Synergistic transcriptional activation by Sox10 and Sp1 family members

Neuronal nicotinic acetylcholine receptors (nAChR) are expressed at specifi c times during development and in discrete neuronal populations. Transcript ional regulation of the receptor genes clearly plays a key role in the mole cular pathway underlying the expression of these critical synaptic componen ts. In an effort to understand this regulation, we focus upon the genes enc oding three receptor subunits: alpha3, alpha5 and beta4. These subunits are genomically clustered and constitute the predominant nAChR subtype express ed in the peripheral nervous system. We and others demonstrated that the ge neral transcription factors, Sp1 and Sp3, can transactivate the promoter of each subunit gene. Further, we showed that the regulatory factor Sox10 tra nsactivates the alpha3 and beta4 promoters and does so in a cell-type-speci fic manner. Interestingly, the Sp- and Sox10-binding sites on the beta4 pro moter are located immediately adjacent to each other, raising the possibili ty that the two sets of factors functionally interact to regulate receptor gene expression. Consistent with this hypothesis, we demonstrated that the proteins can directly interact. Here, we extend these observations and show that Sox10 and the Sp factors functionally interact, leading to synergisti c transcriptional activation in a cholinergic cell Line. Finally, evidence for the existence of cell-type-specific co-regulators for Sp1 and Sox10 is presented. (C) 2000 Elsevier Science Ltd. All rights reserved.