1
|
Trubacova R, Drastichova Z, Novotny J. Biochemical and physiological insights into TRH receptor-mediated signaling. Front Cell Dev Biol 2022; 10:981452. [PMID: 36147745 PMCID: PMC9485831 DOI: 10.3389/fcell.2022.981452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/16/2022] [Indexed: 11/13/2022] Open
Abstract
Thyrotropin-releasing hormone (TRH) is an important endocrine agent that regulates the function of cells in the anterior pituitary and the central and peripheral nervous systems. By controlling the synthesis and release of thyroid hormones, TRH affects many physiological functions, including energy homeostasis. This hormone exerts its effects through G protein-coupled TRH receptors, which signal primarily through Gq/11 but may also utilize other G protein classes under certain conditions. Because of the potential therapeutic benefit, considerable attention has been devoted to the synthesis of new TRH analogs that may have some advantageous properties compared with TRH. In this context, it may be interesting to consider the phenomenon of biased agonism and signaling at the TRH receptor. This possibility is supported by some recent findings. Although knowledge about the mechanisms of TRH receptor-mediated signaling has increased steadily over the past decades, there are still many unanswered questions, particularly about the molecular details of post-receptor signaling. In this review, we summarize what has been learned to date about TRH receptor-mediated signaling, including some previously undiscussed information, and point to future directions in TRH research that may offer new insights into the molecular mechanisms of TRH receptor-triggered actions and possible ways to modulate TRH receptor-mediated signaling.
Collapse
|
2
|
Moravcova R, Melkes B, Novotny J. TRH receptor mobility in the plasma membrane is strongly affected by agonist binding and by interaction with some cognate signaling proteins. J Recept Signal Transduct Res 2017; 38:20-26. [PMID: 29137494 DOI: 10.1080/10799893.2017.1398756] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVES Extensive research has been dedicated to elucidating the mechanisms of signal transduction through different G protein-coupled receptors (GPCRs). However, relatively little is known about the regulation of receptor movement within the cell membrane upon ligand binding. In this study we focused our attention on the thyrotropin-releasing hormone (TRH) receptor that typically couples to Gq/11 proteins. METHODS We monitored receptor diffusion in the plasma membrane of HEK293 cells stably expressing yellow fluorescent protein (YFP)-tagged TRH receptor (TRHR-YFP) by fluorescence recovery after photobleaching (FRAP). RESULTS FRAP analysis indicated that the lateral movement of the TRH receptor was markedly reduced upon TRH binding as the value of its diffusion coefficient fell down by 55%. This effect was prevented by the addition of the TRH receptor antagonist midazolam. We also found that siRNA-mediated knockdown of Gq/11α, Gβ, β-arrestin2 and phospholipase Cβ1, but not of Giα1, β-arrestin1 or G protein-coupled receptor kinase 2, resulted in a significant decrease in the rate of TRHR-YFP diffusion, indicating the involvement of the former proteins in the regulation of TRH receptor behavior. The observed partial reduction of the TRHR-YFP mobile fraction caused by down-regulation of Giα1 and β-arrestin1 suggests that these proteins may also play distinct roles in THR receptor-mediated signaling. CONCLUSION These results demonstrate for the first time that not only agonist binding but also abundance of some signaling proteins may strongly affect TRH receptor dynamics in the plasma membrane.
