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。     

血小板膜P2Y12受体基因T744C多态性对外伤性脑梗死(PTCI)患者血小板聚合率及疗效的影响

目的:外伤性脑梗死(posttraumatic cerebral infarction,PTCI)是颅脑损伤的常见并发症之一,P2Y12受体介导血小板聚集是血栓形成的重要通路,与血小板聚集形成密切相关。本研究探讨外伤性脑梗死发生发展与血小板膜P2Y12受体基因T744C基因多态性的关系。方法:用聚合酶链反应(PCR)和限制性酶切片段长度多态性(RFLP)技术对186例外伤性脑梗死患者P2Y12受体基因T744C多态性进行分析。分别在治疗前和治疗后对所有颅脑外伤患者的伤情GCS评分,并按基因型分组对照分析结果。结果:血小板膜T744C血小板膜T744C基因型基因频率分别为TT基因型59.14%、TC型32.26%、CC型8.60%,T等位基因75.27%、C等位基因24.73%;其中TT基因型对奥扎格雷反应较敏感,GCS评分预后好;而CC型对奥扎格雷反应性低,预后差。结论:T744C基因多态性中CC基因型可能导致外伤性脑梗死临床及预后存在明显的个体差异,与其对抗血小板药物抵抗有关。T744C的C等位基因可能是脑梗死的遗传危险因素,开展相关遗传学风险研究,对于进一步缓解脑梗症状、改善预后具有重要意义。     

血小板衍生生长因子受体结构与功能的研究

血小板衍生生长因子受体(platelet-derived growth factor receptor, PDGFR),包括PDGFRα和PDGFRβ,属于第三类受体酪氨酸激酶家族.它们参与血管再生和创伤修复等重要生理过程,并能够促进肿瘤细胞的增殖、迁移与存活.目前,在多种肿瘤、纤维化以及心血管疾病中均检测到高表达或突变的PDGFR受体以及高表达的血小板衍生生长因子(platelet-derived growth factor, PDGF), PDGF/PDGFR已成为基础生物学与转化医学研究所关注的重要靶点.本文总结了当前关于PDGFR的结构与功能研究,对PDGF/PDGFR信号传导机制以及PDGF/PDGFR信号异常与疾病的关系进行了梳理,论述了针对该信号通路的多种靶向药物的治疗机制,并对今后研究方向进行了展望.     

Rho/Rho激酶信号通路与脉管收缩

Rho/Rho激酶信号通路在正常血管、淋巴管等脉管收缩过程中发挥重要的调节作用,并参与休克后血管反应性和钙敏感性的双相调节以及休克淋巴管低反应性的发生.以Rho/Rho激酶为靶点,对于干预休克脉管系统低反应性的发生具有重要意义.本文综述Rho/Rho激酶信号通路在脉管收缩中的调节机制.     

TGF-β1通过激活Smad信号途径抑制PI3K/AKT信号介导的BMSC成脂分化

转化生长因子β1 (TGF-β1) 是参与骨髓间充质干细胞（BMSCs）脂肪定向分化的重要调节因子,其具体的调节机制尚不清楚. 本研究证明,BMSCs在体外分化为脂肪细胞的过程中, TGF-β1的基因表达显著下调,重组TGF-β1能够抑制BMSCs体外脂肪细胞定向分化,其分化的标志蛋白C/EBPβ和αP2的表达水平显著降低. TGF-β1在激活Smad信号通路的同时,还抑制胰岛素(脂肪分化的主要诱导剂)对PI3K/Akt信号通路的激活.加入Smad特异性阻断剂后,C/EBPβ和αP2的诱导表达恢复正常,同时PI3K/Akt信号通路的活化亦得以恢复. 结果提示,TGF-β1可通过Smad信号通路干扰脂肪细胞分化的核心信号通路-PI3K/Akt的活化,从而实现对BMSCs脂肪分化的抑制.该研究结果为肥胖等导致的心血管疾病或Ⅱ型糖尿病等的临床治疗提供有价值的参考.     

Hippo信号通路与心血管发育及疾病调控

心血管疾病已成为中国乃至全球首位死亡原因,探索心血管系统发育及调控异常的原因及相关机制可以为心血管疾病的预防和治疗提供重要的科学依据。Hippo信号通路是新近发现的在调节器官大小、细胞增殖及凋亡、干细胞命运等方面具有重要功能的一条信号通路。Hippo信号通路的不同成分参与心脏血管的发育和心血管细胞增殖、分化等功能调控,影响损伤后修复及再生等过程,该通路调节异常可引起心血管疾病,如心梗、心肌肥大、血管内膜增生、动脉硬化等。本文综述了Hippo信号通路对心血管系统发育和疾病调控的相关研究及最新进展,以期为Hippo通路在心血管疾病的发病机制及临床转化研究提供潜在的理论基础。     

