Abstract
Platelet-specific collagen receptor glycoprotein (GP)VI is stable on the surface of
circulating platelets but undergoes ectodomain cleavage on activated platelets.
Activation-dependent GPVI metalloproteolysis is primarily mediated by A Disintegrin
And Metalloproteinase (ADAM) 10. Regulation of platelet ADAMs activity is not welldefined
however Tissue Inhibitors of Metalloproteinases (TIMPs) may play a role. As
levels of TIMPs on platelets and the control of ADAMs-mediated shedding by TIMPs
has not been evaluated, we quantified the levels of TIMPs on the surface of resting
and activated platelets from healthy donors by flow cytometry and multiplex ELISA.
Variable levels of all TIMPs could be detected on platelets. Plasma contained
significant quantities of TIMP1 and TIMP2, but only trace amounts of TIMP3 and
TIMP4. Recombinant TIMP3 strongly ablated resting and activated platelet ADAM10
activity, when monitored using a quenched fluorogenic peptide substrate with
ADAM10 specificity. Whilst ADAM10-specific inhibitor GI254023X or ethylenediamine
tetraacetic acid (EDTA) could modulate ligand-initiated shedding of GPVI, only
recombinant TIMP2 achieved a modest (~20%) inhibition. We conclude that some
platelet TIMPs are able to modulate platelet ADAM10 activity but none strongly
regulate ligand-dependent shedding of GPVI. Our findings provide new insights into
the regulation of platelet receptor sheddase activity.
circulating platelets but undergoes ectodomain cleavage on activated platelets.
Activation-dependent GPVI metalloproteolysis is primarily mediated by A Disintegrin
And Metalloproteinase (ADAM) 10. Regulation of platelet ADAMs activity is not welldefined
however Tissue Inhibitors of Metalloproteinases (TIMPs) may play a role. As
levels of TIMPs on platelets and the control of ADAMs-mediated shedding by TIMPs
has not been evaluated, we quantified the levels of TIMPs on the surface of resting
and activated platelets from healthy donors by flow cytometry and multiplex ELISA.
Variable levels of all TIMPs could be detected on platelets. Plasma contained
significant quantities of TIMP1 and TIMP2, but only trace amounts of TIMP3 and
TIMP4. Recombinant TIMP3 strongly ablated resting and activated platelet ADAM10
activity, when monitored using a quenched fluorogenic peptide substrate with
ADAM10 specificity. Whilst ADAM10-specific inhibitor GI254023X or ethylenediamine
tetraacetic acid (EDTA) could modulate ligand-initiated shedding of GPVI, only
recombinant TIMP2 achieved a modest (~20%) inhibition. We conclude that some
platelet TIMPs are able to modulate platelet ADAM10 activity but none strongly
regulate ligand-dependent shedding of GPVI. Our findings provide new insights into
the regulation of platelet receptor sheddase activity.
Original language | English |
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Article number | 2288213 |
Number of pages | 10 |
Journal | Platelets |
Volume | 34 |
Issue number | 1 |
DOIs | |
Publication status | Published - 30 Nov 2023 |
Externally published | Yes |
Bibliographical note
FundingThis work was supported by the National Health and Medical Research Council of Australia and the Australian Research Council.