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Zhao R, Wu X, Bi XY, Yang H, Zhang Q. Baicalin attenuates blood-spinal cord barrier disruption and apoptosis through PI3K/Akt signaling pathway after spinal cord injury. Neural Regen Res 2022; 17:1080-1087. [PMID: 34558536 PMCID: PMC8552841 DOI: 10.4103/1673-5374.324857] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/07/2021] [Accepted: 07/08/2021] [Indexed: 11/19/2022] Open
Abstract
Baicalin is a natural active ingredient isolated from Scutellariae Radix that can cross the blood-brain barrier and exhibits neuroprotective effects on multiple central nervous system diseases. However, the mechanism behind the neuroprotective effects remains unclear. In this study, rat models of spinal cord injury were established using a modified Allen's impact method and then treated with intraperitoneal injection of Baicalin. The results revealed that Baicalin greatly increased the Basso, Beattie, Bresnahan Locomotor Rating Scale score, reduced blood-spinal cord barrier permeability, decreased the expression of Bax, Caspase-3, and nuclear factor κB, increased the expression of Bcl-2, and reduced neuronal apoptosis and pathological spinal cord injury. SH-SY5Y cell models of excitotoxicity were established by application of 10 mM glutamate for 12 hours and then treated with 40 µM Baicalin for 48 hours to investigate the mechanism of action of Baicalin. The results showed that Baicalin reversed tight junction protein expression tendencies (occludin and ZO-1) and apoptosis-related protein expression (Bax, Bcl-2, Caspase-3, and nuclear factor-κB), and also led to up-regulation of PI3K and Akt phosphorylation. These effects on Bax, Bcl-2, and Caspase-3 were blocked by pretreatment with the PI3K inhibitor LY294002. These findings suggest that Baicalin can inhibit blood-spinal cord barrier permeability after spinal cord injury and reduce neuronal apoptosis, possibly by activating the PI3K/Akt signaling pathway. This study was approved by Animal Ethics Committee of Xi'an Jiaotong University on March 6, 2014.
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Affiliation(s)
- Rui Zhao
- College of Pharmacy, Shaanxi University of Chinese Medicine, Xi’an, Shaanxi Province, China
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi’an, Shaanxi Province, China
- Translational Medicine Center, Hong Hui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi Province, China
| | - Xue Wu
- College of Pharmacy, Shaanxi University of Chinese Medicine, Xi’an, Shaanxi Province, China
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi’an, Shaanxi Province, China
- Translational Medicine Center, Hong Hui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi Province, China
| | - Xue-Yuan Bi
- Department of Pharmacy, Hong Hui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi Province, China
| | - Hao Yang
- College of Pharmacy, Shaanxi University of Chinese Medicine, Xi’an, Shaanxi Province, China
- Translational Medicine Center, Hong Hui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi Province, China
| | - Qian Zhang
- College of Pharmacy, Shaanxi University of Chinese Medicine, Xi’an, Shaanxi Province, China
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi’an, Shaanxi Province, China
- Translational Medicine Center, Hong Hui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi Province, China
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2
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In vitro investigation of zinc oxide nanoparticle toxic effects in spermatogonial cells at the molecular level. Chem Biol Interact 2021; 351:109687. [PMID: 34653396 DOI: 10.1016/j.cbi.2021.109687] [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: 06/08/2021] [Revised: 09/18/2021] [Accepted: 10/05/2021] [Indexed: 11/20/2022]
Abstract
Because spermatogonia transmit genetic information across generations, their DNA must be protected from environmental damages, including exposure to zinc oxide nanoparticles (ZnO NPs), which are frequently used in modern technology. Here, we used an in vitro system enriched for spermatogonia and exposed them to 10 and 20 μg/ml ZnO NPs for one/seven days. We did not detect any significant cell death, chromosomal instability, or DNA fragmentation in the spermatogonia treated with the ZnO NPs following one-day treatment with 10 or 20 μg/ml ZnO NPs. However, ZnO NPs (both 10 and 20 μg/ml) induced chromosomal instability in the spermatogonia after seven days of treatment. Moreover, one-day exposure to these NPs induced reactive oxygen species (ROS) generation and upregulation of apoptotic pathway-related genes p53, Caspase3 and Il6, as an inflammatory factor. Taken together, our study provides preliminary evidence for possible damages induced by low concentrations of ZnO NPs in spermatogonia. We should pay increased attention when using these NPs because of the silent damages in spermatogonia that can be transmitted to the next generation and cause severe effects. However, more data and validation of these results are required to determine the extent of this concern.
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Rodemer W, Selzer ME. Role of axon resealing in retrograde neuronal death and regeneration after spinal cord injury. Neural Regen Res 2019; 14:399-404. [PMID: 30539805 PMCID: PMC6334596 DOI: 10.4103/1673-5374.245330] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Spinal cord injury leads to persistent behavioral deficits because mammalian central nervous system axons fail to regenerate. A neuron's response to axon injury results from a complex interplay of neuron-intrinsic and environmental factors. The contribution of axotomy to the death of neurons in spinal cord injury is controversial because very remote axotomy is unlikely to result in neuronal death, whereas death of neurons near an injury may reflect environmental factors such as ischemia and inflammation. In lampreys, axotomy due to spinal cord injury results in delayed apoptosis of spinal-projecting neurons in the brain, beyond the extent of these environmental factors. This retrograde apoptosis correlates with delayed resealing of the axon, and can be reversed by inducing rapid membrane resealing with polyethylene glycol. Studies in mammals also suggest that polyethylene glycol may be neuroprotective, although the mechanism(s) remain unclear. This review examines the early, mechanical, responses to axon injury in both mammals and lampreys, and the potential of polyethylene glycol to reduce injury-induced pathology. Identifying the mechanisms underlying a neuron's response to axotomy will potentially reveal new therapeutic targets to enhance regeneration and functional recovery in humans with spinal cord injury.
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Affiliation(s)
- William Rodemer
- Shriners Hospital Pediatric Research Center (Center for Neural Repair and Rehabilitation), Philadelphia, PA, USA
| | - Michael E Selzer
- Shriners Hospital Pediatric Research Center (Center for Neural Repair and Rehabilitation); Department of Neurology, the Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
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GABA promotes survival and axonal regeneration in identifiable descending neurons after spinal cord injury in larval lampreys. Cell Death Dis 2018; 9:663. [PMID: 29950557 PMCID: PMC6021415 DOI: 10.1038/s41419-018-0704-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 04/24/2018] [Accepted: 05/14/2018] [Indexed: 12/25/2022]
Abstract
The poor regenerative capacity of descending neurons is one of the main causes of the lack of recovery after spinal cord injury (SCI). Thus, it is of crucial importance to find ways to promote axonal regeneration. In addition, the prevention of retrograde degeneration leading to the atrophy/death of descending neurons is an obvious prerequisite to activate axonal regeneration. Lampreys show an amazing regenerative capacity after SCI. Recent histological work in lampreys suggested that GABA, which is massively released after a SCI, could promote the survival of descending neurons. Here, we aimed to study if GABA, acting through GABAB receptors, promotes the survival and axonal regeneration of descending neurons of larval sea lampreys after a complete SCI. First, we used in situ hybridization to confirm that identifiable descending neurons of late-stage larvae express the gabab1 subunit of the GABAB receptor. We also observed an acute increase in the expression of this subunit in descending neurons after SCI, which further supported the possible role of GABA and GABAB receptors in promoting the survival and regeneration of these neurons. So, we performed gain and loss of function experiments to confirm this hypothesis. Treatments with GABA and baclofen (GABAB agonist) significantly reduced caspase activation in descending neurons 2 weeks after a complete SCI. Long-term treatments with GABOB (a GABA analogue) and baclofen significantly promoted axonal regeneration of descending neurons after SCI. These data indicate that GABAergic signalling through GABAB receptors promotes the survival and regeneration of descending neurons after SCI. Finally, we used morpholinos against the gabab1 subunit to knockdown the expression of the GABAB receptor in descending neurons. Long-term morpholino treatments caused a significant inhibition of axonal regeneration. This shows that endogenous GABA promotes axonal regeneration after a complete SCI in lampreys by activating GABAB receptors.
