Elements between the protein-coding regions of the adjacent beta 4 and alpha 3 acetylcholine receptor genes direct neuron-specific expression in the central nervous system.
The expression patterns of three clustered neuronal nicotinic acetylcholine receptor (nAchR) subunit genes ordered beta 4, alpha 3, and alpha 5 overlap extensively in the peripheral nervous system (PNS) but only partially in the central nervous system (CNS). We have begun to investigate cell type-specific cis elements regulating these genes by analyzing in both cell culture and transgenic mice, a 2.8-kb fragment (-2732/+47) containing the alpha 3 promoter region, the beta 4/alpha 3 intergenic region, and a portion of the beta 4 3'-untranslated exon. The -2732/+47 fragment is preferentially active in PC12 cells relative to nonneural cell lines. Deletion analysis revealed a cell type-specific positive transcriptional element positioned in the beta 4 3'-untranslated exon. The positive element is likely to be an enhancer and not a second alpha 3 promoter, because no alpha 3 exons are present in this region. Having shown in cell culture that cell-type specific cis elements are positioned between the beta 4 and alpha 3 coding regions, we investigated the activity of -2732/+47 in vivo. Transgenic mice were generated, which carry the lacZ gene fused downstream of -2732/+47. Expression of the lacZ transgene is restricted to neurons of the CNS; no expression was detected in the PNS or in nonneural tissues. LacZ-positive cells were detected virtually exclusively in a subset of CNS nuclei that transcribe the endogenous alpha 3 gene. Some overlap was seen with the beta 4 gene, but nearly none with the alpha 5 gene. Our results demonstrate that cis elements positioned between the alpha 3 and beta 4 coding regions are important for establishing part of the restricted CNS patterns of beta 4, alpha 3, and alpha 5 gene transcription.
Yang
X
X
Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4975, USA.
Yang
F
F
Fyodorov
D
D
Wang
F
F
McDonough
J
J
Herrup
K
K
Deneris
E
E
D000818:Animals; D002490:Central Nervous System / Q000166:cytology / Q000378:metabolism*; D005091:Exons; D015870:Gene Expression; D005796:Genes; D017930:Genes, Reporter; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000378:metabolism*; D016716:PC12 Cells; D011401:Promoter Regions, Genetic; D051381:Rats; D011978:Receptors, Nicotinic / Q000235:genetics* / Q000378:metabolism*; D019076:Transgenes
D011978:Receptors, Nicotinic