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Mitchell R, Mikolajczak M, Kersten C, Fleetwood-Walker S. ErbB1-dependent signalling and vesicular trafficking in primary afferent nociceptors associated with hypersensitivity in neuropathic pain. Neurobiol Dis 2020; 142:104961. [DOI: 10.1016/j.nbd.2020.104961] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/26/2020] [Accepted: 06/08/2020] [Indexed: 02/06/2023] Open
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2
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Difference of acute dissociation and 1-day culture on the electrophysiological properties of rat dorsal root ganglion neurons. J Physiol Biochem 2018; 74:207-221. [DOI: 10.1007/s13105-017-0606-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 12/29/2017] [Indexed: 10/24/2022]
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3
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Zhang Q, Hsia SC, Martin-Caraballo M. Regulation of T-type Ca 2+ channel expression by herpes simplex virus-1 infection in sensory-like ND7 cells. J Neurovirol 2017. [PMID: 28639215 DOI: 10.1007/s13365-017-0545-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Infection of sensory neurons by herpes simplex virus (HSV)-1 disrupts electrical excitability, altering pain sensory transmission. Because of their low threshold for activation, functional expression of T-type Ca2+ channels regulates various cell functions, including neuronal excitability and neuronal communication. In this study, we have tested the effect of HSV-1 infection on the functional expression of T-type Ca2+ channels in differentiated ND7-23 sensory-like neurons. Voltage-gated Ca2+ currents were measured using whole cell patch clamp recordings in differentiated ND7-23 neurons under various culture conditions. Differentiation of ND7-23 cells evokes a significant increase in T-type Ca2+ current densities. Increased T-type Ca2+ channel expression promotes the morphological differentiation of ND7-23 cells and triggers a rebound depolarization. HSV-1 infection of differentiated ND7-23 cells causes a significant loss of T-type Ca2+ channels from the membrane. HSV-1 evoked reduction in the functional expression of T-type Ca2+ channels is mediated by several factors, including decreased expression of Cav3.2 T-type Ca2+ channel subunits and disruption of endocytic transport. Decreased functional expression of T-type Ca2+ channels by HSV-1 infection requires protein synthesis and viral replication, but occurs independently of Egr-1 expression. These findings suggest that infection of neuron-like cells by HSV-1 causes a significant disruption in the expression of T-type Ca2+ channels, which can results in morphological and functional changes in electrical excitability.
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Affiliation(s)
- Qiaojuan Zhang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Eastern Shore, Princess Anne, MD, 21853, USA
| | - Shao-Chung Hsia
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Eastern Shore, Princess Anne, MD, 21853, USA
| | - Miguel Martin-Caraballo
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Eastern Shore, Princess Anne, MD, 21853, USA.
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Thrombospondin-4 divergently regulates voltage-gated Ca2+ channel subtypes in sensory neurons after nerve injury. Pain 2017; 157:2068-2080. [PMID: 27168360 DOI: 10.1097/j.pain.0000000000000612] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Loss of high-voltage-activated (HVA) calcium current (ICa) and gain of low-voltage-activated (LVA) ICa after painful peripheral nerve injury cause elevated excitability in sensory neurons. Nerve injury is also accompanied by increased expression of the extracellular matrix glycoprotein thrombospondin-4 (TSP4), and interruption of TSP4 function can reverse or prevent behavioral hypersensitivity after injury. We therefore investigated TSP4 regulation of ICa in dorsal root ganglion (DRG) neurons. During depolarization adequate to activate HVA ICa, TSP4 decreases both N- and L-type ICa and the associated intracellular calcium transient. In contrast, TSP4 increases ICa and the intracellular calcium signal after low-voltage depolarization, which we confirmed is due to ICa through T-type channels. These effects are blocked by gabapentin, which ameliorates neuropathic pain by targeting the α2δ1 calcium subunit. Injury-induced changes of HVA and LVA ICa are attenuated in TSP4 knockout mice. In the neuropathic pain model of spinal nerve ligation, TSP4 application did not further regulate ICa of injured DRG neurons. Taken together, these findings suggest that elevated TSP4 after peripheral nerve injury may contribute to hypersensitivity of peripheral sensory systems by decreasing HVA and increasing LVA in DRG neurons by targeting the α2δ1 calcium subunit. Controlling TSP4 overexpression in peripheral sensory neurons may be a target for analgesic drug development for neuropathic pain.
