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Bhatt V, Tiwari AK. Sirtuins, a key regulator of ageing and age-related neurodegenerative diseases. Int J Neurosci 2023; 133:1167-1192. [PMID: 35549800 DOI: 10.1080/00207454.2022.2057849] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 03/15/2022] [Indexed: 10/18/2022]
Abstract
Sirtuins are Nicotinamide Adenine Dinucleotide (NAD+) dependent class ІΙΙ histone deacetylases enzymes (HDACs) present from lower to higher organisms such as bacteria (Sulfolobus solfataricus L. major), yeasts (Saccharomyces cerevisiae), nematodes (Caenorhabditis elegans), fruit flies (Drosophila melanogaster), humans (Homo sapiens sapiens), even in plants such as rice (Oryza sativa), thale cress (Arabidopsis thaliana), vine (Vitis vinifera L.) tomato (Solanum lycopersicum). Sirtuins play an important role in the regulation of various vital cellular functions during metabolism and ageing. It also plays a neuroprotective role by modulating several biological pathways such as apoptosis, DNA repair, protein aggregation, and inflammatory processes associated with ageing and neurodegenerative diseases. In this review, we have presented an updated Sirtuins and its role in ageing and age-related neurodegenerative diseases (NDDs). Further, this review also describes the therapeutic potential of Sirtuins and the use of Sirtuins inhibitor/activator for altering the NDDs disease pathology.
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Affiliation(s)
- Vidhi Bhatt
- Department of Biological Sciences & Biotechnology, Institute of Advanced Research, Koba, Gandhinagar, Gujarat, India
| | - Anand Krishna Tiwari
- Department of Biological Sciences & Biotechnology, Institute of Advanced Research, Koba, Gandhinagar, Gujarat, India
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Sánchez-Vidaña DI, Li J, Abokyi S, Chan JNM, Ngai SPC, Lau BWM. In vitro methods in autophagy research: Applications in neurodegenerative diseases and mood disorders. Front Mol Neurosci 2023; 16:1168948. [PMID: 37122628 PMCID: PMC10130388 DOI: 10.3389/fnmol.2023.1168948] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Accepted: 03/14/2023] [Indexed: 05/02/2023] Open
Abstract
Background Autophagy is a conserved physiological intracellular mechanism responsible for the degradation and recycling of cytoplasmic constituents (e.g., damaged organelles, and protein aggregates) to maintain cell homeostasis. Aberrant autophagy has been observed in neurodegenerative diseases, including Alzheimer's Disease (AD), Parkinson's Disease (PD), Amyotrophic Lateral Sclerosis (ALS), and Huntington's Disease (HD), and recently aberrant autophagy has been associated with mood disorders, such as depression. Several in vitro methods have been developed to study the complex and tightly regulated mechanisms of autophagy. In vitro methods applied to autophagy research are used to identify molecular key players involved in dysfunctional autophagy and to screen autophagy regulators with therapeutic applications in neurological diseases and mood disorders. Therefore, the aims of this narrative review are (1) to compile information on the cell-based methods used in autophagy research, (2) to discuss their application, and (3) to create a catalog of traditional and novel in vitro methods applied in neurodegenerative diseases and depression. Methods Pubmed and Google Scholar were used to retrieve relevant in vitro studies on autophagy mechanisms in neurological diseases and depression using a combination of search terms per mechanism and disease (e.g., "macroautophagy" and "Alzheimer's disease"). A total of 37 studies were included (14 in PD, 8 in AD, 5 in ALS, 5 in %, and 5 in depression). Results A repertoire of traditional and novel approaches and techniques was compiled and discussed. The methods used in autophagy research focused on the mechanisms of macroautophagy, microautophagy, and chaperone-mediated autophagy. The in vitro tools presented in this review can be applied to explore pathophysiological mechanisms at a molecular level and to screen for potential therapeutic agents and their mechanism of action, which can be of great importance to understanding disease biology and potential therapeutic options in the context of neurodegenerative disorders and depression. Conclusion This is the first review to compile, discuss, and provide a catalog of traditional and novel in vitro models applied to neurodegenerative disorders and depression.
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Affiliation(s)
- Dalinda Isabel Sánchez-Vidaña
- Department of Rehabilitation Sciences, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
- Mental Health Research Centre, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
- *Correspondence: Dalinda Isabel Sánchez-Vidaña, ;
| | - Jingjing Li
- Department of Rehabilitation Sciences, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Samuel Abokyi
- School of Optometry, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Jackie Ngai-Man Chan
- Department of Rehabilitation Sciences, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Shirley Pui-Ching Ngai
- Department of Rehabilitation Sciences, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Benson Wui-Man Lau
- Department of Rehabilitation Sciences, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
- Mental Health Research Centre, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
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3
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Hiura F, Kawabata Y, Aoki T, Mizokami A, Jimi E. Inhibition of the ATG4-LC3 pathway suppressed osteoclast maturation. Biochem Biophys Res Commun 2022; 632:40-47. [DOI: 10.1016/j.bbrc.2022.09.065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 09/12/2022] [Accepted: 09/15/2022] [Indexed: 11/24/2022]
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Zhang L, Liu X, Huang M, Wang R, Zhu W, Li Y, Shen L, Li C. Metformin Inhibits HaCaT Cell Proliferation Under Hyperlipidemia Through Reducing Reactive Oxygen Species via FOXO3 Activation. Clin Cosmet Investig Dermatol 2022; 15:1403-1413. [PMID: 35910506 PMCID: PMC9326038 DOI: 10.2147/ccid.s368845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 07/11/2022] [Indexed: 11/23/2022]
Abstract
Purpose Metformin (MET) has been proved to be effective for the treatment of psoriasis. The mechanisms of its action under the hyperlipidemia have yet to be fully elucidated. Here, we investigated the effect of metformin on the cell proliferation induced by hyperlipidemia and the underlying mechanism in immortalized human keratinocyte cell line (HaCat). Methods Wild-type or FOXO3 knockdown HaCat cells were treated with free fatty acids (FFA) for 10 days and then co-treated with metformin for another 4 days. Triglyceride (TG) level, cell viability, proliferation, apoptosis, antioxidant enzymes, reactive oxygen species (ROS) levels, as well as the transcription activity of FOXO3 were analyzed. Results Metformin decreased HaCaT cell proliferation and induced cell apoptosis after FFA treatment. Metformin was found to significantly increase the expressions and the activities of superoxide dismutase (SOD) as well as catalase (CAT), and reduced the reactive oxygen species (ROS) level. Metformin significantly promoted the autophagy and increase FOXO3 protein level in the nucleus under hyperlipidemia. However, all of the effects from metformin were partially blocked by FOXO3 knockdown. Conclusion This study demonstrated that under the hyperlipidemia, metformin has significant antiproliferation and proapoptosis effects by reducing ROS level as well as increasing autophagy. All of these effects from metformin were through FOXO3-dependent pathway.
