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Taoro-González L, Cabrera-Pastor A, Sancho-Alonso M, Felipo V. Intracellular and extracelluar cyclic GMP in the brain and the hippocampus. VITAMINS AND HORMONES 2022; 118:247-288. [PMID: 35180929 DOI: 10.1016/bs.vh.2021.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cyclic Guanosine-Monophosphate (cGMP) is implicated as second messenger in a plethora of pathways and its effects are executed mainly by cGMP-dependent protein kinases (PKG). It is involved in both peripheral (cardiovascular regulation, intestinal secretion, phototransduction, etc.) and brain (hippocampal synaptic plasticity, neuroinflammation, cognitive function, etc.) processes. Stimulation of hippocampal cGMP signaling have been proved to be beneficial in animal models of aging, Alzheimer's disease or hepatic encephalopathy, restoring different cognitive functions such as passive avoidance, object recognition or spatial memory. However, even when some inhibitors of cGMP-degrading enzymes (PDEs) are already used against peripheral pathologies, their utility as neurological treatments is still under clinical investigation. Additionally, it has been demonstrated a list of cGMP roles as not second but first messenger. The role of extracellular cGMP has been specially studied in hippocampal function and cognitive impairment in animal models and it has emerged as an important modulator of neuroinflammation-mediated cognitive alterations and hippocampal synaptic plasticity malfunction. Specifically, it has been demonstrated that extracellular cGMP decreases hippocampal IL-1β levels restoring membrane expression of glutamate receptors in the hippocampus and cognitive function in hyperammonemic rats. The mechanisms implicated are still unclear and might involve complex interactions between hippocampal neurons, astrocytes and microglia. Membrane targets for extracellular cGMP are still poorly understood and must be addressed in future studies.
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Affiliation(s)
- Lucas Taoro-González
- Department of Clinical Psychology, Psychobiology and Methodology, Area of Psycobiology, University of La Laguna, Tenerife, Spain
| | - Andrea Cabrera-Pastor
- Fundación Investigación Hospital Clínico, Instituto de Investigación Sanitaria (INCLIVA), Valencia, Spain; Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - María Sancho-Alonso
- Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Vicente Felipo
- Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, Valencia, Spain.
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Antiviral Drug Ivermectin at Nanomolar Concentrations Inhibits Glycine-Induced Chloride Current in Rat Hippocampal Neurons. Bull Exp Biol Med 2021; 170:649-653. [PMID: 33788116 PMCID: PMC8011064 DOI: 10.1007/s10517-021-05125-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Indexed: 11/21/2022]
Abstract
Ivermectin (IVM) belongs to the class of macrocyclic lactones, which is used as an antiparasitic agent. At present, the researchers focus on possibility to use IVM in treatment of certain forms of cancer and viral diseases such as COVID-19. The mechanisms of IVM action are not clear. It is assumed that IVM affects chloride channels and increases cytoplasmic concentration of chloride. This study examines the effect of IVM on chloride currents induced by glycine (IGly). Experiments were carried out on isolated pyramidal neurons of the rat hippocampus with whole-cell patch clamp. A short-term (600 msec) application of IVM in a concentration of 10 μM induced a slow inward current, which persisted after washing the neurons. The low concentrations (0.1-1000 nM) of IVM did not induce any novel current, but it rapidly and reversibly reduced the peak amplitude and accelerated desensitization of IGly in a dose-dependent manner. The threshold concentrations of IVM sufficient to reduce peak amplitude of IGly and to accelerate desensitization of IGly were 100 nM and 0.1 nM, respectively. The study revealed a high sensitivity of neuronal glycine receptors to IVM.