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Abstract
UNLABELLED Tauopathies are neurodegenerative diseases characterized by intraneuronal inclusions of hyperphosphorylated tau protein and abnormal expression of brain-derived neurotrophic factor (BDNF), a key modulator of neuronal survival and function. The severity of both these pathological hallmarks correlate with the degree of cognitive impairment in patients. However, how tau pathology specifically modifies BDNF signaling and affects neuronal function during early prodromal stages of tauopathy remains unclear. Here, we report that the mild tauopathy developing in retinal ganglion cells (RGCs) of the P301S tau transgenic (P301S) mouse induces functional retinal changes by disrupting BDNF signaling via the TrkB receptor. In adult P301S mice, the physiological visual response of RGCs to pattern light stimuli and retinal acuity decline significantly. As a consequence, the activity-dependent secretion of BDNF in the vitreous is impaired in P301S mice. Further, in P301S retinas, TrkB receptors are selectively upregulated, but uncoupled from downstream extracellular signal-regulated kinase (ERK) 1/2 signaling. We also show that the impairment of TrkB signaling is triggered by tau pathology and mediates the tau-induced dysfunction of visual response. Overall our results identify a neurotrophin-mediated mechanism by which tau induces neuronal dysfunction during prodromal stages of tauopathy and define tau-driven pathophysiological changes of potential value to support early diagnosis and informed therapeutic decisions. SIGNIFICANCE STATEMENT This work highlights the potential molecular mechanisms by which initial tauopathy induces neuronal dysfunction. Combining clinically used electrophysiological techniques (i.e., electroretinography) and molecular analyses, this work shows that in a relevant model of early tauopathy, the retina of the P301S mutant human tau transgenic mouse, mild tau pathology results in functional changes of neuronal activity, likely due to selective impairment of brain-derived neurotrophic factor signaling via its receptor, TrkB. These findings may have important translational implications for early diagnosis in a subset of Alzheimer's disease patients with early visual symptoms and emphasize the need to clarify the pathophysiological changes associated with distinct tauopathy stages to support informed therapeutic decisions and guide drug discovery.
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Kim SY, Han YM, Oh M, Kim WK, Oh KJ, Lee SC, Bae KH, Han BS. DUSP4 regulates neuronal differentiation and calcium homeostasis by modulating ERK1/2 phosphorylation. Stem Cells Dev 2014; 24:686-700. [PMID: 25397900 DOI: 10.1089/scd.2014.0434] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Protein tyrosine phosphatases have been recognized as critical components of multiple signaling regulators of fundamental cellular processes, including differentiation, cell death, and migration. In this study, we show that dual specificity phosphatase 4 (DUSP4) is crucial for neuronal differentiation and functions in the neurogenesis of embryonic stem cells (ESCs). The endogenous mRNA and protein expression levels of DUSP4 gradually increased during mouse development from ESCs to postnatal stages. Neurite outgrowth and the expression of neuron-specific markers were markedly reduced by genetic ablation of DUSP4 in differentiated neurons, and these effects were rescued by the reintroduction of DUSP4. In addition, DUSP4 knockdown dramatically enhanced extracellular signal-regulated kinase (ERK) activation during neuronal differentiation. Furthermore, the DUSP4-ERK pathway functioned to balance calcium signaling, not only by regulating Ca(2+)/calmodulin-dependent kinase I phosphorylation, but also by facilitating Cav1.2 expression and plasma membrane localization. These data are the first to suggest a molecular link between the MAPK-ERK cascade and calcium signaling, which provides insight into the mechanism by which DUSP4 modulates neuronal differentiation.
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Affiliation(s)
- Sun Young Kim
- 1 Department of Biological Sciences, Center for Stem Cell Differentiation, KAIST , Daejeon, Republic of Korea
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7
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Melemedjian OK, Khoutorsky A, Sorge RE, Yan J, Asiedu MN, Valdez A, Ghosh S, Dussor G, Mogil JS, Sonenberg N, Price TJ. mTORC1 inhibition induces pain via IRS-1-dependent feedback activation of ERK. Pain 2013; 154:1080-91. [PMID: 23607966 DOI: 10.1016/j.pain.2013.03.021] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 03/05/2013] [Accepted: 03/12/2013] [Indexed: 02/07/2023]
Abstract
Mammalian target of rapamycin complex 1 (mTORC1) inhibitors are extensively used as immunosuppressants to prevent transplant rejection and in treatment of certain cancers. In patients, chronic treatment with rapamycin or its analogues (rapalogues) has been reported to lead to sensory hypersensitivity and pain conditions via an unknown mechanism. Here, we show that pharmacological or genetic inhibition of mTORC1 activates the extracellular signal-regulated kinase (ERK) pathway in sensory neurons via suppression of S6K1 to insulin receptor substrate 1 negative feedback loop. As a result, increased ERK activity induces sensory neuron sensitization, mechanical hypersensitivity, and spontaneous pain. The clinically available adenosine monophosphate-activated protein kinase activator, metformin, which is an antidiabetic drug, prevents rapamycin-induced ERK activation and the development of mechanical hypersensitivity and spontaneous pain. Taken together, our findings demonstrate that activation of the ERK pathway in sensory neurons as a consequence of mTORC1 inhibition leads to the development of pain. Importantly, this effect is abolished by co-treatment with metformin, thus providing a potential treatment option for rapalogue-evoked pain. Our findings highlight the physiological relevance of feedback signaling through mTORC1 inhibition and have important implications for development of pain therapeutics that target the mTOR pathway.
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Abstract
Brain-derived neurotrophic factor (BDNF)--a member of a small family of secreted proteins that includes nerve growth factor, neurotrophin 3 and neurotrophin 4--has emerged as a key regulator of neural circuit development and function. The expression, secretion and actions of BDNF are directly controlled by neural activity, and secreted BDNF is capable of mediating many activity-dependent processes in the mammalian brain, including neuronal differentiation and growth, synapse formation and plasticity, and higher cognitive functions. This Review summarizes some of the recent progress in understanding the cellular and molecular mechanisms underlying neurotrophin regulation of neural circuits. The focus of the article is on BDNF, as this is the most widely expressed and studied neurotrophin in the mammalian brain.
