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Zhang Z, Sun GY, Ding S. Glial Cell Line-Derived Neurotrophic Factor and Focal Ischemic Stroke. Neurochem Res 2021; 46:2638-2650. [PMID: 33591443 DOI: 10.1007/s11064-021-03266-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 11/29/2022]
Abstract
Focal ischemic stroke (FIS) is a leading cause of human debilitation and death. Following the onset of a FIS, the brain experiences a series of spatiotemporal changes which are exemplified in different pathological processes. One prominent feature of FIS is the development of reactive astrogliosis and glial scar formation in the peri-infarct region (PIR). During the subacute phase, astrocytes in PIR are activated, referred to as reactive astrocytes (RAs), exhibit changes in morphology (hypotrophy), show an increased proliferation capacity, and altered gene expression profile, a phenomenon known as reactive astrogliosis. Subsequently, the morphology of RAs remains stable, and proliferation starts to decline together with the formation of glial scars. Reactive astrogliosis and glial scar formation eventually cause substantial tissue remodeling and changes in permanent structure around the PIR. Glial cell line-derived neurotrophic factor (GDNF) was originally isolated from a rat glioma cell-line and regarded as a potent survival neurotrophic factor. Under normal conditions, GDNF is expressed in neurons but is upregulated in RAs after FIS. This review briefly describes properties of GDNF, its receptor-mediated signaling pathways, as well as recent studies regarding the role of RAs-derived GDNF in neuronal protection and brain recovery. These results provide evidence suggesting an important role of RA-derived GDNF in intrinsic brain repair and recovery after FIS, and thus targeting GDNF in RAs may be effective for stroke therapy.
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Affiliation(s)
- Zhe Zhang
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO, 65211, USA.,Department of Biomedical, Biological and Chemical Engineering, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | - Grace Y Sun
- Department of Biochemistry, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | - Shinghua Ding
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO, 65211, USA. .,Department of Biomedical, Biological and Chemical Engineering, University of Missouri-Columbia, Columbia, MO, 65211, USA. .,Dalton Cardiovascular Research Center, Department of Biomedical, Biological and Chemical Engineering, University of Missouri-Columbia, 134 Research Park Drive, Columbia, MO, 65211, USA.
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Abstract
Neurotrophin-3 (NT-3) belongs to a family of growth factors called neurotrophins whose actions are centered in the nervous system. NT-3 is structurally related to other neurotrophins like brain-derived neurotrophic factor. The expression of NT-3 starts with the onset of neurogenesis and continues throughout life. A wealth of information links NT-3 to the growth, differentiation, and survival of hippocampal cells as well as sympathetic and sensory neurons. These studies have described the distribution of NT-3 and its receptors throughout development and in the mature nervous system. Prior works has begun to cell-type specific impact of NT-3 as well as identify the signaling pathways involved. However, much less is known about how NT-3 regulates synaptic transmission. This chapter focuses role of NT-3 in the modulation of synaptic transmission.
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3
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Wang J, Gao X, Wang Y, Wang M, Ge C, Liu Z, Xie XE, Chen Z, Song J, Lu C. The physiological modulation by intracellular kinases of hippocampal γ-oscillation in vitro. Am J Physiol Cell Physiol 2020; 318:C879-C888. [PMID: 32023074 DOI: 10.1152/ajpcell.00199.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Hippocampal network oscillations at gamma frequency band (γ-oscillation, 20-80 Hz) are synchronized synaptic activities generated by the interactions between the excitatory and inhibitory interneurons and are associated with higher brain function such as learning and memory. Despite extensive studies about the modulation of intracellular kinases on synaptic transmission and plasticity, little is known about the effects of these kinases on γ-oscillations. In this study, we examined the effects of several critical intracellular kinases such as cyclic AMP-dependent protein kinase (PKA), protein kinase B (PKB)/Akt, protein kinase C (PKC), extracellular-regulated protein kinases (ERK) and AMP-activated protein kinase (AMPK), known to regulate synaptic transmission, on hippocampal γ-oscillations in vitro. We found that AMPK inhibitor but not PKA, PKC, or ERK inhibitor, strongly enhanced the power of γ-oscillation (γ-power) and that Akt inhibitor weakly increased γ-power. Western blot analysis confirmed that AMPK inhibitor reduced the expression of p-AMPK but not total AMPK. By using the slice whole cell voltage-clamp technique, we found that AMPK inhibitor increased the frequency but not amplitude of spontaneous inhibitory postsynaptic currents (sIPSC) and had no effect on either frequency or amplitude of spontaneous excitatory postsynaptic currents (sEPSC). Therefore, AMPK activation negatively modulates hippocampal γ-oscillation via modulation of the inhibitory neurons.
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Affiliation(s)
- JianGang Wang
- International Joint Lab of Noninvasive Neural Modulation of Henan Province, Department of Neurobiology and Physiology, Xinxiang Medical University, Xinxiang, China.,Department of Pathophysiology, Xinxiang Medical University, Xinxiang, China.,Henan Key Laboratory of Neurorestoratology, The first Affiliated Hospital of Xinxiang Medical University, Xinxiang, Henan, People's Republic of China.,The Second Affiliated Hospital of Xinxiang Medical University, Henan Key Laboratory of Biological Psychiatry, Xinxiang Medical University, Xinxiang, People's Republic of China
| | - XiaHuan Gao
- International Joint Lab of Noninvasive Neural Modulation of Henan Province, Department of Neurobiology and Physiology, Xinxiang Medical University, Xinxiang, China.,Department of Pathophysiology, Xinxiang Medical University, Xinxiang, China
| | - YaLi Wang
- International Joint Lab of Noninvasive Neural Modulation of Henan Province, Department of Neurobiology and Physiology, Xinxiang Medical University, Xinxiang, China
| | - MengMeng Wang
- International Joint Lab of Noninvasive Neural Modulation of Henan Province, Department of Neurobiology and Physiology, Xinxiang Medical University, Xinxiang, China
| | - ChunBo Ge
- International Joint Lab of Noninvasive Neural Modulation of Henan Province, Department of Neurobiology and Physiology, Xinxiang Medical University, Xinxiang, China
| | - ZhiHua Liu
- International Joint Lab of Noninvasive Neural Modulation of Henan Province, Department of Neurobiology and Physiology, Xinxiang Medical University, Xinxiang, China
| | - Xin-E Xie
- International Joint Lab of Noninvasive Neural Modulation of Henan Province, Department of Neurobiology and Physiology, Xinxiang Medical University, Xinxiang, China
| | - ZhengYue Chen
- International Joint Lab of Noninvasive Neural Modulation of Henan Province, Department of Neurobiology and Physiology, Xinxiang Medical University, Xinxiang, China.,Department of Pathophysiology, Xinxiang Medical University, Xinxiang, China
| | - JingGui Song
- The Second Affiliated Hospital of Xinxiang Medical University, Henan Key Laboratory of Biological Psychiatry, Xinxiang Medical University, Xinxiang, People's Republic of China
| | - ChengBiao Lu
- International Joint Lab of Noninvasive Neural Modulation of Henan Province, Department of Neurobiology and Physiology, Xinxiang Medical University, Xinxiang, China.,Department of Pathophysiology, Xinxiang Medical University, Xinxiang, China
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Di Liberto V, Mudò G, Belluardo N. Crosstalk between receptor tyrosine kinases (RTKs) and G protein-coupled receptors (GPCR) in the brain: Focus on heteroreceptor complexes and related functional neurotrophic effects. Neuropharmacology 2018; 152:67-77. [PMID: 30445101 DOI: 10.1016/j.neuropharm.2018.11.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 11/01/2018] [Accepted: 11/12/2018] [Indexed: 01/11/2023]
Abstract
Neuronal events are regulated by the integration of several complex signaling networks in which G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs) are considered key players of an intense bidirectional cross-communication in the cell, generating signaling mechanisms that, at the same time, connect and diversify the traditional signal transduction pathways activated by the single receptor. For this receptor-receptor crosstalk, the two classes of receptors form heteroreceptor complexes resulting in RTKs transactivation and in growth-promoting signals. In this review, we describe heteroreceptor complexes between GPCR and RTKs in the central nervous system (CNS) and their functional effects in controlling a variety of neuronal effects, ranging from development, proliferation, differentiation and migration, to survival, repair, synaptic transmission and plasticity. In this interaction, RTKs can also recruit components of the G protein signaling cascade, creating a bidirectional intricate interplay that provides complex control over multiple cellular events. These heteroreceptor complexes, by the integration of different signals, have recently attracted a growing interest as novel molecular target for depressive disorders. This article is part of the Special Issue entitled 'Receptor heteromers and their allosteric receptor-receptor interactions'.
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Affiliation(s)
- Valentina Di Liberto
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Palermo, Italy
| | - Giuseppa Mudò
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Palermo, Italy
| | - Natale Belluardo
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Palermo, Italy.
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5
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Lai BQ, Che MT, Du BL, Zeng X, Ma YH, Feng B, Qiu XC, Zhang K, Liu S, Shen HY, Wu JL, Ling EA, Zeng YS. Transplantation of tissue engineering neural network and formation of neuronal relay into the transected rat spinal cord. Biomaterials 2016; 109:40-54. [DOI: 10.1016/j.biomaterials.2016.08.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 07/13/2016] [Accepted: 08/02/2016] [Indexed: 12/24/2022]
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Pramanik S, Sulistio YA, Heese K. Neurotrophin Signaling and Stem Cells-Implications for Neurodegenerative Diseases and Stem Cell Therapy. Mol Neurobiol 2016; 54:7401-7459. [PMID: 27815842 DOI: 10.1007/s12035-016-0214-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 10/11/2016] [Indexed: 02/07/2023]
Abstract
Neurotrophins (NTs) are members of a neuronal growth factor protein family whose action is mediated by the tropomyosin receptor kinase (TRK) receptor family receptors and the p75 NT receptor (p75NTR), a member of the tumor necrosis factor (TNF) receptor family. Although NTs were first discovered in neurons, recent studies have suggested that NTs and their receptors are expressed in various types of stem cells mediating pivotal signaling events in stem cell biology. The concept of stem cell therapy has already attracted much attention as a potential strategy for the treatment of neurodegenerative diseases (NDs). Strikingly, NTs, proNTs, and their receptors are gaining interest as key regulators of stem cells differentiation, survival, self-renewal, plasticity, and migration. In this review, we elaborate the recent progress in understanding of NTs and their action on various stem cells. First, we provide current knowledge of NTs, proNTs, and their receptor isoforms and signaling pathways. Subsequently, we describe recent advances in the understanding of NT activities in various stem cells and their role in NDs, particularly Alzheimer's disease (AD) and Parkinson's disease (PD). Finally, we compile the implications of NTs and stem cells from a clinical perspective and discuss the challenges with regard to transplantation therapy for treatment of AD and PD.