microRNAs对脂肪细胞分化相关因子的作用及预测

microRNAs是一类调节靶基因的转录后翻译的小型非编码单链RNA,研究已发现microRNAs在癌症、心血管疾病及糖尿病中显示极为重要的生物学功能。糖尿病目前已成为威胁人类健康的最主要疾病,尤其是II型糖尿病的发病机制成为研究热点。脂肪细胞分化异常是导致II型糖尿病以及胰岛素抵抗的主要因素。进一步阐明microRNAs对脂肪细胞分化过程的作用机制,可能为糖尿病治疗找到新的靶点。本综述将从microRNAs与脂肪细胞分化基因、核激素受体以及相关信号通路相互作用三方面阐述和预测microRNAs对脂肪细胞分化的潜在作用。     

周围神经损伤中P2Y12受体-p38MAPK通路的研究进展

周围神经损伤是临床中常见的神经损伤之一,神经胶质细胞和信号通路转导在周围神经损伤和再生修复中发挥重要作用。小胶质细胞的活化与周围神经损伤导致的神经损伤及疼痛密切相关,小胶质细胞是周围神经损伤与修复的关键场所。脊髓背角的小胶质细胞可被嘌呤信号通路的P2Y_(12)受体活化,进而导致p38MAPK磷酸化,造成相关神经损伤及感觉功能障碍。以脊髓背角的小胶质细胞为靶点,从P2Y_(12)受体-p38MAPK通路的角度可揭示周围神经损伤的部分可能机制。探究从嘌呤信号通路与小胶质细胞活化的新角度,将神经损伤后的P2Y_(12)受体与p38MAPK的磷酸化表达联系为P2Y_(12)受体-p38MAPK通路,可为临床治疗周围神经损伤提供新的思路。本文就周围神经损伤中P2Y_(12)受体-p38MAPK通路的研究进展作一综述。     

葡萄籽原花青素通过Nrf2/ARE信号通路抗高糖诱导的HUVEC-12细胞氧化损伤

研究葡萄籽原花青素提取物(GSPE)对高糖诱导的人脐静脉内皮细胞HUVEC-12氧化应激损伤的保护作用及其相关机制。建立高糖诱导的HUVEC-12细胞模型,测定细胞活力,检测细胞内活性氧(ROS)水平、乳酸脱氢酶(LDH)与超氧化物歧化酶(SOD)活性及Nrf2/ARE信号通路中相关基因mRNA水平和蛋白含量。结果显示GSPE作用后显著提高HUVEC-12细胞活力,抑制高糖诱导的细胞内ROS水平升高,增强SOD活性(P0.05),并呈现剂量依赖效应。GSPE作用能同时提高抗氧化转录因子Nrf2和下游区GSH-Px、HO-1、γ-GCS、NQO1基因的表达量以及HO-1、NQO1蛋白的含量(P0.05)。结果表明GSPE能通过激活Nrf2/ARE通路对抗高糖诱导的HUVEC-12细胞氧化应激损伤。     

P38MAPK信号通路与心血管疾病关系的研究进展

P38MAPK信号通路是细胞内主要的信息传递途径之一,与其他信号通路相互联系,共同调节细胞增殖、分化、凋亡、细胞骨架重构及细胞周期,在多种心血管疾病发生发展和转归中均起着重要作用。通过阻断和调控P38MAPK的表达和活性,探索防治心血管疾病的新的治疗手段具有重大临床意义。本文拟将P38MAPK与心血管疾病的关系的研究进展做一综述。     

Purinergic interplay between erythrocytes and platelets in diabetes-associated vascular dysfunction

Cardiovascular complications in diabetes are the leading causes for high morbidity and mortality. It has been shown that alteration of purinergic signaling contributes to diabetes-associated cardiovascular complications. Red blood cells (RBCs) and platelets play a fundamental role in regulation of oxygen transport and hemostasis, respectively. Of note, these cells undergo purinergic dysfunction in diabetes. Recent studies have established a novel function of RBCs as disease mediators for the development of endothelial dysfunction in type 2 diabetes (T2D). RBC-released ATP is defective in T2D, which has implication for induction of vascular dysfunction by dysregulating purinergic signaling. Platelets are hyperactive in diabetes. ADP-mediated P2Y₁ and P2Y₁₂ receptor activation contributes to platelet aggregation and targeting P2Y receptors particularly P2Y₁₂ receptor in platelets is effective for the treatment of cardiovascular events. In contrast to other P2Y₁₂ receptor antagonists, platelet-targeting drug ticagrelor has potential to initiate purinergic signaling in RBCs for the beneficial cardiovascular outcomes. It is increasingly clear that altered vascular purinergic signaling mediated by various nucleotides and nucleoside contributes to diabetes-associated vascular dysfunction. However, the contribution of complex purinergic networks between RBCs and platelets to the vascular dysfunction in diabetes remains unclear. This study discusses the possible interplay of RBCs and platelets via the purinergic network for diabetes-associated vascular dysfunction.     