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Arenas YM, Cabrera-Pastor A, Juciute N, Mora-Navarro E, Felipo V. Blocking glycine receptors reduces neuroinflammation and restores neurotransmission in cerebellum through ADAM17-TNFR1-NF-κβ pathway. J Neuroinflammation 2020; 17:269. [PMID: 32917219 PMCID: PMC7488331 DOI: 10.1186/s12974-020-01941-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 08/24/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Chronic hyperammonemia induces neuroinflammation in cerebellum, with glial activation and enhanced activation of the TNFR1-NF-kB-glutaminase-glutamate-GABA pathway. Hyperammonemia also increases glycinergic neurotransmission. These alterations contribute to cognitive and motor impairment. Activation of glycine receptors is reduced by extracellular cGMP, which levels are reduced in cerebellum of hyperammonemic rats in vivo. We hypothesized that enhanced glycinergic neurotransmission in hyperammonemic rats (1) contributes to induce neuroinflammation and glutamatergic and GABAergic neurotransmission alterations; (2) is a consequence of the reduced extracellular cGMP levels. The aims were to assess, in cerebellum of hyperammonemic rats, (a) whether blocking glycine receptors with the antagonist strychnine reduces neuroinflammation; (b) the cellular localization of glycine receptor; (c) the effects of blocking glycine receptors on the TNFR1-NF-kB-glutaminase-glutamate-GABA pathway and microglia activation; (d) whether adding extracellular cGMP reproduces the effects of strychnine. METHODS We analyzed in freshly isolated cerebellar slices from control or hyperammonemic rats the effects of strychnine on activation of microglia and astrocytes, the content of TNFa and IL1b, the surface expression of ADAM17, TNFR1 and transporters, the phosphorylation levels of ERK, p38 and ADAM17. The cellular localization of glycine receptor was assessed by immunofluorescence. We analyzed the content of TNFa, IL1b, HMGB1, glutaminase, and the level of TNF-a mRNA and NF-κB in Purkinje neurons. Extracellular concentrations of glutamate and GABA were performed by in vivo microdialysis in cerebellum. We tested whether extracellular cGMP reproduces the effects of strychnine in ex vivo cerebellar slices. RESULTS Glycine receptors are expressed mainly in Purkinje cells. In hyperammonemic rats, enhanced glycinergic neurotransmission leads to reduced membrane expression of ADAM17, resulting in increased surface expression and activation of TNFR1 and of the associated NF-kB pathway. This increases the expression in Purkinje neurons of TNFa, IL-1b, HMGB1, and glutaminase. Increased glutaminase activity leads to increased extracellular glutamate, which increases extracellular GABA. Increased extracellular glutamate and HMGB1 potentiate microglial activation. Blocking glycine receptors with strychnine or extracellular cGMP completely prevents the above pathway in hyperammonemic rats. CONCLUSIONS Glycinergic neurotransmission modulates neuroinflammation. Enhanced glycinergic neurotransmission in hyperammonemia would be due to reduced extracellular cGMP. These results shed some light on possible new therapeutic target pathways for pathologies associated to neuroinflammation.
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Affiliation(s)
- Yaiza M Arenas
- Laboratory of Neurobiology, Príncipe Felipe Research Center Valencia, C/Eduardo Primo Yúfera 3, 46012, Valencia, Spain
| | - Andrea Cabrera-Pastor
- Laboratory of Neurobiology, Príncipe Felipe Research Center Valencia, C/Eduardo Primo Yúfera 3, 46012, Valencia, Spain.
- Laboratory of Neurological Impairment, Health Research Institute INCLIVA, 46010, Valencia, Spain.
| | - Nora Juciute
- Laboratory of Neurobiology, Príncipe Felipe Research Center Valencia, C/Eduardo Primo Yúfera 3, 46012, Valencia, Spain
| | - Eloy Mora-Navarro
- Laboratory of Neurobiology, Príncipe Felipe Research Center Valencia, C/Eduardo Primo Yúfera 3, 46012, Valencia, Spain
| | - Vicente Felipo
- Laboratory of Neurobiology, Príncipe Felipe Research Center Valencia, C/Eduardo Primo Yúfera 3, 46012, Valencia, Spain
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Cabrera-Pastor A, Arenas YM, Taoro-Gonzalez L, Montoliu C, Felipo V. Chronic hyperammonemia alters extracellular glutamate, glutamine and GABA and membrane expression of their transporters in rat cerebellum. Modulation by extracellular cGMP. Neuropharmacology 2019; 161:107496. [PMID: 30641078 DOI: 10.1016/j.neuropharm.2019.01.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 12/15/2018] [Accepted: 01/10/2019] [Indexed: 12/14/2022]
