UDP-sugars activate P2Y14 receptors to mediate vasoconstriction of the porcine coronary artery

Involvement of purinergic signalling in the vasomotor response to hypochlorous acid in porcine coronary artery

Hypochlorous acid (HOCl) is generated by neutrophils during the innate immune response. ATP is released from cells by various stimuli and during inflammation but whether ATP is released by and participates in the response to HOCl is unclear. This study investigated vasomotor effects of HOCl on the porcine coronary artery (PCA) and the involvement of ATP and purine receptors. HOCl at 100 μM induced rapid and transient endothelium-dependent relaxation followed by slow and sustained endothelium-independent relaxation. Transient endothelium-dependent relaxation was induced by 500 μM HOCl, followed by endothelium-dependent contraction, then slow endothelium-independent relaxation. 8-(p-sulphophenyl)theophylline (8-SPT), an adenosine/P1 receptor antagonist, blocked rapid relaxation and contraction to HOCl but an A2A receptor antagonist, ZM 241385, and an A1 receptor antagonist, DPCPX, had no effect. Suramin, a P2 receptor antagonist (and membrane channel inhibitor), blocked rapid relaxation (at 100 μM HOCl) and contraction to HOCl. Other antagonists for P2, P2X1, P2Y1 and P2X4 receptors (PPADS, reactive blue 2, NF449, MRS2179 and BX430) did not affect HOCl responses. Relaxation to exogenous ATP was inhibited by 8-SPT but not by suramin suggesting that suramin block of HOCl responses may involve inhibition of membrane channels and endogenous ATP release. Apyrase, which hydrolyzes nucleotides, abolished responses to HOCl, ATP and unexpectedly adenosine. Neither probenecid nor carbenoxelone (connexin and pannexin channel inhibitors) blocked responses to HOCl. Luminescent ATP assay showed that HOCl elicited ATP release from cultures of human coronary artery endothelial cells. These findings advance our understanding of inflammation by showing that HOCl evokes endothelium-dependent vasorelaxation and contraction in coronary arteries which may involve P1 receptors implicating endogenous adenosine, possibly generated from rapid metabolism of ATP released by HOCl.

How selective antagonists and genetic modification have helped characterise the expression and functions of vascular P2Y receptors

Vascular P2Y receptors mediate many effects, but the role of individual subtypes is often unclear. Here we discuss how subtype-selective antagonists and receptor knockout/knockdown have helped identify these roles in numerous species and vessels. P2Y1 receptor-mediated vasoconstriction and endothelium-dependent vasodilation have been characterised using the selective antagonists, MRS2179 and MRS2216, whilst AR-C118925XX, a P2Y2 receptor antagonist, reduced endothelium-dependent relaxation, and signalling evoked by UTP or fluid shear stress. P2Y2 receptor knockdown reduced endothelial signalling and endothelial P2Y2 receptor knockout produced hypertensive mice and abolished vasodilation elicited by an increase in flow. UTP-evoked vasoconstriction was also blocked by AR-C118925XX, but the effects of P2Y2 receptor knockout were complex. No P2Y4 receptor antagonists are available and P2Y4 knockout did not affect the vascular actions of UTP and UDP. The P2Y6 receptor antagonist, MRS2578, identified endothelial P2Y6 receptors mediating vasodilation, but receptor knockout had complex effects. MRS2578 also inhibited, and P2Y6 knockout abolished, contractions evoked by UDP. P2Y6 receptors contribute to the myogenic tone induced by a stepped increase in vascular perfusion pressure and possibly to the development of atherosclerosis. The P2Y11 receptor antagonists, NF157 and NF340, inhibited ATP-evoked signalling in human endothelial cells. Vasoconstriction mediated by P2Y12/P2Y13 and P2Y14 receptors was characterised using the antagonists, cangrelor, ticagrelor, AR-C67085 and MRS2211 or PPTN respectively. This has yet to be backed up by receptor knockout experiments. Thus, subtype-selective antagonists and receptor knockout/knockdown have helped identify which P2Y subtypes are functionally expressed in vascular smooth muscle and endothelial cells and the effects that they mediate.

