KRDS, a new peptide derived from human lactotransferrin, inhibits platelet aggregation and release reaction

Abstract

KRDS (Lys-Arg-Asp-Ser), a tetrapeptide from human lactotransferrin, was tested in vitro on human platelet function, and its effects were compared to those of RGDS, a tetrapeptide from human fibrinogen. Both peptides had a high probability of initiating a p-turn and were highly hydrophilic. KRDS inhibited ADP-induced platelet aggregation [median inhibitory concentration (1C5,J 350 pM] and fibrinogen binding 360 pM) to a lesser extent than RGDS (IC50 75 pM and 20 pM, respectively). Different from RGDS, thrombin-induced serotonin release was inhibited by KRDS (750 pM) on normal platelets (55 loo/,) and type I Glanzmann's thrombasthenia platelets (43% f 1). However, KRDS had no effect on cytoplasmic Ca2 + mobilization, inositol phospholipid metabolism or protein phosphorylation (myosin light chain P20 and P43). In contrast to RGDS, KRDS does not inhibit the binding of monoclonal antibody PAC-1 to activated platelets. KRDS and RGDS inhibited 4P-phorbol-12-myristate-13-acetate (PMA)-induced aggregation and fibrinogen binding, while proteins were normally phosphorylated. Thus, the tetrapeptide KRDS is (a) an inhibitor of serotonin release by a mechanism independent of protein phosphorylation and (b) an inhibitor of fibrinogen binding and, hence, aggregation by a mechanism that may not necessarily involve its direct binding to the glycoprotein IIb-IIIa-complex.It is well established [l, 21 that fibrinogen interaction with platelets is essential for platelet aggregation and that fibrinogen binds to a specific receptor on the platelet surface: the glycoprotein IIb-IIIa complex (GPIIb-IIIa). Unstimulated platelets do not bind fibrinogen. In type I Glanzmann's thrombasthenia, characterized by the absence of platelet membrane GPIIb-IIIa, fibrinogen binding and ADP-or thrombininduced platelet aggregation are not observed. Yet the mechanisms of fibrinogen receptor exposure on the platelet surface and of fibrinogen interaction with GPIIb-IITa are not completely understood. Two binding sites have been identified on the fibrinogen molecule: a decapeptide in the carboxy-terminal region of the y-chain (LGGAKQAGDV; residues 402 -41 1) and a tetrapeptide in the carboxy-terminal region of the a-chain (RGDS; residues 572-575). Both peptides inhibit aggregation and fibrinogen binding to ADP-activated platelets [3]. Recently it has been shown that RGDS becomes more chemically cross-linked to residues 109-171 of GPIIIa number of similarities have been previously reported between these two clotting processes [6, 71. Moreover, structural homology has been found between cow K-casein and human fibrinogen y-chain [8]. Recently, Jolles et al. [9] showed that both the natural and the corresponding synthetic undecapeptide MAIPPKKNQDK of cow K-casein (residues 106-116) were more inhibitory of ADP-induced platelet aggregation and fibrinogen binding than the C-terminal dodecapeptide, HHLGGAKQAGDV, of the human fibrinogen y-chain (residues 400-411). Based on these observations, we looked for a peptide from a milk protein that is structurally and fun...

Lactotransferrin binding to its platelet receptor inhibits platelet aggregation

“…These results suggest that the new inhibition mechanism of platelet aggregation, recently described by Mazoyer et al [28], which does not involve GPIIb-GPIIIa, is mediated by the lactotransferrin receptor.…”

Inhibition Effects of KRDS, a Peptide Derived from Lactotransferrin, on Platelet Function and Arterial Thrombus Formation in Dogs

“…The platelet aggregation can be inhibited by RGDS, a tetrapeptide at the carboxyl-ter minus region of the alpha-chain of fibrinogen, through the interaction of RGDS with the GPIIb/IIIa complex. KRDS, a tetrapeptide derived from lactotransferrin, is similar to RGDS peptide both in the light of structure and function [3,4], The KRDS peptide was reported to inhibit human platelet aggrega tion and fibrinogen binding to ADP-activated platelets [3,4], In this study it was found that the second-phase platelet aggregation was in hibited by KRDS peptide while the firstphase platelet aggregation could not be inhib ited by KRDS even at a higher concentration in dogs. In general, it is considered that the second-phase platelet aggregation is related to the secretion of internal agonists of platelets such as ADP while the first-phase aggregation is related to the direct interaction of agonist with platelets.…”

“…Therefore, investiga tion on new antiplatelet agents is advanta geous to prevent and treat thrombotic disor ders such as acute myocardial infarction. KRDS, a tetrapeptide (Lys-Arg-Asp-Ser), is derived from human lactotransferrin [2][3][4], Previously published reports indicate that platelet aggregation in vitro and thrombus formation in experimental thrombosis in duced by laser are inhibited by KRDS in rats and guinea pigs [3]. The role of KRDS on platelets related to the inhibition of release reaction more closely through a mechanism independent of cytoplasmic Ca2+ mobiliza tion and protein phosphorylation [4], There fore, the precise mechanism of KRDS on anti platelet activity has not been quite clear yet.…”

Peptides: Production, bioactivity, functionality, and applications

“…However, blood coagulation and clot formation are considered undesirable circumstances in some medical conditions and therefore, antithrombotic agents, especially natural ones, are favored. In this regard, bioactive peptides have been found to have antithrombotic effect (Jolles et al, 1986;Raha et al, 1988;Mazoyer et al, 1990;Chabance et al, 1995;Morimatsu et al, 1996;Shimizu et al, 2009). There are two types of antithrombotic agents: anticoagulants and antiplatelets.…”