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Ma X, Chen Y, Li XC, Mi WL, Chu YX, Wang YQ, Mao-Ying QL. Spinal Neuronal GRK2 Contributes to Preventive Effect by Electroacupuncture on Cisplatin-Induced Peripheral Neuropathy in Mice. Anesth Analg 2021; 134:204-215. [PMID: 34652301 PMCID: PMC8647702 DOI: 10.1213/ane.0000000000005768] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The main symptoms of chemotherapy-induced peripheral neuropathy (CIPN) include pain and numbness. Neuronal G protein–coupled receptor kinase 2 (GRK2) plays an important role in various pain models. Cisplatin treatment can induce the activation of proinflammatory microglia in spinal cord. The purpose of this study was to investigate the role of spinal neuronal GRK2 in cisplatin-induced CIPN and in the prevention of CIPN by electroacupuncture (EA).
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Affiliation(s)
- Xue Ma
- From the Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine
| | - Yu Chen
- From the Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine
| | - Xiao-Chen Li
- From the Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine
| | - Wen-Li Mi
- From the Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine
| | - Yu-Xia Chu
- From the Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine
| | - Yan-Qing Wang
- From the Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine.,State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science.,Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, Fudan University, Shanghai, People's Republic of China
| | - Qi-Liang Mao-Ying
- From the Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine.,Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, Fudan University, Shanghai, People's Republic of China
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2
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Xu XH, Du RQ, Li L, Yang LL, Zhang Y, Li QM. The role of G-protein-coupled receptor kinase 2 in diabetic mechanical hyperalgesia in rats. Eur J Pain 2021; 25:2039-2049. [PMID: 34101933 DOI: 10.1002/ejp.1819] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 06/04/2021] [Indexed: 11/10/2022]
Abstract
BACKGROUND Previous studies have indicated a negative correlation between GRK2 expression and pain development and transmission. Here, we investigated whether G-protein-coupled receptor kinase 2 (GRK2) was involved in regulating diabetic mechanical hyperalgesia (DMH). METHODS The adeno-associated viral vectors containing the GRK2 gene (AAV-GRK2) were used to up-regulate GRK2 protein expression. The expression of GRK2 and exchange protein directly activated by cyclic adenosine monophosphate 1 (Epac1) in the dorsal root ganglion (DRG) of lumbar 4-6 was detected via immunoblotting and immunohistochemistry, and the transfection of the GRK2 gene was detected by immunofluorescence. RESULTS Low levels of GRK2 were able to sustain STZ-induced pain in DMH rats. Intrathecal injection of AAV-GRK2 vector up-regulated GRK2 expression, providing pain rain to rats with DMH. With an increase in DMH duration, there was a decrease in paw withdrawal threshold (PWT) value, aggravating the pain, resulting in a decreasing pattern in GRK2 protein expression over time, whereas Epac1 protein expression showed an opposite trend. CONCLUSION GRK2 expression regulated DMH progression and is expected to play a role in the development of targeted therapy for DMH. GRK2 and Epac1 expressions play a vital role in maintaining pain in DMH rats.
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Affiliation(s)
- Xiu-Hua Xu
- Postgraduate Training Base of Jinzhou Medical University, The PLA Rocket Force characteristic Medical Center, Beijing, P. R. China
| | - Rui-Qin Du
- Department of Endocrinology, The PLA Rocket Forced Characteristic Medical Center, Beijing, P. R. China
| | - Lin Li
- Department of Endocrinology, The PLA Rocket Forced Characteristic Medical Center, Beijing, P. R. China
| | - Lin-Lin Yang
- 5th Medical Department, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Yi Zhang
- Postgraduate Training Base of Jinzhou Medical University, The PLA Rocket Force characteristic Medical Center, Beijing, P. R. China
| | - Quan-Min Li
- Department of Endocrinology, The PLA Rocket Forced Characteristic Medical Center, Beijing, P. R. China
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Kong H, Jiang CY, Hu L, Teng P, Zhang Y, Pan XX, Sun XD, Liu WT. Morphine induces dysfunction of PINK1/Parkin-mediated mitophagy in spinal cord neurons implying involvement in antinociceptive tolerance. J Mol Cell Biol 2020; 11:1056-1068. [PMID: 30698724 PMCID: PMC7261486 DOI: 10.1093/jmcb/mjz002] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 07/01/2018] [Accepted: 01/28/2019] [Indexed: 01/15/2023] Open
Abstract
The development of opioid-induced analgesic tolerance is a clinical challenge in long-term use for managing chronic pain. The mechanisms of morphine tolerance are poorly understood. Mitochondria-derived reactive oxygen species (ROS) is a crucial signal inducing analgesic tolerance and pain. Chronic administration of morphine leads to robust ROS production and accumulation of damaged mitochondria, which are immediately removed by mitophagy. Here, we show that morphine inhibits mitochondria damage-induced accumulation of PTEN-induced putative kinase 1 (PINK1) in neurons. It interrupts the recruitment of Parkin to the impaired mitochondria and inhibits the ubiquitination of mitochondrial proteins catalyzed by Parkin. Consequently, morphine suppresses the recognition of autophagosomes to the damaged mitochondria mediated by LC3 and sequestosome-1 (SQSTM1/p62). Thus, morphine inhibits autophagy flux and leads to the accumulation of SQSTM1/p62. Finally, the impaired mitochondria cannot be delivered to lysosomes for degradation and ultimately induces robust ROS production and morphine tolerance. Our findings suggest that the dysfunction of mitophagy is involved in morphine tolerance. The deficiency of PINK1/Parkin-mediated clearance of damaged mitochondria is crucial for the generation of excessive ROS and important to the development of analgesic tolerance. These findings suggest that the compounds capable of stabilizing PINK1 or restoring mitophagy may be utilized to prevent or reduce opioid tolerance during chronic pain management.
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Affiliation(s)
- Hong Kong
- Neuroprotective Drug Discovery Key Laboratory of Nanjing Medical University, Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Chun-Yi Jiang
- Neuroprotective Drug Discovery Key Laboratory of Nanjing Medical University, Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Liang Hu
- Neuroprotective Drug Discovery Key Laboratory of Nanjing Medical University, Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Peng Teng
- Neuroprotective Drug Discovery Key Laboratory of Nanjing Medical University, Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Yan Zhang
- Neuroprotective Drug Discovery Key Laboratory of Nanjing Medical University, Department of Pharmacology, Nanjing Medical University, Nanjing, China.,Research Division of Pharmacology, China Pharmaceutical University, Nanjing, China
| | - Xiu-Xiu Pan
- Neuroprotective Drug Discovery Key Laboratory of Nanjing Medical University, Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Xiao-Di Sun
- Neuroprotective Drug Discovery Key Laboratory of Nanjing Medical University, Department of Pharmacology, Nanjing Medical University, Nanjing, China.,Department of Anesthesiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Wen-Tao Liu
- Neuroprotective Drug Discovery Key Laboratory of Nanjing Medical University, Department of Pharmacology, Nanjing Medical University, Nanjing, China.,Department of Pharmacy, Sir Run Run Shaw Hospital Affiliated to Nanjing Medical University, Nanjing, China
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4
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Penela P, Ribas C, Sánchez-Madrid F, Mayor F. G protein-coupled receptor kinase 2 (GRK2) as a multifunctional signaling hub. Cell Mol Life Sci 2019; 76:4423-4446. [PMID: 31432234 PMCID: PMC6841920 DOI: 10.1007/s00018-019-03274-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 08/06/2019] [Accepted: 08/12/2019] [Indexed: 12/18/2022]
Abstract
Accumulating evidence indicates that G protein-coupled receptor kinase 2 (GRK2) is a versatile protein that acts as a signaling hub by modulating G protein-coupled receptor (GPCR) signaling and also via phosphorylation or scaffolding interactions with an extensive number of non-GPCR cellular partners. GRK2 multifunctionality arises from its multidomain structure and from complex mechanisms of regulation of its expression levels, activity, and localization within the cell, what allows the precise spatio-temporal shaping of GRK2 targets. A better understanding of the GRK2 interactome and its modulation mechanisms is helping to identify the GRK2-interacting proteins and its substrates involved in the participation of this kinase in different cellular processes and pathophysiological contexts.