Extracellular nucleotides in smooth muscle contraction

Extracellular nucleotides and nucleosides are crucial signalling molecules, eliciting diverse biological responses in almost all organs and tissues. These molecules exert their effects by activating specific nucleotide receptors, which are finely regulated by ectonucleotidases that break down their ligands. In this comprehensive review, we aim to elucidate the relevance of extracellular nucleotides as signalling molecules in the context of smooth muscle contraction, considering the modulatory influence of ectonucleotidases on this intricate process. Specifically, we provide a detailed examination of the involvement of extracellular nucleotides in the contraction of non-vascular smooth muscles, including those found in the urinary bladder, the airways, the reproductive system, and the gastrointestinal tract. Furthermore, we present a broader overview of the role of extracellular nucleotides in vascular smooth muscle contraction.

Purinergic signaling in myocardial ischemia-reperfusion injury

Purines and their derivatives, extensively distributed in the body, act as a class of extracellular signaling molecules via a rich array of receptors, also known as purinoceptors (P1, P2X, and P2Y). They mediate multiple intracellular signal transduction pathways and participate in various physiological and pathological cell behaviors. Since the function in myocardial ischemia-reperfusion injury (MIRI), this review summarized the involvement of purinergic signal transduction in diversified pathological processes, including energy metabolism disorder, oxidative stress injury, calcium overload, inflammatory immune response, platelet aggregation, coronary vascular dysfunction, and cell necrosis and apoptosis. Moreover, increasing evidence suggests that purinergic signaling also mediates the prevention and treatment of MIRI, such as ischemic conditioning, pharmacological intervention, and some other therapies. In conclusion, this review exhibited that purinergic signaling mediates the complex processes of MIRI which shows its promising application and prospecting in the future.

Expression of the pro-inflammatory P2Y14 receptor in the non-vasectomized and vasectomized human epididymis

BACKGROUND

Vasectomy causes spermatozoa accumulation in the epididymis, which may cause epididymitis. Inflammation is triggered by alert molecules released following tissue stress or injury. These include UDP-glucose, which activates the pro-inflammatory P2Y14 receptor (P2Y14), and induces immune cell recruitment. However, little is known about P2Y14 in the epididymis and its potential activation following vasectomy.

OBJECTIVES

(i) to localize P2Y14 in the human excurrent duct; and (ii) to examine the effect of vasectomy on P2Y14 protein and P2RY14 mRNA content, the production of selected cytokines and chemokines, and immune cell recruitment in the epididymis.

MATERIAL AND METHODS

in situ hybridization, qRT-PCR, western blotting, immunohistochemistry and immunofluorescence were performed in banked human epididymis samples.

RESULTS

P2RY14 mRNA and P2Y14 protein were detected in epithelial cells in the efferent duct, epididymis and vas deferens in non-vasectomized men. Keratin 5 (KRT5)-positive basal cells were strongly labeled for P2Y14 in all epididymal segments. A progressive apical localization was detected in principal cells (negative for the proton pump V-ATPase) from the corpus to the cauda. A subset of V-ATPase-positive clear cells also showed strong P2Y14 labeling. Vasectomy induced an increase in P2RY14 mRNA in the corpus and cauda, and stronger apical labeling in principal cells in the corpus. CXCL10 mRNA increased in the cauda and CCL2 mRNA decreased in the corpus of vasectomized versus non-vasectomized men. No change in IL-8 and IL-1β mRNA was detected. Numerous CD45⁺ leukocytes were detected in the interstitium of the corpus and cauda following vasectomy, while only a few were seen in non-vasectomized men. Several CD45⁺ leukocytes, some of which containing spermatozoa, were detected in the corpus lumen following vasectomy.

