Involvement of P2Y<Subscript>12</Subscript> receptor of stellate ganglion in diabetic cardiovascular autonomic neuropathy

Diabetes as a chronic epidemic disease with obvious symptom of hyperglycemia is seriously affecting human health globally due to the diverse diabetic complications. Diabetic cardiovascular autonomic neuropathy (DCAN) is a common complication of both type 1 and type 2 diabetes and incurs high morbidity and mortality. However, the underlying mechanism for DCAN is unclear. It is well known that purinergic signaling is involved in the regulation of cardiovascular function. In this study, we examined whether the P2Y₁₂ receptor could mediate DCAN-induced sympathetic reflexes. Our results revealed that the abnormal changes of blood pressure, heart rate, heart rate variability, and sympathetic nerve discharge were improved in diabetic rats treated with P2Y₁₂ short hairpin RNA (shRNA). Meanwhile, the expression of P2Y₁₂ receptor, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and connexin 43 (Cx43) in stellate ganglia (SG) was decreased in P2Y₁₂ shRNA-treated diabetic rats. In addition, knocking down the P2Y₁₂ receptor also inhibited the activation of p38 MARK in the SG of diabetic rats. Taken together, these findings demonstrated that P2Y₁₂ receptor in the SG may participate in developing diabetic autonomic neuropathy, suggesting that the P2Y₁₂ receptor could be a potential therapeutic target for the treatment of DCAN.     

Arrestin scaffolds NHERF1 to the P2Y12 receptor to regulate receptor internalization

We have recently shown in a patient with mild bleeding that the PDZ-binding motif of the platelet G protein-coupled P2Y(12) receptor (P2Y(12)R) is required for effective receptor traffic in human platelets. In this study we show for the first time that the PDZ motif-binding protein NHERF1 exerts a major role in potentiating G protein-coupled receptor (GPCR) internalization. NHERF1 interacts with the C-tail of the P2Y(12)R and unlike many other GPCRs, NHERF1 interaction is required for effective P2Y(12)R internalization. In vitro and prior to agonist stimulation P2Y(12)R/NHERF1 interaction requires the intact PDZ binding motif of this receptor. Interestingly on receptor stimulation NHERF1 no longer interacts directly with the receptor but instead binds to the receptor via the endocytic scaffolding protein arrestin. These findings suggest a novel model by which arrestin can serve as an adaptor to promote NHERF1 interaction with a GPCR to facilitate effective NHERF1-dependent receptor internalization.     

阿片肽与P2Y12受体信号通路的研究进展

糖尿病可增加心血管疾病危险性,因此糖尿病和心血管疾病的密切关系也日益被人们所重视。糖尿病引发的血小板功能亢进以及抗血小板药物抵抗的机制尚不明确。阿片肽类物质能够抑制血小板细胞活性以及凝集作用。本文对2型糖尿病血小板P2Y12信号通路高反应性、阿片肽及阿片受体对抗P2Y12信号通路高反应性的可能机制进行了归纳总结。     

Microglia modulate general anesthesia through P2Y12 receptor

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阿片肽与P2Y12 受体信号通路的研究进展

糖尿病可增加心血管疾病危险性,因此糖尿病和心血管疾病的密切关系也日益被人们所重视。糖尿病引发的血小板功能亢进以及抗血小板药物抵抗的机制尚不明确。阿片肽类物质能够抑制血小板细胞活性以及凝集作用,本文对2型糖尿病血小板P2Y12信号通路高反应性、阿片肽及阿片受体对抗P2Y12信号通路高反应性的可能机制进行了归纳总结。     

Improvement of cardiovascular autonomic reflexes after amelioration of metabolic control in insulin-dependent diabetic subjects with severe autonomic neuropathy

