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Leahy SN, Vita DJ, Broadie K. PTPN11/Corkscrew Activates Local Presynaptic Mapk Signaling to Regulate Synapsin, Synaptic Vesicle Pools, and Neurotransmission Strength, with a Dual Requirement in Neurons and Glia. J Neurosci 2024; 44:e1077232024. [PMID: 38471782 PMCID: PMC11044113 DOI: 10.1523/jneurosci.1077-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 03/01/2024] [Accepted: 03/05/2024] [Indexed: 03/14/2024] Open
Abstract
Cytoplasmic protein tyrosine phosphatase nonreceptor type 11 (PTPN11) and Drosophila homolog Corkscrew (Csw) regulate the mitogen-activated protein kinase (MAPK) pathway via a conserved autoinhibitory mechanism. Disease-causing loss-of-function (LoF) and gain-of-function (GoF) mutations both disrupt this autoinhibition to potentiate MAPK signaling. At the Drosophila neuromuscular junction glutamatergic synapse, LoF/GoF mutations elevate transmission strength and reduce activity-dependent synaptic depression. In both sexes of LoF/GoF mutations, the synaptic vesicles (SV)-colocalized synapsin phosphoprotein tether is highly elevated at rest, but quickly reduced with stimulation, suggesting a larger SV reserve pool with greatly heightened activity-dependent recruitment. Transmission electron microscopy of mutants reveals an elevated number of SVs clustered at the presynaptic active zones, suggesting that the increased vesicle availability is causative for the elevated neurotransmission. Direct neuron-targeted extracellular signal-regulated kinase (ERK) GoF phenocopies both increased local presynaptic MAPK/ERK signaling and synaptic transmission strength in mutants, confirming the presynaptic regulatory mechanism. Synapsin loss blocks this elevation in both presynaptic PTPN11 and ERK mutants. However, csw null mutants cannot be rescued by wild-type Csw in neurons: neurotransmission is only rescued by expressing Csw in both neurons and glia simultaneously. Nevertheless, targeted LoF/GoF mutations in either neurons or glia alone recapitulate the elevated neurotransmission. Thus, PTPN11/Csw mutations in either cell type are sufficient to upregulate presynaptic function, but a dual requirement in neurons and glia is necessary for neurotransmission. Taken together, we conclude that PTPN11/Csw acts in both neurons and glia, with LoF and GoF similarly upregulating MAPK/ERK signaling to enhance presynaptic Synapsin-mediated SV trafficking.
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Affiliation(s)
- Shannon N Leahy
- Departments of Biological Sciences, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
| | - Dominic J Vita
- Departments of Biological Sciences, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
| | - Kendal Broadie
- Departments of Biological Sciences, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
- Cell and Developmental Biology, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
- Pharmacology, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
- Vanderbilt Brain Institute, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
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2
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Wang CS, McCarthy CI, Guzikowski NJ, Kavalali ET, Monteggia LM. Brain-derived neurotrophic factor scales presynaptic calcium transients to modulate excitatory neurotransmission. Proc Natl Acad Sci U S A 2024; 121:e2303664121. [PMID: 38621124 PMCID: PMC11047077 DOI: 10.1073/pnas.2303664121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 02/28/2024] [Indexed: 04/17/2024] Open
Abstract
Brain-derived neurotrophic factor (BDNF) plays a critical role in synaptic physiology, as well as mechanisms underlying various neuropsychiatric diseases and their treatment. Despite its clear physiological role and disease relevance, BDNF's function at the presynaptic terminal, a fundamental unit of neurotransmission, remains poorly understood. In this study, we evaluated single synapse dynamics using optical imaging techniques in hippocampal cell cultures. We find that exogenous BDNF selectively increases evoked excitatory neurotransmission without affecting spontaneous neurotransmission. However, acutely blocking endogenous BDNF has no effect on evoked or spontaneous release, demonstrating that different approaches to studying BDNF may yield different results. When we suppressed BDNF-Tropomyosin receptor kinase B (TrkB) activity chronically over a period of days to weeks using a mouse line enabling conditional knockout of TrkB, we found that evoked glutamate release was significantly decreased while spontaneous release remained unchanged. Moreover, chronic blockade of BDNF-TrkB activity selectively downscales evoked calcium transients without affecting spontaneous calcium events. Via pharmacological blockade by voltage-gated calcium channel (VGCC) selective blockers, we found that the changes in evoked calcium transients are mediated by the P/Q subtype of VGCCs. These results suggest that BDNF-TrkB activity increases presynaptic VGCC activity to selectively increase evoked glutamate release.