The P2Y 13 Met-158-Thr polymorphism, which is in linkage disequilibrium with the P2Y 12 locus, is not associated with acute myocardial infarction

BACKGROUND AND AIMS: The aims of this study were to investigate (1) if P2Y(12) polymorphisms defining the P2Y(12) H2 allele are associated with any other SNPs that may explain the previously reported association with increased ADP induced platelet activation and association with peripheral arterial disease and coronary artery disease and (2) if such variants are associated with acute myocardial infarction (AMI) or classical risk factors for AMI. METHODS AND RESULTS: The P2Y(13) Met-158-Thr polymorphism was found to be in linkage disequilibrium (LD) with the P2Y(12) H2 haplotype (all examined SNPs: D' = 1.0, r(2) = 0.936-1.0), defining a novel P2Y(12) H2/P2Y(13) Thr-158 haplotype. Genotyping of an AMI case control population (n = 1244 cases, 2488 controls) revealed no association of the P2Y(13) Thr-158 allele with AMI (OR = 0.96, 95% C.I. 0.82-1.12, P = 0.63). Also, no differences between the genotype frequencies of P2Y(13) Met-158-Met and Met-158-Thr/Thr-158-Thr were seen in AMI case-control subpopulations (early onset AMI OR = 1.06, 95% C.I. 0.85-1.31, P = 0.62); family history of AMI (OR = 0.98, 95% C.I. 0.78-1.22, P = 0.83) nor in early onset AMIs with family history of AMI (OR = 1.0, 95% C.I. 0.74-1.36, P = 1.0). Genotyping of the P2Y(13) Met-158-Thr polymorphism in a population based sample (n = 6055) revealed no association with cardiovascular risk factors. In addition, the P2Y(13) Met-158-Thr polymorphism was genotyped in a diabetes case-control population, and associations were found neither with DM nor with any examined DM risk factors. CONCLUSION GENOTYPING: The P2Y(13) Met-158-Thr polymorphism is in tight LD with the P2Y(12) locus but is not associated with AMI or classical cardiovascular risk factors.     

P2Y12 receptor expression is a critical determinant of functional responsiveness to ATX's MORFO domain

In the central nervous system, the formation of the myelin sheath and the differentiation of the myelinating cells, namely oligodendrocytes, are regulated by complex signaling networks that involve purinergic receptors and the extracellular matrix. However, the exact nature of the molecular interactions underlying these networks still needs to be defined. In this respect, the data presented here reveal a signaling mechanism that is characterized by an interaction between the purinergic P2Y(12) receptor and the matricellular extracellular matrix protein autotaxin (ATX), also known as ENPP2, phosphodiesterase-Iα/ATX, or lysoPLD. ATX has been previously described by us to mediate intermediate states of oligodendrocyte adhesion and to enable changes in oligodendrocyte morphology that are thought to be crucial for the formation of a fully functional myelin sheath. This functional property of ATX is mediated by ATX's modulator of oligodendrocyte remodeling and focal adhesion organization (MORFO) domain. Here, we show that the expression of the P2Y(12) receptor is necessary for ATX's MORFO domain to exert its effects on differentiating oligodendrocytes. In addition, our data demonstrate that exogenous expression of the P2Y(12) receptor can render cells responsive to the known effects of ATX's MORFO domain, and they identify Rac1 as an intracellular factor mediating the effect of ATX-MORFO-P2Y(12) signaling on the assembly of focal adhesions. Our data further support the idea that a physical interaction between ATX and the P2Y(12) receptor provides the basis for an ATX-MORFO-P2Y(12) signaling axis that is crucial for mediating cellular states of intermediate adhesion and morphological/structural plasticity.     

Expression and functional characterization of P2Y1 and P2Y12 nucleotide receptors in long-term serum-deprived glioma C6 cells