To evaluate the influence of good metabolic equilibrium on Diabetic Autonomic Neuropathy (DAN), cardiovascular autonomic reflexes were monitored in 9 male insulin-dependent diabetic patients with DAN, treated with Continuous Subcutaneous Insulin Infusion (CSII) by pump: 9 for 10 days, 4 for 1 year and 2 for 20 months. Autonomic neuropathy was assessed evaluating 5 cardiovascular autonomic tests: Valsalva Manoeuvre (VR), Deep Breathing (DB), Lying-to-Standing (L-S), Sustained Handgrip (SHG), and Postural Hypotension (PH). Metabolic control was assessed evaluating the mean daily plasma glucose, glucosuria and glycosylated hemoglobin. Ten days of CSII treatment induced a normalization of glucose balance and a slight but significant improvement in some parasympathetic cardiovascular tests (VR: from 1.09 +/- 0.01 to 1.13 +/- 0.02; P less than 0.05). After 4-8 months of CSII treatment a significant improvement in VR (P less than 0.05); DB (P less than 0.01) and L-S (P less than 0.05) was recorded. The long-term treatment with CSII did not seem to induce a further amelioration in cardiovascular autonomic reflexes. These results show that the slight improvement induced by good metabolic balance in the cardiovascular autonomic response could be related to functional-metabolic rather than structural changes in the nerves.     

Satellite glial cell P2Y12 receptor in the trigeminal ganglion is involved in lingual neuropathic pain mechanisms in rats

Background

Interstitial cystitis/painful bladder syndrome (IC/PBS), is a severely debilitating chronic condition that is frequently unresponsive to conventional pain medications. The etiology is unknown, however evidence suggests that nervous system sensitization contributes to enhanced pain in IC/PBS. In particular, central nervous system plasticity of glutamatergic signaling involving NMDA and metabotropic glutamate receptors (mGluRs) has been implicated in a variety of chronic pain conditions. Here, we test the hypothesis that mGluR5 mediates both non-inflammatory and inflammatory bladder pain or nociception in a mouse model by monitoring the visceromotor response (VMR) during graded bladder distention.

Results

Using a combination of genetic and pharmacologic approaches, we provide evidence indicating that mGluR5 is necessary for the full expression of VMR in response to bladder distention in the absence of inflammation. Furthermore, we observed that mice infected with a uropathogenic strain of Escherichia coli (UPEC) develop inflammatory hyperalgesia to bladder distention, and that the selective mGluR5 antagonist fenobam [N-(3-chlorophenyl)-N'-(4,5-dihydro-1-methyl-4-oxo-1H-imidazole-2-yl) urea], reduces the VMR to bladder distention in UPEC-infected mice.

Conclusions

Taken together, these data suggest that mGluR5 modulates both inflammatory and non-inflammatory bladder nociception, and highlight the therapeutic potential for mGluR5 antagonists in the alleviation of bladder pain.     

P2Y12 receptor gene polymorphisms are associated with epilepsy

The basic research indicated that microglial P2Y12 receptors (P2Y12Rs) are involved in the pathophysiology of epilepsy through regulated microglial-neuronal interactions, aberrant neurogenesis, or immature neuronal projections. However, whether the clinic case of epilepsy would be associated with P2Y12 receptor gene polymorphisms is presented with few data. In our study, a total of 176 patients with epilepsy and 50 healthy controls were enrolled. Two single-nucleotide polymorphisms, namely rs1491974 and rs6798347, were selected for analysis. The results revealed that carriers of the G allele of rs1491974 G>A or rs6798347 G>A may be associated with an increased risk of epilepsy (OR = 0.576, 95% CI = 0.368–0.901, p = 0.015; OR = 0.603, 95% CI = 0.367–0.988, p = 0.043). Interestingly, we found that the rs1491974 G>A genotype and allele frequencies have only a significant difference in female instead of male case (p = 0.004 for genotype; p = 0.001 for allele). The subgroup analysis demonstrated that individuals with the rs1491974 G>A genotype might have more frequent seizure (OR = 0.476, 95% CI = 0.255–0.890; p = 0.019). These data implied that both rs1491974 and rs6798347 polymorphisms of P2Y12R would be able to play import roles in epilepsy susceptibility, whereas the rs1491974 polymorphism may be specifically related to seizure frequency.     

