Niamh Moran

Royal College of Surgeons in Ireland | RCSI · Department of Molecular and Cellular Therapeutics

Background Assessment of ‘high on-treatment platelet reactivity (HTPR)’ could enhance understanding of the pathophysiology of first or recurrent vascular events in carotid stenosis patients on antiplatelet therapy. Methods This prospective, multi-centre study assessed antiplatelet–HTPR status and its relationship with micro-emboli signals (MES) in...

Therapeutic modulation of protein interactions is challenging, but short linear motifs (SLiMs) represent potential targets. Focal adhesions play a central role in adhesion by linking cells to the extracellular matrix. Integrins are central to this process, and many other intracellular proteins are components of the integrin adhesome. We applied a p...

Sequence-specificity of the syndecan-4 derived peptide pal-SDC4_tail. (PDF)

Effects of combining pal-ITGA2B_JM and tat peptides in tests for synergy. (PDF)

Differential platelet activation by ACTN1_VBS peptide depending on N or C terminal addition of the tat cell-penetrating peptide. (PDF)

Aggregation results before and after TRAP activation for all peptides. (PDF)

Effects of combinations of peptides on inhibition of platelet activation. (PDF)

Intracellular localisation of tat-ACTN1-VBS peptide. (PDF)

Inhibitory effects of peptide combinations on the activation of platelets: Comparison with peptides at single concentrations. (PDF)

Physical interaction of syntenin-1 with peptide from the tail of syndecan 4. (PDF)

Phosphorylation changes during platelet activation in response to peptide. (PDF)

Effects of combinations of peptides on platelet activation. (PDF)

Peptide activities & literature-described interactions of syndecan peptide regions with protein interaction partners. (PDF)

Effects of chimeric peptides between integrin alpha and other adhesome components. (PDF)

Inhibitory effects of peptide combinations on TRAP activation of platelets: Comparison with peptides at double concentrations. (PDF)

Chimeric peptides from syndecan 4 cytoplasmic region. (PDF)

Phenotypic consequences of deleting adhesome components. (PDF)

Excel-formatted workbook of adhesome of datasets used in generating figures. (XLSX)

The juxtamembrane domains (JMD) of transmembrane proteins are rich in critical peptide sequences that participate in dynamic cell signalling events. Synthetic JMD peptides derived from cadherin cell adhesion proteins have previously been shown to modulate platelet function. In this study, we aimed to develop functional bioactive agents from bioinfo...

Human blood platelets and SK-N-AS neuroblastoma cancer cell capture at spontaneously adsorbed monolayers of fibrinogen binding motifs GRGDS (generic integrin adhesion), HHLGGAKQAGDV (exclusive to platelet integrin αIIbβ3) or octanethiol (adhesion inhibitor) at planar gold and ordered 1.6 micron diameter spherical cap gold cavity arrays was compared...

Platelets have been demonstrated to be vital in cancer epithelial-mesenchymal transition (EMT), an important step in metastasis. Markers of EMT are associated with chemotherapy resistance. However, the association between the development of chemoresistance, EMT, and the contribution of platelets to the process, is still unclear. Here we report that...

Ordered spherical cap gold cavity arrays with 5.4, 1.6 and 0.98 µm diameter apertures were explored as capture surfaces for human blood platelets to investigate the impact of surface geometry and chemical modification on platelet capture efficiency and their potential as platforms for surface enhanced Raman spectroscopy of single platelets. The sub...

Background: Platelets are essential for maintaining haemostasis and play a key role in the pathogenesis of cardiovascular disease. Upon ligation of platelet receptors through subendothelial matrix proteins, intracellular reactive oxygen species (ROS) are generated, further amplifying the platelet activation response. Thrombin, a potent platelet ac...

The diversity of integrins and their complex role in many diseases suggests great potential for this superfamily as drug targets. The initial successes of anti-integrin therapeutics in the treatment of thrombotic disorders suggested that similar anti-integrin agents could be developed for the treatment of inflammatory disorders. While initially a p...

Identifying effective therapeutic drug combinations that modulate complex signaling pathways in platelets is central to the advancement of effective anti-thrombotic therapies. However, there is no systems model of the platelet that predicts responses to different inhibitor combinations. We developed an approach which goes beyond current inhibitor-i...

