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C Sekhar V, Gulia KK, Deepti A, Chakrapani PSB, Baby S, Viswanathan G. Protection by Nano-Encapsulated Bacoside A and Bacopaside I in Seizure Alleviation and Improvement in Sleep- In Vitro and In Vivo Evidences. Mol Neurobiol 2024; 61:3296-3313. [PMID: 37987958 DOI: 10.1007/s12035-023-03741-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 10/24/2023] [Indexed: 11/22/2023]
Abstract
Therapeutic options to contain seizures, a transitional stage of many neuropathologies, are limited due to the blood-brain barrier (BBB). Herbal nanoparticle formulations can be employed to enhance seizure prognosis. Bacoside A (BM3) and bacopaside I (BM4) were isolated from Bacopa monnieri and synthesized as nanoparticles (BM3NP and BM4NP, respectively) for an effective delivery system to alleviate seizures and associated conditions. After physicochemical characterization, cell viability was assessed on mouse neuronal stem cells (mNSC) and neuroblastoma cells (N2a). Thereafter, anti-seizure effects, mitochondrial membrane potential (MMP), apoptosis, immunostaining and epileptic marker mRNA expression were determined in vitro. The seizure-induced changes in the cortical electroencephalogram (EEG), electromyography (EMG), Non-Rapid Eye Movement (NREM) and Rapid Eye Movement (REM) sleep were monitored in vivo in a kainic acid (KA)-induced rat seizure model. The sizes of BM3NPs and BM4NPs were 165.5 nm and 689.6 nm, respectively. They were biocompatible and also aided in neuroplasticity in mNSC. BM3NPs and BM4NPs depicted more than 50% cell viability in N2a cells, with IC50 values of 1609 and 2962 µg/mL, respectively. Similarly, these nanoparticles reduced the cytotoxicity of N2a cells upon KA treatment. Nanoparticles decreased the expression of epileptic markers like fractalkine, HMGB1, FOXO3a and pro-inflammatory cytokines (P < 0.05). They protected neurons from apoptosis and restored MMP. After administration of BM3NPs and BM4NPs, KA-treated rats attained a significant reduction in the epileptic spikes, sleep latency and an increase in NREM sleep duration. Results indicate the potential of BM3NPs and BM4NPs in neutralizing the KA-induced excitotoxic seizures in neurons.
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Affiliation(s)
- Vini C Sekhar
- Phytochemistry and Phytopharmacology Division, KSCSTE-Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram, 695562, Kerala, India
- University of Kerala, Thiruvananthapuram, 695034, Kerala, India
| | - Kamalesh K Gulia
- Division of Sleep Research, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, 695011, India
| | - Ayswaria Deepti
- Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, 682022, Kerala, India
| | - P S Baby Chakrapani
- Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, 682022, Kerala, India
| | - Sabulal Baby
- Phytochemistry and Phytopharmacology Division, KSCSTE-Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram, 695562, Kerala, India
| | - Gayathri Viswanathan
- Phytochemistry and Phytopharmacology Division, KSCSTE-Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram, 695562, Kerala, India.
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miR-223 Enhances the Neuroprotection of Estradiol Against Oxidative Stress Injury by Inhibiting the FOXO3/TXNIP Axis. Neurochem Res 2021; 47:1865-1877. [PMID: 34843004 DOI: 10.1007/s11064-021-03490-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 08/20/2021] [Accepted: 09/09/2021] [Indexed: 12/23/2022]
Abstract
Alzheimer's disease (AD) is an irreversible neurodegenerative disorder characterized by complex pathogenesis, of which oxidative stress has long been regarded as a major mechanism. Previously, the protective effects of estradiol on SH-SY5Y cells against Aβ42-induced injuries were demonstrated. In this study, the protection of SH-SY5Y cells by estradiol from H2O2-caused oxidative stress injury and Alzheimer's mice was further confirmed. H2O2 downregulated, whereas estradiol upregulated miR-223 expression. miR-223 overexpression promoted cell viability, inhibited cell apoptosis, reduced ROS levels, enhanced Superoxide Dismutase (SOD) activity, and decreased malondialdehyde (MDA) content. However, miR-223 inhibition exerted opposite effects. miR-223 directly targeted forkhead box O3 (FOXO3) and inhibited FOXO3 expression. H2O2 increased, whereas estradiol decreased thioredoxin interacting protein (TXNIP) levels; FOXO3 positively regulated TXNIP protein levels. In SH-SY5Y cells, FOXO3 overexpression increased, whereas FOXO3 knockdown reduced the cell apoptosis and ROS levels. FOXO3 bound to TXNIP promoter region and activated TXNIP transcription, whereas the activation could be partially inhibited by estradiol. Collectively, the FOXO3/TXNIP axis is downstream of miR-223. miR-223 enhances the neuroprotection of estradiol against oxidative stress injury through the FOXO3/TXNIP axis.
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Adenosine A1 Receptor Agonist (R-PIA) before Pilocarpine Modulates Pro- and Anti-Apoptotic Factors in an Animal Model of Epilepsy. Pharmaceuticals (Basel) 2021; 14:ph14040376. [PMID: 33919533 PMCID: PMC8074097 DOI: 10.3390/ph14040376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/15/2021] [Accepted: 04/16/2021] [Indexed: 11/26/2022] Open
Abstract
We aimed to characterize the mechanisms involved in neuroprotection by R-PIA administered before pilocarpine-induced seizures. Caspase-1 and caspase-3 activities were assayed using fluorimetry, and cathepsin D, HSP-70, and AKT expression levels were assayed using Western Blot of hippocampal samples. R-PIA was injected before pilocarpine (PILO), and four groups were studied at 1 h 30 min and 7 days following initiation of status epilepticus (SE): PILO, R-PIA+PILO, SALINE, and R-PIA+SALINE. At 1 h 30 min, significantly higher activities of caspase-1 and -3 were observed in the PILO group than in the SALINE group. Caspase-1 and -3 activities were higher in the R-PIA+PILO group than in the PILO group. At 7 days following SE, caspase-1 and -3 activities were higher than in the initial post-seizure phase compared to the SALINE group. The pretreatment of rats receiving PILO significantly reduced caspase activities compared to the PILO group. Expression of HSP-70, AKT, and cathepsin D was significantly higher in the PILO group than in the SALINE. In the R-PIA+PILO group, the expression of AKT and HSP-70 was greater than in rats receiving only PILO, while cathepsin D presented decreased expression. Pretreatment with R-PIA in PILO-injected rats strongly inhibited caspase-1 and caspase-3 activities and cathepsin D expression. It also increased expression levels of the neuroprotective proteins HSP-70 and AKT, suggesting an important role in modulating the cellular survival cascade.
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Kelly E, Sharma D, Wilkinson CJ, Williams RSB. Diacylglycerol kinase (DGKA) regulates the effect of the epilepsy and bipolar disorder treatment valproic acid in Dictyostelium discoideum. Dis Model Mech 2018; 11:11/9/dmm035600. [PMID: 30135067 PMCID: PMC6176992 DOI: 10.1242/dmm.035600] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 07/03/2018] [Indexed: 12/30/2022] Open
Abstract
Valproic acid (VPA) provides a common treatment for both epilepsy and bipolar disorder; however, common cellular mechanisms relating to both disorders have yet to be proposed. Here, we explore the possibility of a diacylglycerol kinase (DGK) playing a role in regulating the effect of VPA relating to the treatment of both disorders, using the biomedical model Dictyostelium discoideum. DGK enzymes provide the first step in the phosphoinositide recycling pathway, implicated in seizure activity. They also regulate levels of diacylglycerol (DAG), thereby regulating the protein kinase C (PKC) activity that is linked to bipolar disorder-related signalling. Here, we show that ablation of the single Dictyostelium dgkA gene results in reduced sensitivity to the acute effects of VPA on cell behaviour. Loss of dgkA also provides reduced sensitivity to VPA in extended exposure during development. To differentiate a potential role for this DGKA-dependent mechanism in epilepsy and bipolar disorder treatment, we further show that the dgkA null mutant is resistant to the developmental effects of a range of structurally distinct branched medium-chain fatty acids with seizure control activity and to the bipolar disorder treatment lithium. Finally, we show that VPA, lithium and novel epilepsy treatments function through DAG regulation, and the presence of DGKA is necessary for compound-specific increases in DAG levels following treatment. Thus, these experiments suggest that, in Dictyostelium, loss of DGKA attenuates a common cellular effect of VPA relating to both epilepsy and bipolar disorder treatments, and that a range of new compounds with this effect should be investigated as alternative therapeutic agents. This article has an associated First Person interview with the first author of the paper. Editor's choice: Here, using a tractable model system, Dictyostelium discoideum, we show that diacylglycerol kinase activity might contribute to the cellular mechanism of action of the epilepsy and bipolar disorder treatment, valproic acid.
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Affiliation(s)
- Elizabeth Kelly
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Devdutt Sharma
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Christopher J Wilkinson
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Robin S B Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
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Cerebrospinal fluid microRNAs are potential biomarkers of temporal lobe epilepsy and status epilepticus. Sci Rep 2017; 7:3328. [PMID: 28607431 PMCID: PMC5468228 DOI: 10.1038/s41598-017-02969-6] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 04/20/2017] [Indexed: 02/06/2023] Open
Abstract
There is a need for diagnostic biomarkers of epilepsy and status epilepticus to support clinical examination, electroencephalography and neuroimaging. Extracellular microRNAs may be potentially ideal biomarkers since some are expressed uniquely within specific brain regions and cell types. Cerebrospinal fluid offers a source of microRNA biomarkers with the advantage of being in close contact with the target tissue and sites of pathology. Here we profiled microRNA levels in cerebrospinal fluid from patients with temporal lobe epilepsy or status epilepticus, and compared findings to matched controls. Differential expression of 20 microRNAs was detected between patient groups and controls. A validation phase included an expanded cohort and samples from patients with other neurological diseases. This identified lower levels of miR-19b in temporal lobe epilepsy compared to controls, status epilepticus and other neurological diseases. Levels of miR-451a were higher in status epilepticus compared to other groups whereas miR-21-5p differed in status epilepticus compared to temporal lobe epilepsy but not to other neurological diseases. Targets of these microRNAs include proteins regulating neuronal death, tissue remodelling, gliosis and inflammation. The present study indicates cerebrospinal fluid contains microRNAs that can support differential diagnosis of temporal lobe epilepsy and status epilepticus from other neurological and non-neurological diseases.
