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Pacini ESA, Satori NA, Jackson EK, Godinho RO. Extracellular cAMP-Adenosine Pathway Signaling: A Potential Therapeutic Target in Chronic Inflammatory Airway Diseases. Front Immunol 2022; 13:866097. [PMID: 35479074 PMCID: PMC9038211 DOI: 10.3389/fimmu.2022.866097] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 03/21/2022] [Indexed: 12/25/2022] Open
Abstract
Adenosine is a purine nucleoside that, via activation of distinct G protein-coupled receptors, modulates inflammation and immune responses. Under pathological conditions and in response to inflammatory stimuli, extracellular ATP is released from damaged cells and is metabolized to extracellular adenosine. However, studies over the past 30 years provide strong evidence for another source of extracellular adenosine, namely the “cAMP-adenosine pathway.” The cAMP-adenosine pathway is a biochemical mechanism mediated by ATP-binding cassette transporters that facilitate cAMP efflux and by specific ectoenzymes that convert cAMP to AMP (ecto-PDEs) and AMP to adenosine (ecto-nucleotidases such as CD73). Importantly, the cAMP-adenosine pathway is operative in many cell types, including those of the airways. In airways, β2-adrenoceptor agonists, which are used as bronchodilators for treatment of asthma and chronic respiratory diseases, stimulate cAMP efflux and thus trigger the extracellular cAMP-adenosine pathway leading to increased concentrations of extracellular adenosine in airways. In the airways, extracellular adenosine exerts pro-inflammatory effects and induces bronchoconstriction in patients with asthma and chronic obstructive pulmonary diseases. These considerations lead to the hypothesis that the cAMP-adenosine pathway attenuates the efficacy of β2-adrenoceptor agonists. Indeed, our recent findings support this view. In this mini-review, we will highlight the potential role of the extracellular cAMP-adenosine pathway in chronic respiratory inflammatory disorders, and we will explore how extracellular cAMP could interfere with the regulatory effects of intracellular cAMP on airway smooth muscle and innate immune cell function. Finally, we will discuss therapeutic possibilities targeting the extracellular cAMP-adenosine pathway for treatment of these respiratory diseases.
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Affiliation(s)
- Enio Setsuo Arakaki Pacini
- Division of Cellular Pharmacology, Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Naiara Ayako Satori
- Division of Cellular Pharmacology, Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Edwin Kerry Jackson
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Rosely Oliveira Godinho
- Division of Cellular Pharmacology, Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil
- *Correspondence: Rosely Oliveira Godinho,
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2
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Extracellular metabolism of 3',5'-cyclic AMP as a source of interstitial adenosine in the rat airways. Biochem Pharmacol 2021; 192:114713. [PMID: 34331910 DOI: 10.1016/j.bcp.2021.114713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 01/29/2023]
Abstract
In the respiratory tract, intracellular 3',5'-cAMP mediates smooth muscle relaxation triggered by the β2-adrenoceptor/Gs protein/adenylyl cyclase axis. More recently, we have shown that β2-adrenoceptor agonists also increase extracellular 3',5'-cAMP levels in isolated rat trachea, which leads to contraction of airway smooth muscle. In many other tissues, extracellular 3',5'-cAMP is metabolized by ectoenzymes to extracellular adenosine, a catabolic pathway that has never been addressed in airways. In order to evaluate the possible extracellular degradation of 3',5'-cAMP into 5'-AMP and adenosine in the airways, isolated rat tracheas were incubated with exogenous 3',5'-cAMP and the amount of 5'-AMP, adenosine and inosine (adenosine metabolite) produced was evaluated using ultraperformance liquid chromatography-tandem mass spectrometry. Incubation of tracheal tissue with 3',5'-cAMP induced a time- and concentration-dependent increase in 5'-AMP, adenosine and inosine in the medium. Importantly, IBMX (non-selective phosphodiesterase (PDE) inhibitor) and DPSPX (selective ecto-PDE inhibitor) reduced the extracellular conversion of 3',5'-cAMP to 5'-AMP. In addition, incubation of 3',5'-cAMP in the presence of AMPCP (inhibitor of ecto-5'-nucleotidase) increased extracellular levels of 5'-AMP while drastically reducing extracellular levels of adenosine and inosine. These results indicate that airways express an extracellular enzymatic system (ecto-phosphodiesterase, ecto-5'-nucleotidase and adenosine deaminase) that sequentially converts 3',5'-cAMP into 5'-AMP, adenosine and inosine. The observation that extracellular 3',5'-cAMP is a source of interstitial adenosine supports the idea that the extrusion and extracellular metabolism of 3',5'-cAMP has a role in respiratory physiology and pathophysiology.
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Purification of 5′-phosphodiesterase from Adzuki (Vigna angularis L.) bean. JOURNAL OF FOOD MEASUREMENT AND CHARACTERIZATION 2021. [DOI: 10.1007/s11694-020-00736-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Lv P, Wang W, Cao Z, Zhao D, Zhao G, Li D, Qi L, Xu J. Fsk and IBMX inhibit proliferation and proapoptotic of glioma stem cells via activation of cAMP signaling pathway. J Cell Biochem 2018; 120:321-331. [PMID: 30171713 DOI: 10.1002/jcb.27364] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 06/26/2018] [Indexed: 12/14/2022]
Abstract
OBJECTIVE We aimed to find out the underlying mechanism of forskolin (Fsk) and 3-isobutyl-1-methylxanthine (IBMX) on glioma stem cells (GSCs). METHODS The expression of cAMP-related protein CREB and pCREB as well as apoptosis-related proteins were detected through Western blot analysis. The level of proliferation and growth rate of human GSCs was measured through thiazolyl blue tetrazolium bromide assay and stem cells forming sphere assay. The apoptosis-related gene expression was measured through reverse transcription-polymerase chain reaction. RESULTS cAMP signaling pathway was activated in GSCs with Fsk-IBMX administration. Fsk-IBMX could inhibit the proliferation as well as invasion and promote the apoptosis of U87 cells. Besides, U0126 could inhibit MAPK signaling pathway to increase the sensitivity of GSCs to cAMP signaling pathway. As a result, Fsk-IBMX combined with U0126 had more negative effect on GSCs. CONCLUSIONS The relationship of cAMP and MAPK signaling pathway in GSCs may provide a potential therapeutic strategy in glioma.
