AP-2 beta represses D-1A dopamine receptor gene transcription in Neuro2a cells

Expression of the D-1A dopamine receptor in brain is restricted to specific neuronal populations. To investigate the mechanism of this selective expre ssion, we localized a silencer upstream of the human D-1A gene and identifi ed its binding transcription factor in the D-1A-negative neural cell line N euro2a. Using deletion CAT analysis, we narrowed this silencer to the regio n between nucleotides -561 and -532 relative to the CAP site. This 30-bp re gion, designated D1AS1, contains a sequence homologous to the AP-2 binding site and binds to a factor that also interacts with the AP-2 consensus sequ ence. In gel supershift assays, this factor is recognized by anti-AP-2 beta antibody. Co-transfection of Neuro2a cells with an AP-2 beta expression ve ctor repressed the basal CAT activity of D-1A promoter-reporter plasmids in a D1AS1-dependent manner. RT-PCR analysis indicated that, among AP-2 famil y members, Neuro2a cells express only AP-2 beta. Furthermore, co-transfecti on of these cells with decoy oligonucleotides corresponding to the D1AS1 se quence de-repressed the D-1A gene promoter. Unlike in Neuro2a cells, AP-2 b eta could not repress the D-1A promoter in the D-1A-positive neural cell li ne, NS20Y. in addition, the expression of AP-2 beta in different brain regi ons does not inversely correlate with that of D-1A dopamine receptor. These observations taken together indicate that AP-2 beta is a repressive transc ription factor that acts on the D1AS1 silencer of the D-1A dopamine recepto r gene via some cell-specific mechanism(s) in Neuro2a. (C) 1999 Elsevier Sc ience B.V. All rights reserved.