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Mortensen OV. MKP3 eliminates depolarization-dependent neurotransmitter release through downregulation of L-type calcium channel Cav1.2 expression. Cell Calcium 2013; 53:224-30. [PMID: 23337371 DOI: 10.1016/j.ceca.2012.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 12/06/2012] [Accepted: 12/24/2012] [Indexed: 01/17/2023]
Abstract
Release of neurotransmitters is a fundamental and regulated process that is essential for normal brain functioning. Regulation of this process is potentially important for any neuronal process, and disruption of the release process may contribute to the pathophysiology associated with psychiatric diseases. In this work it is shown that expression of the negative regulator of mitogen-activated protein kinase (MAPK) signaling the MAPK phosphatase MKP3/DUSP6 eliminates depolarization-dependent release of dopamine in rat PC12 cells. Pharmacologic interventions with latrotroxin (LTX) or A23187, which make the cells permeable to calcium, reestablish the dopamine release. Calcium imaging also reveals that calcium influx is impaired in MKP3-expressing cells. Because acute pharmacologic inhibition of MAPKs has no effect on dopamine release in naïve PC12 cells, the MKP3-mediated elimination of neurotransmitter release must be caused by a long-term process, such as changes in gene expression. In support of this the expression of the L-type calcium channel cav1.2 alpha subunit (Cacna1c) is decreased in MKP3-expressing PC12 cells. With the reintroduction of cav1.2 expression, neurotransmitter release is restored in the MKP3-expressing PC12 cells. Thus, MKP3 expression reduces neurotransmitter release by decreasing the expression of cav1.2. Because MKP3 is increased when neuronal activity is elevated, this process could play a role in regulating neurotransmitter homeostasis.
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Affiliation(s)
- Ole V Mortensen
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
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Campbell TM, Main MJ, Fitzgerald EM. Functional expression of the voltage-gated sodium channel, Nav1.7, underlies epidermal growth factor-mediated invasion in human [R1.S1] non-small cell lung cancer cells. J Cell Sci 2013; 126:4939-49. [DOI: 10.1242/jcs.130013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Various ion channels are expressed in human cancers where they are intimately involved in proliferation, angiogenesis, invasion and metastasis. Expression of functional voltage-gated sodium channels (Nav) is implicated in the metastatic potential of breast, prostate, lung and colon cancer cells. However, the cellular mechanisms that regulate Nav expression in cancer remain largely unknown. Growth factors are attractive candidates; they not only play crucial roles in cancer progression but are also key regulators of ion channel expression and activity in non-cancerous cells. Here, we examine the role of epidermal growth factor receptor (EGFR) signalling and Nav in non-small cell lung carcinoma (NSCLC) cell lines. We show unequivocally, that functional expression of Nav1.7 promotes invasion in H460 NSCLC cells. Inhibition of Nav1.7 activity (tetrodotoxin), or, expression (small interfering RNA), reduces H460 cell invasion by up to 50%. Crucially, non-invasive wild type A549 cells lack functional Nav whereas exogenous over-expression of Nav1.7 is sufficient to promote TTX-sensitive invasion of these cells. EGF/EGFR signalling enhances proliferation, migration and invasion of H460 cells but we find that EGFR-mediated up-regulation of Nav1.7 specifically, is necessary for invasive behaviour in these cells. Examination of Nav1.7 expression at the mRNA, protein and functional levels further reveals that EGF/EGFR signalling via the ERK1/2 pathway controls transcriptional regulation of channel expression to promote cellular invasion. Immunohistochemistry of patient biopsies confirms the clinical relevance of Nav1.7 expression in NSCLC. Thus, Nav1.7 has significant potential as a novel target for therapeutic intervention and/or as a diagnostic/prognostic marker in NSCLC.
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Schmutzler BS, Roy S, Pittman SK, Meadows RM, Hingtgen CM. Ret-dependent and Ret-independent mechanisms of Gfl-induced sensitization. Mol Pain 2011; 7:22. [PMID: 21450093 PMCID: PMC3078874 DOI: 10.1186/1744-8069-7-22] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 03/30/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The GDNF family ligands (GFLs) are regulators of neurogenic inflammation and pain. We have previously shown that GFLs increase the release of the sensory neuron neuropeptide, calcitonin gene-related peptide (CGRP) from isolated mouse DRG. RESULTS Inhibitors of the mitogen-activated protein kinase (MAPK) pathway abolished the enhancement of CGRP release by GDNF. Neurturin-induced enhancement in the stimulated release of CGRP, used as an indication of sensory neuronal sensitization, was abolished by inhibition of the phosphatidylinositol-3 kinase (PI-3K) pathway. Reduction in Ret expression abolished the GDNF-induced sensitization, but did not fully inhibit the increase in stimulus-evoked release of CGRP caused by neurturin or artemin, indicating the presence of Ret-independent GFL-induced signaling in sensory neurons. Integrin β-1 and NCAM are involved in a component of Ret-independent GFL signaling in sensory neurons. CONCLUSIONS These data demonstrate the distinct and variable Ret-dependent and Ret-independent signaling mechanisms by which GFLs induce sensitization of sensory neurons. Additionally, there is a clear disconnect between intracellular signaling pathway activation and changes in sensory neuronal function.