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Chang P, Walker MC, Williams RSB. Seizure-induced reduction in PIP3 levels contributes to seizure-activity and is rescued by valproic acid. Neurobiol Dis 2013; 62:296-306. [PMID: 24148856 PMCID: PMC3898270 DOI: 10.1016/j.nbd.2013.10.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 09/11/2013] [Accepted: 10/11/2013] [Indexed: 12/31/2022] Open
Abstract
Phosphatidylinositol (3–5) trisphosphate (PIP3) is a central regulator of diverse neuronal functions that are critical for seizure progression, however its role in seizures is unclear. We have recently hypothesised that valproic acid (VPA), one of the most commonly used drugs for the treatment of epilepsy, may target PIP3 signalling as a therapeutic mode of action. Here, we show that seizure induction using kainic acid in a rat in vivo epilepsy model resulted in a decrease in hippocampal PIP3 levels and reduced protein kinase B (PKB/AKT) phosphorylation, measured using ELISA mass assays and Western blot analysis, and both changes were restored following VPA treatment. These finding were reproduced in cultured rat hippocampal primary neurons and entorhinal cortex–hippocampal slices during exposure to the GABA(A) receptor antagonist pentylenetetrazol (PTZ), which is widely used to generate seizures and seizure-like (paroxysmal) activity. Moreover, VPA's effect on paroxysmal activity in the PTZ slice model is blocked by phosphatidylinositol 3-kinase (PI3K) inhibition or PIP2 sequestration by neomycin, indicating that VPA's efficacy is dependent upon PIP3 signalling. PIP3 depletion following PTZ treatment may also provide a positive feedback loop, since enhancing PIP3 depletion increases, and conversely, reducing PIP3 dephosphorylation reduces paroxysmal activity and this effect is dependent upon AMPA receptor activation. Our results therefore indicate that PIP3 depletion occurs with seizure activity, and that VPA functions to reverse these effects, providing a novel mechanism for VPA in epilepsy treatment. In vivo seizure induction (using kainic acid) reduces hippocampal PIP3 levels. In vivo seizure induction (using kainic acid) reduces hippocampal phospho-PKB levels. Valproic acid protects against these reductions under seizure conditions only. Similar regulation is seen with PTZ-induced in vitro seizure activity. Seizure-induced PIP3 reduction causes a feedback activation of seizure activity.
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Affiliation(s)
- Pishan Chang
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Matthew C Walker
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, WC1N 3BG, UK.
| | - Robin S B Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK.
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Henshall DC, Engel T. Contribution of apoptosis-associated signaling pathways to epileptogenesis: lessons from Bcl-2 family knockouts. Front Cell Neurosci 2013; 7:110. [PMID: 23882182 PMCID: PMC3712126 DOI: 10.3389/fncel.2013.00110] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/22/2013] [Indexed: 01/22/2023] Open
Abstract
Neuronal cell death is a pathophysiological consequence of many brain insults that trigger epilepsy and has been implicated as a causal factor in epileptogenesis. Seizure-induced neuronal death features excitotoxic necrosis and apoptosis-associated signaling pathways, including activation of multiple members of the Bcl-2 gene family. The availability of mice in which individual Bcl-2 family members have been deleted has provided the means to determine whether they have causal roles in neuronal death and epileptogenesis in vivo. Studies show that multiple members of the Bcl-2 family are activated following status epilepticus and the seizure and damage phenotypes of eight different knockouts of the Bcl-2 family have now been characterized. Loss of certain pro-apoptotic members, including Puma, protected against seizure-induced neuronal death whereas loss of anti-apoptotic Mcl-1 and Bcl-w enhanced hippocampal damage. Notably, loss of two putatively pro-apoptotic members, Bak and Bmf, resulted in more seizure-damage while deletion of Bid had no effect, indicating the role of certain Bcl-2 family proteins in epileptic brain injury is distinct from their contributions following other stressors or in non-CNS tissue. Notably, Puma-deficient mice develop fewer spontaneous seizures after status epilepticus suggesting neuroprotection may preserve functional inhibition, either directly by preserving neuronal networks or indirectly, for example by limiting reactive gliosis and pro-inflammatory responses to neuronal death. Together, these studies support apoptosis-associated molecular mechanisms controlling neuronal death as a component of epileptogenesis which might be targetable to protect against seizure-damage, cognitive deficits and mitigate the severity of syndrome following epilepsy-precipitating injuries to the brain.
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Affiliation(s)
- David C. Henshall
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, St. Stephen's GreenDublin, Ireland
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Bmf upregulation through the AMP-activated protein kinase pathway may protect the brain from seizure-induced cell death. Cell Death Dis 2013; 4:e606. [PMID: 23618904 PMCID: PMC3668628 DOI: 10.1038/cddis.2013.136] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Prolonged seizures (status epilepticus, SE) can cause neuronal death within brain regions such as the hippocampus. This may contribute to impairments in cognitive functioning and trigger or exacerbate epilepsy. Seizure-induced neuronal death is mediated, at least in part, by apoptosis-associated signaling pathways. Indeed, mice lacking certain members of the potently proapoptotic BH3-only subfamily of Bcl-2 proteins are protected against hippocampal damage caused by status epilepticus. The recently identified BH3-only protein Bcl-2-modifying factor (Bmf) normally interacts with the cytoskeleton, but upon certain cellular stresses, such as loss of extracellular matrix adhesion or energy crisis, Bmf relocalizes to mitochondria, where it can promote Bax activation and mitochondrial dysfunction. Although Bmf has been widely reported in the hematopoietic system to exert a proapoptotic effect, no studies have been undertaken in models of neurological disorders. To examine whether Bmf is important for seizure-induced neuronal death, we studied Bmf induction after prolonged seizures induced by intra-amygdala kainic acid (KA) in mice, and examined the effect of Bmf-deficiency on seizures and damage caused by SE. Seizures triggered an early (1-8 h) transcriptional activation and accumulation of Bax in the cell death-susceptible hippocampal CA3 subfield. Bmf mRNA was biphasically upregulated beginning at 1 h after SE and returning to normal by 8 h, while again being found elevated in the hippocampus of epileptic mice. Bmf upregulation was prevented by Compound C, an inhibitor of adenosine monophosphate-activated protein kinase, indicating Bmf expression may be induced in response to bioenergetic stress. Bmf-deficient mice showed normal sensitivity to the convulsant effects of KA, but, surprisingly, displayed significantly more neuronal death in the hippocampal CA1 and CA3 subfields after SE. These are the first studies investigating Bmf in a model of neurologic injury, and suggest that Bmf may protect neurons against seizure-induced neuronal death in vivo.
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Brennan GP, Jimenez-Mateos EM, McKiernan RC, Engel T, Tzivion G, Henshall DC. Transgenic overexpression of 14-3-3 zeta protects hippocampus against endoplasmic reticulum stress and status epilepticus in vivo. PLoS One 2013; 8:e54491. [PMID: 23359526 PMCID: PMC3554740 DOI: 10.1371/journal.pone.0054491] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 12/12/2012] [Indexed: 01/05/2023] Open
Abstract
14-3-3 proteins are ubiquitous molecular chaperones that are abundantly expressed in the brain where they regulate cell functions including metabolism, the cell cycle and apoptosis. Brain levels of several 14-3-3 isoforms are altered in diseases of the nervous system, including epilepsy. The 14-3-3 zeta (ζ) isoform has been linked to endoplasmic reticulum (ER) function in neurons, with reduced levels provoking ER stress and increasing vulnerability to excitotoxic injury. Here we report that transgenic overexpression of 14-3-3ζ in mice results in selective changes to the unfolded protein response pathway in the hippocampus, including down-regulation of glucose-regulated proteins 78 and 94, activating transcription factors 4 and 6, and Xbp1 splicing. No differences were found between wild-type mice and transgenic mice for levels of other 14-3-3 isoforms or various other 14-3-3 binding proteins. 14-3-3ζ overexpressing mice were potently protected against cell death caused by intracerebroventricular injection of the ER stressor tunicamycin. 14-3-3ζ overexpressing mice were also potently protected against neuronal death caused by prolonged seizures. These studies demonstrate that increased 14-3-3ζ levels protect against ER stress and seizure-damage despite down-regulation of the unfolded protein response. Delivery of 14-3-3ζ may protect against pathologic changes resulting from prolonged or repeated seizures or where injuries provoke ER stress.
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Affiliation(s)
- Gary P. Brennan
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Eva M. Jimenez-Mateos
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Ross C. McKiernan
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Tobias Engel
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Guri Tzivion
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - David C. Henshall
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
- * E-mail:
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Salih DAM, Rashid AJ, Colas D, de la Torre-Ubieta L, Zhu RP, Morgan AA, Santo EE, Ucar D, Devarajan K, Cole CJ, Madison DV, Shamloo M, Butte AJ, Bonni A, Josselyn SA, Brunet A. FoxO6 regulates memory consolidation and synaptic function. Genes Dev 2012; 26:2780-801. [PMID: 23222102 DOI: 10.1101/gad.208926.112] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The FoxO family of transcription factors is known to slow aging downstream from the insulin/IGF (insulin-like growth factor) signaling pathway. The most recently discovered FoxO isoform in mammals, FoxO6, is highly enriched in the adult hippocampus. However, the importance of FoxO factors in cognition is largely unknown. Here we generated mice lacking FoxO6 and found that these mice display normal learning but impaired memory consolidation in contextual fear conditioning and novel object recognition. Using stereotactic injection of viruses into the hippocampus of adult wild-type mice, we found that FoxO6 activity in the adult hippocampus is required for memory consolidation. Genome-wide approaches revealed that FoxO6 regulates a program of genes involved in synaptic function upon learning in the hippocampus. Consistently, FoxO6 deficiency results in decreased dendritic spine density in hippocampal neurons in vitro and in vivo. Thus, FoxO6 may promote memory consolidation by regulating a program coordinating neuronal connectivity in the hippocampus, which could have important implications for physiological and pathological age-dependent decline in memory.
