Effect of F11 Receptor/Junctional Adhesion Molecule-A-derived Peptide on Neointimal Hyperplasia in a Murine Model.

Purpose: To determine whether inhibition of the F11 receptor/JAM-A (F11R) using F11R-specific antagonist peptide 4D results in inhibition of smooth muscle cell (SMC) proliferation and migration in vivo, known as neointimal hyperplasia (NIH), using a mouse focal carotid artery stenosis model (FCASM).

Materials And Methods: The mouse FCASM was chosen to test the hypothesis because the dominant cell type at the site of stenosis is SMC, similar to that in vascular access stenosis. Fourteen C57BL/6 mice underwent left carotid artery (LCA) partial ligation to induce stenosis, followed by daily injection of peptide 4D in 7 mice and saline in the remaining 7 mice, and these mice were observed for 21 days and then euthanized.

data: treatment with the F11R/JAM-A peptide 4D decreases mortality and reduces the generation of atherosclerotic plaques in ApoE-deficient mice.

The data in this article focus on the F11 Receptor (F11R/JAM-A; Junctional Adhesion Molecule-A; JAM-A, F11R), a cell adhesion protein constitutively expressed on the membrane surface of circulating platelets and localized within the tight junctions of healthy endothelial cells (ECs). Previous reports have shown that F11R/JAM-A plays a critical role in the adhesion of platelets to an inflamed endothelium due to its' pathological expression on the luminal surface of the cytokine-inflamed endothelium. Since platelet adhesion to an inflamed endothelium is an early step in the development of atherosclerotic plaque formation, and with time, resulting in heart attacks and stroke, we conducted a long-term, study utilizing the atherosclerosis-prone ApoE mice to attempt a blockade of the formation of atherosclerotic plaques by preventing the adhesion of platelets to the inflamed vasculature .

A peptide antagonist of F11R/JAM-A reduces plaque formation and prolongs survival in an animal model of atherosclerosis.

Background And Aims: The F11 Receptor (F11R), AKA Junctional Adhesion Molecule-A (JAM-A) (F11R/JAM-A), is an adhesion protein constitutively expressed on the membrane surface of circulating platelets and the luminal surface of inflamed endothelial cells (EC). Platelet adhesion to an inflamed endothelium is one of the early steps of atherosclerotic plaque formation. Our previous studies, conducted with cultured EC in vitro, have demonstrated the expression of F11R/JAM-A on the luminal surface of inflamed EC, platelet adhesion to inflamed EC through F11R/JAM-A interactions, and inhibition of this interaction by the presence of F11R/JAM-A antagonistic peptide (F11Rpeptide 4D).

Development of new antiatherosclerotic and antithrombotic drugs utilizing F11 receptor (F11R/JAM-A) peptides.

Peptides with enhanced resistance to proteolysis, based on the amino acid sequence of the F11 receptor molecule (F11R, aka JAM-A/Junctional adhesion molecule-A), were designed, prepared, and examined as potential candidates for the development of anti-atherosclerotic and anti-thrombotic therapeutic drugs. A sequence at the N-terminal of F11R together with another sequence located in the first Ig-loop of this protein, were identified to form a steric active-site operating in the F11R-dependent adhesion between cells that express F11R molecules on their external surface. In silico modeling of the complex between two polypeptide chains with the sequences positioned in the active-site was used to generate peptide-candidates designed to inhibit homophilic interactions between surface-located F11R molecules.

Transcription and translation of human F11R gene are required for an initial step of atherogenesis induced by inflammatory cytokines.

Background: The F11 Receptor (F11R; aka JAM-A, JAM-1) is a cell adhesion protein present constitutively on the membrane surface of circulating platelets and within tight junctions of endothelial cells (ECs). Previous reports demonstrated that exposure of ECs to pro-inflammatory cytokines causes insertion of F11R molecules into the luminal surface of ECs, ensuing with homologous interactions between F11R molecules of platelets and ECs, and a resultant adhesion of platelets to the inflamed ECs. The main new finding of the present report is that the first step in this chain of events is the de-novo transcription and translation of F11R molecules, induced in ECs by exposure to inflammatory cytokines.

