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Abstract
Macroautophagy is an intracellular degradation system that delivers diverse cytoplasmic materials to lysosomes via autophagosomes. Recent advances have enabled identification of several selective autophagy substrates and receptors, greatly expanding our understanding of the cellular functions of autophagy. In this review, we describe the diverse cellular functions of macroautophagy, including its essential contribution to metabolic adaptation and cellular homeostasis. We also discuss emerging findings on the mechanisms and functions of various types of selective autophagy.
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Affiliation(s)
- Hideaki Morishita
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; ,
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; ,
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202
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Zientara-Rytter K, Subramani S. Mechanistic Insights into the Role of Atg11 in Selective Autophagy. J Mol Biol 2019; 432:104-122. [PMID: 31238043 DOI: 10.1016/j.jmb.2019.06.017] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/11/2019] [Accepted: 06/13/2019] [Indexed: 12/19/2022]
Abstract
Macroautophagy (referred to hereafter as autophagy) is an intracellular degradation pathway in which the formation of a double-membrane vesicle called the autophagosome is a key event in the transport of multiple cytoplasmic cargo (e.g., proteins, protein aggregates, lipid droplets or organelles) to the vacuole (lysosome in mammals) for degradation and recycling. During this process, autophagosomes are formed de novo by membrane fusion events leading to phagophore formation initiated at the phagophore assembly site. In yeast, Atg11 and Atg17 function as protein scaffolds, essential for selective and non-selective types of autophagy, respectively. While Atg17 functions in non-selective autophagy are well-defined in the literature, less attention is concentrated on recent findings regarding the roles of Atg11 in selective autophagy. Here, we summarize current knowledge about the Atg11 scaffold protein and review recent findings in the context of its role in selective autophagy initiation and autophagosome formation.
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Affiliation(s)
- Katarzyna Zientara-Rytter
- Section of Molecular Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA.
| | - Suresh Subramani
- Section of Molecular Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
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203
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Wilkinson S. ER-phagy: shaping up and destressing the endoplasmic reticulum. FEBS J 2019; 286:2645-2663. [PMID: 31116513 PMCID: PMC6772018 DOI: 10.1111/febs.14932] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/09/2019] [Accepted: 05/20/2019] [Indexed: 12/16/2022]
Abstract
The endoplasmic reticulum (ER) network has central roles in metabolism and cellular organization. The ER undergoes dynamic alterations in morphology, molecular composition and functional specification. Remodelling of the network under fluctuating conditions enables the continual performance of ER functions and minimizes stress. Recent data have revealed that selective autophagy‐mediated degradation of ER fragments, or ER‐phagy, fundamentally contributes to this remodelling. This review provides a perspective on established views of selective autophagy, comparing these with emerging mechanisms of ER‐phagy and related processes. The text discusses the impact of ER‐phagy on the function of the ER‐ and the cell, both in normal physiology and when dysregulated within disease settings. Finally, unanswered questions regarding the mechanisms and significance of ER‐phagy are highlighted.
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Affiliation(s)
- Simon Wilkinson
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, UK
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204
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Marshall RS, Vierstra RD. Dynamic Regulation of the 26S Proteasome: From Synthesis to Degradation. Front Mol Biosci 2019; 6:40. [PMID: 31231659 PMCID: PMC6568242 DOI: 10.3389/fmolb.2019.00040] [Citation(s) in RCA: 138] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/09/2019] [Indexed: 01/12/2023] Open
Abstract
All eukaryotes rely on selective proteolysis to control the abundance of key regulatory proteins and maintain a healthy and properly functioning proteome. Most of this turnover is catalyzed by the 26S proteasome, an intricate, multi-subunit proteolytic machine. Proteasomes recognize and degrade proteins first marked with one or more chains of poly-ubiquitin, the addition of which is actuated by hundreds of ligases that individually identify appropriate substrates for ubiquitylation. Subsequent proteasomal digestion is essential and influences a myriad of cellular processes in species as diverse as plants, fungi and humans. Importantly, dysfunction of 26S proteasomes is associated with numerous human pathologies and profoundly impacts crop performance, thus making an understanding of proteasome dynamics critically relevant to almost all facets of human health and nutrition. Given this widespread significance, it is not surprising that sophisticated mechanisms have evolved to tightly regulate 26S proteasome assembly, abundance and activity in response to demand, organismal development and stress. These include controls on transcription and chaperone-mediated assembly, influences on proteasome localization and activity by an assortment of binding proteins and post-translational modifications, and ultimately the removal of excess or damaged particles via autophagy. Intriguingly, the autophagic clearance of damaged 26S proteasomes first involves their modification with ubiquitin, thus connecting ubiquitylation and autophagy as key regulatory events in proteasome quality control. This turnover is also influenced by two distinct biomolecular condensates that coalesce in the cytoplasm, one attracting damaged proteasomes for autophagy, and the other reversibly storing proteasomes during carbon starvation to protect them from autophagic clearance. In this review, we describe the current state of knowledge regarding the dynamic regulation of 26S proteasomes at all stages of their life cycle, illustrating how protein degradation through this proteolytic machine is tightly controlled to ensure optimal growth, development and longevity.
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Affiliation(s)
- Richard S Marshall
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
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205
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Yang F, Li Y, Duan H, Wang H, Pei F, Chen Z, Zhang L. Activation of mitophagy in inflamed odontoblasts. Oral Dis 2019; 25:1581-1588. [PMID: 31009146 DOI: 10.1111/odi.13110] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 03/16/2019] [Accepted: 04/16/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Fuhua Yang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM) School and Hospital of StomatologyWuhan University Wuhan China
| | - Yuan Li
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM) School and Hospital of StomatologyWuhan University Wuhan China
| | - Huiling Duan
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM) School and Hospital of StomatologyWuhan University Wuhan China
| | - Haisheng Wang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM) School and Hospital of StomatologyWuhan University Wuhan China
| | - Fei Pei
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM) School and Hospital of StomatologyWuhan University Wuhan China
| | - Zhi Chen
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM) School and Hospital of StomatologyWuhan University Wuhan China
- Department of Endodontics, School and Hospital of Stomatology Wuhan University Wuhan China
| | - Lu Zhang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei‐MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM) School and Hospital of StomatologyWuhan University Wuhan China
- Department of Endodontics, School and Hospital of Stomatology Wuhan University Wuhan China
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206
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Abstract
Autophagy is a self-eating catabolic pathway that contributes to liver homeostasis through its role in energy balance and in the quality control of the cytoplasm, by removing misfolded proteins, damaged organelles and lipid droplets. Autophagy not only regulates hepatocyte functions but also impacts on non-parenchymal cells, such as endothelial cells, macrophages and hepatic stellate cells. Deregulation of autophagy has been linked to many liver diseases and its modulation is now recognized as a potential new therapeutic strategy. Indeed, enhancing autophagy may prevent the progression of a number of liver diseases, including storage disorders (alpha-1 antitrypsin deficiency, Wilson's disease), acute liver injury, non-alcoholic steatohepatitis and chronic alcohol-related liver disease. Nevertheless, in some situations such as fibrosis, targeting specific liver cells must be considered, as autophagy displays opposing functions depending on the cell type. In addition, an optimal therapeutic time-window should be identified, since autophagy might be beneficial in the initial stages of disease, but detrimental at more advanced stages, as in the case of hepatocellular carcinoma. Finally, identifying biomarkers of autophagy and methods to monitor autophagic flux in vivo are important steps for the future development of personalized autophagy-targeting strategies. In this review, we provide an update on the regulatory role of autophagy in various aspects of liver pathophysiology, describing the different strategies to manipulate autophagy and discussing the potential to modulate autophagy as a therapeutic strategy in the context of liver diseases.
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207
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Wang X, Wang P, Zhang Z, Farré JC, Li X, Wang R, Xia Z, Subramani S, Ma C. The autophagic degradation of cytosolic pools of peroxisomal proteins by a new selective pathway. Autophagy 2019; 16:154-166. [PMID: 31007124 PMCID: PMC6984484 DOI: 10.1080/15548627.2019.1603546] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Damaged or redundant peroxisomes and their luminal cargoes are removed by pexophagy, a selective autophagy pathway. In yeasts, pexophagy depends mostly on the pexophagy receptors, such as Atg30 for Pichia pastoris and Atg36 for Saccharomyces cerevisiae, the autophagy scaffold proteins, Atg11 and Atg17, and the core autophagy machinery. In P. pastoris, the receptors for peroxisomal matrix proteins containing peroxisomal targeting signals (PTSs) include the PTS1 receptor, Pex5, and the PTS2 receptor and co-receptor, Pex7 and Pex20, respectively. These shuttling receptors are predominantly cytosolic and only partially peroxisomal. It remains unresolved as to whether, when and how the cytosolic pools of peroxisomal receptors, as well as the peroxisomal matrix proteins, are degraded under pexophagy conditions. These cytosolic pools exist both in normal and mutant cells impaired in peroxisome biogenesis. We report here that Pex5 and Pex7, but not Pex20, are degraded by an Atg30-independent, selective autophagy pathway. To enter this selective autophagy pathway, Pex7 required its major PTS2 cargo, Pot1. Similarly, the degradation of Pex5 was inhibited in cells missing abundant PTS1 cargoes, such as alcohol oxidases and Fox2 (hydratase-dehydrogenase-epimerase). Furthermore, in cells deficient in PTS receptors, the cytosolic pools of peroxisomal matrix proteins, such as Pot1 and Fox2, were also removed by Atg30-independent, selective autophagy, under pexophagy conditions. In summary, the cytosolic pools of PTS receptors and their cargoes are degraded via a pexophagy-independent, selective autophagy pathway under pexophagy conditions. These autophagy pathways likely protect cells from futile enzymatic reactions that could potentially cause the accumulation of toxic cytosolic products.Abbreviations: ATG: autophagy related; Cvt: cytoplasm to vacuole targeting; Fox2: hydratase-dehydrogenase-epimerase; PAGE: polyacrylamide gel electrophoresis; Pot1: thiolase; PMP: peroxisomal membrane protein; Pgk1: 3-phosphoglycerate kinase; PTS: peroxisomal targeting signal; RADAR: receptor accumulation and degradation in the absence of recycling; RING: really interesting new gene; SDS: sodium dodecyl sulphate; TCA, trichloroacetic acid; Ub: ubiquitin; UPS: ubiquitin-proteasome system Vid: vacuole import and degradation.
