Chemokine receptor 6 also known as CCR6 is a CC chemokine receptor protein which in humans is encoded by the CCR6 gene. [5] CCR6 has also recently been designated CD196 (cluster of differentiation 196). The gene is located on the long arm of Chromosome 6 (6q27) on the Watson (plus) strand. It is 139,737 bases long and encodes a protein of 374 amino acids (molecular weight 42,494 Da). [5]
This protein belongs to family A of G protein-coupled receptor superfamily. The gene is expressed in lymphatic and non-lymphatic tissue as spleen, lymph nodes, pancreas, colon, appendix, small intestine. CCR6 is expressed on B-cells, immature dendritic cells (DC), T-cells (Th1, Th2, Th17, Treg), natural killer T cells (NKT cells) and neutrophils. [6] The ligand of this receptor is CCL20 or in the other name - macrophage inflammatory protein 3 alpha (MIP-3 alpha). This chemokine receptor is special because it binds only one chemokine ligand CCL20 in compare to other chemokine receptors. [7] CCR6 has a key role in connection between immature DC an adaptive immunity. [8] This receptor has been shown to be important for B-lineage maturation and antigen-driven B-cell differentiation, and it may regulate the migration and recruitment of dendritic cells and T cells during inflammatory and immunological responses. Alternatively spliced transcript variants that encode the same protein have been described for this gene. [9]
Interleukin 4 (IL-4) and interferon gamma (IFNγ) suppress expression of CCR6 in langerhans cells development and interleukin 10 (IL-10) induces the expression. It can regulate immune response in inflammatory tissue. [10]
Proinflammatory Th17 cells express CCR6 and its ligand CCL20. CCR6 influences their migration to sites of inflammation. Some Th17 cells migrate via chemokine gradient of CCL20 to inflammatory sites and themselves can express more CCL20 to bring in more Th17 cells and regulatory T-cells (Treg). This can lead to chronic inflammation. In some models, the lack of CCR6 leads to less severe autoimmune encephalomyelitis. [11]
CCR6 has a function in development and metastatic spread of gastrointestinal malignancies. [7] Expression of CCR6 was found to be up-regulated in colorectal cancer. [12] Many patients with colorectal cancer have liver metastases. Colorectal carcinoma cells express CCR6 and CCL20. High level of CCL20 in liver chemoattract colorectal carcinoma cells and cause metastases in liver. [7] [13] Novel research has identified a microRNA that is able to downregulate CCR6 in cancer cell lines. [14]
CCR6 has been associated with Crohn's disease. [15]
Macrophage Inflammatory Proteins (MIP) belong to the family of chemotactic cytokines known as chemokines. In humans, there are two major forms, MIP-1α and MIP-1β that are now officially named CCL3 and CCL4, respectively. However, other names can sometimes be encountered, especially in older literature, as LD78α, AT 464.1 and GOS19-1 for human CCL3 and AT 744, Act-2, LAG-1, HC21 and G-26 for human CCL4. Other macrophage inflammatory proteins include MIP-2, MIP-3 and MIP-5.
Chemokine ligands 4 previously known as macrophage inflammatory protein (MIP-1β), is a protein which in humans is encoded by the CCL4 gene. CCL4 belongs to a cluster of genes located on 17q11-q21 of the chromosomal region. Identification and localization of the gene on the chromosome 17 was in 1990 although the discovery of MIP-1 was initiated in 1988 with the purification of a protein doublet corresponding to inflammatory activity from supernatant of endotoxin-stimulated murine macrophages. At that time, it was also named as "macrophage inflammatory protein-1" (MIP-1) due to its inflammatory properties.
Chemokine ligand 1 (CCL1) is also known as small inducible cytokine A1 and I-309 in humans. CCL1 is a small glycoprotein that belongs to the CC chemokine family.
Chemokine ligand 7 (CCL7) is a small cytokine that was previously called monocyte-chemotactic protein 3 (MCP3). CCL7 is a small protein that belongs to the CC chemokine family and is most closely related to CCL2.
Chemokine ligand 8 (CCL8), also known as monocyte chemoattractant protein 2 (MCP2), is a protein that in humans is encoded by the CCL8 gene.
C-C motif chemokine 11 also known as eosinophil chemotactic protein and eotaxin-1 is a protein that in humans is encoded by the CCL11 gene. This gene is encoded on three exons and is located on chromosome 17.