Platelet integrin αIIbβ3 is a key mediator of platelet activation and thrombosis. Upon activation αIIbβ3 undergoes significant conformational rearrangement, inducing complex bidirectional signalling and protein recruitment leading to platelet activation. Reconstituted lipid models of the integrin can enhance our understanding of the structural and...

Protein-protein and protein-peptide interactions are responsible for the vast majority of biological functions in vivo, but targeting these interactions with small molecules has historically been difficult. What is required are efficient combined computational and experimental screening methods to choose among a number of potential protein interfac...

Polymer-peptide conjugates are a promising class of compounds, where polymers can be used to overcome some of the limitations associated with peptides intended for therapeutic and/or diagnostic applications. Linear polymers such as poly(ethylene glycol) can be conjugated through terminal moieties and have therefore limited loading capacities. In th...

Blood platelet adhesion is crucial in dictating haemocompatibility of medical implants and in platelet capture in diagnostics. Understanding the role of platelet activation in dictating platelet adhesion at chemically modified interfaces is important but relatively unexplored. Using scanning electron microscopy and confocal fluorescence microscopy...

Bioactive peptides in the juxtamembrane regions of proteins are involved in many signaling events. The juxtamembrane regions of cadherins were examined for the identification of bioactive regions. Several peptides spanning the cytoplasmic juxtamembrane regions of E- and N-cadherin were synthesized and assessed for the ability to influence TGFβ resp...

Introduction The importance of thrombin generation in the pathogenesis of TIA or stroke and its relationship with cerebral microembolic signals (MES) in asymptomatic and symptomatic carotid stenosis has not been comprehensively assessed. Methods Plasma thrombin generation parameters from patients with moderate or severe (≥50%) asymptomatic carotid...

The ability of two novel ruthenium(II) polypyridyl-Arg-Gly-Asp (RGD) peptide conjugates to act as molecular probes for reporting on the presence and conformation of integrin αIIbβ3 in solution and in live cells was described. The compounds are [Ru(bpy)2PIC-RGD]2+, bpy-RGD, and [Ru(dpp)2PIC-RGD]2+, dpp-RGD, where dpp is 4,7 diphenyl-1,10-phenanthrol...

Background and purposevon Willebrand factor propeptide (VWF:Ag II) is potentially a more sensitive marker of acute endothelial activation than von Willebrand factor antigen (VWF:Ag). These biomarkers have not been simultaneously assessed in asymptomatic versus symptomatic carotid stenosis patients. The relationship between endothelial activation an...

Platelets play a role in cancer by acting as a dynamic reservoir of effectors that facilitate tumor vascularization, growth, and metastasis. However, little information is available about the mechanism of tumor cell-induced platelet secretion (TCIPS) or the molecular machinery by which effector molecules are released from platelets. Here we demonst...

Significance: The regulation of platelet function is finely tuned by a balance between the vasculature's redox environment and the oxidative processes that occur in it. The activation of platelets at sites of vascular damage is essential for the maintenance of normal hemostasis. In the extracellular milieu, a normal redox environment is maintained...

Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations of the CF transmembrane conductance regulator (CFTR) gene[1]. It is the most prevalent single gene disorder found worldwide that affects more than 70,000 individuals[2]. To date more than 1500 mutations in the CFTR gene have been identified. However the functional importanc...

Background: Cerebral microembolic signals (MES) may predict increased stroke risk in carotid stenosis. However, the relationship between platelet counts or platelet activation status and MES in symptomatic vs. asymptomatic carotid stenosis has not been comprehensively assessed. Setting: University teaching hospitals. Methods: This prospective,...

Pregnancy-specific glycoproteins (PSGs) are immunoglobulin superfamily members encoded by multigene families in rodents and primates. In human pregnancy, PSGs are secreted by the syncytiotrophoblast, a fetal tissue, and reach a concentration of up to 400 ug/ml in the maternal bloodstream at term. Human and mouse PSGs induce release of anti-inflamma...

Pregnancy-specific glycoproteins (PSGs) are immunoglobulin superfamily members encoded by multigene families in rodents and primates. In human pregnancy, PSGs are secreted by the syncytiotrophoblast, a fetal tissue, and reach a concentration of up to 400 ug/ml in the maternal bloodstream at term. Human and mouse PSGs induce release of anti-inflamma...

