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He Y, Wang F, Zhang H, Li J, Zhou H, Wen Y. Vildagliptin showed anti-epileptic effects and promoted subthreshold A-type potassium currents by regulating DPPs and Kv4s binding. Neurosci Lett 2024; 842:137970. [PMID: 39245254 DOI: 10.1016/j.neulet.2024.137970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 08/17/2024] [Accepted: 09/04/2024] [Indexed: 09/10/2024]
Abstract
The subthreshold A-type potassium current (Isa), mediated by Kv4, is a hyperpolarizing current that decreases neuronal excitability. The Kv4 accessory proteins, DPP6 and DPP10 (DPPs), modulate the current. Thus, agents that modify the binding of DPPs to these channels affect neuronal excitability. Vildagliptin inhibits DPP4, a protein with structural similarities to DPPs. In this study, we investigated whether vildagliptin, an antidiabetic medication, exhibits anti-epileptic properties. Seizures were induced in rats by injecting pentylenetetrazole (PTZ), and vildagliptin at different doses was administered one hour before the PTZ injection. Vildagliptin treatment delayed the onset of epileptiform activity and reduced seizure duration and frequency. A dose-dependent decrease in DPPs was observed in vildagliptin-treated rats. We induced epileptic activity in cultured hippocampal neurons and found that treatment with vildagliptin suppressed the firing frequency. We found that the Isa current in cultured neurons was mediated by Kv4s and suppressed in epileptic neurons. Furthermore, the Kv4s to DPPs ratio in the channel complex was decreased in epileptic neurons, but was restored to a normal level in vildagliptin-treated neurons. In conclusion, the anti-epileptic effects of vildagliptin were likely mediated by the suppression of seizure-induced DPP6 and DPP10 expression and decreased membrane excitability by restoring Isa current density via the regulation of DPPs and Kv4s binding, indicating that vildagliptin may be a novel treatment option for epileptic patients.
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Affiliation(s)
- Ya He
- Department of Physical Examination Center, Chongqing University Jiangjin Hospital, Chongqing University, Number 725, Jiangzhou Avenue, Jiangjin District, 402260 Chongqing, China
| | - Fei Wang
- Department of Neurosurgery, Chongqing University Jiangjin Hospital, Chongqing University, Number 725, Jiangzhou Avenue, Jiangjin District, 402260 Chongqing, China
| | - Hongxia Zhang
- Department of Neurosurgery, Yongchuan Hospital of Chongqing Medical University, Chongqing Medical University, Number 439, Xuanhua Road, Yongchuan District, 402160 Chongqing, China
| | - Jingang Li
- Department of Neurosurgery, Chongqing University Jiangjin Hospital, Chongqing University, Number 725, Jiangzhou Avenue, Jiangjin District, 402260 Chongqing, China
| | - Hui Zhou
- Department of Neurosurgery, Chongqing University Jiangjin Hospital, Chongqing University, Number 725, Jiangzhou Avenue, Jiangjin District, 402260 Chongqing, China
| | - Yuetao Wen
- Department of Neurosurgery, Chongqing University Jiangjin Hospital, Chongqing University, Number 725, Jiangzhou Avenue, Jiangjin District, 402260 Chongqing, China.
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Hu JH, Liu Y, Hoffman DA. Identification of Kv4.2 protein complex and modifications by tandem affinity purification-mass spectrometry in primary neurons. Front Cell Neurosci 2022; 16:1070305. [PMID: 36568885 PMCID: PMC9788671 DOI: 10.3389/fncel.2022.1070305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 11/24/2022] [Indexed: 12/13/2022] Open
Abstract
Proteins usually form complexes to fulfill variable physiological functions. In neurons, communication relies on synapses where receptors, channels, and anchoring proteins form complexes to precisely control signal transduction, synaptic integration, and action potential firing. Although there are many published protocols to isolate protein complexes in cell lines, isolation in neurons has not been well established. Here we introduce a method that combines lentiviral protein expression with tandem affinity purification followed by mass-spectrometry (TAP-MS) to identify protein complexes in neurons. This protocol can also be used to identify post-translational modifications (PTMs) of synaptic proteins. We used the A-type voltage-gated K+ channel subunit Kv4.2 as the target protein. Kv4.2 is highly expressed in the hippocampus where it contributes to learning and memory through its regulation of neuronal excitability and synaptic plasticity. We tagged Kv4.2 with the calmodulin-binding-peptide (CBP) and streptavidin-binding-peptide (SBP) at its C-terminus and expressed it in neurons via lentivirus. Kv4.2 was purified by two-step TAP and samples were analyzed by MS. MS identified two prominently known Kv4.2 interacting proteins [dipeptidyl peptidase like (DPPs) and Kv channel-interacting proteins (KChIPs)] in addition to novel synaptic proteins including glutamate receptors, a calcium channel, and anchoring proteins. Co-immunoprecipitation and colocalization experiments validated the association of Kv4.2 with glutamate receptors. In addition to protein complex identification, we used TAP-MS to identify Kv4.2 phosphorylation sites. Several known and unknown phosphorylation sites were identified. These findings provide a novel path to identify protein-protein interactions and PTMs in neurons and shed light on mechanisms of neuronal signaling potentially involved in the pathology of neurological diseases.
