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Heyburn L, Dahal S, Abutarboush R, Reed E, Urioste R, Batuure A, Wilder D, Ahlers ST, Long JB, Sajja VS. Differential effects on TDP-43, piezo-2, tight-junction proteins in various brain regions following repetitive low-intensity blast overpressure. Front Neurol 2023; 14:1237647. [PMID: 37877029 PMCID: PMC10593467 DOI: 10.3389/fneur.2023.1237647] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 09/15/2023] [Indexed: 10/26/2023] Open
Abstract
Introduction Mild traumatic brain injury (mTBI) caused by repetitive low-intensity blast overpressure (relBOP) in military personnel exposed to breaching and heavy weapons is often unrecognized and is understudied. Exposure to relBOP poses the risk of developing abnormal behavioral and psychological changes such as altered cognitive function, anxiety, and depression, all of which can severely compromise the quality of the life of the affected individual. Due to the structural and anatomical heterogeneity of the brain, understanding the potentially varied effects of relBOP in different regions of the brain could lend insights into the risks from exposures. Methods In this study, using a rodent model of relBOP and western blotting for protein expression we showed the differential expression of various neuropathological proteins like TDP-43, tight junction proteins (claudin-5, occludin, and glial fibrillary acidic protein (GFAP)) and a mechanosensitive protein (piezo-2) in different regions of the brain at different intensities and frequency of blast. Results Our key results include (i) significant increase in claudin-5 after 1x blast of 6.5 psi in all three regions and no definitive pattern with higher number of blasts, (ii) significant increase in piezo-2 at 1x followed by significant decrease after multiple blasts in the cortex, (iii) significant increase in piezo-2 with increasing number of blasts in frontal cortex and mixed pattern of expression in hippocampus and (iv) mixed pattern of TDP-3 and GFAP expression in all the regions of brain. Discussion These results suggest that there are not definitive patterns of changes in these marker proteins with increase in intensity and/or frequency of blast exposure in any particular region; the changes in expression of these proteins are different among the regions. We also found that the orientation of blast exposure (e.g. front vs. side exposure) affects the altered expression of these proteins.
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Affiliation(s)
- Lanier Heyburn
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Shataakshi Dahal
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
- The Geneva Foundation, Tacoma, WA, United States
| | | | - Eileen Reed
- Naval Medical Research Center, Silver Spring, MD, United States
| | - Rodrigo Urioste
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Andrew Batuure
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Donna Wilder
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | | | - Joseph B. Long
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
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Heyburn L, Batuure A, Wilder D, Long J, Sajja VS. Neuroinflammation Profiling of Brain Cytokines Following Repeated Blast Exposure. Int J Mol Sci 2023; 24:12564. [PMID: 37628746 PMCID: PMC10454588 DOI: 10.3390/ijms241612564] [Citation(s) in RCA: 3] [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: 06/23/2023] [Revised: 08/02/2023] [Accepted: 08/05/2023] [Indexed: 08/27/2023] Open
Abstract
Due to use of explosive devices and heavy weapons systems in modern conflicts, the effect of BW on the brain and body is of increasing concern. These exposures have been commonly linked with neurodegenerative diseases and psychiatric disorders in veteran populations. A likely neurobiological link between exposure to blasts and the development of neurobehavioral disorders, such as depression and PTSD, could be neuroinflammation triggered by the blast wave. In this study, we exposed rats to single or repeated BW (up to four exposures-one per day) at varied intensities (13, 16, and 19 psi) to mimic the types of blast exposures that service members may experience in training and combat. We then measured a panel of neuroinflammatory markers in the brain tissue with a multiplex cytokine/chemokine assay to understand the pathophysiological process(es) associated with single and repeated blast exposures. We found that single and repeated blast exposures promoted neuroinflammatory changes in the brain that are similar to those characterized in several neurological disorders; these effects were most robust after 13 and 16 psi single and repeated blast exposures, and they exceeded those recorded after 19 psi repeated blast exposures. Tumor necrosis factor-alpha and IL-10 were changed by 13 and 16 psi single and repeated blast exposures. In conclusion, based upon the growing prominence of negative psychological health outcomes in veterans and soldiers with a history of blast exposures, identifying the molecular etiology of these disorders, such as blast-induced neuroinflammation, is necessary for rationally establishing countermeasures and treatment regimens.
