Gene Summary: This FGFR3 gene encodes a member of the fibroblast growth factor receptor (FGFR) family, with its amino acid sequence being highly conserved between members and among divergent species. FGFR family members differ from one another in their ligand affinities and tissue distribution. A full-length representative protein would consist of an extracellular region, composed of three immunoglobulin-like domains, a single hydrophobic membrane-spanning segment and a cytoplasmic tyrosine kinase domain. The extracellular portion of the protein interacts with fibroblast growth factors, setting in motion a cascade of downstream signals, ultimately influencing mitogenesis and differentiation. This particular family member binds acidic and basic fibroblast growth hormone and plays a role in bone development and maintenance. Mutations in this FGFR3 gene lead to craniosynostosis and multiple types of skeletal dysplasia. Three alternatively spliced transcript variants that encode different protein isoforms have been described.General information above from NCBI
Catalytic activity: ATP + a [protein]-L-tyrosine = ADP + a [protein]-L-tyrosine phosphate.
Enzyme regulation: Present in an inactive conformation in the absence of bound ligand. Ligand binding leads to dimerization and activation by autophosphorylation on tyrosine residues. Inhibited by SU5402.
Subunit structure: Monomer. Homodimer after ligand binding. Interacts with FGF1, FGF2, FGF4, FGF6; FGF8, FGF9, FGF10, FGF17, FGF18, FGF19, FGF20 and FGF23 (in vitro). Interacts with KLB. Affinity for fibroblast growth factors (FGFs) is increased by heparan sulfate glycosaminoglycans that function as coreceptors. Likewise, KLB increases the affinity for FGF19 and FGF21. Interacts with PIK3R1, PLCG1, SOCS1 and SOCS3.
Domain: The second and third Ig-like domains directly interact with fibroblast growth factors (FGF) and heparan sulfate proteoglycans.
Subcellular location: Cell membrane; Single-pass type I membrane protein. Cytoplasmic vesicle. Endoplasmic reticulum. Note=The activated receptor is rapidly internalized and degraded. Detected in intracellular vesicles after internalization of the autophosphorylated receptor.
Tissue specificity: Expressed in brain, kidney and testis. Very low or no expression in spleen, heart, and muscle. In 20- to 22- week old fetuses it is expressed at high level in kidney, lung, small intestine and brain, and to a lower degree in spleen, liver, and muscle. Isoform 2 is detected in epithelial cells. Isoform 1 is not detected in epithelial cells. Isoform 1 and isoform 2 are detected in fibroblastic cells.
Post-translational: Autophosphorylated. Binding of FGF family members together with heparan sulfate proteoglycan or heparin promotes receptor dimerization and autophosphorylation on tyrosine residues. Autophosphorylation occurs in trans between the two FGFR molecules present in the dimer. Phosphorylation at Tyr-724 is essential for stimulation of cell proliferation and activation of PIK3R1, STAT1 and MAP kinase signaling. Phosphorylation at Tyr-760 is required for interaction with PIK3R1 and PLCG1.
Ubiquitinated. Is rapidly ubiquitinated after ligand binding and autophosphorylation, leading to receptor internalization and degradation. Subject to both proteasomal and lysosomal degradation.
N-glycosylated in the endoplasmic reticulum. The N-glycan chains undergo further maturation to an Endo H-resistant form in the Golgi apparatus.
Involvement in disease: Achondroplasia (ACH) [MIM:100800]: A frequent form of short-limb dwarfism. It is characterized by a long, narrow trunk, short extremities, particularly in the proximal (rhizomelic) segments, a large head with frontal bossing, hypoplasia of the midface and a trident configuration of the hands. Note=The disease is caused by mutations affecting the gene represented in this entry.
Crouzon syndrome with acanthosis nigricans (CAN) [MIM:612247]: Classic Crouzon disease which is caused by mutations in the FGFR2 gene is characterized by craniosynostosis (premature fusion of the skull sutures), and facial hypoplasia. Crouzon syndrome with acanthosis nigricans (a skin disorder characterized by pigmentation anomalies), CAN, is considered to be an independent disorder from classic Crouzon syndrome. CAN is characterized by additional more severe physical manifestation, such as Chiari malformation, hydrocephalus, and atresia or stenosis of the choanas, and is caused by a specific mutation (Ala-391 to Glu) in the transmembrane domain of FGFR3. It is proposed to have an autosomal dominant mode of inheritance. Note=The disease is caused by mutations affecting the gene represented in this entry.
Thanatophoric dysplasia 1 (TD1) [MIM:187600]: A neonatal lethal skeletal dysplasia. Affected individuals manifest severe shortening of the limbs with macrocephaly, narrow thorax, short ribs, and curved femurs. Note=The disease is caused by mutations affecting the gene represented in this entry.
Thanatophoric dysplasia 2 (TD2) [MIM:187601]: A neonatal lethal skeletal dysplasia causing severe shortening of the limbs, narrow thorax and short ribs. Patients with thanatophoric dysplasia type 2 have straight femurs and cloverleaf skull. Note=The disease is caused by mutations affecting the gene represented in this entry.
Hypochondroplasia (HCH) [MIM:146000]: Autosomal dominant disease and is characterized by disproportionate short stature. It resembles achondroplasia, but with a less severe phenotype. Note=The disease is caused by mutations affecting the gene represented in this entry.
