共查询到20条相似文献,搜索用时 46 毫秒
1.
Ling KK Siow NL Choi RC Ting AK Kong LW Tsim KW 《The Journal of biological chemistry》2004,279(30):31081-31088
At vertebrate neuromuscular junctions, ATP is known to stabilize acetylcholine in the synaptic vesicles and to be co-released with it. We have shown previously that a nucleotide receptor, P2Y(1) receptor, is localized at the nmjs, and we propose that this mediates a trophic role for synaptic ATP there. In cultured myotubes, the activation of P2Y(1) receptors modulated agrin-induced acetylcholine receptor (AChR) aggregation in a potentiation manner. This potentiation effect in agrin-induced AChR aggregation was reduced by antagonizing the P2Y(1) receptors. The guanosine triphosphatase RhoA was shown to be responsible for this P2Y(1)-potentiated effect. The localization of RhoA in rat and chicken skeletal muscles was restricted at the neuromuscular junctions. Application of P2Y(1) agonists in cultured myotubes induced RhoA activation, which showed an additive effect with agrin-induced RhoA activation. Over-expression of dominant-negative mutant of RhoA in cultured myotubes diminished the agrin-induced AChR aggregation, as well as the potentiation effect of P2Y(1)-specific agonist. Application of UTP in the cultures also triggered similar responses as did 2-methylthioadenosine 5'-diphosphate, suggesting the involvement of other subtypes of P2Y receptors. These results demonstrate that RhoA could serve as a downstream mediator of signaling mediated by P2Y(1) receptor and agrin, which therefore synergizes the effects of the two neuron-derived trophic factors in modulating the formation and/or maintenance of post-synaptic apparatus at the neuromuscular junctions. 相似文献
2.
The motor neuron, the Schwann cell and the muscle cell are highly specialized at the vertebrate skeletal neuromuscular junction (NMJ). The muscle cell surface contains a high local density of acetylcholine (ACh) receptors (AChRs), acetylcholinesterase (AChE) and their interacting macromolecules at the NMJ, forming the postsynaptic specializations. During the early stages of development, the incoming nerve terminal induces the formation of these postsynaptic specializations; the nerve secretes agrin and neuregulin (NRG), which are known to aggregate existing AChRs and to increase the expression of AChR at the synaptic region, respectively. In addition, adenosine 5'-triphosphate (ATP) is stored at the motor nerve terminals and is coreleased with ACh during muscle contraction. Recent evidence suggests that ATP can play a role in forming and maintaining the postsynaptic specializations by activating its corresponding receptors. In particular, one of the nucleotide receptor subtypes, the P2Y(1) receptor, is specifically localized at the NMJs. The gene expression of AChR and AChE is upregulated after the activation of P2Y(1) receptors. Thus, the synaptic ATP together with agrin and NRG can act as a synapse-organizing factor to induce the expression of postsynaptic functional effectors. 相似文献
3.
Following vessel wall injury, platelets adhere to the exposed subendothelium, become activated and release mediators such
as TXA2 and nucleotides stored at very high concentration in the so-called dense granules. Released nucleotides and other soluble
agents act in a positive feedback mechanism to cause further platelet activation and amplify platelet responses induced by
agents such as thrombin or collagen. Adenine nucleotides act on platelets through three distinct P2 receptors: two are G protein-coupled
ADP receptors, namely the P2Y1 and P2Y12 receptor subtypes, while the P2X1 receptor ligand-gated cation channel is activated by ATP. The P2Y1 receptor initiates platelet aggregation but is not sufficient for a full platelet aggregation in response to ADP, while the
P2Y12 receptor is responsible for completion of the aggregation to ADP. The latter receptor, the molecular target of the antithrombotic
drugs clopidogrel, prasugrel and ticagrelor, is responsible for most of the potentiating effects of ADP when platelets are
stimulated by agents such as thrombin, collagen or immune complexes. The P2X1 receptor is involved in platelet shape change and in activation by collagen under shear conditions. Each of these receptors
is coupled to specific signal transduction pathways in response to ADP or ATP and is differentially involved in all the sequential
events involved in platelet function and haemostasis. As such, they represent potential targets for antithrombotic drugs. 相似文献
4.