DISCUSSION AND CONCLUSION

Our study indicates that vasectomy-induced spermatozoa congestion may lead to an inflamed-prone local environment characterized by potential activation of P2Y14 and recruitment of immune cells in the epididymis. This article is protected by copyright. All rights reserved.

Purinergic receptors modulators: An emerging pharmacological tool for disease management

Purinergic signaling is mediated through extracellular nucleotides (adenosine 5'-triphosphate, uridine-5'-triphosphate, adenosine diphosphate, uridine-5'-diphosphate, and adenosine) that serve as signaling molecules. In the early 1990s, purines and pyrimidine receptors were cloned and characterized drawing the attention of scientists toward this aspect of cellular signaling. This signaling pathway is comprised of four subtypes of adenosine receptors (P1), eight subtypes of G-coupled protein receptors (P2YRs), and seven subtypes of ligand-gated ionotropic receptors (P2XRs). In current studies, the pathophysiology and therapeutic potentials of these receptors have been focused on. Various ligands, modulating the functions of purinergic receptors, are in current clinical practices for the treatment of various neurodegenerative disorders and cardiovascular diseases. Moreover, several purinergic receptors ligands are in advanced phases of clinical trials as a remedy for depression, epilepsy, autism, osteoporosis, atherosclerosis, myocardial infarction, diabetes, irritable bowel syndrome, and cancers. In the present study, agonists and antagonists of purinergic receptors have been summarized that may serve as pharmacological tools for drug design and development.

Microglial P2Y14 receptor contributes to central sensitization following repeated inflammatory dural stimulation

BACKGROUND

Recent studies have indicated that P2Y receptors in spinal microglia play a role in the development of neuropathic and inflammatory pain. However, it remains unclear whether P2Y receptors in microglia are involved in the pathogenesis of migraine. Therefore, the aim of this study was to investigate the role of microglial P2Y14 receptor in trigeminal cervical complex (TCC) in migraine.

METHODS

We used a rat model of migraine induced by repeated inflammatory stimulation of the dura and examined the expression of P2Y14 receptor in the TCC in migraine rats by Western Blotting and immunofluorescence staining. Then, we determined the effect of P2Y14 antagonist PPTN on inflammatory soup (IS)-induced mechanical allodynia, microglial activation and ERK expression in TCC.

RESULTS

The expression level of P2Y14 receptor increased significantly in microglia in TCC after 4 or 7 days of repeated IS stimulation of the dura. Application of PPTN significantly attenuated the decrease of periorbital pain threshold in migraine model rats. In addition, repeated IS stimulation of the dura induced the activation of microglia and the phosphorylation of the ERK1/2 in microglia in TCC, which were abolished by the application of PPTN.

CONCLUSION

Our findings suggest that the increased P2Y14 receptor in microglia in TCC play a crucial role in the generation of mechanical allodynia in migraine rat model. Furthermore, the activation of the P2Y14 receptor is involved in microglial activation and ERK phosphorylation as well. The P2Y14 receptor in microglia might be used as a potential target for migraine treatment.

Localization, proteomics, and metabolite profiling reveal a putative vesicular transporter for UDP-glucose

Vesicular neurotransmitter transporters (VNTs) mediate the selective uptake and enrichment of small-molecule neurotransmitters into synaptic vesicles (SVs) and are therefore a major determinant of the synaptic output of specific neurons. To identify novel VNTs expressed on SVs (thus identifying new neurotransmitters and/or neuromodulators), we conducted localization profiling of 361 solute carrier (SLC) transporters tagging with a fluorescent protein in neurons, which revealed 40 possible candidates through comparison with a known SV marker. We parallelly performed proteomics analysis of immunoisolated SVs and identified seven transporters in overlap. Ultrastructural analysis further supported that one of the transporters, SLC35D3, localized to SVs. Finally, by combining metabolite profiling with a radiolabeled substrate transport assay, we identified UDP-glucose as the principal substrate for SLC35D3. These results provide new insights into the functional role of SLC transporters in neurotransmission and improve our understanding of the molecular diversity of chemical transmitters.

