A47
Characterisation of ECSM2, a filamin A interacting protein, which modulates endothelial chemotaxis.
Victoria L Heath1, Laura-Jane Armstrong2, Sharon Sanderson2, Sukhbir Kaur1, James FJ Beesley1, John MJ Herbert1, John A Legg1, Richard Poulsom3, Roy Bicknell1
1Cancer Research UK Angiogenesis Group, The Institute for Biomedical Research, University of Birmingham Medical School, Edgbaston, Birmingham B15 2TT, UK, 2Angiogenesis Laboratory, Cancer Research UK, Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK, 3Cancer Research UK, The London Research Institute, Lincoln’s Inn Fields, London WC2A 3PX, UK
Endothelial cells line all blood vessels and play a critical role in regulating vascular permeability, leukocyte transmigration and angiogenesis. Angiogenesis or the growth of new blood vessels plays a critical role in controlling the growth and metastasis of solid tumours, thus playing a key role in the pathogenesis of cancer.
We originally identified endothelial cell specific molecule 2 (ECSM2) bioinformatically as having endothelial specific expression; this has been confirmed both in vitro using reverse transcription and PCR on a range of immortalised and primary cell lines and in vivo using in situ hybridisation. ECSM2 is a type I transmembrane molecule which localises to the plasma membrane, particularly in actin-rich structures such as filopodia. In order to assess its function in endothelial cells, its expression was knocked down using siRNA in human umbilical vein endothelial cells.
Endothelial cells lacking ECSM2 failed to undergo chemotaxis in response to growth factors and showed defective tube formation on matrigel, a solubilised basement membrane preparation. Yeast-2-hybrid analyses using the intracellular domain of ECSM2 as bait identified filaminA as an interacting protein. This was confirmed using ECSM2 intracellular domain to pulldown filamin A from endothelial cell lysate. Filamin A is a member of the filamin family of actin binding proteins which link actin filaments at the cell surface, and are involved in the maintenance of cell shape and locomotion.
This is the first characterization of ECSM2 as a filamin A interacting protein, which modulates endothelial chemotaxis and tube formation.
