scholarly journals Adenosine Receptor Agonists Increase the Inhibition of Platelet Function by P2Y12 Antagonists in a cAMP- and Calcium-Dependent Manner

2020 ◽  
Vol 13 (8) ◽  
pp. 177
Author(s):  
Nina Wolska ◽  
Hassan Kassassir ◽  
Boguslawa Luzak ◽  
Cezary Watala ◽  
Marcin Rozalski
Keyword(s):  
P2y12 Receptor ◽  
Dependent Manner ◽  
Platelet Activity ◽  
Receptor Antagonists ◽  
Adenosine Receptor Agonists ◽  
Calcium Dependent ◽  
Fibrinogen Binding ◽  
P2y12 Antagonists ◽  
Simultaneous Inhibition

We have shown previously that platelet activity can be lowered through the simultaneous inhibition of P2Y12 receptor and activation of adenosine receptors (AR). This work explores this concept by testing the antiplatelet potential of nine AR agonists in combination with P2Y12 receptor antagonists—cangrelor and prasugrel metabolite. A panel of in vitro methods was used to assess platelet viability, P-selectin expression, GPIIb-IIIa activation, fibrinogen binding, calcium ion mobilization, VASP-P level, and cAMP formation, utilizing whole blood or isolated platelets from healthy volunteers. The AR agonists demonstrated anti-platelet effects, but stimulated signaling pathways to varying degrees. AR agonists and P2Y12 antagonists reduced expression of both P-selectin and the activated form of GPIIb-IIIa on platelets; however, the combined systems (AR agonist + P2Y12 antagonist) demonstrated stronger effects. The antiplatelet effects of AR when combined with P2Y12 were more pronounced with regard to exogenous fibrinogen binding and calcium mobilization. The cAMP levels in both resting and ADPactivated platelets were increased by AR agonist treatment, and more so when combined with P2Y12 inhibitor. In conclusion, as AR agonists are fast-acting compounds, the methods detecting early activation events are more suitable for assessing their antiplatelet action. The exogenous fibrinogen binding, calcium mobilisation and cAMP level turned out to be sensitive markers for detecting the inhibition caused by AR agonists alone or in combination with P2Y12 receptor antagonists.

Insights from In Vitro and Clinical Data to Guide Transition from the Novel P2Y12 Antagonist Selatogrel to Clopidogrel, Prasugrel, and Ticagrelor

2021 ◽  
Author(s):  
Uta Schilling ◽  
Jasper Dingemanse ◽  
Michael Dobrow ◽  
Martine Baumann ◽  
Markus A. Riederer ◽  
...  
Keyword(s):  
P2y12 Receptor ◽  
Time Interval ◽  
Dependent Manner ◽  
The Novel ◽  
Receptor Antagonists ◽  
Open Label ◽  
Double Blind ◽  
Concentration Dependent Manner ◽  
P2y12 Receptor Antagonist

AbstractReduced pharmacodynamic (PD) effects of irreversible oral P2Y12 receptor antagonists have been reported when administered during cangrelor infusion. Therefore, the PD interaction liability of the novel P2Y12 receptor antagonist selatogrel with irreversible (i.e., clopidogrel, prasugrel) and reversible (i.e., ticagrelor) oral P2Y12 receptor antagonists was investigated in vitro and in healthy subjects. In vitro, selatogrel reduced the effects of clopidogrel and prasugrel in a concentration-dependent manner, while additive effects were observed for the combination of selatogrel and ticagrelor. Accordingly, a single-center, randomized, double-blind, two-way crossover study was conducted consisting of six groups. In each group (N = 12), an open-label loading dose of 300 or 600 mg clopidogrel, 60 mg prasugrel, or 180 mg ticagrelor was administered 30 minutes (i.e., at t max of selatogrel) or 12 hours after a single subcutaneous dose of 16 mg selatogrel or placebo. Inhibition of platelet aggregation (IPA) was assessed at various time points up to 48 hours. Reduced IPA was determined when clopidogrel or prasugrel was administered 30 minutes after selatogrel (∼40 and 70% lower IPA, respectively, at 24 hours postdosing). However, when administering prasugrel 12 hours after selatogrel, IPA was not impacted (>90% IPA) and in the case of clopidogrel reduced effects were partially mitigated. Similar IPA was determined for ticagrelor when administered 30 minutes after selatogrel or placebo. In conclusion, reduced IPA was observed for clopidogrel and prasugrel when administered after selatogrel, which can be mitigated by applying an appropriate time interval. No PD interaction with ticagrelor was observed.