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Affiliation(s)
- Li Zhang
- Department of Dermatology, The First Medical Center of Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Xiaoling Liu
- Department of Dermatology, The First Medical Center of Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Min Huang
- Department of Dermatology, The First Medical Center of Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Rui Wang
- Department of Dermatology, The First Medical Center of Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Wenwei Zhu
- Department of Dermatology, The First Medical Center of Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Yu Li
- Department of Dermatology, The Fifth Medical Center of Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Lin Shen
- Department of Dermatology, The First Medical Center of Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Chengxin Li
- Department of Dermatology, The First Medical Center of Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
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Bastien J, Menon S, Messa M, Nyfeler B. Molecular targets and approaches to restore autophagy and lysosomal capacity in neurodegenerative disorders. Mol Aspects Med 2021; 82:101018. [PMID: 34489092 DOI: 10.1016/j.mam.2021.101018] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/18/2021] [Accepted: 08/25/2021] [Indexed: 01/18/2023]
Abstract
Autophagy is a catabolic process that promotes cellular fitness by clearing aggregated protein species, pathogens and damaged organelles through lysosomal degradation. The autophagic process is particularly important in the nervous system where post-mitotic neurons rely heavily on protein and organelle quality control in order to maintain cellular health throughout the lifetime of the organism. Alterations of autophagy and lysosomal function are hallmarks of various neurodegenerative disorders. In this review, we conceptualize some of the mechanistic and genetic evidence pointing towards autophagy and lysosomal dysfunction as a causal driver of neurodegeneration. Furthermore, we discuss rate-limiting pathway nodes and potential approaches to restore pathway activity, from autophagy initiation, cargo sequestration to lysosomal capacity.
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Affiliation(s)
- Julie Bastien
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Suchithra Menon
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Mirko Messa
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Beat Nyfeler
- Novartis Institutes for BioMedical Research, Basel, Switzerland.
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Kim H, Seong J. Fluorescent Protein-Based Autophagy Biosensors. MATERIALS 2021; 14:ma14113019. [PMID: 34199451 PMCID: PMC8199620 DOI: 10.3390/ma14113019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/28/2021] [Accepted: 05/30/2021] [Indexed: 11/16/2022]
Abstract
Autophagy is an essential cellular process of self-degradation for dysfunctional or unnecessary cytosolic constituents and organelles. Dysregulation of autophagy is thus involved in various diseases such as neurodegenerative diseases. To investigate the complex process of autophagy, various biochemical, chemical assays, and imaging methods have been developed. Here we introduce various methods to study autophagy, in particular focusing on the review of designs, principles, and limitations of the fluorescent protein (FP)-based autophagy biosensors. Different physicochemical properties of FPs, such as pH-sensitivity, stability, brightness, spectral profile, and fluorescence resonance energy transfer (FRET), are considered to design autophagy biosensors. These FP-based biosensors allow for sensitive detection and real-time monitoring of autophagy progression in live cells with high spatiotemporal resolution. We also discuss future directions utilizing an optobiochemical strategy to investigate the in-depth mechanisms of autophagy. These cutting-edge technologies will further help us to develop the treatment strategies of autophagy-related diseases.
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Affiliation(s)
- Heejung Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea;
- Department of Converging Science and Technology, Kyung Hee University, Seoul 02453, Korea
| | - Jihye Seong
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea;
- Department of Converging Science and Technology, Kyung Hee University, Seoul 02453, Korea
- Correspondence:
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Li X, Sun L, Yan G, Yan X. PFKP facilitates ATG4B phosphorylation during amino acid deprivation-induced autophagy. Cell Signal 2021; 82:109956. [PMID: 33607258 DOI: 10.1016/j.cellsig.2021.109956] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 01/29/2021] [Accepted: 02/13/2021] [Indexed: 12/09/2022]
Abstract
ATG4B facilitates autophagy by promoting autophagosome maturation through the reversible lipidation and delipidation of LC3. Recent reports have shown that phosphorylation of ATG4B regulates its activity and LC3 processing, leading to modulate autophagy activity. However, the mechanism about how ATG4B phosphorylation is involved in amino acid deprivation-induced autophagy is unclear. Here, we combined the tandem affinity purification with mass spectrometry (MS) and identified the ATG4B-interacting proteins including its well-known partner gamma-aminobutyric acid receptor-associated protein (GABARAP, a homolog of LC3) and phosphofructokinase 1 platelet isoform (PFKP). Further immunoprecipitation assays showed that amino acid deprivation strengthened the interaction between ATG4B and PFKP. By genetic depletion of PFKP using CRISPR/Cas9, we uncovered that PFKP loss reduced the degradation of LC3-II and p62 due to a partial block in autophagic flux. Furthermore, MS analysis of Flag-tagged ATG4B immunoprecipitates identified phosphorylation of ATG4B serine 34 residue (S34) and PFKP serine 386 residue (S386) under amino acid deprivation condition. In vitro kinase assay validated that PFKP functioning as a protein kinase phosphorylated ATG4B at S34. This phosphorylation could enhance ATG4B activity and p62 degradation. In addition, PFKP S386 phosphorylation was important to ATG4B S34 phosphorylation and autophagy in HEK293T cells. In brief, our findings describe that PFKP, a rate-limiting enzyme in the glycolytic pathway, functions as a protein kinase for ATG4B to regulate ATG4B activity and autophagy under amino acid deprivation condition.
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Affiliation(s)
- Xiuzhi Li
- State Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China; Hubei Provincial Engineering Laboratory for Pig Precision Feeding and Feed Safety Technology, Wuhan, Hubei 430070, China
| | - Lingling Sun
- State Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China; Hubei Provincial Engineering Laboratory for Pig Precision Feeding and Feed Safety Technology, Wuhan, Hubei 430070, China
| | - Guokai Yan
- State Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China; Hubei Provincial Engineering Laboratory for Pig Precision Feeding and Feed Safety Technology, Wuhan, Hubei 430070, China
| | - Xianghua Yan
- State Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei 430070, China; Hubei Provincial Engineering Laboratory for Pig Precision Feeding and Feed Safety Technology, Wuhan, Hubei 430070, China.
