title: Cytochrome P450 2C epoxygenases mediate photochemical stress-induced death of photoreceptors.
abstract: Degenerative loss of photoreceptors occurs in inherited and age-related retinal degenerative diseases. A chemical screen facilitates development of new testing routes for neuroprotection and mechanistic investigation. Herein, we conducted a mouse-derived photoreceptor (661W cell)-based high throughput screen of the Food and Drug Administration-approved Prestwick drug library to identify putative cytoprotective compounds against light-induced, synthetic visual chromophore-precipitated cell death. Different classes of hit compounds were identified, some of which target known genes or pathways pathologically associated with retinitis pigmentosa. Sulfaphenazole (SFZ), a selective inhibitor of human cytochrome P450 (CYP) 2C9 isozyme, was identified as a novel and leading cytoprotective compound. Expression of CYP2C proteins was induced by light. Gene-targeted knockdown of CYP2C55, the homologous gene of CYP2C9, demonstrated viability rescue to light-induced cell death, whereas stable expression of functional CYP2C9-GFP fusion protein further exacerbated light-induced cell death. Mechanistically, SFZ inhibited light-induced necrosis and mitochondrial stress-initiated apoptosis. Light elicited calcium influx, which was mitigated by SFZ. Light provoked the release of arachidonic acid from membrane phospholipids and production of non-epoxyeicosatrienoic acid metabolites. Administration of SFZ further stimulated the production of non-epoxyeicosatrienoic acid metabolites, suggesting a metabolic shift of arachidonic acid under inhibition of the CYP2C pathway. Together, our findings indicate that CYP2C genes play a direct causative role in photochemical stress-induced death of photoreceptors and suggest that the CYP monooxygenase system is a risk factor for retinal photodamage, especially in individuals with Stargardt disease and age-related macular degeneration that deposit condensation products of retinoids.
authors: From the Departments of Ophthalmology and Visual Sciences and.
authors: Qing
authors: Q
authors: Chang
authors: Evgeny
authors: E
authors: Berdyshev
authors: Dingcai
authors: D
authors: Cao
authors: Joseph D
authors: JD
authors: Bogaard
authors: Jerry J
authors: JJ
authors: White
authors: Siquan
authors: S
authors: Chen
authors: Ravi
authors: R
authors: Shah
authors: Wenbo
authors: W
authors: Mu
authors: Rita
authors: R
authors: Grantner
authors: Sam
authors: S
authors: Bettis
authors: Michael A
authors: MA
authors: Grassi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D065729:Cytochrome P-450 CYP2C9; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000072467:Cytochrome P450 Family 2; D019610:Cytoprotection / Q000187:drug effects*; D004353:Drug Evaluation, Preclinical; D015870:Gene Expression; D020868:Gene Silencing; D006801:Humans; D008027:Light; D051379:Mice; D008969:Molecular Sequence Data; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects* / Q000201:enzymology / Q000528:radiation effects*; D016415:Sequence Alignment; D013426:Sulfaphenazole / Q000494:pharmacology*
chemical_list: D013426:Sulfaphenazole; D003577:Cytochrome P-450 Enzyme System; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C485373:Cyp2c55 protein, mouse; D000072467:Cytochrome P450 Family 2
keywords: Apoptosis; Calcium; Cytochrome P450; Drug Screening; Eicosanoid; Fatty Acid; Necrosis (Necrotic Death)