1
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Yang W, Tang CY, Fan DY, Wang YS, Wang PG, An J, Luan GM. Mice with type I interferon signaling deficiency are prone to epilepsy upon HSV-1 infection. Virol Sin 2024; 39:251-263. [PMID: 38219860 PMCID: PMC11074648 DOI: 10.1016/j.virs.2024.01.002] [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: 08/09/2023] [Accepted: 01/09/2024] [Indexed: 01/16/2024] Open
Abstract
Viral encephalitis continues to be a significant public health concern. In our previous study, we discovered a lower expression of antiviral factors, such as IFN-β, STING and IFI16, in the brain tissues of patients with Rasmussen's encephalitis (RE), a rare chronic neurological disorder often occurred in children, characterized by unihemispheric brain atrophy. Furthermore, a higher cumulative viral score of human herpes viruses (HHVs) was also found to have a significant positive correlation with the unihemispheric atrophy in RE. Type I IFNs (IFN-I) signaling is essential for innate anti-infection response by binding to IFN-α/β receptor (IFNAR). In this study, we infected WT mice and IFNAR-deficient A6 mice with herpes simplex virus 1 (HSV-1) via periocular injection to investigate the relationship between IFN-I signaling and HHVs-induced brain lesions. While all mice exhibited typical viral encephalitis lesions in their brains, HSV-induced epilepsy was only observed in A6 mice. The gene expression matrix, functional enrichment analysis and protein-protein interaction network revealed four gene models that were positively related with HSV-induced epilepsy. Additionally, ten key genes with the highest scores were identified. Taken together, these findings indicate that intact IFN-I signaling can effectively limit HHVs induced neural symptoms and brain lesions, thereby confirming the positive correlation between IFN-I signaling repression and brain atrophy in RE and other HHVs encephalitis.
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MESH Headings
- Animals
- Female
- Mice
- Brain/pathology
- Brain/virology
- Disease Models, Animal
- Encephalitis, Herpes Simplex/virology
- Encephalitis, Herpes Simplex/immunology
- Encephalitis, Herpes Simplex/pathology
- Epilepsy/virology
- Epilepsy/pathology
- Herpes Simplex/virology
- Herpes Simplex/pathology
- Herpes Simplex/immunology
- Herpesvirus 1, Human/pathogenicity
- Herpesvirus 1, Human/immunology
- Interferon Type I/metabolism
- Interferon Type I/immunology
- Mice, Inbred C57BL
- Mice, Knockout
- Protein Interaction Maps
- Receptor, Interferon alpha-beta/genetics
- Receptor, Interferon alpha-beta/deficiency
- Signal Transduction
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Affiliation(s)
- Wei Yang
- Beijing Key Laboratory of Epilepsy, Sanbo Brain Hospital, Capital Medical University, Beijing, 100093, China; Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100093, China
| | - Chong-Yang Tang
- Department of Neurosurgery, Epilepsy Center, Sanbo Brain Hospital, Capital Medical University, Beijing, 100093, China
| | - Dong-Ying Fan
- Department of Microbiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Yi-Song Wang
- Department of Microbiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Pei-Gang Wang
- Department of Microbiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Jing An
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100093, China; Department of Microbiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Guo-Ming Luan
- Beijing Key Laboratory of Epilepsy, Sanbo Brain Hospital, Capital Medical University, Beijing, 100093, China; Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100093, China; Department of Neurosurgery, Epilepsy Center, Sanbo Brain Hospital, Capital Medical University, Beijing, 100093, China; Chinese Institute for Brain Research, Beijing, 102206, China.
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2
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Kim JY, Kwon YG, Kim YM. The stress-responsive protein REDD1 and its pathophysiological functions. Exp Mol Med 2023; 55:1933-1944. [PMID: 37653030 PMCID: PMC10545776 DOI: 10.1038/s12276-023-01056-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 05/13/2023] [Accepted: 05/17/2023] [Indexed: 09/02/2023] Open
Abstract
Regulated in development and DNA damage-response 1 (REDD1) is a stress-induced protein that controls various cellular functions, including metabolism, oxidative stress, autophagy, and cell fate, and contributes to the pathogenesis of metabolic and inflammatory disorders, neurodegeneration, and cancer. REDD1 usually exerts deleterious effects, including tumorigenesis, metabolic inflammation, neurodegeneration, and muscle dystrophy; however, it also exhibits protective functions by regulating multiple intrinsic cell activities through either an mTORC1-dependent or -independent mechanism. REDD1 typically regulates mTORC1 signaling, NF-κB activation, and cellular pro-oxidant or antioxidant activity by interacting with 14-3-3 proteins, IκBα, and thioredoxin-interacting protein or 75 kDa glucose-regulated protein, respectively. The diverse functions of REDD1 depend on cell type, cellular context, interaction partners, and cellular localization (e.g., mitochondria, endomembrane, or cytosol). Therefore, comprehensively understanding the molecular mechanisms and biological roles of REDD1 under pathophysiological conditions is of utmost importance. In this review, based on the published literature, we highlight and discuss the molecular mechanisms underlying the REDD1 expression and its actions, biological functions, and pathophysiological roles.
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Affiliation(s)
- Ji-Yoon Kim
- Department of Anesthesiology and Pain Medicine, Hanyang University Hospital, Seoul, 04763, Republic of Korea
| | - Young-Guen Kwon
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
| | - Young-Myeong Kim
- Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chuncheon, 24341, Republic of Korea.
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3
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Wei C, Li S, Zhu Y, Chen W, Li C, Xu R. Network pharmacology identify intersection genes of quercetin and Alzheimer’s disease as potential therapeutic targets. Front Aging Neurosci 2022; 14:902092. [PMID: 36081896 PMCID: PMC9447902 DOI: 10.3389/fnagi.2022.902092] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 08/01/2022] [Indexed: 11/30/2022] Open
Abstract
Background Currently, there are no efficient therapies for Alzheimer’s disease (AD) among the elderly, although it is the most common etiology of dementia among the elderly. Quercetin, which has a variety of therapeutic properties, may pave the way for novel approaches to AD treatment. In the AD patients’ frontal cortex, current study aims to identify the potential mechanisms of quercetin’s pharmacological targets. Materials and methods The pharmacological targets of quercetin have been studied from DrugBank and SwissTarget. In order to distinguish AD-associated genes targeted by quercetin (Q-ADGs), we utilized an integrated intersection of gene expressions of the frontal cortex in combination with transcriptome analysis. To detect cortex-related Q-ADGs and immune-related Q-ADGs, a drug screening database and the immune infiltration analysis was utilized. The Q-ADGs were then linked with the AD severity scores (MMSE scores) to find severity-associated Q-ADGs. In addition, the miRNA-seq datasets were examined to identify severity-associated Q-ADG-miRNAs. Twelve genes, more frequently related to AD by previous studies among all the genes identified in the present study, were subjected to the verification of qRT-PCR in AD cell model. Results In the frontal lobe of AD, 207 Q-ADGs were discovered and found that axonogenesis, glial differentiation, and other biological processes had been enriched. There were 155 immune-related Q-ADGs (e.g., COX2, NOS2, HMGB1) and 65 cortex-related Q-ADGs (e.g., FOXO1, CXCL16, NOTCH3). Sixteen Q-ADGs (e.g., STAT3, RORA, BCL6) and 28 miRNAs (e.g., miR-142-5p, miR-17-5p) were found to be related to MMSE scores. In the qRT-PCR results, six out of twelve genes were significantly regulated by quercetin. DYRK1A, FOXO1, NOS2, NGF, NQO1, and RORA genes were novel target of quercetin in AD. DYRK1A, NOS2, and NQO1 genes targeted by quercetin have benefits in the treatment of AD. However, FOXO1, NGF, and RORA genes targeted by quercetin might have a negative impact on AD. Conclusion The role of quercetin in AD appears to be multifaceted, and it can affect patients’ frontal cortex in a variety of pathways, such as axonogenesis, immune infiltration, and glial cell differentiation. DYRK1A, NOS2, and NQO1 might be potential novel effective drug targets for quercetin in AD.