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Affiliation(s)
- Brian S Schmutzler
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, 46202, USA.
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Guillou A, Romanò N, Bonnefont X, Le Tissier P, Mollard P, Martin AO. Modulation of the tyrosine kinase receptor Ret/glial cell-derived neurotrophic factor (GDNF) signaling: a new player in reproduction induced anterior pituitary plasticity? Endocrinology 2011; 152:515-25. [PMID: 21239429 DOI: 10.1210/en.2010-0673] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
During gestation, parturition, and lactation, the endocrine axis of the dam must continually adapt to ensure the continual and healthy development of offspring. The anterior pituitary gland, which serves as the endocrine interface between the brain and periphery, undergoes adaptations that contribute to regulation of the reproductive axis. Growth factors and their receptors are potential candidates for intrapituitary and paracrine factors to participate in the functional and anatomical plasticity of the gland. We examined the involvement of the growth factor glial cell-derived neurotrophic factor (GDNF) and its receptor tyrosine kinase rearranged during transfection (Ret) in the physiological functional and anatomical plasticity of the anterior pituitary gland. We found that variations in both expression and subcellular localization of Ret during gestation and lactation are temporally correlated with changes in pituitary gland function. We showed that Ret/GDNF signaling could endorse two different functional roles depending on the physiological status. At the end of lactation and after weaning, Ret was colocalized with markers of apoptosis. We found that Ret could therefore act as a physiological dependence receptor capable of inducing apoptosis in the absence of GDNF. In addition, we identified the follicullostellate cell as a probable source for intrapituitary GDNF and proposed GDNF as a potential physiological modulator of endocrine cell function. During all stages studied, we showed that acute application of GDNF to pituitary slices was able to modulate both positively and negatively intracellular calcium activity. Altogether our results implicate Ret/GDNF as a potent pleiotropic factor able to influence pituitary physiology during a period of high plasticity.
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Affiliation(s)
- Anne Guillou
- Department of Endocrinology, Institute of Functional Genomics, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale Unité 661, and University of Montpellier, Montpellier 34094, France
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Subtype-specific reduction of voltage-gated calcium current in medium-sized dorsal root ganglion neurons after painful peripheral nerve injury. Neuroscience 2011; 179:244-55. [PMID: 21277351 DOI: 10.1016/j.neuroscience.2011.01.049] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 01/08/2011] [Accepted: 01/23/2011] [Indexed: 11/23/2022]
Abstract
Sensory neurons express a variety of voltage-gated Ca2+ channel subtypes, but reports differ on their proportionate representation, and the effects of painful nerve injury on each subtype are not established. We compared levels of high-voltage activated currents in medium-sized (30-40 μm) dorsal root ganglion neurons dissociated from control animals and those subjected to spinal nerve ligation, using sequential application of semiselective channel blockers (nisoldipine for L-type, SNX-111 or ω-conotoxin GVIA for N-type, agatoxin IVA or ω-conotoxin MVIIC for P/Q-type, and SNX-482 for a component of R-type) during either square wave depolarizations or action potential waveform voltage commands. Using sequential administration of multiple blockers, proportions of total Ca2+ current attributable to different subtypes and the effect of injury depended on the sequence of blocker administration and type of depolarization command. Overall, however, N-type and L-type currents comprised the dominant components of ICa in sensory neurons under control conditions, and these subtypes showed the greatest loss of current following injury (L-type 26-71% loss, N-type 0-51% loss). Further exploration of N-type current identified by its sensitivity to ω-conotoxin GVIA applied alone showed that injury reduced the peak N-type current during step depolarization by 68% and decreased the total charge entry during action potential waveform stimulation by 44%. Isolation of N-type current by blockade of all other subtypes demonstrated a 50% loss with injury, and also revealed an injury-related rightward shift in the activation curve. Non-stationary noise analyses of N-type current in injured neurons revealed unitary channel current and number of channels that were not different from control, which indicates that injury-induced loss of current is due to a decrease in channel open probability. Our findings suggest that diminished Ca2+ influx through N-type and L-type channels may contribute to sensory neuron dysfunction and pain after nerve injury.