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5
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Sobrido-Cameán D, Barreiro-Iglesias A. Role of Caspase-8 and Fas in Cell Death After Spinal Cord Injury. Front Mol Neurosci 2018; 11:101. [PMID: 29666570 PMCID: PMC5891576 DOI: 10.3389/fnmol.2018.00101] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/15/2018] [Indexed: 01/10/2023] Open
Abstract
Spinal cord injury (SCI) causes the death of neurons and glial cells due to the initial mechanical forces (i.e., primary injury) and through a cascade of secondary molecular events (e.g., inflammation or excitotoxicity) that exacerbate cell death. The loss of neurons and glial cells that are not replaced after the injury is one of the main causes of disability after SCI. Evidence accumulated in last decades has shown that the activation of apoptotic mechanisms is one of the factors causing the death of intrinsic spinal cord (SC) cells following SCI. Although this is not as clear for brain descending neurons, some studies have also shown that apoptosis can be activated in the brain following SCI. There are two main apoptotic pathways, the extrinsic and the intrinsic pathways. Activation of caspase-8 is an important step in the initiation of the extrinsic pathway. Studies in rodents have shown that caspase-8 is activated in SC glial cells and neurons and that the Fas receptor plays a key role in its activation following a traumatic SCI. Recent work in the lamprey model of SCI has also shown the retrograde activation of caspase-8 in brain descending neurons following SCI. Here, we review our current knowledge on the role of caspase-8 and the Fas pathway in cell death following SCI. We also provide a perspective for future work on this process, like the importance of studying the possible contribution of Fas/caspase-8 signaling in the degeneration of brain neurons after SCI in mammals.
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Affiliation(s)
- Daniel Sobrido-Cameán
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Antón Barreiro-Iglesias
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
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Retrograde Activation of the Extrinsic Apoptotic Pathway in Spinal-Projecting Neurons after a Complete Spinal Cord Injury in Lampreys. BIOMED RESEARCH INTERNATIONAL 2017; 2017:5953674. [PMID: 29333445 PMCID: PMC5733621 DOI: 10.1155/2017/5953674] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 10/25/2017] [Indexed: 12/15/2022]
Abstract
Spinal cord injury (SCI) is a devastating condition that leads to permanent disability because injured axons do not regenerate across the trauma zone to reconnect to their targets. A prerequisite for axonal regeneration will be the prevention of retrograde degeneration that could lead to neuronal death. However, the specific molecular mechanisms of axotomy-induced degeneration of spinal-projecting neurons have not been elucidated yet. In lampreys, SCI induces the apoptotic death of identifiable descending neurons that are “bad regenerators/poor survivors” after SCI. Here, we investigated the apoptotic process activated in identifiable descending neurons of lampreys after SCI. For this, we studied caspase activation by using fluorochrome-labeled inhibitors of caspases, the degeneration of spinal-projecting neurons using Fluro-Jade C staining, and the involvement of the intrinsic apoptotic pathway by means of cytochrome c and Vα double immunofluorescence. Our results provide evidence that, after SCI, bad-regenerating spinal cord-projecting neurons slowly degenerate and that the extrinsic pathway of apoptosis is involved in this process. Experiments using the microtubule stabilizer Taxol showed that caspase-8 signaling is retrogradely transported by microtubules from the site of axotomy to the neuronal soma. Preventing the activation of this process could be an important therapeutic approach after SCI in mammals.
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Jin Y, Yang S, Zhang X. Reduction of neuronal damage and promotion of locomotor recovery after spinal cord injury by early administration of methylprednisolone: possible involvement of autophagy pathway. RSC Adv 2017. [DOI: 10.1039/c6ra25794a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Interaction between autophagy and apoptosis participates in the neuroprotective effect of methylprednisolone on spinal cord injury.
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Affiliation(s)
- Yichao Jin
- Department of Neurosurgery
- Shanghai Renji Hospital
- Shanghai Jiaotong University
- School of Medicine
- Shanghai 200127
| | - Shaofeng Yang
- Department of Neurosurgery
- Shanghai Renji Hospital
- Shanghai Jiaotong University
- School of Medicine
- Shanghai 200127
| | - Xiaohua Zhang
- Department of Neurosurgery
- Shanghai Renji Hospital
- Shanghai Jiaotong University
- School of Medicine
- Shanghai 200127
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8
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Abstract
Several studies have shown that minocycline, a semisynthetic, second-generation tetracycline derivative, is neuroprotective in animal models of central nervous system trauma and several neurodegenerative diseases. Common to all these reports are the beneficial effects of minocycline in reducing neural inflammation and preventing cell death. Here, the authors review the proposed mechanisms of action of minocycline and suggest that minocycline may inhibit several aspects of the inflammatory response and prevent cell death through the inhibition of the p38 mitogen-activated protein kinase pathway, an important regulator of immune cell function and cell death.
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Affiliation(s)
- David P Stirling
- ICORD (International Collaboration On Repair Discoveries), University of British Columbia, Vancouver, BC, Canada
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9
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Metformin Improves Functional Recovery After Spinal Cord Injury via Autophagy Flux Stimulation. Mol Neurobiol 2016; 54:3327-3341. [PMID: 27167128 DOI: 10.1007/s12035-016-9895-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Accepted: 04/21/2016] [Indexed: 12/15/2022]
Abstract
Spinal cord injury (SCI) is a severe neurological disease with few efficacious drugs. Autophagy is a cellular process to confront with stress after SCI and considered to be a therapeutic target of SCI. In this study, we investigated the therapeutic effect of metformin on functional recovery after SCI and its underlying mechanism of autophagy regulation. Using a rat model of traumatic SCI, we found improved function recovery which was paralleled by a reduction of apoptosis after metformin treatment. We further examined autophagy via detecting autophagosomes by transmission electron microscopy and immunofluorescence, as well as autophagy markers by western blot in each groups. The results showed that the number of autophagosomes and expression of autophagy markers such as LC3 and beclin1 were increased in SCI group, while autophagy substrate protein p62 as well as ubiquitinated proteins were found to accumulate in SCI group, indicating an impaired autophagy flux in SCI. But, metformin treatment attenuated the accumulation of p62 and ubiquitinated proteins, suggesting a stimulative effect of autophagy flux by metformin. Blockage of autophagy flux by chloroquine partially abolished the apoptosis inhibition and functional recovery effect of metformin on SCI, which suggested that the protective effect of metformin on SCI was through autophagy flux stimulation. Activation of AMPK as well as inhibition of its downstream mTOR signaling were detected under metformin treatment in vivo and in vitro; inhibition of AMPK signaling by compound C suppressed autophagy flux induced by metformin in vitro, indicating that AMPK signaling was involved in the effect of metformin on autophagy flux regulation. Together, these results illustrated that metformin improved functional recovery effect through autophagy flux stimulation and implied metformin to be a potential drug for SCI therapy.
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Hu JG, Shi LL, Chen YJ, Xie XM, Zhang N, Zhu AY, Jiang ZS, Feng YF, Zhang C, Xi J, Lü HZ. Differential effects of myelin basic protein-activated Th1 and Th2 cells on the local immune microenvironment of injured spinal cord. Exp Neurol 2016; 277:190-201. [PMID: 26772636 DOI: 10.1016/j.expneurol.2016.01.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/01/2016] [Accepted: 01/04/2016] [Indexed: 01/22/2023]
Abstract
Myelin basic protein (MBP) activated T cells (MBP-T) play an important role in the damage and repair process of the central nervous system (CNS). However, whether these cells play a beneficial or detrimental role is still a matter of debate. Although some studies showed that MBP-T cells are mainly helper T (Th) cells, their subtypes are still not very clear. One possible explanation for MBP-T immunization leading to conflicting results may be the different subtypes of T cells are responsible for distinct effects. In this study, the Th1 and Th2 type MBP-T cells (MBP-Th1 and -Th2) were polarized in vitro, and their effects on the local immune microenvironment and tissue repair of spinal cord injury (SCI) after adoptive immunization were investigated. In MBP-Th1 cell transferred rats, the high levels of pro-inflammatory cells (Th1 cells and M1 macrophages) and cytokines (IFN-γ, TNF-α, -β, IL-1β) were detected in the injured spinal cord; however, the anti-inflammatory cells (Th2 cells, regulatory T cells, and M2 macrophages) and cytokines (IL-4, -10, and -13) were found in MBP-Th2 cell transferred animals. MBP-Th2 cell transfer resulted in decreased lesion volume, increased myelination of axons, and preservation of neurons. This was accompanied by significant locomotor improvement. These results indicate that MBP-Th2 adoptive transfer has beneficial effects on the injured spinal cord, in which the increased number of Th2 cells may alter the local microenvironment from one primarily populated by Th1 and M1 cells to another dominated by Th2, Treg, and M2 cells and is conducive for SCI repair.
