Endo-PDI is required for TNFα-induced angiogenesis

De Lucca Camargo, L. , Babelova, A., Mieth, A., Weigert, A., Mooz, J., Rajalingam, K., Heide, H., Wittig, I., Rossetti Lopes, L. and Brandes, R. P. (2013) Endo-PDI is required for TNFα-induced angiogenesis. Free Radical Biology and Medicine, 65, pp. 1398-1407. (doi: 10.1016/j.freeradbiomed.2013.09.028) (PMID:24103565)

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Protein disulfide isomerase (PDI) and its homologs are oxidoreductases facilitating protein folding in the ER. Endo-PDI (also termed ERp46) is highly expressed in endothelial cells. It belongs to the PDI family but its physiological function is largely unknown. We studied the role of Endo-PDI in endothelial angiogenic responses. Stimulation of human umbilical vein endothelial cells (with TNFα (10 ng/ml) increased ERK1/2 phosphorylation. This effect was largely attenuated by Endo-PDI siRNA, whereas JNK and p38 MAP kinase phosphorylation was Endo-PDI independent. Similarly, TNFα-stimulated NF-κB signaling determined by IκBα degradation as well as TNFα-induced ICAM expression was unaffected by Endo-PDI siRNA. The action of Endo-PDI was not mediated by extracellular thiol exchange or cell surface PDI as demonstrated by nonpermeative inhibitors and PDI-neutralizing antibody. Moreover, exogenously added PDI failed to restore ERK1/2 activation after Endo-PDI knockdown. This suggests that Endo-PDI acts intracellularly potentially by maintaining the Ras/Raf/MEK/ERK pathway. Indeed, knockdown of Endo-PDI attenuated Ras activation measured by G-LISA and Raf phosphorylation. ERK activation influences gene expression by the transcriptional factor AP-1, which controls MMP-9 and cathepsin B, two proteases required for angiogenesis. TNFα-stimulated MMP-9 and cathepsin B induction was reduced by silencing of Endo-PDI. Accordingly, inhibition of cathepsin B or Endo-PDI siRNA blocked the TNFα-stimulated angiogenic response in the spheroid outgrowth assays. Moreover ex vivo tube formation and in vivo Matrigel angiogenesis in response to TNFα were attenuated by Endo-PDI siRNA. In conclusion, our study establishes Endo-PDI as a novel, important mediator of AP-1-driven gene expression and endothelial angiogenic function.

Item Type:Articles
Glasgow Author(s) Enlighten ID:De Lucca Camargo, Ms Livia
Authors: De Lucca Camargo, L., Babelova, A., Mieth, A., Weigert, A., Mooz, J., Rajalingam, K., Heide, H., Wittig, I., Rossetti Lopes, L., and Brandes, R. P.
College/School:College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
Journal Name:Free Radical Biology and Medicine
ISSN (Online):1873-4596
Published Online:05 October 2013

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