IL17RD | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | IL17RD , HH18, IL-17RD, IL17RLM, SEF, interleukin 17 receptor D | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 606807 MGI: 2159727 HomoloGene: 9717 GeneCards: IL17RD | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Interleukin 17 receptor D (also known as Sef) is a protein that in humans is encoded by the IL17RD gene. [5]
This gene encodes a membrane protein belonging to the interleukin-17 receptor (IL-17R) protein family. Alternate splicing generates multiple transcript variants encoding distinct isoforms. IL-17RD has been described to limit fibroblast growth factor receptor (FGFR) signaling and to be a part of the IL-17 receptor signaling complex.
IL-17RD was initially discovered during a large-scale in situ hybridization screen for genes regulating zebrafish embryogenesis. It was identified as a part of a synexpression group (genes with similar spatio-temporal expression) with negative regulators of fibroblast growth factor (FGF) and termed Sef (similar expression to FGF genes). The name was later changed to IL-17RD due to its sequence similarity to other IL-17 receptors. It was further determined that IL-17RD co-immunoprecipitates with FGF receptor (FGFR) and inhibits FGF signaling at the level of signal transduction and not by interfering with the ligand or its binding to FGFR. [6] [7]
IL-17RD is a type I transmembrane protein containing extracellular Ig-like domain followed by a fibronectin type III domain, a short transmembrane domain of ~20 amino acids, and an intracellular SEFIR domain which was identified in IL-17 receptors and some soluble factors involved in IL-17 signaling. [8] The SEFIR domain contains a region with sequence similarity to the TIR domain, which is characteristic of Toll-like receptors (TLRs), receptors of the interleukin 1 family, and adaptor proteins involved in the signaling pathways of these receptors. The regions within SEFIR that can be found in the TIR domain include box 1 and box 2. [9]
IL-17RD (Sef) was identified as part of a group of genes involved in FGF signaling in zebrafish and Xenopus laevis embryo. Injection of 1-cell stage embryo with sef mRNA lead to ventralization of the embryo, a similar effect observed after injection with XFD (a dominant negative of FGF receptor), suggesting its function as a negative regulator of FGF receptor signaling. Co-immunoprecipitation assay revealed that the intracellular part, but not the SEFIR domain, is critical for IL-17RD association with FGFR. [6] One of the pathways activated by stimulation of FGFR is Ras/MAPK (the rest being PI3/AKT and PLCγ). Injection of embryos with high amounts of Ras, Raf or MEK causes cell cycle arrest, which can be rescued by co-injection of IL-17RD, further supporting the role of IL-17RD in negative regulation of FGFR signaling. Moreover, IL-17RD appears to regulate FGF signaling at the level of downstream signaling, not the receptor, since overexpression of FGF or FGFR does not cause cell cycle arrest. [7] Taken together IL-17RD seems to negatively regulate FGFR signaling by limiting MAPK signaling via its intracellular domain.
The IL-17 receptor family belongs to a group of structurally similar receptors with a distinctive SEFIR (Sef and IL-17R) domain. [9] The founding member, IL-17RA, along with IL-17RC serve as a receptor complex for IL-17. IL-17 is a proinflammatory cytokine mainly produced by Th17 subset of T cells and plays an important role in extracellular pathogen elimination as well as several autoinflammatory diseases (such as psoriasis or rheumatoid arthritis). [10] IL-17RD has been reported to associate and co-localize with IL-17RA, mediate IL-17 signaling, and interact with TRAF6 (an IL-17 downstream molecule). Moreover, deletion of IL-17RD intracellular domain has a dominant negative effect and suppresses IL-17 signaling. In contrast, deletion of extracellular domain had no effect on IL-17 signaling. [11] However, full-body IL-17RD knockout mice do not present with any apparent phenotype. [12] This might be accounted for by the presence of IL-17RC which to an extent substitutes IL-17RD. It is important to note, however, that IL-17RC or IL-17RD deletion fails to protect against imiquimod-induced psoriasis. [13]
Since the SEFIR domain contains a TIR domain, the possible role of IL-17RD in TLR signaling was investigated. One study discovered that IL-17RD interacts with TIR adaptor proteins (such as MyD88, Mal, and TRIF) following TLR stimulation. Additionally, this interaction was abolished in IL-17RD which lacks the SEFIR domain. The study concluded that IL-17RD targets TLR-induced pro-inflammatory pathways and inhibits signaling upstream of NF-κB and IRF3. [14]
One study reported that TNF induces IL-17RD expression, which then serves as a feedback loop inhibiting the activation of TNF-activated NF-κB. [15] Another study focusing on renal cells describes IL-17RD to associate with TNFR2, but not TNFR1, to augment NF-κB activation. [16] The contrasting results suggest different roles of IL-17RD in various tissues.
Fibroblast growth factors (FGF) are a family of cell signalling proteins produced by macrophages; they are involved in a wide variety of processes, most notably as crucial elements for normal development in animal cells. Any irregularities in their function lead to a range of developmental defects. These growth factors typically act as systemic or locally circulating molecules of extracellular origin that activate cell surface receptors. A defining property of FGFs is that they bind to heparin and to heparan sulfate. Thus, some are sequestered in the extracellular matrix of tissues that contains heparan sulfate proteoglycans and are released locally upon injury or tissue remodeling.
IRAK-4, in the IRAK family, is a protein kinase involved in signaling innate immune responses from Toll-like receptors. It also supports signaling from T-cell receptors. IRAK4 contains domain structures which are similar to those of IRAK1, IRAK2, IRAKM and Pelle. IRAK4 is unique compared to IRAK1, IRAK2 and IRAKM in that it functions upstream of the other IRAKs, but is more similar to Pelle in this trait. IRAK4 has important clinical applications.
