Inhibition of the plasma SCUBE1, a novel platelet adhesive protein, protects mice against thrombosis.
OBJECTIVE
Signal peptide-CUB-EGF domain-containing protein 1 (SCUBE1), a secreted and surface-exposed glycoprotein on activated platelets, promotes platelet-platelet interaction and supports platelet-matrix adhesion. Its plasma level is a biomarker of platelet activation in acute thrombotic diseases. However, the exact roles of plasma SCUBE1 in vivo remain undefined.


RESULTS
We generated new mutant (Δ) mice lacking the soluble but retaining the membrane-bound form of SCUBE1. Plasma SCUBE1-depleted Δ/Δ mice showed normal hematologic and coagulant features and expression of major platelet receptors, but Δ/Δ platelet-rich plasma showed impaired platelet aggregation in response to ADP and collagen treatment. The addition of purified recombinant SCUBE1 protein restored the aggregation of platelets in Δ/Δ platelet-rich plasma and further enhanced platelet aggregation in +/+ platelet-rich plasma. Plasma deficiency of SCUBE1 diminished arterial thrombosis in mice and protected against lethal thromboembolism induced by collagen-epinephrine treatment. Last, antibodies directed against the epidermal growth factor-like repeats of SCUBE1, which are involved in trans-homophilic protein-protein interactions, protected mice against fatal thromboembolism without causing bleeding in vivo.


CONCLUSIONS
We conclude that plasma SCUBE1 participates in platelet aggregation by bridging adjacent activated platelets in thrombosis. Blockade of soluble SCUBE1 might represent a novel antithrombotic strategy.
From the Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., R.-B.Y.); Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., C.-F.T., S.R.R., R.-B.Y.); Molecular Medicine Program, Taiwan International Graduate Program, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (C.-F.T.); Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan (C.-F.T.); Department of Applied Statistics and Information Science, Ming Chuan University, Taoyuan, Taiwan (M.-H.C.); and Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Meng-Ying
MY
Wu
From the Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., R.-B.Y.); Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., C.-F.T., S.R.R., R.-B.Y.); Molecular Medicine Program, Taiwan International Graduate Program, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (C.-F.T.); Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan (C.-F.T.); Department of Applied Statistics and Information Science, Ming Chuan University, Taoyuan, Taiwan (M.-H.C.); and Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Yuh-Charn
YC
Lin
From the Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., R.-B.Y.); Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., C.-F.T., S.R.R., R.-B.Y.); Molecular Medicine Program, Taiwan International Graduate Program, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (C.-F.T.); Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan (C.-F.T.); Department of Applied Statistics and Information Science, Ming Chuan University, Taoyuan, Taiwan (M.-H.C.); and Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Wei-Ju
WJ
Liao
From the Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., R.-B.Y.); Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., C.-F.T., S.R.R., R.-B.Y.); Molecular Medicine Program, Taiwan International Graduate Program, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (C.-F.T.); Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan (C.-F.T.); Department of Applied Statistics and Information Science, Ming Chuan University, Taoyuan, Taiwan (M.-H.C.); and Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Cheng-Fen
CF
Tu
From the Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., R.-B.Y.); Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., C.-F.T., S.R.R., R.-B.Y.); Molecular Medicine Program, Taiwan International Graduate Program, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (C.-F.T.); Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan (C.-F.T.); Department of Applied Statistics and Information Science, Ming Chuan University, Taoyuan, Taiwan (M.-H.C.); and Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Ming-Huei
MH
Chen
From the Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., R.-B.Y.); Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., C.-F.T., S.R.R., R.-B.Y.); Molecular Medicine Program, Taiwan International Graduate Program, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (C.-F.T.); Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan (C.-F.T.); Department of Applied Statistics and Information Science, Ming Chuan University, Taoyuan, Taiwan (M.-H.C.); and Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Steve R
SR
Roffler
From the Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., R.-B.Y.); Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (M.-Y.W., Y.-C.L., W.-J.L., C.-F.T., S.R.R., R.-B.Y.); Molecular Medicine Program, Taiwan International Graduate Program, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (C.-F.T.); Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan (C.-F.T.); Department of Applied Statistics and Information Science, Ming Chuan University, Taoyuan, Taiwan (M.-H.C.); and Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.). rbyang@ibms.sinica.edu.tw.
Ruey-Bing
RB
Yang
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002135:Calcium-Binding Proteins; D048430:Cell Shape; D004195:Disease Models, Animal; D005343:Fibrinolytic Agents / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood* / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009154:Mutation; D010974:Platelet Aggregation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D011655:Pulmonary Embolism / Q000097:blood / Q000235:genetics / Q000517:prevention & control*; D015398:Signal Transduction; D013927:Thrombosis / Q000097:blood / Q000235:genetics / Q000517:prevention & control*; D013997:Time Factors
D000911:Antibodies, Monoclonal; D002135:Calcium-Binding Proteins; D005343:Fibrinolytic Agents; D036341:Intercellular Signaling Peptides and Proteins; C417547:Scube1 protein, mouse
antibodies, neutralizing; blood platelets; mice, knockout; platelet aggregation; thrombosis