Synthetic peptides corresponding to ligand-binding region of death receptors, DR5, Fas, and TNFR, specifically inhibit cell death mediated by the death ligands, respectively.

Apoptosis as well as cell growth and cell differentiation play an important role in the maintenance of homeostasis in multicellular organisms. Disruption of apoptosis causes serious diseases, such as cancer, chronic inflammatory diseases, and autoimmune diseases; therefore, the control of apoptosis is one of the most promising therapeutic approaches to these apoptosis-disrupted diseases. Apoptosis is mediated by soluble factors, which belong to the TNF superfamily, such as TNF-alpha, FasL, and TRAIL. Here, we report that we deduced ligand-binding domains based on the structure of apoptosis ligand-receptor complex, and the synthetic peptide corresponding to residues 91-102 of DR5 indeed showed specific binding to TRAIL molecule and inhibited TRAIL-induced cell death both in L929 cells and in HeLa cells. The other death receptor-derived peptides, which are the corresponding regions of TNFR1 and Fas, also showed specific binding to TNF-alpha and FasL and inhibited the ligand-induced cell death, respectively. These results suggest that the position of the ligand-binding region is conserved among these death-receptor family members, whereas the primary amino acid sequence determines ligand specificity.