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Zhang S, Peng B, Chen Z, Yu J, Deng G, Bao Y, Ma C, Du F, Sheu WC, Kimberly WT, Simard JM, Coman D, Chen Q, Hyder F, Zhou J, Sheth KN. Brain-targeting, acid-responsive antioxidant nanoparticles for stroke treatment and drug delivery. Bioact Mater 2022; 16:57-65. [PMID: 35386312 PMCID: PMC8958421 DOI: 10.1016/j.bioactmat.2022.02.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/02/2022] [Accepted: 02/28/2022] [Indexed: 12/15/2022] Open
Abstract
Stroke is the leading cause of death and disability. Currently, there is no effective pharmacological treatment for this disease, which can be partially attributed to the inability to efficiently deliver therapeutics to the brain. Here we report the development of natural compound-derived nanoparticles (NPs), which function both as a potent therapeutic agent for stroke treatment and as an efficient carrier for drug delivery to the ischemic brain. First, we screened a collection of natural nanomaterials and identified betulinic acid (BA) as one of the most potent antioxidants for stroke treatment. Next, we engineered BA NPs for preferential drug release in acidic ischemic tissue through chemically converting BA to betulinic amine (BAM) and for targeted drug delivery through surface conjugation of AMD3100, a CXCR4 antagonist. The resulting AMD3100-conjugated BAM NPs, or A-BAM NPs, were then assessed as a therapeutic agent for stroke treatment and as a carrier for delivery of NA1, a neuroprotective peptide. We show that intravenous administration of A-BAM NPs effectively improved recovery from stroke and its efficacy was further enhanced when NA1 was encapsulated. Due to their multifunctionality and significant efficacy, we anticipate that A-BAM NPs have the potential to be translated both as a therapeutic agent and as a drug carrier to improve the treatment of stroke.
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Key Words
- A-BAM NPs, A-BAM NPs
- ALT, alanine aminotransferase
- AST, aspartate aminotransferase
- Acid-triggered release
- Antioxidant nanoparticles
- BA, betulinic acid
- BAM, betulinic amine
- BBB, blood brain barrier
- BIRDS, biosensor imaging of redundant deviation in shifts
- BT, ß-sitosterol
- DLS, dynamic light scattering
- DTA, dehydrotrametenolic acid
- DYDA, diketohydrindylidene diketohydrindamine
- Drug delivery
- GA, glycyrrhetic acid
- Ischemic stroke
- LCMS, liquid chromatography mass spectrometry
- LP, lupeol
- MCAO, middle cerebral artery occlusion
- NA1
- NMR, nuclear magnetic resonance
- NP, nanoparticle
- OA, oleanolic acid
- PAA, poricoic acid
- PEG, polyethylene glycol
- SA, sumaresinolic acid
- SEM, scanning electron microscopy
- ST, stigmasterol
- TEM, transmission electron microscope
- TTC, triphenyltetrazolium chloride
- UA, ursolic acid
- tPA, tissue-type plasminogen activator
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Affiliation(s)
- Shenqi Zhang
- Department of Neurosurgery, USA
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, 430060, China
| | | | | | | | | | | | - Chao Ma
- Department of Neurosurgery, USA
| | | | | | - W. Taylor Kimberly
- Department of Neurology, Division of Neurocritical Care, Massachusetts General Hospital, Boston, MA, USA
| | - J. Marc Simard
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Daniel Coman
- Department of Radiology and Biomedical Imaging, USA
| | - Qianxue Chen
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, 430060, China
| | - Fahmeed Hyder
- Department of Biomedical Engineering, USA
- Department of Radiology and Biomedical Imaging, USA
| | - Jiangbing Zhou
- Department of Neurosurgery, USA
- Department of Biomedical Engineering, USA
| | - Kevin N. Sheth
- Department of Neurosurgery, USA
- Department of Neurology, Yale University, New Haven, CT, 06510, USA
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Balogh M, Zhang J, Gaffney CM, Kalakuntla N, Nguyen NT, Trinh RT, Aguilar C, Pham HV, Milutinovic B, Nichols JM, Mahalingam R, Shepherd AJ. Sensory neuron dysfunction in orthotopic mouse models of colon cancer. J Neuroinflammation 2022; 19:204. [PMID: 35962398 PMCID: PMC9375288 DOI: 10.1186/s12974-022-02566-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 08/07/2022] [Indexed: 11/10/2022] Open
Abstract
Reports of neurological sequelae related to colon cancer are largely restricted to rare instances of paraneoplastic syndromes, due to autoimmune reactions. Systemic inflammation associated with tumor development influences sensory neuron function in other disease models, though the extent to which this occurs in colorectal cancer is unknown. We induced orthotopic colorectal cancer via orthotopic injection of two colorectal cancer cell lines (MC38 and CT26) in two different mouse strains (C57BL/6 and Balb/c, respectively). Behavioral tests of pain sensitivity and activity did not detect significant alterations in sensory sensitivity or diminished well-being throughout tumor development. However, immunohistochemistry revealed widespread reductions in intraepidermal nerve fiber density in the skin of tumor-bearing mice. Though loss of nerve fiber density was not associated with increased expression of cell injury markers in dorsal root ganglia, lumbar dorsal root ganglia neurons of tumor-bearing animals showed deficits in mitochondrial function. These neurons also had reduced cytosolic calcium levels in live-cell imaging and reduced spontaneous activity in multi-electrode array analysis. Bulk RNA sequencing of DRGs from tumor-bearing mice detected activation of gene expression pathways associated with elevated cytokine and chemokine signaling, including CXCL10. This is consistent with the detection of CXCL10 (and numerous other cytokines, chemokines and growth factors) in MC38 and CT26 cell-conditioned media, and the serum of tumor-bearing mice. Our study demonstrates in a pre-clinical setting that colon cancer is associated with latent sensory neuron dysfunction and implicates cytokine/chemokine signaling in this process. These findings may have implications for determining risk factors and treatment responsiveness related to neuropathy in colorectal cancer.
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Affiliation(s)
- Mihály Balogh
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Pharmaceutical Analysis, Groningen Research Institute of Pharmacy, University of Groningen, 9700 AD, Groningen, The Netherlands
| | - Jixiang Zhang
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Caitlyn M Gaffney
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Neha Kalakuntla
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Nicholas T Nguyen
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Graduate School of Biomedical Sciences, UT Southwestern Medical Center, Dallas, TX, USA
| | - Ronnie T Trinh
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Clarissa Aguilar
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Neuroscience and Behavior Graduate Program, University of Massachusetts Amherst, Amherst, MA, USA
| | - Hoang Vu Pham
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Bojana Milutinovic
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Department of Neurosurgery, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - James M Nichols
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Rajasekaran Mahalingam
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Andrew J Shepherd
- The MD Anderson Pain Research Consortium and the Laboratories of Neuroimmunology, Department of Symptom Research, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
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3
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Clenbuterol-sensitive delayed outward potassium currents in a cell model of spinal and bulbar muscular atrophy. Pflugers Arch 2021; 473:1213-1227. [PMID: 34021780 DOI: 10.1007/s00424-021-02559-6] [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: 01/26/2021] [Revised: 03/09/2021] [Accepted: 03/23/2021] [Indexed: 10/21/2022]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by polyglutamine (polyQ) expansions in the androgen receptor (AR) gene. SBMA is characterized by selective dysfunction and degeneration of motor neurons in the brainstem and spinal cord through still unclear mechanisms in which ion channel modulation might play a central role as for other neurodegenerative diseases. The beta2-adrenergic agonist clenbuterol was observed to ameliorate the SBMA phenotype in mice and patient-derived myotubes. However, the underlying molecular mechanism has yet to be clarified. Here, we unveil that ionic current alterations induced by the expression of polyQ-expanded AR in motor neuron-derived MN-1 cells are attenuated by the administration of clenbuterol. Our combined electrophysiological and pharmacological approach allowed us to reveal that clenbuterol modifies delayed outward potassium currents. Overall, we demonstrated that the protection provided by clenbuterol restores the normal function through the modulation of KV2-type outward potassium currents, possibly contributing to the protective effect on motor neuron toxicity in SBMA.
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Bachmann M, Li W, Edwards MJ, Ahmad SA, Patel S, Szabo I, Gulbins E. Voltage-Gated Potassium Channels as Regulators of Cell Death. Front Cell Dev Biol 2020; 8:611853. [PMID: 33381507 PMCID: PMC7767978 DOI: 10.3389/fcell.2020.611853] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/23/2020] [Indexed: 12/11/2022] Open
Abstract
Ion channels allow the flux of specific ions across biological membranes, thereby determining ion homeostasis within the cells. Voltage-gated potassium-selective ion channels crucially contribute to the setting of the plasma membrane potential, to volume regulation and to the physiologically relevant modulation of intracellular potassium concentration. In turn, these factors affect cell cycle progression, proliferation and apoptosis. The present review summarizes our current knowledge about the involvement of various voltage-gated channels of the Kv family in the above processes and discusses the possibility of their pharmacological targeting in the context of cancer with special emphasis on Kv1.1, Kv1.3, Kv1.5, Kv2.1, Kv10.1, and Kv11.1.