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Affiliation(s)
- Caihui Wei
- Department of Neurology, Jiangxi Provincial People’s Hospital, Medical College of Nanchang University, Nanchang, China
| | - Shu Li
- Department of Neurology, Jiangxi Provincial People’s Hospital, Medical College of Nanchang University, Nanchang, China
| | - Yu Zhu
- Department of Neurology, Jiangxi Provincial People’s Hospital, Medical College of Nanchang University, Nanchang, China
| | - Wenzhi Chen
- Department of Neurology, Jiangxi Provincial People’s Hospital, Medical College of Nanchang University, Nanchang, China
| | - Cheng Li
- Department of Neurology, Jiangxi Provincial People’s Hospital, Medical College of Nanchang University, Nanchang, China
| | - Renshi Xu
- Department of Neurology, Jiangxi Provincial People’s Hospital, Medical College of Nanchang University, Nanchang, China
- Department of Neurology, The First Affiliated Hospital of Nanchang Medical College, Jiangxi Provincial People’s Hospital, Nanchang, China
- *Correspondence: Renshi Xu,
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4
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Guan L, Crasta KC, Maier AB. Assessment of cell cycle regulators in human peripheral blood cells as markers of cellular senescence. Ageing Res Rev 2022; 78:101634. [PMID: 35460888 DOI: 10.1016/j.arr.2022.101634] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/11/2022] [Accepted: 04/15/2022] [Indexed: 12/12/2022]
Abstract
Cellular senescence has gained increasing interest during recent years, particularly due to causal involvement in the aging process corroborated by multiple experimental findings. Indeed, cellular senescence considered to be one of the hallmarks of aging, is defined as a stable growth arrest predominantly mediated by cell cycle regulators p53, p21 and p16. Senescent cells have frequently been studied in the peripheral blood of humans due to its accessibility. This review summarizes ex vivo studies describing cell cycle regulators as markers of senescence in human peripheral blood cells, along with detection methodologies and associative studies examining demographic and clinical characteristics. The utility of techniques such as the quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), microarray, RNA sequencing and nCounter technologies for detection at the transcriptional level, along with Western blotting, enzyme-linked immunosorbent assay and flow cytometry at the translational level, will be brought up at salient points throughout this review. Notably, housekeeping genes or proteins serving as controls such as GAPDH and β-Actin, were found not to be stably expressed in some contexts. As such, optimization and validation of such genes during experimental design were recommended. In addition, the expression of cell cycle regulators was found to vary not only between different types of blood cells such as T cells and B cells but also between stages of cellular differentiation such as naïve T cells and highly differentiated T cells. On the other hand, the associations of the presence of cell cycle regulators with demographics (age, gender, ethnicity, and socioeconomic status), clinical characteristics (body mass index, specific diseases, disease-related parameters) and lifestyle vary in groups of participants. One envisions that increased understanding and insights into the assessment of cell cycle regulators as markers of senescence in human peripheral blood cells will help inform prognostication and clinical intervention in elderly individuals.
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Affiliation(s)
- Lihuan Guan
- Department of Medicine and Aged Care, @AgeMelbourne, The Royal Melbourne Hospital, The University of Melbourne, Victoria, Australia.
| | - Karen C Crasta
- Healthy Longevity Translational Researc h Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Department of Physiology, National University of Singapore, Singapore; NUS Center for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Agency for Science, Technology & Research (A⁎STAR), Institute of Molecular and Cell Biology (IMCB), Singapore.
| | - Andrea B Maier
- Department of Medicine and Aged Care, @AgeMelbourne, The Royal Melbourne Hospital, The University of Melbourne, Victoria, Australia; Healthy Longevity Translational Researc h Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Centre for Healthy Longevity, @AgeSingapore, National University Health System, Singapore; Department of Human Movement Sciences, @AgeAmsterdam, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, the Netherlands.
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5
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Pérez-Sisqués L, Sancho-Balsells A, Solana-Balaguer J, Campoy-Campos G, Vives-Isern M, Soler-Palazón F, Anglada-Huguet M, López-Toledano MÁ, Mandelkow EM, Alberch J, Giralt A, Malagelada C. RTP801/REDD1 contributes to neuroinflammation severity and memory impairments in Alzheimer's disease. Cell Death Dis 2021; 12:616. [PMID: 34131105 PMCID: PMC8206344 DOI: 10.1038/s41419-021-03899-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 05/25/2021] [Accepted: 06/01/2021] [Indexed: 02/05/2023]
Abstract
RTP801/REDD1 is a stress-regulated protein whose upregulation is necessary and sufficient to trigger neuronal death. Its downregulation in Parkinson's and Huntington's disease models ameliorates the pathological phenotypes. In the context of Alzheimer's disease (AD), the coding gene for RTP801, DDIT4, is responsive to Aβ and modulates its cytotoxicity in vitro. Also, RTP801 mRNA levels are increased in AD patients' lymphocytes. However, the involvement of RTP801 in the pathophysiology of AD has not been yet tested. Here, we demonstrate that RTP801 levels are increased in postmortem hippocampal samples from AD patients. Interestingly, RTP801 protein levels correlated with both Braak and Thal stages of the disease and with GFAP expression. RTP801 levels are also upregulated in hippocampal synaptosomal fractions obtained from murine 5xFAD and rTg4510 mice models of the disease. A local RTP801 knockdown in the 5xFAD hippocampal neurons with shRNA-containing AAV particles ameliorates cognitive deficits in 7-month-old animals. Upon RTP801 silencing in the 5xFAD mice, no major changes were detected in hippocampal synaptic markers or spine density. Importantly, we found an unanticipated recovery of several gliosis hallmarks and inflammasome key proteins upon neuronal RTP801 downregulation in the 5xFAD mice. Altogether our results suggest that RTP801 could be a potential future target for theranostic studies since it could be a biomarker of neuroinflammation and neurotoxicity severity of the disease and, at the same time, a promising therapeutic target in the treatment of AD.
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Affiliation(s)
- Leticia Pérez-Sisqués
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Anna Sancho-Balsells
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Catalonia, Spain
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Júlia Solana-Balaguer
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Genís Campoy-Campos
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Marcel Vives-Isern
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Ferran Soler-Palazón
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Marta Anglada-Huguet
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
- CAESAR Research Center, Bonn, Germany
| | | | - Eva-Maria Mandelkow
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
- CAESAR Research Center, Bonn, Germany
| | - Jordi Alberch
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Catalonia, Spain
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
- Production and Validation Center of Advanced Therapies (Creatio), Faculty of Medicine and Health Science, University of Barcelona, Barcelona, Catalonia, Spain
| | - Albert Giralt
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Catalonia, Spain.
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
- Production and Validation Center of Advanced Therapies (Creatio), Faculty of Medicine and Health Science, University of Barcelona, Barcelona, Catalonia, Spain.
| | - Cristina Malagelada
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Catalonia, Spain.