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Affiliation(s)
- Camille S. Wang
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN3729-7933
- Department of Pharmacology, Vanderbilt University, Nashville, TN37240-7933
| | - Clara I. McCarthy
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN3729-7933
- Department of Pharmacology, Vanderbilt University, Nashville, TN37240-7933
| | - Natalie J. Guzikowski
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN3729-7933
- Department of Pharmacology, Vanderbilt University, Nashville, TN37240-7933
| | - Ege T. Kavalali
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN3729-7933
- Department of Pharmacology, Vanderbilt University, Nashville, TN37240-7933
| | - Lisa M. Monteggia
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN3729-7933
- Department of Pharmacology, Vanderbilt University, Nashville, TN37240-7933
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3
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Moya-Alvarado G, Valero-Peña X, Aguirre-Soto A, Bustos FJ, Lazo OM, Bronfman FC. PLC-γ-Ca 2+ pathway regulates axonal TrkB endocytosis and is required for long-distance propagation of BDNF signaling. Front Mol Neurosci 2024; 17:1009404. [PMID: 38660384 PMCID: PMC11040097 DOI: 10.3389/fnmol.2024.1009404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 03/25/2024] [Indexed: 04/26/2024] Open
Abstract
Brain-derived neurotrophic factor (BDNF) and its tropomyosin receptor kinase B (TrkB) are important signaling proteins that regulate dendritic growth and maintenance in the central nervous system (CNS). After binding of BDNF, TrkB is endocytosed into endosomes and continues signaling within the cell soma, dendrites, and axon. In previous studies, we showed that BDNF signaling initiated in axons triggers long-distance signaling, inducing dendritic arborization in a CREB-dependent manner in cell bodies, processes that depend on axonal dynein and TrkB activities. The binding of BDNF to TrkB triggers the activation of different signaling pathways, including the ERK, PLC-γ and PI3K-mTOR pathways, to induce dendritic growth and synaptic plasticity. How TrkB downstream pathways regulate long-distance signaling is unclear. Here, we studied the role of PLC-γ-Ca2+ in BDNF-induced long-distance signaling using compartmentalized microfluidic cultures. We found that dendritic branching and CREB phosphorylation induced by axonal BDNF stimulation require the activation of PLC-γ in the axons of cortical neurons. Locally, in axons, BDNF increases PLC-γ phosphorylation and induces intracellular Ca2+ waves in a PLC-γ-dependent manner. In parallel, we observed that BDNF-containing signaling endosomes transport to the cell body was dependent on PLC-γ activity and intracellular Ca2+ stores. Furthermore, the activity of PLC-γ is required for BDNF-dependent TrkB endocytosis, suggesting a role for the TrkB/PLC-γ signaling pathway in axonal signaling endosome formation.
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Affiliation(s)
- Guillermo Moya-Alvarado
- Faculty of Biological Sciences, Pontificia Universidad Catolica de Chile (UC), Santiago, Chile
| | - Xavier Valero-Peña
- NeuroSignaling Laboratory, Institute of Biomedical Sciences (ICB), Faculty of Medicine and Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile
| | - Alejandro Aguirre-Soto
- NeuroSignaling Laboratory, Institute of Biomedical Sciences (ICB), Faculty of Medicine and Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile
| | - Fernando J. Bustos
- Constantin-Paton Research Laboratory, Institute of Biomedical Sciences (ICB), Faculty of Medicine and Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile
| | - Oscar M. Lazo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Francisca C. Bronfman
- NeuroSignaling Laboratory, Institute of Biomedical Sciences (ICB), Faculty of Medicine and Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile
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4
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Xiong HY, Hendrix J, Schabrun S, Wyns A, Campenhout JV, Nijs J, Polli A. The Role of the Brain-Derived Neurotrophic Factor in Chronic Pain: Links to Central Sensitization and Neuroinflammation. Biomolecules 2024; 14:71. [PMID: 38254671 PMCID: PMC10813479 DOI: 10.3390/biom14010071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/02/2024] [Accepted: 01/03/2024] [Indexed: 01/24/2024] Open
Abstract
Chronic pain is sustained, in part, through the intricate process of central sensitization (CS), marked by maladaptive neuroplasticity and neuronal hyperexcitability within central pain pathways. Accumulating evidence suggests that CS is also driven by neuroinflammation in the peripheral and central nervous system. In any chronic disease, the search for perpetuating factors is crucial in identifying therapeutic targets and developing primary preventive strategies. The brain-derived neurotrophic factor (BDNF) emerges as a critical regulator of synaptic plasticity, serving as both a neurotransmitter and neuromodulator. Mounting evidence supports BDNF's pro-nociceptive role, spanning from its pain-sensitizing capacity across multiple levels of nociceptive pathways to its intricate involvement in CS and neuroinflammation. Moreover, consistently elevated BDNF levels are observed in various chronic pain disorders. To comprehensively understand the profound impact of BDNF in chronic pain, we delve into its key characteristics, focusing on its role in underlying molecular mechanisms contributing to chronic pain. Additionally, we also explore the potential utility of BDNF as an objective biomarker for chronic pain. This discussion encompasses emerging therapeutic approaches aimed at modulating BDNF expression, offering insights into addressing the intricate complexities of chronic pain.
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Affiliation(s)
- Huan-Yu Xiong
- Pain in Motion Research Group (PAIN), Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, 1090 Brussels, Belgium; (H.-Y.X.); (J.H.); (A.W.); (J.V.C.); (A.P.)
| | - Jolien Hendrix
- Pain in Motion Research Group (PAIN), Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, 1090 Brussels, Belgium; (H.-Y.X.); (J.H.); (A.W.); (J.V.C.); (A.P.)
- Department of Public Health and Primary Care, Centre for Environment & Health, KU Leuven, 3000 Leuven, Belgium
- Research Foundation—Flanders (FWO), 1000 Brussels, Belgium
| | - Siobhan Schabrun
- The School of Physical Therapy, University of Western Ontario, London, ON N6A 3K7, Canada;
- The Gray Centre for Mobility and Activity, Parkwood Institute, London, ON N6A 4V2, Canada
| | - Arne Wyns
- Pain in Motion Research Group (PAIN), Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, 1090 Brussels, Belgium; (H.-Y.X.); (J.H.); (A.W.); (J.V.C.); (A.P.)
| | - Jente Van Campenhout
- Pain in Motion Research Group (PAIN), Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, 1090 Brussels, Belgium; (H.-Y.X.); (J.H.); (A.W.); (J.V.C.); (A.P.)
| | - Jo Nijs
- Pain in Motion Research Group (PAIN), Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, 1090 Brussels, Belgium; (H.-Y.X.); (J.H.); (A.W.); (J.V.C.); (A.P.)