Ventilatory response to exercise in diabetic subjects with autonomic neuropathy

Tantucci, C., P. Bottini, M. L. Dottorini, E. Puxeddu, G. Casucci, L. Scionti, and C. A. Sorbini. Ventilatory response toexercise in diabetic subjects with autonomic neuropathy.J. Appl. Physiol. 81(5):1978-1986, 1996.We have used diabetic autonomic neuropathy as amodel of chronic pulmonary denervation to study the ventilatoryresponse to incremental exercise in 20 diabetic subjects, 10 with(Dan+) and 10 without (Dan) autonomic dysfunction, and in 10 normal control subjects. Although both Dan+ and Dan subjectsachieved lower O₂ consumption andCO₂ production(CO₂) thancontrol subjects at peak of exercise, they attained similar values ofeither minute ventilation(E) oradjusted ventilation (E/maximalvoluntary ventilation). The increment of respiratory rate withincreasing adjusted ventilation was much higher in Dan+ than inDan and control subjects (P < 0.05). The slope of the linearE/CO₂relationship was 0.032 ± 0.002, 0.027 ± 0.001 (P < 0.05), and 0.025 ± 0.001 (P < 0.001) ml/min inDan+, Dan, and control subjects, respectively. Bothneuromuscular and ventilatory outputs in relation to increasingCO₂ were progressivelyhigher in Dan+ than in Dan and control subjects. At peak ofexercise, end-tidal PCO₂ was muchlower in Dan+ (35.9 ± 1.6 Torr) than in Dan (42.1 ± 1.7 Torr; P < 0.02) and control (42.1 ± 0.9 Torr; P < 0.005) subjects.We conclude that pulmonary autonomic denervation affects ventilatoryresponse to stressful exercise by excessively increasing respiratoryrate and alveolar ventilation. Reduced neural inhibitory modulationfrom sympathetic pulmonary afferents and/or increasedchemosensitivity may be responsible for the higher inspiratoryoutput.

     

Docking-based virtual screening of potential human P2Y12 receptor antagonists

Platelet plays essential roles in hemostasis and its dysregulation can lead to arterial thrombosis. P2Y12 is an important platelet membrane adenosine diphosphate receptor, and its antagonists have been widely developed as anti-coagulation agents. The current P2Y12 inhibitors available in clinical practice have not fully achieved satisfactory anti-thrombotic effects, leaving room for further improvement. To identify new chemical compounds as potential anti-coagulation inhibitors, we constructed a three-dimensional structure model of human P2Y12 by homology modeling based on the recently reported G-protein coupled receptor Meleagris gallopavo β1 adrenergic receptor. Virtual screening of the modeled P2Y12 against three subsets of small molecules from the ZINC database, namely lead-like, fragment-like, and drug-like, identified a number of compounds that might have high binding affinity to P2Y12. Detailed analyses of the top three compounds from each subset with the highest scores indicated that all of these compounds beard a hydrophobic bulk supplemented with a few polar atoms which bound at the ligand binding site via largely hydrophobic interactions with the receptor. This study not only provides a structure model of P2Y12 for rational design of anti-platelet inhibitors, but also identifies some potential chemicals for further development.     

The Gi-coupled P2Y12 receptor regulates diacylglycerol-mediated signaling in human platelets