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Bergmann-Leitner ES, Bobrov AG, Bolton JS, Rouse MD, Heyburn L, Pavlovic R, Garry BI, Alamneh Y, Long J, Swierczewski B, Tyner S, Getnet D, Sajja VS, Antonic V. Blast Waves Cause Immune System Dysfunction and Transient Bone Marrow Failure in a Mouse Model. Front Bioeng Biotechnol 2022; 10:821169. [PMID: 35392409 PMCID: PMC8980552 DOI: 10.3389/fbioe.2022.821169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 02/23/2022] [Indexed: 11/29/2022] Open
Abstract
Explosive devices, either conventional or improvised, are common sources of injuries during combat, civil unrest, and terror attacks, resulting in trauma from exposure to blast. A blast wave (BW), a near-instantaneous rise in pressure followed by a negative pressure, propagates through the body in milliseconds and can affect physiology for days/months after exposure. Epidemiological data show that blast-related casualties result in significantly higher susceptibility to wound infections, suggesting long-lasting immune modulatory effects from blast exposure. The mechanisms involved in BW-induced immune changes are poorly understood. We evaluated the effects of BW on the immune system using an established murine model. Animals were exposed to BWs (using an Advanced Blast Simulator), followed by longitudinally sampling for 14 days. Blood, bone marrow, and spleen were analyzed for changes in the 1) complete blood count (CBC), and 2) composition of bone marrow cells (BMC) and splenocytes, and 3) concentrations of systemic cytokines/chemokines. Our data demonstrate that BW results in transient bone marrow failure and long-term changes in the frequency and profile of progenitor cell populations. Viability progressively decreased in hematopoietic stem cells and pluripotent progenitor cells. Significant decrease of CD4+ T cells in the spleen indicates reduced functionality of adaptive immune system. Dynamic changes in the concentrations of several cytokines and chemokines such as IL-1α and IL-17 occurred potentially contributing to dysregulation of immune response after trauma. This work lays the foundation for identifying the potential mechanisms behind BW’s immunosuppressive effects to inform the recognition of this compromised status is crucial for the development of therapeutic interventions for infections to reduce recovery time of wounded patients injured by explosive devices.
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Affiliation(s)
- Elke S. Bergmann-Leitner
- Biologics Research and Development, Walter Reed Army Institute of Research, Silver Spring, MD, United States
- *Correspondence: Elke S. Bergmann-Leitner, ; Venkatasivasai S. Sajja, ; Vlado Antonic,
| | - Alexander G. Bobrov
- Wound Infections Department, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Jessica S. Bolton
- Biologics Research and Development, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Michael D. Rouse
- Wound Infections Department, Naval Research Medical Center, Silver Spring, MD, United States
- Henry M. Jackson Foundation, Rockville, MD, United States
| | - Lanier Heyburn
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Radmila Pavlovic
- Wound Infections Department, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Brittany I. Garry
- Wound Infections Department, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Yonas Alamneh
- Wound Infections Department, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Joseph Long
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Brett Swierczewski
- Bacterial Disease Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Stuart Tyner
- Military Infectious Diseases Research Program, Frederick, MD, United States
| | - Derese Getnet
- Wound Infections Department, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Venkatasivasai S. Sajja
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
- *Correspondence: Elke S. Bergmann-Leitner, ; Venkatasivasai S. Sajja, ; Vlado Antonic,
| | - Vlado Antonic
- Wound Infections Department, Walter Reed Army Institute of Research, Silver Spring, MD, United States
- *Correspondence: Elke S. Bergmann-Leitner, ; Venkatasivasai S. Sajja, ; Vlado Antonic,
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Heyburn L, Abutarboush R, Goodrich S, Urioste R, Batuure A, Wheel J, Wilder DM, Arun P, Ahlers ST, Long JB, Sajja VS. Repeated Low-Level Blast Acutely Alters Brain Cytokines, Neurovascular Proteins, Mechanotransduction, and Neurodegenerative Markers in a Rat Model. Front Cell Neurosci 2021; 15:636707. [PMID: 33679327 PMCID: PMC7933446 DOI: 10.3389/fncel.2021.636707] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 01/26/2021] [Indexed: 12/16/2022] Open
Abstract