- Chronic Pain Rehabilitation, Department of Physical Medicine and Physiotherapy, University Hospital Brussels, 1090 Brussels, Belgium
- Department of Health and Rehabilitation, Unit of Physiotherapy, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, 41390 Göterbog, Sweden
| | - Andrea Polli
- Pain in Motion Research Group (PAIN), Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, 1090 Brussels, Belgium; (H.-Y.X.); (J.H.); (A.W.); (J.V.C.); (A.P.)
- Department of Public Health and Primary Care, Centre for Environment & Health, KU Leuven, 3000 Leuven, Belgium
- Research Foundation—Flanders (FWO), 1000 Brussels, Belgium
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5
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Riggs LM, Pereira EFR, Thompson SM, Gould TD. cAMP-dependent protein kinase signaling is required for ( 2R,6R)-hydroxynorketamine to potentiate hippocampal glutamatergic transmission. J Neurophysiol 2024; 131:64-74. [PMID: 38050689 DOI: 10.1152/jn.00326.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 11/10/2023] [Accepted: 11/23/2023] [Indexed: 12/06/2023] Open
Abstract
(2R,6R)-Hydroxynorketamine (HNK) is a ketamine metabolite that shows rapid antidepressant-like effects in preclinical studies and lacks the adverse N-methyl-d-aspartate receptor (NMDAR) inhibition-related properties of ketamine. Investigating how (2R,6R)-HNK exerts its antidepressant actions may be informative in the design of novel pharmacotherapies with improved safety and efficacy. We sought to identify the molecular substrates through which (2R,6R)-HNK induces functional changes at excitatory synapses, a prevailing hypothesis for how rapid antidepressant effects are initiated. We recorded excitatory postsynaptic potentials in hippocampal slices from male Wistar Kyoto rats, which have impaired hippocampal plasticity and are resistant to traditional antidepressants. (2R,6R)-HNK (10 µM) led to a rapid potentiation of electrically evoked excitatory postsynaptic potentials at Schaffer collateral CA1 stratum radiatum synapses. This potentiation was associated with a decrease in paired pulse facilitation, suggesting an increase in the probability of glutamate release. The (2R,6R)-HNK-induced potentiation was blocked by inhibiting either cyclic adenosine monophosphate (cAMP) or its downstream target, cAMP-dependent protein kinase (PKA). As cAMP is a potent regulator of brain-derived neurotrophic factor (BDNF) release, we assessed whether (2R,6R)-HNK exerts this acute potentiation through a rapid increase in cAMP-dependent BDNF-TrkB signaling. We found that the cAMP-PKA-dependent potentiation was not dependent on TrkB activation by BDNF, which functionally delimits the acute synaptic effects of (2R,6R)-HNK from its sustained BDNF-dependent actions in vivo. These results suggest that, by potentiating glutamate release via cAMP-PKA signaling, (2R,6R)-HNK initiates acute adaptations in fast excitatory synaptic transmission that promote structural plasticity leading to maintained antidepressant action.NEW & NOTEWORTHY Ketamine is a rapid-acting antidepressant and its preclinical effects are mimicked by its (2R,6R)-(HNK) metabolite. We found that (2R,6R)-HNK initiates acute adaptations in fast excitatory synaptic transmission by potentiating glutamate release via cAMP-PKA signaling at hippocampal Schaffer collateral synapses. This cAMP-PKA-dependent potentiation was not dependent on TrkB activation by BDNF, which functionally delimits the rapid synaptic effects of (2R,6R)-HNK from its sustained BDNF-dependent actions that are thought to maintain antidepressant action in vivo.
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Affiliation(s)
- Lace M Riggs
- Program in Neuroscience and Training Program in Integrative Membrane Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - Edna F R Pereira
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland, United States
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - Scott M Thompson
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, United States
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - Todd D Gould
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, United States
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland, United States
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States
- Veterans Affairs Maryland Health Care System, Baltimore, Maryland, United States
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6
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Thakkar B, Acevedo EO. BDNF as a biomarker for neuropathic pain: Consideration of mechanisms of action and associated measurement challenges. Brain Behav 2023; 13:e2903. [PMID: 36722793 PMCID: PMC10013954 DOI: 10.1002/brb3.2903] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 01/08/2023] [Accepted: 01/16/2023] [Indexed: 02/02/2023] Open
Abstract
INTRODUCTION The primary objective of this paper is to (1) provide a summary of human studies that have used brain derived neurotrophic factor (BDNF) as a biomarker, (2) review animal studies that help to elucidate the mechanistic involvement of BDNF in the development and maintenance of neuropathic pain (NP), and (3) provide a critique of the existing measurement techniques to highlight the limitations of the methods utilized to quantify BDNF in different biofluids in the blood (i.e., serum and plasma) with the intention of presenting a case for the most reliable and valid technique. Lastly, this review also explores potential moderators that can influence the measurement of BDNF and provides recommendations to standardize its quantification to reduce the inconsistencies across studies. METHODS In this manuscript we examined the literature on BDNF, focusing on its role as a biomarker, its mechanism of action in NP, and critically analyzed its measurement in serum and plasma to identify factors that contribute to the discrepancy in results between plasma and serum BDNF values. RESULTS A large heterogenous literature was reviewed that detailed BDNF's utility as a potential biomarker in healthy volunteers, patients with chronic pain, and patients with neuropsychiatric disorders but demonstrated inconsistent findings. The literature provides insight into the mechanism of action of BDNF at different levels of the central nervous system using animal studies. We identified multiple factors that influence the measurement of BDNF in serum and plasma and based on current evidence, we recommend assessing serum BDNF levels to quantify peripheral BDNF as they are more stable and sensitive to changes than plasma BDNF. CONCLUSION Although mechanistic studies clearly explain the role of BDNF, results from human studies are inconsistent. More studies are needed to evaluate the methodological challenges in using serum BDNF as a biomarker in NP.