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8
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Xia F, Liu P, Li M. The regulatory factors and pathological roles of autophagy-related protein 4 in diverse diseases: Recent research advances. Med Res Rev 2020; 41:1644-1675. [PMID: 33314291 DOI: 10.1002/med.21772] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 12/01/2020] [Accepted: 12/02/2020] [Indexed: 12/12/2022]
Abstract
Macroautophagy (autophagy) is an evolutionarily conserved and dynamic degradation/recycling pathway in which portions of the cytoplasm, such as dysfunctional proteins and surplus organelles, are engulfed by double-membrane bound vesicles through a lysosome-dependent process. As the only proteolytic enzyme of the core mammalian autophagy proteins, autophagy-related protein 4 (ATG4) primes newly synthesized pro-light chain 3 (LC3) to form LC3-I that attaches to phosphatidylethanolamine and delipidates LC3-PE to LC3-I for recycling. Besides autophagy, ATG4 has been shown to be involved in regulating various biological and pathological processes. The roles of ATG4 in cancer therapy, a methodology for ATG4 activity detection, and the discovery of chemical modulators have been well-reviewed. However, a comprehensive summary on how ATG4 is regulated by multiple factors and, thereby, how ATG4 influences autophagy or other pathways remains lacking. In this paper, we summarize multiple processes and molecules that regulate the activity of ATG4, such as micro-RNAs, posttranslational modifications, and small molecules. Additionally, we focus on the relationship between ATG4 and diverse diseases, including cancer, neurodegeneration, microbial infection, and other diseases. It provides insight regarding potential ATG4-targeted therapeutic opportunities, which could be beneficial for future studies and human health.
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Affiliation(s)
- Fan Xia
- Department of Pharmacology and Toxicology, Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, National and Local United Engineering Lab of Druggability and New Drugs Evaluation, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Peiqing Liu
- Department of Pharmacology and Toxicology, Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, National and Local United Engineering Lab of Druggability and New Drugs Evaluation, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Min Li
- Department of Pharmacology and Toxicology, Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, National and Local United Engineering Lab of Druggability and New Drugs Evaluation, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
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9
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García-Huerta P, Troncoso-Escudero P, Wu D, Thiruvalluvan A, Cisternas-Olmedo M, Henríquez DR, Plate L, Chana-Cuevas P, Saquel C, Thielen P, Longo KA, Geddes BJ, Lederkremer GZ, Sharma N, Shenkman M, Naphade S, Sardi SP, Spichiger C, Richter HG, Court FA, Tshilenge KT, Ellerby LM, Wiseman RL, Gonzalez-Billault C, Bergink S, Vidal RL, Hetz C. Insulin-like growth factor 2 (IGF2) protects against Huntington's disease through the extracellular disposal of protein aggregates. Acta Neuropathol 2020; 140:737-764. [PMID: 32642868 PMCID: PMC8513574 DOI: 10.1007/s00401-020-02183-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 06/06/2020] [Accepted: 06/19/2020] [Indexed: 12/13/2022]
Abstract
Impaired neuronal proteostasis is a salient feature of many neurodegenerative diseases, highlighting alterations in the function of the endoplasmic reticulum (ER). We previously reported that targeting the transcription factor XBP1, a key mediator of the ER stress response, delays disease progression and reduces protein aggregation in various models of neurodegeneration. To identify disease modifier genes that may explain the neuroprotective effects of XBP1 deficiency, we performed gene expression profiling of brain cortex and striatum of these animals and uncovered insulin-like growth factor 2 (Igf2) as the major upregulated gene. Here, we studied the impact of IGF2 signaling on protein aggregation in models of Huntington's disease (HD) as proof of concept. Cell culture studies revealed that IGF2 treatment decreases the load of intracellular aggregates of mutant huntingtin and a polyglutamine peptide. These results were validated using induced pluripotent stem cells (iPSC)-derived medium spiny neurons from HD patients and spinocerebellar ataxia cases. The reduction in the levels of mutant huntingtin was associated with a decrease in the half-life of the intracellular protein. The decrease in the levels of abnormal protein aggregation triggered by IGF2 was independent of the activity of autophagy and the proteasome pathways, the two main routes for mutant huntingtin clearance. Conversely, IGF2 signaling enhanced the secretion of soluble mutant huntingtin species through exosomes and microvesicles involving changes in actin dynamics. Administration of IGF2 into the brain of HD mice using gene therapy led to a significant decrease in the levels of mutant huntingtin in three different animal models. Moreover, analysis of human postmortem brain tissue and blood samples from HD patients showed a reduction in IGF2 level. This study identifies IGF2 as a relevant factor deregulated in HD, operating as a disease modifier that buffers the accumulation of abnormal protein species.
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Affiliation(s)
- Paula García-Huerta
- Faculty of Medicine, Biomedical Neuroscience Institute, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Sector B, Second Floor, Faculty of Medicine, University of Chile, Independencia 1027, P.O. Box 70086, Santiago, Chile
| | - Paulina Troncoso-Escudero
- Faculty of Medicine, Biomedical Neuroscience Institute, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Sector B, Second Floor, Faculty of Medicine, University of Chile, Independencia 1027, P.O. Box 70086, Santiago, Chile
- Center for Integrative Biology, Faculty of Sciences, University Mayor, Santiago, Chile
| | - Di Wu
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Arun Thiruvalluvan
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Marisol Cisternas-Olmedo
- Faculty of Medicine, Biomedical Neuroscience Institute, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
- Center for Integrative Biology, Faculty of Sciences, University Mayor, Santiago, Chile
| | - Daniel R Henríquez
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
- Department of Cell Biology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Lars Plate
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Pedro Chana-Cuevas
- Faculty of Medical Sciences, University of Santiago de Chile, Santiago, Chile
| | - Cristian Saquel
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
- Center for Integrative Biology, Faculty of Sciences, University Mayor, Santiago, Chile
| | - Peter Thielen
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, 02115, USA
| | | | | | - Gerardo Z Lederkremer
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- George Wise Faculty of Life Sciences, School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Neeraj Sharma
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- George Wise Faculty of Life Sciences, School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Marina Shenkman
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- George Wise Faculty of Life Sciences, School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Swati Naphade
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - S Pablo Sardi
- Rare and Neurological Diseases Therapeutic Area, Sanofi, 49 New York Avenue, Framingham, MA, 01701, USA
| | - Carlos Spichiger
- Faculty of Sciences, Institute of Biochemistry and Microbiology, University Austral of Chile, Valdivia, Chile
| | - Hans G Richter
- Faculty of Medicine, Institute of Anatomy, Histology and Pathology, University Austral of Chile, Valdivia, Chile
| | - Felipe A Court
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
- Center for Integrative Biology, Faculty of Sciences, University Mayor, Santiago, Chile
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | | | - Lisa M Ellerby
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - R Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Christian Gonzalez-Billault
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
- Department of Cell Biology, Faculty of Sciences, University of Chile, Santiago, Chile
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Steven Bergink
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Rene L Vidal
- Faculty of Medicine, Biomedical Neuroscience Institute, University of Chile, Santiago, Chile.