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Affiliation(s)
- Subrata Pramanik
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Republic of Korea
| | - Yanuar Alan Sulistio
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Republic of Korea
| | - Klaus Heese
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Republic of Korea.
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7
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Mizui T, Ishikawa Y, Kumanogoh H, Kojima M. Neurobiological actions by three distinct subtypes of brain-derived neurotrophic factor: Multi-ligand model of growth factor signaling. Pharmacol Res 2015; 105:93-8. [PMID: 26747403 DOI: 10.1016/j.phrs.2015.12.019] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 12/19/2015] [Indexed: 01/20/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) is one of the most active members of the neurotrophin family. BDNF not only regulates neuronal survival and differentiation, but also functions in activity-dependent plasticity processes such as long-term potentiation (LTP), long-term depression (LTD), learning, and memory. Like other growth factors, BDNF is produced by molecular and cellular mechanisms including transcription and translation, and functions as a bioactive molecule in the nervous system. Among these mechanisms, a particular post-translational mechanism, namely the conversion of precursor BDNF into mature BDNF by proteolytic cleavage, was not fully understood. In this review, we discuss the manner through which this post-translational mechanism alters the biological actions of BDNF protein. In addition to the initially elucidated findings on BDNF, the biological roles of precursor BDNF and the BDNF pro-peptide, especially synaptic plasticity, will be extensively discussed. Recent findings on the BDNF pro-peptide will provide new insights for understanding the mechanisms of action of the pro-peptides of growth factors.
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Affiliation(s)
- Toshiyuki Mizui
- Biomedical Research Institute, Advanced Industrial Science and Technology (AIST), Osaka 563-8577, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan.
| | - Yasuyuki Ishikawa
- Department of Systems Life Engineering, Maebashi Institute of Technology, Gunma 371-0816, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
| | - Haruko Kumanogoh
- Biomedical Research Institute, Advanced Industrial Science and Technology (AIST), Osaka 563-8577, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
| | - Masami Kojima
- Biomedical Research Institute, Advanced Industrial Science and Technology (AIST), Osaka 563-8577, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan.
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Hu JG, Wu XJ, Feng YF, Xi GM, Deng LX, Wang ZH, Wang R, Shen L, Zhou JS, Lü HZ. The molecular events involved in oligodendrocyte precursor cell proliferation induced by the conditioned medium from b104 neuroblastoma cells. Neurochem Res 2013; 38:601-9. [PMID: 23283697 DOI: 10.1007/s11064-012-0957-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 11/28/2012] [Accepted: 12/19/2012] [Indexed: 11/29/2022]
Abstract
The conditioned medium from B104 neuroblastoma cells (B104CM) induces proliferation of oligodendrocyte progenitor cells (OPCs) in vitro. However, the molecular events that occur during B104CM-induced proliferation of OPCs has not been well clarified. In the present study, using OPCs immunopanned from embryonic day 14 Sprague-Dawley rat spinal cords, we explored the activation of several signaling pathways and the expression of several important immediate early genes (IEGs) and cyclins in OPCs in response to B104CM. We found that B104CM can induce OPC proliferation through the activation of the extracellular signal-regulated kinases 1 and 2 (Erk1/2), but not PI3K or p38 MAPK signaling pathways in vitro. The IEGs involved in B104CM-induced OPC proliferation include c-fos, c-jun and Id2, but not c-myc, fyn, or p21. The cyclins D1, D2 and E are also involved in B104CM-stimulated proliferation of OPCs. The activation of Erk results in subsequent expression of IEGs (such as c-fos, c-jun and Id-2) and cyclins (including cyclin D1, D2 and E), which play key roles in cell cycle initiation and OPC proliferation. Collectively, these results suggest that the phosphorylation of Erk1/2 is an important molecular event during OPC proliferation induced by B104CM.
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Affiliation(s)
- Jian-Guo Hu
- Department of Clinical Laboratory Science, The First Affiliated Hospital of Bengbu Medical College, 287 Chang Huai Road, Bengbu, 233004, People's Republic of China
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9
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Jang HJ, Yang YR, Kim JK, Choi JH, Seo YK, Lee YH, Lee JE, Ryu SH, Suh PG. Phospholipase C-γ1 involved in brain disorders. Adv Biol Regul 2013; 53:51-62. [PMID: 23063587 DOI: 10.1016/j.jbior.2012.09.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Revised: 09/11/2012] [Accepted: 09/11/2012] [Indexed: 06/01/2023]
Abstract
Phosphoinositide-specific phospholipase C-γ1 (PLC-γ1) is an important signaling regulator involved in various cellular processes. In brain, PLC-γ1 is highly expressed and participates in neuronal cell functions mediated by neurotrophins. Consistent with essential roles of PLC-γ1, it is involved in development of brain and synaptic transmission. Significantly, abnormal expression and activation of PLC-γ1 appears in various brain disorders such as epilepsy, depression, Huntington's disease and Alzheimer's disease. Thus, PLC-γ1 has been implicated in brain functions as well as related brain disorders. In this review, we discuss the roles of PLC-γ1 in neuronal functions and its pathological relevance to diverse brain diseases.
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Affiliation(s)
- Hyun-Jun Jang
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 689-798, Republic of Korea
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10
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Aoyagi K, Ohara-Imaizumi M, Nishiwaki C, Nakamichi Y, Ueki K, Kadowaki T, Nagamatsu S. Acute inhibition of PI3K-PDK1-Akt pathway potentiates insulin secretion through upregulation of newcomer granule fusions in pancreatic β-cells. PLoS One 2012; 7:e47381. [PMID: 23077605 PMCID: PMC3471824 DOI: 10.1371/journal.pone.0047381] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 09/12/2012] [Indexed: 02/03/2023] Open
Abstract
In glucose-induced insulin secretion from pancreatic β-cells, a population of insulin granules fuses with the plasma membrane without the typical docking process (newcomer granule fusions), however, its mechanism is unclear. In this study, we investigated the PI3K signaling pathways involved in the upregulation of newcomer granule fusions. Acute treatment with the class IA-selective PI3K inhibitors, PIK-75 and PI-103, enhanced the glucose-induced insulin secretion. Total internal reflection fluorescent microscopy revealed that the PI3K inhibitors increased the fusion events from newcomer granules. We developed a new system for transfection into pancreatic islets and demonstrated the usefulness of this system in order for evaluating the effect of transfected genes on the glucose-induced secretion in primary cultured pancreatic islets. Using this transfection system together with a series of constitutive active mutants, we showed that the PI3K-3-phosphoinositide dependent kinase-1 (PDK1)-Akt pathway mediated the potentiation of insulin secretion. The Akt inhibitor also enhanced the glucose-induced insulin secretion in parallel with the upregulation of newcomer granule fusions, probably via increased motility of intracellular insulin granules. These data suggest that the PI3K-PDK1-Akt pathway plays a significant role in newcomer granule fusions, probably through an alteration of the dynamics of the intracellular insulin granules.
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Affiliation(s)
- Kyota Aoyagi
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
| | - Mica Ohara-Imaizumi
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
| | - Chiyono Nishiwaki
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
| | - Yoko Nakamichi
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
| | - Kohjiro Ueki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Takashi Kadowaki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Shinya Nagamatsu
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
- * E-mail:
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11
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TRPC5 channel is the mediator of neurotrophin-3 in regulating dendritic growth via CaMKIIα in rat hippocampal neurons. J Neurosci 2012; 32:9383-95. [PMID: 22764246 DOI: 10.1523/jneurosci.6363-11.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Neurotrophin-3 (NT-3) plays numerous important roles in the CNS and the elevation of intracellular Ca(2+) ([Ca(2+)](i)) is critical for these functions of NT-3. However, the mechanism by which NT-3 induces [Ca(2+)](i) elevation remains largely unknown. Here, we found that transient receptor potential canonical (TRPC) 5 protein and TrkC, the NT-3 receptor, exhibited a similar temporal expression in rat hippocampus and cellular colocalization in hippocampal neurons. Stimulation of the neurons by NT-3 induced a nonselective cation conductance and PLCγ-dependent [Ca(2+)](i) elevation, which were both blocked when TRPC5, but not TRPC6 channels, were inhibited. Moreover, the Ca(2+) influx through TRPC5 induced by NT-3 inhibited the neuronal dendritic growth through activation of calmodulin-dependent kinase (CaMK) IIα. In contrast, the Ca(2+) influx through TRPC6 induced by NT-4 promoted the dendritic growth. Thus, TRPC5 acts as a novel and specific mediator for NT-3 to regulate dendrite development through CaMKIIα.
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Li Voti P, Conte A, Suppa A, Iezzi E, Bologna M, Aniello MS, Defazio G, Rothwell JC, Berardelli A. Correlation between cortical plasticity, motor learning and BDNF genotype in healthy subjects. Exp Brain Res 2011; 212:91-9. [PMID: 21537966 DOI: 10.1007/s00221-011-2700-5] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 04/15/2011] [Indexed: 01/16/2023]
Abstract
There is good evidence that synaptic plasticity in human motor cortex is involved in behavioural motor learning; in addition, it is now possible to probe mechanisms of synaptic plasticity using a variety of transcranial brain-stimulation protocols. Interactions between these protocols suggest that they both utilise common mechanisms. The aim of the present experiments was to test how well responsiveness to brain-stimulation protocols and behavioural motor learning correlate with each other in a sample of 21 healthy volunteers. We also examined whether any of these measures were influenced by the presence of a Val66Met polymorphism in the BDNF gene since this is another factor that has been suggested to be able to predict response to tests of synaptic plasticity. In 3 different experimental sessions, volunteers underwent 5-Hz rTMS, intermittent theta-burst stimulation (iTBS) and a motor learning task. Blood samples were collected from each subject for BDNF genotyping. As expected, both 5-Hz rTMS and iTBS significantly facilitated MEPs. Similarly, as expected, kinematic variables of finger movement significantly improved during the motor learning task. Although there was a significant correlation between the effect of iTBS and 5-Hz rTMS, there was no relationship in each subject between the amount of TMS-induced plasticity and the increase in kinematic variables during motor learning. Val66Val and Val66Met carriers did not differ in their response to any of the protocols. The present results emphasise that although some TMS measures of cortical plasticity may correlate with each other, they may not always relate directly to measures of behavioural learning. Similarly, presence of the Val66Met BDNF polymorphism also does not reliably predict responsiveness in small groups of individuals. Individual success in behavioural learning is unlikely to be closely related to any single measure of synaptic plasticity.