Exposure to the repeated low-level blast overpressure (BOP) periodically experienced by military personnel in operational and training environments can lead to deficits in behavior and cognition. While these low-intensity blasts do not cause overt changes acutely, repeated exposures may lead to cumulative effects in the brain that include acute inflammation, vascular disruption, and other molecular changes, which may eventually contribute to neurodegenerative processes. To identify these acute changes in the brain following repeated BOP, an advanced blast simulator was used to expose rats to 8.5 or 10 psi BOP once per day for 14 days. At 24 h after the final BOP, brain tissue was collected and analyzed for inflammatory markers, astrogliosis (GFAP), tight junction proteins (claudin-5 and occludin), and neurodegeneration-related proteins (Aβ40/42, pTau, TDP-43). After repeated exposure to 8.5 psi BOP, the change in cytokine profile was relatively modest compared to the changes observed following 10 psi BOP, which included a significant reduction in several inflammatory markers. Reduction in the tight junction protein occludin was observed in both groups when compared to controls, suggesting cerebrovascular disruption. While repeated exposure to 8.5 psi BOP led to a reduction in the Alzheimer’s disease (AD)-related proteins amyloid-β (Aβ)40 and Aβ42, these changes were not observed in the 10 psi group, which had a significant reduction in phosphorylated tau. Finally, repeated 10 psi BOP exposures led to an increase in GFAP, indicating alterations in astrocytes, and an increase in the mechanosensitive ion channel receptor protein, Piezo2, which may increase brain sensitivity to injury from pressure changes from BOP exposure. Overall, cumulative effects of repeated low-level BOP may increase the vulnerability to injury of the brain by disrupting neurovascular architecture, which may lead to downstream deleterious effects on behavior and cognition.
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Affiliation(s)
- Lanier Heyburn
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Rania Abutarboush
- Neurotrauma Department, Operational and Undersea Medicine Directorate, Naval Medical Research Center, Silver Spring, MD, United States
| | - Samantha Goodrich
- Neurotrauma Department, Operational and Undersea Medicine Directorate, Naval Medical Research Center, Silver Spring, MD, United States
| | - Rodrigo Urioste
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Andrew Batuure
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Jaimena Wheel
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Donna M Wilder
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Peethambaran Arun
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Stephen T Ahlers
- Neurotrauma Department, Operational and Undersea Medicine Directorate, Naval Medical Research Center, Silver Spring, MD, United States
| | - Joseph B Long
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Venkatasivasai Sujith Sajja
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
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Heyburn L, Abutarboush R, Goodrich S, Urioste R, Batuure A, Statz J, Wilder D, Ahlers ST, Long JB, Sajja VSSS. Repeated Low-Level Blast Overpressure Leads to Endovascular Disruption and Alterations in TDP-43 and Piezo2 in a Rat Model of Blast TBI. Front Neurol 2019; 10:766. [PMID: 31417481 PMCID: PMC6682625 DOI: 10.3389/fneur.2019.00766] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 07/01/2019] [Indexed: 11/29/2022] Open
Abstract
Recent evidence linking repeated low-level blast overpressure exposure in operational and training environments with neurocognitive decline, neuroinflammation, and neurodegenerative processes has prompted concern over the cumulative deleterious effects of repeated blast exposure on the brains of service members. Repetitive exposure to low-level primary blast may cause symptoms (subclinical) similar to those seen in mild traumatic brain injury (TBI), with progressive vascular and cellular changes, which could contribute to neurodegeneration. At the cellular level, the mechanical force associated with blast exposure can cause cellular perturbations in the brain, leading to secondary injury. To examine the cumulative effects of repetitive blast on the brain, an advanced blast simulator (ABS) was used to closely mimic “free-field” blast. Rats were exposed to 1–4 daily blasts (one blast per day, separated by 24 h) at 13, 16, or 19 psi peak incident pressures with a positive duration of 4–5 ms, either in a transverse or longitudinal orientation. Blood-brain barrier (BBB) markers (vascular endothelial growth factor (VEGF), occludin, and claudin-5), transactive response DNA binding protein (TDP-43), and the mechanosensitive channel Piezo2 were measured following blast exposure. Changes in expression of VEGF, occludin, and claudin-5 after repeated blast exposure indicate alterations in the BBB, which has been shown to be disrupted following TBI. TDP-43 is very tightly regulated in the brain and altered expression of TDP-43 is found in clinically-diagnosed TBI patients. TDP-43 levels were differentially affected by the number and magnitude of blast exposures, decreasing after 2 exposures, but increasing following a greater number of exposures at various intensities. Lastly, Piezo2 has been shown to be dysregulated following blast exposure and was here observed to increase after multiple blasts of moderate magnitude, indicating that blast may cause a change in sensitivity to mechanical stimuli in the brain and may contribute to cellular injury. These findings reveal that cumulative effects of repeated exposures to blast can lead to pathophysiological changes in the brain, demonstrating a possible link between blast injury and neurodegenerative disease, which is an important first step in understanding how to prevent these diseases in soldiers exposed to blast.