Abstract
Trafficking of glutamate, glutamine and GABA between astrocytes and neurons is essential to maintain proper neurotransmission. Chronic hyperammonemia alters neurotransmission and cognitive function. The aims of this work were to analyze in cerebellum of rats the effects of chronic hyperammonemia on: a) extracellular glutamate, glutamine and GABA concentrations; b) membrane expression of glutamate, glutamine and GABA transporters; c) how they are modulated by extracellular cGMP. Hyperammonemic rats show increased levels of extracellular glutamate, glutamine, GABA and citrulline in cerebellum in vivo. Hyperammonemic rats show: a) increased membrane expression of the astrocytic glutamine transporter SNAT3 and reduced membrane expression of the neuronal transporter SNAT1; b) reduced membrane expression of the neuronal GABA transporter GAT1 and increased membrane expression of the astrocytic GAT3 transporter; c) reduced membrane expression of the astrocytic glutamate transporters GLAST and GLT-1 and of the neuronal transporter EAAC1. Increasing extracellular cGMP normalizes membrane expression of SNAT3, GAT3, GAT1 and GLAST and extracellular glutamate, glutamine, GABA and citrulline hyperammonemic rats. Extracellular cGMP also modulates membrane expression of most transporters in control rats, reducing membrane expression of SNAT1, GLT-1 and EAAC1 and increasing that of GAT1 and GAT3. Modulation of SNAT3, SNAT1, GLT-1 and EAAC1 by extracellular cGMP would be mediated by inhibition of glycine receptors. These data suggest that, in pathological situations such as hyperammonemia, hepatic encephalopathy or Alzheimer's disease, reduced levels of extracellular cGMP contribute to alterations in membrane expression of glutamine, glutamate and GABA transporters, in the extracellular levels of glutamine, glutamate and GABA and in neurotransmission. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- Andrea Cabrera-Pastor
- Laboratory of Neurobiology, Centro de Investigación Principe Felipe, Valencia, Spain; Fundacion Investigacion Hospital Clinico Valencia, Instituto de Investigacion Sanitaria INCLIVA, Valencia, Spain
| | - Yaiza M Arenas
- Laboratory of Neurobiology, Centro de Investigación Principe Felipe, Valencia, Spain
| | - Lucas Taoro-Gonzalez
- Laboratory of Neurobiology, Centro de Investigación Principe Felipe, Valencia, Spain
| | - Carmina Montoliu
- Fundacion Investigacion Hospital Clinico Valencia, Instituto de Investigacion Sanitaria INCLIVA, Valencia, Spain
| | - Vicente Felipo
- Laboratory of Neurobiology, Centro de Investigación Principe Felipe, Valencia, Spain.
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Bukanova JV, Solntseva EI, Kolbaev SN, Kudova E. Modulation of GABA and glycine receptors in rat pyramidal hippocampal neurones by 3α5β-pregnanolone derivatives. Neurochem Int 2018; 118:145-151. [PMID: 29886074 DOI: 10.1016/j.neuint.2018.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 05/25/2018] [Accepted: 06/06/2018] [Indexed: 12/28/2022]
Abstract
The ability of pregnanolone glutamate (PA-Glu), pregnanolone hemisuccinate (PA-hSuc) and pregnanolone hemipimelate (PA-hPim), neuroactive steroids with a negative modulatory effect on excitatory N-methyl-d-aspartate receptors, to influence the functional activity of inhibitory γ-aminobutyric acid and glycine receptors was estimated. The GABA- and glycine-induced chloride currents (IGABA and IGly) were measured in isolated pyramidal neurons of the rat hippocampus using the patch-clamp technique. Compound PA-Glu was found to potentiate IGABA and to inhibit IGly, while PA-hSuc and PA-hPim inhibited both IGABA and IGly. Moreover, PA-Glu, PA-hSuc, and PA-hPim had a greater effect on desensitization than on the peak amplitude of IGly. At a high concentration of glycine (500 μM), the effect of neurosteroids on the peak amplitude of IGly disappeared, and the acceleration of desensitization remained. The conversion of PA-Glu into androstane glutamate (AND-Glu), an analogue that lacks the C-17 acetyl moiety, completely eliminated the effects on these receptors. Our results indicate that the C-17 acetyl moiety is crucial for the action on IGABA and IGly. Our results indicate that the pregnanolone derivatives, in contrast to the androstane analogues, modulate IGABA and IGly at low micromolar concentrations and this family of neurosteroids can be useful for future structure-activity relationship studies of the steroid modulation of other receptor types.
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Affiliation(s)
| | | | | | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic.
