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Ravizza T, Scheper M, Di Sapia R, Gorter J, Aronica E, Vezzani A. mTOR and neuroinflammation in epilepsy: implications for disease progression and treatment. Nat Rev Neurosci 2024; 25:334-350. [PMID: 38531962 DOI: 10.1038/s41583-024-00805-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2024] [Indexed: 03/28/2024]
Abstract
Epilepsy remains a major health concern as anti-seizure medications frequently fail, and there is currently no treatment to stop or prevent epileptogenesis, the process underlying the onset and progression of epilepsy. The identification of the pathological processes underlying epileptogenesis is instrumental to the development of drugs that may prevent the generation of seizures or control pharmaco-resistant seizures, which affect about 30% of patients. mTOR signalling and neuroinflammation have been recognized as critical pathways that are activated in brain cells in epilepsy. They represent a potential node of biological convergence in structural epilepsies with either a genetic or an acquired aetiology. Interventional studies in animal models and clinical studies give strong support to the involvement of each pathway in epilepsy. In this Review, we focus on available knowledge about the pathophysiological features of mTOR signalling and the neuroinflammatory brain response, and their interactions, in epilepsy. We discuss mitigation strategies for each pathway that display therapeutic effects in experimental and clinical epilepsy. A deeper understanding of these interconnected molecular cascades could enhance our strategies for managing epilepsy. This could pave the way for new treatments to fill the gaps in the development of preventative or disease-modifying drugs, thus overcoming the limitations of current symptomatic medications.
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Affiliation(s)
- Teresa Ravizza
- Department of Acute Brain and Cardiovascular Injury, Mario Negri Institute for Pharmacological Research IRCCS, Milano, Italy
| | - Mirte Scheper
- Department of (Neuro)Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Rossella Di Sapia
- Department of Acute Brain and Cardiovascular Injury, Mario Negri Institute for Pharmacological Research IRCCS, Milano, Italy
| | - Jan Gorter
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, The Netherlands
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands.
| | - Annamaria Vezzani
- Department of Acute Brain and Cardiovascular Injury, Mario Negri Institute for Pharmacological Research IRCCS, Milano, Italy.
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Aronica E, Ciusani E, Coppola A, Costa C, Russo E, Salmaggi A, Perversi F, Maschio M. Epilepsy and brain tumors: Two sides of the same coin. J Neurol Sci 2023; 446:120584. [PMID: 36842341 DOI: 10.1016/j.jns.2023.120584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 02/06/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023]
Abstract
Epilepsy is the most common symptom in patients with brain tumors. The shared genetic, molecular, and cellular mechanisms between tumorigenesis and epileptogenesis represent 'two sides of the same coin'. These include augmented neuronal excitatory transmission, impaired inhibitory transmission, genetic mutations in the BRAF, IDH, and PIK3CA genes, inflammation, hemodynamic impairments, and astrocyte dysfunction, which are still largely unknown. Low-grade developmental brain tumors are those most commonly associated with epilepsy. Given this strict relationship, drugs able to target both seizures and tumors would be of extreme clinical usefulness. In this regard, anti-seizure medications (ASMs) are optimal candidates as they have well-characterized effects and safety profiles, do not increase the risk of developing cancer, and already offer well-defined seizure control. The most important ASMs showing preclinical and clinical efficacy are brivaracetam, lacosamide, perampanel, and especially valproic acid and levetiracetam. However, the data quality is low or limited to preclinical studies, and results are sometimes conflicting. Future trials with a prospective, randomized, and controlled design accounting for different prognostic factors will help clarify the role of these ASMs and the clinical setting in which they might be used. In conclusion, brain tumor-related epilepsies are clear examples of how close, multidisciplinary collaborations among investigators with different expertise are warranted for pursuing scientific knowledge and, more importantly, for the well-being of patients needing targeted and effective therapies.
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Affiliation(s)
- Eleonora Aronica
- Amsterdam UMC location the University of Amsterdam, Department of (Neuro)Pathology Amsterdam Neuroscience, Meibergdreef 9, Amsterdam, the Netherlands; Stichting Epilepsie Instellingen Nederland, Heemstede, The Netherlands
| | - Emilio Ciusani
- Department of Research and Technology, Fondazione IRCCS Istituto Neurologico C. Besta Milan, Italy
| | - Antonietta Coppola
- Department of Neuroscience, Odontostomatology and Reproductive Sciences, Federico II University of Naples, Naples, Italy
| | - Cinzia Costa
- Neurology Clinic, Department of Medicine and Surgery, University of Perugia, S. Maria della Misericordia Hospital, Perugia, Italy
| | - Emilio Russo
- Science of Health Department, Magna Grecia University, Catanzaro, Italy
| | - Andrea Salmaggi
- Department of Neurosciences, Unit of Neurology, Presidio A. Manzoni, ASST Lecco, Italy
| | | | - Marta Maschio
- Center for tumor-related epilepsy, UOSD Neurooncology, IRCCS Regina Elena National Cancer Institute, Rome, Italy.