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Affiliation(s)
- Peng Lv
- Department of Pathophysiology, Jilin Medical University, Jilin, China
| | - Weiyao Wang
- Department of Pathophysiology, Jilin Medical University, Jilin, China
| | - Zhiyou Cao
- 465 Hospital, Jilin Medical University, Jilin, China
| | - Donghai Zhao
- Department of Pathology, Jilin Medical University, Jilin, China
| | - Guifang Zhao
- Department of Pathology, Jilin Medical University, Jilin, China
| | - Dailin Li
- Institute of Petrochemical Technology, Jilin Institute of Chemical Technology, Jilin, China
| | - Ling Qi
- Department of Pathophysiology, Jilin Medical University, Jilin, China
| | - Junjie Xu
- School of Basic Medicine Sciences, Jilin Medical University, Jilin, China
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5
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Jackson EK. Discovery and Roles of 2',3'-cAMP in Biological Systems. Handb Exp Pharmacol 2017; 238:229-252. [PMID: 26721674 DOI: 10.1007/164_2015_40] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In 2009, investigators using ultra-performance liquid chromatography-tandem mass spectrometry to measure, by selected reaction monitoring, 3',5'-cAMP in the renal venous perfusate from isolated, perfused kidneys detected a large signal at the same m/z transition (330 → 136) as 3',5'-cAMP but at a different retention time. Follow-up experiments demonstrated that this signal was due to a positional isomer of 3',5'-cAMP, namely, 2',3'-cAMP. Soon thereafter, investigative teams reported the detection of 2',3'-cAMP and other 2',3'-cNMPs (2',3'-cGMP, 2',3'-cCMP, and 2',3'-cUMP) in biological systems ranging from bacteria to plants to animals to humans. Injury appears to be the major stimulus for the release of these unique noncanonical cNMPs, which likely are formed by the breakdown of RNA. In mammalian cells in culture, in intact rat and mouse kidneys, and in mouse brains in vivo, 2',3'-cAMP is metabolized to 2'-AMP and 3'-AMP; and these AMPs are subsequently converted to adenosine. In rat and mouse kidneys and mouse brains, injury releases 2',3'-cAMP, 2'-AMP, and 3'-AMP into the extracellular compartment; and in humans, traumatic brain injury is associated with large increases in 2',3'-cAMP, 2'-AMP, 3'-AMP, and adenosine in the cerebrospinal fluid. These findings motivate the extracellular 2',3'-cAMP-adenosine pathway hypothesis: intracellular production of 2',3'-cAMP → export of 2',3'-cAMP → extracellular metabolism of 2',3'-cAMP to 2'-AMP and 3'-AMP → extracellular metabolism of 2'-AMP and 3'-AMP to adenosine. Since 2',3'-cAMP has been shown to activate mitochondrial permeability transition pores (mPTPs) leading to apoptosis and necrosis and since adenosine is generally tissue protective, the extracellular 2',3'-cAMP-adenosine pathway may be a protective mechanism [i.e., removes 2',3'-cAMP (an intracellular toxin) and forms adenosine (a tissue protectant)]. This appears to be the case in the brain where deficiency in CNPase (the enzyme that metabolizes 2',3'-cAMP to 2-AMP) leads to increased susceptibility to brain injury and neurological diseases. Surprisingly, CNPase deficiency in the kidney actually protects against acute kidney injury, perhaps by preventing the formation of 2'-AMP (which turns out to be a renal vasoconstrictor) and by augmenting the mitophagy of damaged mitochondria. With regard to 2',3'-cNMPs and their downstream metabolites, there is no doubt much more to be discovered.
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Affiliation(s)
- Edwin K Jackson
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, 100 Technology Drive, Room 514, Pittsburgh, PA, 15219, USA.
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Höllerhage M, Moebius C, Melms J, Chiu WH, Goebel JN, Chakroun T, Koeglsperger T, Oertel WH, Rösler TW, Bickle M, Höglinger GU. Protective efficacy of phosphodiesterase-1 inhibition against alpha-synuclein toxicity revealed by compound screening in LUHMES cells. Sci Rep 2017; 7:11469. [PMID: 28904388 PMCID: PMC5597612 DOI: 10.1038/s41598-017-11664-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 08/25/2017] [Indexed: 01/09/2023] Open
Abstract
α-synuclein-induced neurotoxicity is a core pathogenic event in neurodegenerative synucleinopathies such as Parkinson’s disease, dementia with Lewy bodies, or multiple system atrophy. There is currently no disease-modifying therapy available for these diseases. We screened 1,600 FDA-approved drugs for their efficacy to protect LUHMES cells from degeneration induced by wild-type α-synuclein and identified dipyridamole, a non-selective phosphodiesterase inhibitor, as top hit. Systematic analysis of other phosphodiesterase inhibitors identified a specific phosphodiesterase 1 inhibitor as most potent to rescue from α-synuclein toxicity. Protection was mediated by an increase of cGMP and associated with the reduction of a specific α-synuclein oligomeric species. RNA interference experiments confirmed PDE1A and to a smaller extent PDE1C as molecular targets accounting for the protective efficacy. PDE1 inhibition also rescued dopaminergic neurons from wild-type α-synuclein induced degeneration in the substantia nigra of mice. In conclusion, this work identifies inhibition of PDE1A in particular as promising target for neuroprotective treatment of synucleinopathies.