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
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6
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Huang P, Bai L, Liu L, Fu J, Wu K, Liu H, Liu Y, Qi B, Qi B. Redd1 knockdown prevents doxorubicin-induced cardiac senescence. Aging (Albany NY) 2021; 13:13788-13806. [PMID: 33962393 PMCID: PMC8202877 DOI: 10.18632/aging.202972] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 03/23/2021] [Indexed: 12/13/2022]
Abstract
Regulated in development and DNA damage response-1 (Redd1) is a stress-response gene that is transcriptionally induced by diverse stressful stimuli to influence cellular growth and survival. Although evidence suggests that aging may drive Redd1 expression in skeletal muscles, the expression patterns and functions of Redd1 in senescent cardiomyocytes remain unspecified. To address this issue, in vitro and in vivo models of cardiomyocyte senescence were established by administration of doxorubicin (Dox). Redd1 overexpression and knockdown was achieved in cultured H9c2 cardiomyocytes and mouse tissues using, respectively, lentivirals and adeno-associated virus 9 (AAV9) vectors. In the hearts of both aged (24 months old) and Dox-treated mice, as well as in Dox-exposed H9c2 cardiomyocytes, high Redd1 expression accompanied the increase in both cellular senescence markers (p16INK4a and p21) and pro-inflammatory cytokine expression indicative of a stress-associated secretory phenotype (SASP). Notably, Redd1 overexpression accentuated, whereas Redd1 silencing markedly attenuated, Dox-induced cardiomyocyte senescence features both in vitro and in vivo. Notably, AAV9-shRNA-mediated Redd1 silencing significantly alleviated Dox-induced cardiac dysfunction. Moreover, through pharmacological inhibition, immunofluorescence, and western blotting, signaling pathway analyses indicated that Redd1 promotes cardiomyocyte senescence as a downstream effector of p38 MAPK to promote NF-kB signaling via p65 phosphorylation and nuclear translocation.
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Affiliation(s)
- Pianpian Huang
- Department of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
- Department of Geriatrics, Wuhan No.1 Hospital, Wuhan, Hubei 430022, China
| | - Lijuan Bai
- Department of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Lihua Liu
- Department of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Jun Fu
- Department of Radiology, Wuhan No.1 Hospital, Wuhan, Hubei 430022, China
| | - Kefei Wu
- Department of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Hongxia Liu
- Department of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Yun Liu
- Department of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Benming Qi
- Department of Otorhinolaryngology, First People’s Hospital of Yunnan Province, Kunming, Yunnan 650000, China
| | - Benling Qi
- Department of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
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7
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Britto FA, Dumas K, Giorgetti-Peraldi S, Ollendorff V, Favier FB. Is REDD1 a metabolic double agent? Lessons from physiology and pathology. Am J Physiol Cell Physiol 2020; 319:C807-C824. [PMID: 32877205 DOI: 10.1152/ajpcell.00340.2020] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Akt/mechanistic target of rapamycin (mTOR) signaling pathway governs macromolecule synthesis, cell growth, and metabolism in response to nutrients and growth factors. Regulated in development and DNA damage response (REDD)1 is a conserved and ubiquitous protein, which is transiently induced in response to multiple stimuli. Acting like an endogenous inhibitor of the Akt/mTOR signaling pathway, REDD1 protein has been shown to regulate cell growth, mitochondrial function, oxidative stress, and apoptosis. Recent studies also indicate that timely REDD1 expression limits Akt/mTOR-dependent synthesis processes to spare energy during metabolic stresses, avoiding energy collapse and detrimental consequences. In contrast to this beneficial role for metabolic adaptation, REDD1 chronic expression appears involved in the pathogenesis of several diseases. Indeed, REDD1 expression is found as an early biomarker in many pathologies including inflammatory diseases, cancer, neurodegenerative disorders, depression, diabetes, and obesity. Moreover, prolonged REDD1 expression is associated with cell apoptosis, excessive reactive oxygen species (ROS) production, and inflammation activation leading to tissue damage. In this review, we decipher several mechanisms that make REDD1 a likely metabolic double agent depending on its duration of expression in different physiological and pathological contexts. We also discuss the role played by REDD1 in the cross talk between the Akt/mTOR signaling pathway and the energetic metabolism.
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Affiliation(s)
| | - Karine Dumas
- Université Cote d'Azur, INSERM, UMR1065, C3M, Nice, France
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8
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Hugon J, Mouton-Liger F, Dumurgier J, Paquet C. PKR involvement in Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2017; 9:83. [PMID: 28982375 PMCID: PMC5629792 DOI: 10.1186/s13195-017-0308-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Accepted: 09/08/2017] [Indexed: 12/15/2022]
Abstract
BACKGROUND Brain lesions in Alzheimer's disease (AD) are characterized by Aβ accumulation, neurofibrillary tangles, and synaptic and neuronal vanishing. According to the amyloid cascade hypothesis, Aβ1-42 oligomers could trigger a neurotoxic cascade with kinase activation that leads to tau phosphorylation and neurodegeneration. Detrimental pathways that are associated with kinase activation could also be linked to the triggering of direct neuronal death, the production of free radicals, and neuroinflammation. RESULTS Among these kinases, PKR (eukaryotic initiation factor 2α kinase 2) is a pro-apoptotic enzyme that inhibits translation and that has been implicated in several molecular pathways that lead to AD brain lesions and disturbed memory formation. PKR accumulates in degenerating neurons and is activated by Aβ1-42 neurotoxicity. It might modulate Aβ synthesis through BACE 1 induction. PKR is increased in cerebrospinal fluid from patients with AD and mild cognitive impairment and can induce the activation of pro-inflammatory pathways leading to TNFα and IL1-β production. In addition, experimentally, PKR seems to down-regulate the molecular processes of memory consolidation. This review highlights the major findings linking PKR and abnormal brain metabolism associated with AD lesions. CONCLUSIONS Studying the detrimental role of PKR signaling in AD could pave the way for a neuroprotective strategy in which PKR inhibition could reduce neuronal demise and alleviate cognitive decline as well as the cumbersome burden of AD for patients.
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Affiliation(s)
- Jacques Hugon
- Center of Cognitive Neurology and Inserm U942 Lariboisière Hospital AP-HP University Paris Diderot, 75010, Paris, France. .,Center of Cognitive Neurology, Lariboisière FW Hospital, 200 rue du Faubourg Saint Denis, 75010, Paris, France.
| | | | - Julien Dumurgier
- Center of Cognitive Neurology and Inserm U942 Lariboisière Hospital AP-HP University Paris Diderot, 75010, Paris, France
| | - Claire Paquet
- Center of Cognitive Neurology and Inserm U942 Lariboisière Hospital AP-HP University Paris Diderot, 75010, Paris, France
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9
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Muvarak NE, Chowdhury K, Xia L, Robert C, Choi EY, Cai Y, Bellani M, Zou Y, Singh ZN, Duong VH, Rutherford T, Nagaria P, Bentzen SM, Seidman MM, Baer MR, Lapidus RG, Baylin SB, Rassool FV. Enhancing the Cytotoxic Effects of PARP Inhibitors with DNA Demethylating Agents - A Potential Therapy for Cancer. Cancer Cell 2016; 30:637-650. [PMID: 27728808 PMCID: PMC5201166 DOI: 10.1016/j.ccell.2016.09.002] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 03/16/2016] [Accepted: 09/08/2016] [Indexed: 12/20/2022]
Abstract
Poly (ADP-ribose) polymerase inhibitors (PARPis) are clinically effective predominantly for BRCA-mutant tumors. We introduce a mechanism-based strategy to enhance PARPi efficacy based on DNA damage-related binding between DNA methyltransferases (DNMTs) and PARP1. In acute myeloid leukemia (AML) and breast cancer cells, DNMT inhibitors (DNMTis) alone covalently bind DNMTs into DNA and increase PARP1 tightly bound into chromatin. Low doses of DNMTis plus PARPis, versus each drug alone, increase PARPi efficacy, increasing amplitude and retention of PARP1 directly at laser-induced DNA damage sites. This correlates with increased DNA damage, synergistic tumor cytotoxicity, blunting of self-renewal, and strong anti-tumor responses, in vivo in unfavorable AML subtypes and BRCA wild-type breast cancer cells. Our combinatorial approach introduces a strategy to enhance efficacy of PARPis in treating cancer.