Biased agonism describes a multistate model of G protein-coupled receptor activation in which each ligand induces a unique structural conformation of the receptor, such that the receptor couples differentially to G proteins and other intracellular proteins. P2Y receptors are G protein-coupled receptors that are activated by endogenous nucleotides, such as adenosine 5′-triphosphate (ATP) and uridine 5′-triphosphate (UTP). A previous report suggested that UTP may be a biased agonist at the human P2Y11 receptor, as it increased cytosolic [Ca2+], but did not induce accumulation of inositol phosphates, whereas ATP did both. The mechanism of action of UTP was unclear, so the aim of this study was to characterise the interaction of UTP with the P2Y11 receptor in greater detail. Intracellular Ca2+ was monitored in 1321N1 cells stably expressing human P2Y11 receptors using the Ca2+-sensitive fluorescent indicator, fluo-4. ATP evoked a rapid, concentration-dependent rise in intracellular Ca2+, but surprisingly, even high concentrations of UTP were ineffective. In contrast, UTP was slightly, but significantly more potent than ATP in evoking a rise in intracellular Ca2+ in 1321N1 cells stably expressing the human P2Y2 receptor, with no difference in the maximum response. Thus, the lack of response to UTP at hP2Y11 receptors was not due to a problem with the UTP solution. Furthermore, coapplying a high concentration of UTP with ATP did not inhibit the response to ATP. Thus, contrary to a previous report, we find no evidence for an agonist action of UTP at the human P2Y11 receptor, nor does UTP act as an antagonist. 相似文献
5.
This work addresses the physiological regulation of skeletal muscle acetylcholinesterase (AChE) isoforms by examining endplate-enriched samples from adult rat gracilis muscles 48 h after: lowintensity treadmill exercise; obturator nerve transection; nerve impulse conduction blockade by tetrodotoxin; acetylcholine (ACh) receptor (AChR) inactivation by -bungarotoxin; and, addition of obturator nerve extracts to muscles in organ culture. Results document the important role(s) of functional AChRs and ACh-AChR interactions in the differential control of individual AChE isoenzymes. A theoretical model based on these and other findings considers that: AChR activation by spontaneously released ACh is the only neural factor required for the maintenance of G1+G2 AChE; the amount of A12 AChE is determined by the combined effects of ACh and another neurogenic substance; although mechanisms intrinsic to myofibers control normal levels of G4 AChE, enhanced production of this isoform is initiated through increasing the frequency of ACh-AChR interactions.Special issue dedicated to Dr. Frederick E. Samson 相似文献
6.
Giovanna Maraula Daniele Lana Elisabetta Coppi Francesca Gentile Tommaso Mello Alessia Melani Andrea Galli Maria Grazia Giovannini Felicita Pedata Anna Maria Pugliese 《PloS one》2014,9(12)
Purinergic P2X and P2Y receptors are broadly expressed on both neurons and glial cells in the central nervous system (CNS), including dentate gyrus (DG). The aim of this research was to determine the synaptic and proliferative response of the DG to severe oxygen and glucose deprivation (OGD) in acute rat hippocampal slices and to investigate the contribution of P2X7 and P2Y1 receptor antagonism to recovery of synaptic activity after OGD. Extracellular field excitatory post-synaptic potentials (fEPSPs) in granule cells of the DG were recorded from rat hippocampal slices. Nine-min OGD elicited an irreversible loss of fEPSP and was invariably followed by the appearance of anoxic depolarization (AD). Application of MRS2179 (selective antagonist of P2Y1 receptor) and BBG (selective antagonist of P2X7 receptor), before and during OGD, prevented AD appearance and allowed a significant recovery of neurotransmission after 9-min OGD. The effects of 9-min OGD on proliferation and maturation of cells localized in the subgranular zone (SGZ) of slices prepared from rats treated with 5-Bromo-2′-deoxyuridine (BrdU) were investigated. Slices were further incubated with an immature neuron marker, doublecortin (DCX). The number of BrdU+ cells in the SGZ was significantly decreased 6 hours after OGD. This effect was antagonized by BBG, but not by MRS2179. Twenty-four hours after 9-min OGD, the number of BrdU+ cells returned to control values and a significant increase of DCX immunofluorescence was observed. This phenomenon was still evident when BBG, but not MRS2179, was applied during OGD. Furthermore, the P2Y1 antagonist reduced the number of BrdU+ cells at this time. The data demonstrate that P2X7 and P2Y1 activation contributes to early damage induced by OGD in the DG. At later stages after the insult, P2Y1 receptors might play an additional and different role in promoting cell proliferation and maturation in the DG. 相似文献
7.