scholarly journals Role of α1-adrenergic receptor subtypes in contractility of the rabbit abdominal aorta in vitro

2013 ◽  
Vol 82 (3) ◽  
pp. 331-336 ◽  
Author(s):  
Jan Gnus ◽  
Albert Czerski ◽  
Stanisław Ferenc ◽  
Wojciech Zawadzki ◽  
Wojciech Witkiewicz ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Receptor Antagonist ◽  
Abdominal Aorta ◽  
Adrenergic Receptor ◽  
Receptor Subtypes ◽  
Organ Bath ◽  
Dependent Manner ◽  
Receptor Antagonists ◽  
Selective Antagonists

Investigation of the effect of α1-adrenergic receptor subtypes on the contraction of the abdominal aorta will allow for more effective treatment of hypertension by use of selective antagonists. The aim of the study was to evaluate the participation of α1-adrenergic receptor subtypes in the contractility of the aortic smooth muscle cells in rabbits. The in vitro experiments were performed in isolated tissue preparations from 30 adult female New Zealand rabbits. The abdominal aortic sections were placed in organ bath chambers and contracted with increasing doses of non-selective α1-adrenergic receptor agonist phenylephrine without pre-incubation or after incubation in α1-adrenergic receptor subtype-selective or non-selective antagonists. Separate sections were incubated with increasing concentrations of antagonists. Phenylephrine caused maximal rise in arterial smooth muscle tone to 4.75 ± 0.47 mN. The most potent in blocking phenylephrine induced contraction was 5-metylurapidil (α1A-adrenergic receptor antagonist) followed by phentolamine and prazosin (non-selective α1-adrenergic receptor antagonists); BMY 7378 (α1D-adrenergic receptor antagonist), cyclazosin and L-765.314 (α1B-adrenergic receptor antagonists) were less effective. All antagonists, except BMY 7378 elicited relaxation of non-precontracted aorta in dose dependent manner. Our results indicate that postsynaptic α1A receptors are the most potent in producing rabbit abdominal aorta contraction, while α1B and α1D subtypes are less effective.

Characterization of a cDNA encoding a novel band 4.1-like protein in zebrafish

1997 ◽  
Vol 75 (5) ◽  
pp. 623-632 ◽  
Author(s):  
Gregory M Kelly ◽  
Bruno Reversade
Keyword(s):  
Cell Communication ◽  
Membrane Skeleton ◽  
Adult Brain ◽  
Dependent Manner ◽  
Midblastula Transition ◽  
Protein 4.1 ◽  
Calcium Dependent ◽  
Calcium Calmodulin Dependent ◽  
Integral Role

Membrane skeleton protein 4.1 and other members of a family of proteins that link the cytoskeleton to the plasma membrane may play an integral role in cell communication during development. The polymerase chain reaction and degenerate oligodeoxynucleotide primers to consensus sequences in the putative membrane-binding domain of the protein 4.1 superfamily were used to isolate cDNAs encoding members of the zebrafish protein 4.1 family. Zebrafish stage- and tissue-specific first strand cDNA was used in the PCR. After the reaction, amplicons of the predicted size were sequenced to confirm their relationship to the protein 4.1 superfamily. One cDNA, with a high degree of similarity to a mouse novel band 4.1-like cDNA, was used to probe a zebrafish adult brain library. A 2.4-kb cDNA was isolated and found to encode a 619 amino acid polypeptide homologous to mouse novel band 4.1-like protein 4. Zebrafish nbl4 mRNA is maternally supplied and is expressed throughout embryogenesis. In adults, nbl4 is found in the ovary, eye, heart, and brain, but not in gut or skeletal muscle. When synthetic nbl4 mRNA is translated in vitro it binds calmodulin in a calcium-dependent manner. These data indicate that zebrafish nbl4 is a maternal transcript owing to its presence before the midblastula transition, and it is present later on in specific adult structures. The ability to bind calmodulin would suggest that the function of nbl4 protein may be potentially regulated via a calcium-calmodulin dependent mechanism.