Stimulation of G(q)-coupled receptors activates phospholipase C and is supposed to promote both intracellular Ca(2+) mobilization and protein kinase C (PKC) activation. We found that ADP-induced phosphorylation of pleckstrin, the main platelet substrate for PKC, was completely inhibited not only by an antagonist of the G(q)-coupled P2Y1 receptor but also upon blockade of the G(i)-coupled P2Y12 receptor. The role of G(i) on PKC regulation required stimulation of phosphatidylinositol 3-kinase rather than inhibition of adenylyl cyclase. P2Y12 antagonists also inhibited pleckstrin phosphorylation, Rap1b activation, and platelet aggregation induced upon G(q) stimulation by the thromboxane A(2) analogue U46619. Importantly, activation of phospholipase C and intracellular Ca(2+) mobilization occurred normally. Phorbol 12-myristate 13-acetate overcame the inhibitory effect of P2Y12 receptor blockade on PKC activation but not on Rap1b activation and platelet aggregation. By contrast, inhibition of diacylglycerol kinase restored both PKC and Rap1b activity and caused platelet aggregation. Stimulation of P2Y12 receptor or direct inhibition of diacylglycerol kinase potentiated the effect of membrane-permeable sn-1,2-dioctanoylglycerol on platelet aggregation and pleckstrin phosphorylation, in association with inhibition of its phosphorylation to phosphatidic acid. These results reveal a novel and unexpected role of the G(i)-coupled P2Y12 receptor in the regulation of diacylglycerol-mediated events in activated platelets.     

Correction to: P2Y12 receptor upregulation in satellite glial cells is involved in neuropathic pain induced by HIV glycoprotein 120 and 2',3'-dideoxycytidine

Purinergic Signalling - Due to the authors’ carelessness, we mistakenly used similar images between the Fig. 1b on the expression of P2Y12 protein (upper) and Fig. 5a on the expression of...     

P2Y1 and P2Y12 receptor cross-talk in calcium signalling: Evidence from nonstarved and long-term serum-deprived glioma C6 cells

The current work presents results of experiments on the calcium response evoked by the stimulation by extracellular nucleotides occurring in control, nonstarved glioma C6 cells and in cells after long-term (96 h) serum starvation. Three nucleotide receptors were studied: P2Y₁, P2Y₂ and P2Y₁₂. Two of them, P2Y₁ and P2Y₂, directly stimulate calcium response. The protein level of the P2Y₂ receptor did not change during the serum starvation, while P2Y₁ protein level fell dramatically. Observed changes in the calcium response generated by P2Y₁ are directly correlated with the receptor protein level as well as with the amount of calcium present in the intracellular calcium stores, partially depleted during starvation process. The third receptor, P2Y₁₂, did not directly evoke calcium response, however it is activated by the same ligand as P2Y₁. The experiments with AR-C69941MX, the P2Y₁₂-specific antagonist, indicated that in control and serum-starved cells, calcium response evoked by P2Y₁ receptor is potentiated by the activity of P2Y₁₂-dependent signaling pathways. This potentiation may be mediated by P2Y₁₂ inhibitory effect on the plasma membrane calcium pump. The calcium influx enhanced by the cooperation of P2Y₁ and P2Y₁₂ receptor activity directly depends on the capacitative calcium entrance mechanism.     

Structural and functional evolution of the P2Y12-like receptor group

Metabotropic pyrimidine and purine nucleotide receptors (P2Y receptors) belong to the superfamily of G protein-coupled receptors (GPCR). They are distinguishable from adenosine receptors (P1) as they bind adenine and/or uracil nucleotide triphosphates or diphosphates depending on the subtype. Over the past decade, P2Y receptors have been cloned from a variety of tissues and species, and as many as eight functional subtypes have been characterized. Most recently, several members of the P2Y₁₂-like receptor group, which includes the clopidogrel-sensitive ADP receptor P2Y₁₂, have been deorphanized. The P2Y₁₂-like receptor group comprises several structurally related GPCR which, however, display heterogeneous agonist specificity including nucleotides, their derivatives, and lipids. Besides the established function of P2Y₁₂ in platelet activation, expression in macrophages, neuronal and glial cells as well as recent results from functional studies implicate that several members of this group may have specific functions in neurotransmission, inflammation, chemotaxis, and response to tissue injury. This review focuses specifically on the structure-function relation and shortly summarizes some aspects of the physiological relevance of P2Y₁₂-like receptor members.     