This work shows that ATP activates JNK1, but not JNK2, in rat osteoblasts and ROS-A 17/2.8 osteoblast-like cells. In ROS-A 17/2.8 cells ATP induced JNK1 phosphorylation in a dose- and time-dependent manner. JNK1 phosphorylation also increased after osteoblast stimulation with ATPγS and UTP, but not with ADPβS. RT-PCR studies supported the expression of P2Y2 receptor subtype. ATP-induced JNK1 activation was reduced by PI-PLC, IP3 receptor, PKC and Src inhibitors and by gadolinium, nifedipine and verapamil or a Ca2+-free medium. ERK 1/2 or p38 MAPK inhibitors diminished JNK1 activation by ATP, suggesting a cross-talk between these pathways. ATP stimulated osteoblast-like cell proliferation consistent with the participation of P2Y2 receptors. These results show that P2Y2 receptor stimulation by ATP induces JNK1 phosphorylation in ROS-A 17/2.8 cells in a way dependent on PI-PLC/IP3/intracellular Ca2+ release and Ca2+ influx through stress activated and L-type voltage-dependent calcium channels and involves PKC and Src kinases. 相似文献
8.
Tassya Cataldi Cardoso Thaís Emanuelle Pompeu Claudia Lucia Martins Silva 《Purinergic signalling》2017,13(3):331-338
Extracellular ATP (released by endothelial and immune cells) and its metabolite ADP are important pro-inflammatory mediators via the activation of purinergic P2 receptors (P2Y and P2X), which represent potential new targets for anti-inflammatory therapy. Endothelial P2Y1 receptor (P2Y1R) induces endothelial cell activation triggering leukocyte adhesion. A number of data have implicated melatonin as a modulator of immunity, inflammation, and endothelial cell function, but to date no studies have investigated whether melatonin modulates endothelial P2YR signaling. Here, we evaluated the putative effect of melatonin on P2Y1R-mediated leukocyte adhesion to endothelial cells and TNF-α production, using mesenteric endothelial cells and fresh peripheral blood mononuclear cells isolated from rats. Endothelial cells were treated with the P2Y1R agonist 2MeSATP, alone or in combination with melatonin, and then exposed to mononuclear cells. 2MeSATP increased leukocyte adhesion to endothelial cells and TNF-α production in vitro, and melatonin inhibited both effects without altering P2Y1R protein expression. In addition, assays with the Ca2+ chelator BAPTA-AM indicate that the effect of melatonin on 2MeSATP-stimulated leukocyte adhesion depends on intracellular Ca2+ modulation. P2Y1R is considered a potential target to control chronic inflammation. Therefore, our data unveiled a new endothelial cell modulator of purinergic P2Y1 receptor signaling. 相似文献
9.
10.