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Affiliation(s)
- Jian-Guo Hu
- Clinical Laboratory, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China; Anhui Key Laboratory of Tissue Transplantation, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China
| | - Ling-Ling Shi
- Clinical Laboratory, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China; Department of Immunology, Bengbu Medical College, Anhui 233030, PR China
| | - Yue-Juan Chen
- Clinical Laboratory, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China; Anhui Key Laboratory of Tissue Transplantation, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China
| | - Xiu-Mei Xie
- Clinical Laboratory, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China; Anhui Key Laboratory of Tissue Transplantation, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China
| | - Nan Zhang
- Anhui Key Laboratory of Tissue Transplantation, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China
| | - An-You Zhu
- Clinical Laboratory, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China
| | - Zheng-Song Jiang
- Anhui Key Laboratory of Tissue Transplantation, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China; Department of Immunology, Bengbu Medical College, Anhui 233030, PR China
| | - Yi-Fan Feng
- Clinical Laboratory, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China; Anhui Key Laboratory of Tissue Transplantation, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China
| | - Chen Zhang
- Anhui Key Laboratory of Tissue Transplantation, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China
| | - Jin Xi
- Anhui Key Laboratory of Tissue Transplantation, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China
| | - He-Zuo Lü
- Clinical Laboratory, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China; Anhui Key Laboratory of Tissue Transplantation, The First Affiliated Hospital of Bengbu Medical College, Anhui 233004, PR China; Department of Immunology, Bengbu Medical College, Anhui 233030, PR China.
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11
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Chen YJ, Zhu H, Zhang N, Shen L, Wang R, Zhou JS, Hu JG, Lü HZ. Temporal kinetics of macrophage polarization in the injured rat spinal cord. J Neurosci Res 2015; 93:1526-33. [PMID: 26096572 DOI: 10.1002/jnr.23612] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 06/02/2015] [Accepted: 06/03/2015] [Indexed: 02/03/2023]
Affiliation(s)
- Yue-Juan Chen
- Central Laboratory; First Affiliated Hospital of Bengbu Medical College; Anhui People's Republic of China
- Anhui Key Laboratory of Tissue Transplantation; First Affiliated Hospital of Bengbu Medical College; Anhui People's Republic of China
| | - Hai Zhu
- Central Laboratory; First Affiliated Hospital of Bengbu Medical College; Anhui People's Republic of China
- Department of Immunology; Bengbu Medical College; Anhui People's Republic of China
- Anhui Key Laboratory of Infection and Immunity at Bengbu Medical College; Anhui People's Republic of China
| | - Nan Zhang
- Anhui Key Laboratory of Tissue Transplantation; First Affiliated Hospital of Bengbu Medical College; Anhui People's Republic of China
| | - Lin Shen
- Anhui Key Laboratory of Tissue Transplantation; First Affiliated Hospital of Bengbu Medical College; Anhui People's Republic of China
| | - Rui Wang
- Anhui Key Laboratory of Tissue Transplantation; First Affiliated Hospital of Bengbu Medical College; Anhui People's Republic of China
| | - Jian-Sheng Zhou
- Anhui Key Laboratory of Tissue Transplantation; First Affiliated Hospital of Bengbu Medical College; Anhui People's Republic of China
| | - Jian-Guo Hu
- Anhui Key Laboratory of Tissue Transplantation; First Affiliated Hospital of Bengbu Medical College; Anhui People's Republic of China
| | - He-Zuo Lü
- Central Laboratory; First Affiliated Hospital of Bengbu Medical College; Anhui People's Republic of China
- Anhui Key Laboratory of Tissue Transplantation; First Affiliated Hospital of Bengbu Medical College; Anhui People's Republic of China
- Department of Immunology; Bengbu Medical College; Anhui People's Republic of China
- Anhui Key Laboratory of Infection and Immunity at Bengbu Medical College; Anhui People's Republic of China
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Adoptive transfer of M2 macrophages promotes locomotor recovery in adult rats after spinal cord injury. Brain Behav Immun 2015; 45:157-70. [PMID: 25476600 DOI: 10.1016/j.bbi.2014.11.007] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 11/17/2014] [Accepted: 11/17/2014] [Indexed: 01/09/2023] Open
Abstract
Classically activated pro-inflammatory (M1) and alternatively activated anti-inflammatory (M2) macrophages populate the local microenvironment after spinal cord injury (SCI). The former type is neurotoxic while the latter has positive effects on neuroregeneration and is less toxic. In addition, while the M1 macrophage response is rapidly induced and sustained, M2 induction is transient. A promising strategy for the repair of SCI is to increase the fraction of M2 cells and prolong their residence time. This study investigated the effect of M2 macrophages induced from bone marrow-derived macrophages on the local microenvironment and their possible role in neuroprotection after SCI. M2 macrophages produced anti-inflammatory cytokines such as interleukin (IL)-10 and transforming growth factor β and infiltrated into the injured spinal cord, stimulated M2 and helper T (Th)2 cells, and produced high levels of IL-10 and -13 at the site of injury. M2 cell transfer decreased spinal cord lesion volume and resulted in increased myelination of axons and preservation of neurons. This was accompanied by significant locomotor improvement as revealed by Basso, Beattie and Bresnahan locomotor rating scale, grid walk and footprint analyses. These results indicate that M2 adoptive transfer has beneficial effects for the injured spinal cord, in which the increased number of M2 macrophages causes a shift in the immunological response from Th1- to Th2-dominated through the production of anti-inflammatory cytokines, which in turn induces the polarization of local microglia and/or macrophages to the M2 subtype, and creates a local microenvironment that is conducive to the rescue of residual myelin and neurons and preservation of neuronal function.
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13
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Barreiro-Iglesias A, Shifman MI. Detection of activated caspase-8 in injured spinal axons by using fluorochrome-labeled inhibitors of caspases (FLICA). Methods Mol Biol 2015; 1254:329-39. [PMID: 25431075 DOI: 10.1007/978-1-4939-2152-2_23] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Here, we present a detailed protocol for the detection of activated caspase-8 in axotomized axons of the whole-mounted lamprey spinal cord. This method is based on the use of fluorochrome -labeled inhibitors of caspases (FLICA) in ex vivo tissue. We offer a very convenient vertebrate model to study the retrograde degeneration of descending pathways after spinal cord injury.
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Affiliation(s)
- Antón Barreiro-Iglesias
- Centre for Neuroregeneration, School of Biomedical Sciences, University of Edinburgh, 49 Little France Crescent, Edinburgh, EH16 4SB, UK,
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Wang ZY, Lin JH, Muharram A, Liu WG. Beclin-1-mediated autophagy protects spinal cord neurons against mechanical injury-induced apoptosis. Apoptosis 2014; 19:933-45. [PMID: 24623173 DOI: 10.1007/s10495-014-0976-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Apoptosis has been widely reported to be involved in the pathogenesis associated with spinal cord injury (SCI). Recently, autophagy has also been implicated in various neuronal damage models. However, the role of autophagy in SCI is still controversial and its interrelationship with apoptosis remains unclear. Here, we used an in vitro SCI model to observe a time-dependent induction of autophagy and apoptosis. Mechanical injury induced autophagy markers such as LC3 lipidation, LC3II/LC3I conversion, and Beclin-1 expression. Injured neurons showed decreased cell viability and increased apoptosis. To elucidate the effect of autophagy on apoptosis, the mechanically-injured neurons were treated with the mTOR inhibitor rapamycin and 3-methyl adenine (3-MA), which are known to regulate autophagy positively and negatively, respectively. Rapamycin-treated neurons showed the highest level of cell viability and lowest level of apoptosis among the injured neurons and those treated with 3-MA showed the reciprocal effect. Notably, rapamycin-treated neurons exhibited slightly reduced Bax expression and significantly increased Bcl-2 expression. Furthermore, by plasmid transfection, we showed that Beclin-1-overexpressing neuronal cells responded to mechanical injury with greater LC3II/LC3I conversion and cell viability, lower levels of apoptosis, higher Bcl-2 expression, and unaltered Bax expression as compared to vector control cells. Beclin-1-knockdown neurons showed almost the opposite effects. Taken together, our results suggest that autophagy may serve as a protection against apoptosis in mechanically-injured spinal cord neurons. Targeting mTOR and/or enhancing Beclin-1 expression might be alternative therapeutic strategies for SCI.
