Interactions between regulatory proteins that bind to the nicotinic receptor beta 4 subunit gene promoter

The genes encoding the alpha 3, alpha 5 and beta 4 subunits of nicotinic ac etylcholine receptors are tightly clustered within the genome. As these thr ee subunits constitute the predominant acetylcholine receptor subtype expre ssed in the peripheral nervous system, their genomic proximity suggests a r egulatory mechanism ensuring their coordinate expression. We previously ide ntified two transcriptional regulatory elements within the beta 4 promoter. One of these elements, a CT box, interacts with the regulatory factors het erogeneous nuclear ribonucleoprotein K and Pur alpha. Another element, a CA box, interacts with Sp1 and Sp3. The binding site for a fifth factor, Sox1 0, overlaps the CT and CA boxes. As the CT and CA. boxes are adjacent, we p ostulated that the proteins that bind to the elements interact. Here we rep ort that the CT box-binding factors interact with each other as do the CA b ox-binding factors. However, there are no direct associations between the t wo pairs of proteins. Interestingly though, Sox10 directly interacts with a ll four proteins, suggesting a central role in beta 4 gene expression for t his member of the Sox family of regulatory factors. (C) 2000 Published by E lsevier Science B.V. All rights reserved.