The fibroblast growth factor receptors (FGFR) are, as their name implies, receptors that bind to members of the fibroblast growth factor (FGF) family of proteins. Some of these receptors are involved in pathological conditions. For example, a point mutation in FGFR3 can lead to achondroplasia.
Myeloid differentiation primary response 88 (MYD88) is a protein that, in humans, is encoded by the MYD88 gene. originally discovered in the laboratory of Dan A. Liebermann as a Myeloid differentiation primary response gene.
TIR domain containing adaptor molecule 1 is an adapter in responding to activation of toll-like receptors (TLRs). It mediates the rather delayed cascade of two TLR-associated signaling cascades, where the other one is dependent upon a MyD88 adapter.
Toll-like receptor 4 (TLR4) is a transmembrane protein of approximately 95 kDa that is encoded by the TLR4 gene. TLR4 is also designated as CD284.
Fibroblast growth factor receptor 1 (FGFR1), also known as basic fibroblast growth factor receptor 1, fms-related tyrosine kinase-2 / Pfeiffer syndrome, and CD331, is a receptor tyrosine kinase whose ligands are specific members of the fibroblast growth factor family. FGFR1 has been shown to be associated with Pfeiffer syndrome, and clonal eosinophilias.
TRAF6 is a TRAF human protein.
Toll-like receptor 6 is a protein that in humans is encoded by the TLR6 gene. TLR6 is a transmembrane protein, member of toll-like receptor family, which belongs to the pattern recognition receptor (PRR) family. TLR6 acts in a heterodimer form with toll-like receptor 2 (TLR2). Its ligands include multiple diacyl lipopeptides derived from gram-positive bacteria and mycoplasma and several fungal cell wall saccharides. After dimerizing with TLR2, the NF-κB intracellular signalling pathway is activated, leading to a pro-inflammatory cytokine production and activation of innate immune response. TLR6 has also been designated as CD286.
Fibroblast growth factor receptor 4 is a protein that in humans is encoded by the FGFR4 gene. FGFR4 has also been designated as CD334.
Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) is a protein receptor that in humans is encoded by the NOD1 gene. It recognizes bacterial molecules and stimulates an immune reaction.
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.
Single Ig IL-1-related receptor (SIGIRR), also called Toll/Interleukin-1 receptor 8 (TIR8) or Interleukin-1 receptor 8 (IL-1R8), is transmembrane protein encoded by gene SIGIRR, which modulate inflammation, immune response, and tumorigenesis of colonic epithelial cells.
Interleukin-17 receptor (IL-17R) is a cytokine receptor which belongs to new subfamily of receptors binding proinflammatory cytokine interleukin 17A, a member of IL-17 family ligands produced by T helper 17 cells (Th17). IL-17R family consists of 5 members: IL-17RA, IL-17RB, IL-17RC, IL-17RD and IL-17RE. Functional IL-17R is a transmembrane receptor complex usually consisting of one IL-17RA, which is a founding member of the family, and second other family subunit, thus forming heteromeric receptor binding different ligands. IL-17A, a founding member of IL-17 ligand family binds to heteromeric IL-17RA/RC receptor complex. IL-17RB binds preferentially IL-17B and IL-17E and heteromeric IL-17RA/RE complex binds IL-17C. However, there is still unknown ligand for IL-17RD. The first identified member IL-17RA is located on human chromosome 22, whereas other subunits IL-17RB to IL-17RD are encoded within human chromosome 3.
The toll-interleukin-1 receptor (TIR) homology domain is an intracellular signaling domain found in MyD88, SARM1, interleukin-1 receptors, toll receptors and many plant R proteins. It contains three highly conserved regions, and mediates protein-protein interactions between the toll-like receptors (TLRs) and signal-transduction components. TIR-like motifs are also found in plant proteins where they are involved in resistance to disease and in bacteria where they are associated with virulence. When activated, TIR domains recruit cytoplasmic adaptor proteins MyD88 (UniProt Q99836) and TOLLIP (toll-interacting protein, UniProt Q9H0E2). In turn, these associate with various kinases to set off signaling cascades. Some TIR domains have also been found to have intrinsic NAD+ cleavage activity, such as in SARM1. In the case of SARM1, the TIR NADase activity leads to the production of Nam, ADPR and cADPR and the activation of downstream pathways involved in Wallerian degeneration and neuron death.
The Interleukin-1 family is a group of 11 cytokines that plays a central role in the regulation of immune and inflammatory responses to infections or sterile insults.
Members of the very wide interleukin-1 receptor (IL-1R) family are characterized by extracellular immunoglobulin-like domains and intracellular Toll/Interleukin-1R (TIR) domain. It is a group of structurally homologous proteins, conserved throughout the species as it was identified from plants to mammals. Proteins of this family play important role in host defence, injury and stress. There are four main groups of TIR domain-containing proteins in animals; Toll-like receptors, Interleukin-1 receptor (IL-1R), cytosolic adaptor proteins and insect and nematode Toll. Each of these groups is involved mainly in host defence; Toll receptors are also involved in embryogenesis.
Nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, delta also known as IκBNS is a protein in humans that is encoded by the NFKBID 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.
Interleukin 17F (IL-17F) is signaling protein that is in human is encoded by the IL17F gene and is considered a pro-inflammatory cytokine. This protein belongs to the interleukin 17 family and is mainly produced by the T helper 17 cells after their stimulation with interleukin 23. However, IL-17F can be also produced by a wide range of cell types, including innate immune cells and epithelial cells.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.