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Affiliation(s)
- Dervis A M Salih
- Department of Genetics, Stanford University, Stanford, California 94305, USA
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Lin TK, Cheng CH, Chen SD, Liou CW, Huang CR, Chuang YC. Mitochondrial dysfunction and oxidative stress promote apoptotic cell death in the striatum via cytochrome c/caspase-3 signaling cascade following chronic rotenone intoxication in rats. Int J Mol Sci 2012; 13:8722-8739. [PMID: 22942730 PMCID: PMC3430261 DOI: 10.3390/ijms13078722] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Revised: 07/04/2012] [Accepted: 07/05/2012] [Indexed: 12/21/2022] Open
Abstract
Parkinson's disease (PD) is a progressive neurological disorder marked by nigrostriatal dopaminergic degeneration. Evidence suggests that mitochondrial dysfunction may be linked to PD through a variety of different pathways, including free-radical generation and dysfunction of the mitochondrial Complex I activity. In Lewis rats, chronic systemic administration of a specific mitochondrial Complex I inhibitor, rotenone (3 mg/kg/day) produced parkinsonism-like symptoms. Increased oxidized proteins and peroxynitrite, and mitochondrial or cytosol translocation of Bim, Bax or cytochrome c in the striatum was observed after 2-4 weeks of rotenone infusion. After 28 days of systemic rotenone exposure, imunohistochemical staining for tyrosine hydroxylase indicated nigrostriatal dopaminergic neuronal cell degeneration. Characteristic histochemical (TUNEL or activated caspase-3 staining) or ultrastructural (electron microscopy) features of apoptotic cell death were present in the striatal neuronal cell after chronic rotenone intoxication. We conclude that chronic rotenone intoxication may enhance oxidative and nitrosative stress that induces mitochondrial dysfunction and ultrastructural damage, resulting in translocation of Bim and Bax from cytosol to mitochondria that contributes to apoptotic cell death in the striatum via cytochrome c/caspase-3 signaling cascade.
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Affiliation(s)
- Tsu-Kung Lin
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan; E-Mails: (S.-D.C.); (C.-W.L.); (C.-R.H.)
- Center for Parkinson’s Disease, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan
- Authors to whom correspondence should be addressed; E-Mails: (T.-K.L.); (Y.-C.C.); Tel.: +886-7-7317123 (T.-K.L.) (Y.-C.C.); Fax: +886-7-7318762 (T.-K.L.) (Y.-C.C.)
| | - Ching-Hsiao Cheng
- Neurosurgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan; E-Mail:
| | - Shang-Der Chen
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan; E-Mails: (S.-D.C.); (C.-W.L.); (C.-R.H.)
- Center for Parkinson’s Disease, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan
- Center for Translational Research in Biomedical Sciences, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan
| | - Chia-Wei Liou
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan; E-Mails: (S.-D.C.); (C.-W.L.); (C.-R.H.)
- Center for Parkinson’s Disease, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan
| | - Chi-Ren Huang
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan; E-Mails: (S.-D.C.); (C.-W.L.); (C.-R.H.)
| | - Yao-Chung Chuang
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan; E-Mails: (S.-D.C.); (C.-W.L.); (C.-R.H.)
- Center for Parkinson’s Disease, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan
- Neurosurgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan; E-Mail:
- Department of Biological Science, National Sun Yet-Sen University, Kaohsiung 804, Taiwan
- Authors to whom correspondence should be addressed; E-Mails: (T.-K.L.); (Y.-C.C.); Tel.: +886-7-7317123 (T.-K.L.) (Y.-C.C.); Fax: +886-7-7318762 (T.-K.L.) (Y.-C.C.)
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Zhou W, Chen L, Yang S, Li F, Li X. Behavioral stress-induced activation of FoxO3a in the cerebral cortex of mice. Biol Psychiatry 2012; 71:583-92. [PMID: 21978520 PMCID: PMC3254805 DOI: 10.1016/j.biopsych.2011.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 08/22/2011] [Accepted: 08/25/2011] [Indexed: 01/22/2023]
Abstract
BACKGROUND The transcription factor FoxO3a is highly expressed in brain, but little is known about the response of FoxO3a to behavioral stress and its impact in the associated behavioral changes. METHODS We tested the response of brain FoxO3a in the learned helplessness (LH) paradigm and tested signaling pathways that mediate the response of FoxO3a. RESULTS A single session of inescapable shocks (IES) in mice reduced FoxO3a phosphorylation at the Akt-regulating serine/threonine residues and induced prolonged nuclear accumulation of FoxO3a in the cerebral cortex, both indicating activation of FoxO3a in brain. The response of FoxO3a is accompanied by a transient inactivation of Akt and a prolonged activation of glycogen synthase kinase-3beta (GSK3β). Noticeably, FoxO3a formed a protein complex with GSK3β in the cerebral cortex, and the interaction between the two proteins was stronger in IES-treated mice. Inhibition of glycogen synthase kinase-3 was able to abolish IES-induced LH behavior, disrupt IES-induced GSK3β-FoxO3a interaction, and reduce nuclear FoxO3a accumulation. In vitro approaches further revealed that the interaction between GSK3β and FoxO3a was strongest when both were active; FoxO3a was phosphorylated by recombinant GSK3β; and glycogen synthase kinase-3 inhibitors effectively reduced FoxO3a transcriptional activity. Importantly, IES-induced LH behavior was markedly diminished in FoxO3a-deficient mice that had minimal FoxO3a expression and reduced levels of FoxO3a-inducible genes. CONCLUSIONS FoxO3a is activated in response to IES by interacting with GSK3β, and inhibition of GSK3β or reducing FoxO3a expression promotes resistance to stress-induced behavioral disturbance by disrupting this signaling mechanism.
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Affiliation(s)
- Wenjun Zhou
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA
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13
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Piro RM, Molineris I, Ala U, Di Cunto F. Evaluation of candidate genes from orphan FEB and GEFS+ loci by analysis of human brain gene expression atlases. PLoS One 2011; 6:e23149. [PMID: 21858011 PMCID: PMC3157479 DOI: 10.1371/journal.pone.0023149] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 07/07/2011] [Indexed: 12/19/2022] Open
Abstract
Febrile seizures, or febrile convulsions (FEB), represent the most common form of childhood seizures and are believed to be influenced by variations in several susceptibility genes. Most of the associated loci, however, remain ‘orphan’, i.e. the susceptibility genes they contain still remain to be identified. Further orphan loci have been mapped for a related disorder, genetic (generalized) epilepsy with febrile seizures plus (GEFS+). We show that both spatially mapped and ‘traditional’ gene expression data from the human brain can be successfully employed to predict the most promising candidate genes for FEB and GEFS+, apply our prediction method to the remaining orphan loci and discuss the validity of the predictions. For several of the orphan FEB/GEFS+ loci we propose excellent, and not always obvious, candidates for mutation screening in order to aid in gaining a better understanding of the genetic origin of the susceptibility to seizures.
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Affiliation(s)
- Rosario M Piro
- Molecular Biotechnology Center and Department of Genetics, Biology and Biochemistry, University of Torino, Torino, Italy.
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14
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Bozzi Y, Dunleavy M, Henshall DC. Cell signaling underlying epileptic behavior. Front Behav Neurosci 2011; 5:45. [PMID: 21852968 PMCID: PMC3151612 DOI: 10.3389/fnbeh.2011.00045] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 07/13/2011] [Indexed: 12/12/2022] Open
Abstract
Epilepsy is a complex disease, characterized by the repeated occurrence of bursts of electrical activity (seizures) in specific brain areas. The behavioral outcome of seizure events strongly depends on the brain regions that are affected by overactivity. Here we review the intracellular signaling pathways involved in the generation of seizures in epileptogenic areas. Pathways activated by modulatory neurotransmitters (dopamine, norepinephrine, and serotonin), involving the activation of extracellular-regulated kinases and the induction of immediate early genes (IEGs) will be first discussed in relation to the occurrence of acute seizure events. Activation of IEGs has been proposed to lead to long-term molecular and behavioral responses induced by acute seizures. We also review deleterious consequences of seizure activity, focusing on the contribution of apoptosis-associated signaling pathways to the progression of the disease. A deep understanding of signaling pathways involved in both acute- and long-term responses to seizures continues to be crucial to unravel the origins of epileptic behaviors and ultimately identify novel therapeutic targets for the cure of epilepsy.
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Affiliation(s)
- Yuri Bozzi
- Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Trento, Italy
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15
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In vivo contributions of BH3-only proteins to neuronal death following seizures, ischemia, and traumatic brain injury. J Cereb Blood Flow Metab 2011; 31:1196-210. [PMID: 21364604 PMCID: PMC3099642 DOI: 10.1038/jcbfm.2011.26] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The Bcl-2 homology (BH) domain 3-only proteins are a proapoptotic subgroup of the Bcl-2 gene family, which regulate cell death via effects on mitochondria. The BH3-only proteins react to various cell stressors and promote cell death by binding and inactivating antiapoptotic Bcl-2 family members and direct activation of proapoptotic multi-BH domain proteins such as Bax. Here, we review the in vivo evidence for their involvement in the pathophysiology of status epilepticus and contrast it to ischemia and traumatic brain injury. Seizures in rodents activate three potent proapoptotic BH3-only proteins: Bid, Bim, and Puma. Analysis of damage after seizures in mice singly deficient for each BH3-only protein supports a causal role for Puma and to a lesser extent Bim but, surprisingly, not Bid. In ischemia and trauma, where core aspects of the pathophysiology of cell death overlap, multiple BH3-only proteins are also activated and Bid has been shown to be required for neuronal death. The findings suggest that while each neurologic insult activates multiple BH3-only proteins, there may be specificity in their functional contribution. Future challenges include evaluating the remaining BH3-only proteins, explaining different causal contributions, and, if possible, exploring neurologic outcomes in mouse models deficient for multiple BH3-only proteins.