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de Almeida AA, Gomes da Silva S, Lopim GM, Vannucci Campos D, Fernandes J, Cabral FR, Arida RM. Physical exercise alters the activation of downstream proteins related to BDNF-TrkB signaling in male Wistar rats with epilepsy. J Neurosci Res 2017; 96:911-920. [DOI: 10.1002/jnr.24196] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/16/2017] [Accepted: 10/17/2017] [Indexed: 12/17/2022]
Affiliation(s)
- Alexandre Aparecido de Almeida
- Departamento de Fisiologia; Universidade Federal de São Paulo; São Paulo Brazil
- Instituto Federal Goiano (IF Goiano), Campus Ceres; Ceres Brazil
| | - Sérgio Gomes da Silva
- Hospital Israelita Albert Einstein; São Paulo Brazil
- Universidade de Mogi das Cruzes; Mogi das Cruzes Brazil
| | | | | | - Jansen Fernandes
- Departamento de Fisiologia; Universidade Federal de São Paulo; São Paulo Brazil
| | - Francisco Romero Cabral
- Hospital Israelita Albert Einstein; São Paulo Brazil
- Faculdade de Ciências Médicas da Santa Casa de São Paulo; São Paulo Brazil
| | - Ricardo Mario Arida
- Departamento de Fisiologia; Universidade Federal de São Paulo; São Paulo Brazil
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Reynolds JP, Jimenez-Mateos EM, Cao L, Bian F, Alves M, Miller-Delaney SF, Zhou A, Henshall DC. Proteomic Analysis After Status Epilepticus Identifies UCHL1 as Protective Against Hippocampal Injury. Neurochem Res 2017; 42:2033-2054. [PMID: 28397067 DOI: 10.1007/s11064-017-2260-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 04/02/2017] [Accepted: 04/03/2017] [Indexed: 12/27/2022]
Abstract
Brief, non-harmful seizures (preconditioning) can temporarily protect the brain against prolonged, otherwise injurious seizures. Following focal-onset status epilepticus (SE) in preconditioned (tolerance) and sham-preconditioned (injury) mice, we screened for protein changes using a proteomic approach and identified several putative candidates of epileptic tolerance. Among SE-induced changes to both proteomic screens, proteins clustered in key regulatory pathways, including protein trafficking and cytoskeletal regulation. Downregulation of one such protein, ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1), was unique to injury and not evident in tolerance. UCHL1 inhibition decreased hippocampal ubiquitin, disrupted UPS function, interfered with seizure termination and exacerbated seizure-induced cell death. Though UCHL1 transcription was maintained after SE, we observed downregulation of the pro-translational antisense Uchl1 (AsUchl1) and confirmed that both AsUchl1 and rapamycin can increase UCHL1 expression in vivo. These data indicate that the post-transcriptional loss of UCHL1 following SE is deleterious to neuronal survival and may contribute to hyperexcitability, and are suggestive of a novel modality of rapamycin therapy.
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Affiliation(s)
- James P Reynolds
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
| | - Eva M Jimenez-Mateos
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
| | - Li Cao
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, 30310, USA
| | - Fang Bian
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, 30310, USA
| | - Mariana Alves
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
| | - Suzanne F Miller-Delaney
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
| | - An Zhou
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, 30310, USA
| | - David C Henshall
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland.