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Affiliation(s)
- Zhen-Yu Wang
- Department of Orthopedics, Affiliated Union Hospital of Fujian Medical University, Fuzhou, 086-350001, China
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15
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Wu KLH, Chan SHH, Chan JYH. Neuroinflammation and oxidative stress in rostral ventrolateral medulla contribute to neurogenic hypertension induced by systemic inflammation. J Neuroinflammation 2012; 9:212. [PMID: 22958438 PMCID: PMC3462714 DOI: 10.1186/1742-2094-9-212] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Accepted: 08/27/2012] [Indexed: 02/07/2023] Open
Abstract
Background In addition to systemic inflammation, neuroinflammation in the brain, which enhances sympathetic drive, plays a significant role in cardiovascular diseases, including hypertension. Oxidative stress in rostral ventrolateral medulla (RVLM) that augments sympathetic outflow to blood vessels is involved in neural mechanism of hypertension. We investigated whether neuroinflammation and oxidative stress in RVLM contribute to hypertension following chronic systemic inflammation. Methods In normotensive Sprague-Dawley rats, systemic inflammation was induced by infusion of Escherichia coli lipopolysaccharide (LPS) into the peritoneal cavity via an osmotic minipump. Systemic arterial pressure and heart rate were measured under conscious conditions by the non-invasive tail-cuff method. The level of the inflammatory markers in plasma or RVLM was analyzed by ELISA. Protein expression was evaluated by Western blot or immunohistochemistry. Tissue level of superoxide anion (O2·-) in RVLM was determined using the oxidation-sensitive fluorescent probe dihydroethidium. Pharmacological agents were delivered either via infusion into the cisterna magna with an osmotic minipump or microinjection bilaterally into RVLM. Results Intraperitoneal infusion of LPS (1.2 mg/kg/day) for 14 days promoted sustained hypertension and induced a significant increase in plasma level of C-reactive protein, tumor necrosis factor-α (TNF-α), or interleukin-1β (IL-1β). This LPS-induced systemic inflammation was accompanied by activation of microglia, augmentation of IL-1β, IL-6, or TNF-α protein expression, and O2·- production in RVLM, all of which were blunted by intracisternal infusion of a cycloxygenase-2 (COX-2) inhibitor, NS398; an inhibitor of microglial activation, minocycline; or a cytokine synthesis inhibitor, pentoxifylline. Neuroinflammation in RVLM was also associated with a COX-2-dependent downregulation of endothelial nitric oxide synthase and an upregulation of intercellular adhesion molecule-1. Finally, the LPS-promoted long-term pressor response and the reduction in expression of voltage-gated potassium channel, Kv4.3 in RVLM were antagonized by minocycline, NS398, pentoxifylline, or a superoxide dismutase mimetic, tempol, either infused into cisterna magna or microinjected bilaterally into RVLM. The same treatments, on the other hand, were ineffective against LPS-induced systemic inflammation. Conclusion These results suggest that systemic inflammation activates microglia in RVLM to induce COX-2-dependent neuroinflammation that leads to an increase in O2·- production. The resultant oxidative stress in RVLM in turn mediates neurogenic hypertension.
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Affiliation(s)
- Kay L H Wu
- Center for Translational Research in Biomedical Sciences, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung, 83301, Taiwan
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16
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Hu JG, Shen L, Wang R, Wang QY, Zhang C, Xi J, Ma SF, Zhou JS, Lü HZ. Effects of Olig2-overexpressing neural stem cells and myelin basic protein-activated T cells on recovery from spinal cord injury. Neurotherapeutics 2012; 9:422-45. [PMID: 22173726 PMCID: PMC3337015 DOI: 10.1007/s13311-011-0090-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
Abstract
Neural stem cell (NSC) transplantation is a major focus of current research for treatment of spinal cord injury (SCI). However, it is very important to promote the survival and differentiation of NSCs into myelinating oligodendrocytes (OLs). In this study, myelin basic protein-activated T (MBP-T) cells were passively immunized to improve the SCI microenvironment. Olig2-overexpressing NSCs were infected with a lentivirus carrying the enhanced green fluorescent protein (GFP) reporter gene to generate Olig2-GFP-NSCs that were transplanted into the injured site to differentiate into OLs. Transferred MBP-T cells infiltrated the injured spinal cord, produced neurotrophic factors, and induced the differentiation of resident microglia and/or infiltrating blood monocytes into an "alternatively activated" anti-inflammatory macrophage phenotype by producing interleukin-13. As a result, the survival of transplanted NSCs increased fivefold in MBP-T cell-transferred rats compared with that of the vehicle-treated control. In addition, the differentiation of MBP-positive OLs increased 12-fold in Olig2-GFP-NSC-transplanted rats compared with that of GFP-NSC-transplanted controls. In the MBP-T cell and Olig2-GFP-NSC combined group, the number of OL-remyelinated axons significantly increased compared with those of all other groups. However, a significant decrease in spinal cord lesion volume and an increase in spared myelin and behavioral recovery were observed in Olig2-NSC- and NSC-transplanted MBP-T cell groups. Collectively, these results suggest that MBP-T cell adoptive immunotherapy combined with NSC transplantation has a synergistic effect on histological and behavioral improvement after traumatic SCI. Although Olig2 overexpression enhances OL differentiation and myelination, the effect on functional recovery may be surpassed by MBP-T cells.
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Affiliation(s)
- Jian-Guo Hu
- />Central Laboratory, First Affiliated Hospital of Bengbu Medical College, Anhui, 233004 People’s Republic of China
- />Anhui Key Laboratory of Tissue Transplantation, Bengbu Medical College, Anhui, 233004 People’s Republic of China
| | - Lin Shen
- />Anhui Key Laboratory of Tissue Transplantation, Bengbu Medical College, Anhui, 233004 People’s Republic of China
| | - Rui Wang
- />Anhui Key Laboratory of Tissue Transplantation, Bengbu Medical College, Anhui, 233004 People’s Republic of China
| | - Qi-Yi Wang
- />Anhui Key Laboratory of Tissue Transplantation, Bengbu Medical College, Anhui, 233004 People’s Republic of China
| | - Chen Zhang
- />Anhui Key Laboratory of Tissue Transplantation, Bengbu Medical College, Anhui, 233004 People’s Republic of China
| | - Jin Xi
- />Anhui Key Laboratory of Tissue Transplantation, Bengbu Medical College, Anhui, 233004 People’s Republic of China
| | - Shan-Feng Ma
- />Anhui Key Laboratory of Tissue Transplantation, Bengbu Medical College, Anhui, 233004 People’s Republic of China
| | - Jian-Sheng Zhou
- />Anhui Key Laboratory of Tissue Transplantation, Bengbu Medical College, Anhui, 233004 People’s Republic of China
| | - He-Zuo Lü
- />Central Laboratory, First Affiliated Hospital of Bengbu Medical College, Anhui, 233004 People’s Republic of China
- />Anhui Key Laboratory of Tissue Transplantation, Bengbu Medical College, Anhui, 233004 People’s Republic of China
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Kang J, Jiang MH, Min HJ, Jo EK, Lee S, Karin M, Yune TY, Lee SJ. IKK-β-mediated myeloid cell activation exacerbates inflammation and inhibits recovery after spinal cord injury. Eur J Immunol 2011; 41:1266-77. [DOI: 10.1002/eji.201040582] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 12/19/2010] [Accepted: 02/10/2011] [Indexed: 11/10/2022]
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Yan X, Liu J, Luo Z, Ding Q, Mao X, Yan M, Yang S, Hu X, Huang J, Luo Z. Proteomic profiling of proteins in rat spinal cord induced by contusion injury. Neurochem Int 2010; 56:971-83. [PMID: 20399821 DOI: 10.1016/j.neuint.2010.04.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2009] [Revised: 03/28/2010] [Accepted: 04/09/2010] [Indexed: 01/05/2023]
Abstract
It is widely accepted that mechanical injury to spinal cord can cause nervous system dysfunction, which leads to the loss of movement and sensation. However, the exact molecular mechanism is currently unclear. In this study, contused rat spinal cords were collected at 8h, 1 day, 3, and 5 days after injury and the expression patterns of the proteins were monitored and quantified with two-dimensional gel electrophoresis-based proteomics. Fifty-one protein spots showed significant regulation at least at one time point. Of the 39 proteins, identified by mass spectrometry analysis and clustered into three down-regulation profiles and two up-regulation profiles, eight contusion-related proteins have been reported in previous proteomic studies of spinal cord whereas 31 proteins were described for the first time. For example, apoptosis-related protein of heat shock 70 kDa protein 1B increased after contusion, reaching the peak at 1 day; septin 7, a protein involved in cytoskeleton organization, maintained a steady increase for the first 5 days after injury; metabolism-related protein of 3-hydroxy-3-methylglutaryl-Coenzyme A synthase 1 was constantly down-regulated during the whole time course observed; tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, epsilon polypeptide, associated with cell cycle progression, showed a gradual increase after contusion. To our knowledge, this is the first case of detailed and dynamic proteomic snapshots of contusion-induced spinal cord injury. Most of the identified proteins were found for the first time to be differentially expressed after spinal cord contusion, which may help explore the complex molecular cascades underlying the progressive pathologic changes in the contused spinal cord.