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Affiliation(s)
- Matthias Höllerhage
- Department of Translational Neurodegeneration, German Center for Neurodegenerative Diseases (DZNE), D-81377, Munich, Germany.,Department of Neurology, Technical University of Munich, D-81675, Munich, Germany
| | - Claudia Moebius
- HT-Technology Development Studio, Max Planck Institute of Molecular Cell Biology and Genetics, D-01307, Dresden, Germany
| | - Johannes Melms
- Department of Translational Neurodegeneration, German Center for Neurodegenerative Diseases (DZNE), D-81377, Munich, Germany.,Department of Neurology, Technical University of Munich, D-81675, Munich, Germany
| | - Wei-Hua Chiu
- Department of Neurology, University of Marburg, D-35043, Marburg, Germany
| | - Joachim N Goebel
- Department of Neurology, University of Marburg, D-35043, Marburg, Germany
| | - Tasnim Chakroun
- Department of Translational Neurodegeneration, German Center for Neurodegenerative Diseases (DZNE), D-81377, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), D-81337, Munich, Germany
| | - Thomas Koeglsperger
- Department of Translational Neurodegeneration, German Center for Neurodegenerative Diseases (DZNE), D-81377, Munich, Germany.,Department of Neurology, Ludwig Maximilian University of Munich, D-81377, Munich, Germany
| | - Wolfgang H Oertel
- Department of Neurology, University of Marburg, D-35043, Marburg, Germany.,Institute of Neurogenomics, Helmholtz Center Munich, D-85764, Neuherberg, Germany
| | - Thomas W Rösler
- Department of Neurology, Technical University of Munich, D-81675, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), D-81337, Munich, Germany
| | - Marc Bickle
- HT-Technology Development Studio, Max Planck Institute of Molecular Cell Biology and Genetics, D-01307, Dresden, Germany
| | - Günter U Höglinger
- Department of Translational Neurodegeneration, German Center for Neurodegenerative Diseases (DZNE), D-81377, Munich, Germany. .,Department of Neurology, Technical University of Munich, D-81675, Munich, Germany. .,Munich Cluster for Systems Neurology (SyNergy), D-81337, Munich, Germany.
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7
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Hasan AU, Kittikulsuth W, Yamaguchi F, Musarrat Ansary T, Rahman A, Shibayama Y, Nakano D, Hitomi H, Tokuda M, Nishiyama A. IBMX protects human proximal tubular epithelial cells from hypoxic stress through suppressing hypoxia-inducible factor-1α expression. Exp Cell Res 2017; 358:343-351. [DOI: 10.1016/j.yexcr.2017.07.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 06/12/2017] [Accepted: 07/05/2017] [Indexed: 10/19/2022]
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8
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Maréchal L, Guillemette C, Goupil S, Blondin P, Leclerc P, Richard FJ. Cyclic nucleotide phosphodiesterases in human spermatozoa and seminal fluid: Presence of an active PDE10A in human spermatozoa. Biochim Biophys Acta Gen Subj 2016; 1861:147-156. [PMID: 27836756 DOI: 10.1016/j.bbagen.2016.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 10/21/2016] [Accepted: 11/04/2016] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cyclic adenosine monophosphate (cAMP) plays a crucial role as a signaling molecule for sperm functions such as capacitation, motility and acrosome reaction. It is well known that cAMP degradation by phosphodiesterase (PDE) enzyme has a major impact on sperm functions. The present study was undertaken to characterize cAMP-PDE activity in human semen. METHODS cAMP-PDE activity was measured in human sperm and seminal plasma using family specific PDE inhibitors. Three sperm fractionation methods were applied to assess cAMP-PDE activity in spermatozoa. Western blots were used to validate the presence of specific family in sperm and seminal plasma. RESULTS Using three sperm fractionation methods, we demonstrated that in human sperm, the major cAMP-PDE activity is papaverine-sensitive and thus ascribed to PDE10. In seminal plasma, total cAMP-PDE activity was 1.14±0.39fmol of cAMP hydrolyzed per minute per μg of protein. Using specific inhibitors, we showed that the major cAMP-PDE activity found in human seminal plasma is ascribed to PDE4 and PDE11. Western blot analysis, immunoprecipitation with a specific monoclonal antibody, and mass spectrometry confirmed the presence of PDE10 in human spermatozoa. CONCLUSION This study provides the first demonstration of the presence of functional PDE10 in human spermatozoa and functional PDE4 and PDE11 in human seminal plasma. GENERAL SIGNIFICANCE Since the contribution of cyclic nucleotides in several sperm functions is well known, the finding that PDE10 is an active enzyme in human spermatozoa is novel and may lead to new insight into fertility.
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Affiliation(s)
- Loïze Maréchal
- Centre de recherche en reproduction, développement et santé intergénérationnelle, Département d'obstétrique, gynécologie et reproduction, Centre de recherche du CHU de Québec-Université Laval, 2705 Boul. Laurier, Québec G1V 4G2, Canada
| | - Christine Guillemette
- Centre de recherche en reproduction, développement et santé intergénérationnelle, Département des Sciences Animales, Faculté des sciences de l'agriculture et de l'alimentation, Université Laval, Québec G1V 0A6, Québec, Canada
| | - Serge Goupil
- Centre de recherche en reproduction, développement et santé intergénérationnelle, Département d'obstétrique, gynécologie et reproduction, Centre de recherche du CHU de Québec-Université Laval, 2705 Boul. Laurier, Québec G1V 4G2, Canada
| | - Patrick Blondin
- L'Alliance Boviteq Inc, 19320 Grand rang St-François, Saint-Hyacinthe, Québec J2T 5H1, Canada
| | - Pierre Leclerc
- Centre de recherche en reproduction, développement et santé intergénérationnelle, Département d'obstétrique, gynécologie et reproduction, Centre de recherche du CHU de Québec-Université Laval, 2705 Boul. Laurier, Québec G1V 4G2, Canada
| | - François J Richard
- Centre de recherche en reproduction, développement et santé intergénérationnelle, Département des Sciences Animales, Faculté des sciences de l'agriculture et de l'alimentation, Université Laval, Québec G1V 0A6, Québec, Canada.