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Chen LL, Wu ML, Zhu F, Kai JJ, Dong JY, Wu XM, Zeng LH. Neural Progenitor Cells Rptor Ablation Impairs Development but Benefits to Seizure-Induced Behavioral Abnormalities. CNS Neurosci Ther 2016; 22:1000-1008. [PMID: 27677248 DOI: 10.1111/cns.12607] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 08/17/2016] [Accepted: 08/18/2016] [Indexed: 01/21/2023] Open
Abstract
AIMS Previous study suggests that mTOR signaling pathway may play an important role in epileptogenesis. The present work was designed to explore the contribution of raptor protein to the development of epilepsy and comorbidities. METHODS Mice with conditional knockout of raptor protein were generated by cross-bred Rptorflox/flox mice with nestin-CRE mice. The expression of raptor protein was analyzed by Western blotting in brain tissue samples. Neuronal death and mossy fiber sprouting were detected by FJB staining and Timm staining, respectively. Spontaneous seizures were recorded by EEG-video system. Morris water maze, open field test, and excitability test were used to study the behaviors of Rptor CKO mice. RESULTS As the consequence of deleting Rptor, downstream proteins of raptor in mTORC1 signaling were partly blocked. Rptor CKO mice exhibited decrease in body and brain weight under 7 weeks old and accordingly, cortical layer thickness. After kainic acid (KA)-induced status epilepticus, overactivation of mTORC1 signaling was markedly reversed in Rptor CKO mice. Although low frequency of spontaneous seizure and seldom neuronal cell death were observed in both Rptor CKO and control littermates, KA seizure-induced mossy fiber spouting were attenuated in Rptor CKO mice. Additionally, cognitive-deficit and anxiety-like behavior after KA-induced seizures were partly reversed in Rptor CKO mice. CONCLUSION Loss of the Rptor gene in mice neural progenitor cells affects normal development in young age and may contribute to alleviate KA seizure-induced behavioral abnormalities, suggesting that raptor protein plays an important role in seizure comorbidities.
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Affiliation(s)
- Ling-Lin Chen
- Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Mei-Ling Wu
- Department of Pharmacy, School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Feng Zhu
- Department of Pharmacy, School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Jie-Jing Kai
- Department of Pharmacy, School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Jing-Yin Dong
- Department of Pharmacy, School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Xi-Mei Wu
- Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ling-Hui Zeng
- Department of Pharmacy, School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
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Citraro R, Leo A, Constanti A, Russo E, De Sarro G. mTOR pathway inhibition as a new therapeutic strategy in epilepsy and epileptogenesis. Pharmacol Res 2016; 107:333-343. [DOI: 10.1016/j.phrs.2016.03.039] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/23/2016] [Accepted: 03/31/2016] [Indexed: 12/24/2022]
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Phillips-Farfán BV, Rubio Osornio MDC, Custodio Ramírez V, Paz Tres C, Carvajal Aguilera KG. Caloric restriction protects against electrical kindling of the amygdala by inhibiting the mTOR signaling pathway. Front Cell Neurosci 2015; 9:90. [PMID: 25814935 PMCID: PMC4356078 DOI: 10.3389/fncel.2015.00090] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 02/26/2015] [Indexed: 11/26/2022] Open
Abstract
Caloric restriction (CR) has been shown to possess antiepileptic properties; however its mechanism of action is poorly understood. CR might inhibit the activity of the mammalian or mechanistic target of rapamycin (mTOR) signaling cascade, which seems to participate crucially in the generation of epilepsy. Thus, we investigated the effect of CR on the mTOR pathway and whether CR modified epilepsy generation due to electrical amygdala kindling. The former was studied by analyzing the phosphorylation of adenosine monophosphate-activated protein kinase, protein kinase B and the ribosomal protein S6. The mTOR cascade is regulated by energy and by insulin levels, both of which may be changed by CR; thus we investigated if CR altered the levels of energy substrates in the blood or the level of insulin in plasma. Finally, we studied if CR modified the expression of genes that encode proteins participating in the mTOR pathway. CR increased the after-discharge threshold and tended to reduce the after-discharge duration, indicating an anti-convulsive action. CR diminished the phosphorylation of protein kinase B and ribosomal protein S6, suggesting an inhibition of the mTOR cascade. However, CR did not change glucose, β-hydroxybutyrate or insulin levels; thus the effects of CR were independent from them. Interestingly, CR also did not modify the expression of any investigated gene. The results suggest that the anti-epileptic effect of CR may be partly due to inhibition of the mTOR pathway.
