Fibroblast growth factor receptor

{{short description|Family of proteins that bind to fibroblast growth factors}}

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| Name = Fibroblast growth factor receptor

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The fibroblast growth factor receptors (FGFR) are, as their name implies, receptors that bind to members of the fibroblast growth factor (FGF) family of proteins. Some of these receptors are involved in pathological conditions. For example, a point mutation in FGFR3 can lead to achondroplasia.

Structure

The fibroblast growth factor receptors consist of an extracellular ligand domain composed of three immunoglobulin-like domains, a single transmembrane helix domain, and an intracellular domain with tyrosine kinase activity. These receptors bind fibroblast growth factors, members of the largest family of growth factor ligands, comprising 22 members.{{cite journal | vauthors = Ornitz DM, Itoh N | title = Fibroblast growth factors | journal = Genome Biology | volume = 2 | issue = 3 | pages = REVIEWS3005 | year = 2001 | pmid = 11276432 | pmc = 138918 | doi = 10.1186/gb-2001-2-3-reviews3005 | doi-access = free }}{{cite journal | vauthors = Belov AA, Mohammadi M | title = Molecular mechanisms of fibroblast growth factor signaling in physiology and pathology | journal = Cold Spring Harbor Perspectives in Biology | volume = 5 | issue = 6 | pages = a015958 | date = June 2013 | pmid = 23732477 | pmc = 3660835 | doi = 10.1101/cshperspect.a015958 }}

The natural alternate splicing of four fibroblast growth factor receptor (FGFR) genes results in the production of over 48 different isoforms of FGFR.{{cite journal | vauthors = Duchesne L, Tissot B, Rudd TR, Dell A, Fernig DG | title = N-glycosylation of fibroblast growth factor receptor 1 regulates ligand and heparan sulfate co-receptor binding | journal = The Journal of Biological Chemistry | volume = 281 | issue = 37 | pages = 27178–89 | date = September 2006 | pmid = 16829530 | doi = 10.1074/jbc.M601248200 | doi-access = free }} These isoforms vary in their ligand-binding properties and kinase domains, however all share the common extracellular region composed of three immunoglobulin(Ig)-like domains (D1-D3), and thus belong to the immunoglobulin superfamily.{{cite journal | vauthors = Coutts JC, Gallagher JT | title = Receptors for fibroblast growth factors | journal = Immunology and Cell Biology | volume = 73 | issue = 6 | pages = 584–9 | date = December 1995 | pmid = 8713482 | doi = 10.1038/icb.1995.92 }}

The three immunoglobin(Ig)-like domains—D1, D2, and D3—present a stretch of acidic amino acids ("the acid box") between D1 and D2.{{cite journal | vauthors = Kalinina J, Dutta K, Ilghari D, Beenken A, Goetz R, Eliseenkova AV, Cowburn D, Mohammadi M | display-authors = 6 | title = The alternatively spliced acid box region plays a key role in FGF receptor autoinhibition | journal = Structure | volume = 20 | issue = 1 | pages = 77–88 | date = January 2012 | pmid = 22244757 | pmc = 3378326 | doi = 10.1016/j.str.2011.10.022 }}

This "acid box" can participate in the regulation of FGF binding to the FGFR. Immunoglobulin-like domains D2 and D3 are sufficient for FGF binding. Each receptor can be activated by several FGFs. In many cases, the FGFs themselves can also activate more than one receptor (i.e., FGF1, which binds all seven principal FGFRs{{cite journal | vauthors = Ornitz DM, Xu J, Colvin JS, McEwen DG, MacArthur CA, Coulier F, Gao G, Goldfarb M | display-authors = 6 | title = Receptor specificity of the fibroblast growth factor family | journal = The Journal of Biological Chemistry | volume = 271 | issue = 25 | pages = 15292–7 | date = June 1996 | pmid = 8663044 | doi = 10.1074/jbc.271.25.15292 | doi-access =free }}). FGF7, however, can only activate FGFR2b, and FGF18 was recently shown to activate FGFR3.{{cite journal | vauthors = Davidson D, Blanc A, Filion D, Wang H, Plut P, Pfeffer G, Buschmann MD, Henderson JE | display-authors = 6 | title = Fibroblast growth factor (FGF) 18 signals through FGF receptor 3 to promote chondrogenesis | journal = The Journal of Biological Chemistry | volume = 280 | issue = 21 | pages = 20509–15 | date = May 2005 | pmid = 15781473 | doi = 10.1074/jbc.M410148200 | doi-access = free }}

A gene for a fifth FGFR protein, FGFR5, has also been identified. In contrast to FGFRs 1-4, it lacks a cytoplasmic tyrosine kinase domain and one isoform, FGFR5γ, and only contains the extracellular domains D1 and D2.{{cite journal | vauthors = Sleeman M, Fraser J, McDonald M, Yuan S, White D, Grandison P, Kumble K, Watson JD, Murison JG | display-authors = 6 | title = Identification of a new fibroblast growth factor receptor, FGFR5 | journal = Gene | volume = 271 | issue = 2 | pages = 171–82 | date = June 2001 | pmid = 11418238 | doi = 10.1016/S0378-1119(01)00518-2 }} The FGFRs are known to dimerize as heterodimers and homodimers.

Genes

So far, five distinct membrane FGFR have been identified in vertebrates and all of them belong to the tyrosine kinase superfamily (FGFR1 to FGFR4).

As a drug target

The FGF/FGFR signalling pathway is involved in a variety of cancers.{{cite journal | vauthors = Porta R, Borea R, Coelho A, Khan S, Araújo A, Reclusa P, Franchina T, Van Der Steen N, Van Dam P, Ferri J, Sirera R, Naing A, Hong D, Rolfo C | display-authors = 6 | title = FGFR a promising druggable target in cancer: Molecular biology and new drugs | journal = Critical Reviews in Oncology/Hematology | volume = 113 | pages = 256–267 | date = May 2017 | pmid = 28427515 | doi = 10.1016/j.critrevonc.2017.02.018 | hdl = 10447/238074 | url = https://iris.unipa.it/bitstream/10447/238074/1/1-s2.0-S1040842817300859-main.pdf | hdl-access = free }}

There are non-selective FGFR inhibitors that act on all of FGFR1-4 and other proteins, and some selective FGFR inhibitors for some/all of FGFR1-4.{{cite journal | vauthors = Chae YK, Ranganath K, Hammerman PS, Vaklavas C, Mohindra N, Kalyan A, Matsangou M, Costa R, Carneiro B, Villaflor VM, Cristofanilli M, Giles FJ | display-authors = 6 | title = Inhibition of the fibroblast growth factor receptor (FGFR) pathway: the current landscape and barriers to clinical application | journal = Oncotarget | volume = 8 | issue = 9 | pages = 16052–16074 | date = February 2017 | pmid = 28030802 | pmc = 5362545 | doi = 10.18632/oncotarget.14109 }} Selective FGFR inhibitors include AZD4547, BGJ398, JNJ42756493, and PD173074.

References

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