The epidermal growth factor-like domains of the human EMR2 receptor mediate cell attachment through chondroitin sulfate glycosaminoglycans.
Using multivalent protein probes, an evolutionarily conserved endogenous ligand for EMR2, a human myeloid cell-restricted EGF-TM7 receptor, was identified on the surface of a number of adherent cell lines. In addition, in situ staining of the ligand has revealed specific in vivo patterns consistent with a connective tissue distribution. The interaction is conserved across species and mediated exclusively by the largest EMR2 isoform containing 5 epidermal growth factor (EGF)-like modules. Antibody-blocking studies subsequently revealed that the fourth EGF-like module constitutes the major ligand-binding site. The largest isoform of CD97, a related EGF-TM7 molecule containing an identical EGF-like module, also binds to the putative EMR2 ligand. Through the use of mutant Chinese hamster ovary (CHO) cell lines defective in glycosaminoglycans (GAGs) biosynthesis as well as the enzymatic removal of specific cell surface GAGs, the molecular identity of the EMR2 ligand was identified as chondroitin sulfate (CS). Thus, exogenous CS GAGs blocked the EMR2-ligand interaction in a dose-dependent manner. EMR2-CS interaction is Ca2+- and sulphation-dependent and results in cell attachment. This is the first report of a GAG ligand for the TM7 receptors extending the already vast repertoire of stimuli of the GPCR superfamily.
Stacey
Martin
M
Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, United Kingdom.
Chang
Gin-Wen
GW
Davies
John Q
JQ
Kwakkenbos
Mark J
MJ
Sanderson
Ralph D
RD
Hamann
Jörg
J
Gordon
Siamon
S
Lin
Hsi-Hsien
HH
D017398:Alternative Splicing; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001665:Binding Sites; D019921:Biotinylation; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D002469:Cell Separation; D002478:Cells, Cultured; D002809:Chondroitin Sulfates / Q000737:chemistry*; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D004815:Epidermal Growth Factor / Q000737:chemistry* / Q000378:metabolism; D005434:Flow Cytometry; D006025:Glycosaminoglycans / Q000737:chemistry*; D006801:Humans; D008024:Ligands; D051379:Mice; D008856:Microscopy, Fluorescence; D011485:Protein Binding; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled; D014018:Tissue Distribution
C412456:ADGRE2 protein, human; D000911:Antibodies, Monoclonal; D006025:Glycosaminoglycans; D008024:Ligands; D020033:Protein Isoforms; D043562:Receptors, G-Protein-Coupled; D004815:Epidermal Growth Factor; D002809:Chondroitin Sulfates; D002118:Calcium