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Affiliation(s)
- P Li Voti
- Department of Neurology and Psychiatry, Sapienza, University of Rome, Viale dell'Università 30, 00185, Rome, Italy
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Abstract
Autism spectrum disorders (ASDs) are pervasive developmental disorders that frequently involve a triad of deficits in social skills, communication and language. For the underlying neurobiology of these symptoms, disturbances in neuronal development and synaptic plasticity have been discussed. The physiological development, regulation and survival of specific neuronal populations shaping neuronal plasticity require the so-called 'neurotrophic factors' (NTFs). These regulate cellular proliferation, migration, differentiation and integrity, which are also affected in ASD. Therefore, NTFs have gained increasing attention in ASD research. This review provides an overview and explores the key role of NTFs in the aetiology of ASD. We have also included evidence derived from neurochemical investigations, gene association studies and animal models. By focussing on the role of NTFs in ASD, we intend to further elucidate the puzzling aetiology of these conditions.
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Affiliation(s)
- T Nickl-Jockschat
- Department of Psychiatry and Psychotherapy, RWTH Aachen University, Aachen, Germany
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14
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Rogers RC, McDougal DH, Hermann GE. Leptin amplifies the action of thyrotropin-releasing hormone in the solitary nucleus: an in vitro calcium imaging study. Brain Res 2011; 1385:47-55. [PMID: 21334313 DOI: 10.1016/j.brainres.2011.02.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 02/11/2011] [Accepted: 02/11/2011] [Indexed: 12/28/2022]
Abstract
Leptin exerts a powerful permissive influence on neurogenic thermogenesis. During starvation and an absence of leptin, animals cannot produce thermogenic reactions to cold stress. However, thermogenesis is rescued by restoring leptin. We have previously observed a highly cooperative interaction between leptin and thyrotropin-releasing hormone [TRH] to activate hindbrain-generated thermogenic responses (Hermann et al., 2006). In vivo physiological studies (Rogers et al., 2009) suggested that the thermogenic impact of TRH in the hindbrain is amplified by the action of leptin through a leptin receptor-mediated production of phosphoinositol-trisphosphate [PIP3]. In turn, PIP3 can activate a tyrosine kinase whose target is the Src-SH2 regulatory site on the phospholipase C [PLC] complex. The TRH receptor signals through the PLC complex. Our immunohistochemical studies (Barnes et al., 2010) suggest that this transduction interaction between leptin and TRH occurs within neurons of the solitary nucleus [NST], though this interaction had not been verified. The present in vitro live cell calcium imaging study shows that while medial NST neurons are rarely activated by leptin alone, leptin pre-treatment significantly augments NST neurons' responsiveness to TRH. This leptin-mediated priming of NST neurons was uncoupled by pre-treatment with the phosphoinositide 3-kinase [PI3K] inhibitor [wortmannin], the phospholipase C inhibitor [U73122] and the Src-SH2 antagonist [PP2]. TTX did not eliminate the synergistic response of the agonists, thus the sensitization cannot be attributed to pre-synaptic mechanisms. It seems likely that NST neurons are involved in the leptin-mediated increase in BAT temperature by sensitizing the TRH-PLC-IP3-calcium release mechanism.
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Affiliation(s)
- Richard C Rogers
- Laboratory of Autonomic Neurosciences, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
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Je HS, Ji Y, Wang Y, Yang F, Wu W, Lu B. Presynaptic protein synthesis required for NT-3-induced long-term synaptic modulation. Mol Brain 2011; 4:1. [PMID: 21211057 PMCID: PMC3023743 DOI: 10.1186/1756-6606-4-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Accepted: 01/07/2011] [Indexed: 12/05/2022] Open
Abstract
Background Neurotrophins elicit both acute and long-term modulation of synaptic transmission and plasticity. Previously, we demonstrated that the long-term synaptic modulation requires the endocytosis of neurotrophin-receptor complex, the activation of PI3K and Akt, and mTOR mediated protein synthesis. However, it is unclear whether the long-term synaptic modulation by neurotrophins depends on protein synthesis in pre- or post-synaptic cells. Results Here we have developed an inducible protein translation blocker, in which the kinase domain of protein kinase R (PKR) is fused with bacterial gyrase B domain (GyrB-PKR), which could be dimerized upon treatment with a cell permeable drug, coumermycin. By genetically targeting GyrB-PKR to specific cell types, we show that NT-3 induced long-term synaptic modulation requires presynaptic, but not postsynaptic protein synthesis. Conclusions Our results provide mechanistic insights into the cell-specific requirement for protein synthesis in the long-term synaptic modulation by neurotrophins. The GyrB-PKR system may be useful tool to study protein synthesis in a cell-specific manner.
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Affiliation(s)
- H Shawn Je
- Genes, Cognition and Psychosis Program (GCAP), National Institute of Mental Health/NIH, Bethesda, MD 20892, U.S.A
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Finsterwald C, Fiumelli H, Cardinaux JR, Martin JL. Regulation of dendritic development by BDNF requires activation of CRTC1 by glutamate. J Biol Chem 2010; 285:28587-95. [PMID: 20639200 DOI: 10.1074/jbc.m110.125740] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dendritic growth is essential for the establishment of a functional nervous system. Among extrinsic signals that control dendritic development, substantial evidence indicates that BDNF regulates dendritic morphology. However, little is known about the underlying mechanisms by which BDNF controls dendritic growth. In this study, we show that the MAPK signaling pathway and the transcription factor cAMP response element-binding protein (CREB) mediate the effects of BDNF on dendritic length and complexity. However, phosphorylation of CREB alone is not sufficient for the stimulation of dendritic growth by BDNF. Thus, using a mutant form of CREB unable to bind CREB-regulated transcription coactivator (CRTC1), we demonstrate that this effect also requires a functional interaction between CREB and CRTC1. Moreover, inhibition of CRTC1 expression by shRNA-mediated knockdown abolished BDNF-induced dendritic growth of cortical neurons. Interestingly, we found that nuclear translocation of CRTC1 results from activation of NMDA receptors by glutamate, a process that is essential for the effects of BDNF on dendritic development. Together, these data identify a previously unrecognized mechanism by which CREB and the coactivator CRTC1 mediate the effects of BDNF on dendritic growth.
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Affiliation(s)
- Charles Finsterwald
- Department of Physiology, University of Lausanne, CH-1005 Lausanne, Switzerland
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17
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Cytoplasmic polyadenylation element-binding protein regulates neurotrophin-3-dependent beta-catenin mRNA translation in developing hippocampal neurons. J Neurosci 2009; 29:13630-9. [PMID: 19864575 DOI: 10.1523/jneurosci.2910-08.2009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neuronal morphogenesis, the growth and arborization of neuronal processes, is an essential component of brain development. Two important but seemingly disparate components regulating neuronal morphology have previously been described. In the hippocampus, neurotrophins, particularly brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT3), act to enhance cell growth and branching, while activity-induced branching was shown to be dependent upon intracellular beta-catenin. We now describe a molecular link between NT3 stimulation and beta-catenin increase in developing neurons and demonstrate that this process is required for the NT3-mediated increase in process branching. Here, we show that beta-catenin is rapidly increased specifically in growth cones following NT3 stimulation. This increase in beta-catenin is protein synthesis dependent and requires the activity of cytoplasmic polyadenylation element-binding protein-1 (CPEB1), an mRNA-binding protein that regulates mRNA translation. We find that CPEB1 protein binds beta-catenin mRNA in a CPE-dependent manner and that both localize to growth cones of developing hippocampal neurons. Both the NT3-mediated rapid increase in beta-catenin and process branching are abolished when CPEB1 function is inhibited. In addition, the NT3-mediated increase in beta-catenin in growth cones is dependent upon internal calcium and the activity of CaMKII (calcium/calmodulin-dependent kinase II). Together, these results suggest that CPEB1 regulates beta-catenin synthesis in neurons and may contribute to neuronal morphogenesis.
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Leptin "gates" thermogenic action of thyrotropin-releasing hormone in the hindbrain. Brain Res 2009; 1295:135-41. [PMID: 19643094 DOI: 10.1016/j.brainres.2009.07.063] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 07/16/2009] [Accepted: 07/18/2009] [Indexed: 12/19/2022]
Abstract
Leptin, acting as a measure of metabolic fuel availability, exerts a powerful permissive influence on neurogenic thermogenesis. During starvation and an absence of leptin, animals cannot produce thermogenic reactions to cold stress. However, thermogenesis is rescued by restoring leptin. We have previously observed (Hermann, G.E., Barnes, M.J., Rogers, R.C., 2006. Leptin and thyrotropin-releasing hormone: cooperative action in the hindbrain to activate brown adipose thermogenesis. Brain Res. 1117, 118-124.) a highly cooperative interaction between leptin and thyrotropin-releasing hormone [TRH] to activate hindbrain generated thermogenic responses. Specifically, exposure to both leptin and TRH elicited a 3.5 degrees C increase in brown adipose tissue [BAT] thermogenesis, while leptin alone did not evoke any change, and TRH alone caused only approximately 1 degrees C increase. The present study shows that the leptin-TRH synergy in controlling brown adipose [BAT] thermogenesis is order-specific and dependent on the feeding status of the animal. That is, fourth ventricular [4V] application of leptin to the food-deprived animal, before TRH injection, yields a substantial increase in BAT; while the reverse order yields a significantly smaller effect. If the animal were fed within minutes of anesthesia, then exogenous leptin was not necessary for TRH to yield a large increase in BAT temperature. The leptin-TRH synergy was uncoupled by pretreatment with the phosphoinositol-tris phosphate kinase [PI3K] inhibitor, wortmannin and the Src-SH2 antagonist, PP2. The TRH transduction mechanism utilizes phospholipase C [PLC] potently regulated by the SH2 site. Previous work in culture systems suggests that the product of PI3K activity [PIP3] potently upregulates PLC by activating the SH2 domain of the PLC complex. Perhaps leptin "gates" the thermogenic action of TRH in the hindbrain by invoking this same mechanism.