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Affiliation(s)
- Petronila Penela
- Departamento de Biología Molecular, Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, C/Nicolás Cabrera 1, 28049, Madrid, Spain
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain
| | - Catalina Ribas
- Departamento de Biología Molecular, Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, C/Nicolás Cabrera 1, 28049, Madrid, Spain
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain
| | - Francisco Sánchez-Madrid
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain
- Cell-Cell Communication Laboratory, Vascular Pathophysiology Area, Centro Nacional Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
| | - Federico Mayor
- Departamento de Biología Molecular, Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, C/Nicolás Cabrera 1, 28049, Madrid, Spain.
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain.
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain.
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5
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Li T, Wan Y, Sun L, Tao S, Chen P, Liu C, Wang K, Zhou C, Zhao G. Inhibition of MicroRNA-15a/16 Expression Alleviates Neuropathic Pain Development through Upregulation of G Protein-Coupled Receptor Kinase 2. Biomol Ther (Seoul) 2019; 27:414-422. [PMID: 31189298 PMCID: PMC6609114 DOI: 10.4062/biomolther.2018.073] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/24/2018] [Accepted: 08/14/2018] [Indexed: 12/26/2022] Open
Abstract
There is accumulating evidence that microRNAs are emerging as pivotal regulators in the development and progression of neuropathic pain. MicroRNA-15a/16 (miR-15a/16) have been reported to play an important role in various diseases and inflammation response processes. However, whether miR-15a/16 participates in the regulation of neuroinflammation and neuropathic pain development remains unknown. In this study, we established a mouse model of neuropathic pain by chronic constriction injury (CCI) of the sciatic nerves. Our results showed that both miR-15a and miR-16 expression was significantly upregulated in the spinal cord of CCI rats. Downregulation of the expression of miR-15a and miR-16 by intrathecal injection of a specific inhibitor significantly attenuated the mechanical allodynia and thermal hyperalgesia of CCI rats. Furthermore, inhibition of miR-15a and miR-16 downregulated the expression of interleukin-1β and tumor-necrosis factor-α in the spinal cord of CCI rats. Bioinformatic analysis predicted that G protein-coupled receptor kinase 2 (GRK2), an important regulator in neuropathic pain and inflammation, was a potential target gene of miR-15a and miR-16. Inhibition of miR-15a and miR-16 markedly increased the expression of GRK2 while downregulating the activation of p38 mitogen-activated protein kinase and NF-κB in CCI rats. Notably, the silencing of GRK2 significantly reversed the inhibitory effects of miR-15a/16 inhibition in neuropathic pain. In conclusion, our results suggest that inhibition of miR-15a/16 expression alleviates neuropathic pain development by targeting GRK2. These findings provide novel insights into the molecular pathogenesis of neuropathic pain and suggest potential therapeutic targets for preventing neuropathic pain development.
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Affiliation(s)
- Tao Li
- Department of Anesthesiology, China-Japan Union Hospital, Jilin University, Jilin 130033, China
| | - Yingchun Wan
- Department of Endocrinology, China-Japan Union Hospital, Jilin University, Jilin 130033, China
| | - Lijuan Sun
- Department of Endocrinology, China-Japan Union Hospital, Jilin University, Jilin 130033, China
| | - Shoujun Tao
- Department of Anesthesiology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Zhejiang 310006, China
| | - Peng Chen
- Department of Anesthesiology, China-Japan Union Hospital, Jilin University, Jilin 130033, China
| | - Caihua Liu
- Department of Anaesthesiology, The Central Hospital of Wuhan Affiliated with Tongji Medical College of Huazhong University of Science and Technology, Hubei 430014, China
| | - Ke Wang
- Department of Gynaecology and Obstetrics, China-Japan Union Hospital, Jilin University, Jilin 130033, China
| | - Changyu Zhou
- Department of Gastroenterology, China-Japan Union Hospital, Jilin University, Jilin 130033, China
| | - Guoqing Zhao
- Department of Anesthesiology, China-Japan Union Hospital, Jilin University, Jilin 130033, China
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6
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Robichaux WG, Cheng X. Intracellular cAMP Sensor EPAC: Physiology, Pathophysiology, and Therapeutics Development. Physiol Rev 2018; 98:919-1053. [PMID: 29537337 PMCID: PMC6050347 DOI: 10.1152/physrev.00025.2017] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 12/13/2022] Open
Abstract
This review focuses on one family of the known cAMP receptors, the exchange proteins directly activated by cAMP (EPACs), also known as the cAMP-regulated guanine nucleotide exchange factors (cAMP-GEFs). Although EPAC proteins are fairly new additions to the growing list of cAMP effectors, and relatively "young" in the cAMP discovery timeline, the significance of an EPAC presence in different cell systems is extraordinary. The study of EPACs has considerably expanded the diversity and adaptive nature of cAMP signaling associated with numerous physiological and pathophysiological responses. This review comprehensively covers EPAC protein functions at the molecular, cellular, physiological, and pathophysiological levels; and in turn, the applications of employing EPAC-based biosensors as detection tools for dissecting cAMP signaling and the implications for targeting EPAC proteins for therapeutic development are also discussed.
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Affiliation(s)
- William G Robichaux
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center , Houston, Texas
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center , Houston, Texas
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7
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Osteogenesis Is Improved by Low Tumor Necrosis Factor Alpha Concentration through the Modulation of Gs-Coupled Receptor Signals. Mol Cell Biol 2017; 37:MCB.00442-16. [PMID: 28137910 DOI: 10.1128/mcb.00442-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 01/24/2017] [Indexed: 12/31/2022] Open
Abstract
In the early phase of bone damage, low concentrations of the cytokine tumor necrosis factor alpha (TNF-α) favor osteoblast differentiation. In contrast, chronic high doses of the same cytokine contribute to bone loss, demonstrating opposite effects depending on its concentration and on the time of exposure. In the bone microenvironment, TNF-α modulates the expression/function of different G protein-coupled receptors (GPCRs) and of their regulatory proteins, GPCR-regulated kinases (GRKs), thus dictating their final biological outcome in controlling bone anabolic processes. Here, the effects of TNF-α were investigated on the expression/responsiveness of the A2B adenosine receptor (A2BAR), a Gs-coupled receptor that promotes mesenchymal stem cell (MSC) differentiation into osteoblasts. Low TNF-α concentrations exerted a prodifferentiating effect on MSCs, pushing them toward an osteoblast phenotype. By regulating GRK2 turnover and expression, the cytokine impaired A2BAR desensitization, accelerating receptor-mediated osteoblast differentiation. These data supported the anabolic effect of TNF-α submaximal concentration and demonstrated that the cytokine regulates GPCR responses by interfering with the receptor desensitization machinery, thereby enhancing the anabolic responses evoked by A2BAR ligands. Overall, these results indicated that GPCR desensitization plays a pivotal role in osteogenesis and that its manipulation is an effective strategy to favor bone remodeling.
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8
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Penela P. Chapter Three - Ubiquitination and Protein Turnover of G-Protein-Coupled Receptor Kinases in GPCR Signaling and Cellular Regulation. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 141:85-140. [PMID: 27378756 DOI: 10.1016/bs.pmbts.2016.04.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
G-protein-coupled receptors (GPCRs) are responsible for regulating a wide variety of physiological processes, and distinct mechanisms for GPCR inactivation exist to guarantee correct receptor functionality. One of the widely used mechanisms is receptor phosphorylation by specific G-protein-coupled receptor kinases (GRKs), leading to uncoupling from G proteins (desensitization) and receptor internalization. GRKs and β-arrestins also participate in the assembly of receptor-associated multimolecular complexes, thus initiating alternative G-protein-independent signaling events. In addition, the abundant GRK2 kinase has diverse "effector" functions in cellular migration, proliferation, and metabolism homeostasis by means of the phosphorylation or interaction with non-GPCR partners. Altered expression of GRKs (particularly of GRK2 and GRK5) occurs during pathological conditions characterized by impaired GPCR signaling including inflammatory syndromes, cardiovascular disease, and tumor contexts. It is increasingly appreciated that different pathways governing GRK protein stability play a role in the modulation of kinase levels in normal and pathological conditions. Thus, enhanced GRK2 degradation by the proteasome pathway occurs upon GPCR stimulation, what allows cellular adaptation to chronic stimulation in a physiological setting. β-arrestins participate in this process by facilitating GRK2 phosphorylation by different kinases and by recruiting diverse E3 ubiquitin ligase to the receptor complex. Different proteolytic systems (ubiquitin-proteasome, calpains), chaperone activities and signaling pathways influence the stability of GRKs in different ways, thus endowing specificity to GPCR regulation as protein turnover of GRKs can be differentially affected. Therefore, modulation of protein stability of GRKs emerges as a versatile mechanism for feedback regulation of GPCR signaling and basic cellular processes.
