Platelet factor 4

"PF4" redirects here. For SpaceShipTwo PF04, see 2014 Virgin Galactic crash. For USN Tacoma-class patrol frigate, see USS Sausalito (PF-4). For Philippine Navy frigate, see BRP Rajah Lakandula (PF-4). For JMSDF frigate, see JDS Momi (PF-4). For 1997 PF4, see 14967 Madrid. For 1999 PF4, see 38245 Marcospontes. For PF4 receptor, see PF4 receptor.

Platelet factor 4 (PF4) is a small cytokine belonging to the CXC chemokine family that is also known as chemokine (C-X-C motif) ligand 4 (CXCL4) . This chemokine is released from alpha-granules of activated platelets during platelet aggregation, and promotes blood coagulation by moderating the effects of heparin-like molecules. Due to these roles, it is predicted to play a role in wound repair and inflammation. It is usually found in a complex with proteoglycan.

PF4
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1RHP, 1DN3, 1F9Q, 1F9R, 1F9S, 1PFM, 1PFN, 4R9W, 4R9Y, 4RAU
Identifiers
Aliases	PF4, CXCL4, PF-4, SCYB4, platelet factor 4
External IDs	OMIM: 173460; MGI: 1888711; HomoloGene: 87791; GeneCards: PF4; OMA:PF4 - orthologs
Gene location (Human) Chr. Chromosome 4 (human) Band 4q13.3 Start 73,980,811 bp End 73,982,027 bp
Gene location (Mouse) Chr. Chromosome 5 (mouse) Band 5|5 E1 Start 90,920,294 bp End 90,921,242 bp
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in monocyte trabecular bone granulocyte blood gonad bone marrow testicle bone marrow cells periodontal fiber spleen Top expressed in tibiofemoral joint blood sciatic nerve stroma of bone marrow fetal liver hematopoietic progenitor cell dermis ankle vestibular sensory epithelium carotid body spleen More reference expression data BioGPS More reference expression data
Gene ontology Molecular function cytokine activity heparin binding CXCR3 chemokine receptor binding chemokine activity protein binding Cellular component extracellular region platelet alpha granule lumen extracellular space cytoplasm collagen-containing extracellular matrix Biological process cytokine-mediated signaling pathway chemokine-mediated signaling pathway positive regulation of macrophage differentiation platelet degranulation negative regulation of megakaryocyte differentiation positive regulation of cAMP-mediated signaling negative regulation of MHC class II biosynthetic process leukocyte chemotaxis chemotaxis response to lipopolysaccharide positive regulation of macrophage derived foam cell differentiation positive regulation of gene expression regulation of cell population proliferation immune response positive regulation of tumor necrosis factor production negative regulation of angiogenesis negative regulation of extrinsic apoptotic signaling pathway in absence of ligand inflammatory response positive regulation of transcription by RNA polymerase II negative regulation of cytolysis platelet activation defense response positive regulation of neutrophil chemotaxis antimicrobial humoral immune response mediated by antimicrobial peptide regulation of megakaryocyte differentiation regulation of signaling receptor activity G protein-coupled receptor signaling pathway adenylate cyclase-activating G protein-coupled receptor signaling pathway neutrophil chemotaxis cellular response to lipopolysaccharide Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 5196 56744 Ensembl ENSG00000163737 ENSMUSG00000029373 UniProt P02776 Q9Z126 RefSeq (mRNA) NM_002619 NM_001363352 NM_019932 RefSeq (protein) NP_002610 NP_001350281 NP_064316 Location (UCSC) Chr 4: 73.98 – 73.98 Mb Chr 5: 90.92 – 90.92 Mb PubMed search
Wikidata
View/Edit Human View/Edit Mouse

Genomics

The gene for human PF4 is located on human chromosome 4.

Function

Platelet factor-4 is a 70-amino acid protein that is released from the alpha-granules of activated platelets and binds with high affinity to heparin. Its major physiologic role appears to be neutralization of heparin-like molecules on the endothelial surface of blood vessels, thereby inhibiting local antithrombin activity and promoting coagulation. As a strong chemoattractant for neutrophils and fibroblasts, PF4 probably has a role in inflammation and wound repair.

PF4 is chemotactic for neutrophils, fibroblasts and monocytes, and interacts with a splice variant of the chemokine receptor CXCR3, known as CXCR3-B.

Clinical significance

The heparin:PF4 complex is the antigen in heparin-induced thrombocytopenia (HIT), an idiosyncratic autoimmune reaction to the administration of the anticoagulant heparin. PF4 autoantibodies have also been found in patients with thrombosis and features resembling HIT but no prior administration of heparin. Antibodies against PF4 have been implicated in cases of thrombosis and thrombocytopenia subsequent to vaccination with the Oxford–AstraZeneca or the Janssen COVID-19 vaccine. This phenomenon has been termed vaccine-induced immune thrombotic thrombocytopenia (VITT). Changes in the expression of PF4 have also been associated with symptoms of long COVID.

It is increased in patients with systemic sclerosis that also have interstitial lung disease.

The human platelet factor 4 kills malaria parasites within erythrocytes by selectively lysing the parasite's digestive vacuole.