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Cabrera-Pastor A, Balzano T, Hernández-Rabaza V, Malaguarnera M, Llansola M, Felipo V. Increasing extracellular cGMP in cerebellum in vivo reduces neuroinflammation, GABAergic tone and motor in-coordination in hyperammonemic rats. Brain Behav Immun 2018; 69:386-398. [PMID: 29288802 DOI: 10.1016/j.bbi.2017.12.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 12/21/2017] [Accepted: 12/26/2017] [Indexed: 11/28/2022] Open
Abstract
Hyperammonemia is a main contributor to cognitive impairment and motor in-coordination in patients with hepatic encephalopathy. Hyperammonemia-induced neuroinflammation mediates the neurological alterations in hepatic encephalopathy. Intracerebral administration of extracellular cGMP restores some but not all types of cognitive impairment. Motor in-coordination, is mainly due to increased GABAergic tone in cerebellum. We hypothesized that extracellular cGMP would restore motor coordination in hyperammonemic rats by normalizing GABAergic tone in cerebellum and that this would be mediated by reduction of neuroinflammation. The aims of this work were to assess whether chronic intracerebral administration of cGMP to hyperammonemic rats: 1) restores motor coordination; 2) reduces neuroinflammation in cerebellum; 3) reduces extracellular GABA levels and GABAergic tone in cerebellum; and also 4) to provide some advance in the understanding on the molecular mechanisms involved. The results reported show that rats with chronic hyperammonemia show neuroinflammation in cerebellum, including microglia and astrocytes activation and increased levels of IL-1b and TNFa and increased membrane expression of the TNFa receptor. This is associated with increased glutaminase expression and extracellular glutamate, increased amount of the GABA transporter GAT-3 in activated astrocytes, increased extracellular GABA in cerebellum and motor in-coordination. Chronic intracerebral administration of extracellular cGMP to rats with chronic hyperammonemia reduces neuroinflammation, including microglia and astrocytes activation and membrane expression of the TNFa receptor. This is associated with reduced nuclear NF-κB, glutaminase expression and extracellular glutamate, reduced amount of the GABA transporter GAT-3 in activated astrocytes and reduced extracellular GABA in cerebellum and restoration of motor coordination. The data support that extracellular cGMP restores motor coordination in hyperammonemic rats by reducing microglia activation and neuroinflammation, leading to normalization of extracellular glutamate and GABA levels in cerebellum and of motor coordination.
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Affiliation(s)
- Andrea Cabrera-Pastor
- Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe de Valencia, Spain
| | - Tiziano Balzano
- Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe de Valencia, Spain
| | | | - Michele Malaguarnera
- Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe de Valencia, Spain
| | - Marta Llansola
- Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe de Valencia, Spain
| | - Vicente Felipo
- Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe de Valencia, Spain.
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Extracellular Cyclic GMP Modulates Membrane Expression of The GluA1 and GluA2 Subunits of AMPA Receptor in Cerebellum: Molecular Mechanisms Involved. Sci Rep 2017; 7:17656. [PMID: 29247190 PMCID: PMC5732250 DOI: 10.1038/s41598-017-18024-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 12/05/2017] [Indexed: 02/06/2023] Open
Abstract
There is increasing evidence that extracellular cGMP modulates glutamatergic neurotransmission and some forms of learning. However, the underlying mechanisms remain unknown. We proposed the hypotheses that extracellular cGMP may regulate membrane expression of AMPA receptors. To do this extracellular cGMP should act on a membrane protein and activate signal transduction pathways modulating phosphorylation of the GluA1 and/or GluA2 subunits. It has been shown that extracellular cGMP modulates glycine receptors. The aims of this work were to assess: 1) whether extracellular cGMP modulates membrane expression of GluA1 and GluA2 subunits of AMPA receptors in cerebellum in vivo; 2) whether this is mediated by glycine receptors; 3) the role of GluA1 and GluA2 phosphorylation and 4) identify steps of the intracellular pathways involved. We show that extracellular cGMP modulates membrane expression of GluA1 and GluA2 in cerebellum in vivo and unveil the mechanisms involved. Extracellular cGMP reduced glycine receptor activation, modulating cAMP, protein kinases and phosphatases, and GluA1 and GluA2 phosphorylation, resulting in increased GluA1 and reduced GluA2 membrane expression. Extracellular cGMP therefore modulates membrane expression of AMPA receptors and glutamatergic neurotransmission. The steps identified may be therapeutic targets to improve neurotransmission and neurological function in pathological situations with abnormal glutamatergic neurotransmission.