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16
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Chen SD, Chang AYW, Chuang YC. The potential role of mitochondrial dysfunction in seizure-associated cell death in the hippocampus and epileptogenesis. J Bioenerg Biomembr 2011; 42:461-5. [PMID: 21153870 DOI: 10.1007/s10863-010-9321-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Epilepsy is considered one of the most common neurological disorders worldwide. The burst firing neurons associated with prolonged epileptic discharges could lead to a large number of changes with events of cascades at the cellular level. From its role as the cellular powerhouse, mitochondria also play a crucial role in the mechanisms of cell death. Emerging evidence has shown that prolonged seizures may result in mitochondrial dysfunction and increase of oxidative and nitrosative stress in the hippocampus that precede neuronal cell death and cause subsequent epileptogenesis. The selective dysfunction of mitochondrial respiratory chain Complex I has been suggested to be a biochemical hallmark of seizure-induced neuronal cell death and epileptogenesis. Therefore, protection of mitochondria from bioenergetic failure and oxidative stress in the hippocampus may open a new vista to the development of effective neuroprotective strategies against seizure-induced brain damage and to the design of novel treatment perspectives against therapy-resistant forms of epilepsy.
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Affiliation(s)
- Shang-Der Chen
- Department of Neurology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan
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17
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Thompson S, Pearson AN, Ashley MD, Jessick V, Murphy BM, Gafken P, Henshall DC, Morris KT, Simon RP, Meller R. Identification of a novel Bcl-2-interacting mediator of cell death (Bim) E3 ligase, tripartite motif-containing protein 2 (TRIM2), and its role in rapid ischemic tolerance-induced neuroprotection. J Biol Chem 2011; 286:19331-9. [PMID: 21478148 DOI: 10.1074/jbc.m110.197707] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously shown that the cell death-promoting protein Bcl-2-interacting mediator of cell death (Bim) is ubiquitinated and degraded following a neuroprotection-conferring episode of brief ischemia (preconditioning). Here, we identify the E3 ligase that ubiquitinates Bim in this model, using a proteomics approach. Using phosphorylated GST-Bim as bait, we precipitated and identified by mass spectrometry tripartite motif protein 2 (TRIM2), a RING (really interesting new gene) domain-containing protein. The reaction between TRIM2 and Bim was confirmed using co-immunoprecipitation followed by immunoblotting. We show that TRIM2 binds to Bim when it is phosphorylated by p42/p44 MAPK but does not interact with a nonphosphorylatable Bim mutant (3ABim). 12-O-tetradecanoylphorbol-13-acetate activation of p42/p44 MAPK drives Bim ubiquitination in mouse embryonic fibroblast cells and is associated with an increased interaction between TRIM2 and Bim. One hour following preconditioning ischemia, the binding of Bim to TRIM2 increased, consistent with the time window of enhanced Bim degradation. Blocking p42/p44 MAPK activation following preconditioning ischemia with U0126 or using the nonphosphorylatable 3ABim reduced the binding between Bim and TRIM2. Immunodepletion of TRIM2 from cell lysates prepared from preconditioned cells reduced Bim ubiquitination. Finally, suppression of TRIM2 expression, using lentivirus transduction of shRNAmir, stabilized Bim protein levels and blocked neuroprotection observed in rapid ischemic tolerance. Taken together, these data support a role for TRIM2 in mediating the p42/p44 MAPK-dependent ubiquitination of Bim in rapid ischemic tolerance.
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Affiliation(s)
- Simon Thompson
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia 30310-1495, USA
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18
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Engel T, Schindler CK, Sanz-Rodriguez A, Conroy RM, Meller R, Simon RP, Henshall DC. Expression of neurogenesis genes in human temporal lobe epilepsy with hippocampal sclerosis. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2010; 3:38-47. [PMID: 21479101 PMCID: PMC3068852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Accepted: 12/08/2010] [Indexed: 05/30/2023]
Abstract
Both evoked and spontaneous seizures have been reported to increase neurogenesis in animal models. Less is known about whether neurogenesis and markers thereof are aberrantly expressed in human temporal lobe epilepsy (TLE) with hippocampal sclerosis. In the present study we measured protein levels of multiple neurogenesis marker genes using Western blotting. Tissue homogenates from sclerotic hippocampus surgically resected from patients with pharmacoresistantTLE (n = 7) were compared to hippocampal samples from a group of age- and gender-matched autopsy controls (n = 6). Expression of the mature neuron marker NeuN was significantly lower in TLE samples compared to controls. In contrast, levels of neurogenesis-associated genes including TUC-4, doublecortin, Neu-roD and Numb, were all similarly expressed in TLE and control hippocampus samples. The present study suggests hippocampal expression levels of proteins associated with neurogenesis are not notably different in human TLE, implying the sclerotic hippocampus may retain neurogenic potential.
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19
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Hardingham GE, Bading H. Synaptic versus extrasynaptic NMDA receptor signalling: implications for neurodegenerative disorders. Nat Rev Neurosci 2010; 11:682-96. [PMID: 20842175 PMCID: PMC2948541 DOI: 10.1038/nrn2911] [Citation(s) in RCA: 1137] [Impact Index Per Article: 81.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
There is a long-standing paradox that NMDA (N-methyl-D-aspartate) receptors (NMDARs) can both promote neuronal health and kill neurons. Recent studies show that NMDAR-induced responses depend on the receptor location: stimulation of synaptic NMDARs, acting primarily through nuclear Ca(2+) signalling, leads to the build-up of a neuroprotective 'shield', whereas stimulation of extrasynaptic NMDARs promotes cell death. These differences result from the activation of distinct genomic programmes and from opposing actions on intracellular signalling pathways. Perturbations in the balance between synaptic and extrasynaptic NMDAR activity contribute to neuronal dysfunction in acute ischaemia and Huntington's disease, and could be a common theme in the aetiology of neurodegenerative diseases. Neuroprotective therapies should aim to both enhance the effect of synaptic activity and disrupt extrasynaptic NMDAR-dependent death signalling.
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Affiliation(s)
- Giles E. Hardingham
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Hilmar Bading
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Im Neuenheimer Feld 364, D-69120 Heidelberg, Germany
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20
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Rocha LL, Lopez-Meraz ML, Niquet J, Wasterlain CG. Do single seizures cause neuronal death in the human hippocampus? Epilepsy Curr 2010; 7:77-81. [PMID: 17520081 PMCID: PMC1874327 DOI: 10.1111/j.1535-7511.2007.00178.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The question of whether repeated single seizures cause neuronal death in the adult human brain is of great clinical importance and might have broad therapeutic implications. Reviewed here are recent studies on the effects of repeated single seizures (in the absence of status epilepticus) on hippocampal volume and on neuronal death markers in blood and in surgically ablated hippocampi.
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Affiliation(s)
- Luisa L Rocha
- Pharmacobiology Department, Center for Research and Advanced Studies, Mexico City, Mexico
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21
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Engel T, Hatazaki S, Tanaka K, Prehn JHM, Henshall DC. Deletion of Puma protects hippocampal neurons in a model of severe status epilepticus. Neuroscience 2010; 168:443-50. [PMID: 20362645 DOI: 10.1016/j.neuroscience.2010.03.057] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 03/23/2010] [Accepted: 03/26/2010] [Indexed: 02/04/2023]
Abstract
Prolonged seizures (status epilepticus) can activate apoptosis-associated signaling pathways. The extent to which such pathways contribute to cell death might depend on the insult intensity, whereby the programmed or apoptotic cell death component is reduced when seizures are more severe or protracted. We recently showed that mice lacking the pro-apoptotic Bcl-2 homology domain 3-only protein Puma (Bbc3) were potently protected against damage caused by status epilepticus. In the present study we examined whether Puma deficiency was protective when the seizure episode was more severe. Intra-amygdala microinjection of 1 microg kainic acid (KA) into C57BL/6 mice triggered status epilepticus that lasted about twice as long as with 0.3 microg KA prior to lorazepam termination. Hippocampal damage was also significantly greater in the higher-dose group. Over 80% of degenerating neurons after seizures were positive for DNA fragmentation assessed by terminal deoxynucleotidyl dUTP nick end labeling (TUNEL). Microscopic analysis of neuronal nuclear morphology in TUNEL-positive cells revealed the proportion displaying large rounded clumps of condensed chromatin was approximately 50% lower in the high-dose versus low-dose KA group. Nevertheless, compared to heterozygous and wild-type mice subject to status epilepticus by high-dose KA, neuronal death was reduced by approximately 50% in the hippocampus of Puma-deficient mice. These data suggest aspects of the apoptotic component of seizure-induced neuronal death are insult duration- or severity-dependent. Moreover, they provide further genetic evidence that seizure-induced neuronal death is preventable by targeting so-called apoptosis-associated signaling pathways and Puma loss likely disrupts caspase-independent or non-apoptotic seizure-induced neuronal death.