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MESH Headings
- Animals
- Antineoplastic Combined Chemotherapy Protocols/pharmacology
- Cell Line, Tumor
- Chromatin/metabolism
- DNA Breaks, Double-Stranded
- DNA Methylation/drug effects
- Drug Synergism
- Female
- Humans
- Leukemia, Myeloid, Acute/drug therapy
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/metabolism
- Male
- Mice
- Mice, Inbred NOD
- Mice, Nude
- Phthalazines/pharmacology
- Poly (ADP-Ribose) Polymerase-1/antagonists & inhibitors
- Poly (ADP-Ribose) Polymerase-1/metabolism
- Poly(ADP-ribose) Polymerase Inhibitors/pharmacology
- Triple Negative Breast Neoplasms/drug therapy
- Triple Negative Breast Neoplasms/genetics
- Triple Negative Breast Neoplasms/metabolism
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Nidal E Muvarak
- Department of Radiation Oncology, University of Maryland, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA
| | - Khadiza Chowdhury
- Department of Radiation Oncology, University of Maryland, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA
| | - Limin Xia
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins Medical Institutions, Baltimore, MD 21231, USA
| | - Carine Robert
- Department of Radiation Oncology, University of Maryland, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA
| | - Eun Yong Choi
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA
| | - Yi Cai
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins Medical Institutions, Baltimore, MD 21231, USA
| | - Marina Bellani
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Ying Zou
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Zeba N Singh
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Vu H Duong
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA
| | | | - Pratik Nagaria
- Department of Radiation Oncology, University of Maryland, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA
| | - Søren M Bentzen
- Department of Radiation Oncology, University of Maryland, Baltimore, MD 21201, USA; Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Michael M Seidman
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Maria R Baer
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA; Veterans Affairs Medical Center, Baltimore, MD 21201, USA
| | - Rena G Lapidus
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA
| | - Stephen B Baylin
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins Medical Institutions, Baltimore, MD 21231, USA; Van Andel Research Institute, Grand Rapids, MI 49503
| | - Feyruz V Rassool
- Department of Radiation Oncology, University of Maryland, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA.
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10
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Taga M, Minett T, Classey J, Matthews FE, Brayne C, Ince PG, Nicoll JA, Hugon J, Boche D. Metaflammasome components in the human brain: a role in dementia with Alzheimer's pathology? Brain Pathol 2016; 27:266-275. [PMID: 27106634 PMCID: PMC5412675 DOI: 10.1111/bpa.12388] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 04/19/2016] [Indexed: 12/17/2022] Open
Abstract
Epidemiological and genetic studies have identified metabolic disorders and inflammation as risk factors for Alzheimer's disease (AD). Evidence in obesity and type-2 diabetes suggests a role for a metabolic inflammasome ("metaflammasome") in mediating chronic inflammation in peripheral organs implicating IKKβ (inhibitor of nuclear factor kappa-B kinase subunit beta), IRS1 (insulin receptor substrate 1), JNK (c-jun N-terminal kinase), and PKR (double-stranded RNA protein kinase). We hypothesized that these proteins are expressed in the brain in response to metabolic risk factors in AD. Neocortex from 299 participants from the MRC Cognitive Function and Ageing Studies was analysed by immunohistochemistry for the expression of the phosphorylated (active) form of IKKβ [pSer176/180 ], IRS1 [pS312 ], JNK [pThr183 /Tyr185 ] and PKR [pT451 ]. The data were analyzed to investigate whether the proteins were expressed together and in relation with metabolic disorders, dementia, Alzheimer's pathology and APOE genotype. We observed a change from a positive to a negative association between the proteins and hypertension according to the dementia status. Type-2 diabetes was negatively related with the proteins among participants without dementia; whereas participants with dementia and AD pathology showed a positive association with JNK. A significant association between IKKβ and JNK in participants with dementia and AD pathology was observed, but not in those without dementia. Otherwise, weak to moderate associations were observed among the protein loads. The presence of dementia was significantly associated with JNK and negatively associated with IKKβ and IRS1. Cognitive scores showed a significant positive relationship with IKKβ and a negative with IRS1, JNK and PKR. The proteins were significantly associated with pathology in Alzheimer's participants with the relationship being inverse or not significant in participants without dementia. Expression of the proteins was not related to APOE genotype. These findings highlight a role for these proteins in AD pathophysiology but not necessarily as a complex.
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Affiliation(s)
- Mariko Taga
- Clinical Neurosciences, Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, UK.,INSERM U942, Paris, France
| | - Thais Minett
- Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Cambridge, UK.,Department of Radiology, University of Cambridge, Cambridge, UK
| | - John Classey
- Clinical Neurosciences, Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Fiona E Matthews
- MRC Biostatistics Unit, Cambridge Institute of Public Health, Cambridge, UK
| | - Carol Brayne
- Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Cambridge, UK
| | - Paul G Ince
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, Sheffield University, Sheffield, UK
| | - James Ar Nicoll
- Clinical Neurosciences, Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, UK.,Department of Cellular Pathology, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Jacques Hugon
- INSERM U942, Paris, France.,University of Paris Diderot, Sorbonne Paris Cité, Paris, France.,Centre Memoire de Ressources et de Recherche Paris Nord Ile de France AP-HP, Hôpital Lariboisière, Paris, France
| | - Delphine Boche
- Clinical Neurosciences, Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, UK
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11
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Pinno J, Bongartz H, Klepsch O, Wundrack N, Poli V, Schaper F, Dittrich A. Interleukin-6 influences stress-signalling by reducing the expression of the mTOR-inhibitor REDD1 in a STAT3-dependent manner. Cell Signal 2016; 28:907-16. [PMID: 27094713 DOI: 10.1016/j.cellsig.2016.04.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 04/05/2016] [Accepted: 04/09/2016] [Indexed: 11/30/2022]
Abstract
Interleukin 6 (IL-6) is a pleiotropic cytokine and a strong activator of Mammalian Target of Rapamycin (mTOR). In contrast, mTOR activity is negatively regulated by Regulated in Development and DNA Damage Responses 1 (REDD1). Expression of REDD1 is induced by cellular stressors such as glucocorticoids and DNA damaging agents. We show that the expression of basal as well as stress-induced REDD1 is reduced by IL-6. The reduction of REDD1 expression by IL-6 is independent of proteasomal or caspase-mediated degradation of REDD1 protein. Instead, induction of REDD1 mRNA is reduced by IL-6. The regulation of REDD1 expression by IL-6 is independent of Phosphatidylinositide-3-Kinase (PI3K) and Mitogen-Activated Protein Kinase (MAPK) signalling but depends on the expression and activation of Signal Transducer and Activator of Transcription 3 (STAT3). Furthermore, the reduction of basal REDD1 expression by IL-6 correlates with IL-6-induced activation of mTOR signalling. Inhibition of STAT3 activation blocks IL-6-induced mTOR activation. In summary, we present a novel STAT3-dependent mechanism of both IL-6-induced activation of mTOR and IL-6-dependent reversion of stress-induced inhibition of mTOR activity.