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Affiliation(s)
- P Penela
- Department of Molecular Biology and Centre of Molecular Biology "Severo Ochoa" (CSIC-UAM), Madrid, Autonomous University of Madrid, Madrid, Spain; Spain Health Research Institute The Princesa, Madrid, Spain.
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9
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Lu C, Shi L, Sun B, Zhang Y, Hou B, Sun Y, Ma Z, Gu X. A Single Intrathecal or Intraperitoneal Injection of CB2 Receptor Agonist Attenuates Bone Cancer Pain and Induces a Time-Dependent Modification of GRK2. Cell Mol Neurobiol 2016; 37:101-109. [DOI: 10.1007/s10571-016-0349-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Accepted: 02/11/2016] [Indexed: 01/01/2023]
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10
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Cai Y, Kong H, Pan YB, Jiang L, Pan XX, Hu L, Qian YN, Jiang CY, Liu WT. Procyanidins alleviates morphine tolerance by inhibiting activation of NLRP3 inflammasome in microglia. J Neuroinflammation 2016; 13:53. [PMID: 26931361 PMCID: PMC4774188 DOI: 10.1186/s12974-016-0520-z] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Accepted: 02/22/2016] [Indexed: 12/15/2022] Open
Abstract
Background The development of antinociceptive tolerance following repetitive administration of opioid analgesics significantly hinders their clinical use. Evidence has accumulated indicating that microglia within the spinal cord plays a critical role in morphine tolerance. The inhibitor of microglia is effective to attenuate the tolerance; however, the mechanism is not fully understood. Our present study investigated the effects and possible mechanism of a natural product procyanidins in improving morphine tolerance via its specific inhibition on NOD-like receptor protein3 (NLRP3) inflammasome in microglia. Methods CD-1 mice were used for tail-flick test to evaluate the degree of pain. The microglial cell line BV-2 was used to investigate the effects and the mechanism of procyanidins. Reactive oxygen species (ROS) produced from BV-2 cells was evaluated by flow cytometry. Cell signaling was measured by western blot assay and immunofluorescence assay. Results Co-administration of procyanidins with morphine potentiated its antinociception effect and attenuated the development of acute and chronic morphine tolerance. Procyanidins also inhibited morphine-induced increase of interleukin-1β and activation of NOD-like receptor protein3 (NLRP3) inflammasome. Furthermore, procyanidins decreased the phosphorylation of p38 mitogen-activated protein kinase, inhibited the translocation of nuclear factor-κB (NF-κB), and suppressed the level of reactive oxygen species in microglia. Conclusions Procyanidins suppresses morphine-induced activation of NLRP3 inflammasome and inflammatory responses in microglia, and thus resulting in significant attenuation of morphine antinociceptive tolerance. Electronic supplementary material The online version of this article (doi:10.1186/s12974-016-0520-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yang Cai
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Han-Zhong Road, Nanjing, 210029, China
| | - Hong Kong
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Han-Zhong Road, Nanjing, 210029, China
| | - Yin-Bing Pan
- Department of Anesthesiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Lai Jiang
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Han-Zhong Road, Nanjing, 210029, China
| | - Xiu-Xiu Pan
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Han-Zhong Road, Nanjing, 210029, China
| | - Liang Hu
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Han-Zhong Road, Nanjing, 210029, China
| | - Yan-Ning Qian
- Department of Anesthesiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Chun-Yi Jiang
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Han-Zhong Road, Nanjing, 210029, China.
| | - Wen-Tao Liu
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Han-Zhong Road, Nanjing, 210029, China.
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Critical role for Epac1 in inflammatory pain controlled by GRK2-mediated phosphorylation of Epac1. Proc Natl Acad Sci U S A 2016; 113:3036-41. [PMID: 26929333 DOI: 10.1073/pnas.1516036113] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
cAMP signaling plays a key role in regulating pain sensitivity. Here, we uncover a previously unidentified molecular mechanism in which direct phosphorylation of the exchange protein directly activated by cAMP 1 (EPAC1) by G protein kinase 2 (GRK2) suppresses Epac1-to-Rap1 signaling, thereby inhibiting persistent inflammatory pain. Epac1(-/-) mice are protected against inflammatory hyperalgesia in the complete Freund's adjuvant (CFA) model. Moreover, the Epac-specific inhibitor ESI-09 inhibits established CFA-induced mechanical hyperalgesia without affecting normal mechanical sensitivity. At the mechanistic level, CFA increased activity of the Epac target Rap1 in dorsal root ganglia of WT, but not of Epac1(-/-), mice. Using sensory neuron-specific overexpression of GRK2 or its kinase-dead mutant in vivo, we demonstrate that GRK2 inhibits CFA-induced hyperalgesia in a kinase activity-dependent manner. In vitro, GRK2 inhibits Epac1-to-Rap1 signaling by phosphorylation of Epac1 at Ser-108 in the Disheveled/Egl-10/pleckstrin domain. This phosphorylation event inhibits agonist-induced translocation of Epac1 to the plasma membrane, thereby reducing Rap1 activation. Finally, we show that GRK2 inhibits Epac1-mediated sensitization of the mechanosensor Piezo2 and that Piezo2 contributes to inflammatory mechanical hyperalgesia. Collectively, these findings identify a key role of Epac1 in chronic inflammatory pain and a molecular mechanism for controlling Epac1 activity and chronic pain through phosphorylation of Epac1 at Ser-108. Importantly, using the Epac inhibitor ESI-09, we validate Epac1 as a potential therapeutic target for chronic pain.
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Repeated Mu-Opioid Exposure Induces a Novel Form of the Hyperalgesic Priming Model for Transition to Chronic Pain. J Neurosci 2015; 35:12502-17. [PMID: 26354917 DOI: 10.1523/jneurosci.1673-15.2015] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The primary afferent nociceptor was used as a model system to study mechanisms of pain induced by chronic opioid administration. Repeated intradermal injection of the selective mu-opioid receptor (MOR) agonist DAMGO induced mechanical hyperalgesia and marked prolongation of prostaglandin E2 (PGE2) hyperalgesia, a key feature of hyperalgesic priming. However, in contrast to prior studies of priming induced by receptor-mediated (i.e., TNFα, NGF, or IL-6 receptor) or direct activation of protein kinase Cε (PKCε), the pronociceptive effects of PGE2 in DAMGO-treated rats demonstrated the following: (1) rapid induction (4 h compared with 3 d); (2) protein kinase A (PKA), rather than PKCε, dependence; (3) prolongation of hyperalgesia induced by an activator of PKA, 8-bromo cAMP; (4) failure to be reversed by a protein translation inhibitor; (5) priming in females as well as in males; and (6) lack of dependence on the isolectin B4-positive nociceptor. These studies demonstrate a novel form of hyperalgesic priming induced by repeated administration of an agonist at the Gi-protein-coupled MOR to the peripheral terminal of the nociceptor. Significance statement: The current study demonstrates the molecular mechanisms involved in the sensitization of nociceptors produced by repeated activation of mu-opioid receptors and contributes to our understanding of the painful condition observed in patients submitted to chronic use of opioids.
