title: Induction of necrotic cell death by oxidative stress in retinal pigment epithelial cells.
abstract: Age-related macular degeneration (AMD) is a degenerative disease of the retina and the leading cause of blindness in the elderly. Retinal pigment epithelial (RPE) cell death and the resultant photoreceptor apoptosis are characteristic of late-stage dry AMD, especially geographic atrophy (GA). Although oxidative stress and inflammation have been associated with GA, the nature and underlying mechanism for RPE cell death remains controversial, which hinders the development of targeted therapy for dry AMD. The purpose of this study is to systematically dissect the mechanism of RPE cell death induced by oxidative stress. Our results show that characteristic features of apoptosis, including DNA fragmentation, caspase 3 activation, chromatin condensation and apoptotic body formation, were not observed during RPE cell death induced by either hydrogen peroxide or tert-Butyl hydroperoxide. Instead, this kind of cell death can be prevented by RIP kinase inhibitors necrostatins but not caspase inhibitor z-VAD, suggesting necrotic feature of RPE cell death. Moreover, ATP depletion, receptor interacting protein kinase 3 (RIPK3) aggregation, nuclear and plasma membrane leakage and breakdown, which are the cardinal features of necrosis, were observed in RPE cells upon oxidative stress. Silencing of RIPK3, a key protein in necrosis, largely prevented oxidative stress-induced RPE death. The necrotic nature of RPE death is consistent with the release of nuclear protein high mobility group protein B1 into the cytoplasm and cell medium, which induces the expression of inflammatory gene TNFα in healthy RPE and THP-1 cells. Interestingly, features of pyroptosis or autophagy were not observed in oxidative stress-treated RPE cells. Our results unequivocally show that necrosis, but not apoptosis, is a major type of cell death in RPE cells in response to oxidative stress. This suggests that preventing oxidative stress-induced necrotic RPE death may be a viable approach for late-stage dry AMD.
authors: Department of Cell and Molecular Biology, Tulane University, New Orleans, LA, USA.
authors: J
authors: J
authors: Hanus
authors: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
authors: H
authors: H
authors: Zhang
authors: Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
authors: Z
authors: Z
authors: Wang
authors: Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
authors: Q
authors: Q
authors: Liu
authors: Department of Cell and Molecular Biology, Tulane University, New Orleans, LA, USA.
authors: Q
authors: Q
authors: Zhou
authors: 1] Department of Cell and Molecular Biology, Tulane University, New Orleans, LA, USA [2] Department of Ophthalmology, Tulane University, New Orleans, LA, USA.
authors: S
authors: S
authors: Wang
mesh_terms: D002460:Cell Line; D053938:DNA Fragmentation; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism*; D024243:HMGB1 Protein / Q000378:metabolism; D006801:Humans; D009336:Necrosis / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology*; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000166:cytology*; D014162:Transfection
chemical_list: D024243:HMGB1 Protein; C119705:RIPK3 protein, human; D053422:Receptor-Interacting Protein Serine-Threonine Kinases