Genetic and pharmacological inactivation of adenosine A2A receptor reveals an Egr-2-mediated transcriptional regulatory network in the mouse striatum

The adenosine A(2A) receptor (A(2A)R) is highly expressed in the striatum, where it modulates motor and emotional behaviors. We used both microarray and bioinformatics analyses to compare gene expression profiles by genetic and pharmacological inactivation of A(2A)R and inferred an A(2A)R-controlled transcription network in the mouse striatum. A comparison between vehicle (VEH)-treated A(2A)R knockout (KO) mice (A(2A)R KO-VEH) and wild-type (WT) mice (WT-VEH) revealed 36 upregulated genes that were partially mimicked by treatment with SCH-58261 (SCH; an A(2A)R antagonist) and 54 downregulated genes that were not mimicked by SCH treatment. We validated the A(2A)R as a specific drug target for SCH by comparing A(2A)R KO-SCH and A(2A)R KO-VEH groups. The unique downregulation effect of A(2A)R KO was confirmed by comparing A(2A)R KO-SCH with WT-SCH gene groups. The distinct striatal gene expression profiles induced by A(2A)R KO and SCH should provide clues to the molecular mechanisms underlying the different phenotypes observed after genetic and pharmacological inactivation of A(2A)R. Furthermore, bioinformatics analysis discovered that Egr-2 binding sites were statistically overrepresented in the proximal promoters of A(2A)R KO-affected genes relative to the unaffected genes. This finding was further substantiated by the demonstration that the Egr-2 mRNA level increased in the striatum of both A(2A)R KO and SCH-treated mice and that striatal Egr-2 binding activity in the promoters of two A(2A)R KO-affected genes was enhanced in A(2A)R KO mice as assayed by chromatin immunoprecipitation. Taken together, these results strongly support the existence of an Egr-2-directed transcriptional regulatory network controlled by striatal A(2A)Rs.