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Abstract
Proinflammatory cytokines are major mediators in the pathogenesis of diseases of joints such as rheumatoid arthritis and osteoarthritis. This review emphasizes that proinflammatory cytokines such as tumor necrosis factor-alpha, interleukin-1beta, interleukin-6 and interleukin-17 are also mediators of pain by directly acting on the nociceptive system. Proportions of nociceptive sensory neurons express receptors for these cytokines, and the application of cytokines rapidly changes the excitability, ion currents and second messenger systems of these neurons. By inducing persistent sensitization of nociceptive sensory neurons (C- and a proportion of Aδ-fibers) for mechanical stimuli in the joint (a process called peripheral sensitization), these cytokines significantly contribute to the persistent hyperalgesia typical for many disease states of the joint. In addition, the disease-associated release of cytokines in the spinal cord supports the generation of central sensitization. The therapeutic neutralization of proinflammatory cytokines thus not only reduces the process of inflammation but may directly reduce hyperalgesia and pain by reversing the neuronal effects of cytokines. It is emerging that different cytokines have different actions on neurons. The neutralization of tumor necrosis factor-alpha reduces both mechanical and thermal hyperalgesia of the joint. The neutralization of interleukin-1beta attenuates thermal hyperalgesia whereas the neutralization of interleukin-6 and interleukin-17 mainly reduces mechanical hyperalgesia. These different effects are partly explained by influencing different target molecules in sensory neurons. For example, in cultured sensory neurons tumor necrosis factor-alpha and interleukin-1beta upregulate the TRPV1 ion channel, which is involved in the transduction of heat stimuli, consistent with an effect of these cytokines in thermal hyperalgesia. By contrast, interleukin-17 upregulates the TRPV4 ion channel, which has a role in the transduction of mechanical stimuli. Thus, the analgesic potential of neutralizing cytokines seems to depend on which cytokine is mainly involved in the particular pain state.
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Affiliation(s)
- Hans-Georg Schaible
- Institute of Physiology I/Neurophysiology, Jena University Hospital - Friedrich Schiller University, Teichgraben 8, Jena, D-07740, Germany.
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Downregulation of Spinal G Protein-Coupled Kinase 2 Abolished the Antiallodynic Effect of Electroacupuncture. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 2015:848603. [PMID: 26064176 PMCID: PMC4429192 DOI: 10.1155/2015/848603] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 04/03/2015] [Indexed: 02/07/2023]
Abstract
Acupuncture or electroacupuncture (EA) has been demonstrated to have a powerful antihypernociceptive effect on inflammatory pain. The attenuation of G protein-coupled receptor kinase 2 (GRK2) in spinal cord and peripheral nociceptor has been widely acknowledged to promote the transition from acute to chronic pain and to facilitate the nociceptive progress. This study was designed to investigate the possible role of spinal GRK2 in EA antiallodynic in a rat model with complete Freund's adjuvant (CFA) induced inflammatory pain. EA was applied to ST36 (“Zusanli”) and BL60 (“Kunlun”) one day after CFA injection. Single EA treatment at day 1 after CFA injection remarkably alleviated CFA induced mechanical allodynia two hours after EA. Repeated EA displayed significant antiallodynic effect from 2nd EA treatment and a persistent effect was observed during the rest of treatments. However, downregulation of spinal GRK2 by intrathecal exposure of GRK2 antisense 30 mins after EA treatment completely eliminated both the transient and persistent antiallodynic effect by EA treatment. These pieces of data demonstrated that the spinal GRK2 played an important role in EA antiallodynia on inflammatory pain.
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15
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Abstract
Reciprocal signalling between immunocompetent cells in the central nervous system (CNS) has emerged as a key phenomenon underpinning pathological and chronic pain mechanisms. Neuronal excitability can be powerfully enhanced both by classical neurotransmitters derived from neurons, and by immune mediators released from CNS-resident microglia and astrocytes, and from infiltrating cells such as T cells. In this Review, we discuss the current understanding of the contribution of central immune mechanisms to pathological pain, and how the heterogeneous immune functions of different cells in the CNS could be harnessed to develop new therapeutics for pain control. Given the prevalence of chronic pain and the incomplete efficacy of current drugs--which focus on suppressing aberrant neuronal activity--new strategies to manipulate neuroimmune pain transmission hold considerable promise.
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Wang H, Heijnen CJ, van Velthoven CTJ, Willemen HLDM, Ishikawa Y, Zhang X, Sood AK, Vroon A, Eijkelkamp N, Kavelaars A. Balancing GRK2 and EPAC1 levels prevents and relieves chronic pain. J Clin Invest 2013; 123:5023-34. [PMID: 24231349 DOI: 10.1172/jci66241] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 09/12/2013] [Indexed: 01/12/2023] Open
Abstract
Chronic pain is a major clinical problem, yet the mechanisms underlying the transition from acute to chronic pain remain poorly understood. In mice, reduced expression of GPCR kinase 2 (GRK2) in nociceptors promotes cAMP signaling to the guanine nucleotide exchange factor EPAC1 and prolongs the PGE2-induced increase in pain sensitivity (hyperalgesia). Here we hypothesized that reduction of GRK2 or increased EPAC1 in dorsal root ganglion (DRG) neurons would promote the transition to chronic pain. We used 2 mouse models of hyperalgesic priming in which the transition from acute to chronic PGE2-induced hyperalgesia occurs. Hyperalgesic priming with carrageenan induced a sustained decrease in nociceptor GRK2, whereas priming with the PKCε agonist ΨεRACK increased DRG EPAC1. When either GRK2 was increased in vivo by viral-based gene transfer or EPAC1 was decreased in vivo, as was the case for mice heterozygous for Epac1 or mice treated with Epac1 antisense oligodeoxynucleotides, chronic PGE2-induced hyperalgesia development was prevented in the 2 priming models. Using the CFA model of chronic inflammatory pain, we found that increasing GRK2 or decreasing EPAC1 inhibited chronic hyperalgesia. Our data suggest that therapies targeted at balancing nociceptor GRK2 and EPAC1 levels have promise for the prevention and treatment of chronic pain.
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Won KA, Kim MJ, Yang KY, Park JS, Lee MK, Park MK, Bae YC, Ahn DK. The glial-neuronal GRK2 pathway participates in the development of trigeminal neuropathic pain in rats. THE JOURNAL OF PAIN 2013; 15:250-61. [PMID: 24216329 DOI: 10.1016/j.jpain.2013.10.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 09/23/2013] [Accepted: 10/31/2013] [Indexed: 10/26/2022]
Abstract
UNLABELLED This study examined the role of the glial-neuronal G protein-coupled receptor kinase 2 (GRK2) pathway in the development of trigeminal neuropathic pain. Male Sprague Dawley rats, weighing 220 to 240 g, were anesthetized with ketamine (0.2 g/kg) and xylazine (0.02 g/kg). Under anesthesia, the left lower second molar was extracted, followed by the placement of a mini-dental implant to intentionally injure the inferior alveolar nerve. This injury produced mechanical allodynia along with the downregulation of neuronal GRK2 expression in the medullary dorsal horn. On the other hand, early intracisternal treatment with MDL28170, a calpain inhibitor, produced prolonged antiallodynic effects and blocked this downregulation of neuronal GRK2 expression. The intracisternal infusion of minocycline, a microglia inhibitor, and l-α-aminoadipic acid, an astrocytic specific inhibitor, also blocked the induced mechanical allodynia and downregulated neuronal GRK2 expression, respectively. Double immunofluorescence showed that the interleukin (IL)-1β and IL-1R signals colocalize with the astrocytes and neurons, respectively, in the medullary dorsal horn following an inferior alveolar nerve injury. In addition, the intracisternal infusion of an IL-1 receptor antagonist also produced antiallodynic effects and blocked the downregulation of neuronal GRK2 expression. These results suggest that the glial-neuronal GRK2 pathway is a potentially important new target for treating neuropathic pain. Moreover, the IL-1β expressed in astrocytes plays a significant role in modulating this pathway. PERSPECTIVE This study showed that the glial-neuronal GRK2 pathway participates in the development of trigeminal neuropathic pain in rats. These results suggest that the glial-neuronal GRK2 pathway is a potentially important new target for the treatment of neuropathic pain.
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Affiliation(s)
- Kyoung A Won
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Min J Kim
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Kui Y Yang
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Jae S Park
- Department of Physiology, School of Medicine, Kyungpook National University Daegu, Daegu, Korea
| | - Min K Lee
- Department of Dental Hygiene, Dong-Eui University, Busan, Korea
| | - Min K Park
- Department of Dental Hygiene, Kyung-Woon University, Gumi, Korea
| | - Yong C Bae
- Department of Oral Anatomy, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Dong K Ahn
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Korea.