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Yang F, Je HS, Ji Y, Nagappan G, Hempstead B, Lu B. Pro-BDNF-induced synaptic depression and retraction at developing neuromuscular synapses. ACTA ACUST UNITED AC 2009; 185:727-41. [PMID: 19451278 PMCID: PMC2711569 DOI: 10.1083/jcb.200811147] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Postsynaptic cells generate positive and negative signals that retrogradely modulate presynaptic function. At developing neuromuscular synapses, prolonged stimulation of muscle cells induces sustained synaptic depression. We provide evidence that pro-brain-derived neurotrophic factor (BDNF) is a negative retrograde signal that can be converted into a positive signal by metalloproteases at the synaptic junctions. Application of pro-BDNF induces a dramatic decrease in synaptic efficacy followed by a retraction of presynaptic terminals, and these effects are mediated by presynaptic pan-neurotrophin receptor p75 (p75(NTR)), the pro-BDNF receptor. A brief stimulation of myocytes expressing cleavable or uncleavable pro-BDNF elicits synaptic potentiation or depression, respectively. Extracellular application of metalloprotease inhibitors, which inhibits the cleavage of endogenous pro-BDNF, facilitates the muscle stimulation-induced synaptic depression. Inhibition of presynaptic p75(NTR) or postsynaptic BDNF expression also blocks the activity-dependent synaptic depression and retraction. These results support a model in which postsynaptic secretion of a single molecule, pro-BDNF, may stabilize or eliminate presynaptic terminals depending on its proteolytic conversion at the synapses.
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Affiliation(s)
- Feng Yang
- Section on Neural Development and Plasticity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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20
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Mantilla CB, Sieck GC. Trophic factor expression in phrenic motor neurons. Respir Physiol Neurobiol 2009; 164:252-62. [PMID: 18708170 DOI: 10.1016/j.resp.2008.07.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 07/16/2008] [Accepted: 07/21/2008] [Indexed: 01/08/2023]
Abstract
The function of a motor neuron and the muscle fibers it innervates (i.e., a motor unit) determines neuromotor output. Unlike other skeletal muscles, respiratory muscles (e.g., the diaphragm, DIAm) must function from birth onwards in sustaining ventilation. DIAm motor units are capable of both ventilatory and non-ventilatory behaviors, including expulsive behaviors important for airway clearance. There is significant diversity in motor unit properties across different types of motor units in the DIAm. The mechanisms underlying the development and maintenance of motor unit diversity in respiratory muscles (including the DIAm) are not well understood. Recent studies suggest that trophic factor influences contribute to this diversity. Remarkably little is known about the expression of trophic factors and their receptors in phrenic motor neurons. This review will focus on the contribution of trophic factors to the establishment and maintenance of motor unit diversity in the DIAm, during development and in response to injury or disease.
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Affiliation(s)
- Carlos B Mantilla
- Department of Anesthesiology, Mayo Clinic, 4-184 W. Joseph SMH, 200 First St SW, Rochester, MN 55905, USA.
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Zheng F, Soellner D, Nunez J, Wang H. The basal level of intracellular calcium gates the activation of phosphoinositide 3-kinase-Akt signaling by brain-derived neurotrophic factor in cortical neurons. J Neurochem 2008; 106:1259-74. [PMID: 18485103 DOI: 10.1111/j.1471-4159.2008.05478.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) mediates survival and neuroplasticity through the activation of phosphoinositide 3-kinase-Akt pathway. Although previous studies suggested the roles of mitogen-activated protein kinase, phospholipase C-gamma-mediated intracellular calcium ([Ca2+]i) increase, and extracellular calcium influx in regulating Akt activation, the cellular mechanisms are largely unknown. We demonstrated that sub-nanomolar BDNF significantly induced Akt activation in developing cortical neurons. The TrkB-dependent Akt phosphorylation at S473 and T308 required only phosphoinositide 3-kinase, but not phospholipase C and mitogen-activated protein kinase activity. Blocking NMDA receptors, L-type voltage-gated calcium channels, and chelating extracellular calcium by EGTA failed to block BDNF-induced Akt phosphorylation. In contrast, chelating [Ca2+]i by 1,2-bis(o-aminophenoxy)ethane-N,N,N ',N '-tetraacetic acid-acetoxymethyl ester (BAPTA-AM) abolished Akt phosphorylation. Interestingly, sub-nanomolar BDNF did not stimulate [Ca2+]i increase under our culture conditions. Together with that NMDA- and membrane depolarization-induced [Ca2+]i increase did not activate Akt, we conclude that the basal level of [Ca2+]i gates BDNF function. Furthermore, inhibiting calmodulin by W13 suppressed Akt phosphorylation. On the other hand, inhibition of protein phosphatase 1 by okadaic acid and tautomycin rescued Akt phosphorylation in BAPTA-AM and W13-treated neurons. We further demonstrated that the phosphorylation of phosphoinositide-dependent kinase-1 did not correlate with Akt phosphorylation at T308. Our results suggested novel roles of basal [Ca2+]i, rather than activity-induced calcium elevation, in BDNF-Akt signaling.
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Affiliation(s)
- Fei Zheng
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
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22
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Simsek-Duran F, Lonart G. The role of RIM1alpha in BDNF-enhanced glutamate release. Neuropharmacology 2008; 55:27-34. [PMID: 18499195 DOI: 10.1016/j.neuropharm.2008.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2007] [Revised: 03/14/2008] [Accepted: 04/11/2008] [Indexed: 11/30/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is known to activate proline-directed Ser/Thr protein kinases and to enhance glutamatergic transmission via a Rab3a-dependent molecular pathway. The identity of molecular targets in BDNF's action on Rab3a pathway, a synaptic vesicle protein involved in vesicle trafficking and synaptic plasticity, is not fully known. Here we demonstrate that BDNF enhances depolarization-evoked efflux of [(3)H]-glutamate from nerve terminals isolated from the CA1 region of the hippocampus. BDNF also potentiated hyperosmotic shock-evoked [(3)H]-glutamate efflux, indicating an effect on the size of the readily releasable pool. This effect of BDNF was completely abolished in nerve terminals derived from Rim1alphaKO (Rab3 interacting molecule 1alpha null mutant) mice. Using in vitro phosphorylation assays we identified two novel phosphorylation sites, Ser447 and Ser745 that were substrates for ERK2, a proline-directed kinase known to be activated by BDNF. The pSer447 site was phosphorylated under resting conditions in hippocampal CA1 nerve terminals and its phosphorylation was enhanced by BDNF treatment, as indicated by the use of a pSer447-RIM1alpha antibody we have developed. Together these findings identify RIM1alpha, a component of the Rab3a molecular pathway in mediating presynaptic plasticity, as a necessary factor in BDNF's enhancement of [(3)H]-glutamate efflux from hippocampal CA1 nerve terminals and indicate a possible role for RIM1alpha phosphorylation in BDNF-dependent presynaptic plasticity.
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Affiliation(s)
- Fatma Simsek-Duran
- Department of Pathology and Anatomy, Eastern Virginia Medical School, 700 W. Olney Road Norfolk, VA 23507, USA
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23
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Desrivières S, Krause K, Dyer A, Frank J, Blomeyer D, Lathrop M, Mann K, Banaschewski T, Laucht M, Schumann G. Nucleotide sequence variation within the PI3K p85 alpha gene associates with alcohol risk drinking behaviour in adolescents. PLoS One 2008; 3:e1769. [PMID: 18335044 PMCID: PMC2262154 DOI: 10.1371/journal.pone.0001769] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Accepted: 02/04/2008] [Indexed: 11/24/2022] Open
Abstract
Background While the phosphatidylinositol 3-kinase (PI3K)-dependent signaling pathway is typically known to regulate cell growth and survival, emerging evidence suggest a role for this pathway in regulating the behavioural responses to addictive drugs. Methodology/Principal Findings To investigate whether PI3K contributes to patterns of risky alcohol drinking in human, we investigated genetic variations in PIK3R1, encoding the 85 kD regulatory subunit of PIK, in 145 family trios consisting of 15–16 year old adolescents and their parents. Screening for mutations in exons, exon-intron boundaries and regulatory sequences, we identified 14 single nucleotide polymorphisms (SNPs) in the PIK3R1 gene region from exon 1 to the beginning of the 3′ untranslated region (UTR). These SNPs defined haplotypes for the respective PIK3R1 region. Four haplotype tagging (ht)SNPs (rs706713, rs2302975, rs171649 and rs1043526), discriminating all haplotypes with a frequency ≥4.5% were identified. These htSNPs were used to genotype adolescents from the “Mannheim Study of Risk Children” (MARC). Transmission disequilibrium tests in these adolescents and their parents demonstrated sex-specific association of two SNPs, rs2302975 and rs1043526, with patterns of risky alcohol consumption in male adolescents, including lifetime prevalence of drunkenness (p = 0.0019 and 0.0379, respectively) and elevated maximum amount of drinking (p = 0.0020 and 0.0494, respectively), as a measure for binge drinking pattern. Conclusions/Significance Our findings highlight a previously unknown relevance of PIK3R1 genotypes for alcohol use disorders and might help discriminate individuals at risk for alcoholism.
