Mitogen-activated protein kinase kinase kinase 7 (MAP3K7), also known as TAK1, is an enzyme that in humans is encoded by the MAP3K7 gene. [3]
TAK1 is an evolutionarily conserved kinase in the MAP3 K family and clusters with the tyrosine-like and sterile kinase families. The protein structure of TAK1 contains an N (residues 1–104)- and C (residues 111–303)-terminus connected through the hinge region (Met 104-Ser 111). The ATP binding pocket is located in the hinge region of the kinase. Additionally, TAK1 has a catalytic lysine (Lys63) in the active site. Crystal structure of TAK1-ATP have shown that ATP forms two hydrogen bonds with residues Ala 107 and Glu 105. Further hydrogen bonding is observed to Asp 175, which is the leading residue of the DFG motif. This residue is thought to interact with Lys 63 through polar interactions and is catalytically important for phosphate transfer to substrate molecules. Critical for the TAK1-TAB1 complex is a helical loop around Phe 484, which provides extensive surface contact between the two proteins.
The protein encoded by this gene is a member of the serine/threonine protein kinase family. This kinase mediates signal transduction induced by TGF beta and morphogenetic protein (BMP), and controls a variety of cell functions including transcription regulation and apoptosis. TAK1 is a central regulator of cell death and is activated through a diverse set of intra- and extracellular stimuli. TAK1 regulates cell survival not solely through NF-κB but also through NF-κB-independent pathways such as oxidative stress and receptor-interacting protein kinase 1 (RIPK1) kinase activity-dependent pathway. [4] In response to IL-1, this protein forms a kinase complex including TRAF6, MAP3K7P1/TAB1 and MAP3K7P2/TAB2; this complex is required for the activation of nuclear factor kappa B. This kinase can also activate MAPK8/JNK, MAP2K4/MKK4, and thus plays a role in the cell response to environmental stresses. Four alternatively spliced transcript variants encoding distinct isoforms have been reported. [5] ]
In addition to IL-1 agonist activation, TAK1has been shown to be activated following TNF, TGFB, and LPS stimulation leading to the activation of pro-inflammatory pathways. Following TNF stimulation, TAK1 forms a ternary structure with TAB1 and TAB2/3 to form a fully activated TAK1 kinase. Following activation, TAK1 phosphorylates downstream effectors such as NFKB, p38 and cJUN leading the up-regulation of pro inflammatory pro survival genes.
This kinase has also been shown to regulate downstream cytokine expression such as TNF. Due to its regulation of TNF, TAK1 has become a novel target for the treatment of TNF mediated diseases such as auto immune disease ( Rheumatoid Arthritis, lupus, IBD) but also other cytokine mediated disorders such as chronic pain and cancer. [6] [7] With the advent of novel selective TAK1 inhibitors, groups have explored the therapeutic potential of TAK1 targeted therapies. One group has shown that the selective TAK1 inhibitor, Takinib developed at Duke University attenuated rheumatoid arthritis like pathology in the CIA mouse model of human inflammatory arthritis. [8] Furthermore, pharmacological inhibition of TAK1 has shown to reduce inflammatory cytokines in particular TNF. [9]
A rare mutation in TAK1 in humans has been reported. The mutation leads to gain of function, and hyper activation of TAK1 signaling pathways. Patients with gain of function mutations often present with craniofacial abnormalities.
MAP3K7 has been shown to interact with:
Signal transducing adaptor proteins (STAPs) are proteins that are accessory to main proteins in a signal transduction pathway. Adaptor proteins contain a variety of protein-binding modules that link protein-binding partners together and facilitate the creation of larger signaling complexes. These proteins tend to lack any intrinsic enzymatic activity themselves, instead mediating specific protein–protein interactions that drive the formation of protein complexes. Examples of adaptor proteins include MYD88, Grb2 and SHC1.
Receptor activator of nuclear factor κ B (RANK), also known as TRANCE receptor or TNFRSF11A, is a member of the tumor necrosis factor receptor (TNFR) molecular sub-family. RANK is the receptor for RANK-Ligand (RANKL) and part of the RANK/RANKL/OPG signaling pathway that regulates osteoclast differentiation and activation. It is associated with bone remodeling and repair, immune cell function, lymph node development, thermal regulation, and mammary gland development. Osteoprotegerin (OPG) is a decoy receptor for RANKL, and regulates the stimulation of the RANK signaling pathway by competing for RANKL. The cytoplasmic domain of RANK binds TRAFs 1, 2, 3, 5, and 6 which transmit signals to downstream targets such as NF-κB and JNK.
TRAF6 is a TRAF human protein.
TNF receptor-associated factor 2 is a protein that in humans is encoded by the TRAF2 gene.