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile.
- Center for Integrative Biology, Faculty of Sciences, University Mayor, Santiago, Chile.
| | - Claudio Hetz
- Faculty of Medicine, Biomedical Neuroscience Institute, University of Chile, Santiago, Chile.
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile.
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Sector B, Second Floor, Faculty of Medicine, University of Chile, Independencia 1027, P.O. Box 70086, Santiago, Chile.
- Buck Institute for Research on Aging, Novato, CA, 94945, USA.
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Exercise and dietary intervention ameliorate high-fat diet-induced NAFLD and liver aging by inducing lipophagy. Redox Biol 2020; 36:101635. [PMID: 32863214 PMCID: PMC7365984 DOI: 10.1016/j.redox.2020.101635] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 06/25/2020] [Accepted: 07/03/2020] [Indexed: 02/08/2023] Open
Abstract
Exercise and dietary intervention are currently available strategies to treat nonalcoholic fatty liver disease (NAFLD), while the underlying mechanism remains controversial. Emerging evidence shows that lipophagy is involved in the inhibition of the lipid droplets accumulation. However, it is still unclear if exercise and dietary intervention improve NAFLD through regulating lipophagy, and how exercise of skeletal muscle can modulate lipid metabolism in liver. Moreover, NAFLD is associated with aging, and little is known about the effect of lipid accumulation on aging process. Here in vivo and in vitro models, we found that exercise and dietary intervention reduced lipid droplets formation, decreased hepatic triglyceride in the liver induced by high-fat diet. Exercise and dietary intervention enhanced the lipophagy by activating AMPK/ULK1 and inhibiting Akt/mTOR/ULK1 pathways respectively. Furthermore, exercise stimulated FGF21 production in the muscle, followed by secretion to the circulation to promote the lipophagy in the liver via an AMPK-dependent pathway. Importantly, for the first time, we demonstrated that lipid accumulation exacerbated liver aging, which was ameliorated by exercise and dietary intervention through inducing lipophagy. Our findings suggested a new mechanism of exercise and dietary intervention to improve NAFLD through promoting lipophagy. The study also provided evidence to support that muscle exercise is beneficial to other metabolic organs such as liver. The FGF21-mediated AMPK dependent lipophagy might be a potential drug target for NAFLD and aging caused by lipid metabolic dysfunction.
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Park H, Kang JH, Lee S. Autophagy in Neurodegenerative Diseases: A Hunter for Aggregates. Int J Mol Sci 2020; 21:ijms21093369. [PMID: 32397599 PMCID: PMC7247013 DOI: 10.3390/ijms21093369] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/07/2020] [Accepted: 05/07/2020] [Indexed: 12/14/2022] Open
Abstract
Cells have developed elaborate quality-control mechanisms for proteins and organelles to maintain cellular homeostasis. Such quality-control mechanisms are maintained by conformational folding via molecular chaperones and by degradation through the ubiquitin-proteasome or autophagy-lysosome system. Accumulating evidence suggests that impaired autophagy contributes to the accumulation of intracellular inclusion bodies consisting of misfolded proteins, which is a hallmark of most neurodegenerative diseases. In addition, genetic mutations in core autophagy-related genes have been reported to be linked to neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. Conversely, the pathogenic proteins, such as amyloid β and α-synuclein, are detrimental to the autophagy pathway. Here, we review the recent advances in understanding the relationship between autophagic defects and the pathogenesis of neurodegenerative diseases and suggest autophagy induction as a promising strategy for the treatment of these conditions.
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Affiliation(s)
- Hyungsun Park
- Department of Anatomy, College of Medicine, Inha University, Incheon 22212, Korea;
- Hypoxia-related Disease Research Center, College of Medicine, Inha University, Incheon 22212, Korea;
| | - Ju-Hee Kang
- Hypoxia-related Disease Research Center, College of Medicine, Inha University, Incheon 22212, Korea;
- Department of Pharmacology, College of Medicine, Inha University, Incheon 22212, Korea
| | - Seongju Lee
- Department of Anatomy, College of Medicine, Inha University, Incheon 22212, Korea;
- Hypoxia-related Disease Research Center, College of Medicine, Inha University, Incheon 22212, Korea;
- Correspondence: ; Tel.: +82-32-860-9891
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12
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Agrotis A, Ketteler R. On ATG4B as Drug Target for Treatment of Solid Tumours-The Knowns and the Unknowns. Cells 2019; 9:cells9010053. [PMID: 31878323 PMCID: PMC7016753 DOI: 10.3390/cells9010053] [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] [Received: 12/03/2019] [Revised: 12/17/2019] [Accepted: 12/19/2019] [Indexed: 12/13/2022] Open
Abstract
Autophagy is an evolutionary conserved stress survival pathway that has been shown to play an important role in the initiation, progression, and metastasis of multiple cancers; however, little progress has been made to date in translation of basic research to clinical application. This is partially due to an incomplete understanding of the role of autophagy in the different stages of cancer, and also to an incomplete assessment of potential drug targets in the autophagy pathway. While drug discovery efforts are on-going to target enzymes involved in the initiation phase of the autophagosome, e.g., unc51-like autophagy activating kinase (ULK)1/2, vacuolar protein sorting 34 (Vps34), and autophagy-related (ATG)7, we propose that the cysteine protease ATG4B is a bona fide drug target for the development of anti-cancer treatments. In this review, we highlight some of the recent advances in our understanding of the role of ATG4B in autophagy and its relevance to cancer, and perform a critical evaluation of ATG4B as a druggable cancer target.
