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Apoptosis. 2006 Dec;11(12):2137-45.

EMAP-II facilitates TNF-R1 apoptotic signalling in endothelial cells and induces TRADD mobilization.

Author information

1
Laboratory of Experimental Surgical Oncology, Department of Surgical Oncology, 3000 Daniel den Hoed Cancer Centre, Erasmus MC-Room Ee 0104, PO Box 1738, Rotterdam, The Netherlands.

Abstract

Endothelial monocyte-activating polypeptide-II (EMAP-II), a proinflammatory cytokine with antiangiogenic properties, renders tumours sensitive to tumour necrosis factor-alpha (TNF) treatment. The exact mechanisms for this effect remain unclear. Here we show that human endothelial cells (EC) are insensitive to TNF-induced apoptosis but after a short pre-treatment with EMAP-II, EC quickly undergo TNF-induced apoptosis. We further analysed this EMAP-II pre-treatment effect and found no increase of TNF-R1 protein expression but rather an induction of TNF-R1 redistribution from Golgi storage pools to cell membranes. In addition, we observed EMAP-II induced mobilization and membrane expression of the TNF-R1-Associated Death Domain (TRADD) protein. Immunofluorescence co-staining experiments revealed that these two effects occurred at the same time in the same cell but TNF-R1 and TRADD were localized in different vesicles. These findings suggest that EMAP-II sensitises EC to apoptosis by facilitating TNF-R1 apoptotic signalling via TRADD mobilization and introduce a molecular and antiangiogenic explanation for the TNF sensitising properties of EMAP-II in tumours.

PMID:
17051333
DOI:
10.1007/s10495-006-0284-5
[Indexed for MEDLINE]

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