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Castañeda-Corral G, Jimenez-Andrade JM, Bloom AP, Taylor RN, Mantyh WG, Kaczmarska MJ, Ghilardi JR, Mantyh PW. The majority of myelinated and unmyelinated sensory nerve fibers that innervate bone express the tropomyosin receptor kinase A. Neuroscience 2011; 178:196-207. [PMID: 21277945 DOI: 10.1016/j.neuroscience.2011.01.039] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 01/16/2011] [Accepted: 01/20/2011] [Indexed: 12/13/2022]
Abstract
Although skeletal pain is a leading cause of chronic pain and disability, relatively little is known about the specific populations of nerve fibers that innervate the skeleton. Recent studies have reported that therapies blocking nerve growth factor (NGF) or its cognate receptor, tropomyosin receptor kinase A (TrkA) are efficacious in attenuating skeletal pain. A potential factor to consider when assessing the analgesic efficacy of targeting NGF-TrkA signaling in a pain state is the fraction of NGF-responsive TrkA+ nociceptors that innervate the tissue from which the pain is arising, as this innervation and the analgesic efficacy of targeting NGF-TrkA signaling may vary considerably from tissue to tissue. To explore this in the skeleton, tissue slices and whole mount preparations of the normal, adult mouse femur were analyzed using immunohistochemistry and confocal microscopy. Analysis of these preparations revealed that 80% of the unmyelinated/thinly myelinated sensory nerve fibers that express calcitonin gene-related peptide (CGRP) and innervate the periosteum, mineralized bone and bone marrow also express TrkA. Similarly, the majority of myelinated sensory nerve fibers that express neurofilament 200 kDa (NF200) which innervate the periosteum, mineralized bone and bone marrow also co-express TrkA. In the normal femur, the relative density of CGRP+, NF200+ and TrkA+ sensory nerve fibers per unit volume is: periosteum>bone marrow>mineralized bone>cartilage with the respective relative densities being 100:2:0.1:0. The observation that the majority of sensory nerve fibers innervating the skeleton express TrkA+, may in part explain why therapies that block NGF/TrkA pathway are highly efficacious in attenuating skeletal pain.
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Affiliation(s)
- G Castañeda-Corral
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
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Andres C, Meyer S, Dina OA, Levine JD, Hucho T. Quantitative automated microscopy (QuAM) elucidates growth factor specific signalling in pain sensitization. Mol Pain 2010; 6:98. [PMID: 21187008 PMCID: PMC3023724 DOI: 10.1186/1744-8069-6-98] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 12/27/2010] [Indexed: 01/19/2023] Open
Abstract
Background Dorsal root ganglia (DRG)-neurons are commonly characterized immunocytochemically. Cells are mostly grouped by the experimenter's eye as "marker-positive" and "marker-negative" according to their immunofluorescence intensity. Classification criteria remain largely undefined. Overcoming this shortfall, we established a quantitative automated microscopy (QuAM) for a defined and multiparametric analysis of adherent heterogeneous primary neurons on a single cell base. The growth factors NGF, GDNF and EGF activate the MAP-kinase Erk1/2 via receptor tyrosine kinase signalling. NGF and GDNF are established factors in regeneration and sensitization of nociceptive neurons. If also the tissue regenerating growth factor, EGF, influences nociceptors is so far unknown. We asked, if EGF can act on nociceptors, and if QuAM can elucidate differences between NGF, GDNF and EGF induced Erk1/2 activation kinetics. Finally, we evaluated, if the investigation of one signalling component allows prediction of the behavioral response to a reagent not tested on nociceptors such as EGF. Results We established a software-based neuron identification, described quantitatively DRG-neuron heterogeneity and correlated measured sample sizes and corresponding assay sensitivity. Analysing more than 70,000 individual neurons we defined neuronal subgroups based on differential Erk1/2 activation status in sensory neurons. Baseline activity levels varied strongly already in untreated neurons. NGF and GDNF subgroup responsiveness correlated with their subgroup specificity on IB4(+)- and IB4(-)-neurons, respectively. We confirmed expression of EGF-receptors in all sensory neurons. EGF treatment induced STAT3 translocation into the nucleus. Nevertheless, we could not detect any EGF induced Erk1/2 phosphorylation. Accordingly, intradermal injection of EGF resulted in a fundamentally different outcome than NGF/GDNF. EGF did not induce mechanical hyperalgesia, but blocked PGE2-induced sensitization. Conclusions QuAM is a suitable if not necessary tool to analyze activation of endogenous signalling in heterogeneous cultures. NGF, GDNF and EGF stimulation of DRG-neurons shows differential Erk1/2 activation responses and a corresponding differential behavioral phenotype. Thus, in addition to expression-markers also signalling-activity can be taken for functional subgroup differentiation and as predictor of behavioral outcome. The anti-nociceptive function of EGF is an intriguing result in the context of tissue damage but also for understanding pain resulting from EGF-receptor block during cancer therapy.