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Affiliation(s)
- Magdalena Bachmann
- Department of Biology, University of Padova, Padua, Italy.,Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Weiwei Li
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Michael J Edwards
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Syed A Ahmad
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Sameer Patel
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padua, Italy.,Consiglio Nazionale delle Ricerche Institute of Neuroscience, Padua, Italy
| | - Erich Gulbins
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States.,Department of Molecular Biology, University of Duisburg-Essen, Essen, Germany
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Zhu X, Chen Y, Xu X, Xu X, Lu Y, Huang X, Zhou J, Hu L, Wang J, Shen X. SP6616 as a Kv2.1 inhibitor efficiently ameliorates peripheral neuropathy in diabetic mice. EBioMedicine 2020; 61:103061. [PMID: 33096484 PMCID: PMC7581884 DOI: 10.1016/j.ebiom.2020.103061] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 09/20/2020] [Accepted: 09/24/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Diabetic peripheral neuropathy (DPN) is a common complication of diabetes severely afflicting the patients, while there is yet no effective medication against this disease. As Kv2.1 channel functions potently in regulating neurological disorders, the present work was to investigate the regulation of Kv2.1 channel against DPN-like pathology of DPN model mice by using selective Kv2.1 inhibitor SP6616 (ethyl 5-(3-ethoxy-4-methoxyphenyl)-2-(4-hydroxy-3-methoxybenzylidene)-7-methyl-3-oxo-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine-6-carboxylate) as a probe. METHODS STZ-induced type 1 diabetic mice with DPN (STZ mice) were defined at 12 weeks of age (4 weeks after STZ injection) through behavioral tests, and db/db (BKS Cg-m+/+Leprdb/J) type 2 diabetic mice with DPN (db/db mice) were at 18 weeks of age. SP6616 was administered daily via intraperitoneal injection for 4 weeks. The mechanisms underlying the amelioration of SP6616 on DPN-like pathology were investigated by RT-PCR, western blot and immunohistochemistry technical approaches against diabetic mice, and verified against the STZ mice with Kv2.1 knockdown in dorsal root ganglion (DRG) tissue by injection of adeno associated virus AAV9-Kv2.1-RNAi. Amelioration of SP6616 on the pathological behaviors of diabetic mice was assessed against tactile allodynia, thermal sensitivity and motor nerve conduction velocity (MNCV). FINDINGS SP6616 treatment effectively ameliorated the threshold of mechanical stimuli, thermal sensitivity and MNCV of diabetic mice. Mechanism research results indicated that SP6616 suppressed Kv2.1 expression, increased the number of intraepidermal nerve fibers (IENFs), improved peripheral nerve structure and vascular function in DRG tissue. In addition, SP6616 improved mitochondrial dysfunction through Kv2.1/CaMKKβ/AMPK/PGC-1α pathway, repressed inflammatory response by inhibiting Kv2.1/NF-κB signaling and alleviated apoptosis of DRG neuron through Kv2.1-mediated regulation of Bcl-2 family proteins and Caspase-3 in diabetic mice. INTERPRETATION Our work has highly supported the beneficial of Kv2.1 inhibition in ameliorating DPN-like pathology and highlighted the potential of SP6616 in the treatment of DPN. FUNDING Please see funding sources.
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Affiliation(s)
- Xialin Zhu
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Yun Chen
- Department of Medicinal Chemistry, China Pharmaceutical University, 24 Tongjia Xiang, Nanjing 210009, China
| | - Xu Xu
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Xiaoju Xu
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Yin Lu
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Xi Huang
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Jinpei Zhou
- Department of Medicinal Chemistry, China Pharmaceutical University, 24 Tongjia Xiang, Nanjing 210009, China.
| | - Lihong Hu
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Jiaying Wang
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China.
| | - Xu Shen
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China.
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6
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Justice JA, Manjooran DT, Yeh CY, Hartnett-Scott KA, Schulien AJ, Kosobucki GJ, Mammen S, Palladino MJ, Aizenman E. Molecular Neuroprotection Induced by Zinc-Dependent Expression of Hepatitis C-Derived Protein NS5A Targeting Kv2.1 Potassium Channels. J Pharmacol Exp Ther 2018; 367:348-355. [PMID: 30190339 PMCID: PMC6193254 DOI: 10.1124/jpet.118.252338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 09/06/2018] [Indexed: 12/20/2022] Open
Abstract
We present the design of an innovative molecular neuroprotective strategy and provide proof-of-concept for its implementation, relying on the injury-mediated activation of an ectopic gene construct. As oxidative injury leads to the intracellular liberation of zinc, we hypothesize that tapping onto the zinc-activated metal regulatory element (MRE) transcription factor 1 system to drive expression of the Kv2.1-targeted hepatitis C protein NS5A (hepatitis C nonstructural protein 5A) will provide neuroprotection by preventing cell death-enabling cellular potassium loss in rat cortical neurons in vitro. Indeed, using biochemical and morphologic assays, we demonstrate rapid expression of MRE-driven products in neurons. Further, we report that MRE-driven NS5A expression, induced by a slowly evolving excitotoxic stimulus, functionally blocks injurious, enhanced Kv2.1 potassium whole-cell currents and improves neuronal viability. We suggest this form of "on-demand" neuroprotection could provide the basis for a tenable therapeutic strategy to prevent neuronal cell death in neurodegeneration.
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Affiliation(s)
- Jason A Justice
- Departments of Neurobiology (J.A.J., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., E.A.) and Pharmacology and Chemical Biology (D.T.M., M.J.P.) and Pittsburgh Institute for Neurodegenerative Diseases (J.A.J., D.T.M., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., M.J.P., E.A.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Daniel T Manjooran
- Departments of Neurobiology (J.A.J., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., E.A.) and Pharmacology and Chemical Biology (D.T.M., M.J.P.) and Pittsburgh Institute for Neurodegenerative Diseases (J.A.J., D.T.M., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., M.J.P., E.A.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Chung-Yang Yeh
- Departments of Neurobiology (J.A.J., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., E.A.) and Pharmacology and Chemical Biology (D.T.M., M.J.P.) and Pittsburgh Institute for Neurodegenerative Diseases (J.A.J., D.T.M., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., M.J.P., E.A.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Karen A Hartnett-Scott
- Departments of Neurobiology (J.A.J., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., E.A.) and Pharmacology and Chemical Biology (D.T.M., M.J.P.) and Pittsburgh Institute for Neurodegenerative Diseases (J.A.J., D.T.M., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., M.J.P., E.A.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Anthony J Schulien
- Departments of Neurobiology (J.A.J., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., E.A.) and Pharmacology and Chemical Biology (D.T.M., M.J.P.) and Pittsburgh Institute for Neurodegenerative Diseases (J.A.J., D.T.M., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., M.J.P., E.A.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Gabrielle J Kosobucki
- Departments of Neurobiology (J.A.J., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., E.A.) and Pharmacology and Chemical Biology (D.T.M., M.J.P.) and Pittsburgh Institute for Neurodegenerative Diseases (J.A.J., D.T.M., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., M.J.P., E.A.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Shalom Mammen
- Departments of Neurobiology (J.A.J., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., E.A.) and Pharmacology and Chemical Biology (D.T.M., M.J.P.) and Pittsburgh Institute for Neurodegenerative Diseases (J.A.J., D.T.M., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., M.J.P., E.A.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Michael J Palladino
- Departments of Neurobiology (J.A.J., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., E.A.) and Pharmacology and Chemical Biology (D.T.M., M.J.P.) and Pittsburgh Institute for Neurodegenerative Diseases (J.A.J., D.T.M., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., M.J.P., E.A.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Elias Aizenman
- Departments of Neurobiology (J.A.J., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., E.A.) and Pharmacology and Chemical Biology (D.T.M., M.J.P.) and Pittsburgh Institute for Neurodegenerative Diseases (J.A.J., D.T.M., C.-Y.Y., K.A.H.-S., A.J.S., G.J.K., S.M., M.J.P., E.A.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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Angiotensin II Triggers Peripheral Macrophage-to-Sensory Neuron Redox Crosstalk to Elicit Pain. J Neurosci 2018; 38:7032-7057. [PMID: 29976627 DOI: 10.1523/jneurosci.3542-17.2018] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 05/03/2018] [Accepted: 05/07/2018] [Indexed: 12/20/2022] Open
Abstract
Injury, inflammation, and nerve damage initiate a wide variety of cellular and molecular processes that culminate in hyperexcitation of sensory nerves, which underlies chronic inflammatory and neuropathic pain. Using behavioral readouts of pain hypersensitivity induced by angiotensin II (Ang II) injection into mouse hindpaws, our study shows that activation of the type 2 Ang II receptor (AT2R) and the cell-damage-sensing ion channel TRPA1 are required for peripheral mechanical pain sensitization induced by Ang II in male and female mice. However, we show that AT2R is not expressed in mouse and human dorsal root ganglia (DRG) sensory neurons. Instead, expression/activation of AT2R on peripheral/skin macrophages (MΦs) constitutes a critical trigger of mouse and human DRG sensory neuron excitation. Ang II-induced peripheral mechanical pain hypersensitivity can be attenuated by chemogenetic depletion of peripheral MΦs. Furthermore, AT2R activation in MΦs triggers production of reactive oxygen/nitrogen species, which trans-activate TRPA1 on mouse and human DRG sensory neurons via cysteine modification of the channel. Our study thus identifies a translatable immune cell-to-sensory neuron signaling crosstalk underlying peripheral nociceptor sensitization. This form of cell-to-cell signaling represents a critical peripheral mechanism for chronic pain and thus identifies multiple druggable analgesic targets.SIGNIFICANCE STATEMENT Pain is a widespread health problem that is undermanaged by currently available analgesics. Findings from a recent clinical trial on a type II angiotensin II receptor (AT2R) antagonist showed effective analgesia for neuropathic pain. AT2R antagonists have been shown to reduce neuropathy-, inflammation- and bone cancer-associated pain in rodents. We report that activation of AT2R in macrophages (MΦs) that infiltrate the site of injury, but not in sensory neurons, triggers an intercellular redox communication with sensory neurons via activation of the cell damage/pain-sensing ion channel TRPA1. This MΦ-to-sensory neuron crosstalk results in peripheral pain sensitization. Our findings provide an evidence-based mechanism underlying the analgesic action of AT2R antagonists, which could accelerate the development of efficacious non-opioid analgesic drugs for multiple pain conditions.