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13
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Linsley JW, Tripathi A, Epstein I, Schmunk G, Mount E, Campioni M, Oza V, Barch M, Javaherian A, Nowakowski TJ, Samsi S, Finkbeiner S. Automated four-dimensional long term imaging enables single cell tracking within organotypic brain slices to study neurodevelopment and degeneration. Commun Biol 2019; 2:155. [PMID: 31069265 PMCID: PMC6494885 DOI: 10.1038/s42003-019-0411-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 03/18/2019] [Indexed: 02/08/2023] Open
Abstract
Current approaches for dynamic profiling of single cells rely on dissociated cultures, which lack important biological features existing in tissues. Organotypic slice cultures preserve aspects of structural and synaptic organisation within the brain and are amenable to microscopy, but established techniques are not well adapted for high throughput or longitudinal single cell analysis. Here we developed a custom-built, automated confocal imaging platform, with improved organotypic slice culture and maintenance. The approach enables fully automated image acquisition and four-dimensional tracking of morphological changes within individual cells in organotypic cultures from rodent and human primary tissues for at least 3 weeks. To validate this system, we analysed neurons expressing a disease-associated version of huntingtin (HTT586Q138-EGFP), and observed that they displayed hallmarks of Huntington's disease and died sooner than controls. By facilitating longitudinal single-cell analyses of neuronal physiology, our system bridges scales necessary to attain statistical power to detect developmental and disease phenotypes.
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Affiliation(s)
- Jeremy W Linsley
- Gladstone Center for Systems and Therapeutics, San Francisco, CA 94158 USA
| | - Atmiyata Tripathi
- Gladstone Center for Systems and Therapeutics, San Francisco, CA 94158 USA
| | - Irina Epstein
- Gladstone Center for Systems and Therapeutics, San Francisco, CA 94158 USA
| | - Galina Schmunk
- 2Department of Anatomy, University of California, San Francisco, CA 94158 USA
| | - Elliot Mount
- Gladstone Center for Systems and Therapeutics, San Francisco, CA 94158 USA
| | - Matthew Campioni
- Gladstone Center for Systems and Therapeutics, San Francisco, CA 94158 USA
| | - Viral Oza
- Gladstone Center for Systems and Therapeutics, San Francisco, CA 94158 USA
| | - Mariya Barch
- Gladstone Center for Systems and Therapeutics, San Francisco, CA 94158 USA
| | - Ashkan Javaherian
- Gladstone Center for Systems and Therapeutics, San Francisco, CA 94158 USA
| | - Tomasz J Nowakowski
- 2Department of Anatomy, University of California, San Francisco, CA 94158 USA
| | - Siddharth Samsi
- 3Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Luxembourg, L-4367 Luxembourg
- 9Present Address: MIT Lincoln Laboratory, Lexington, MA 02421 USA
| | - Steven Finkbeiner
- Gladstone Center for Systems and Therapeutics, San Francisco, CA 94158 USA
- 4Neuroscience Graduate Program, University of California, San Francisco, CA 94158 USA
- 5Biomedical Sciences and Neuroscience Graduate Program, University of California, San Francisco, CA 94143 USA
- 6Taube/Koret Center for Neurodegenerative Disease, Gladstone Institutes, San Francisco, CA 94158 USA
- 7Department of Neurology, University of California, San Francisco, CA 94158 USA
- 8Department of Physiology, University of California, San Francisco, CA 94158 USA
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André EM, Daviaud N, Sindji L, Cayon J, Perrot R, Montero-Menei CN. A novel ex vivo Huntington's disease model for studying GABAergic neurons and cell grafts by laser microdissection. PLoS One 2018; 13:e0193409. [PMID: 29505597 PMCID: PMC5837106 DOI: 10.1371/journal.pone.0193409] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 02/09/2018] [Indexed: 02/05/2023] Open
Abstract
Organotypic brain slice cultures have been recently used to study neurodegenerative disorders such as Parkinson’s disease and Huntington’s disease (HD). They preserve brain three-dimensional architecture, synaptic connectivity and brain cells microenvironment. Here, we developed an innovative model of Huntington’s disease from coronal rat brain slices, that include all the areas involved in the pathology. HD-like neurodegeneration was obtained in only one week, in a single step, during organotypic slice preparation, without the use of neurotoxins. HD-like histopathology was analysed and after one week, a reduction of 40% of medium spiny neurons was observed. To analyse new therapeutic approaches in this innovative HD model, we developed a novel protocol of laser microdissection to isolate and analyse by RT-qPCR, grafted cells as well as surrounding tissue of fresh organotypic slices. We determined that laser microdissection could be performed on a 400μm organotypic slice after alcohol dehydration protocol, allowing the analysis of mRNA expression in the rat tissue as well as in grafted cells. In conclusion, we developed a new approach for modeling Huntington's disease ex vivo, and provided a useful innovative method for screening new potential therapies for neurodegenerative diseases especially when associated with laser microdissection.
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Affiliation(s)
- E. M. André
- CRCINA, INSERM, Université de Nantes, Université d’Angers, Angers, France
| | - N. Daviaud
- CRCINA, INSERM, Université de Nantes, Université d’Angers, Angers, France
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - L. Sindji
- CRCINA, INSERM, Université de Nantes, Université d’Angers, Angers, France
| | - J. Cayon
- PACEM, Angers University, Angers, France
| | - R. Perrot
- SCIAM, Angers University, Angers, France
| | - C. N. Montero-Menei
- CRCINA, INSERM, Université de Nantes, Université d’Angers, Angers, France
- * E-mail:
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15
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Chu J, Fu Y, Xu J, Zheng X, Gu Q, Luo X, Dai Q, Zhang S, Liu P, Hong L, Li M. ATG4B inhibitor FMK-9a induces autophagy independent on its enzyme inhibition. Arch Biochem Biophys 2018; 644:29-36. [PMID: 29510087 DOI: 10.1016/j.abb.2018.03.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/07/2018] [Accepted: 03/02/2018] [Indexed: 02/07/2023]
Abstract
Atg4 is essential for autophagosome formation and Atg8 recycle with the function of processing the precursor and the lipidated Atg8-family proteins. Abnormal autophagic activity is involved in a variety of pathophysiological diseases and ATG4B is of interest as a potential therapeutic target due to its key roles in autophagy process. So ATG4B inhibitors are highly needed. FMK-9a is the most potent inhibitor reported so far. In this study, we confirmed FMK-9a could suppress ATG4B activity in vitro and in cells, with an IC50 of 260 nM. Besides, FMK-9a could also attenuate the process of cleavage of pro-LC3 and the delipidation of LC3-PE. Importantly, FMK-9a could induce autophagy both in HeLa and MEF cells regardless of its inhibition on ATG4B activity. Moreover, FMK-9a induced autophagy required FIP200 and ATG5. In conclusion, we demonstrated that ATG4B inhibitor FMK-9a induces autophagy independent on its enzyme inhibition. Thus, FMK-9a may plays multiple roles in autophagy process and cannot simply take it as an ATG4B inhibitor.