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Protein tyrosine phosphatase receptor delta (PTPRD) is a member of a large family of protein tyrosine phosphatases which negatively regulate tyrosine phosphorylation. Neuroblastoma is a major childhood cancer arising from precursor cells of the sympathetic nervous system which is known to acquire deletions and alterations in the expression patterns...

(A) Expression of AURKA mRNA 48 hours post PTPRD expression. Either 1 μg of PTPRD or empty vector (E.V.) were transfected into Kelly cells. mRNA was extracted at 48 hours and qPCR was performed. The figure is representative of four independent experiments and E.V. is set as 1.0. (B) Expression of MYCN mRNA 48 hours post PTPRD expression. Either 1 μ...

Expression of PTPRD (A) mRNA and (B) protein following transfection of Kelly cells with increasing concentrations of PTPRD cDNA. mRNA was extracted at 24 hours and qPCR was performed. Lysates were harvested at 48 h and subjected to SDS PAGE and western blot analysis with a monoclonal antibody to the V5 epitope tag or alpha tubulin. All experiments...

Platelet signalling responses to single agonists have been identified previously. However, a model of the total platelet signalling network is still lacking. In order to gain insights into this network, we explored the effects of a range of platelet-function inhibitors in two independent assays of platelet function, namely fibrinogen binding and AD...

Elevated levels of plasma homocysteine (Hcy) are an independent risk factor for cardiovascular disease and thrombosis. The molecular basis for this phenomenon is not known but may relate to modification of cell surface thiols. The platelet specific integrin α(IIb)β₃ is a cysteine-rich cell adhesion molecule that plays a critical role in platelet ag...

The integrins are a large family of cell adhesion molecules that are essential for the regulation of cell growth and function. The identification of key roles for integrins in a diverse range of diseases, including cancer, infection, thrombosis and autoimmune disorders, has revealed their substantial potential as therapeutic targets. However, so fa...

Integrins are transmembrane proteins regulating cellular shape, mobility and the cell cycle. A highly conserved signature motif in the cytoplasmic tail of the integrin alpha-subunit, KXGFFKR, plays a critical role in regulating integrin function. To date, six proteins have been identified that target this motif of the platelet-specific integrin alp...

The capacity of platelets to form a thrombus is mediated by integrin alpha(IIb)beta(3). The cytoplasmic tail of alpha(IIb) contains a highly conserved motif, (989)KVGFFKR(995), which plays a critical role in regulating integrin activation and acts as a recognition site for various intracellular proteins, e.g. CIB1, PP1, ICln and RN181. Previously,...

The electrochemically induced desorption of Oregon green labeled fibrinogen layers from clean gold surfaces at negative potentials has been probed using capacitance, fluorescence microscopy, and atomic force microscopy. Capacitance measurements on fibrinogen layers indicate that desorption occurs at potentials more negative than -0.8 V and that com...

A synthetic cell-permeable peptide corresponding to the highly conserved alpha-integrin signature motif, Palmityl-K(989)VGFFKR(995) (Pal-FF), induces integrin activation and aggregation in human platelets. Systematic replacement of the F(992)-F(993) with amino acids of greater or lesser hydrophobicity to create Pal-KVGxxKR peptides demonstrate that...

Two novel polyarginine labelled ruthenium polypyridyl dyes are reported, one conjugated to five, (Ru-Ahx-R5), and one to eight arginine residues, (Ru-Ahx-R8); both complexes exhibit long-lived, intense, and oxygen-sensitive luminescence; (Ru-R8) is passively, efficiently and very rapidly transported across the cell membrane into the cytoplasm witho...

The volume-regulating protein, ICln, interacts with the conserved KxGFFKR alpha-integrin signature motif. ICln is an abundant protein (4455 +/- 650 molecules/platelet) found exclusively in the soluble cytosolic fraction of unactivated platelets. In contrast, its binding partner, the platelet integrin alpha(IIb)beta(3), is present in detergent-insol...

We previously identified proteins that bind with high affinity to a peptide corresponding to the cytoplasmic regulatory domain (KVGFFKR) of the platelet-specific integrin subunit alpha(IIb). These included a hypothetical protein termed HSPC238, recently renamed as RING finger protein, RN181. Here, we establish the presence of RN181 in human platele...