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8
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Zhu J, Zang S, Chen X, Jiang L, Gu A, Cheng J, Zhang L, Wang J, Xiao H. Involvement of the delayed rectifier outward potassium channel Kv2.1 in methamphetamine-induced neuronal apoptosis via the p38 mitogen-activated protein kinase signaling pathway. J Appl Toxicol 2018; 38:696-704. [PMID: 29297590 DOI: 10.1002/jat.3576] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 11/06/2017] [Accepted: 11/11/2017] [Indexed: 01/08/2023]
Abstract
Methamphetamine (Meth) is an illicit psychostimulant with high abuse potential and severe neurotoxicity. Recent studies have shown that dysfunctions in learning and memory induced by Meth may partially reveal the mechanisms of neuronal channelopathies. Kv2.1, the primary delayed rectifying potassium channel in neurons, is responsible for mediating apoptotic current surge. However, whether Kv2.1 is involved in Meth-mediated neural injury remains unknown. In the present study, the treatment of primary cultured hippocampal neurons with Meth indicated that Meth induced a time- and dose-dependent augmentation of Kv2.1 protein expression, accompanied by elevated cleaved-caspase 3 and declined bcl-2/bax ratio. The blockage of Kv2.1 with the inhibitor GxTx-1E or the knockdown of the channel noticeably abrogated the pro-apoptotic effects mediated by Meth, demonstrating the specific roles of Kv2.1 in Meth-mediated neural damage. Additionally, the p38 mitogen-activated protein kinase (MAPK) signaling was demonstrated to be involved in Meth-mediated Kv2.1 upregulation and in the subsequent pro-apoptotic effects, as treatment with a p38 MAPK inhibitor significantly attenuated Meth-mediated Kv2.1 upregulation and cell apoptosis. Of note, PRE-084, a sigma-1 receptor agonist, obviously attenuated Meth-induced upregulation of Kv2.1 expression, neural apoptosis and p38 MAPK activation. Taken together, these results reveal a novel mechanism involved in Meth-induced neural death with implications for therapeutic interventions for Meth users.
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Affiliation(s)
- Jingying Zhu
- Key Lab of Modern Toxicology (NJMU), Ministry of Education; Department of Toxicology, School of Public Health, Nanjing Medical University, 818 Tianyuan East Road, Nanjing, Jiangsu, 211166, China.,Wuxi Center for Disease Control and Prevention, 499 Jincheng Road, Liangxi District, Wuxi, Jiangsu, 214023, China
| | - Songsong Zang
- Key Lab of Modern Toxicology (NJMU), Ministry of Education; Department of Toxicology, School of Public Health, Nanjing Medical University, 818 Tianyuan East Road, Nanjing, Jiangsu, 211166, China
| | - Xufeng Chen
- Department of Emergency Medicine, the First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu, 210029, China
| | - Lei Jiang
- Department of Emergency Medicine, the First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu, 210029, China
| | - Aihua Gu
- Key Lab of Modern Toxicology (NJMU), Ministry of Education; Department of Toxicology, School of Public Health, Nanjing Medical University, 818 Tianyuan East Road, Nanjing, Jiangsu, 211166, China
| | - Jie Cheng
- Key Lab of Modern Toxicology (NJMU), Ministry of Education; Department of Toxicology, School of Public Health, Nanjing Medical University, 818 Tianyuan East Road, Nanjing, Jiangsu, 211166, China
| | - Li Zhang
- Children's Hospital of Nanjing Medical University, 72 Guangzhou Road, Nanjing, Jiangsu, 210029, China
| | - Jun Wang
- Key Lab of Modern Toxicology (NJMU), Ministry of Education; Department of Toxicology, School of Public Health, Nanjing Medical University, 818 Tianyuan East Road, Nanjing, Jiangsu, 211166, China
| | - Hang Xiao
- Key Lab of Modern Toxicology (NJMU), Ministry of Education; Department of Toxicology, School of Public Health, Nanjing Medical University, 818 Tianyuan East Road, Nanjing, Jiangsu, 211166, China
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9
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Wu PR, Cho KK, Vogt D, Sohal VS, Rubenstein JL. The Cytokine CXCL12 Promotes Basket Interneuron Inhibitory Synapses in the Medial Prefrontal Cortex. Cereb Cortex 2017; 27:4303-4313. [PMID: 27497284 PMCID: PMC6410508 DOI: 10.1093/cercor/bhw230] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 06/28/2016] [Indexed: 12/20/2022] Open
Abstract
Prenatally, the cytokine CXCL12 regulates cortical interneuron migration, whereas its postnatal functions are poorly understood. Here, we report that CXCL12 is expressed postnatally in layer V pyramidal neurons and localizes on their cell bodies in the medial prefrontal cortex (mPFC), while its receptors CXCR4/CXCR7 localize to the axon terminals of parvalbumin (PV) interneurons. Conditionally eliminating CXCL12 in neonatal layer V pyramidal neurons led to decreased axon targeting and reduced inhibitory perisomatic synapses from PV+ basket interneurons onto layer V pyramidal neurons. Consequently, the mPFC of Cxcl12 conditional mutants displayed attenuated inhibitory postsynaptic currents onto layer V pyramidal neurons. Thus, postnatal CXCL12 signaling promotes a specific interneuron circuit that inhibits mPFC activity.
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Affiliation(s)
- Pei-Rung Wu
- Department of Psychiatry, University of California, San
Francisco, San Francisco, CA 94143,
USA
| | - Kathleen K.A. Cho
- Department of Psychiatry, University of California, San
Francisco, San Francisco, CA 94143,
USA
- Center for Integrative Neuroscience, University of California, San
Francisco, San Francisco,
CA94143, USA
- Sloan-Swartz Center for Theoretical Neurobiology, University of California, San
Francisco, San Francisco,
CA94143, USA
| | - Daniel Vogt
- Department of Psychiatry, University of California, San
Francisco, San Francisco, CA 94143,
USA
| | - Vikaas S. Sohal
- Department of Psychiatry, University of California, San
Francisco, San Francisco, CA 94143,
USA
- Center for Integrative Neuroscience, University of California, San
Francisco, San Francisco,
CA94143, USA
- Sloan-Swartz Center for Theoretical Neurobiology, University of California, San
Francisco, San Francisco,
CA94143, USA
| | - John L.R. Rubenstein
- Department of Psychiatry, University of California, San
Francisco, San Francisco, CA 94143,
USA
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10
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Schulien AJ, Justice JA, Di Maio R, Wills ZP, Shah NH, Aizenman E. Zn(2+) -induced Ca(2+) release via ryanodine receptors triggers calcineurin-dependent redistribution of cortical neuronal Kv2.1 K(+) channels. J Physiol 2017; 594:2647-59. [PMID: 26939666 DOI: 10.1113/jp272117] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 02/14/2016] [Indexed: 12/30/2022] Open
Abstract
KEY POINTS Increases in intracellular Zn(2+) concentrations are an early, necessary signal for the modulation of Kv2.1 K(+) channel localization and physiological function. Intracellular Zn(2+) -mediated Kv2.1 channel modulation is dependent on calcineurin, a Ca(2+) -activated phosphatase. We show that intracellular Zn(2+) induces a significant increase in ryanodine receptor-dependent cytosolic Ca(2+) transients, which leads to a calcineurin-dependent redistribution of Kv2.1 channels from pre-existing membrane clusters to diffuse localization. As such, the link between Zn(2+) and Ca(2+) signalling in this Kv2.1 modulatory pathway is established. We observe that a sublethal ischaemic preconditioning insult also leads to Kv2.1 redistribution in a ryanodine receptor-dependent fashion. We suggest that Zn(2+) may be an early and ubiquitous signalling molecule mediating Ca(2+) release from the cortical endoplasmic reticulum via ryanodine receptor activation. ABSTRACT Sublethal injurious stimuli in neurons induce transient increases in free intracellular Zn(2+) that are associated with regulating adaptive responses to subsequent lethal injury, including alterations in the function and localization of the delayed-rectifier potassium channel, Kv2.1. However, the link between intracellular Zn(2+) signalling and the observed changes in Kv2.1 remain undefined. In the present study, utilizing exogenous Zn(2+) treatment, along with a selective Zn(2+) ionophore, we show that transient elevations in intracellular Zn(2+) concentrations are sufficient to induce calcineurin-dependent Kv2.1 channel dispersal in rat cortical neurons in vitro, which is accompanied by a relatively small but significant hyperpolarizing shift in the voltage-gated activation kinetics of the channel. Critically, using a molecularly encoded calcium sensor, we found that the calcineurin-dependent changes in Kv2.1 probably occur as a result of Zn(2+) -induced cytosolic Ca(2+) release via activation of neuronal ryanodine receptors. Finally, we couple this mechanism with an established model for in vitro ischaemic preconditioning and show that Kv2.1 channel modulation in this process is also ryanodine receptor-sensitive. Our results strongly suggest that intracellular Zn(2+) -initiated signalling may represent an early and possibly widespread component of Ca(2+) -dependent processes in neurons.
