title: In vitro inhibition of antirecoverin immunoglobulin-mediated death of mammalian photoreceptor cells.
abstract: Cancer-associated retinopathy (CAR) is a blinding disease, which can be mediated by autoimmune reactions with a specific calcium-binding retinal protein, recoverin. A number of recent studies demonstrate that agents that mobilize intracellular calcium can protect neurons from apoptotic death induced by a variety of insults. In this study, we investigated the effect of one such agent, potassium, on the survival of mammalian rod photoreceptors exposed to antirecoverin IgG. Primary cell cultures of rat retinal neurons were grown in a chemically defined medium, and cells were exposed to antirecoverin IgG for 72 hr in various concentrations of potassium and the surviving cells counted. Rod photoreceptors were quantitated using antirhodopsin immunofluorescence microscopy, and total cell numbers were determined by 4',6-diamidino-2-phenylindole (DAPI) staining of nuclei. Apoptosis was evaluated by TdT-mediated biotin-dUTP nick-end labeling (TUNEL), cell death-detection ELISA, and DNA laddering. The present study shows that elevated extracellular K+ ([K+](o)) protects retinal neurons from antirecoverin antibody-mediated cell death. The protective effects of ([K+](o)) were shown to be time- and dose-dependent. The inhibition of antirecoverin IgG-mediated death of photoreceptors by elevated ([K+](o)) suggests that the mobilization of internal calcium stores rescues the cells by interfering with apoptotic signal transduction pathways. These data also suggest that the death of photoreceptor cells occurring in CAR possibly can be prevented by reagents and/or environmental changes that mobilize intracellular calcium.
authors.affiliation: Department of Ophthalmology, Dean A. McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton Young Boulevard, Oklahoma City, OK 73104, USA.
authors.forename: W
authors.initials: W
authors.lastname: Chen
authors.forename: W
authors.initials: W
authors.lastname: Cao
authors.forename: A M
authors.initials: AM
authors.lastname: Achyuthan
authors.forename: J F
authors.initials: JF
authors.lastname: McGinnis
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects* / Q000276:immunology; D002135:Calcium-Binding Proteins / Q000276:immunology* / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D002478:Cells, Cultured; D053938:DNA Fragmentation / Q000187:drug effects / Q000276:immunology; D004305:Dose-Response Relationship, Drug; D005136:Eye Proteins; D051597:Hippocalcin; D007074:Immunoglobulin G / Q000494:pharmacology*; D020287:In Situ Nick-End Labeling; D008074:Lipoproteins; D009419:Nerve Tissue Proteins; D018696:Neuroprotective Agents / Q000494:pharmacology*; D020361:Paraneoplastic Syndromes, Nervous System / Q000188:drug therapy / Q000276:immunology / Q000503:physiopathology; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D051603:Recoverin; D012164:Retinal Diseases / Q000188:drug therapy / Q000276:immunology / Q000503:physiopathology; D017948:Retinal Rod Photoreceptor Cells / Q000187:drug effects* / Q000276:immunology / Q000503:physiopathology
chemical_list: D002135:Calcium-Binding Proteins; D005136:Eye Proteins; D007074:Immunoglobulin G; D008074:Lipoproteins; D009419:Nerve Tissue Proteins; D018696:Neuroprotective Agents; C496733:Rcvrn protein, rat; D051603:Recoverin; D051597:Hippocalcin; D011188:Potassium