Fibroblast growth factors (FGFs) [, ]are a family of multifunctional proteins, often referred to as 'promiscuous growth factors' due to their diverse actions on multiple cell types [, ]. FGFs are mitogens, which stimulate growth or differentiation of cells of mesodermal or neuroectodermal origin. The function of FGFs in developmental processes include mesoderm induction, anterior-posterior patterning, limb development, and neural induction and development. In mature tissues, they are involved in diverse processes including keratinocyte organisation and wound healing [, , , , , ]. FGF involvement is critical during normal development of both vertebrates and invertebrates, and irregularities in their function leads to a range of developmental defects [, , , ]. Fibroblast growth factors are heparin-binding proteins and interactions with cell-surface-associated heparan sulfate proteoglycans have been shown to be essential for FGF signal transduction. FGFs have internal pseudo-threefold symmetry (β-trefoil topology) []. There are currently over 20 different FGF family members that have been identified in mammals, all of which are structurally related signaling molecules [, ]. They exert their effects through four distinct membrane fibroblast growth factor receptors (FGFRs), FGFR1 to FGFR4 [], which belong to the tyrosine kinase superfamily. Upon binding to FGF, the receptors dimerize and their intracellular tyrosine kinase domains become active [].This entry represents fibroblast growth factor 18 (FGF18), also referred to ZFGF5. FGF18 is required for normal ossification and bone development and stimulates hepatic and intestinal proliferation [, , , ].
Fibroblast growth factors (FGFs) [, ]are a family of multifunctional proteins, often referred to as 'promiscuous growth factors' due to their diverse actions on multiple cell types [, ]. FGFs are mitogens, which stimulate growth or differentiation of cells of mesodermal or neuroectodermal origin. The function of FGFs in developmental processes include mesoderm induction, anterior-posterior patterning, limb development, and neural induction and development. In mature tissues, they are involved in diverse processes including keratinocyte organisation and wound healing [, , , , , ]. FGF involvement is critical during normal development of both vertebrates and invertebrates, and irregularities in their function leads to a range of developmental defects [, , , ]. Fibroblast growth factors are heparin-binding proteins and interactions with cell-surface-associated heparan sulfate proteoglycans have been shown to be essential for FGF signal transduction. FGFs have internal pseudo-threefold symmetry (β-trefoil topology) []. There are currently over 20 different FGF family members that have been identified in mammals, all of which are structurally related signaling molecules [, ]. They exert their effects through four distinct membrane fibroblast growth factor receptors (FGFRs), FGFR1 to FGFR4 [], which belong to the tyrosine kinase superfamily. Upon binding to FGF, the receptors dimerize and their intracellular tyrosine kinase domains become active [].The FGFRs consist of an extracellular ligand-binding domain composed of three immunoglobulin-like domains (D1-D3), a single transmembrane helix domain, and an intracellular domain with tyrosine kinase activity []. The three immunoglobin(Ig)-like domains, D1, D2, and D3, present a stretch of acidic amino acids (known as the acid box) between D1 and D2. 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. FGFR family members differ from one another in their ligandaffinities and tissue distribution [, ]. Most FGFs can bind to several different FGFR subtypes. Indeed, FGF1 is sometimes referred to as the universal ligand, as it is capable of activating all of the different FGFRs []. However, there are some exceptions. For example, FGF7 only interacts with FGFR2 []and FGF18 was recently shown to only activate FGFR3 []. Fibroblast growth factor receptor 1 (FGFR1) binds both acidic and basic fibroblast growth factors and is involved in limb induction []. FGFR1 has been shown to be associated with Pfeiffer syndrome [], and cleft lip and/or palate [, ]. Fibroblast growth factor receptor 1 has been shown to interact with growth factor receptor-bound protein 14 (GRB14) [], Src homology 2 domain containing adaptor protein B (SHB) [], fibroblast growth factor receptor substrate 2 (FRS2)[]and fibroblast growth factor 1 (FGF1) [, ].This entry represents the catalytic domain of FGFR1.
Fibroblast growth factors (FGFs) [, ]are a family of multifunctional proteins, often referred to as 'promiscuous growth factors' due to their diverse actions on multiple cell types [, ]. FGFs are mitogens, which stimulate growth or differentiation of cells of mesodermal or neuroectodermal origin. The function of FGFs in developmental processes include mesoderm induction, anterior-posterior patterning, limb development, and neural induction and development. In mature tissues, they are involved in diverse processes including keratinocyte organisation and wound healing [, , , , , ]. FGF involvement is critical during normal development of both vertebrates and invertebrates, and irregularities in their function leads to a range of developmental defects [, , , ]. Fibroblast growth factors are heparin-binding proteins and interactions with cell-surface-associated heparan sulfate proteoglycans have been shown to be essential for FGF signal transduction. FGFs have internal pseudo-threefold symmetry (β-trefoil topology) []. There are currently over 20 different FGF family members that have been identified in mammals, all of which are structurally related signaling molecules [, ]. They exert their effects through four distinct membrane fibroblast growth factor receptors (FGFRs), FGFR1 to FGFR4 [], which belong to the tyrosine kinase superfamily. Upon binding to FGF, the receptors dimerize and their intracellular tyrosine kinase domains become active [].The FGFRs consist of an extracellular ligand-binding domain composed of three immunoglobulin-like domains (D1-D3), a single transmembrane helix domain, and an intracellular domain with tyrosine kinase activity []. The three immunoglobin(Ig)-like domains, D1, D2, and D3, present a stretch of acidic amino acids (known as the acid box) between D1 and D2. 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. FGFR family members differ from one another in their ligand affinities and tissue distribution [, ]. Most FGFs can bind to several different FGFR subtypes. Indeed, FGF1 is sometimes referred to as the universal ligand, as it is capable of activating all of the different FGFRs []. However, there are some exceptions. For example, FGF7 only interacts with FGFR2 []and FGF18 was recently shown to only activate FGFR3 []. This entry represents the fibroblast growth factor receptor family.