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9
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Bergeron A, Aragon JP, Guillemette C, Hébert A, Sullivan R, Blondin P, Richard FJ. Characterization of cAMP-phosphodiesterase activity in bovine seminal plasma. Andrology 2016; 4:1123-1130. [PMID: 27565610 DOI: 10.1111/andr.12267] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 06/22/2016] [Accepted: 07/14/2016] [Indexed: 12/11/2022]
Abstract
The second messenger cyclic adenosine monophosphate (cAMP) has a central role in sperm physiology. Extracellular cAMP can be sequentially degraded into 5'AMP and adenosine by ecto-phosphodiesterases (ecto-PDE) and ecto-nucleotidases, a phenomenon called extracellular cAMP-adenosine pathway. As cAMP-adenosine pathway is involved in sperm capacitation, we hypothesize that extracellular PDEs are functionally present in seminal plasma. Exclusively measuring cAMP-PDE activity, total activity in bovine seminal plasma was 10.1 ± 1.5 fmoles/min/μg. Using different family-specific PDE inhibitors, we showed that in seminal plasma, the major cAMP-PDE activity was papaverine sensitive (47.5%). These data support the presence of PDE10 in bovine seminal plasma and was further confirmed by western blot. In epididymal fluid, total cAMP-PDE activity was 48.2 ± 14.8 fmoles/min/μg and we showed that the major cAMP-PDE activity was 3-isobutyl-methylxanthine insensitive and thus ascribed to PDE8 family. PDE10A mRNAs were found in the testis, epididymis, and seminal vesicles. cAMP-PDE activity is present in bovine seminal plasma and epididymal fluid. The results suggest a role for ecto-PDEs present in those fluids in the signaling pathways involved in sperm functions.
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Affiliation(s)
- A Bergeron
- Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle, Université Laval, Québec, QC, Canada.,Département des Sciences Animales, Faculté des Sciences de L'agriculture et de L'alimentation, Université Laval, Québec, QC, Canada
| | - J P Aragon
- Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle, Université Laval, Québec, QC, Canada.,Département des Sciences Animales, Faculté des Sciences de L'agriculture et de L'alimentation, Université Laval, Québec, QC, Canada
| | - C Guillemette
- Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle, Université Laval, Québec, QC, Canada.,Département des Sciences Animales, Faculté des Sciences de L'agriculture et de L'alimentation, Université Laval, Québec, QC, Canada
| | - A Hébert
- Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle, Université Laval, Québec, QC, Canada.,Département des Sciences Animales, Faculté des Sciences de L'agriculture et de L'alimentation, Université Laval, Québec, QC, Canada
| | - R Sullivan
- Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle, Université Laval, Québec, QC, Canada.,Département Obstétrique, Gynécologie et Reproduction, Faculté de Médecine, Université Laval, Québec, QC, Canada
| | - P Blondin
- Boviteq, Saint-Hyacinthe, QC, Canada
| | - F J Richard
- Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle, Université Laval, Québec, QC, Canada.,Département des Sciences Animales, Faculté des Sciences de L'agriculture et de L'alimentation, Université Laval, Québec, QC, Canada
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10
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Jackson EK, Boison D, Schwarzschild MA, Kochanek PM. Purines: forgotten mediators in traumatic brain injury. J Neurochem 2016; 137:142-53. [PMID: 26809224 DOI: 10.1111/jnc.13551] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 01/13/2016] [Accepted: 01/14/2016] [Indexed: 12/12/2022]
Abstract
Recently, the topic of traumatic brain injury has gained attention in both the scientific community and lay press. Similarly, there have been exciting developments on multiple fronts in the area of neurochemistry specifically related to purine biology that are relevant to both neuroprotection and neurodegeneration. At the 2105 meeting of the National Neurotrauma Society, a session sponsored by the International Society for Neurochemistry featured three experts in the field of purine biology who discussed new developments that are germane to both the pathomechanisms of secondary injury and development of therapies for traumatic brain injury. This included presentations by Drs. Edwin Jackson on the novel 2',3'-cAMP pathway in neuroprotection, Detlev Boison on adenosine in post-traumatic seizures and epilepsy, and Michael Schwarzschild on the potential of urate to treat central nervous system injury. This mini review summarizes the important findings in these three areas and outlines future directions for the development of new purine-related therapies for traumatic brain injury and other forms of central nervous system injury. In this review, novel therapies based on three emerging areas of adenosine-related pathobiology in traumatic brain injury (TBI) were proposed, namely, therapies targeting 1) the 2',3'-cyclic adenosine monophosphate (cAMP) pathway, 2) adenosine deficiency after TBI, and 3) augmentation of urate after TBI.