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Affiliation(s)
- Sylvane Desrivières
- Section of Addiction Biology, Interdisciplinary Research Group “Addiction” and NIHR-Biomedical Research Centre, Institute of Psychiatry, King's College, London, United Kingdom
| | - Kristina Krause
- Section of Addiction Biology, Interdisciplinary Research Group “Addiction” and NIHR-Biomedical Research Centre, Institute of Psychiatry, King's College, London, United Kingdom
- Molecular Genetics Laboratory, Department of Addiction Medicine, Central Institute of Mental Health, Mannheim, Germany
| | - Anne Dyer
- Department of Psychosomatic Medicine, Central Institute of Mental Health, Mannheim, Germany
| | - Josef Frank
- Molecular Genetics Laboratory, Department of Addiction Medicine, Central Institute of Mental Health, Mannheim, Germany
| | - Dorothea Blomeyer
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany
| | | | - Karl Mann
- Molecular Genetics Laboratory, Department of Addiction Medicine, Central Institute of Mental Health, Mannheim, Germany
| | - Tobias Banaschewski
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany
| | - Manfred Laucht
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany
- Division of Clinical Psychology, Department of Psychology, University of Potsdam, Germany
- * E-mail:
| | - Gunter Schumann
- Section of Addiction Biology, Interdisciplinary Research Group “Addiction” and NIHR-Biomedical Research Centre, Institute of Psychiatry, King's College, London, United Kingdom
- Molecular Genetics Laboratory, Department of Addiction Medicine, Central Institute of Mental Health, Mannheim, Germany
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Je HS, Yang F, Zhou J, Lu B. Neurotrophin 3 induces structural and functional modification of synapses through distinct molecular mechanisms. ACTA ACUST UNITED AC 2007; 175:1029-42. [PMID: 17178914 PMCID: PMC2064711 DOI: 10.1083/jcb.200603061] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanisms by which neurotrophins elicit long-term structural and functional changes of synapses are not known. We report the mechanistic separation of functional and structural synaptic regulation by neurotrophin 3 (NT-3), using the neuromuscular synapse as a model. Inhibition of cAMP response element (CRE)-binding protein (CREB)-mediated transcription blocks the enhancement of transmitter release elicited by NT-3, without affecting the synaptic varicosity of the presynaptic terminals. Further analysis indicates that CREB is activated through Ca(2+)/calmodulin-dependent kinase IV (CaMKIV) pathway, rather than the mitogen-activated protein kinase (MAPK) or cAMP pathway. In contrast, inhibition of MAPK prevents the NT-3-induced structural, but not functional, changes. Genetic and imaging experiments indicate that the small GTPase Rap1, but not Ras, acts upstream of MAPK activation by NT-3. Thus, NT-3 initiates parallel structural and functional modifications of synapses through the Rap1-MAPK and CaMKIV-CREB pathways, respectively. These findings may have implications in the general mechanisms of long-term synaptic modulation by neurotrophins.
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Affiliation(s)
- Hyun-Soo Je
- Section on Neural Development and Plasticity, National Institute of Child Health and Human Development, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
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25
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Liou JC, Kang KH, Chang LS, Ho SY. Mechanism of β-bungarotoxin in facilitating spontaneous transmitter release at neuromuscular synapse. Neuropharmacology 2006; 51:671-80. [PMID: 16806309 DOI: 10.1016/j.neuropharm.2006.05.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 05/12/2006] [Accepted: 05/15/2006] [Indexed: 10/24/2022]
Abstract
The mechanism of the action of beta-bungarotoxin (beta-BuTx) in the facilitation of spontaneous transmitter release at neuromuscular synapse was investigated in Xenopus cell culture using whole-cell patch clamp recording. Exposure of the culture to beta-BuTx dose-dependently enhances the frequency of spontaneous synaptic currents (SSCs). Buffering the rise of intracellular Ca2+ with BAPTA-AM hampered the facilitation of SSC frequency induced by beta-BuTx. The beta-BuTx-enhanced SSC frequency was reduced when the pharmacological Ca2+ -ATPase inhibitor thapsigargin was used to deplete intracellular Ca2+ store. Application of membrane-permeable inhibitors of inositol 1,4,5-trisphosphate (IP3) but not ryanodine receptors effectively occluded the increase of SSC frequency elicited by beta-BuTx. Treating cells with either wortmannin or LY294002, two structurally different inhibitors of phosphatidylinositol 3-kinase (PI3K) and with phospholipase C (PLC) inhibitor U73122, abolished the beta-BuTx-induced facilitation of synaptic transmission. The beta-BuTx-induced synaptic facilitation was completely abolished while there was presynaptic loading of the motoneuron with GDPbetaS, a non-hydrolyzable GDP analogue and inhibitor of G protein. Taken collectively, these results suggest that beta-BuTx elicits Ca2+ release from the IP3 sensitive intracellular Ca2+ stores of the presynaptic nerve terminal. This is done via PI3K/PLC signaling cascades and G protein activation, leading to an enhancement of spontaneous transmitter release.
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Affiliation(s)
- Jau-Cheng Liou
- Department of Biological Sciences, National Sun Yat-sen University, No 70, Lein-Hai Rd., Kaohsiung 804, Taiwan.
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26
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Je HS, Zhou J, Yang F, Lu B. Distinct mechanisms for neurotrophin-3-induced acute and long-term synaptic potentiation. J Neurosci 2006; 25:11719-29. [PMID: 16354930 PMCID: PMC6726032 DOI: 10.1523/jneurosci.4087-05.2005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Although neurotrophins elicit both acute and long-term effects, it is unclear whether the two modes of action are mediated by the same or different mechanisms. Using neuromuscular junction (NMJ) as a model system, we identified three characteristic features required for long-term, but not acute, forms of synaptic modulation by neurotrophin-3 (NT-3): endocytosis of NT-3-receptor complex, activation of the PI3 kinase substrate Akt, and new protein synthesis. Long-term effects were eliminated when NT-3 was conjugated to a bead that was too large to be endocytosed or when dominant-negative dynamin was expressed in presynaptic neurons. Presynaptic inhibition of Akt also selectively prevented NT-3-mediated long-term effects. Blockade of protein translation by the mammalian target of rapamycin inhibitor rapamycin prevented the long-term structural and functional changes at the NMJ, without affecting the acute potentiation of synaptic transmission by NT-3. These results reveal fundamental differences between acute and long-term modulation by neurotrophins.
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Affiliation(s)
- Hyun-Soo Je
- Section on Neural Development and Plasticity, National Institute of Child Health and Human Development, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892-3714, USA
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27
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Gärtner A, Polnau DG, Staiger V, Sciarretta C, Minichiello L, Thoenen H, Bonhoeffer T, Korte M. Hippocampal long-term potentiation is supported by presynaptic and postsynaptic tyrosine receptor kinase B-mediated phospholipase Cgamma signaling. J Neurosci 2006; 26:3496-504. [PMID: 16571757 PMCID: PMC6673845 DOI: 10.1523/jneurosci.3792-05.2006] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Neurotrophins have been shown to play a critical role in activity-dependent synaptic plasticity such as long-term potentiation (LTP) in the hippocampus. Although the role of brain-derived neurotrophic factor (BDNF) and its tyrosine kinase receptor [tyrosine receptor kinase B (TrkB)] is well documented, it still remains unresolved whether presynaptic or postsynaptic activation of TrkB is involved in the induction of LTP. To address this question, we locally and specifically interfered with a downstream target of the TrkB receptor, phospholipase Cgamma (PLCgamma). We prevented PLCgamma signaling by overexpression of the PLCgamma pleckstrin homology (PH) domain with a Sindbis virus vector. The isolated PH domain has an inhibitory effect and thereby blocks endogenous PLCgamma signaling and consequently also IP3 production. Surprisingly, concurrent presynaptic and postsynaptic blockade of PLCgamma signaling was required to reduce LTP to levels comparable with those in TrkB and BDNF knock-out mice. Blockade of presynaptic or postsynaptic signaling alone did not result in a significant reduction of LTP.
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28
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Pagani MR, Reisin RC, Uchitel OD. Calcium signaling pathways mediating synaptic potentiation triggered by amyotrophic lateral sclerosis IgG in motor nerve terminals. J Neurosci 2006; 26:2661-72. [PMID: 16525045 PMCID: PMC6675160 DOI: 10.1523/jneurosci.4394-05.2006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Sporadic amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects particularly motoneurons. Several pieces of evidence suggested the involvement of autoimmune mechanisms mediated by antibodies in ALS. However, the significance of those antibodies in the disease and the underlying mechanisms are unknown. Here we showed that IgG purified from a group of sporadic ALS patients, but not familial ALS patients, specifically interact with the presynaptic membrane of motoneurons through an antigen-antibody interaction and modulated synaptic transmission. Immunoreactivity against nerve terminals showed strong correlation with synaptic modulation ability. In addition, several controls have ruled out the possibility for this synaptic modulation to be mediated through proteases or nonspecific effects. Effective IgG potentiated both spontaneous and asynchronous transmitter release. Application of pharmacological inhibitors suggested that activation of this increased release required a nonconstitutive Ca2+ influx through N-type (Cav2.2) channels and phospholipase C activity and that activation of IP3 and ryanodine receptors were necessary to both activate and sustain the increased release. Consistent with the notion that ALS is heterogeneous disorder, our results reveal that, in approximately 50% of ALS patients, motor nerve terminals constitutes a target for autoimmune response.