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Affiliation(s)
- Lanier Heyburn
- Walter Reed Army Institute of Research, Blast Induced Neurotrauma Branch, Silver Spring, MD, United States
| | - Rania Abutarboush
- Neurotrauma Department, Naval Medical Research Center, Silver Spring, MD, United States.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
| | - Samantha Goodrich
- Neurotrauma Department, Naval Medical Research Center, Silver Spring, MD, United States.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
| | - Rodrigo Urioste
- Walter Reed Army Institute of Research, Blast Induced Neurotrauma Branch, Silver Spring, MD, United States
| | - Andrew Batuure
- Walter Reed Army Institute of Research, Blast Induced Neurotrauma Branch, Silver Spring, MD, United States
| | - Jonathan Statz
- Neurotrauma Department, Naval Medical Research Center, Silver Spring, MD, United States.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
| | - Donna Wilder
- Walter Reed Army Institute of Research, Blast Induced Neurotrauma Branch, Silver Spring, MD, United States
| | - Stephen T Ahlers
- Neurotrauma Department, Naval Medical Research Center, Silver Spring, MD, United States
| | - Joseph B Long
- Walter Reed Army Institute of Research, Blast Induced Neurotrauma Branch, Silver Spring, MD, United States
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Abstract
Due largely to the use of improvised explosive devices (IEDs) and other explosives in recent military conflicts, blast-related TBI has emerged as a prominent injury sustained by warfighters. In the recent wars in Iraq and Afghanistan, traumatic brain injury (TBI) has been one of the most common types of injury sustained by soldiers and military personnel; of the ~380,000 TBIs reported in service members from 2000 to 2017, 82.3% were classified as mild (mTBI). While mTBI is associated with normal structural imaging, brief or no loss of consciousness, and rapid recovery of mental state, mTBI can nevertheless lead to persistent behavioral and cognitive effects. As in other cases of mTBI, exposure to low-level blast often does not cause immediate overt neurological effects, but may similarly lead to persistent behavioral and cognitive deficits. These effects are likely to be compounded when multiple exposures to blast and/or impact are sustained, since there is increasing evidence that multiple mTBIs can lead to chronic neurodegeneration. One common form of this deleterious outcome is frontotemporal lobar degeneration (FTLD), which is a progressive neurodegenerative process marked by atrophy of the frontal and temporal lobes, leading to frontotemporal dementia, a common form of dementia affecting behavior, cognition and language. About half of all cases of FTLD are marked by TAR-DNA binding protein (TDP-43)-positive protein inclusions. TDP-43, a DNA/RNA binding protein, controls the expression of thousands of genes and is associated with several neurodegenerative diseases including amyotrophic lateral sclerosis, Alzheimer's disease, Huntington's disease, and chronic traumatic encephalopathy. TDP-43 abnormalities have also been associated with traumatic brain injury in both pre-clinical and clinical studies. The role of TDP-43 in the manifestation of FTLD pathology in military TBI cases is currently unclear, and to date there has been only a limited number of pre-clinical studies addressing the effects of repeated blast-related mild TBI (rbTBI) in relation to FTLD and TDP-43. This review will summarize some of these findings and address the concerns and critical knowledge gaps associated with FTLD manifestation with military populations, as well as clinical findings on other forms of mTBI.
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Affiliation(s)
- Lanier Heyburn
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Venkata S S S Sajja
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Joseph B Long
- Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
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Heyburn L, Moussa CEH. TDP-43 in the spectrum of MND-FTLD pathologies. Mol Cell Neurosci 2017; 83:46-54. [PMID: 28687523 DOI: 10.1016/j.mcn.2017.07.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 06/28/2017] [Accepted: 07/04/2017] [Indexed: 12/12/2022] Open
Abstract
The relationship between RNA-binding proteins, particularly TAR DNA binding protein 43 (TDP-43), and neurodegeneration is an important area of research. TDP-43 is involved in so many cellular processes that perturbation of protein homeostasis can lead to countless downstream effects. Understanding what leads to this disease-related protein imbalance and the resulting cellular and molecular effects will help to develop targets for disease intervention, whether it be prevention of protein accumulation, or addressing a secondary effect of protein accumulation. Here we review the current literature of TDP-43 and TDP-43 pathologies, the effects of TDP-43 overexpression and disruption of synaptic proteins through its binding of messenger RNA, leading to synaptic dysfunction. This review highlights some of the still-limited knowledge of the protein TDP-43 and how it can contribute to disease.
