Submitted on March 22, 2005
Accepted on July 15, 2005
Genetic and Pharmacological Inactivation of Adenosine A2A Receptor Reveals an Egr-2 Mediated Transcriptional Regulatory Network in the Mouse Striatum
Liqun Yu1, Peter M Haverty2, Juliana Mariani1, Yumei Wang1, Hai-Ying Shen1, Michael A Schwarzschild3, Zhiping Weng4, and Jiang-Fan Chen1*
1 Neurology, Boston University School of Medicine, Boston, MA, USA
2 Bioinformatics Program, Boston University, Boston, MA, USA
3 Neurology, Massachusetts General Hospital & Harvard Medical School, Charlestown, MA, USA
4 Bioinformatics Program, Boston University, Boston, MA, USA; Biomedical Engineering, Boston University School of Engineering, Boston, MA, USA
* To whom correspondence should be addressed. E-mail: chenjf{at}bu.edu.
The Adenosine A2A receptor (A2AR) 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 A2AR and inferred an A2AR-controlled transcription network in the mouse striatum. A comparison between A2AR knockout (KO)-Vehicle (VEH) and wild-type (WT)-VEH revealed 36 up-regulated genes that were partially mimicked by treatment of SCH58261 (an A2AR antagonist), and 54 down-regulated genes that were not mimicked by SCH58261 treatment. We validated A2AR as a specific drug target for SCH58261 by comparing A2AR KO-SCH and A2AR KO-VEH groups. The unique down-regulation effect of A2AR KO was confirmed by comparing A2AR-KO-SCH with WT-SCH gene groups. The distinct striatal gene expression profiles induced by A2AR KO and SCH58261 should provide clues to the molecular mechanisms underlying the different phenotypes observed after genetic and pharmacological inactivation of A2AR. Bioinformatics analysis discovered that the Egr-2 binding sites were statistically over-represented in the proximal promoters of A2AR-KO-affected genes relative to the unaffected genes. This finding was further substantiated by the demonstration that Egr-2 mRNA level increased in the striatum of both A2AR-KO and SCH58261-treated mice and that striatal Egr-2 binding activity in the promoters of two A2AR-KO-affected genes was enhanced in A2AR 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 A2AR.