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Affiliation(s)
- Bhushan Thakkar
- Department of Physical Therapy, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Edmund O Acevedo
- Department of Kinesiology and Health Sciences, Virginia Commonwealth University, Richmond, Virginia, USA
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Fries GR, Saldana VA, Finnstein J, Rein T. Molecular pathways of major depressive disorder converge on the synapse. Mol Psychiatry 2023; 28:284-297. [PMID: 36203007 PMCID: PMC9540059 DOI: 10.1038/s41380-022-01806-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 104.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 09/07/2022] [Accepted: 09/14/2022] [Indexed: 01/07/2023]
Abstract
Major depressive disorder (MDD) is a psychiatric disease of still poorly understood molecular etiology. Extensive studies at different molecular levels point to a high complexity of numerous interrelated pathways as the underpinnings of depression. Major systems under consideration include monoamines, stress, neurotrophins and neurogenesis, excitatory and inhibitory neurotransmission, mitochondrial dysfunction, (epi)genetics, inflammation, the opioid system, myelination, and the gut-brain axis, among others. This review aims at illustrating how these multiple signaling pathways and systems may interact to provide a more comprehensive view of MDD's neurobiology. In particular, considering the pattern of synaptic activity as the closest physical representation of mood, emotion, and conscience we can conceptualize, each pathway or molecular system will be scrutinized for links to synaptic neurotransmission. Models of the neurobiology of MDD will be discussed as well as future actions to improve the understanding of the disease and treatment options.
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Affiliation(s)
- Gabriel R. Fries
- grid.267308.80000 0000 9206 2401Translational Psychiatry Program, Faillace Department of Psychiatry and Behavioral Sciences, The University of Texas Health Science Center at Houston, 1941 East Rd, Houston, TX 77054 USA ,grid.240145.60000 0001 2291 4776Neuroscience Graduate Program, The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, 6767 Bertner Ave, Houston, TX 77030 USA
| | - Valeria A. Saldana
- grid.262285.90000 0000 8800 2297Frank H. Netter MD School of Medicine at Quinnipiac University, 370 Bassett Road, North Haven, CT 06473 USA
| | - Johannes Finnstein
- grid.419548.50000 0000 9497 5095Department of Translational Research in Psychiatry, Project Group Molecular Pathways of Depression, Max Planck Institute of Psychiatry, Kraepelinstr. 10, 80804 Munich, Germany
| | - Theo Rein
- Department of Translational Research in Psychiatry, Project Group Molecular Pathways of Depression, Max Planck Institute of Psychiatry, Kraepelinstr. 10, 80804, Munich, Germany.
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Bazzari AH, Bazzari FH. BDNF Therapeutic Mechanisms in Neuropsychiatric Disorders. Int J Mol Sci 2022; 23:ijms23158417. [PMID: 35955546 PMCID: PMC9368938 DOI: 10.3390/ijms23158417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 11/16/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is the most abundant neurotrophin in the adult brain and functions as both a primary neurotrophic signal and a neuromodulator. It serves essential roles in neuronal development, maintenance, transmission, and plasticity, thereby influencing aging, cognition, and behavior. Accumulating evidence associates reduced central and peripheral BDNF levels with various neuropsychiatric disorders, supporting its potential utilization as a biomarker of central pathologies. Subsequently, extensive research has been conducted to evaluate restoring, or otherwise augmenting, BDNF transmission as a potential therapeutic approach. Promising results were indeed observed for genetic BDNF upregulation or exogenous administration using a multitude of murine models of neurological and psychiatric diseases. However, varying mechanisms have been proposed to underlie the observed therapeutic effects, and many findings indicate the engagement of disease-specific and other non-specific mechanisms. This is because BDNF essentially affects all aspects of neuronal cellular function through tropomyosin receptor kinase B (TrkB) receptor signaling, the disruptions of which vary between brain regions across different pathologies leading to diversified consequences on cognition and behavior. Herein, we review the neurophysiology of BDNF transmission and signaling and classify the converging and diverging molecular mechanisms underlying its therapeutic potentials in neuropsychiatric disorders. These include neuroprotection, synaptic maintenance, immunomodulation, plasticity facilitation, secondary neuromodulation, and preservation of neurovascular unit integrity and cellular viability. Lastly, we discuss several findings suggesting BDNF as a common mediator of the therapeutic actions of centrally acting pharmacological agents used in the treatment of neurological and psychiatric illness.
