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Laketa D, Lavrnja I. Extracellular Purine Metabolism-Potential Target in Multiple Sclerosis. Mol Neurobiol 2024:10.1007/s12035-024-04104-9. [PMID: 38499905 DOI: 10.1007/s12035-024-04104-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 03/07/2024] [Indexed: 03/20/2024]
Abstract
The purinergic signaling system comprises a complex network of extracellular purines and purine-metabolizing ectoenzymes, nucleotide and nucleoside receptors, ATP release channels, and nucleoside transporters. Because of its immunomodulatory function, this system is critically involved in the pathogenesis of multiple sclerosis (MS) and its best-characterized animal model, experimental autoimmune encephalomyelitis (EAE). MS is a chronic neuroinflammatory demyelinating and neurodegenerative disease with autoimmune etiology and great heterogeneity, mostly affecting young adults and leading to permanent disability. In MS/EAE, alterations were detected in almost all components of the purinergic signaling system in both peripheral immune cells and central nervous system (CNS) glial cells, which play an important role in the pathogenesis of the disease. A decrease in extracellular ATP levels and an increase in its downstream metabolites, particularly adenosine and inosine, were frequently observed at MS, indicating a shift in metabolism toward an anti-inflammatory environment. Accordingly, upregulation of the major ectonucleotidase tandem CD39/CD73 was detected in the blood cells and CNS of relapsing-remitting MS patients. Based on the postulated role of A2A receptors in the transition from acute to chronic neuroinflammation, the association of variants of the adenosine deaminase gene with the severity of MS, and the beneficial effects of inosine treatment in EAE, the adenosinergic system emerged as a promising target in neuroinflammation. More recently, several publications have identified ADP-dependent P2Y12 receptors and the major extracellular ADP producing enzyme nucleoside triphosphate diphosphohydrolase 2 (NTPDase2) as novel potential targets in MS.
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Affiliation(s)
- Danijela Laketa
- Department of General Physiology and Biophysics, Institute for Physiology and Biochemistry "Ivan Djaja", Faculty of Biology, University of Belgrade, Studentski Trg 3, Belgrade, Republic of Serbia.
| | - Irena Lavrnja
- Institute for Biological Research, Sinisa Stankovic" - National Institute of the Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, Belgrade, Republic of Serbia
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2
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Zhang S, Li B, Tang L, Tong M, Jiang N, Gu X, Zhang Y, Ge Y, Liu XL, Chen JF. Disruption of CD73-Derived and Equilibrative Nucleoside Transporter 1-Mediated Adenosine Signaling Exacerbates Oxygen-Induced Retinopathy. THE AMERICAN JOURNAL OF PATHOLOGY 2022; 192:1633-1646. [PMID: 36029802 DOI: 10.1016/j.ajpath.2022.07.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 07/10/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Retinopathy of prematurity (ROP) is characterized by pathologic angiogenesis in retina, and remains a leading cause of blindness in children. Although enhanced extracellular adenosine is markedly increased in response to retinal hypoxia, adenosine acting at the A1 and A2A receptors has the opposite effect on pathologic angiogenesis. Herein, the oxygen-induced retinopathy (OIR) model of ROP was used to demonstrate that pharmacologic and genetic inactivation of CD73 (the key 5'-ectonucleotidase for extracellular generation of adenosine) did not affect normal retinal vasculature development but exacerbated intravitreal neovascularization at postnatal day (P) 17 and delayed revascularization at P21 of OIR. This exacerbated damage to retinal vessels by CD73 inactivation was associated with increased cellular apoptosis and microglial activation but decreased astrocyte function at P17 of OIR. Furthermore, pharmacologic blockade of equilibrative nucleoside transporter 1/2 (ENT1/2; bidirectional transport for controlling the balance of intracellular and extracellular adenosine) by 6-nitrobenzylthioinosine aggravated pathologic angiogenesis at P17 of OIR. Pharmacologic blockade of ENT1/2 and genetic inactivation of CD73 also aggravated avascular areas at the hyperoxia phase (P12) of OIR. Thus, disruption of CD73-derived extracellular adenosine or ENT1/2-mediated transport of adenosine flux across membrane aggravated the damage to retinal vessels. These findings support the role of adenosine as an endogenous protective regulator that limits oxygen-induced retinopathy. Thus, enhancing extracellular adenosine signaling represents a novel neuroprotection strategy for ROP by targeting CD73 and ENT1/2 activities.
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Affiliation(s)
- Shuya Zhang
- State Key Laboratory of Optometry, Ophthalmology and Vision Science, The Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Bo Li
- State Key Laboratory of Optometry, Ophthalmology and Vision Science, The Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Lingyun Tang
- State Key Laboratory of Optometry, Ophthalmology and Vision Science, The Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Mengyun Tong
- State Key Laboratory of Optometry, Ophthalmology and Vision Science, The Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Nan Jiang
- State Key Laboratory of Optometry, Ophthalmology and Vision Science, The Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Xuejiao Gu
- State Key Laboratory of Optometry, Ophthalmology and Vision Science, The Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Yu Zhang
- State Key Laboratory of Optometry, Ophthalmology and Vision Science, The Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Yuanyuan Ge
- State Key Laboratory of Optometry, Ophthalmology and Vision Science, The Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Xiao-Ling Liu
- State Key Laboratory of Optometry, Ophthalmology and Vision Science, The Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Jiang-Fan Chen
- The Oujiang Laboratory, State Key Laboratory of Optometry, Ophthalmology and Vision Science, The Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, China.
