101
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Suda K, Kaneko A, Shimobayashi M, Nakashima A, Maeda T, Hall MN, Ushimaru T. TORC1 regulates autophagy induction in response to proteotoxic stress in yeast and human cells. Biochem Biophys Res Commun 2019; 511:434-439. [PMID: 30797551 DOI: 10.1016/j.bbrc.2019.02.077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 02/15/2019] [Indexed: 11/18/2022]
Abstract
Misfolded and aggregated proteins are eliminated to maintain protein homeostasis. Autophagy contributes to the removal of protein aggregates. However, if and how proteotoxic stress induces autophagy is poorly understood. Here we show that proteotoxic stress after treatment with azetidine-2-carboxylic acid (AZC), a toxic proline analog, induces autophagy in budding yeast. AZC treatment attenuated target of rapamycin complex 1 (TORC1) activity, resulting in the dephosphorylation of Atg13, a key factor of autophagy. By contrast, AZC treatment did not affect target of rapamycin complex 2 (TORC2). Proteotoxic stress also induced TORC1 inactivation and autophagy in fission yeast and human cells. This study suggested that TORC1 is a conserved key factor to cope with proteotoxic stress in eukaryotic cells.
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Affiliation(s)
- Kazuki Suda
- Department of Biological Science, Shizuoka University, Shizuoka, 422-8021, Japan
| | - Atsuki Kaneko
- Course of Biological Science, Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, 422-8021, Japan
| | | | - Akio Nakashima
- Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan
| | - Tatsuya Maeda
- Department of Biology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, 431-3192, Japan
| | - Michael N Hall
- Biozentrum, University of Basel, 4056, Basel, Switzerland, Switzerland
| | - Takashi Ushimaru
- Department of Biological Science, Shizuoka University, Shizuoka, 422-8021, Japan; Course of Biological Science, Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, 422-8021, Japan.
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102
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Scrivo A, Codogno P, Bomont P. Gigaxonin E3 ligase governs ATG16L1 turnover to control autophagosome production. Nat Commun 2019; 10:780. [PMID: 30770803 PMCID: PMC6377711 DOI: 10.1038/s41467-019-08331-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 12/21/2018] [Indexed: 12/12/2022] Open
Abstract
Autophagy is an essential self-digestion machinery for cell survival and homoeostasis. Membrane elongation is fundamental, as it drives the formation of the double-membrane vesicles that engulf cytosolic material. LC3-lipidation, the signature of autophagosome formation, results from a complex ubiquitin-conjugating cascade orchestrated by the ATG16L1 protein, whose regulation is unknown. Here, we identify the Gigaxonin-E3 ligase as the first regulator of ATG16L1 turn-over and autophagosome production. Gigaxonin interacts with the WD40 domain of ATG16L1 to drive its ubiquitination and subsequent degradation. Gigaxonin depletion induces the formation of ATG16L1 aggregates and impairs LC3 lipidation, hence altering lysosomal fusion and degradation of the main autophagy receptor p62. Altogether, we demonstrate that the Gigaxonin-E3 ligase controls the production of autophagosomes by a reversible, ubiquitin-dependent process selective for ATG16L1. Our findings unveil the fundamental mechanisms of the control of autophagosome formation, and provide a molecular switch to fine-tune the activation of autophagy. Membrane elongation is fundamental to autophagy and is controlled by an ubiquitin-conjugating cascade orchestrated by ATG16L1. Here, the authors identify that the E3 ligase Gigaxonin regulates autophagosome formation by controlling ATG16L1 turnover.
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Affiliation(s)
- Aurora Scrivo
- Avenir-Atip team, INM, INSERM, Université Montpellier, 34091, Montpellier, France.,Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 10461, New York, NY, USA
| | - Patrice Codogno
- Institut Necker-Enfants Malades (INEM), INSERM U1151-CNRS UMR8253, 75993, Paris, France.,Université Paris Descartes-Sorbonne Paris Cité, 75006, Paris, France
| | - Pascale Bomont
- Avenir-Atip team, INM, INSERM, Université Montpellier, 34091, Montpellier, France.
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103
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Gustafsson ÅB, Dorn GW. Evolving and Expanding the Roles of Mitophagy as a Homeostatic and Pathogenic Process. Physiol Rev 2019; 99:853-892. [PMID: 30540226 PMCID: PMC6442924 DOI: 10.1152/physrev.00005.2018] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 08/10/2018] [Accepted: 09/29/2018] [Indexed: 02/07/2023] Open
Abstract
The central functions fulfilled by mitochondria as both energy generators essential for tissue homeostasis and gateways to programmed apoptotic and necrotic cell death mandate tight control over the quality and quantity of these ubiquitous endosymbiotic organelles. Mitophagy, the targeted engulfment and destruction of mitochondria by the cellular autophagy apparatus, has conventionally been considered as the mechanism primarily responsible for mitochondrial quality control. However, our understanding of how, why, and under what specific conditions mitophagy is activated has grown tremendously over the past decade. Evidence is accumulating that nonmitophagic mitochondrial quality control mechanisms are more important to maintaining normal tissue homeostasis whereas mitophagy is an acute tissue stress response. Moreover, previously unrecognized mitophagic regulation of mitochondrial quantity control, metabolic reprogramming, and cell differentiation suggests that the mechanisms linking genetic or acquired defects in mitophagy to neurodegenerative and cardiovascular diseases or cancer are more complex than simple failure of normal mitochondrial quality control. Here, we provide a comprehensive overview of mitophagy in cellular homeostasis and disease and examine the most revolutionary concepts in these areas. In this context, we discuss evidence that atypical mitophagy and nonmitophagic pathways play central roles in mitochondrial quality control, functioning that was previously considered to be the primary domain of mitophagy.
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Affiliation(s)
- Åsa B Gustafsson
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego , La Jolla, California ; and Washington University School of Medicine, St. Louis, Missouri
| | - Gerald W Dorn
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego , La Jolla, California ; and Washington University School of Medicine, St. Louis, Missouri
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104
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Seranova E, Ward C, Chipara M, Rosenstock TR, Sarkar S. In Vitro Screening Platforms for Identifying Autophagy Modulators in Mammalian Cells. Methods Mol Biol 2019; 1880:389-428. [PMID: 30610712 DOI: 10.1007/978-1-4939-8873-0_26] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Autophagy is a vital homeostatic pathway essential for cellular survival and human health. It primarily functions as an intracellular degradation process for the turnover of aggregation-prone proteins and unwanted organelles. Dysregulation of autophagy underlying diverse human diseases reduces cell viability, whereas stimulation of autophagy is cytoprotective in a number of transgenic disease models including neurodegenerative disorders. Thus, therapeutic exploitation of autophagy is considered a potential treatment strategy in certain human diseases, and therefore, chemical inducers of autophagy have tremendous biomedical relevance. In this review, we describe the in vitro screening platforms to identify autophagy modulators in mammalian cells using various methodologies including fluorescence and high-content imaging, flow cytometry, fluorescence and luminescence detection by microplate reader, immunoblotting, and immunofluorescence. The commonly used autophagy reporters in these screening platforms are either based on autophagy marker like LC3 or autophagy substrate such as aggregation-prone proteins or p62/SQSTM1. The reporters and assays for monitoring autophagy are evolving over time to become more sensitive in measuring autophagic flux with the capability of high-throughput applications for drug discovery. Here we highlight these developments and also describe the stringent secondary autophagy assays for characterizing the autophagy modulators arising from the primary screen. Since autophagy is implicated in myriad human physiological and pathological conditions, these technologies will enable identifying novel chemical modulators or genetic regulators of autophagy that will be of biomedical and fundamental importance to human health.
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Affiliation(s)
- Elena Seranova
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Carl Ward
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Miruna Chipara
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Tatiana R Rosenstock
- Department of Physiological Science, Santa Casa de São Paulo School of Medical Science, São Paulo, Brazil
| | - Sovan Sarkar
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
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105
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Delorme-Axford E, Klionsky DJ. On the edge of degradation: Autophagy regulation by RNA decay. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 10:e1522. [PMID: 30560575 DOI: 10.1002/wrna.1522] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 11/21/2018] [Accepted: 11/27/2018] [Indexed: 12/21/2022]
Abstract
Cells must dynamically adapt to altered environmental conditions, particularly during times of stress, to ensure their ability to function effectively and survive. The macroautophagy/autophagy pathway is highly conserved across eukaryotic cells and promotes cell survival during stressful conditions. In general, basal autophagy occurs at a low level to sustain cellular homeostasis and metabolism. However, autophagy is robustly upregulated in response to nutrient deprivation, pathogen infection and increased accumulation of potentially toxic protein aggregates and superfluous organelles. Within the cell, RNA decay maintains quality control to remove aberrant transcripts and regulate appropriate levels of gene expression. Recent evidence has identified components of the cellular mRNA decay machinery as novel regulators of autophagy. Here, we review current findings that demonstrate how autophagy is modulated through RNA decay. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Turnover and Surveillance > Regulation of RNA Stability.
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Affiliation(s)
| | - Daniel J Klionsky
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan
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106
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Autophagy and Its Role in Protein Secretion: Implications for Cancer Therapy. Mediators Inflamm 2018; 2018:4231591. [PMID: 30622432 PMCID: PMC6304875 DOI: 10.1155/2018/4231591] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 09/26/2018] [Accepted: 10/02/2018] [Indexed: 12/11/2022] Open
Abstract
Autophagy is a protein and organelle degradation pathway important for the maintenance of cytoplasmic homeostasis and for providing nutrients for survival in response to stress conditions. Recently, autophagy has been shown to be important for the secretion of diverse proteins involved in inflammation, intercellular signaling, and cancer progression. The role of autophagy in cancer depends on the stage of tumorigenesis, serving a tumor-suppressor role before transformation and a tumor-survival function once a tumor is established. We review recent evidence demonstrating the complexity of autophagy regulation during cancer, considering the interaction of autophagy with protein secretion pathways. Autophagy manipulation during cancer treatment is likely to affect protein secretion andinter-cellular signaling either to the neighboring cancer cells or to the antitumoral immune response. This will be an important consideration during cancer therapy since several clinical trials are trying to manipulate autophagy in combination with chemotherapy for the treatment of diverse types of cancers.
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107
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Cao Y, Luo Y, Zou J, Ouyang J, Cai Z, Zeng X, Ling H, Zeng T. Autophagy and its role in gastric cancer. Clin Chim Acta 2018; 489:10-20. [PMID: 30472237 DOI: 10.1016/j.cca.2018.11.028] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/17/2018] [Accepted: 11/20/2018] [Indexed: 02/08/2023]
Abstract
Autophagy, which is tightly regulated by a series of autophagy-related genes (ATGs), is a vital intracellular homeostatic process through which defective proteins and organelles are degraded and recycled under starvation, hypoxia or other specific cellular stress conditions. For both normal cells and tumour cells, autophagy not only sustains cell survival but can also promote cell death. Autophagy-related signalling pathways include mTOR-dependent pathways, such as the AMPK/mTOR and PI3K/Akt/mTOR pathways, and non-mTOR dependent pathways, such as the P53 pathway. Additionally, autophagy plays a dual role in gastric carcinoma (GC), including a tumour-suppressor role and a tumour-promoter role. Long-term Helicobacter pylori infection can impair autophagy, which may eventually promote tumourigenesis of the gastric mucosa. Moreover, Beclin1, LC3 and P62/SQSTM1 are regarded as autophagy-related markers with GC prognostic value. Autophagy inhibitors and autophagy inducers show promise for GC treatment. This review describes research progress regarding autophagy and its significant role in gastric cancer.
