Abstract
The discoidin domain receptors (DDRs) are receptor tyrosine kinases that upon binding to collagens undergo receptor phosphorylation, which in turn activates signal transduction pathways that regulate cell-collagen interactions. We report here that collagen-dependent DDR1 activation is partly regulated by the proteolytic activity of the membrane-anchored collagenases, MT1-, MT2-, and MT3-matrix metalloproteinase (MMP). These collagenases cleave DDR1 and attenuate collagen I- and IV-induced receptor phosphorylation. This effect is not due to ligand degradation, as it proceeds even when the receptor is stimulated with collagenase-resistant collagen I (r/r) or with a triple-helical peptide harboring the DDR recognition motif in collagens. Moreover, the secreted collagenases MMP-1 and MMP-13 and the glycosylphosphatidylinositol-anchored membrane-type MMPs (MT4- and MT6-MMP) have no effect on DDR1 cleavage or activation. N-terminal sequencing of the MT1-MMP-mediated cleaved products and mutational analyses show that cleavage of DDR1 takes place within the extracellular juxtamembrane region, generating a membrane-anchored C-terminal fragment. Metalloproteinase inhibitor studies show that constitutive shedding of endogenous DDR1 in breast cancer HCC1806 cells is partly mediated by MT1-MMP, which also regulates collagen-induced receptor activation. Taken together, these data suggest a role for the collagenase of membrane-type MMPs in regulation of DDR1 cleavage and activation at the cell-matrix interface.
Highlights
DDR1 is a receptor tyrosine kinase that signals in response to collagen and regulates cell-collagen interactions
Previous studies have shown that DDR1 is shed from the cell surface in both constitutive [41] and collagen-induced manners [35, 42], leading to the formation of two C-terminal fragments of 58 and 62 kDa [42]
The data presented here show for the first time that membraneanchored but not secreted collagenases cleave DDR1 releasing a soluble ectodomain and, negatively regulate collagen-dependent receptor phosphorylation. This effect of the membrane-anchored collagenases on DDR1 could not be reproduced by either MT4- or MT6-matrix metalloproteinase (MMP) further demonstrating the specificity of DDR1 as a substrate for the transmembrane membrane-type MMPs (MT-MMPs)
Summary
DDR1 is a receptor tyrosine kinase that signals in response to collagen and regulates cell-collagen interactions. We report here that collagen-dependent DDR1 activation is partly regulated by the proteolytic activity of the membrane-anchored collagenases, MT1-, MT2-, and MT3-matrix metalloproteinase (MMP) These collagenases cleave DDR1 and attenuate collagen I- and IV-induced receptor phosphorylation. Metalloproteinase inhibitor studies show that constitutive shedding of endogenous DDR1 in breast cancer HCC1806 cells is partly mediated by MT1-MMP, which regulates collagen-induced receptor activation Taken together, these data suggest a role for the collagenase of membrane-type MMPs in regulation of DDR1 cleavage and activation at the cellmatrix interface. DDR1b and DDR1c contain an additional 37 residues in the intracellular juxtamembrane region (residues 505–541), whereas DDR1c possesses six additional residues in the KD These DDR1 variants are fully functional RTKs that may activate different signaling pathways in response to collagen and elicit different cell functions [1,2,3]. Our results shed light on a novel interaction between surface proteases and RTKs that integrate collagen-induced signaling and pericellular proteolysis
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