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Affiliation(s)
- Anthony J Schulien
- Department of Neurobiology.,Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, PA, USA
| | - Jason A Justice
- Department of Neurobiology.,Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, PA, USA
| | - Roberto Di Maio
- Department of Neurology.,Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, PA, USA
| | | | | | - Elias Aizenman
- Department of Neurobiology.,Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, PA, USA
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11
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Targeting a Potassium Channel/Syntaxin Interaction Ameliorates Cell Death in Ischemic Stroke. J Neurosci 2017; 37:5648-5658. [PMID: 28483976 DOI: 10.1523/jneurosci.3811-16.2017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 04/25/2017] [Accepted: 05/01/2017] [Indexed: 12/12/2022] Open
Abstract
The voltage-gated K+ channel Kv2.1 has been intimately linked with neuronal apoptosis. After ischemic, oxidative, or inflammatory insults, Kv2.1 mediates a pronounced, delayed enhancement of K+ efflux, generating an optimal intracellular environment for caspase and nuclease activity, key components of programmed cell death. This apoptosis-enabling mechanism is initiated via Zn2+-dependent dual phosphorylation of Kv2.1, increasing the interaction between the channel's intracellular C-terminus domain and the SNARE (soluble N-ethylmaleimide-sensitive factor activating protein receptor) protein syntaxin 1A. Subsequently, an upregulation of de novo channel insertion into the plasma membrane leads to the critical enhancement of K+ efflux in damaged neurons. Here, we investigated whether a strategy designed to interfere with the cell death-facilitating properties of Kv2.1, specifically its interaction with syntaxin 1A, could lead to neuroprotection following ischemic injury in vivo The minimal syntaxin 1A-binding sequence of Kv2.1 C terminus (C1aB) was first identified via a far-Western peptide screen and used to create a protherapeutic product by conjugating C1aB to a cell-penetrating domain. The resulting peptide (TAT-C1aB) suppressed enhanced whole-cell K+ currents produced by a mutated form of Kv2.1 mimicking apoptosis in a mammalian expression system, and protected cortical neurons from slow excitotoxic injury in vitro, without influencing NMDA-induced intracellular calcium responses. Importantly, intraperitoneal administration of TAT-C1aB in mice following transient middle cerebral artery occlusion significantly reduced ischemic stroke damage and improved neurological outcome. These results provide strong evidence that targeting the proapoptotic function of Kv2.1 is an effective and highly promising neuroprotective strategy.SIGNIFICANCE STATEMENT Kv2.1 is a critical regulator of apoptosis in central neurons. It has not been determined, however, whether the cell death-enabling function of this K+ channel can be selectively targeted to improve neuronal survival following injury in vivo The experiments presented here demonstrate that the cell death-specific role of Kv2.1 can be uniquely modulated to provide neuroprotection in an animal model of acute ischemic stroke. We thus reveal a novel therapeutic strategy for neurological disorders that are accompanied by Kv2.1-facilitated forms of cell death.
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12
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Justice JA, Schulien AJ, He K, Hartnett KA, Aizenman E, Shah NH. Disruption of K V2.1 somato-dendritic clusters prevents the apoptogenic increase of potassium currents. Neuroscience 2017; 354:158-167. [PMID: 28461216 DOI: 10.1016/j.neuroscience.2017.04.034] [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: 12/23/2016] [Revised: 03/01/2017] [Accepted: 04/21/2017] [Indexed: 12/27/2022]
Abstract
As the predominant mediator of the delayed rectifier current, KV2.1 is an important regulator of neuronal excitability. KV2.1, however, also plays a well-established role in apoptotic cell death. Apoptogenic stimuli induce syntaxin-dependent trafficking of KV2.1, resulting in an augmented delayed rectifier current that acts as a conduit for K+ efflux required for pro-apoptotic protease/nuclease activation. Recent evidence suggests that KV2.1 somato-dendritic clusters regulate the formation of endoplasmic reticulum-plasma membrane junctions that function as scaffolding sites for plasma membrane trafficking of ion channels, including KV2.1. However, it is unknown whether KV2.1 somato-dendritic clusters are required for apoptogenic trafficking of KV2.1. By overexpression of a protein derived from the C-terminus of the cognate channel KV2.2 (KV2.2CT), we induced calcineurin-independent disruption of KV2.1 somato-dendritic clusters in rat cortical neurons, without altering the electrophysiological properties of the channel. We observed that KV2.2CT-expressing neurons are less susceptible to oxidative stress-induced cell death. Critically, expression of KV2.2CT effectively blocked the increased current density of the delayed rectifier current associated with oxidative injury, supporting a vital role of KV2.1-somato-dendritic clusters in apoptogenic increases in KV2.1-mediated currents.
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Affiliation(s)
- Jason A Justice
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
| | - Anthony J Schulien
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Kai He
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Karen A Hartnett
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Elias Aizenman
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Niyathi H Shah
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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13
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Sanchez AB, Medders KE, Maung R, Sánchez-Pavón P, Ojeda-Juárez D, Kaul M. CXCL12-induced neurotoxicity critically depends on NMDA receptor-gated and L-type Ca 2+ channels upstream of p38 MAPK. J Neuroinflammation 2016; 13:252. [PMID: 27664068 PMCID: PMC5035480 DOI: 10.1186/s12974-016-0724-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 09/16/2016] [Indexed: 11/25/2022] Open
Abstract
Background The chemokine receptor CXCR4 (CD184) and its natural ligand CXCL12 contribute to many physiological processes, including decisions about cell death and survival in the central nervous system. In addition, CXCR4 is a co-receptor for human immunodeficiency virus (HIV)-1 and mediates the neurotoxicity of the viral envelope protein gp120. However, we previously observed that CXCL12 also causes toxicity in cerebrocortical neurons but the cellular mechanism remained incompletely defined. Methods Primary neuronal-glial cerebrocortical cell cultures from rat were exposed to a neurotoxicity-inducing CXCL12 concentration for different times and the activity of the stress-associated mitogen-activated protein kinase p38 (p38 MAPK) was assessed using an in vitro kinase assay. Neurotoxicity of CXCL12 and cellular localization of p38 MAPK was analyzed by immunofluorescence microscopy. Pharmacological inhibition of NMDA-type glutamate receptor-gated ion channels (NMDAR) of l-type Ca2+ channels was employed during 12- and 24-h exposure to neurotoxic amounts of CXCL12 to study the effects on active p38 MAPK and neuronal survival by Western blotting and microscopy, respectively. Neurotoxicity of CXCL12 was also assessed during pharmacological inhibition of p38 MAPK. Results Here, we show that a neurotoxic amount of CXCL12 triggers a significant increase of endogenous p38 MAPK activity in cerebrocortical cells. Immunofluorescence and Western blotting experiments with mixed neuronal-glial and neuron-depleted glial cerebrocortical cells revealed that the majority of active/phosphorylated p38 MAPK was located in neurons. Blockade of NMDAR-gated ion channels or l-type Ca2+ channels both abrogated an increase of active p38 MAPK and toxicity of CXCL12 in cerebrocortical neurons. Inhibition of l-type Ca2+ channels with nimodipine kept the active kinase at levels not significantly different from baseline while blocking NMDAR with MK-801 strongly reduced phosphorylated p38 MAPK below baseline. Finally, we confirmed that directly blocking p38 MAPK also abrogated neurotoxicity of CXCL12. Conclusions Our findings link CXCL12-induced neuronal death to the regulation of NMDAR-gated ion channels and l-type Ca2+ channels upstream of p38 MAPK activation.
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Affiliation(s)
- Ana B Sanchez
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, Bldg. 10, La Jolla, CA, 92037, USA
| | - Kathryn E Medders
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, Bldg. 10, La Jolla, CA, 92037, USA.,Present address: UC San Diego Health, 200 W. Arbor Drive #8765, San Diego, CA, 92103, USA
| | - Ricky Maung
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, Bldg. 10, La Jolla, CA, 92037, USA
| | - Paloma Sánchez-Pavón
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, Bldg. 10, La Jolla, CA, 92037, USA
| | - Daniel Ojeda-Juárez
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, Bldg. 10, La Jolla, CA, 92037, USA
| | - Marcus Kaul
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, Bldg. 10, La Jolla, CA, 92037, USA. .,Department of Psychiatry, University of California, San Diego, 9500 Gilman Drive, San Diego, CA, 92093, USA.