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18
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Eidson LN, Murphy AZ. Blockade of Toll-like receptor 4 attenuates morphine tolerance and facilitates the pain relieving properties of morphine. J Neurosci 2013; 33:15952-63. [PMID: 24089500 PMCID: PMC3787504 DOI: 10.1523/jneurosci.1609-13.2013] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 08/26/2013] [Accepted: 08/27/2013] [Indexed: 11/21/2022] Open
Abstract
The ventrolateral periaqueductal gray (vlPAG) is an integral locus for morphine action. Although it is clear that glia contribute to the development of morphine tolerance, to date, the investigation of their role has been limited to spinal and medullary loci. Opioids induce a neuroinflammatory response that opposes acute and long-term analgesia, thereby limiting their efficacy as therapeutic agents. Recent data suggest that the innate immune receptor Toll-like receptor 4 (TLR4), along with its coreceptor myeloid differentiation factor-2 (MD-2), mediates these effects. To date, the brain loci through which TLR4 modulates morphine tolerance have not been identified. We have previously demonstrated that chronic subcutaneous morphine results in tolerance that is accompanied by increases in vlPAG glial cell activity. Using in vivo pharmacological manipulations of vlPAG glia and TLR4 in the adult male rat, we show that intra-vlPAG administration of the general glial cell metabolic inhibitor propentofylline or the astrocyte activity inhibitor fluorocitrate attenuate tolerance to morphine. Characterization of MD-2 expression within the PAG revealed dense MD-2 expression throughout the vlPAG. Further, antagonizing vlPAG TLR4 dose dependently prevented the development of morphine tolerance, and vlPAG microinjections of TLR4 agonists dose dependently produced a "naive" tolerance to subsequent challenge doses of morphine. Finally, using a model of persistent inflammatory pain and pharmacological manipulation of TLR4 we demonstrate that systemic antagonism of TLR4 potentiated acute morphine antihyperalgesia. These results, together, indicate that vlPAG glia regulate morphine tolerance development via TLR4 signaling, and implicate TLR4 as a potential therapeutic target for the treatment of pain.
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Affiliation(s)
- Lori N. Eidson
- Neuroscience Institute, Georgia State University, Atlanta, Georgia 30303
| | - Anne Z. Murphy
- Neuroscience Institute, Georgia State University, Atlanta, Georgia 30303
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19
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Ghanemi A. Targeting G protein coupled receptor-related pathways as emerging molecular therapies. Saudi Pharm J 2013; 23:115-29. [PMID: 25972730 PMCID: PMC4420995 DOI: 10.1016/j.jsps.2013.07.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 07/29/2013] [Indexed: 12/20/2022] Open
Abstract
G protein coupled receptors (GPCRs) represent the most important targets in modern pharmacology because of the different functions they mediate, especially within brain and peripheral nervous system, and also because of their functional and stereochemical properties. In this paper, we illustrate, via a variety of examples, novel advances about the GPCR-related molecules that have been shown to play diverse roles in GPCR pathways and in pathophysiological phenomena. We have exemplified how those GPCRs’ pathways are, or might constitute, potential targets for different drugs either to stimulate, modify, regulate or inhibit the cellular mechanisms that are hypothesized to govern some pathologic, physiologic, biologic and cellular or molecular aspects both in vivo and in vitro. Therefore, influencing such pathways will, undoubtedly, lead to different therapeutical applications based on the related pharmacological implications. Furthermore, such new properties can be applied in different fields. In addition to offering fruitful directions for future researches, we hope the reviewed data, together with the elements found within the cited references, will inspire clinicians and researchers devoted to the studies on GPCR’s properties.
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Affiliation(s)
- Abdelaziz Ghanemi
- Department of Pharmacology, China Pharmaceutical University, Nanjing 210009, China
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20
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Eidson LN, Murphy AZ. Persistent peripheral inflammation attenuates morphine-induced periaqueductal gray glial cell activation and analgesic tolerance in the male rat. THE JOURNAL OF PAIN 2013; 14:393-404. [PMID: 23395474 PMCID: PMC3991566 DOI: 10.1016/j.jpain.2012.12.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 12/12/2012] [Accepted: 12/14/2012] [Indexed: 11/15/2022]
Abstract
UNLABELLED Morphine is among the most prevalent analgesics prescribed for chronic pain. However, prolonged morphine treatment results in the development of analgesic tolerance. An abundance of evidence has accumulated indicating that central nervous system glial cell activity facilitates pain transmission and opposes morphine analgesia. While the midbrain ventrolateral periaqueductal gray (vlPAG) is an important neural substrate mediating pain modulation and the development of morphine tolerance, no studies have directly assessed the role of PAG glia. Here we test the hypothesis that morphine-induced increases in vlPAG glial cell activity contribute to the development of morphine tolerance. As morphine is primarily consumed for the alleviation of severe pain, the influence of persistent inflammatory pain was also assessed. Administration of morphine, in the absence of persistent inflammatory pain, resulted in the rapid development of morphine tolerance and was accompanied by a significant increase in vlPAG glial activation. In contrast, persistent inflammatory hyperalgesia, induced by intraplantar administration of complete Freund's adjuvant (CFA), significantly attenuated the development of morphine tolerance. No significant differences were noted in vlPAG glial cell activation for CFA-treated animals versus controls. These results indicate that vlPAG glia are modulated by a persistent pain state, and implicate vlPAG glial cells as possible regulators of morphine tolerance. PERSPECTIVE The development of morphine tolerance represents a significant impediment to its use in the management of chronic pain. We report that morphine tolerance is accompanied by increased glial cell activation within the vlPAG, and that the presence of a persistent pain state prevented vlPAG glial activation and attenuated morphine tolerance.
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Affiliation(s)
- Lori N Eidson
- Neuroscience Institute, Georgia State University, 100 Piedmont Ave, Atlanta, GA 30303, USA
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21
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Solinski HJ, Zierler S, Gudermann T, Breit A. Human sensory neuron-specific Mas-related G protein-coupled receptors-X1 sensitize and directly activate transient receptor potential cation channel V1 via distinct signaling pathways. J Biol Chem 2012; 287:40956-71. [PMID: 23074220 DOI: 10.1074/jbc.m112.408617] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sensory neuron-specific Mas-related G protein-coupled receptors-X1 (MRGPR-X1) are primate-specific proteins that are exclusively expressed in primary sensory neurons and provoke pain in humans. Hence, MRGPR-X1 represent promising targets for future pain therapy, but signaling pathways activated by MRGPR-X1 are poorly understood. The transient receptor potential cation channel V1 (TRPV1) is also expressed in primary sensory neurons and detects painful stimuli such as protons and heat. G(q)-promoted signaling has been shown to sensitize TRPV1 via protein kinase C (PKC)-dependent phosphorylation. In addition, recent studies suggested TRPV1 activation via a G(q)-mediated mechanism involving diacylglycerol (DAG) or phosphatidylinositol-4,5-bisphosphate (PIP(2)). However, it is not clear if DAG-promoted TRPV1 activation occurs independently from classic TRPV1 activation modes induced by heat and protons. Herein, we analyzed putative functional interactions between MRGPR-X1 and TRPV1 in a previously reported F11 cell line stably over-expressing MRGPR-X1. First, we found that MRGPR-X1 sensitized TRPV1 to heat and protons in a PKC-dependent manner. Second, we observed direct MRGPR-X1-mediated TRPV1 activation independent of MRGPR-X1-induced Ca(2+)-release and PKC activity or other TRPV1 affecting enzymes such as lipoxygenase, extracellular signal-regulated kinases-1/2, sarcoma, or phosphoinositide 3-kinase. Investigating several TRPV1 mutants, we observed that removal of the TRPV1 binding site for DAG and of the putative PIP(2) sensor decreased MRGPR-X1-induced TRPV1 activation by 71 and 43%, respectively. Therefore, we demonstrate dual functional interactions between MRGPR-X1 and TRPV1, resulting in PKC-dependent TRPV1 sensitization and DAG/PIP(2)-mediated activation. The molecular discrimination between TRPV1 sensitization and activation may help improve the specificity of current pain therapies.