To understand the regulation of integrin alpha(IIb)beta(3), a critical platelet adhesion molecule, we have developed a peptide affinity chromatography method using the known integrin regulatory motif, LAMWKVGFFKR. Using standard Fmoc chemistry, this peptide was synthesized onto a Toyopearl AF-Amino-650 M resin on a 6-aminohexanoic acid (Ahx) linker...

The exact mechanisms regulating conformational changes in the platelet-specific integrin alphaIIbbeta3 are not fully understood. However, a role exists for thiol/disulfide exchange in integrin conformational changes leading to altered disulfide bonding patterns, via its endogenous thiol isomerase activity. Nitric oxide (NO) accelerates this intrins...

Short synthetic oligopeptides based on regions of human proteins that encompass functional motifs are versatile reagents for understanding protein signaling and interactions. They can either mimic or inhibit the parent protein's activity and have been used in drug development. Peptide studies typically either derive peptides from a single identifie...

Platelets play a central role in maintaining biological hemostasis. Inappropriate platelet activation is responsible for thrombotic diseases such as myocardial infarction and stroke. Therefore, novel agents that can inhibit platelet activation are necessary. However, assays that monitor platelet aggregation are generally time-consuming and require...

The highly conserved integrin alpha-subunit membrane-proximal motif KVGFFKR plays a decisive role in modulating the activation of integrin alphaIIbbeta3. Previously, we have shown that a platelet permeable palmityl (pal)-peptide with this seven amino acid sequence can directly activate alphaIIbbeta3 leading to platelet aggregation. To investigate f...

Platelet activation causes conformational changes of integrin GPIIb/IIIa (alpha(IIb)beta3), resulting in the exposure of its ligand-binding pocket. This provides the unique possibility to design agents that specifically block activated platelets only. We used phage display of single-chain antibody (scFv) libraries in combination with several rounds...

Sequences of human proteins are frequently prepared as synthetic oligopeptides to assess their functional ability to act as compounds modulating pathways involving the parent protein. Our objective was to analyze a set of oligopeptides, to determine if their solubility or activity correlated with features of their primary sequence, or with features...

The functional regulation of integrins is a major determinant of cell adhesion, migration and tissue maintenance. The binding of cytoskeletal proteins to various sites of integrin cytoplasmic domains is a key mechanism of this functional regulation. Expression of recombinant integrin alpha(IIb)beta(3) and alpha(M)beta(2) lacking the GFFKR-region in...

The platelet-specific integrin alphaIIb beta3 has endogenous thiol isomerase activity associated with the CXXC motifs within the beta subunit. Using a highly purified form of bacitracin, a thiol isomerase inhibitor, we now provide further evidence of the functional significance of this enzymatic activity in integrin activation. In addition, we demo...

Occlusion of a blood vessel due to thrombosis can reduce or completely stop blood supply to different tissues or organs with the clinical consequences of myocardial infarction or stroke. Platelets are the cellular component which initiate thrombus formation, they activate in response to a variety of signals, such as interactions with a damaged bloo...

Newly developed proteomic technologies now permit the routine identification of hundreds or even thousands of proteins in a single experiment. However, the global study of any proteome has unique challenges that set it apart from comprehensive studies of genes and transcripts. The detection of low-abundance, biologically relevant proteins poses a p...

A critical role for the conserved alpha-integrin cytoplasmic motif, KVGFFKR, is recognized in the regulation of activation of the platelet integrin alpha(IIb)beta(3). To understand the molecular mechanisms of this regulation, we sought to determine the nature of the protein interactions with this cytoplasmic motif. We used a tagged synthetic peptid...

The platelet integrin alphaIIbbeta3 alters conformation in response to platelet activation and ligand binding, although the molecular mechanisms involved are not known. We previously showed that a lipid modified peptide, corresponding to the membrane proximal 989KVGFFKR995 portion of the alphaIIb cytoplasmic tail, independently activates platelet a...

Extensive study in integrin research has seen the platelet specific receptor alpha(IIb)beta(3) (Glycoprotein GPIIb/IIIa) under much scrutiny, and provided vast information as to the workings of this integrin within the blood. Glanzmann's thrombasthenia, a rare autosomal recessive bleeding disorder, highlights the vital role played by this receptor...