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3
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Huang L, Guo X, Liu P, Zhao Y, Wu C, Zhou C, Huang C, Li G, Zhuang Y, Cheng S, Cao H, Zhang C, Xu Z, Liu X, Hu G, Liu P. Correlation between acute brain injury and brain metabonomics in dichlorvos-poisoned broilers. JOURNAL OF HAZARDOUS MATERIALS 2022; 422:126849. [PMID: 34416688 DOI: 10.1016/j.jhazmat.2021.126849] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 07/17/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Dichlorvos (DDVP) is an insecticide with neurotoxicity that is widely used in agricultural production and life. However, the effects of acute DDVP poisoning on brain tissue remain underinvestigated. The purpose of this study was to evaluate the differences within 15 min-6 h in plasma biochemical indexes, brain histology and metabolites among three groups of commercial broilers orally administered different dosages of DDVP one time: (1) high-dose group (11.3 mg/kg), (2) low-dose group (2.48 mg/kg) and (3) control group (0 mg/kg). The results of biochemical indexes showed that acute DDVP poisoning could cause hyperglycemia and oxidative stress in poisoned broilers. Histological examination showed that DDVP could induce brain edema, abnormal expression of glial fibrillary acidic protein (GFAP) and neuronal mitochondrial damage in broilers. Whole-brain metabolism showed that DDVP could significantly change the secretion of neurotransmitters, energy metabolism, amino acid metabolism and nucleotide metabolism. Correlation analysis showed that metabolites such as hypoxanthine, acetylcarnitine and glucose 6-phosphate were significantly correlated with blood glucose, biomarkers of oxidative stress and brain injury pathology. The results of this study provide new insights into the molecular mechanism of brain tissue responses to acute DDVP exposure in broilers and deliver important information for clinical research on neurodegenerative diseases caused by acute DDVP poisoning.
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Affiliation(s)
- Lujia Huang
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Xiaoquan Guo
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Pei Liu
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Yulan Zhao
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Cong Wu
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Changming Zhou
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Cheng Huang
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Guyue Li
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Yu Zhuang
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Sufang Cheng
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Huabin Cao
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Caiying Zhang
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Zheng Xu
- Department of Mathematics and Statistics, Wright State University, Dayton, OH 45435, United States
| | - Xin Liu
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China
| | - Guoliang Hu
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China.
| | - Ping Liu
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, China.
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Yin C, Ma Z, Li F, Duan C, Yuan Y, Zhu C, Wang L, Zhu X, Wang S, Gao P, Shu G, Zhang H, Jiang Q. Hypoxanthine Induces Muscular ATP Depletion and Fatigue via UCP2. Front Physiol 2021; 12:647743. [PMID: 33746782 PMCID: PMC7966526 DOI: 10.3389/fphys.2021.647743] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 02/11/2021] [Indexed: 01/01/2023] Open
Abstract
Hypoxanthine (Hx), an intermediate metabolite of the purine metabolism pathway which is dramatically increased in blood and skeletal muscle during muscle contraction and metabolism, is characterized as a marker of exercise exhaustion. However, the physiological effects of Hx on skeletal muscle remain unknown. Herein, we demonstrate that chronic treatment with Hx through dietary supplementation resulted in skeletal muscle fatigue and impaired the exercise performance of mice without affecting their growth and skeletal muscle development. Hx increased the uncoupling protein 2 (UCP2) expression in the skeletal muscle, which led to decreased energy substrate storage and enhanced glycolysis. These effects could also be verified in acute treatment with Hx through intraperitoneal injection. In addition, muscular specifically knockout of UCP2 through intra-muscle tissue injection of adenovirus-associated virus reversed the effects of Hx. In conclusion, we identified a novel role of Hx in the skeletal muscular fatigue mediated by UCP2-dependent mitochondrial uncoupling. This finding may shed light on the pathological mechanism of clinical muscle dysfunctions due to abnormal metabolism, such as muscle fatigue and weakness.
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Affiliation(s)
- Cong Yin
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Zewei Ma
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Fan Li
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Chen Duan
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Yexian Yuan
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Canjun Zhu
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Lina Wang
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Xiaotong Zhu
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Songbo Wang
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Ping Gao
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Gang Shu
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Huihua Zhang
- College of Life and Science, Foshan University, Foshan, China
| | - Qingyan Jiang
- Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry and Guangdong Province Key Laboratory of Animal Nutritional Regulation, College of Animal Science, South China Agricultural University, Guangzhou, China
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Dong ZSW, Cao ZP, Shang YJ, Liu QY, Wu BY, Liu WX, Li CH. Neuroprotection of cordycepin in NMDA-induced excitotoxicity by modulating adenosine A 1 receptors. Eur J Pharmacol 2019; 853:325-335. [PMID: 30978320 DOI: 10.1016/j.ejphar.2019.04.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 04/03/2019] [Accepted: 04/05/2019] [Indexed: 12/24/2022]
Abstract
Cerebral ischemia impairs physiological form of synaptic plasticity such as long-term potentiation (LTP). Clinical symptoms of cognitive dysfunction resulting from cerebral ischemia are associated with neuron loss and synaptic function impairment in hippocampus. It has been widely reported that cordycepin displays neuroprotective effect on ameliorating cognitive dysfunction induced by cerebral ischemia. Therefore, it is necessary to study whether cordycepin recovers cognitive function after brain ischemia through improving LTP induction. However, there has been very little discussion about the effects of cordycepin on LTP of cerebral ischemia so far. In the present study, we investigated the effects of cordycepin on LTP impairment and neuron loss induced by cerebral ischemia and excitotoxicity, using electrophysiological recording and Nissl staining techniques. The models were obtained by bilateral common carotid artery occlusion (BCCAO) and intrahippocampal NMDA microinjection. We also explored whether adenosine A1 receptors involve in the neuroprotection of cordycepin by using western blot. We found that cordycepin remarkably alleviated LTP impairment and protected pyramidal cell of hippocampal CA1 region against cerebral ischemia and excitotoxicity. Meanwhile, cordycepin prevented the reduction on adenosine A1 receptor level caused by ischemia but did not alter the adenosine A2A receptor level in hippocampal CA1 area. The improvement of LTP in the excitotoxic rats after cordycepin treatment could be blocked by DPCPX, a selective antagonist of adenosine A1 receptor. In summary, our findings provided new insights into the mechanisms of cordycepin neuroprotection in excitotoxic diseases, which is through regulating adenosine A1 receptor to improve LTP formation and neuronal survival.
