Oxidative stress-induced apoptosis in retinal photoreceptor cells is mediated by calpains and caspases and blocked by the oxygen radical scavenger CR-6.
A critical role for reactive oxygen species (ROS) in photoreceptor apoptosis has been established. However, the exact molecular mechanisms triggered by oxidative stress in photoreceptor cell death remain undefined. This study delineates the molecular events that occur after treatment of the photoreceptor cell line 661W with the nitric oxide donor sodium nitroprusside (SNP). Cytosolic calcium levels increased during photoreceptor apoptosis, leading to activation of the calcium-dependent proteases calpains. Furthermore, caspase activation also occurred following SNP insult. However, although treatment with the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone inhibited caspase activity per se in SNP-treated 661W cells, it did not prevent apoptosis. On the other hand, CR-6 (3,4-dihydro-6-hydroxy-7-methoxy-2,2-dimethyl-1(2H)-benzopyran) acted as a scavenger of ROS and reduced 661W photoreceptor apoptosis induced by SNP by preventing the activation of a pathway in which calpains have a key role. In summary, we report for the first time that both caspases and calpains are involved in 661W photoreceptor apoptosis and that calpain activation can be prevented by the ROS scavenger CR-6.
Sanvicens
Nuria
N
Tumour Biology Laboratory, Department of Biochemistry, Bioscience Research Institute, University College, Cork, Ireland.
Gómez-Vicente
Violeta
V
Masip
Isabel
I
Messeguer
Angel
A
Cotter
Thomas G
TG
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001578:Benzopyrans / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D053454:Caspase 12; D053148:Caspase 3; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology* / Q000201:enzymology*; D017382:Reactive Oxygen Species / Q000378:metabolism
D000590:Amino Acid Chloromethyl Ketones; D001578:Benzopyrans; C120400:CR 6; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D016166:Free Radical Scavengers; D020030:Nitric Oxide Donors; D017382:Reactive Oxygen Species; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D009599:Nitroprusside; D009569:Nitric Oxide; D002154:Calpain; C506440:Casp12 protein, mouse; C505409:Casp3 protein, mouse; C506434:Casp9 protein, mouse; D053454:Caspase 12; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; C449000:m-calpain; D002118:Calcium