Tumor necrosis factor alpha (TNFα) is a proinflammatory cytokine involved in various biological processes including regulation of cell proliferation, differentiation, apoptosis and immune response. TNFα is mainly produced by macrophages, also by other tissues including lymphoid cells, mast cells, endothelial cells, fibroblasts and neuronal tissues. TNF was identified as a soluble cytokine produced upon the activation by the immune system and able to exert cytotoxicity on tumor cell lines and cause tumor necrosis in animal models. TNF is primarily produced as a type II transmembrane protein arranged as stable homotrimers. The members of TNFα family exert their cellular effect through two distinct surface receptors of the TNF receptor family, TNFRSF1A (TNF-R1) and TNFRSF1B (TNF-R2). TNF-R1 is ubiquitously expressed, whereas TNF-R2 is found typically on cells of the immune system and is highly regulated. TNF-R1 and TNF-R2 binds membrane-integrated TNF (memTNF) as well as soluble TNF (sTNF) TNF-R1 contains a protein-protein interaction domain, called death domain (DD). This domain interacts with other DD-containing proteins and couples the death receptors to caspase activation and apoptosis. TNF-R2 induces gene expression by a TRAF-2 dependent signaling mechanism and also crosstalk's with TNF-R1. The pleiotropic biological effects of TNF can be attributed to its ability to simultaneously activate multiple signaling pathways in cells. Binding of TNFα to TNF-R1 on the cell surface triggers trimerization of the receptor and exposes intracellular domain of TNF-R1 following the release of an inhibitory protein. This intracellular domain recruits a death-domain containing adaptor protein, TRADD by homophilic interactions. TRADD, which acts as a scaffold protein, recruits TRAF2 and RIPK1 to form a complex , referred to as complex 1. Complex 1 is believed to be important in NF-κB activation and JNK activation. Complex 1 eventually dissociates from the receptor and integrates FADD and procaspase8 to form a complex referred to as the complex 2. In some cases, FADD/CASP8 association depends on high molecular weight complexes containing unubiquitinated RIPK1 as scaffold. Activated CASP8 induces CASP3 activity and execution of apoptosis. CASP8 activates apoptotic signal through another mechanism involving BID cleavage to truncated BID (tBID). tBID translocates to the mitochondria, increasing its outer membrane permeability. This results in cytochrome C release and activation of other caspases ultimately leading to apoptosis. Reactive oxygen species (ROS) have been found to increase during or after complex 1 and 2 formation to mediate or potentiate apoptosis upon TNF stimulation. TRAF-2 in complex 1 also activates the MAP kinase cascade, that leads to the activation of JNK, which on prolonged activation is believed to mediate both apoptosis and necrotic cell death. On complex 1 formation, NF-κB regulated anti-apoptotic gene products efficiently block initiation of apoptosis by complex 2. There is evidence of an early attempt to signal for apoptosis, which precedes the activation of NF-κB. The intracellular part of TNF-R1 binds to NSMAF which in turn mediates SMPD2-dependant ceramide production from cell membrane. Ceramide induces membrane permeabilization and apoptosis. This is observed before TNF-R1 internalization and NF-κB activation. This process is repressed on TNF-R1 internalization. This signal however is enough to initiate apoptosis in some cells. Another form of cell death, necrosis, is also mediated through TNF stimulation. On TNF stimulation, deubiquitinated RIPK1 dissociates