Ž . European Journal of Pharmacology 393 2000 69–74 www.elsevier.nlrlocaterejphar Transcriptional control of the neuronal nicotinic acetylcholine receptor gene cluster by the b 43 X enhancer, Sp1, SCIP and ETS transcription factors Evan S. Deneris ) , Nicole Francis, Jenny McDonough, Dmitry Fyodorov, Tim Miller, Xiangdong Yang Case Western ReserÕe UniÕersity, School of Medicine, Department of Neurosciences, 2109 Adelbert Rd. CleÕeland OH, 44106-4975, USA Accepted 21 January 2000 Abstract Receptors assembled from the products of a neuronal b4 a 3a 5 NAChR gene cluster depend on these genes being coordinately regulated in particular populations of neurons. Little is known, however, about the transcriptional mechanisms that are likely to underlie their co-expression in correct neuronal cell types. We have identified several regulatory elements and transcription factors that influence transcription of the a 3 and b4 genes. The promoters of these genes appear to contain a common cis element that binds Sp1 transcription factors. They can be activated by the POU-domain factor SCIP and activation does not require SCIP binding sites. Between these two promoters is a cell type specific enhancer called b43 X . This enhancer has little activity in non-neuronal cells and is preferentially active in particular populations of central neurons. The clustered genes are potential targets of ETS factors as the ETS domain factor, Pet-1 can activate b43 X -dependent transcription. The neuron-selective properties of b43 X and its location suggest that it is a component of the cis regulatory information required to control expression of the b4 and a 3 genes in specific populations of neurons. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Nicotinic receptor; Transcription; Enhancer; Promoter; Neuron 1. Introduction The vertebrate genome provides a tremendous potential for generating nicotinic acetylcholine receptor diversity by encoding at least sixteen different subunits that can be used to assemble receptors. An important question cur- rently under investigation is what are the transcriptional mechanisms that control the distribution of subunit mRNA within various populations of vertebrate neurons? As most nicotinic receptor subtypes expressed in neurons are het- eromeric assemblies of two, three, or even four different subunits, the genes encoding them must be coordinately regulated to allow the co-expression of appropriate subunit mRNA in the correct neuronal cell types. Thus, as the protein-coding regions of the neuronal nicotinic receptor ) Corresponding author. Tel.: q 1-216-368-8725; fax: q 1-216-368- 4650. Ž . E-mail address: esd@po.cwru.edu E.S. Deneris . subunit genes diversified over time, the genetic regulatory information required to restrict and coordinate neuronal co-expression of individual subunit mRNAs must have evolved in parallel. Three of the neuronal nicotinic receptor subunit genes are clustered in the order b 4, a 3, and a 5 over about 50 Ž kb in the vertebrate genome Boulter et al., 1990; Cou- . turier et al., 1990; Raimondi et al., 1992 . Clustering of the b 4, a 3, and a 5 genes suggests that this organization has been evolutionarily conserved in order to preserve regula- tory information needed to control cell-type specific tran- scription of these genes. It is straightforward to imagine what might be the functional significance of this organiza- tion as the b 4, a 3, and a 5 subunits are assembled to- gether into at least one major ganglionic nicotinic receptor Ž . subtype Conroy and Berg, 1995; Vernallis et al., 1993 . b 4 and a 3 but not a 5 are also likely to be assembled together into at least one retinal subtype well as other brain Ž . subtypes Vailati et al., 1999; Zoli et al., 1998 . It seems 0014-2999r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S0014-2999 99 00883-3