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Affiliation(s)
- Yijing Cao
- Key Laboratory of Tumor Cellular & Molecular Pathology (University of South China), College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, PR China; Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study [Hunan Provincial Education Department document (Approval number: 2014-405)], Hengyang, Hunan 421001, PR China
| | - Yichen Luo
- Key Laboratory of Tumor Cellular & Molecular Pathology (University of South China), College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, PR China; Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study [Hunan Provincial Education Department document (Approval number: 2014-405)], Hengyang, Hunan 421001, PR China
| | - Juan Zou
- Key Laboratory of Tumor Cellular & Molecular Pathology (University of South China), College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, PR China; Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study [Hunan Provincial Education Department document (Approval number: 2014-405)], Hengyang, Hunan 421001, PR China
| | - Jun Ouyang
- Department of Gastrointestinal Surgery, the First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, PR China
| | - Zhihong Cai
- Key Laboratory of Tumor Cellular & Molecular Pathology (University of South China), College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, PR China; Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study [Hunan Provincial Education Department document (Approval number: 2014-405)], Hengyang, Hunan 421001, PR China
| | - Xi Zeng
- Key Laboratory of Tumor Cellular & Molecular Pathology (University of South China), College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, PR China; Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study [Hunan Provincial Education Department document (Approval number: 2014-405)], Hengyang, Hunan 421001, PR China
| | - Hui Ling
- Key Laboratory of Tumor Cellular & Molecular Pathology (University of South China), College of Hunan Province, Cancer Research Institute, University of South China, Hengyang, Hunan 421001, PR China; Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study [Hunan Provincial Education Department document (Approval number: 2014-405)], Hengyang, Hunan 421001, PR China.
| | - Tiebing Zeng
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study [Hunan Provincial Education Department document (Approval number: 2014-405)], Hengyang, Hunan 421001, PR China; Institute of Pathogenic Biology, Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, University of South China, Hengyang, Hunan 421001, PR China.
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108
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Grasso D, Renna FJ, Vaccaro MI. Initial Steps in Mammalian Autophagosome Biogenesis. Front Cell Dev Biol 2018; 6:146. [PMID: 30406104 PMCID: PMC6206277 DOI: 10.3389/fcell.2018.00146] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/08/2018] [Indexed: 12/11/2022] Open
Abstract
During the last decade, autophagy has been pointed out as a central process in cellular homeostasis with the consequent implication in most cellular settings and human diseases pathology. At present, there is significant data available about molecular mechanisms that regulate autophagy. Nevertheless, autophagy pathway itself and its importance in different cellular aspects are still not completely clear. In this article, we are focused in four main aspects: (a) Induction of Autophagy: Autophagy is an evolutionarily conserved mechanism induced by nutrient starvation or lack of growth factors. In higher eukaryotes, autophagy is a cell response to stress which starts as a consequence of organelle damage, such as oxidative species and other stress conditions. (b) Initiation of Autophagy; The two major actors in this signaling process are mTOR and AMPK. These multitasking protein complexes are capable to summarize the whole environmental, nutritional, and energetic status of the cell and promote the autophagy induction by means of the ULK1-Complex, that is the first member in the autophagy initiation. (c) ULK1-Complex: This is a highly regulated complex responsible for the initiation of autophagosome formation. We review the post-transductional modifications of this complex, considering the targets of ULK1. (d)The mechanisms involved in autophagosome formation. In this section we discuss the main events that lead to the initial structures in autophagy. The BECN1-Complex with PI3K activity and the proper recognition of PI3P are one of these. Also, the transmembrane proteins, such as VMP1 and ATG9, are critically involved. The membrane origin and the cellular localization of autophagosome biogenesis will be also considered. Hence, in this article we present an overview of the current knowledge of the molecular mechanisms involved in the initial steps of mammalian cell autophagosome biogenesis.
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Affiliation(s)
- Daniel Grasso
- Institute of Biochemistry and Molecular Medicine (IBIMOL-CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina
| | - Felipe Javier Renna
- Institute of Biochemistry and Molecular Medicine (IBIMOL-CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina
| | - Maria Ines Vaccaro
- Institute of Biochemistry and Molecular Medicine (IBIMOL-CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina
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109
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Keown JR, Black MM, Ferron A, Yap M, Barnett MJ, Pearce FG, Stoye JP, Goldstone DC. A helical LC3-interacting region mediates the interaction between the retroviral restriction factor Trim5α and mammalian autophagy-related ATG8 proteins. J Biol Chem 2018; 293:18378-18386. [PMID: 30282803 PMCID: PMC6254359 DOI: 10.1074/jbc.ra118.004202] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 09/10/2018] [Indexed: 11/28/2022] Open
Abstract
The retroviral restriction factor tripartite motif–containing 5α (Trim5α) acts during the early postentry stages of the retroviral life cycle to block infection by a broad range of retroviruses, disrupting reverse transcription and integration. The mechanism of this restriction is poorly understood, but it has recently been suggested to involve recruitment of components of the autophagy machinery, including members of the mammalian autophagy-related 8 (ATG8) family involved in targeting proteins to the autophagosome. To better understand the molecular details of this interaction, here we utilized analytical ultracentrifugation to characterize the binding of six ATG8 isoforms and determined the crystal structure of the Trim5α Bbox coiled-coil region in complex with one member of the mammalian ATG8 proteins, autophagy-related protein LC3 B (LC3B). We found that Trim5α binds all mammalian ATG8s and that, unlike the typical LC3-interacting region (LIR) that binds to mammalian ATG8s through a β-strand motif comprising approximately six residues, LC3B binds to Trim5α via the α-helical coiled-coil region. The orientation of the structure demonstrated that LC3B could be accommodated within a Trim5α assembly that can bind the retroviral capsid. However, mutation of the binding interface does not affect retroviral restriction. Comparison of the typical linear β-strand LIR with our atypical helical LIR reveals a conservation of the presentation of residues that are required for the interaction with LC3B. This observation expands the range of LC3B-binding proteins to include helical binding motifs and demonstrates a link between Trim5α and components of the autophagosome.
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Affiliation(s)
- Jeremy R Keown
- From the School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
| | - Moyra M Black
- From the School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
| | - Aaron Ferron
- the Francis Crick Institute, London NW1 1ST, United Kingdom
| | - Melvyn Yap
- the Francis Crick Institute, London NW1 1ST, United Kingdom
| | - Michael J Barnett
- From the School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
| | - F Grant Pearce
- the School of Biological Sciences, University of Canterbury, Christchurch 8041, New Zealand, and
| | | | - David C Goldstone
- From the School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand,; the Maurice Wilkins Centre for Molecular Biodiscovery, Auckland 1010, New Zealand.
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110
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Ogmundsdottir MH, Fock V, Sooman L, Pogenberg V, Dilshat R, Bindesbøll C, Ogmundsdottir HM, Simonsen A, Wilmanns M, Steingrimsson E. A short isoform of ATG7 fails to lipidate LC3/GABARAP. Sci Rep 2018; 8:14391. [PMID: 30258106 PMCID: PMC6158294 DOI: 10.1038/s41598-018-32694-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 09/10/2018] [Indexed: 12/13/2022] Open
Abstract
Autophagy is a degradation pathway important for cellular homeostasis. The E1-like enzyme ATG7 is a key component of the autophagy machinery, with the main function of mediating the lipidation of LC3/GABARAP during autophagosome formation. By analysing mRNA-sequencing data we found that in addition to the full-length ATG7 isoform, various tissues express a shorter isoform lacking an exon of 27 amino acids in the C-terminal part of the protein, termed ATG7(2). We further show that ATG7(2) does not bind LC3B and fails to mediate the lipidation of members of the LC3/GABARAP family. We have thus identified an isoform of ATG7 that is unable to carry out the best characterized function of the protein during the autophagic response. This short isoform will have to be taken into consideration when further studying the role of ATG7.
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Affiliation(s)
- M H Ogmundsdottir
- Department of Biochemistry and Molecular Biology, Biomedical Center, Faculty of Medicine, University of Iceland, Sturlugata 8, 101, Reykjavik, Iceland.
| | - V Fock
- Department of Biochemistry and Molecular Biology, Biomedical Center, Faculty of Medicine, University of Iceland, Sturlugata 8, 101, Reykjavik, Iceland
| | - L Sooman
- Department of Biochemistry and Molecular Biology, Biomedical Center, Faculty of Medicine, University of Iceland, Sturlugata 8, 101, Reykjavik, Iceland
| | - V Pogenberg
- European Molecular Biology Laboratory, Hamburg Unit, Notkestrasse 85, 22607, Hamburg, Germany
| | - R Dilshat
- Department of Biochemistry and Molecular Biology, Biomedical Center, Faculty of Medicine, University of Iceland, Sturlugata 8, 101, Reykjavik, Iceland
| | - C Bindesbøll
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Sognsvannsveien 9, N-0317, Oslo, Norway
| | - H M Ogmundsdottir
- Cancer Research Laboratory, Biomedical Center, Faculty of Medicine, University of Iceland, Sturlugata 8, 101, Reykjavik, Iceland
| | - A Simonsen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Sognsvannsveien 9, N-0317, Oslo, Norway
| | - M Wilmanns
- European Molecular Biology Laboratory, Hamburg Unit, Notkestrasse 85, 22607, Hamburg, Germany
| | - E Steingrimsson
- Department of Biochemistry and Molecular Biology, Biomedical Center, Faculty of Medicine, University of Iceland, Sturlugata 8, 101, Reykjavik, Iceland.
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111
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Abstract
Peroxisomes are ubiquitous and highly dynamic organelles that play a central role in the metabolism of lipids and reactive oxygen species. The importance of peroxisomal metabolism is illustrated by severe peroxisome biogenesis disorders in which functional peroxisomes are absent or disorders caused by single peroxisomal enzyme deficiencies. These multisystemic diseases manifest specific clinical and biochemical disturbances that originate from the affected peroxisomal pathways. An emerging role of the peroxisome has been identified in many types of diseases, including cancer, neurodegenerative disorders, aging, obesity, and diabetes. Peroxisome homeostasis is achieved via a tightly regulated interplay between peroxisome biogenesis and degradation via selective autophagy, which is commonly known as "pexophagy". Dysregulation of either peroxisome biogenesis or pexophagy may be detrimental to the health of cells and contribute to the pathophysiology of these diseases. Autophagy is an evolutionary conserved catabolic process for non-selective degradation of macromolecules and organelles in response to various stressors. In selective autophagy, specific cargo-recognizing receptors connect the cargo to the core autophagic machinery, and additional posttranslational modifications such as ubiquitination and phosphorylation regulate this process. Several stress conditions have been shown to stimulate pexophagy and decrease peroxisome abundance. However, our understanding of the mechanisms that particularly regulate mammalian pexophagy has been limited. In recent years considerable progress has been made uncovering signaling pathways, autophagy receptors and adaptors as well as posttranslational modifications involved in pexophagy. In this review, which is published back-to-back with a peroxisome review by Islinger et al. [(Histochem Cell Biol 137:547-574, 2018). The peroxisome: an update on mysteries 2.0], we focus on recent novel findings on the underlying molecular mechanisms of pexophagy in yeast and mammalian cells and highlight concerns and gaps in our knowledge.