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Affiliation(s)
- Hans Jürgen Solinski
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München 80336 München, Germany
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22
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Ferrari LF, Bogen O, Alessandri-Haber N, Levine E, Gear RW, Levine JD. Transient decrease in nociceptor GRK2 expression produces long-term enhancement in inflammatory pain. Neuroscience 2012; 222:392-403. [PMID: 22796071 DOI: 10.1016/j.neuroscience.2012.07.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 06/15/2012] [Accepted: 07/04/2012] [Indexed: 12/13/2022]
Abstract
In heterozygous mice, attenuation of G-protein-coupled receptor kinase 2 (GRK2) level in nociceptors is associated with enhanced and prolonged inflammatory hyperalgesia. To further elucidate the role of GRK2 in nociceptor function we reversibly decreased GRK2 expression using intrathecal antisense oligodeoxynucleotide (AS-ODN). GRK2 AS-ODN administration led to an enhanced and prolonged hyperalgesia induced by prostaglandin E(2), epinephrine and carrageenan. Moreover, this effect persisted unattenuated 2weeks after the last dose of antisense, well after GRK2 protein recovered, suggesting that transient attenuation of GRK2 produced neuroplastic changes in nociceptor function. Unlike hyperalgesic priming induced by transient activation of protein kinase C epsilon (PKCε), (Aley et al., 2000; Parada et al., 2003b), the enhanced and prolonged hyperalgesia following attenuation of GRK2 is PKCε- and cytoplasmic polyadenylation element binding protein (CPEB)-independent and is protein kinase A (PKA)- and Src tyrosine kinase (Src)-dependent. Finally, rats treated with GRK2 AS-ODN exhibited enhanced and prolonged hyperalgesia induced by direct activation of second messengers, adenyl cyclase, Epac or PKA, suggesting changes downstream of G-protein-coupled receptors. Because inflammation can produce a decrease in GRK2, such a mechanism could help explain a predilection to develop chronic pain, after resolution of acute inflammation.
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Affiliation(s)
- L F Ferrari
- Departments of Medicine and Oral Surgery, and Division of Neuroscience, University of California at San Francisco, 521 Parnassus Avenue, San Francisco, CA 94143-0440, USA
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23
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Gurevich EV, Tesmer JJG, Mushegian A, Gurevich VV. G protein-coupled receptor kinases: more than just kinases and not only for GPCRs. Pharmacol Ther 2011; 133:40-69. [PMID: 21903131 DOI: 10.1016/j.pharmthera.2011.08.001] [Citation(s) in RCA: 319] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 08/01/2011] [Indexed: 12/24/2022]
Abstract
G protein-coupled receptor (GPCR) kinases (GRKs) are best known for their role in homologous desensitization of GPCRs. GRKs phosphorylate activated receptors and promote high affinity binding of arrestins, which precludes G protein coupling. GRKs have a multidomain structure, with the kinase domain inserted into a loop of a regulator of G protein signaling homology domain. Unlike many other kinases, GRKs do not need to be phosphorylated in their activation loop to achieve an activated state. Instead, they are directly activated by docking with active GPCRs. In this manner they are able to selectively phosphorylate Ser/Thr residues on only the activated form of the receptor, unlike related kinases such as protein kinase A. GRKs also phosphorylate a variety of non-GPCR substrates and regulate several signaling pathways via direct interactions with other proteins in a phosphorylation-independent manner. Multiple GRK subtypes are present in virtually every animal cell, with the highest expression levels found in neurons, with their extensive and complex signal regulation. Insufficient or excessive GRK activity was implicated in a variety of human disorders, ranging from heart failure to depression to Parkinson's disease. As key regulators of GPCR-dependent and -independent signaling pathways, GRKs are emerging drug targets and promising molecular tools for therapy. Targeted modulation of expression and/or of activity of several GRK isoforms for therapeutic purposes was recently validated in cardiac disorders and Parkinson's disease.
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Affiliation(s)
- Eugenia V Gurevich
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, Preston Research Building, Rm. 454, Nashville, TN 37232, United States.
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24
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Kavelaars A, Eijkelkamp N, Willemen HLDM, Wang H, Carbajal AG, Heijnen CJ. Microglial GRK2: a novel regulator of transition from acute to chronic pain. Brain Behav Immun 2011; 25:1055-60. [PMID: 21473908 DOI: 10.1016/j.bbi.2011.03.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 03/28/2011] [Accepted: 03/30/2011] [Indexed: 12/30/2022] Open
Abstract
Pain is a hallmark of tissue damage and inflammation promoting tissue protection and thereby contributing to repair. Therefore, transient acute pain is an important feature of the adaptive response to damage. However, in a significant number of cases, pain persists for months to years after the problem that originally caused the pain has resolved. Such chronic pain is maladaptive as it no longer serves a protective aim. Chronic pain is debilitating, both physiologically and psychologically, and treatments to provide relief from chronic pain are often ineffective. The neurobiological mechanisms underlying the transition from adaptive acute pain to maladaptive chronic pain are only partially understood. In this review, we will summarize recent evidence that a kinase known as G protein-coupled receptor kinase (GRK2) is a key regulator of the transition from acute to chronic inflammatory pain. Our recent studies have shown that mice with a reduction in the cellular level of GRK2 develop chronic hyperalgesia in response to inflammatory mediators that induce only transient hyperalgesia in WT mice. This finding is clinically relevant because rodent models of chronic pain are associated with reduced cellular levels of GRK2. We propose that GRK2 is a newly discovered major player in the regulation of chronic pain. The pathways regulated by this kinase may open up new avenues for development of treatment strategies that target the cause, and not the symptoms of chronic pain.
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Affiliation(s)
- Annemieke Kavelaars
- Laboratory of Neuroimmunology and Developmental Origins of Disease, University Medical Center Utrecht, Utrecht, The Netherlands.
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25
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Hutchinson MR, Shavit Y, Grace PM, Rice KC, Maier SF, Watkins LR. Exploring the neuroimmunopharmacology of opioids: an integrative review of mechanisms of central immune signaling and their implications for opioid analgesia. Pharmacol Rev 2011; 63:772-810. [PMID: 21752874 DOI: 10.1124/pr.110.004135] [Citation(s) in RCA: 284] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Vastly stimulated by the discovery of opioid receptors in the early 1970s, preclinical and clinical research was directed at the study of stereoselective neuronal actions of opioids, especially those played in their crucial analgesic role. However, during the past decade, a new appreciation of the non-neuronal actions of opioids has emerged from preclinical research, with specific appreciation for the nonclassic and nonstereoselective sites of action. Opioid activity at Toll-like receptors, newly recognized innate immune pattern recognition receptors, adds substantially to this unfolding story. It is now apparent from molecular and rodent data that these newly identified signaling events significantly modify the pharmacodynamics of opioids by eliciting proinflammatory reactivity from glia, the immunocompetent cells of the central nervous system. These central immune signaling events, including the release of cytokines and chemokines and the associated disruption of glutamate homeostasis, cause elevated neuronal excitability, which subsequently decreases opioid analgesic efficacy and leads to heightened pain states. This review will examine the current preclinical literature of opioid-induced central immune signaling mediated by classic and nonclassic opioid receptors. A unification of the preclinical pharmacology, neuroscience, and immunology of opioids now provides new insights into common mechanisms of chronic pain, naive tolerance, analgesic tolerance, opioid-induced hyperalgesia, and allodynia. Novel pharmacological targets for future drug development are discussed in the hope that disease-modifying chronic pain treatments arising from the appreciation of opioid-induced central immune signaling may become practical.
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Affiliation(s)
- Mark R Hutchinson
- Discipline of Pharmacology, School of Medical Science, University of Adelaide, South Australia, Australia, 5005.
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26
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Xing Y, Gu Y, Gomes RR, You J. P2Y(2) receptors and GRK2 are involved in oscillatory fluid flow induced ERK1/2 responses in chondrocytes. J Orthop Res 2011; 29:828-33. [PMID: 21520257 PMCID: PMC3126889 DOI: 10.1002/jor.21319] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 10/28/2010] [Indexed: 02/04/2023]
Abstract
Mechanical loading is an important factor regulating cartilage metabolism maintained by chondrocytes. However, some of its underlying mechanisms remain poorly understood. In this study, we employed a chondrogenic cell line ATDC5 to investigate roles of P2Y(2) and GRK2 in chondrocyte mechanotransduction. We first confirmed the expression of chondrocyte markers in differentiated ATDC5 cells. We then exposed both differentiated and undifferentiated ATDC5 cells to oscillatory fluid flow, and found that differentiated ATDC5 cells responded to oscillatory fluid flow by increasing COX-2 and aggrecan expressions. More importantly, fluid flow induced ERK1/2 response in differentiated cells was increased more than 10 times compared to those in undifferentiated cells. Furthermore, we found that P2Y(2) mRNA and protein levels in differentiated ATDC5 cells were significantly higher than those in undifferentiated cells. In contrast, GRK2 protein levels in differentiated cells were significantly lower than those in undifferentiated cells. Finally, overexpressions of P2Y(2) and GRK2 in differentiated ATDC5 cells result in a 34% increase and a 21% decrease of the ERK1/2 phosphorylation, respectively, in response to oscillatory fluid flow, suggesting important roles of P2Y(2) and GRK2 in chondrocyte mechanotransduction.
