51
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Franich NR, Basso M, André EA, Ochaba J, Kumar A, Thein S, Fote G, Kachemov M, Lau AL, Yeung SY, Osmand A, Zeitlin SO, Ratan RR, Thompson LM, Steffan JS. Striatal Mutant Huntingtin Protein Levels Decline with Age in Homozygous Huntington's Disease Knock-In Mouse Models. J Huntingtons Dis 2019; 7:137-150. [PMID: 29843246 PMCID: PMC6002862 DOI: 10.3233/jhd-170274] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Background: Huntington’s disease (HD) is a progressive neurodegenerative disorder associated with aging, caused by an expanded polyglutamine (polyQ) repeat within the Huntingtin (HTT) protein. In HD, degeneration of the striatum and atrophy of the cortex are observed while cerebellum is less affected. Objective: To test the hypothesis that HTT protein levels decline with age, which together with HTT mutation could influence disease progression. Methods: Using whole brain cell lysates, a unique method of SDS-PAGE and western analysis was used to quantitate HTT protein, which resolves as a monomer and as a high molecular weight species that is modulated by the presence of transglutaminase 2. HTT levels were measured in striatum, cortex and cerebellum in congenic homozygous Q140 and HdhQ150 knock-in mice and WT littermate controls. Results: Mutant HTT in both homozygous knock-in HD mouse models and WT HTT in control striatal and cortical tissues significantly declined in a progressive manner over time. Levels of mutant HTT in HD cerebellum remained high during aging. Conclusions: A general decline in mutant HTT levels in striatum and cortex is observed that may contribute to disease progression in homozygous knock-in HD mouse models through reduction of HTT function. In cerebellum, sustained levels of mutant HTT with aging may be protective to this tissue which is less overtly affected in HD.
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Affiliation(s)
- Nicholas R Franich
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Manuela Basso
- Centre for Integrative Biology, University of Trento, Trento, Italy
| | - Emily A André
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Joseph Ochaba
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA
| | - Amit Kumar
- Burke Medical Research Institute, White Plains, NY, USA.,Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY, USA.,Department of Neurology, Weill Medical College of Cornell University, New York, NY, USA
| | - Soe Thein
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - Gianna Fote
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - Marketta Kachemov
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA
| | - Alice L Lau
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - Sylvia Y Yeung
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - Alexander Osmand
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
| | - Scott O Zeitlin
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Rajiv R Ratan
- Burke Medical Research Institute, White Plains, NY, USA.,Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY, USA.,Department of Neurology, Weill Medical College of Cornell University, New York, NY, USA
| | - Leslie M Thompson
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA.,Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA.,Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, USA
| | - Joan S Steffan
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA.,Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, USA
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52
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Abstract
Huntingtin (HTT) is a scaffold protein mostly known because it gives rise to the severe and incurable inherited neurological disorder Huntington’s disease (HD) when mutated. The Huntingtin gene (HTT) carries a polymorphic trinucleotide expansion of CAGs in exon 1 that ranges from 9 to 35 in the non-HD affected population. However, if it exceeds 35 CAG repeats, the altered protein is referred to as mutant HTT and leads to the development of HD. Given the wide spectrum of severe symptoms developed by HD individuals, wild-type and mutant HTT have been mostly studied in the context of this disorder. However, HTT expression is ubiquitous and several peripheral symptoms in HD have been described, suggesting that HTT is of importance, not only in the central nervous system (CNS), but also in peripheral organs. Accordingly, HTT and mutant HTT may interfere with non-brain-related diseases. Correlative studies have highlighted a decreased cancer incidence in the HD population and both wild-type and mutant HTT have been implicated in tumor progression. In this review, we describe the current evidence linking wild-type and mutant HTT to cancer and discuss how CAG polymorphism, HTT function, and partners may influence carcinogenesis and metastatic progression.
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Affiliation(s)
- Morgane Sonia Thion
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris Cedex 05, France
| | - Sandrine Humbert
- Grenoble Institut des Neurosciences, GIN, Univ. Grenoble Alpes, Grenoble, France.,INSERM, U1216, Grenoble, France
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53
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Aktar F, Burudpakdee C, Polanco M, Pei S, Swayne TC, Lipke PN, Emtage L. The huntingtin inclusion is a dynamic phase-separated compartment. Life Sci Alliance 2019; 2:2/5/e201900489. [PMID: 31527136 PMCID: PMC6749095 DOI: 10.26508/lsa.201900489] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 08/22/2019] [Accepted: 09/02/2019] [Indexed: 12/17/2022] Open
Abstract
Inclusions of disordered protein are a characteristic feature of most neurodegenerative diseases, including Huntington's disease. Huntington's disease is caused by expansion of a polyglutamine tract in the huntingtin protein; mutant huntingtin protein (mHtt) is unstable and accumulates in large intracellular inclusions both in affected individuals and when expressed in eukaryotic cells. Using mHtt-GFP expressed in Saccharomyces cerevisiae, we find that mHtt-GFP inclusions are dynamic, mobile, gel-like structures that concentrate mHtt together with the disaggregase Hsp104. Although inclusions may associate with the vacuolar membrane, the association is reversible and we find that inclusions of mHtt in S. cerevisiae are not taken up by the vacuole or other organelles. Instead, a pulse-chase study using photoconverted mHtt-mEos2 revealed that mHtt is directly and continuously removed from the inclusion body. In addition to mobile inclusions, we also imaged and tracked the movements of small particles of mHtt-GFP and determine that they move randomly. These observations suggest that inclusions may grow through the collision and coalescence of small aggregative particles.
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Affiliation(s)
- Fahmida Aktar
- Biology Department, City University of New York, York College, Queens, NY, USA
| | | | - Mercedes Polanco
- Biology Department, City University of New York, York College, Queens, NY, USA
| | - Sen Pei
- Biology Department, City University of New York, York College, Queens, NY, USA
| | - Theresa C Swayne
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA
| | - Peter N Lipke
- Biology Department, City University of New York, Brooklyn College, Brooklyn, NY, USA.,Molecular, Cellular and Developmental Biology Program, City University of New York Graduate Center, New York, NY, USA
| | - Lesley Emtage
- Biology Department, City University of New York, York College, Queens, NY, USA .,Molecular, Cellular and Developmental Biology Program, City University of New York Graduate Center, New York, NY, USA
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54
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Tang RH, Qi RQ, Liu HY. Interleukin-4 affects microglial autophagic flux. Neural Regen Res 2019; 14:1594-1602. [PMID: 31089059 PMCID: PMC6557092 DOI: 10.4103/1673-5374.255975] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 02/24/2019] [Indexed: 12/15/2022] Open
Abstract
Interleukin-4 plays an important protective role in Alzheimer's disease by regulating microglial phenotype, phagocytosis of amyloid-β, and secretion of anti-inflammatory and neurotrophic cytokines. Recently, increasing evidence has suggested that autophagy regulates innate immunity by affecting M1/M2 polarization of microglia/macrophages. However, the role of interleukin-4 in microglial autophagy is unknown. In view of this, BV2 microglia were treated with 0, 10, 20 or 50 ng/mL interleukin-4 for 24, 48, or 72 hours. Subsequently, light chain 3-II and p62 protein expression levels were detected by western blot assay. BV2 microglia were incubated with interleukin-4 (20 ng/mL, experimental group), 3-methyladenine (500 μM, autophagy inhibitor, negative control group), rapamycin (100 nM, autophagy inductor, positive control group), 3-methyladenine + interleukin-4 (rescue group), or without treatment for 24 hours, and then exposed to amyloid-β (1 μM, model group) or vehicle control (control) for 24 hours. LC3-II and p62 protein expression levels were again detected by western blot assay. In addition, expression levels of multiple markers of M1 and M2 phenotype were assessed by real-time fluorescence quantitative polymerase chain reaction, while intracellular and supernatant amyloid-β protein levels were measured by enzyme-linked immunosorbent assay. Our results showed that interleukin-4 induced microglial autophagic flux, most significantly at 20 ng/mL for 48 hours. Interleukin-4 pretreated microglia inhibited blockade of amyloid-β-induced autophagic flux, and promoted amyloid-β uptake and degradation partly through autophagic flux, but inhibited switching of amyloid-β-induced M1 phenotype independent on autophagic flux. These results indicate that interleukin-4 pretreated microglia increases uptake and degradation of amyloid-β in a process partly mediated by autophagy, which may play a protective role against Alzheimer's disease.
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Affiliation(s)
- Run-Hong Tang
- Department of Neurology, the First Hospital of China Medical University, Shenyang, Liaoning Province, China
| | - Rui-Qun Qi
- Department of Dermatology, Key Laboratory of Immunodermatology, the First Hospital of China Medical University, Shenyang, Liaoning Province, China
| | - Hua-Yan Liu
- Department of Neurology, the First Hospital of China Medical University, Shenyang, Liaoning Province, China
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55
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Liu J, Yao Q, Xiao L, Ma W, Li F, Lai B, Wang N. PPARγ induces NEDD4 gene expression to promote autophagy and insulin action. FEBS J 2019; 287:529-545. [PMID: 31423749 DOI: 10.1111/febs.15042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/24/2019] [Accepted: 08/16/2019] [Indexed: 12/28/2022]
Abstract
The E3 ubiquitin ligase neural precursor cell-expressed developmentally down-regulated protein 4 (NEDD4) plays a crucial role in governing a number of signaling pathways, including insulin and autophagy signaling. However, the molecular mechanism by which NEDD4 gene is transcriptionally regulated has not been fully elucidated. Here, we reported that NEDD4 mRNA and protein levels were increased by peroxisome proliferator-activated receptor-γ (PPARγ) in HepG2 hepatocytes. PPARγ antagonist GW9662 abolished thiazolidinedione (TZD)-induced NEDD4 expression. ChIP and luciferase reporter assays showed that PPARγ directly bound to the potential PPAR-responsive elements (PPREs) within the promoter region of the human NEDD4 gene. In addition, TZDs increased Akt phosphorylation and glucose uptake, which were abrogated through NEDD4 depletion. Furthermore, we showed that NEDD4-mediated autophagy induction and Akt phosphorylation were suppressed by oleic acid and high glucose treatment, activation of PPARγ successfully prevented this suppression. In conclusion, these results suggest that PPARγ plays a novel role in linking glucose metabolism and protein homeostasis through NEDD4-mediated effects on the autophagy machinery.
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Affiliation(s)
- Jia Liu
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, China
| | - Qinyu Yao
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, China
| | - Lei Xiao
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, China
| | - Wen Ma
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, China
| | - Fan Li
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, China
| | - Baochang Lai
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, China
| | - Nanping Wang
- Advanced Institute for Medical Sciences, Dalian Medical University, China
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56
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Metformin treatment reduces motor and neuropsychiatric phenotypes in the zQ175 mouse model of Huntington disease. Exp Mol Med 2019; 51:1-16. [PMID: 31165723 PMCID: PMC6549163 DOI: 10.1038/s12276-019-0264-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Huntington disease is a neurodegenerative condition for which there is no cure to date. Activation of AMP-activated protein kinase has previously been shown to be beneficial in in vitro and in vivo models of Huntington’s disease. Moreover, a recent cross-sectional study demonstrated that treatment with metformin, a well-known activator of this enzyme, is associated with better cognitive scores in patients with this disease. We performed a preclinical study using metformin to treat phenotypes of the zQ175 mouse model of Huntington disease. We evaluated behavior (motor and neuropsychiatric function) and molecular phenotypes (aggregation of mutant huntingtin, levels of brain-derived neurotrophic factor, neuronal inflammation, etc.). We also used two models of polyglutamine toxicity in Caenorhabditis elegans to further explore potential mechanisms of metformin action. Our results provide strong evidence that metformin alleviates motor and neuropsychiatric phenotypes in zQ175 mice. Moreover, metformin intake reduces the number of nuclear aggregates of mutant huntingtin in the striatum. The expression of brain-derived neurotrophic factor, which is reduced in mutant animals, is partially restored in metformin-treated mice, and glial activation in mutant mice is reduced in metformin-treated animals. In addition, using worm models of polyglutamine toxicity, we demonstrate that metformin reduces polyglutamine aggregates and restores neuronal function through mechanisms involving AMP-activated protein kinase and lysosomal function. Our data indicate that metformin alleviates the progression of the disease and further supports AMP-activated protein kinase as a druggable target against Huntington’s disease. Metformin, an existing drug for diabetes, shows promise in alleviating symptoms of early Huntington’s disease in mouse models. Huntington’s disease is a genetic disorder that results in the gradual deterioration of motor skills and cognitive ability. It is caused by a defect in a single gene that then encodes a mutant huntingtin protein, which aggregates and kills brain cells. Growing observational evidence suggests that patients undergoing metformin treatment for diabetes type II exhibit fewer symptoms of age-related disease, as well as Huntington’s disease. Rafael Vázquez-Manrique at Hospital Universitario y Politécnico La Fe, València and Pascual Sanz at IBV-CSIC and CIBERER, València, and scientists across Spain used metformin to treat motor and neuropsychiatric symptoms in a Huntington’s mouse model. They found that metformin alleviated symptoms by actively reducing huntingtin levels, dispersing aggregations and limiting brain inflammation.