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29
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Yee C, Bartel DL, Finger TE. Effects of glossopharyngeal nerve section on the expression of neurotrophins and their receptors in lingual taste buds of adult mice. J Comp Neurol 2005; 490:371-90. [PMID: 16127713 DOI: 10.1002/cne.20670] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The expression of neurotrophins and neurotrophin receptors is essential for the proper establishment and function of many sensory systems. To determine which neurotrophins and neurotrophin receptors are expressed in taste buds, and in taste buds of mice following denervation, antibodies directed against the neurotrophins and their receptors were applied to adult mouse gustatory tissue. Immunohistochemistry reveals that nerve growth factor (NGF)-like immunoreactive (LIR), tyrosine kinase (trk) A-LIR, trkB-LIR, and p75-LIR elongated, differentiated taste cells are present within all lingual taste buds, whereas neither neurotrophin (NT)-3- nor trkC-LIR was detected in taste cells. Double-label immunohistochemistry using markers of different taste cell types in brain-derived neurotrophic factor (BDNF)LacZ mice reveals that BDNF (beta-gal) and trkB colocalize, mainly in type III taste cells. NGF, pro-NGF, and trkA coexist in type II taste cells, i.e., those expressing phospholipase Cbeta2 (PLCbeta2). p75-LIR also is present in both BDNF and NGF taste cell populations. To determine the neural dependence of neurotrophin expression in adult taste buds, glossopharyngeal nerves were cut unilaterally. During the period of denervation (10 days to 3 weeks), taste buds largely disappear, and few neurotrophin-expressing cells are present. Three weeks after nerve transection, nerve fascicles on the operated side of the tongue exhibit BDNF-LIR, NGF-LIR, and ubiquitin carboxyl terminal hydrolase (PGP 9.5)-LIR. However, BDNF-LIR staining intensity but not NGF-LIR or PGP 9.5-LIR is increased in nerve fascicles on the operated compared with the unoperated side. Five weeks following nerve transection, NT and NT receptor expression resumes and appears normal in taste buds and nerves. These results indicate that neurotrophin expression in taste buds is dependent on gustatory innervation, but expression in nerves is not dependent on contact with taste buds.
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Affiliation(s)
- Cindy Yee
- Rocky Mountain Taste and Smell Center, Department of Cellular and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado 80045-6511, USA
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Huang YJ, Maruyama Y, Lu KS, Pereira E, Plonsky I, Baur JE, Wu D, Roper SD. Mouse taste buds use serotonin as a neurotransmitter. J Neurosci 2005; 25:843-7. [PMID: 15673664 PMCID: PMC6725637 DOI: 10.1523/jneurosci.4446-04.2005] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Synapses between gustatory receptor cells and primary sensory afferent fibers transmit the output signal from taste buds to the CNS. Several transmitter candidates have been proposed for these synapses, including serotonin (5-HT), glutamate, acetylcholine, ATP, peptides, and others, but, to date, none has been unambiguously identified. We used Chinese hamster ovary cells stably expressing 5-HT2C receptors as biodetectors to monitor 5-HT release from taste buds. When taste buds were depolarized with KCl or stimulated with bitter, sweet, or sour (acid) tastants, serotonin was released. KCl- and acid-induced 5-HT release, but not release attributable to sweet or bitter stimulation, required Ca2+ influx. In contrast, 5-HT release evoked by sweet and bitter stimulation seemed to be triggered by intracellular Ca2+ release. These experiments strongly implicate serotonin as a taste bud neurotransmitter and reveal unexpected transmitter release mechanisms.
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Affiliation(s)
- Yi-Jen Huang
- Department of Physiology and Biophysics, University of Miami School of Medicine, Miami, Florida 33136, USA
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Zhuang ZY, Xu H, Clapham DE, Ji RR. Phosphatidylinositol 3-kinase activates ERK in primary sensory neurons and mediates inflammatory heat hyperalgesia through TRPV1 sensitization. J Neurosci 2005; 24:8300-9. [PMID: 15385613 PMCID: PMC6729698 DOI: 10.1523/jneurosci.2893-04.2004] [Citation(s) in RCA: 329] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Although the PI3K (phosphatidylinositol 3-kinase) pathway typically regulates cell growth and survival, increasing evidence indicates the involvement of this pathway in neural plasticity. It is unknown whether the PI3K pathway can mediate pain hypersensitivity. Intradermal injection of capsaicin and NGF produce heat hyperalgesia by activating their respective TRPV1 (transient receptor potential vanilloid receptor-1) and TrkA receptors on nociceptor sensory nerve terminals. We examined the activation of PI3K in primary sensory DRG neurons by these inflammatory agents and the contribution of PI3K activation to inflammatory pain. We further investigated the correlation between the PI3K and the ERK (extracellular signal-regulated protein kinase) pathway. Capsaicin and NGF induce phosphorylation of the PI3K downstream target AKT (protein kinase B), which is blocked by the PI3K inhibitors LY294002 and wortmannin, indicative of the activation of PI3K by both agents. ERK activation by capsaicin and NGF was also blocked by PI3K inhibitors. Similarly, intradermal capsaicin in rats activated PI3K and ERK in C-fiber DRG neurons and epidermal nerve fibers. Injection of PI3K or MEK (ERK kinase) inhibitors into the hindpaw attenuated capsaicin- and NGF-evoked heat hyperalgesia but did not change basal heat sensitivity. Furthermore, PI3K, but not ERK, inhibition blocked early induction of hyperalgesia. In acutely dissociated DRG neurons, the capsaicin-induced TRPV1 current was strikingly potentiated by NGF, and this potentiation was completely blocked by PI3K inhibitors and primarily suppressed by MEK inhibitors. Therefore, PI3K induces heat hyperalgesia, possibly by regulating TRPV1 activity, in an ERK-dependent manner. The PI3K pathway also appears to play a role that is distinct from ERK by regulating the early onset of inflammatory pain.
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Affiliation(s)
- Zhi-Ye Zhuang
- Pain Research Center, Department of Anesthesiology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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Pezet S, Spyropoulos A, Williams RJ, McMahon SB. Activity-dependent phosphorylation of Akt/PKB in adult DRG neurons. Eur J Neurosci 2005; 21:1785-97. [PMID: 15869474 DOI: 10.1111/j.1460-9568.2005.04011.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The serine/threonine kinase Akt/PKB has been implicated in cell survival signalling in many cell types, including the dorsal root ganglion (DRG). However, little is known about its role in physiological and pathophysiological conditions in the adult sensory and nociceptive system. In this study, we show that in naive animals almost all cells express Akt but only a subset of small-diameter neurons expresses a high level of phospho-Akt (p-Akt Ser 473). Activation of peripheral nociceptors in vivo using intraplantar injections of capsaicin in anaesthetized rats induced a rapid onset and time-dependent increase in p-Akt Ser 473 in small- and medium-sized DRG, predominantly TRPV1-positive neurons. In addition, electrical stimulation of 'A and C' fibres in the sciatic nerve induced an increase in the cytoplasmic staining of p-Akt Ser 473 in small- and medium-size DRG neurons. Blocking neuronal activity in the sciatic nerve using tetrodotoxin reduced the basal level of p-Akt Ser 473. Cultured DRG neurons confirmed that phosphorylation of Akt in different cellular compartments is triggered by depolarization or receptor activation, and suggested that this effect is mediated in part by phosphatidylinositol 3-kinase. Our results show that p-Akt Ser 473 is a marker of nociceptor activation and suggest a novel role for Akt in the transduction of intracellular signals in adult DRG neurons.
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Affiliation(s)
- Sophie Pezet
- King's College London, Center for Age Related Diseases, Wolfson Wing, Guy's Campus, London Bridge, London SE1 1UL, UK.
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33
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Itakura M, Yamamori S, Kuwahara R, Sekiguchi M, Takahashi M. Two distinct regulatory mechanisms of neurotransmitter release by phosphatidylinositol 3-kinase. J Neurochem 2005; 94:502-9. [PMID: 15998300 DOI: 10.1111/j.1471-4159.2005.03242.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Recent studies have indicated that various growth factors are involved in synaptic functions; however, the precise mechanisms remain unclear. In order to elucidate the molecular mechanisms of the growth factor-mediated regulation of presynaptic functions, the effects of epidermal growth factor (EGF) and insulin-like growth factor-1 (IGF-1) on neurotransmitter release were studied in rat PC12 cells. Brief treatment with EGF and IGF-1 enhanced Ca2+-dependent dopamine release in a concentration-dependent manner. EGF activated both mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3-kinase) pathways, and the EGF-dependent enhancement of DA release was suppressed by a MAPK kinase inhibitor as well as by PI3-kinase inhibitors. In striking contrast, IGF-1 activated the PI3-kinase pathway but not the MAPK pathway, and IGF-1-dependent enhancement was suppressed by a PI3-kinase inhibitor but not by a MAPK kinase inhibitor. The enhanced green fluorescent protein-tagged pleckstrin homology (PH) domain of protein kinase B, which selectively binds to phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-triphosphate, was translocated to the plasma membrane after treatment with either EGF or NGF. By contrast, no significant redistribution was induced by IGF-1. These results indicate that PI3-kinase participates in the enhancement of neurotransmitter release by two distinct mechanisms: EGF and NGF activate PI3-kinase in the plasma membrane, whereas IGF-1 activates PI3-kinase possibly in the intracellular membrane, leading to enhancement of neurotransmitter release in a MAPK-dependent and -independent manner respectively.
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Shah BH, Neithardt A, Chu DB, Shah FB, Catt KJ. Role of EGF receptor transactivation in phosphoinositide 3-kinase-dependent activation of MAP kinase by GPCRs. J Cell Physiol 2005; 206:47-57. [PMID: 15920762 DOI: 10.1002/jcp.20423] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many G protein coupled receptors (GPCRs) cause phosphorylation of MAP kinases through transactivation of the epidermal growth factor receptor (EGF-R), leading to increased cell survival and growth, motility, and migration. Phosphoinositide 3-kinase (PI3K) is one of the important cell survival signaling molecules activated by EGF-R stimulation. However, the extent to which EGF-R transactivation is essential for GPCR agonist-stimulated PI3K activation is not known. Here we examined the mechanism of PI3K activation that elicits GPCR-mediated ERK1/2 activation by pathways dependent and/or independent of EGF-R transactivation in specific cell types. Immortalized hypothalamic neurons (GT1-7 cells) express endogenous gonadotropin-releasing hormone receptors (GnRH-R) and their stimulation causes marked phosphorylation of ERK1/2 and Akt (Ser 473) through transactivation of the EGF-R and recruitment of PI3K. In C9 hepatocytes, agonist activation of AT1 angiotensin II (AT1-R), lysophosphatidic acid (LPA), and EGF receptors caused phosphorylation of Akt through activation of the EGF-R in a PI3K-dependent manner. However, ERK1/2 activation by these agonists in these cells was independent of PI3K activation. In contrast, agonist stimulation of HEK 293 cells stably expressing AT1-R caused ERK1/2 phosphorylation that was independent of EGF-R transactivation but required PI3K activation. LPA signaling in these cells showed partial and complete dependence on EGF-R and PI3K, respectively. These data indicate that GPCR-induced ERK1/2 phosphorylation is dependent or independent of PI3K in specific cell types, and that the involvement of PI3K during ERK1/2 activation is not dependent solely on agonist-induced transactivation of the EGF-R.