Molecular pharmacology of P2Y receptor subtypes

Professor Geoffrey Burnstock proposed the concept of purinergic signaling via P1 and P2 receptors. P2Y receptors are G-protein-coupled receptors (GPCRs) for extracellular adenine and uracil nucleotides. Eight mammalian P2Y receptor subtypes have been identified. They are divided into two subgroups (P2Y₁, P2Y₂, P2Y₄, P2Y₆, and P2Y₁₁) and (P2Y₁₂, P2Y₁₃, and P2Y₁₄). P2Y receptors are found in almost all cells and mediate responses in physiology and pathophysiology including pain and inflammation. The antagonism of platelet P2Y₁₂ receptors by cangrelor, ticagrelor or active metabolites of the thienopyridine compounds ticlopidine, clopidogrel and prasugrel reduces the ADP-induced platelet aggregation in patients with thrombotic complications of vascular diseases. The nucleotide agonist diquafosol acting at P2Y₂ receptors is used for the treatment of the dry eye syndrome. Structural information obtained by crystallography of the human P2Y₁ and P2Y₁₂ receptor proteins, site-directed mutagenesis and molecular modeling will facilitate the rational design of novel selective drugs.

Purinergic signalling in the cardiovascular system-a tribute to Geoffrey Burnstock

Geoffrey Burnstock made groundbreaking discoveries on the physiological roles of purinergic receptors and led on P2 purinergic receptor classification. His knowledge, vision and leadership inspired and influenced the international scientific community. I had the privilege of spending over 10 years (from 1985) with Geoff at the Department of Anatomy and Developmental Biology, initially as a PhD student and then as a postdoctoral research fellow. I regarded him with enormous admiration and affection. This review on purinergic signalling in the cardiovascular system is a tribute to Geoff. It includes some personal recollections of Geoff.

Role of P2Y Receptors in Platelet Extracellular Vesicle Release

Platelet extracellular vesicles (PEVs) are potential new biomarkers of platelet activation which may allow us to predict and/or diagnose developing coronary thrombosis before myocardial necrosis occurs. The P2Y1 and P2Y12 receptors play a key role in platelet activation and aggregation. Whereas the P2Y1 antagonists are at the preclinical stage, at present, the P2Y12 antagonists are the most effective treatment strategy to prevent stent thrombosis after percutaneous coronary intervention. Despite an increasing number of publications on PEVs, the mechanisms underlying their formation, including the role of purinergic receptors in this process, remain an active research field. Here, we outline the clinical relevance of PEVs in cardiovascular disease, summarize the role and downstream signalling of P2Y receptors in platelet activation, and discuss the available evidence regarding their role in PEV formation.

Sleep fragmentation increases blood pressure and is associated with alterations in the gut microbiome and fecal metabolome in rats

The gut microbiota, via the production of metabolites entering the circulation, plays a role in blood pressure regulation. Blood pressure is also affected by the characteristics of sleep. To date, no studies have examined relationships among the gut microbiota/metabolites, blood pressure, and sleep. We hypothesized that fragmented sleep is associated with elevated mean arterial pressure, an altered and dysbiotic gut microbial community, and changes in fecal metabolites. In our model system, rats were randomized to 8 h of sleep fragmentation during the rest phase (light phase) or were undisturbed (controls) for 28 consecutive days. Rats underwent sleep and blood pressure recordings, and fecal samples were analyzed during: baseline (days -4 to -1), early sleep fragmentation (days 0-3), midsleep fragmentation (days 6-13), late sleep fragmentation (days 20-27), and recovery/rest (days 28-34). Less sleep per hour during the sleep fragmentation period was associated with increased mean arterial pressure. Analyses of gut microbial communities and metabolites revealed that putative short chain fatty acid-producing bacteria were differentially abundant between control and intervention animals during mid-/late sleep fragmentation and recovery. Midsleep fragmentation was also characterized by lower alpha diversity, lower Firmicutes:Bacteroidetes ratio, and higher Proteobacteria in intervention rats. Elevated putative succinate-producing bacteria and acetate-producing bacteria were associated with lower and higher mean arterial pressure, respectively, and untargeted metabolomics analysis demonstrates that certain fecal metabolites are significantly correlated with blood pressure. These data reveal associations between sleep fragmentation, mean arterial pressure, and the gut microbiome/fecal metabolome and provide insight to links between disrupted sleep and cardiovascular pathology.