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112
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Werner A, Herzog B, Voigt O, Valerius O, Braus GH, Pöggeler S. NBR1 is involved in selective pexophagy in filamentous ascomycetes and can be functionally replaced by a tagged version of its human homolog. Autophagy 2018; 15:78-97. [PMID: 30081713 DOI: 10.1080/15548627.2018.1507440] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Macroautophagy/autophagy is a conserved degradation process in eukaryotic cells involving the sequestration of proteins and organelles within double-membrane vesicles termed autophagosomes. In filamentous fungi, its main purposes are the regulation of starvation adaptation and developmental processes. In contrast to nonselective bulk autophagy, selective autophagy is characterized by cargo receptors, which bind specific cargos such as superfluous organelles, damaged or harmful proteins, or microbes, and target them for autophagic degradation. Herein, using the core autophagy protein ATG8 as bait, GFP-Trap analysis followed by liquid chromatography mass spectrometry (LC/MS) identified a putative homolog of the human autophagy cargo receptor NBR1 (NBR1, autophagy cargo receptor) in the filamentous ascomycete Sordaria macrospora (Sm). Fluorescence microscopy revealed that SmNBR1 colocalizes with SmATG8 at autophagosome-like structures and in the lumen of vacuoles. Delivery of SmNBR1 to the vacuoles requires SmATG8. Both proteins interact in an LC3 interacting region (LIR)-dependent manner. Deletion of Smnbr1 leads to impaired vegetative growth under starvation conditions and reduced sexual spore production under non-starvation conditions. The human NBR1 homolog partially rescues the phenotypic defects of the fungal Smnbr1 deletion mutant. The Smnbr1 mutant can neither use fatty acids as a sole carbon source nor form fruiting bodies under oxidative stress conditions. Fluorescence microscopy revealed that degradation of a peroxisomal reporter protein is impaired in the Smnbr1 deletion mutant. Thus, SmNBR1 is a cargo receptor for pexophagy in filamentous ascomycetes.
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Affiliation(s)
- Antonia Werner
- a Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany
| | - Britta Herzog
- a Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany
| | - Oliver Voigt
- a Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany
| | - Oliver Valerius
- b Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany
| | - Gerhard H Braus
- b Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany.,c Göttingen Center for Molecular Biosciences (GZMB) , University of Göttingen , Göttingen , Germany
| | - Stefanie Pöggeler
- a Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany.,c Göttingen Center for Molecular Biosciences (GZMB) , University of Göttingen , Göttingen , Germany
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113
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Kim BW, Jin Y, Kim J, Kim JH, Jung J, Kang S, Kim IY, Kim J, Cheong H, Song HK. The C-terminal region of ATG101 bridges ULK1 and PtdIns3K complex in autophagy initiation. Autophagy 2018; 14:2104-2116. [PMID: 30081750 PMCID: PMC6984762 DOI: 10.1080/15548627.2018.1504716] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 07/20/2018] [Accepted: 07/23/2018] [Indexed: 01/07/2023] Open
Abstract
The initiation of macroautophagy/autophagy is tightly regulated by the upstream ULK1 kinase complex, which affects many downstream factors including the PtdIns3K complex. The phosphorylation of the right position at the right time on downstream molecules is governed by proper complex formation. One component of the ULK1 complex, ATG101, known as an accessory protein, is a stabilizer of ATG13 in cells. The WF finger region of ATG101 plays an important role in the recruitment of WIPI1 (WD repeat domain, phosphoinositide interacting protein 1) and ZFYVE1 (zinc finger FYVE-type containing 1). Here, we report that the C-terminal region identified in the structure of the human ATG101-ATG13HORMA complex is responsible for the binding of the PtdIns3K complex. This region adopts a β-strand conformation in free ATG101, but either an α-helix or random coil in our ATG101-ATG13HORMA complex, which protrudes from the core and interacts with other molecules. The C-terminal deletion of ATG101 shows a significant defect in the interaction with PtdIns3K components and subsequently impairs autophagosome formation. This result clearly presents an additional role of ATG101 for bridging the ULK1 and PtdIns3K complexes in the mammalian autophagy process. Abbreviations: ATG: autophagy related; BECN1: beclin 1; GFP: green fluorescent protein; HORMA: Hop1p/Rev7p/MAD2; HsATG13HORMA: HORMA domain of ATG13 from Homo sapiens; KO: knockout; MAD2: mitotic arrest deficient 2 like 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PIK3R4/VPS15: phosphoinositide-3-kinase regulatory subunit 4; PtdIns3K: phosphatidylinositol 3-kinase; RB1CC1/FIP200: RB1 inducible coiled-coil 1; SAXS: small-angle X-ray scattering; ScAtg13HORMA: HORMA domain of Atg13 from Sccharomyces cerevisiae; SEC-SAXS: size-exclusion chromatography with small-angle X-ray scattering; SpAtg13HORMA: HORMA domain of Atg13 from Schizosaccharomyces pombe; SQSTM1/p62: sequestosome 1; ULK1: unc51-like autophagy activating kinase 1; UVRAG: UV radiation resistance associated; WIPI1: WD repeat domain: phosphoinositide interacting 1; ZFYVE1/DFCP1: zinc finger FYVE-type containing 1.
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Affiliation(s)
- Byeong-Won Kim
- Department of Life Sciences, Korea University, Seongbuk-gu, Seoul, Republic of Korea
| | - Yunjung Jin
- Department of Life Sciences, Korea University, Seongbuk-gu, Seoul, Republic of Korea
| | - Jiyea Kim
- Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy, Seongbuk-gu, Seoul, Republic of Korea
- Tumor Microenvironment Branch, Research Institute, National Cancer Center, Goyang, Republic of Korea
| | - Jun Hoe Kim
- Department of Life Sciences, Korea University, Seongbuk-gu, Seoul, Republic of Korea
| | - Juneyoung Jung
- Department of Life and Nanopharmaceutical Sciences, Graduate School, Seongbuk-gu, Seoul, Republic of Korea
| | - Seongman Kang
- Department of Life Sciences, Korea University, Seongbuk-gu, Seoul, Republic of Korea
| | - Ick Young Kim
- Department of Life Sciences, Korea University, Seongbuk-gu, Seoul, Republic of Korea
| | - Joungmok Kim
- Department of Oral Biochemistry and Molecular BiologySchool of Dentistry, Kyung Hee University, Seoul, Republic of Korea
| | - Heesun Cheong
- Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy, Seongbuk-gu, Seoul, Republic of Korea
- Tumor Microenvironment Branch, Research Institute, National Cancer Center, Goyang, Republic of Korea
| | - Hyun Kyu Song
- Department of Life Sciences, Korea University, Seongbuk-gu, Seoul, Republic of Korea
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114
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Ubiquitin, SUMO, and NEDD8: Key Targets of Bacterial Pathogens. Trends Cell Biol 2018; 28:926-940. [PMID: 30107971 DOI: 10.1016/j.tcb.2018.07.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 07/13/2018] [Accepted: 07/17/2018] [Indexed: 01/09/2023]
Abstract
Manipulation of host protein post-translational modifications (PTMs) is used by various pathogens to interfere with host cell functions. Among these modifications, ubiquitin (UBI) and ubiquitin-like proteins (UBLs) constitute key targets because they are regulators of pathways essential for the host cell. In particular, these PTM modifiers control pathways that have been described as crucial for infection such as pathogen entry, replication, propagation, or detection by the host. Although bacterial pathogens lack eucaryotic-like UBI or UBL systems, many of them produce proteins that specifically interfere with these host PTMs during infection. In this review we discuss the different mechanisms used by bacteria to interfere with host UBI and the two UBLs, SUMO and NEDD8.
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115
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Fontana R, Vivo M. Dynamics of p14ARF and Focal Adhesion Kinase-Mediated Autophagy in Cancer. Cancers (Basel) 2018; 10:cancers10070221. [PMID: 29966311 PMCID: PMC6071150 DOI: 10.3390/cancers10070221] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 06/22/2018] [Accepted: 06/26/2018] [Indexed: 12/23/2022] Open
Abstract
It has been widely shown that the focal adhesion kinase (FAK) is involved in nearly every aspect of cancer, from invasion to metastasis to epithelial–mesenchymal transition and maintenance of cancer stem cells. FAK has been shown to interact with p14ARF (alternative reading frame)—a well-established tumor suppressor—and functions in the negative regulation of cancer through both p53-dependent and -independent pathways. Interestingly, both FAK and ARF (human and mouse counterpart) proteins, as well as p53, are involved in autophagy—a process of “self-digestion”—whose main function is the recycling of cellular components and quality control of proteins and organelles. In the last years, an unexpected role of p14ARF in the survival of cancer cells has been underlined in different cellular contexts, suggesting a novel pro-oncogenic function of this protein. In this review, the mechanisms whereby ARF and FAK control autophagy are presented, as well as the role of autophagy in cell migration and spreading. Integrated investigation of these cell functions is extremely important to understand the mechanism of the basis of cell transformation and migration and thus cancer development.
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Affiliation(s)
- Rosa Fontana
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy.
| | - Maria Vivo
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy.
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116
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Kim L, Kwon DH, Kim BH, Kim J, Park MR, Park ZY, Song HK. Structural and Biochemical Study of the Mono-ADP-Ribosyltransferase Domain of SdeA, a Ubiquitylating/Deubiquitylating Enzyme from Legionella pneumophila. J Mol Biol 2018; 430:2843-2856. [PMID: 29870726 DOI: 10.1016/j.jmb.2018.05.043] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 05/24/2018] [Accepted: 05/27/2018] [Indexed: 11/18/2022]
Abstract
Conventional ubiquitylation occurs through an ATP-dependent three-enzyme cascade (E1, E2, and E3) that mediates the covalent conjugation of the C-terminus of ubiquitin to a lysine on the substrate. SdeA, which belongs to the SidE effector family of Legionella pneumophila, can transfer ubiquitin to endoplasmic reticulum-associated Rab-family GTPases in a manner independent of E1 and E2 enzymes. The novel ubiquitin-modifying enzyme SdeA utilizes NAD+ as a cofactor to attach ubiquitin to a serine residue of the substrate. Here, to elucidate the coupled enzymatic reaction of NAD+ hydrolysis and ADP-ribosylation of ubiquitin in SdeA, we characterized the mono-ADP-ribosyltransferase domain of SdeA and show that it consists of two sub-domains termed mART-N and mART-C. The crystal structure of the mART-C domain of SdeA was also determined in free form and in complex with NAD+ at high resolution. Furthermore, the spatial orientations of the N-terminal deubiquitylase, phosphodiesterase, mono-ADP-ribosyltransferase, and C-terminal coiled-coil domains within the 180-kDa full-length SdeA were determined. These results provide insight into the unusual ubiquitylation mechanism of SdeA and expand our knowledge on the structure-function of mono-ADP-ribosyltransferases.
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Affiliation(s)
- Leehyeon Kim
- Department of Life Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea
| | - Do Hoon Kwon
- Department of Life Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea
| | - Bong Heon Kim
- Department of Life Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea
| | - Jiyeon Kim
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - Mi Rae Park
- Department of Life Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea
| | - Zee-Yong Park
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - Hyun Kyu Song
- Department of Life Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea.