Collapse
Affiliation(s)
- Radka Moravcova
- a Department of Physiology, Faculty of Science , Charles University , Prague , Czech Republic
| | - Barbora Melkes
- a Department of Physiology, Faculty of Science , Charles University , Prague , Czech Republic
| | - Jiri Novotny
- a Department of Physiology, Faculty of Science , Charles University , Prague , Czech Republic
| |
Collapse
|
3
|
Ujcikova H, Hlouskova M, Cechova K, Stolarova K, Roubalova L, Svoboda P. Determination of μ-, δ- and κ-opioid receptors in forebrain cortex of rats exposed to morphine for 10 days: Comparison with animals after 20 days of morphine withdrawal. PLoS One 2017; 12:e0186797. [PMID: 29053731 PMCID: PMC5650167 DOI: 10.1371/journal.pone.0186797] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 10/06/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Chronic exposure of mammalian organism to morphine results in adaption to persistent high opioid tone through homeostatic adjustments. Our previous results indicated that in the frontal brain cortex (FBC) of rats exposed to morphine for 10 days, such a compensatory adjustment was detected as large up-regulation of adenylylcyclases I (8-fold) and II (2.5-fold). The other isoforms of AC (III-IX) were unchanged. Importantly, the increase of ACI and ACII was reversible as it disappeared after 20 days of morphine withdrawal. Changes of down-stream signaling molecules such as G proteins and adenylylcyclases should respond to and be preceded by primary changes proceeding at receptor level. Therefore in our present work, we addressed the problem of reversibility of the long-term morphine effects on μ-, δ- and κ-OR protein levels in FBC. METHODS Rats were exposed to increasing doses of morphine (10-40 mg/kg) for 10 days and sacrificed either 24 h (group +M10) or 20 days (group +M10/-M20) after the last dose of morphine in parallel with control animals (groups -M10 and -M10/-M20). Post-nuclear supernatant (PNS) fraction was prepared from forebrain cortex, resolved by 1D-SDS-PAGE under non-dissociated (-DTT) and dissociated (+DTT) conditions, and analyzed for the content of μ-, δ- and κ-OR by immunoblotting with C- and N-terminus oriented antibodies. RESULTS Significant down-regulation of δ-OR form exhibiting Mw ≈ 60 kDa was detected in PNS prepared from both (+M10) and (+M10/-M20) rats. However, the total immunoblot signals of μ-, δ- and κ-OR, respectively, were unchanged. Plasma membrane marker Na, K-ATPase, actin and GAPDH were unaffected by morphine in both types of PNS. Membrane-domain marker caveolin-1 and cholesterol level increased in (+M10) rats and this increase was reversed back to control level in (+M10/-M20) rats. CONCLUSIONS In FBC, prolonged exposure of rats to morphine results in minor (δ-OR) or no change (μ- and κ-OR) of opioid receptor content. The reversible increases of caveolin-1 and cholesterol levels suggest participation of membrane domains in compensatory responses during opioid withdrawal. GENERAL SIGNIFICANCE Analysis of reversibility of morphine effect on mammalian brain.
Collapse
MESH Headings
- Animals
- Blotting, Western
- Electrophoresis, Gel, Two-Dimensional
- Electrophoresis, Polyacrylamide Gel
- Male
- Morphine/administration & dosage
- Morphine/adverse effects
- Prosencephalon/metabolism
- Rats
- Rats, Wistar
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/metabolism
- Substance Withdrawal Syndrome
Collapse
Affiliation(s)
- Hana Ujcikova
- Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Martina Hlouskova
- Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Kristina Cechova
- Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Katerina Stolarova
- Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lenka Roubalova
- Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Petr Svoboda
- Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| |
Collapse
|
4
|
Brejchova J, Vosahlikova M, Roubalova L, Parenti M, Mauri M, Chernyavskiy O, Svoboda P. Plasma membrane cholesterol level and agonist-induced internalization of δ-opioid receptors; colocalization study with intracellular membrane markers of Rab family. J Bioenerg Biomembr 2016; 48:375-96. [DOI: 10.1007/s10863-016-9667-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 06/02/2016] [Indexed: 10/21/2022]
|
5
|
Brejchová J, Sýkora J, Ostašov P, Merta L, Roubalová L, Janáček J, Hof M, Svoboda P. TRH-receptor mobility and function in intact and cholesterol-depleted plasma membrane of HEK293 cells stably expressing TRH-R-eGFP. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:781-96. [DOI: 10.1016/j.bbamem.2014.11.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 11/24/2014] [Accepted: 11/26/2014] [Indexed: 01/03/2023]
|
6
|
Xie AX, Lauderdale K, Murphy T, Myers TL, Fiacco TA. Inducing plasticity of astrocytic receptors by manipulation of neuronal firing rates. J Vis Exp 2014. [PMID: 24686723 PMCID: PMC4155624 DOI: 10.3791/51458] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Close to two decades of research has established that astrocytes in situ and in vivo express numerous G protein-coupled receptors (GPCRs) that can be stimulated by neuronally-released transmitter. However, the ability of astrocytic receptors to exhibit plasticity in response to changes in neuronal activity has received little attention. Here we describe a model system that can be used to globally scale up or down astrocytic group I metabotropic glutamate receptors (mGluRs) in acute brain slices. Included are methods on how to prepare parasagittal hippocampal slices, construct chambers suitable for long-term slice incubation, bidirectionally manipulate neuronal action potential frequency, load astrocytes and astrocyte processes with fluorescent Ca(2+) indicator, and measure changes in astrocytic Gq GPCR activity by recording spontaneous and evoked astrocyte Ca(2+) events using confocal microscopy. In essence, a "calcium roadmap" is provided for how to measure plasticity of astrocytic Gq GPCRs. Applications of the technique for study of astrocytes are discussed. Having an understanding of how astrocytic receptor signaling is affected by changes in neuronal activity has important implications for both normal synaptic function as well as processes underlying neurological disorders and neurodegenerative disease.