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57
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Ochaba J, Fote G, Kachemov M, Thein S, Yeung SY, Lau AL, Hernandez S, Lim RG, Casale M, Neel MJ, Monuki ES, Reidling J, Housman DE, Thompson LM, Steffan JS. IKKβ slows Huntington's disease progression in R6/1 mice. Proc Natl Acad Sci U S A 2019; 116:10952-10961. [PMID: 31088970 PMCID: PMC6561205 DOI: 10.1073/pnas.1814246116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Neuroinflammation is an important contributor to neuronal pathology and death in neurodegenerative diseases and neuronal injury. Therapeutic interventions blocking the activity of the inflammatory kinase IKKβ, a key regulator of neuroinflammatory pathways, is protective in several animal models of neurodegenerative disease and neuronal injury. In Huntington's disease (HD), however, significant questions exist as to the impact of blocking or diminishing the activity of IKKβ on HD pathology given its potential role in Huntingtin (HTT) degradation. In cell culture, IKKβ phosphorylates HTT serine (S) 13 and activates HTT degradation, a process that becomes impaired with polyQ expansion. To investigate the in vivo relationship of IKKβ to HTT S13 phosphorylation and HD progression, we crossed conditional tamoxifen-inducible IKKβ knockout mice with R6/1 HD mice. Behavioral assays in these mice showed a significant worsening of HD pathological phenotypes. The increased behavioral pathology correlated with reduced levels of endogenous mouse full-length phospho-S13 HTT, supporting the importance of IKKβ in the phosphorylation of HTT S13 in vivo. Notably, many striatal autophagy genes were up-regulated in HD vs. control mice; however, IKKβ knockout partially reduced this up-regulation in HD, increased striatal neurodegeneration, and enhanced an activated microglial response. We propose that IKKβ is protective in striatal neurons early in HD progression via phosphorylation of HTT S13. As IKKβ is also required for up-regulation of some autophagy genes and HTT is a scaffold for selective autophagy, IKKβ may influence autophagy through multiple mechanisms to maintain healthy striatal function, thereby reducing neuronal degeneration to slow HD onset.
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Affiliation(s)
- Joseph Ochaba
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697
| | - Gianna Fote
- Department of Biological Chemistry, University of California, Irvine, CA 92697
| | - Marketta Kachemov
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697
| | - Soe Thein
- Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92697
| | - Sylvia Y Yeung
- Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92697
| | - Alice L Lau
- Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92697
| | - Sarah Hernandez
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697
- Sue and Bill Gross Stem Cell Center, University of California, Irvine, CA 92697
| | - Ryan G Lim
- Department of Biological Chemistry, University of California, Irvine, CA 92697
- Sue and Bill Gross Stem Cell Center, University of California, Irvine, CA 92697
| | - Malcolm Casale
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697
| | - Michael J Neel
- Department of Pathology & Laboratory Medicine, University of California, Irvine, CA 92697
| | - Edwin S Monuki
- Department of Pathology & Laboratory Medicine, University of California, Irvine, CA 92697
| | - Jack Reidling
- Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697
| | - David E Housman
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139;
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Leslie M Thompson
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697
- Department of Biological Chemistry, University of California, Irvine, CA 92697
- Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92697
- Sue and Bill Gross Stem Cell Center, University of California, Irvine, CA 92697
- Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697
| | - Joan S Steffan
- Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92697;
- Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697
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58
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Bar-Yosef T, Damri O, Agam G. Dual Role of Autophagy in Diseases of the Central Nervous System. Front Cell Neurosci 2019; 13:196. [PMID: 31191249 PMCID: PMC6548059 DOI: 10.3389/fncel.2019.00196] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 04/18/2019] [Indexed: 12/14/2022] Open
Abstract
Autophagy is a vital lysosomal degradation and recycling pathway in the eukaryotic cell, responsible for maintaining an intricate balance between cell survival and cell death, necessary for neuronal survival and function. This dual role played by autophagy raises the question whether this process is a protective or a destructive pathway, the contributor of neuronal cell death or a failed attempt to repair aberrant processes? Deregulated autophagy at different steps of the pathway, whether excessive or downregulated, has been proposed to be associated with neurodegenerative disorders such as Alzheimer's-, Huntington's-, and Parkinson's-disease, known for their intracellular accumulation of protein aggregates. Recent observations of impaired autophagy also appeared in psychiatric disorders such as schizophrenia and bipolar disorder suggesting an additional contribution to the pathophysiology of mental illness. Here we review the current understanding of autophagy's role in various neuropsychiatric disorders and, hitherto, the prevailing new potential autophagy-related therapeutic strategies for their treatment.
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Affiliation(s)
- Tamara Bar-Yosef
- Department of Clinical Biochemistry and Pharmacology and Psychiatry Research Unit, Faculty of Health Sciences, Ben-Gurion University of the Negev and Mental Health Center, Beersheba, Israel
| | - Odeya Damri
- Department of Clinical Biochemistry and Pharmacology and Psychiatry Research Unit, Faculty of Health Sciences, Ben-Gurion University of the Negev and Mental Health Center, Beersheba, Israel
| | - Galila Agam
- Department of Clinical Biochemistry and Pharmacology and Psychiatry Research Unit, Faculty of Health Sciences, Ben-Gurion University of the Negev and Mental Health Center, Beersheba, Israel
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59
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de Mello NP, Orellana AM, Mazucanti CH, de Morais Lima G, Scavone C, Kawamoto EM. Insulin and Autophagy in Neurodegeneration. Front Neurosci 2019; 13:491. [PMID: 31231176 PMCID: PMC6558407 DOI: 10.3389/fnins.2019.00491] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 04/29/2019] [Indexed: 12/12/2022] Open
Abstract
Crosstalk in the pathophysiological processes underpinning metabolic diseases and neurodegenerative disorders have been the subject of extensive investigation, in which insulin signaling and autophagy impairment demonstrate to be a common factor in both conditions. Although it is still somewhat conflicting, pharmacological and genetic strategies that regulate these pathways may be a promising approach for aggregate protein clearancing and consequently the delaying of onset or progression of the disease. However, as the response due to this modulation seems to be time-dependent, finding the right regulation of autophagy may be a potential target for drug development for neurodegenerative diseases. In this way, this review focuses on the role of insulin signaling/resistance and autophagy in some neurodegenerative diseases, discussing pharmacological and non-pharmacological interventions in these diseases.
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Affiliation(s)
- Natália Prudente de Mello
- Laboratory of Molecular and Functional Neurobiology, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Ana Maria Orellana
- Laboratory of Molecular Neuropharmacology, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Caio Henrique Mazucanti
- Laboratory of Molecular Neuropharmacology, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Geovanni de Morais Lima
- Laboratory of Molecular and Functional Neurobiology, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Cristoforo Scavone
- Laboratory of Molecular Neuropharmacology, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Elisa Mitiko Kawamoto
- Laboratory of Molecular and Functional Neurobiology, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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60
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Di Pardo A, Pepe G, Castaldo S, Marracino F, Capocci L, Amico E, Madonna M, Giova S, Jeong SK, Park BM, Park BD, Maglione V. Stimulation of Sphingosine Kinase 1 (SPHK1) Is Beneficial in a Huntington's Disease Pre-clinical Model. Front Mol Neurosci 2019; 12:100. [PMID: 31068790 PMCID: PMC6491579 DOI: 10.3389/fnmol.2019.00100] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 04/03/2019] [Indexed: 12/19/2022] Open
Abstract
Although several agents have been identified to provide therapeutic benefits in Huntington disease (HD), the number of conventionally used treatments remains limited and only symptomatic. Thus, it is plausible that the need to identify new therapeutic targets for the development of alternative and more effective treatments is becoming increasingly urgent. Recently, the sphingosine-1-phosphate (S1P) axis has been reported to be a valid potential novel molecular target for therapy development in HD. Modulation of aberrant metabolism of S1P in HD has been proved to exert neuroprotective action in vitro settings including human HD iPSC-derived neurons. In this study, we investigated whether promoting S1P production by stimulating Sphingosine Kinase 1 (SPHK1) by the selective activator, K6PC-5, may have therapeutic benefit in vivo in R6/2 HD mouse model. Our findings indicate that chronic administration of 0.05 mg/kg K6PC-5 exerted an overall beneficial effect in R6/2 mice. It significantly slowed down the progressive motor deficit associated with disease progression, modulated S1P metabolism, evoked the activation of pro-survival pathways and markedly reduced the toxic mutant huntingtin (mHtt) aggregation. These results suggest that K6PC-5 may represent a future therapeutic option in HD and may potentially counteract the perturbed brain function induced by deregulated S1P pathways.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Se Kyoo Jeong
- Department of Cosmetic Science, Seowon University, Cheongju, South Korea
| | - Bu-Mahn Park
- NeoPharm USA Inc., Engelwood Cliffs, NJ, United States
| | - Byeong Deog Park
- Dr. Raymond Laboratories, Inc., Englewood Cliffs, NJ, United States
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61
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Eskelinen EL. Autophagy: Supporting cellular and organismal homeostasis by self-eating. Int J Biochem Cell Biol 2019; 111:1-10. [PMID: 30940605 DOI: 10.1016/j.biocel.2019.03.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/25/2019] [Accepted: 03/29/2019] [Indexed: 01/07/2023]
Abstract
Autophagy is a conserved catabolic process that delivers cytoplasmic components and organelles to lysosomes for degradation and recycling. This pathway serves to degrade nonfunctional organelles and aggregate-prone proteins, as well as to produce substrates for energy production and biosynthesis. Autophagy is especially important for the maintenance of stem cells, and for the survival and homeostasis of post-mitotic cells like neurons. Functional autophagy promotes longevity in several model organisms. Autophagy regulates immunity and inflammation at several levels and has both anti- and pro-tumorigenic roles in cancer. This review provides a concise overview of autophagy and its importance in cellular and organismal homeostasis, with emphasis on aging, stem cells, neuronal cells, immunity, inflammation, and cancer.
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Affiliation(s)
- Eeva-Liisa Eskelinen
- University of Turku, Institute of Biomedicine, Turku, Finland; University of Helsinki, Molecular and Integrative Biosciences Research Programme, Helsinki, Finland.
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62
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Eenjes E, Yang-Klingler YJ, Yamamoto A. Monitoring Aggregate Clearance and Formation in Cell-Based Assays. Methods Mol Biol 2019; 1873:157-169. [PMID: 30341608 DOI: 10.1007/978-1-4939-8820-4_9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Understanding the fundamental mechanism underlying the accumulation and clearance of misfolded proteins can lead to insights into the synthetic and degradative pathways that maintain the homeostasis of proteins in all cells. Given the interconnection between protein homeostasis and cell health, as well as the complexity of aggregate formation and the degradation pathways with which it is intertwined, the design of the tools that are used to examine protein aggregation and accumulation can have a profound impact on the interpretation of results. We rely on two previously published stable cell lines that use conditional expression and the ligand-receptor tag known as HaloTag, to temporally distinguish distinct pools of aggregates, and use a combination of biochemical- and imaging-based methods to measure aggregation of a canonical aggregation-prone protein. We measure aggregate load biochemically using Filter Trap Analysis, which combines a filter trap retardation assay and immunoblotting to measure detergent soluble and insoluble protein levels, and visually, using confocal microscopy to monitor simultaneously aggregate formation and growth events in the background of aggregate clearance. As a secondary screen to more simplistic screen based approaches, this method permits further insight into how aggregate load is affected.
