The p55 tumor necrosis factor receptor (CD120a) induces endothelin-1 synthesis in endothelial and epithelial cells

Synthesis of the vasoconstrictor peptide endothelin-1 by endothelial and epithelial cells is strongly induced by tumor necrosis factor alpha (TNF-alpha). The actions of TNF-alpha are mediated by two transmembrane receptors of approximately 55 (p55, CD120a) and 75 kDa (p75, CD120b). Reagents activating selectively these receptor subtypes have been used to identify which TNF receptor mediates the induction of endothelin-1 synthesis. Stimulation of bovine aortic endothelial cells or human HEp-2 epithelial cells with a p55-selective mutant of human TNF-alpha (R32W-S86T) induced significant and concentration-dependent increases in endothelin-1 release. A p75 receptor-selective TNF-alpha mutant (D143N-A145R) was ineffective alone or in combination with the p55-selective mutant. Competitive binding experiments with [125I]TNF-alpha showed the p55-selective mutant, but not the p75-selective mutant, to inhibit the binding of [125I]TNF-alpha to endothelial and HEp-2 cells. Similar results were obtained with the p55 agonist antibody htr1 in both cell lines. These results establish the p55 TNF receptor as the main receptor involved in the induction of endothelin-1 synthesis by TNF-alpha.