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Affiliation(s)
| | | | | | - Carlos Paz Tres
- Laboratorio de Neurofisiología, Instituto Nacional de Neurología y Neurocirugía México City, México
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Bejarano E, Rodríguez-Navarro JA. Autophagy and amino acid metabolism in the brain: implications for epilepsy. Amino Acids 2014; 47:2113-26. [DOI: 10.1007/s00726-014-1822-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 07/31/2014] [Indexed: 12/31/2022]
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What are the arguments for and against rational therapy for epilepsy? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 813:295-308. [PMID: 25012386 DOI: 10.1007/978-94-017-8914-1_24] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Although more than a dozen new anti-seizure drugs (ASDs) have entered the market since 1993, a substantial proportion of patients (~30 %) remain refractory to current treatments. Thus, a concerted effort to identify and develop new therapies that will help these patients continues. Until this effort succeeds, it is reasonable to re-assess the use of currently available therapies and to consider how these therapies might be utilized in a more efficacious manner. This applies to the selection of monotherapies in newly-diagnosed epilepsy, but perhaps, more importantly, to the choice of combination treatments in otherwise drug-refractory epilepsy. Rational polytherapy is a concept that is predicated on the combination of drugs with complementary mechanisms of action (MoAs) that work synergistically to maximize efficacy and minimize the potential for adverse events. Furthermore, rational polytherapy requires a detailed understanding of the MoA subclasses amongst available ASDs and an appreciation of the empirical evidence that supports the use of specific combinations. The majority of ASDs can be loosely categorized into those that target neurotransmission and network hyperexcitability, modulate intrinsic neuronal properties through ion channels, or possess broad-spectrum efficacy as a result of multiple mechanisms. Within each of these categories, there are discrete pharmacological profiles that differentiate individual ASDs. This chapter will consider how knowledge of MoA can help guide therapy in a rational manner, both in the selection of monotherapies for specific seizure types and syndromes, but also in the choice of drug combinations for patients whose epilepsy is not optimally controlled with a single ASD.
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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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Gene expression profiling of a hypoxic seizure model of epilepsy suggests a role for mTOR and Wnt signaling in epileptogenesis. PLoS One 2013; 8:e74428. [PMID: 24086344 PMCID: PMC3785482 DOI: 10.1371/journal.pone.0074428] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 08/01/2013] [Indexed: 01/09/2023] Open
Abstract
Microarray profiling was used to investigate gene expression in the hypoxic seizure model of acquired epilepsy in the rat, with the aim of characterizing functional pathways which are persistently activated or repressed during epileptogenesis. Hippocampal and cortical tissues were transcriptionally profiled over a one week period following an initial series of seizures induced by mild hypoxia at post-natal day 10 (P10), and the gene expression data was then analyzed with a focus on gene set enrichment analysis, an approach which emphasizes regulation of entire pathways rather than of individual genes. Animals were subjected to one of three conditions: a control with no hypoxia, hypoxic seizures, and hypoxic seizures followed by treatment with the AMPAR antagonist NBQX, a compound currently proposed to be a modulator of epileptogenesis. While temporal gene expression in the control samples was found to be consistent with known processes of neuronal maturation in the rat for the given time window, the hypoxic seizure response was found to be enriched for components of the PI3K/mTOR and Wnt signaling pathways, alongside gene sets representative of glutamatergic, synaptic and axonal processes, perhaps regulated as a downstream consequence of activation of these pathways. Wnt signaling components were also found enriched in the more specifically epileptogenic NBQX-responsive gene set. While activation of the mTOR pathway is consistent with its known role in epileptogenesis and strengthens the case for mTOR or PI3K pathway inhibitors as potential anti-epileptogenic drugs, investigation of the role of Wnt signaling and the effect of appropriate inhibitors might offer a parallel avenue of research toward anti-epileptogenic treatment of epilepsy.
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Meng XF, Yu JT, Song JH, Chi S, Tan L. Role of the mTOR signaling pathway in epilepsy. J Neurol Sci 2013; 332:4-15. [PMID: 23773767 DOI: 10.1016/j.jns.2013.05.029] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 05/19/2013] [Accepted: 05/23/2013] [Indexed: 11/19/2022]
Abstract
Epilepsy, a common neurological disorder and cause of significant morbidity and mortality, places an enormous burden on the individual and society. Presently, most drugs for epilepsy primarily suppress seizures as symptomatic therapies but do not possess actual antiepileptogenic or disease-modifying properties. The mTOR (mammalian target of rapamycin) signaling pathway is involved in major multiple cellular functions, including protein synthesis, cell growth and proliferation and synaptic plasticity, which may influence neuronal excitability and be responsible for epileptogenesis. Intriguing findings of the frequent hyperactivation of mTOR signaling in epilepsy make it a potential mechanism in the pathogenesis as well as an attractive target for the therapeutic intervention, and have driven the significant ongoing efforts to pharmacologically target this pathway. This review explores the relevance of the mTOR pathway to epileptogenesis and its potential as a therapeutic target in epilepsy treatment by presenting the current results on mTOR inhibitors, in particular, rapamycin, in animal models of diverse types of epilepsy. Limited clinical studies in human epilepsy, some paradoxical experimental data and outstanding questions have also been discussed.