Rui Xie Jingyu Xu Guorong Wen Hai Jin Xuemei Liu Yuan Yang Bei Ji Yixia Jiang Penghong Song Hui Dong Biguang Tuo 《The Journal of biological chemistry》2014,289(27):19137-19149
ATP is an abundant biochemical component of the tumor microenvironment and a physiologic ligand for the P2Y2 nucleotide receptor (P2Y2R). In this study, we investigated the effect of ATP on the cellular behavior of human hepatocellular carcinoma (HCC) cells and the role of P2Y2R in ATP action and aimed to find a new therapeutic target against HCC. The experiments were performed in native isolated human HCC cells, normal hepatocytes, human HCC cell lines, and nude mice. We found that the mRNA and protein expression levels of P2Y2R in native human HCC cells and the human HCC cell lines HepG2 and BEL-7404 were enhanced markedly compared with human normal hepatocytes and the normal hepatocyte line LO2, respectively. ATP induced intracellular Ca2+ increases in HCC cells and promoted the proliferation and migration of HCC cells and the growth of HCC in nude mice. The P2Y receptor antagonist suramin, P2Y2R-specific shRNA, the store-operated calcium channel inhibitors 2-aminoethoxydiphenyl borate (2-APB) and 1-(β-3-(4-methoxy-phenyl) propoxyl-4-methoxyphenethyl)1H-imidazole-hydrochloride (), and stromal interaction molecule (STIM1)-specific shRNA inhibited the action of ATP on HCC cells. In conclusion, P2Y2R mediated the action of ATP on the cellular behavior of HCC cells through store-operated calcium channel-mediated Ca2+ signaling, and targeting P2Y2R may be a promising therapeutic strategy against human HCC. SKF96365相似文献
11.
The human P2Y1 receptor was expressed in the yeast Saccharomyces cerevisiae strain MPY578q5, which is engineered to couple to mammalian G protein-coupled receptors (GPCRs) and requires agonist-induced activation for
growth. A range of known P2Y1 receptor agonists were examined with the yeast growth assay system, and the results were validated by comparing with potencies
in the transfected 1321N1 astrocytoma cell line, in which calcium mobilization was measured with a FLIPR (fluorometric-imaging
plate reader). The data were also compared with those from phospholipase C activation and radioligand binding with the use
of a newly available radioligand [3H]MRS2279 (2-chloro-N
6-methyl-(N)-methanocarba-2’-deoxyadenosine-3’,5’bisphosphate). In the yeast growth assay, the rank order of potency of 2-MeSADP (2-methylthioadenosine
5’-diphosphate), ADP (adenosine 5’-diphosphate), and ATP (adenosine 5’-triphosphate) is the same as those in other assay systems,
i.e., 2-MeSADP>ADP>ATP. The P2Y1-selective antagonist MRS2179 (N
6-methyl-2-deoxyadenosine-3’,5’-bisphosphate) was shown to act as an antagonist with similar potency in all systems. The results
suggest that the yeast expression system is suitable for screening P2Y1 receptor ligands, both agonists and antagonists. The yeast system should be useful for random mutagenesis of GPCRs to identify
mutants with certain properties, such as selective potency enhancement for small synthetic molecules and constitutive activity. 相似文献
12.