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Affiliation(s)
- Xiaodong Yan
- Institute of Orthopaedics, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
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19
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Neuroprotective effects of caspase-3 inhibition on functional recovery and tissue sparing after acute spinal cord injury. Spine (Phila Pa 1976) 2008; 33:2269-77. [PMID: 18827691 DOI: 10.1097/brs.0b013e3181831f7e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN We used gene microarrays and found that caspase-related death genes were upregulated. We tested caspase inhibition and evaluated its effect on the spinal cord after traumatic injury. OBJECTIVE The logical extension of previous studies was to determine whether downstream CASP genes might also be involved and whether inhibition might prevent injury-induced cell death. SUMMARY OF BACKGROUND DATA Apoptotic cell death occurs in all endogenous cellular compartments of the spinal cord, peaking at 3 days after injury in neurons, astrocytes, and microglia. The downstream effector caspase-3 cleaves several important cellular sites after being activated by upstream initiator caspases. Along with others, we have previously identified caspase signature cleavage of PARP, alpha-fodrin, and DFF45/ICAD in the injured rat spinal cord. We also showed rapid upregulation of caspase-3 gene expression along with localization of active caspase-3 in neurons and activated microglia after SCI. Others have reported that a more general active-site mimetic peptide ketone, benzylocarbonyl-Val-Ala-Asp-fluromethylketone (zVAD-fmk) was neuroprotective after rat spinal cord injury (SCI). METHODS In this study, we administered the caspase-3 subfamily tetrapeptide cell permeable inhibitor Z-Asp(O-Me)-Glu(O-Me)-Val-Asp(O-Me) fluoromethyl ketone (DEVD-fmk) intraperitoneally 1 hour after laminectomy and moderate (25 g cm force) SCI in rats. RESULTS.: We used the open field locomotor rating (LRS) over a 14-day course and found statistically significant improvement in DEVD-fmk-treated rats, LRS, 9.8 +/- 0.93 SEM, compared with vehicle, 6.6 +/- 0.4 (P < 0.05). Histologic analysis of percent spinal cord tissue volume spared was 50% greater for DEVD-fmk versus control (P < 0.5). CONCLUSION These results indicate neuroprotection at both the cellular level and with substantial functional recovery, suggesting caspase-3 inhibition may be a viable therapy in the early hours after experimental SCI.
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20
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Jang H, Boltz DA, Webster RG, Smeyne RJ. Viral parkinsonism. Biochim Biophys Acta Mol Basis Dis 2008; 1792:714-21. [PMID: 18760350 DOI: 10.1016/j.bbadis.2008.08.001] [Citation(s) in RCA: 215] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Revised: 08/04/2008] [Accepted: 08/05/2008] [Indexed: 12/30/2022]
Abstract
Parkinson's disease is a debilitating neurological disorder that affects 1-2% of the adult population over 55 years of age. For the vast majority of cases, the etiology of this disorder is unknown, although it is generally accepted that there is a genetic susceptibility to any number of environmental agents. One such agent may be viruses. It has been shown that numerous viruses can enter the nervous system, i.e. they are neurotropic, and induce a number of encephalopathies. One of the secondary consequences of these encephalopathies can be parkinsonism, that is both transient as well as permanent. One of the most highlighted and controversial cases of viral parkinsonism is that which followed the 1918 influenza outbreak and the subsequent induction of von Economo's encephalopathy. In this review, we discuss the neurological sequelae of infection by influenza virus as well as that of other viruses known to induce parkinsonism including Coxsackie, Japanese encephalitis B, St. Louis, West Nile and HIV viruses.
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Affiliation(s)
- Haeman Jang
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, USA
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21
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Di Loreto S, Zimmitti V, Sebastiani P, Cervelli C, Falone S, Amicarelli F. Methylglyoxal causes strong weakening of detoxifying capacity and apoptotic cell death in rat hippocampal neurons. Int J Biochem Cell Biol 2007; 40:245-57. [PMID: 17869161 DOI: 10.1016/j.biocel.2007.07.019] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 07/24/2007] [Accepted: 07/25/2007] [Indexed: 01/10/2023]
Abstract
The hippocampus is known to play a crucial role in learning and memory. Recent data from literature show that cognitive problems, common to aged or diabetic patients, may be related to accumulation of toxic alpha-oxoaldehydes such as methylglyoxal. Thus, it is possible that methylglyoxal could be, at least in part, responsible for the impairment of cognitive functions, and the knowledge of the mechanisms through which this compound elicits neuronal toxicity could be useful for the development of possible therapeutic strategies. We previously reported a high susceptibility of hippocampal neurons to methylglyoxal, through an oxidation-dependent mechanism. In the present study, we extend our investigation on the molecular mechanisms which underlie methylglyoxal toxicity, focusing on possible effects on expression and activity of glyoxalases, its main detoxifying enzymes, and glutathione peroxidase, as well as on the levels of reduced glutathione. We also investigate methylglyoxal-induced modulation of brain derived neurotrophic factor and proinflammatory cytokines. Our results show that methylglyoxal causes a dramatic depletion of reduced glutathione and a significant inhibition of both glyoxalase and glutathione peroxidase activities. Furthermore, methylglyoxal treatment seems to affect the expression of inflammatory cytokines and survival factors. In conclusion, our findings suggest that methylglyoxal-induced neurotoxicity occurs through the impairment of detoxification pathway and depletion of reduced glutathione. This, in turn, triggers widespread apoptotic cell death, occurring through the convergence of both mitochondrial and Fas-receptor pathways.
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Affiliation(s)
- Silvia Di Loreto
- Institute for Organ Transplantation and Immunocytology (ITOI), CNR, P. le Collemaggio, 67100 L'Aquila, Italy.