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Affiliation(s)
- Evelien Eenjes
- Department of Neurology, Columbia University, New York, NY, USA
- Department of Pediatric Surgery, Erasmus Medical Center-Sophia Children's Hospital, Rotterdam, The Netherlands
| | | | - Ai Yamamoto
- Department of Neurology, Columbia University, New York, NY, USA.
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.
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63
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Li XG, Du JH, Lu Y, Lin XJ. Neuroprotective effects of rapamycin on spinal cord injury in rats by increasing autophagy and Akt signaling. Neural Regen Res 2019; 14:721-727. [PMID: 30632514 PMCID: PMC6352584 DOI: 10.4103/1673-5374.247476] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Rapamycin treatment has been shown to increase autophagy activity and activate Akt phosphorylation, suppressing apoptosis in several models of ischemia reperfusion injury. However, little has been studied on the neuroprotective effects on spinal cord injury by activating Akt phosphorylation. We hypothesized that both effects of rapamycin, the increased autophagy activity and Akt signaling, would contribute to its neuroprotective properties. In this study, a compressive spinal cord injury model of rat was created by an aneurysm clip with a 30 g closing force. Rat models were intraperitoneally injected with rapamycin 1 mg/kg, followed by autophagy inhibitor 3-methyladenine 2.5 mg/kg and Akt inhibitor IV 1 µg/kg. Western blot assay, immunofluorescence staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay were used to observe the expression of neuronal autophagy molecule Beclin 1, apoptosis-related molecules Bcl-2, Bax, cytochrome c, caspase-3 and Akt signaling. Our results demonstrated that rapamycin inhibited the expression of mTOR in injured spinal cord tissue and up-regulated the expression of Beclin 1 and phosphorylated-Akt. Rapamycin prevented the decrease of bcl-2 expression in injured spinal cord tissue, reduced Bax, cytochrome c and caspase-3 expression levels and reduced the number of apoptotic neurons in injured spinal cord tissue 24 hours after spinal cord injury. 3-Methyladenine and Akt inhibitor IV intervention suppressed the expression of Beclin-1 and phosphorylated-Akt in injured spinal cord tissue and reduced the protective effect of rapamycin on apoptotic neurons. The above results indicate that the neuroprotective effect of rapamycin on spinal cord injury rats can be achieved by activating autophagy and the Akt signaling pathway.
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Affiliation(s)
- Xi-Gong Li
- Department of Orthopedic Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
| | - Jun-Hua Du
- Department of Orthopedic Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
| | - Yang Lu
- Department of Orthopedic Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
| | - Xiang-Jin Lin
- Department of Orthopedic Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
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64
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Hong H, Koon AC, Chen ZS, Wei Y, An Y, Li W, Lau MHY, Lau KF, Ngo JCK, Wong CH, Au-Yeung HY, Zimmerman SC, Chan HYE. AQAMAN, a bisamidine-based inhibitor of toxic protein inclusions in neurons, ameliorates cytotoxicity in polyglutamine disease models. J Biol Chem 2018; 294:2757-2770. [PMID: 30593503 DOI: 10.1074/jbc.ra118.006307] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/26/2018] [Indexed: 01/30/2023] Open
Abstract
Polyglutamine (polyQ) diseases are a group of dominantly inherited neurodegenerative disorders caused by the expansion of an unstable CAG repeat in the coding region of the affected genes. Hallmarks of polyQ diseases include the accumulation of misfolded protein aggregates, leading to neuronal degeneration and cell death. PolyQ diseases are currently incurable, highlighting the urgent need for approaches that inhibit the formation of disaggregate cytotoxic polyQ protein inclusions. Here, we screened for bisamidine-based inhibitors that can inhibit neuronal polyQ protein inclusions. We demonstrated that one inhibitor, AQAMAN, prevents polyQ protein aggregation and promotes de-aggregation of self-assembled polyQ proteins in several models of polyQ diseases. Using immunocytochemistry, we found that AQAMAN significantly reduces polyQ protein aggregation and specifically suppresses polyQ protein-induced cell death. Using a recombinant and purified polyQ protein (thioredoxin-Huntingtin-Q46), we further demonstrated that AQAMAN interferes with polyQ self-assembly, preventing polyQ aggregation, and dissociates preformed polyQ aggregates in a cell-free system. Remarkably, AQAMAN feeding of Drosophila expressing expanded polyQ disease protein suppresses polyQ-induced neurodegeneration in vivo In addition, using inhibitors and activators of the autophagy pathway, we demonstrated that AQAMAN's cytoprotective effect against polyQ toxicity is autophagy-dependent. In summary, we have identified AQAMAN as a potential therapeutic for combating polyQ protein toxicity in polyQ diseases. Our findings further highlight the importance of the autophagy pathway in clearing harmful polyQ proteins.
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Affiliation(s)
- Huiling Hong
- From the Laboratory of Drosophila Research.,School of Life Sciences, Faculty of Science
| | - Alex Chun Koon
- From the Laboratory of Drosophila Research.,School of Life Sciences, Faculty of Science
| | - Zhefan Stephen Chen
- From the Laboratory of Drosophila Research.,School of Life Sciences, Faculty of Science
| | - Yuming Wei
- From the Laboratory of Drosophila Research.,School of Life Sciences, Faculty of Science
| | - Ying An
- From the Laboratory of Drosophila Research.,School of Life Sciences, Faculty of Science
| | - Wen Li
- School of Life Sciences, Faculty of Science
| | - Matthew Ho Yan Lau
- the Department of Chemistry, University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR, China, and
| | | | | | | | - Ho Yu Au-Yeung
- the Department of Chemistry, University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR, China, and
| | - Steven C Zimmerman
- the Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Ho Yin Edwin Chan
- From the Laboratory of Drosophila Research, .,School of Life Sciences, Faculty of Science.,Gerald Choa Neuroscience Centre, Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
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65
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Xie W, Zhou J. Aberrant regulation of autophagy in mammalian diseases. Biol Lett 2018; 14:rsbl.2017.0540. [PMID: 29321247 DOI: 10.1098/rsbl.2017.0540] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 12/13/2017] [Indexed: 12/11/2022] Open
Abstract
Autophagy is a major cellular metabolic pathway that facilitates degradation of a subset of long-lived proteins and cytoplasmic organelles in eukaryotic cells. This pathway plays a vital role in preserving the cellular homeostasis of the cells themselves, in addition to maintaining the normal physiological state of cell renewal. Many stressors, such as starvation, ischaemia and oxidative stress can induce autophagy. In addition to its physiological roles, autophagy also occurs in a wide variety of pathological processes, including tumour progression, metabolic disorders, and neurodegenerative and lung diseases. In recent years, a growing body of evidence has shown that autophagy also plays a key role in the development of mammalian diseases, a function that has garnered substantial attention and study. An in-depth understanding of the molecular role that autophagy plays in pathological settings is vital for both the diagnosis and treatment of mammalian diseases and will aid in the search for novel targets for therapeutic drug intervention. Here, we provide an integrated review of recent studies implicating autophagy dysfunction in the progression of mammalian disorders and summarize research suggesting that the molecular pathways involved in autophagy could serve as potential therapeutic targets.
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Affiliation(s)
- Wei Xie
- Shandong Provincial Key Laboratory of Animal Resistance Biology, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, P. R. China
| | - Jun Zhou
- Shandong Provincial Key Laboratory of Animal Resistance Biology, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, P. R. China
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66
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Chang CC, Lin TC, Ho HL, Kuo CY, Li HH, Korolenko TA, Chen WJ, Lai TJ, Ho YJ, Lin CL. GLP-1 Analogue Liraglutide Attenuates Mutant Huntingtin-Induced Neurotoxicity by Restoration of Neuronal Insulin Signaling. Int J Mol Sci 2018; 19:ijms19092505. [PMID: 30149534 PMCID: PMC6164932 DOI: 10.3390/ijms19092505] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 08/18/2018] [Accepted: 08/22/2018] [Indexed: 12/27/2022] Open
Abstract
Huntington’s disease (HD) is a progressive and fatal neurodegenerative disease caused by CAG repeat expansion in the coding region of huntingtin (HTT) protein. The accumulation of mutant HTT (mHTT) contributes to neurotoxicity by causing autophagy defects and oxidative stress that ultimately lead to neuronal death. Interestingly, epidemiologic studies have demonstrated that the prevalence of type-2 diabetes, a metabolic disease mainly caused by defective insulin signaling, is higher in patients with HD than in healthy controls. Although the precise mechanisms of mHTT-mediated toxicity remain unclear, the blockade of brain insulin signaling may initiate or exacerbate mHTT-induced neurodegeneration. In this study, we used an in vitro HD model to investigate whether neuronal insulin signaling is involved in mHTT-mediated neurotoxicity. Our results demonstrated that mHTT overexpression significantly impairs insulin signaling and causes apoptosis in neuronal cells. However, treatment with liraglutide, a GLP-1 analogue, markedly restores insulin sensitivity and enhances cell viability. This neuroprotective effect may be attributed to the contribution of the upregulated expression of genes associated with endogenous antioxidant pathways to oxidative stress reduction. In addition, liraglutide stimulates autophagy through AMPK activation, which attenuates the accumulation of HTT aggregates within neuronal cells. Our findings collectively suggest that liraglutide can rescue impaired insulin signaling caused by mHTT and that GLP-1 may potentially reduce mHTT-induced neurotoxicity in the pathogenesis of HD.
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Affiliation(s)
- Ching-Chi Chang
- Institute of Medicine, Chung Shan Medical University, Taichung 40201, Taiwan.
- Department of Psychiatry, Chung Shan Medical University Hospital, Taichung 40201, Taiwan.
| | - Tzu-Chin Lin
- Department of Psychiatry, Chung Shan Medical University Hospital, Taichung 40201, Taiwan.
| | - Hsiao-Li Ho
- Institute of Medicine, Chung Shan Medical University, Taichung 40201, Taiwan.
| | - Chien-Yin Kuo
- Institute of Medicine, Chung Shan Medical University, Taichung 40201, Taiwan.
| | - Hsin-Hua Li
- Institute of Medicine, Chung Shan Medical University, Taichung 40201, Taiwan.
| | - Tatiana A Korolenko
- Federal State Budgetary Scientific Institution, Scientific Research Institute of Physiology and Basic Medicine, Novosibirsk 630117, Russia.
| | - Wei-Jen Chen
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung 40201, Taiwan.
| | - Te-Jen Lai
- Institute of Medicine, Chung Shan Medical University, Taichung 40201, Taiwan.
- Department of Psychiatry, Chung Shan Medical University Hospital, Taichung 40201, Taiwan.
| | - Ying-Jui Ho
- Department of Psychology, Chung Shan Medical University, Taichung 40201, Taiwan.
| | - Chih-Li Lin
- Institute of Medicine, Chung Shan Medical University, Taichung 40201, Taiwan.
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung 40201, Taiwan.
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67
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Croce KR, Yamamoto A. A role for autophagy in Huntington's disease. Neurobiol Dis 2018; 122:16-22. [PMID: 30149183 DOI: 10.1016/j.nbd.2018.08.010] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 08/10/2018] [Accepted: 08/23/2018] [Indexed: 12/19/2022] Open
Abstract
The lysosome-mediated degradation pathway known as macroautophagy is the most versatile means through which cells can eliminate and recycle unwanted materials. Through both selective and non-selective means, macroautophagy can degrade a wide range of cargoes from bulk cytosol to organelles and aggregated proteins. Although studies of disorders such as Parkinson's disease and Amyotrophic Lateral Sclerosis suggest that autophagic and lysosomal dysfunction directly contributes to disease, this had not been the case for the polyglutamine disorder Huntington's disease (HD), for which there was little indication of a disruption in the autophagic-lysosomal system. This supported the possibility of targeting autophagy as a much needed therapeutic approach to combat this disease. Possibly challenging this view, however, are a recent set of studies suggesting that the protein affected in Huntington's disease, huntingtin, might mechanistically contribute to macroautophagy. In this review, we will explore how autophagy might impact or be impacted by HD pathogenesis, and whether a therapeutic approach centering on autophagy may be possible for this yet incurable disease.
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Affiliation(s)
- Katherine R Croce
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, United States
| | - Ai Yamamoto
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, United States; Department of Neurology, Columbia University, New York, NY 10032, United States.