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Affiliation(s)
- Edwin K Jackson
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Detlev Boison
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, Oregon, USA
| | - Michael A Schwarzschild
- Department of Neurology, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Patrick M Kochanek
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.,Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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11
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Jackson EK. The 2',3'-cAMP-adenosine pathway. Am J Physiol Renal Physiol 2011; 301:F1160-7. [PMID: 21937608 PMCID: PMC3233866 DOI: 10.1152/ajprenal.00450.2011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 09/15/2011] [Indexed: 01/11/2023] Open
Abstract
Our recent studies employing HPLC-tandem mass spectrometry to analyze venous perfusate from isolated, perfused kidneys demonstrate that intact kidneys produce and release into the extracellular compartment 2',3'-cAMP, a positional isomer of the second messenger 3',5'-cAMP. To our knowledge, this represents the first detection of 2',3'-cAMP in any cell/tissue/organ/organism. Nuclear magnetic resonance experiments with isolated RNases and experiments in isolated, perfused kidneys suggest that 2',3'-cAMP likely arises from RNase-mediated transphosphorylation of mRNA. Both in vitro and in vivo kidney experiments demonstrate that extracellular 2',3'-cAMP is efficiently metabolized to 2'-AMP and 3'-AMP, both of which can be further metabolized to adenosine. This sequence of reactions is called the 2',3'-cAMP-adenosine pathway (2',3'-cAMP → 2'-AMP/3'-AMP → adenosine). Experiments in rat and mouse kidneys show that metabolic poisons increase extracellular levels of 2',3'-cAMP, 2'-AMP, 3'-AMP, and adenosine; however, little is known regarding the pharmacology of 2',3'-cAMP, 2'-AMP, and 3'-AMP. What is known is that 2',3'-cAMP facilitates activation of mitochondrial permeability transition pores, a process that can lead to apoptosis and necrosis, and inhibits proliferation of vascular smooth muscle cells and glomerular mesangial cells. In summary, there is mounting evidence that at least some types of cellular injury, by triggering mRNA degradation, engage the 2',3'-cAMP-adenosine pathway, and therefore this pathway should be added to the list of biochemical pathways that produce adenosine. Although speculative, it is possible that the 2',3'-cAMP-adenosine pathway may protect against some forms of acute organ injury, for example acute kidney injury, by both removing an intracellular toxin (2',3'-cAMP) and increasing an extracellular renoprotectant (adenosine).
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Affiliation(s)
- Edwin K Jackson
- Dept. of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, 100 Technology Drive, Pittsburgh, PA 15219, USA.
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12
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Verrier JD, Exo JL, Jackson TC, Ren J, Gillespie DG, Dubey RK, Kochanek PM, Jackson EK. Expression of the 2',3'-cAMP-adenosine pathway in astrocytes and microglia. J Neurochem 2011; 118:979-87. [PMID: 21777245 PMCID: PMC3166383 DOI: 10.1111/j.1471-4159.2011.07392.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Many organs express the extracellular 3',5'-cAMP-adenosine pathway (conversion of extracellular 3',5'-cAMP to 5'-AMP and 5'-AMP to adenosine). Some organs release 2',3'-cAMP (isomer of 3',5'-cAMP) and convert extracellular 2',3'-cAMP to 2'- and 3'-AMP and convert these AMPs to adenosine (extracellular 2',3'-cAMP-adenosine pathway). As astrocytes and microglia are important participants in the response to brain injury and adenosine is an endogenous neuroprotectant, we investigated whether these extracellular cAMP-adenosine pathways exist in these cell types. 2',3'-, 3',5'-cAMP, 5'-, 3'-, and 2'-AMP were incubated with mouse primary astrocytes or primary microglia for 1 h and purine metabolites were measured in the medium by mass spectrometry. There was little evidence of a 3',5'-cAMP-adenosine pathway in either astrocytes or microglia. In contrast, both cell types converted 2',3'-cAMP to 2'- and 3'-AMP (with 2'-AMP being the predominant product). Although both cell types converted 2'- and 3'-AMP to adenosine, microglia were five- and sevenfold, respectively, more efficient than astrocytes in this regard. Inhibitor studies indicated that the conversion of 2',3'-cAMP to 2'-AMP was mediated by a different ecto-enzyme than that involved in the metabolism of 2',3'-cAMP to 3'-AMP and that although CD73 mediates the conversion of 5'-AMP to adenosine, an alternative ecto-enzyme metabolizes 2'- or 3'-AMP to adenosine.
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Affiliation(s)
- Jonathan D. Verrier
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jennifer L. Exo
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Travis C. Jackson
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jin Ren
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Delbert G. Gillespie
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Raghvendra K. Dubey
- Department of Obstetrics & Gynecology, University Hospital Zurich, Switzerland
| | - Patrick M. Kochanek
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Edwin K. Jackson
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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Jackson EK, Ren J, Cheng D, Mi Z. Extracellular cAMP-adenosine pathways in the mouse kidney. Am J Physiol Renal Physiol 2011; 301:F565-73. [PMID: 21653635 PMCID: PMC3174555 DOI: 10.1152/ajprenal.00094.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 05/31/2011] [Indexed: 01/22/2023] Open
Abstract
The renal extracellular 2',3'-cAMP-adenosine and 3',5'-cAMP-adenosine pathways (extracellular cAMPs→AMPs→adenosine) may contribute to renal adenosine production. Because mouse kidneys provide opportunities to investigate renal adenosine production in genetically modified kidneys, it is important to determine whether mouse kidneys express these cAMP-adenosine pathways. We administered (renal artery) 2',3'-cAMP and 3',5'-cAMP to isolated, perfused mouse kidneys and measured renal venous secretion rates of 2',3'-cAMP, 3',5'-cAMP, 2'-AMP, 3'-AMP, 5'-AMP, adenosine, and inosine. Arterial infusions of 2',3'-cAMP increased (P < 0.0001) the mean venous secretion of 2'-AMP (390-fold), 3'-AMP (497-fold), adenosine (18-fold), and inosine (adenosine metabolite; 7-fold), but they did not alter 5'-AMP secretion. Infusions of 3',5'-cAMP did not affect venous secretion of 2'-AMP or 3'-AMP, but they increased (P < 0.0001) secretion of 5'-AMP (5-fold), adenosine (17-fold), and inosine (6-fold). Energy depletion (metabolic inhibitors) increased the secretion of 2',3'-cAMP (8-fold, P = 0.0081), 2'-AMP (4-fold, P = 0.0028), 3'-AMP (4-fold, P = 0.0270), 5'-AMP (3-fold, P = 0.0662), adenosine (2-fold, P = 0.0317), and inosine (7-fold, P = 0.0071), but it did not increase 3',5'-cAMP secretion. The 2',3'-cAMP-adenosine pathway was quantitatively similar in CD73 -/- vs. +/+ kidneys. However, 3',5'-cAMP induced a 6.7-fold greater increase in 5'-AMP, an attenuated increase (61% reduction) in inosine and a similar increase in adenosine in CD73 -/- vs. CD73 +/+ kidneys. In mouse kidneys, 1) 2',3'-cAMP and 3',5'-cAMP are metabolized to their corresponding AMPs, which are subsequently metabolized to adenosine; 2) energy depletion activates the 2',3'-cAMP-adenosine, but not the 3',5'-cAMP-adenosine, pathway; and 3) although CD73 is involved in the 3',5'-AMP-adenosine pathway, alternative pathways of 5'-AMP metabolism and reduced metabolism of adenosine to inosine compensate for life-long deficiency of CD73.