See also

• Platelet-activating factor
• Platelet-derived growth factor

Further reading

• Bikfalvi A, Gimenez-Gallego G (February 2004). "The control of angiogenesis and tumor invasion by platelet factor-4 and platelet factor-4-derived molecules". Seminars in Thrombosis and Hemostasis. 30 (1): 137–44. doi:10.1055/s-2004-822978. PMID 15034805. S2CID 260320397.
• Maurer AM, Zhou B, Han ZC (December 2006). "Roles of platelet factor 4 in hematopoiesis and angiogenesis". Growth Factors. 24 (4): 242–52. doi:10.1080/08977190600988225. PMID 17381065. S2CID 36468865.
• Deuel TF, Keim PS, Farmer M, Heinrikson RL (June 1977). "Amino acid sequence of human platelet factor 4". Proceedings of the National Academy of Sciences of the United States of America. 74 (6): 2256–8. Bibcode:1977PNAS...74.2256D. doi:10.1073/pnas.74.6.2256. PMC 432148. PMID 267922.
• Walz DA, Wu VY, de Lamo R, Dene H, McCoy LE (December 1977). "Primary structure of human platelet factor 4". Thrombosis Research. 11 (6): 893–8. doi:10.1016/0049-3848(77)90117-7. PMID 601757.
• Nath N, Lowery CT, Niewiarowski S (April 1975). "Antigenic and antiheparin properties of human platelet factor 4 (PF4)". Blood. 45 (4): 537–50. doi:10.1182/blood.V45.4.537.537. PMID 803847.
• Hermodson M, Schmer G, Kurachi K (September 1977). "Isolation, crystallization, and primary amino acid sequence of human platelet factor 4". The Journal of Biological Chemistry. 252 (18): 6276–9. doi:10.1016/S0021-9258(17)39951-9. PMID 893407.
• Maione TE, Gray GS, Petro J, Hunt AJ, Donner AL, Bauer SI, et al. (January 1990). "Inhibition of angiogenesis by recombinant human platelet factor-4 and related peptides". Science. 247 (4938): 77–9. Bibcode:1990Sci...247...77M. doi:10.1126/science.1688470. PMID 1688470.
• Han ZC, Bellucci S, Tenza D, Caen JP (April 1990). "Negative regulation of human megakaryocytopoiesis by human platelet factor 4 and beta thromboglobulin: comparative analysis in bone marrow cultures from normal individuals and patients with essential thrombocythaemia and immune thrombocytopenic purpura". British Journal of Haematology. 74 (4): 395–401. doi:10.1111/j.1365-2141.1990.tb06325.x. PMID 2140694. S2CID 24529258.
• Poncz M, Surrey S, LaRocco P, Weiss MJ, Rappaport EF, Conway TM, Schwartz E (January 1987). "Cloning and characterization of platelet factor 4 cDNA derived from a human erythroleukemic cell line". Blood. 69 (1): 219–23. doi:10.1182/blood.V69.1.219.219. PMID 3098319.
• Griffin CA, Emanuel BS, LaRocco P, Schwartz E, Poncz M (1987). "Human platelet factor 4 gene is mapped to 4q12----q21". Cytogenetics and Cell Genetics. 45 (2): 67–9. doi:10.1159/000132431. PMID 3622011.
• Senior RM, Griffin GL, Huang JS, Walz DA, Deuel TF (February 1983). "Chemotactic activity of platelet alpha granule proteins for fibroblasts". The Journal of Cell Biology. 96 (2): 382–5. doi:10.1083/jcb.96.2.382. PMC 2112304. PMID 6187750.
• Morgan FJ, Begg GS, Chesterman CN (February 1980). "Complete covalent structure of human platelet factor 4". Thrombosis and Haemostasis. 42 (5): 1652–60. PMID 6445090.
• Deuel TF, Senior RM, Chang D, Griffin GL, Heinrikson RL, Kaiser ET (July 1981). "Platelet factor 4 is chemotactic for neutrophils and monocytes". Proceedings of the National Academy of Sciences of the United States of America. 78 (7): 4584–7. Bibcode:1981PNAS...78.4584D. doi:10.1073/pnas.78.7.4584. PMC 319837. PMID 6945600.
• Brown KJ, Parish CR (November 1994). "Histidine-rich glycoprotein and platelet factor 4 mask heparan sulfate proteoglycans recognized by acidic and basic fibroblast growth factor". Biochemistry. 33 (46): 13918–27. doi:10.1021/bi00250a047. PMID 7524669.
• Mayo KH, Roongta V, Ilyina E, Milius R, Barker S, Quinlan C, et al. (September 1995). "NMR solution structure of the 32-kDa platelet factor 4 ELR-motif N-terminal chimera: a symmetric tetramer". Biochemistry. 34 (36): 11399–409. doi:10.1021/bi00036a012. PMID 7547867.
• Barker S, Mayo KH (January 1995). "Quarternary structure amplification of protein folding differences observed in 'native' platelet factor-4". FEBS Letters. 357 (3): 301–4. Bibcode:1995FEBSL.357..301B. doi:10.1016/0014-5793(94)01384-D. PMID 7835432. S2CID 12222261.
• Zhang X, Chen L, Bancroft DP, Lai CK, Maione TE (July 1994). "Crystal structure of recombinant human platelet factor 4". Biochemistry. 33 (27): 8361–6. doi:10.1021/bi00193a025. PMID 8031770.
• Horne MK (April 1993). "The effect of secreted heparin-binding proteins on heparin binding to platelets". Thrombosis Research. 70 (1): 91–8. doi:10.1016/0049-3848(93)90226-E. PMID 8511754.
• Kolset SO, Mann DM, Uhlin-Hansen L, Winberg JO, Ruoslahti E (April 1996). "Serglycin-binding proteins in activated macrophages and platelets". Journal of Leukocyte Biology. 59 (4): 545–54. doi:10.1002/jlb.59.4.545. PMID 8613703. S2CID 23125881.

External links

• Platelet+factor+4 at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

This article incorporates text from the United States National Library of Medicine, which is in the public domain.