scholarly journals Matrix-transmitted paratensile signaling enables myofibroblast–fibroblast cross talk in fibrosis expansion

2020 ◽  
Vol 117 (20) ◽  
pp. 10832-10838 ◽  
Author(s):  
Longwei Liu ◽  
Hongsheng Yu ◽  
Hui Zhao ◽  
Zhaozhao Wu ◽  
Yi Long ◽  
...  
Keyword(s):  
Cross Talk ◽  
Growth Models ◽  
Tissue Level ◽  
Dependent Manner ◽  
Cell Level ◽  
Fibrous Matrix ◽  
Calcium Dependent ◽  
Spatiotemporal Feature ◽  
Fibroblast Foci

While the concept of intercellular mechanical communication has been revealed, the mechanistic insights have been poorly evidenced in the context of myofibroblast–fibroblast interaction during fibrosis expansion. Here we report and systematically investigate the mechanical force-mediated myofibroblast–fibroblast cross talk via the fibrous matrix, which we termed paratensile signaling. Paratensile signaling enables instantaneous and long-range mechanotransduction via collagen fibers (less than 1 s over 70 μm) to activate a single fibroblast, which is intracellularly mediated by DDR2 and integrin signaling pathways in a calcium-dependent manner through the mechanosensitive Piezo1 ion channel. By correlating in vitro fibroblast foci growth models with mathematical modeling, we demonstrate that the single-cell-level spatiotemporal feature of paratensile signaling can be applied to elucidate the tissue-level fibrosis expansion and that blocking paratensile signaling can effectively attenuate the fibroblast to myofibroblast transition at the border of fibrotic and normal tissue. Our comprehensive investigation of paratensile signaling in fibrosis expansion broadens the understanding of cellular dynamics during fibrogenesis and inspires antifibrotic intervention strategies targeting paratensile signaling.

scholarly journals The Receptor for Parathyroid Hormone and Parathyroid Hormone-Related Peptide Is Hydrolyzed and Its Signaling Properties Are Altered by Directly Binding the Calpain Small Subunit

Endocrinology ◽  
2005 ◽  
Vol 146 (5) ◽  
pp. 2336-2344 ◽  
Author(s):  
Masako Shimada ◽  
Matthew J. Mahon ◽  
Peter A. Greer ◽  
Gino V. Segre
Keyword(s):  
Parathyroid Hormone ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Small Subunit ◽  
Hek293 Cells ◽  
Calpain Inhibitor ◽  
Dependent Manner ◽  
Intact Cells ◽  
Calcium Dependent

Abstract We show calcium-dependent, direct binding between the N-terminal portion of the PTH/PTHrP receptor (PTH1R) C-terminal intracellular tail and the calpain small subunit. Binding requires, but may not be limited to, amino acids W474, S475, and W477. The wild-type, full-length rat (r) PTH1R, but not rPTH1R with W474A/W477A substitutions, copurifies with the endogenous calpain small subunit in HEK293 cells. Calpain hydrolyzes ΔNt-rPTH1R, a receptor with a 156-amino acid N-terminal deletion, in a calcium-dependent manner in vitro and in intact cells. Most importantly, PTH stimulation increases the cleavage of ΔNt-rPTH1R and rPTH1R-yellow fluorescent protein in HEK293 cells, and of talin in HEK293 cells expressing rPTH1R-yellow fluorescent protein and in ROS17/2.8 osteoblast-like cells that express rPTH1R endogenously. The absence of calpain in Capn4-null embryonic fibroblasts and the lowered calpain activity in MC3T3-E1 osteoblastic cells due to stable expression of the calpain inhibitor, calpastatin, reduce PTH-stimulated cAMP accumulation. The calpain small subunit is the second protein, in addition to the sodium-hydrogen exchanger regulatory factor, and the first enzyme that binds the PTH1R; PTH1R bound to both of these proteins results in altered PTH signaling.