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Malloy C, Ahern M, Lin L, Hoffman DA. Neuronal Roles of the Multifunctional Protein Dipeptidyl Peptidase-like 6 (DPP6). Int J Mol Sci 2022; 23:ijms23169184. [PMID: 36012450 PMCID: PMC9409431 DOI: 10.3390/ijms23169184] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/09/2022] [Accepted: 08/12/2022] [Indexed: 11/16/2022] Open
Abstract
The concerted action of voltage-gated ion channels in the brain is fundamental in controlling neuronal physiology and circuit function. Ion channels often associate in multi-protein complexes together with auxiliary subunits, which can strongly influence channel expression and function and, therefore, neuronal computation. One such auxiliary subunit that displays prominent expression in multiple brain regions is the Dipeptidyl aminopeptidase-like protein 6 (DPP6). This protein associates with A-type K+ channels to control their cellular distribution and gating properties. Intriguingly, DPP6 has been found to be multifunctional with an additional, independent role in synapse formation and maintenance. Here, we feature the role of DPP6 in regulating neuronal function in the context of its modulation of A-type K+ channels as well as its independent involvement in synaptic development. The prevalence of DPP6 in these processes underscores its importance in brain function, and recent work has identified that its dysfunction is associated with host of neurological disorders. We provide a brief overview of these and discuss research directions currently underway to advance our understanding of the contribution of DPP6 to their etiology.
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Murphy JG, Gutzmann JJ, Lin L, Hu J, Petralia RS, Wang YX, Hoffman DA. R-type voltage-gated Ca 2+ channels mediate A-type K + current regulation of synaptic input in hippocampal dendrites. Cell Rep 2022; 38:110264. [PMID: 35045307 PMCID: PMC10496648 DOI: 10.1016/j.celrep.2021.110264] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 12/02/2021] [Accepted: 12/22/2021] [Indexed: 01/22/2023] Open
Abstract
The subthreshold voltage-gated transient K+ current (IA) carried by pore-forming Kv4.2 subunits regulates the propagation of synaptic input, dendritic excitability, and synaptic plasticity in CA1 pyramidal neuron dendrites of the hippocampus. We report that the Ca2+ channel subunit Cav2.3 regulates IA in this cell type. We initially identified Cav2.3 as a Kv4.2-interacting protein in a proteomic screen and we confirmed Cav2.3-Kv4.2 complex association using multiple techniques. Functionally, Cav2.3 Ca2+-entry increases Kv4.2-mediated whole-cell current due to an increase in Kv4.2 surface expression. Using pharmacology and Cav2.3 knockout mice, we show that Cav2.3 regulates the dendritic gradient of IA. Furthermore, the loss of Cav2.3 function leads to the enhancement of AMPA receptor-mediated synaptic currents and NMDA receptor-mediated spine Ca2+ influx. These results propose that Cav2.3 and Kv4.2 are integral constituents of an ion channel complex that affects synaptic function in the hippocampus.
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Affiliation(s)
- Jonathan G Murphy
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Jakob J Gutzmann
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lin Lin
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jiahua Hu
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ronald S Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dax A Hoffman
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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Mackenzie-Gray Scott CA, Parrish RR, Walsh DA, Racca C, Cowell RM, Treveylan AJ. PV-specific loss of the transcriptional coactivator PGC-1α slows down the evolution of epileptic activity in an acute ictogenic model. J Neurophysiol 2021; 127:86-98. [PMID: 34788174 PMCID: PMC8721902 DOI: 10.1152/jn.00295.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The transcriptional coactivator, PGC-1α (peroxisome proliferator-activated receptor γ coactivator 1α), plays a key role in coordinating energy requirement within cells. Its importance is reflected in the growing number of psychiatric and neurological conditions that have been associated with reduced PGC-1α levels. In cortical networks, PGC-1α is required for the induction of parvalbumin (PV) expression in interneurons, and PGC-1α deficiency affects synchronous GABAergic release. It is unknown, however, how this affects cortical excitability. We show here that knocking down PGC-1α specifically in the PV-expressing cells (PGC-1αPV−/−) blocks the activity-dependent regulation of the synaptic proteins, SYT2 and CPLX1. More surprisingly, this cell class-specific knockout of PGC-1α appears to have a novel antiepileptic effect, as assayed in brain slices bathed in 0 Mg2+ media. The rate of occurrence of preictal discharges developed approximately equivalently in wild-type and PGC-1αPV−/− brain slices, but the intensity of these discharges was lower in PGC-1αPV−/− slices, as evident from the reduced power in the γ range and reduced firing rates in both PV interneurons and pyramidal cells during these discharges. Reflecting this reduced intensity in the preictal discharges, the PGC-1αPV−/− brain slices experienced many more discharges before transitioning into a seizure-like event. Consequently, there was a large increase in the latency to the first seizure-like event in brain slices lacking PGC-1α in PV interneurons. We conclude that knocking down PGC-1α limits the range of PV interneuron firing and this slows the pathophysiological escalation during ictogenesis. NEW & NOTEWORTHY Parvalbumin expressing interneurons are considered to play an important role in regulating cortical activity. We were surprised, therefore, to find that knocking down the transcriptional coactivator, PGC-1α, specifically in this class of interneurons appears to slow ictogenesis. This anti-ictogenic effect is associated with reduced activity in preictal discharges, but with a far longer period of these discharges before the first seizure-like events finally start. Thus, PGC-1α knockdown may promote schizophrenia while reducing epileptic tendencies.