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Affiliation(s)
- T Engel
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
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22
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Ordonez AN, Jessick VJ, Clayton CE, Ashley MD, Thompson SJ, Simon RP, Meller R. Rapid ischemic tolerance induced by adenosine preconditioning results in Bcl-2 interacting mediator of cell death (Bim) degradation by the proteasome. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2010; 2:36-44. [PMID: 20957068 PMCID: PMC2955863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 12/21/2009] [Indexed: 05/30/2023]
Abstract
Rapid ischemic tolerance, induced one hour following ischemic preconditioning, is mediated via the ubiq-uitin-proteasome system and the degradation of the pro-apoptotic bcl-2 family protein Bim. Previous studies implicate adenosine A1 receptors in mediating rapid ischemic tolerance. Since the A1 adenosine receptor antagonist DPCPX (10µM) blocked rapid ischemic tolerance in our model, we investigated whether adenosine-mediated preconditioning induces rapid ischemic tolerance via the proteasomal degradation of Bim. Cultured rat cortical neurons were incubated for 60 minutes with either adenosine (1µM) or (-)-N(6)-(2-Phenyl-isopropyl) adenosine (RPIA (1µM)), prior to a harmful dose of ischemia (120min oxygen and glucose deprivation). Preconditioned cells had significantly lower levels of cell death following harmful ischemia when compared to non-preconditioned cells. The proteasome inhibitor MG132 (0.1µM) blocked the protective effect of adenosine pre-conditioning. Immunoblot analysis revealed a decrease in Bim protein levels in adenosine and RPIA preconditioned neurons. Adenosine preconditioning induced neuroprotection and Bim degradation was blocked by the MEK inhibitor UO126 (10µM). Our data suggests that pharmacological preconditioning with adenosine results in proteasomal Bim degradation mediated by p42/44 MAPK. Therefore, pharmacological approaches may be able to induce rapid ischemic tolerance via similar molecular mechanisms as ischemic preconditioning.
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Affiliation(s)
- Andrea Nicole Ordonez
- Robert S. Dow Neurobiology Laboratories, Legacy Research Portland, Oregon 97232, USA
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23
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Abstract
Epilepsy is characterized by both neuronal and astroglial dysfunction. The endogenous anticonvulsant adenosine, the level of which is largely controlled by astrocytes, might provide a crucial link between astrocyte and neuron dysfunction in epilepsy. Here we have studied astrogliosis, a hallmark of the epileptic brain, adenosine dysfunction and the emergence of spontaneous seizures in a comprehensive approach that includes a new mouse model of focal epileptogenesis, mutant mice with altered brain levels of adenosine, and mice lacking adenosine A1 receptors. In wild-type mice, following a focal epileptogenesis-precipitating injury, astrogliosis, upregulation of the adenosine-removing astrocytic enzyme adenosine kinase (ADK), and spontaneous seizures coincide in a spatio-temporally restricted manner. Importantly, these spontaneous seizures are mimicked by untreated transgenic mice that either overexpress ADK in brain or lack A1 receptors. Conversely, mice with reduced ADK in the forebrain do not develop either astrogliosis or spontaneous seizures. Our studies define ADK as a crucial upstream regulator of A1 receptor-mediated modulation of neuronal excitability, and support the ADK hypothesis of epileptogenesis in which upregulation of ADK during astrogliosis provides a crucial link between astrocyte and neuron dysfunction in epilepsy. These findings define ADK as rational target for therapeutic intervention.
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24
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Jimenez-Mateos EM, Henshall DC. Seizure preconditioning and epileptic tolerance: models and mechanisms. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2009; 1:180-191. [PMID: 21383886 PMCID: PMC3047248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 10/28/2009] [Indexed: 05/30/2023]
Abstract
One or more brief seizures can serve to activate endogenous protective programmes which render brain regions temporarily less susceptible to damage following an otherwise harmful episode of status epilepticus (a prolonged seizure). Epileptic tolerance has been demonstrated using a variety of seizure preconditioning paradigms, including electroconvulsive shocks and low doses of excitotoxins such as kainic acid. The cell and molecular mechanisms underlying the protection are not fully understood but proposed mediators include the transcription factor NfκB, altered ion channel expression, upregulation of growth factors and other protective genes, and suppression of pro-apoptotic Bcl-2 family proteins. Application of microarrays to profile the transcriptome of seizure-preconditioning and tolerance has provided further insights, including roles for chromatin remodeling and evidence that preconditioning generates an anti-excitotoxicity phenotype by reprogramming the transcriptional response to status epilepticus. This review summarizes the various animal models of epileptic tolerance, reviews the key effector(s) and the utility of this experimental paradigm for identifying novel targets for neuroprotection and anti-epileptogenesis.
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Affiliation(s)
- Eva M Jimenez-Mateos
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland Dublin, Ireland
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25
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Contrasting patterns of Bim induction and neuroprotection in Bim-deficient mice between hippocampus and neocortex after status epilepticus. Cell Death Differ 2009; 17:459-68. [PMID: 19779495 DOI: 10.1038/cdd.2009.134] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Prolonged seizures (status epilepticus) are associated with brain region-specific regulation of apoptosis-associated signaling pathways. Bcl-2 homology domain 3-only (BH3) members of the Bcl-2 gene family are of interest as possible initiators of mitochondrial dysfunction and release of apoptogenic molecules after seizures. Previously, we showed that expression of the BH3-only protein, Bcl-2 interacting mediator of cell death (Bim), increased in the rat hippocampus but not in the neocortex after focal-onset status epilepticus. In this study, we examined Bim expression in mice and compared seizure damage between wild-type and Bim-deficient animals. Status epilepticus induced by intra-amygdala kainic acid (KA) caused extensive neuronal death within the ipsilateral hippocampal CA3 region. Hippocampal activation of factors associated with transcriptional and posttranslational activation of Bim, such as CHOP and c-Jun NH(2)-terminal kinases, was significant within 1 h. Upregulation of bim mRNA was evident after 2 h and Bim protein increased between 4 and 24 h. Hippocampal CA3 neurodegeneration was reduced in Bim-deficient mice compared with wild-type animals after seizures in vivo, and short interfering RNA molecules targeting bim reduced cell death after KA treatment of hippocampal organotypic cultures. In contrast, neocortical Bim expression declined after status epilepticus, and neocortex damage in Bim-deficient mice was comparable with that in wild-type animals. These results show region-specific differential contributions of Bim to seizure-induced neuronal death.
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26
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Uncoupling of astrogliosis from epileptogenesis in adenosine kinase (ADK) transgenic mice. ACTA ACUST UNITED AC 2009; 4:91-9. [PMID: 19674507 DOI: 10.1017/s1740925x09990135] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The astrocytic enzyme adenosine kinase (ADK) is a key negative regulator of the brain's endogenous anticonvulsant adenosine. Astrogliosis with concomitant upregulation of ADK is part of the epileptogenic cascade and contributes to seizure generation. To molecularly dissect the respective roles of astrogliosis and ADK-expression for seizure generation, we used a transgenic approach to uncouple ADK-expression from astrogliosis: in Adk-tg mice the endogenous Adk-gene was deleted and replaced by a ubiquitously expressed Adk-transgene with novel ectopic expression in pyramidal neurons, resulting in spontaneous seizures. Here, we followed a unique approach to selectively injure the CA3 of these Adk-tg mice. Using this strategy, we had the opportunity to study astrogliosis and epileptogenesis in the absence of the endogenous astrocytic Adk-gene. After triggering epileptogenesis we demonstrate astrogliosis without upregulation of ADK, but lack of seizures, whereas matching wild-type animals developed astrogliosis with upregulation of ADK and spontaneous recurrent seizures. By uncoupling ADK-expression from astrogliosis, we demonstrate that global expression levels of ADK rather than astrogliosis per se contribute to seizure generation.
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27
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Al-Mubarak B, Soriano FX, Hardingham GE. Synaptic NMDAR activity suppresses FOXO1 expression via a cis-acting FOXO binding site: FOXO1 is a FOXO target gene. Channels (Austin) 2009; 3:233-8. [PMID: 19690465 DOI: 10.4161/chan.3.4.9381] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Activation of gene expression by FOXO transcription factors can promote neuronal death in response to loss of trophic support, or oxidative stress. The predominant neuronal FOXOs, FOXO1 and FOXO3, promote the expression of pro-death genes, such as Fas Ligand, Bim and Txnip. Neuroprotective signals initiated by neurotrophins, growth factors or synaptic activity trigger the nuclear export of FOXOs via activation of the PI3K-Akt pathway. One key aspect of FOXO regulation is that once PI3K-Akt activity has returned to baseline, FOXOs return to the nucleus to resume the activation of their target genes. Thus, the FOXO-inhibiting capacity of the PI3K-Akt pathway is thought to be short-lived. However, we show here that synaptic NMDA receptor activity not only triggers FOXO export, but also suppresses the expression of FOXO1. Blockade of PI3K activity prevents both FOXO nuclear export and suppression of FOXO1 expression, raising the possibility that FOXO1 is itself a FOXO target gene. We found that FOXO3, and to a lesser extent FOXO1 transactivates the FOXO1 promoter via a consensus FOXO binding site (GTA AAC AA), and also an upstream sequence resembling a classical FOXO-binding insulin response sequence (CAA AAC AA). Activity-dependent suppression of the FOXO1 promoter is mediated through the proximal GTAAACAA sequence. Similar suppression via this site is observed by activating neuronal IGF-1 receptors by exogenous insulin. Thus, through a feed-forward inhibition mechanism, synaptic activity triggers FOXO export resulting in suppression of FOXO1 expression. These results suggest that FOXO-inactivating signals are likely to result in longer-term inhibition of FOXO target gene expression than previously thought.