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Affiliation(s)
- Christine Andres
- Department for Molecular Human Genetics, Max Planck Institute for Molecular Genetics, Ihnestrasse 73, Berlin, Germany
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Dib-Hajj SD, Waxman SG. Isoform-specific and pan-channel partners regulate trafficking and plasma membrane stability; and alter sodium channel gating properties. Neurosci Lett 2010; 486:84-91. [DOI: 10.1016/j.neulet.2010.08.077] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 08/25/2010] [Accepted: 08/26/2010] [Indexed: 12/19/2022]
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17
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Nucleus accumbens-derived glial cell line-derived neurotrophic factor is a retrograde enhancer of dopaminergic tone in the mesocorticolimbic system. J Neurosci 2010; 30:14502-12. [PMID: 20980608 DOI: 10.1523/jneurosci.3909-10.2010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Spontaneous firing of ventral tegmental area (VTA) dopamine (DA) neurons provides ambient levels of DA in target areas such as the nucleus accumbens (NAc) and the prefrontal cortex (PFC). Here we report that the glial cell line-derived neurotrophic factor (GDNF), produced in one target region, the NAc, is retrogradely transported by DA neurons to the VTA where the growth factor positively regulates the spontaneous firing activity of both NAc- and PFC-projecting DA neurons in a mechanism that requires the activation of the mitogen-activated protein kinase (MAPK) pathway. We also show that the consequence of GDNF-mediated activation of the MAPK signaling cascade in the VTA is an increase in DA overflow in the NAc. Together, these results demonstrate that NAc-produced GDNF serves as a retrograde enhancer that upregulates the activity of the mesocorticolimbic DA system.
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Groebe K, Hayess K, Klemm-Manns M, Schwall G, Wozny W, Steemans M, Peters AK, Sastri C, Jaeckel P, Stegmann W, Zengerling H, Schöpf R, Poznanovic S, Stummann TC, Seiler A, Spielmann H, Schrattenholz A. Protein Biomarkers for in Vitro Testing of Embryotoxicity. J Proteome Res 2010; 9:5727-38. [DOI: 10.1021/pr100514e] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Karlfried Groebe
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Katrin Hayess
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Martina Klemm-Manns
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Gerhard Schwall
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Woijciech Wozny
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Margino Steemans
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Annelieke K. Peters
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Chaturvedala Sastri
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Petra Jaeckel
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Werner Stegmann
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Helmut Zengerling
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Rainer Schöpf
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Slobodan Poznanovic
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Tina C. Stummann
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Andrea Seiler
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - Horst Spielmann
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
| | - André Schrattenholz
- ProteoSys AG, Carl-Zeiss.-Str. 51, D-55129 Mainz, Germany, Federal Institute for Risk Assessment, Center for Alternative Methods to Animal Experiments - ZEBET Diedersdorfer Weg 1, 12277 Berlin, Germany, Johnson & Johnson PRD, a division of Janssen Pharmaceutical, 2340 Beerse, Belgium, European Centre for the Validation of Alternative Methods (ECVAM) (IHCP, JRC), Via Fermi, 121020 Ispra, Italy
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Epidermal growth factor-mediated proliferation and sodium transport in normal and PKD epithelial cells. Biochim Biophys Acta Mol Basis Dis 2010; 1812:1301-13. [PMID: 20959142 DOI: 10.1016/j.bbadis.2010.10.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 09/30/2010] [Accepted: 10/11/2010] [Indexed: 02/07/2023]
Abstract
Members of the epidermal growth factor (EGF) family bind to ErbB (EGFR) family receptors which play an important role in the regulation of various fundamental cell processes including cell proliferation and differentiation. The normal rodent kidney has been shown to express at least three members of the ErbB receptor family and is a major site of EGF ligand synthesis. Polycystic kidney disease (PKD) is a group of diseases caused by mutations in single genes and is characterized by enlarged kidneys due to the formation of multiple cysts in both kidneys. Tubule cells proliferate, causing segmental dilation, in association with the abnormal deposition of several proteins. One of the first abnormalities described in cell biological studies of PKD pathogenesis was the abnormal mislocalization of the EGFR in cyst lining epithelial cells. The kidney collecting duct (CD) is predominantly an absorptive epithelium where electrogenic Na(+) entry is mediated by the epithelial Na(+) channel (ENaC). ENaC-mediated sodium absorption represents an important ion transport pathway in the CD that might be involved in the development of PKD. A role for EGF in the regulation of ENaC-mediated sodium absorption has been proposed. However, several investigations have reported contradictory results indicating opposite effects of EGF and its related factors on ENaC activity and sodium transport. Recent advances in understanding how proteins in the EGF family regulate the proliferation and sodium transport in normal and PKD epithelial cells are discussed here. This article is part of a Special Issue entitled: Polycystic Kidney Disease.
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ERK1/2 mitogen-activated protein kinase phosphorylates sodium channel Na(v)1.7 and alters its gating properties. J Neurosci 2010; 30:1637-47. [PMID: 20130174 DOI: 10.1523/jneurosci.4872-09.2010] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Na(v)1.7 sodium channels can amplify weak stimuli in neurons and act as threshold channels for firing action potentials. Neurotrophic factors and pro-nociceptive cytokines that are released during development and under pathological conditions activate mitogen-activated protein kinases (MAPKs). Previous studies have shown that MAPKs can transduce developmental or pathological signals by regulating transcription factors that initiate a gene expression response, a long-term effect, and directly modulate neuronal ion channels including sodium channels, thus acutely regulating dorsal root ganglion (DRG) neuron excitability. For example, neurotrophic growth factor activates (phosphorylates) ERK1/2 MAPK (pERK1/2) in DRG neurons, an effect that has been implicated in injury-induced hyperalgesia. However, the acute effects of pERK1/2 on sodium channels are not known. We have shown previously that activated p38 MAPK (pp38) directly phosphorylates Na(v)1.6 and Na(v)1.8 sodium channels and regulates their current densities without altering their gating properties. We now report that acute inhibition of pERK1/2 regulates resting membrane potential and firing properties of DRG neurons. We also show that pERK1 phosphorylates specific residues within L1 of Na(v)1.7, inhibition of pERK1/2 causes a depolarizing shift of activation and fast inactivation of Na(v)1.7 without altering current density, and mutation of these L1 phosphoacceptor sites abrogates the effect of pERK1/2 on this channel. Together, these data are consistent with direct phosphorylation and modulation of Na(v)1.7 by pERK1/2, which unlike the modulation of Na(v)1.6 and Na(v)1.8 by pp38, regulates gating properties of this channel but not its current density and contributes to the effects of MAPKs on DRG neuron excitability.
