Purchase this article with an account.
P. Bargagna–Mohan, R. Mohan; Potential Angiopreventive Mode of Action of Withaferin A . Invest. Ophthalmol. Vis. Sci. 2005;46(13):467.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Previously, we showed that Withaferin A (WA), a small molecule natural product, interferes with the Ubiquitinated Proteosome Pathway (UPP) machinery in vascular endothelial cells. WA increases the level of ubiquitinated proteins and blocks the activation of the transcription factor NF–kB, a key regulator in inflammatory and stress responses. Based on these findings, we hypothesized that WA may protect endothelial cells from oxidative stress injury. We focused our studies on the Heme Oxygenase–1 (HO–1) gene, a well–known inducible anti–stress protein, which is the rate limiting enzyme that converts heme to biliverdin, CO and Ferritin. Methods: We employed primary endothelial cell cultures from Human Umbelical Vein (HUVEC) and Human Choroidal Endothelial Cells (HCEC) for our studies. To determine whether HO–1 is responsive to WA action we performed time–course and dose–response experiments. HUVEC and HCEC were growth–arrested by serum starvation and stimulated with basic fibroblast growth factor (b–FGF) at 10ng/ml in the presence or absence of different concentrations of WA. After treatments, cell lysates were used for Western Blot analysis. Results: We observed that untreated HUVEC and HCEC cells do not express HO–1. In WA–treated HUVEC, WA induces expression of HO–1 at concentrations above 200 nM and its expression is observed as early as 4h with increased expression being observed though the 24h time–course period. In WA–treated HCEC, HO–1 expression is induced at 1µM and higher concentrations. Conclusions: HO–1 is currently thought to play a very important role in protection of the vascular system from oxidative and inflammatory damage. Our findings demonstrate that WA is a potent inducer of HO–1 in endothelial cells. Thus the anti–oxidant effect of WA, combined with its potent NF–kB inhibitory activity, may be important for prophilaxis or pharmacological treatment of age–related macula degeneration (AMD), where cyto–protection of the retina and choroidal vasculature from oxidative injury could be key to prevention of the wet form of AMD.
This PDF is available to Subscribers Only