The heparin-binding domain of HB-EGF mediates localization to sites of cell-cell contact and prevents HB-EGF proteolytic release.
Heparin-binding EGF-like growth factor (HB-EGF) is a ligand for EGF receptor (EGFR) and possesses the ability to signal in juxtacrine, autocrine and/or paracrine mode, with these alternatives being governed by the degree of proteolytic release of the ligand. Although the spatial range of diffusion of released HB-EGF is restricted by binding heparan-sulfate proteoglycans (HSPGs) in the extracellular matrix and/or cellular glycocalyx, ascertaining mechanisms governing non-released HB-EGF localization is also important for understanding its effects. We have employed a new method for independently tracking the localization of the extracellular EGF-like domain of HB-EGF and the cytoplasmic C-terminus. A striking observation was the absence of the HB-EGF transmembrane pro-form from the leading edge of COS-7 cells in a wound-closure assay; instead, this protein localized in regions of cell-cell contact. A battery of detailed experiments found that this localization derives from a trans interaction between extracellular HSPGs and the HB-EGF heparin-binding domain, and that disruption of this interaction leads to increased release of soluble ligand and a switch in cell phenotype from juxtacrine-induced growth inhibition to autocrine-induced proliferation. Our results indicate that extracellular HSPGs serve to sequester the transmembrane pro-form of HB-EGF at the point of cell-cell contact, and that this plays a role in governing the balance between juxtacrine versus autocrine and paracrine signaling.
Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Robin N
RN
Prince
Eric R
ER
Schreiter
Peng
P
Zou
H Steven
HS
Wiley
Alice Y
AY
Ting
Richard T
RT
Lee
Douglas A
DA
Lauffenburger
D000595:Amino Acid Sequence; D066258:Amphiregulin; D000818:Animals; D019556:COS Cells; D002450:Cell Communication / Q000502:physiology*; D049109:Cell Proliferation; D002522:Chlorocebus aethiops; D066255:EGF Family of Proteins; D006023:Glycoproteins / Q000378:metabolism; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D006493:Heparin / Q000235:genetics / Q000378:metabolism*; D066257:Heparin-binding EGF-like Growth Factor; D007365:Intercellular Junctions; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary
D066258:Amphiregulin; C587849:Areg protein, mouse; D066255:EGF Family of Proteins; D006023:Glycoproteins; C587884:Hbegf protein, mouse; D019812:Heparan Sulfate Proteoglycans; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D011498:Protein Precursors; D006493:Heparin