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Koelsch A, Feng Y, Fink DJ, Mata M. Transgene-mediated GDNF expression enhances synaptic connectivity and GABA transmission to improve functional outcome after spinal cord contusion. J Neurochem 2010; 113:143-52. [PMID: 20132484 DOI: 10.1111/j.1471-4159.2010.06593.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glial cell line-derived trophic factor (GDNF) is a peptide with pleiotropic survival and growth-promoting effects on neurons. We found that intraspinal injection of a non-replicating herpes simplex virus-based vector coding for GDNF 2 h after blunt trauma to the thoraco-lumbar spinal cord produced sustained improvement in motor behavioral outcomes up to 5 weeks following injury. The improvement in behavior correlated with an increase in synaptophysin and glutamic acid decarboxylase (GAD) in the spinal cord at the level of injury. Addition of recombinant GDNF protein to primary spinal cord neurons in-vitro resulted in enhanced neurite growth and a marked increase in protein levels of GAD65 and GAD67, synapsin I and synaptophysin. GDNF-mediated increases in GAD and the synaptic markers were blocked by the MEK inhibitor UO126, but not by the phosphoinositide 3-kinase inhibitor LY294002. These results suggest that GDNF, acting through the MEK-ERK pathway enhances axonal sprouting, synaptic connectivity, and GABAergic neurotransmission in the spinal cord, that result in improved behavioral outcomes after spinal cord contusion injury.
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Affiliation(s)
- Angela Koelsch
- Department of Neurology, University of Michigan and Ann Arbor VA Healthcare System, Ann Arbor, MI, USA
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22
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Copik AJ, Ma C, Kosaka A, Sahdeo S, Trane A, Ho H, Dietrich PS, Yu H, Ford APDW, Button D, Milla ME. Facilitatory interplay in alpha 1a and beta 2 adrenoceptor function reveals a non-Gq signaling mode: implications for diversification of intracellular signal transduction. Mol Pharmacol 2008; 75:713-28. [PMID: 19109357 DOI: 10.1124/mol.108.050765] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Agonist occupied alpha(1)-adrenoceptors (alpha(1)-ARs) engage several signaling pathways, including phosphatidylinositol hydrolysis, calcium mobilization, arachidonic acid release, mitogen-activated protein (MAP) kinase activation, and cAMP accumulation. The natural agonist norepinephrine (NE) activates with variable affinity and intrinsic efficacy all adrenoceptors, and in cells that coexpress alpha(1)- and beta-AR subtypes, such as cardiomyocytes, this leads to coactivation of multiple downstream pathways. This may result in pathway cross-talk with significant consequences to heart physiology and pathologic state. To dissect signaling components involved specifically in alpha(1A)- and beta(2)-AR signal interplay, we have developed a recombinant model system that mimics the levels of receptor expression observed in native cells. We followed intracellular Ca(2+) mobilization to monitor in real time the activation of both G(q) and G(s) pathways. We found that coactivation of alpha(1A)- and beta(2)-AR by the nonselective agonist NE or via a combination of the highly selective alpha(1A)-AR agonist A61603 and the beta-selective agonist isoproterenol led to increases in Ca(2+) influx from the extracellular compartment relative to stimulation with A61603 alone, with no effect on the associated transient release of Ca(2+) from intracellular stores. This effect became more evident upon examination of an alpha(1A)-AR variant exhibiting a partial defect in coupling to G(q), and we attribute it to potentiation of a non G(q)-pathway, uncovered by application of a combination of xestospongin C, an endoplasmic reticulum inositol 1,4,5-triphosphate receptor blocker, and 2-aminoethoxydiphenyl borate, a nonselective storeoperated Ca(2+) entry channel blocker. We also found that stimulation with A61603 of a second alpha(1A)-AR variant entirely unable to signal induced no Ca(2+) unless beta(2)-AR was concomitantly activated. These results may be accounted for by the presence of alpha(1A)/beta(2)-AR heterodimers or alternatively by specific adrenoceptor signal cross-talk resulting in distinct pharmacological behavior. Finally, our findings provide a new conceptual framework to rationalize outcomes from clinical studies targeting alpha- and beta-adrenoceptors.