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117
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Thongrod S, Wanichanon C, Kankuan W, Siangcham T, Phadngam S, Morani F, Isidoro C, Sobhon P. Autophagy-Associated Shrinkage of the Hepatopancreas in Fasting Male Macrobrachium rosenbergii Is Rescued by Neuropeptide F. Front Physiol 2018; 9:613. [PMID: 29910737 PMCID: PMC5992412 DOI: 10.3389/fphys.2018.00613] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/07/2018] [Indexed: 12/20/2022] Open
Abstract
Invertebrate neuropeptide F-I (NPF-I), much alike its mammalian homolog neuropeptide Y, influences several physiological processes, including circadian rhythms, cortical excitability, stress response, and food intake behavior. Given the role of autophagy in the metabolic stress response, we investigated the effect of NPF-1 on autophagy during fasting and feeding conditions in the hepatopancreas and muscle tissues of the male giant freshwater prawn Macrobrachium rosenbergii. Starvation up-regulated the expression of the autophagy marker LC3 in both tissues. Yet, based on the relative levels of the autophagosome-associated LC3-II isoform and of its precursor LC3-I, the hepatopancreas was more responsive than the muscle to starvation-induced autophagy. Injection of NPF-I inhibited the autophagosome formation in the hepatopancreas of fasting prawns. Relative to the body weight, the muscle weight was not affected, while that of the hepatopancreas decreased upon starvation and NPF-1 treatment could largely prevent such weight loss. Thus, the hepatopancreas is the reserve organ for the nutrient homeostasis during starvation and NPF-I plays a crucial role in the balancing of energy expenditure and energy intake during starvation by modulating autophagy.
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Affiliation(s)
- Sirorat Thongrod
- Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand.,Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Chaitip Wanichanon
- Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Wilairat Kankuan
- Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand.,Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Tanapan Siangcham
- Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Suratchanee Phadngam
- Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Federica Morani
- Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Ciro Isidoro
- Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Prasert Sobhon
- Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand.,Faculty of Allied Health Sciences, Burapha University, Chonburi, Thailand
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118
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Abstract
Autophagy is a highly conserved process and is essential for the maintenance of cellular homeostasis. Autophagy occurs at a basal level in all cells, but it can be up-regulated during stress, starvation, or infection. Misregulation of autophagy has been linked to various disorders, including cancer, neurodegeneration, and immune diseases. Here, we discuss the essential proteins acting in the formation of an autophagosome, with a focus on the ULK and VPS34 kinase complexes, phosphatidylinositol 3-phosphate effector proteins, and the transmembrane autophagy-related protein ATG9. The function and regulation of these and other autophagy-related proteins acting during formation will be addressed, in particular during amino acid starvation.
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Affiliation(s)
- Thomas J Mercer
- From the Molecular Cell Biology of Autophagy Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, United Kingdom
| | - Andrea Gubas
- From the Molecular Cell Biology of Autophagy Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, United Kingdom
| | - Sharon A Tooze
- From the Molecular Cell Biology of Autophagy Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, United Kingdom
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119
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Dowling SD, Macian F. Autophagy and T cell metabolism. Cancer Lett 2018; 419:20-26. [PMID: 29339212 PMCID: PMC5937942 DOI: 10.1016/j.canlet.2018.01.033] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/05/2018] [Accepted: 01/10/2018] [Indexed: 01/21/2023]
Abstract
Autophagy, a highly conserved catabolic process that involves the degradation and recycling of intracellular components in the lysosome, has emerged as a key process in the maintenance of T cell homeostasis and the regulation of T cell differentiation and function. In this review, we provide an overview of the mechanisms that mediate the regulation of autophagy in T cells and discuss different cellular processes that are under the control of autophagy in CD4+ and CD8+ T cells. A special emphasis is placed on the role that autophagy plays in the modulation of T cell metabolism and the consequences of this regulation on functional states and programs of differentiation in specific T cell populations.
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Affiliation(s)
- Samuel D Dowling
- Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
| | - Fernando Macian
- Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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120
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Kauffman KJ, Yu S, Jin J, Mugo B, Nguyen N, O'Brien A, Nag S, Lystad AH, Melia TJ. Delipidation of mammalian Atg8-family proteins by each of the four ATG4 proteases. Autophagy 2018; 14:992-1010. [PMID: 29458288 DOI: 10.1080/15548627.2018.1437341] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
During macroautophagy/autophagy, mammalian Atg8-family proteins undergo 2 proteolytic processing events. The first exposes a COOH-terminal glycine used in the conjugation of these proteins to lipids on the phagophore, the precursor to the autophagosome, whereas the second releases the lipid. The ATG4 family of proteases drives both cleavages, but how ATG4 proteins distinguish between soluble and lipid-anchored Atg8 proteins is not well understood. In a fully reconstituted delipidation assay, we establish that the physical anchoring of mammalian Atg8-family proteins in the membrane dramatically shifts the way ATG4 proteases recognize these substrates. Thus, while ATG4B is orders of magnitude faster at processing a soluble unprimed protein, all 4 ATG4 proteases can be activated to similar enzymatic activities on lipid-attached substrates. The recognition of lipidated but not soluble substrates is sensitive to a COOH-terminal LIR motif both in vitro and in cells. We suggest a model whereby ATG4B drives very fast priming of mammalian Atg8 proteins, whereas delipidation is inherently slow and regulated by all ATG4 homologs.
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Affiliation(s)
- Karlina J Kauffman
- a Department of Cell Biology , Yale University School of Medicine , New Haven , CT , USA
| | - Shenliang Yu
- a Department of Cell Biology , Yale University School of Medicine , New Haven , CT , USA
| | - Jiaxin Jin
- a Department of Cell Biology , Yale University School of Medicine , New Haven , CT , USA.,b Lanzhou University Second Hospital , Lanzhou , Gansu Province , China
| | - Brian Mugo
- a Department of Cell Biology , Yale University School of Medicine , New Haven , CT , USA
| | - Nathan Nguyen
- a Department of Cell Biology , Yale University School of Medicine , New Haven , CT , USA
| | - Aidan O'Brien
- a Department of Cell Biology , Yale University School of Medicine , New Haven , CT , USA
| | - Shanta Nag
- a Department of Cell Biology , Yale University School of Medicine , New Haven , CT , USA
| | - Alf Håkon Lystad
- c Department of Molecular Medicine , Institute of Basic Medical Sciences, University of Oslo , Norway
| | - Thomas J Melia
- a Department of Cell Biology , Yale University School of Medicine , New Haven , CT , USA
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121
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Kivinen N. The role of autophagy in age-related macular degeneration. Acta Ophthalmol 2018; 96 Suppl A110:1-50. [PMID: 29633521 DOI: 10.1111/aos.13753] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Niko Kivinen
- Department of Ophthalmology; University of Eastern Finland; Kuopio Finland
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122
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Li F, Zhang C, Li Y, Wu G, Hou X, Zhou X, Wang A. Beclin1 restricts RNA virus infection in plants through suppression and degradation of the viral polymerase. Nat Commun 2018; 9:1268. [PMID: 29593293 PMCID: PMC5871769 DOI: 10.1038/s41467-018-03658-2] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 02/28/2018] [Indexed: 01/22/2023] Open
Abstract
Autophagy emerges as an essential immunity defense against intracellular pathogens. Here we report that turnip mosaic virus (TuMV) infection activates autophagy in plants and that Beclin1 (ATG6), a core component of autophagy, inhibits virus replication. Beclin1 interacts with NIb, the RNA-dependent RNA polymerase (RdRp) of TuMV, via the highly conserved GDD motif and the interaction complex is targeted for autophagic degradation likely through the adaptor protein ATG8a. Beclin1-mediated NIb degradation is inhibited by autophagy inhibitors. Deficiency of Beclin1 or ATG8a enhances NIb accumulation and promotes viral infection and vice versa. These data suggest that Beclin1 may be a selective autophagy receptor. Overexpression of a Beclin1 truncation mutant that binds to NIb but lacks the ability to mediate NIb degradation also inhibits virus replication. The Beclin1-RdRp interaction further extends to several RNA viruses. Thus Beclin1 restricts viral infection through suppression and also likely autophagic degradation of the viral RdRp.
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Affiliation(s)
- Fangfang Li
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Department of Biology, Western University, London, ON, N6A 5B7, Canada
| | - Changwei Zhang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 210095, Nanjing, China
| | - Yinzi Li
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Department of Biology, Western University, London, ON, N6A 5B7, Canada
| | - Guanwei Wu
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Department of Biology, Western University, London, ON, N6A 5B7, Canada
| | - Xilin Hou
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 210095, Nanjing, China
| | - Xueping Zhou
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, 100193, Beijing, China
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada.
- Department of Biology, Western University, London, ON, N6A 5B7, Canada.
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123
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Lin MG, Schöneberg J, Davies CW, Ren X, Hurley JH. The dynamic Atg13-free conformation of the Atg1 EAT domain is required for phagophore expansion. Mol Biol Cell 2018. [PMID: 29540529 PMCID: PMC5935072 DOI: 10.1091/mbc.e17-04-0258] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Yeast macroautophagy begins with the de novo formation of a double-membrane phagophore at the preautophagosomal structure/phagophore assembly site (PAS), followed by its expansion into the autophagosome responsible for cargo engulfment. The kinase Atg1 is recruited to the PAS by Atg13 through interactions between the EAT domain of the former and the tMIM motif of the latter. Mass-spectrometry data have shown that, in the absence of Atg13, the EAT domain structure is strikingly dynamic, but the function of this Atg13-free dynamic state has been unclear. We used structure-based mutational analysis and quantitative and superresolution microscopy to show that Atg1 is present on autophagic puncta at, on average, twice the stoichiometry of Atg13. Moreover, Atg1 colocalizes with the expanding autophagosome in a manner dependent on Atg8 but not Atg13. We used isothermal titration calorimetry and crystal structure information to design an EAT domain mutant allele ATG1DD that selectively perturbs the function of the Atg13-free state. Atg1DD shows reduced PAS formation and does not support phagophore expansion, showing that the EAT domain has an essential function that is separate from its Atg13-dependent role in autophagy initiation.
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Affiliation(s)
- Mary G Lin
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720
| | - Johannes Schöneberg
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720
| | - Christopher W Davies
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720
| | - Xuefeng Ren
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720
| | - James H Hurley
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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124
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Pawlowska E, Szczepanska J, Szatkowska M, Blasiak J. An Interplay between Senescence, Apoptosis and Autophagy in Glioblastoma Multiforme-Role in Pathogenesis and Therapeutic Perspective. Int J Mol Sci 2018; 19:ijms19030889. [PMID: 29562589 PMCID: PMC5877750 DOI: 10.3390/ijms19030889] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 03/14/2018] [Accepted: 03/15/2018] [Indexed: 12/12/2022] Open
Abstract
Autophagy, cellular senescence, programmed cell death and necrosis are key responses of a cell facing a stress. These effects are partly interconnected, but regulation of their mutual interactions is not completely clear. That regulation seems to be especially important in cancer cells, which have their own program of development and demand more nutrition and energy than normal cells. Glioblastoma multiforme (GBM) belongs to the most aggressive and most difficult to cure cancers, so studies on its pathogenesis and new therapeutic strategies are justified. Using an animal model, it was shown that autophagy is required for GBM development. Temozolomide (TMZ) is the key drug in GBM chemotherapy and it was reported to induce senescence, autophagy and apoptosis in GBM. In some GBM cells, TMZ induces small toxicity despite its significant concentration and GBM cells can be intrinsically resistant to apoptosis. Resveratrol, a natural compound, was shown to potentiate anticancer effect of TMZ in GBM cells through the abrogation G2-arrest and mitotic catastrophe resulting in senescence of GBM cells. Autophagy is the key player in TMZ resistance in GBM. TMZ can induce apoptosis due to selective inhibition of autophagy, in which autophagic vehicles accumulate as their fusion with lysosomes is blocked. Modulation of autophagic action of TMZ with autophagy inhibitors can result in opposite outcomes, depending on the step targeted in autophagic flux. Studies on relationships between senescence, autophagy and apoptosis can open new therapeutic perspectives in GBM.