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Affiliation(s)
- Jessica Pinno
- Institute of Biology, Department of Systems Biology, Otto-von-Guericke University, Universitätsplatz 2, Gebäude 28, 39106 Magdeburg, Germany.
| | - Hannes Bongartz
- Institute of Biology, Department of Systems Biology, Otto-von-Guericke University, Universitätsplatz 2, Gebäude 28, 39106 Magdeburg, Germany.
| | - Oliver Klepsch
- Institute of Biology, Department of Systems Biology, Otto-von-Guericke University, Universitätsplatz 2, Gebäude 28, 39106 Magdeburg, Germany.
| | - Nicole Wundrack
- Institute of Biology, Department of Systems Biology, Otto-von-Guericke University, Universitätsplatz 2, Gebäude 28, 39106 Magdeburg, Germany.
| | - Valeria Poli
- Molecular Biotechnology Center (MBC), Department of Molecular Biotechnology and Health Sciences, University of Turin, Via Nizza 52, 10126 Turin, Italy.
| | - Fred Schaper
- Institute of Biology, Department of Systems Biology, Otto-von-Guericke University, Universitätsplatz 2, Gebäude 28, 39106 Magdeburg, Germany.
| | - Anna Dittrich
- Institute of Biology, Department of Systems Biology, Otto-von-Guericke University, Universitätsplatz 2, Gebäude 28, 39106 Magdeburg, Germany.
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12
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Grainger DL, Kutzler L, Rannels SL, Kimball SR. Validation of a commercially available anti-REDD1 antibody using RNA interference and REDD1-/- mouse embryonic fibroblasts. F1000Res 2016; 5:250. [PMID: 27335637 PMCID: PMC4893971 DOI: 10.12688/f1000research.7691.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/29/2016] [Indexed: 01/16/2023] Open
Abstract
REDD1 is a transcriptional target gene of p53 and HIF-1, and an inhibitor of mTOR (mechanistic target of rapamycin) complex 1 (mTORC1)-signaling through PP2A-dependent interaction, making it an important convergence point of both tumor suppression and cell growth pathways. In accordance with this positioning, REDD1 levels are transcriptionally upregulated in response to a variety of cellular stress factors such as nutrient deprivation, hypoxia and DNA damage. In the absence of such conditions, and in particular where growth factor signaling is activated, REDD1 expression is typically negligible; therefore, it is necessary to induce REDD1 prior to experimentation or detection in model systems. Here, we evaluated the performance of a commercially available polyclonal antibody recognizing REDD1 by Western blotting in the presence of thapsigargin, a pharmacological inducer of ER stress well known to upregulate REDD1 protein expression. Further, REDD1 antibody specificity was challenged in HEK-293 cells in the presence of RNA interference and with a REDD1
-/- mouse embryonic fibroblast knockout cell line. Results showed reproducibility and specificity of the antibody, which was upheld in the presence of thapsigargin treatment. We conclude that this antibody can be used to reliably detect REDD1 endogenous expression in samples of both human and mouse origin.
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Affiliation(s)
| | - Lydia Kutzler
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA, USA
| | - Sharon L Rannels
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA, USA
| | - Scot R Kimball
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA, USA
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13
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Julian A, Dugast E, Ragot S, Krolak-Salmon P, Berrut G, Dantoine T, Hommet C, Hanon O, Page G, Paccalin M. There is no correlation between peripheral inflammation and cognitive status at diagnosis in Alzheimer's disease. Aging Clin Exp Res 2015; 27:589-94. [PMID: 25700558 DOI: 10.1007/s40520-015-0332-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 02/10/2015] [Indexed: 12/18/2022]
Abstract
BACKGROUND Besides the neurofibrillary tangles and amyloid plaques, an inflammatory process is involved at central and peripheral levels in Alzheimer's disease (AD). We aimed to determine whether peripheral inflammatory parameter levels, in plasma and in peripheral blood mononuclear cells (PBMCs), could be correlated with the cognitive status at the time of AD diagnosis. METHODS Patients were included at diagnosis with MMSE score between 16 and 25 and were naive of symptomatic treatment for AD. C-reactive protein >10 mg/L and any acute or chronic inflammation were considered as exclusion criteria. Cognitive assessment also included the ADAScog scale. Plasma interleukins (IL)-1β, IL-6, tumor necrosis factor (TNF)-α and the chemokine ligand 5 (CCL5) were measured using Luminex(®) X-MAP(®) technology. A subgroup of patients also underwent measures of these parameters in extracellular and intracellular compartments of PBMCs (ancillary study). RESULTS One hundred and nine patients were included; mean age 79.4 ± 6.8 years with 37 patients in the ancillary study. The mean values of IL-1β, TNF-α, IL-6 and CCL5 values were 1.49, 7.18, 3.09 and 69,615.81 pg/mL, respectively. No correlation between plasma cytokines or chemokine levels and cognitive scores was found. In PBMCs, the levels of cytokines were detectable but did not either show any correlation with cognitive scores. CONCLUSION Our data indicate that at diagnosis, peripheral levels of cytokines and CCL5 display low values without any correlation with the cognitive status. Further results of our study will show if these circulating markers are related to the progression of AD.
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Affiliation(s)
- Adrien Julian
- Centre Mémoire de Ressources et de Recherche, Poitiers University Hospital, Poitiers, France.
- Department of Neurology, Poitiers University Hospital, Poitiers, France.
- EA3808 molecular Targets and Therapeutic of Alzheimer's disease, University of Poitiers, Pôle Biologie Santé Bâtiment B36/B37, Secteur β-Niveau 0, 1 Rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France.