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Affiliation(s)
- Lanier Heyburn
- Department of Neurology, Translational Neurotherapeutics Program, Laboratory for Dementia and Parkinsonism, Georgetown University Medical Center, Washington D.C. 20007, USA; Department of Pathology, Georgetown University Medical Center, Washington D.C., USA 20007.
| | - Charbel E-H Moussa
- Department of Neurology, Translational Neurotherapeutics Program, Laboratory for Dementia and Parkinsonism, Georgetown University Medical Center, Washington D.C. 20007, USA
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Lee SJ, Zhu W, Heyburn L, Nowicki M, Harris B, Zhang LG. Development of Novel 3-D Printed Scaffolds With Core-Shell Nanoparticles for Nerve Regeneration. IEEE Trans Biomed Eng 2017; 64:408-418. [DOI: 10.1109/tbme.2016.2558493] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Heyburn L, Hebron ML, Smith J, Winston C, Bechara J, Li Z, Lonskaya I, Burns MP, Harris BT, Moussa CEH. Tyrosine kinase inhibition reverses TDP-43 effects on synaptic protein expression, astrocytic function and amino acid dis-homeostasis. J Neurochem 2016; 139:610-623. [PMID: 27507246 DOI: 10.1111/jnc.13763] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [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: 06/03/2016] [Revised: 07/22/2016] [Accepted: 08/02/2016] [Indexed: 01/25/2023]
Abstract
The trans-activating response of DNA/RNA-binding protein (TDP)-43 pathology is associated with many neurodegenerative diseases via unknown mechanisms. Here, we use a transgenic mouse model over-expressing human wild-type neuronal TDP-43 to study the effects of TDP-43 pathology on glutamate metabolism and synaptic function. We found that neuronal TDP-43 over-expression affects synaptic protein expression, including Synapsin I, and alters surrounding astrocytic function. TDP-43 over-expression is associated with an increase in glutamate and γ-amino butyric acid and reduction of glutamine and aspartate levels, indicating impairment of presynaptic terminal. TDP-43 also decreases tricarboxylic acid cycle metabolism and induces oxidative stress via lactate accumulation. Neuronal TDP-43 does not alter microglia activity or significantly changes systemic and brain inflammatory markers compared to control. We previously demonstrated that brain-penetrant tyrosine kinase inhibitors (TKIs), nilotinib and bosutinib, reduce TDP-43-induced cell death in transgenic mice. Here, we show that TKIs reverse the effects of TDP-43 on synaptic proteins, increase astrocytic function and restore glutamate and neurotransmitter balance in TDP-43 mice. Nilotinib, but not bosutinib, reverses mitochondrial impairment and oxidative metabolism. Taken together, these data suggest that TKIs can attenuate TDP-43 toxicity and improve synaptic and astrocytic function, independent of microglial or other inflammatory effects. In conclusion, our data demonstrate novel mechanisms of the effects of neuronal TDP-43 over-expression on synaptic protein expression and alteration of astrocytic function.