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Affiliation(s)
- Elzbieta Pawlowska
- Department of Orthodontics, Medical University of Lodz, 92-216 Lodz, Poland.
| | - Joanna Szczepanska
- Department of Pediatric Dentistry, Medical University of Lodz, 92-216 Lodz, Poland.
| | - Magdalena Szatkowska
- Department of Molecular Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland.
| | - Janusz Blasiak
- Department of Molecular Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland.
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125
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Anzell AR, Maizy R, Przyklenk K, Sanderson TH. Mitochondrial Quality Control and Disease: Insights into Ischemia-Reperfusion Injury. Mol Neurobiol 2018; 55:2547-2564. [PMID: 28401475 PMCID: PMC5636654 DOI: 10.1007/s12035-017-0503-9] [Citation(s) in RCA: 252] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 03/20/2017] [Indexed: 12/28/2022]
Abstract
Mitochondria are key regulators of cell fate during disease. They control cell survival via the production of ATP that fuels cellular processes and, conversely, cell death via the induction of apoptosis through release of pro-apoptotic factors such as cytochrome C. Therefore, it is essential to have stringent quality control mechanisms to ensure a healthy mitochondrial network. Quality control mechanisms are largely regulated by mitochondrial dynamics and mitophagy. The processes of mitochondrial fission (division) and fusion allow for damaged mitochondria to be segregated and facilitate the equilibration of mitochondrial components such as DNA, proteins, and metabolites. The process of mitophagy are responsible for the degradation and recycling of damaged mitochondria. These mitochondrial quality control mechanisms have been well studied in chronic and acute pathologies such as Parkinson's disease, Alzheimer's disease, stroke, and acute myocardial infarction, but less is known about how these two processes interact and contribute to specific pathophysiologic states. To date, evidence for the role of mitochondrial quality control in acute and chronic disease is divergent and suggests that mitochondrial quality control processes can serve both survival and death functions depending on the disease state. This review aims to provide a synopsis of the molecular mechanisms involved in mitochondrial quality control, to summarize our current understanding of the complex role that mitochondrial quality control plays in the progression of acute vs chronic diseases and, finally, to speculate on the possibility that targeted manipulation of mitochondrial quality control mechanisms may be exploited for the rationale design of novel therapeutic interventions.
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Affiliation(s)
- Anthony R Anzell
- Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, MI, 48201, USA
- Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, MI, 48201, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Rita Maizy
- Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Karin Przyklenk
- Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, MI, 48201, USA
- Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, MI, 48201, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Thomas H Sanderson
- Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
- Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
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126
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Cargo recognition and degradation by selective autophagy. Nat Cell Biol 2018; 20:233-242. [PMID: 29476151 DOI: 10.1038/s41556-018-0037-z] [Citation(s) in RCA: 733] [Impact Index Per Article: 122.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 01/05/2018] [Indexed: 12/12/2022]
Abstract
Macroautophagy, initially described as a non-selective nutrient recycling process, is essential for the removal of multiple cellular components. In the past three decades, selective autophagy has been characterized as a highly regulated and specific degradation pathway for removal of unwanted cytosolic components and damaged and/or superfluous organelles. Here, we discuss different types of selective autophagy, emphasizing the role of ligand receptors and scaffold proteins in providing cargo specificity, and highlight unanswered questions in the field.
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127
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Corridoni D, Chapman T, Ambrose T, Simmons A. Emerging Mechanisms of Innate Immunity and Their Translational Potential in Inflammatory Bowel Disease. Front Med (Lausanne) 2018. [PMID: 29515999 PMCID: PMC5825991 DOI: 10.3389/fmed.2018.00032] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Activation of the innate immune system through pattern-recognition receptor (PRR) signaling plays a pivotal role in the early induction of host defense following exposure to pathogens. Loss of intestinal innate immune regulation leading aberrant immune responses has been implicated in the pathogenesis of inflammatory bowel disease (IBD). The precise role of PRRs in gut inflammation is not well understood, but considering their role as bacterial sensors and their genetic association with IBD, they likely contribute to dysregulated immune responses to the commensal microbiota. The purpose of this review is to evaluate the emerging functions of PRRs including their functional cross-talk, how they respond to mitochondrial damage, induce mitophagy or autophagy, and influence adaptive immune responses by interacting with the antigen presentation machinery. The review also summarizes some of the recent attempts to harness these pathways for therapeutic approaches in intestinal inflammation.
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Affiliation(s)
- Daniele Corridoni
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.,Translational Gastroenterology Unit, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Thomas Chapman
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.,Translational Gastroenterology Unit, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Tim Ambrose
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.,Translational Gastroenterology Unit, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Alison Simmons
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.,Translational Gastroenterology Unit, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
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128
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Gao J, Langemeyer L, Kümmel D, Reggiori F, Ungermann C. Molecular mechanism to target the endosomal Mon1-Ccz1 GEF complex to the pre-autophagosomal structure. eLife 2018; 7:31145. [PMID: 29446751 PMCID: PMC5841931 DOI: 10.7554/elife.31145] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 02/12/2018] [Indexed: 11/13/2022] Open
Abstract
During autophagy, a newly formed double membrane surrounds its cargo to generate the so-called autophagosome, which then fuses with a lysosome after closure. Previous work implicated that endosomal Rab7/Ypt7 associates to autophagosomes prior to their fusion with lysosomes. Here, we unravel how the Mon1-Ccz1 guanosine exchange factor (GEF) acting upstream of Ypt7 is specifically recruited to the pre-autophagosomal structure under starvation conditions. We find that Mon1-Ccz1 directly binds to Atg8, the yeast homolog of the members of the mammalian LC3 protein family. This requires at least one LIR motif in the Ccz1 C-terminus, which is essential for autophagy but not for endosomal transport. In agreement, only wild-type, but not LIR-mutated Mon1-Ccz1 promotes Atg8-dependent activation of Ypt7. Our data reveal how GEF targeting can specify the fate of a newly formed organelle and provide new insights into the regulation of autophagosome-lysosome fusion. Autophagy is a word derived from the Greek for “self-eating”. It describes a biological process in which a living cell breaks down its own material to release their chemical building blocks that can then be used to make new molecules. Autophagy is often triggered when a cell becomes damaged or when nutrients are in short supply. The hallmark of autophagy is the formation of structures called autophagosomes. These structures capture the cellular material, fuse with other compartments in the cell – namely endosomes in animals and vacuoles in yeast – and then deliver the material inside, ready to be broken down. For an autophagosome to fuse to an endosome or a vacuole, small proteins of the Rab protein family must be located on the surface of the autophagosome. Rab proteins are recruited to this surface by enzymes known as GEFs. However it remains unclear how most GEFs get to the surface of a compartment within the cell to begin with. The Mon1-Ccz1 complex is a GEF that occurs in yeast and animals, including fruit flies and humans. It is found on endosomes, and was recently shown to also localize to autophagosomes. Now, Gao et al. report that, in yeast, the Mon1-Ccz1 complex binds directly to a protein named Atg8. This protein is anchored on to the surface of autophagosomes, and is closely related to other proteins in animal cells. Gao et al. discovered that this specific GEF binds to Atg8 via at least one binding site on its Ccz1 component. This binding site is only needed for the GEF to localize to the autophagosomes; the Mon1-Czz1 complex can still bind to endosomes without it. Blocking the GEF from binding to Atg8 stopped the autophagosomes from fusing with vacuoles. These findings reveal how a GEF can be targeted to two distinct compartments in the cell: endosomes and autophagosomes. Further work is now needed to understand how this process is regulated by the availability of nutrients or damage to the cell, to ensure that autophagy is only triggered under the right conditions. Also, because cancer cells often rely on autophagy to survive, the molecules that regulate this process could represent possible targets for new anticancer drugs.
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Affiliation(s)
- Jieqiong Gao
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Lars Langemeyer
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Daniel Kümmel
- Structural Biology Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Christian Ungermann
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
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129
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Kwon DH, Song HK. A Structural View of Xenophagy, a Battle between Host and Microbes. Mol Cells 2018; 41:27-34. [PMID: 29370690 PMCID: PMC5792709 DOI: 10.14348/molcells.2018.2274] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 02/06/2023] Open
Abstract
The cytoplasm in mammalian cells is a battlefield between the host and invading microbes. Both the living organisms have evolved unique strategies for their survival. The host utilizes a specialized autophagy system, xenophagy, for the clearance of invading pathogens, whereas bacteria secrete proteins to defend and escape from the host xenophagy. Several molecules have been identified and their structural investigation has enabled the comprehension of these mechanisms at the molecular level. In this review, we focus on one example of host autophagy and the other of bacterial defense: the autophagy receptor, NDP52, in conjunction with the sugar receptor, galectin-8, plays a critical role in targeting the autophagy machinery against Salmonella; and the cysteine protease, RavZ secreted by Legionella pneumophila cleaves the LC3-PE on the phagophore membrane. The structure-function relationships of these two examples and the directions of future research will be discussed.
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Affiliation(s)
- Do Hoon Kwon
- Department of Life Sciences, Korea University, Seoul 02841,
Korea
| | - Hyun Kyu Song
- Department of Life Sciences, Korea University, Seoul 02841,
Korea
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130
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Harper JW, Ordureau A, Heo JM. Building and decoding ubiquitin chains for mitophagy. Nat Rev Mol Cell Biol 2018; 19:93-108. [DOI: 10.1038/nrm.2017.129] [Citation(s) in RCA: 323] [Impact Index Per Article: 53.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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131
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Luis-Ravelo D, Estévez-Silva H, Barroso-Chinea P, Afonso-Oramas D, Salas-Hernández J, Rodríguez-Núñez J, Acevedo-Arozena A, Marcellino D, González-Hernández T. Pramipexole reduces soluble mutant huntingtin and protects striatal neurons through dopamine D3 receptors in a genetic model of Huntington's disease. Exp Neurol 2018; 299:137-147. [DOI: 10.1016/j.expneurol.2017.10.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 09/29/2017] [Accepted: 10/19/2017] [Indexed: 12/26/2022]
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132
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Moreno-Blas D, Gorostieta-Salas E, Castro-Obregón S. Connecting chaperone-mediated autophagy dysfunction to cellular senescence. Ageing Res Rev 2018; 41:34-41. [PMID: 29113832 DOI: 10.1016/j.arr.2017.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/26/2017] [Accepted: 11/03/2017] [Indexed: 12/20/2022]
Abstract
Chaperone-mediated autophagy (CMA) is one of the main pathways of the lysosome-autophagy proteolytic system. It regulates different cellular process through the selective degradation of cytosolic proteins. In ageing, the function of CMA is impaired causing an inefficient stress response and the accumulation of damaged, oxidized or misfolded proteins, which is associated with numerous age-related diseases. Deficient protein degradation alters cellular proteostasis and activates signaling pathways that culminate in the induction of cellular senescence, whose accumulation is a typical feature of ageing. However, the relationship between CMA activity and cellular senescence has been poorly studied. Here, we review and integrate evidence showing that CMA dysfunction correlates with the acquisition of many hallmarks of cellular senescence and propose that loss of CMA function during aging promotes cellular senescence.
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Affiliation(s)
- Daniel Moreno-Blas
- Department of Neurodevelopment and Physiology, Institute of Cellular Physiology, National Autonomous University of México (UNAM), Mexico City, Mexico.
| | - Elisa Gorostieta-Salas
- Department of Neurodevelopment and Physiology, Institute of Cellular Physiology, National Autonomous University of México (UNAM), Mexico City, Mexico.
| | - Susana Castro-Obregón
- Department of Neurodevelopment and Physiology, Institute of Cellular Physiology, National Autonomous University of México (UNAM), Mexico City, Mexico.