The role of pannexin 1 in the purinergic regulation of synaptic transmission in mouse motor synapses
A. S. Miteva A. E. Gaydukov V. I. Shestopalov O. P. Balezina 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2017,11(4):311-320
The role of pannexin 1 in the release to the extracellular space of ATP/adenosine modulating the acetylcholine (ACh) secretion was studied in mouse diaphragm motor synapses. Using neuromuscular preparations obtained from wild-type and pannexin-1 knockout mice, the miniature endplate potential (MEPPs) and evoked endplate potentials (EPPs) were recorded in combination with pharmacological modulation of P2-type ATP receptors and A1-type adenosine receptors. Selective inhibition of A1 receptors with DPCPX or P2 receptors with PPADS increased quantal content of EPPs in wild-type mice. MRS 2211, selective antagonist of P2Y13 receptors, produced the same effect. Activation of receptors A1 or P2Y13 by their agonists (2-CADO and IDP, respectively) decreased the EPP quantal content. It means that the activity of endogenous ATP and adenosine is synergistic and directed to depression of the ACh release. ARL67156, an inhibitor of synaptic ecto-ATPases, which blocks the hydrolysis of ATP to adenosine and increases the level of ATP in the synaptic cleft, prolonged EPPs without changing their quantal content. In pannexin-1 knockout mice there were no changes in the EPP quantal content and in other parameters of synaptic transmission as compared to wildtype mice. However, downregulation of purinergic effects with antagonists of A1 or P2 receptors (DPCPX, PPADS, MRS 2211) did not change EPP quantal content and any other parameters of spontaneous or evoked ACh release in all cases. ARL67156 did not alter the temporal parameters of EPPs, either. Nevertheless, 2-CADO, the A1-type receptor agonist, decreased the EPP quantal content, while the agonist of P2Y13 receptors decreased the MEPP amplitude. Thus, in mice lacking pannexin 1, procedures revealing the presence and regulatory activity of synaptic ATP/adenosine did not change the parameters of synaptic transmission. The obtained data substantiate a mandatory role of pannexin 1 in the purinergic regulation of motor synapse activity by endogenous ATP/adenosine. 相似文献
13.
Adenosine triphosphate (ATP) is coreleased with catecholamines from adrenal medullary chromaffin cells in response to sympathetic
nervous system stimulation and may regulate these cells in an autocrine or paracrine manner. Increases in extracellular signal-regulated
kinase (ERK) 1/2 phosphorylation were observed in response to ATP stimulation of bovine chromaffin cells. The signaling pathway
involved in ATP-mediated ERK1/2 phosphorylation was investigated via Western blot analysis. ATP and uridine 5′-triphosphate
(UTP) increased ERK1/2 phosphorylation potently, peaking between 5 and 15 min. The mitogen-activated protein kinase (MAPK/ERK)-activating
kinase (MEK) inhibitor PD98059 blocked this response. UTP, which is selective for G-protein-coupled P2Y receptors, was the
most potent agonist among several nucleotides tested. Adenosine 5′-O-(3-thio) triphosphate (ATPγS) and ATP were also potent
agonists, characteristic of the P2Y2 or P2Y4 receptor subtypes, whereas agonists selective for P2X receptors or other P2Y receptor subtypes were weakly effective. The
receptor involved was further characterized by the nonspecific P2 antagonists suramin and reactive blue 2, which each partially
inhibited ATP-mediated ERK1/2 phosphorylation. Inhibitors of protein kinase C (PKC), protein kinase A (PKA), Ca2+/calmodulin-dependent protein kinase II (CaMKII), and phosphoinositide-3 kinase (PI3K) had no effect on ATP-mediated ERK1/2
phosphorylation. The Src inhibitor PP2, epidermal growth factor receptor (EGFR) inhibitor AG1478, and metalloproteinase inhibitor
GM6001 decreased ATP-mediated ERK1/2 phosphorylation. These results suggest nucleotide-mediated ERK1/2 phosphorylation is
mediated by a P2Y2 or P2Y4 receptor, which stimulates metalloproteinase-dependent transactivation of the EGFR. 相似文献
14.
Jacob M. Dundee Mar Puigdellívol Richard Butler Thomas O. J. Cockram Guy C. Brown 《Aging cell》2023,22(2):e13761
Aging causes loss of brain synapses and memory, and microglial phagocytosis of synapses may contribute to this loss. Stressed neurons can release the nucleotide UTP, which is rapidly converted into UDP, that in turn activates the P2Y6 receptor (P2Y6R) on the surface of microglia, inducing microglial phagocytosis of neurons. However, whether the activation of P2Y6R affects microglial phagocytosis of synapses is unknown. We show here that inactivation of P2Y6R decreases microglial phagocytosis of isolated synapses (synaptosomes) and synaptic loss in neuronal–glial co-cultures. In vivo, wild-type mice aged from 4 to 17 months exhibited reduced synaptic density in cortical and hippocampal regions, which correlated with increased internalization of synaptic material within microglia. However, this aging-induced synaptic loss and internalization were absent in P2Y6R knockout mice, and these mice also lacked any aging-induced memory loss. Thus, P2Y6R appears to mediate aging-induced loss of synapses and memory by increasing microglial phagocytosis of synapses. Consequently, blocking P2Y6R has the potential to prevent age-associated memory impairment. 相似文献
15.