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Affiliation(s)
| | | | | | | | - Bao-Yan Wu
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, PR China
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The ecto-enzymes CD73 and adenosine deaminase modulate 5'-AMP-derived adenosine in myofibroblasts of the rat small intestine. Purinergic Signal 2018; 14:409-421. [PMID: 30269308 DOI: 10.1007/s11302-018-9623-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 08/21/2018] [Indexed: 12/12/2022] Open
Abstract
Adenosine is a versatile signaling molecule recognized to physiologically influence gut motor functions. Both the duration and magnitude of adenosine signaling in enteric neuromuscular function depend on its availability, which is regulated by the ecto-enzymes ecto-5'-nucleotidase (CD73), alkaline phosphatase (AP), and ecto-adenosine deaminase (ADA) and by dipyridamole-sensitive equilibrative transporters (ENTs). Our purpose was to assess the involvement of CD73, APs, ecto-ADA in the formation of AMP-derived adenosine in primary cultures of ileal myofibroblasts (IMFs). IMFs were isolated from rat ileum longitudinal muscle segments by means of primary explant technique and identified by immunofluorescence staining for vimentin and α-smooth muscle actin. IMFs confluent monolayers were exposed to exogenous 5'-AMP in the presence or absence of CD73, APs, ecto-ADA, or ENTs inhibitors. The formation of adenosine and its metabolites in the IMFs medium was monitored by high-performance liquid chromatography. The distribution of CD73 and ADA in IMFs was detected by confocal immunocytochemistry and qRT-PCR. Exogenous 5'-AMP was rapidly cleared being almost undetectable after 60-min incubation, while adenosine levels significantly increased. Treatment of IMFs with CD73 inhibitors markedly reduced 5'-AMP clearance whereas ADA blockade or inhibition of both ADA and ENTs prevented adenosine catabolism. By contrast, inhibition of APs did not affect 5'-AMP metabolism. Immunofluorescence staining and qRT-PCR analysis confirmed the expression of CD73 and ADA in IMFs. Overall, our data show that in IMFs an extracellular AMP-adenosine pathway is functionally active and among the different enzymatic pathways regulating extracellular adenosine levels, CD73 and ecto-ADA represent the critical catabolic pathway.
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Pastor-Anglada M, Pérez-Torras S. Who Is Who in Adenosine Transport. Front Pharmacol 2018; 9:627. [PMID: 29962948 PMCID: PMC6010718 DOI: 10.3389/fphar.2018.00627] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/24/2018] [Indexed: 12/13/2022] Open
Abstract
Extracellular adenosine concentrations are regulated by a panel of membrane transporters which, in most cases, mediate its uptake into cells. Adenosine transporters belong to two gene families encoding Equilibrative and Concentrative Nucleoside Transporter proteins (ENTs and CNTs, respectively). The lack of appropriate pharmacological tools targeting every transporter subtype has introduced some bias on the current knowledge of the role of these transporters in modulating adenosine levels. In this regard, ENT1, for which pharmacology is relatively well-developed, has often been identified as a major player in purinergic signaling. Nevertheless, other transporters such as CNT2 and CNT3 can also contribute to purinergic modulation based on their high affinity for adenosine and concentrative capacity. Moreover, both transporter proteins have also been shown to be under purinergic regulation via P1 receptors in different cell types, which further supports its relevance in purinergic signaling. Thus, several transporter proteins regulate extracellular adenosine levels. Moreover, CNT and ENT proteins are differentially expressed in tissues but also in particular cell types. Accordingly, transporter-mediated fine tuning of adenosine levels is cell and tissue specific. Future developments focusing on CNT pharmacology are needed to unveil transporter subtype-specific events.
