Tumor necrosis factor-related apoptosis-inducing ligand receptor (TRAIL receptor) (TRAILR (also known as DR4 and DR5 for the main signaling receptors))

The **tumor necrosis factor-related apoptosis-inducing ligand receptors**—commonly referred to as **TRAIL receptors**—are members of the tumor necrosis factor receptor superfamily that mediate extrinsic apoptotic signaling. The two principal pro-apoptotic human TRAIL receptors are **Death Receptor 4** (**DR4**, also called **TRAIL-R1**, TNFRSF10A) and **Death Receptor 5** (**DR5**, also called **TRAIL-R2**, TNFRSF10B). These transmembrane proteins contain an intracellular "death domain" critical for transmitting apoptotic signals. Upon binding their cognate ligand (**TRAIL/APO2L**), these receptors trimerize at the cell surface. This conformational change recruits adaptor proteins such as FADD via homotypic interactions between their respective death domains. The resulting complex—the death-inducing signaling complex (**DISC**)—recruits initiator procaspases (-8/-10), which become activated through proximity-induced auto-cleavage. Activated caspase 8 then triggers a proteolytic cascade involving effector caspases (-3/-7) that execute programmed cell death. This pathway is especially important in immune surveillance against tumors because it preferentially induces apoptosis in transformed or malignant cells while sparing most normal tissues. However, many cancers develop resistance mechanisms—including upregulation of decoy TRAIL receptors lacking functional death domains—that limit clinical efficacy. Therapeutic strategies have included recombinant human TRAIL ligands and agonistic antibodies targeting DR4/DR5; however, clinical benefit has been limited by resistance mechanisms within tumors and variable patient responses.[1][2][6]

Other names

Death receptor 4 (DR4, TRAILR1, TNFRSF10A)Death receptor 5 (DR5, TRAILR2, TNFRSF10B)Apo2CD261 (for DR4), CD262 (for DR5)Tumor necrosis factor receptor superfamily member 10A/10BDecoy receptors DcR1/TRAILR3 and DcR2/TRAILR4 are related but do not signal apoptosis[1][2][9]

Agonist antibodies or ligands bind to TRAIL receptors to trigger oligomerization, recruitment of FADD adaptor protein, formation of the death-inducing signaling complex (DISC), activation of caspase 8/10, leading to downstream caspase cascade and apoptosis in target cells—primarily tumor cells[1][2][6].