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28
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Henshall DC, Dürmüller N, White HS, Williams R, Moser P, Dunleavy M, Silverstone PH. Electroencephalographic and behavioral convulsant effects of hydrobromide and hydrochloride salts of bupropion in conscious rodents. Neuropsychiatr Dis Treat 2009; 5:189-206. [PMID: 19557114 PMCID: PMC2695230 DOI: 10.2147/ndt.s4714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
A novel bromide salt of the antidepressant bupropion (bupropion HBr) has recently been developed and approved for use in the United States. Given previous use of bromides to treat seizures, and that the existing chloride salt of bupropion (HCl) can cause seizures, it is important to determine if the HBr salt may be less likely to cause seizures than the HCl salt. In the present animal studies this was evaluated by means of quantified electroencephalogram (EEG), observation, and the rotarod test in mice and rats. Both bupropion salts were tested at increasing equimolar doses administered intraperitoneally. The results in mice showed that bupropion HCl 125 mg/kg induced a significantly higher ten-fold increase in the mean number of cortical EEG seizures compared to bupropion HBr (7.50 +/- 2.56 vs 0.75 +/- 0.96; p = 0.045), but neither drug caused any brain injuries. In rats bupropion HBr 100 mg/kg induced single EEG seizure activity in the cortical and hippocampal (depth) electrodes and in significantly (p < 0.05) fewer rats (44%) compared to bupropion HCl, which induced 1 to 4 convulsions per rat in all rats (100%) dosed. The total duration of cortical seizures in bupropion HCl-treated rats was significantly longer than the corresponding values obtained in bupropion HBr-treated rats (424.6 seconds vs 124.5 seconds respectively, p < 0.05). Bupropion HCl consistently induced more severe convulsions at each dose level compared to bupropion HBr. Both treatments demonstrated a similar dose-dependent impairment of rotarod performance in mice. In conclusion, these findings suggest that bupropion HBr may have a significantly lower potential to induce seizures in mice and rats, particularly at higher doses, compared to bupropion HCl. Determination of this potential clinical advantage will require human studies. If confirmed by such studies, it is likely that this potential beneficial clinical benefit would be due to the presence of the bromide salt given the long history of the use of bromide to treat seizure disorders.
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Affiliation(s)
- David C Henshall
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Nick Dürmüller
- Porsolt and Partners Pharmacology, Le Genest-Saint-Isle, France
| | | | | | - Paul Moser
- Porsolt and Partners Pharmacology, Le Genest-Saint-Isle, France
| | - Mark Dunleavy
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
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Engel T, Henshall DC. Apoptosis, Bcl-2 family proteins and caspases: the ABCs of seizure-damage and epileptogenesis? INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2009; 1:97-115. [PMID: 21383882 PMCID: PMC3047241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Accepted: 03/20/2009] [Indexed: 05/30/2023]
Abstract
Epilepsy is a common, chronic neurological disorder. It is characterized by recurring seizures which are the result of abnormal electrical activity in the brain. Molecular pathways underlying neuronal death are of importance because prolonged seizure episodes (status epilepticus) cause significant damage to the brain, particularly within vulnerable structures such as the hippocampus. Additionally, repeated seizures over time in patients with poorly controlled epilepsy may cause further cell loss. Biochemical hallmarks associated with apoptosis have been identified in hippocampal and neocortical material removed from patients with pharmacoresistant epilepsy: altered expression of pro-apoptotic Bcl-2 family genes and increased expression of caspases and the presence of their cleaved forms. However, apoptotic cells are rarely detected in such patient material and there is evidence of anti-apoptotic signaling changes in the same tissue, including upregulation of Bcl-2 and Bcl-w. From animal studies there is evidence that both brief and prolonged seizures can cause neuronal apoptosis within the hippocampus. Such cell death can be associated with caspase and pro-apoptotic Bcl-2 family protein activation. Pharmacological or genetic modulations of these pathways can significantly influence DNA fragmentation and neuronal cell death after seizures. Thus, the signaling pathways associated with apoptosis are potentially important for the pathogenesis of epilepsy and may represent targets for neuroprotective and perhaps anti-epileptogenic therapies.
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Affiliation(s)
- Tobias Engel
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland Dublin, Ireland
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30
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Meller R. The role of the ubiquitin proteasome system in ischemia and ischemic tolerance. Neuroscientist 2009; 15:243-60. [PMID: 19181875 DOI: 10.1177/1073858408327809] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Ubiquitin modification targets a protein for rapid degradation by the proteasome. However, polyubiquitination of proteins can result in multiple functions depending on the topology of the ubiquitin chain. Therefore, ubiquitin signaling offers a more complex and versatile biology compared with many other posttranslational modifications. One area of potential for the application of this knowledge is the field of ischemia-induced brain damage, as occurs following a stroke. The ubiquitin proteasome system may exert a dual role on neuronal outcome following ischemia. Harmful ischemia results in an overload of the ubiquitin proteasome system, and blocking the proteasome reduces brain infarction following ischemia. However, the rapid and selective degradation of proteins following brief ischemia results in endogenous protection against ischemia. Therefore, further understanding of the molecular signaling mechanisms that regulate the ubiquitin proteasome system may reveal novel therapeutic targets to reduce brain damage when ischemia is predicted or reduce the activation of the cell death mechanisms and the inflammatory response following stroke. The aim of this review is to discuss some of the recent advances in the understanding of protein ubiquitination and its implications for novel stroke therapies.
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Affiliation(s)
- Robert Meller
- Legacy Clinical Research and Technology Center, Portland, Oregon, USA.
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31
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Cui M, Huang Y, Zhao Y, Zheng J. New insights for FOXO and cell-fate decision in HIV infection and HIV associated neurocognitive disorder. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 665:143-59. [PMID: 20429422 DOI: 10.1007/978-1-4419-1599-3_11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Human immunodeficiency virus Type 1 (HIV-1) infection and associated diseases continue to represent major health problem worldwide. FOXO transcriptional factors play an important role in the regulation of cell apoptosis, cell cycle arrest, stress resistance, metabolism and differentiation. This chapter will discuss the diverse functions of FOXO in different cell types including T-cells, macrophages, neurons and astrocytes within the context of HIV-1 infection. Given the overwhelming evidence that FOXO proteins influence the cell fate of immune cells and involve in the homeostasis of the central nervous system (CNS), we will also discuss the potential role of FOXO factors in HIV-1-associated neurological disorders.
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Affiliation(s)
- Min Cui
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska 68198-5880, USA
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32
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Howlett E, Lin CCJ, Lavery W, Stern M. A PI3-kinase-mediated negative feedback regulates neuronal excitability. PLoS Genet 2008; 4:e1000277. [PMID: 19043547 PMCID: PMC2581892 DOI: 10.1371/journal.pgen.1000277] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Accepted: 10/23/2008] [Indexed: 01/22/2023] Open
Abstract
Use-dependent downregulation of neuronal activity (negative feedback) can act as a homeostatic mechanism to maintain neuronal activity at a particular specified value. Disruption of this negative feedback might lead to neurological pathologies, such as epilepsy, but the precise mechanisms by which this feedback can occur remain incompletely understood. At one glutamatergic synapse, the Drosophila neuromuscular junction, a mutation in the group II metabotropic glutamate receptor gene (DmGluRA) increased motor neuron excitability by disrupting an autocrine, glutamate-mediated negative feedback. We show that DmGluRA mutations increase neuronal excitability by preventing PI3 kinase (PI3K) activation and consequently hyperactivating the transcription factor Foxo. Furthermore, glutamate application increases levels of phospho-Akt, a product of PI3K signaling, within motor nerve terminals in a DmGluRA-dependent manner. Finally, we show that PI3K increases both axon diameter and synapse number via the Tor/S6 kinase pathway, but not Foxo. In humans, PI3K and group II mGluRs are implicated in epilepsy, neurofibromatosis, autism, schizophrenia, and other neurological disorders; however, neither the link between group II mGluRs and PI3K, nor the role of PI3K-dependent regulation of Foxo in the control of neuronal excitability, had been previously reported. Our work suggests that some of the deficits in these neurological disorders might result from disruption of glutamate-mediated homeostasis of neuronal excitability. Use-dependent downregulation of neuronal excitability (negative feedback) can act to maintain neuronal activity within specified levels. Disruption of this homeostasis can lead to neurological disorders, such as epilepsy. Here, we report a novel mechanism for negative feedback control of excitability in the Drosophila larval motor neuron. In this mechanism, activation by the excitatory neurotransmitter glutamate of metabotropic glutamate receptors (mGluRs) located at motor nerve terminals decreases excitability by activating PI3 kinase (PI3K), consequently causing the phosphorylation and inhibition of the transcription factor Foxo. Foxo inhibition, in turn, decreases neuronal excitability. These observations are of interest for two reasons. First, our observation that PI3K activity regulates neuronal excitability is of interest because altered PI3K activity is implicated in a number of neurological disorders, such as autism and neurofibromatosis. Our results raise the possibility that altered excitability might contribute to the deficits in these disorders. Second, our observation that group II metabotropic glutamate receptors (mGluRs) activate PI3K is of interest because group II mGluRs are implicated in epilepsy, anxiety disorders, and schizophrenia. Yet the downstream signaling pathways affected by these treatments are incompletely understood. Our results raise the possibility that the PI3K pathway might be an essential mediator of signalling by these mGluRs.
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Affiliation(s)
- Eric Howlett
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America.
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33
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Salih DAM, Brunet A. FoxO transcription factors in the maintenance of cellular homeostasis during aging. Curr Opin Cell Biol 2008; 20:126-36. [PMID: 18394876 DOI: 10.1016/j.ceb.2008.02.005] [Citation(s) in RCA: 433] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2008] [Revised: 02/14/2008] [Accepted: 02/18/2008] [Indexed: 01/10/2023]
Abstract
The FoxO family of Forkhead transcription factors functions at the interface of tumor suppression, energy metabolism, and organismal longevity. FoxO factors are key downstream targets of insulin, growth factor, nutrient, and oxidative stress stimuli that coordinate a wide range of cellular outputs. FoxO-dependent cellular responses include gluconeogenesis, neuropeptide secretion, atrophy, autophagy, apoptosis, cell cycle arrest, and stress resistance. This review will discuss the roles of the mammalian FoxO family in a variety of cell types, from stem cells to mature cells, in the context of the whole organism. Given the overwhelming evidence that the FoxO factors promote longevity in invertebrates, this review will also discuss the potential role of the FoxO factors in the aging of mammalian organisms.