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Affiliation(s)
- Marçal Pastor-Anglada
- Molecular Pharmacology and Experimental Therapeutics, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine, University of Barcelona, Barcelona, Spain
- Oncology Program, National Biomedical Research Institute on Liver and Gastrointestinal Diseases – CIBER ehd, Institut de Recerca Sant Joan de Déu, Barcelona, Spain
| | - Sandra Pérez-Torras
- Molecular Pharmacology and Experimental Therapeutics, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine, University of Barcelona, Barcelona, Spain
- Oncology Program, National Biomedical Research Institute on Liver and Gastrointestinal Diseases – CIBER ehd, Institut de Recerca Sant Joan de Déu, Barcelona, Spain
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Peña-Altamira LE, Polazzi E, Giuliani P, Beraudi A, Massenzio F, Mengoni I, Poli A, Zuccarini M, Ciccarelli R, Di Iorio P, Virgili M, Monti B, Caciagli F. Release of soluble and vesicular purine nucleoside phosphorylase from rat astrocytes and microglia induced by pro-inflammatory stimulation with extracellular ATP via P2X 7 receptors. Neurochem Int 2017; 115:37-49. [PMID: 29061383 DOI: 10.1016/j.neuint.2017.10.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/12/2017] [Accepted: 10/18/2017] [Indexed: 12/31/2022]
Abstract
Purine nucleoside phosphorylase (PNP), a crucial enzyme in purine metabolism which converts ribonucleosides into purine bases, has mainly been found inside glial cells. Since we recently demonstrated that PNP is released from rat C6 glioma cells, we then wondered whether this occurs in normal brain cells. Using rat primary cultures of microglia, astrocytes and cerebellar granule neurons, we found that in basal condition all these cells constitutively released a metabolically active PNP with Km values very similar to those measured in C6 glioma cells. However, the enzyme expression/release was greater in microglia or astrocytes that in neurons. Moreover, we exposed primary brain cell cultures to pro-inflammatory agents such as lipopolysaccharide (LPS) or ATP alone or in combination. LPS alone caused an increased interleukin-1β (IL-1β) secretion mainly from microglia and no modification in the PNP release, even from neurons in which it enhanced cell death. In contrast, ATP administered alone to glial cells at high micromolar concentrations significantly stimulated the release of PNP within 1 h, an effect not modified by LPS presence, whereas IL-1β secretion was stimulated by ATP only in cells primed for 2 h with LPS. In both cases ATP effect was mediated by P2X7 receptor (P2X7R), since it was mimicked by cell exposure to Bz-ATP, an agonist of P2X7R, and blocked by cell pre-treatment with the P2X7R antagonist A438079. Interestingly, ATP-induced PNP release from glial cells partly occurred through the secretion of lysosomal vesicles in the extracellular medium. Thus, during inflammatory cerebral events PNP secretion promoted by extracellular ATP accumulation might concur to control extracellular purine signals. Further studies could elucidate whether, in these conditions, a consensual activity of enzymes downstream of PNP in the purine metabolic cascade avoids accumulation of extracellular purine bases that might concur to brain injury by unusual formation of reactive oxygen species.
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Affiliation(s)
| | - Elisabetta Polazzi
- Department of Pharmacy and Bio-Technology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Patricia Giuliani
- Department of Medical, Oral and Biotechnology Sciences, University of Chieti-Pescara, Via dei Vestini 29, 66100 Chieti, Italy; Aging Research Center and Translational Medicine (CeSI-MeT), University of Chieti-Pescara, Via dei Vestini 29, 66100 Chieti, Italy
| | - Alina Beraudi
- Department of Pharmacy and Bio-Technology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Francesca Massenzio
- Department of Pharmacy and Bio-Technology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Ilaria Mengoni
- Department of Pharmacy and Bio-Technology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Alessandro Poli
- Department of Pharmacy and Bio-Technology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Mariachiara Zuccarini
- Department of Medical, Oral and Biotechnology Sciences, University of Chieti-Pescara, Via dei Vestini 29, 66100 Chieti, Italy; Aging Research Center and Translational Medicine (CeSI-MeT), University of Chieti-Pescara, Via dei Vestini 29, 66100 Chieti, Italy
| | - Renata Ciccarelli
- Department of Medical, Oral and Biotechnology Sciences, University of Chieti-Pescara, Via dei Vestini 29, 66100 Chieti, Italy; Aging Research Center and Translational Medicine (CeSI-MeT), University of Chieti-Pescara, Via dei Vestini 29, 66100 Chieti, Italy.
| | - Patrizia Di Iorio
- Department of Medical, Oral and Biotechnology Sciences, University of Chieti-Pescara, Via dei Vestini 29, 66100 Chieti, Italy; Aging Research Center and Translational Medicine (CeSI-MeT), University of Chieti-Pescara, Via dei Vestini 29, 66100 Chieti, Italy
| | - Marco Virgili
- Department of Pharmacy and Bio-Technology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Barbara Monti
- Department of Pharmacy and Bio-Technology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Francesco Caciagli
- Department of Medical, Oral and Biotechnology Sciences, University of Chieti-Pescara, Via dei Vestini 29, 66100 Chieti, Italy; Aging Research Center and Translational Medicine (CeSI-MeT), University of Chieti-Pescara, Via dei Vestini 29, 66100 Chieti, Italy
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Di Liberto V, Mudò G, Garozzo R, Frinchi M, Fernandez-Dueñas V, Di Iorio P, Ciccarelli R, Caciagli F, Condorelli DF, Ciruela F, Belluardo N. The Guanine-Based Purinergic System: The Tale of An Orphan Neuromodulation. Front Pharmacol 2016; 7:158. [PMID: 27378923 PMCID: PMC4911385 DOI: 10.3389/fphar.2016.00158] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 05/30/2016] [Indexed: 11/17/2022] Open
Abstract
Guanine-based purines (GBPs) have been recently proposed to be not only metabolic agents but also extracellular signaling molecules that regulate important functions in the central nervous system. In such way, GBPs-mediated neuroprotection, behavioral responses and neuronal plasticity have been broadly described in the literature. However, while a number of these functions (i.e., GBPs neurothophic effects) have been well-established, the molecular mechanisms behind these GBPs-dependent effects are still unknown. Furthermore, no plasma membrane receptors for GBPs have been described so far, thus GBPs are still considered orphan neuromodulators. Interestingly, an intricate and controversial functional interplay between GBPs effects and adenosine receptors activity has been recently described, thus triggering the hypothesis that GBPs mechanism of action might somehow involve adenosine receptors. Here, we review recent data describing the GBPs role in the brain. We focus on the involvement of GBPs regulating neuronal plasticity, and on the new hypothesis based on putative GBPs receptors. Overall, we expect to shed some light on the GBPs world since although these molecules might represent excellent candidates for certain neurological diseases management, the lack of putative GBPs receptors precludes any high throughput screening intent for the search of effective GBPs-based drugs.
