ECSM2, an endothelial specific filamin a binding protein that mediates chemotaxis.
OBJECTIVE
We aimed to characterize the expression and function of a novel transcript that bioinformatics analysis predicted to be endothelial specific, called endothelial-specific molecule-2 (ECSM2).


RESULTS
A full-length cDNA was isolated and predicted ECSM2 to be a putative 205-amino acid transmembrane protein that bears no homology to any known protein. Quantitative polymerase chain reaction analysis in vitro and in situ hybridization analysis in vivo confirmed ECSM2 expression to be exclusively endothelial, and localization to the plasma membrane was shown. Knockdown of ECSM2 expression in human umbilical vein endothelial cells using siRNA resulted in both reduced chemotaxis and impaired tube formation on matrigel, a solubilized basement membrane, both processes involved in angiogenesis. A yeast 2 hybrid analysis using the ECSM2 intracellular domain identified filamin A as an interacting protein. This interaction was confirmed by precipitation of filamin-A from endothelial cell lysates by a GST-tagged intracellular domain of ECSM2.


CONCLUSIONS
This study is the first to characterize a novel cell surface protein ECSM2 that regulates endothelial chemotaxis and tube formation, and interacts with filamin A. These studies implicate a role for ECSM2 in angiogenesis via modulation of the actin cytoskeleton.
Armstrong
Laura-Jane
LJ
Angiogenesis Laboratory, Cancer Research UK, Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford.
Heath
Victoria L
VL
Sanderson
Sharon
S
Kaur
Sukhbir
S
Beesley
James F J
JF
Herbert
John M J
JM
Legg
John A
JA
Poulsom
Richard
R
Bicknell
Roy
R
D000595:Amino Acid Sequence; D051017:Apoptosis Regulatory Proteins; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D002633:Chemotaxis; D003001:Cloning, Molecular; D003285:Contractile Proteins / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism*; D064448:Filamins; D006801:Humans; D017403:In Situ Hybridization; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008840:Microfilament Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D018919:Neovascularization, Physiologic; D016133:Polymerase Chain Reaction; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D020798:Two-Hybrid System Techniques
D051017:Apoptosis Regulatory Proteins; D003285:Contractile Proteins; C531407:ECSCR protein, human; D064448:Filamins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins