Fibroblast growth factor 8

FGF8
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 2FDB
Identifiers
Aliases	FGF8, AIGF, FGF-8, HBGF-8, HH6, KAL6, fibroblast growth factor 8
External IDs	OMIM: 600483; MGI: 99604; HomoloGene: 7715; GeneCards: FGF8; OMA:FGF8 - orthologs
Gene location (Human) Chr. Chromosome 10 (human)[1] Band 10q24.32 Start 101,770,109 bp[1] End 101,780,371 bp[1]
Gene location (Mouse) Chr. Chromosome 19 (mouse)[2] Band 19 C3|19 38.75 cM Start 45,725,237 bp[2] End 45,731,354 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in gonad sural nerve Brodmann area 9 monocyte cingulate gyrus anterior cingulate cortex prefrontal cortex right frontal lobe tendon primary visual cortex Top expressed in surface ectoderm Apical ectodermal ridge footplate third ventricle medial nasal prominence pituitary stalk infundibular recess tail of embryo lateral nasal prominence endoderm More reference expression data BioGPS More reference expression data
Gene ontology Molecular function type 1 fibroblast growth factor receptor binding type 2 fibroblast growth factor receptor binding growth factor activity fibroblast growth factor receptor binding chemoattractant activity protein tyrosine kinase activity 1-phosphatidylinositol-3-kinase activity phosphatidylinositol-4,5-bisphosphate 3-kinase activity Cellular component extracellular region intracellular anatomical structure external side of plasma membrane extracellular space Biological process negative regulation of neuron apoptotic process cell migration involved in mesendoderm migration male genitalia development epithelial to mesenchymal transition involved in endocardial cushion formation outflow tract morphogenesis embryonic heart tube development mesonephros development heart looping forebrain neuron development blood vessel remodeling central nervous system neuron development positive regulation of ERK1 and ERK2 cascade metanephros development cell proliferation in forebrain positive regulation of mitotic nuclear division gonad development pharyngeal system development branching involved in salivary gland morphogenesis apoptotic process dopaminergic neuron differentiation cell fate commitment limb morphogenesis kidney development lung development anatomical structure morphogenesis signal transduction involved in regulation of gene expression regulation of odontogenesis of dentin-containing tooth response to oxidative stress embryo development ending in birth or egg hatching forebrain morphogenesis heart development telencephalon development branching involved in ureteric bud morphogenesis midbrain-hindbrain boundary development branching involved in blood vessel morphogenesis thyroid-stimulating hormone-secreting cell differentiation positive chemotaxis mesodermal cell migration cell differentiation dorsal/ventral axon guidance corticotropin hormone secreting cell differentiation organ induction neural plate morphogenesis positive regulation of organ growth negative regulation of apoptotic process BMP signaling pathway outflow tract septum morphogenesis odontogenesis thyroid gland development pallium development gastrulation canonical Wnt signaling pathway subpallium development lung morphogenesis response to organic cyclic compound otic vesicle formation forebrain dorsal/ventral pattern formation heart morphogenesis aorta morphogenesis generation of neurons MAPK cascade neuroepithelial cell differentiation multicellular organism development fibroblast growth factor receptor signaling pathway positive regulation of gene expression negative regulation of cardiac muscle tissue development determination of left/right symmetry inner ear morphogenesis positive regulation of cell population proliferation bone development motor neuron axon guidance positive regulation of cell division embryonic hindlimb morphogenesis phosphatidylinositol phosphate biosynthetic process phosphatidylinositol-3-phosphate biosynthetic process peptidyl-tyrosine phosphorylation positive regulation of cell differentiation regulation of signaling receptor activity positive regulation of protein kinase B signaling positive regulation of G protein-coupled receptor signaling pathway positive regulation of peptidyl-tyrosine phosphorylation Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 2253 14179 Ensembl ENSG00000107831 ENSMUSG00000025219 UniProt P55075 P37237 RefSeq (mRNA) NM_001206389 NM_006119 NM_033163 NM_033164 NM_033165 NM_001166361 NM_001166362 NM_001166363 NM_010205 NM_001379139 NM_001379140 RefSeq (protein) NP_001193318 NP_006110 NP_149353 NP_149354 NP_149355 NP_001159833 NP_001159834 NP_001159835 NP_034335 NP_001366068 NP_001366069 NP_001390029 Location (UCSC) Chr 10: 101.77 – 101.78 Mb Chr 19: 45.73 – 45.73 Mb PubMed search [3] [4]
Wikidata
View/Edit Human View/Edit Mouse

Fibroblast growth factor 8 (FGF-8) is a protein that in humans is encoded by the FGF8 gene.^[5][6]

Function

The protein encoded by this gene is a member of the fibroblast growth factor (FGF) family. FGF family members possess broad mitogenic and cell survival activities, and are involved in a variety of biological processes, including embryonic development, cell growth, morphogenesis, tissue repair, tumor growth and invasion.^[6]

