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Marshall KL, Rajbhandari L, Venkatesan A, Maragakis NJ, Farah MH. Enhanced axonal regeneration of ALS patient iPSC-derived motor neurons harboring SOD1 A4V mutation. Sci Rep 2023; 13:5597. [PMID: 37020097 PMCID: PMC10076424 DOI: 10.1038/s41598-023-31720-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 03/16/2023] [Indexed: 04/07/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease, characterized by degeneration of upper and lower motor neurons that leads to muscle weakness, paralysis, and death, but the effects of disease-causing mutations on axonal outgrowth of neurons derived from human induced pluripotent stem cells (iPSC)-derived motor neurons (hiPSC-MN) are poorly understood. The use of hiPSC-MN is a promising tool to develop more relevant models for target identification and drug development in ALS research, but questions remain concerning the effects of distinct disease-causing mutations on axon regeneration. Mutations in superoxide dismutase 1 (SOD1) were the first to be discovered in ALS patients. Here, we investigated the effect of the SOD1A4V mutation on axonal regeneration of hiPSC-MNs, utilizing compartmentalized microfluidic devices, which are powerful tools for studying hiPSC-MN distal axons. Surprisingly, SOD1+/A4V hiPSC-MNs regenerated axons more quickly following axotomy than those expressing the native form of SOD1. Though initial axon regrowth was not significantly different following axotomy, enhanced regeneration was apparent at later time points, indicating an increased rate of outgrowth. This regeneration model could be used to identify factors that enhance the rate of human axon regeneration.
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Affiliation(s)
- Katherine L Marshall
- Neuromuscular Division, Department of Neurology, Johns Hopkins University School of Medicine, The John G. Rangos Sr. Building, Room 239, 855 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - Labchan Rajbhandari
- Neuromuscular Division, Department of Neurology, Johns Hopkins University School of Medicine, The John G. Rangos Sr. Building, Room 239, 855 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - Arun Venkatesan
- Neuromuscular Division, Department of Neurology, Johns Hopkins University School of Medicine, The John G. Rangos Sr. Building, Room 239, 855 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - Nicholas J Maragakis
- Neuromuscular Division, Department of Neurology, Johns Hopkins University School of Medicine, The John G. Rangos Sr. Building, Room 239, 855 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - Mohamed H Farah
- Neuromuscular Division, Department of Neurology, Johns Hopkins University School of Medicine, The John G. Rangos Sr. Building, Room 239, 855 N. Wolfe Street, Baltimore, MD, 21205, USA.
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2
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Jeong YE, Rajbhandari L, Kim BW, Venkatesan A, Hoke A. Downregulation of SF3B2 protects CNS neurons in models of multiple sclerosis. Ann Clin Transl Neurol 2023; 10:246-265. [PMID: 36574260 PMCID: PMC9930435 DOI: 10.1002/acn3.51717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/21/2022] [Accepted: 11/21/2022] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE Neurodegeneration induced by inflammatory stress in multiple sclerosis (MS) leads to long-term neurological disabilities that are not amenable to current immunomodulatory therapies. METHODS AND RESULTS Here, we report that neuronal downregulation of Splicing factor 3b subunit 2 (SF3B2), a component of U2 small nuclear ribonucleoprotein (snRNP), preserves retinal ganglion cell (RGC) survival and axonal integrity in experimental autoimmune encephalomyelitis (EAE)-induced mice. By employing an in vitro system recapitulating the inflammatory environment of MS lesion, we show that when SF3B2 levels are downregulated, cell viability and axon integrity are preserved in cortical neurons against inflammatory toxicity. Notably, knockdown of SF3B2 suppresses the expression of injury-response and necroptosis genes and prevents activation of Sterile Alpha and TIR Motif Containing 1 (Sarm1), a key enzyme that mediates programmed axon degeneration. INTERPRETATION Together, these findings suggest that the downregulation of SF3B2 is a novel potential therapeutic target to prevent secondary neurodegeneration in MS.