Apoptosis signal-regulating kinase 1 (ASK1) also known as mitogen-activated protein kinase 5 (MAP3K5) is a member of MAP kinase family and as such a part of mitogen-activated protein kinase pathway. It activates c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases in a Raf-independent fashion in response to an array of stresses such as oxidative stress, endoplasmic reticulum stress and calcium influx. ASK1 has been found to be involved in cancer, diabetes, rheumatoid arthritis, cardiovascular and neurodegenerative diseases.
Mitogen-activated protein kinase 8 is a ubiquitous enzyme that in humans is encoded by the MAPK8 gene.
Inhibitor of nuclear factor kappa-B kinase subunit alpha (IKK-α) also known as IKK1 or conserved helix-loop-helix ubiquitous kinase (CHUK) is a protein kinase that in humans is encoded by the CHUK gene. IKK-α is part of the IκB kinase complex that plays an important role in regulating the NF-κB transcription factor. However, IKK-α has many additional cellular targets, and is thought to function independently of the NF-κB pathway to regulate epidermal differentiation.
TNF receptor-associated factor 1 is a protein that in humans is encoded by the TRAF1 gene.
Dual specificity mitogen-activated protein kinase kinase 6 also known as MAP kinase kinase 6 or MAPK/ERK kinase 6 is an enzyme that in humans is encoded by the MAP2K6 gene, on chromosome 17.
Interleukin-1 receptor-associated kinase 1 (IRAK-1) is an enzyme in humans encoded by the IRAK1 gene. IRAK-1 plays an important role in the regulation of the expression of inflammatory genes by immune cells, such as monocytes and macrophages, which in turn help the immune system in eliminating bacteria, viruses, and other pathogens. IRAK-1 is part of the IRAK family consisting of IRAK-1, IRAK-2, IRAK-3, and IRAK-4, and is activated by inflammatory molecules released by signaling pathways during pathogenic attack. IRAK-1 is classified as a kinase enzyme, which regulates pathways in both innate and adaptive immune systems.
Testicular receptor 4 also known as NR2C2 is a protein that in humans is encoded by the NR2C2 gene.
Mitogen-activated protein kinase kinase kinase 1 (MAP3K1) is a signal transduction enzyme that in humans is encoded by the autosomal MAP3K1 gene.
Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) functions in a variety of cellular pathways related to both cell survival and death. In terms of cell death, RIPK1 plays a role in apoptosis and necroptosis. Some of the cell survival pathways RIPK1 participates in include NF-κB, Akt, and JNK.
Mitogen-activated protein kinase kinase kinase 14 also known as NF-kappa-B-inducing kinase (NIK) is an enzyme that in humans is encoded by the MAP3K14 gene.
Inhibitor of nuclear factor kappa-B kinase subunit epsilon also known as I-kappa-B kinase epsilon or IKK-epsilon is an enzyme that in humans is encoded by the IKBKE gene.
Mitogen-activated protein kinase kinase kinase 7-interacting protein 2 is an enzyme that in humans is encoded by the MAP3K7IP2 gene.
Mitogen-activated protein kinase kinase kinase 7-interacting protein 1 is an enzyme that in humans is encoded by the TAB1 gene.
Mitogen-activated protein kinase kinase kinase 4 is an enzyme that in humans is encoded by the MAP3K4 gene.
Mitogen-activated protein kinase kinase kinase 7-interacting protein 3 is an enzyme that in humans is encoded by the MAP3K7IP3 gene.
The interleukin-1 receptor (IL-1R) associated kinase (IRAK) family plays a crucial role in the protective response to pathogens introduced into the human body by inducing acute inflammation followed by additional adaptive immune responses. IRAKs are essential components of the Interleukin-1 receptor signaling pathway and some Toll-like receptor signaling pathways. Toll-like receptors (TLRs) detect microorganisms by recognizing specific pathogen-associated molecular patterns (PAMPs) and IL-1R family members respond the interleukin-1 (IL-1) family cytokines. These receptors initiate an intracellular signaling cascade through adaptor proteins, primarily, MyD88. This is followed by the activation of IRAKs. TLRs and IL-1R members have a highly conserved amino acid sequence in their cytoplasmic domain called the Toll/Interleukin-1 (TIR) domain. The elicitation of different TLRs/IL-1Rs results in similar signaling cascades due to their homologous TIR motif leading to the activation of mitogen-activated protein kinases (MAPKs) and the IκB kinase (IKK) complex, which initiates a nuclear factor-κB (NF-κB) and AP-1-dependent transcriptional response of pro-inflammatory genes. Understanding the key players and their roles in the TLR/IL-1R pathway is important because the presence of mutations causing the abnormal regulation of Toll/IL-1R signaling leading to a variety of acute inflammatory and autoimmune diseases.