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68
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Al-Ramahi I, Lu B, Di Paola S, Pang K, de Haro M, Peluso I, Gallego-Flores T, Malik NT, Erikson K, Bleiberg BA, Avalos M, Fan G, Rivers LE, Laitman AM, Diaz-García JR, Hild M, Palacino J, Liu Z, Medina DL, Botas J. High-Throughput Functional Analysis Distinguishes Pathogenic, Nonpathogenic, and Compensatory Transcriptional Changes in Neurodegeneration. Cell Syst 2018; 7:28-40.e4. [PMID: 29936182 PMCID: PMC6082401 DOI: 10.1016/j.cels.2018.05.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/14/2018] [Accepted: 05/16/2018] [Indexed: 01/17/2023]
Abstract
Discriminating transcriptional changes that drive disease pathogenesis from nonpathogenic and compensatory responses is a daunting challenge. This is particularly true for neurodegenerative diseases, which affect the expression of thousands of genes in different brain regions at different disease stages. Here we integrate functional testing and network approaches to analyze previously reported transcriptional alterations in the brains of Huntington disease (HD) patients. We selected 312 genes whose expression is dysregulated both in HD patients and in HD mice and then replicated and/or antagonized each alteration in a Drosophila HD model. High-throughput behavioral testing in this model and controls revealed that transcriptional changes in synaptic biology and calcium signaling are compensatory, whereas alterations involving the actin cytoskeleton and inflammation drive disease. Knockdown of disease-driving genes in HD patient-derived cells lowered mutant Huntingtin levels and activated macroautophagy, suggesting a mechanism for mitigating pathogenesis. Our multilayered approach can thus untangle the wealth of information generated by transcriptomics and identify early therapeutic intervention points.
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Affiliation(s)
- Ismael Al-Ramahi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Boxun Lu
- State Key Laboratory of Medical Neurobiology, Collaborative Innovation Center for Brain Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Simone Di Paola
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Kaifang Pang
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Maria de Haro
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Ivana Peluso
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Tatiana Gallego-Flores
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Nazish T Malik
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Kelly Erikson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Benjamin A Bleiberg
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Matthew Avalos
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - George Fan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Laura Elizabeth Rivers
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Andrew M Laitman
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Javier R Diaz-García
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Marc Hild
- Novartis Institutes for Biomedical Research, Cambridge, MA, USA
| | - James Palacino
- Novartis Institutes for Biomedical Research, Cambridge, MA, USA
| | - Zhandong Liu
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Diego L Medina
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Juan Botas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA.
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69
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Tissue-Specific Upregulation of Drosophila Insulin Receptor (InR) Mitigates Poly(Q)-Mediated Neurotoxicity by Restoration of Cellular Transcription Machinery. Mol Neurobiol 2018; 56:1310-1329. [DOI: 10.1007/s12035-018-1160-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 05/29/2018] [Indexed: 12/11/2022]
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70
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Saha S, Panigrahi DP, Patil S, Bhutia SK. Autophagy in health and disease: A comprehensive review. Biomed Pharmacother 2018; 104:485-495. [PMID: 29800913 DOI: 10.1016/j.biopha.2018.05.007] [Citation(s) in RCA: 356] [Impact Index Per Article: 59.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/12/2018] [Accepted: 05/07/2018] [Indexed: 12/13/2022] Open
Abstract
Autophagy, a conserved catabolic process, plays an immensely significant role in a variety of diseases. However, whether it imparts a protective function in diseases remains debatable. During aging, autophagy gradually subsides, manifested by the reduced formation of autophagic vacuoles and improper fusion of these vacuoles with the lysosomes. Similarly, in neurodegenerative disorders, accumulation of tau and synuclein proteins has been attributed to the decline in the autophagic removal of proteins. Equivalently, lysosomal disorders show an impairment of the autophagic process leading to the accumulation of lipid molecules within lysosomes. On the other hand, activation of the autophagic pathway has also proved beneficial in evading various foreign pathogens, thereby contributing to the innate immunity. In the context of cancer, autophagy has shown to play a puzzling role where it serves as a tumor suppressor during initial stages but later protects the tumor cells from the immune system defense mechanisms. Similarly, muscular and heart disorders have been shown to be positively and negatively regulated by autophagy, respectively. In the present review, we, therefore, present a comprehensive review on the role of autophagy in various diseases and their corresponding outcomes.
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Affiliation(s)
- Sarbari Saha
- Department of Life Science, National Institute of Technology Rourkela, Rourkela 769008, Odisha, India
| | - Debasna P Panigrahi
- Department of Life Science, National Institute of Technology Rourkela, Rourkela 769008, Odisha, India
| | - Shankargouda Patil
- Department of Maxillofacial Surgery and Diagnostic Sciences, Division of Oral Pathology, College of Dentistry, Jazan University, Saudi Arabia
| | - Sujit K Bhutia
- Department of Life Science, National Institute of Technology Rourkela, Rourkela 769008, Odisha, India.
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71
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Abstract
Amyloid fibrils are protein homopolymers that adopt diverse cross-β conformations. Some amyloid fibrils are associated with the pathogenesis of devastating neurodegenerative disorders, including Alzheimer's disease and Parkinson's disease. Conversely, functional amyloids play beneficial roles in melanosome biogenesis, long-term memory formation and release of peptide hormones. Here, we showcase advances in our understanding of amyloid assembly and structure, and how distinct amyloid strains formed by the same protein can cause distinct neurodegenerative diseases. We discuss how mutant steric zippers promote deleterious amyloidogenesis and aberrant liquid-to-gel phase transitions. We also highlight effective strategies to combat amyloidogenesis and related toxicity, including: (1) small-molecule drugs (e.g. tafamidis) to inhibit amyloid formation or (2) stimulate amyloid degradation by the proteasome and autophagy, and (3) protein disaggregases that disassemble toxic amyloid and soluble oligomers. We anticipate that these advances will inspire therapeutics for several fatal neurodegenerative diseases. Summary: This Review showcases important advances in our understanding of amyloid structure, assembly and disassembly, which are inspiring novel therapeutic strategies for amyloid disorders.
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Affiliation(s)
- Edward Chuang
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.,Pharmacology Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Acacia M Hori
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christina D Hesketh
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA .,Pharmacology Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
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72
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Thomas EA, D'Mello SR. Complex neuroprotective and neurotoxic effects of histone deacetylases. J Neurochem 2018; 145:96-110. [PMID: 29355955 DOI: 10.1111/jnc.14309] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 12/05/2017] [Accepted: 12/27/2017] [Indexed: 12/14/2022]
Abstract
By their ability to shatter quality of life for both patients and caregivers, neurodegenerative diseases are the most devastating of human disorders. Unfortunately, there are no effective or long-terms treatments capable of slowing down the relentless loss of neurons in any of these diseases. One impediment is the lack of detailed knowledge of the molecular mechanisms underlying the processes of neurodegeneration. While some neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, are mostly sporadic in nature, driven by both environment and genetic susceptibility, many others, including Huntington's disease, spinocerebellar ataxias, and spinal-bulbar muscular atrophy, are genetically inherited disorders. Surprisingly, given their different roots and etiologies, both sporadic and genetic neurodegenerative disorders have been linked to disease mechanisms involving histone deacetylase (HDAC) proteins, which consists of 18 family members with diverse functions. While most studies have implicated certain HDAC subtypes in promoting neurodegeneration, a substantial body of literature suggests that other HDAC proteins can preserve neuronal viability. Of particular interest, however, is the recent realization that a single HDAC subtype can have both neuroprotective and neurotoxic effects. Diverse mechanisms, beyond transcriptional regulation have been linked to these effects, including deacetylation of non-histone proteins, protein-protein interactions, post-translational modifications of the HDAC proteins themselves and direct interactions with disease proteins. The roles of these HDACs in both sporadic and genetic neurodegenerative diseases will be discussed in the current review.
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Affiliation(s)
- Elizabeth A Thomas
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California, USA
| | - Santosh R D'Mello
- Department of Biological Sciences, Southern Methodist University, Dallas, Texas, USA
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73
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Abstract
Autophagy is an evolutionarily conserved degradation pathway for cells to maintain homeostasis, produce energy, degrade misfolded proteins and damaged organelles, and fight against intracellular pathogens. The process of autophagy entails the isolation of cytoplasmic cargo into double membrane bound autophagosomes that undergo maturation by fusion with endosomes and lysosomes to obtain degradation capacity. RAB proteins regulate intracellular vesicle trafficking events including autophagy. RAB24 is an atypical RAB protein that is required for the clearance of late autophagic vacuoles under basal conditions. RAB24 has also been connected to several diseases including ataxia, cancer and tuberculosis. This review gives a short summary on autophagy and RAB proteins, and an overview on the current knowledge on the roles of RAB24 in autophagy and disease.
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Affiliation(s)
- Päivi Ylä-Anttila
- a Department of Biosciences , University of Helsinki , Helsinki , Finland
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74
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Xia F, Deng C, Jiang Y, Qu Y, Deng J, Cai Z, Ding Y, Guo Z, Wang J. IL4 (interleukin 4) induces autophagy in B cells leading to exacerbated asthma. Autophagy 2018; 14:450-464. [PMID: 29297752 DOI: 10.1080/15548627.2017.1421884] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Allergic asthma is a common airway inflammatory disease in which B cells play important roles through IgE production and antigen presentation. SNP (single nucleotide polymorphism) analysis showed that Atg (autophagy-related) allele mutations are involved in asthma. It has been demonstrated that macroautophagy/autophagy is essential for B cell survival, plasma cell differentiation and immunological memory maintenance. However, whether B cell autophagy participates in asthma pathogenesis remains to be investigated. In this report, we found that autophagy was enhanced in pulmonary B cells from asthma-prone mice. Autophagy deficiency in B cells led to attenuated immunopathological symptoms in asthma-prone mice. Further investigation showed that IL4 (interleukin 4), a key effector Th2 cytokine in allergic asthma, was critical for autophagy induction in B cells both in vivo and in vitro, which further sustained B cell survival and enhanced antigen presentation by B cells. Moreover, IL4-induced autophagy depended on JAK signaling via an MTOR-independent, PtdIns3K-dependent pathway. Together, our data indicate that B cell autophagy aggravates experimental asthma through multiple mechanisms.
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Affiliation(s)
- Fucan Xia
- a Institute of Immunology , Zhejiang University School of Medicine , Hangzhou , China
| | - Changwen Deng
- b Department of Respiratory Medicine , Changhai Hospital , Second Military Medical University , Shanghai , China
| | - Yanyan Jiang
- c National Key Laboratory of Medical Immunology & Institute of Immunology , Second Military Medical University , Shanghai , China
| | - Yulan Qu
- b Department of Respiratory Medicine , Changhai Hospital , Second Military Medical University , Shanghai , China
| | - Jiewen Deng
- c National Key Laboratory of Medical Immunology & Institute of Immunology , Second Military Medical University , Shanghai , China
| | - Zhijian Cai
- a Institute of Immunology , Zhejiang University School of Medicine , Hangzhou , China
| | - Yuanyuan Ding
- d National Key Laboratory of Medical Molecular Biology & Department of Immunology , Institute of Basic Medical Sciences , Peking Union Medical College , Chinese Academy of Medical Sciences , Beijing , China
| | - Zhenhong Guo
- c National Key Laboratory of Medical Immunology & Institute of Immunology , Second Military Medical University , Shanghai , China
| | - Jianli Wang
- a Institute of Immunology , Zhejiang University School of Medicine , Hangzhou , China
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75
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Sun P, Zhang S, Qin X, Chang X, Cui X, Li H, Zhang S, Gao H, Wang P, Zhang Z, Luo J, Li Z. Foot-and-mouth disease virus capsid protein VP2 activates the cellular EIF2S1-ATF4 pathway and induces autophagy via HSPB1. Autophagy 2018; 14:336-346. [PMID: 29166823 PMCID: PMC5902195 DOI: 10.1080/15548627.2017.1405187] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Foot-and-mouth disease virus (FMDV) can result in economical destruction of cloven-hoofed animals. FMDV infection has been reported to induce macroautophagy/autophagy; however, the precise molecular mechanisms of autophagy induction and effect of FMDV capsid protein on autophagy remain unknown. In the present study, we report that FMDV infection induced a complete autophagy process in the natural host cells of FMDV, and inhibition of autophagy significantly decreased FMDV production, suggesting that FMDV-induced autophagy facilitates viral replication. We found that the EIF2S1-ATF4 pathway was activated and the AKT-MTOR signaling pathway was inhibited by FMDV infection. We also observed that ultraviolet (UV)-inactivated FMDV can induce autophagy. Importantly, our work provides the first piece of evidence that expression of FMDV capsid protein VP2 can induce autophagy through the EIF2S1-ATF4-AKT-MTOR cascade, and we found that VP2 interacted with HSPB1 (heat shock protein family B [small] member 1) and activated the EIF2S1-ATF4 pathway, resulting in autophagy and enhanced FMDV replication. In addition, we show that VP2 induced autophagy in a variety of mammalian cell lines and decreased aggregates of a model mutant HTT (huntingtin) polyglutamine expansion protein (HTT103Q). Overall, our results demonstrate that FMDV capsid protein VP2 induces autophagy through interaction with HSPB1 and activation of the EIF2S1-ATF4 pathway.