16.
Receptors for purines and pyrimidines are expressed throughout the cardiovascular system. This study investigated their functional expression in porcine isolated pancreatic arteries. Pancreatic arteries (endothelium intact or denuded) were prepared for isometric tension recording and preconstricted with U46619, a thromboxane A2 mimetic; adenosine-5′-diphosphate (ADP), uridine-5′-triphosphate (UTP) and MRS2768, a selective P2Y2 agonist, were applied cumulatively, while adenosine-5′-triphosphate (ATP) and αβ-methylene-ATP (αβ-meATP) response curves were generated from single concentrations per tissue segment. Antagonists/enzyme inhibitors were applied prior to U46619 addition. ATP, αβ-meATP, UTP and MRS2768 induced vasoconstriction, with a potency order of αβ-meATP > MRS2768 > ATP ≥ UTP. Contractions to ATP and αβ-meATP were blocked by NF449, a selective P2X1 receptor antagonist. The contraction induced by ATP, but not UTP, was followed by vasorelaxation. Endothelium removal and DUP 697, a cyclooxygenase-2 inhibitor, had no significant effect on contraction to ATP but attenuated that to UTP, indicating actions at distinct receptors. MRS2578, a selective P2Y6 receptor antagonist, had no effect on contractions to UTP. ADP induced endothelium-dependent vasorelaxation which was inhibited by MRS2179, a selective P2Y1 receptor antagonist, or SCH58261, a selective adenosine A2A receptor antagonist. The contractions to ATP and αβ-meATP were attributed to actions at P2X1 receptors on the vascular smooth muscle, whereas it was shown for the first time that UTP induced an endothelium-dependent vasoconstriction which may involve P2Y2 and/or P2Y4 receptors. The relaxation induced by ADP is mediated by P2Y1 and A2A adenosine receptors. Porcine pancreatic arteries appear to lack vasorelaxant P2Y2 and P2Y4 receptors. 相似文献
17.
Jacob M. Dundee Mar Puigdellívol Richard Butler Thomas O. J. Cockram Guy C. Brown 《Aging cell》2023,22(2)
Aging causes loss of brain synapses and memory, and microglial phagocytosis of synapses may contribute to this loss. Stressed neurons can release the nucleotide UTP, which is rapidly converted into UDP, that in turn activates the P2Y6 receptor (P2Y6R) on the surface of microglia, inducing microglial phagocytosis of neurons. However, whether the activation of P2Y6R affects microglial phagocytosis of synapses is unknown. We show here that inactivation of P2Y6R decreases microglial phagocytosis of isolated synapses (synaptosomes) and synaptic loss in neuronal–glial co‐cultures. In vivo, wild‐type mice aged from 4 to 17 months exhibited reduced synaptic density in cortical and hippocampal regions, which correlated with increased internalization of synaptic material within microglia. However, this aging‐induced synaptic loss and internalization were absent in P2Y6R knockout mice, and these mice also lacked any aging‐induced memory loss. Thus, P2Y6R appears to mediate aging‐induced loss of synapses and memory by increasing microglial phagocytosis of synapses. Consequently, blocking P2Y6R has the potential to prevent age‐associated memory impairment. 相似文献
18.