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Affiliation(s)
- Valentina Di Liberto
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo Palermo, Italy
| | - Giuseppa Mudò
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo Palermo, Italy
| | - Roberta Garozzo
- Department of Biomedical and Biotechnological Sciences, Unit of Medical Biochemistry, University of Catania Catania, Italy
| | - Monica Frinchi
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo Palermo, Italy
| | - Víctor Fernandez-Dueñas
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine, Bellvitge Biomedical Research Institute, Institute of Neurosciences, University of Barcelona Barcelona, Spain
| | - Patrizia Di Iorio
- Department of Medical, Oral and Biotecnological Sciences, University of Chieti-Pescara Chieti, Italy
| | - Renata Ciccarelli
- Department of Medical, Oral and Biotecnological Sciences, University of Chieti-Pescara Chieti, Italy
| | - Francesco Caciagli
- Department of Medical, Oral and Biotecnological Sciences, University of Chieti-Pescara Chieti, Italy
| | - Daniele F Condorelli
- Department of Biomedical and Biotechnological Sciences, Unit of Medical Biochemistry, University of Catania Catania, Italy
| | - Francisco Ciruela
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine, Bellvitge Biomedical Research Institute, Institute of Neurosciences, University of Barcelona Barcelona, Spain
| | - Natale Belluardo
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo Palermo, Italy
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Garcia-Esparcia P, Hernández-Ortega K, Ansoleaga B, Carmona M, Ferrer I. Purine metabolism gene deregulation in Parkinson's disease. Neuropathol Appl Neurobiol 2015; 41:926-40. [PMID: 25597950 DOI: 10.1111/nan.12221] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Accepted: 01/12/2015] [Indexed: 11/27/2022]
Abstract
AIMS To explore alterations in the expression of genes encoding enzymes involved in purine metabolism in Parkinson's disease (PD) brains as purines are the core of the DNA, RNA, nucleosides and nucleotides which participate in a wide variety of crucial metabolic pathways. METHODS Analysis of mRNA using real-time quantitative PCR of 22 genes involved in purine metabolism in the substantia nigra, putamen and cerebral cortex area 8 in PD at different stages of disease progression, and localization of selected purine metabolism-related enzymes with immunohistochemistry. RESULTS Reduced expression of adenylate kinase 2 (AKA2), AK3, AK4, adenine phosphoribosyltransferase, ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1), ENTPD3, nonmetastatic cells 3, nucleoside-diphosphatese kinase 3 (NME1), NME7 and purine nucleoside phosphorylase 1 (PNP1) mRNA in the substantia nigra at stages 3-6; up-regulation of ADA mRNA in the frontal cortex area 8 at stages 3-4 and of AK1, AK5, NME4, NME5, NME6, 5'-nucleotidase (NT5E), PNP1 and prune homolog Drosophila at stages 5-6. There is no modification in the expression of these genes in the putamen at stages 3-5. CONCLUSIONS Gene down-regulation in the substantia nigra may be interpreted as a consequence of dopaminergic cell death as ENTPD3, NME1, NME7, AK1 and PNP1 are mainly expressed in neurons. Yet ENTPD1 and NT5E, also down-regulated in the substantia nigra, are expressed in astrocytes, probably pericytes and microglia, respectively. In contrast, gene up-regulation in the frontal cortex area 8 at advanced stages of the disease suggests a primary manifestation or a compensation of altered purine metabolism in this region.
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Affiliation(s)
- Paula Garcia-Esparcia
- Institute of Neuropathology, Bellvitge University Hospital-Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.,Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED), Institute Carlos III, Ministry of Health, Barcelona, Spain
| | - Karina Hernández-Ortega
- Institute of Neuropathology, Bellvitge University Hospital-Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Belén Ansoleaga
- Institute of Neuropathology, Bellvitge University Hospital-Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Margarita Carmona
- Institute of Neuropathology, Bellvitge University Hospital-Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.,Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED), Institute Carlos III, Ministry of Health, Barcelona, Spain
| | - Isidre Ferrer
- Institute of Neuropathology, Bellvitge University Hospital-Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.,Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED), Institute Carlos III, Ministry of Health, Barcelona, Spain.,University of Barcelona, Barcelona, Spain
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Effect of ecto-5'-nucleotidase (eN) in astrocytes on adenosine and inosine formation. Purinergic Signal 2014; 10:603-9. [PMID: 25129451 PMCID: PMC4272361 DOI: 10.1007/s11302-014-9421-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 07/28/2014] [Indexed: 12/04/2022] Open
Abstract
ATP is a gliotransmitter released from astrocytes. Extracellularly, ATP is metabolized by a series of enzymes, including ecto-5′-nucleotidase (eN; also known as CD73) which is encoded by the gene 5NTE and functions to form adenosine (ADO) from adenosine monophosphate (AMP). Under ischemic conditions, ADO levels in brain increase up to 100-fold. We used astrocytes cultured from 5NTE+/+ or 5NTE−/− mice to evaluate the role of eN expressed by astrocytes in the production of ADO and inosine (INO) in response to glucose deprivation (GD) or oxygen-glucose deprivation (OGD). We also used co-cultures of these astrocytes with wild-type neurons to evaluate the role of eN expressed by astrocytes in the production of ADO and INO in response to GD, OGD, or N-methyl-d-aspartate (NMDA) treatment. As expected, astrocytes from 5NTE+/+ mice produced adenosine from AMP; the eN inhibitor α,β-methylene ADP (AOPCP) decreased ADO formation. In contrast, little ADO was formed by astrocytes from 5NTE−/− mice and AOPCP had no significant effect. GD and OGD treatment of 5NTE+/+ astrocytes and 5NTE+/+ astrocyte-neuron co-cultures produced extracellular ADO levels that were inhibited by AOPCP. In contrast, these conditions did not evoke ADO production in cultures containing 5NTE−/− astrocytes. NMDA treatment produced similar increases in ADO in both 5NTE+/+ and 5NTE−/− astrocyte-neuron co-cultures; dipyridamole (DPR) but not AOPCP inhibited ADO production. These results indicate that eN is prominent in the formation of ADO from astrocytes but in astrocyte-neuron co-cultures, other enzymes or pathways contribute to rising ADO levels in ischemia-like conditions.