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Affiliation(s)
- Peng Sun
- a State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture , Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Lanzhou , Gansu , China.,b Department of Cell Biology, School of Life Sciences , Lanzhou University , Lanzhou , Gansu , China
| | - Shumin Zhang
- a State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture , Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Lanzhou , Gansu , China
| | - Xiaodong Qin
- a State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture , Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Lanzhou , Gansu , China
| | - Xingni Chang
- a State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture , Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Lanzhou , Gansu , China
| | - Xiaorui Cui
- a State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture , Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Lanzhou , Gansu , China
| | - Haitao Li
- a State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture , Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Lanzhou , Gansu , China
| | - Shuaijun Zhang
- a State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture , Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Lanzhou , Gansu , China
| | - Huanhuan Gao
- b Department of Cell Biology, School of Life Sciences , Lanzhou University , Lanzhou , Gansu , China
| | - Penghua Wang
- c Department of Microbiology and Immunology , New York Medical College, Valhalla , New York , USA
| | - Zhidong Zhang
- a State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture , Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Lanzhou , Gansu , China
| | - Jianxun Luo
- a State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture , Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Lanzhou , Gansu , China
| | - Zhiyong Li
- a State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture , Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Lanzhou , Gansu , China
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Kyani A, Tamura S, Yang S, Shergalis A, Samanta S, Kuang Y, Ljungman M, Neamati N. Discovery and Mechanistic Elucidation of a Class of Protein Disulfide Isomerase Inhibitors for the Treatment of Glioblastoma. ChemMedChem 2018; 13:164-177. [PMID: 29235250 DOI: 10.1002/cmdc.201700629] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/10/2017] [Indexed: 12/14/2022]
Abstract
Protein disulfide isomerase (PDI) is overexpressed in glioblastoma, the most aggressive form of brain cancer, and folds nascent proteins responsible for the progression and spread of the disease. Herein we describe a novel nanomolar PDI inhibitor, pyrimidotriazinedione 35G8, that is toxic in a panel of human glioblastoma cell lines. We performed a medium-throughput 20 000-compound screen of a diverse subset of 1 000 000 compounds to identify cytotoxic small molecules. Cytotoxic compounds were screened for PDI inhibition, and, from the screen, 35G8 emerged as the most cytotoxic inhibitor of PDI. Bromouridine labeling and sequencing (Bru-seq) of nascent RNA revealed that 35G8 induces nuclear factor-like 2 (Nrf2) antioxidant response, endoplasmic reticulum (ER) stress response, and autophagy. Specifically, 35G8 upregulated heme oxygenase 1 and solute carrier family 7 member 11 (SLC7A11) transcription and protein expression and repressed PDI target genes such as thioredoxin-interacting protein 1 (TXNIP) and early growth response 1 (EGR1). Interestingly, 35G8-induced cell death did not proceed via apoptosis or necrosis, but by a mixture of autophagy and ferroptosis. Cumulatively, our data demonstrate a mechanism for a novel PDI inhibitor as a chemical probe to validate PDI as a target for brain cancer.
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Affiliation(s)
- Anahita Kyani
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, MI, 48109, USA
| | - Shuzo Tamura
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, MI, 48109, USA
| | - Suhui Yang
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, MI, 48109, USA
| | - Andrea Shergalis
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, MI, 48109, USA
| | - Soma Samanta
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, MI, 48109, USA
| | - Yuting Kuang
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, MI, 48109, USA
| | - Mats Ljungman
- Departments of Radiation Oncology and Environmental Health Sciences, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, MI, 48109, USA
| | - Nouri Neamati
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, MI, 48109, USA
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Abstract
Parkinson's disease is a progressive neurodegenerative disease characterized by Lewy body pathology of which the primary constituent is aggregated misfolded alpha-synuclein protein. Currently, there are no clinical therapies for treatment of the underlying alpha-synuclein dysfunction and accumulation, and the standard of care for patients with Parkinson's disease focuses only on symptom management, creating an immense therapeutic gap that needs to be filled. Defects in autophagy have been strongly implicated in Parkinson's disease. Here, we review evidence from human, mouse, and cell culture studies to briefly explain these defects in autophagy in Parkinson's disease and the necessity for autophagy to be carefully and precisely tuned to maintain neuron survival. We summarize recent experimental agents for treating alpha-synuclein accumulation in α-synuclein Parkinson's disease and related synucleinopathies. Most of the efforts for developing experimental agents have focused on immunotherapeutic strategies, but we discuss why those efforts are misplaced. Finally, we emphasize why increasing autophagy flux for alpha-synuclein clearance is the most promising therapeutic strategy. Activating autophagy has been successful in preclinical models of Parkinson's disease and yields promising results in clinical trials.
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Affiliation(s)
- Alan J Fowler
- Department of Neurology, Laboratory for Dementia and Parkinsonism, Translational Neurotherapeutics Program, Room 203-C, Building D, 4000 Reservoir Rd. NW, Washington, DC, USA
| | - Charbel E-H Moussa
- Department of Neurology, Laboratory for Dementia and Parkinsonism, Translational Neurotherapeutics Program, Room 203-C, Building D, 4000 Reservoir Rd. NW, Washington, DC, USA.
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Abstract
Macroautophagy is an intracellular pathway used for targeting of cellular components to the lysosome for their degradation and involves sequestration of cytoplasmic material into autophagosomes formed from a double membrane structure called the phagophore. The nucleation and elongation of the phagophore is tightly regulated by several autophagy-related (ATG) proteins, but also involves vesicular trafficking from different subcellular compartments to the forming autophagosome. Such trafficking must be tightly regulated by various intra- and extracellular signals to respond to different cellular stressors and metabolic states, as well as the nature of the cargo to become degraded. We are only starting to understand the interconnections between different membrane trafficking pathways and macroautophagy. This review will focus on the membrane trafficking machinery found to be involved in delivery of membrane, lipids, and proteins to the forming autophagosome and in the subsequent autophagosome fusion with endolysosomal membranes. The role of RAB proteins and their regulators, as well as coat proteins, vesicle tethers, and SNARE proteins in autophagosome biogenesis and maturation will be discussed.
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79
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Su H, Yang F, Wang Q, Shen Q, Huang J, Peng C, Zhang Y, Wan W, Wong CCL, Sun Q, Wang F, Zhou T, Liu W. VPS34 Acetylation Controls Its Lipid Kinase Activity and the Initiation of Canonical and Non-canonical Autophagy. Mol Cell 2017; 67:907-921.e7. [PMID: 28844862 DOI: 10.1016/j.molcel.2017.07.024] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 06/13/2017] [Accepted: 07/26/2017] [Indexed: 12/13/2022]
Abstract
The class III phosphoinositide 3-kinase VPS34 plays a key role in the regulation of vesicular trafficking and macroautophagy. So far, we know little about the molecular mechanism of VPS34 activation besides its interaction with regulatory proteins to form complexes. Here, we report that VPS34 is specifically acetylated by the acetyltransferase p300, and p300-mediated acetylation represses VPS34 activity. Acetylation at K771 directly diminishes the affinity of VPS34 for its substrate PI, while acetylation at K29 hinders the VPS34-Beclin 1 core complex formation. Inactivation of p300 induces VPS34 deacetylation, PI3P production, and autophagy, even in AMPK-/-, TSC2-/-, or ULK1-/- cells. In fasting mice, liver autophagy correlates well with p300 inactivation/VPS34 deacetylation, which facilitates the clearance of lipid droplets in hepatocytes. Thus, p300-dependent VPS34 acetylation/deacetylation is the physiological key to VPS34 activation, which controls the initiation of canonical autophagy and of non-canonical autophagy in which the upstream kinases of VPS34 can be bypassed.
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Affiliation(s)
- Hua Su
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Fei Yang
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Qiuting Wang
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Qiuhong Shen
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Jingtao Huang
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Chao Peng
- National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yi Zhang
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Wei Wan
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Catherine C L Wong
- National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Qiming Sun
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Fudi Wang
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Tianhua Zhou
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Wei Liu
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China.
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80
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Phosphatidylinositol 3 kinase (PI3K) modulates manganese homeostasis and manganese-induced cell signaling in a murine striatal cell line. Neurotoxicology 2017; 64:185-194. [PMID: 28780388 DOI: 10.1016/j.neuro.2017.07.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 07/14/2017] [Accepted: 07/14/2017] [Indexed: 12/22/2022]
Abstract
In a recent study, we found that blocking the protein kinase ataxia telangiectasia mutated (ATM) with the small molecule inhibitor (SMI) KU-55933 can completely abrogate Mn-induced phosphorylation of p53 at serine 15 (p-p53) in human induced pluripotent stem cell (hiPSC)-differentiated striatal neuroprogenitors. However, in the immortalized mouse striatal progenitor cell line STHdhQ7/Q7, a concentration of KU55933 far exceeding its IC50 for ATM was required to inhibit Mn-induced p-p53. This suggested an alternative signaling system redundant with ATM kinase for activating p53 in this cell line- one that was altered by KU55933 at these higher concentrations (i.e. mTORC1, DNApk, PI3K). To test the hypothesis that one or more of these signaling pathways contributed to Mn-induced p-p53, we utilized a set of SMIs (e.g. NU7441 and LY294002) known to block DNApk, PI3K, and mTORC1 at distinct concentrations. We found that the SMIs inhibit Mn-induced p-p53 expression near the expected IC50s for PI3K, versus other known targets. We hypothesized that inhibiting PI3K reduces intracellular Mn and thereby decreases activation of p53 by Mn. Using the cellular fura-2 manganese extraction assay (CFMEA), we determined that KU55933/60019, NU7441, and LY294002 (at concentrations near their IC50s for PI3K) all decrease intracellular Mn (∼50%) after a dual, 24-h Mn and SMI exposure. Many pathways are activated by Mn aside from p-p53, including AKT and mTOR pathways. Thus, we explored the activation of these pathways by Mn in STHdh cells as well as the effects of other pathway inhibitors. p-AKT and p-S6 activation by Mn is almost completely blocked upon addition of NU7441(5μM) or LY294002(7μM), supporting PI3K's upstream role in the AKT/mTOR pathway. We also investigated whether PI3K inhibition blocks Mn uptake in other cell lines. LY294002 exposure did not reduce Mn uptake in ST14A, Neuro2A, HEK293, MEF, or hiPSC-derived neuroprogenitors. Next, we sought to determine whether inhibition of PI3K blocked p53 phosphorylation by directly blocking an unknown PI3K/p53 interaction or indirectly reducing intracellular Mn, decreasing p-p53 expression. In-Cell Western and CFMEA experiments using multiple concentrations of Mn exposures demonstrated that intracellular Mn levels directly correlated with p-p53 expression with or without addition of LY294002. Finally, we examined whether PI3K inhibition was able to block Mn-induced p-p53 activity in hiPSC-derived striatal neuroprogenitors. As expected, LY294002 does not block Mn-induced p-p53 as PI3K inhibition is unable to reduce Mn net uptake in this cell line, suggesting the effect of LY294002 on Mn uptake is relatively specific to the STHdh mouse striatal cell line.