Update of P2Y receptor pharmacology: IUPHAR Review 27

Eight G protein-coupled P2Y receptor subtypes respond to extracellular adenine and uracil mononucleotides and dinucleotides. P2Y receptors belong to the δ group of rhodopsin-like GPCRs and contain two structurally distinct subfamilies: P2Y₁ , P2Y₂ , P2Y₄ , P2Y₆ , and P2Y₁₁ (principally G_q protein-coupled P2Y₁ -like) and P2Y_12-14 (principally G_i protein-coupled P2Y₁₂ -like) receptors. Brain P2Y receptors occur in neurons, glial cells, and vasculature. Endothelial P2Y₁ , P2Y₂ , P2Y₄ , and P2Y₆ receptors induce vasodilation, while smooth muscle P2Y₂ , P2Y₄ , and P2Y₆ receptor activation leads to vasoconstriction. Pancreatic P2Y₁ and P2Y₆ receptors stimulate while P2Y₁₃ receptors inhibits insulin secretion. Antagonists of P2Y₁₂ receptors, and potentially P2Y₁ receptors, are anti-thrombotic agents, and a P2Y₂ /P2Y₄ receptor agonist treats dry eye syndrome in Asia. P2Y receptor agonists are generally pro-inflammatory, and antagonists may eventually treat inflammatory conditions. This article reviews recent developments in P2Y receptor pharmacology (using synthetic agonists and antagonists), structure and biophysical properties (using X-ray crystallography, mutagenesis and modelling), physiological and pathophysiological roles, and present and potentially future therapeutic targeting.

Amplification of the COX/TXS/TP receptor pathway enhances uridine diphosphate-induced contraction by advanced glycation end products in rat carotid arteries

Advanced glycation end products (AGEs) play a pivotal role in vascular functions under various pathophysiological conditions. Although uridine diphosphate (UDP) is an important extracellular nucleotide, the relationship between AGEs and UDP regarding their effect on vascular functions remains unclear. Therefore, we investigated the effects of AGE-bovine serum albumin (AGE-BSA) on UDP-mediated responses in rat thoracic aorta and carotid arteries. In rat thoracic aorta, UDP-induced relaxation was observed and this relaxation was similar between control (1.0 v/v% PBS) and AGE-BSA-treated (0.1 mg/mL for 60 min) groups. In contrast, contraction but not relaxation was obtained following UDP application to carotid arteries with and without endothelia; contraction was greater in the AGE-BSA-treated group than in the control group. The difference in UDP-induced contraction between the two groups was not abolished by the use of a nitric oxide synthase (NOS) inhibitor, whereas it was abolished by the use of cyclooxygenase (COX), thromboxane synthase (TXS), and thromboxane-prostanoid (TP) receptor antagonist. Further, the difference in UDP-induced contraction was not abolished by the use of a cPLA₂ inhibitor, whereas it was abolished by the use of an iPLA₂ inhibitor. UDP increased TXA₂ release in both groups, and its level was similar in both groups. Moreover, the release of PGE₂, PGF_2α, and PGI₂ was similar among the groups. Under NOS inhibition, TP receptor agonist-induced contraction increased in the AGE-BSA-treated group (vs. control group). In conclusion, the increase in UDP-induced carotid arterial contraction by AGE-BSA can be attributed to an increase in the COX/TXS/TP receptor pathway, particularly, TP receptor signaling.