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Affiliation(s)
- Dervis A M Salih
- Department of Genetics, Stanford University, Stanford, CA 94305, United States
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34
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Li T, Ren G, Lusardi T, Wilz A, Lan JQ, Iwasato T, Itohara S, Simon RP, Boison D. Adenosine kinase is a target for the prediction and prevention of epileptogenesis in mice. J Clin Invest 2008; 118:571-82. [PMID: 18172552 DOI: 10.1172/jci33737] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Accepted: 10/31/2007] [Indexed: 11/17/2022] Open
Abstract
Astrogliosis is a pathological hallmark of the epileptic brain. The identification of mechanisms that link astrogliosis to neuronal dysfunction in epilepsy may provide new avenues for therapeutic intervention. Here we show that astrocyte-expressed adenosine kinase (ADK), a key negative regulator of the brain inhibitory molecule adenosine, is a potential predictor and modulator of epileptogenesis. In a mouse model of focal epileptogenesis, in which astrogliosis is restricted to the CA3 region of the hippocampus, we demonstrate that upregulation of ADK and spontaneous focal electroencephalographic seizures were both restricted to the affected CA3. Furthermore, spontaneous seizures in CA3 were mimicked in transgenic mice by overexpression of ADK in this brain region, implying that overexpression of ADK without astrogliosis is sufficient to cause seizures. Conversely, after pharmacological induction of an otherwise epileptogenesis-precipitating acute brain injury, transgenic mice with reduced forebrain ADK were resistant to subsequent epileptogenesis. Likewise, ADK-deficient ES cell-derived brain implants suppressed astrogliosis, upregulation of ADK, and spontaneous seizures in WT mice when implanted after the epileptogenesis-precipitating brain injury. Our findings suggest that astrocyte-based ADK provides a critical link between astrogliosis and neuronal dysfunction in epilepsy.
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Affiliation(s)
- Tianfu Li
- Robert S. Dow Neurobiology Laboratories, Legacy Clinical Research, Portland, Oregon 97232, USA
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35
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Engel T, Murphy BM, Schindler CK, Henshall DC. Elevated p53 and lower MDM2 expression in hippocampus from patients with intractable temporal lobe epilepsy. Epilepsy Res 2007; 77:151-6. [PMID: 17942278 DOI: 10.1016/j.eplepsyres.2007.09.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 08/31/2007] [Accepted: 09/03/2007] [Indexed: 10/22/2022]
Abstract
Recent studies of resected hippocampus from patients with intractable temporal lobe epilepsy (TLE) have yielded biochemical evidence of signalling pathways associated with apoptosis. The tumor suppressor and transcription factor p53 regulates expression of several genes involved in apoptosis. Cellular levels of p53 are regulated in part by murine double minute 2 (MDM2) via ubiquitination and degradation through the proteasome. Presently, we compared expression of p53 and MDM2 in resected hippocampus from patients with intractable TLE to matched autopsy control samples. Western blotting detected significantly higher levels of p53 within TLE samples than controls. MDM2 levels were significantly lower in patient brain and its cleaved form was more abundant. Immunohistochemistry localized elevated p53 to a mainly nuclear distribution in neurons and glia in sections from TLE hippocampus. These data extend other findings on altered expression of genes regulating cell death and survival decisions in human intractable TLE.
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Affiliation(s)
- Tobias Engel
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
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36
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Hatazaki S, Bellver-Estelles C, Jimenez-Mateos EM, Meller R, Bonner C, Murphy N, Matsushima S, Taki W, Prehn JHM, Simon RP, Henshall DC. Microarray profile of seizure damage-refractory hippocampal CA3 in a mouse model of epileptic preconditioning. Neuroscience 2007; 150:467-77. [PMID: 17935890 DOI: 10.1016/j.neuroscience.2007.09.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 08/21/2007] [Accepted: 09/11/2007] [Indexed: 12/15/2022]
Abstract
A neuroprotected state can be acquired by preconditioning brain with a stimulus that is subthreshold for damage (tolerance). Acquisition of tolerance involves coordinate, bi-directional changes to gene expression levels and the re-programmed phenotype is determined by the preconditioning stimulus. While best studied in ischemic brain there is evidence brief seizures can confer tolerance against prolonged seizures (status epilepticus). Presently, we developed a model of epileptic preconditioning in mice and used microarrays to gain insight into the transcriptional phenotype within the target hippocampus at the time tolerance had been acquired. Epileptic tolerance was induced by an episode of non-damaging seizures in adult C57Bl/6 mice using a systemic injection of kainic acid. Neuron and DNA damage-positive cell counts 24 h after status epilepticus induced by intraamygdala microinjection of kainic acid revealed preconditioning given 24 h prior reduced CA3 neuronal death by approximately 45% compared with non-tolerant seizure mice. Microarray analysis of over 39,000 transcripts (Affymetrix 430 2.0 chip) from microdissected CA3 subfields was undertaken at the point at which tolerance was acquired. Results revealed a unique profile of small numbers of equivalently up- and down-regulated genes with biological functions that included transport and localization, ubiquitin metabolism, apoptosis and cell cycle control. Select microarray findings were validated post hoc by real-time polymerase chain reaction and Western blotting. The present study defines a paradigm for inducing epileptic preconditioning in mice and first insight into the global transcriptome of the seizure-damage refractory brain.
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Affiliation(s)
- S Hatazaki
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
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37
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Murphy B, Dunleavy M, Shinoda S, Schindler C, Meller R, Bellver-Estelles C, Hatazaki S, Dicker P, Yamamoto A, Koegel I, Chu X, Wang W, Xiong Z, Prehn J, Simon R, Henshall D. Bcl-w protects hippocampus during experimental status epilepticus. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:1258-68. [PMID: 17702891 PMCID: PMC1988875 DOI: 10.2353/ajpath.2007.070269] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Experimentally evoked seizures can activate the intrinsic mitochondrial cell death pathway, components of which are modulated in the hippocampus of patients with temporal lobe epilepsy. Bcl-2 family proteins are critical regulators of mitochondrial dysfunction, but their significance in this setting remains primarily untested. Presently, we investigated the mitochondrial pathway and role of anti-apoptotic Bcl-2 proteins using a mouse model of seizure-induced neuronal death. Status epilepticus was evoked in mice by intra-amygdala kainic acid, causing cytochrome c release, processing of caspases 9 and 7, and death of ipsilateral hippocampal pyramidal neurons. Seizures caused a rapid decline in hippocampal Bcl-w levels not seen for either Bcl-2 or Bcl-xl. To test whether endogenous Bcl-w was functionally significant for neuronal survival, we investigated hippocampal injury after seizures in Bcl-w-deficient mice. Seizures induced significantly more hippocampal CA3 neuronal loss and DNA fragmentation in Bcl-w-deficient mice compared with wild-type mice. Quantitative electroencephalography analysis also revealed that Bcl-w-deficient mice display a neurophysiological phenotype whereby there was earlier polyspike seizure onset. Finally, we detected higher levels of Bcl-w in hippocampus from temporal lobe epilepsy patients compared with autopsy controls. These data identify Bcl-w as an endogenous neuroprotectant that may have seizure-suppressive functions.
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Affiliation(s)
- Brona Murphy
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
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38
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Ren G, Li T, Lan JQ, Wilz A, Simon RP, Boison D. Lentiviral RNAi-induced downregulation of adenosine kinase in human mesenchymal stem cell grafts: a novel perspective for seizure control. Exp Neurol 2007; 208:26-37. [PMID: 17716659 PMCID: PMC2205528 DOI: 10.1016/j.expneurol.2007.07.016] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 07/11/2007] [Accepted: 07/20/2007] [Indexed: 12/14/2022]
Abstract
Cell therapies based on focal delivery of the inhibitory neuromodulator adenosine were previously shown to provide potent seizure suppression in animal models of epilepsy. However, hitherto used therapeutic cells were derived from rodents and thus not suitable for clinical applications. Autologous patient-derived adenosine-releasing cell implants would constitute a major therapeutic advance to avoid both xenotransplantation and immunosuppression. Here we describe a novel approach based on lentiviral RNAi mediated downregulation of adenosine kinase (ADK), the major adenosine-removing enzyme, in human mesenchymal stem cells (hMSCs), which would be compatible with autologous cell grafting in patients. Following lentiviral transduction of hMSCs with anti-ADK miRNA expression cassettes we demonstrate up to 80% downregulation of ADK and a concentration of 8.5 ng adenosine per ml of medium after incubating 10(5) cells for 8 h. hMSCs with a knockdown of ADK or cells expressing a scrambled control sequence were transplanted into hippocampi of mice 1 week prior to the intraamygdaloid injection of kainic acid (KA). While mice with control implants expressing a scrambled miRNA sequence or sham treated control animals were characterized by KA-induced status epilepticus and subsequent CA3 neuronal cell loss, animals with therapeutic ADK knockdown implants displayed a 35% reduction in seizure duration and 65% reduction in CA3 neuronal cell loss, when analyzed 24 h after KA-injection. We conclude that lentiviral expression of anti-ADK miRNA constitutes a versatile tool to generate therapeutically effective adenosine releasing hMSCs, thus representing a model system to generate patient identical autologous adult stem cell grafts.