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Affiliation(s)
- Amjad H. Bazzari
- Faculty of Medicine, Arab American University, 13 Zababdeh, Jenin 240, Palestine
- Correspondence:
| | - Firas H. Bazzari
- Faculty of Pharmacy, Arab American University, 13 Zababdeh, Jenin 240, Palestine;
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Wang CS, Kavalali ET, Monteggia LM. BDNF signaling in context: From synaptic regulation to psychiatric disorders. Cell 2022; 185:62-76. [PMID: 34963057 PMCID: PMC8741740 DOI: 10.1016/j.cell.2021.12.003] [Citation(s) in RCA: 163] [Impact Index Per Article: 81.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 10/10/2021] [Accepted: 12/02/2021] [Indexed: 01/09/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) is a neuropeptide that plays numerous important roles in synaptic development and plasticity. While its importance in fundamental physiology is well established, studies of BDNF often produce conflicting and unclear results, and the scope of existing research makes the prospect of setting future directions daunting. In this review, we examine the importance of spatial and temporal factors on BDNF activity, particularly in processes such as synaptogenesis, Hebbian plasticity, homeostatic plasticity, and the treatment of psychiatric disorders. Understanding the fundamental physiology of when, where, and how BDNF acts and new approaches to control BDNF signaling in time and space can contribute to improved therapeutics and patient outcomes.
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Affiliation(s)
- Camille S Wang
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232-2050, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA
| | - Ege T Kavalali
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232-2050, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA
| | - Lisa M Monteggia
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232-2050, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA.
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Plantar Stimulations during 3-Day Hindlimb Unloading Prevent Loss of Neural Progenitors and Maintain ERK1/2 Activity in the Rat Hippocampus. Life (Basel) 2021; 11:life11050449. [PMID: 34067876 PMCID: PMC8157184 DOI: 10.3390/life11050449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/09/2021] [Accepted: 05/14/2021] [Indexed: 12/23/2022] Open
Abstract
Adult neurogenesis is a flexible process that depends on the environment and correlates with cognitive functions. Cognitive functions are impaired by various factors including space flight conditions and reduced physical activity. Physically active life significantly improves both cognition and the hippocampal neurogenesis. Here, we analyzed how 3-day simulated microgravity caused by hindlimb unloading (HU) or dynamic foot stimulation (DFS) during HU can affect the hippocampal neurogenesis. Adult Wistar rats were recruited in the experiments. The results demonstrated a decrease in the number of doublecortine (DCX) positive neural progenitors, but proliferation in the subgranular zone of the dentate gyrus was not changed after 3-day HU. Analysis of the effects of DFS showed restoration of neural progenitor population in the subgranular zone of the dentate gyrus. Additionally, we analyzed activity of the cRaf/ERK1/2 pathway, which is one of the major players in the regulation of neuronal differentiation. The results demonstrated inhibition of cRaf/ERK1/2 signaling in the hippocampus of HU rats. In DFS rats, no changes in the activity of cRaf/ERK1/2 were observed. Thus, we demonstrated that the process of neurogenesis fading during HU begins with inhibition of the formation of immature neurons and associated ERK1/2 signaling activity, while DFS prevents the development of mentioned alterations.
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11
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Lisek M, Zylinska L, Boczek T. Ketamine and Calcium Signaling-A Crosstalk for Neuronal Physiology and Pathology. Int J Mol Sci 2020; 21:ijms21218410. [PMID: 33182497 PMCID: PMC7665128 DOI: 10.3390/ijms21218410] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/31/2020] [Accepted: 11/05/2020] [Indexed: 12/12/2022] Open
Abstract
Ketamine is a non-competitive antagonist of NMDA (N-methyl-D-aspartate) receptor, which has been in clinical practice for over a half century. Despite recent data suggesting its harmful side effects, such as neuronal loss, synapse dysfunction or disturbed neural network formation, the drug is still applied in veterinary medicine and specialist anesthesia. Several lines of evidence indicate that structural and functional abnormalities in the nervous system caused by ketamine are crosslinked with the imbalanced activity of multiple Ca2+-regulated signaling pathways. Due to its ubiquitous nature, Ca2+ is also frequently located in the center of ketamine action, although the precise mechanisms underlying drug’s negative or therapeutic properties remain mysterious for the large part. This review seeks to delineate the relationship between ketamine-triggered imbalance in Ca2+ homeostasis and functional consequences for downstream processes regulating key aspects of neuronal function.
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12
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Niculescu D, Michaelsen-Preusse K, Güner Ü, van Dorland R, Wierenga CJ, Lohmann C. A BDNF-Mediated Push-Pull Plasticity Mechanism for Synaptic Clustering. Cell Rep 2020; 24:2063-2074. [PMID: 30134168 DOI: 10.1016/j.celrep.2018.07.073] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 06/12/2018] [Accepted: 07/23/2018] [Indexed: 01/09/2023] Open
Abstract
During development, activity-dependent synaptic plasticity refines neuronal networks with high precision. For example, spontaneous activity helps sorting synaptic inputs with similar activity patterns into clusters to enhance neuronal computations in the mature brain. Here, we show that TrkB activation and postsynaptic brain-derived neurotrophic factor (BDNF) are required for synaptic clustering in developing hippocampal neurons. Moreover, BDNF and TrkB modulate transmission at synapses depending on their clustering state, indicating that endogenous BDNF/TrkB signaling stabilizes locally synchronized synapses. Together with our previous data on proBDNF/p75NTR signaling, these findings suggest a push-pull plasticity mechanism for synaptic clustering: BDNF stabilizes clustered synapses while proBDNF downregulates out-of-sync synapses. This idea is supported by our observation that synaptic clustering requires matrix-metalloproteinase-9 activity, a proBDNF-to-BDNF converting enzyme. Finally, NMDA receptor activation mediates out-of-sync depression upstream of proBDNF signaling. Together, these data delineate an efficient plasticity mechanism where proBDNF and mature BDNF establish synaptic clustering through antagonistic modulation of synaptic transmission.