| | - Emilie Dugast
- EA3808 molecular Targets and Therapeutic of Alzheimer's disease, University of Poitiers, Pôle Biologie Santé Bâtiment B36/B37, Secteur β-Niveau 0, 1 Rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
- Centre d'Investigation Clinique, Poitiers University Hospital, Poitiers, France
| | - Stéphanie Ragot
- Centre d'Investigation Clinique, Poitiers University Hospital, Poitiers, France
| | - Pierre Krolak-Salmon
- Centre Mémoire de Ressources et de Recherche, Lyon University Hospital, Lyon, France
| | - Gilles Berrut
- Department of Geriatrics, Nantes University Hospital, Nantes, France
| | - Thierry Dantoine
- Department of Geriatrics, Limoges University Hospital, Limoges, France
| | - Caroline Hommet
- Centre Mémoire de Ressources et de Recherche, Tours University Hospital, Tours, France
| | - Olivier Hanon
- Department of Geriatrics, Paris Broca University Hospital, Paris, France
| | - Guylène Page
- EA3808 molecular Targets and Therapeutic of Alzheimer's disease, University of Poitiers, Pôle Biologie Santé Bâtiment B36/B37, Secteur β-Niveau 0, 1 Rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
| | - Marc Paccalin
- Centre Mémoire de Ressources et de Recherche, Poitiers University Hospital, Poitiers, France
- EA3808 molecular Targets and Therapeutic of Alzheimer's disease, University of Poitiers, Pôle Biologie Santé Bâtiment B36/B37, Secteur β-Niveau 0, 1 Rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
- Centre d'Investigation Clinique, Poitiers University Hospital, Poitiers, France
- Department of Geriatrics, Poitiers University Hospital, Poitiers, France
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14
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Martín-Flores N, Romaní-Aumedes J, Rué L, Canal M, Sanders P, Straccia M, Allen ND, Alberch J, Canals JM, Pérez-Navarro E, Malagelada C. RTP801 Is Involved in Mutant Huntingtin-Induced Cell Death. Mol Neurobiol 2015; 53:2857-2868. [PMID: 25876513 DOI: 10.1007/s12035-015-9166-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/30/2015] [Indexed: 01/16/2023]
Abstract
RTP801 expression is induced by cellular stress and has a pro-apoptotic function in non-proliferating differentiated cells such as neurons. In several neurodegenerative disorders, including Parkinson's disease and Alzheimer's disease, elevated levels of RTP801 have been observed, which suggests a role for RTP801 in neuronal death. Neuronal death is also a pathological hallmark in Huntington's disease (HD), an inherited neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin gene. Currently, the exact mechanisms underlying mutant huntingtin (mhtt)-induced toxicity are still unclear. Here, we investigated whether RTP801 is involved in (mhtt)-induced cell death. Ectopic exon-1 mhtt elevated RTP801 mRNA and protein levels in nerve growth factor (NGF)-differentiated PC12 cells and in rat primary cortical neurons. In neuronal PC12 cells, mhtt also contributed to RTP801 protein elevation by reducing its proteasomal degradation rate, in addition to promoting RTP801 gene expression. Interestingly, silencing RTP801 expression with short hairpin RNAs (shRNAs) blocked mhtt-induced cell death in NGF-differentiated PC12 cells. However, RTP801 protein levels were not altered in the striatum of Hdh(Q7/Q111) and R6/1 mice, two HD models that display motor deficits but not neuronal death. Importantly, RTP801 protein levels were elevated in both neural telencephalic progenitors differentiated from HD patient-derived induced pluripotent stem cells and in the putamen and cerebellum of human HD postmortem brains. Taken together, our results suggest that RTP801 is a novel downstream effector of mhtt-induced toxicity and that it may be relevant to the human disease.
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Affiliation(s)
- Núria Martín-Flores
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain
| | - Joan Romaní-Aumedes
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain
| | - Laura Rué
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Mercè Canal
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain
| | - Phil Sanders
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Marco Straccia
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Nicholas D Allen
- Divisions of Pathophysiology & Repair and Neuroscience, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
| | - Jordi Alberch
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Josep M Canals
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Esther Pérez-Navarro
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain. .,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain. .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
| | - Cristina Malagelada
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.
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15
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Abstract
Alzheimer's disease (AD) is characterized by cognitive impairment in clinical presentation, and by β-amyloid (Aβ) production and the hyper-phosphorylation of tau in basic research. More highlights demonstrate that the activation of the mammalian target of rapamycin (mTOR) enhances Aβ generation and deposition by modulating amyloid precursor protein (APP) metabolism and upregulating β- and γ-secretases. mTOR, an inhibitor of autophagy, decreases Aβ clearance by scissoring autophagy function. mTOR regulates Aβ generation or Aβ clearance by regulating several key signaling pathways, including phosphoinositide 3-kinase (PI3-K)/protein kinase B (Akt), glycogen synthase kinase 3 [GSK-3], AMP-activated protein kinase (AMPK), and insulin/insulin-like growth factor 1 (IGF-1). The activation of mTOR is also a contributor to aberrant hyperphosphorylated tau. Rapamycin, the inhibitor of mTOR, may mitigate cognitive impairment and inhibit the pathologies associated with amyloid plaques and neurofibrillary tangles by promoting autophagy. Furthermore, the upstream and downstream components of mTOR signaling are involved in the pathogenesis and progression of AD. Hence, inhibiting the activation of mTOR may be an important therapeutic target for AD.
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Affiliation(s)
- Zhiyou Cai
- Department of Neurology, Renmin Hospital, Hubei University of Medicine, Shiyan Renmin Hospital, Shiyan, Hubei Province, People's Republic of China
| | - Guanghui Chen
- Department of Neurology, Renmin Hospital, Hubei University of Medicine, Shiyan Renmin Hospital, Shiyan, Hubei Province, People's Republic of China
| | - Wenbo He
- Department of Neurology, Renmin Hospital, Hubei University of Medicine, Shiyan Renmin Hospital, Shiyan, Hubei Province, People's Republic of China
| | - Ming Xiao
- Department of Anatomy, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Liang-Jun Yan
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA
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16
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Canal M, Romaní-Aumedes J, Martín-Flores N, Pérez-Fernández V, Malagelada C. RTP801/REDD1: a stress coping regulator that turns into a troublemaker in neurodegenerative disorders. Front Cell Neurosci 2014; 8:313. [PMID: 25324725 PMCID: PMC4183088 DOI: 10.3389/fncel.2014.00313] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Accepted: 09/17/2014] [Indexed: 12/16/2022] Open
Abstract
Mechanistic target of Rapamycin (mTOR) pathway regulates essential processes directed to preserve cellular homeostasis, such as cell growth, proliferation, survival, protein synthesis and autophagy. Importantly, mTOR pathway deregulation has been related to many diseases. Indeed, it has become a hallmark in neurodegenerative disorders, since a fine-tuned regulation of mTOR activities is crucial for neuron function and survival. RTP801/REDD1/Dig2 has become one of the most puzzling regulators of mTOR. Although the mechanism is not completely understood, RTP801 inactivates mTOR and Akt via the tuberous sclerosis complex (TSC1/TSC2) in many cellular contexts. Intriguingly, RTP801 protects dividing cells from hypoxia or H2O2-induced apoptosis, while it sensitizes differentiated cells to stress. Based on experimental models of Parkinson’s disease (PD), it has been proposed that at early stages of the disease, stress-induced RTP801 upregulation contributes to mTOR repression, in an attempt to maintain cell function and viability. However, if RTP801 elevation is sustained, it leads to neuron cell death by a sequential inhibition of mTOR and Akt. Here, we will review RTP801 deregulation of mTOR in a context of PD and other neurodegenerative disorders.
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Affiliation(s)
- Mercè Canal
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona Barcelona, Catalonia, Spain
| | - Joan Romaní-Aumedes
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona Barcelona, Catalonia, Spain
| | - Núria Martín-Flores
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona Barcelona, Catalonia, Spain
| | - Víctor Pérez-Fernández
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona Barcelona, Catalonia, Spain
| | - Cristina Malagelada
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona Barcelona, Catalonia, Spain
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17
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Marchal JA, Lopez GJ, Peran M, Comino A, Delgado JR, García-García JA, Conde V, Aranda FM, Rivas C, Esteban M, Garcia MA. The impact of PKR activation: from neurodegeneration to cancer. FASEB J 2014; 28:1965-74. [PMID: 24522206 DOI: 10.1096/fj.13-248294] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
An inverse association between cancer and neurodegeneration is plausible because these biological processes share several genes and signaling pathways. Whereas uncontrolled cell proliferation and decreased apoptotic cell death governs cancer, excessive apoptosis contributes to neurodegeneration. Protein kinase R (PKR), an interferon-inducible double-stranded RNA protein kinase, is involved in both diseases. PKR activation blocks global protein synthesis through eIF2α phosphorylation, leading to cell death in response to a variety of cellular stresses. However, PKR also has the dual role of activating the nuclear factor κ-B pathway, promoting cell proliferation. Whereas PKR is recognized for its negative effects on neurodegenerative diseases, in part, inducing high level of apoptosis, the role of PKR activation in cancer remains controversial. In general, PKR is considered to have a tumor suppressor function, and some clinical data show a correlation between suppressed or inactivated PKR and a poor prognosis for several cancers. However, other studies show high PKR expression and activation levels in various cancers, suggesting that PKR might contribute to neoplastic progression. Understanding the cellular factors and signals involved in the regulation of PKR in these age-related diseases is relevant and may have important clinical implications. The present review highlights the current knowledge on the role of PKR in neurodegeneration and cancer, with special emphasis on its regulation and clinical implications.