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Affiliation(s)
- Edwin K Jackson
- Dept. of Pharmacology and Chemical Biology, Univ. of Pittsburgh School of Medicine, PA 15219, USA.
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Kukulski F, Lévesque SA, Sévigny J. Impact of ectoenzymes on p2 and p1 receptor signaling. ADVANCES IN PHARMACOLOGY 2011; 61:263-99. [PMID: 21586362 DOI: 10.1016/b978-0-12-385526-8.00009-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
P2 receptors that are activated by extracellular nucleotides (e.g., ATP, ADP, UTP, UDP, Ap(n)A) and P1 receptors activated by adenosine control a diversity of biological processes. The activation of these receptors is tightly regulated by ectoenzymes that metabolize their ligands. This review presents these enzymes as well as their roles in the regulation of P2 and P1 receptor activation. We focus specifically on the role of ectoenzymes in processes of our interest, that is, inflammation, vascular tone, and neurotransmission. An update on the development of ectonucleotidase inhibitors is also presented.
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Affiliation(s)
- Filip Kukulski
- Centre de Recherche en Rhumatologie et Immunologie, Centre Hospitalier Universitaire de Québec, Québec, Canada
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15
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Chen CC, Yang CH, Huang CC, Hsu KS. Acute stress impairs hippocampal mossy fiber-CA3 long-term potentiation by enhancing cAMP-specific phosphodiesterase 4 activity. Neuropsychopharmacology 2010; 35:1605-17. [PMID: 20237461 PMCID: PMC3055459 DOI: 10.1038/npp.2010.33] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The mossy fiber synapses onto hippocampal CA3 neurons show unique molecular features and a wide dynamic range of plasticity. Although acute stress has been well recognized to alter bidirectional long-term synaptic plasticity in the hippocampal CA1 region and dentate gyrus, it remains unclear whether the same effect may also occur at the mossy fiber-CA3 synapses. Here, we report that hippocampal slices prepared from adult mice that had experienced an acute unpredictable and inescapable restraint tail-shock stress showed a marked impairment of long-term potentiation (LTP) induced by high-frequency stimulation or adenylyl cyclase activator forskolin. This effect was prevented when animals were submitted to bilateral adrenalectomy or given the glucocorticoid receptor antagonist RU38486 before experiencing stress. In contrast, stress has no effect on synaptic potentiation induced by the non-hydrolysable and membrane-permeable cyclic adenosine 5'-monophosphate (cAMP) analog Sp-8-bromo-cAMPS. No obvious differences were observed between control and stressed mice in the basal synaptic transmission, paired-pulse facilitation, or frequency facilitation at the mossy fiber-CA3 synapses. We also found that the inhibitory effect of stress on mossy fiber LTP was obviated by the adenosine A(1) receptor antagonist 8-cyclopentyl-1,3,-dipropylxanthine, the non-specific phosphodiesterase (PDE) inhibitor 3-isobutyl-methylxanthine, and the specific PDE4 inhibitor 4-(3-butoxy-4-methoxyphenyl)methyl-2-imidazolidone. In addition, stress induces a sustained and profound increase in cAMP-specific PDE4 activity. These results suggest that the inhibition of mossy fiber LTP by acute stress treatment seems originating from a corticosterone-induced sustained increase in the PDE4 activity to accelerate the metabolism of cAMP to adenosine, in turn triggering an adenosine A(1) receptor-mediated impairment of transmitter release machinery.
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Affiliation(s)
- Chien-Chung Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chih-Hao Yang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chiung-Chun Huang
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Kuei-Sen Hsu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan,Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan,Center for Gene Regulation and Signal Transduction Research, National Cheng Kung University, Tainan, Taiwan,Department of Pharmacology, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan, Tel: +886 6235 3535 ext: 5498, Fax: +886 6274 9296, E-mail:
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16
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Abstract
We discovered that renal injury releases 2',3'-cAMP (positional isomer of 3',5'-cAMP) into the interstitium. This finding motivated a novel hypothesis: renal injury leads to activation of an extracellular 2',3'-cAMP-adenosine pathway (i.e. metabolism of extracellular 2',3'-cAMP to 3'-AMP and 2'-AMP, which are metabolized to adenosine, a retaliatory metabolite). In isolated rat kidneys, arterial infusions of 2',3'-cAMP (30 mumol/liter) increased the mean venous secretion of 3'-AMP (3,400-fold), 2'-AMP (26,000-fold), adenosine (53-fold), and inosine (adenosine metabolite, 30-fold). Renal injury with metabolic inhibitors increased the mean secretion of 2',3'-cAMP (29-fold), 3'-AMP (16-fold), 2'-AMP (10-fold), adenosine (4.2-fold), and inosine (6.1-fold) while slightly increasing 5'-AMP (2.4-fold). Arterial infusions of 2'-AMP and 3'-AMP increased secretion of adenosine and inosine similar to that achieved by 5'-AMP. Renal artery infusions of 2',3'-cAMP in vivo increased urinary excretion of 2'-AMP, 3'-AMP and adenosine, and infusions of 2'-AMP and 3'-AMP increased urinary excretion of adenosine as efficiently as 5'-AMP. The implications are that 1) in intact organs, 2'-AMP and 3'-AMP are converted to adenosine as efficiently as 5'-AMP (previously considered the most important adenosine precursor) and 2) because 2',3'-cAMP opens mitochondrial permeability transition pores, a pro-apoptotic/pro-necrotic process, conversion of 2',3'-cAMP to adenosine by the extracellular 2',3'-cAMP-adenosine pathway would protect tissues by reducing a pro-death factor (2',3'-cAMP) while increasing a retaliatory metabolite (adenosine).