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Affiliation(s)
- Ye Eun Jeong
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA
| | - Labchan Rajbhandari
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA
| | - Byung Woo Kim
- Division of Neuropathology, Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA
| | - Arun Venkatesan
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA
| | - Ahmet Hoke
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA
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3
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Alexandris AS, Ryu J, Rajbhandari L, Harlan R, McKenney J, Wang Y, Aja S, Graham D, Venkatesan A, Koliatsos VE. Protective effects of NAMPT or MAPK inhibitors and NaR on Wallerian degeneration of mammalian axons. Neurobiol Dis 2022; 171:105808. [PMID: 35779777 PMCID: PMC10621467 DOI: 10.1016/j.nbd.2022.105808] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/14/2022] [Accepted: 06/25/2022] [Indexed: 01/23/2023] Open
Abstract
Wallerian degeneration (WD) is a conserved axonal self-destruction program implicated in several neurological diseases. WD is driven by the degradation of the NAD+ synthesizing enzyme NMNAT2, the buildup of its substrate NMN, and the activation of the NAD+ degrading SARM1, eventually leading to axonal fragmentation. The regulation and amenability of these events to therapeutic interventions remain unclear. Here we explored pharmacological strategies that modulate NMN and NAD+ metabolism, namely the inhibition of the NMN-synthesizing enzyme NAMPT, activation of the nicotinic acid riboside (NaR) salvage pathway and inhibition of the NMNAT2-degrading DLK MAPK pathway in an axotomy model in vitro. Results show that NAMPT and DLK inhibition cause a significant but time-dependent delay of WD. These time-dependent effects are related to NMNAT2 degradation and changes in NMN and NAD+ levels. Supplementation of NAMPT inhibition with NaR has an enhanced effect that does not depend on timing of intervention and leads to robust protection up to 4 days. Additional DLK inhibition extends this even further to 6 days. Metabolite analyses reveal complex effects indicating that NAMPT and MAPK inhibition act by reducing NMN levels, ameliorating NAD+ loss and suppressing SARM1 activity. Finally, the axonal NAD+/NMN ratio is highly predictive of cADPR levels, extending previous cell-free evidence on the allosteric regulation of SARM1. Our findings establish a window of axon protection extending several hours following injury. Moreover, we show prolonged protection by mixed treatments combining MAPK and NAMPT inhibition that proceed via complex effects on NAD+ metabolism and inhibition of SARM1.
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Affiliation(s)
| | - Jiwon Ryu
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Labchan Rajbhandari
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robert Harlan
- The Molecular Determinants Center and Core, Johns Hopkins All Children's Hospital, St. Petersburg, FL, USA
| | - James McKenney
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yiqing Wang
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Susan Aja
- The Molecular Determinants Center and Core, Johns Hopkins All Children's Hospital, St. Petersburg, FL, USA
| | - David Graham
- The Molecular Determinants Center and Core, Johns Hopkins All Children's Hospital, St. Petersburg, FL, USA
| | - Arun Venkatesan
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Vassilis E Koliatsos
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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4
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Ouwendijk WJD, Depledge DP, Rajbhandari L, Lenac Rovis T, Jonjic S, Breuer J, Venkatesan A, Verjans GMGM, Sadaoka T. Varicella-zoster virus VLT-ORF63 fusion transcript induces broad viral gene expression during reactivation from neuronal latency. Nat Commun 2020; 11:6324. [PMID: 33303747 PMCID: PMC7730162 DOI: 10.1038/s41467-020-20031-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 11/10/2020] [Indexed: 02/07/2023] Open
Abstract
Varicella-zoster virus (VZV) establishes lifelong neuronal latency in most humans world-wide, reactivating in one-third to cause herpes zoster and occasionally chronic pain. How VZV establishes, maintains and reactivates from latency is largely unknown. VZV transcription during latency is restricted to the latency-associated transcript (VLT) and RNA 63 (encoding ORF63) in naturally VZV-infected human trigeminal ganglia (TG). While significantly more abundant, VLT levels positively correlated with RNA 63 suggesting co-regulated transcription during latency. Here, we identify VLT-ORF63 fusion transcripts and confirm VLT-ORF63, but not RNA 63, expression in human TG neurons. During in vitro latency, VLT is transcribed, whereas VLT-ORF63 expression is induced by reactivation stimuli. One isoform of VLT-ORF63, encoding a fusion protein combining VLT and ORF63 proteins, induces broad viral gene transcription. Collectively, our findings show that VZV expresses a unique set of VLT-ORF63 transcripts, potentially involved in the transition from latency to lytic VZV infection.
