 671 cells respond to both nicotinic and muscarinic stimuli, this continuous line represents a useful model system for studying PNMT gene regulation by cholinergic stimuli.