Purchase this article with an account.
Y. Zhong, J. Li, J. Wang, Y. Le, S. Zhang; X-Box Binding Protein 1 is a Novel Regulator of Anti-Oxidant Genes in the RPE. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1427.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Oxidative damage of the retinal pigment epithelium (RPE) is a significant pathogenic factor of age-related macular degeneration (AMD). Identifying key regulators of the anti-oxidant defense system can provide critical information for developing therapeutic modalities to prevent or halt the development and progression of AMD. X-box-binding protein (XBP1) is a bZIP transcription factor that induces genes involved in multiple cellular processes, such as biogenesis of the endoplasmic reticulum (ER), protein folding and lipogenesis. The purpose of this study is to investigate the role of XBP1 in the regulation of the anti-oxidant system and oxidative stress in the RPE.
Human RPE (ARPE-19) cells were transfected with siRNA specific for XBP1 or control siRNA for 24 h. The mRNA and protein expressions of anti-oxidant genes were examined by real-time PCR and Western blot analysis, respectively. Intracellular superoxide (O2-) and reactive oxygen species (ROS) were determined by dihydroethidium (DHE) and dichlorofluorescein (DCF) fluorescence. Cell viability was determined by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay.
Depletion of XBP1 significantly decreased the mRNA expression of anti-oxidant genes, including nuclear-factor-E2-related factor 2 (Nrf2), superoxide dismutase (SOD1 and SOD2), catalase, and glutathione synthase, in human ARPE-19 cells. Decreased protein levels of Nrf2 and SOD2 in XBP1-deficient cells were confirmed by Western blot analysis. These changes coincided with increased levels of intracellular O2- and ROS. In addition, depletion of XBP1 significantly decreased cell viability in ARPE-19 cells.
Our results suggest XBP1 is a novel transcription factor coordinating the cellular protective system in the RPE. Insight into the mechanisms of XBP1 on regulation of anti-oxidant genes and developing XBP1-based therapeutic strategies may provide novel approaches to prevent and treat AMD.
This PDF is available to Subscribers Only