Collapse
Affiliation(s)
- Alison X Xie
- Graduate Program in Neuroscience, University of California Riverside
| | - Kelli Lauderdale
- Graduate Program in Neuroscience, University of California Riverside
| | - Thomas Murphy
- Graduate Program in Neuroscience, University of California Riverside
| | - Timothy L Myers
- Graduate Program in Neuroscience, University of California Riverside
| | - Todd A Fiacco
- Department of Cell Biology and Neuroscience, University of California Riverside; Center for Glial-Neuronal Interactions, University of California Riverside;
| |
Collapse
|
7
|
UJČÍKOVÁ H, BREJCHOVÁ J, VOŠAHLÍKOVÁ M, KAGAN D, DLOUHÁ K, SÝKORA J, MERTA L, DRASTICHOVÁ Z, NOVOTNÝ J, OSTAŠOV P, ROUBALOVÁ L, PARENTI M, HOF M, SVOBODA P. Opioid-Receptor (OR) Signaling Cascades in Rat Cerebral Cortex and Model Cell Lines: the Role of Plasma Membrane Structure. Physiol Res 2014; 63:S165-76. [DOI: 10.33549/physiolres.932638] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Large number of extracellular signals is received by plasma membrane receptors which, upon activation, transduce information into the target cell interior via trimeric G-proteins (GPCRs) and induce activation or inhibition of adenylyl cyclase enzyme activity (AC). Receptors for opioid drugs such as morphine (μ-OR, δ-OR and κ-OR) belong to rhodopsin family of GPCRs. Our recent results indicated a specific up-regulation of AC I (8-fold) and AC II (2.5-fold) in plasma membranes (PM) isolated from rat brain cortex exposed to increasing doses of morphine (10-50 mg/kg) for 10 days. Increase of ACI and ACII represented the specific effect as the amount of ACIII-ACIX, prototypical PM marker Na, K-ATPase and trimeric G-protein α and β subunits was unchanged. The up-regulation of ACI and ACII faded away after 20 days since the last dose of morphine. Proteomic analysis of these PM indicated that the brain cortex of morphine-treated animals cannot be regarded as being adapted to this drug because significant up-regulation of proteins functionally related to oxidative stress and alteration of brain energy metabolism occurred. The number of δ-OR was increased 2-fold and their sensitivity to monovalent cations was altered. Characterization of δ-OR-G-protein coupling in model HEK293 cell line indicated high ability of lithium to support affinity of δ-OR response to agonist stimulation. Our studies of PM structure and function in context with desensitization of GPCRs action were extended by data indicating participation of cholesterol-enriched membrane domains in agonist-specific internalization of δ-OR. In HEK293 cells stably expressing δ-OR-Gi1α fusion protein, depletion of PM cholesterol was associated with the decrease in affinity of G-protein response to agonist stimulation, whereas maximum response was unchanged. Hydrophobic interior of isolated PM became more “fluid”, chaotically organized and accessible to water molecules. Validity of this conclusion was supported by the analysis of an immediate PM environment of cholesterol molecules in living δ-OR-Gi1α-HEK293 cells by fluorescent probes 22- and 25-NBD-cholesterol. The alteration of plasma membrane structure by cholesterol depletion made the membrane more hydrated. Understanding of the positive and negative feedback regulatory loops among different OR-initiated signaling cascades (µ-, δ-, and κ-OR) is crucial for understanding of the long-term mechanisms of drug addiction as the decrease in functional activity of µ-OR may be compensated by increase of δ-OR and/or κ-OR signaling.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - P. SVOBODA
- Department of Biochemistry of Membrane Receptors, Institute of Physiology Academy of Sciences of the Czech Republic
| |
Collapse
|
8
|
Xie AX, Sun MY, Murphy T, Lauderdale K, Tiglao E, Fiacco TA. Bidirectional scaling of astrocytic metabotropic glutamate receptor signaling following long-term changes in neuronal firing rates. PLoS One 2012; 7:e49637. [PMID: 23166735 PMCID: PMC3499417 DOI: 10.1371/journal.pone.0049637] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 10/16/2012] [Indexed: 11/19/2022] Open
Abstract
Very little is known about the ability of astrocytic receptors to exhibit plasticity as a result of changes in neuronal activity. Here we provide evidence for bidirectional scaling of astrocytic group I metabotropic glutamate receptor signaling in acute mouse hippocampal slices following long-term changes in neuronal firing rates. Plasticity of astrocytic mGluRs was measured by recording spontaneous and evoked Ca2+ elevations in both astrocytic somata and processes. An exogenous astrocytic Gq G protein-coupled receptor was resistant to scaling, suggesting that the alterations in astrocyte Ca2+ signaling result from changes in activity of the surface mGluRs rather than a change in intracellular G protein signaling molecules. These findings suggest that astrocytes actively detect shifts in neuronal firing rates and adjust their receptor signaling accordingly. This type of long-term plasticity in astrocytes resembles neuronal homeostatic plasticity and might be important to ensure an optimal or expected level of input from neurons.