The molecular mechanisms involved in regulating the activation-dependent conformational switch in integrins are not known although recent evidence suggests that integrins are a direct target for redox modulation. We have identified an endogenous integrin thiol isomerase activity that may be responsible for regulating integrin activation states. The...

The platelet receptor GPIb/IX/V mediates a crucial role in hemostasis, yet the signaling mechanisms involved are incompletely understood. The complex consists of four polypeptides GPIb alpha, GPIb beta, GPIX and GPV. We identified an amino acid sequence in the cytoplasmic tail of the GPIb beta subunit between residues R151 and A161 that is highly c...

  The platelet receptor GPIb/IX/V mediates a crucial role in hemostasis, yet the signaling mechanisms involved are incompletely understood. The complex consists of four polypeptides GPIbα, GPIbβ, GPIX and GPV. We identified an amino acid sequence in the cytoplasmic tail of the GPIbβ subunit between residues R151 and A161 that is highly conserved ac...

Glycoprotein (GP) Ib-V-IX is a unique adhesion receptor complex on platelets. Mutations in GPIbalpha, Ibbeta, and IX can lead to the rare bleeding disorder, Bernard-Soulier Syndrome (BSS). Here, we report a novel hemizygous variant of BSS in which Pro29 in one GPIbbeta allele is substituted by a Leu (GPIbbeta:P29L). Fluoresence in situ hybridisatio...

Glycoprotein (GP) Ib-V-IX is a unique adhesion receptor complex on platelets. Mutations in GPIbα, Ibβ, and IX can lead to the rare bleeding disorder, Bernard-Soulier Syndrome (BSS). Here, we report a novel hemizygous variant of BSS in which Pro29 in one GPIbβ allele is substituted by a Leu (GPIbβ:P29L). Fluoresence in situ hybridisation revealed th...

We have identified a patient designated as (GTa) with Glanzmann's Thrombasthenia (GT) diagnosed on the basis of a prolonged bleeding time and failure of the patient's platelets to aggregate. The number of glycoprotein (GP)IIb/IIIa receptors on the platelet surface was 37% of normal and those receptors displayed a defect in soluble fibrinogen bindin...

Integrins are cysteine-rich heterodimeric cell-surface adhesion molecules that alter their affinity for ligands in response to cellular activation. The molecular mechanisms involved in this activation of integrins are not understood. Treatment with the thiol-reducing agent, dithiothreitol, can induce an activation-like state in many integrins sugge...

Integrins are cysteine-rich heterodimeric cell-surface adhesion molecules that alter their affinity for ligands in response to cellular activation. The molecular mechanisms involved in this activation of integrins are not understood. Treatment with the thiol-reducing agent, dithiothreitol, can induce an activation-like state in many integrins sugge...

Bernard-Soulier syndrome is a rare bleeding disorder caused by a quantitative or qualitative defect in the platelet glycoprotein (GP) Ib-IX-V complex. The complex, which serves as a platelet receptor for von Willebrand factor, is composed of 4 subunits: GPIb alpha, GPIb beta, GPIX, and GPV. We here describe the molecular basis of a novel form of Be...

Bernard-Soulier syndrome is a rare bleeding disorder caused by a quantitative or qualitative defect in the platelet glycoprotein (GP) Ib-IX-V complex. The complex, which serves as a platelet receptor for von Willebrand factor, is composed of 4 subunits: GPIb, GPIbβ, GPIX, and GPV. We here describe the molecular basis of a novel form of Bernard-Sou...

Platelet inhibition significantly reduces the risk of cardiovascular mortality and morbidity. However, current antiplatelet therapies have limitations, and more efficacious agents are needed. E5510 is a novel compound that has multiple platelet inhibitory effects in in vitro studies. We compared the in vivo, pharmacodynamic effects of maximal antip...

All integrin alpha subunits contain a highly conserved KXGFFKR motif in their cytoplasmic domains that plays a crucial role in the regulation of integrin affinity for their ligands. We show that a lipid-modified peptide corresponding to the cytoplasmic region, 989-995, of the platelet integrin subunit glycoprotein GpIIb (alphaIIb), palmitoyl-KVGFFK...