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Affiliation(s)
| | - Robert Ryley Parrish
- Newcastle University Biosciences Institute, Medical School, Framlington Place, Newcastle upon Tyne, United Kingdom
| | - Darren A Walsh
- Newcastle University Biosciences Institute, Medical School, Framlington Place, Newcastle upon Tyne, United Kingdom
| | - Claudia Racca
- Newcastle University Biosciences Institute, Medical School, Framlington Place, Newcastle upon Tyne, United Kingdom
| | - Rita M Cowell
- Department of Neuroscience, Drug Discovery Division at Southern Research, Birmingham, AL, United States.,Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Andrew J Treveylan
- Newcastle University Biosciences Institute, Medical School, Framlington Place, Newcastle upon Tyne, United Kingdom
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Sanz-Ezquerro JJ, Cuenda A. p38 Signalling Pathway. Int J Mol Sci 2021; 22:ijms22031003. [PMID: 33498296 PMCID: PMC7863928 DOI: 10.3390/ijms22031003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 01/15/2021] [Indexed: 01/12/2023] Open
Affiliation(s)
- Juan José Sanz-Ezquerro
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología/CSIC (CNB-CSIC), Campus-UAM, 28049 Madrid, Spain
- Correspondence: (J.J.S.-E.); (A.C.); Tel.: +34-91-5855-395 (J.J.S.-E.); +34-91-5855-451 (A.C.)
| | - Ana Cuenda
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC (CNB-CSIC), Campus-UAM, 28049 Madrid, Spain
- Correspondence: (J.J.S.-E.); (A.C.); Tel.: +34-91-5855-395 (J.J.S.-E.); +34-91-5855-451 (A.C.)
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Zhou X, Chen Q, Huang H, Zhang J, Wang J, Chen Y, Peng Y, Zhang H, Zeng J, Feng Z, Xu Z. Inhibition of p38 MAPK regulates epileptic severity by decreasing expression levels of A1R and ENT1. Mol Med Rep 2020; 22:5348-5357. [PMID: 33174009 PMCID: PMC7647013 DOI: 10.3892/mmr.2020.11614] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 09/08/2020] [Indexed: 12/16/2022] Open
Abstract
Epilepsy is a chronic nervous system disease. Excessive increase of the excitatory neurotransmitter glutamate in the body results in an imbalance of neurotransmitters and excessive excitation of neurons, leading to epileptic seizures. Long‑term recurrent seizures lead to behavior and cognitive changes, and even increase the risk of death by 2‑ to 3‑fold relative to the general population. Adenosine A1 receptor (A1R), a member of the adenosine system, has notable anticonvulsant effects, and adenosine levels are controlled by the type 1 equilibrative nucleoside transporter (ENT1); in addition the p38 MAPK signaling pathway is involved in the regulation of ENT1, although the effect of its inhibitors on the expression levels of A1R and ENT1 is unclear. Therefore, in the present study, SB203580 was used to inhibit the p38 MAPK signaling pathway in rats, and the expression levels of A1R and ENT1 in the brain tissue of rats with acute LiCl‑pilocarpine‑induced status epilepticus was detected. SB203580 decreased pathological damage of hippocampal neurons, prolonged seizure latency, reduced the frequency of seizures, and decreased levels of A1R and ENT1 protein in rats.
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Affiliation(s)
- Xuejiao Zhou
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Qian Chen
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Hao Huang
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jun Zhang
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jing Wang
- Department of Prevention and Health Care, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Ya Chen
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Yan Peng
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Haiqing Zhang
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Junwei Zeng
- Department of Physiology, Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Zhanhui Feng
- Department of Neurology, Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
| | - Zucai Xu
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
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