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133
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Dysregulation of autophagy as a common mechanism in lysosomal storage diseases. Essays Biochem 2017; 61:733-749. [PMID: 29233882 PMCID: PMC5869865 DOI: 10.1042/ebc20170055] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 10/08/2017] [Accepted: 10/12/2017] [Indexed: 12/19/2022]
Abstract
The lysosome plays a pivotal role between catabolic and anabolic processes as the nexus for signalling pathways responsive to a variety of factors, such as growth, nutrient availability, energetic status and cellular stressors. Lysosomes are also the terminal degradative organelles for autophagy through which macromolecules and damaged cellular components and organelles are degraded. Autophagy acts as a cellular homeostatic pathway that is essential for organismal physiology. Decline in autophagy during ageing or in many diseases, including late-onset forms of neurodegeneration is considered a major contributing factor to the pathology. Multiple lines of evidence indicate that impairment in autophagy is also a central mechanism underlying several lysosomal storage disorders (LSDs). LSDs are a class of rare, inherited disorders whose histopathological hallmark is the accumulation of undegraded materials in the lysosomes due to abnormal lysosomal function. Inefficient degradative capability of the lysosomes has negative impact on the flux through the autophagic pathway, and therefore dysregulated autophagy in LSDs is emerging as a relevant disease mechanism. Pathology in the LSDs is generally early-onset, severe and life-limiting but current therapies are limited or absent; recognizing common autophagy defects in the LSDs raises new possibilities for therapy. In this review, we describe the mechanisms by which LSDs occur, focusing on perturbations in the autophagy pathway and present the latest data supporting the development of novel therapeutic approaches related to the modulation of autophagy.
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134
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mTORC1 as the main gateway to autophagy. Essays Biochem 2017; 61:565-584. [PMID: 29233869 PMCID: PMC5869864 DOI: 10.1042/ebc20170027] [Citation(s) in RCA: 355] [Impact Index Per Article: 50.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 10/19/2017] [Accepted: 10/20/2017] [Indexed: 12/16/2022]
Abstract
Cells and organisms must coordinate their metabolic activity with changes in their environment to ensure their growth only when conditions are favourable. In order to maintain cellular homoeostasis, a tight regulation between the synthesis and degradation of cellular components is essential. At the epicentre of the cellular nutrient sensing is the mechanistic target of rapamycin complex 1 (mTORC1) which connects environmental cues, including nutrient and growth factor availability as well as stress, to metabolic processes in order to preserve cellular homoeostasis. Under nutrient-rich conditions mTORC1 promotes cell growth by stimulating biosynthetic pathways, including synthesis of proteins, lipids and nucleotides, and by inhibiting cellular catabolism through repression of the autophagic pathway. Its close signalling interplay with the energy sensor AMP-activated protein kinase (AMPK) dictates whether the cell actively favours anabolic or catabolic processes. Underlining the role of mTORC1 in the coordination of cellular metabolism, its deregulation is linked to numerous human diseases ranging from metabolic disorders to many cancers. Although mTORC1 can be modulated by a number of different inputs, amino acids represent primordial cues that cannot be compensated for by any other stimuli. The understanding of how amino acids signal to mTORC1 has increased considerably in the last years; however this area of research remains a hot topic in biomedical sciences. The current ideas and models proposed to explain the interrelationship between amino acid sensing, mTORC1 signalling and autophagy is the subject of the present review.
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135
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Yamaguchi M, Satoo K, Suzuki H, Fujioka Y, Ohsumi Y, Inagaki F, Noda NN. Atg7 Activates an Autophagy-Essential Ubiquitin-like Protein Atg8 through Multi-Step Recognition. J Mol Biol 2017; 430:249-257. [PMID: 29237558 DOI: 10.1016/j.jmb.2017.12.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 12/05/2017] [Accepted: 12/06/2017] [Indexed: 01/07/2023]
Abstract
Atg8 is a unique ubiquitin-like protein that is covalently conjugated with a phosphatidylethanolamine through reactions similar to ubiquitination and plays essential roles in autophagy. Atg7 is the E1 enzyme for Atg8, and it activates the C-terminal Gly116 of Atg8 using ATP. Here, we report the crystal structure of Atg8 bound to the C-terminal domain of Atg7 in an unprecedented mode. Atg8 neither contacts with the central β-sheet nor binds to the catalytic site of Atg7, both of which were observed in previously reported Atg7-Atg8 structures. Instead, Atg8 binds to the C-terminal α-helix and crossover loop, thereby changing the autoinhibited conformation of the crossover loop observed in the free Atg7 structure into a short helix and a disordered loop. Mutational analyses suggested that this interaction mode is important for the activation reaction. We propose that Atg7 recognizes Atg8 through multiple steps, which would be necessary to induce a conformational change in Atg7 that is optimal for the activation reaction.
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Affiliation(s)
- Masaya Yamaguchi
- Department of Structural Biology, Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Kenji Satoo
- Department of Structural Biology, Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Hironori Suzuki
- Institute of Microbial Chemistry (BIKAKEN), Tokyo 141-0021, Japan
| | - Yuko Fujioka
- Institute of Microbial Chemistry (BIKAKEN), Tokyo 141-0021, Japan
| | - Yoshinori Ohsumi
- Research Center for Cell Biology, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Fuyuhiko Inagaki
- Department of Structural Biology, Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Nobuo N Noda
- Institute of Microbial Chemistry (BIKAKEN), Tokyo 141-0021, Japan.
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136
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Shimasaki K, Watanabe-Takahashi M, Umeda M, Funamoto S, Saito Y, Noguchi N, Kumagai K, Hanada K, Tsukahara F, Maru Y, Shibata N, Naito M, Nishikawa K. Pleckstrin homology domain of p210 BCR-ABL interacts with cardiolipin to regulate its mitochondrial translocation and subsequent mitophagy. Genes Cells 2017; 23:22-34. [PMID: 29205725 DOI: 10.1111/gtc.12544] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 10/30/2017] [Indexed: 02/05/2023]
Abstract
Chronic myeloid leukemia (CML) is caused by the chimeric protein p210 BCR-ABL encoded by a gene on the Philadelphia chromosome. Although the kinase domain of p210 BCR-ABL is an active driver of CML, the pathological role of its pleckstrin homology (PH) domain remains unclear. Here, we carried out phospholipid vesicle-binding assays to show that cardiolipin (CL), a characteristic mitochondrial phospholipid, is a unique ligand of the PH domain. Arg726, a basic amino acid in the ligand-binding region, was crucial for ligand recognition. A subset of wild-type p210 BCR-ABL that was transiently expressed in HEK293 cells was dramatically translocated from the cytosol to mitochondria in response to carbonyl cyanide m-chlorophenylhydrazone (CCCP) treatment, which induces mitochondrial depolarization and subsequent externalization of CL to the organelle's outer membrane, whereas an R726A mutant of the protein was not translocated. Furthermore, only wild-type p210 BCR-ABL, but not the R726A mutant, suppressed CCCP-induced mitophagy and subsequently enhanced reactive oxygen species production. Thus, p210 BCR-ABL can change its intracellular localization via interactions between the PH domain and CL to cope with mitochondrial damage. This suggests that p210 BCR-ABL could have beneficial effects for cancer proliferation, providing new insight into the PH domain's contribution to CML pathogenesis.
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Affiliation(s)
- Kentaro Shimasaki
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Miho Watanabe-Takahashi
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Masato Umeda
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Satoru Funamoto
- Department of Neuropathology, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Yoshiro Saito
- Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Noriko Noguchi
- Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Keigo Kumagai
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kentaro Hanada
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Fujiko Tsukahara
- Department of Pharmacology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Yoshiro Maru
- Department of Pharmacology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Norihito Shibata
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, Tokyo, Japan
| | - Mikihiko Naito
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, Tokyo, Japan
| | - Kiyotaka Nishikawa
- Department of Molecular Life Sciences, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
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137
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Moura-Martiniano NO, Machado-Ferreira E, Gazêta GS, Soares CAG. Relative transcription of autophagy-related genes in Amblyomma sculptum and Rhipicephalus microplus ticks. EXPERIMENTAL & APPLIED ACAROLOGY 2017; 73:401-428. [PMID: 29181673 DOI: 10.1007/s10493-017-0193-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 11/17/2017] [Indexed: 06/07/2023]
Abstract
Ticks endure stressful off-host periods and perform as vectors of a diversity of infectious agents, thus engaging pathways that expectedly demand for autophagy. Little is known of ticks' autophagy, a conserved eukaryotic machinery assisting in homeostasis processes that also participates in tissue-dependent metabolic functions. Here, the autophagy-related ATG4 (autophagin-1), ATG6 (beclin-1) and ATG8 (LC3) mRNAs from the human diseases vector Amblyomma sculptum and the cattle-tick Rhipicephalus microplus were identified. Comparative qPCR quantifications evidenced different transcriptional status for the ATG genes in the salivary glands (SG), ovaries and intestines of actively feeding ticks. These ATGs had increased relative transcription under nutrient-deprivation, as determined by validation tests with R. microplus embryo-derivative cells BME26 and A. sculptum SG explants incubations in HBSS. Starvation lead to 4-31.8× and ~ 60-500× increments on the ATGs mRNA loads in BME26 and A. sculptum SG explants, respectively. PI3K inhibitor 3MA treatment also affected ATGs expression in BME26. Some ATGs were more transcribed in the SGs than in the ovaries of cattle-ticks. Amblyomma sculptum/R. microplus interspecific comparisons showed that ATG4 and ATG6 were 0.18× less expressed in A. sculptum SGs, but ~ 10-100× more expressed in their ovaries when compared to R. microplus organs. ATG4 and ATG8a transcript loads were ~ 120× and ~ 40× higher, respectively, in A. sculptum intestines when compared to cattle-ticks of similar weight category. ATGs expression in A. sculptum intestines increased with tick weight, indicating Atgs contribution to intracellular blood digestion. Possible roles of the autophagy machinery and their organ-specific expression profile on vector biology are discussed.
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Affiliation(s)
- Nicole O Moura-Martiniano
- Laboratório de Genética Molecular de Eucariontes e Simbiontes, Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Erik Machado-Ferreira
- Laboratório de Genética Molecular de Eucariontes e Simbiontes, Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gilberto S Gazêta
- Laboratório de Referência Nacional em Vetores das Riquetsioses, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Carlos Augusto Gomes Soares
- Laboratório de Genética Molecular de Eucariontes e Simbiontes, Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
- , Ilha do Fundão, CCS, Bloco A, Lab. A2-120. Rua Professor Rodolpho Paulo Rocco S/N, Rio de Janeiro, RJ, 21941-617, Brazil.
