CCL17 gene

CCL17 (C-C motif chemokine ligand 17) is a protein-coding gene located on chromosome 16q21. Gene Ontology (GO) annotations associated with this gene include binding to signaling receptors and binding to the chemokine receptor CCR4. An important paralog of this gene is CCL22.

The encoded CCL17 chemokine (TARC) exhibits chemotactic activity for T lymphocytes, preferably Th2 cells, but not for monocytes or granulocytes. It is constitutively expressed in the thymus and inconstantly in stimulated peripheral blood mononuclear cells. TARC (CCL17) acts as a selective chemoattractant for T cells expressing a class of receptors that bind TARC with high affinity and specificity. TARC selectively binds to cells expressing CCR4.

TARC (CCL17) therefore plays an important role in a variety of inflammatory and immunological processes (Imai T et al. 1996; Imai T et al. 1997). The chemokine acts by binding to CCR4 on the surface of T cells. It mediates GM-CSF/CSF2-related pain and inflammation (Achuthan A et al. 2016). In the brain, TARC(CCL17) is required to maintain the typical, highly branched morphology of microglia in the hippocampus under homeostatic conditions.

Diseases associated with TARC (CCL17) include eosinophilic pneumonia and paragonimiasis. Associated signaling pathways include MIF-mediated glucocorticoid regulation and TGF-beta signaling pathway.

1. Achuthan A et al. (2016) Granulocyte macrophage colony-stimulating factor induces CCL17 production via IRF4 to mediate inflammation. J Clin Invest 126:3453-66.
2. Imai T et al. (1996) Molecular cloning of a novel T cell-directed CC chemokine expressed in thymus by signal sequence trap using Epstein-Barr virus vector. J Biol Chem271:21514-21521
3. Imai T et al. (1997) The T cell-directed CC chemokine TARC is a highly specific biological ligand for CC chemokine receptor 4. J Biol Chem 272:15036-42.