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Affiliation(s)
- Xiaofeng Wang
- College of Life Sciences, Shandong Normal University, Jinan, Shandong, China
| | - Pingping Wang
- College of Life Sciences, Shandong Normal University, Jinan, Shandong, China
| | - Zhuangzhuang Zhang
- College of Life Sciences, Shandong Normal University, Jinan, Shandong, China
| | - Jean-Claude Farré
- Section of Molecular Biology, Division of Biological Sciences, University of California, La Jolla, CA, USA
| | - Xuezhi Li
- College of Life Sciences, Shandong Normal University, Jinan, Shandong, China
| | - Ruonan Wang
- College of Life Sciences, Shandong Normal University, Jinan, Shandong, China
| | - Zhijie Xia
- College of Life Sciences, Shandong Normal University, Jinan, Shandong, China.,Section of Molecular Biology, Division of Biological Sciences, University of California, La Jolla, CA, USA
| | - Suresh Subramani
- Section of Molecular Biology, Division of Biological Sciences, University of California, La Jolla, CA, USA
| | - Changle Ma
- College of Life Sciences, Shandong Normal University, Jinan, Shandong, China
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208
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Wang L, Howell MEA, Sparks-Wallace A, Hawkins C, Nicksic CA, Kohne C, Hall KH, Moorman JP, Yao ZQ, Ning S. p62-mediated Selective autophagy endows virus-transformed cells with insusceptibility to DNA damage under oxidative stress. PLoS Pathog 2019; 15:e1007541. [PMID: 31017975 PMCID: PMC6502431 DOI: 10.1371/journal.ppat.1007541] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 05/06/2019] [Accepted: 03/26/2019] [Indexed: 12/26/2022] Open
Abstract
DNA damage response (DDR) and selective autophagy both can be activated by reactive oxygen/nitrogen species (ROS/RNS), and both are of paramount importance in cancer development. The selective autophagy receptor and ubiquitin (Ub) sensor p62 plays a key role in their crosstalk. ROS production has been well documented in latent infection of oncogenic viruses including Epstein-Barr Virus (EBV). However, p62-mediated selective autophagy and its interplay with DDR have not been investigated in these settings. In this study, we provide evidence that considerable levels of p62-mediated selective autophagy are spontaneously induced, and correlate with ROS-Keap1-NRF2 pathway activity, in virus-transformed cells. Inhibition of autophagy results in p62 accumulation in the nucleus, and promotes ROS-induced DNA damage and cell death, as well as downregulates the DNA repair proteins CHK1 and RAD51. In contrast, MG132-mediated proteasome inhibition, which induces rigorous autophagy, promotes p62 degradation but accumulation of the DNA repair proteins CHK1 and RAD51. However, pretreatment with an autophagy inhibitor offsets the effects of MG132 on CHK1 and RAD51 levels. These findings imply that p62 accumulation in the nucleus in response to autophagy inhibition promotes proteasome-mediated CHK1 and RAD51 protein instability. This claim is further supported by the findings that transient expression of a p62 mutant, which is constitutively localized in the nucleus, in B cell lines with low endogenous p62 levels recaptures the effects of autophagy inhibition on CHK1 and RAD51 protein stability. These results indicate that proteasomal degradation of RAD51 and CHK1 is dependent on p62 accumulation in the nucleus. However, small hairpin RNA (shRNA)-mediated p62 depletion in EBV-transformed lymphoblastic cell lines (LCLs) had no apparent effects on the protein levels of CHK1 and RAD51, likely due to the constitutive localization of p62 in the cytoplasm and incomplete knockdown is insufficient to manifest its nuclear effects on these proteins. Rather, shRNA-mediated p62 depletion in EBV-transformed LCLs results in significant increases of endogenous RNF168-γH2AX damage foci and chromatin ubiquitination, indicative of activation of RNF168-mediated DNA repair mechanisms. Our results have unveiled a pivotal role for p62-mediated selective autophagy that governs DDR in the setting of oncogenic virus latent infection, and provide a novel insight into virus-mediated oncogenesis.
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Affiliation(s)
- Ling Wang
- Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
- Center of Excellence for Inflammation, Infectious Diseases and Immunity, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
| | - Mary E. A. Howell
- Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
| | - Ayrianna Sparks-Wallace
- Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
| | - Caroline Hawkins
- Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
| | - Camri A. Nicksic
- Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
| | - Carissa Kohne
- Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
| | - Kenton H. Hall
- Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
| | - Jonathan P. Moorman
- Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
- Center of Excellence for Inflammation, Infectious Diseases and Immunity, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
- The HCV/HIV Program, James H Quillen VA Medical Center, Johnson City, TN, United States of America
| | - Zhi Q. Yao
- Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
- Center of Excellence for Inflammation, Infectious Diseases and Immunity, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
- The HCV/HIV Program, James H Quillen VA Medical Center, Johnson City, TN, United States of America
| | - Shunbin Ning
- Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
- Center of Excellence for Inflammation, Infectious Diseases and Immunity, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
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209
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Lin HY, Wang JJ, Feng MG, Ying SH. Autophagy-related gene ATG7 participates in the asexual development, stress response and virulence of filamentous insect pathogenic fungus Beauveria bassiana. Curr Genet 2019; 65:1015-1024. [PMID: 30879087 DOI: 10.1007/s00294-019-00955-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/06/2019] [Accepted: 03/12/2019] [Indexed: 12/21/2022]
Abstract
Autophagy is a sophisticated mechanism for maintaining cellular homeostasis, in which E1-like enzyme (ATG7) controls the activation of ubiquitin-like conjugation system in the autophagy pathway. In the insect pathogenic fungus Beauveria bassiana, a yeast ortholog of ATG7 was identified and functionally analyzed. Ablation of BbATG7 gene blocks the autophagic process under starvation stress. The mutant ΔBbATG7 exhibited impaired growth on the media with chitin as single nitrogen source. On rich media, gene loss did not cause notable effect on vegetative growth, but resulted in a considerable reduction in conidiation (71.6%) and blastospore yield (61.1%) in the mutant. In addition, the ΔBbATG7 mutant displayed increased sensitivity to stress caused by menadione and Congo red. The virulence of ΔBbATG7 mutant was significantly attenuated as indicated in topical and intrahemocoel injection assays. Our study indicates that BbATG7 contributes to B. bassiana virulence via regulating autophagy pathway and playing non-autophagic functions in the infection cycle.
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Affiliation(s)
- Hai-Yan Lin
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Jia-Jia Wang
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Ming-Guang Feng
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Sheng-Hua Ying
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China.
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210
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Aghaei M, Motallebnezhad M, Ghorghanlu S, Jabbari A, Enayati A, Rajaei M, Pourabouk M, Moradi A, Alizadeh AM, Khori V. Targeting autophagy in cardiac ischemia/reperfusion injury: A novel therapeutic strategy. J Cell Physiol 2019; 234:16768-16778. [PMID: 30807647 DOI: 10.1002/jcp.28345] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 01/17/2019] [Accepted: 01/22/2019] [Indexed: 12/31/2022]
Abstract
Acute myocardial infarction (AMI) is one of the leading causes of morbidity worldwide. Myocardial reperfusion is known as an effective therapeutic choice against AMI. However, reperfusion of blood flow induces ischemia/reperfusion (I/R) injury through different complex processes including ion accumulation, disruption of mitochondrial membrane potential, the formation of reactive oxygen species, and so forth. One of the processes that gets activated in response to I/R injury is autophagy. Indeed, autophagy acts as a "double-edged sword" in the pathology of myocardial I/R injury and there is a controversy about autophagy being beneficial or detrimental. On the basis of the autophagy effect and regulation on myocardial I/R injury, many studies targeted it as a therapeutic strategy. In this review, we discuss the role of autophagy in I/R injury and its targeting as a therapeutic strategy.
