The Role of Bcl-x_Lin Mouse RPE Cell Survival

Abstract

PURPOSE. Retinal pigment epithelial (RPE) cell survival plays a critical role in normal physiology and in retinal diseases, such as age-related macular degeneration (AMD) and proliferative vitreoretinopathy (PVR). We have previously demonstrated that Bcl-x(L) is an important cell survival protein in human RPE (hRPE) cells. Herein, we determined the role of Bcl-x(L) as a survival protein in mouse RPE (mRPE) cells. METHODS. Survival factor gene expression and Bcl-x(L) protein distribution were determined using qRT-PCR and immunohistochemistry, respectively. Cultured mRPE cells were transfected with two modified 2'-O-methoxyethoxy antisense oligonucleotides (ASOs): Bcl-x(L)-mismatched control and Bcl-x(L)-specific. Bcl-x(L) protein levels were analyzed using Western blot. To determine the effects of survival factor regulation in mRPE cells, cultured cells were treated for 24 hours with mouse TNF-α, human IL-1β, and human TNF-α. RESULTS. Bcl-x(L) was the most highly expressed survival factor in both mouse eyecup and cultured mRPE cells, whereas Bax was the most highly expressed antisurvival factor. Bcl-x(L) was expressed in the RPE layer, and the distribution among the retinal layers was similar to that observed in human eyecups. IL-1β and TNF-α had minimal effect on Bcl-x(L) and Bax expression and strongly upregulated Traf-1. Transfection with Bcl-x(L)-specific ASO resulted in markedly diminished Bcl-x(L) gene expression, Bcl-x(L) protein levels, and cell number. CONCLUSIONS. Bcl-x(L) is the most highly expressed survival gene in mRPE cells and is essential for mRPE cell survival. Our data suggest that mouse tissue is an appropriate model for investigations of RPE survival factor genes.

IL1RL1 is dynamically expressed on Cbfb-MYH11+ leukemia stem cells and promotes cell survival

“…6B,C), indicating that IL-33 does not induce proliferation in Cbfb-MYH11 + leukemia cells. To test if increased cell survival could mediate IL-33’s effect on colony-forming ability, we performed quantitative reverse-transcription PCR (qRT-PCR) for genes known to be induced by IL-33 in normal myeloid cells: Bcl-xl , Bcl-2 , TRAF-1 , TRAF-2 , and Mcl-1 27,28 . After 6 hours of stimulation with IL-33, we observed significantly increased expression of Bcl-xl , TRAF-1 , TRAF-2 , and Mcl-1 , but not Bcl-2 in leukemia cells (Fig.…”

Nitric oxide leads to cytoskeletal reorganization in the retinal pigment epithelium under oxidative stress

“…Reduced Bcl-x L expression levels confer apoptotic cell death in the RPE [20]. Inhibition of Bcl-x L expression alters RPE morphology and diminishes cell survival [21].…”

“…The regulatory subunit PP2Ab enhances the formation of stable complexes between PP2Aa-c. PP2A positively regulates apoptosis by controlling pro-apoptotic molecules (Bad, Bak, Bax) and anti-apoptotic Bcl-2 family members (Bcl-x L ) [20]. PP2A dephosphorylates phosducin, a phosphoprotein which modulates the light activated phototransduction cascade in vertebrate retina [19, 20]. Suppression of endogenous PP2Aa by 50% leads to cell transformation; further suppression results in cell cycle arrest and apoptosis.…”

Glucocorticoid-Induced Leucine Zipper Protects the Retina From Light-Induced Retinal Degeneration by Inducing Bcl-xL in Rats

“…Previous studies showed that TNF-a downregulates Bcl-xL in various cell types. [30][31][32][33] Therefore, we hypothesized that GILZ inhibits proapoptotic factors such as TNF-a by inhibiting NF-jB p65 transcriptional activity, and the downregulation of proapoptotic factors allows upregulation of Bcl-xL in the retina. TUNEL staining showed that most of the apoptotic cells following light damage were photoreceptor cells and that GILZ overexpression significantly protected the apoptosis of photoreceptors.…”