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138
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Pei Z, Deng Q, Babcock SA, He EY, Ren J, Zhang Y. Inhibition of advanced glycation endproduct (AGE) rescues against streptozotocin-induced diabetic cardiomyopathy: Role of autophagy and ER stress. Toxicol Lett 2017; 284:10-20. [PMID: 29174818 DOI: 10.1016/j.toxlet.2017.11.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 10/30/2017] [Accepted: 11/21/2017] [Indexed: 01/13/2023]
Abstract
Diabetes mellitus leads to oxidative stress and contractile dysfunction in the heart. Although several rationales have been speculated, the precise mechanism behind diabetic cardiomyopathy remains elusive. This study was designed to assess the role of inhibition of advanced glycation endproducts (AGE) in streptozotocin (STZ)-induced diabetic cardiac dysfunction. Cardiac contractile function was assessed in normal C57BL/6 and STZ (200mg/kg, single injection and maintained for 2 wks)-induced diabetic mice treated with or without the AGE inhibitor aminoguanidine (50mg/kg/d in drinking water) for 2 weeks using echocardiography and IonOptix MyoCam techniques. Diabetes compromised cardiac contractile function shown as reduced fractional shortening and ejection fraction, enlarged left ventricular end systolic/diastolic diameters, decreased peak shortening, maximal velocity of shortening/relengthening, prolonged shortening and relengthening duration as well as impaired intracellular Ca2+ homeostasis, the effects of which were alleviated or reversed by aminoguanidine treatment. Diabetes also inhibited autophagy, increased ER stress and phosphorylation of pro-hypertrophic signaling molecules Akt and mTOR, the effect of which was reversed by aminoguanidine. In vitro study revealed that methylglyoxal-derived AGE (MG-AGE) incubation in isolated cardiomyocytes promoted oxidation of sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2a) and production of superoxide, the effects of which were negated by the autophagy inducer rapamycin, the ER stress chaperone TUDCA or the antioxidant N-acetylcysteine. Taken together, these data revealed that inhibition of AGE formation rescues against experimental diabetes-induced cardiac remodeling and contractile dysfunction possible through regulation of autophagy and ER stress.
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Affiliation(s)
- Zhaohui Pei
- The Second Department of Cardiology, The Third Hospital of Nanchang, Nanchang, Jiangxi 330009, China
| | - Qinqin Deng
- The Second Department of Cardiology, The Third Hospital of Nanchang, Nanchang, Jiangxi 330009, China
| | - Sara A Babcock
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, WY 82071, USA
| | - Emily Y He
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, WY 82071, USA
| | - Jun Ren
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, WY 82071, USA; Department of Cardiology, Zhongshan Hospital Fudan University, Shanghai 210032, China.
| | - Yingmei Zhang
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, WY 82071, USA; Department of Cardiology, Zhongshan Hospital Fudan University, Shanghai 210032, China.
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139
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Human ATG3 binding to lipid bilayers: role of lipid geometry, and electric charge. Sci Rep 2017; 7:15614. [PMID: 29142222 PMCID: PMC5688168 DOI: 10.1038/s41598-017-15057-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 10/16/2017] [Indexed: 12/14/2022] Open
Abstract
Specific protein-lipid interactions lead to a gradual recruitment of AuTophaGy-related (ATG) proteins to the nascent membrane during autophagosome (AP) formation. ATG3, a key protein in the movement of LC3 towards the isolation membrane, has been proposed to facilitate LC3/GABARAP lipidation in highly curved membranes. In this work we have performed a biophysical study of human ATG3 interaction with membranes containing phosphatidylethanolamine, phosphatidylcholine and anionic phospholipids. We have found that ATG3 interacts more strongly with negatively-charged phospholipid vesicles or nanotubes than with electrically neutral model membranes, cone-shaped anionic phospholipids (cardiolipin and phosphatidic acid) being particularly active in promoting binding. Moreover, an increase in membrane curvature facilitates ATG3 recruitment to membranes although addition of anionic lipid molecules makes the curvature factor relatively less important. The predicted N-terminus amphipathic α-helix of ATG3 would be responsible for membrane curvature detection, the positive residues Lys 9 and 11 being essential in the recognition of phospholipid negative moieties. We have also observed membrane aggregation induced by ATG3 in vitro, which could point to a more complex function of this protein in AP biogenesis. Moreover, in vitro GABARAP lipidation assays suggest that ATG3-membrane interaction could facilitate the lipidation of ATG8 homologues.
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140
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Lipid-based DNA/siRNA transfection agents disrupt neuronal bioenergetics and mitophagy. Biochem J 2017; 474:3887-3902. [PMID: 29025974 DOI: 10.1042/bcj20170632] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/06/2017] [Accepted: 10/09/2017] [Indexed: 12/13/2022]
Abstract
A multitude of natural and artificial compounds have been recognized to modulate autophagy, providing direct or, through associated pathways, indirect entry points to activation and inhibition. While these pharmacological tools are extremely useful in the study of autophagy, their abundance also suggests the potential presence of unidentified autophagic modulators that may interfere with experimental designs if applied unknowingly. Here, we report unanticipated effects on autophagy and bioenergetics in neuronal progenitor cells (NPCs) incubated with the widely used lipid-based transfection reagent lipofectamine (LF), which induced mitochondria depolarization followed by disruption of electron transport. When NPCs were exposed to LF for 5 h followed by 24, 48, and 72 h in LF-free media, an immediate increase in mitochondrial ROS production and nitrotyrosine formation was observed. These events were accompanied by disrupted mitophagy (accumulation of dysfunctional and damaged mitochondria, and of LC3II and p62), in an mTOR- and AMPK-independent manner, and despite the increased mitochondrial PINK1 (PTEN-inducible kinase 1) localization. Evidence supported a role for a p53-mediated abrogation of parkin translocation and/or abrogation of membrane fusion between autophagosome and lysosomes. While most of the outcomes were LF-specific, only two were shared by OptiMEM exposure (with no serum and reduced glucose levels) albeit at lower extents. Taken together, our findings show that the use of transfection reagents requires critical evaluation with respect to consequences for overall cellular health, particularly in experiments designed to address autophagy-inducing effects and/or energy stress.
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141
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Zheng JX, Li Y, Ding YH, Liu JJ, Zhang MJ, Dong MQ, Wang HW, Yu L. Architecture of the ATG2B-WDR45 complex and an aromatic Y/HF motif crucial for complex formation. Autophagy 2017; 13:1870-1883. [PMID: 28820312 DOI: 10.1080/15548627.2017.1359381] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
PtdIns3P signaling is critical for dynamic membrane remodeling during autophagosome formation. Proteins in the Atg18/WIPI family are PtdIns3P-binding effectors which can form complexes with proteins in the Atg2 family, and both families are essential for macroautophagy/autophagy. However, little is known about the biophysical properties and biological functions of the Atg2-Atg18/WIPI complex as a whole. Here, we demonstrate that an ortholog of yeast Atg18, mammalian WDR45/WIPI4 has a stronger binding capacity for mammalian ATG2A or ATG2B than the other 3 WIPIs. We purified the full-length Rattus norvegicus ATG2B and found that it could bind to liposomes independently of PtdIns3P or WDR45. We also purified the ATG2B-WDR45 complex and then performed 3-dimensional reconstruction of the complex by single-particle electron microscopy, which revealed a club-shaped heterodimer with an approximate length of 22 nm. Furthermore, we performed cross-linking mass spectrometry and identified a set of highly cross-linked intermolecular and intramolecular lysine pairs. Finally, based on the cross-linking data followed by bioinformatics and mutagenesis analysis, we determined the conserved aromatic H/YF motif in the C terminus of ATG2A and ATG2B that is crucial for complex formation.
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Affiliation(s)
- Jing-Xiang Zheng
- a State Key Laboratory of Membrane Biology , Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University , Beijing , China.,b Joint Graduate Program of Peking-Tsinghua-National Institute of Biological Science , Tsinghua University , Beijing , China
| | - Yan Li
- c Ministry of Education Key Laboratory of Protein Sciences , Tsinghua-Peking Joint Center for Life Sciences , Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing , China
| | - Yue-He Ding
- d National Institute of Biological Sciences , Beijing , China
| | - Jun-Jie Liu
- b Joint Graduate Program of Peking-Tsinghua-National Institute of Biological Science , Tsinghua University , Beijing , China.,c Ministry of Education Key Laboratory of Protein Sciences , Tsinghua-Peking Joint Center for Life Sciences , Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing , China
| | - Mei-Jun Zhang
- d National Institute of Biological Sciences , Beijing , China
| | - Meng-Qiu Dong
- d National Institute of Biological Sciences , Beijing , China
| | - Hong-Wei Wang
- c Ministry of Education Key Laboratory of Protein Sciences , Tsinghua-Peking Joint Center for Life Sciences , Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing , China
| | - Li Yu
- a State Key Laboratory of Membrane Biology , Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University , Beijing , China
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142
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Heckmann BL, Boada-Romero E, Cunha LD, Magne J, Green DR. LC3-Associated Phagocytosis and Inflammation. J Mol Biol 2017; 429:3561-3576. [PMID: 28847720 DOI: 10.1016/j.jmb.2017.08.012] [Citation(s) in RCA: 181] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/16/2017] [Accepted: 08/22/2017] [Indexed: 02/06/2023]
Abstract
LC3-associated phagocytosis (LAP) is a novel form of non-canonical autophagy where LC3 (microtubule-associated protein 1A/1B-light chain 3) is conjugated to phagosome membranes using a portion of the canonical autophagy machinery. The impact of LAP to immune regulation is best characterized in professional phagocytes, in particular macrophages, where LAP has instrumental roles in the clearance of extracellular particles including apoptotic cells and pathogens. Binding of dead cells via receptors present on the macrophage surface results in the translocation of the autophagy machinery to the phagosome and ultimately LC3 conjugation. These events promote a rapid form of phagocytosis that produces an "immunologically silent" clearance of the apoptotic cells. Consequences of LAP deficiency include a decreased capacity to clear dying cells and the establishment of a lupus-like autoimmune disease in mice. The ability of LAP to attenuate autoimmunity likely occurs through the dampening of pro-inflammatory signals upon engulfment of dying cells and prevention of autoantigen presentation to other immune cells. However, it remains unclear how LAP shapes both the activation and outcome of the immune response at the molecular level. Herein, we provide a detailed review of LAP and its known roles in the immune response and provide further speculation on the putative mechanisms by which LAP may regulate immune function, perhaps through the metabolic reprogramming and polarization of macrophages.
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Affiliation(s)
- Bradlee L Heckmann
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, United States
| | - Emilio Boada-Romero
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, United States
| | - Larissa D Cunha
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, United States
| | - Joelle Magne
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, United States
| | - Douglas R Green
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, United States.
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143
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Defective expression of ATG4D abrogates autophagy and promotes growth in human uterine fibroids. Cell Death Discov 2017; 3:17041. [PMID: 28815060 PMCID: PMC5554887 DOI: 10.1038/cddiscovery.2017.41] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 05/05/2017] [Accepted: 05/22/2017] [Indexed: 02/07/2023] Open
Abstract
Uterine fibroids (UF) are the most common pelvic tumors in women of reproductive-age and they usually cause heavy menstrual bleeding, pain and infertility. Autophagy is a collection of processes that enables the cells to digest and recycle their cytoplasmic contents, such as toxic protein aggregates, defunct or disused organelles and invading microorganisms. Dysregulation in autophagy process were described in neoplasms; however, the contribution of autophagy to the pathogenesis of UF remains unknown. In this study, we demonstrate that autophagy is deregulated in human UF as evidenced by significant accumulation of autophagosome in human UF cells compared to normal myometrium cells. Analysis of the autophagy markers revealed an enhanced initiation of the autophagy in UF tissues compared to their adjacent myometrial tissues (MyoF). However, autophagosome maturation and flux was blocked in UF tissues, as marked by accumulation of LC3-B and P62 protein. This block was associated with defective expression of autophagy-related protein 4 (ATG4) in the UF tissues compared to MyoF in ~90% of patient samples. Silencing of ATG4D in normal human myometrial cells resulted in defective autophagy flux, enhanced cell proliferation and increased extracellular matrix production, which phenocopy UF cell line. This study indicates that impairment of autophagy flux secondary to defective expression of ATG4D expression is a new mechanistic aberration that contributes to UF pathogenesis. Targeting autophagy pathway could provide novel medical therapeutic approach for non-surgical treatment of UF.