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Affiliation(s)
- Mehrdad Aghaei
- Rheumatology Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Morteza Motallebnezhad
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Immunology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.,Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
| | - Sajjad Ghorghanlu
- Ischemic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Ali Jabbari
- Ischemic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Ayesheh Enayati
- Ischemic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran.,Department of Pharmacognosy, Faculty of Pharmacy and Medicinal Plants Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Maryam Rajaei
- Ischemic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Mona Pourabouk
- Ischemic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Alireza Moradi
- Department of Physiology, Medical School, Ardabil University of Medical Sciences, Ardabil, Iran
| | | | - Vahid Khori
- Ischemic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
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211
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Schaaf MB, Houbaert D, Meçe O, Agostinis P. Autophagy in endothelial cells and tumor angiogenesis. Cell Death Differ 2019; 26:665-679. [PMID: 30692642 PMCID: PMC6460396 DOI: 10.1038/s41418-019-0287-8] [Citation(s) in RCA: 130] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/07/2019] [Accepted: 01/10/2019] [Indexed: 12/14/2022] Open
Abstract
In mammalian cells, autophagy is the major pathway for the degradation and recycling of obsolete and potentially noxious cytoplasmic materials, including proteins, lipids, and whole organelles, through the lysosomes. Autophagy maintains cellular and tissue homeostasis and provides a mechanism to adapt to extracellular cues and metabolic stressors. Emerging evidence unravels a critical function of autophagy in endothelial cells (ECs), the major components of the blood vasculature, which delivers nutrients and oxygen to the parenchymal tissue. EC-intrinsic autophagy modulates the response of ECs to various metabolic stressors and has a fundamental role in redox homeostasis and EC plasticity. In recent years moreover, genetic evidence suggests that autophagy regulates pathological angiogenesis, a hallmark of solid tumors. In the hypoxic, nutrient-deprived, and pro-angiogenic tumor microenvironment, heightened autophagy in the blood vessels is emerging as a critical mechanism enabling ECs to dynamically accommodate their higher bioenergetics demands to the extracellular environment and connect with other components of the tumor stroma through paracrine signaling. In this review, we provide an overview of the major cellular mechanisms regulated by autophagy in ECs and discuss their potential role in tumor angiogenesis, tumor growth, and response to anticancer therapy. Vascular homeostasis relies on the proper behavior of endothelial cells (ECs). Emerging evidence indicate a critical role of autophagy, a vesicular process for lysosomal degradation of cytoplasmic content, in EC biology. While EC-intrinsic autophagy promotes EC function and quiescent state through redox homeostasis and possibly metabolic control, a role for EC-associated autophagy in cancer seems more complex. ![]()
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Affiliation(s)
- Marco B Schaaf
- Cell Death Research & Therapy (CDRT) Laboratory, Department for Cellular and Molecular Medicine, KU Leuven University of Leuven, Leuven, Belgium
| | - Diede Houbaert
- Cell Death Research & Therapy (CDRT) Laboratory, Department for Cellular and Molecular Medicine, KU Leuven University of Leuven, Leuven, Belgium
| | - Odeta Meçe
- Cell Death Research & Therapy (CDRT) Laboratory, Department for Cellular and Molecular Medicine, KU Leuven University of Leuven, Leuven, Belgium
| | - Patrizia Agostinis
- Cell Death Research & Therapy (CDRT) Laboratory, Department for Cellular and Molecular Medicine, KU Leuven University of Leuven, Leuven, Belgium.
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212
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Mitter AL, Schlotterhose P, Krick R. Gyp1 has a dual function as Ypt1 GAP and interaction partner of Atg8 in selective autophagy. Autophagy 2019; 15:1031-1050. [PMID: 30686108 DOI: 10.1080/15548627.2019.1569929] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Macroautophagy/autophagy is a highly conserved intracellular vesicle transport pathway that prevents accumulation of harmful materials within cells. The dynamic assembly and disassembly of the different autophagic protein complexes at the so-called phagophore assembly site (PAS) is strictly regulated. Rab GTPases are major regulators of cellular vesicle trafficking, and the Rab GTPase Ypt1 and its GEF TRAPPIII have been implicated in autophagy. We show that Gyp1 acts as a Ypt1 GTPase-activating protein (GAP) for selective autophagic variants, such as the Cvt pathway or the selective autophagic degradation of mitochondria (mitophagy). Gyp1 regulates the dynamic disassembly of the conserved Ypt1-Atg1 complex. Thereby, Gyp1 sets the stage for efficient Atg14 recruitment, and facilitates the critical step from nucleation to elongation of the phagophore. In addition, we identified Gyp1 as a new Atg8-interacting motif (AIM)-dependent Atg8 interaction partner. The Gyp1 AIM is required for efficient formation of the cargo receptor-Atg8 complexes. Our findings elucidate the molecular mechanisms of complex disassembly during phagophore formation and suggest potential dual functions of GAPs in cellular vesicle trafficking. Abbreviations AIM, Atg8-interacting motif; Atg, autophagy related; Cvt, cytoplasm-to-vacuole targeting; GAP, GTPase-activating protein; GEF, guanine-nucleotide exchange factor; GFP, green fluorescent protein; log phase, logarithmic growth phase; NHD, N-terminal helical domain; PAS, phagophore assembly site; PE, phosphatidylethanolamine; PtdIns3P, phosphatidylinositol-3-phosphate; WT, wild-type.
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Affiliation(s)
- Anne Lisa Mitter
- a Department of Cellular Biochemistry, University Medicine , Georg-August University , Goettingen , Germany
| | - Petra Schlotterhose
- a Department of Cellular Biochemistry, University Medicine , Georg-August University , Goettingen , Germany
| | - Roswitha Krick
- a Department of Cellular Biochemistry, University Medicine , Georg-August University , Goettingen , Germany
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213
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PP2C phosphatases promote autophagy by dephosphorylation of the Atg1 complex. Proc Natl Acad Sci U S A 2019; 116:1613-1620. [PMID: 30655342 DOI: 10.1073/pnas.1817078116] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Macroautophagy is orchestrated by the Atg1-Atg13 complex in budding yeast. Under nutrient-rich conditions, Atg13 is maintained in a hyperphosphorylated state by the TORC1 kinase. After nutrient starvation, Atg13 is dephosphorylated, triggering Atg1 kinase activity and macroautophagy induction. The phosphatases that dephosphorylate Atg13 remain uncharacterized. Here, we show that two redundant PP2C phosphatases, Ptc2 and Ptc3, regulate macroautophagy by dephosphorylating Atg13 and Atg1. In the absence of these phosphatases, starvation-induced macroautophagy and the cytoplasm-to-vacuole targeting pathway are inhibited, and the recruitment of the essential autophagy machinery to the phagophore assembly site is impaired. Expressing a genomic ATG13 -8SA allele lacking key TORC1 phosphorylation sites partially bypasses the macroautophagy defect in ptc2Δ ptc3Δ strains. Moreover, Ptc2 and Ptc3 interact with the Atg1-Atg13 complex. Taken together, these results suggest that PP2C-type phosphatases promote macroautophagy by regulating the Atg1 complex.
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214
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Gonzalez Porras MA, Sieck GC, Mantilla CB. Impaired Autophagy in Motor Neurons: A Final Common Mechanism of Injury and Death. Physiology (Bethesda) 2019; 33:211-224. [PMID: 29638184 DOI: 10.1152/physiol.00008.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Autophagy is a cellular digestion process that contributes to cellular homeostasis and adaptation by the elimination of proteins and damaged organelles. Evidence suggests that dysregulation of autophagy plays a role in neurodegenerative diseases, including motor neuron disorders. Herein, we review emerging evidence indicating the roles of autophagy in physiological motor neuron processes and its function in specific compartments. Moreover, we discuss the involvement of autophagy in the pathogenesis of motor neuron diseases, including spinal cord injury and aging, and recent developments that offer promising therapeutic approaches to mitigate effects of dysregulated autophagy in health and disease.
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Affiliation(s)
| | - Gary C Sieck
- Department of Physiology & Biomedical Engineering, Mayo Clinic , Rochester, Minnesota.,Department of Anesthesiology and Perioperative Medicine, Mayo Clinic , Rochester, Minnesota
| | - Carlos B Mantilla
- Department of Physiology & Biomedical Engineering, Mayo Clinic , Rochester, Minnesota.,Department of Anesthesiology and Perioperative Medicine, Mayo Clinic , Rochester, Minnesota
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215
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Yang F, Kimberlin AN, Elowsky CG, Liu Y, Gonzalez-Solis A, Cahoon EB, Alfano JR. A Plant Immune Receptor Degraded by Selective Autophagy. MOLECULAR PLANT 2019; 12:113-123. [PMID: 30508598 DOI: 10.1016/j.molp.2018.11.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 10/16/2018] [Accepted: 11/22/2018] [Indexed: 05/21/2023]
Abstract
Plants recycle non-activated immune receptors to maintain a functional immune system. The Arabidopsis immune receptor kinase FLAGELLIN-SENSING 2 (FLS2) recognizes bacterial flagellin. However, the molecular mechanisms by which non-activated FLS2 and other non-activated plant PRRs are recycled remain not well understood. Here, we provide evidence showing that Arabidopsis orosomucoid (ORM) proteins, which have been known to be negative regulators of sphingolipid biosynthesis, act as selective autophagy receptors to mediate the degradation of FLS2. Arabidopsis plants overexpressing ORM1 or ORM2 have undetectable or greatly diminished FLS2 accumulation, nearly lack FLS2 signaling, and are more susceptible to the bacterial pathogen Pseudomonas syringae. On the other hand, ORM1/2 RNAi plants and orm1 or orm2 mutants generated by the CRISPR/Cas9-mediated gene editing have increased FLS2 accumulation and enhanced FLS2 signaling, and are more resistant to P. syringae. ORM proteins interact with FLS2 and the autophagy-related protein ATG8. Interestingly, overexpression of ORM1 or ORM2 in autophagy-defective mutants showed FLS2 abundance that is comparable to that in wild-type plants. Moreover, FLS2 levels were not decreased in Arabidopsis plants overexpressing ORM1/2 derivatives that do not interact with ATG8. Taken together, these results suggest that selective autophagy functions in maintaining the homeostasis of a plant immune receptor and that beyond sphingolipid metabolic regulation ORM proteins can also act as selective autophagy receptors.