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Affiliation(s)
- Dragos Niculescu
- Department of Synapse and Network Development, Netherlands Institute for Neuroscience, 1105 Amsterdam, the Netherlands; Department of Neurogenesis and Circuit Development, Vision Institute, 75012 Paris, France
| | - Kristin Michaelsen-Preusse
- Department of Synapse and Network Development, Netherlands Institute for Neuroscience, 1105 Amsterdam, the Netherlands
| | - Ülkü Güner
- Department of Synapse and Network Development, Netherlands Institute for Neuroscience, 1105 Amsterdam, the Netherlands
| | - René van Dorland
- Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, the Netherlands
| | - Corette J Wierenga
- Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, the Netherlands
| | - Christian Lohmann
- Department of Synapse and Network Development, Netherlands Institute for Neuroscience, 1105 Amsterdam, the Netherlands; Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University, Amsterdam, the Netherlands.
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13
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Regulation of Acetylcholine Quantal Release by Coupled Thrombin/BDNF Signaling in Mouse Motor Synapses. Cells 2019; 8:cells8070762. [PMID: 31336670 PMCID: PMC6678150 DOI: 10.3390/cells8070762] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 07/13/2019] [Accepted: 07/22/2019] [Indexed: 12/23/2022] Open
Abstract
The aim of this study was to compare the acute effects of thrombin and brain-derived neurotrophic factor (BDNF) on spontaneous miniature endplate potentials (MEPPs) and multiquantal evoked endplate potentials (EPPs) in mouse neuromuscular junctions (NMJs) of m. diaphragma and m. EDL. Intracellular microelectrode recordings of MEPPs and EPPs were used to evaluate the changes in acetylcholine (ACh) release in mature and newly-formed mouse NMJs. Thrombin (1 nM) increased the amplitude of MEPPs and EPPs by 25–30% in mature and newly-formed NMJs. This effect was due to an enhanced loading of synaptic vesicles with ACh and increase of ACh quantal size, since it was fully prevented by blocking of vesicular ACh transporter. It was also prevented by tropomyosin-related kinase B (TrkB) receptors inhibitor ANA12. Exogenous BDNF (1 nM) mimicked thrombin effect and increased the amplitude of MEPPs and EPPs by 25–30%. It required involvement of protein kinase A (PKA) and mitogen-activated protein kinase (MEK1/2)-mediated pathway, but not phospholipase C (PLC). Blocking A2A adenosine receptors by ZM241385 abolished the effect of BDNF, whereas additional stimulation of A2A receptors by CGS21680 increased MEPP amplitudes, which was prevented by MEK1/2 inhibitor U0126. At mature NMJs, BDNF enhanced MEPPs frequency by 30–40%. This effect was selectively prevented by inhibition of PLC, but not PKA or MEK1/2. It is suggested that interrelated effects of thrombin/BDNF in mature and newly-formed NMJs are realized via enhancement of vesicular ACh transport and quantal size increase. BDNF-induced potentiation of synaptic transmission involves the functional coupling between A2A receptor-dependent active PKA and neurotrophin-triggered MAPK pathway, as well as PLC-dependent increase in frequency of MEPPs.
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14
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Deyama S, Bang E, Kato T, Li XY, Duman RS. Neurotrophic and Antidepressant Actions of Brain-Derived Neurotrophic Factor Require Vascular Endothelial Growth Factor. Biol Psychiatry 2019; 86:143-152. [PMID: 30712809 PMCID: PMC6597338 DOI: 10.1016/j.biopsych.2018.12.014] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 12/17/2018] [Accepted: 12/17/2018] [Indexed: 12/28/2022]
Abstract
BACKGROUND Activity-dependent release of brain-derived neurotrophic factor (BDNF) in the medial prefrontal cortex (mPFC) is essential for the rapid and sustained antidepressant actions of ketamine, and a recent study shows a similar requirement for vascular endothelial growth factor (VEGF). Since BDNF is reported to stimulate VEGF expression and/or release in neuroblastoma cells, the present study tested the hypothesis that the actions of BDNF are mediated by VEGF. METHODS The role of VEGF in the antidepressant behavioral actions of BDNF was tested by intra-mPFC coinfusion of a VEGF neutralizing antibody and by neuron-specific deletion of VEGF. The influence of BDNF on the release of VEGF and the role of VEGF in the neurotrophic actions of BDNF were determined in rat primary cortical neurons. The role of BDNF in the behavioral and neurotrophic actions of VEGF was also determined. RESULTS The results show that the rapid and sustained antidepressant-like actions of intra-mPFC BDNF are blocked by coinfusion of a VEGF neutralizing antibody, and that neuron-specific mPFC deletion of VEGF blocks the antidepressant-like actions of BDNF. Studies in primary cortical neurons demonstrate that BDNF stimulates the release of VEGF and that BDNF induction of dendrite complexity is blocked by a selective VEGF-fetal liver kinase 1 receptor antagonist. Surprisingly, the results also show reciprocal interactions, indicating that the behavioral and neurotrophic actions of VEGF are dependent on BDNF. CONCLUSIONS These findings indicate that the antidepressant-like and neurotrophic actions of BDNF require VEGF signaling, but they also demonstrate reciprocal interdependence for BDNF in the actions of VEGF.
