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S. Kase, S. He, S. Sonoda, C. Spee, M. Kitamura, S. J. Ryan, R. Kannan, D. R. Hinton; Attenuation of Retinal Neovascularization in Oxygen-Induced Retinopathy in AlphaB-Crystallin Knockout Mice. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2941.
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© ARVO (1962-2015); The Authors (2016-present)
AlphaB-crystallin is a chaperone belonging to the small heat shock protein family. The aim of this study was to examine a role of alphaB-crystallin in retinal angiogenesis in vivo.
Retinal neovascularization was induced in oxygen-induced retinopathy in wild-type and alphaB-crystallin knockout (alphaB(-/-)) mice. Fluorescein angiography, histopathology, immunohistochemistry using antibodies for VEGF-A, phosphorylated alphaB-crystallin (pSer59), CD105, NG-1, VEGF-R2 antibodies, and TUNEL were performed in murine eyes at postnatal day 12 and 17 after exposure to hyperoxia. VEGF concentration and gene expression were analyzed by ELISA and real-time PCR in proteins and RNA extracted from posterior eyecups in treated mice, respectively. Expression of alphaB-crystallin, pSer59 and hypoxia-inducible factor (Hif)-1alpha were analyzed by Western blot, and VEGF binding to alphaB-crystallin in posterior eyecups was determined by immunoprecipitation.
Retinal neovascularization was prominently attenuated in alphaB(-/-) mice compared to wild-type mice as evaluated by fluorescein angiography and histopathology. Gene expression of VEGF, and Hif-1alpha and pSer59 protein expression were induced during retinal angiogenesis, but VEGF protein expression remained low in alphaB(-/-) retina compared with wild-type mice. Immunoprecipitation revealed alphaB-crystallin binding to VEGF during angiogenesis in wild-type mice. Immunoreactivity for CD105 was high in neovessels of wild-type mice, while NG-1 and VEGF-R2 expressions were similar in wild-type and alphaB(-/-) retinas. Endothelial cell apoptosis in newly formed vessels was significantly greater in alphaB(-/-) than in wild-type mice.
Our studies point to the important role of alphaB-crystallin in retinal angiogenesis and its potential as a therapeutic target; attenuation of angiogenesis in alphaB(-/-) mice might be mediated by downregulation of VEGF through posttranslational mechanisms.
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