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14
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Ru W, Tang SJ. HIV-1 gp120Bal down-Regulates Phosphorylated NMDA Receptor Subunit 1 in Cortical Neurons via Activation of Glutamate and Chemokine Receptors. J Neuroimmune Pharmacol 2016; 11:182-91. [PMID: 26582091 PMCID: PMC4746099 DOI: 10.1007/s11481-015-9644-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 11/12/2015] [Indexed: 01/08/2023]
Abstract
HIV-1 envelope glycoprotein gp120 (gp120) is a major virulence protein implicated in the pathogenesis of HIV-associated neurocognitive disorders (HAND). Although gp120 has been suggested to cause synaptic and neuronal injuries by disrupting NMDA receptor (NMDAR) function, the underlying mechanism is unclear. Here, we show that gp120Bal down-regulates the phosphorylation of the NMDAR subunit1 NR1 (at Ser896 and Ser897), which is essential for NMDAR function. This effect of gp120Bal is blocked by specific antagonists of both NMDA and AMPA receptors, indicating a critical role of synaptic activation. Furthermore, AMD3100 and maraviroc, antagonists of CCR5 and CXCR4 chemokine receptors, respectively, inhibit the effect of gp120Bal on NR1, suggesting that CXCR4 and CCR5 activation are involved. These findings may provide mechanistic insights into the synaptopathogenesis caused by HIV-1 infection.
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Affiliation(s)
- Wenjuan Ru
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Shao-Jun Tang
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA.
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15
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Gupte RP, Kadunganattil S, Shepherd AJ, Merrill R, Planer W, Bruchas MR, Strack S, Mohapatra DP. Convergent phosphomodulation of the major neuronal dendritic potassium channel Kv4.2 by pituitary adenylate cyclase-activating polypeptide. Neuropharmacology 2015; 101:291-308. [PMID: 26456351 DOI: 10.1016/j.neuropharm.2015.10.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 09/29/2015] [Accepted: 10/03/2015] [Indexed: 12/30/2022]
Abstract
The endogenous neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) is secreted by both neuronal and non-neuronal cells in the brain and spinal cord, in response to pathological conditions such as stroke, seizures, chronic inflammatory and neuropathic pain. PACAP has been shown to exert various neuromodulatory and neuroprotective effects. However, direct influence of PACAP on the function of intrinsically excitable ion channels that are critical to both hyperexcitation as well as cell death, remain largely unexplored. The major dendritic K(+) channel Kv4.2 is a critical regulator of neuronal excitability, back-propagating action potentials in the dendrites, and modulation of synaptic inputs. We identified, cloned and characterized the downstream signaling originating from the activation of three PACAP receptor (PAC1) isoforms that are expressed in rodent hippocampal neurons that also exhibit abundant expression of Kv4.2 protein. Activation of PAC1 by PACAP leads to phosphorylation of Kv4.2 and downregulation of channel currents, which can be attenuated by inhibition of either PKA or ERK1/2 activity. Mechanistically, this dynamic downregulation of Kv4.2 function is a consequence of reduction in the density of surface channels, without any influence on the voltage-dependence of channel activation. Interestingly, PKA-induced effects on Kv4.2 were mediated by ERK1/2 phosphorylation of the channel at two critical residues, but not by direct channel phosphorylation by PKA, suggesting a convergent phosphomodulatory signaling cascade. Altogether, our findings suggest a novel GPCR-channel signaling crosstalk between PACAP/PAC1 and Kv4.2 channel in a manner that could lead to neuronal hyperexcitability.
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Affiliation(s)
- Raeesa P Gupte
- Department of Pharmacology, The University of Iowa Roy J. and Lucile A. Carver College of Medicine, Iowa City, IA 52242, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Suraj Kadunganattil
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Andrew J Shepherd
- Department of Pharmacology, The University of Iowa Roy J. and Lucile A. Carver College of Medicine, Iowa City, IA 52242, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ronald Merrill
- Department of Pharmacology, The University of Iowa Roy J. and Lucile A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - William Planer
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Michael R Bruchas
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Stefan Strack
- Department of Pharmacology, The University of Iowa Roy J. and Lucile A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - Durga P Mohapatra
- Department of Pharmacology, The University of Iowa Roy J. and Lucile A. Carver College of Medicine, Iowa City, IA 52242, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA.
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16
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Zhu Q, Song X, Zhou J, Wang Y, Xia J, Qian W, Zhu J, Gao R, Wang J, Xiao H. Target of HIV-1 Envelope Glycoprotein gp120-Induced Hippocampal Neuron Damage: Role of Voltage-Gated K(+) Channel Kv2.1. Viral Immunol 2015; 28:495-503. [PMID: 26393286 DOI: 10.1089/vim.2015.0020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein 120 (gp120) has been reported to be toxic to the hippocampal neurons, and to be involved in the pathogenesis of HIV-1-associated neurocognitive disorders (HAND). Accumulating evidence has demonstrated that voltage-gated potassium (Kv) channels, especially the outward delayed-rectifier K(+) (Ik) channels, play a critical role in gp120-induced cortical neuronal death in vitro. However, the potential mechanisms underlying the hippocampal neuronal injury resulted from gp120-mediated neurotoxicity remain poorly understood. Using whole-cell patch clamp recording in cultured hippocampal neurons, this study found that gp120 significantly increased the outward delayed-rectifier K(+) currents (Ik). Meanwhile, Western blot assay revealed that gp120 markedly upregulated Kv2.1 protein levels, which was consistent with the increased Ik density. With Western blot and terminal deoxynucleotidyl transferase dUTP nick end labeling assays, it was discovered that gp120-induced neuronal injury was largely due to activation of Kv2.1 channels and resultant apoptosis mediated by caspase-3 activation, as the pharmacological blockade of Kv2.1 channels largely attenuated gp120-induced cell damage and caspase-3 expression. Moreover, p38 MAPK was demonstrated to participate in gp120-induced hippocampal neural damage, since p38 MAPK antagonist (SB203580) partially abrogated gp120-induced Kv2.1 upregulation and neural apoptosis. Taken together, these results suggest that gp120 induces hippocampal neuron apoptosis by enhancement of the Ik, which might be associated with increased Kv2.1 expression via the p38 MAPK pathway.
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Affiliation(s)
- Qing Zhu
- 1 Key Lab of Modern Toxicology (NJMU), Ministry of Education, Department of Toxicology, School of Public Health, Nanjing Medical University , Nanjing, China
| | - Xu Song
- 1 Key Lab of Modern Toxicology (NJMU), Ministry of Education, Department of Toxicology, School of Public Health, Nanjing Medical University , Nanjing, China
| | - Jing Zhou
- 1 Key Lab of Modern Toxicology (NJMU), Ministry of Education, Department of Toxicology, School of Public Health, Nanjing Medical University , Nanjing, China
| | - Yixin Wang
- 1 Key Lab of Modern Toxicology (NJMU), Ministry of Education, Department of Toxicology, School of Public Health, Nanjing Medical University , Nanjing, China
| | - Jianxun Xia
- 2 Department of Psychology, Queens College, City University of New York , New York
| | - Wenyi Qian
- 1 Key Lab of Modern Toxicology (NJMU), Ministry of Education, Department of Toxicology, School of Public Health, Nanjing Medical University , Nanjing, China
| | - Jingying Zhu
- 1 Key Lab of Modern Toxicology (NJMU), Ministry of Education, Department of Toxicology, School of Public Health, Nanjing Medical University , Nanjing, China
| | - Rong Gao
- 1 Key Lab of Modern Toxicology (NJMU), Ministry of Education, Department of Toxicology, School of Public Health, Nanjing Medical University , Nanjing, China
| | - Jun Wang
- 1 Key Lab of Modern Toxicology (NJMU), Ministry of Education, Department of Toxicology, School of Public Health, Nanjing Medical University , Nanjing, China
| | - Hang Xiao
- 1 Key Lab of Modern Toxicology (NJMU), Ministry of Education, Department of Toxicology, School of Public Health, Nanjing Medical University , Nanjing, China
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17
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Carryl H, Swang M, Lawrence J, Curtis K, Kamboj H, Van Rompay KKA, De Paris K, Burke MW. Of mice and monkeys: can animal models be utilized to study neurological consequences of pediatric HIV-1 infection? ACS Chem Neurosci 2015; 6:1276-89. [PMID: 26034832 PMCID: PMC4545399 DOI: 10.1021/acschemneuro.5b00044] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pediatric human immunodeficiency virus (HIV-1) infection remains a global health crisis. Children are much more susceptible to HIV-1 neurological impairments than adults, which can be exacerbated by coinfections. Neurological characteristics of pediatric HIV-1 infection suggest dysfunction in the frontal cortex as well as the hippocampus; limited MRI data indicate global cerebral atrophy, and pathological data suggest accelerated neuronal apoptosis in the cortex. An obstacle to pediatric HIV-1 research is a human representative model system. Host-species specificity of HIV-1 limits the ability to model neurological consequences of pediatric HIV-1 infection in animals. Several models have been proposed including neonatal intracranial injections of HIV-1 viral proteins in rats and perinatal simian immunodeficiency virus (SIV) infection of infant macaques. Nonhuman primate models recapitulate the complexity of pediatric HIV-1 neuropathogenesis while rodent models are able to elucidate the role specific viral proteins exert on neurodevelopment. Nonhuman primate models show similar behavioral and neuropathological characteristics to pediatric HIV-1 infection and offer a stage to investigate early viral mechanisms, latency reservoirs, and therapeutic interventions. Here we review the relative strengths and limitations of pediatric HIV-1 model systems.
