This entry represents TRADD (or tumour necrosis factor receptor type 1-associated DEATH domain protein). TRADD interacts with the cytoplasmic domain of activated TNFRSF1A/TNFR1, which in turn enables it to interact with FADD. Overexpression of TRADD results in apoptosis and activation of NF-kappa-B []. TRADD shuttles from the cytoplasm into the nucleus. The nuclear form of TRADD is a tumour suppressor, which by interacting with TRIP12 disrupts its complex with isoform p19ARF/ARF of CDKN2A, preventing ubiquitination and degradation [].
TRADD is a signalling adaptor protein involved in tumour necrosis factor-receptor I (TNFR1)-associated apoptosis and cell survival. The decision between apoptosis and cell survival involves the interplay between two sequential signalling complexes. The plasma membrane-bound complex I is comprised of TNFR1, TRADD, the kinase RIP1, and TRAF2, which together mediate the activation of NF-kappaB. Subsequently, complex II is formed in the cytoplasm, where TRADD and RIP1 associate with FADD and caspase-8. If NF-kappaB is activated by complex I, then complex II will associate with the caspase-8 inhibitor FLIP(L) and the cell survives, while the failure to activate NF-kappaB leads to apoptosis [].TRADD contains two functionally separate domains, which allow the protein to couple to two distinct signaling pathways. The TRADD C-terminal death domain is responsible for its association with TNFR1, and with the death-domain proteins FADD and RIP1, which promote apoptosis. The TRADD N-terminal domain binds TRAF2 and promotes TRAF2 recruitment to TNFR1, thereby mediating the activation of NK-kappaB and JNK/AP1, which promote cell survival []. The N-terminal TRADD domain is composed of an α/β sandwich, where the β-strands form an antiparallel β-sheet.
TRADD is a signalling adaptor protein involved in tumour necrosis factor-receptor I (TNFR1)-associated apoptosis and cell survival. The decision between apoptosis and cell survival involves the interplay between two sequential signalling complexes. The plasma membrane-bound complex I is comprised of TNFR1, TRADD, the kinase RIP1, and TRAF2, which together mediate the activation of NF-kappaB. Subsequently, complex II is formed in the cytoplasm, where TRADD and RIP1 associate with FADD and caspase-8. If NF-kappaB is activated by complex I, then complex II will associate with the caspase-8 inhibitor FLIP(L) and the cell survives, while the failure to activate NF-kappaB leads to apoptosis [].TRADD contains two functionally separate domains, which allow the protein to couple to two distinct signaling pathways. The TRADD C-terminal death domain is responsible for its association with TNFR1, and with the death-domain proteins FADD and RIP1, which promote apoptosis. The TRADD N-terminal domain binds TRAF2 and promotes TRAF2 recruitment to TNFR1, thereby mediating the activation of NK-kappaB and JNK/AP1, which promote cell survival []. The N-terminal TRADD domain is composed of an α/β sandwich, where the β-strands form an antiparallel β-sheet.
This subfamily of tumor necrosis factor receptor 1A (TNFRSF1, also known as type I TNFR, TNFR1, DR1, TNFRSF1A, CD120a, p55) is found in teleosts. It binds TNF-alpha, through the death domain (DD), and activates NF-kappaB, mediates apoptosis and activates signaling pathways controlling inflammatory, immune, and stress responses. It mediates signal transduction by interacting with antiapoptotic protein BCL2-associated athanogene 4 (BAG4/SODD) and adaptor proteins TRAF2 and TRADD that play regulatory roles [, ].Knockout studies in zebrafish embryos have shown that a signaling balance between TNFRSF1A and TNFRSF1B is required for endothelial cell integrity. TNFRSF1A signals apoptosis through caspase-8, whereas TNFRSF1B signals survival via NF-kappaB in endothelial cells. Thus, this apoptotic pathway seems to be evolutionarily conserved, as TNFalpha promotes apoptosis of human endothelial cells and triggers caspase-2 and P53 activation in these cells via TNFRSF1A [].This entry represents the N-terminal domain of TNFR1A from teleosts. TNF-receptors are modular proteins. The N-terminal extracellular part contains a cysteine-rich region responsible for ligand-binding. This region is composed of small modules of about 40 residues containing 6 conserved cysteines; the number and type of modules can vary in different members of the family [, , ].
Tumor necrosis factor receptor superfamily member 1A (TNFRSF1A, also known as type I TNFR, TNFR1, DR1, CD120a, p55) binds TNF-alpha, through the death domain (DD), and activates NF-kappaB, mediates apoptosis and activates signaling pathways controlling inflammatory, immune, and stress responses. It mediates signal transduction by interacting with antiapoptotic protein BCL2-associated athanogene 4 (BAG4/SODD) and adaptor proteins TRAF2 and TRADD that play regulatory roles [, ].The human genetic disorder called tumor necrosis factor associated periodic syndrome (TRAPS), or periodic fever syndrome, is associated with germline mutations of the extracellular domains of this receptor, possibly due to impaired receptor clearance []. TNFRSF1A polymorphisms rs1800693 and rs4149584 are associated with elevated risk of multiple sclerosis []. Serum levels of TNFRSF1A are elevated in schizophrenia and bipolar disorder, and high levels are also associated with cognitive impairment and dementia [, ]. Patients with idiopathic recurrent acute pericarditis (IRAP), presumed to be an autoimmune process, have also been shown to carry rare mutations (R104Q and D12E) in the TNFRSF1A gene [].This entry represents the N-terminal domain of TNFR1A. TNF-receptors are modular proteins. The N-terminal extracellular part contains a cysteine-rich region responsible for ligand-binding. This region is composed of small modules of about 40 residues containing 6 conserved cysteines; the number and type of modules can vary in different members of the family [, , ].
RIP kinases serve as essential sensors of cellular stress. Vertebrates contain several types containing a homologous N-terminal kinase domain and varying C-terminal domains [, ]. RIP1 harbours a C-terminal Death domain (DD), which binds death receptors (DRs) including TNF receptor 1, Fas, TNF-related apoptosis-inducing ligand receptor 1 (TRAILR1), and TRAILR2. It also interacts with other DD-containing adaptor proteins such as TRADD and FADD. RIP1 plays a crucial role in determining a cell's fate, between survival or death, following exposure to stress signals. It is important in the signaling of NF-kappaB and MAPKs, and it links DR-associated signaling to reactive oxygen species (ROS) production. Abnormal RIP1 function may result in ROS accumulation affecting inflammatory responses, innate immunity, stress responses, and cell survival [, ]. DDs (Death domains) are protein-protein interaction domains found in a variety of domain architectures. Their common feature is that they form homodimers by self-association or heterodimers by associating with other members of the DD superfamily including CARD (Caspase activation and recruitment domain), DED (Death Effector Domain), and PYRIN. They serve as adaptors in signaling pathways and can recruit other proteins into signaling complexes [, ].