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Affiliation(s)
- Jiaqi Chu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China
| | - Yuanyuan Fu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China
| | - Jiecheng Xu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China
| | - Xueping Zheng
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China
| | - Qianqian Gu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China
| | - Xia Luo
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China
| | - Qi Dai
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China
| | - Shuxian Zhang
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China
| | - Peiqing Liu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China
| | - Liang Hong
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China.
| | - Min Li
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, China.
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16
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Masnata M, Cicchetti F. The Evidence for the Spread and Seeding Capacities of the Mutant Huntingtin Protein in in Vitro Systems and Their Therapeutic Implications. Front Neurosci 2017; 11:647. [PMID: 29234268 PMCID: PMC5712341 DOI: 10.3389/fnins.2017.00647] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/07/2017] [Indexed: 12/22/2022] Open
Abstract
Neurodegenerative disorders are not only characterized by specific patterns of cell loss but the presence and accumulation of various pathological proteins—both of which correlate with disease evolution. There is now mounting evidence to suggest that these pathological proteins present with toxic, at times prion-like, properties and can therefore seed pathology in neighboring as well remotely connected healthy neurons as they spread across the brain. What is less clear, at this stage, is how much this actually contributes to, and drives, the core pathogenic events. In this review, we present a comprehensive, up-to-date summary of the reported in vitro studies that support the spreading and seeding capacities of pathological proteins, with an emphasis on mutant huntingtin protein in the context of Huntington's disease, although in vivo work remains to be performed to validate this theory in this particular disease. We have further reviewed these findings in light of their potential implications for the development of novel therapeutic approaches.
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Affiliation(s)
- Maria Masnata
- Axe Neurosciences, Centre de Recherche du CHU de Québec-Université Laval, Quebec, QC, Canada
| | - Francesca Cicchetti
- Axe Neurosciences, Centre de Recherche du CHU de Québec-Université Laval, Quebec, QC, Canada.,Département de Psychiatrie & Neurosciences, Université Laval, Quebec, QC, Canada
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17
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Ni Z, Gong Y, Dai X, Ding W, Wang B, Gong H, Qin L, Cheng P, Li S, Lian J, He F. AU4S: a novel synthetic peptide to measure the activity of ATG4 in living cells. Autophagy 2016; 11:403-15. [PMID: 25831015 DOI: 10.1080/15548627.2015.1009773] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
ATG4 plays a key role in autophagy induction, but the methods for monitoring ATG4 activity in living cells are limited. Here we designed a novel fluorescent peptide named AU4S for noninvasive detection of ATG4 activity in living cells, which consists of the cell-penetrating peptide (CPP), ATG4-recognized sequence "GTFG," and the fluorophore FITC. Additionally, an ATG4-resistant peptide AG4R was used as a control. CPP can help AU4S or AG4R to penetrate cell membrane efficiently. AU4S but not AG4R can be recognized and cleaved by ATG4, leading to the change of fluorescence intensity. Therefore, the difference between AU4S- and AG4R-measured fluorescence values in the same sample, defined as "F-D value," can reflect ATG4 activity. By detecting the F-D values, we found that ATG4 activity paralleled LC3B-II levels in rapamycin-treated cells, but neither paralleled LC3B-II levels in starved cells nor presented a correlation with LC3B-II accumulation in WBCs from healthy donors or leukemia patients. However, when DTT was added to the system, ATG4 activity not only paralleled LC3B-II levels in starved cells in the presence or absence of autophagy inhibitors, but also presented a positive correlation with LC3B-II accumulation in WBCs from leukemia patients (R(2) = 0.5288). In conclusion, this study provides a convenient, rapid, and quantitative method to monitor ATG4 activity in living cells, which may be beneficial to basic and clinical research on autophagy.
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Key Words
- 3-MA, 3-methyladenine
- AG4R, ATG4-resistant peptide
- ATG4
- ATG4, autophagy-related 4, cysteine peptidase
- AU4S
- AU4S, autophagy-related 4 substrate
- Ac, acetyl
- CFP, cyan fluorescent protein
- CPP, cell-penetrating peptide
- CQ, chloroquine
- DTT, dithiothreitol
- EBSS, Earle's balanced salt solution
- FITC, fluorescein isothiocyanate
- HIV, human immunodeficiency virus
- LC3
- MAP1LC3/LC3, microtubule-associated protein 1 light chain 3
- NAC, N-acetyl-L-cysteine
- NRK, normal rat kidney cell line
- PAGE, polyacrylamide gel electrophoresis
- PBS, phosphate-buffered saline
- PE, phosphatidylethanolamine
- PLA2, phospholipase A2
- PMSF, phenylmethanesulfonyl fluoride
- PtdIns3K, phosphatidylinositol 3-kinase
- ROS
- ROS, reactive oxygen species
- SDS, sodium dodecyl sulfate
- WBCs, white blood cells
- YFP, yellow fluorescent protein
- autophagy
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Affiliation(s)
- Zhenhong Ni
- a Department of Biochemistry and Molecular Biology; College of Basic Medical Sciences ; Third Military Medical University ; Chongqing , China
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18
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Biasiotto G, Di Lorenzo D, Archetti S, Zanella I. Iron and Neurodegeneration: Is Ferritinophagy the Link? Mol Neurobiol 2015; 53:5542-74. [PMID: 26468157 DOI: 10.1007/s12035-015-9473-y] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/01/2015] [Indexed: 12/12/2022]
Abstract
Mounting evidence indicates that the lysosome-autophagy pathway plays a critical role in iron release from ferritin, the main iron storage cellular protein, hence in the distribution of iron to the cells. The recent identification of nuclear receptor co-activator 4 as the receptor for ferritin delivery to selective autophagy sheds further light on the understanding of the mechanisms underlying this pathway. The emerging view is that iron release from ferritin through the lysosomes is a general mechanism in normal and tumour cells of different tissue origins, but it has not yet been investigated in brain cells. Defects in the lysosome-autophagy pathway are often involved in the pathogenesis of neurodegenerative disorders, and brain iron homeostasis disruption is a hallmark of many of these diseases. However, in most cases, it has not been established whether iron dysregulation is directly involved in the pathogenesis of the diseases or if it is a secondary effect derived from other pathogenic mechanisms. The recent evidence of the crucial involvement of autophagy in cellular iron handling offers new perspectives about the role of iron in neurodegeneration, suggesting that autophagy dysregulation could cause iron dyshomeostasis. In this review, we recapitulate our current knowledge on the routes through which iron is released from ferritin, focusing on the most recent advances. We summarise the current evidence concerning lysosome-autophagy pathway dysfunctions and those of iron metabolism and discuss their potential interconnections in several neurodegenerative disorders, such as Alzheimer's, Parkinson's and Huntington's diseases; amyotrophic lateral sclerosis; and frontotemporal lobar dementia.