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Affiliation(s)
- Edwin K Jackson
- Departments of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15219, USA.
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Sasseville M, Albuz FK, Côté N, Guillemette C, Gilchrist RB, Richard FJ. Characterization of novel phosphodiesterases in the bovine ovarian follicle. Biol Reprod 2009; 81:415-25. [PMID: 19357367 DOI: 10.1095/biolreprod.108.074450] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The phosphodiesterase (PDE) family is a group of enzymes that catalyzes the transformation of cyclic nucleotides into 5' nucleotides. Based on rodents, the current mammalian model of PDE distribution in the ovarian follicle predicts Pde3a in the oocyte and Pde4d in the somatic cells. Using bovine as an experimental model, the present results showed that PDE3 was the predominant PDE activity in oocytes. However, cumulus cell cAMP-PDE activity was predominantly resistant to inhibition by 3-isobutyl-methylxantine, indicating PDE8 activity (60% of total PDE activity) and a minor role for PDE4 (<5%). A total of 20% of total oocyte PDE activity was also attributed to PDE8. The PDE activity measurements in mural granulosa cells from 2 to 6 mm in diameter suggest the presence of PDE4 and PDE8. In granulosa cells from follicles >10 mm, total PDE and PDE8 activities along with PDE8A protein level were increased compared with smaller follicles. The RT-PCR experiments showed that cumulus cells expressed PDE8A, PDE8B, and PDE10A. Western blot experiments showed PDE8A, PDE8B, and PDE4D proteins in mural granulosa cells and cumulus-oocyte complexes. PDE8 inhibition using dipyridamole in a dose-dependent manner increased cAMP levels in the cumulus-oocyte complexes and delayed oocyte nuclear maturation. These results are the first to demonstrate the functional presence of PDE8 in the mammalian ovarian follicle. This challenges the recently described cell-specific expression of cAMP-PDEs in the ovarian follicle and the notion that PDE4 is the predominant granulosa/cumulus cell PDE. These findings have implications for our understanding of hormonal regulation of folliculogenesis and the potential application of PDE inhibitors as novel contraceptives.
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Affiliation(s)
- Maxime Sasseville
- Département des Sciences Animales, Centre de Recherche en Biologie de la Reproduction, Université Laval, Sainte-Foy, Québec, Canada
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Rieg T, Vallon V. ATP and adenosine in the local regulation of water transport and homeostasis by the kidney. Am J Physiol Regul Integr Comp Physiol 2008; 296:R419-27. [PMID: 19020292 DOI: 10.1152/ajpregu.90784.2008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Regulation of body water homeostasis is critically dependent on the kidney and under the control of AVP, which is released from the neurohypophysis. In the collecting duct (CD) of the kidney, AVP activates adenylyl cyclase via vasopressin V2 receptors. cAMP-dependent activation of protein kinase A phosphorylates the water channel aquaporin-2 and increases water permeability by insertion of aquaporin-2 into the apical cell membrane. However, local factors modulate the effects of AVP to fine tune its effects, accelerate responses, and potentially protect the integrity of CD cells. Nucleotides like ATP belong to these local factors and act in an autocrine and paracrine way to activate P2Y2 receptors on CD cells. Extracellular breakdown of ATP and cAMP forms adenosine, the latter also induces specific effects on the CD by activation of adenosine A1 receptors. Activation of both receptor types can inhibit the cAMP-triggered activation of protein kinase A and reduce water permeability and transport. This review focuses on the role and potential interactions of the ATP and adenosine system with regard to the regulation of water transport in the CD. We address the potential stimuli and mechanisms involved in nucleotide release and adenosine formation, and discuss the corresponding signaling cascades that are activated. Potential interactions between the ATP and adenosine system, as well as other factors involved in the regulation of CD function, are outlined. Data from pharmacological studies and gene-targeted mouse models are presented to demonstrate the in vivo relevance to water transport and homeostasis.
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Affiliation(s)
- Timo Rieg
- Department of Medicine, Division of Nephrology and Hypertension, University of California San Diego, 3350 La Jolla Village Dr., La Jolla, CA 92161, USA.
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Pekkinen M, Ahlström MEB, Riehle U, Huttunen MM, Lamberg-Allardt CJE. Effects of phosphodiesterase 7 inhibition by RNA interference on the gene expression and differentiation of human mesenchymal stem cell-derived osteoblasts. Bone 2008; 43:84-91. [PMID: 18420479 DOI: 10.1016/j.bone.2008.02.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 02/23/2008] [Accepted: 02/26/2008] [Indexed: 12/25/2022]
Abstract
The second messenger molecule cyclic adenosine monophosphate (cAMP) plays an important role in the hormonal regulation of bone metabolism. cAMP is inactivated by the cyclic nucleotide phosphodiesterases (PDEs), a superfamily of enzymes divided into 11 known families designated PDE 1-11. The aim of this study was to investigate the effect of PDE7 and PDE8 inhibition on the gene expression and differentiation of human osteoblasts. Osteoblasts differentiated from human mesenchymal stem cells (hMSC) were cultured and treated with short interfering RNAs (siRNAs) generated from PDE7 and PDE8 PCR products. Total RNA was isolated from the cells, and gene expression was assayed with cDNA microarray and quantitative real-time PCR. bALP measurements were assayed during differentiation, and mineralization was determined by quantitative Alizarin red S staining. PDE7 and PDE8 inhibition by RNA interference decreased the gene expression of PDE7A by 60-70%, PDE7B by 40-50%, and PDE8A by 30%. PDE7 silencing increased the expression of beta-catenin, osteocalcin, caspase-8, and cAMP-responsive element-binding protein 5 (CREB-5) genes and decreased the expression of the 1, 25-dihydroxyvitamin D3 receptor gene. PDE8A silencing increased the expression of anti-apoptotic genes, but decreased the expression of osteoglycin (osteoinductive factor) and bone morphogenetic protein 1 (BMP-1). PDE7 silencing increased bALP and mineralization up to three-fold compared to controls. Treatment with the PDE7-selective PDE inhibitor BRL-50481 had similar effects on mineralization as the gene silencing. The PDE7 silencing also increased forskolin stimulated cAMP response, but had no effect on the proliferation rate. Furthermore, osteocalcin expression was increased by PDE7 silencing by a mechanism dependent on protein kinase A. Our results show that specific gene silencing with the RNAi method is a useful tool for inhibiting the gene expression of specific PDEs and that PDE7 silencing upregulates several osteogenic genes and increases mineralization. PDE7 may play an important role in the regulation of osteoblastic differentiation.