Troy S. Peterson Jean M. Camden Yanfang Wang Cheikh I. Seye W. G. Wood Grace Y. Sun Laurie Erb Michael J. Petris Gary A. Weisman 《Molecular neurobiology》2010,41(2-3):356-366
Acute inflammation is important for tissue repair; however, chronic inflammation contributes to neurodegeneration in Alzheimer's disease (AD) and occurs when glial cells undergo prolonged activation. In the brain, stress or damage causes the release of nucleotides and activation of the Gq protein-coupled P2Y2 nucleotide receptor subtype (P2Y2R) leading to pro-inflammatory responses that can protect neurons from injury, including the stimulation and recruitment of glial cells. P2Y2R activation induces the phosphorylation of the epidermal growth factor receptor (EGFR), a response dependent upon the presence of a SH3 binding domain in the intracellular C terminus of the P2Y2R that promotes Src binding and transactivation of EGFR, a pathway that regulates the proliferation of cortical astrocytes. Other studies indicate that P2Y2R activation increases astrocyte migration. P2Y2R activation by UTP increases the expression in astrocytes of αVβ3/5 integrins that bind directly to the P2Y2R via an Arg-Gly-Asp (RGD) motif in the first extracellular loop of the P2Y2R, an interaction required for Go and G12 protein-dependent astrocyte migration. In rat primary cortical neurons (rPCNs) P2Y2R expression is increased by stimulation with interleukin-1β (IL-1β), a pro-inflammatory cytokine whose levels are elevated in AD, in part due to nucleotide-stimulated release from glial cells. Other results indicate that oligomeric β-amyloid peptide (Aβ1-42), a contributor to AD, increases nucleotide release from astrocytes, which would serve to activate upregulated P2Y2Rs in neurons. Data with rPCNs suggest that P2Y2R upregulation by IL-1β and subsequent activation by UTP are neuroprotective, since this increases the non-amyloidogenic cleavage of amyloid precursor protein. Furthermore, activation of IL-1β-upregulated P2Y2Rs in rPCNs increases the phosphorylation of cofilin, a cytoskeletal protein that stabilizes neurite outgrowths. Thus, activation of pro-inflammatory P2Y2Rs in glial cells can promote neuroprotective responses, suggesting that P2Y2Rs represent a novel pharmacological target in neurodegenerative and other pro-inflammatory diseases. 相似文献
19.
Fabian Doktor Philipp Prager Peter Wiedemann Leon Kohen Andreas Bringmann Margrit Hollborn 《Purinergic signalling》2018,14(4):471-484
Retinal hypoxia is a major condition of the chronic inflammatory disease age-related macular degeneration. Extracellular ATP is a danger signal which is known to activate the NLRP3 inflammasome in various cell systems. We investigated in cultured human retinal pigment epithelial (RPE) cells whether hypoxia alters the expression of inflammasome-associated genes and whether purinergic receptor signaling contributes to the hypoxic expression of key inflammatory (NLRP3) and angiogenic factor (VEGF) genes. Hypoxia and chemical hypoxia were induced by a 0.2%-O2 atmosphere and addition of CoCl2, respectively. Gene expression was determined with real-time RT-PCR. Cytosolic NLRP3 and (pro-) IL-1β levels, and the extracellular VEGF level, were evaluated with Western blot and ELISA analyses. Cell culture in 0.2% O2 induced expression of NLRP3 and pro-IL-1β genes but not of the pro-IL-18 gene. Hypoxia also increased the cytosolic levels of NLRP3 and (pro-) IL-1β proteins. Inflammasome activation by lysosomal destabilization decreased the cell viability under hypoxic, but not control conditions. In addition to activation of IL-1 receptors, purinergic receptor signaling mediated by a pannexin-dependent release of ATP and a release of adenosine, and activation of P2Y2 and adenosine A1 receptors, was required for the full hypoxic expression of the NLRP3 gene. P2Y2 (but not A1) receptor signaling also contributed to the hypoxic expression and secretion of VEGF. The data indicate that hypoxia induces priming and activation of the NLRP3 inflammasome in cultured RPE cells. The hypoxic NLRP3 and VEGF gene expression and the secretion of VEGF are in part mediated by P2Y2 receptor signaling. 相似文献