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22
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Dey S, Snow DM. Cocaine exposure in vitro induces apoptosis in fetal locus coeruleus neurons through TNF-alpha-mediated induction of Bax and phosphorylated c-Jun NH(2)-terminal kinase. J Neurochem 2007; 103:542-56. [PMID: 17635674 DOI: 10.1111/j.1471-4159.2007.04750.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cocaine exposure results in aberrant outgrowth and decreased survival for locus coeruleus (LC), a noradrenergic population of neurons that putatively regulates attentional function; however, the underlying mechanisms for these events are not known. We previously showed that cocaine exposure in vitro activates pro-apoptotic Bax, caspase-9, and caspase-3 in LC neurons dissected from embryonic day 14 rats, implicating that apoptosis may be orchestrated via signal transduction events. In the current study in vitro, we examined upstream events to determine the role of the pro-inflammatory cytokine, tumor necrosis factor alpha (TNF-alpha), on LC signal transduction, because cocaine exposure to LC neurons triggered TNF-alpha expression at 30 min as measured by ELISA. Exposure of LC neurons to recombinant-TNF-alpha resulted in decreased metabolic activity, an indicator of reduced neuron viability [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay], and increased apoptosis (terminal deoxynucleotidyl transferase-mediated DNA nick end labeling assay). Pro-apoptotic caspase-3 was induced by cocaine starting at 30 min. Recombinant-TNF-alpha induced caspase-3 activity earlier than cocaine (15 and 20 min). The caspase-3 levels were significantly reduced when cocaine and TNF-alpha were combined with neutralizing-TNF-alpha (nTNF-alpha), respectively. Further, cocaine alone elevated phospho-p38-mitogen-activated protein kinases that persisted when combined with nTNF-alpha. However, both cocaine and TNF-alpha independently increased phospho-c-Jun NH(2)-terminal kinase and Bax levels at concurrent time periods (30 min and 1 h), and this elevation was attenuated in the presence of nTNF-alpha. These simultaneous molecular events triggered by cocaine and TNF-alpha implicate a potential apoptotic signal transduction pathway via induction of phospho-c-Jun NH(2)-terminal kinase and Bax that may lead to caspase-3 activation and apoptosis in cocaine-exposed fetal LC neurons.
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Affiliation(s)
- Swatee Dey
- Graduate Center for Toxicology, University of Kentucky, Lexington, Kentucky 40536, USA.
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23
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Cittelly DM, Perez-Polo JR. Antiapoptotic therapies in the treatment of spinal cord injury. FUTURE NEUROLOGY 2007. [DOI: 10.2217/14796708.2.4.425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mechanical trauma to the spinal cord triggers events resulting in the death of neurons and glia over several weeks following the initial injury. It has been suggested that the prevention of delayed apoptosis after spinal cord injury (SCI) is likely to have a beneficial effect by reducing the extent of neuronal and oligodendroglial death, which would translate into better functional outcomes. Drugs acting at different levels in the apoptotic cascade (i.e., caspase inhibitors and antiapoptotic Bcl-xL) have been shown to decrease apoptotic cell death, but benefits in functional outcomes result only when inflammation is also decreased. Furthermore, long-term antiapoptotic therapy can result in nonapoptotic death with necrotic features, which will further increase inflammation and worsen outcome. Even though neuroprotective therapies are one of the targets for the promotion of functional recovery after SCI, targeting only post-SCI apoptosis is unlikely to be as successful as more integrated interventions that also target inflammation.
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Affiliation(s)
- Diana M Cittelly
- Department of Biochemistry, 1430 Tulane Ave, SL43, New Orleans, LA 70112, USA
| | - J Regino Perez-Polo
- University of Texas, Medical Branch at Galveston 301 University Boulevard, Department of Biochemistry & Molecular Biology, Galveston, TX 77555–1072, USA
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24
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Chuang YC, Chen SD, Lin TK, Liou CW, Chang WN, Chan SHH, Chang AYW. Upregulation of nitric oxide synthase II contributes to apoptotic cell death in the hippocampal CA3 subfield via a cytochrome c/caspase-3 signaling cascade following induction of experimental temporal lobe status epilepticus in the rat. Neuropharmacology 2007; 52:1263-73. [PMID: 17336342 DOI: 10.1016/j.neuropharm.2007.01.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Revised: 01/10/2007] [Accepted: 01/15/2007] [Indexed: 11/24/2022]
Abstract
Status epilepticus results in preferential neuronal cell loss in the hippocampus. We evaluated the hypothesis that the repertoire of intracellular events in the vulnerable hippocampal CA3 subfield after induction of experimental temporal lobe status epilepticus entails upregulation of nitric oxide synthase II (NOS II), followed by the release of mitochondrial cytochrome c that triggers the cytosolic caspase-3 cascade, leading to apoptotic cell death. In Sprague-Dawley rats, significant and temporally correlated upregulation of NOS II (3-24h), but not NOS I or II expression, enhanced cytosolic translocation of cytochrome c (days 1 and 3), augmented activated caspase-3 in cytosol (days 1, 3 and 7) and DNA fragmentation (days 1, 3 and 7) was detected bilaterally in the hippocampal CA3 subfield after elicitation of sustained seizure activity by microinjection of kainic acid into the unilateral CA3 subfield. Application bilaterally into the hippocampal CA3 subfield of a selective NOS II inhibitor, S-methylisothiourea, significantly blunted these apoptotic events; a selective NOS I inhibitor, N(omega)-propyl-l-arginine or a potent NOS III inhibitor, N(5)-(1-iminoethyl)-l-ornithine was ineffective. We conclude that upregulation of NOS II contributes to apoptotic cell death in the hippocampal CA3 subfield via a cytochrome c/caspase-3 signaling cascade following the induction of experimental temporal lobe status epilepticus.
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Affiliation(s)
- Y C Chuang
- Department of Neurology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung 833, Taiwan, ROC
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Wu KLH, Hsu C, Chan JYH. Impairment of the mitochondrial respiratory enzyme activity triggers sequential activation of apoptosis-inducing factor-dependent and caspase-dependent signaling pathways to induce apoptosis after spinal cord injury. J Neurochem 2007; 101:1552-66. [PMID: 17298387 DOI: 10.1111/j.1471-4159.2006.04445.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The mitochondrion participates in caspase-independent or caspase-dependent apoptotic pathways through the release of apoptosis-inducing factor or cytochrome c. Whether both mitochondrial apoptotic cascades are triggered in the injured spinal cord remains unknown. Here, we demonstrated that neurons, astrocytes and microglia in spinal segments proximal to a complete spinal cord transection underwent two phases of apoptotic cell death. The early phase of high-molecular weight (HMW) DNA fragmentation was associated with nuclear translocation of apoptosis-inducing factor, reduction in mitochondrial respiratory chain enzyme activity and decrease in cellular ATP concentration. The delayed phase of low-molecular weight (LMW) DNA fragmentation was accompanied by cytosolic release of cytochrome c, activation of caspases 9 and 3, and resumption of mitochondrial respiratory functions and ATP contents. Microinfusion of coenzyme Q(10), an electron carrier in mitochondrial respiratory chain, into the epicenter of the transected spinal cord attenuated both phases of induced apoptosis, and reversed the elicited mitochondrial dysfunction, bioenergetic failure, and activation of apoptosis-inducing factor, cytochrome c, or caspases 9 and 3. We conclude that mitochondrial dysfunction after spinal cord transection represents the initiating cellular events that trigger the sequential activation of apoptosis-inducing factor-dependent and caspase-dependent signaling cascades, leading to apoptotic cell death in the injured spinal cord.
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Affiliation(s)
- Kay L H Wu
- Graduate Institute of Medicine, Kaohsiung Medical University, and Department of Medical Edcuation and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
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Chan JYH, Cheng HL, Chou JLJ, Li FCH, Dai KY, Chan SHH, Chang AYW. Heat Shock Protein 60 or 70 Activates Nitric-oxide Synthase (NOS) I- and Inhibits NOS II-associated Signaling and Depresses the Mitochondrial Apoptotic Cascade during Brain Stem Death. J Biol Chem 2007; 282:4585-4600. [PMID: 17150954 DOI: 10.1074/jbc.m603394200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The cellular and molecular basis of brain stem death remains an enigma. As the origin of a "life-and-death" signal that reflects the progression toward brain stem death, the rostral ventrolateral medulla (RVLM) is a suitable neural substrate for mechanistic delineation of this phenomenon. Here, we evaluated the hypothesis that heat shock proteins (HSPs) play a neuroprotective role in the RVLM during brain stem death and delineated the underlying mechanisms, using a clinically relevant animal model that employed the organophosphate pesticide mevinphos (Mev) as the experimental insult. In Sprague-Dawley rats, proteomic, Western blot, and real-time PCR analyses demonstrated that Mev induced de novo synthesis of HSP60 or HSP70 in the RVLM without affecting HSP90 level. Loss-of-function manipulations of HSP60 or HSP70 in the RVLM using anti-serum or antisense oligonucleotide potentiated Mev-elicited cardiovascular depression alongside reduced nitric-oxide synthase (NOS) I/protein kinase G signaling, enhanced NOS II/peroxynitrite cascade, intensified nucleosomal DNA fragmentation, elevated cytoplasmic histone-associated DNA fragments or activated caspase-3, and augmented the cytochrome c/caspase-3 cascade of apoptotic signaling in the RVLM. Co-immunoprecipitation experiments further revealed a progressive increase in the complex formed between HSP60 and mitochondrial or cytosolic Bax or mitochondrial Bcl-2 during Mev intoxication, alongside a dissociation of the cytosolic HSP60-Bcl-2 complex. We conclude that HSP60 and HSP70 confer neuroprotection against Mev intoxication by ameliorating cardiovascular depression via an anti-apoptotic action in the RVLM. The possible underlying intracellular processes include enhancing NOS I/protein kinase G signaling and inhibiting the NOS II/peroxynitrite cascade. In addition, HSP60 exerts its effects against apoptosis by blunting Mev-induced activation of the Bax/cytochrome c/caspase-3 cascade.