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Affiliation(s)
| | | | | | - Jun You
- Corresponding Author: Jun You, Ph.D., Department of Orthopaedics, 500 University Drive, Hershey, PA 17033, U.S.A., , Tel: (01)-717-531-4819, Fax: (01)-717-531-7583
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27
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Wang H, Heijnen CJ, Eijkelkamp N, Carbajal AG, Schedlowski M, Kelley KW, Dantzer R, Kavelaars A. GRK2 in sensory neurons regulates epinephrine-induced signalling and duration of mechanical hyperalgesia. Pain 2011; 152:1649-1658. [PMID: 21514055 DOI: 10.1016/j.pain.2011.03.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 01/26/2011] [Accepted: 03/04/2011] [Indexed: 10/18/2022]
Abstract
Epinephrine (EPI) contributes to hyperalgesia in inflammatory and stress conditions. EPI signals via adrenoceptors, which are regulated by G protein-coupled receptor kinase 2 (GRK2). We previously reported that GRK2 is decreased in nociceptors during chronic inflammation. Herein, we investigated whether GRK2 modulates EPI-induced mechanical and thermal hyperalgesia by using GRK2(+/-) mice, which express 50% of the GRK2 protein. We demonstrate for the first time that EPI-induced mechanical as well as thermal hyperalgesia is prolonged to approximately 21 days in GRK2(+/-) mice, whereas it lasts only 3 to 4 days in wild-type mice. Using cell- specific GRK2-deficient mice, we further show that a low level of GRK2 in primary sensory neurons is critical for this prolongation of EPI-induced hyperalgesia. Low GRK2 in microglia had only a small effect on EPI-induced hyperalgesia. Low GRK2 in astrocytes did not alter EPI-induced hyperalgesia. EPI-induced hyperalgesia was prolonged similarly in mice with tamoxifen-induced homozygous or heterozygous deletion of GRK2. In terms of EPI signalling pathways, the protein kinase A (PKA) inhibitor H-89 inhibited EPI-induced mechanical hyperalgesia in wild-type mice, whereas H-89 had no effect in mice with low GRK2 in sensory neurons (SNS-GRK2(+/-) mice). Conversely, intraplantar injection of the protein kinase Cε PKCε inhibitor TAT-PKC(εv1-2) inhibited hyperalgesia in sensory neuron specific (SNS)-GRK2(+/-) mice and not in wild-type mice. These results indicate that low GRK2 in primary sensory neurons switches EPI-induced signalling from a protein kinase A-dependent toward a PKCε-dependent pathway that ultimately mediates prolonged EPI-induced hyperalgesia.
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Affiliation(s)
- Huijing Wang
- Laboratory of Neuroimmunology and Developmental Origins of Disease, University Medical Center Utrecht, 3584 EA Utrecht, The Netherlands Department of Pharmacology, Shanghai Medical College, Fudan University, 200032 Shanghai, PR China Molecular Nociception Group, University College London, London WC1E 6BT, UK Institute of Medical Psychology and Immunobiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany Integrative Immunology and Behavior Program, College of Medicine and College of ACES, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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Low nociceptor GRK2 prolongs prostaglandin E2 hyperalgesia via biased cAMP signaling to Epac/Rap1, protein kinase Cepsilon, and MEK/ERK. J Neurosci 2010; 30:12806-15. [PMID: 20861385 DOI: 10.1523/jneurosci.3142-10.2010] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Hyperexcitability of peripheral nociceptive pathways is often associated with inflammation and is an important mechanism underlying inflammatory pain. Here we describe a completely novel mechanism via which nociceptor G-protein-coupled receptor kinase 2 (GRK2) contributes to regulation of inflammatory hyperalgesia. We show that nociceptor GRK2 is downregulated during inflammation. In addition, we show for the first time that prostaglandin E2 (PGE2)-induced hyperalgesia is prolonged from <6 h in wild-type (WT) mice to 3 d in mice with low GRK2 in Nav1.8+ nociceptors (SNS-GRK2+/- mice). This prolongation of PGE2 hyperalgesia in SNS-GRK2+/- mice does not depend on changes in the sensitivity of the prostaglandin receptors because prolonged hyperalgesia also developed in response to 8-Br-cAMP. PGE2 or cAMP-induced hyperalgesia in WT mice is PKA dependent. However, PKA activity is not required for hyperalgesia in SNS-GRK2+/- mice. SNS-GRK2+/- mice developed prolonged hyperalgesia in response to the Exchange proteins directly activated by cAMP (Epac) activator 8-pCPT-2'-O-Me-cAMP (8-pCPT). Coimmunoprecipitation experiments showed that GRK2 binds to Epac1. In vitro, GRK2 deficiency increased 8-pCPT-induced activation of the downstream effector of Epac, Rap1, and extracellular signal-regulated kinase (ERK). In vivo, inhibition of MEK1 or PKCε prevented prolonged PGE2, 8-Br-cAMP, and 8-pCPT hyperalgesia in SNS-GRK2+/- mice. In conclusion, we discovered GRK2 as a novel Epac1-interacting protein. A reduction in the cellular level of GRK2 enhances activation of the Epac-Rap1 pathway. In vivo, low nociceptor GRK2 leads to prolonged inflammatory hyperalgesia via biased cAMP signaling from PKA to Epac-Rap1, ERK/PKCε pathways.
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von Banchet GS, Fischer N, Uhlig B, Hensellek S, Eitner A, Schaible HG. Molecular effects of interleukin-1β on dorsal root ganglion neurons: prevention of ligand-induced internalization of the bradykinin 2 receptor and downregulation of G protein-coupled receptor kinase 2. Mol Cell Neurosci 2010; 46:262-71. [PMID: 20883789 DOI: 10.1016/j.mcn.2010.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 09/20/2010] [Accepted: 09/21/2010] [Indexed: 10/19/2022] Open
Abstract
In dorsal root ganglion sections numerous small-to medium-sized neurons were found to exhibit extensive colocalization of the bradykinin receptor 2, the interleukin-1 receptor 1 and G protein-coupled receptor kinase 2. Application of bradykinin to cultured DRG neurons caused substantial internalization of the bradykinin 2 receptor which significantly reduced the responsiveness of DRG neurons to a second application of bradykinin. Such an internalization was not observed in DRG neurons which were exposed to long-term pretreatment with interleukin-1β. The long-term incubation with interleukin-1β on its own did neither change the proportion of neurons which expressed the bradykinin 2 receptor in the cytoplasma nor the proportion of neurons expressing the bradykinin 2 receptor in the membrane but it reduced the proportion of neurons expressing G protein-coupled receptor kinase 2, an enzyme which facilitates the internalization of G protein-coupled receptors. These results show that interleukin-1β maintains the responsiveness of DRG neurons to bradykinin in the long-term range, and they suggest that the downregulation of G protein-coupled receptor kinase 2 could be a cellular mechanism involved in this interleukin-1β effect.
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Affiliation(s)
- Gisela Segond von Banchet
- Jena University Hospital - Friedrich Schiller University Jena, Institute of Physiology Ι, Teichgraben 8, D-07743 Jena, Germany.
