Ccl12

Chemokines, a subgroup of cytokines, are small (size between 8 and 10 kDa), chemotactically active proteins (signal proteins). They are common in all vertebrates, some virus types and bacteria. In humans, about 50 chemokines are currently known. A strongly conserved structural feature of all chemokines is a fixed group of cysteine residues that is stabilized by 1 or 2 disulfide bridges. This key structural position in the molecule is responsible for its fixed 3-dimensional structure.

In the CC chemokines, the cysteines follow each other directly (see figure), in the CXC chemokines they are separated (CC = acronym for cysteine-cysteine) by 1, in the CXXXC chemokines by 3 other amino acids. Chemokines are produced and secreted by a large number of immune cells. They transmit their signals by binding to chemokine receptors via G-proteins. Some chemokines have a pro-inflammatory effect, others have a regulatory effect on the formation, homeostasis and proliferation of tissues.

CCL12, also known as C-C motif chemokine 12 or MCP-1-related chemokine, is a murine (previously only detectable in rats and mice) protein from the group of chemokines. Its role in humans is unclear.

CCL12 is a ligand for the chemokine receptor CCR2. Under physiological conditions CCL12 is expressed predominantly in lymph nodes and thymus and is chemoattractive for eosinophil (but not for neutrophil granulocytes) granulocytes, monocytes/macrophages and lymphocytes. Its involvement in allergic reactions and in the defence against pathogens has been demonstrated in animal experiments. In malignant melanoma, the cytokine (as well as CCL8) seems to play a role in the invasiveness of tumor cells.

1. Barbai T et al (2015)The importance ofmicroenvironment: the role of CCL8 in metastasis formation of melanoma. Oncotarget 6:29111-29128.
2. Moore BB et al.(2006) The role of CCL12 in the recruitment of fibrocytes and lung fibrosis. At J Respir Cell Mol Biol 35:175-181.
3. Tsui P eg al (2007) Generation, characterization and biological activity of CCL2 (MCP-1/JE) and CCL12 (MCP-5) specific antibodies. Hum Antibodies 16:117-125.