title: Protective action of nipradilol mediated through S-nitrosylation of Keap1 and HO-1 induction in retinal ganglion cells.
abstract: Nipradilol (Nip), which has α1- and β-adrenoceptor antagonist and nitric oxide (NO)-donating properties, has clinically been used as an anti-glaucomatous agent in Japan. NO mediates cellular signaling pathways that regulate physiological functions. The major signaling mechanisms mediated by NO are cGMP-dependent signaling and protein S-nitrosylation-dependent signalings. Nip has been described as having neuroprotective effects through cGMP-dependent pathway in retinal ganglion cells (RGCs). However, the effect seems to be partial. On the other hand, whether Nip can prevent cell death through S-nitrosylation is not yet clarified. In this study, we therefore focused on the neuroprotective mechanism of Nip through S-nitrosylation. Nip showed a dramatic neuroprotective effect against oxidative stress-induced death of RGC-5 cells. However, denitro-nipradilol, which does not have NO-donating properties, was not protective against oxidative stress. Furthermore, an NO scavenger significantly reversed the protective action of Nip against oxidative stress. In addition, we demonstrated that α1- or β-adrenoceptor antagonists (prazosin or timolol) did not show any neuroprotective effect against oxidative stress in RGC-5 cells. We also demonstrated that Nip induced the expression of the NO-dependent antioxidant enzyme, heme oxygenase-1 (HO-1). S-nitrosylation of Kelch-like ECH-associated protein by Nip was shown to contribute to the translocation of NF-E2-related factor 2 to the nucleus, and triggered transcriptional activation of HO-1. Furthermore, RGC death and levels of 4-hydroxy-2-nonenal (4HNE) were increased after optic nerve injury in vivo. Pretreatment with Nip significantly suppressed RGC death and accumulation of 4HNE after injury through an HO-1 activity-dependent mechanism. These data demonstrate a novel neuroprotective action of Nip against oxidative stress-induced RGC death in vitro and in vivo.
authors.affiliation: Department of Molecular Neurobiology, Kanazawa University, Kanazawa, Japan. koriyama@med.kanazawa-u.ac.jp
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Koriyama
authors.forename: Marie
authors.initials: M
authors.lastname: Kamiya
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Takadera
authors.forename: Kunizo
authors.initials: K
authors.lastname: Arai
authors.forename: Kayo
authors.initials: K
authors.lastname: Sugitani
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ogai
authors.forename: Satoru
authors.initials: S
authors.lastname: Kato
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D017931:DNA Primers; D004790:Enzyme Induction; D051547:Heme Oxygenase-1 / Q000096:biosynthesis*; D007150:Immunohistochemistry; D000072019:Kelch-Like ECH-Associated Protein 1; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011412:Propanolamines / Q000494:pharmacology*; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D017931:DNA Primers; C117301:Keap1 protein, mouse; D000072019:Kelch-Like ECH-Associated Protein 1; D011412:Propanolamines; D014665:Vasodilator Agents; D009569:Nitric Oxide; D051547:Heme Oxygenase-1; C036089:nipradilol