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Affiliation(s)
| | | | | | | | | | - Detlev Boison
- Corresponding author: Detlev Boison, Robert S. Dow Neurobiology Laboratories, Legacy Research, 1225 NE 2 Avenue, Portland, OR 97232, USA, Tel: +1 (503) 413-1754; Fax: +1 (503) 413-5465, E-mail:
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39
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Yao M, Nguyen TVV, Pike CJ. Estrogen regulates Bcl-w and Bim expression: role in protection against beta-amyloid peptide-induced neuronal death. J Neurosci 2007; 27:1422-33. [PMID: 17287517 PMCID: PMC6673600 DOI: 10.1523/jneurosci.2382-06.2007] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Estrogen is neuroprotective against a variety of insults, including beta-amyloid peptide (Abeta); however, the underlying mechanism(s) is not fully understood. Here, we report that 17beta-estradiol (E2) selectively regulates neuronal expression of the Bcl-2 family (bcl-2, bcl-x, bcl-w, bax, bak, bad, bik, bnip3, bid, and bim). In primary cerebrocortical neuron cultures under basal conditions, we observe that E2 upregulates expression of antiapoptotic Bcl-w and downregulates expression of proapoptotic Bim in an estrogen receptor (ER)-dependent manner. In the presence of toxic levels of Abeta, we observe that E2 attenuates indices of neuronal apoptosis: c-Jun N-terminal kinase (JNK)-dependent downregulation of Bcl-w and upregulation of Bim, mitochondrial release of cytochrome c and Smac, and cell death. These neuroprotective effects of E2 against Abeta-induced apoptosis are mimicked by the JNK inhibitor SP600125 (anthra[1,9-cd]pyrazol-6(2H)-one). In addition, E2 attenuates Abeta-induced JNK phosphorylation in an ER-dependent manner, but does not affect basal levels of JNK phosphorylation. These results suggest that E2 may reduce Abeta-induced neuronal apoptosis at least in part by two complementary pathways: (1) ER-dependent, JNK-independent upregulation of Bcl-w and downregulation of Bim under basal conditions, and (2) ER-dependent inhibition of Abeta-induced JNK activation and subsequent JNK-dependent downregulation of Bcl-w and upregulation of Bim, resulting in mitochondrial release of cytochrome c and Smac and eventual cell death. These data provide new understanding into the mechanisms contributing to estrogen neuroprotection, a neural function with potential therapeutic relevance to Alzheimer's disease.
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Affiliation(s)
- Mingzhong Yao
- Davis School of Gerontology, University of Southern California, Los Angeles, California 90089
| | - Thuy-Vi V. Nguyen
- Davis School of Gerontology, University of Southern California, Los Angeles, California 90089
| | - Christian J. Pike
- Davis School of Gerontology, University of Southern California, Los Angeles, California 90089
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40
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Greene LA, Liu DX, Troy CM, Biswas SC. Cell cycle molecules define a pathway required for neuron death in development and disease. Biochim Biophys Acta Mol Basis Dis 2006; 1772:392-401. [PMID: 17229557 PMCID: PMC1885990 DOI: 10.1016/j.bbadis.2006.12.003] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Revised: 12/07/2006] [Accepted: 12/11/2006] [Indexed: 12/26/2022]
Abstract
We review here evidence defining a molecular pathway that includes cell cycle-related molecules and that appears to play a required role in neuron death during normal development as well as in disease and trauma. The pathway starts with inappropriate activation of cyclin dependent kinase 4 (Cdk4) in neurons which leads to hyper-phosphorylation of the pRb family member p130. This in turn results in dissociation of p130 and its associated chromatin modifiers Suv39H1 and HDAC1 from the transcription factor E2F4. Dissociation of this complex results in de-repression of genes with E2F binding sites including those encoding the transcription factors B- and C-Myb. Once elevated in neurons, B- and C-Myb proteins bind to the promoter for the pro-apoptotic BH3-only protein Bim and promote its induction. Bim then interacts with the core cellular apoptotic machinery, leading to caspase activation and apoptotic death. This pathway is supported by a variety of observations and experimental findings that implicate it as a required element for neuron loss in development and in many nervous system traumas and disorders. The components of this pathway appear to represent potential therapeutic targets for prevention of disease-associated neuron death.
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Affiliation(s)
- Lloyd A Greene
- Department of Pathology and Center for Neurobiology and Behavior, Columbia University College of Physicians and Surgeons, 630 W. 168th Street, New York, NY 10032, USA.
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41
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Meller R, Clayton C, Torrey DJ, Schindler CK, Lan JQ, Cameron JA, Chu XP, Xiong ZG, Simon RP, Henshall DC. Activation of the caspase 8 pathway mediates seizure-induced cell death in cultured hippocampal neurons. Epilepsy Res 2006; 70:3-14. [PMID: 16542823 PMCID: PMC1618926 DOI: 10.1016/j.eplepsyres.2006.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Revised: 01/06/2006] [Accepted: 02/03/2006] [Indexed: 11/21/2022]
Abstract
In response to harmful stresses, cells induce programmed cell death (PCD) or apoptosis. Seizures can induce neural damage and activate biochemical pathways associated with PCD. Since seizures trigger intracellular calcium overload, it has been presumed that the intrinsic cell death pathway mediated by mitochondrial dysfunction would modulate cell death following seizures. However, previous work suggests that the extrinsic cell death pathway may initiate the damage program. Here we investigate intrinsic versus extrinsic cell death pathway activation using caspase cleavage as a marker for activation of these pathways in a rat in vitro model of seizures. Hippocampal cells, chronically treated with kynurenic acid, had kynurenic acid withdrawn to induce seizure-like activity for 40 min. Subjecting rat hippocampal cultures to seizures increased cell death and apoptosis-like DNA fragmentation using TUNEL staining. Seizure-induced cell death was blocked by both MK801 (10 microM) and CNQX (40 microM), which suggests multiple glutamate receptors regulate seizure-induced cell death. Cleavage of the initiator caspases, caspase 8 and 12 were increased 4h following seizure, and cleavage of the quintessential executioner caspase, caspase 3 was increased 4h following seizure. In contrast, caspase 9 cleavage only increased 24h following seizure. Using an affinity labeling approach to trap activated caspases in situ, we show that caspase 8 is the apical caspase activated following seizures. Finally, we show that the caspase 8 inhibitor Ac-IETD-CHO was more effective at blocking seizure-induced cell death than the caspase 9 inhibitor Ac-LEHD-CHO. Taken together, our data suggests the extrinsic cell death pathway-associated caspase 8 is activated following seizures in vitro.
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Affiliation(s)
- R Meller
- Robert S. Dow Neurobiology Laboratories, Legacy Research, Portland, OR 97232, USA.
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42
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Meller R, Cameron JA, Torrey DJ, Clayton CE, Ordonez AN, Henshall DC, Minami M, Schindler CK, Saugstad JA, Simon RP. Rapid degradation of Bim by the ubiquitin-proteasome pathway mediates short-term ischemic tolerance in cultured neurons. J Biol Chem 2006; 281:7429-36. [PMID: 16431916 PMCID: PMC1400596 DOI: 10.1074/jbc.m512138200] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
A previous exposure to a non-harmful ischemic insult (preconditioning) protects the brain against subsequent harmful ischemia (ischemic tolerance). In contrast to delayed gene-mediated ischemic tolerance, little is known about the molecular mechanisms that regulate rapid ischemic tolerance, which occurs within 1 h following preconditioning. Here we have investigated the degradation of the pro-apoptotic Bcl-2 family member Bim as a mechanism of rapid ischemic tolerance. Bim protein levels were reduced 1 h following preconditioning and occurred concurrent with an increase in Bim ubiquitination. Ubiquitinated proteins are degraded by the proteasome, and inhibition of the proteasome with MG132 (a proteasome inhibitor) prevented Bim degradation and blocked rapid ischemic tolerance. Inhibition of p42/p44 mitogen-activated protein kinase activation by U0126 reduced Bim ubiquitination and Bim degradation and blocked rapid ischemic tolerance. Finally, inhibition of Bim expression using antisense oligonucleotides also reduced cell death following ischemic challenge. Our results suggest that following preconditioning ischemia, Bim is rapidly degraded by the ubiquitin-proteasome system, resulting in rapid ischemic tolerance. This suggests that the rapid degradation of cell death-promoting proteins by the ubiquitin-proteasome pathway may represent a novel therapeutic strategy to reduce cell damage following neuropathological insults, e.g. stroke.
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Affiliation(s)
- Robert Meller
- Robert S. Dow Neurobiology Laboratories, Legacy Clinical Research and Technology Center, 1225 NE 2nd Avenue, Portland, OR 97232, USA.
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43
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Abstract
At present there is a poor understanding of the events that lead up to neuronal apoptosis that occurs in neurodegenerative diseases and following acute ischemic episodes. Apoptosis is critical for the elimination of unwanted neurons within the developing nervous system. The Bcl-2 family of proteins contains pro- and anti-apoptotic proteins that regulate the mitochondrial pathway of apoptosis. There is increasing interest in a subfamily of the Bcl-2 family, the BH3-only proteins, and their pro-apoptotic effects within neurons. Recently ischemic and seizure-induced neuronal injury has been shown to result in the activation of the BH3-only protein, Bid. This protein is cleaved and the truncated protein (tBid) translocates to the mitochondria. The translocation of tBid to the mitochondria is associated with the activation of outer mitochondrial membrane proteins Bax/Bak and the release of cytochrome C from the mitochondria. ER stress also has been implicated as a factor for the induction of apoptosis in ischemic neuronal injury. The induction of ER stress in hippocampal neurons has been shown to activate expression of bb3/PUMA, a member of the BH3-only gene family. Activation of PUMA is associated with the activation and clustering of the pro-apoptotic Bcl-2 family member Bax and the loss of cytochrome C from the mitochondria.
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Affiliation(s)
- Manus W Ward
- Department of Physiology, Royal College of Surgeons, 123 St Stephen's Green, Dublin 2, Ireland
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44
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Niquet J, Wasterlain CG. Bim, Bad, and Bax: a deadly combination in epileptic seizures. J Clin Invest 2004; 113:960-2. [PMID: 15057301 PMCID: PMC379331 DOI: 10.1172/jci21478] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Several Bcl-2 family members, including Bim, may contribute to programmed cell death by inducing mitochondrial cytochrome c release, which activates caspase-9 and then caspase-3, the "executioner" of the cell. In this issue of the JCI, Shinoda and collaborators show the key role of Bim in epileptic seizure-induced neuronal injury and identify the contribution of transcription factors responsible for seizure-induced Bim upregulation.
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Affiliation(s)
- Jerome Niquet
- Epilepsy Research Laboratory, Veteran's Administration Greater Los Angeles Healthcare System, West Los Angeles, California 90073, USA.
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