VEGF receptor

fms-related tyrosine kinase 1 (vascular endothelial growth factor/vascular permeability factor receptor) Identifiers Symbol FLT1 Alt. symbols FLT Entrez 2321 HUGO 3763 OMIM 165070 RefSeq NM_002019 UniProt P17948 Other data EC number 2.7.1.112 Locus Chr. 13 q12 kinase insert domain receptor (a type III receptor tyrosine kinase) Identifiers Symbol KDR Alt. symbols FLK1, VEGFR, VEGFR2, CD309 Entrez 3791 HUGO 6307 OMIM 191306 RefSeq NM_002253 UniProt P35968 Other data EC number 2.7.1.112 Locus Chr. 4 q11-q12 fms-related tyrosine kinase 4 Identifiers Symbol FLT4 Alt. symbols VEGFR3, PCL Entrez 2324 HUGO 3767 OMIM 136352 RefSeq NM_002020 UniProt P35916 Other data EC number 2.7.1.112 Locus Chr. 5 q34-q35

VEGF receptors are receptors for vascular endothelial growth factor (VEGF). There are three main subtypes of VEGFR, numbered 1, 2 and 3. Also, they may be membrane-bound (mbVEGFR) or soluble (sVEGFR), depending on alternative splicing.

VEGF

Main article: Vascular endothelial growth factor

Vascular endothelial growth factor (VEGF) is an important signaling protein involved in both vasculogenesis (the formation of the circulatory system) and angiogenesis (the growth of blood vessels from pre-existing vasculature). As its name implies, VEGF activity is restricted mainly to cells of the vascular endothelium, although it does have effects on a limited number of other cell types (e.g. stimulation monocyte/macrophage migration). In vitro, VEGF has been shown to stimulate endothelial cell mitogenesis and cell migration. VEGF also enhances microvascular permeability and is sometimes referred to as vascular permeability factor.

Receptor biology

Ligands for different VEGF receptors.

All members of the VEGF family stimulate cellular responses by binding to tyrosine kinase receptors (the VEGFRs) on the cell surface, causing them to dimerize and become activated through transphosphorylation. The VEGF receptors have an extracellular portion consisting of 7 immunoglobulin-like domains, a single transmembrane spanning region and an intracellular portion containing a split tyrosine-kinase domain.

VEGF-A binds to VEGFR-1 (Flt-1) and VEGFR-2 (KDR/Flk-1). VEGFR-2 appears to mediate almost all of the known cellular responses to VEGF. The function of VEGFR-1 is less well defined, although it is thought to modulate VEGFR-2 signaling. Another function of VEGFR-1 is to act as a dummy/decoy receptor, sequestering VEGF from VEGFR-2 binding (this appears to be particularly important during vasculogenesis in the embryo). In fact, an alternatively spliced form of VEGFR-1 (sFlt1) is not a membrane bound protein but is secreted and functions primarily as a decoy. A third receptor has been discovered (VEGFR-3), however, VEGF-A is not a ligand for this receptor. VEGFR-3 mediates lymphangiogenesis in response to VEGF-C and VEGF-D.

In addition to binding to VEGFRs, VEGF binds to receptor complexes consisting of both neuropilins and VEGFRs. This receptor complex has increased VEGF signalling activity in endothelial cells (blood vessels). Neuropilins (NRP) are pleitrophic receptors and therefore other molecules may interfere with the signalling of the NRP/VEGFR receptor complexes. For example, Class 3 semaphorins compete with VEGF₁₆₅ for NRP binding and could therefore regulate VEGF-mediated angiogensis.

VEGFR antagonists

Some VEGFR antagonists (inhibitors) (for example lenvatinib, motesanib) are under investigation for treating various cancers. Pazopanib was approved for renal cell carcinoma in 2009. Regorafenib was approved for colorectal cancer in Sept 2012.

External links

• VEGF Receptors at the US National Library of Medicine Medical Subject Headings (MeSH)
• Proteopedia Vascular_Endothelial_Growth_Factor_Receptor - the Vascular Endothelial Growth Factor Receptor Structure in Interactive 3D