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Affiliation(s)
- Fan Yang
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68588-0722, USA; Center for Plant Science Innovation, University of Nebraska, Lincoln, NE 68588-0660, USA
| | - Athen N Kimberlin
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE 68588-0660, USA; Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0664, USA
| | - Christian G Elowsky
- Center for Biotechnology, University of Nebraska, Lincoln, NE 68588-0665, USA
| | - Yunfeng Liu
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE 68588-0660, USA
| | - Ariadna Gonzalez-Solis
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE 68588-0660, USA; Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0664, USA
| | - Edgar B Cahoon
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE 68588-0660, USA; Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0664, USA.
| | - James R Alfano
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68588-0722, USA; Center for Plant Science Innovation, University of Nebraska, Lincoln, NE 68588-0660, USA.
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216
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Structural Basis of Autophagy Regulatory Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1206:287-326. [PMID: 31776992 DOI: 10.1007/978-981-15-0602-4_15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Autophagy is an evolutionarily conserved lysosome-dependent intracellular degradation process that is essential for the maintenance of cellular homeostasis and adaptation to cellular stresses in eukaryotic cells. The most well-characterized type of autophagy, the macroautophagy, involves the progressive sequestration of cytoplasmic components into dedicated double-membraned vesicles called autophagosomes, which ultimately fuse with lysosomes to initiate the autophagic degradation of the sequestered cargo. In the past decade, our understanding of the molecular mechanism of macroautophagy has significantly evolved, with particular contributions from the biochemical and structural characterizations of autophagy-related proteins. In this chapter, we focus on some autophagy regulatory proteins involved in the macroautophagy pathway, summarize their currently known structures, and discuss their relevant molecular mechanisms from a perspective of structural biology.
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217
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Wang R, Wang G. Protein Modification and Autophagy Activation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1206:237-259. [PMID: 31776989 DOI: 10.1007/978-981-15-0602-4_12] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Protein modification refers to the chemical modification of proteins after their biosynthesis, which is also called posttranslational modification (PTM). PTM causes changes in protein properties and functions. PTM includes an attachment of addition of functional groups, such as methylation, acetylation, glycosylation and phosphorylation; a covalent coupling of small peptides or proteins, such as ubiquitination and SUMOylation; or chemical changes in amino acids, such as citrullination (conversion of arginine to citrulline). Protein modification plays an important role in cellular processes. Since a protein can be modified in different ways, such as acetylation, methylation and phosphorylation, the functions of proteins are different under different modification states. Moreover, the same modification at different sites may have completely different effects on protein function. For example, phosphorylation at some sites in a protein may lead to a functional activation, while phosphorylation at other sites may cause an inhibition of the functions. Thus, different modifications, combinations and sites changes lead to different functional regulations of a protein, resulting in different effects in the cells. In autophagy, PTMs are widely involved in the regulation of autophagy, including ubiquitination, phosphorylation and acetylation. Ubiquitination is the covalent conjugation of ubiquitin to the substrates through a series of enzymes. Phosphorylation refers to an attachment of a phosphoryl group into a protein, primarily on serine, threonine and tyrosine, which is catalyzed by the kinases. Phosphorylation, a common modification, regulates protein function and localization. Phosphorylation in autophagy regulates the activity of autophagy-associated proteins and the initiation and progression of autophagy by regulating signaling pathways. Acetylation means the addition of acetyl groups onto lysine or N-terminal segment of target proteins through acetyltransferases. Acetylation and deacetylation are both involved in the regulation of autophagy initiation and selective autophagy by controlling the acetylation level of important proteins in the autophagy process. In this chapter, we will focus on the regulation of ubiquitination and phosphorylation in autophagy.
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Affiliation(s)
- Rui Wang
- Laboratory of Molecular Neuropathology, Jiangsu Key Laboratory of Neuropsychiatric Diseases & Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, China
| | - Guanghui Wang
- Laboratory of Molecular Neuropathology, Jiangsu Key Laboratory of Neuropsychiatric Diseases & Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, China.
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218
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Sánchez-Martín P, Saito T, Komatsu M. p62/SQSTM1: 'Jack of all trades' in health and cancer. FEBS J 2018; 286:8-23. [PMID: 30499183 PMCID: PMC7379270 DOI: 10.1111/febs.14712] [Citation(s) in RCA: 161] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/11/2018] [Accepted: 11/28/2018] [Indexed: 12/17/2022]
Abstract
p62 is a stress‐inducible protein able to change among binding partners, cellular localizations and form liquid droplet structures in a context‐dependent manner. This protein is mainly defined as a cargo receptor for selective autophagy, a process that allows the degradation of detrimental and unnecessary components through the lysosome. Besides this role, its ability to interact with multiple binding partners allows p62 to act as a main regulator of the activation of the Nrf2, mTORC1, and NF‐κB signaling pathways, linking p62 to the oxidative defense system, nutrient sensing, and inflammation, respectively. In the present review, we will present the molecular mechanisms behind the control p62 exerts over these pathways, their interconnection and how their deregulation contributes to cancer progression.
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Affiliation(s)
- Pablo Sánchez-Martín
- Department of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Japan
| | - Tetsuya Saito
- Department of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Japan
| | - Masaaki Komatsu
- Department of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Japan.,Department of Physiology, Juntendo University Graduate School of Medicine, Tokyo, Japan
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219
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Hill SM, Wrobel L, Rubinsztein DC. Post-translational modifications of Beclin 1 provide multiple strategies for autophagy regulation. Cell Death Differ 2018; 26:617-629. [PMID: 30546075 DOI: 10.1038/s41418-018-0254-9] [Citation(s) in RCA: 149] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/19/2018] [Accepted: 11/28/2018] [Indexed: 01/07/2023] Open
Abstract
Autophagy is a conserved intracellular degradation pathway essential for protein homeostasis, survival and development. Defects in autophagic pathways have been connected to a variety of human diseases, including cancer and neurodegeneration. In the process of macroautophagy, cytoplasmic cargo is enclosed in a double-membrane structure and fused to the lysosome to allow for digestion and recycling of material. Autophagosome formation is primed by the ULK complex, which enables the downstream production of PI(3)P, a key lipid signalling molecule, on the phagophore membrane. The PI(3)P is generated by the PI3 kinase (PI3K) complex, consisting of the core components VPS34, VPS15 and Beclin 1. Beclin 1 is a central player in autophagy and constitutes a molecular platform for the regulation of autophagosome formation and maturation. Post-translational modifications of Beclin 1 affect its stability, interactions and ability to regulate PI3K activity, providing the cell with a plethora of strategies to fine-tune the levels of autophagy. Being such an important regulator, Beclin 1 is a potential target for therapeutic intervention and interfering with the post-translational regulation of Beclin 1 could be one way of manipulating the levels of autophagy. In this review, we provide an overview of the known post-translational modifications of Beclin 1 that govern its role in autophagy and how these modifications are maintained by input from several upstream signalling pathways. ▓.
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Affiliation(s)
- Sandra M Hill
- Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Lidia Wrobel
- Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - David C Rubinsztein
- Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK. .,UK Dementia Research Institute, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.
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220
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Farré JC, Mahalingam SS, Proietto M, Subramani S. Peroxisome biogenesis, membrane contact sites, and quality control. EMBO Rep 2018; 20:embr.201846864. [PMID: 30530632 DOI: 10.15252/embr.201846864] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 10/08/2018] [Accepted: 11/16/2018] [Indexed: 12/19/2022] Open
Abstract
Peroxisomes are conserved organelles of eukaryotic cells with important roles in cellular metabolism, human health, redox homeostasis, as well as intracellular metabolite transfer and signaling. We review here the current status of the different co-existing modes of biogenesis of peroxisomal membrane proteins demonstrating the fascinating adaptability in their targeting and sorting pathways. While earlier studies focused on peroxisomes as autonomous organelles, the necessity of the ER and potentially even mitochondria as sources of peroxisomal membrane proteins and lipids has come to light in recent years. Additionally, the intimate physical juxtaposition of peroxisomes with other organelles has transitioned from being viewed as random encounters to a growing appreciation of the expanding roles of such inter-organellar membrane contact sites in metabolic and regulatory functions. Peroxisomal quality control mechanisms have also come of age with a variety of mechanisms operating both during biogenesis and in the cellular response to environmental cues.
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Affiliation(s)
- Jean-Claude Farré
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, CA, USA
| | - Shanmuga S Mahalingam
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, CA, USA
| | - Marco Proietto
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, CA, USA
| | - Suresh Subramani
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, CA, USA
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221
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McLoughlin F, Augustine RC, Marshall RS, Li F, Kirkpatrick LD, Otegui MS, Vierstra RD. Maize multi-omics reveal roles for autophagic recycling in proteome remodelling and lipid turnover. NATURE PLANTS 2018; 4:1056-1070. [PMID: 30478358 DOI: 10.1038/s41477-018-0299-2] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 10/10/2018] [Indexed: 05/21/2023]
Abstract
The turnover of cytoplasmic material by autophagic encapsulation and delivery to vacuoles is essential for recycling cellular constituents, especially under nutrient-limiting conditions. To determine how cells/tissues rely on autophagy, we applied in-depth multi-omic analyses to study maize (Zea mays) autophagy mutants grown under nitrogen-replete and -starvation conditions. Broad alterations in the leaf metabolome were evident in plants missing the core autophagy component ATG12, even in the absence of stress, particularly affecting products of lipid turnover and secondary metabolites, which were underpinned by substantial changes in the transcriptome and/or proteome. Cross-comparison of messenger RNA and protein abundances allowed for the identification of organelles, protein complexes and individual proteins targeted for selective autophagic clearance, and revealed several processes controlled by this catabolism. Collectively, we describe a facile multi-omic strategy to survey autophagic substrates, and show that autophagy has a remarkable influence in sculpting eukaryotic proteomes and membranes both before and during nutrient stress.