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Affiliation(s)
- Giorgio Biasiotto
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy
- Biotechnology Laboratory, Department of Diagnostics, Civic Hospital of Brescia, Piazzale Spedali Civili 1, 25123, Brescia, Italy
| | - Diego Di Lorenzo
- Biotechnology Laboratory, Department of Diagnostics, Civic Hospital of Brescia, Piazzale Spedali Civili 1, 25123, Brescia, Italy
| | - Silvana Archetti
- Biotechnology Laboratory, Department of Diagnostics, Civic Hospital of Brescia, Piazzale Spedali Civili 1, 25123, Brescia, Italy
| | - Isabella Zanella
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
- Biotechnology Laboratory, Department of Diagnostics, Civic Hospital of Brescia, Piazzale Spedali Civili 1, 25123, Brescia, Italy.
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19
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Fernández ÁF, López-Otín C. The functional and pathologic relevance of autophagy proteases. J Clin Invest 2015; 125:33-41. [PMID: 25654548 DOI: 10.1172/jci73940] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Autophagy is a well-conserved catabolic process essential for cellular homeostasis. First described in yeast as an adaptive response to starvation, this pathway is also present in higher eukaryotes, where it is triggered by stress signals such as damaged organelles or pathogen infection. Autophagy is characterized at the cellular level by the engulfment of portions of the cytoplasm in double-membrane structures called autophagosomes. Autophagosomes fuse with lysosomes, resulting in degradation of the inner autophagosomal membrane and luminal content. This process is coordinated by complex molecular systems, including the ATG8 ubiquitin-like conjugation system and the ATG4 cysteine proteases, which are implicated in the formation, elongation, and fusion of these autophagic vesicles. In this Review, we focus on the diverse functional roles of the autophagins, a protease family formed by the four mammalian orthologs of yeast Atg4. We also address the dysfunctional expression of these proteases in several pathologic conditions such as cancer and inflammation and discuss potential therapies based on their modulation.
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20
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Rout AK, Strub MP, Piszczek G, Tjandra N. Structure of transmembrane domain of lysosome-associated membrane protein type 2a (LAMP-2A) reveals key features for substrate specificity in chaperone-mediated autophagy. J Biol Chem 2014; 289:35111-23. [PMID: 25342746 PMCID: PMC4271201 DOI: 10.1074/jbc.m114.609446] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/21/2014] [Indexed: 12/11/2022] Open
Abstract
Chaperone-mediated autophagy (CMA) is a highly regulated cellular process that mediates the degradation of a selective subset of cytosolic proteins in lysosomes. Increasing CMA activity is one way for a cell to respond to stress, and it leads to enhanced turnover of non-critical cytosolic proteins into sources of energy or clearance of unwanted or damaged proteins from the cytosol. The lysosome-associated membrane protein type 2a (LAMP-2A) together with a complex of chaperones and co-chaperones are key regulators of CMA. LAMP-2A is a transmembrane protein component for protein translocation to the lysosome. Here we present a study of the structure and dynamics of the transmembrane domain of human LAMP-2A in n-dodecylphosphocholine micelles by nuclear magnetic resonance (NMR). We showed that LAMP-2A exists as a homotrimer in which the membrane-spanning helices wrap around each other to form a parallel coiled coil conformation, whereas its cytosolic tail is flexible and exposed to the cytosol. This cytosolic tail of LAMP-2A interacts with chaperone Hsc70 and a CMA substrate RNase A with comparable affinity but not with Hsp40 and RNase S peptide. Because the substrates and the chaperone complex can bind at the same time, thus creating a bimodal interaction, we propose that substrate recognition by chaperones and targeting to the lysosomal membrane by LAMP-2A are coupled. This can increase substrate affinity and specificity as well as prevent substrate aggregation, assist in the unfolding of the substrate, and promote the formation of the higher order complex of LAMP-2A required for translocation.
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Affiliation(s)
| | | | - Grzegorz Piszczek
- Biophysics Core, Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
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21
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Selective VPS34 inhibitor blocks autophagy and uncovers a role for NCOA4 in ferritin degradation and iron homeostasis in vivo. Nat Cell Biol 2014; 16:1069-79. [PMID: 25327288 DOI: 10.1038/ncb3053] [Citation(s) in RCA: 489] [Impact Index Per Article: 48.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 09/16/2014] [Indexed: 12/17/2022]
Abstract
Cells rely on autophagy to clear misfolded proteins and damaged organelles to maintain cellular homeostasis. In this study we use the new autophagy inhibitor PIK-III to screen for autophagy substrates. PIK-III is a selective inhibitor of VPS34 that binds a unique hydrophobic pocket not present in related kinases such as PI(3)Kα. PIK-III acutely inhibits autophagy and de novo lipidation of LC3, and leads to the stabilization of autophagy substrates. By performing ubiquitin-affinity proteomics on PIK-III-treated cells we identified substrates including NCOA4, which accumulates in ATG7-deficient cells and co-localizes with autolysosomes. NCOA4 directly binds ferritin heavy chain-1 (FTH1) to target the iron-binding ferritin complex with a relative molecular mass of 450,000 to autolysosomes following starvation or iron depletion. Interestingly, Ncoa4(-/-) mice exhibit a profound accumulation of iron in splenic macrophages, which are critical for the reutilization of iron from engulfed red blood cells. Taken together, the results of this study provide a new mechanism for selective autophagy of ferritin and reveal a previously unappreciated role for autophagy and NCOA4 in the control of iron homeostasis in vivo.