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Affiliation(s)
- Bukhtiar H Shah
- Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4510, USA.
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35
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Banerjee S, Hasan G. The InsP3 receptor: its role in neuronal physiology and neurodegeneration. Bioessays 2005; 27:1035-47. [PMID: 16163728 DOI: 10.1002/bies.20298] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The InsP3 receptor is a ligand-gated channel that releases Ca2+ from intracellular stores in a variety of cell types, including neurons. Genetic studies from vertebrate and invertebrate model systems suggest that coordinated rhythmic motor functions are most susceptible to changes in Ca2+ release from the InsP3 receptor. In many cases, the InsP3 receptor interacts with other signaling mechanisms that control levels of cytosolic Ca2+, suggesting that the maintenance of Ca2+ homeostasis in normal cells could be controlled by the activity of the InsP3R. In support of this idea, recent studies show that altered InsP3 receptor activity can be partially responsible for Ca2+ dyshomeostasis seen in many neurodegenerative conditions. These observations open new avenues for carrying out genetic and drug screens that target InsP3R function in neurodegenerative conditions.
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Affiliation(s)
- Santanu Banerjee
- National Centre for Biological Sciences, Tata Institute for Fundamental Research, Bangalore, Karnataka, India.
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36
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Tzeng SF, Huang HY. Downregulation of inducible nitric oxide synthetase by neurotrophin-3 in microglia. J Cell Biochem 2004; 90:227-33. [PMID: 14505339 DOI: 10.1002/jcb.10658] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Microglia activated after many neurological degeneration of the central nervous system (CNS) act as important regulators for neuropathogenesis in the injured CNS via producing proinflammatory mediators, such as nitric oxide (NO), TNF-alpha, and IL-1beta. Neurotrophin-3 (NT-3) is a well-known trophic factor for neural survival, development, and plasticity. Activated microglia are NT-3-producing cells in the injured CNS, and express its receptor-TrkC. However, little is known about the effect of NT-3 on activated microglia. In this study, pre-treatment of a mouse microglial cell line, BV2, with NT-3 for 24 h indicated that NT-3 reduced the inducible form of NO synthase (iNOS), NO, and TNF-alpha in BV2 stimulated with lipopolysaccharide (LPS). NT-3 exerted less effect on the reduction of these proinflammatory mediators when it was added to BV2 cultures either simultaneously with LPS or post LPS treatment. These findings indicate that NT-3 may serve as an anti-inflammatory factor to suppress microglial activation.
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Affiliation(s)
- Shun-Fen Tzeng
- Department of Biology, National Cheng Kung University, Tainan City, Taiwan.
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37
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Blum S, Dash PK. A Cell-Permeable Phospholipase C 1-Binding Peptide Transduces Neurons and Impairs Long-Term Spatial Memory. Learn Mem 2004; 11:239-43. [PMID: 15169852 DOI: 10.1101/lm.74104] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Growth factor-mediated signaling has emerged as an essential component of memory formation. In this study, we used a phospholipase C gamma 1 (PLCgamma1) binding, cell-penetrating peptide to sequester PLCgamma1 away from its target, the phosphotyrosine residues within the activated growth factor receptor. Peptides appear to transduce neurons but not astrocytes or oligodendrocytes. The presence of the peptides in the hippocampus during training in the Morris water maze significantly impaired long-term memory, but not memory acquisition. These results, along with previous studies on extracellular signal-regulated kinase (ERK) and phosphoinositide-3 kinase (PI3K), implicate all three key growth factor receptor-activated intracellular signaling pathways in memory storage.
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Affiliation(s)
- Sonja Blum
- Department of Neurobiology and Anatomy, The Vivian L. Smith Center for Neurologic Research, The University of Texas Medical School, Houston, Texas 77225, USA
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38
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Yang F, He XP, Russell J, Lu B. Ca2+ influx-independent synaptic potentiation mediated by mitochondrial Na(+)-Ca2+ exchanger and protein kinase C. ACTA ACUST UNITED AC 2004; 163:511-23. [PMID: 14610054 PMCID: PMC2173636 DOI: 10.1083/jcb.200307027] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Activity-dependent modulation of synaptic transmission is an essential mechanism underlying many brain functions. Here we report an unusual form of synaptic modulation that depends on Na+ influx and mitochondrial Na+-Ca2+ exchanger, but not on Ca2+ influx. In Ca2+-free medium, tetanic stimulation of Xenopus motoneurons induced a striking potentiation of transmitter release at neuromuscular synapses. Inhibition of either Na+ influx or the rise of Ca2+ concentrations ([Ca2+]i) at nerve terminals prevented the tetanus-induced synaptic potentiation (TISP). Blockade of Ca2+ release from mitochondrial Na+-Ca2+ exchanger, but not from ER Ca2+ stores, also inhibited TISP. Tetanic stimulation in Ca2+-free medium elicited an increase in [Ca2+]i, which was prevented by inhibition of Na+ influx or mitochondrial Ca2+ release. Inhibition of PKC blocked the TISP as well as mitochondrial Ca2+ release. These results reveal a novel form of synaptic plasticity and suggest a role of PKC in mitochondrial Ca2+ release during synaptic transmission.
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Affiliation(s)
- Feng Yang
- Section on Neural Development and Plasticity, Laboratory of Cellular and Synaptic Neurophysiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4480, USA
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39
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Abstract
While it has now been well accepted that neurotrophins play an important role in synapse development and plasticity, the specific effects of each neurotrophin on different populations of neurons at different developmental stages have just begun to be worked out. Moreover, the cellular and molecular mechanisms underlying the synaptic function of neurotrophins remain poorly understood. In general, synaptic effects of neurotrophins could be divided into two categories: acute effect on synaptic transmission and plasticity occurring within seconds or minutes after cells are exposed to a neurotrophin, and long-term effect on synaptic structures and function that takes days to accomplish. In this review I have considered the previous findings on neurotrophic regulation of synapses in view of these two categories. Acute and long-term effects of neurotrophins are reexamined in detail in three model systems: the neuromuscular junction, the hippocampus and the visual cortex. Potential molecular mechanisms that mediate the acute or long-term neurotrophic regulation are discussed. Efforts are made to understand the mechanistic differences between the two effects and their relationships. Further study of these mechanisms will help us better understand how neurotrophins can achieve diverse and synapse-specific modulation.
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Affiliation(s)
- Bai Lu
- Section on Neural Development and Plasticity, NICHD, NIH, Building 49, Rm. 6A80, 49 Convent Dr., MSC4480, Bethesda, MD 20892-4480, USA.
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40
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Merighi A, Carmignoto G, Gobbo S, Lossi L, Salio C, Vergnano AM, Zonta M. Neurotrophins in spinal cord nociceptive pathways. PROGRESS IN BRAIN RESEARCH 2004; 146:291-321. [PMID: 14699971 DOI: 10.1016/s0079-6123(03)46019-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Neurotrophins are a well-known family of growth factors for the central and peripheral nervous systems. In the course of the last years, several lines of evidence converged to indicate that some members of the family, particularly NGF and BDNF, also participate in structural and functional plasticity of nociceptive pathways within the dorsal root ganglia and spinal cord. A subpopulation of small-sized dorsal root ganglion neurons is sensitive to NGF and responds to peripheral NGF stimulation with upregulation of BDNF synthesis and increased anterograde transport to the dorsal horn. In the latter, release of BDNF appears to modulate or even mediate nociceptive sensory inputs and pain hypersensitivity. We summarize here the status of the art on the role of neurotrophins in nociceptive pathways, with special emphasis on short-term synaptic and intracellular events that are mediated by this novel class of neuromessengers in the dorsal horn. Under this perspective we review the findings obtained through an array of techniques in naïve and transgenic animals that provide insight into the modulatory mechanisms of BDNF at central synapses. We also report on the results obtained after immunocytochemistry, in situ hybridization, and monitoring intracellular calcium levels by confocal microscopy, that led to hypothesize that also NGF might have a direct central effect in pain modulation. Although it is unclear whether or not NGF may be released at dorsal horn endings of certain nociceptors in vivo, we believe that these findings offer a clue for further studies aiming to elucidate the putative central effects of NGF and other neurotrophins in nociceptive pathways.
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Affiliation(s)
- Adalberto Merighi
- Department of Veterinary Morphophysiology, Rita Levi-Montalcini Center for Brain Repair, Via Leonardo da Vinci 44, 10095 Grugliasco, Turin, Italy.
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41
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Numakawa T, Nakayama H, Suzuki S, Kubo T, Nara F, Numakawa Y, Yokomaku D, Araki T, Ishimoto T, Ogura A, Taguchi T. Nerve growth factor-induced glutamate release is via p75 receptor, ceramide, and Ca(2+) from ryanodine receptor in developing cerebellar neurons. J Biol Chem 2003; 278:41259-69. [PMID: 12902347 DOI: 10.1074/jbc.m304409200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Very little is known about the contribution of a low affinity neurotrophin receptor, p75, to neurotransmitter release. Here we show that nerve growth factor (NGF) induced a rapid release of glutamate and an increase of Ca2+ in cerebellar neurons through a p75-dependent pathway. The NGF-induced release occurred even in the presence of the Trk inhibitor K252a. The release caused by NGF but not brain-derived neurotrophic factor was enhanced in neurons overexpressing p75. Further, after transfection of p75-small interfering RNA, which down-regulated the endogenous p75 expression, the NGF-induced release was inhibited, suggesting that the NGF-induced glutamate release was through p75. We found that the NGF-increased Ca2+ was derived from the ryanodine-sensitive Ca2+ receptor and that the NGF-increased Ca2+ was essential for the NGF-induced glutamate release. Furthermore, scyphostatin, a sphingomyelinase inhibitor, blocked the NGF-dependent Ca2+ increase and glutamate release, suggesting that a ceramide produced by sphingomyelinase was required for the NGF-stimulated Ca2+ increase and glutamate release. This action of NGF only occurred in developing neurons whereas the brain-derived neurotrophic factor-mediated Ca2+ increase and glutamate release was observed at the mature neuronal stage. Thus, we demonstrate that NGF-mediated neurotransmitter release via the p75-dependent pathway has an important role in developing neurons.