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81
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Rocchi A, Yamamoto S, Ting T, Fan Y, Sadleir K, Wang Y, Zhang W, Huang S, Levine B, Vassar R, He C. A Becn1 mutation mediates hyperactive autophagic sequestration of amyloid oligomers and improved cognition in Alzheimer's disease. PLoS Genet 2017; 13:e1006962. [PMID: 28806762 PMCID: PMC5570506 DOI: 10.1371/journal.pgen.1006962] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 08/24/2017] [Accepted: 08/07/2017] [Indexed: 12/31/2022] Open
Abstract
Impairment of the autophagy pathway has been observed during the pathogenesis of Alzheimer's disease (AD), a neurodegenerative disorder characterized by abnormal deposition of extracellular and intracellular amyloid β (Aβ) peptides. Yet the role of autophagy in Aβ production and AD progression is complex. To study whether increased basal autophagy plays a beneficial role in Aβ clearance and cognitive improvement, we developed a novel genetic model to hyperactivate autophagy in vivo. We found that knock-in of a point mutation F121A in the essential autophagy gene Beclin 1/Becn1 in mice significantly reduces the interaction of BECN1 with its inhibitor BCL2, and thus leads to constitutively active autophagy even under non-autophagy-inducing conditions in multiple tissues, including brain. Becn1F121A-mediated autophagy hyperactivation significantly decreases amyloid accumulation, prevents cognitive decline, and restores survival in AD mouse models. Using an immunoisolation method, we found biochemically that Aβ oligomers are autophagic substrates and sequestered inside autophagosomes in the brain of autophagy-hyperactive AD mice. In addition to genetic activation of autophagy by Becn1 gain-of-function, we also found that ML246, a small-molecule autophagy inducer, as well as voluntary exercise, a physiological autophagy inducer, exert similar Becn1-dependent protective effects on Aβ removal and memory in AD mice. Taken together, these results demonstrate that genetically disrupting BECN1-BCL2 binding hyperactivates autophagy in vivo, which sequestrates amyloid oligomers and prevents AD progression. The study establishes new approaches to activate autophagy in the brain, and reveals the important function of Becn1-mediated autophagy hyperactivation in the prevention of AD.
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Affiliation(s)
- Altea Rocchi
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Soh Yamamoto
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Department of Microbiology, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Tabitha Ting
- Center for Autophagy Research, Department of Internal Medicine, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Yuying Fan
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Key Laboratory on Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, Changchun, Jilin, China
| | - Katherine Sadleir
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Yigang Wang
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- School of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, Zhejiang, China
| | - Weiran Zhang
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Sui Huang
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Beth Levine
- Center for Autophagy Research, Department of Internal Medicine, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Robert Vassar
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Congcong He
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
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Abstract
Autophagy is an evolutionarily conserved degradation pathway for cells to maintain homeostasis, produce energy, degrade misfolded proteins and damaged organelles, and fight against intracellular pathogens. The process of autophagy entails the isolation of cytoplasmic cargo into double membrane bound autophagosomes that undergo maturation by fusion with endosomes and lysosomes to obtain degradation capacity. RAB proteins regulate intracellular vesicle trafficking events including autophagy. RAB24 is an atypical RAB protein that is required for the clearance of late autophagic vacuoles under basal conditions. RAB24 has also been connected to several diseases including ataxia, cancer and tuberculosis. This review gives a short summary on autophagy and RAB proteins, and an overview on the current knowledge on the roles of RAB24 in autophagy and disease.
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Affiliation(s)
- Päivi Ylä-Anttila
- a Department of Biosciences , University of Helsinki , Helsinki , Finland
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83
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Peraro L, Zou Z, Makwana KM, Cummings AE, Ball HL, Yu H, Lin YS, Levine B, Kritzer JA. Diversity-Oriented Stapling Yields Intrinsically Cell-Penetrant Inducers of Autophagy. J Am Chem Soc 2017; 139:7792-7802. [PMID: 28414223 PMCID: PMC5473019 DOI: 10.1021/jacs.7b01698] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
![]()
Autophagy
is an essential pathway by which cellular and foreign
material are degraded and recycled in eukaryotic cells. Induction
of autophagy is a promising approach for treating diverse human diseases,
including neurodegenerative disorders and infectious diseases. Here,
we report the use of a diversity-oriented stapling approach to produce
autophagy-inducing peptides that are intrinsically cell-penetrant.
These peptides induce autophagy at micromolar concentrations in vitro,
have aggregate-clearing activity in a cellular model of Huntington’s
disease, and induce autophagy in vivo. Unexpectedly, the solution
structure of the most potent stapled peptide, DD5-o, revealed an α-helical
conformation in methanol, stabilized by an unusual (i,i+3) staple which cross-links two d-amino
acids. We also developed a novel assay for cell penetration that reports
exclusively on cytosolic access and used it to quantitatively compare
the cell penetration of DD5-o and other autophagy-inducing peptides.
These new, cell-penetrant autophagy inducers and their molecular details
are critical advances in the effort to understand and control autophagy.
More broadly, diversity-oriented stapling may provide a promising
alternative to polycationic sequences as a means for rendering peptides
more cell-penetrant.
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Affiliation(s)
- Leila Peraro
- Department of Chemistry, Tufts University , Medford, Massachusetts 02155, United States
| | | | - Kamlesh M Makwana
- Department of Chemistry, Tufts University , Medford, Massachusetts 02155, United States
| | - Ashleigh E Cummings
- Department of Chemistry, Tufts University , Medford, Massachusetts 02155, United States
| | | | - Hongtao Yu
- Department of Chemistry, Tufts University , Medford, Massachusetts 02155, United States
| | - Yu-Shan Lin
- Department of Chemistry, Tufts University , Medford, Massachusetts 02155, United States
| | | | - Joshua A Kritzer
- Department of Chemistry, Tufts University , Medford, Massachusetts 02155, United States
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ErbB2 regulates autophagic flux to modulate the proteostasis of APP-CTFs in Alzheimer's disease. Proc Natl Acad Sci U S A 2017; 114:E3129-E3138. [PMID: 28351972 DOI: 10.1073/pnas.1618804114] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Proteolytic processing of amyloid precursor protein (APP) C-terminal fragments (CTFs) by γ-secretase underlies the pathogenesis of Alzheimer's disease (AD). An RNA interference screen using APP-CTF [99-residue CTF (C99)]- and Notch-specific γ-secretase interaction assays identified a unique ErbB2-centered signaling network that was predicted to preferentially govern the proteostasis of APP-C99. Consistently, significantly elevated levels of ErbB2 were confirmed in the hippocampus of human AD brains. We then found that ErbB2 effectively suppressed autophagic flux by physically dissociating Beclin-1 from the Vps34-Vps15 complex independent of its kinase activity. Down-regulation of ErbB2 by CL-387,785 decreased the levels of C99 and secreted amyloid-β in cellular, zebrafish, and mouse models of AD, through the activation of autophagy. Oral administration of an ErbB2-targeted CL-387,785 for 3 wk significantly improves the cognitive functions of APP/presenilin-1 (PS1) transgenic mice. This work unveils a noncanonical function of ErbB2 in modulating autophagy and establishes ErbB2 as a therapeutic target for AD.
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85
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Bryan MR, Bowman AB. Manganese and the Insulin-IGF Signaling Network in Huntington's Disease and Other Neurodegenerative Disorders. ADVANCES IN NEUROBIOLOGY 2017; 18:113-142. [PMID: 28889265 PMCID: PMC6559248 DOI: 10.1007/978-3-319-60189-2_6] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease resulting in motor impairment and death in patients. Recently, several studies have demonstrated insulin or insulin-like growth factor (IGF) treatment in models of HD, resulting in potent amelioration of HD phenotypes via modulation of the PI3K/AKT/mTOR pathways. Administration of IGF and insulin can rescue microtubule transport, metabolic function, and autophagy defects, resulting in clearance of Huntingtin (HTT) aggregates, restoration of mitochondrial function, amelioration of motor abnormalities, and enhanced survival. Manganese (Mn) is an essential metal to all biological systems but, in excess, can be toxic. Interestingly, several studies have revealed the insulin-mimetic effects of Mn-demonstrating Mn can activate several of the same metabolic kinases and increase peripheral and neuronal insulin and IGF-1 levels in rodent models. Separate studies have shown mouse and human striatal neuroprogenitor cell (NPC) models exhibit a deficit in cellular Mn uptake, indicative of a Mn deficiency. Furthermore, evidence from the literature reveals a striking overlap between cellular consequences of Mn deficiency (i.e., impaired function of Mn-dependent enzymes) and known HD endophenotypes including excitotoxicity, increased reactive oxygen species (ROS) accumulation, and decreased mitochondrial function. Here we review published evidence supporting a hypothesis that (1) the potent effect of IGF or insulin treatment on HD models, (2) the insulin-mimetic effects of Mn, and (3) the newly discovered Mn-dependent perturbations in HD may all be functionally related. Together, this review will present the intriguing possibility that intricate regulatory cross-talk exists between Mn biology and/or toxicology and the insulin/IGF signaling pathways which may be deeply connected to HD pathology and, perhaps, other neurodegenerative diseases (NDDs) and other neuropathological conditions.
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Affiliation(s)
- Miles R Bryan
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
| | - Aaron B Bowman
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Vanderbilt Center in Molecular Toxicology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
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87
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Wold MS, Lim J, Lachance V, Deng Z, Yue Z. ULK1-mediated phosphorylation of ATG14 promotes autophagy and is impaired in Huntington's disease models. Mol Neurodegener 2016; 11:76. [PMID: 27938392 PMCID: PMC5148922 DOI: 10.1186/s13024-016-0141-0] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 12/03/2016] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Autophagy is a bulk degradation pathway for long-lived proteins, protein aggregates, and damaged organelles. ULK1 protein kinase and Vps34 lipid kinase are two key autophagy regulators that are critical for autophagosome biogenesis. However, it isn't fully understood how ULK1 regulates Vps34, especially in the context of disease. Polyglutamine expansion in huntingtin (Htt) causes aberrant accumulation of the aggregated protein and disrupts various cellular pathways including autophagy, a lysosomal degradation pathway, underlying the pathogenesis of Huntington's disease (HD). Although autophagic clearance of Htt aggregates is under investigation as therapeutic strategy for HD, the precise mechanism of autophagy impairment remains poorly understood. Moreover, in-vivo assays of autophagy have been particularly challenging due to lack of reliable and robust molecular biomarkers. METHOD We generated anti-phosphorylated ATG14 antibody to determine ATG14-mediated autophagy regulation; we employed Huntington's disease (HD) genetic cell models and animal models as well as autophagy reporter animal model to understand autophagy signaling and regulation in vivo. We applied biochemical analysis and molecular biology approaches to dissect the alteration of autophagy kinase activity and regulation. RESULTS Here, we demonstrate that ULK1 phosphorylates ATG14 at serine 29 in an mTOR-dependent manner. This phosphorylation critically regulates ATG14-Vps34 lipid kinase activity to control autophagy level. We also show that ATG14-associated Vps34 activity and ULK1-mediated phosphorylation of ATG14 and Beclin 1 are compromised in the Q175 mouse model of Huntington's disease. Finally, we show that ATG14 phosphorylation is decreased during general proteotoxic stress caused by proteasomal inhibition. This reduction of the specific phosphorylation of ATG14 and Beclin 1 is mediated, in part, by p62-induced sequestration of ULK1 to an insoluble cellular fraction. We show that increased ULK1 levels and phosphor-mimetic mutant ATG14 facilitate the clearance of polyQ mutant in cells. CONCLUSION Our study identifies a new regulatory mechanism for ATG14-Vps34 kinase activity by ULK1, which can be used as valuable molecular markers for in-vivo autophagic activity as well as potential therapeutic target for the clearance of polyglutamine disease protein.
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Affiliation(s)
- Mitchell S Wold
- Department of Neurology, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Junghyun Lim
- Department of Neurology, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.,Present Address: Genentech, Inc, 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Véronik Lachance
- Department of Neurology, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Zhiqiang Deng
- Department of Neurology, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.,Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, School of Pharmaceutical Sciences, and Medical Research Institute, Wuhan University, Wuhan, 430071, China
| | - Zhenyu Yue
- Department of Neurology, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA. .,Leon and Norma Hess Center for Science and Medicine, 9-106, 1470 Madison Ave, New York, NY, 10029, USA.