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22
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Fan J, Dong X, Zhang W, Zeng X, Li Y, Sun Y, Wang S, Wang Z, Gao H, Zhao W, Ju D. Tyrosine kinase inhibitor Thiotanib targets Bcr-Abl and induces apoptosis and autophagy in human chronic myeloid leukemia cells. Appl Microbiol Biotechnol 2014; 98:9763-75. [PMID: 25200837 DOI: 10.1007/s00253-014-6003-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 07/28/2014] [Accepted: 07/30/2014] [Indexed: 11/25/2022]
Abstract
Chronic myeloid leukemia (CML) is characterized by abnormal Bcr and Abl genes and enhanced tyrosine kinase activity. Anti-CML therapy has been much improved along with the applications of tyrosine kinase inhibitors (TKIs) which selectively target Bcr-Abl and have a cytotoxic effect on CML. Recently, four-membered heterocycles as "compact modules" have attracted much interest in drug discovery. Grafting these small four-membered heterocycles onto a molecular scaffold could probably provide compounds that retain notable activity and populate chemical space otherwise not previously accessed. Accordingly, a novel TKI, Thiotanib, has been designed and synthesized. It selectively targets Bcr-Abl, inducing growth inhibition, cell cycle arrest, and apoptosis of CML cells. Meanwhile, the compound Thiotanib could also induce autophagy in CML cells. Interestingly, inhibition of autophagy promotes Thiotanib-induced apoptosis with no further activation of caspase 3, while inhibition of caspases did not affect the cell survival of CML cells. Moreover, the compound Thiotanib could inhibit phosphorylation of Akt and mTOR, increase beclin-1 and Vps34, and block the formation of the Bcl-2 and Beclin-1 complex. This indicates the probable pathway of autophagy initiation. Our results highlight a new approach for TKI reforming and further provide an indication of the efficacy enhancement of TKIs in combination with autophagy inhibitors.
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Affiliation(s)
- Jiajun Fan
- School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai, 201203, People's Republic of China
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23
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Transneuronal propagation of mutant huntingtin contributes to non-cell autonomous pathology in neurons. Nat Neurosci 2014; 17:1064-72. [PMID: 25017010 DOI: 10.1038/nn.3761] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 06/17/2014] [Indexed: 12/11/2022]
Abstract
In Huntington's disease (HD), whether transneuronal spreading of mutant huntingtin (mHTT) occurs and its contribution to non-cell autonomous damage in brain networks is largely unknown. We found mHTT spreading in three different neural network models: human neurons integrated in the neural network of organotypic brain slices of HD mouse model, an ex vivo corticostriatal slice model and the corticostriatal pathway in vivo. Transneuronal propagation of mHTT was blocked by two different botulinum neurotoxins, each known for specifically inactivating a single critical component of the synaptic vesicle fusion machinery. Moreover, healthy human neurons in HD mouse model brain slices displayed non-cell autonomous changes in morphological integrity that were more pronounced when these neurons bore mHTT aggregates. Altogether, our findings suggest that transneuronal propagation of mHTT might be an important and underestimated contributor to the pathophysiology of HD.
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Abstract
Autophagy is a conserved catabolic process that delivers the cytosol and cytosolic constituents to the lysosome. Its fundamental role is to maintain cellular homeostasis and to protect cells from varying insults, including misfolded proteins and damaged organelles. Beyond these roles, the highly specialized cells of the brain have further adapted autophagic pathways to suit their distinct needs. In this review, we briefly summarize our current understanding of the different forms of autophagy and then offer a closer look at how these pathways impact neuronal and glial functions. The emerging evidence indicates that not only are autophagy pathways essential for neural health, but they have a direct impact on developmental and neurodegenerative processes. Taken together, as we unravel the complex roles autophagy pathways play, we will gain the necessary insight to modify these pathways to protect the human brain and treat neurodegenerative diseases.
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Affiliation(s)
- Ai Yamamoto
- Departments of Neurology, Pathology, and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY 10032;
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25
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Baldo B, Soylu R, Petersén Å. Maintenance of basal levels of autophagy in Huntington's disease mouse models displaying metabolic dysfunction. PLoS One 2013; 8:e83050. [PMID: 24376631 PMCID: PMC3869748 DOI: 10.1371/journal.pone.0083050] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 11/07/2013] [Indexed: 11/24/2022] Open
Abstract
Huntington's disease (HD) is a fatal neurodegenerative disorder caused by an expanded polyglutamine repeat in the huntingtin protein. Neuropathology in the basal ganglia and in the cerebral cortex has been linked to the motor and cognitive symptoms whereas recent work has suggested that the hypothalamus might be involved in the metabolic dysfunction. Several mouse models of HD that display metabolic dysfunction have hypothalamic pathology, and expression of mutant huntingtin in the hypothalamus has been causally linked to the development of metabolic dysfunction in mice. Although the pathogenic mechanisms by which mutant huntingtin exerts its toxic functions in the HD brain are not fully known, several studies have implicated a role for the lysososomal degradation pathway of autophagy. Interestingly, changes in autophagy in the hypothalamus have been associated with the development of metabolic dysfunction in wild-type mice. We hypothesized that expression of mutant huntingtin might lead to changes in the autophagy pathway in the hypothalamus in mice with metabolic dysfunction. We therefore investigated whether there were changes in basal levels of autophagy in a mouse model expressing a fragment of 853 amino acids of mutant huntingtin selectively in the hypothalamus using a recombinant adeno-associate viral vector approach as well as in the transgenic BACHD mice. We performed qRT-PCR and Western blot to investigate the mRNA and protein expression levels of selected autophagy markers. Our results show that basal levels of autophagy are maintained in the hypothalamus despite the presence of metabolic dysfunction in both mouse models. Furthermore, although there were no major changes in autophagy in the striatum and cortex of BACHD mice, we detected modest, but significant differences in levels of some markers in mice at 12 months of age. Taken together, our results indicate that overexpression of mutant huntingtin in mice do not significantly perturb basal levels of autophagy.
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Affiliation(s)
- Barbara Baldo
- Translational Neuroendocrine Research Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Rana Soylu
- Translational Neuroendocrine Research Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Åsa Petersén
- Translational Neuroendocrine Research Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
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