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Affiliation(s)
- Werner J D Ouwendijk
- Department of Viroscience, Erasmus Medical Centre, 3015 CN, Rotterdam, The Netherlands
| | - Daniel P Depledge
- Department of Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | - Labchan Rajbhandari
- Division of Neuroimmunology and Neuroinfectious Diseases, Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Meyer 6-113, Baltimore, MD, 21287, USA
| | - Tihana Lenac Rovis
- Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, 51000, Croatia
| | - Stipan Jonjic
- Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, 51000, Croatia
| | - Judith Breuer
- Division of Infection and Immunity, University College London, London, WC1E 6BT, UK
| | - Arun Venkatesan
- Division of Neuroimmunology and Neuroinfectious Diseases, Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Meyer 6-113, Baltimore, MD, 21287, USA
| | - Georges M G M Verjans
- Department of Viroscience, Erasmus Medical Centre, 3015 CN, Rotterdam, The Netherlands
| | - Tomohiko Sadaoka
- Division of Clinical Virology, Center for Infectious Diseases, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan.
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5
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Morales Pantoja IE, Smith MD, Rajbhandari L, Cheng L, Gao Y, Mahairaki V, Venkatesan A, Calabresi PA, Fitzgerald KC, Whartenby KA. iPSCs from people with MS can differentiate into oligodendrocytes in a homeostatic but not an inflammatory milieu. PLoS One 2020; 15:e0233980. [PMID: 32511247 PMCID: PMC7279569 DOI: 10.1371/journal.pone.0233980] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 05/15/2020] [Indexed: 11/19/2022] Open
Abstract
Multiple sclerosis (MS) is an inflammatory and demyelinating disease of the central nervous system (CNS) that results in variable severities of neurodegeneration. The understanding of MS has been limited by the inaccessibility of the affected cells and the lengthy timeframe of disease development. However, recent advances in stem cell technology have facilitated the bypassing of some of these challenges. Towards gaining a greater understanding of the innate potential of stem cells from people with varying degrees of disability, we generated induced pluripotent stem cells (iPSCs) from peripheral blood mononuclear cells derived from stable and progressive MS patients, and then further differentiated them into oligodendrocyte (OL) lineage cells. We analyzed differentiation under both homeostatic and inflammatory conditions via sustained exposure to low-dose interferon gamma (IFNγ), a prominent cytokine in MS. We found that all iPSC lines differentiated into mature myelinating OLs, but chronic exposure to IFNγ dramatically inhibited differentiation in both MS groups, particularly if exposure was initiated during the pre-progenitor stage. Low-dose IFNγ was not toxic but led to an early upregulation of interferon response genes in OPCs followed by an apparent redirection in lineage commitment from OL to a neuron-like phenotype in a significant portion of the treated cells. Our results reveal that a chronic low-grade inflammatory environment may have profound effects on the efficacy of regenerative therapies.
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Affiliation(s)
- Itzy E. Morales Pantoja
- Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Matthew D. Smith
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Labchan Rajbhandari
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Linzhao Cheng
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Yongxing Gao
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Vasiliki Mahairaki
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Arun Venkatesan
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Peter A. Calabresi
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Kathryn C. Fitzgerald
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Department of Epidemiology Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Katharine A. Whartenby
- Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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6
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Dagro A, Rajbhandari L, Orrego S, Kang SH, Venkatesan A, Ramesh KT. Quantifying the Local Mechanical Properties of Cells in a Fibrous Three-Dimensional Microenvironment. Biophys J 2019; 117:817-828. [PMID: 31421835 DOI: 10.1016/j.bpj.2019.07.042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 06/28/2019] [Accepted: 07/26/2019] [Indexed: 12/27/2022] Open
Abstract
Measurements of the mechanical response of biological cells are critical for understanding injury and disease, for developing diagnostic tools, and for computational models in mechanobiology. Although it is well known that cells are sensitive to the topography of their microenvironment, the current paradigm in mechanical testing of adherent cells is mostly limited to specimens grown on flat two-dimensional substrates. In this study, we introduce a technique in which cellular indentation via optical trapping is performed on cells at a high spatial resolution to obtain their regional mechanical properties while they exist in a more favorable three-dimensional microenvironment. We combine our approach with nonlinear contact mechanics theory to consider the effects of a large deformation. This allows us to probe length scales that are relevant for obtaining overall cell stiffness values. The experimental results herein provide the hyperelastic material properties at both high (∼100 s-1) and low (∼1-10 s-1) strain rates of murine central nervous system glial cells. The limitations due to possible misalignment of the indenter in the three-dimensional space are examined using a computational model.