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12
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Sun Z, Yathindranath V, Worden M, Thliveris JA, Chu S, Parkinson FE, Hegmann T, Miller DW. Characterization of cellular uptake and toxicity of aminosilane-coated iron oxide nanoparticles with different charges in central nervous system-relevant cell culture models. Int J Nanomedicine 2013; 8:961-70. [PMID: 23494517 PMCID: PMC3593762 DOI: 10.2147/ijn.s39048] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Background Aminosilane-coated iron oxide nanoparticles (AmS-IONPs) have been widely used in constructing complex and multifunctional drug delivery systems. However, the biocompatibility and uptake characteristics of AmS-IONPs in central nervous system (CNS)-relevant cells are unknown. The purpose of this study was to determine the effect of surface charge and magnetic field on toxicity and uptake of AmS-IONPs in CNS-relevant cell types. Methods The toxicity and uptake profile of positively charged AmS-IONPs and negatively charged COOH-AmS-IONPs of similar size were examined using a mouse brain microvessel endothelial cell line (bEnd.3) and primary cultured mouse astrocytes and neurons. Cell accumulation of IONPs was examined using the ferrozine assay, and cytotoxicity was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results No toxicity was observed in bEnd.3 cells at concentrations up to 200 μg/mL for either AmS-IONPs or COOH-AmS-IONPs. AmS-IONPs at concentrations above 200 μg/mL reduced neuron viability by 50% in the presence or absence of a magnetic field, while only 20% reductions in viability were observed with COOH-AmS-IONPs. Similar concentrations of AmS-IONPs in astrocyte cultures reduced viability to 75% but only in the presence of a magnetic field, while exposure to COOH-AmS-IONPs reduced viability to 65% and 35% in the absence and presence of a magnetic field, respectively. Cellular accumulation of AmS-IONPs was greater in all cell types examined compared to COOH-AmS-IONPs. Rank order of cellular uptake for AmS-IONPs was astrocytes > bEnd.3 > neurons. Accumulation of COOH-AmS-IONPs was minimal and similar in magnitude in different cell types. Magnetic field exposure enhanced cellular accumulation of both AmS- and COOH-AmS-IONPs. Conclusion Both IONP compositions were nontoxic at concentrations below 100 μg/mL in all cell types examined. At doses above 100 μg/mL, neurons were more sensitive to AmS-IONPs, whereas astrocytes were more vulnerable toward COOH-AmS-IONPs. Toxicity appears to be dependent on the surface coating as opposed to the amount of iron-oxide present in the cell.
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Affiliation(s)
- Zhizhi Sun
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
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13
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Chu S, Xiong W, Zhang D, Soylu H, Sun C, Albensi BC, Parkinson FE. Regulation of adenosine levels during cerebral ischemia. Acta Pharmacol Sin 2013; 34:60-6. [PMID: 23064722 DOI: 10.1038/aps.2012.127] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Adenosine is a neuromodulator with its level increasing up to 100-fold during ischemic events, and attenuates the excitotoxic neuronal injury. Adenosine is produced both intracellularly and extracellularly, and nucleoside transport proteins transfer adenosine across plasma membranes. Adenosine levels and receptor-mediated effects of adenosine are regulated by intracellular ATP consumption, cellular release of ATP, metabolism of extracellular ATP (and other adenine nucleotides), adenosine influx, adenosine efflux and adenosine metabolism. Recent studies have used genetically modified mice to investigate the relative contributions of intra- and extracellular pathways for adenosine formation. The importance of cortical or hippocampal neurons as a source or a sink of adenosine under basal and hypoxic/ischemic conditions was addressed through the use of transgenic mice expressing human equilibrative nucleoside transporter 1 (hENT1) under the control of a promoter for neuron-specific enolase. From these studies, we conclude that ATP consumption within neurons is the primary source of adenosine in neuronal cultures, but not in hippocampal slices or in vivo mice exposed to ischemic conditions.