Chemokine ligand 20 (CCL20) or liver activation regulated chemokine (LARC) or Macrophage Inflammatory Protein-3 (MIP3A) is a small cytokine belonging to the CC chemokine family. It is strongly chemotactic for lymphocytes and weakly attracts neutrophils. CCL20 is implicated in the formation and function of mucosal lymphoid tissues via chemoattraction of lymphocytes and dendritic cells towards the epithelial cells surrounding these tissues. CCL20 elicits its effects on its target cells by binding and activating the chemokine receptor CCR6.
Chemokine ligand 18 (CCL18) is a small cytokine belonging to the CC chemokine family. The functions of CCL18 have been well studied in laboratory settings, however the physiological effects of the molecule in living organisms have been difficult to characterize because there is no similar protein in rodents that can be studied. The receptor for CCL18 has been identified in humans only recently, which will help scientists understand the molecule's role in the body.
Chemokine ligand 21 (CCL21) is a small cytokine belonging to the CC chemokine family. This chemokine is also known as 6Ckine, exodus-2, and secondary lymphoid-tissue chemokine (SLC). CCL21 elicits its effects by binding to a cell surface chemokine receptor known as CCR7. The main function of CCL21 is to guide CCR7 expressing leukocytes to the secondary lymphoid organs, such as lymph nodes and Peyer´s patches.
C-C motif chemokine 22 is a protein that in humans is encoded by the CCL22 gene.
CCL17 is a powerful chemokine produced in the thymus and by antigen-presenting cells like dendritic cells, macrophages, and monocytes. CCL17 plays a complex role in cancer. It attracts T-regulatory cells allowing for some cancers to evade an immune response. However, in other cancers, such as melanoma, an increase in CCL17 is linked to an improved outcome. CCL17 has also been linked to autoimmune and allergic diseases.
Chemokine ligand 19 (CCL19) is a protein that in humans is encoded by the CCL19 gene.
CC chemokine receptors are integral membrane proteins that specifically bind and respond to cytokines of the CC chemokine family. They represent one subfamily of chemokine receptors, a large family of G protein-linked receptors that are known as seven transmembrane (7-TM) proteins since they span the cell membrane seven times. To date, ten true members of the CC chemokine receptor subfamily have been described. These are named CCR1 to CCR10 according to the IUIS/WHO Subcommittee on Chemokine Nomenclature.
Chemokine ligand 9 (CCL9) is a small cytokine belonging to the CC chemokine family. It is also called macrophage inflammatory protein-1 gamma (MIP-1γ), macrophage inflammatory protein-related protein-2 (MRP-2) and CCF18, that has been described in rodents. CCL9 has also been previously designated CCL10, although this name is no longer in use. It is secreted by follicle-associated epithelium (FAE) such as that found around Peyer's patches, and attracts dendritic cells that possess the cell surface molecule CD11b and the chemokine receptor CCR1. CCL9 can activate osteoclasts through its receptor CCR1 suggesting an important role for CCL9 in bone resorption. CCL9 is constitutively expressed in macrophages and myeloid cells. The gene for CCL9 is located on chromosome 11 in mice.
C-C chemokine receptor type 7 is a protein that in humans is encoded by the CCR7 gene. Two ligands have been identified for this receptor: the chemokines ligand 19 (CCL19/ELC) and ligand 21 (CCL21). The ligands have similar affinity for the receptor, though CCL19 has been shown to induce internalisation of CCR7 and desensitisation of the cell to CCL19/CCL21 signals. CCR7 is a transmembrane protein with 7 transmembrane domains, which is coupled with heterotrimeric G proteins, which transduce the signal downstream through various signalling cascades. The main function of the receptor is to guide immune cells to immune organs by detecting specific chemokines, which these tissues secrete.
C-C chemokine receptor type 1 is a protein that in humans is encoded by the CCR1 gene.
C-C chemokine receptor type 10 is a protein that in humans is encoded by the CCR10 gene.
C-C chemokine receptor type 9 is a protein that in humans is encoded by the CCR9 gene. This gene is mapped to the chemokine receptor gene cluster region. Two alternatively spliced transcript variants have been described.
C-C chemokine receptor type 11 is a protein that in humans is encoded by the CCRL1 gene.
Chemokine-binding protein 2 is a protein that in humans is encoded by the CCBP2 gene.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
 | This transmembrane receptor-related article is a stub. You can help Wikipedia by expanding it. |