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Affiliation(s)
- Amy Dagro
- U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland.
| | | | - Santiago Orrego
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Sung Hoon Kang
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland; Hopkins Extreme Materials Institute, Johns Hopkins University, Baltimore, Maryland
| | - Arun Venkatesan
- Department of Neurology, Johns Hopkins University, Baltimore, Maryland
| | - Kaliat T Ramesh
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland; Hopkins Extreme Materials Institute, Johns Hopkins University, Baltimore, Maryland
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7
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Tomlinson RE, Li Z, Zhang Q, Goh BC, Li Z, Thorek DLJ, Rajbhandari L, Brushart TM, Minichiello L, Zhou F, Venkatesan A, Clemens TL. NGF-TrkA Signaling by Sensory Nerves Coordinates the Vascularization and Ossification of Developing Endochondral Bone. Cell Rep 2016; 16:2723-2735. [PMID: 27568565 DOI: 10.1016/j.celrep.2016.08.002] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 06/13/2016] [Accepted: 07/31/2016] [Indexed: 12/16/2022] Open
Abstract
Developing tissues dictate the amount and type of innervation they require by secreting neurotrophins, which promote neuronal survival by activating distinct tyrosine kinase receptors. Here, we show that nerve growth factor (NGF) signaling through neurotrophic tyrosine kinase receptor type 1 (TrkA) directs innervation of the developing mouse femur to promote vascularization and osteoprogenitor lineage progression. At the start of primary ossification, TrkA-positive axons were observed at perichondrial bone surfaces, coincident with NGF expression in cells adjacent to centers of incipient ossification. Inactivation of TrkA signaling during embryogenesis in TrkA(F592A) mice impaired innervation, delayed vascular invasion of the primary and secondary ossification centers, decreased numbers of Osx-expressing osteoprogenitors, and decreased femoral length and volume. These same phenotypic abnormalities were observed in mice following tamoxifen-induced disruption of NGF in Col2-expressing perichondrial osteochondral progenitors. We conclude that NGF serves as a skeletal neurotrophin to promote sensory innervation of developing long bones, a process critical for normal primary and secondary ossification.
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Affiliation(s)
- Ryan E Tomlinson
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Zhi Li
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Qian Zhang
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Brian C Goh
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Zhu Li
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Daniel L J Thorek
- Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD 21287, USA; Department of Oncology, Johns Hopkins University, Baltimore, MD 21287, USA
| | | | - Thomas M Brushart
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | | | - Fengquan Zhou
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Arun Venkatesan
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Thomas L Clemens
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA; Baltimore Veterans Administration Medical Center, Baltimore, MD 21201, USA.
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8
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Sadaoka T, Depledge DP, Rajbhandari L, Venkatesan A, Breuer J, Cohen JI. In vitro system using human neurons demonstrates that varicella-zoster vaccine virus is impaired for reactivation, but not latency. Proc Natl Acad Sci U S A 2016; 113:E2403-12. [PMID: 27078099 PMCID: PMC4855584 DOI: 10.1073/pnas.1522575113] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Varicella-zoster virus (VZV) establishes latency in human sensory and cranial nerve ganglia during primary infection (varicella), and the virus can reactivate and cause zoster after primary infection. The mechanism of how the virus establishes and maintains latency and how it reactivates is poorly understood, largely due to the lack of robust models. We found that axonal infection of neurons derived from hESCs in a microfluidic device with cell-free parental Oka (POka) VZV resulted in latent infection with inability to detect several viral mRNAs by reverse transcriptase-quantitative PCR, no production of infectious virus, and maintenance of the viral DNA genome in endless configuration, consistent with an episome configuration. With deep sequencing, however, multiple viral mRNAs were detected. Treatment of the latently infected neurons with Ab to NGF resulted in production of infectious virus in about 25% of the latently infected cultures. Axonal infection of neurons with vaccine Oka (VOka) VZV resulted in a latent infection similar to infection with POka; however, in contrast to POka, VOka-infected neurons were markedly impaired for reactivation after treatment with Ab to NGF. In addition, viral transcription was markedly reduced in neurons latently infected with VOka compared with POka. Our in vitro system recapitulates both VZV latency and reactivation in vivo and may be used to study viral vaccines for their ability to establish latency and reactivate.