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Affiliation(s)
- Fionn McLoughlin
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Robert C Augustine
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Richard S Marshall
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Faqiang Li
- Department of Genetics, University of Wisconsin, Madison, WI, USA
- College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Liam D Kirkpatrick
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Marisa S Otegui
- Department of Genetics, University of Wisconsin, Madison, WI, USA
- Department of Botany, University of Wisconsin, Madison, WI, USA
- Laboratory of Cell and Molecular Biology, University of Wisconsin, Madison, WI, USA
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA.
- Department of Genetics, University of Wisconsin, Madison, WI, USA.
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222
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Trejo-Solís C, Serrano-Garcia N, Escamilla-Ramírez Á, Castillo-Rodríguez RA, Jimenez-Farfan D, Palencia G, Calvillo M, Alvarez-Lemus MA, Flores-Nájera A, Cruz-Salgado A, Sotelo J. Autophagic and Apoptotic Pathways as Targets for Chemotherapy in Glioblastoma. Int J Mol Sci 2018; 19:ijms19123773. [PMID: 30486451 PMCID: PMC6320836 DOI: 10.3390/ijms19123773] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 11/14/2018] [Accepted: 11/21/2018] [Indexed: 01/07/2023] Open
Abstract
Glioblastoma multiforme is the most malignant and aggressive type of brain tumor, with a mean life expectancy of less than 15 months. This is due in part to the high resistance to apoptosis and moderate resistant to autophagic cell death in glioblastoma cells, and to the poor therapeutic response to conventional therapies. Autophagic cell death represents an alternative mechanism to overcome the resistance of glioblastoma to pro-apoptosis-related therapies. Nevertheless, apoptosis induction plays a major conceptual role in several experimental studies to develop novel therapies against brain tumors. In this review, we outline the different components of the apoptotic and autophagic pathways and explore the mechanisms of resistance to these cell death pathways in glioblastoma cells. Finally, we discuss drugs with clinical and preclinical use that interfere with the mechanisms of survival, proliferation, angiogenesis, migration, invasion, and cell death of malignant cells, favoring the induction of apoptosis and autophagy, or the inhibition of the latter leading to cell death, as well as their therapeutic potential in glioma, and examine new perspectives in this promising research field.
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Affiliation(s)
- Cristina Trejo-Solís
- Departamento de Neuroinmunología, Laboratorio de Neurobiología Molecular y Celular, Laboratorio Experimental de Enfermedades Neurodegenerativas del Instituto Nacional de Neurología y Neurocirugía "Manuel Velasco Suárez", C.P. 14269 Ciudad de México, Mexico.
| | - Norma Serrano-Garcia
- Departamento de Neuroinmunología, Laboratorio de Neurobiología Molecular y Celular, Laboratorio Experimental de Enfermedades Neurodegenerativas del Instituto Nacional de Neurología y Neurocirugía "Manuel Velasco Suárez", C.P. 14269 Ciudad de México, Mexico.
| | - Ángel Escamilla-Ramírez
- Departamento de Neuroinmunología, Laboratorio de Neurobiología Molecular y Celular, Laboratorio Experimental de Enfermedades Neurodegenerativas del Instituto Nacional de Neurología y Neurocirugía "Manuel Velasco Suárez", C.P. 14269 Ciudad de México, Mexico.
- Hospital Regional de Alta Especialidad de Oaxaca, Secretaria de Salud, C.P. 71256 Oaxaca, Mexico.
| | | | - Dolores Jimenez-Farfan
- Laboratorio de Inmunología, División de Estudios de Posgrado e Investigación, Facultad de Odontología, Universidad Nacional Autónoma de México, C.P. 04510 Ciudad de México, Mexico.
| | - Guadalupe Palencia
- Departamento de Neuroinmunología, Laboratorio de Neurobiología Molecular y Celular, Laboratorio Experimental de Enfermedades Neurodegenerativas del Instituto Nacional de Neurología y Neurocirugía "Manuel Velasco Suárez", C.P. 14269 Ciudad de México, Mexico.
| | - Minerva Calvillo
- Departamento de Neuroinmunología, Laboratorio de Neurobiología Molecular y Celular, Laboratorio Experimental de Enfermedades Neurodegenerativas del Instituto Nacional de Neurología y Neurocirugía "Manuel Velasco Suárez", C.P. 14269 Ciudad de México, Mexico.
| | - Mayra A Alvarez-Lemus
- División Académica de Ingeniería y Arquitectura, Universidad Juárez Autónoma de Tabasco, C.P. 86040 Tabasco, Mexico.
| | - Athenea Flores-Nájera
- Departamento de Cirugía Experimental, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Secretaria de Salud, 14000 Ciudad de México, Mexico.
| | - Arturo Cruz-Salgado
- Departamento de Neuroinmunología, Laboratorio de Neurobiología Molecular y Celular, Laboratorio Experimental de Enfermedades Neurodegenerativas del Instituto Nacional de Neurología y Neurocirugía "Manuel Velasco Suárez", C.P. 14269 Ciudad de México, Mexico.
| | - Julio Sotelo
- Departamento de Neuroinmunología, Laboratorio de Neurobiología Molecular y Celular, Laboratorio Experimental de Enfermedades Neurodegenerativas del Instituto Nacional de Neurología y Neurocirugía "Manuel Velasco Suárez", C.P. 14269 Ciudad de México, Mexico.
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223
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Wang Q, Liu H, Xu H, Hei R, Zhang S, Jiang C, Xu JR. Independent losses and duplications of autophagy-related genes in fungal tree of life. Environ Microbiol 2018; 21:226-243. [DOI: 10.1111/1462-2920.14451] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/16/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Qinhu Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection; Northwest A&F University; Yangling Shaanxi 712100 China
| | - Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection; Northwest A&F University; Yangling Shaanxi 712100 China
| | - Huaijian Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection; Northwest A&F University; Yangling Shaanxi 712100 China
| | - Ruonan Hei
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection; Northwest A&F University; Yangling Shaanxi 712100 China
| | - Shijie Zhang
- School of Life Sciences; Zhengzhou University; Zhengzhou Henan 450001 China
| | - Cong Jiang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection; Northwest A&F University; Yangling Shaanxi 712100 China
| | - Jin-Rong Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection; Northwest A&F University; Yangling Shaanxi 712100 China
- Department of Botany and Plant Pathology; Purdue University; West Lafayette IN 47907 USA
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224
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Ying SH, Feng MG. Insight into vital role of autophagy in sustaining biological control potential of fungal pathogens against pest insects and nematodes. Virulence 2018; 10:429-437. [PMID: 30257619 PMCID: PMC6550541 DOI: 10.1080/21505594.2018.1518089] [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: 12/15/2022] Open
Abstract
Autophagy is a conserved self-degradation mechanism that governs a large array of cellular processes in filamentous fungi. Filamentous insect and nematode mycopthogens function in the natural control of host populations and have been widely applied for biological control of insect and nematode pests. Entomopathogenic and nematophagous fungi have conserved “core” autophagy machineries that are analogous to those found in yeast but also feature several proteins involved in specific aspects of the autophagic pathways. Here, we review the functions of autophagy in protecting fungal cells from starvation and stress cues and sustaining cell differentiation, asexual development and virulence. An emphasis is placed upon the regulatory mechanisms involved in autophagic and non-autophagic roles of some autophagy-related genes. Methods used for monitoring conserved or specific autophagic events in fungal pathogens are also discussed.
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Affiliation(s)
- Sheng-Hua Ying
- a Institute of Microbiology, College of Life Sciences , Zhejiang University , Hangzhou , China
| | - Ming-Guang Feng
- a Institute of Microbiology, College of Life Sciences , Zhejiang University , Hangzhou , China
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225
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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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226
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Filippakis H, Belaid A, Siroky B, Wu C, Alesi N, Hougard T, Nijmeh J, Lam HC, Henske EP. Vps34-mediated macropinocytosis in Tuberous Sclerosis Complex 2-deficient cells supports tumorigenesis. Sci Rep 2018; 8:14161. [PMID: 30242175 PMCID: PMC6155086 DOI: 10.1038/s41598-018-32256-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 09/03/2018] [Indexed: 01/04/2023] Open
Abstract
Tuberous Sclerosis Complex (TSC), a rare genetic disorder with mechanistic target of rapamycin complex 1 (mTORC1) hyperactivation, is characterized by multi-organ hamartomatous benign tumors including brain, skin, kidney, and lung (Lymphangioleiomyomatosis). mTORC1 hyperactivation drives metabolic reprogramming including glucose and glutamine utilization, protein, nucleic acid and lipid synthesis. To investigate the mechanisms of exogenous nutrients uptake in Tsc2-deficient cells, we measured dextran uptake, a polysaccharide internalized via macropinocytosis. Tsc2-deficient cells showed a striking increase in dextran uptake (3-fold, p < 0.0001) relative to Tsc2-expressing cells, which was decreased (3-fold, p < 0.0001) with mTOR inhibitor, Torin1. Pharmacologic and genetic inhibition of the lipid kinase Vps34 markedly abrogated uptake of Dextran in Tsc2-deficient cells. Macropinocytosis was further increased in Tsc2-deficient cells that lack autophagic mechanisms, suggesting that autophagy inhibition leads to dependence on exogenous nutrient uptake in Tsc2-deficient cells. Treatment with a macropinocytosis inhibitor, ethylisopropylamiloride (EIPA), resulted in selective growth inhibition of Atg5-deficient, Tsc2-deficient cells (50%, p < 0.0001). Genetic inhibition of autophagy (Atg5−/− MEFs) sensitized cells with Tsc2 downregulation to the Vps34 inhibitor, SAR405, resulting in growth inhibition (75%, p < 0.0001). Finally, genetic downregulation of Vps34 inhibited tumor growth and increased tumor latency in an in vivo xenograft model of TSC. Our findings show that macropinocytosis is upregulated with Tsc2-deficiency via a Vps34-dependent mechanism to support their anabolic state. The dependence of Tsc2-deficient cells on exogenous nutrients may provide novel approaches for the treatment of TSC.