Collapse
Affiliation(s)
- Alison X. Xie
- Graduate Program in Neuroscience, University of California Riverside, Riverside, California, United States of America
| | - Min-Yu Sun
- Graduate Program in Cellular, Molecular, and Developmental Biology, University of California Riverside, Riverside, California, United States of America
| | - Thomas Murphy
- Graduate Program in Neuroscience, University of California Riverside, Riverside, California, United States of America
| | - Kelli Lauderdale
- Graduate Program in Neuroscience, University of California Riverside, Riverside, California, United States of America
| | - Elizabeth Tiglao
- Undergraduate Neuroscience Major, University of California Riverside, Riverside, California, United States of America
| | - Todd A. Fiacco
- Department of Cell Biology and Neuroscience and Center for Glial-Neuronal Interactions, University of California Riverside, Riverside, California, United States of America
- * E-mail:
| |
Collapse
|
9
|
Brejchová J, Sýkora J, Dlouhá K, Roubalová L, Ostašov P, Vošahlíková M, Hof M, Svoboda P. Fluorescence spectroscopy studies of HEK293 cells expressing DOR-Gi1α fusion protein; the effect of cholesterol depletion. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2819-29. [DOI: 10.1016/j.bbamem.2011.08.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 08/04/2011] [Accepted: 08/08/2011] [Indexed: 01/04/2023]
|
10
|
Adenosine A(1) receptor agonist N(6)-cyclohexyl-adenosine induced phosphorylation of delta opioid receptor and desensitization of its signaling. Acta Pharmacol Sin 2010; 31:784-90. [PMID: 20562901 DOI: 10.1038/aps.2010.70] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
AIM To define the effect of adenosine A(1) receptor (A(1)R) on delta opioid receptor (DOR)-mediated signal transduction. METHODS CHO cells stably expressing HA-tagged A(1)R and DOR-CFP fusion protein were used. The localization of receptors was observed using confocal microscope. DOR-mediated inhibition of adenylyl cyclase was measured using cyclic AMP assay. Western blots were employed to detect the phosphorylation of Akt and the DOR. The effect of A(1)R agonist N(6)-cyclohexyladenosine (CHA) on DOR down-regulation was assessed using radioligand binding assay. RESULTS CHA 1 micromol/L time-dependently attenuated DOR agonist [D-Pen(2,5)]enkephalin (DPDPE)-induced inhibition of intracellular cAMP accumulation with a t(1/2)=2.56 (2.09-3.31) h. Pretreatment with 1 micromol/L CHA for 24 h caused a right shift of the dose-response curve of DPDPE-mediated inhibition of cAMP accumulation, with a significant increase in EC(50) but no change in E(max). Pretreatment with 1 micromol/L CHA for 1 h also induced a significant attenuation of DPDPE-stimulated phosphorylation of Akt. Moreover, CHA time-dependently phosphorylated DOR (Ser363), and this effect was inhibited by A(1)R antagonist 1,3-Dipropyl-8-cyclopentylxanthine (DPCPX) but not by DOR antagonist naloxone. However, CHA failed to produce the down-regulation of DOR, as neither receptor affinity (K(d)) nor receptor density (B(max)) of DOR showed significant change after chronic CHA exposure. CONCLUSION Activation of A(1)R by its agonist caused heterologous desensitization of DOR-mediated inhibition of intracellular cAMP accumulation and phosphorylation of Akt. Activation of A(1)R by its agonist also induced heterologous phosphorylation but not down-regulation of DOR.
Collapse
|