Death Receptors Bind SHP-1 and Block Cytokine-induced Anti-apoptotic Signaling in Neutrophils

Death domain-containing receptors of the tumor necrosis factor (TNF)/nerve growth factor (NGF) family can induce apoptosis upon activation in many cellular systems. We show here that a conserved phosphotyrosine-containing motif within the death domain of these receptors can mediate inhibitory functions. The Src homology domain 2 (SH2)-containing tyrosine phosphatase-1 (SHP-1), SHP-2 and SH2-containing inositol phosphatase (SHIP) bound to this motif in a caspase-independent but cell-dependent manner. We also found that stimulation of death receptors disrupted anti-apoptosis pathways initiated (at least under certain conditions) by survival factors in neutrophils. In these cells, activation of the tyrosine kinase Lyn, an important anti-apoptotic event, was prevented as a consequence of death-receptor stimulation, most likely through association of the receptor with activated SHP-1. Thus, we provide molecular and functional evidence for negative signaling by death receptors.