from complex 1 and recruits RIPK3, FADD and CASP8. RIPK3 is autophosphorylated and phosphorylates RIPK1. Taken together, it has been speculated that RIP1 and RIP3 increase carbohydrate and glutamine metabolism of the cell, leading to increased ROS production and eventual necrosis. Recruitment of CASP8, activation of FADD/RIP1 and apoptosis induction, is blunted when RIPK1 becomes ubiquitinated. IKBKG binds to ubiquitinated RIPK1 to induce the activation of NF-κB, which exerts antiapoptotic effects. Cellular inhibitor of apoptosis, BIRC2 and BIRC3 has E3-ubiquitin ligase activity and functionally interact with TRAF2 and RIPK1 to induce polyubiquitination of RIPK1 upon TNF stimulation. Loss of these inhibitors attenuates TNF-induced NF-κB activation. The adaptor proteins TAB2 and TAB3 bind preferentially to Lys-63 polyubiquitinated RIPK1. This facilitates dimerization of MAP3K7, promoting its phosphorylation and activation. The IKK complex, consisting of CHUK, IKBKB and IKBKG, is recruited to RIP1 through binding of IKBKG to the ubiquitin chain of RIP1. Activated TAK1 directly phosphorylates IKBKB within the activation loop, leading to activation of the IKK complex and NF-κB. Certain regulatory proteins have been known to intercept NF-κB activation at the level of ubiquitinated RIP1. TNFAIP3, an NF-κB inhibitory protein, removes Lys-63 polyubiquitin chain and promotes Lys-48 linked ubiquitination of RIPK1 leading to its degradation and NF-κB signal termination. IKBKG stabilizes the bound polyubiquitinated RIPK1 by inhibiting its degradation, most probably by impairing its interaction with TNFAIP3. OTUD7B is recruited to the activated TNF-R1 and promotes RIP1 deubiquitination, thereby attenuating NF-κB activation. At internalized TNF-receptosomes, RIPK1 is ubiquitinated by endocytic vesicle associated RFFL, inducing RIPK1 degradation, which terminates NF-κB activation. When successful, TNF-induced NF-κB activation induces transcription and expression of genes encoding proinflammatory IL-6, anti-apoptotic factors BIRC2, BIRC3 and BCL-2 homologue BCL2L1. This causes the cell to remain inert to apoptotic stimuli. Please access this pathway at [http://www.netpath.org/netslim/tnf_alpha_pathway.html NetSlim] database. Proteins on this pathway have targeted assays available via the [https://assays.cancer.gov/available_assays?wp_id=WP231 CPTAC Assay Portal]. SH3 domain of NOXO1 interacts with TRADD in mouse embryonic fibroblasts and 293 cells. Stimulation with TNF alpha induces the phosphorylation of CREB at Ser-133 in human vascular smooth muscle cells and in H5V cells. Stimulation with TNF-alpha induces the phosphorylation of IkappaBalpha at Ser-32 and ser-36 Stimulation with TNF-alpha induces the degradation of IkappaBalpha in mouse sertoli cells and mouse embryonic fibroblasts. Stimulation with TNF alpha induces the activation and phosphorylation of JNK Stimulation with TNF alpha induces the phosphorylation of RELA at Ser-536 in mouse epidermal JB6 cells. Stimulation with TNF-alpha induces the phosphorylation of AKT at ser-473 in human interstinal microvascular endothelial cells abd mouse embryonic fibroblasts. Stimulation with TNF alpha induces NIK phosphorylation at Thr-559 (NP_003945.2) in NCM460 cells. Stimulation with TNF-alpha induces the phosphorylation of ERK in human RASFs, endometrial stromal cells, dendritic cells, B16/F10.9 and 3T3-L1 adipocytes. Stimulation with TNF-alpha induces the phosphorylation of IKK-alpha in mouse embryonic fibroblasts. Stimulation of TNF-R1 with TNF alpha induces ubiquitination of RIP at Lys-377 in mouse embryonic fibroblasts and HEK293 