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Soylu H, Zhang D, Buist R, Martin M, Albensi BC, Parkinson FE. Intracortical injection of endothelin-1 induces cortical infarcts in mice: effect of neuronal expression of an adenosine transporter. EXPERIMENTAL & TRANSLATIONAL STROKE MEDICINE 2012; 4:4. [PMID: 22409811 PMCID: PMC3329638 DOI: 10.1186/2040-7378-4-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 03/12/2012] [Indexed: 01/01/2023]
Abstract
Background Activation of adenosine A1 receptors has neuroprotective effects in animal stroke models. Adenosine levels are regulated by nucleoside transporters. In vitro studies showed that neuron-specific expression of human equilibrative nucleoside transporter 1 (hENT1) decreases extracellular adenosine levels and adenosine A1 receptor activity. In this study, we tested the effect of hENT1 expression on cortical infarct size following intracerebral injection of the vasoconstrictor endothelin-1 (ET-1) or saline. Methods Mice underwent stereotaxic intracortical injection of ET-1 (1 μl; 400 pmol) or saline (1 μl). Some mice received the adenosine receptor antagonist caffeine (25 mg/kg, intraperitoneal) 30 minutes prior to ET-1. Perfusion and T2-weighted magnetic resonance imaging (MRI) were used to measure cerebral blood flow (CBF) and subsequent infarct size, respectively. Results ET-1 reduced CBF at the injection site to 7.3 ± 1.3% (n = 12) in hENT1 transgenic (Tg) and 12.5 ± 2.0% (n = 13) in wild type (Wt) mice. At 48 hours following ET-1 injection, CBF was partially restored to 35.8 ± 4.5% in Tg and to 45.2 ± 6.3% in Wt mice; infarct sizes were significantly greater in Tg (9 ± 1.1 mm3) than Wt (5.4 ± 0.8 mm3) mice. Saline-treated Tg and Wt mice had modest decreases in CBF and infarcts were less than 1 mm3. For mice treated with caffeine, CBF values and infarct sizes were not significantly different between Tg and Wt mice. Conclusions ET-1 produced greater ischemic injury in hENT1 Tg than in Wt mice. This genotype difference was not observed in mice that had received caffeine. These data indicate that hENT1 Tg mice have reduced ischemia-evoked increases in adenosine receptor activity compared to Wt mice.
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Affiliation(s)
- Hanifi Soylu
- Departments of Pharmacology and Therapeutics, University of Manitoba, A404, 753 McDermot Avenue, Winnipeg, MB, Canada R3E 0 T6
| | - Dali Zhang
- Departments of Pharmacology and Therapeutics, University of Manitoba, A404, 753 McDermot Avenue, Winnipeg, MB, Canada R3E 0 T6
| | - Richard Buist
- Departments of Radiology, University of Manitoba, Winnipeg, Canada
| | - Melanie Martin
- Departments of Pharmacology and Therapeutics, University of Manitoba, A404, 753 McDermot Avenue, Winnipeg, MB, Canada R3E 0 T6.,Departments of Radiology, University of Manitoba, Winnipeg, Canada.,Department of Physics, University of Winnipeg, Winnipeg, Canada
| | - Benedict C Albensi
- Departments of Pharmacology and Therapeutics, University of Manitoba, A404, 753 McDermot Avenue, Winnipeg, MB, Canada R3E 0 T6.,Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre, Winnipeg, MB, Canada
| | - Fiona E Parkinson
- Departments of Pharmacology and Therapeutics, University of Manitoba, A404, 753 McDermot Avenue, Winnipeg, MB, Canada R3E 0 T6
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Kost S, Sun C, Xiong W, Graham K, Cass CE, Young JD, Albensi BC, Parkinson FE. Behavioral effects of elevated expression of human equilibrative nucleoside transporter 1 in mice. Behav Brain Res 2011; 224:44-9. [DOI: 10.1016/j.bbr.2011.05.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 05/16/2011] [Accepted: 05/22/2011] [Indexed: 10/18/2022]
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Absence of equilibrative nucleoside transporter 1 in ENT1 knockout mice leads to altered nucleoside levels following hypoxic challenge. Life Sci 2011; 89:621-30. [PMID: 21872611 DOI: 10.1016/j.lfs.2011.08.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 06/23/2011] [Accepted: 07/27/2011] [Indexed: 01/18/2023]
Abstract
AIMS Equilibrative nucleoside transporters (ENT) modulate the flux of adenosine. The ENT1-null (KO) mouse heart is endogenously cardioprotected but the cellular basis of this phenotype is unknown. Therefore, we investigated the cellular mechanisms underlying ENT1-mediated cardioprotection. MAIN METHODS Circulating adenosine levels were measured in WT and KO mice. Cellular levels of nucleosides and nucleotides were investigated in isolated adult cardiomyocytes from WT and KO mice using HPLC following hypoxic challenge (30 min, 2% O(2)). Changes in hypoxic gene expression were analyzed by PCR arrays and cAMP levels were measured to investigate contributions from adenosine receptors. KEY FINDINGS Circulating adenosine levels were significantly higher in KO (416±42nmol/l, n=12) compared to WT animals (208±21, n=13, p<0.001). Absence of ENT1 led to an elevated expression of genes involved in cardioprotective pathways compared to WT cardiomyocytes. Following hypoxic challenge, extracellular adenosine levels were significantly elevated in KO (4360±1840 pmol/mg protein) versus WT cardiomyocytes (3035±730 pmol/mg protein, n≥12, p<0.05). This effect was enhanced in the presence of dipyridamole (30 μM), which inhibits ENT1 and ENT2. Enhanced extracellular adenosine levels in ENT1-null cardiomyocytes appeared to come from a pool of extracellular nucleotides including IMP, AMP and ADP. Adenosine receptor (AR) activation mimicked increases in cAMP levels due to hypoxic challenge suggesting that ENT1 modulates AR-dependent signaling. SIGNIFICANCE ENT1 contributes to modulation of extracellular adenosine levels and subsequent purinergic signaling via ARs. ENT1-null mice possess elevated circulating adenosine levels and reduced cellular uptake resulting in a perpetually cardioprotected phenotype.