Silencing of the F11R gene reveals a role for F11R/JAM-A in the migration of inflamed vascular smooth muscle cells and in atherosclerosis.

Rationale And Objective: Our previous studies have determined that the F11 receptor (F11R; aka JAM-A) exerts a critical force in the adhesion of human platelets to inflamed endothelial cells (ECs), and thus can play a significant role in the initiation of atherosclerotic plaque formation. In the present study, we focus on a subsequent event in plaque development--the migration of smooth muscle cells (SMCs) from the media to the intima of inflamed vessels. Here we report our investigation of the expression of F11R in atherosclerotic arteries of coronary artery disease (CAD) patients, and of the role of F11R in the migration of SMCs involved in atherogenesis.

Elevated plasma level of soluble F11 receptor/junctional adhesion molecule-A (F11R/JAM-A) in hypertension.

Background: The F11 receptor (F11R, also known as junctional adhesion molecule A (JAM-A)) plays a role in the development of hypertension in rat. Genetic variants in the human F11R gene were demonstrated to influence systolic blood pressure. In the present study, we investigated the relationship between F11R and hypertension by examining the levels of a circulating soluble form of F11R (sF11R) in hypertensive patients.

Association of plasma levels of F11 receptor/junctional adhesion molecule-A (F11R/JAM-A) with human atherosclerosis.

Objectives: The purpose of this study was to determine the association of the F11 receptor (F11R) with human vascular disease.

Background: A molecule identified as critical for platelet adhesion to a cytokine-inflamed endothelial surface in vitro is F11R. The F11R is known to be expressed in platelets and endothelium and reported recently to be overexpressed in atherosclerotic plaques.

Relationship between the soluble F11 receptor and markers of inflammation in hemodialysis patients.

Background: The human F11 receptor (F11R) is an important cell adhesion molecule implicated in inflammatory thrombosis. We hypothesize that serum levels of the soluble released form of F11R (sF11R) are elevated in dialysis patients since these patients have higher cardiovascular disease burdens than the general population. In this study, we examined whether sF11R levels were elevated in hemodialysis (HD) patients and correlated with known inflammatory cytokines.

The F11 receptor (F11R/JAM-A) in atherothrombosis: overexpression of F11R in atherosclerotic plaques.

F11R is the gene name for an adhesion protein, called the F11-receptor, aka JAM-A, which under normal physiological conditions is expressed constitutively on the surface of platelets and localized within tight junctions of endothelial cells (EC). Previous studies of the interactions between human platelets and EC suggested that F11R/JAM-A plays a crucial role in inflammatory thrombosis and atherosclerosis. The study reported here obtained in-vivo confirmation of this conclusion by investigating F11R/JAM-A protein and mRNA in patients with aortic and peripheral vascular disease and in an animal model of atherosclerosis.

Genomic structure, organization and promoter analysis of the human F11R/F11 receptor/junctional adhesion molecule-1/JAM-A.

The F11-receptor (F11R) (a.k.a.

Expression of a recombinant protein of the platelet F11 receptor (F11R) (JAM-1/JAM-A) in insect cells: F11R is naturally phosphorylated in the extracellular domain.

The F11 receptor (F11R/JAM) is a member of the immunoglobulin superfamily localized on the membrane surface of human platelets and a component of tight junctions of endothelial and epithelial cells. F11R was demonstrated to participate in the adhesion of human platelets to cytokine-inflamed endothelial cells (EC), indicating an important role for F11R in inflammatory thrombosis and atherosclerosis. Domains responsible for the formation of tight junctions, the adhesion of platelets to EC, activation of platelets resulting in granule release, the activation of IIb/3 integrin and platelet aggregation, were identified in the external portion of F11R.

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.

The F11 receptor (F11R) (a.k.a.

F11-receptor (F11R/JAM) mediates platelet adhesion to endothelial cells: role in inflammatory thrombosis.

The F11 receptor (F11R) is a cell adhesion molecule (CAM), member of the immunoglobulin superfamily found on the surface of human platelets, and determined to play a role in platelet aggregation, secretion, adhesion and spreading. The same molecule is present also at tight junctions of endothelial cells (EC) where it is known as JAM and acts as a CAM through homophilic interactions. The role of F11R/JAM in the interaction of platelets with endothelial cells was investigated in the current studies.