We characterized the expression and functional properties of the ADP-sensitive P2Y(1) and P2Y(12) nucleotide receptors in glioma C6 cells cultured in medium devoid of serum for up to 96 h. During this long-term serum starvation, cell morphology changed from fibroblast-like flat to round, the adhesion pattern changed, cell-cycle arrest was induced, extracellular signal-regulated kinase (ERK1/2) phosphorylation was reduced, Akt phosphorylation was enhanced, and expression of the P2Y(12) receptor relative to P2Y(1) was increased. These processes did not reflect differentiation into astrocytes or oligodendrocytes, as expression of glial fibrillary acidic protein and NG2 proteoglycan (standard markers of glial cell differentiation) was not increased during the serum deprivation. Transfer of the cells into fresh medium containing 10% fetal bovine serum reversed the changes. This demonstrates that serum starvation caused only temporary growth arrest of the glioma C6 cells, which were ready for rapid division as soon as the environment became more favorable. In cells starved for 72 and 96 h, expression of the P2Y(1) receptor was low, and the P2Y(12) receptor was the major player, responsible for ADP-evoked signal transduction. The P2Y(12) receptor activated ERK1/2 kinase phosphorylation (a known cell proliferation regulator) and stimulated Akt activity. These effects were reduced by AR-C69931MX, a specific antagonist of the P2Y(12) receptor. On the other hand, Akt phosphorylation increased in parallel with the low expression of the P2Y(1) receptor, indicating the inhibitory role of P2Y(1) in Akt pathway signaling. The shift in nucleotide receptor expression from P2Y(1) to P2Y(12) would appear to be a new and important self-regulating mechanism that promotes cell growth rather than differentiation and is a defense mechanism against effects of serum deprivation.     

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.     

P2Y2 and TrkA receptors interact with Src family kinase for neuronal differentiation

The crosstalk between the P2Y(2) G-protein-coupled receptor (GPCR) with TrkA receptor tyrosine kinase (RTK) is an important mechanism that regulates neuronal differentiation. We show that Src family kinases (SFK) regulate P2Y(2)-TrkA molecular crosstalk. SFK inhibitors block ATPgammaS/P2Y(2)-promoted enhancement of NGF/TrkA signaling and neuronal differentiation in PC12 cells, abrogate the enhancement by ATPgammaS of neurite outgrowth in primary cultures of dorsal root ganglion neurons, and block co-immunoprecipitation of TrkA, P2Y(2) receptors and SFK. These results identify SFK as mediating nucleotide-enhanced neurotrophin-dependent neuronal differentiation and thus, as a key convergence point for interaction between RTKs and GPCRs.     

PAR4, but not PAR1, signals human platelet aggregation via Ca2+ mobilization and synergistic P2Y12 receptor activation

Regulation of platelet activation plays a central role in hemostasis and pathophysiological processes such as coronary artery disease. Thrombin is the most potent activator of platelets. Human platelets express two thrombin receptors, PAR1 and PAR4, both of which signal platelet activation. Evidence is lacking on the mechanism by which PAR1 and PAR4 may differentially signal platelet aggregation. Here we show that at the relatively high concentration of agonist most likely found at the site of a local thrombus, dual inhibition of the P2Y12 receptor and calcium mobilization result in a complete inhibition of PAR4-induced aggregation, while having no effect on either thrombin or PAR1-mediated platelet aggregation. Both PAR1- and PAR4mediated aggregation are independent of calcium mobilization. Furthermore, we show that P2Y12 receptor activation is not required for protease-activated receptor-mediated aggregation at higher agonist concentrations and is only partially required for Rap1 as well as GPIIbIIIa activation. P2Y12 receptor inhibitors clinically in use such as clopidogrel are postulated to decrease platelet aggregation through partial inhibition of PAR1 signaling. Our data, however, indicate that at high local concentrations of thrombin, it is the signaling through PAR4 rather than PAR1 that may be regulated through purinergic feedback. Thus, our data identify an intra-platelet mechanism that may function as a future site for therapeutic intervention.     

Dual P2Y 12 receptor signaling in thrombin-stimulated platelets--involvement of phosphoinositide 3-kinase beta but not gamma isoform in Ca2+ mobilization and procoagulant activity

During thrombus formation, thrombin, which is abundantly present at sites of vascular injury, activates platelets in part via autocrine-produced ADP. We investigated the signaling pathways by which thrombin and ADP in synergy induced platelet Ca(2+) elevation and procoagulant activity, and we monitored the consequences for the coagulation process. Even at high thrombin concentration, autocrine and added ADP enhanced and prolonged Ca(2+) depletion from internal stores via stimulation of the P2Y(12) receptors. This P2Y(12)-dependent effect was mediated via two distinct signaling pathways. The first is enhanced Ca(2+) mobilization by the inositol 1,4,5-trisphosphate receptors due to inhibition of protein kinase A. The second pathway concerns prolonged activation of phosphoinositide 3-kinase (PI3-K) and phospholipase C. Experiments with phosphoinositide 3-kinase isoform-selective inhibitors and p110gamma deficient platelets demonstrated that the phosphoinositide 3-kinase beta and not the phosphoinositide 3-kinase gamma isoform is responsible for the prolonged Ca(2+) response and for the subsequent increases in procoagulant activity and coagulation. Taken together, these results demonstrate a dual P2Y(12)-dependent signaling mechanism, which increases the platelet-activating effect of thrombin by prolongation of Ca(2+) elevation, thereby facilitating the coagulation process.