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Willemen HLDM, Eijkelkamp N, Wang H, Dantzer R, Dorn GW, Kelley KW, Heijnen CJ, Kavelaars A. Microglial/macrophage GRK2 determines duration of peripheral IL-1beta-induced hyperalgesia: contribution of spinal cord CX3CR1, p38 and IL-1 signaling. Pain 2010; 150:550-560. [PMID: 20609517 DOI: 10.1016/j.pain.2010.06.015] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 05/17/2010] [Accepted: 06/15/2010] [Indexed: 12/27/2022]
Abstract
Chronic pain associated with inflammation is a major clinical problem, but the underlying mechanisms are incompletely understood. Recently, we reported that GRK2(+/-) mice with a approximately 50% reduction of GRK2 develop prolonged hyperalgesia following a single intraplantar injection of the pro-inflammatory cytokine interleukin-1beta (IL-1beta). Here we show that spinal microglia/macrophage GRK2 is reduced during chronic inflammation-induced hyperalgesia. Next, we applied CRE-Lox technology to create mice with low GRK2 in microglia/macrophages/granulocytes (LysM-GRK2(f/+)), or sensory neurons or astrocytes. Only mice deficient in microglial/macrophage/granulocyte GRK2 display prolonged IL-1beta-induced hyperalgesia that lasts up to 8days. Two days after intraplantar IL-1beta, increased microglial/macrophage activity occurs in the lumbar but not thoracic spinal cord of GRK2-deficient mice. Intrathecal pre-treatment with minocycline, an inhibitor of microglia/macrophage activation, accelerates resolution of hyperalgesia independent of genotype and prevents transition to chronic hyperalgesia in GRK2(+/-) mice. Ongoing hyperalgesia in GRK2(+/-) mice is reversed by minocycline administration at days 1 and 2 after IL-1beta injection. Similarly, IL-1beta-induced hyperalgesia in LysM-GRK2(f/+) mice is attenuated by intrathecal administration of anti-CX3CR1 to abrogate fractalkine signaling, the p38 inhibitor SB239063 and the IL-1 antagonist IL-1ra. These data establish that chronic inflammatory hyperalgesia is associated with reduced GRK2 in microglia/macrophages and that low GRK2 in these cells is sufficient to markedly prolong hyperalgesia after a single intraplantar injection of IL-1beta. Ongoing hyperalgesia is maintained by spinal microglial/macrophage activity, fractalkine signaling, p38 activation and IL-1 signaling. We propose that chronic inflammation decreases spinal microglial/macrophage GRK2, which prevents silencing of microglia/macrophage activity and thereby contributes to prolonged hyperalgesia.
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Affiliation(s)
- Hanneke L D M Willemen
- Laboratory of Neuroimmunology and Developmental Origins of Disease (NIDOD), University Medical Center Utrecht, 3584 EA Utrecht, The Netherlands Integrative Immunology and Behavior Program, College of ACES and College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Center for Pharmacogenomics, Washington University, St. Louis, MI 63110, USA
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31
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Abstract
Chronic pain associated with inflammation is a common clinical problem, and the underlying mechanisms have only begun to be unraveled. GRK2 regulates cellular signaling by promoting G-protein-coupled receptor (GPCR) desensitization and direct interaction with downstream kinases including p38. The aim of this study was to determine the contribution of GRK2 to regulation of inflammatory pain and to unravel the underlying mechanism. GRK2(+/-) mice with an approximately 50% reduction in GRK2 developed increased and markedly prolonged thermal hyperalgesia and mechanical allodynia after carrageenan-induced paw inflammation or after intraplantar injection of the GPCR-binding chemokine CCL3. The effect of reduced GRK2 in specific cells was investigated using Cre-Lox technology. Carrageenan- or CCL3-induced hyperalgesia was increased but not prolonged in mice with decreased GRK2 only in Na(v)1.8 nociceptors. In vitro, reduced neuronal GRK2 enhanced CCL3-induced TRPV1 sensitization. In vivo, CCL3-induced acute hyperalgesia in GRK2(+/-) mice was mediated via TRPV1. Reduced GRK2 in microglia/monocytes only was required and sufficient to transform acute carrageenan- or CCL3-induced hyperalgesia into chronic hyperalgesia. Chronic hyperalgesia in GRK2(+/-) mice was associated with ongoing microglial activation and increased phospho-p38 and tumor necrosis factor alpha (TNF-alpha) in the spinal cord. Inhibition of spinal cord microglial, p38, or TNF-alpha activity by intrathecal administration of specific inhibitors reversed ongoing hyperalgesia in GRK2(+/-) mice. Microglia/macrophage GRK2 expression was reduced in the lumbar ipsilateral spinal cord during neuropathic pain, underlining the pathophysiological relevance of microglial GRK2. Thus, we identified completely novel cell-specific roles of GRK2 in regulating acute and chronic inflammatory hyperalgesia.
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Lötsch J, Geisslinger G, Tegeder I. Genetic modulation of the pharmacological treatment of pain. Pharmacol Ther 2009; 124:168-84. [DOI: 10.1016/j.pharmthera.2009.06.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Accepted: 06/22/2009] [Indexed: 12/15/2022]
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Kleibeuker W, Gabay E, Kavelaars A, Zijlstra J, Wolf G, Ziv N, Yirmiya R, Shavit Y, Tal M, Heijnen CJ. IL-1 beta signaling is required for mechanical allodynia induced by nerve injury and for the ensuing reduction in spinal cord neuronal GRK2. Brain Behav Immun 2008; 22:200-8. [PMID: 17869478 DOI: 10.1016/j.bbi.2007.07.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Revised: 07/13/2007] [Accepted: 07/17/2007] [Indexed: 01/11/2023] Open
Abstract
Many neurotransmitters involved in pain perception transmit signals via G protein-coupled receptors (GPCRs). GPCR kinase 2 (GRK2) regulates agonist-induced desensitization and signaling of multiple GPCRs and interacts with downstream molecules with consequences for signaling. In general, low GRK2 levels are associated with increased responses to agonist stimulation of GPCRs. Recently, we reported that in mice with reduced GRK2 levels, inflammation-induced mechanical allodynia was increased. In addition, mice with impaired interleukin (IL)-1 beta signaling did not develop mechanical allodynia after L5 spinal nerve transection (SNT). We hypothesized that in the L5 SNT model mechanical allodynia would be associated with reduced neuronal GRK2 levels in the spinal cord dorsal horn and that IL-1 beta signaling would be required to induce both the decrease in GRK2 and mechanical allodynia. We show here that in wild type (WT) mice L5 SNT induces a bilateral decrease in neuronal GRK2 expression in the lumbar spinal cord dorsal horn, 1 and 2 weeks after L5 SNT. No changes in GRK2 were observed in the thoracic segments. Moreover, spinal cord GRK2 expression was not decreased in IL-1R(-/-) mice after L5 SNT. These data show that IL-1 beta signaling is not only required for the development of mechanical allodynia, but also to reduce neuronal GRK2 expression. These results suggest a functional relation between the L5 SNT-induced IL-1 beta-mediated decrease in GRK2 and development of mechanical allodynia.
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Affiliation(s)
- Wendy Kleibeuker
- University Medical Centre Utrecht, Laboratory of Psychoneuroimmunology, Lundlaan 6, 3584 EA Utrecht, The Netherlands
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Kleibeuker W, Jurado-Pueyo M, Murga C, Eijkelkamp N, Mayor Jr F, Heijnen CJ, Kavelaars A. Physiological changes in GRK2 regulate CCL2-induced signaling to ERK1/2 and Akt but not to MEK1/2 and calcium. J Neurochem 2008; 104:979-92. [DOI: 10.1111/j.1471-4159.2007.05023.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Watkins LR, Hutchinson MR, Milligan ED, Maier SF. "Listening" and "talking" to neurons: implications of immune activation for pain control and increasing the efficacy of opioids. BRAIN RESEARCH REVIEWS 2007; 56:148-69. [PMID: 17706291 PMCID: PMC2245863 DOI: 10.1016/j.brainresrev.2007.06.006] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 06/21/2007] [Accepted: 06/26/2007] [Indexed: 01/08/2023]
Abstract
It is recently become clear that activated immune cells and immune-like glial cells can dramatically alter neuronal function. By increasing neuronal excitability, these non-neuronal cells are now implicated in the creation and maintenance of pathological pain, such as occurs in response to peripheral nerve injury. Such effects are exerted at multiple sites along the pain pathway, including at peripheral nerves, dorsal root ganglia, and spinal cord. In addition, activated glial cells are now recognized as disrupting the pain suppressive effects of opioid drugs and contributing to opioid tolerance and opioid dependence/withdrawal. While this review focuses on regulation of pain and opioid actions, such immune-neuronal interactions are broad in their implications. Such changes in neuronal function would be expected to occur wherever immune-derived substances come in close contact with neurons.
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Affiliation(s)
- Linda R Watkins
- Department of Psychology and Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309-0345, USA.
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