|
Background
|
Human CXCL-16, also known as Chemokine (C-X-C Motif) Ligand 16, is initially synthesized as a 254 amino acid precursor molecule with an initial 29 residue signal peptide followed by the actual 225 residue CXCL- 16 chain. CXCL-16 is encoded by the gene CXCL16, located at locus 17p13 on chromosome 17. After proteolytic cleavage events, the 29 residue signal sequence is removed and a mature CXCL-16 peptide is allowed to form. CXCL-16 is commonly known to act as a scavenger receptor on macrophages that specifically binds to oxidized low density lipoprotein (OxLDL), suggesting that it may be involved in pathophysiology such as atherogenesis. Structurally, the cytokine is composed of a C-X-C chemokine domain, a mucin-like stalk, a transmembrane domain, and a cytoplasmic tail containing a potential tyrosine phosphorylation site that may bind SH2. Moreover, these features allow for CXCL-16 to exist as cell surface molecule as well as a soluble chemokine. It is produced in dendritic cells located in the T-cell zones of lymphoid organs and by the red pulp of the spleen. CXCL-16 is also highly expressed in lymph nodes, the lungs, kidneys, small intestine and thymus while having weak expression in the heart and liver and no expression in the brain or bone marrow. Expression of the CXCL-16 cytokine is inducible by inflammatory cytokines, IFN-γ and TNF-α, which may further cause the chemotactic response of several types of T-cells and natural killer T-cells via its high affinity interaction with chemokine receptor CXCR6 or Bonzo. Source: Entrez Gene: CXCL16 chemokine c-x-c motif Ligand 16 [Homo sapiens], Swiss-Prot: Q9H2A7, Matloubian M, David A, Engel S, Ryan J, Cyster J (2000). "A transmembrane CXC chemokine is a ligand for HIV- coreceptor Bonzo". Nat Immunol 1 (4): 298-304., Abel S, Hundhausen C, Mentlein R, Schulte A, Berkhout T, Broadway N, Hartmann D, Sedlacek R, Dietrich S, Muetze B, Schuster B, Kallen K, Saftig P, Rose-John S, Ludwig A (2004). "The transmembrane CXC-chemokine ligand 16 is induced by IFN-gamma and TNF-alpha and shed by the activity of the disintegrin-like metalloproteinase ADAM10". J Immunol 172 (10): 6362-72.
|