Recent progress on the discovery of P2Y14 receptor antagonists

The P2Y₁₄ receptor (P2Y₁₄R), a G protein-coupled receptor (GPCR), is activated by extracellular nucleotides. P2Y₁₄R is involved in inflammatory, diabetes, immune processes and other related complications, and is therefore an attractive therapeutic target. As the three-dimensional structure of the P2Y₁₄R has not yet been elucidated, homology modeling based on the crystallography of the closely related P2Y₁₂R have been used in the structure-based design of P2Y₁₄R ligands. Several P2Y₁₄R antagonists with excellent potency and high subtype-selectivity have been discovered in recent years. In this review, development of novel small molecules as antagonists of P2Y₁₄R was described.

Pharmacology of P2Y receptors

P2Y receptors are G-protein-coupled receptors (GPCRs) for extracellular nucleotides. There are eight mammalian P2Y receptor subtypes divided into two subgroups (P2Y₁, P2Y₂, P2Y₄, P2Y₆, and P2Y₁₁) and (P2Y₁₂, P2Y₁₃, and P2Y₁₄). The P2Y receptors are expressed in various cell types and play important roles in physiology and pathophysiology including inflammatory responses and neuropathic pain. The antagonism of P2Y₁₂ receptors is used in pharmacotherapy for the prevention and therapy of cardiovascular events. The nucleoside analogue ticagrelor and active metabolites of the thienopyridine compounds ticlopidine, clopidogrel and prasugrel inhibit platelet P2Y₁₂ receptors and reduce thereby platelet aggregation. The P2Y₂ receptor agonist diquafosol is used for the treatment of the dry eye syndrome. The P2Y receptor subtypes differ in their amino acid sequences, their pharmacological profiles and their signaling transduction pathways. Recently, selective receptor ligands have been developed for all subtypes. The published crystal structures of the human P2Y₁ and P2Y₁₂ receptors as well as receptor models will facilitate the development of novel drugs for pharmacotherapy.

Altered Purinergic Receptor Sensitivity in Type 2 Diabetes-Associated Endothelial Dysfunction and Up₄A-Mediated Vascular Contraction

Purinergic signaling may be altered in diabetes accounting for endothelial dysfunction. Uridine adenosine tetraphosphate (Up₄A), a novel dinucleotide substance, regulates vascular function via both purinergic P1 and P2 receptors (PR). Up₄A enhances vascular contraction in isolated arteries of diabetic rats likely through P2R. However, the precise involvement of PRs in endothelial dysfunction and the vasoconstrictor response to Up₄A in diabetes has not been fully elucidated. We tested whether inhibition of PRs improved endothelial function and attenuated Up₄A-mediated vascular contraction using both aortas and mesenteric arteries of type 2 diabetic (T2D) Goto Kakizaki (GK) rats vs. control Wistar (WT) rats. Endothelium-dependent (EDR) but not endothelium-independent relaxation was significantly impaired in both aortas and mesenteric arteries from GK vs. WT rats. Non-selective inhibition of P1R or P2R significantly improved EDR in aortas but not mesenteric arteries from GK rats. Inhibition of A1R, P2X₇R, or P2Y₆R significantly improved EDR in aortas. Vasoconstrictor response to Up₄A was enhanced in aortas but not mesenteric arteries of GK vs. WT rats via involvement of A1R and P2X₇R but not P2Y₆R. Depletion of major endothelial component nitric oxide enhanced Up₄A-induced aortic contraction to a similar extent between WT and GK rats. No significant differences in protein levels of A1R, P2X₇R, and P2Y₆R in aortas from GK and WT rats were observed. These data suggest that altered PR sensitivity accounts for endothelial dysfunction in aortas in diabetes. Modulating PRs may represent a potential therapy for improving endothelial function.