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Affiliation(s)
- Satoshi Deyama
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA.,Laboratory of Molecular Pharmacology, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-1192, Japan
| | - Eunyoung Bang
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA
| | - Taro Kato
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA.,Drug Development Research Laboratories, Sumitomo Dainippon Pharma Co., Ltd., Suita 564-0053, Japan
| | - Xiao-Yuan Li
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA
| | - Ronald S. Duman
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA.,Correspondence: Ronald S. Duman, Ph.D., Department of Psychiatry, Yale University School of Medicine, 34 Park Street, New Haven, CT 06519, USA. Tel: 203-974-7726, Fax: 203-974-7724,
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15
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Jang M, Gould E, Xu J, Kim EJ, Kim JH. Oligodendrocytes regulate presynaptic properties and neurotransmission through BDNF signaling in the mouse brainstem. eLife 2019; 8:42156. [PMID: 30998186 PMCID: PMC6504230 DOI: 10.7554/elife.42156] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 04/17/2019] [Indexed: 12/17/2022] Open
Abstract
Neuron–glia communication contributes to the fine-tuning of synaptic functions. Oligodendrocytes near synapses detect and respond to neuronal activity, but their role in synapse development and plasticity remains largely unexplored. We show that oligodendrocytes modulate neurotransmitter release at presynaptic terminals through secretion of brain-derived neurotrophic factor (BDNF). Oligodendrocyte-derived BDNF functions via presynaptic tropomyosin receptor kinase B (TrkB) to ensure fast, reliable neurotransmitter release and auditory transmission in the developing brain. In auditory brainstem slices from Bdnf+/– mice, reduction in endogenous BDNF significantly decreased vesicular glutamate release by reducing the readily releasable pool of glutamate vesicles, without altering presynaptic Ca2+ channel activation or release probability. Using conditional knockout mice, cell-specific ablation of BDNF in oligodendrocytes largely recapitulated this effect, which was recovered by BDNF or TrkB agonist application. This study highlights a novel function for oligodendrocytes in synaptic transmission and their potential role in the activity-dependent refinement of presynaptic properties.
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Affiliation(s)
- Miae Jang
- The Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, United States
| | - Elizabeth Gould
- The Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, United States
| | - Jie Xu
- The Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, United States.,Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Eun Jung Kim
- The Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, United States
| | - Jun Hee Kim
- The Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, United States
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Naletova I, Satriano C, Pietropaolo A, Gianì F, Pandini G, Triaca V, Amadoro G, Latina V, Calissano P, Travaglia A, Nicoletti VG, La Mendola D, Rizzarelli E. The Copper(II)-Assisted Connection between NGF and BDNF by Means of Nerve Growth Factor-Mimicking Short Peptides. Cells 2019; 8:E301. [PMID: 30939824 PMCID: PMC6523629 DOI: 10.3390/cells8040301] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 03/23/2019] [Accepted: 03/30/2019] [Indexed: 01/16/2023] Open
Abstract
Nerve growth factor (NGF) is a protein necessary for development and maintenance of the sympathetic and sensory nervous systems. We have previously shown that the NGF N-terminus peptide NGF(1-14) is sufficient to activate TrkA signaling pathways essential for neuronal survival and to induce an increase in brain-derived neurotrophic factor (BDNF) expression. Cu2+ ions played a critical role in the modulation of the biological activity of NGF(1-14). Using computational, spectroscopic, and biochemical techniques, here we report on the ability of a newly synthesized peptide named d-NGF(1-15), which is the dimeric form of NGF(1-14), to interact with TrkA. We found that d-NGF(1-15) interacts with the TrkA-D5 domain and induces the activation of its signaling pathways. Copper binding to d-NGF(1-15) stabilizes the secondary structure of the peptides, suggesting a strengthening of the noncovalent interactions that allow for the molecular recognition of D5 domain of TrkA and the activation of the signaling pathways. Intriguingly, the signaling cascade induced by the NGF peptides ultimately involves cAMP response element-binding protein (CREB) activation and an increase in BDNF protein level, in keeping with our previous result showing an increase of BDNF mRNA. All these promising connections can pave the way for developing interesting novel drugs for neurodegenerative diseases.
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Affiliation(s)
- Irina Naletova
- Department of Chemical Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy.
| | - Cristina Satriano
- Department of Chemical Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy.
| | - Adriana Pietropaolo
- Department of Health Sciences, University of Catanzaro, Campus Universitario Viale Europa, 88100 Catanzaro, Italy.
| | - Fiorenza Gianì
- Endocrinology, Department of Clinical and Experimental Medicine, Garibaldi-Nesima Medical Center, University of Catania, via Palermo n. 636, 95122 Catania, Italy.
| | - Giuseppe Pandini
- Endocrinology, Department of Clinical and Experimental Medicine, Garibaldi-Nesima Medical Center, University of Catania, via Palermo n. 636, 95122 Catania, Italy.
| | - Viviana Triaca
- Medicina Molecolare e Traslazionale "Rita Levi Montalcini", Institute of Cellular Biology and Neurobiology (IBCN), National Research Council (CNR), c/o Policlinico Umberto I, University of Rome "La Sapienza", Via del Policlinico 255, 00161 Rome, Italy.
| | - Giuseppina Amadoro
- Institute of Translational Pharmacology (IFT), National Research Council (CNR), 00131 Rome, Italy.
| | - Valentina Latina
- European Brain Research Institute, Viale Regina Elena 295, 00161, 64-65, 00143 Rome, Italy.
| | - Pietro Calissano
- European Brain Research Institute, Viale Regina Elena 295, 00161, 64-65, 00143 Rome, Italy.
| | - Alessio Travaglia
- Department of Chemical Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy.
| | - Vincenzo Giuseppe Nicoletti
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, University of Catania, 95124 Catania, Italy.
| | - Diego La Mendola
- Department of Pharmacy, University of Pisa, Via Bonanno Pisano 6, 56126 Pisa, Italy.
| | - Enrico Rizzarelli
- Department of Chemical Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy.
