1 Graduate School of Health and Medical Sciences, Faculty of Health and Medical Sciences, Københavns Universitet2 Department of Immunology and Microbiology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, Københavns Universitet3 Department of Ophthalmology, Copenhagen University Hospital Roskilde, 4000 Roskilde, Denmark.4 Department of Neuroscience and Pharmacology, University of Copenhagen Copenhagen, Denmark.5 Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark ; Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.6 Graduate School of Health and Medical Sciences, Faculty of Health and Medical Sciences, Københavns Universitet7 Department of Immunology and Microbiology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, Københavns Universitet
PURPOSE: To investigate the significance of calcium-independent phospholipase A₂, group VIA (iPLA2-VIA), in RPE cell survival following responses to sodium iodate (SI) in cell cultures. METHODS: The human retinal pigment epithelium (RPE) cell line (ARPE-19) cells and primary mouse-RPE cultures were treated with SI to induce cell death. Cells were transfected with an iPLA₂-VIA promoter-luciferase construct to evaluate the regulation of iPLA-VIA after exposure to SI. PCR analysis, western blot analysis, and activity assays were performed to evaluate the mRNA level, protein level, and activity levels of iPLA₂-VIA after SI exposure. Inhibitors of iPLA₂-VIA were used to explore a potential protective role in cells exposed to SI. Primary RPE cell cultures were grown from iPLA₂-VIA knockout mice and wild-type mice. The cultures were exposed to SI to investigate a possible increased protection against SI in iPLA₂-VIA knockout mice compared to wild-type mice. RESULTS: The study revealed upregulation of iPLA₂-VIA expression (promoter activity, iPLA₂-VIA mRNA, iPLA₂-VIA protein, and iPLA₂-VIA protein activity) in ARPE-19 cells exposed to SI. SI-induced cell death was shown to be inhibited by iPLA₂-VIA-specific inhibitors in ARPE-19 cell cultures. RPE cultures from iPLA₂-VIA knockout mice were less vulnerable to SI-induced cell death compared to RPE cultures from wild-type mice. CONCLUSIONS: SI -induced RPE cell death involves iPLA₂-VIA upregulation and activation, and amelioration of SI-induced RPE cell death can be facilitated by inhibitors of iPLA₂-VIA. Thus, we suggest iPLA₂-VIA as a possible pharmaceutical target to treat RPE-related retinal diseases.