IWR-1 Inhibits Collagen-Induced Platelet Activation and Protects against Thrombogenesis

2019 ◽  
Vol 39 (04) ◽  
pp. 392-397
Author(s):  
Wei Wang ◽  
Songqing Lai ◽  
ZiJin Xiao ◽  
Haiyue Yan ◽  
Yongxi Li ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Antiplatelet Agent ◽  
Wnt Signalling ◽  
In Vivo Studies ◽  
Dependent Manner ◽  
Platelet Activity ◽  
Occlusion Time ◽  
Negative Effect

AbstractPlatelets play a crucial role in haemostasis and several pathophysiological processes. Collagen is a main initiator for platelet activation and aggregation. Given that Wnt signalling negatively regulates platelet function, and IWR-1 (a small molecule inhibitor for Wnt signalling) has the potential of inhibiting collagen synthesis, it is essential to investigate whether IWR-1 regulates collagen-induced platelet activation and protects against thrombogenesis. In the present study we found that IWR-1 pretreatment effectively suppressed collagen-induced platelet aggregation in a dose-dependent manner. In addition, IWR-1 also resulted in a decrease of P-selectin and phosphatidylserine surface exposure using fluorescence-activated cell sorting analysis. In vitro studies further revealed that IWR-1 had a negative effect on integrin a2β1 activation and platelet spreading. More importantly, the results from in vivo studies showed that IWR-1 exhibited a robust bleeding diathesis in the tail-bleeding assay and a prolonged occlusion time in the FeCl3-induced carotid injury model. Taken together, current results demonstrate that IWR-1 could effectively block collagen-induced platelet activity in vitro and in vivo, and suggest its candidacy as a new antiplatelet agent.

Reticulon 3-mediated Chk2/p53 activation suppresses hepatocellular carcinogenesis and is blocked by hepatitis B virus

Gut ◽  
2020 ◽  
pp. gutjnl-2020-321386
Author(s):  
Shushu Song ◽  
Yinghong Shi ◽  
Weicheng Wu ◽  
Hao Wu ◽  
Lei Chang ◽  
...  
Keyword(s):  
Cellular Proliferation ◽  
Dependent Manner ◽  
Mice Model ◽  
Calcium Dependent ◽  
B Virus ◽  
P53 Activation ◽  
Underlying Mechanisms ◽  
Induced Apoptosis

ObjectiveDysfunction of endoplasmic reticulum (ER) proteins is closely related to homeostasis disturbance and malignant transformation of hepatocellular carcinoma (HCC). Reticulons (RTN) are a family of ER-resident proteins critical for maintaining ER function. Nevertheless, the precise roles of RTN in HCC remain largely unclear. The aim of the study is to examine the effect of reticulon family member RTN3 on HCC development and explore the underlying mechanisms.DesignClinical HCC samples were collected to assess the relationship between RTN3 expression and patients’ outcome. HCC cell lines were employed to examine the effects of RTN3 on cellular proliferation, apoptosis and signal transduction in vitro. Nude mice model was used to detect the role of RTN3 in modulating tumour growth in vivo.ResultsWe found that RTN3 was highly expressed in normal hepatocytes but frequently downregulated in HCC. Low RTN3 expression predicted poor outcome in patients with HCC in TP53 gene mutation and HBV infection status-dependent manner. RTN3 restrained HCC growth and induced apoptosis by activating p53. Mechanism studies indicated that RTN3 facilitated p53 Ser392 phosphorylation via Chk2 and enhanced subsequent p53 nuclear localisation. RTN3 interacted with Chk2, recruited it to ER and promoted its activation in an ER calcium-dependent manner. Nevertheless, the tumour suppressive effects of RTN3 were abrogated in HBV-positive cells. HBV surface antigen competed with Chk2 for RTN3 binding and blocked RTN3-mediated Chk2/p53 activation.ConclusionThe findings suggest that RTN3 functions as a novel suppressor of HCC by activating Chk2/p53 pathway and provide more clues to better understand the oncogenic effects of HBV.