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Affiliation(s)
- Tomohiko Sadaoka
- Medical Virology Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Daniel P Depledge
- Division of Infection and Immunity, MRC Centre for Medical Molecular Virology, University College London, London WC1E 6BT, United Kingdom
| | - Labchan Rajbhandari
- Division of Neuroimmunology and Neuroinfectious Diseases, Department of Neurology, Johns Hopkins University School of Medicine, Johns Hopkins Hospital, Baltimore, MD 21287
| | - Arun Venkatesan
- Division of Neuroimmunology and Neuroinfectious Diseases, Department of Neurology, Johns Hopkins University School of Medicine, Johns Hopkins Hospital, Baltimore, MD 21287
| | - Judith Breuer
- Division of Infection and Immunity, MRC Centre for Medical Molecular Virology, University College London, London WC1E 6BT, United Kingdom
| | - Jeffrey I Cohen
- Medical Virology Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892;
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9
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Fournier AJ, Rajbhandari L, Shrestha S, Venkatesan A, Ramesh KT. In vitro and in situ visualization of cytoskeletal deformation under load: traumatic axonal injury. FASEB J 2014; 28:5277-87. [PMID: 25205740 DOI: 10.1096/fj.14-251942] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
It is difficult to obtain insight into the mechanisms occurring within live cells during mechanical loading, because this complex environment is dynamic and evolving. This is a particular challenge from a subcellular mechanics perspective, where temporal and spatial information on the evolving cytoskeletal structures is required under loading. Using fluorescently labeled proteins, we visualize 3-dimensional live subcellular cytoskeletal populations under mechanical loading using a high-resolution confocal microscope. The mechanical forces are determined using a computational (finite element) model that is validated by integrating instrumentation into the testing platform. Transfected microtubules and neurofilaments of E17 rat neuronal axons are imaged before, during, and after loading. Comparisons between unloaded and loaded live cells demonstrate both spatial and temporal changes for cytoskeletal populations within the imaged volume. NF signal decreases by 24%, yet the microtubule signal exhibits no significant change 20-35 s after loading. Transmission electron microscopy assesses cytoskeletal structure spatial distribution for undeformed and deformed axons. While cytoskeletal degeneration occurs at prolonged time intervals following loads, our data provides insights into real time cytoskeletal evolution occurring in situ. Our findings suggest that, for axons undergoing traumatic injury in response to applied mechanical loads, changes at the substructural level of neurofilaments may precede microtubule rupture and degeneration.
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Affiliation(s)
- Adam J Fournier
- Mechanical Engineering Department, Johns Hopkins University, Baltimore, Maryland, USA; and
| | - Labchan Rajbhandari
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Shiva Shrestha
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Arun Venkatesan
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - K T Ramesh
- Mechanical Engineering Department, Johns Hopkins University, Baltimore, Maryland, USA; and
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10
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Rajbhandari L, Tegenge MA, Shrestha S, Ganesh Kumar N, Malik A, Mithal A, Hosmane S, Venkatesan A. Toll-like receptor 4 deficiency impairs microglial phagocytosis of degenerating axons. Glia 2014; 62:1982-91. [PMID: 25042766 DOI: 10.1002/glia.22719] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 06/25/2014] [Accepted: 06/25/2014] [Indexed: 01/19/2023]
Abstract
Microglia are rapidly activated in the central nervous system (CNS) in response to a variety of injuries, including inflammation, trauma, and stroke. In addition to modulation of the innate immune response, a key function of microglia is the phagocytosis of dying cells and cellular debris, which can facilitate recovery. Despite emerging evidence that axonal debris can pose a barrier to regeneration of new axons in the CNS, little is known of the cellular and molecular mechanisms that underlie clearance of degenerating CNS axons. We utilize a custom micropatterned microfluidic system that enables robust microglial-axon co-culture to explore the role of Toll-like receptors (TLRs) in microglial phagocytosis of degenerating axons. We find that pharmacologic and genetic disruption of TLR4 blocks induction of the Type-1 interferon response and inhibits phagocytosis of axon debris in vitro. Moreover, TLR4-dependent microglial clearance of unmyelinated axon debris facilitates axon outgrowth. In vivo, microglial phagocytosis of CNS axons undergoing Wallerian degeneration in a dorsal root axotomy model is impaired in adult mice in which TLR4 has been deleted. Since purinergic receptors can influence TLR4-mediated signaling, we also explored a role for the microglia P2 receptors and found that the P2X7R contributes to microglial clearance of degenerating axons. Overall, we identify TLR4 as a key player in axonal debris clearance by microglia, thus creating a more permissive environment for axonal outgrowth. Our findings have significant implications for the development of protective and regenerative strategies for the many inflammatory, traumatic, and neurodegenerative conditions characterized by CNS axon degeneration.