Two regions of the human platelet F11-receptor (F11R) are critical for platelet aggregation, potentiation and adhesion.

The F11 receptor (F11R) was first identified on the surface of human platelets as a target for a stimulatory monoclonal antibody (M.Ab.F11) that induces secretion, followed by exposure of fibrinogen receptors and aggregation.

Cloning of the human platelet F11 receptor: a cell adhesion molecule member of the immunoglobulin superfamily involved in platelet aggregation.

This study demonstrates that the human platelet F11 receptor (F11R) functions as an adhesion molecule, and this finding is confirmed by the structure of the protein as revealed by molecular cloning. The F11R is a 32-/35-kd protein duplex that serves as the binding site through which a stimulatory monoclonal antibody causes platelet aggregation and granule secretion. A physiological role for the F11R protein was demonstrated by its phosphorylation after the stimulation of platelets by thrombin and collagen.

Platelet-activating factor in infants at risk for necrotizing enterocolitis.

Background: Platelet-activating factor (PAF) is a heterogeneous phospholipid that has been implicated as participating in a number of perinatal disease processes including necrotizing enterocolitis (NEC).

Methods: Baseline blood levels of PAF and related lipids (PAF-LL) were measured for 164 infants at risk for NEC from 3 neonatal intensive care units. Serial levels were obtained from the 11 infants in whom NEC developed.

Identification of ecto-PKC on surface of human platelets: role in maintenance of latent fibrinogen receptors.

Human platelets express a protein phosphorylation system on their surface. A specific protein kinase C (PKC) antibody, monoclonal antibody (MAb) 1.9, which binds to the catalytic domain of PKC and inhibits its activity, causes the aggregation of intact platelets while inhibiting the phosphorylation of platelet surface proteins.

Enhancement of human platelet aggregation and secretion induced by rapamycin.

Background: Rapamycin is a new immunosuppressive drug of the macrolide type. Despite binding to one of the FK-binding proteins as the initial step in intracellular action, further effects differ from those of the other fungally derived macrolides, cyclosporine and tacrolimus. We have previously demonstrated an enhancement of agonist-mediated platelet activation by cyclosporine and tacrolimus which was associated with increased phosphorylation of two intracellular platelet proteins, p20 and p40.

Activation of human platelets by protein kinase C antibody: role for surface phosphorylation in homeostasis.

A monoclonal antibody that inhibits protein kinase C (PKC) activity, as well as PKC pseudosubstrate inhibitory peptides, was found to cause aggregation of human platelets followed by granular secretion. Binding of this antibody to the platelet surface was demonstrated directly by flow cytometry and immunofluorescence microscopy. Assays of ecto-protein kinase activity revealed that this antibody inhibits the phosphorylation of five proteins on the platelet surface.

Platelet activating factor (PAF) in memory formation: role as a retrograde messenger in long-term potentiation.

Long-term potentiation (LTP) is a neurophysiological process that has been implicated in memory formation. The elevation of intracellular Ca2+ levels in postsynaptic neurons, an essential step in the induction of LTP in the hippocampus, can lead to activation of the enzyme acetyl-CoA:lyso-PAF acetyltransferase that is required for PAF synthesis in neurons. Thus, during the induction of LTP, stimulation of Ca2+ influx by glutamate receptors would lead to a postsynaptic increase in PAF biosynthesis.

Surface protein phosphorylation by ecto-protein kinase is required for the maintenance of hippocampal long-term potentiation.

During the induction of long-term potentiation (LTP) in hippocampal slices adenosine triphosphate (ATP) is secreted into the synaptic cleft, and a 48 kDa/50 kDa protein duplex becomes phosphorylated by extracellular ATP. All the criteria required as evidence that these two proteins serve as principal substrates of ecto-protein kinase activity on the surface of hippocampal pyramidal neurons have been fulfilled. This phosphorylation activity was detected on the surface of pyramidal neurons assayed after synaptogenesis, but not in immature neurons nor in glial cells.