- Institute of Crystallography-Catania, National Research Council (CNR), Via P. Gaifami, 95126 Catania, Italy.
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17
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BDNF Val66Met polymorphism is associated with altered activity-dependent modulation of short-interval intracortical inhibition in bilateral M1. PLoS One 2018; 13:e0197505. [PMID: 29856758 PMCID: PMC5983496 DOI: 10.1371/journal.pone.0197505] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 05/03/2018] [Indexed: 11/19/2022] Open
Abstract
The BDNF Val66Met polymorphism is associated with impaired short-term plasticity in the motor cortex, short-term motor learning, and intermanual transfer of a procedural motor skill. Here, we investigated the impact of the Val66Met polymorphism on the modulation of cortical excitability and interhemispheric inhibition through sensorimotor practice of simple dynamic skills with the right and left first dorsal interosseous (FDI) muscles. To that end, we compared motor evoked potentials (MEP) amplitudes and short-interval intracortical inhibition (SICI) in the bilateral representations of the FDI muscle in the primary motor cortex (M1), and interhemispheric inhibition (IHI) from the left to right M1, before and after right and left FDI muscle training in an alternated sequence. Val66Met participants did not differ from their Val66Val counterparts on motor performance at baseline and following motor training, or on measures of MEP amplitude and IHI. However, while the Val66Val group displayed significant SICI reduction in the bilateral M1 in response to motor training, SICI remained unchanged in the Val66Met group. Further, Val66Val group's SICI decrease in the left M1, which was also observed following unimanual training with the right hand in the Control Right group, was correlated with motor improvement with the left hand. The potential interaction between left and right M1 activity during bimanual training and the implications of altered activity-dependent cortical excitability on short-term motor learning in Val66Met carriers are discussed.
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18
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Kao HT, Ryoo K, Lin A, Janoschka SR, Augustine GJ, Porton B. Synapsins regulate brain-derived neurotrophic factor-mediated synaptic potentiation and axon elongation by acting on membrane rafts. Eur J Neurosci 2017; 45:1085-1101. [PMID: 28245069 DOI: 10.1111/ejn.13552] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 01/27/2017] [Accepted: 02/15/2017] [Indexed: 11/29/2022]
Abstract
In neurons, intracellular membrane rafts are essential for specific actions of brain-derived neurotrophic factor (BDNF), which include the regulation of axon outgrowth, growth cone turning and synaptic transmission. Virtually, all the actions of BDNF are mediated by binding to its receptor, TrkB. The association of TrkB with the tyrosine kinase, Fyn, is critical for its localization to intracellular membrane rafts. Here, we show that synapsins, a family of highly amphipathic neuronal phosphoproteins, regulate membrane raft lipid composition and consequently, the ability of BDNF to regulate axon/neurite development and potentiate synaptic transmission. In the brains of mice lacking all synapsins, the expression of both BDNF and TrkB were increased, suggesting that BDNF/TrkB-mediated signaling is impaired. Consistent with this finding, synapsin-depleted neurons exhibit altered raft lipid composition, deficient targeting of Fyn to rafts, attenuated TrkB activation, and abrogation of BDNF-stimulated axon outgrowth and synaptic potentiation. Conversely, overexpression of synapsins in neuroblastoma cells results in corresponding reciprocal changes in raft lipid composition, increased localization of Fyn to rafts and promotion of BDNF-stimulated neurite formation. In the presence of synapsins, the ratio of cholesterol to estimated total phospholipids converged to 1, suggesting that synapsins act by regulating the ratio of lipids in intracellular membranes, thereby promoting lipid raft formation. These studies reveal a mechanistic link between BDNF and synapsins, impacting early development and synaptic transmission.
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Affiliation(s)
- Hung-Teh Kao
- Department of Psychiatry and Human Behavior, Brown University, 171 Meeting Street, Room 187, Providence, RI, 02912, USA.,Butler Hospital, Providence, RI, USA
| | - Kanghyun Ryoo
- Center for Functional Connectomics, Korea Institute of Science and Technology, Sungbukgu, Seoul, Korea
| | - Albert Lin
- Department of Psychiatry and Human Behavior, Brown University, 171 Meeting Street, Room 187, Providence, RI, 02912, USA.,Butler Hospital, Providence, RI, USA
| | - Stephen R Janoschka
- Department of Psychiatry and Human Behavior, Brown University, 171 Meeting Street, Room 187, Providence, RI, 02912, USA.,Butler Hospital, Providence, RI, USA
| | - George J Augustine
- Center for Functional Connectomics, Korea Institute of Science and Technology, Sungbukgu, Seoul, Korea.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Barbara Porton
- Department of Psychiatry and Human Behavior, Brown University, 171 Meeting Street, Room 187, Providence, RI, 02912, USA.,Butler Hospital, Providence, RI, USA
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