VEGF receptor


VEGF receptors are receptors for vascular endothelial growth factor. There are three main subtypes of VEGFR, numbered 1, 2 and 3. Also, they may be membrane-bound or soluble, depending on alternative splicing.
Inhibitors of VEGFR are used in the treatment of cancer.

VEGF

is an important signaling protein involved in both vasculogenesis and angiogenesis. 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. 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

All members of the VEGF family stimulate cellular responses by binding to tyrosine kinase receptors 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 and VEGFR-2. 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. In fact, an alternatively spliced form of VEGFR-1 is not a membrane bound protein but is secreted and functions primarily as a decoy. A third receptor has been discovered, 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, TACO VEGF binds to receptor complexes consisting of both neuropilins and VEGFRs. This receptor complex has increased VEGF signalling activity in endothelial cells. Neuropilins 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 angiogenesis.