Mode of action of P2Y12 antagonists as inhibitors of platelet function

2011 ◽  
Vol 105 (01) ◽  
pp. 96-106 ◽  
Author(s):  
Jackie Glenn ◽  
Ann White ◽  
Sue Fox ◽  
Hans van Giezen ◽  
Sven Nylander ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
G Protein ◽  
Platelet Function ◽  
Adenosine Diphosphate ◽  
P2y12 Receptor ◽  
Receptor Antagonists ◽  
Receptor Agonists ◽  
P2y12 Antagonists ◽  
Induced Aggregation ◽  
G Protein Coupled

SummaryP2Y12 receptor antagonists are antithrombotic agents that inhibit platelet function by blocking the effects of adenosine diphosphate (ADP) at P2Y12 receptors. However, some P2Y12 receptor antagonists may affect platelet function through additional mechanisms. It was the objective of this study to investigate the possibility that P2Y12 antagonists inhibit platelet function through interaction with G-protein-coupled receptors other than P2Y12 receptors. We compared the effects of cangrelor, ticagrelor and the prasugrel active metabolite on platelet aggregation and on phosphorylation of vasodilator-stimulated phosphoprotein (VASP). We compared their effects with those of selective IP, EP4 and A2A agonists, which act at Gs-coupled receptors. All three P2Y12 antagonists were strong inhibitors of ADP-induced platelet aggregation but only partial inhibitors of aggregation induced by thrombin receptor activating peptide (TRAP) or the thromboxane A2 mimetic U46619. Further, after removing ADP and its metabolites using apyrase and adenosine deaminase, the P2Y12 antagonists produced only minor additional inhibition of TRAP or U46619-induced aggregation. Conversely, the Gs-coupled receptor agonists always produced strong inhibition of aggregation irrespective of whether ADP was removed. Other experiments using selective receptor agonists and antagonists provided no evidence of any of the P2Y12 antagonists acting through PAR1, TP, IP, EP4, A2A or EP3 receptors. All three P2Y12 antagonists enhanced VASPphosphorylation to a small and equal extent but the effects were much smaller than those of the IP, EP4 and A2A agonists. The effects of cangrelor, ticagrelor and prasugrel on platelet function are mediated mainly through P2Y12 receptors and not through another G-protein-coupled receptor.

Identification of a new C-type lectin, TES-70, secreted by infective larvae of Toxocara canis, which binds to host ligands

Parasitology ◽  
2000 ◽  
Vol 121 (5) ◽  
pp. 545-554 ◽  
Author(s):  
A. LOUKAS ◽  
A. DOEDENS ◽  
M. HINTZ ◽  
R. M. MAIZELS
Keyword(s):  
Immune Cell ◽  
Sequence Similarity ◽  
Mannose Receptor ◽  
Toxocara Canis ◽  
Dependent Manner ◽  
Expression Screening ◽  
Lectin Domain ◽  
Calcium Dependent ◽  
Infective Larvae

Infective larvae of the dog roundworm Toxocara canis survive in the tissues of their hosts for extended periods in a state of developmental arrest, successfully evading immune destruction. This survival strategy is thought to be mediated by T. canis excretory/secretory (TES) products which downregulate or divert the immune response. We purified one of the major TES products, TES-70 and gained amino acid sequence from 4 tryptic peptides. These peptides were matched to a predicted protein from a cDNA that was isolated by expression screening a T. canis cDNA library with mouse anti-TES serum. The predicted protein (Tc-CTL-4) is similar to, but larger than, Tc-CTL-1, a 32-kDa C-type lectin secreted by T. canis larvae. Tc-CTL-4 has a signal peptide, 2 Cys-rich domains and a C-terminal calcium-dependent C-type lectin domain that shares sequence similarity with host immune cell receptors such as macrophage mannose receptor and CD23. The lectin domain was expressed in bacteria and antiserum to the purified recombinant protein was used to confirm that Tc-ctl-4 did encode the native TES-70 glycoprotein. TES-70 selectively bound to ligands on the surface of Madin–Darby Canine Kidney cells in vitro in a calcium-dependent manner, inhibitable by mammalian serum, indicating that a host glycan is the native ligand for this new parasite lectin.

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