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Affiliation(s)
- Xiang-Fei Meng
- Department of Neurology, School of Medicine, Qingdao Municipal Hospital, Qingdao University, China
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Macias M, Blazejczyk M, Kazmierska P, Caban B, Skalecka A, Tarkowski B, Rodo A, Konopacki J, Jaworski J. Spatiotemporal characterization of mTOR kinase activity following kainic acid induced status epilepticus and analysis of rat brain response to chronic rapamycin treatment. PLoS One 2013; 8:e64455. [PMID: 23724051 PMCID: PMC3665782 DOI: 10.1371/journal.pone.0064455] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 04/15/2013] [Indexed: 01/09/2023] Open
Abstract
Mammalian target of rapamycin (mTOR) is a protein kinase that senses nutrient availability, trophic factors support, cellular energy level, cellular stress, and neurotransmitters and adjusts cellular metabolism accordingly. Adequate mTOR activity is needed for development as well as proper physiology of mature neurons. Consequently, changes in mTOR activity are often observed in neuropathology. Recently, several groups reported that seizures increase mammalian target of rapamycin (mTOR) kinase activity, and such increased activity in genetic models can contribute to spontaneous seizures. However, the current knowledge about the spatiotemporal pattern of mTOR activation induced by proconvulsive agents is rather rudimentary. Also consequences of insufficient mTOR activity on a status epilepticus are poorly understood. Here, we systematically investigated these two issues. We showed that mTOR signaling was activated by kainic acid (KA)-induced status epilepticus through several brain areas, including the hippocampus and cortex as well as revealed two waves of mTOR activation: an early wave (2 h) that occurs in neurons and a late wave that predominantly occurs in astrocytes. Unexpectedly, we found that pretreatment with rapamycin, a potent mTOR inhibitor, gradually (i) sensitized animals to KA treatment and (ii) induced gross anatomical changes in the brain.
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Affiliation(s)
- Matylda Macias
- Laboratory of Molecular and Cell Neurobiology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Magdalena Blazejczyk
- Laboratory of Molecular and Cell Neurobiology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | | | - Bartosz Caban
- Department of Neurobiology, University of Lodz, Lodz, Poland
| | - Agnieszka Skalecka
- Laboratory of Molecular and Cell Neurobiology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Bartosz Tarkowski
- Laboratory of Molecular and Cell Neurobiology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Anna Rodo
- Department of Pathology and Veterinary Diagnostics, Warsaw University of Life Sciences-SGGW, Warsaw, Poland
| | - Jan Konopacki
- Department of Neurobiology, University of Lodz, Lodz, Poland
| | - Jacek Jaworski
- Laboratory of Molecular and Cell Neurobiology, International Institute of Molecular and Cell Biology, Warsaw, Poland
- * E-mail:
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Yates SC, Zafar A, Hubbard P, Nagy S, Durant S, Bicknell R, Wilcock G, Christie S, Esiri MM, Smith AD, Nagy Z. Dysfunction of the mTOR pathway is a risk factor for Alzheimer's disease. Acta Neuropathol Commun 2013; 1:3. [PMID: 24252508 PMCID: PMC3776211 DOI: 10.1186/2051-5960-1-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 01/17/2013] [Indexed: 11/17/2022] Open
Abstract
Background The development of disease-modifying therapies for Alzheimer’s disease is hampered by our lack of understanding of the early pathogenic mechanisms and the lack of early biomarkers and risk factors. We have documented the expression pattern of mTOR regulated genes in the frontal cortex of Alzheimer’s disease patients. We have also examined the functional integrity of mTOR signaling in peripheral lymphocytes in Alzheimer’s disease patients relative to healthy controls. Results In the brain mTOR is seen to control molecular functions related to cell cycle regulation, cell death and several metabolic pathways. These downstream elements of the mTOR signaling cascade are deregulated in the brain of Alzheimer’s disease patients well before the development of pathology. This dysregulation of the mTOR downstream signaling cascade is not restricted to the brain but appears to be systemic and can be detected in peripheral lymphocytes as a reduced Rapamycin response. Conclusions The dysfunction of the signaling pathways downstream of mTOR may represent a risk factor for Alzheimer’s disease and is independent of the ApoE status of the patients. We have also identified the molecular substrates of the beneficial effects of Rapamycin on the nervous system. We believe that these results can further inform the development of clinical predictive tests for the risk of Alzheimer’s disease in patients with mild cognitive impairment.