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Affiliation(s)
- Juan A Marchal
- 1University Hospital Virgen de las Nieves, Azpitarte sn., Granada E-18012, Spain.
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18
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Park CS, Rehrauer H, Mansuy IM. Genome-wide analysis of H4K5 acetylation associated with fear memory in mice. BMC Genomics 2013; 14:539. [PMID: 23927422 PMCID: PMC3751108 DOI: 10.1186/1471-2164-14-539] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 08/03/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Histone acetylation has been implicated in learning and memory in the brain, however, its function at the level of the genome and at individual genetic loci remains poorly investigated. This study examines a key acetylation mark, histone H4 lysine 5 acetylation (H4K5ac), genome-wide and its role in activity-dependent gene transcription in the adult mouse hippocampus following contextual fear conditioning. RESULTS Using ChIP-Seq, we identified 23,235 genes in which H4K5ac correlates with absolute gene expression in the hippocampus. However, in the absence of transcription factor binding sites 150 bp upstream of the transcription start site, genes were associated with higher H4K5ac and expression levels. We further establish H4K5ac as a ubiquitous modification across the genome. Approximately one-third of all genes have above average H4K5ac, of which ~15% are specific to memory formation and ~65% are co-acetylated for H4K12. Although H4K5ac is prevalent across the genome, enrichment of H4K5ac at specific regions in the promoter and coding region are associated with different levels of gene expression. Additionally, unbiased peak calling for genes differentially acetylated for H4K5ac identified 114 unique genes specific to fear memory, over half of which have not previously been associated with memory processes. CONCLUSIONS Our data provide novel insights into potential mechanisms of gene priming and bookmarking by histone acetylation following hippocampal memory activation. Specifically, we propose that hyperacetylation of H4K5 may prime genes for rapid expression following activity. More broadly, this study strengthens the importance of histone posttranslational modifications for the differential regulation of transcriptional programs in cognitive processes.
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Affiliation(s)
- C Sehwan Park
- Department of Health Science and Technology, ETH Zürich, Zürich, Switzerland.
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Trinh MA, Klann E. Translational control by eIF2α kinases in long-lasting synaptic plasticity and long-term memory. Neurobiol Learn Mem 2013; 105:93-9. [PMID: 23707798 DOI: 10.1016/j.nlm.2013.04.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 04/25/2013] [Accepted: 04/25/2013] [Indexed: 01/10/2023]
Abstract
Although the requirement for new protein synthesis in synaptic plasticity and memory has been well established, recent genetic, molecular, electrophysiological, and pharmacological studies have broadened our understanding of the translational control mechanisms that are involved in these processes. One of the critical translational control points mediating general and gene-specific translation depends on the phosphorylation of eukaryotic initiation factor 2 alpha (eIF2α) by four regulatory kinases. Here, we review the literature highlighting the important role for proper translational control via regulation of eIF2α phosphorylation by its kinases in long-lasting synaptic plasticity and long-term memory.
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Affiliation(s)
- Mimi A Trinh
- Pharmaceutical Research Division, CNS Drug Discovery Unit, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa 251-8555, Japan
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Abstract
The double-stranded RNA-dependent protein kinase PKR plays multiple roles in cells, in response to different stress situations. As a member of the interferon (IFN)‑Stimulated Genes, PKR was initially recognized as an actor in the antiviral action of IFN, due to its ability to control translation, through phosphorylation, of the alpha subunit of eukaryotic initiation factor 2 (eIF2α). As such, PKR participates in the generation of stress granules, or autophagy and a number of viruses have designed strategies to inhibit its action. However, PKR deficient mice resist most viral infections, indicating that PKR may play other roles in the cell other than just acting as an antiviral agent. Indeed, PKR regulates several signaling pathways, either as an adapter protein and/or using its kinase activity. Here we review the role of PKR as an eIF2α kinase, its participation in the regulation of the NF-κB, p38MAPK and insulin pathways, and we focus on its role during infection with the hepatitis C virus (HCV). PKR binds the HCV IRES RNA, cooperates with some functions of the HCV core protein and may represent a target for NS5A or E2. Novel data points out for a role of PKR as a pro-HCV agent, both as an adapter protein and as an eIF2α-kinase, and in cooperation with the di-ubiquitin-like protein ISG15. Developing pharmaceutical inhibitors of PKR may help in resolving some viral infections as well as stress-related damages.
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Affiliation(s)
- Stéphanie Dabo
- Unit Hepacivirus and Innate Immunity, Department Virology, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France.
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Tan M, Wang S, Song J, Jia J. Combination of p53(ser15) and p21/p21(thr145) in peripheral blood lymphocytes as potential Alzheimer's disease biomarkers. Neurosci Lett 2012; 516:226-31. [PMID: 22503900 DOI: 10.1016/j.neulet.2012.03.093] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 03/29/2012] [Accepted: 03/30/2012] [Indexed: 01/20/2023]
Abstract
Alzheimer's disease (AD) is still difficult to be precisely diagnosed in its early stage to date. Establishing of reliable and manageable disease-specific biological markers is required to improve diagnostic accuracy. Based on the hypothesis of cell cycle regulatory failure at the early stage of AD, we tested whether cell cycle regulating proteins p53, p21 and their phosphorylated forms p53(ser15), p21(thr145) were changed in AD patients and whether these proteins could be used as diagnostic biomarkers. Western bolt, Enzyme-linked immunosorbent assay (ELISA), immunofluorescent staining and flow cytometry (FCM) analysis were employed to analyze levels of these proteins in peripheral blood lymphocytes (PBLs) from 95 controls, 94 AD, 12 Parkinson's disease (PD) and 15 vascular dementia (VaD) patients. Compared with controls, p53(ser15) and p21(thr145) levels were significantly increased and p21 level was significantly decreased in PBLs of AD patients but not in PD or VaD, while p53 was increased in both AD and VaD patients. The receiver operating characteristic (ROC) curve analysis showed that the specificity and sensitivity were 76% and 84% for p53, 88% and 82% for p53(ser15), 80% and 75% for p21 and 84% and 68% for p21(thr145) in identifying AD patients. The relatively high diagnostic accuracy support these proteins, especially p53(ser15) and p21 in PBLs may become potential biomarkers for diagnosis of AD.