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Affiliation(s)
- Heather Carryl
- Department of Physiology & Biophysics, College of Medicine, Howard University, Washington, D.C. 20059, United States
| | - Melanie Swang
- Department of Biology, Howard University, Washington, D.C. 20059, United States
| | - Jerome Lawrence
- Department of Biology, Howard University, Washington, D.C. 20059, United States
| | - Kimberly Curtis
- Department of Physiology & Biophysics, College of Medicine, Howard University, Washington, D.C. 20059, United States
| | - Herman Kamboj
- Department of Physiology & Biophysics, College of Medicine, Howard University, Washington, D.C. 20059, United States
| | - Koen K. A. Van Rompay
- California National Primate Research Center, University of California at Davis, Davis, California 95616, United States
| | - Kristina De Paris
- Department of Microbiology and Immunology and Center for AIDS Research School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Mark W. Burke
- Department of Physiology & Biophysics, College of Medicine, Howard University, Washington, D.C. 20059, United States
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18
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He K, McCord MC, Hartnett KA, Aizenman E. Regulation of Pro-Apoptotic Phosphorylation of Kv2.1 K+ Channels. PLoS One 2015; 10:e0129498. [PMID: 26115091 PMCID: PMC4482604 DOI: 10.1371/journal.pone.0129498] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 05/08/2015] [Indexed: 12/12/2022] Open
Abstract
Caspase activity during apoptosis is inhibited by physiological concentrations of intracellular K+. To enable apoptosis in injured cortical and hippocampal neurons, cellular loss of this cation is facilitated by the insertion of Kv2.1 K+ channels into the plasma membrane via a Zn2+/CaMKII/SNARE-dependent process. Pro-apoptotic membrane insertion of Kv2.1 requires the dual phosphorylation of the channel by Src and p38 at cytoplasmic N- and C-terminal residues Y124 and S800, respectively. In this study, we investigate if these phosphorylation sites are mutually co-regulated, and whether putative N- and C-terminal interactions, possibly enabled by Kv2.1 intracellular cysteine residues C73 and C710, influence the phosphorylation process itself. Studies were performed with recombinant wild type and mutant Kv2.1 expressed in Chinese hamster ovary (CHO) cells. Using immunoprecipitated Kv2.1 protein and phospho-specific antibodies, we found that an intact Y124 is required for p38 phosphorylation of S800, and, importantly, that Src phosphorylation of Y124 facilitates the action of the p38 at the S800 residue. Moreover, the actions of Src on Kv2.1 are substantially decreased in the non-phosphorylatable S800A channel mutant. We also observed that mutations of either C73 or C710 residues decreased the p38 phosphorylation at S800 without influencing the actions of Src on tyrosine phosphorylation of Kv2.1. Surprisingly, however, apoptotic K+ currents were suppressed only in cells expressing the Kv2.1(C73A) mutant but not in those transfected with Kv2.1(C710A), suggesting a possible structural alteration in the C-terminal mutant that facilitates membrane insertion. These results show that intracellular N-terminal domains critically regulate phosphorylation of the C-terminal of Kv2.1, and vice versa, suggesting possible new avenues for modifying the apoptotic insertion of these channels during neurodegenerative processes.
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Affiliation(s)
- Kai He
- Department of Neurobiology, University of Pittsburgh School of Medicine, E1456 BST, 3500 Terrace St., Pittsburgh, PA, 15261, United States of America
| | - Meghan C. McCord
- Department of Neurobiology, University of Pittsburgh School of Medicine, E1456 BST, 3500 Terrace St., Pittsburgh, PA, 15261, United States of America
| | - Karen A. Hartnett
- Department of Neurobiology, University of Pittsburgh School of Medicine, E1456 BST, 3500 Terrace St., Pittsburgh, PA, 15261, United States of America
| | - Elias Aizenman
- Department of Neurobiology, University of Pittsburgh School of Medicine, E1456 BST, 3500 Terrace St., Pittsburgh, PA, 15261, United States of America
- * E-mail:
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19
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Reduction of pyramidal and immature hippocampal neurons in pediatric simian immunodeficiency virus infection. Neuroreport 2015; 25:973-8. [PMID: 25102373 DOI: 10.1097/wnr.0000000000000148] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Pediatric HIV infection remains a global health crisis with a worldwide infection rate of 2.5 million (WHO, Geneva Switzerland, 2009). Children are much more susceptible to HIV-1 neurological impairments compared with adults, which is exacerbated by coinfections. A major obstacle in pediatric HIV research is sample access. The proposed studies take advantage of ongoing pediatric simian immunodeficiency virus (SIV) pathogenesis and vaccine studies to test the hypothesis that pediatric SIV infection diminishes neuronal populations and neurogenesis in the hippocampus. Newborn rhesus macaques (Macaca mulatta) that received intravenous inoculation of highly virulent SIVmac251 (n=3) or vehicle (control n=4) were used in this study. After a 6-18-week survival time, the animals were euthanized and the brains prepared for quantitative histopathological analysis. Systematic sections through the hippocampus were either Nissl stained or immunostained for doublecortin (DCX+), a putative marker of immature neurons. Using design-based stereology, we report a 42% reduction in the pyramidal neuron population of the CA1, CA2, and CA3 fields of the hippocampus (P<0.05) in SIV-infected infants. The DCX+ neuronal population was also significantly reduced within the dentate gyrus of the hippocampus. The loss of hippocampal neurons and neurogenic capacity may contribute to the rapid neurocognitive decline associated with pediatric HIV infection. These data suggest that pediatric SIV infection, which leads to significant neuronal loss in the hippocampus within 3 months, closely models a subset of pediatric HIV infections with rapid progression.
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Optogenetic activation of cajal-retzius cells reveals their glutamatergic output and a novel feedforward circuit in the developing mouse hippocampus. J Neurosci 2014; 34:13018-32. [PMID: 25253849 DOI: 10.1523/jneurosci.1407-14.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cajal-Retzius cells orchestrate the development of cortical circuits by secreting the glycoprotein reelin. However, their computational functions are still unknown. In fact, the nature of their postsynaptic targets, major neurotransmitter released, as well as the class of postsynaptic receptors activated by their firing remain unclear. Here, we have addressed these questions by activating Cajal-Retzius cells optogenetically in mouse hippocampal slices. Light delivered to stratum lacunosum-moleculare triggered EPSCs both on local interneurons and on pyramidal cells. Responses recorded under voltage-clamp conditions had identical short latencies and similar amplitudes, but were kinetically different (i.e., faster in interneurons vs pyramidal cells). In both cases, responses were blocked by TTX, indicating that they were generated by action potential-dependent release. Responses in interneurons were rescued by the addition of 4-AP to TTX, and decreased when presynaptic firing in Cajal-Retzius cells was reduced by the chemokine CXCL12, indicating the existence of a direct Cajal-Retzius cell-interneuron monosynaptic connection. Although the combined application of 4-AP and TTX did not rescue responses in pyramidal cells, neither were they affected by the GABAA receptor blocker gabazine, which would be expected if they were polysynaptic. Both connections showed physiological and pharmacological properties indicating the involvement of AMPA- and NMDA-type glutamate receptors. The connectivity from presynaptic Cajal-Retzius cells to interneurons was strong enough to generate long-latency feedforward GABAergic input onto pyramidal cells. We propose that this newly defined Cajal-Retzius cell-dependent microcircuit may regulate synaptic plasticity and dendritic development in stratum lacunosum-moleculare, thus impacting the integrative properties of the developing hippocampus.
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Zheng W, Huang W, Liu S, Levitt RC, Candiotti KA, Lubarsky DA, Hao S. Interleukin 10 mediated by herpes simplex virus vectors suppresses neuropathic pain induced by human immunodeficiency virus gp120 in rats. Anesth Analg 2014; 119:693-701. [PMID: 25137003 DOI: 10.1213/ane.0000000000000311] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Human immunodeficiency virus (HIV)-associated sensory neuropathy is a common neurological complication of HIV infection affecting up to 30% of HIV-positive individuals. However, the exact neuropathological mechanisms remain unknown, which hinders our ability to develop effective treatments for HIV-related neuropathic pain (NP). In this study, we tested the hypothesis that inhibition of proinflammatory factors with overexpression of interleukin (IL)-10 reduces HIV-related NP in a rat model. METHODS NP was induced by the application of recombinant HIV-1 envelope protein gp120 into the sciatic nerve. The hindpaws of rats were inoculated with nonreplicating herpes simplex virus (HSV) vectors expressing anti-inflammatory cytokine IL-10 or control vector. Mechanical threshold was tested using von Frey filaments before and after treatments with the vectors. The mechanical threshold response was assessed over time using the area under curves. The expression of phosphorylated p38 mitogen-activated kinase, tumor necrosis factor-α, stromal cell-derived factor-1α, and C-X-C chemokine receptor type 4 in both the lumbar spinal cord and the L4/5 dorsal root ganglia (DRG), was examined at 14 and 28 days after vector inoculation using Western blots. RESULTS We found that in the gp120-induced NP model, IL-10 overexpression mediated by the HSV vector resulted in a significant elevation of the mechanical threshold that was apparent on day 3 after vector inoculation compared with the control vector (P < 0.001). The antiallodynic effect of the single HSV vector inoculation expressing IL-10 lasted >28 days. The area under curve in the HSV vector expressing IL-10 was increased compared with that in the control vector (P < 0.0001). HSV vectors expressing IL-10 reversed the upregulation of phosphorylated p38 mitogen-activated kinase, tumor necrosis factor-α, stromal cell-derived factor-1α, and C-X-C chemokine receptor type 4 expression at 14 and/or 28 days in the DRG and/or the spinal dorsal horn. CONCLUSIONS Our studies demonstrate that blocking the signaling of these proinflammatory molecules in the DRG and/or the spinal cord using the HSV vector expressing IL-10 is able to reduce HIV-related NP. These results provide new insights on the potential mechanisms of HIV-associated NP and a proof of concept for treating painful HIV sensory neuropathy with this type of gene therapy.