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88
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Cavadas C, Aveleira CA, Souza GFP, Velloso LA. The pathophysiology of defective proteostasis in the hypothalamus - from obesity to ageing. Nat Rev Endocrinol 2016; 12:723-733. [PMID: 27388987 DOI: 10.1038/nrendo.2016.107] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Hypothalamic dysfunction has emerged as an important mechanism involved in the development of obesity and its comorbidities, as well as in the process of ageing and age-related diseases, such as type 2 diabetes mellitus, hypertension and Alzheimer disease. In both obesity and ageing, inflammatory signalling is thought to coordinate many of the cellular events that lead to hypothalamic neuronal dysfunction. This process is triggered by the activation of signalling via the toll-like receptor 4 pathway and endoplasmic reticulum stress, which in turn results in intracellular inflammatory signalling. However, the process that connects inflammation with neuronal dysfunction is complex and includes several regulatory mechanisms that ultimately control the homeostasis of intracellular proteins and organelles (also known as 'proteostasis'). This Review discusses the evidence for the key role of proteostasis in the control of hypothalamic neurons and the involvement of this process in regulating whole-body energy homeostasis and lifespan.
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Affiliation(s)
- Cláudia Cavadas
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, 3004-504, Portugal
- Faculty of Pharmacy, University of Coimbra, Coimbra, 3004-504, Portugal
| | - Célia A Aveleira
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, 3004-504, Portugal
| | - Gabriela F P Souza
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, University of Campinas, Campinas, 1308-970, Brazil
| | - Lício A Velloso
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, University of Campinas, Campinas, 1308-970, Brazil
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89
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Vicente Miranda H, Gomes MA, Branco-Santos J, Breda C, Lázaro DF, Lopes LV, Herrera F, Giorgini F, Outeiro TF. Glycation potentiates neurodegeneration in models of Huntington's disease. Sci Rep 2016; 6:36798. [PMID: 27857176 PMCID: PMC5114697 DOI: 10.1038/srep36798] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 10/21/2016] [Indexed: 11/19/2022] Open
Abstract
Protein glycation is an age-dependent posttranslational modification associated with several neurodegenerative disorders, including Alzheimer’s and Parkinson’s diseases. By modifying amino-groups, glycation interferes with folding of proteins, increasing their aggregation potential. Here, we studied the effect of pharmacological and genetic manipulation of glycation on huntingtin (HTT), the causative protein in Huntington’s disease (HD). We observed that glycation increased the aggregation of mutant HTT exon 1 fragments associated with HD (HTT72Q and HTT103Q) in yeast and mammalian cell models. We found that glycation impairs HTT clearance thereby promoting its intracellular accumulation and aggregation. Interestingly, under these conditions autophagy increased and the levels of mutant HTT released to the culture medium decreased. Furthermore, increased glycation enhanced HTT toxicity in human cells and neurodegeneration in fruit flies, impairing eclosion and decreasing life span. Overall, our study provides evidence that glycation modulates HTT exon-1 aggregation and toxicity, and suggests it may constitute a novel target for therapeutic intervention in HD.
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Affiliation(s)
- Hugo Vicente Miranda
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School
- Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal.,Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Marcos António Gomes
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Joana Branco-Santos
- Department of Genetics, University of Leicester, Leicester LE1 7RH, United Kingdom.,Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Estação Agronomica Nacional, Av. da República, Oeiras 2780-157, Portugal
| | - Carlo Breda
- Department of Genetics, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Diana F Lázaro
- Department of Neurodegeneration and Restorative Research, Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), University Medical Center Göttingen, Waldweg 33, 37073 Göttingen, Germany
| | - Luísa Vaqueiro Lopes
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Federico Herrera
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Estação Agronomica Nacional, Av. da República, Oeiras 2780-157, Portugal
| | - Flaviano Giorgini
- Department of Genetics, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Tiago Fleming Outeiro
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School
- Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal.,Department of Neurodegeneration and Restorative Research, Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), University Medical Center Göttingen, Waldweg 33, 37073 Göttingen, Germany.,Max Planck Institute for Experimental Medicine, Göttingen, Germany
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90
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Banerjee M, Datta M, Bhattacharyya NP. Modulation of mutant Huntingtin aggregates and toxicity by human myeloid leukemia factors. Int J Biochem Cell Biol 2016; 82:1-9. [PMID: 27840155 DOI: 10.1016/j.biocel.2016.11.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 10/26/2016] [Accepted: 11/09/2016] [Indexed: 12/28/2022]
Abstract
Increased poly glutamine (polyQ) stretch at N-terminal of Huntingtin (HTT) causes Huntington's disease. HTT interacts with large number of proteins, although the preference for such interactions with wild type or mutated HTT protein remains largely unknown. HYPK, an intrinsically unstructured protein chaperone and interactor of mutant HTT was found to interact with myeloid leukemia factor 1 (MLF1) and 2 (MLF2). To identify the role of these two proteins in mutant HTT mediated aggregate formation and toxicity in a cell model, both the proteins were found to preferentially interact with the mutated N-terminal HTT. They significantly reduced the number of cells containing mutant HTT aggregates and subsequent apoptosis in Neuro2A cells. Additionally, in FRAP assay, mobile fraction of mutant HTT aggregates was increased in the presence of MLF1 or MLF2. Further, MLF1 could release transcription factors like p53, CBP and CREB from mutant HTT aggregates. Moreover, in HeLa cell co-expressing mutant HTT exon1 and full length MLF1, p53 was released from the aggregates, leading to the recovery of the expression of the GADD45A transcript, a p53 regulated gene. Taking together, these results showed that MLF1 and MLF2 modulated the formation of aggregates and induction of apoptosis as well as the expressions of genes indirectly.
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Affiliation(s)
- Manisha Banerjee
- Crystallography & Molecular Biology Division and Structural Genomics Section, Saha Institute of Nuclear Physics, 1/AF, Bidhan Nagar, Kolkata, 700064, India.
| | - Moumita Datta
- Crystallography & Molecular Biology Division and Structural Genomics Section, Saha Institute of Nuclear Physics, 1/AF, Bidhan Nagar, Kolkata, 700064, India
| | - Nitai P Bhattacharyya
- Crystallography & Molecular Biology Division and Structural Genomics Section, Saha Institute of Nuclear Physics, 1/AF, Bidhan Nagar, Kolkata, 700064, India.
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91
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Fan Y, Wang N, Rocchi A, Zhang W, Vassar R, Zhou Y, He C. Identification of natural products with neuronal and metabolic benefits through autophagy induction. Autophagy 2016; 13:41-56. [PMID: 27791467 DOI: 10.1080/15548627.2016.1240855] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Autophagy is a housekeeping lysosomal degradation pathway important for cellular survival, homeostasis and function. Various disease models have shown that upregulation of autophagy may be beneficial to combat disease pathogenesis. However, despite several recently reported small-molecule screens for synthetic autophagy inducers, natural chemicals of diverse structures and functions have not been included in the synthetic libraries, and characterization of their roles in autophagy has been lacking. To discover novel autophagy-regulating compounds and study their therapeutic mechanisms, we used analytic chemistry approaches to isolate natural phytochemicals from a reservoir of medicinal plants used in traditional remedies. From this pilot plant metabolite library, we identified several novel autophagy-inducing phytochemicals, including Rg2. Rg2 is a steroid glycoside chemical that activates autophagy in an AMPK-ULK1-dependent and MTOR-independent manner. Induction of autophagy by Rg2 enhances the clearance of protein aggregates in a cell-based model, improves cognitive behaviors in a mouse model of Alzheimer disease, and prevents high-fat diet-induced insulin resistance. Thus, we discovered a series of autophagy-inducing phytochemicals from medicinal plants, and found that one of the compounds Rg2 mediates metabolic and neurotrophic effects dependent on activation of the autophagy pathway. These findings may help explain how medicinal plants exert the therapeutic functions against metabolic diseases.
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Affiliation(s)
- Yuying Fan
- a Department of Cell and Molecular Biology , Feinberg School of Medicine, Northwestern University , Chicago , IL , USA.,b Key Laboratory on Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University , Changchun, Jilin , China
| | - Nan Wang
- a Department of Cell and Molecular Biology , Feinberg School of Medicine, Northwestern University , Chicago , IL , USA.,c Key Laboratory of Industrial Microbiology , Ministry of Education and Tianjin City, College of Biotechnology, Tianjin University of Science and Technology , Tianjin , China
| | - Altea Rocchi
- a Department of Cell and Molecular Biology , Feinberg School of Medicine, Northwestern University , Chicago , IL , USA
| | - Weiran Zhang
- a Department of Cell and Molecular Biology , Feinberg School of Medicine, Northwestern University , Chicago , IL , USA
| | - Robert Vassar
- a Department of Cell and Molecular Biology , Feinberg School of Medicine, Northwestern University , Chicago , IL , USA
| | - Yifa Zhou
- b Key Laboratory on Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University , Changchun, Jilin , China
| | - Congcong He
- a Department of Cell and Molecular Biology , Feinberg School of Medicine, Northwestern University , Chicago , IL , USA
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92
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Assessing Basal and Acute Autophagic Responses in the Adult Drosophila Nervous System: The Impact of Gender, Genetics and Diet on Endogenous Pathway Profiles. PLoS One 2016; 11:e0164239. [PMID: 27711219 PMCID: PMC5053599 DOI: 10.1371/journal.pone.0164239] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/21/2016] [Indexed: 11/28/2022] Open
Abstract
The autophagy pathway is critical for the long-term homeostasis of cells and adult organisms and is often activated during periods of stress. Reduced pathway efficacy plays a central role in several progressive neurological disorders that are associated with the accumulation of cytotoxic peptides and protein aggregates. Previous studies have shown that genetic and transgenic alterations to the autophagy pathway impacts longevity and neural aggregate profiles of adult Drosophila. In this study, we have identified methods to measure the acute in vivo induction of the autophagy pathway in the adult fly CNS. Our findings indicate that the genotype, age, and gender of adult flies can influence pathway responses. Further, we demonstrate that middle-aged male flies exposed to intermittent fasting (IF) had improved neuronal autophagic profiles. IF-treated flies also had lower neural aggregate profiles, maintained more youthful behaviors and longer lifespans, when compared to ad libitum controls. In summary, we present methodology to detect dynamic in vivo changes that occur to the autophagic profiles in the adult Drosophila CNS and that a novel IF-treatment protocol improves pathway response in the aging nervous system.
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93
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Ylä-Anttila P, Mikkonen E, Happonen KE, Holland P, Ueno T, Simonsen A, Eskelinen EL. RAB24 facilitates clearance of autophagic compartments during basal conditions. Autophagy 2016; 11:1833-48. [PMID: 26325487 DOI: 10.1080/15548627.2015.1086522] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
RAB24 belongs to a family of small GTPases and has been implicated to function in autophagy. Here we confirm the intracellular localization of RAB24 to autophagic vacuoles with immuno electron microscopy and cell fractionation, and show that prenylation and guanine nucleotide binding are necessary for the targeting of RAB24 to autophagic compartments. Further, we show that RAB24 plays a role in the maturation and/or clearance of autophagic compartments under nutrient-rich conditions, but not during short amino acid starvation. Quantitative electron microscopy shows an increase in the numbers of late autophagic compartments in cells silenced for RAB24, and mRFP-GFP-LC3 probe and autophagy flux experiments indicate that this is due to a hindrance in their clearance. Formation of autophagosomes is shown to be unaffected by RAB24-silencing with siRNA. A defect in aggregate clearance in the absence of RAB24 is also shown in cells forming polyglutamine aggregates. This study places RAB24 function in the termination of the autophagic process under nutrient-rich conditions.