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Affiliation(s)
- Julie Y H Chan
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 81346
| | - Hsiao-Lei Cheng
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung 80424, and the
| | - Jimmy L J Chou
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung 80424, and the
| | - Faith C H Li
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung 80424, and the
| | - Kuang-Yu Dai
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung 80424, and the
| | - Samuel H H Chan
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung 80424, and the; Center for Gene Regulation and Signal Transduction Research, National Cheng Kung University, Tainan 70101, Taiwan
| | - Alice Y W Chang
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung 80424, and the; Center for Gene Regulation and Signal Transduction Research, National Cheng Kung University, Tainan 70101, Taiwan.
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Chan JYH, Chang AYW, Wang LL, Ou CC, Chan SHH. Protein kinase C-dependent mitochondrial translocation of proapoptotic protein Bax on activation of inducible nitric-oxide synthase in rostral ventrolateral medulla mediates cardiovascular depression during experimental endotoxemia. Mol Pharmacol 2007; 71:1129-39. [PMID: 17227955 DOI: 10.1124/mol.106.031161] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sympathetic premotor neurons for the maintenance of vasomotor tone are located in rostral ventrolateral medulla (RVLM). We demonstrated previously that overproduction of nitric oxide (NO) by inducible NO synthase (iNOS) in RVLM, leading to caspase 3-dependent apoptotic cell death, plays a pivotal role in cardiovascular depression during endotoxemia induced by intravenous administration of Escherichia coli lipopolysaccharide. The interposing intracellular events remain unknown. We evaluated the hypothesis that these events encompass protein kinase C (PKC) activation, which triggers activation and translocation of Bax that opens mitochondrial permeability transition pore by interacting with adenine nucleotide translocase (ANT) or voltage-dependent anion protein (VDAC), followed by cytosolic release of cytochrome c. In Sprague-Dawley rats, coimmunoprecipitation and Western blot analyses revealed sequential manifestations during endotoxemia of membrane-bound translocation of PKC, dissociation of cytosolic PKC/Bax complex, mitochondrial translocation of activated Bax, augmented Bax/ANT or Bax/VDAC association, elevated cytosolic cytochrome c and caspase 3, and DNA fragmentation in ventrolateral medulla. Microinjection of iNOS inhibitor into bilateral RVLM significantly retarded PKC and Bax activation. The induced association of translocated Bax with ANT or VDAC and the triggered mitochondrial apoptotic signaling cascade were blunted by blockade in RVLM of PKC, mitochondrial translocation of Bax, Bax channels, ANT, or caspase 3, alongside significant amelioration of cardiovascular depression. We conclude that formation of mitochondrial Bax/ANT or Bax/VDAC complex that initiates caspase 3-dependent apoptosis in the RVLM as a result of PKC-dependent mitochondrial translocation of activated Bax activated by iNOS-derived NO plays a pivotal role in the manifestation of endotoxin-induced cardiovascular depression.
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Affiliation(s)
- Julie Y H Chan
- Department of Medical Education & Research, Kaohsiung Veterans General Hospital, Taiwan, Republic of China
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Pusterla N, Wilson WD, Conrad PA, Mapes S, Leutenegger CM. Comparative analysis of cytokine gene expression in cerebrospinal fluid of horses without neurologic signs or with selected neurologic disorders. Am J Vet Res 2006; 67:1433-7. [PMID: 16881858 DOI: 10.2460/ajvr.67.8.1433] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine gene transcription for cytokines in nucleated cells in CSF of horses without neurologic signs or with cervical stenotic myelopathy (CSM), West Nile virus (WNV) encephalitis, equine protozoal myeloencephalitis (EPM), or spinal cord trauma. ANIMALS 41 horses (no neurologic signs [n = 12], CSM [8], WNV encephalitis [9], EPM [6], and spinal cord trauma [6]). PROCEDURES Total RNA was extracted from nucleated cells and converted into cDNA. Gene expression was measured by use of real-time PCR assay and final quantitation via the comparative threshold cycle method. RESULTS Cytokine genes expressed by nucleated cells of horses without neurologic signs comprised a balance between proinflammatory tumor necrosis factor-alpha (TNF-alpha), anti-inflammatory cytokines (interleukin [IL]-10 and transforming growth factor [TGF]-beta), and Th1 mediators (interferon [IFN]-gamma). Cells of horses with CSM mainly expressed genes for TNF-alpha, TGF-beta, and IL-10. Cells of horses with WNV encephalitis mainly expressed genes for IL-6 and TGF-beta. Cells of horses with EPM mainly had expression of genes for IL-6, IL-8, IL-10, TNF-alpha, IFN-gamma, and TGF-beta. Cells from horses with spinal cord trauma had expression mainly for IL-6; IFN-gamma; TGF-beta; and less frequently, IL-2, IL-10, and TNF-alpha. Interleukin-8 gene expression was only detected in CSF of horses with infectious diseases. CONCLUSIONS AND CLINICAL RELEVANCE Despite the small number of CSF samples for each group, results suggest distinct gene signatures expressed by nucleated cells in the CSF of horses without neurologic signs versus horses with inflammatory or traumatic neurologic disorders.
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Affiliation(s)
- Nicola Pusterla
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, 95616, USA
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Ahn YH, Lee G, Kang SK. Molecular insights of the injured lesions of rat spinal cords: Inflammation, apoptosis, and cell survival. Biochem Biophys Res Commun 2006; 348:560-70. [PMID: 16890196 DOI: 10.1016/j.bbrc.2006.07.105] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Accepted: 07/17/2006] [Indexed: 12/20/2022]
Abstract
Spinal cord injury (SCI) is a devastating neurologic injury with functional deficits. In the acute phase, which starts at the moment of the injury and extends over the first few days, numerous pathological processes begin. In this study, we made several additional advances to broaden our understanding of SCI-induced gene expression changes. We examined changes at multiple time points: 0, 6, 24, 48, and 72 h after injury, with the latter time period being added. Also, we utilized multiple analysis methods such as real-time RT-PCR, Western blot, and immunohistochemistry to increase confidence in our candidate gene and molecular processes. From the pool of information, we generated profiles of expression changes and molecular mechanisms of several injury processing. Early stages after the injury are characterized by the strong upregulation of genes involved in transcription, inflammation, and signaling proteins, and a general downregulation of neural function-related genes. In addition, edema of the spinal cord develops, and metabolic disturbances involving intra-neuronal Ca2+ accumulation occur. This translates into a general failure of normal neural functions and a stage of signal shock that lasts for a few days in experimental rat models. Traumatic injury to the spinal cord also leads to a strong inflammatory response with the recruitment of peripherally derived immature cells, such as ED1-positive macrophages. After the trauma, apoptotic cell death continues, and scarring and demyelination accompany Wallerian degeneration. Strong expression of transcription factors of the Janus-activated kinase (JAK) and signal transducer and activator of transcription (STAT) family represents an early attempt of spinal cord repair and regeneration. Our study allowed us to conclude that combined therapeutic strategies for enhanced recovery should be performed until the chronic phase of the injury in areas distal to the lesion epicenter of spinal cords.
