title: Adenosine attenuates oxidant injury in human proximal tubular cells via A(1) and A(2a) adenosine receptors.
abstract: We have recently demonstrated protection against renal ischemic-reperfusion injury in vivo by A(1)- and A(2a)-adenosine receptor (AR) modulations. To further elucidate the signaling cascades of AR-induced cytoprotection against reperfusion/oxidant-mediated injury, immortalized human proximal tubule (HK-2) cells were treated with H(2)O(2). H(2)O(2) caused dose- and time-dependent HK-2 cell death that was measured by lactate dehydrogenase release and trypan blue dye uptake. Adenosine protected against H(2)O(2)-induced HK-2 cell death by means of A(1)- and A(2a)-AR activation. A(1)-AR-mediated protection involves pertussis toxin-sensitive G proteins and protein kinase C, whereas A(2a)-AR-mediated protection involves protein kinase A activation by means of cAMP and activation of the cAMP response element binding protein. Moreover, protein kinase A activators (forskolin and Sp-isomer cAMP) also protected HK-2 cells against H(2)O(2) injury. De novo gene transcription and protein synthesis are required for both A(1)- and A(2a)-AR-mediated cytoprotection as actinomycin D and cycloheximide, respectively, blocked cytoprotection. Chronic treatments with a nonselective AR agonist abolished the protection by adenosine. Moreover, chronic treatments with a nonselective AR antagonist increased the endogenous tolerance of HK-2 cells against H(2)O(2). We concluded that A(1)- and A(2a)-AR activation protects HK-2 cells against H(2)O(2)-induced injury by means of distinct signaling pathways that require new gene transcription and new protein synthesis.
authors.affiliation: Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York 10032-3784, USA. tl128@columbia.edu
authors.forename: H T
authors.initials: HT
authors.lastname: Lee
authors.forename: Charles W
authors.initials: CW
authors.lastname: Emala
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects*; D002461:Cell Line, Transformed; D004396:Coloring Agents; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000166:cytology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D018384:Oxidative Stress; D011493:Protein Kinase C / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D058915:Purinergic P1 Receptor Antagonists; D043705:Receptor, Adenosine A2A; D018047:Receptors, Purinergic P1 / Q000502:physiology*; D015427:Reperfusion Injury / Q000517:prevention & control; D015398:Signal Transduction; D014343:Trypan Blue / Q000378:metabolism
chemical_list: D004396:Coloring Agents; D017362:Cyclic AMP Response Element-Binding Protein; D019384:Nucleic Acid Synthesis Inhibitors; D011500:Protein Synthesis Inhibitors; D058915:Purinergic P1 Receptor Antagonists; D043705:Receptor, Adenosine A2A; D018047:Receptors, Purinergic P1; D003609:Dactinomycin; D003513:Cycloheximide; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D014343:Trypan Blue; D000241:Adenosine