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Affiliation(s)
- Harilaos Filippakis
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
| | - Amine Belaid
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Brian Siroky
- Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Constance Wu
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Nicola Alesi
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Thomas Hougard
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Julie Nijmeh
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Hilaire C Lam
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Elizabeth P Henske
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
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227
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Daskalaki I, Gkikas I, Tavernarakis N. Hypoxia and Selective Autophagy in Cancer Development and Therapy. Front Cell Dev Biol 2018; 6:104. [PMID: 30250843 PMCID: PMC6139351 DOI: 10.3389/fcell.2018.00104] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/13/2018] [Indexed: 01/07/2023] Open
Abstract
Low oxygen availability, a condition known as hypoxia, is a common feature of various pathologies including stroke, ischemic heart disease, and cancer. Hypoxia adaptation requires coordination of intricate pathways and mechanisms such as hypoxia-inducible factors (HIFs), the unfolded protein response (UPR), mTOR, and autophagy. Recently, great effort has been invested toward elucidating the interplay between hypoxia-induced autophagy and cancer cell metabolism. Although novel types of selective autophagy have been identified, including mitophagy, pexophagy, lipophagy, ERphagy and nucleophagy among others, their potential interface with hypoxia response mechanisms remains poorly understood. Autophagy activation facilitates the removal of damaged cellular compartments and recycles components, thus promoting cell survival. Importantly, tumor cells rely on autophagy to support self-proliferation and metastasis; characteristics related to poor disease prognosis. Therefore, a deeper understanding of the molecular crosstalk between hypoxia response mechanisms and autophagy could provide important insights with relevance to cancer and hypoxia-related pathologies. Here, we survey recent findings implicating selective autophagy in hypoxic responses, and discuss emerging links between these pathways and cancer pathophysiology.
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Affiliation(s)
- Ioanna Daskalaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
- Department of Biology, University of Crete, Heraklion, Greece
| | - Ilias Gkikas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
- Department of Biology, University of Crete, Heraklion, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
- Department of Basic Sciences, Medical School, University of Crete, Heraklion, Greece
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228
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Coordinate regulation of mutant NPC1 degradation by selective ER autophagy and MARCH6-dependent ERAD. Nat Commun 2018; 9:3671. [PMID: 30202070 PMCID: PMC6131187 DOI: 10.1038/s41467-018-06115-2] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 07/26/2018] [Indexed: 12/30/2022] Open
Abstract
Niemann–Pick type C disease is a fatal, progressive neurodegenerative disorder caused by loss-of-function mutations in NPC1, a multipass transmembrane glycoprotein essential for intracellular lipid trafficking. We sought to define the cellular machinery controlling degradation of the most common disease-causing mutant, I1061T NPC1. We show that this mutant is degraded, in part, by the proteasome following MARCH6-dependent ERAD. Unexpectedly, we demonstrate that I1061T NPC1 is also degraded by a recently described autophagic pathway called selective ER autophagy (ER-phagy). We establish the importance of ER-phagy both in vitro and in vivo, and identify I1061T as a misfolded endogenous substrate for this FAM134B-dependent process. Subcellular fractionation of I1061T Npc1 mouse tissues and analysis of human samples show alterations of key components of ER-phagy, including FAM134B. Our data establish that I1061T NPC1 is recognized in the ER and degraded by two different pathways that function in a complementary fashion to regulate protein turnover. Niemann-Pick type C1 disease is most commonly caused by the allele NPC1 I1061T, which is misfolded in the ER and rapidly degraded by the ubiquitin proteasome system. Here the authors show that the I1061T mutant is also degraded by ER-phagy.
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229
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Yang S, He J, Li X, Liu H, Zhao J, Liu M. Hydrogen attenuated oxidized low-density lipoprotein-induced inflammation through the stimulation of autophagy via sirtuin 1. Exp Ther Med 2018; 16:4042-4048. [PMID: 30344682 PMCID: PMC6176137 DOI: 10.3892/etm.2018.6691] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 07/06/2018] [Indexed: 12/14/2022] Open
Abstract
Chronic inflammation is a central pathogenic mechanism underlying the induction and progression of atherosclerosis (AS). Hydrogen has been demonstrated to serve a protective role in diverse models of disease. However, the potential effects and mechanism of hydrogen with respect to ox-LDL-induced inflammation have not yet been completely elucidated. In the present study, various concentrations (0, 50 and 100 mg/l) of oxidized low-density lipoprotein (ox-LDL) were used to treat RAW264.7 cells. A Cell Counting kit-8 assay was used to determine cell viability and western blot analysis was performed to determine the expression of proteins that are involved in autophagy. The expression of inflammatory cytokines in ox-LDL-treated macrophages was detected using ELISA. Small interfering (si)RNA against sirtuin 1 (SIRT1) was employed to investigate the mechanism underlying hydrogen-activated autophagy. The results indicated that ox-LDL stimulation promoted inflammatory cytokine expression and impaired autophagic flux in RAW264.7 cells. Furthermore, hydrogen inhibited ox-LDL-induced inflammatory cytokine expression by upregulating autophagic flux. SIRT1 mediated the upregulation of autophagic flux via hydrogen in ox-LDL-treated macrophages. To conclude, the present study provided novel insights into the role of defective autophagy in the pathogenesis of AS and identified autophagy to be a promising therapeutic target for the treatment of AS. Notably, hydrogen may represent a potential agent for the treatment of AS.
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Affiliation(s)
- Sen Yang
- Department of Vascular Surgery, Tianjin First Central Hospital, Tianjin 300192, P.R. China
| | - Ju He
- Department of Vascular Surgery, Tianjin First Central Hospital, Tianjin 300192, P.R. China
| | - Xiaofeng Li
- Department of Vascular Surgery, Tianjin First Central Hospital, Tianjin 300192, P.R. China
| | - Hui Liu
- Department of Vascular Surgery, Tianjin First Central Hospital, Tianjin 300192, P.R. China
| | - Jian Zhao
- Department of Vascular Surgery, Tianjin First Central Hospital, Tianjin 300192, P.R. China
| | - Mingming Liu
- Department of Vascular Surgery, Tianjin First Central Hospital, Tianjin 300192, P.R. China
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230
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Ding JL, Peng YJ, Chu XL, Feng MG, Ying SH. Autophagy-related gene BbATG11 is indispensable for pexophagy and mitophagy, and contributes to stress response, conidiation and virulence in the insect mycopathogen Beauveria bassiana. Environ Microbiol 2018; 20:3309-3324. [PMID: 30058280 DOI: 10.1111/1462-2920.14329] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 06/06/2018] [Accepted: 06/17/2018] [Indexed: 12/17/2022]
Abstract
Autophagy is a conserved degradation system in eukaryotic cells that includes non-selective and selective processes. Selective autophagy functions as a selective degradation mechanism for specific substrates in which autophagy-related protein 11 (ATG11) acts as an essential scaffold protein. In B. bassiana, there is a unique ATG11 family protein, which is designated as BbATG11. Disruption of BbATG11 resulted in significantly reduced conidial germination under starvation stress. The mutant ΔBbATG11 displayed enhanced sensitivity to oxidative stress and impaired asexual reproduction. The conidial yield was reduced by approximately 75%, and this defective phenotype could be repressed by increasing exogenous nutrients. The virulence of the ΔBbATG11 mutant strain was significantly impaired as indicated in topical and intra-hemocoel injection bioassays, with a greater reduction in topical infection. Notably, BbATG11 was involved in pexophagy and mitophagy, but these two autophagic processes appeared in different fungal physiological aspects. Both pexophagy and mitophagy were associated with nutrient shift, starvation stress and growth in the host hemocoel, but only pexophagy appeared in both oxidation-stressed cells and aerial mycelia. This study highlights that BbATG11 mediates pexophagy and mitophagy in B. bassiana and links selective autophagy to the fungal stress response, conidiation and virulence.