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Chen LL, Feng HF, Mao XX, Ye Q, Zeng LH. One hour of pilocarpine-induced status epilepticus is sufficient to develop chronic epilepsy in mice, and is associated with mossy fiber sprouting but not neuronal death. Neurosci Bull 2013; 29:295-302. [PMID: 23471864 DOI: 10.1007/s12264-013-1310-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Accepted: 08/20/2012] [Indexed: 11/29/2022] Open
Abstract
Determining the minimal duration of status epilepticus (SE) that leads to the development of subsequent spontaneous seizures (i.e., epilepsy) is important, because it provides a critical time-window for seizure intervention and epilepsy prevention. In the present study, male ICR (Imprinting Control Region) mice were injected with pilocarpine to induce acute seizures. SE was terminated by diazepam at 10 min, 30 min, 1 h, 2 h and 4 h after seizure onset. Spontaneous seizures occurred in the 1, 2 and 4 h SE groups, and the seizure frequency increased with the prolongation of SE. Similarly, the Morris water maze revealed that the escape latency was significantly increased and the number of target quadrant crossings was markedly decreased in the 1, 2 and 4 h SE groups. Robust mossy fiber sprouting was observed in these groups, but not in the 10 or 30 min group. In contrast, Fluoro-Jade B staining revealed significant cell death only in the 4 h SE group. The incidence and frequency of spontaneous seizures were correlated with Timm score (P = 0.004) and escape latency (P = 0.004). These data suggest that SE longer than one hour results in spontaneous motor seizures and memory deficits, and spontaneous seizures are likely associated with robust mossy fiber sprouting but not neuronal death.
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Affiliation(s)
- Ling-Lin Chen
- Department of Pharmacology, College of Medicine, Zhejiang University, Hangzhou, 310058, China
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Chen L, Hu L, Dong JY, Ye Q, Hua N, Wong M, Zeng LH. Rapamycin has paradoxical effects on S6 phosphorylation in rats with and without seizures. Epilepsia 2013; 53:2026-33. [PMID: 23145776 DOI: 10.1111/epi.12013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
PURPOSE Accumulating data have demonstrated that seizures induced by kainate (KA) or pilocarpine activate the mammalian target of rapamycin (mTOR) pathway and that mTOR inhibitor rapamycin can inhibit mTOR activation, which subsequently has potential antiepileptic effects. However, a preliminary study showed a paradoxical exacerbation of increased mTOR pathway activity reflected by S6 phosphorylation when rapamycin was administrated within a short period before KA injection. In the present study, we examined this paradoxical effect of rapamycin in more detail, both in normal rats and KA-injected animals. METHODS Normal rats or KA-treated rats pretreated with rapamycin at different time intervals were sacrificed at various time points (1, 3, 6, 10, 15, and 24 h) after rapamycin administration or seizure onset for western blotting analysis. Phosphorylation of mTOR signaling target of Akt, mTOR, Rictor, Raptor, S6K, and S6 were analyzed. Seizure activity was monitored behaviorally and graded according to a modified Racine scale (n = 6 for each time point). Neuronal cell death was detected by Fluoro-Jade B staining. KEY FINDINGS In normal rats, we found that rapamycin showed the expected dose-dependent inhibition of S6 phosphorylation 3-24 h after injection, whereas a paradoxical elevation of S6 phosphorylation was observed 1 h after rapamycin. Similarly, pretreatment with rapamycin over 10 h before KA inhibited the KA seizure-induced mTOR activation. In contrast, rapamycin administered 1-6 h before KA caused a paradoxical increase in the KA seizure-induced mTOR activation. Rats pretreated with rapamycin 1 h prior to KA exhibited an increase in severity and duration of seizures and more neuronal cell death as compared to vehicle-treated groups. In contrast, rapamycin pretreated 10 h prior to KA had no effect on the seizures and decreased neuronal cell death. The paradoxical effect of rapamycin on S6 phosphorylation was correlated with upstream mTOR signaling and was reversed by pretreatment of perifosine, an Akt inhibitor. SIGNIFICANCE These data indicate the complexity of S6 regulation and its effect on epilepsy. Paradoxical effects of rapamycin need to be considered in clinical applications, such as for potential treatment for epilepsy and other neurologic disorders.
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Affiliation(s)
- Linglin Chen
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
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McCubrey JA, Steelman LS, Chappell WH, Sun L, Davis NM, Abrams SL, Franklin RA, Cocco L, Evangelisti C, Chiarini F, Martelli AM, Libra M, Candido S, Ligresti G, Malaponte G, Mazzarino MC, Fagone P, Donia M, Nicoletti F, Polesel J, Talamini R, Bäsecke J, Mijatovic S, Maksimovic-Ivanic D, Michele M, Tafuri A, Dulińska-Litewka J, Laidler P, D'Assoro AB, Drobot L, Umezawa D, Montalto G, Cervello M, Demidenko ZN. Advances in targeting signal transduction pathways. Oncotarget 2012; 3:1505-21. [PMID: 23455493 PMCID: PMC3681490 DOI: 10.18632/oncotarget.802] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 12/28/2012] [Indexed: 02/07/2023] Open
Abstract
Over the past few years, significant advances have occurred in both our understanding of the complexity of signal transduction pathways as well as the isolation of specific inhibitors which target key components in those pathways. Furthermore critical information is being accrued regarding how genetic mutations can affect the sensitivity of various types of patients to targeted therapy. Finally, genetic mechanisms responsible for the development of resistance after targeted therapy are being discovered which may allow the creation of alternative therapies to overcome resistance. This review will discuss some of the highlights over the past few years on the roles of key signaling pathways in various diseases, the targeting of signal transduction pathways and the genetic mechanisms governing sensitivity and resistance to targeted therapies.
