title: Rescue of p53 blockage by the A(2A) adenosine receptor via a novel interacting protein, translin-associated protein X.
abstract: Blockage of the p53 tumor suppressor has been found to impair nerve growth factor (NGF)-induced neurite outgrowth in PC-12 cells. We report herein that such impairment could be rescued by stimulation of the A(2A) adenosine receptor (A(2A)-R), a G protein-coupled receptor implicated in neuronal plasticity. The A(2A)-R-mediated rescue occurred in the presence of protein kinase C (PKC) inhibitors or protein kinase A (PKA) inhibitors and in a PKA-deficient PC-12 variant. Thus, neither PKA nor PKC was involved. In contrast, expression of a truncated A(2A)-R mutant harboring the seventh transmembrane domain and its C terminus reduced the rescue effect of A(2A)-R. Using the cytoplasmic tail of the A(2A)-R as bait, a novel-A(2A)-R-interacting protein [translin-associated protein X (TRAX)] was identified in a yeast two-hybrid screen. The authenticity of this interaction was verified by pull-down experiments, coimmunoprecipitation, and colocalization of these two molecules in the brain. It is noteworthy that reduction of TRAX using an antisense construct suppressed the rescue effect of A(2A)-R, whereas overexpression of TRAX alone caused the same rescue effect as did A(2A)-R activation. Results of [(3)H]thymidine and bromodeoxyuridine incorporation suggested that A(2A)-R stimulation inhibited cell proliferation in a TRAX-dependent manner. Because the antimitotic activity is crucial for NGF function, the A(2A)-R might exert its rescue effect through a TRAX-mediated antiproliferative signal. This antimitotic activity of the A(2A)-R also enables a mitogenic factor (epidermal growth factor) to induce neurite outgrowth. We demonstrate that the A(2A)-R modulates the differentiation ability of trophic factors through a novel interacting protein, TRAX.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan.
authors.forename: Chung-Nan
authors.initials: CN
authors.lastname: Sun
authors.forename: Hsiao-Chun
authors.initials: HC
authors.lastname: Cheng
authors.forename: Jui-Ling
authors.initials: JL
authors.lastname: Chou
authors.forename: Shen-Yang
authors.initials: SY
authors.lastname: Lee
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: Lin
authors.forename: Hsing-Lin
authors.initials: HL
authors.lastname: Lai
authors.forename: Hui-Mei
authors.initials: HM
authors.lastname: Chen
authors.forename: Yijuang
authors.initials: Y
authors.lastname: Chern
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D004247:DNA / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000502:physiology*; D020932:Nerve Growth Factor / Q000494:pharmacology; D016716:PC12 Cells; D011493:Protein Kinase C / Q000502:physiology; D051381:Rats; D043705:Receptor, Adenosine A2A / Q000737:chemistry / Q000502:physiology*; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors*
chemical_list: D004268:DNA-Binding Proteins; D043705:Receptor, Adenosine A2A; C498307:Tsnax protein, rat; D016159:Tumor Suppressor Protein p53; D004247:DNA; D020932:Nerve Growth Factor; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C