cells. Stimulation with TNF alpha induces the activation and phosphorylation of JNK in human RASFs, HeLa, endometric stromal cells, HUVECs, dendritic cells and 3T3-L1 adipocytes. Stimulation with TNF-alpha induces c-Jun phosphorylation in HepG2 and colo201 and mouse sertoli cells. Stimulation with TNF alpha induces the phosphorylation of ERK in human RASFs, HeLa cells, eosinophils, endometriotic stromal tissue, 3T3-L1 cells and L929sA murine fibrosarcoma cells. Stimultion with TNF alpha induces the phosphorylation of MAP3K7 at Thr-187 in HeLa cells. Stimulation of TNF receptor 1 with TNF alpha induces the interaction of RIP with TRAF2 via its amino-terminal kinase domain and its central intermediate domain in 293 cells. Stimulation with TNF alpha also induces the ubiquitination of RIP at Lys-377 by TRAF2 in FLS and HEK293 cells. Stimulation of TNF-R1 with TNF alpha induces the phosphorylation of JNK by MKK7 and MKK4 at Thr-183 and Tyr-185 in mouse embryonic fibroblasts. Stimulation of TNF-R1 with TNF-alpha induces the interaction of phosphorylated RELA with CREBBP in HEK 293, COLO205, HCT116 and mouse embryonic fibroblast cells. Stimulation with TNF-alpha induces the interaction of TRADD with TRAFs and FADD and simultaneously recruit TRAFs and FADD to TNF-R1 in 293 cells. C-terminal domain of TRADD interacts with FADD. Stimulation with TNF-alpha induces the interaction of death domain of MADD with death domain of TNF-R1 in COS cells. Stimulation with TNF alpha induces the interaction of TNF-R1 with TRAP2 in HeLa cells. Stimulation with TNF-alpha induces the interaction of CDC37 with IKK complex in HeLa and HEK293 cells. Stimulation with TNF alpha induces the translocaton of NFKBs from cytoplasm to nucleus. Stimulation with TNF-R1 with TNF-alpha induces the interaction of TRAF2 with cIAPs in HeLa and U937 cells. cIAP is recruited to TNF-R1 through TRADD. TRAF2 bound cIAPs molecules are able to block activation of caspase-8. stimualtion of TNF-R1 with TNF-alpha induces the recruitment of CEZANNE to recruited to TNF-R1 in HEK293 cells. Bir3 domain of Smac-mimetic interacts with cIAP and induces cIAPs autoubiquitination and degradation leading to the release of RIPK1 from the activated TNF receptor complex to form a caspase-8-activating complex consisting of RIPK1, FADD, and caspase-8. caspase 3 and caspase 7 proteolytically cleaves IKK-beta at Asp-78, 242, 373 and 546 (NP_001547.1) in MCF-7 cells during TNF-alpha induces apoptosis. Stimulation of TNF-R1 with TNF-alpha induces the interaction and phosphorylation of RAF1 at Thr-268 and Thr-269 (NP_002871.1) by CAP-kinase in HL-60 cells. Stimulation with TNF alphai nduces the translocation of REL and RELA from cytoplasm to nucleus in 293 cells, COLO205 cells and intestinal microvascular endothelial cells (HIMEC), Human alveolar epitheliacells (HIMEC), Human alveolar epithelial A549 cells, RASFs, HUVECs and bovine endothelial cells as well as mouse embryonic fibroblasts. Stimulation with TNF-alpha induces the interaction of TAK1 with TRAF2 in HeLa cells. Stimulation with TNF alpha induces the phosphorylation of RELA at ser-536 by CHUK in HeLa cells. WD repeats of FAN interacts with N-SMase activating domain of TNF-R1 in 293 and COS-1 cells. This interaction induces the activation of nSMase. Stimulation with TNF-alpha induces the translocation of cytochrome C from mitochondria to cytoplasm. Stimulation with TNF-alpha induces the phosphorylation of RIP1 by RIP3 in mouse embryonic fibroblasts and 293T cells. Stimulation with TNF-alpha induces the interaction of RFK to TRAF1 death domain in HeLa cells. COOH-terminal SH3 domain of GRB2 