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144
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Stürner E, Behl C. The Role of the Multifunctional BAG3 Protein in Cellular Protein Quality Control and in Disease. Front Mol Neurosci 2017; 10:177. [PMID: 28680391 PMCID: PMC5478690 DOI: 10.3389/fnmol.2017.00177] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 05/18/2017] [Indexed: 01/01/2023] Open
Abstract
In neurons, but also in all other cells the complex proteostasis network is monitored and tightly regulated by the cellular protein quality control (PQC) system. Beyond folding of newly synthesized polypeptides and their refolding upon misfolding the PQC also manages the disposal of aberrant proteins either by the ubiquitin-proteasome machinery or by the autophagic-lysosomal system. Aggregated proteins are primarily degraded by a process termed selective macroautophagy (or aggrephagy). One such recently discovered selective macroautophagy pathway is mediated by the multifunctional HSP70 co-chaperone BAG3 (BCL-2-associated athanogene 3). Under acute stress and during cellular aging, BAG3 in concert with the molecular chaperones HSP70 and HSPB8 as well as the ubiquitin receptor p62/SQSTM1 specifically targets aggregation-prone proteins to autophagic degradation. Thereby, BAG3-mediated selective macroautophagy represents a pivotal adaptive safeguarding and emergency system of the PQC which is activated under pathophysiological conditions to ensure cellular proteostasis. Interestingly, BAG3-mediated selective macroautophagy is also involved in the clearance of aggregated proteins associated with age-related neurodegenerative disorders, like Alzheimer’s disease (tau-protein), Huntington’s disease (mutated huntingtin/polyQ proteins), and amyotrophic lateral sclerosis (mutated SOD1). In addition, based on its initial description BAG3 is an anti-apoptotic protein that plays a decisive role in other widespread diseases, including cancer and myopathies. Therefore, in the search for novel therapeutic intervention avenues in neurodegeneration, myopathies and cancer BAG3 is a promising candidate.
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Affiliation(s)
- Elisabeth Stürner
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg University MainzMainz, Germany
| | - Christian Behl
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg University MainzMainz, Germany
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145
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Abstract
Eukaryotes use autophagy as a mechanism for maintaining cellular homeostasis by degrading and recycling organelles and proteins. This process assists in the proliferation and survival of advanced cancers. There is mounting preclinical evidence that targeting autophagy can enhance the efficacy of many cancer therapies. Hydroxychloroquine (HCQ) is the only clinically-approved autophagy inhibitor, and this systematic review focuses on HCQ use in cancer clinical trials. Preclinical trials have shown that HCQ alone and in combination therapy leads to enhancement of tumor shrinkage. This has provided the base for multiple ongoing clinical trials involving HCQ alone and in combination with other treatments. However, due to its potency, there is still a need for more potent and specific autophagy inhibitors. There are multiple autophagy inhibitors in the pre-clinical stage at various stages of development. Additional studies on the mechanism of HCQ and other autophagy inhibitors are still required to answer questions surrounding how these agents will eventually be used in the clinic.
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Affiliation(s)
- Cynthia I Chude
- Department of Medicine and Abramson Cancer Center, University of Pennsylvania, 852 BRB, 421 Curie Blvd, Philadelphia, PA 19104, USA.
| | - Ravi K Amaravadi
- Department of Medicine and Abramson Cancer Center, University of Pennsylvania, 852 BRB, 421 Curie Blvd, Philadelphia, PA 19104, USA.
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146
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Yu S, Melia TJ. The coordination of membrane fission and fusion at the end of autophagosome maturation. Curr Opin Cell Biol 2017; 47:92-98. [PMID: 28463755 DOI: 10.1016/j.ceb.2017.03.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 02/16/2017] [Accepted: 03/21/2017] [Indexed: 10/19/2022]
Abstract
The two major objectives of macroautophagy are to sequester cargo away from the cytoplasm and deliver this material for breakdown in the lysosome. Sequestration is complete when the autophagosome membrane undergoes fission to produce separate inner and outer membranes, while delivery into the lysosome requires fusion of the outer autophagosome membrane with the lysosome membrane. Thus, the merging of membranes through fission and fusion underlies each of the pivotal events in macroautophagic clearance. How these merging events are controlled in the cell is poorly understood. Several recent studies however suggest that the two events may be temporally coordinated and rely upon members of the classic membrane fusion SNARE family as well as the autophagy-specific family of Atg8 proteins.
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Affiliation(s)
- Shenliang Yu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, United States
| | - Thomas J Melia
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, United States.
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147
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Yang A, Pantoom S, Wu YW. Elucidation of the anti-autophagy mechanism of the Legionella effector RavZ using semisynthetic LC3 proteins. eLife 2017; 6. [PMID: 28395732 PMCID: PMC5388539 DOI: 10.7554/elife.23905] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 03/15/2017] [Indexed: 12/13/2022] Open
Abstract
Autophagy is a conserved cellular process involved in the elimination of proteins and organelles. It is also used to combat infection with pathogenic microbes. The intracellular pathogen Legionella pneumophila manipulates autophagy by delivering the effector protein RavZ to deconjugate Atg8/LC3 proteins coupled to phosphatidylethanolamine (PE) on autophagosomal membranes. To understand how RavZ recognizes and deconjugates LC3-PE, we prepared semisynthetic LC3 proteins and elucidated the structures of the RavZ:LC3 interaction. Semisynthetic LC3 proteins allowed the analysis of structure-function relationships. RavZ extracts LC3-PE from the membrane before deconjugation. RavZ initially recognizes the LC3 molecule on membranes via its N-terminal LC3-interacting region (LIR) motif. The RavZ α3 helix is involved in extraction of the PE moiety and docking of the acyl chains into the lipid-binding site of RavZ that is related in structure to that of the phospholipid transfer protein Sec14. Thus, Legionella has evolved a novel mechanism to specifically evade host autophagy.
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Affiliation(s)
- Aimin Yang
- Institute of Chemical Biology and Precision Therapy, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.,Chemical Genomics Centre of the Max Planck Society, Dortmund, Germany.,Max-Planck-Institute of Molecular Physiology, Dortmund, Germany
| | - Supansa Pantoom
- Chemical Genomics Centre of the Max Planck Society, Dortmund, Germany.,Max-Planck-Institute of Molecular Physiology, Dortmund, Germany
| | - Yao-Wen Wu
- Institute of Chemical Biology and Precision Therapy, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.,Chemical Genomics Centre of the Max Planck Society, Dortmund, Germany.,Max-Planck-Institute of Molecular Physiology, Dortmund, Germany
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148
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Complex inhibition of autophagy by mitochondrial aldehyde dehydrogenase shortens lifespan and exacerbates cardiac aging. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1919-1932. [PMID: 28347844 DOI: 10.1016/j.bbadis.2017.03.016] [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] [Received: 12/17/2016] [Revised: 03/21/2017] [Accepted: 03/22/2017] [Indexed: 02/07/2023]
Abstract
Autophagy, a conservative degradation process for long-lived and damaged proteins, participates in a cascade of biological processes including aging. A number of autophagy regulators have been identified. Here we demonstrated that mitochondrial aldehyde dehydrogenase (ALDH2), an enzyme with the most common single point mutation in humans, governs cardiac aging through regulation of autophagy. Myocardial mechanical and autophagy properties were examined in young (4months) and old (26-28months) wild-type (WT) and global ALDH2 transgenic mice. ALDH2 overexpression shortened lifespan by 7.7% without affecting aging-associated changes in plasma metabolic profiles. Myocardial function was compromised with aging associated with cardiac hypertrophy, the effects were accentuated by ALDH2. Aging overtly suppressed autophagy and compromised autophagy flux, the effects were exacerbated by ALDH2. Aging dampened phosphorylation of JNK, Bcl-2, IKKβ, AMPK and TSC2 while promoting phosphorylation of mTOR, the effects of which were exaggerated by ALDH2. Co-immunoprecipitation revealed increased dissociation between Bcl-2 and Beclin-1 (result of decreased Bcl-2 phosphorylation) in aging, the effect of which was exacerbated with ALDH2. Chronic treatment of the autophagy inducer rapamycin alleviated aging-induced cardiac dysfunction in both WT and ALDH2 mice. Moreover, activation of JNK and inhibition of either Bcl-2 or IKKβ overtly attenuated ALDH2 activation-induced accentuation of cardiomyocyte aging. Examination of the otherwise elderly individuals revealed a positive correlation between cardiac function/geometry and ALDH2 gene mutation. Taken together, our data revealed that ALDH2 enzyme may suppress myocardial autophagy possibly through a complex JNK-Bcl-2 and IKKβ-AMPK-dependent mechanism en route to accentuation of myocardial remodeling and contractile dysfunction in aging. This article is part of a Special Issue entitled: Genetic and epigenetic control of heart failure - edited by Jun Ren & Megan Yingmei Zhang.
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149
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Ubiquitylation of p62/sequestosome1 activates its autophagy receptor function and controls selective autophagy upon ubiquitin stress. Cell Res 2017; 27:657-674. [PMID: 28322253 DOI: 10.1038/cr.2017.40] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 12/06/2016] [Accepted: 01/22/2017] [Indexed: 12/16/2022] Open
Abstract
Alterations in cellular ubiquitin (Ub) homeostasis, known as Ub stress, feature and affect cellular responses in multiple conditions, yet the underlying mechanisms are incompletely understood. Here we report that autophagy receptor p62/sequestosome-1 interacts with E2 Ub conjugating enzymes, UBE2D2 and UBE2D3. Endogenous p62 undergoes E2-dependent ubiquitylation during upregulation of Ub homeostasis, a condition termed as Ub+ stress, that is intrinsic to Ub overexpression, heat shock or prolonged proteasomal inhibition by bortezomib, a chemotherapeutic drug. Ubiquitylation of p62 disrupts dimerization of the UBA domain of p62, liberating its ability to recognize polyubiquitylated cargoes for selective autophagy. We further demonstrate that this mechanism might be critical for autophagy activation upon Ub+ stress conditions. Delineation of the mechanism and regulatory roles of p62 in sensing Ub stress and controlling selective autophagy could help to understand and modulate cellular responses to a variety of endogenous and environmental challenges, potentially opening a new avenue for the development of therapeutic strategies against autophagy-related maladies.
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150
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Santana-Codina N, Mancias JD, Kimmelman AC. The Role of Autophagy in Cancer. ANNUAL REVIEW OF CANCER BIOLOGY-SERIES 2017; 1:19-39. [PMID: 31119201 DOI: 10.1146/annurev-cancerbio-041816-122338] [Citation(s) in RCA: 137] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Autophagy is a highly conserved and regulated process that targets proteins and damaged organelles for lysosomal degradation to maintain cell metabolism, genomic integrity, and cell survival. The role of autophagy in cancer is dynamic and depends, in part, on tumor type and stage. Although autophagy constrains tumor initiation in normal tissue, some tumors rely on autophagy for tumor promotion and maintenance. Studies in genetically engineered mouse models support the idea that autophagy can constrain tumor initiation by regulating DNA damage and oxidative stress. In established tumors, autophagy can also be required for tumor maintenance, allowing tumors to survive environmental stress and providing intermediates for cell metabolism. Autophagy can also be induced in response to chemotherapeutics, acting as a drug-resistance mechanism. Therefore, targeting autophagy is an attractive cancer therapeutic option currently undergoing validation in clinical trials.
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Affiliation(s)
- Naiara Santana-Codina
- Division of Genomic Stability and DNA Repair, Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215
| | - Joseph D Mancias
- Division of Genomic Stability and DNA Repair, Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215
| | - Alec C Kimmelman
- Department of Radiation Oncology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY 10016;
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