The overall goal of our research is the delineation of biochemical pathways which operate in the process initiated by the binding of an agonist to surface receptors, and leading to platelet secretion, activation of fibrinogen binding sites and aggregation. As part of my ongoing studies in this line of investigation, we have prepared and isolated a stimulatory monoclonal antibody (M.Ab.), named F-11. M.A.b F-11 acts as an agonist which induces secretion and aggregation of human platelets. The clinical significant of antibodies which activate platelets is well documented, but detailed characterization of the surface antigens that serve as receptors in this process and biochemical pathways triggered by such antibodies has not yet been delineated. We expect that detailed studies of M.Ab. F-11 will begin to fill these gaps. The use of M.Ab F-11 provides two distinct advantages: (1) The protein recognized by M.Ab. F-11 on the platelet surface has been identified and partially purified in our laboratory. Thus, our studies focus now on an activation process initiated by a receptor whose molecular entity is already known. (2) The activation of human platelets by purified IgG of M.Ab. F-11 involves a lag period of 6 to 20 minutes. This latency period permits detailed measurements of the sequence of molecular events leading to platelet secretion and aggregation. Accordingly, the Research Plan submitted here is designed to achieve the following specific goals: (a) Purification of a non-denatured form of the F-11 receptor, (b) characterization of the F-11 antigen and investigation as to whether it is a unique receptor, part of the receptor complex for one of the naturally-occurring platelet agonists, or a component of a known signal transduction system, (c) Determination of the biochemical pathway(s) operating in the activation of platelets by F-11, (d) development of polyclonal and monoclonal antibodies to the purified F-11 receptor, for use in functional domains of the platelet F-11 antigen, (e) cloning, sequencing and chromosomal localization of the gene for the F-11 receptor. We expect that accomplishment of these research goals will provide new and significant information on basic mechanisms operating during platelet activation. The health-related implications of these studies are particularly relevant to pathophysiological states involving interaction of antibodies with circulating platelets.
| Sobocka, Malgorzata B; Sobocki, Tomasz; Babinska, Anna et al. (2004) Signaling pathways of the F11 receptor (F11R; a.k.a. JAM-1, JAM-A) in human platelets: F11R dimerization, phosphorylation and complex formation with the integrin GPIIIa. J Recept Signal Transduct Res 24:85-105 |
| Wang, F; Naik, U P; Ehrlich, Y H et al. (1995) Stimulatory antibody-induced activation and selective translocation of protein kinase C isoenzymes in human platelets. Biochem J 311 ( Pt 2):401-6 |
| Naik, U P; Ehrlich, Y H; Kornecki, E (1995) Mechanisms of platelet activation by a stimulatory antibody: cross-linking of a novel platelet receptor for monoclonal antibody F11 with the Fc gamma RII receptor. Biochem J 310 ( Pt 1):155-62 |
| Wang, F; Naik, U P; Ehrlich, Y H et al. (1993) A new protein kinase C, nPKC eta', and nPKC theta are expressed in human platelets: involvement of nPKC eta' and nPKC theta in signal transduction stimulated by PAF. Biochem Biophys Res Commun 191:240-6 |