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Affiliation(s)
- Alicja J Copik
- Inflammation Discovery, Roche Palo Alto, Palo Alto, California, USA
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Ozaki Y, Kitamura N, Tsutsumi A, Dayanithi G, Shibuya I. NGF-induced hyperexcitability causes spontaneous fluctuations of intracellular Ca2+ in rat nociceptive dorsal root ganglion neurons. Cell Calcium 2008; 45:209-15. [PMID: 19027951 DOI: 10.1016/j.ceca.2008.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 10/09/2008] [Accepted: 10/14/2008] [Indexed: 10/21/2022]
Abstract
NGF is a candidate for a pathogenic mediator of neuropathic pain after nerve injury and inflammation. It has been reported that adult rat dorsal root ganglion (DRG) neurons cultured in the presence of NGF at 100 ng/ml generate spontaneous action potentials. However, it is unclear what types of subpopulation of DRG neurons are affected by NGF and how the intracellular Ca(2+) concentration ([Ca(2+)](i)) changes in such neurons. To elucidate these points, we measured [Ca(2+)](i) in adult rat DRG neurons cultured with or without NGF. [Ca(2+)](i) fluctuated spontaneously in the absence of any stimuli in subpopulations of NGF-treated neurons, but such fluctuations were not observed in all NGF-untreated neurons. NGF-induced [Ca(2+)](i) fluctuations were inhibited by decreases in extracellular Na(+) concentration, TTX and Lidocaine, suggesting that spontaneous action potentials provoked the [Ca(2+)](i) fluctuation. NGF-induced [Ca(2+)](i) fluctuation was observed in small and medium sized neurons and in Capsaicin-sensitive neurons more frequently than in Capsaicin-non-responsive neurons. These results suggest that NGF acted on the nociceptive neurons and made them hyperexcitable to generate spontaneous action potentials and spontaneous [Ca(2+)](i) fluctuations. The [Ca(2+)](i) fluctuation induced by NGF may play some role in the regulation of membrane excitability of nociceptive sensory neurons and neuropathic pain.
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Affiliation(s)
- Yui Ozaki
- Department of Veterinary Physiology, Faculty of Agriculture, Tottori University, 101, South 4th, Koyama, Tottori 6808553, Japan
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Xiang Z, Xiong Y, Yan N, Li X, Mao Y, Ni X, He C, LaMotte RH, Burnstock G, Sun J. Functional up-regulation of P2X 3 receptors in the chronically compressed dorsal root ganglion. Pain 2008; 140:23-34. [PMID: 18715715 DOI: 10.1016/j.pain.2008.07.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 06/03/2008] [Accepted: 07/07/2008] [Indexed: 12/20/2022]
Abstract
P2X receptors on dorsal root ganglion (DRG) neurons have been strongly implicated in pathological nociception after peripheral nerve injuries or inflammation. However, nothing is known of a role for purinergic receptors in neuropathic pain produced by a chronic compression of DRG (CCD) - an injury that may accompany an intraforaminal stenosis, a laterally herniated disc or other disorders of the spine leading to radicular pain. In a rat model of DRG compression, hyperexcitable neurons retain functioning axonal connections with their peripheral targets. It is unknown whether such hyperexcitability might enhance chemically mediated nociceptive stimulation of the skin. In this study, CCD facilitated the nocifensive behavior and mechanical hyperalgesia-induced by the P2X 3 agonist, alpha,beta-methylene ATP (alpha,beta-meATP). An injection of alpha,beta-meATP into the hind paw of CCD rats resulted in a significantly greater decrease in the mean threshold to von Frey stimuli and a greater duration of paw lifts than in sham-operated control rats. CCD also increased the levels of P2X 3 receptor protein and the number of P2X 3 immunoreactive, small diameter DRG neurons in the compressed ganglion. P2X 3 receptors were co-labeled with the isolectin IB4, consistent with a role in nociception. In addition, a alpha,beta-meATP induced significantly larger fast-inactivating currents in CCD- than in sham-operated acutely dissociated DRG neurons. These currents were accompanied by the generation of action potentials - but only in the CCD neurons. U0126, a specific inhibitor of the MEK1/2, greatly down-regulated the enhanced current. Taken together, these observations suggest that enhanced purinergic responses after CCD are mediated by P2X 3 receptors.
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Affiliation(s)
- Zhenghua Xiang
- Department of Physiology, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, PR China Department of Neurobiology, Second Military Medical University, Shanghai 200433, PR China Department of Anesthesiology, Changhai Hospital, Second Military Medical University, Shanghai 200433, PR China Key Laboratory of Molecular Neurobiology, Ministry of Education, Second Military Medical University, Shanghai 200433, PR China Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510, USA Autonomic Neuroscience Centre, Royal Free and University College Medical School, Rowland Hill Street, London NW3 2PF, UK
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25
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Fraser SP, Pardo LA. Ion channels: functional expression and therapeutic potential in cancer. Colloquium on Ion Channels and Cancer. EMBO Rep 2008; 9:512-5. [PMID: 18451877 DOI: 10.1038/embor.2008.75] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Accepted: 04/11/2008] [Indexed: 12/27/2022] Open
Affiliation(s)
- Scott P Fraser
- Neuroscience Solutions to Cancer Research Group, Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, UK.
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