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Affiliation(s)
- Lanier Heyburn
- Laboratory for Dementia and Parkinsonism, Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia, USA.,Department of Pathology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Michaeline L Hebron
- Laboratory for Dementia and Parkinsonism, Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Jacqueline Smith
- Drug Discovery Center, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Charisse Winston
- Trauma and Dementia Laboratory, Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - John Bechara
- Laboratory for Dementia and Parkinsonism, Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Zhaoxia Li
- Laboratory for Dementia and Parkinsonism, Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia, USA.,School of Traditional Chinese Medicine, Capital Medical University, Fengtai District, Beijing, China
| | - Irina Lonskaya
- Laboratory for Dementia and Parkinsonism, Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Mark P Burns
- Trauma and Dementia Laboratory, Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Brent T Harris
- Laboratory for Dementia and Parkinsonism, Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia, USA.,Department of Pathology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Charbel E-H Moussa
- Laboratory for Dementia and Parkinsonism, Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia, USA
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Affiliation(s)
- Lanier Heyburn
- Department of Neurology, Laboratory for Dementia and Parkinsonism, Translational Neurotherapeutics Program, Georgetown University Medical Center, Washington D.C., USA
| | - Charbel E-H Moussa
- Department of Neurology, Laboratory for Dementia and Parkinsonism, Translational Neurotherapeutics Program, Georgetown University Medical Center, Washington D.C., USA
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Degtyareva NP, Heyburn L, Sterling J, Resnick MA, Gordenin DA, Doetsch PW. Oxidative stress-induced mutagenesis in single-strand DNA occurs primarily at cytosines and is DNA polymerase zeta-dependent only for adenines and guanines. Nucleic Acids Res 2013; 41:8995-9005. [PMID: 23925127 PMCID: PMC3799438 DOI: 10.1093/nar/gkt671] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Localized hyper-mutability caused by accumulation of lesions in persistent single-stranded (ss) DNA has been recently found in several types of cancers. An increase in endogenous levels of reactive oxygen species (ROS) is considered to be one of the hallmarks of cancers. Employing a yeast model system, we addressed the role of oxidative stress as a potential source of hyper-mutability in ssDNA by modulation of the endogenous ROS levels and by exposing cells to oxidative DNA-damaging agents. We report here that under oxidative stress conditions the majority of base substitution mutations in ssDNA are caused by erroneous, DNA polymerase (Pol) zeta-independent bypass of cytosines, resulting in C to T transitions. For all other DNA bases Pol zeta is essential for ROS-induced mutagenesis. The density of ROS-induced mutations in ssDNA is lower, compared to that caused by UV and MMS, which suggests that ssDNA could be actively protected from oxidative damage. These findings have important implications for understanding mechanisms of oxidative mutagenesis, and could be applied to development of anticancer therapies and cancer prevention.
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Affiliation(s)
- Natalya P Degtyareva
- Department of Biochemistry, Winship Cancer Institute, Emory University School of Medicine, 4013 Rollins Research Center, Atlanta, GA 30322, USA, Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences (NIH, DHHS), Research Triangle Park, NC 27709, USA and Department of Radiation Oncology, Emory University School of Medicine, 4013 Rollins Research Center, Atlanta, GA 30322, USA
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Morris LP, Degtyareva N, Sheppard C, Heyburn L, Ivanov AA, Kow YW, Doetsch PW. Saccharomyces cerevisiae Apn1 mutation affecting stable protein expression mimics catalytic activity impairment: implications for assessing DNA repair capacity in humans. DNA Repair (Amst) 2012; 11:753-65. [PMID: 22818187 DOI: 10.1016/j.dnarep.2012.06.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 06/18/2012] [Accepted: 06/25/2012] [Indexed: 11/18/2022]
Abstract
Apurinic/apyrimidinic (AP) endonucleases play a major role in the repair of AP sites, oxidative damage and alkylation damage in DNA. We employed Saccharomyces cerevisiae in an unbiased forward genetic screen to identify amino acid substitutions in the major yeast AP endonuclease, Apn1, that impair cellular DNA repair capacity by conferring sensitivity to the DNA alkylating agent methyl methanesulfonate. We report here the identification and characterization of the Apn1 V156E amino acid substitution mutant through biochemical and functional analysis. We found that steady state levels of Apn1 V156E were substantially decreased compared to wild type protein, and that this decrease was due to more rapid degradation of mutant protein compared to wild type. Based on homology to E. coli endonuclease IV and computational modeling, we predicted that V156E impairs catalytic ability. However, overexpression of mutant protein restored DNA repair activity in vitro and in vivo. Thus, the V156E substitution decreases DNA repair capacity by an unanticipated mechanism via increased degradation of mutant protein, leading to substantially reduced cellular levels. Our study provides evidence that the V156 residue plays a critical role in Apn1 structural integrity, but is not involved in catalytic activity. These results have important implications for elucidating structure-function relationships for the endonuclease IV family of proteins, and for employing simple eukaryotic model systems to understand how structural defects in the major human AP endonuclease APE1 may contribute to disease etiology.
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Affiliation(s)
- Lydia P Morris
- Program in Genetics and Molecular Biology, Graduate Division of Biological and Biomedical Sciences, James T. Laney School of Graduate Studies, Emory University, USA
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