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Affiliation(s)
- Mengshan Tan
- Department of Neurology, Xuan Wu Hospital of the Capital Medical University, Beijing 100053, China
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Cai Z, Yan LJ, Li K, Quazi SH, Zhao B. Roles of AMP-activated protein kinase in Alzheimer's disease. Neuromolecular Med 2012; 14:1-14. [PMID: 22367557 DOI: 10.1007/s12017-012-8173-2] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Accepted: 02/04/2012] [Indexed: 12/22/2022]
Abstract
AMP-activated protein kinase (AMPK), a master regulator of cellular energy homeostasis and a central player in glucose and lipid metabolism, is potentially implicated in the pathogenesis of Alzheimer's disease (AD). AMPK activity decreases in AD brain, indicating decreased mitochondrial biogenesis and function. Emerging evidence demonstrates that AMPK activation is a potential target for improving perturbed brain energy metabolism that is involved in the pathogenesis of AD. The roles of AMPK in the pathogenesis of AD include β-amyloid protein (Aβ) generation and tau phosphorylation. In particular, AMPK may regulate Aβ generation through modulating neuronal cholesterol and sphingomyelin levels and through regulating APP distribution in the lipid rafts. AMPK is activated by phosphorylation of Thr-172 by LKB1 complex in response to increase in the AMP/ATP ratio and by calmodulin-dependent protein kinase kinase-beta in response to elevated Ca(2+) levels, which contributes to regulating Aβ generation. AMPK is a physiological tau kinase and can increase the phosphorylation of tau at Ser-262. AMPK can also directly phosphorylate tau at Thr-231 and Ser-396/404. Furthermore, AMPK activation decreases mTOR signaling activity to facilitate autophagy and promotes lysosomal degradation of Aβ. However, AMPK activation has non-neuroprotective property and may lead to detrimental outcomes, including Aβ generation and tau phosphorylation. Therefore, it is still unclear whether AMPK could serve a potential therapeutic target for AD, and hence, further studies will be needed to clarify the role of AMPK in AD.
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Affiliation(s)
- Zhiyou Cai
- Department of Neurology, The Affiliated Hospital of Guangdong Medical College, District of Xiashan, Zhanjiang 524001, Guangdong, People's Republic of China
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Mammalian target of rapamycin: A valid therapeutic target through the autophagy pathway for alzheimer's disease? J Neurosci Res 2012; 90:1105-18. [DOI: 10.1002/jnr.23011] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 10/28/2011] [Accepted: 11/18/2011] [Indexed: 12/15/2022]
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Couturier J, Morel M, Pontcharraud R, Gontier V, Fauconneau B, Paccalin M, Page G. Interaction of double-stranded RNA-dependent protein kinase (PKR) with the death receptor signaling pathway in amyloid beta (Abeta)-treated cells and in APPSLPS1 knock-in mice. J Biol Chem 2010; 285:1272-82. [PMID: 19889624 PMCID: PMC2801255 DOI: 10.1074/jbc.m109.041954] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 10/27/2009] [Indexed: 01/05/2023] Open
Abstract
For 10 years, research has focused on signaling pathways controlling translation to explain neuronal death in Alzheimer Disease (AD). Previous studies demonstrated in different cellular and animal models and AD patients that translation is down-regulated by the activation of double-stranded RNA-dependent protein kinase (PKR). Among downstream factors of PKR, the Fas-associated protein with a death domain (FADD) and subsequent activated caspase-8 are responsible for PKR-induced apoptosis in recombinant virus-infected cells. However, no studies have reported the role of PKR in death receptor signaling in AD. The aim of this project is to determine physical and functional interactions of PKR with FADD in amyloid-beta peptide (Abeta) neurotoxicity and in APP(SL)PS1 KI transgenic mice. In SH-SY5Y cells, results showed that Abeta42 induced a large increase in phosphorylated PKR and FADD levels and a physical interaction between PKR and FADD in the nucleus, also observed in the cortex of APP(SL)PS1 KI mice. However, PKR gene silencing or treatment with a specific PKR inhibitor significantly prevented the increase in pT(451)-PKR and pS(194)-FADD levels in SH-SY5Y nuclei and completely inhibited activities of caspase-3 and -8. The contribution of PKR in neurodegeneration through the death receptor signaling pathway may support the development of therapeutics targeting PKR to limit neuronal death in AD.
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Affiliation(s)
- Julien Couturier
- From the Research Group on Brain Aging, GReViC EA 3808, University of Poitiers, 6 rue de la Milétrie, BP 199, 86034 Poitiers Cedex, France
| | - Milena Morel
- From the Research Group on Brain Aging, GReViC EA 3808, University of Poitiers, 6 rue de la Milétrie, BP 199, 86034 Poitiers Cedex, France
| | - Raymond Pontcharraud
- From the Research Group on Brain Aging, GReViC EA 3808, University of Poitiers, 6 rue de la Milétrie, BP 199, 86034 Poitiers Cedex, France
| | - Virginie Gontier
- From the Research Group on Brain Aging, GReViC EA 3808, University of Poitiers, 6 rue de la Milétrie, BP 199, 86034 Poitiers Cedex, France
| | - Bernard Fauconneau
- From the Research Group on Brain Aging, GReViC EA 3808, University of Poitiers, 6 rue de la Milétrie, BP 199, 86034 Poitiers Cedex, France
| | - Marc Paccalin
- From the Research Group on Brain Aging, GReViC EA 3808, University of Poitiers, 6 rue de la Milétrie, BP 199, 86034 Poitiers Cedex, France
- the Department of Geriatrics, Poitiers University Hospital, 2 rue de la Milétrie, BP 577, 86021 Poitiers Cedex, France, and
- the Clinical Investigation Center, CIC INSERM 802, Poitiers University Hospital, Poitiers, France
| | - Guylène Page
- From the Research Group on Brain Aging, GReViC EA 3808, University of Poitiers, 6 rue de la Milétrie, BP 199, 86034 Poitiers Cedex, France
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Morel M, Couturier J, Lafay-Chebassier C, Paccalin M, Page G. PKR, the double stranded RNA-dependent protein kinase as a critical target in Alzheimer's disease. J Cell Mol Med 2009; 13:1476-88. [PMID: 19602051 PMCID: PMC3828860 DOI: 10.1111/j.1582-4934.2009.00849.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Amyloid β-peptide (Aβ) deposits and neurofibrillary tangles are key hallmarks in Alzheimer's disease (AD). Aβ stimulates many signal transducers involved in the neuronal death. However, many mechanisms remain to be elucidated because no definitive therapy of AD exists. Some studies have focused on the control of translation which involves eIF2 and eIF4E, main eukaryotic factors of initiation. The availability of these factors depends on the activation of the double-stranded RNA-dependent protein kinase (PKR) and the mammalian target of rapamycin (mTOR), respectively. mTOR positively regulates the translation while PKR results in a protein synthesis shutdown. Many studies demonstrated that the PKR signalling pathway is up-regulated in cellular and animal models of AD and in the brain of AD patients. Interestingly, our results showed that phosphorylated PKR and eIF2α levels were significantly increased in lymphocytes of AD patients. These modifications were significantly correlated with cognitive and memory test scores performed in AD patients. On the contrary, the mTOR signalling pathway is down-regulated in cellular and animal models of AD. Recently, we showed that p53, regulated protein in development and DNA damage response 1 and tuberous sclerosis complex 2 could represent molecular links between PKR and mTOR signalling pathways. PKR could be an early biomarker of the neuronal death and a critical target for a therapeutic programme in AD.
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Affiliation(s)
- Milena Morel
- Research Group on Brain Aging (EA 3808) University of Poitiers, Poitiers Cedex, France
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