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Affiliation(s)
- Young Hwan Ahn
- Department of Physiology, College of Medicine, Pusan National University, Busan, Republic of Korea
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Chang AYW, Chan JYH, Chou JLJ, Li FCH, Dai KY, Chan SHH. Heat shock protein 60 in rostral ventrolateral medulla reduces cardiovascular fatality during endotoxaemia in the rat. J Physiol 2006; 574:547-64. [PMID: 16675490 PMCID: PMC1817760 DOI: 10.1113/jphysiol.2006.110890] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 04/03/2006] [Accepted: 04/28/2006] [Indexed: 01/02/2023] Open
Abstract
The rostral ventrolateral medulla (RVLM) is the origin of a 'life-and-death' signal that reflects central cardiovascular regulatory failure during brain stem death. Using an experimental endotoxaemia model, we evaluated the hypothesis that the 60 kDa heat shock protein 60 (HSP60) reduces cardiovascular fatality during brain stem death via an anti-apoptotic action in the RVLM. In Sprague-Dawley rats maintained under propofol anaesthesia, proteomic or Western blot analysis revealed a progressive augmentation of HSP60 expression in the RVLM after intravenous administration of Escherichia coli lipopolysaccharide (30 mg kg(-1)). Pretreatment with a microinjection of actinomycin D or cycloheximide into bilateral RVLM significantly blunted this HSP60 increase, whereas real-time PCR showed progressive augmentation of hsp60 mRNA. Intriguingly, superimposed on the augmented expression was a progressive decline in mitochondrial, or elevation in cytosolic, HSP60 in ventrolateral medulla. Loss-of-function manipulations in the RVLM using anti-HSP60 antiserum or antisense hsp60 oligonucleotide exacerbated mortality by potentiating the cardiovascular depression during experimental endotoxaemia, alongside intensified nucleosomal DNA fragmentation, elevated cytoplasmic histone-associated DNA fragments or augmented cytochromec-caspase-3 cascade of apoptotic signalling in the RVLM. Immunoprecipitation coupled with immunoblot analysis further revealed a progressive increase in the complex formed between HSP60 and mitochondrial or cytosolic Bax or mitochondrial Bcl-2 during endotoxaemia, alongside a dissociation of the cytosolic HSP60-Bcl-2 complex. We conclude that HSP60 redistributed from mitochondrion to cytosol in the RVLM confers neuroprotection against fatal cardiovascular depression during endotoxaemia via reduced activation of the cytochrome c-caspase-3 cascade of apoptotic signalling through enhanced interactions with mitochondrial or cytosolic Bax or Bcl-2.
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Affiliation(s)
- Alice Y W Chang
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung 80424, Taiwan, Republic of China
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Ubol S, Kasisith J, Pitidhammabhorn D, Tepsumethanol V. Screening of pro-apoptotic genes upregulated in an experimental street rabies virus-infected neonatal mouse brain. Microbiol Immunol 2005; 49:423-31. [PMID: 15905604 DOI: 10.1111/j.1348-0421.2005.tb03746.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Rabies virus (RABV) is able to induce apoptotic death of target cells. The molecular pathway of RABV-induced cell death is partially known. In the present study, cDNA array analysis was used as a tool to screen for pro-apoptotic genes that may be involved in RABV induction. RNA was extracted from the infected CNS and from mock-infected controls. When the mean gene expression was compared between the infected group and controls, 21 potential apoptotic genes were identified that exhibited more than 2.5-fold difference in their expression levels. These 21 genes can be grouped into two groups, those genes that participate in the commitment phase and those that play a role as executioners. Examples of genes in commitment phase were death receptors (Fas-L receptor, TNF-receptor), lysosomal proteases, calpain, caspase-1, signaling molecules (ERK, p38MAPK) and bcl-2 family members. Cytochrome c and caspase-3 were representatives of executioners. Based on types of genes activated during the commitment phase, two independent apoptotic mechanisms may be activated in response to the RV infection. The first is immune-mediated death which may operate through the receptor-ligand pathway activated by caspase-1 and the pro-inflammatory cytokine, IL-1beta. The other mechanism is a protease-mediated process which involves lysosomal proteases and calcium-dependent neutral proteases. These two stimulating pathways were followed by Bad, Bak, Bid activation and subsequently the upregulation of cytochrome c and caspase-3. In addition, mobilization of K+ ion and other accessory apoptotic genes such as annexins and clusterin were also upregulated.
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Affiliation(s)
- Sukathida Ubol
- Department of Microbiology, Faculty of Science, Mahidol University, Ratchatewee, Bangkok, Thailand.
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Chan SHH, Wu KLH, Wang LL, Chan JYH. Nitric oxide- and superoxide-dependent mitochondrial signaling in endotoxin-induced apoptosis in the rostral ventrolateral medulla of rats. Free Radic Biol Med 2005; 39:603-18. [PMID: 16085179 DOI: 10.1016/j.freeradbiomed.2005.04.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Revised: 03/21/2005] [Accepted: 04/16/2005] [Indexed: 11/21/2022]
Abstract
This study evaluated the hypothesis that the repertoire of cellular events that underlie circulatory fatality during endotoxemia may entail mitochondrial respiratory enzyme dysfunction, followed by the release of cytochrome c to the cytosol that triggers the activation of caspase cascades, leading to apoptotic cell death in the rostral ventrolateral medulla (RVLM) where sympathetic premotor neurons responsible for maintaining vasomotor tone are located. In adult Sprague-Dawley rats maintained under propofol anesthesia, nucleosomal DNA fragmentation was detected in the RVLM in a temporal profile that coincided positively with the progression of cardiovascular depression during experimental endotoxemia induced by Escherichia coli lipopolysaccharide (LPS). LPS also induced nitric oxide (NO) and superoxide (O(2)(-)) production, depressed mitochondrial Complex I and IV activity, promoted the release of cytochrome c from mitochondria to cytosol, upregulated the cytosolic expression of activated caspase-9 and -3, or increased caspase-3 enzyme activity in the RVLM. Microinjection bilaterally into the RVLM of an inducible nitric oxide synthase (iNOS) blocker, S-methylisothiourea, or a superoxide dismutase mimetic, Tempol, significantly blunted these apoptotic cellular events and antagonized the cardiovascular depression during endotoxemia. We conclude that caspase-dependent apoptotic cell death that results from NO- and O(2)(-)-associated mitochondrial signaling in the RVLM may underlie fatal cardiovascular depression during endotoxemia.
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Affiliation(s)
- Samuel H H Chan
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung 804, Taiwan, Republic of China
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Knoblach SM, Huang X, VanGelderen J, Calva-Cerqueira D, Faden AI. Selective caspase activation may contribute to neurological dysfunction after experimental spinal cord trauma. J Neurosci Res 2005; 80:369-80. [PMID: 15795935 DOI: 10.1002/jnr.20465] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Caspases are implicated in apoptotic cell death after spinal cord injury (SCI), but the relative contribution of these proteases to the secondary injury process has been only partially described. We examined the activation of caspases 1, 2, 3, 6, 8, and 9 from 1 hr to 7 days after moderate contusion injury induced by a weight-drop method in the rat. Tissue homogenates from a 1-cm segment of cord that contained the site of impact were processed by fluorometric enzymatic activity assays and/or immunoblotting methods. Caspases 3, 8, and 9 were activated from 1 to 72 hr after injury, whereas caspases 1, 2, and 6 were not. Double-label immunohistochemistry utilizing antibodies for CNS cell-type-specific markers and active subunits of caspases 3, 8, or 9 showed that, at 4 and 72 hr after injury, these caspases were primarily activated in neurons and oligodendrocytes, rather than in astrocytes. Active caspase subunits were present in neurons within the necrotic lesion core at 4 hr after injury and in cells more than several segments away at 4 or 72 hr after injury. Intrathecal injection of the pan-caspase inhibitor Boc-Asp (OMe)-fluoromethylketone (Boc-d-fmk) at 15 min after injury improved locomotor function 21 and 28 days later. Treatment with the selective caspase 3 inhibitor N-benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethyl ketone (z-DEVD-fmk) improved function at 21 days after injury. These data suggest that caspases 3, 8, and 9 may be differentially activated in white and gray matter after spinal cord trauma and that such activation may contribute to subsequent neurological dysfunction.
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Affiliation(s)
- S M Knoblach
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20007, USA.
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