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Cabrera-Pastor A, Malaguarnera M, Taoro-Gonzalez L, Llansola M, Felipo V. Extracellular cGMP Modulates Learning Biphasically by Modulating Glycine Receptors, CaMKII and Glutamate-Nitric Oxide-cGMP Pathway. Sci Rep 2016; 6:33124. [PMID: 27634333 PMCID: PMC5025658 DOI: 10.1038/srep33124] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 08/22/2016] [Indexed: 01/06/2023] Open
Abstract
It has been proposed that extracellular cGMP modulates the ability to learn a Y maze task, but the underlying mechanisms remained unknown. Here we show that extracellular cGMP, at physiological concentrations, modulates learning in the Y maze in a biphasic way by modulating the glutamate-nitric oxide-cGMP pathway in cerebellum. Extracellular cGMP reduces glycine receptors activation inducing a voltage-dependent calcium-channels-mediated increase of calcium in Purkinje neurons. This calcium increase modulates CaMKII phosphorylation in a biphasic way. When basal calcium concentration is low extracellular cGMP reduces CaMKII phosphorylation, increasing nitric oxide synthase activity, the glutamate-NO-cGMP pathway function and learning ability. When basal calcium is normal extracellular cGMP increases CaMKII phosphorylation, reducing nitric oxide synthase activity, the pathway function and learning. These data unveil new mechanisms modulating learning in the Y maze and likely other learning types which may be therapeutic targets to improve learning in pathological situations associated with altered cGMP levels.
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Affiliation(s)
- Andrea Cabrera-Pastor
- Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe de Valencia, Spain
| | - Michele Malaguarnera
- Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe de Valencia, Spain
| | - Lucas Taoro-Gonzalez
- Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe de Valencia, Spain
| | - Marta Llansola
- Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe de Valencia, Spain
| | - Vicente Felipo
- Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe de Valencia, Spain
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Lithium ions in nanomolar concentration modulate glycine-activated chloride current in rat hippocampal neurons. Neurochem Int 2016; 94:67-73. [DOI: 10.1016/j.neuint.2016.02.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 02/05/2016] [Accepted: 02/09/2016] [Indexed: 11/17/2022]
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Schneider E, Wolter S, Dittmar F, Fernández G, Seifert R. Differentiation between first and second messenger effects of cGMP. BMC Pharmacol Toxicol 2015. [PMCID: PMC4565094 DOI: 10.1186/2050-6511-16-s1-a84] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Fe2+ and Fe3+ in micromolar concentrations modulate glycine-induced Cl− current in rat hippocampal neurons. Brain Res Bull 2015; 115:9-16. [DOI: 10.1016/j.brainresbull.2015.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 04/06/2015] [Accepted: 04/07/2015] [Indexed: 11/22/2022]
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Seifert R, Schneider EH, Bähre H. From canonical to non-canonical cyclic nucleotides as second messengers: pharmacological implications. Pharmacol Ther 2014; 148:154-84. [PMID: 25527911 DOI: 10.1016/j.pharmthera.2014.12.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 12/11/2014] [Indexed: 02/07/2023]
Abstract
This review summarizes our knowledge on the non-canonical cyclic nucleotides cCMP, cUMP, cIMP, cXMP and cTMP. We place the field into a historic context and discuss unresolved questions and future directions of research. We discuss the implications of non-canonical cyclic nucleotides for experimental and clinical pharmacology, focusing on bacterial infections, cardiovascular and neuropsychiatric disorders and reproduction medicine. The canonical cyclic purine nucleotides cAMP and cGMP fulfill the criteria of second messengers. (i) cAMP and cGMP are synthesized by specific generators, i.e. adenylyl and guanylyl cyclases, respectively. (ii) cAMP and cGMP activate specific effector proteins, e.g. protein kinases. (iii) cAMP and cGMP exert specific biological effects. (iv) The biological effects of cAMP and cGMP are terminated by phosphodiesterases and export. The effects of cAMP and cGMP are mimicked by (v) membrane-permeable cyclic nucleotide analogs and (vi) bacterial toxins. For decades, the existence and relevance of cCMP and cUMP have been controversial. Modern mass-spectrometric methods have unequivocally demonstrated the existence of cCMP and cUMP in mammalian cells. For both, cCMP and cUMP, the criteria for second messenger molecules are now fulfilled as well. There are specific patterns by which nucleotidyl cyclases generate cNMPs and how they are degraded and exported, resulting in unique cNMP signatures in biological systems. cNMP signaling systems, specifically at the level of soluble guanylyl cyclase, soluble adenylyl cyclase and ExoY from Pseudomonas aeruginosa are more promiscuous than previously appreciated. cUMP and cCMP are evolutionary new molecules, probably reflecting an adaption to signaling requirements in higher organisms.
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Affiliation(s)
- Roland Seifert
- Institute of Pharmacology, Hannover Medical School, D-30625 Hannover, Germany.
| | - Erich H Schneider
- Institute of Pharmacology, Hannover Medical School, D-30625 Hannover, Germany
| | - Heike Bähre
- Institute of Pharmacology, Hannover Medical School, D-30625 Hannover, Germany
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