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Affiliation(s)
- Labchan Rajbhandari
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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11
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Hosmane S, Fournier A, Wright R, Rajbhandari L, Siddique R, Yang IH, Ramesh KT, Venkatesan A, Thakor N. Valve-based microfluidic compression platform: single axon injury and regrowth. Lab Chip 2011; 11:3888-95. [PMID: 21975691 DOI: 10.1039/c1lc20549h] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We describe a novel valve-based microfluidic axon injury micro-compression (AIM) platform that enables focal and graded compression of micron-scale segments of single central nervous system (CNS) axons. The device utilizes independently controlled "push-down" injury pads that descend upon pressure application and contact underlying axonal processes. Regulated compressed gas is input into the AIM system and pressure levels are modulated to specify the level of injury. Finite element modeling (FEM) is used to quantitatively characterize device performance and parameterize the extent of axonal injury by estimating the forces applied between the injury pad and glass substrate. In doing so, injuries are normalized across experiments to overcome small variations in device geometry. The AIM platform permits, for the first time, observation of axon deformation prior to, during, and immediately after focal mechanical injury. Single axons acutely compressed (~5 s) under varying compressive loads (0-250 kPa) were observed through phase time-lapse microscopy for up to 12 h post injury. Under mild injury conditions (< 55 kPa) ~73% of axons continued to grow, while at moderate (55-95 kPa) levels of injury, the number of growing axons dramatically reduced to 8%. At severe levels of injury (> 95 kPa), virtually all axons were instantaneously transected and nearly half (~46%) of these axons were able to regrow within the imaging period in the absence of exogenous stimulating factors.
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Affiliation(s)
- Suneil Hosmane
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Venkatesan A, Uzasci L, Chen Z, Rajbhandari L, Anderson C, Lee MH, Bianchet MA, Cotter R, Song H, Nath A. Impairment of adult hippocampal neural progenitor proliferation by methamphetamine: role for nitrotyrosination. Mol Brain 2011; 4:28. [PMID: 21708025 PMCID: PMC3142219 DOI: 10.1186/1756-6606-4-28] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 06/27/2011] [Indexed: 11/24/2022] Open
Abstract
Methamphetamine (METH) abuse has reached epidemic proportions, and it has become increasingly recognized that abusers suffer from a wide range of neurocognitive deficits. Much previous work has focused on the deleterious effects of METH on mature neurons, but little is known about the effects of METH on neural progenitor cells (NPCs). It is now well established that new neurons are continuously generated from NPCs in the adult hippocampus, and accumulating evidence suggests important roles for these neurons in hippocampal-dependent cognitive functions. In a rat hippocampal NPC culture system, we find that METH results in a dose-dependent reduction of NPC proliferation, and higher concentrations of METH impair NPC survival. NPC differentiation, however, is not affected by METH, suggesting cell-stage specificity of the effects of METH. We demonstrate that the effects of METH on NPCs are, in part, mediated through oxidative and nitrosative stress. Further, we identify seventeen NPC proteins that are post-translationally modified via 3-nitrotyrosination in response to METH, using mass spectrometric approaches. One such protein was pyruvate kinase isoform M2 (PKM2), an important mediator of cellular energetics and proliferation. We identify sites of PKM2 that undergo nitrotyrosination, and demonstrate that nitration of the protein impairs its activity. Thus, METH abuse may result in impaired adult hippocampal neurogenesis, and effects on NPCs may be mediated by protein nitration. Our study has implications for the development of novel therapeutic approaches for METH-abusing individuals with neurologic dysfunction and may be applicable to other neurodegenerative diseases in which hippocampal neurogenesis is impaired.
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Affiliation(s)
- Arun Venkatesan
- Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
| | - Lerna Uzasci
- Middle Atlantic Mass Spectrometry Laboratory, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
- Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
| | - Zhaohui Chen
- Middle Atlantic Mass Spectrometry Laboratory, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
| | - Labchan Rajbhandari
- Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
| | - Carol Anderson
- Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
- National Institutes of Health, Section of Infections of the Nervous Systems, Bldg 10-CRC, Room 7C103; Bethesda, MD 20892
| | - Myoung-Hwa Lee
- Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
- National Institutes of Health, Section of Infections of the Nervous Systems, Bldg 10-CRC, Room 7C103; Bethesda, MD 20892
| | - Mario A Bianchet
- Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
| | - Robert Cotter
- Middle Atlantic Mass Spectrometry Laboratory, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
- Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
| | - Hongjun Song
- Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
| | - Avindra Nath
- Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA
- National Institutes of Health, Section of Infections of the Nervous Systems, Bldg 10-CRC, Room 7C103; Bethesda, MD 20892
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