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Affiliation(s)
- Tadahiro Numakawa
- Neuronics R G Special Division for Human Life Technology National Institute of Advanced Industrial Science and Technology (AIST) Midorigaoka, Ikeda, Osaka 563-8577, Japan.
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42
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Brain-derived neurotrophic factor modulation of GABAergic synapses by postsynaptic regulation of chloride transport. J Neurosci 2003. [PMID: 14507972 DOI: 10.1523/jneurosci.23-25-08722.2003] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) potentiates excitatory synapses in a variety of systems by promoting presynaptic transmitter release. The existing evidence indicates that BDNF attenuates inhibitory transmission, but reports differ considerably in their characterization of the effect and proposed mechanisms. We examined the effects of exogenously applied BDNF on EPSCs and IPSCs recorded from functionally identified neurons in dissociated rat hippocampal cultures. When recording from glutamatergic neurons, we found that BDNF exerted differential effects at excitatory versus inhibitory synapses: increasing amplitude of EPSCs but slightly decreasing that of IPSCs. Furthermore, when recording from GABAergic neurons, we found that BDNF increased the IPSC amplitude. That these differential BDNF effects reflect distinct presynaptic and postsynaptic mechanisms was suggested by the BDNF-induced changes in miniature EPSCs and IPSCs. An increased mini-frequency was found at all synapses, indicating elevated presynaptic transmitter secretion; a change in the amplitude of mini-IPSCs was found at GABAergic cells, suggesting postsynaptic modulation of GABA responses. Selective postsynaptic mechanisms were further examined by comparing the effect of BDNF on GABA-induced currents recorded from glutamatergic versus GABAergic cells. For GABAergic but not glutamatergic postsynaptic cells, BDNF induced a shift in the reversal potential (EIPSC) toward more positive levels, hence reducing the inhibitory action of IPSCs. This BDNF-induced effect correlates with the existing level of furosemide-sensitive K+-Cl- transport activity in the postsynaptic cell. Thus, BDNF may decrease the efficacy of inhibitory transmission by acute postsynaptic downregulation of Cl- transport, in addition to its well known presynaptic effect.
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Cousin MA, Malladi CS, Tan TC, Raymond CR, Smillie KJ, Robinson PJ. Synapsin I-associated phosphatidylinositol 3-kinase mediates synaptic vesicle delivery to the readily releasable pool. J Biol Chem 2003; 278:29065-71. [PMID: 12754199 DOI: 10.1074/jbc.m302386200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Maintaining synaptic transmission requires replenishment of docked synaptic vesicles within the readily releasable pool (RRP) from synaptic vesicle clusters in the synapsin-bound reserve pool. We show that synapsin forms a complex with phosphatidylinositol 3-kinase (PI 3-kinase) in intact nerve terminals and that synapsin-associated kinase activity increases on depolarization. Disruption of either PI 3-kinase activity or its interaction with synapsin inhibited replenishment of the RRP, but did not affect exocytosis from the RRP. Thus we conclude that a synapsin-associated PI 3-kinase activity plays a role in synaptic vesicle delivery to the RRP. This also suggests that PI 3-kinase contributes to the maintenance of synaptic transmission during periods of high activity, indicating a possible role in synaptic plasticity.
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Affiliation(s)
- Michael A Cousin
- Cell Signalling Unit, Children's Medical Research Institute, Locked Bag 23, Wentworthville 2145, NSW, Australia.
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44
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Goggi J, Pullar IA, Carney SL, Bradford HF. Signalling pathways involved in the short-term potentiation of dopamine release by BDNF. Brain Res 2003; 968:156-61. [PMID: 12644273 DOI: 10.1016/s0006-8993(03)02234-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) has been shown to modulate synaptic plasticity in the corpus striatum in vitro by activation of the tyrosine kinase linked receptor, TrkB. However, the signalling pathways that mediate this modulation of plasticity are poorly understood. Three proteins mediating signalling pathways are activated by the binding of BDNF to TrkB: phosphoinositol-3 kinase (PI3K); Ras-MEK and phospholipase C-gamma (PLCgamma). The present study investigates which of these pathways are necessary for BDNF-mediated potentiation of synaptic output of dopamine from slices and synaptosomes of rat corpus striatum. The results indicate that activation of the PI3K and Ras-MEK pathways, but not PLCgamma, are involved. Inhibitors of transcription and translation had no effect on the potentiation of depolarisation-stimulated (15 mM KCl) dopamine release mediated by BDNF.
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Affiliation(s)
- Julian Goggi
- Department of Biochemistry, Imperial College of Science, Technology and Medicine, Imperial College Road, South Kensington, SW7 2AY, London, UK
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45
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Chao MV. Neurotrophins and their receptors: a convergence point for many signalling pathways. Nat Rev Neurosci 2003; 4:299-309. [PMID: 12671646 DOI: 10.1038/nrn1078] [Citation(s) in RCA: 1657] [Impact Index Per Article: 78.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Moses V Chao
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York 10016, USA.
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46
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Abstract
It is widely accepted that neuronal activity plays a pivotal role in synaptic plasticity. Neurotrophins have emerged recently as potent factors for synaptic modulation. The relationship between the activity and neurotrophic regulation of synapse development and plasticity, however, remains unclear. A prevailing hypothesis is that activity-dependent synaptic modulation is mediated by neurotrophins. An important but unresolved issue is how diffusible molecules such as neurotrophins achieve local and synapse-specific modulation. In this review, I discuss several potential mechanisms with which neuronal activity could control the synapse-specificity of neurotrophin regulation, with particular emphasis on BDNF. Data accumulated in recent years suggest that neuronal activity regulates the transcription of BDNF gene, the transport of BDNF mRNA and protein into dendrites, and the secretion of BDNF protein. There is also evidence for activity-dependent regulation of the trafficking of the BDNF receptor, TrkB, including its cell surface expression and ligand-induced endocytosis. Further study of these mechanisms will help us better understand how neurotrophins could mediate activity-dependent plasticity in a local and synapse-specific manner.
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Affiliation(s)
- Bai Lu
- Section on Neural Development and Plasticity, National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland 20892-4480, USA.
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47
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Takahashi M, Itakura M, Kataoka M. New Aspects of Neurotransmitter Releasee and Exocytosis: Regulation of Neurotransmitter Release by Phosphorylation. J Pharmacol Sci 2003; 93:41-5. [PMID: 14501150 DOI: 10.1254/jphs.93.41] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Synaptic transmission is conducted by neurotransmitters released from nerve terminals. Neurotransmitter release is regulated both positively and negatively by multiple mechanisms, and its regulation is believed to be one of the important mechanisms of synaptic plasticity underlying learning and memory. Various protein kinases play important roles in the regulation, and candidates for protein substrates essential for the regulation have been identified.
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Affiliation(s)
- Masami Takahashi
- Department of Biochemistry, Kitasato University School of Medicine, Kanagawa, Japan.
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48
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Cardona-Gómez GP, Mendez P, DonCarlos LL, Azcoitia I, Garcia-Segura LM. Interactions of estrogen and insulin-like growth factor-I in the brain: molecular mechanisms and functional implications. J Steroid Biochem Mol Biol 2002; 83:211-7. [PMID: 12650718 DOI: 10.1016/s0960-0760(02)00261-3] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In the brain, as in other tissues, estradiol interacts with growth factors. One of the growth factors that is involved in the neural actions of estradiol is insulin-like growth factor-I (IGF-I). Estradiol and IGF-I cooperate in the central nervous system to regulate neuronal development, neural plasticity, neuroendocrine events and the response of neural tissue to injury. The precise molecular mechanisms involved in these interactions are still not well understood. In the central nervous system there is abundant co-expression of estrogen receptors (ERs) and IGF-I receptors (IGF-IRs) in the same cells. Furthermore, the expression of estrogen receptors and IGF-I receptors in the brain is cross-regulated. In addition, using specific antibodies for the phosphorylated forms of extracellular-signal regulated kinase (ERK) 1 and ERK2 and Akt/protein kinase B (Akt/PKB) it has been shown that estradiol affects IGF-I signaling pathways in the brain. Estradiol treatment results in a dose-dependent increase in the phosphorylation of ERK and Akt/PKB in the brain of adult ovariectomized rats. In addition, estradiol and IGF-I have a synergistic effects on the activation of Akt/PKB in the adult rat brain. These findings suggest that estrogen effects in the brain may be mediated in part by the activation of the signaling pathways of the IGF-I receptor.
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49
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Vicario-Abejón C, Owens D, McKay R, Segal M. Role of neurotrophins in central synapse formation and stabilization. Nat Rev Neurosci 2002; 3:965-74. [PMID: 12461553 DOI: 10.1038/nrn988] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Carlos Vicario-Abejón
- Group of Growth Factors in Vertebrate Development, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, E-28006 Madrid, Spain.
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Numakawa T, Yokomaku D, Kiyosue K, Adachi N, Matsumoto T, Numakawa Y, Taguchi T, Hatanaka H, Yamada M. Basic fibroblast growth factor evokes a rapid glutamate release through activation of the MAPK pathway in cultured cortical neurons. J Biol Chem 2002; 277:28861-9. [PMID: 12034732 DOI: 10.1074/jbc.m202927200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
We examined the possibility that basic fibroblast growth factor (bFGF) is involved in synaptic transmissions. We found that bFGF rapidly induced the release of glutamate and an increase in the intracellular Ca2+ concentration through voltage-dependent Ca2+ channels in cultured cerebral cortical neurons. bFGF also evoked a significant influx of Na+. Tetanustoxin inhibited the bFGF-induced glutamate release, revealing that bFGF triggered exocytosis. The mitogen-activated protein kinase (MAPK) pathway was required for these acute effects of bFGF. We also found that pretreatment with bFGF significantly enhanced high K+-elicited glutamate release also in a MAPK activation-dependent manner. Therefore, we propose that bFGF exerts promoting effects on excitatory neuronal transmission via activation of the MAPK pathway.
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Affiliation(s)
- Tadahiro Numakawa
- Division of Protein Biosynthesis, Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
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