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Affiliation(s)
- Jin-Li Ding
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Yue-Jin Peng
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Xin-Ling Chu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Ming-Guang Feng
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Sheng-Hua Ying
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
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231
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Hu S, Wang Y, Gong Y, Liu J, Li Y, Pan L. Mechanistic Insights into Recognitions of Ubiquitin and Myosin VI by Autophagy Receptor TAX1BP1. J Mol Biol 2018; 430:3283-3296. [DOI: 10.1016/j.jmb.2018.06.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/01/2018] [Accepted: 06/18/2018] [Indexed: 12/29/2022]
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232
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Ma M, Kumar S, Purushothaman L, Babst M, Ungermann C, Chi RJ, Burd CG. Lipid trafficking by yeast Snx4 family SNX-BAR proteins promotes autophagy and vacuole membrane fusion. Mol Biol Cell 2018; 29:2190-2200. [PMID: 29949447 PMCID: PMC6249802 DOI: 10.1091/mbc.e17-12-0743] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 05/30/2018] [Accepted: 06/22/2018] [Indexed: 12/11/2022] Open
Abstract
Cargo-selective and nonselective autophagy pathways employ a common core autophagy machinery that directs biogenesis of an autophagosome that eventually fuses with the lysosome to mediate turnover of macromolecules. In yeast ( Saccharomyces cerevisiae) cells, several selective autophagy pathways fail in cells lacking the dimeric Snx4/Atg24 and Atg20/Snx42 sorting nexins containing a BAR domain (SNX-BARs), which function as coat proteins of endosome-derived retrograde transport carriers. It is unclear whether endosomal sorting by Snx4 proteins contributes to autophagy. Cells lacking Snx4 display a deficiency in starvation induced, nonselective autophagy that is severely exacerbated by ablation of mitochondrial phosphatidylethanolamine synthesis. Under these conditions, phosphatidylserine accumulates in the membranes of the endosome and vacuole, autophagy intermediates accumulate within the cytoplasm, and homotypic vacuole fusion is impaired. The Snx4-Atg20 dimer displays preference for binding and remodeling of phosphatidylserine-containing membrane in vitro, suggesting that Snx4-Atg20-coated carriers export phosphatidylserine-rich membrane from the endosome. Autophagy and vacuole fusion are restored by increasing phosphatidylethanolamine biosynthesis via alternative pathways, indicating that retrograde sorting by the Snx4 family sorting nexins maintains glycerophospholipid homeostasis required for autophagy and fusion competence of the vacuole membrane.
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Affiliation(s)
- Mengxiao Ma
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
| | - Santosh Kumar
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
| | - Latha Purushothaman
- Department of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Markus Babst
- Department of Biology, University of Utah, Salt Lake City, UT 84112
| | - Christian Ungermann
- Department of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Richard J. Chi
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223
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233
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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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234
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Hyttinen JMT, Viiri J, Kaarniranta K, Błasiak J. Mitochondrial quality control in AMD: does mitophagy play a pivotal role? Cell Mol Life Sci 2018; 75:2991-3008. [PMID: 29777261 PMCID: PMC11105454 DOI: 10.1007/s00018-018-2843-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/25/2018] [Accepted: 05/16/2018] [Indexed: 01/05/2023]
Abstract
Age-related macular degeneration (AMD) is the predominant cause of visual loss in old people in the developed world, whose incidence is increasing. This disease is caused by the decrease in macular function, due to the degeneration of retinal pigment epithelium (RPE) cells. The aged retina is characterised by increased levels of reactive oxygen species (ROS), impaired autophagy, and DNA damage that are linked to AMD pathogenesis. Mitophagy, a mitochondria-specific type of autophagy, is an essential part of mitochondrial quality control, the collective mechanism responsible for this organelle's homeostasis. The abundance of ROS, DNA damage, and the excessive energy consumption in the ageing retina all contribute to the degeneration of RPE cells and their mitochondria. We discuss the role of mitophagy in the cell and argue that its impairment may play a role in AMD pathogenesis. Thus, mitophagy as a potential therapeutic target in AMD and other degenerative diseases is as well explored.
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Affiliation(s)
- Juha M T Hyttinen
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland.
| | - Johanna Viiri
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
| | - Kai Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
- Department of Ophthalmology, Kuopio University Hospital, P.O. Box 100, 70029 KYS, Kuopio, Finland
| | - Janusz Błasiak
- Department of Molecular Genetics, University of Łódź, Pomorska 141/143, 90-236, Łódź, Poland
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235
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The PP2A-like Protein Phosphatase Ppg1 and the Far Complex Cooperatively Counteract CK2-Mediated Phosphorylation of Atg32 to Inhibit Mitophagy. Cell Rep 2018; 23:3579-3590. [DOI: 10.1016/j.celrep.2018.05.064] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 05/07/2018] [Accepted: 05/17/2018] [Indexed: 12/13/2022] Open
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236
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Piekarski A, Nagarajan G, Ishola P, Flees J, Greene ES, Kuenzel WJ, Ohkubo T, Maier H, Bottje WG, Cline MA, Dridi S. AMP-Activated Protein Kinase Mediates the Effect of Leptin on Avian Autophagy in a Tissue-Specific Manner. Front Physiol 2018; 9:541. [PMID: 29867578 PMCID: PMC5963154 DOI: 10.3389/fphys.2018.00541] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 04/26/2018] [Indexed: 12/23/2022] Open
Abstract
Autophagy, a highly conserved intracellular self-digestion process, plays an integral role in maintaining cellular homeostasis. Although emerging evidence indicate that the endocrine system regulates autophagy in mammals, there is still a scarcity of information on autophagy in avian (non-mammalian) species. Here, we show that intracerebroventricular administration of leptin reduces feed intake, modulates the expression of feeding-related hypothalamic neuropeptides, activates leptin receptor and signal transducer and activator of transcription (Ob-Rb/STAT) pathway, and significantly increases the expression of autophagy-related proteins (Atg3, Atg5, Atg7, beclin1, and LC3B) in chicken hypothalamus, liver, and muscle. Similarly, leptin treatment activates Ob-Rb/STAT pathway and increased the expression of autophagy-related markers in chicken hypothalamic organotypic cultures, muscle (QM7) and hepatocyte (Sim-CEL) cell cultures as well as in Chinese Hamster Ovary (CHO-K1) cells-overexpressing chicken Ob-Rb and STAT3. To define the downstream mediator(s) of leptin's effects on autophagy, we determined the role of the master energy sensor AMP-activated protein kinase (AMPK). Leptin treatment significantly increased the phosphorylated levels of AMPKα1/2 at Thr172 site in chicken hypothalamus and liver, but not in muscle. Likewise, AMPKα1/2 was activated by leptin in chicken hypothalamic organotypic culture and Sim-CEL, but not in QM7 cells. Blocking AMPK activity by compound C reverses the autophagy-inducing effect of leptin. Together, these findings indicate that AMPK mediates the effect of leptin on chicken autophagy in a tissue-specific manner.
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Affiliation(s)
- Alissa Piekarski
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, United States
| | - Gurueswar Nagarajan
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, United States
| | - Peter Ishola
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, United States
| | - Joshua Flees
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, United States
| | - Elizabeth S. Greene
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, United States
| | - Wayne J. Kuenzel
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, United States
| | - Takeshi Ohkubo
- College of Agriculture, Ibaraki University, Ibaraki, Japan
| | - Helena Maier
- Nidovirus-Cell Interactions Group, The Pirbright Institute, Woking, United Kingdom
| | - Walter G. Bottje
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, United States
| | - Mark A. Cline
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA, United States
| | - Sami Dridi
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, United States
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237
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Abstract
Plants have evolved sophisticated mechanisms to recycle intracellular constituents, which are essential for developmental and metabolic transitions; for efficient nutrient reuse; and for the proper disposal of proteins, protein complexes, and even entire organelles that become obsolete or dysfunctional. One major route is autophagy, which employs specialized vesicles to encapsulate and deliver cytoplasmic material to the vacuole for breakdown. In the past decade, the mechanics of autophagy and the scores of components involved in autophagic vesicle assembly have been documented. Now emerging is the importance of dedicated receptors that help recruit appropriate cargo, which in many cases exploit ubiquitylation as a signal. Although operating at a low constitutive level in all plant cells, autophagy is upregulated during senescence and various environmental challenges and is essential for proper nutrient allocation. Its importance to plant metabolism and energy balance in particular places autophagy at the nexus of robust crop performance, especially under suboptimal conditions.
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Affiliation(s)
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130, USA;
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238
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Orsini M, Morceau F, Dicato M, Diederich M. Autophagy as a pharmacological target in hematopoiesis and hematological disorders. Biochem Pharmacol 2018; 152:347-361. [PMID: 29656115 DOI: 10.1016/j.bcp.2018.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 04/10/2018] [Indexed: 12/14/2022]
Abstract
Autophagy is involved in many cellular processes, including cell homeostasis, cell death/survival balance and differentiation. Autophagy is essential for hematopoietic stem cell survival, quiescence, activation and differentiation. The deregulation of this process is associated with numerous hematological disorders and pathologies, including cancers. Thus, the use of autophagy modulators to induce or inhibit autophagy emerges as a potential therapeutic approach for treating these diseases and could be particularly interesting for differentiation therapy of leukemia cells. This review presents therapeutic strategies and pharmacological agents in the context of hematological disorders. The pros and cons of autophagy modulators in therapy will also be discussed.
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Affiliation(s)
- Marion Orsini
- Laboratoire de Biologie Moléculaire et Cellulaire du Cancer, Hôpital Kirchberg, 9, rue Edward Steichen, L-2540 Luxembourg, Luxembourg
| | - Franck Morceau
- Laboratoire de Biologie Moléculaire et Cellulaire du Cancer, Hôpital Kirchberg, 9, rue Edward Steichen, L-2540 Luxembourg, Luxembourg
| | - Mario Dicato
- Laboratoire de Biologie Moléculaire et Cellulaire du Cancer, Hôpital Kirchberg, 9, rue Edward Steichen, L-2540 Luxembourg, Luxembourg
| | - Marc Diederich
- College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.