Bladder cancer (BLC) [MIM:109800]: A malignancy originating in tissues of the urinary bladder. It often presents with multiple tumors appearing at different times and at different sites in the bladder. Most bladder cancers are transitional cell carcinomas that begin in cells that normally make up the inner lining of the bladder. Other types of bladder cancer include squamous cell carcinoma (cancer that begins in thin, flat cells) and adenocarcinoma (cancer that begins in cells that make and release mucus and other fluids). Bladder cancer is a complex disorder with both genetic and environmental influences. Note=Disease susceptibility is associated with variations affecting the gene represented in this entry. Somatic mutations can constitutively activate FGFR3.
Cervical cancer (CERCA) [MIM:603956]: A malignant neoplasm of the cervix, typically originating from a dysplastic or premalignant lesion previously present at the active squamocolumnar junction. The transformation from mild dysplastic to invasive carcinoma generally occurs slowly within several years, although the rate of this process varies widely. Carcinoma in situ is particularly known to precede invasive cervical cancer in most cases. Cervical cancer is strongly associated with infection by oncogenic types of human papillomavirus. Note=The gene represented in this entry is involved in disease pathogenesis.
Camptodactyly tall stature and hearing loss syndrome (CATSHL syndrome) [MIM:610474]: Autosomal dominant syndrome characterized by permanent and irreducible flexion of one or more fingers of the hand and/or feet, tall stature, scoliosis and/or a pectus excavatum, and hearing loss. Affected individuals have developmental delay and/or mental retardation, and several of these have microcephaly. Radiographic findings included tall vertebral bodies with irregular borders and broad femoral metaphyses with long tubular shafts. On audiological exam, each tested member have bilateral sensorineural hearing loss and absent otoacoustic emissions. The hearing loss was congenital or developed in early infancy, progressed variably in early childhood, and range from mild to severe. Computed tomography and magnetic resonance imaging reveal that the brain, middle ear, and inner ear are structurally normal. Note=The disease is caused by mutations affecting the gene represented in this entry.
Multiple myeloma (MM) [MIM:254500]: A malignant tumor of plasma cells usually arising in the bone marrow and characterized by diffuse involvement of the skeletal system, hyperglobulinemia, Bence-Jones proteinuria and anemia. Complications of multiple myeloma are bone pain, hypercalcemia, renal failure and spinal cord compression. The aberrant antibodies that are produced lead to impaired humoral immunity and patients have a high prevalence of infection. Amyloidosis may develop in some patients. Multiple myeloma is part of a spectrum of diseases ranging from monoclonal gammopathy of unknown significance (MGUS) to plasma cell leukemia. Note=The gene represented in this entry may be involved in disease pathogenesis. A chromosomal aberration involving FGFR3 is found in multiple myeloma. Translocation t(4;14)(p16.3;q32.3) with the IgH locus.
Lacrimo-auriculo-dento-digital syndrome (LADDS) [MIM:149730]: An autosomal dominant ectodermal dysplasia, a heterogeneous group of disorders due to abnormal development of two or more ectodermal structures. Lacrimo-auriculo-dento-digital syndrome is characterized by aplastic/hypoplastic lacrimal and salivary glands and ducts, cup-shaped ears, hearing loss, hypodontia and enamel hypoplasia, and distal limb segments anomalies. In addition to these cardinal features, facial dysmorphism, malformations of the kidney and respiratory system and abnormal genitalia have been reported. Craniosynostosis and severe syndactyly are not observed. Note=The disease is caused by mutations affecting the gene represented in this entry.
Keratinocytic non-epidermolytic nevus (KNEN) [MIM:162900]: Epidermal nevi of the common, non-organoid and non- epidermolytic type are benign skin lesions and may vary in their extent from a single (usually linear) lesion to widespread and systematized involvement. They may be present at birth or develop early during childhood. Note=The disease is caused by mutations affecting the gene represented in this entry.
Muenke syndrome (MNKS) [MIM:602849]: A condition characterized by premature closure of coronal suture of skull during development (coronal craniosynostosis), which affects the shape of the head and face. It may be uni- or bilateral. When bilateral, it is characterized by a skull with a small antero- posterior diameter (brachycephaly), often with a decrease in the depth of the orbits and hypoplasia of the maxillae. Unilateral closure of the coronal sutures leads to flattening of the orbit on the involved side (plagiocephaly). The intellect is normal. In addition to coronal craniosynostosis some affected individuals show skeletal abnormalities of hands and feet, sensorineural hearing loss, mental retardation and respiratory insufficiency. Note=The disease is caused by mutations affecting the gene represented in this entry.
Keratosis, seborrheic (KERSEB) [MIM:182000]: A common benign skin tumor. Seborrheic keratoses usually begin with the appearance of one or more sharply defined, light brown, flat macules. The lesions may be sparse or numerous. As they initially grow, they develop a velvety to finely verrucous surface, followed by an uneven warty surface with multiple plugged follicles and a dull or lackluster appearance. Note=The disease is caused by mutations affecting the gene represented in this entry.
Testicular germ cell tumor (TGCT) [MIM:273300]: A common malignancy in males representing 95% of all testicular neoplasms. TGCTs have various pathologic subtypes including: unclassified intratubular germ cell neoplasia, seminoma (including cases with syncytiotrophoblastic cells), spermatocytic seminoma, embryonal carcinoma, yolk sac tumor, choriocarcinoma, and teratoma. Note=The gene represented in this entry may be involved in disease pathogenesis.
Sequence similarity: Belongs to the protein kinase superfamily. Tyr protein kinase family. Fibroblast growth factor receptor subfamily.
Contains 3 Ig-like C2-type (immunoglobulin-like) domains.
Contains 1 protein kinase domain.
General information above from UniProt