A NOVEL REGULATORY ELEMENT OF A NICOTINIC ACETYLCHOLINE-RECEPTOR GENEINTERACTS WITH A DNA-BINDING ACTIVITY ENRICHED IN RAT-BRAIN

Nicotinic acetylcholine receptors are ligand-gated ion channels that p lay a critical role in signal transmission in the nervous system. The genes encoding the Various subunits that comprise functional acetylcho line receptors are expressed in distinct temporal and spatial patterns . Studies to understand the molecular mechanisms underlying the differ ential expression of the receptor subunit genes have led to the identi fication, in this report, of a 19-base pair cis-acting element that is required for transcriptional activation of the rat beta 4 subunit gen e. Screening of computer data bases with the 19-base pair element reve aled the sequence to be unique among known transcriptional regulatory elements. Loss of this element resulted in drastically reduced beta 4 promoter activity in transfected cholinergic SN17 cells. Furthermore, this element specifically interacts with nuclear proteins prepared fro m both SN17 cells and adult rat brain. UV cross-linking experiments in dicated the presence, in SN17 nuclear extracts, of a prominent protein species (approximately 50 kDa) that interacts specifically with the I s-base pair element. These results lead us to hypothesize that interac tions between the 50-kDa protein and the novel 19-base pair element ar e necessary for transcriptional activation of the beta 4 subunit gene.