TNF-R1, IL1RAP, IRAKM, TRAF2, SITPEC (ECSIT), Ubiquitin, IL-1RI, IKK-beta, I-kB, LTBR(TNFRSF3), SUMO-1, IRAK1/2, CD28, NF-kB p52/RelB, TNF-alpha, TNF-beta, NF-kB2 (p100), LBP, MD-2, CD14, IL-1 alpha, TLR4, MyD88, TCR alpha/beta, TOLLIP, RIPK2, TRADD, AKT(PKB), TRAF6, IKK (cat), IKAP, PKC-theta, IKK-alpha, LPS, NIK(MAP3K14), NF-kB, MEKK1(MAP3K1), IKK-gamma
NF-kB signaling pathway
The Nuclear factor kappa B ( NF-kB ) plays a crucial role in immune and inflammatory responses through the regulation of genes encoding pro-inflammatory cytokines, adhesion molecules, chemokines, growth factors and inducible enzymes. Transcription factors of the NF-kB family are activated in response to signals that lead to cell growth, differentiation, apoptosis and other events. NF-kB is activated by signals that activate Nuclear factor NF-kappa-B inhibitor kinase ( IKK ) resulting in the phosphorylation of Nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor ( I-kB ), this targets I-kB for degradation in the proteasome and frees the NF-kB dimer, which then translocates to the nucleus and activates target genes .
Tumor necrosis factor ( TNF-alpha ) activates NF-kB via canonical phosphorylation of IKK mediated by TNFRSF1A-associated via death domain ( TRADD )/ TNF receptor-associated factor 2 ( TRAF2 )/ Mitogen-activated protein kinase kinase kinase 14 ( NIK(MAP3K14) ) . The non-canonical pathway of NF-kB activation is utilized in response to the ligation of only certain TNF receptor superfamily members, for example Lymphotoxin beta receptor ( LTBR(TNFRSF3) ). In the non-canonical pathway, TRAF stimulates NIK, which subsequently activates IKK-alpha by phosphorylation. IKK-alpha promotes the processing of nuclear factor of kappa light polypeptide gene enhancer in B-cells 2 ( NF-kB2 (p100) ) from p100 to p52 form. Further processed NF-kB2 is bound to V-rel reticuloendotheliosis viral oncogene homolog B ( RelB ). NF-kB p52/RelB dimer is translocated into the nucleus to affect gene transcription. The non-canonical pathway is independent on IKK-beta and IKK-gamma , .
T cell receptor ( TCR ) and CD28 molecule ( CD28 ) can stimulate NF-KB via Protein kinase C theta ( PKC-theta )-dependent pathway , , . Also CD28 triggers V-akt murine thymoma viral oncogene homolog 1 ( AKT )-mediated pathway .
Upon binding of Interleukin 1 ( IL-1 ), the Interleukin 1 receptor type I ( IL-1RI ) associates with Interleukin 1 receptor accessory protein ( IL1RAP ), forming a functional signaling receptor complex that recruits myeloid differentiation primary response gene 88 ( MyD88 ). This leads to the translocation into this complex of Interleukin-1 receptor-associated kinase ( IRAK1/2 ) together with Toll interacting protein ( TOLLIP ). IRAK1 binds TNF receptor-associated factor 6 ( TRAF6 ). After dissociation from the receptor complex, IRAK1/ TRAF6 induces NIK or Mitogen-activated protein kinase kinase kinase 1 ( MEKK1(MAP3K1) )-dependent phosphorylation of IKK .
Lipopolysacccharide ( LPS ) in complex with Lipopolysaccharide binding protein ( LBP ) binds CD14 molecule ( CD14 ) on the cell membrane. It transfers LPS to lymphocyte antigen 96 ( MD- 2 ) and Toll-like receptor 4 ( TLR4 ). TLR4 via binding MyD88  and/or possibly Receptor-interacting serine-threonine kinase 2 ( RIPK2 ) induces NF-kB -activating cascade .