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Affiliation(s)
- Päivi Ylä-Anttila
- a Department of Biosciences, Division of Biochemistry and Biotechnology; University of Helsinki ; Helsinki , Finland
| | - Elisa Mikkonen
- a Department of Biosciences, Division of Biochemistry and Biotechnology; University of Helsinki ; Helsinki , Finland
| | - Kaisa E Happonen
- a Department of Biosciences, Division of Biochemistry and Biotechnology; University of Helsinki ; Helsinki , Finland
| | - Petter Holland
- b Department of Biochemistry, Institute of Basic Medical Sciences; University of Oslo ; Oslo , Norway
| | - Takashi Ueno
- c Laboratory of Proteomics and Biomolecular Science; Research Support Center; Juntendo University Graduate School of Medicine ; Tokyo , Japan
| | - Anne Simonsen
- b Department of Biochemistry, Institute of Basic Medical Sciences; University of Oslo ; Oslo , Norway
| | - Eeva-Liisa Eskelinen
- a Department of Biosciences, Division of Biochemistry and Biotechnology; University of Helsinki ; Helsinki , Finland
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94
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Procaccini C, Santopaolo M, Faicchia D, Colamatteo A, Formisano L, de Candia P, Galgani M, De Rosa V, Matarese G. Role of metabolism in neurodegenerative disorders. Metabolism 2016; 65:1376-90. [PMID: 27506744 DOI: 10.1016/j.metabol.2016.05.018] [Citation(s) in RCA: 152] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/30/2016] [Accepted: 05/31/2016] [Indexed: 01/12/2023]
Abstract
Along with the increase in life expectancy over the last century, the prevalence of age-related disorders, such as neurodegenerative diseases continues to rise. This is the case of Alzheimer's, Parkinson's, Huntington's diseases and Multiple sclerosis, which are chronic disorders characterized by neuronal loss in motor, sensory or cognitive systems. Accumulating evidence has suggested the presence of a strong correlation between metabolic changes and neurodegeneration. Indeed epidemiologic studies have shown strong associations between obesity, metabolic dysfunction, and neurodegeneration, while animal models have provided insights into the complex relationships between these conditions. In this context, hormones such as leptin, ghrelin, insulin and IGF-1 seem to play a key role in the regulation of neuronal damage, toxic insults and several other neurodegenerative processes. This review aims to presenting the most recent evidence supporting the crosstalk linking energy metabolism and neurodegeneration, and will focus on metabolic manipulation as a possible therapeutic tool in the prevention and treatment of neurodegenerative diseases.
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Affiliation(s)
- Claudio Procaccini
- Laboratorio di Immunologia, Istituto di Endocrinologia e Oncologia Sperimentale, Consiglio Nazionale delle Ricerche (IEOS-CNR) c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II", 80131, Napoli, Italy
| | - Marianna Santopaolo
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II", 80131, Napoli, Italy
| | - Deriggio Faicchia
- Dipartimento di Scienze Mediche Traslazionali, Università di Napoli "Federico II", 80131, Napoli, Italy
| | - Alessandra Colamatteo
- Unità di NeuroImmunologia, IRCCS Fondazione Santa Lucia, 00143, Roma, Italy; Dipartimento di Medicina e Chirurgia, Università degli Studi di Salerno, Baronissi Campus, 84081, Baronissi, Salerno, Italy
| | - Luigi Formisano
- Divisione di Farmacologia, Dipartimento di Scienze e Tecnologie, Università degli Studi del Sannio, 82100, Benevento, Italy
| | | | - Mario Galgani
- Laboratorio di Immunologia, Istituto di Endocrinologia e Oncologia Sperimentale, Consiglio Nazionale delle Ricerche (IEOS-CNR) c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II", 80131, Napoli, Italy
| | - Veronica De Rosa
- Laboratorio di Immunologia, Istituto di Endocrinologia e Oncologia Sperimentale, Consiglio Nazionale delle Ricerche (IEOS-CNR) c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II", 80131, Napoli, Italy; Unità di NeuroImmunologia, IRCCS Fondazione Santa Lucia, 00143, Roma, Italy
| | - Giuseppe Matarese
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II", 80131, Napoli, Italy.
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95
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Fraldi A, Klein AD, Medina DL, Settembre C. Brain Disorders Due to Lysosomal Dysfunction. Annu Rev Neurosci 2016; 39:277-95. [DOI: 10.1146/annurev-neuro-070815-014031] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Alessandro Fraldi
- Telethon Institute of Genetics and Medicine (TIGEM), 80078 Pozzuoli, Italy
| | - Andrés D. Klein
- Telethon Institute of Genetics and Medicine (TIGEM), 80078 Pozzuoli, Italy
| | - Diego L. Medina
- Telethon Institute of Genetics and Medicine (TIGEM), 80078 Pozzuoli, Italy
| | - Carmine Settembre
- Telethon Institute of Genetics and Medicine (TIGEM), 80078 Pozzuoli, Italy
- Dulbecco Telethon Institute, 80078 Pozzuoli, Italy
- Medical Genetics Unit, Department of Medical and Translational Science, Federico II University, 80131 Naples, Italy; ,
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96
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Saffert P, Adamla F, Schieweck R, Atkins JF, Ignatova Z. An Expanded CAG Repeat in Huntingtin Causes +1 Frameshifting. J Biol Chem 2016; 291:18505-13. [PMID: 27382061 DOI: 10.1074/jbc.m116.744326] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Indexed: 01/08/2023] Open
Abstract
Maintenance of triplet decoding is crucial for the expression of functional protein because deviations either into the -1 or +1 reading frames are often non-functional. We report here that expression of huntingtin (Htt) exon 1 with expanded CAG repeats, implicated in Huntington pathology, undergoes a sporadic +1 frameshift to generate from the CAG repeat a trans-frame AGC repeat-encoded product. This +1 recoding is exclusively detected in pathological Htt variants, i.e. those with expanded repeats with more than 35 consecutive CAG codons. An atypical +1 shift site, UUC C at the 5' end of CAG repeats, which has some resemblance to the influenza A virus shift site, triggers the +1 frameshifting and is enhanced by the increased propensity of the expanded CAG repeats to form a stem-loop structure. The +1 trans-frame-encoded product can directly influence the aggregation of the parental Htt exon 1.
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Affiliation(s)
- Paul Saffert
- From the Institute of Biochemistry, University of Potsdam, 14467 Potsdam, Germany
| | - Frauke Adamla
- Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, 20146 Hamburg, Germany
| | - Rico Schieweck
- From the Institute of Biochemistry, University of Potsdam, 14467 Potsdam, Germany
| | - John F Atkins
- the School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland, and the Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112
| | - Zoya Ignatova
- From the Institute of Biochemistry, University of Potsdam, 14467 Potsdam, Germany, Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, 20146 Hamburg, Germany,
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97
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Cui D, Xiong X, Zhao Y. Cullin-RING ligases in regulation of autophagy. Cell Div 2016; 11:8. [PMID: 27293474 PMCID: PMC4902950 DOI: 10.1186/s13008-016-0022-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/27/2016] [Indexed: 12/25/2022] Open
Abstract
Cullin-RING ligases (CRLs), the largest E3 ubiquitin ligase family, promote ubiquitination and degradation of various cellular key regulators involved in a broad array of physiological and pathological processes, including cell cycle progression, signal transduction, transcription, cardiomyopathy, and tumorigenesis. Autophagy, an intracellular catabolic reaction that delivers cytoplasmic components to lysosomes for degradation, is crucial for cellular metabolism and homeostasis. The dysfunction of autophagy has been proved to associate with a variety of human diseases. Recent evidences revealed the emerging roles of CRLs in the regulation of autophagy. In this review, we will focus mainly on recent advances in our understandings of the regulation of autophagy by CRLs and the cross-talk between CRLs and autophagy, two degradation systems. We will also discuss the pathogenesis of human diseases associated with the dysregulation of CRLs and autophagy. Finally, we will discuss current efforts and future perspectives on basic and translational research on CRLs and autophagy.
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Affiliation(s)
- Danrui Cui
- Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, 79 Qing-Chun Road, Hangzhou, Zhejiang 310003 People's Republic of China ; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kai-Xuan Road, Hangzhou, Zhejiang 310029 People's Republic of China
| | - Xiufang Xiong
- Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kai-Xuan Road, Hangzhou, Zhejiang 310029 People's Republic of China
| | - Yongchao Zhao
- Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, 79 Qing-Chun Road, Hangzhou, Zhejiang 310003 People's Republic of China ; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kai-Xuan Road, Hangzhou, Zhejiang 310029 People's Republic of China
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98
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Metformin Improves Functional Recovery After Spinal Cord Injury via Autophagy Flux Stimulation. Mol Neurobiol 2016; 54:3327-3341. [PMID: 27167128 DOI: 10.1007/s12035-016-9895-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Accepted: 04/21/2016] [Indexed: 12/15/2022]
Abstract
Spinal cord injury (SCI) is a severe neurological disease with few efficacious drugs. Autophagy is a cellular process to confront with stress after SCI and considered to be a therapeutic target of SCI. In this study, we investigated the therapeutic effect of metformin on functional recovery after SCI and its underlying mechanism of autophagy regulation. Using a rat model of traumatic SCI, we found improved function recovery which was paralleled by a reduction of apoptosis after metformin treatment. We further examined autophagy via detecting autophagosomes by transmission electron microscopy and immunofluorescence, as well as autophagy markers by western blot in each groups. The results showed that the number of autophagosomes and expression of autophagy markers such as LC3 and beclin1 were increased in SCI group, while autophagy substrate protein p62 as well as ubiquitinated proteins were found to accumulate in SCI group, indicating an impaired autophagy flux in SCI. But, metformin treatment attenuated the accumulation of p62 and ubiquitinated proteins, suggesting a stimulative effect of autophagy flux by metformin. Blockage of autophagy flux by chloroquine partially abolished the apoptosis inhibition and functional recovery effect of metformin on SCI, which suggested that the protective effect of metformin on SCI was through autophagy flux stimulation. Activation of AMPK as well as inhibition of its downstream mTOR signaling were detected under metformin treatment in vivo and in vitro; inhibition of AMPK signaling by compound C suppressed autophagy flux induced by metformin in vitro, indicating that AMPK signaling was involved in the effect of metformin on autophagy flux regulation. Together, these results illustrated that metformin improved functional recovery effect through autophagy flux stimulation and implied metformin to be a potential drug for SCI therapy.
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99
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Gao B, Wang D, Sun W, Meng X, Zhang W, Xue D. Differentially expressed microRNA identification and target gene function analysis in starvation-induced autophagy of AR42J pancreatic acinar cells. Mol Med Rep 2016; 14:590-8. [PMID: 27175615 DOI: 10.3892/mmr.2016.5240] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 03/23/2016] [Indexed: 11/05/2022] Open
Abstract
Acute pancreatitis (AP) is a common acute digestive tract disease, with increased morbidity and mortality, and an unclear pathogenesis. Trypsinogen activation in pancreatic acinar cells may be the primary mechanism underlying the development of AP. Previous studies reported that autophagy participates in the formation of acinar cell vacuoles in AP and in the process of trypsinogen activation as an important cause of AP. Furthermore, microRNAs (miRNAs) maintain the autophagy process by regulating the expression of autophagy‑associated genes. In the present study, an in vitro pancreatic acinar cell autophagy model was established using the AR42J starvation‑induced pancreatic acinar cell line. Twenty differentially expressed microRNAs were identified using miRNA microarray. Bioinformatics analysis was used to predict the target genes of miRNAs and analyze the functions of differentially expressed miRNAs. The results demonstrated that only the downregulated miRNA rno‑miR‑148b‑3p predicted 593 target genes with a statistical significance (P<0.05), from which 10 genes were autophagy‑associated. The results of gene ontology and pathway analyses demonstrated that the target genes of miRNAs were enriched in the Response to insulin stimulus, Regulation of cell death and the Insulin signaling pathways (P<0.05, FDR<0.05). In addition, protein‑protein interaction network analysis demonstrated a widespread interaction among the 593 target genes. The results of the present study may provide novel targets for research on the mechanisms of autophagy-promoted AP and AP treatment.
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Affiliation(s)
- Bo Gao
- Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
| | - Duanping Wang
- Department of General Surgery, The First Hospital of Qiqihar, Qiqihar, Heilongjiang 161005, P.R. China
| | - Wang Sun
- Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
| | - Xianzhi Meng
- Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
| | - Weihui Zhang
- Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
| | - Dongbo Xue
- Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
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100
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Abstract
Autophagy is an essential homeostatic process for degrading cellular cargo. Aging organelles and protein aggregates are degraded by the autophagosome-lysosome pathway, which is particularly crucial in neurons. There is increasing evidence implicating defective autophagy in neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease, Parkinson's disease and Huntington's disease. Recent work using live-cell imaging has identified autophagy as a predominantly polarized process in neuronal axons; autophagosomes preferentially form at the axon tip and undergo retrograde transport back towards the cell body. Autophagosomes engulf cargo including damaged mitochondria (mitophagy) and protein aggregates, and subsequently fuse with lysosomes during axonal transport to effectively degrade their internalized cargo. In this Cell Science at a Glance article and the accompanying poster, we review recent progress on the dynamics of the autophagy pathway in neurons and highlight the defects observed at each step of this pathway during neurodegeneration.
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Affiliation(s)
- Yvette C Wong
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104 USA
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104 USA
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