The CEACAM1-derived peptide QLSN impairs collagen-induced human platelet activation through glycoprotein VI.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) regulates collagen-mediated platelet activation through its cytoplasmic immunoreceptor tyrosine-based inhibition motifs (ITIMs). However, the function of CEACAM1's extracellular cleavage fragments is currently unknown. In the present study, we used mass spectrometry (MS) to identify 9 cleavage fragments shed by matrix metallopeptidase 12 (MMP-12), and then we synthesized peptides with sequences corresponding to the fragments. QLSNGNRTLT (QLSN), a peptide from the A1-domain of CEACAM1, significantly attenuated collagen-induced platelet aggregation. QLSN also attenuated platelet static adhesion to collagen. Additionally, QLSN reduced human platelet secretion and integrin α_IIbβ₃ activation in response to glycoprotein VI (GPVI)-selective agonist, convulxin. Correspondingly, QLSN treatment significantly decreased convulxin-mediated phosphorylation of Src, protein kinase B (Akt), spleen tyrosine kinase (Syk) and phospholipase Cγ2 (PLCγ2) in human platelets. These data indicate that the CEACAM1-derived peptide QLSN inhibits GPVI-mediated human platelet activation. QLSN could potentially be developed as a novel antiplatelet agent.

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