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Affiliation(s)
- James A McCubrey
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, USA.
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Tsai V, Parker WE, Orlova KA, Baybis M, Chi AWS, Berg BD, Birnbaum JF, Estevez J, Okochi K, Sarnat HB, Flores-Sarnat L, Aronica E, Crino PB. Fetal brain mTOR signaling activation in tuberous sclerosis complex. ACTA ACUST UNITED AC 2012; 24:315-27. [PMID: 23081885 DOI: 10.1093/cercor/bhs310] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Tuberous sclerosis complex (TSC) is characterized by developmental malformations of the cerebral cortex known as tubers, comprised of cells that exhibit enhanced mammalian target of rapamycin (mTOR) signaling. To date, there are no reports of mTORC1 and mTORC2 activation in fetal tubers or in neural progenitor cells lacking Tsc2. We demonstrate mTORC1 activation by immunohistochemical detection of substrates phospho-p70S6K1 (T389) and phospho-S6 (S235/236), and mTORC2 activation by substrates phospho-PKCα (S657), phospho-Akt (Ser473), and phospho-SGK1 (S422) in fetal tubers. Then, we show that Tsc2 shRNA knockdown (KD) in mouse neural progenitor cells (mNPCs) in vitro results in enhanced mTORC1 (phospho-S6, phospho-4E-BP1) and mTORC2 (phospho-Akt and phospho-NDRG1) signaling, as well as a doubling of cell size that is rescued by rapamycin, an mTORC1 inhibitor. Tsc2 KD in vivo in the fetal mouse brain by in utero electroporation causes disorganized cortical lamination and increased cell volume that is prevented with rapamycin. We demonstrate for the first time that mTORC1 and mTORC2 signaling is activated in fetal tubers and in mNPCs following Tsc2 KD. These results suggest that inhibition of mTOR pathway signaling during embryogenesis could prevent abnormal brain development in TSC.
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Affiliation(s)
- Victoria Tsai
- PENN Epilepsy Center, Department of Neurology and University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA
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McCubrey JA, Steelman LS, Chappell WH, Abrams SL, Montalto G, Cervello M, Nicoletti F, Fagone P, Malaponte G, Mazzarino MC, Candido S, Libra M, Bäsecke J, Mijatovic S, Maksimovic-Ivanic D, Milella M, Tafuri A, Cocco L, Evangelisti C, Chiarini F, Martelli AM. Mutations and deregulation of Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades which alter therapy response. Oncotarget 2012; 3:954-87. [PMID: 23006971 PMCID: PMC3660063 DOI: 10.18632/oncotarget.652] [Citation(s) in RCA: 217] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Accepted: 09/17/2012] [Indexed: 02/07/2023] Open
Abstract
The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Certain components of these pathways, RAS, NF1, BRAF, MEK1, DUSP5, PP2A, PIK3CA, PIK3R1, PIK3R4, PIK3R5, IRS4, AKT, NFKB1, MTOR, PTEN, TSC1, and TSC2 may also be activated/inactivated by mutations or epigenetic silencing. Upstream mutations in one signaling pathway or even in downstream components of the same pathway can alter the sensitivity of the cells to certain small molecule inhibitors. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of components of these cascades can contribute to: resistance to other pathway inhibitors, chemotherapeutic drug resistance, premature aging as well as other diseases. This review will first describe these pathways and discuss how genetic mutations and epigenetic alterations can result in resistance to various inhibitors.
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Affiliation(s)
- James A McCubrey
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC, USA.
