Platelet release of trimolecular complex components MT1-MMP/TIMP2/MMP2: involvement in MMP2 activation and platelet aggregation.
Matrix metalloproteinase 2 (MMP2) has been reported to be secreted by collagen-stimulated platelets, and active MMP2 has been shown to play a role in platelet aggregation. It has been demonstrated that MMP2 activation is dependent on the complex (membrane type 1 [MT1]-MMP/tissue inhibitor of MMP2 [TIMP2]) receptor and MMP2. We have investigated human platelets as a possible source of MT1-MMP, and we have studied its role in MMP2 activation and in platelet aggregation. Gelatin zymograms showed the existence of MMP2 at proforms (68 kd) and activated-enzyme forms (62-59 kd) in supernatants of resting and activated platelets, respectively. No gelatinolytic activity was associated with the platelet pellet after aggregation, suggesting a total release of MMP2 during cell activation. By Western blot analysis in nonreduced conditions, MT1-MMP was found on resting platelet membranes in 2 forms-the inactive 45-kd form and an apparent 89-kd form, which totally disappeared under reduced conditions. After platelet degranulation, only the 45-kd form was detected. Reverse transcription-polymerase chain reaction experiments showed the expression in platelets of messenger RNA encoding for MMP2, MT1-MMP, and TIMP2. Flow cytometry analysis showed that MT1-MMP, MMP2, and TIMP2 expressions were enhanced at the activated platelet surface. MMP inhibitors, recombinant TIMP2, and synthetic BB94 inhibited collagen-induced platelet aggregation in a concentration-dependent manner, indicating the role of activated MT1-MMP in the modulation of platelet function. In conclusion, our results demonstrate the expression of the trimolecular complex components (MT1-MMP/TIMP2/MMP2) by blood platelets as well as the ability of MMP inhibitors to modulate the aggregating response.
Kazes
I
I
INSERM U489 and Association Claude Bernard, Tenon Hospital, and Unité de Pharmacologie Cellulaire, Unité Associée, Pasteur Institute INSERM U485, Paris, France. kazes@b3e.jussieu.fr
Elalamy
I
I
Sraer
J D
JD
Hatmi
M
M
Nguyen
G
G
D001792:Blood Platelets / Q000502:physiology*; D003094:Collagen / Q000494:pharmacology; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D006801:Humans; D066298:In Vitro Techniques; D020778:Matrix Metalloproteinase 2 / Q000097:blood* / Q000235:genetics; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000097:blood* / Q000235:genetics; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology*; D011480:Protease Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D013876:Thiophenes / Q000494:pharmacology; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000097:blood* / Q000187:drug effects / Q000235:genetics
D011480:Protease Inhibitors; D012333:RNA, Messenger; D013876:Thiophenes; D019716:Tissue Inhibitor of Metalloproteinase-2; D010649:Phenylalanine; D003094:Collagen; C080985:batimastat; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2