CD14

CD14 molecule
Rendering based on PDB 1WWL​.
Available structures PDB Ortholog search: PDBe, RCSB List of PDB id codes 4GLP​
Identifiers
Symbol	CD14
External IDs	OMIM: 158120 MGI: 88318 HomoloGene: 493 GeneCards: CD14 Gene
Gene ontology Molecular function • lipopolysaccharide binding • opsonin receptor activity • protein binding • peptidoglycan receptor activity • lipoteichoic acid binding Cellular component • extracellular region • extracellular space • plasma membrane • cell surface • endosome membrane • anchored component of membrane • membrane raft • extracellular exosome Biological process • toll-like receptor signaling pathway • MyD88-dependent toll-like receptor signaling pathway • MyD88-independent toll-like receptor signaling pathway • receptor-mediated endocytosis • phagocytosis • apoptotic process • inflammatory response • cell surface receptor signaling pathway • I-kappaB kinase/NF-kappaB signaling • response to heat • programmed cell death • response to magnesium ion • positive regulation of type I interferon production • positive regulation of tumor necrosis factor production • toll-like receptor 2 signaling pathway • toll-like receptor 3 signaling pathway • toll-like receptor 4 signaling pathway • response to tumor necrosis factor • TRIF-dependent toll-like receptor signaling pathway • toll-like receptor TLR1:TLR2 signaling pathway • toll-like receptor TLR6:TLR2 signaling pathway • innate immune response • response to ethanol • positive regulation of endocytosis • positive regulation of cytokine secretion • response to electrical stimulus • cellular response to lipopolysaccharide • cellular response to lipoteichoic acid • extrinsic apoptotic signaling pathway • activation of cysteine-type endopeptidase activity involved in apoptotic signaling pathway Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	929	12475
Ensembl	ENSG00000170458	ENSMUSG00000051439
UniProt	P08571	P10810
RefSeq (mRNA)	NM_000591	NM_009841
RefSeq (protein)	NP_000582	NP_033971
Location (UCSC)	Chr 5: 140.63 – 140.63 Mb	Chr 18: 36.73 – 36.73 Mb
PubMed search

CD14 (cluster of differentiation 14), also known as CD14, is a human gene.^[1][2]

The protein encoded by this gene is a component of the innate immune system. CD14 exists in two forms, one anchored to the membrane by a glycosylphosphatidylinositol tail (mCD14), the other a soluble form (sCD14). Soluble CD14 either appears after shedding of mCD14 (48 kDa) or is directly secreted from intracellular vesicles (56 kDa).^[3]

The x-ray crystal structure of human CD14 (4GLP.pdb) reveals a monomeric, bent solenoid structure containing a hydrophobic amino-terminal pocket.^[4]

CD14 was the first described pattern recognition receptor.

Function

CD14 acts as a co-receptor (along with the Toll-like receptor TLR 4 and MD-2) for the detection of bacterial lipopolysaccharide (LPS).^[5][6] CD14 can bind LPS only in the presence of lipopolysaccharide-binding protein (LBP). Although LPS is considered its main ligand, CD14 also recognizes other pathogen-associated molecular patterns such as lipoteichoic acid.^[7]

Signaling pathway of toll-like receptors. Dashed grey lines represent unknown associations

Tissue distribution

CD14 is expressed mainly by macrophages and (at 10-times lesser extent) by neutrophils. It is also expressed by dendritic cells. The soluble form of the receptor (sCD14) is secreted by the liver and monocytes and is sufficient in low concentrations to confer LPS-responsiveness to cells not expressing CD14. mCD14 and sCD14 are also present on enterocytes.^[8] sCD14 is also present in human milk, where it is believed to regulate microbial growth in the infant gut.

Differentiation

CD14+ monocytes can differentiate into a host of different cells, including dendritic cells, a differentiation pathway encouraged by cytokines, including GM-CSF and IL-4.

Interactions

CD14 has been shown to interact with lipopolysaccharide-binding protein.^[9][10]

References

1. Setoguchi M, Nasu N, Yoshida S, Higuchi Y, Akizuki S, Yamamoto S (July 1989). "Mouse and human CD14 (myeloid cell-specific leucine-rich glycoprotein) primary structure deduced from cDNA clones". Biochim. Biophys. Acta 1008 (2): 213–22. doi:10.1016/0167-4781(80)90012-3. PMID 2472171.
2. Simmons DL, Tan S, Tenen DG, Nicholson-Weller A, Seed B (1 January 1989). "Monocyte antigen CD14 is a phospholipid anchored membrane protein". Blood 73 (1): 284–9. PMID 2462937.
3. Kirkland TN, Viriyakosol S (1998). "Structure-function analysis of soluble and membrane-bound CD14". Prog. Clin. Biol. Res. 397: 79–87. PMID 9575549.
4. Kelley SL, Lukk T, Nair SK, Tapping, RI (2013). "The Crystal Structure of Human Soluble CD14 Reveals a Bent Solenoid with a Hydrophobic Amino-Terminal Pocket". Journal of Immunology 190 (3): 1304–1311. doi:10.4049/jimmunol.1202446. PMID 23264655.
5. Kitchens RL (2000). "Role of CD14 in cellular recognition of bacterial lipopolysaccharides". Chem. Immunol. Chemical Immunology and Allergy 74: 61–82. doi:10.1159/000058750. ISBN 3-8055-6917-3. PMID 10608082.
6. Tapping RI, Tobias PS (2000). "Soluble CD14-mediated cellular responses to lipopolysaccharide". Chem. Immunol. Chemical Immunology and Allergy 74: 108–21. doi:10.1159/000058751. ISBN 3-8055-6917-3. PMID 10608084.
7. Ranoa DR, Kelley SL, Tapping RI (2013). "Human LBP and CD14 independently deliver triacylated lipoproteins to TLR1 and TLR2 and enhance formation of the ternary signaling complex.". J. Biol. Chem. 74: 9729–41. doi:10.1074/jbc.M113.453266. PMID 23430250.
8. "CD14 Is Expressed and Released as Soluble CD14 by Human Intestinal Epithelial Cells In Vitro: Lipopolysaccharide Activation of Epithelial Cells Revisited".
9. Thomas, Celestine J; Kapoor Mili; Sharma Shilpi; Bausinger Huguette; Zyilan Umit; Lipsker Dan; Hanau Daniel; Surolia Avadhesha (November 2002). "Evidence of a trimolecular complex involving LPS, LPS binding protein and soluble CD14 as an effector of LPS response". FEBS Lett. (Netherlands) 531 (2): 184–8. doi:10.1016/S0014-5793(02)03499-3. ISSN 0014-5793. PMID 12417309.
10. Yu, B; Wright S D (1995). "LPS-dependent interaction of Mac-2-binding protein with immobilized CD14". J. Inflamm. (UNITED STATES) 45 (2): 115–25. ISSN 1078-7852. PMID 7583357.

External links

• CD14 Antigens at the US National Library of Medicine Medical Subject Headings (MeSH)