Purine nucleoside-mediated protection of chemical hypoxia-induced neuronal injuries involves p42/44 MAPK activation.
Hypoxia in brain may lead to cell death by apoptosis and necrosis. Concomitant is the formation of purine nucleosides, e.g. adenosine, a powerful endogenous neuroprotectant. Despite vigorous studies, many aspects of the mechanisms involved in purine-based protection are still unclear. In this study, we wanted to investigate the effect of purine nucleosides on cellular responses to chemical hypoxia. O(2)-sensitive neuronal pheochromocytoma (PC12)-cells, which are widely used as a model system for sympathetic ganglion-like neurons, were subjected to chemical hypoxia induced with rotenone, an inhibitor of mitochondrial complex I. Adenosine and its relatives guanosine and inosine were tested for their neuroprotective capability to improve neurite outgrowth and viability. In addition, cell lysates were analyzed for mitogen-activated-protein-kinases (MAPK) activation by anti-active and anti-total MAPKinase immunoblotting. Adenosine, guanosine and inosine significantly inhibited the loss of viability after hypoxic insult. In combination with NGF, purine nucleosides also partially rescued neurite outgrowth. The MEK-1/-2 inhibitor PD098059 inhibited purine nucleoside-mediated protection up to 85.23% and also markedly decreased neurite formation induced by NGF and purine nucleosides in hypoxic cells. Immunoblot analysis revealed a strong activation of MAPKinase upon incubation of cells with adenosine, guanosine or inosine. In combination with NGF an additive effect was observed. Results suggested that activation of the MAPKinase pathway plays a vital role in purine nucleoside-mediated protection of neuronal cells following hypoxic insult.
Tomaselli
Bettina
B
Biocenter Innsbruck, Division of Neurobiochemistry, Medical University of Innsbruck, Fritz Pregl Strasse 3, A-6020 Innsbruck, Austria.
Podhraski
Valerie
V
Heftberger
Veronika
V
Böck
Günther
G
Baier-Bitterlich
Gabriele
G
D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D004357:Drug Synergism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006151:Guanosine / Q000494:pharmacology; D002534:Hypoxia, Brain / Q000188:drug therapy / Q000378:metabolism*; D007288:Inosine / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000187:drug effects / Q000378:metabolism; D009410:Nerve Degeneration / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D020932:Nerve Growth Factor / Q000494:pharmacology; D018696:Neuroprotective Agents / Q000494:pharmacology* / Q000627:therapeutic use; D016716:PC12 Cells; D011684:Purine Nucleosides / Q000494:pharmacology* / Q000627:therapeutic use; D051381:Rats; D012402:Rotenone; D014475:Uncoupling Agents
D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D011684:Purine Nucleosides; D014475:Uncoupling Agents; D012402:Rotenone; D006151:Guanosine; D007288:Inosine; D020932:Nerve Growth Factor; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D000241:Adenosine