Retinal Pigment Epithelium Rescues Vascular Endothelium from Retinoic Acid-Induced Apoptosis

Abstract Background: Puerarin, an isoflavonoid, is a neuroprotectant against many ischemic brain injuries. The research purpose was to investigate whether puerarin treatment can inhibit hypoxia-induced apoptosis and barrier breakdown on human retinal pigment epithelium (ARPE-19) cells.Methods: Treatment with 100 µM of puerarin showed no ARPE-19 cytotoxicity. Treatments with 50 µM or 100 µM of puerarin significantly preserved cell viability under hypoxic conditions for 12 h (p < 0.05). Moreover, treatments with 50 µM and 100 µM of puerarin significantly reduced the proportion of Annexin V- and PI-positive ARPE cells under hypoxic conditions (p < 0.05). The TER analysis and junctional protein staining demonstrated that treatments with 50 µM or 100 µM of puerarin prevented the hypoxia-induced barrier disruption in APRE-19 cultures. In contrast to the untreated group, treatment with puerarin significantly increased the level of Bcl-2 and decreased the levels of p-Bad, Bax, and cleaved caspase 3 in RPE cell under hypoxic conditions (p < 0.05). Treatment with puerarin maintained Akt1 activation in the ARPE-19 cells under hypoxic conditions (p < 0.05), and inhibition of PR-induced Akt1 activation abolished the protective effect of puerarin in ARPE-19 cells under hypoxic conditions.Conclusion: Our results demonstrated that treatment with puerarin protected RPE cell against hypoxia-induced blood-retinal barrier breakdown and Akt-dependent apoptosis. These findings suggest that puerarin could be developed as an alternative treatment for ischemic and hypoxic retinal injuries.

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Chick embryonic pigmented retina is one of the group of epithelioid tissues that lack cytokeratins and desmosomes and have intermediate filaments composed of vimentin

Journal of Cell Science ◽

10.1242/jcs.71.1.61 ◽

1984 ◽

Vol 71 (1) ◽

pp. 61-74

Author(s):

R.J. Docherty ◽

J.G. Edwards ◽

D.R. Garrod ◽

D.L. Mattey

Keyword(s):

Retinal Pigment Epithelium ◽

Intermediate Filaments ◽

Vascular Endothelium ◽

Sodium Dodecyl Sulphate ◽

Pigment Epithelium ◽

Retinal Pigment ◽

Sodium Dodecyl ◽

Major Protein ◽

Ultrastructural Studies ◽

Chick Embryonic Tissue

Using sodium dodecyl sulphate/polyacrylamide gels to analyse detergent-insoluble residues, and indirect immunofluorescence, we have found that the major protein of intermediate filaments in cultures and freshly explanted fragments of chick embryonic retinal pigment epithelium (RPE) is vimentin. Moreover, these cells also fail to stain with antibodies against cytokeratins and most components of true desmosomes (maculae adhaerentes). Staining with anti-vinculin antibody suggests that the principal intercellular junction is the zonula adherens. Thus although RPE is an epithelium according to all other criteria, it belongs to a group of tissues (including vascular endothelium, iris and lens-forming epithelium) that have intermediate filaments composed of vimentin and possess neither cytokeratins nor desmosomes. That a tissue can be fully epithelial by other criteria, whilst lacking these components, is in agreement with other work, which has shown a lack of effect of micro-injection of antibodies to cytokeratin, and of the suppression of desmosome formation, on epithelial organization in culture. Although our observations were made solely on chick embryonic tissue, we suggest that published ultrastructural studies are consistent with the possibility that RPE of other species, including human, may lack true desmosomes.

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