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Affiliation(s)
- Wenwen Zheng
- From the Department of Anesthesiology, University of Miami Miller School of Medicine, Miami, Florida; Department of Anesthesiology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China; Hussman Institute of Human Genomics, University of Miami Miller School of Medicine; and Veterans Affairs Medical Center, Miami, Florida
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22
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Abstract
Kv2.1 is a major delayed rectifying K(+) channel normally localized to highly phosphorylated somatodendritic clusters in neurons. Excitatory stimuli induce calcineurin-dependent dephosphorylation and dispersal of Kv2.1 clusters, with a concomitant hyperpolarizing shift in the channel's activation kinetics. We showed previously that sublethal ischemia, which renders neurons transiently resistant to excitotoxic cell death, can also induce Zn(2+)-dependent changes in Kv2.1 localization and activation kinetics, suggesting that activity-dependent modifications of Kv2.1 may contribute to cellular adaptive responses to injury. Recently, cyclin-dependent kinase 5 (Cdk5) was shown to phosphorylate Kv2.1, with pharmacological Cdk5 inhibition being sufficient to decluster channels. In another study, cyclin E1 was found to restrict neuronal Cdk5 kinase activity. We show here that cyclin E1 regulates Kv2.1 cellular localization via inhibition of Cdk5 activity. Expression of cyclin E1 in human embryonic kidney cells prevents Cdk5-mediated phosphorylation of Kv2.1, and cyclin E1 overexpression in rat cortical neurons triggers dispersal of Kv2.1 channel clusters. Sublethal ischemia in neurons induces calcineurin-dependent upregulation of cyclin E1 protein expression and cyclin E1-dependent Kv2.1 channel declustering. Importantly, overexpression of cyclin E1 in neurons is sufficient to reduce excitotoxic cell death. These results support a novel role for neuronal cyclin E1 in regulating the phosphorylation status and localization of Kv2.1 channels, a likely component of signaling cascades leading to ischemic preconditioning.
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Michaud JL, Lachance M, Hamdan FF, Carmant L, Lortie A, Diadori P, Major P, Meijer IA, Lemyre E, Cossette P, Mefford HC, Rouleau GA, Rossignol E. The genetic landscape of infantile spasms. Hum Mol Genet 2014; 23:4846-58. [PMID: 24781210 DOI: 10.1093/hmg/ddu199] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Infantile spasms (IS) is an early-onset epileptic encephalopathy of unknown etiology in ∼40% of patients. We hypothesized that unexplained IS cases represent a large collection of rare single-gene disorders. We investigated 44 children with unexplained IS using comparative genomic hybridisation arrays (aCGH) (n = 44) followed by targeted sequencing of 35 known epilepsy genes (n = 8) or whole-exome sequencing (WES) of familial trios (n = 18) to search for rare inherited or de novo mutations. aCGH analysis revealed de novo variants in 7% of patients (n = 3/44), including a distal 16p11.2 duplication, a 15q11.1q13.1 tetrasomy and a 2q21.3-q22.2 deletion. Furthermore, it identified a pathogenic maternally inherited Xp11.2 duplication. Targeted sequencing was informative for ARX (n = 1/14) and STXBP1 (n = 1/8). In contrast, sequencing of a panel of 35 known epileptic encephalopathy genes (n = 8) did not identify further mutations. Finally, WES (n = 18) was very informative, with an excess of de novo mutations identified in genes predicted to be involved in neurodevelopmental processes and/or known to be intolerant to functional variations. Several pathogenic mutations were identified, including de novo mutations in STXBP1, CASK and ALG13, as well as recessive mutations in PNPO and ADSL, together explaining 28% of cases (5/18). In addition, WES identified 1-3 de novo variants in 64% of remaining probands, pointing to several interesting candidate genes. Our results indicate that IS are genetically heterogeneous with a major contribution of de novo mutations and that WES is significantly superior to targeted re-sequencing in identifying detrimental genetic variants involved in IS.
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Affiliation(s)
- Jacques L Michaud
- Department of Pediatrics and Department of Neurosciences, Université de Montréal, Montréal, QC, Canada, CHU Ste-Justine Research Center, Montréal, QC, Canada
| | | | - Fadi F Hamdan
- CHU Ste-Justine Research Center, Montréal, QC, Canada
| | - Lionel Carmant
- Department of Pediatrics and Department of Neurosciences, Université de Montréal, Montréal, QC, Canada, CHU Ste-Justine Research Center, Montréal, QC, Canada
| | - Anne Lortie
- Department of Pediatrics and Department of Neurosciences, Université de Montréal, Montréal, QC, Canada, CHU Ste-Justine Research Center, Montréal, QC, Canada
| | - Paola Diadori
- Department of Pediatrics and Department of Neurosciences, Université de Montréal, Montréal, QC, Canada, CHU Ste-Justine Research Center, Montréal, QC, Canada
| | - Philippe Major
- Department of Pediatrics and Department of Neurosciences, Université de Montréal, Montréal, QC, Canada, CHU Ste-Justine Research Center, Montréal, QC, Canada
| | - Inge A Meijer
- CHU Ste-Justine Research Center, Montréal, QC, Canada
| | - Emmanuelle Lemyre
- Department of Pediatrics and CHU Ste-Justine Research Center, Montréal, QC, Canada
| | - Patrick Cossette
- Department of Neurosciences, Université de Montréal, Montréal, QC, Canada, CHUM, Montréal, QC, Canada
| | - Heather C Mefford
- Department of Pediatrics, University of Washington, Seattle, WA, USA and
| | - Guy A Rouleau
- Department of Neurosciences, Montreal Neurological Institute, McGill University, Montréal, QC, Canada
| | - Elsa Rossignol
- Department of Pediatrics and Department of Neurosciences, Université de Montréal, Montréal, QC, Canada, CHU Ste-Justine Research Center, Montréal, QC, Canada,
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24
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Guyon A. CXCL12 chemokine and GABA neurotransmitter systems crosstalk and their putative roles. Front Cell Neurosci 2014; 5:115. [PMID: 24808825 PMCID: PMC4009426 DOI: 10.3389/fncel.2014.00115] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 04/08/2014] [Indexed: 11/28/2022] Open
Abstract
Since CXCL12 and its receptors, CXCR4 and CXCR7, have been found in the brain, the role of this chemokine has been expanded from chemoattractant in the immune system to neuromodulatory in the brain. Several pieces of evidence suggest that this chemokine system could crosstalk with the GABAergic system, known to be the main inhibitory neurotransmitter system in the brain. Indeed, GABA and CXCL12 as well as their receptors are colocalized in many cell types including neurons and there are several examples in which these two systems interact. Several mechanisms can be proposed to explain how these systems interact, including receptor–receptor interactions, crosstalk at the level of second messenger cascades, or direct pharmacological interactions, as GABA and GABAB receptor agonists/antagonists have been shown to be allosteric modulators of CXCR4. The interplay between CXCL12/CXCR4-CXCR7 and GABA/GABAA-GABAB receptors systems could have many physiological implications in neurotransmission, cancer and inflammation. In addition, the GABAB agonist baclofen is currently used in medicine to treat spasticity in patients with spinal cord injury, cerebral palsy, traumatic brain injury, multiple sclerosis, and other disorders. More recently it has also been used in the treatment of alcohol dependence and withdrawal. The allosteric effects of this agent on CXCR4 could contribute to these beneficial effects or at the opposite, to its side effects.
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Affiliation(s)
- Alice Guyon
- CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, Université Nice Sophia Antipolis Valbonne, France
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25
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Electrophysiological characterization of Ts6 and Ts7, K⁺ channel toxins isolated through an improved Tityus serrulatus venom purification procedure. Toxins (Basel) 2014; 6:892-913. [PMID: 24590385 PMCID: PMC3968367 DOI: 10.3390/toxins6030892] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 01/24/2014] [Accepted: 02/17/2014] [Indexed: 01/09/2023] Open
Abstract
In Brazil, Tityus serrulatus (Ts) is the species responsible for most of the scorpion related accidents. Among the Ts toxins, the neurotoxins with action on potassium channels (α-KTx) present high interest, due to their effect in the envenoming process and the ion channel specificity they display. The α-KTx toxins family is the most relevant because its toxins can be used as therapeutic tools for specific target cells. The improved isolation method provided toxins with high resolution, obtaining pure Ts6 and Ts7 in two chromatographic steps. The effects of Ts6 and Ts7 toxins were evaluated in 14 different types of potassium channels using the voltage-clamp technique with two-microelectrodes. Ts6 toxin shows high affinity for Kv1.2, Kv1.3 and Shaker IR, blocking these channels in low concentrations. Moreover, Ts6 blocks the Kv1.3 channel in picomolar concentrations with an IC50 of 0.55 nM and therefore could be of valuable assistance to further designing immunosuppressive therapeutics. Ts7 toxin blocks multiple subtypes channels, showing low selectivity among the channels analyzed. This work also stands out in its attempt to elucidate the residues important for interacting with each channel and, in the near future, to model a desired drug.