Adenosine analogues as inhibitors of P2Y12 receptor mediated platelet aggregation

Modified adenosine derivatives may lead to the development of P2Y(12) antagonists that are potent, selective, and bind reversibly to the receptor. Analogues of 2',3'-trans-styryl acetal-N6-ureido-adenosine monophosphate were prepared by modification of the 5'-position. The resulting analogues were tested for P2Y(12) antagonism in a platelet aggregation assay.     

Optimization of ketone-based P2Y12 receptor antagonists as antithrombotic agents: Pharmacodynamics and receptor kinetics considerations

Modification of a series of P2Y₁₂ receptor antagonists by replacement of the ester functionality was aimed at minimizing the risk of in vivo metabolic instability and pharmacokinetic variability. The resulting ketones were then optimized for their P2Y₁₂ antagonistic and anticoagulation effects in combination with their physicochemical and absorption profiles. The most promising compound showed very potent antiplatelet action in vivo. However, pharmacodynamic–pharmacokinetic analysis did not reveal a significant separation between its anti-platelet and bleeding effects. The relevance of receptor binding kinetics to the in vivo profile is described.     

Functional interaction between purinergic receptors: effect of ligands for A2A and P2Y12 receptors on P2Y1 receptor function

A_2A adenosine receptor (A_2AR), P2Y₁ receptor (P2Y₁R) and P2Y₁₂ receptor (P2Y₁₂R) are predominantly expressed on human platelets. The individual role of each of these receptors in platelet aggregation has been actively reported. Previously, hetero-oligomerization between these three receptors has been shown to occur. Here, we show that Ca²⁺ signaling evoked by the P2Y₁R agonist, 2-methylthioladenosine 5’ diphosphate (2MeSADP) was significantly inhibited by the A_2AR antagonist (ZM241385 and SCH442416) and the P2Y₁₂R antagonist (ARC69931MX) using HEK293T cells expressing the three receptors. It was confirmed that inhibition of P2Y₁R signaling by A_2AR and P2Y₁₂R antagonists was indeed mediated through A_2AR and P2Y₁₂R using 1321N1 human astrocytoma cells which do not express P2Y receptors. We expect that intermolecular signal transduction and specific conformational changes occur among components of hetero-oligomers formed by these three receptors.     

Genetic variants of platelet ADP receptor P2Y12 associated with changed platelet functional activity and development of cardiovascular diseases

The key role in platelet aggregation is played by the platelet ADP receptor P2Y12, which is the target for antiaggregant drugs, clopidogrel and ticlopidine. At present, only sporadic data on genetic variants of platelet ADP receptor P2Y12 are available from literature, and their association with thromboembolic and cardiovascular diseases still remains obscure. Analysis of the group of subjects with high platelet reactivity resulted in identification of two nucleotide substitutions, C18T and G36T, in the coding region of the P2Y12 gene. The frequency of the P2Y12 T18 allele was higher in control group than in the group of patients survived from myocardial infarction at the age under 45 years (39% versus 28%, respectively, P = 0.04). Moreover, in the T18 carriers, platelet aggregation activity was lower than in the carriers of the wild-type genotype (0.84 ± 0.05%/s versus 1.01 ± 0.08%/s, respectively, P = 0.03). In the group of patients with early myocardial infarctions, a tendency towards the increased frequency of T36 allele in comparison with control group (20 and 12%, respectively, P = 0.07) was observed. The rate of ADP-induced platelet aggregation in the carriers of T36 allele from the control group was somewhat higher than in the subjects with the GG36 genotype (1.31 ± 0.16%/s versus 1.12 ± 0.06%/s, respectively, P = 0.07). The nucleotide substitutions identified were in lincage disequilibrium, i.e., allele T18 conformed to allele G36. On the contrary, allele C18 conformed to allele T36. Haplotype T18G36 was found to be responsible for the decreased risk of myocardial infarction and decreased platelet reactivity. It is suggested that polymorphisms of the P2Y12 gene identified can be used for determination of the risk group for myocardial infarction in the young males.