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Russo E, Citraro R, Constanti A, De Sarro G. The mTOR Signaling Pathway in the Brain: Focus on Epilepsy and Epileptogenesis. Mol Neurobiol 2012; 46:662-81. [DOI: 10.1007/s12035-012-8314-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 07/13/2012] [Indexed: 01/09/2023]
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Zhang B, Wong M. Pentylenetetrazole-induced seizures cause acute, but not chronic, mTOR pathway activation in rat. Epilepsia 2012; 53:506-11. [PMID: 22242835 DOI: 10.1111/j.1528-1167.2011.03384.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE The mammalian target of rapamycin (mTOR) pathway has been implicated in contributing to progressive epileptogenesis in models of chronic epilepsy. Conversely, seizures themselves may directly cause acute activation of the mTOR pathway. To isolate the direct effects of seizures on the mTOR pathway, the time course and mechanisms of mTOR activation were investigated with acute seizures induced by pentylenetetrazole (PTZ), which does not lead to chronic epilepsy. METHODS Western blot analysis was used to assay the phosphorylation of Akt and S6, as measures of activation of the phosphoinositide 3-kinase (PI3K)/Akt and mTOR pathways, respectively, at various time points after PTZ-induced seizures in rats. The ability of wortmannin, a PI3K inhibitor, to inhibit PTZ seizure-induced activation of the mTOR pathway was tested. KEY FINDINGS PTZ-induced seizures produced an immediate, transient mTOR activation lasting several hours, but no later, more chronic activation over days to weeks. This acute stimulation of the mTOR pathway by PTZ-induced seizures was mediated by upstream PI3K/Akt pathway activation and was blocked by a PI3K inhibitor. SIGNIFICANCE Compared with models of chronic epilepsy that exhibit biphasic (acute and chronic) mTOR pathway activation, PTZ-induced seizures produce only acute, but not chronic, mTOR activation. These results in the PTZ seizure model highlight potential differences in the involvement of the mTOR pathway between self-limited seizures and progressive epileptogenesis. These findings also suggest a potential therapeutic role of PI3K inhibitors in epilepsy.
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Affiliation(s)
- Bo Zhang
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA
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Abstract
Deregulated mTOR signaling drives the growth of various human cancers, making mTOR a major target for development of cancer chemotherapeutics. The role of mTOR in carcinogenesis is thought to be largely a consequence of its activity in the cytoplasm resulting in increased translation of pro-tumorigenic genes. However, emerging data locate mTOR in various subcellular compartments including Golgi, mitochondria, endoplasmic reticulum, and the nucleus, implying the presence of compartment-specific mTOR substrates and functions. Efforts to identify mTOR substrates in these compartments, and the mechanisms by which mTOR recruits these substrates and affects downstream cellular processes, will add to our understanding of the diversity of roles played by mTOR in carcinogenesis.
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Affiliation(s)
- Jung H Back
- Department of Dermatology, Columbia University Medical Center, New York, NY, USA
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Rapamycin for treatment of epilepsy: antiseizure, antiepileptogenic, both, or neither? Epilepsy Curr 2011; 11:66-8. [PMID: 21852879 DOI: 10.5698/1535-7511-11.2.66] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Therapeutic role of mammalian target of rapamycin (mTOR) inhibition in preventing epileptogenesis. Neurosci Lett 2011; 497:231-9. [PMID: 21354266 DOI: 10.1016/j.neulet.2011.02.037] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 01/25/2011] [Accepted: 02/15/2011] [Indexed: 12/19/2022]
Abstract
Traditionally, medical therapy for epilepsy has aimed to suppress seizure activity, but has been unable to alter the progression of the underlying disease. Recent advances in our understanding of mechanisms of epileptogenesis open the door for the development of new therapies which prevent the pathogenic changes in the brain that predispose to spontaneous seizures. In particular, the mammalian target of rapamycin (mTOR) signaling pathway has recently garnered interest as an important regulator of cellular changes involved in epileptogenesis, and mTOR inhibitors have generated excitement as potential antiepileptogenic agents. mTOR hyperactivation occurs in tuberous sclerosis complex (TSC), a common genetic cause of epilepsy, as a result of genetic mutations in upstream regulatory molecules. mTOR inhibition prevents epilepsy and brain pathology in animal models of TSC. mTOR dysregulation has also been demonstrated in a variety of other genetic and acquired epilepsies, including brain tumors, focal cortical dysplasias, and animal models of brain injury due to status epilepticus or trauma. Indeed, mTOR inhibitors appear to possess antiepileptogenic properties in animal models of acquired epilepsy as well. Thus, mTOR dysregulation may represent a final common pathway in epilepsies of various causes. Therefore, mTOR inhibition is an exciting potential antiepileptogenic strategy with broad applications for epilepsy and could be involved in a number of treatment modalities, including the ketogenic diet. Further research is necessary to determine the clinical utility of rapamycin and other mTOR inhibitors for antiepileptogenesis, and to devise new therapeutic targets by further elucidating the signaling molecules involved in epileptogenesis.
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