to a PLAP motif within TNFR-I while its NH2 terminal SH3 domain interacts with SOS1/2 in CCL13 cells. Stimulation of TNF-R1 with TNF-alpha induces the interaction of Casper with FADD. Stimulation with TNF alpha induces the interaction of TRAP1 with TNF-R1. Stimulation of TNF-R1 with TNF-alpha induces the interaction of amino- and carboxy-termini of ASK1 with TRAFdomains of TRAF2 in 293 cells. Calcium controls activation of PLA2 which induce a series of events leading to necrotic cell death. Stimulation of TNF alpha results in the recruitment of RIP to the death domain of TNF-R1-bound TRADD via its carboxy-terminal death domain in HeLa S3 cells. Stimulation with TNF alpha enhances the activation of PYGL which mediated ROS production and necrosis. Stimulation with TNF-alpha results in the disassociation of deubiquitinated RIP1 from TRADD, RIP1, TRAF2, CIAPs complex and recruits RIP3, FADD and CASP8 to RIP1 in mouse embryonic fibroblasts. Recruited CEZANNE to TNF_R1 in response to TNF-alpha promotes deubiquitination of RIP and thereby attenuate NF-kappaB activation. BCL-XL prevents the binding of truncated BID to BAX. This is prevented by BAD. BAD can displace tBID from BCL-XL. Stimulation of TNF alpha induces the complex formation of SKP1, BTRC, FBXW11, Cullin-1 with NFKBIA. This complex ubiquitinates phosphorylated I kappa B alpha in HeLa-S3 cells. Activated CASP8 proteolytically cleaves RIP at Glu-324 and negatively regulates NF kappa B activation in HEK293 cells. Stimulation of TNF-R1 with TNF alpha induces the interaction of COOH-terminal 141 amino acids and PEST3 motif of GCK with amino terminal regulatory domain of MEKK1 in 293 and RAMOS cells. Stimulation with TNF alpha enhances the activation of GLULwhich mediated ROS production and necrosis. Stimulation of TNF alpha induces the interaction of TRADD with the death domain of TNF receptor 1 in 293 cells. Stimulation of TNF-R1 with TNF-alpha induces the interaction and phosphorylation of RELA by PKC delta at Ser-311 in mouse embryo fibroblasts and AKI cells. In presence of a apoptotic signal, the mitochondrial translocated cytochrome C interacts with WD-40 domains of APAF1. Stimulation of TNF-R1 with TNF-alpha induces the interaction of TANK with TBK1 in HEK293 cells. Stimulation with TNF alpha induces the phosphorylation of NFKBIB by CHUK Stimulation with TNF alpha induces the phosphorylation of NFKBIB at ser-19 and ser-23 by IKK beta in HEK293 cells. Stimulation with TNF-alpha induces the phosphorylation of IKK-2 at ser-177 and ser-181 by MEKK3 in mouse embryonic fibroblasts. RFK mediated activation of NOX1 interacts with NOXO1, TRADD, RIP1 and RAC1 and results in the production of ROS in 293 cells and mouse embryonic fibroblasts. Stimulation of TNF-R1 with TNF-alpha induces the interaction of A20 with NEMO in HEK293T cells. Anti-apoptotic BCL-XL prevents the binding of truncated BID to BAX. Stimulation of TNF-R1 with TNF-alpha induces the interaction of BH1 domain of BAX with BH-3 domain of BID. Stimulation of TNF-R2 with TNF alpha induces the ubiquitination of TRAF2 by cIAP1. The RING-domain-dependent ubiquitin protein ligase activity of cIAP1 is essential for the ubiquitination of TRAF2. Stimulation of TNF-R1 with TNF-alpha induces the interaction of NFKBIA with BTRC in HeLa and HEK293 cells. RIPK1 undergoes autophosphorylation at Ser-161 which is required for necrosis. Autophosphorylation of ASK1 in 293 cells. Stimualtion with TNF-alpha induces the autophosphorylation of RIP3 at Ser199 (NP_006862.2) regulates necrosis in Jurkat cells. tumor necrosis factor mediated signaling pathway PW:0000233 Pathway Ontology