AP-2β represses D1A dopamine receptor gene transcription in Neuro2a cells
Abstract Expression of the D 1A dopamine receptor in brain is restricted to specific neuronal populations. To investigate the mechanism of this selective expression, we localized a silencer upstream of the human D 1A gene and identified its binding transcription factor in the D 1A -negative neural cell line Neuro2a. Using deletion CAT analysis, we narrowed this silencer to the region between nucleotides −561 and −532 relative to the CAP site. This 30-bp region, 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 sequence. In gel supershift assays, this factor is recognized by anti-AP-2β antibody. Co-transfection of Neuro2a cells with an AP-2β expression vector repressed the basal CAT activity of D 1A promoter–reporter plasmids in a D1AS1-dependent manner. RT-PCR analysis indicated that, among AP-2 family members, Neuro2a cells express only AP-2β. Furthermore, co-transfection of these cells with decoy oligonucleotides corresponding to the D1AS1 sequence de-repressed the D 1A gene promoter. Unlike in Neuro2a cells, AP-2β could not repress the D 1A promoter in the D 1A -positive neural cell line, NS20Y. In addition, the expression of AP-2β in different brain regions does not inversely correlate with that of D 1A dopamine receptor. These observations taken together indicate that AP-2β is a repressive transcription factor that acts on the D1AS1 silencer of the D 1A dopamine receptor gene via some cell-specific mechanism(s) in Neuro2a.