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Vetri F, Xu H, Mao L, Paisansathan C, Pelligrino DA. ATP hydrolysis pathways and their contributions to pial arteriolar dilation in rats. Am J Physiol Heart Circ Physiol 2011; 301:H1369-77. [PMID: 21803949 DOI: 10.1152/ajpheart.00556.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
ATP is thought to be released to the extracellular compartment by neurons and astrocytes during neural activation. We examined whether ATP exerts its effect of promoting pial arteriolar dilation (PAD) directly or upon conversion (via ecto-nucleotidase action) to AMP and adenosine. Blockade of extracellular direct ATP to AMP conversion, with ARL-67156, significantly reduced sciatic nerve stimulation-evoked PADs by 68%. We then monitored PADs during suffusions of ATP, ADP, AMP, and adenosine in the presence and absence of the following: 1) the ecto-5'-nucleotidase inhibitor α,β-methylene adenosine 5'-diphosphate (AOPCP), 2) the A(2) receptor blocker ZM 241385, 3) the ADP P2Y(1) receptor antagonist MRS 2179, and 4) ARL-67156. Vasodilations induced by 1 and 10 μM, but not 100 μM, ATP were markedly attenuated by ZM 241385, AOPCP, and ARL-67156. Substantial loss of reactivity to 100 μM ATP required coapplications of ZM 241385 and MRS 2179. Dilations induced by ADP were blocked by MRS 2179 but were not affected by either ZM 241385 or AOPCP. AMP-elicited dilation was partially inhibited by AOPCP and completely abolished by ZM 241385. Collectively, these and previous results indicate that extracellular ATP-derived adenosine and AMP, via A(2) receptors, play key roles in neural activation-evoked PAD. However, at high extracellular ATP levels, some conversion to ADP may occur and contribute to PAD through P2Y(1) activation.
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Affiliation(s)
- Francesco Vetri
- Neuroanesthesia Research, University of Illinois at Chicago, Chicago, Illinois 60612, USA
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Ruby CL, Adams CA, Knight EJ, Nam HW, Choi DS. An essential role for adenosine signaling in alcohol abuse. ACTA ACUST UNITED AC 2011; 3:163-74. [PMID: 21054262 DOI: 10.2174/1874473711003030163] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 09/20/2010] [Indexed: 12/16/2022]
Abstract
In the central nervous system (CNS), adenosine plays an important role in regulating neuronal activity and modulates signaling by other neurotransmitters, including GABA, glutamate, and dopamine. Adenosine suppresses neurotransmitter release, reduces neuronal excitability, and regulates ion channel function through activation of four classes of G protein-coupled receptors, A(1), A(2A), A(2B), and A(3). Central adenosine are largely controlled by nucleoside transporters, which transport adenosine levels across the plasma membrane. Adenosine has been shown to modulate cortical glutamate signaling and ventral-tegmental dopaminergic signaling, which are involved in several aspects of alcohol use disorders. Acute ethanol elevates extracellular adenosine levels by selectively inhibiting the type 1 equilibrative nucleoside transporter, ENT1. Raised adenosine levels mediate the ataxic and sedative/hypnotic effects of ethanol through activation of A(1) receptors in the cerebellum, striatum, and cerebral cortex. Recently, we have shown that pharmacological inhibition or genetic deletion of ENT1 reduces the expression of excitatory amino acid transporter 2 (EAAT2), the primary regulator of extracellular glutamate, in astrocytes. These lines of evidence support a central role for adenosine-mediated glutamate signaling and the involvement of astrocytes in regulating ethanol intoxication and preference. In this paper, we discuss recent findings on the implication of adenosine signaling in alcohol use disorders.
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Affiliation(s)
- Christina L Ruby
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, Minnesota 55905, USA
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Redzic ZB, Malatiali SA, Al-Bader M, Al-Sarraf H. Effects of hypoxia, glucose deprivation and recovery on the expression of nucleoside transporters and adenosine uptake in primary culture of rat cortical astrocytes. Neurochem Res 2010; 35:1434-44. [PMID: 20577800 DOI: 10.1007/s11064-010-0203-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2010] [Indexed: 01/16/2023]
Abstract
The aim of this study was to explore effects of hypoxia, glucose deprivation (HGD) and recovery on expression and activities of equilibrative nucleoside transporters (rENT) and concentrative nucleoside transporters (rCNT) in rat astrocytes in primary culture. Amounts of cellular ATP in the control group (CG, 5% CO(2) in air, medium containing 7 mM D-glucose, 1 mM Na(+)-pyruvate, 1 h), HGD group (2% O(2)/5% CO(2) in N(2), pyruvate-free medium containing 1.5 mM D-glucose and 10 mM 2-deoxy-D-glucose, 1 h) and recovery group (RG, HGD for 1 h, followed by 1 h exposure to the same conditions as the CG) were (nmol/mg protein, n = 4) 18 +/- 1.6, 4.9 +/- 0.6 and 10.1 +/- 0.8, respectively. Extracellular adenosine concentrations increased from (nM, n = 3) 42 +/- 4 in the CG, to 99 +/- 8 in the HGD group and 86 +/- 3 in the RG. Real-time PCR and immunoblotting revealed that in the HGD group and RG, the amounts of rENT1 mRNA and protein were reduced to 40 and 50%, when compared to the CG, respectively. Astrocyte cultures took up [(3)H]adenosine by concentrative and equilibrative transport processes; however, rENT1-mediated uptake was absent in the RG and cultures from the RG took up significantly less [(3)H]adenosine by equilibrative mechanisms than cultures from the CG.
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Affiliation(s)
- Zoran B Redzic
- Department of Physiology, Faculty of Medicine, Kuwait University, Safat, Kuwait.
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Kudryashov IE. Effects of some derivatives of purine nucleotides in the nervous tissue: Focus on adenosine and xanthine. NEUROCHEM J+ 2009. [DOI: 10.1134/s1819712409040011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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