Guanosine protects human neuroblastoma SH-SY5Y cells against mitochondrial oxidative stress by inducing heme oxigenase-1 via PI3K/Akt/GSK-3β pathway.
Mitochondrial perturbation and oxidative stress are key factors in neuronal vulnerability in several neurodegenerative diseases or during brain ischemia. Here we have investigated the protective mechanism of action of guanosine, the guanine nucleoside, in a human neuroblastoma cell line, SH-SY5Y, subjected to mitochondrial oxidative stress. Blockade of mitochondrial complexes I and V with rotenone plus oligomycin (Rot/oligo) caused a significant decrease in cell viability and an increase in ROS production. Guanosine that the protective effect of guanosine incubated concomitantly with Rot/oligo abolished Rot/oligo-induced cell death and ROS production in a concentration dependent manner; maximum protection was achieved at the concentration of 1mM. The cytoprotective effect afforded by guanosine was abolished by adenosine A(1) or A(2A) receptor antagonists (DPCPX or ZM241385, respectively), or by a large (big) conductance Ca(2+)-activated K(+) channel (BK) blocker (charybdotoxin). Evaluation of signaling pathways showed that the protective effect of guanosine was not abolished by a MEK inhibitor (PD98059), by a p38(MAPK) inhibitor (SB203580), or by a PKC inhibitor (cheleritrine). However, when blocking the PI3K/Akt pathway with LY294002, the neuroprotective effect of guanosine was abolished. Guanosine increased Akt and p-Ser-9-GSK-3β phosphorylation confirming this pathway plays a key role in guanosine's neuroprotective effect. Guanosine induced the antioxidant enzyme heme oxygenase-1 (HO-1) expression. The protective effects of guanosine were prevented by heme oxygenase-1 inhibitor, SnPP. Moreover, bilirubin, an antioxidant and physiologic product of HO-1, is protective against mitochondrial oxidative stress. In conclusion, our results show that guanosine can afford protection against mitochondrial oxidative stress by a signaling pathway that implicates PI3K/Akt/GSK-3β proteins and induction of the antioxidant enzyme HO-1.
Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Trindade, 88040-900 Florianópolis, SC, Brazil. tharinedc@yahoo.com.br
Tharine
T
Dal-Cim
Simone
S
Molz
Javier
J
Egea
Esther
E
Parada
Alejandro
A
Romero
Josiane
J
Budni
Maria D
MD
Martín de Saavedra
Laura
L
del Barrio
Carla I
CI
Tasca
Manuela G
MG
López
D015153:Blotting, Western; D045744:Cell Line, Tumor; D004790:Enzyme Induction; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006151:Guanosine / Q000494:pharmacology*; D051547:Heme Oxygenase-1 / Q000096:biosynthesis*; D006801:Humans; D008928:Mitochondria / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000187:drug effects*; D018384:Oxidative Stress / Q000187:drug effects*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
D017382:Reactive Oxygen Species; D006151:Guanosine; D051547:Heme Oxygenase-1; D019869:Phosphatidylinositol 3-Kinases; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3