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Affiliation(s)
- Minna Pekkinen
- Calcium Research Unit, Department of Applied Chemistry and Microbiology, University of Helsinki, Finland.
| | - Mikael E B Ahlström
- Calcium Research Unit, Department of Applied Chemistry and Microbiology, University of Helsinki, Finland
| | - Ulrike Riehle
- Institution of Biological Chemistry and Nutrition, University of Hohenheim, Germany
| | - Minna M Huttunen
- Calcium Research Unit, Department of Applied Chemistry and Microbiology, University of Helsinki, Finland
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Jackson EK, Mi Z. Regulation of renal ectophosphodiesterase by protein kinase C and sodium diet. J Pharmacol Exp Ther 2008; 325:210-6. [PMID: 18223197 DOI: 10.1124/jpet.107.134445] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Kidneys metabolize arterial cAMP to adenosine by the sequential actions of ectophosphodiesterase (cAMP --> AMP) and ecto-5'-nucleotidase (AMP --> adenosine). In this study, we demonstrated that etheno-AMP (fluorescent AMP analog) is nearly completely converted to etheno-adenosine during a single pass through the isolated, perfused rat kidney indicating that ecto-5'-nucleotidase is not rate limiting. Therefore, we examined the regulation of ectophosphodiesterase. In 17 control kidneys pretreated with alpha,beta-methylene-adenosine-5'-diphosphate (inhibitor of ecto-5'-nucleotidase to prevent AMP metabolism; 100 microM), addition of cAMP (10 microM) to the perfusate increased renal venous AMP from 0.6 +/- 0.2 to 3.5 +/- 0.5 nmol/min/g. Pretreatment of kidneys with phorbol 12-myristate 13-acetate (protein kinase C activator; 7.5 nM) increased renal vascular resistance and significantly augmented the cAMP-induced increase in renal venous AMP (from 0.8 +/- 0.2 to 5.2 +/- 0.7 nmol/min/g with cAMP). Pretreatment of kidneys with bisindolymaleimide I (protein kinase C inhibitor; 3 microM) abrogated the effects of phorbol 12-myristate 13-acetate on both renovascular resistance and cAMP conversion to AMP. Compared with kidneys from rats fed a high-sodium diet (3.15%) for 1 week, in kidneys from rats fed a low-sodium diet (0.03%) the conversion of cAMP to AMP was attenuated (high sodium, from 1.0 +/- 0.1 to 4.6 +/- 0.4 nmol/min/g with cAMP; low sodium, from 0.5 +/- 0.04 to 2.6 +/- 0.04 nmol/min/g with cAMP). We conclude that the renal vasculature efficiently converts AMP to adenosine and that metabolism of cAMP to AMP is rate limiting and regulated acutely by protein kinase C and chronically by sodium intake.
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Affiliation(s)
- Edwin K Jackson
- Center for Clinical Pharmacology, University of Pittsburgh School of Medicine, 100 Technology Drive, Suite 450, Pittsburgh, PA 15219, USA. edj+@pitt.edu
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21
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Abstract
BACKGROUND AND PURPOSE cAMP is a key intracellular signalling molecule that regulates multiple processes of the vertebrate skeletal muscle. We have shown that cAMP can be actively pumped out from the skeletal muscle cell. Since in other tissues, cAMP efflux had been associated with extracellular generation of adenosine, in the present study we have assessed the fate of interstitial cAMP and the existence of an extracellular cAMP-adenosine signalling pathway in skeletal muscle. EXPERIMENTAL APPROACH cAMP efflux and/or its extracellular degradation were analysed by incubating rat cultured skeletal muscle with exogenous cAMP, forskolin or isoprenaline. cAMP and its metabolites were quantified by radioassay or HPLC, respectively. KEY RESULTS Incubation of cells with exogenous cAMP was followed by interstitial accumulation of 5'-AMP and adenosine, a phenomenon inhibited by selective inhibitors of ecto-phosphodiesterase (DPSPX) and ecto-nucleotidase (AMPCP). Activation of adenylyl cyclase (AC) in cultured cells with forskolin or isoprenaline increased cAMP efflux and extracellular generation of 5'-AMP and adenosine. Extracellular cAMP-adenosine pathway was also observed after direct and receptor-dependent stimulation of AC in rat extensor muscle ex vivo. These events were attenuated by probenecid, an inhibitor of ATP binding cassette family transporters. CONCLUSIONS AND IMPLICATIONS Our results show the existence of an extracellular biochemical cascade that converts cAMP into adenosine. The functional relevance of this extracellular signalling system may involve a feedback modulation of cellular response initiated by several G protein-coupled receptor ligands, amplifying cAMP influence to a paracrine mode, through its metabolite, adenosine.
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