TRANSCRIPTIONAL REGULATION OF NEURONAL NICOTINIC ACETYLCHOLINE-RECEPTOR GENES - FUNCTIONAL INTERACTIONS BETWEEN SP1 AND THE RAT BETA-4 SUBUNIT GENE PROMOTER

To date, 11 members (alpha 2-alpha 9 and beta 2-beta 4) of the neurona l nicotinic acetylcholine receptor gene family have been identified. T hese genes encode subunits that form distinct receptors with different pharmacological and physiological profiles in temporally and spatiall y restricted patterns within the nervous system, Distinct molecular me chanisms probably orchestrate the expression of various receptor subty pes, yet little is known of specific transcriptional regulatory elemen ts and their associated factors that are responsible for this segregat ed pattern of expression, Here we report the identification of an elem ent, in the 5'-flanking region of the rat beta 4 subunit gene, contain ing a CA box that is necessary for beta 4 promoter activity in a trans iently transfected cholinergic cell line, SN17. This element was shown to interact with a protein(s) in SN17 nuclear extracts that is antige nically related to the transcriptional activator Sp1. Furthermore, co- transfection experiments confirmed that Sp1 can transactivate a beta 4 promoter-reporter gene construct, indicating that Sp1 is necessary, a t least in part, for transcriptional activation of the beta 4 subunit gene.