Phosphodiesterase 2A forms a complex with the co-chaperone XAP2 and regulates nuclear translocation of the aryl hydrocarbon receptor.
Phosphodiesterase type 2A (PDE2A) hydrolyzes cyclic nucleotides cAMP and cGMP, thus efficiently controlling cNMP-dependent signaling pathways. PDE2A is composed of an amino-terminal region, two regulatory GAF domains, and a catalytic domain. Cyclic nucleotide hydrolysis is known to be activated by cGMP binding to GAF-B; however, other mechanisms may operate to fine-tune local cyclic nucleotide levels. In a yeast two-hybrid screening we identified XAP2, a crucial component of the aryl hydrocarbon receptor (AhR) complex, as a major PDE2A-interacting protein. We mapped the XAP2 binding site to the GAF-B domain of PDE2A. PDE assays with purified proteins showed that XAP2 binding does not change the enzymatic activity of PDE2A. To analyze whether PDE2A could affect the function of XAP2, we studied nuclear translocation of AhR, i.e. the master transcription factor controlling the expression of multiple detoxification genes. Notably, regulation of AhR target gene expression is initiated by tetrachlorodibenzodioxin (TCDD) binding to AhR and by a poorly understood cAMP-dependent pathway followed by the translocation of AhR from the cytosol into the nucleus. Binding of PDE2A to XAP2 inhibited TCDD- and cAMP-induced nuclear translocation of AhR in Hepa1c1c7 hepatocytes. Furthermore, PDE2A attenuated TCDD-induced transcription in reporter gene assays. We conclude that XAP2 targets PDE2A to the AhR complex, thereby restricting AhR mobility, possibly by a local reduction of cAMP levels. Our results provide first insights into the elusive cAMP-dependent regulation of AhR.
de Oliveira
Simone Kobe
SK
Institute of Biochemistry II, University of Frankfurt Medical School, 60590 Frankfurt, Germany.
Hoffmeister
Meike
M
Gambaryan
Stepan
S
Müller-Esterl
Werner
W
Guimaraes
Jorge A
JA
Smolenski
Albert P
AP
D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D010449:Peptide Mapping; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism*; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D017434:Protein Structure, Tertiary / Q000235:genetics; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism*; D013723:Teratogens / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D020798:Two-Hybrid System Techniques
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; D046912:Multiprotein Complexes; D000072317:Polychlorinated Dibenzodioxins; D011506:Proteins; D018336:Receptors, Aryl Hydrocarbon; D013723:Teratogens; C103265:aryl hydrocarbon receptor-interacting protein; D000242:Cyclic AMP; D010727:Phosphoric Diester Hydrolases; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; C517275:PDE2A protein, human; D006152:Cyclic GMP