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Shah NH, Aizenman E. Voltage-gated potassium channels at the crossroads of neuronal function, ischemic tolerance, and neurodegeneration. Transl Stroke Res 2013; 5:38-58. [PMID: 24323720 DOI: 10.1007/s12975-013-0297-7] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/14/2013] [Accepted: 10/14/2013] [Indexed: 11/29/2022]
Abstract
Voltage-gated potassium (Kv) channels are widely expressed in the central and peripheral nervous system and are crucial mediators of neuronal excitability. Importantly, these channels also actively participate in cellular and molecular signaling pathways that regulate the life and death of neurons. Injury-mediated increased K(+) efflux through Kv2.1 channels promotes neuronal apoptosis, contributing to widespread neuronal loss in neurodegenerative disorders such as Alzheimer's disease and stroke. In contrast, some forms of neuronal activity can dramatically alter Kv2.1 channel phosphorylation levels and influence their localization. These changes are normally accompanied by modifications in channel voltage dependence, which may be neuroprotective within the context of ischemic injury. Kv1 and Kv7 channel dysfunction leads to neuronal hyperexcitability that critically contributes to the pathophysiology of human clinical disorders such as episodic ataxia and epilepsy. This review summarizes the neurotoxic, neuroprotective, and neuroregulatory roles of Kv channels and highlights the consequences of Kv channel dysfunction on neuronal physiology. The studies described in this review thus underscore the importance of normal Kv channel function in neurons and emphasize the therapeutic potential of targeting Kv channels in the treatment of a wide range of neurological diseases.
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Affiliation(s)
- Niyathi Hegde Shah
- Department of Neurobiology, University of Pittsburgh School of Medicine, 3500 Terrace Street, E1456 BST, Pittsburgh, PA, 15261, USA,
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27
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Shepherd AJ, Loo L, Mohapatra DP. Chemokine co-receptor CCR5/CXCR4-dependent modulation of Kv2.1 channel confers acute neuroprotection to HIV-1 glycoprotein gp120 exposure. PLoS One 2013; 8:e76698. [PMID: 24086760 PMCID: PMC3782454 DOI: 10.1371/journal.pone.0076698] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 08/23/2013] [Indexed: 11/28/2022] Open
Abstract
Infection with human immunodeficiency virus-1 (HIV-1) within the brain has long been known to be associated with neurodegeneration and neurocognitive disorder (referred as HAND), a condition characterized in its early stages by declining cognitive function and behavioral disturbances. Mechanistically, the HIV-1 coat glycoprotein 120 (gp120) has been suggested to be a critical factor inducing apoptotic cell death in neurons via the activation of p38 mitogen-activated protein kinase (MAPK), upon chronic exposure to the virus. Here we show that acute exposure of neurons to HIV-1 gp120 elicits a homeostatic response, which provides protection against non-apoptotic cell death, involving the major somatodendritic voltage-gated K+ (Kv) channel Kv2.1 as the key mediator. The Kv2.1 channel has recently been shown to provide homeostatic control of neuronal excitability under conditions of seizures, ischemia and neuromodulation/neuroinflammation. Following acute exposure to gp120, cultured rat hippocampal neurons show rapid dephosphorylation of the Kv2.1 protein, which ultimately leads to changes in specific sub-cellular localization and voltage-dependent channel activation properties of Kv2.1. Such modifications in Kv2.1 are dependent on the activation of the chemokine co-receptors CCR5 and CXCR4, and subsequent activation of the protein phosphatase calcineurin. This leads to the overall suppression of neuronal excitability and provides neurons with a homeostatic protective mechanism. Specific blockade of calcineurin and Kv2.1 channel activity led to significant enhancement of non-apoptotic neuronal death upon acute gp120 treatment. These observations shed new light on the intrinsic homeostatic mechanisms of neuronal resilience during the acute stages of neuro-HIV infections.
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Affiliation(s)
- Andrew J. Shepherd
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, United States of America
| | - Lipin Loo
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, United States of America
| | - Durga P. Mohapatra
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, United States of America
- Department of Anesthesia, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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Baclofen and other GABAB receptor agents are allosteric modulators of the CXCL12 chemokine receptor CXCR4. J Neurosci 2013; 33:11643-54. [PMID: 23843532 DOI: 10.1523/jneurosci.6070-11.2013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
CXCR4, a receptor for the chemokine CXCL12 (stromal-cell derived factor-1α), is a G-protein-coupled receptor (GPCR), expressed in the immune and CNS and integrally involved in various neurological disorders. The GABAB receptor is also a GPCR that mediates metabotropic action of the inhibitory neurotransmitter GABA and is located on neurons and immune cells as well. Using diverse approaches, we report novel interaction between GABAB receptor agents and CXCR4 and demonstrate allosteric binding of these agents to CXCR4. First, both GABAB antagonists and agonists block CXCL12-elicited chemotaxis in human breast cancer cells. Second, a GABAB antagonist blocks the potentiation by CXCL12 of high-threshold Ca(2+) channels in rat neurons. Third, electrophysiology in Xenopus oocytes and human embryonic kidney cell line 293 cells in which we coexpressed rat CXCR4 and the G-protein inward rectifier K(+) (GIRK) channel showed that GABAB antagonist and agonist modified CXCL12-evoked activation of GIRK channels. To investigate whether GABAB ligands bind to CXCR4, we expressed this receptor in heterologous systems lacking GABAB receptors and performed competition binding experiments. Our fluorescent resonance energy transfer experiments suggest that GABAB ligands do not bind CXCR4 at the CXCL12 binding pocket suggesting allosteric modulation, in accordance with our electrophysiology experiments. Finally, using backscattering interferometry and lipoparticles containing only the CXCR4 receptor, we quantified the binding affinity for the GABAB ligands, confirming a direct interaction with the CXCR4 receptor. The effect of GABAergic agents on CXCR4 suggests new therapeutic potentials for neurological and immune diseases.
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Convergent Ca2+ and Zn2+ signaling regulates apoptotic Kv2.1 K+ currents. Proc Natl Acad Sci U S A 2013; 110:13988-93. [PMID: 23918396 DOI: 10.1073/pnas.1306238110] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A simultaneous increase in cytosolic Zn(2+) and Ca(2+) accompanies the initiation of neuronal cell death signaling cascades. However, the molecular convergence points of cellular processes activated by these cations are poorly understood. Here, we show that Ca(2+)-dependent activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is required for a cell death-enabling process previously shown to also depend on Zn(2+). We have reported that oxidant-induced intraneuronal Zn(2+) liberation triggers a syntaxin-dependent incorporation of Kv2.1 voltage-gated potassium channels into the plasma membrane. This channel insertion can be detected as a marked enhancement of delayed rectifier K(+) currents in voltage clamp measurements observed at least 3 h following a short exposure to an apoptogenic stimulus. This current increase is the process responsible for the cytoplasmic loss of K(+) that enables protease and nuclease activation during apoptosis. In the present study, we demonstrate that an oxidative stimulus also promotes intracellular Ca(2+) release and activation of CaMKII, which, in turn, modulates the ability of syntaxin to interact with Kv2.1. Pharmacological or molecular inhibition of CaMKII prevents the K(+) current enhancement observed following oxidative injury and, importantly, significantly increases neuronal viability. These findings reveal a previously unrecognized cooperative convergence of Ca(2+)- and Zn(2+)-mediated injurious signaling pathways, providing a potentially unique target for therapeutic intervention in neurodegenerative conditions associated with oxidative stress.
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Muessel MJ, Harry GJ, Armstrong DL, Storey NM. SDF-1α and LPA modulate microglia potassium channels through rho gtpases to regulate cell morphology. Glia 2013; 61:1620-8. [PMID: 23893870 DOI: 10.1002/glia.22543] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 05/14/2013] [Accepted: 05/16/2013] [Indexed: 12/11/2022]
Abstract
Microglia are the resident immune cells of the brain, which are important therapeutic targets for regulating the inflammatory responses particularly neurodegeneration in the aging human brain. The activation, chemotaxis and migration of microglia are regulated through G-protein coupled receptors by chemokines such as stromal cell-derived factor (SDF)-1α and bioactive lysophospholipids such as lysophosphatidic acid (LPA). Potassium channels play important roles in microglial function and cell fate decisions; however, the regulation of microglial potassium channels has not been fully elucidated. Here we show reciprocal action of SDF-1α and LPA, on potassium currents through Kir2.1 channels in primary murine microglia. The potassium channel modulation is mediated by the same small GTPases, Rac and Rho that regulate the actin cytoskeleton. SDF-1α rapidly increased the Kir2.1 current amplitude and cell spreading. These effects were mimicked by dialysing the cells with constitutively active Rac1 protein, and they were blocked by inhibiting the phosphatidylinositol 3-kinase (PI3K) with wortmannin. In contrast, LPA and constitutively active RhoA decreased the Kir2.1 currents and stimulated cell contraction. Thus, SDF-1α and LPA regulate both the actin cytoskeleton and the Kir2.1 potassium channels through the same Rho GTPase signaling pathways. The inhibition of Kir2.1 with chloroethylclonidine produced cell contraction independently of chemokine action. This suggests that potassium channels are essential for the morphological phenotype and functioning of microglia. In conclusion, the small GTPases, Rac and Rho, modulate Kir2.1 channels and block of Kir2.1 channels causes changes in microglia morphology.
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Affiliation(s)
- Michelle J Muessel
- Laboratory of Neurobiology, NIEHS/NIH, Research Triangle Park, North Carolina, USA
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