FGF-8 is important and necessary for setting up and maintaining the midbrain/hindbrain border (or mesencephalon/metencephalon border) which plays the vital role of “organizer” in development, like the Spemann organizer” of the gastrulating embryo. FGF-8 is expressed in the region where Otx2 and Gbx2 cross inhibit each other and is maintained expression by this interaction. Once expressed, the Fgf8 induces other transcription factors to form cross-regulatory loops between cells, thus the border is established. Through development, the Fgf8 goes to regulate the growth and differentiation of progenitor cells in this region to produce ultimate structure of midbrain and hindbrain.^[7] Crossely’s experiment proves that the FGF-8 is sufficient to induce the repatterning of midbrain and hindbrain structure.^[8]

In the development of forebrain, cortical patterning centers are the boundaries or poles of cortical primordium, where multiple BMP and WNT genes are expressed. Besides, at the anterior pole several FGF family including Fgf3, 8,17 and 18 overlap in expression.^[9] The similarity in cortical gene expression in Emx2 mutants and mice in which the anterior FGF8 source is augmented suggests that FGF8 controls the graded expression (low anterior, high posterior) of Emx2 in the cortical primordium. Emx2 is one of the protomap molecular determinants that prove to be closely interacted with Pax6. Emx2 and Pax6 are expressed in opposing gradients along the A/P axis of the cortical primordium and cooperate to set up area pattern. Fgf8 and Emx2 antagonize each other to create the development map. FGF-8 promotes the development of anterior part and suppresses posterior fate, while the Emx2 does the reverse. What's more, FGF8 manipulations suggest FGF8 controls the cortical graded expression of COUP-TF1.^[10] Moreover, the sharpness of both COUPTF1 and COUP-TF2 expression borders would be expected of genes involved in boundary specification. Thus, the interaction between them regulates the A/P axis of cortical primordium and directs the development map of cortical area.

FGF8 signaling from the apical ectodermal ridge (AER), which borders the distal end of the limb bud,^[11] is necessary for forming normal limbs. In the absence of FGF8, limb buds can be reduced in size, hypoplasia or aplasia of bones or digits within the three limb segments may occur, as well as delays in subsequent expressions of other genes (Shh or FGF4). FGF8 is responsible for cell proliferation and survival, as well. Loss of function or decreased expression could result in the malformation or absence of essential limb components. Studies have shown that the forelimbs tend to be more affected by the loss of FGF8 signaling than the hindlimbs^[11] and the loss tends to affect the proximal components more heavily than the distal components.^[12] FGF8 not only aids in the formation of the limb bud and skeletal components of the limb, but the tendons within the limb are affected by it near the portions closest to the muscle extremities.^[13] This diffusible polypeptide is responsible for inducing the limb bud, then inducing and maintaining sonic hedgehog expression in the established limb bud promoting outgrowth of the limb. Evidence for this comes from a study done by Crossley and his colleagues, in which FGF8 soaked beads were surgically used to replace AER areas with the beads.^[14] These studies showed that ectopic limbs formed either fully functional or mostly functional limbs near the normal limbs or limb areas. FGF8 has also been recorded to regulate craniofacial structure formation, including the teeth, palate, mandible, and salivary glands.^[15] Decreased expression can result in the absence of molar teeth, failure to close the palate, or decreased mandible size.

FGF8 has been documented to play a role in oralmaxillogacial diseases and CRISPR-cas9 gene targeting on FGF8 may be key in treating these diseases. Cleft lip and/or palate (CLP) genome wide gene analysis shows a D73H missense mutation in the FGF8 gene^[15] which reduces the binding affinity of FGF8. Loss of Tbx1 and Tfap2 can result in proliferation and apoptosis in the palate cells increasing the risk of CLP. Overexpression of FGF8 due to misregulation of the Gli processing gene may result in cliliopathies. Agnathia, a malformation of the mandible, is often a lethal condition that comes from the absence of BMP4 regulators (noggin and chordin), resulting in high levels of BMP4 signaling, which in turn drastically reduces FGF8 signaling, increasing cell death during mandibular outgrowth.^[15] Lastly, the ability for FGF8 to regulate cell proliferation has caused interest in its effects on tumors or squamous cell carcinoma. CRISPR-cas9 gene targeting methods are currently being studied to determine if they are the key to solving FGF8 mutations associated with oral diseases.

Clinical significance

This protein is known to be a factor that supports androgen and anchorage independent growth of mammary tumor cells. Overexpression of this gene has been shown to increase tumor growth and angiogenesis. The adult expression of this gene was once thought to be restricted to testes and ovaries but has been described in several organ systems.^[16] Temporal and spatial pattern of this gene expression suggests its function as an embryonic epithelial factor. Studies of the mouse and chick homologs reveal roles in midbrain and limb development, organogenesis, embryo gastrulation and left-right axis determination. The alternative splicing of this gene results in four transcript variants.^[6]

References

Further reading

External links

• GeneReviews/NCBI/NIH/UW entry on Kallmann syndrome
• FGF8 human gene location in the UCSC Genome Browser.
• FGF8 human gene details in the UCSC Genome Browser.