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239
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Avin-Wittenberg T, Baluška F, Bozhkov PV, Elander PH, Fernie AR, Galili G, Hassan A, Hofius D, Isono E, Le Bars R, Masclaux-Daubresse C, Minina EA, Peled-Zehavi H, Coll NS, Sandalio LM, Satiat-Jeunemaitre B, Sirko A, Testillano PS, Batoko H. Autophagy-related approaches for improving nutrient use efficiency and crop yield protection. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:1335-1353. [PMID: 29474677 DOI: 10.1093/jxb/ery069] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 02/16/2018] [Indexed: 05/18/2023]
Abstract
Autophagy is a eukaryotic catabolic pathway essential for growth and development. In plants, it is activated in response to environmental cues or developmental stimuli. However, in contrast to other eukaryotic systems, we know relatively little regarding the molecular players involved in autophagy and the regulation of this complex pathway. In the framework of the COST (European Cooperation in Science and Technology) action TRANSAUTOPHAGY (2016-2020), we decided to review our current knowledge of autophagy responses in higher plants, with emphasis on knowledge gaps. We also assess here the potential of translating the acquired knowledge to improve crop plant growth and development in a context of growing social and environmental challenges for agriculture in the near future.
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Affiliation(s)
- Tamar Avin-Wittenberg
- Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Frantisek Baluška
- Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee, Bonn, Germany
| | - Peter V Bozhkov
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Pernilla H Elander
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Alisdair R Fernie
- Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg, Potsdam-Golm, Germany
| | - Gad Galili
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot Israel
| | - Ammar Hassan
- Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee, Bonn, Germany
| | - Daniel Hofius
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center of Plant Biology, Uppsala, Sweden
| | - Erika Isono
- Department of Biology, University of Konstanz, Universitätsstrasse, Konstanz, Germany
| | - Romain Le Bars
- Cell Biology Pôle Imagerie-Gif, Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Céline Masclaux-Daubresse
- INRA-AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, Versailles, France
| | - Elena A Minina
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Hadas Peled-Zehavi
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot Israel
| | - Núria S Coll
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra-Cerdanyola del Valles, Catalonia, Spain
| | - Luisa M Sandalio
- Departmento de Bioquímica, Biología Celular y Molecular de Plantas Experimental del Zaidín, CSIC, Granada, Spain
| | - Béatrice Satiat-Jeunemaitre
- Cell Biology Pôle Imagerie-Gif, Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Agnieszka Sirko
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, ul. Pawinskiego, Warsaw, Poland
| | - Pilar S Testillano
- Pollen Biotechnology of Crop Plants group, Centro de Investigaciones Biológicas, Biological Research Centre (CIB), CSIC, Ramiro de Maeztu, Madrid, Spain
| | - Henri Batoko
- Université Catholique de Louvain, Institute of Life Sciences, Croix du Sud, Louvain-la-Neuve, Belgium
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240
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Abstract
Metabolic changes are hallmarks of aging and genetic and pharmacologic alterations of relevant pathways can extend life span. In this review, we will outline how cellular biochemistry and energy homeostasis change during aging. We will highlight protein quality control, mitochondria, epigenetics, nutrient-sensing pathways, as well as the interplay between these systems with respect to their impact on cellular health.
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Affiliation(s)
- Andre Catic
- Huffington Center on Aging, Stem Cells and Regenerative Medicine Center, Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, United States.
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241
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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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242
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Fukuda T, Kanki T. Mechanisms and Physiological Roles of Mitophagy in Yeast. Mol Cells 2018; 41:35-44. [PMID: 29370687 PMCID: PMC5792711 DOI: 10.14348/molcells.2018.2214] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/08/2017] [Accepted: 12/05/2017] [Indexed: 12/20/2022] Open
Abstract
Mitochondria are responsible for supplying of most of the cell's energy via oxidative phosphorylation. However, mitochondria also can be deleterious for a cell because they are the primary source of reactive oxygen species, which are generated as a byproduct of respiration. Accumulation of mitochondrial and cellular oxidative damage leads to diverse pathologies. Thus, it is important to maintain a population of healthy and functional mitochondria for normal cellular metabolism. Eukaryotes have developed defense mechanisms to cope with aberrant mitochondria. Mitochondria autophagy (known as mitophagy) is thought to be one such process that selectively sequesters dysfunctional or excess mitochondria within double-membrane autophagosomes and carries them into lysosomes/vacuoles for degradation. The power of genetics and conservation of fundamental cellular processes among eukaryotes make yeast an excellent model for understanding the general mechanisms, regulation, and function of mitophagy. In budding yeast, a mitochondrial surface protein, Atg32, serves as a mitochondrial receptor for selective autophagy that interacts with Atg11, an adaptor protein for selective types of autophagy, and Atg8, a ubiquitin-like protein localized to the isolation membrane. Atg32 is regulated transcriptionally and post-translationally to control mitophagy. Moreover, because Atg32 is a mitophagy-specific protein, analysis of its deficient mutant enables investigation of the physiological roles of mitophagy. Here, we review recent progress in the understanding of the molecular mechanisms and functional importance of mitophagy in yeast at multiple levels.
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Affiliation(s)
- Tomoyuki Fukuda
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510,
Japan
| | - Tomotake Kanki
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510,
Japan
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243
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Zientara-Rytter K, Ozeki K, Nazarko TY, Subramani S. Pex3 and Atg37 compete to regulate the interaction between the pexophagy receptor, Atg30, and the Hrr25 kinase. Autophagy 2018; 14:368-384. [PMID: 29260977 DOI: 10.1080/15548627.2017.1413521] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Macroautophagy/autophagy is a highly conserved process in which subcellular components destined for degradation are sequestered within autophagosomes. The selectivity of autophagy is determined by autophagy receptors, such as Pichia pastoris Atg30 (autophagy-related 30), which controls the selective degradation of peroxisomes (pexophagy) through the assembly of a receptor-protein complex (RPC). Previously, we proved that the peroxisomal acyl-CoA-binding protein, Atg37, and the highly conserved peroxin, Pex3, are required for RPC formation and efficient pexophagy. Here, we describe how Atg37 and Pex3 regulate the assembly and activation of the pexophagic RPC. We demonstrate that Atg30 requires both Atg37 and Pex3 to recruit Atg8 and Atg11 to the pexophagic RPC, because Atg37 depends on Pex3 for its localization at the peroxisomal membrane. We establish that due to close proximity of Atg37- and Pex3-binding sites in the middle domain of Atg30, the binding of these proteins to Atg30 is mutually exclusive within this region. We also show that direct binding of Pex3 and Atg37 to Atg30 regulates its phosphorylation by the Hrr25 kinase, negatively and positively, respectively. Based on these results we present a model that clarifies the assembly and activation of the pexophagic RPC through the phosphoregulation of Atg30.
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Affiliation(s)
- Katarzyna Zientara-Rytter
- a Section of Molecular Biology, Division of Biological Sciences , University California , San Diego , CA 92093-0322 , USA
| | - Katharine Ozeki
- a Section of Molecular Biology, Division of Biological Sciences , University California , San Diego , CA 92093-0322 , USA
| | - Taras Y Nazarko
- a Section of Molecular Biology, Division of Biological Sciences , University California , San Diego , CA 92093-0322 , USA
| | - Suresh Subramani
- a Section of Molecular Biology, Division of Biological Sciences , University California , San Diego , CA 92093-0322 , USA
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244
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Delorme-Axford E, Klionsky DJ. Transcriptional and post-transcriptional regulation of autophagy in the yeast Saccharomyces cerevisiae. J Biol Chem 2018; 293:5396-5403. [PMID: 29371397 DOI: 10.1074/jbc.r117.804641] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Autophagy is a highly conserved catabolic pathway that is vital for development, cell survival, and the degradation of dysfunctional organelles and potentially toxic aggregates. Dysregulation of autophagy is associated with cancer, neurodegeneration, and lysosomal storage diseases. Accordingly, autophagy is precisely regulated at multiple levels (transcriptional, post-transcriptional, translational, and post-translational) to prevent aberrant activity. Various model organisms are used to study autophagy, but the baker's yeast Saccharomyces cerevisiae continues to be advantageous for genetic and biochemical analysis of non-selective and selective autophagy. In this Minireview, we focus on the cellular mechanisms that regulate autophagy transcriptionally and post-transcriptionally in S. cerevisiae.
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Affiliation(s)
| | - Daniel J Klionsky
- From the Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109
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245
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Crosstalk of Autophagy and the Secretory Pathway and Its Role in Diseases. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 337:153-184. [DOI: 10.1016/bs.ircmb.2017.12.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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246
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Smith MD, Harley ME, Kemp AJ, Wills J, Lee M, Arends M, von Kriegsheim A, Behrends C, Wilkinson S. CCPG1 Is a Non-canonical Autophagy Cargo Receptor Essential for ER-Phagy and Pancreatic ER Proteostasis. Dev Cell 2017; 44:217-232.e11. [PMID: 29290589 PMCID: PMC5791736 DOI: 10.1016/j.devcel.2017.11.024] [Citation(s) in RCA: 296] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 11/02/2017] [Accepted: 11/29/2017] [Indexed: 12/11/2022]
Abstract
Mechanisms of selective autophagy of the ER, known as ER-phagy, require molecular delineation, particularly in vivo. It is unclear how these events control ER proteostasis and cellular health. Here, we identify cell-cycle progression gene 1 (CCPG1), an ER-resident protein with no known physiological role, as a non-canonical cargo receptor that directly binds to core autophagy proteins via an LIR motif to mammalian ATG8 proteins and, independently and via a discrete motif, to FIP200. These interactions facilitate ER-phagy. The CCPG1 gene is inducible by the unfolded protein response and thus directly links ER stress to ER-phagy. In vivo, CCPG1 protects against ER luminal protein aggregation and consequent unfolded protein response hyperactivation and tissue injury of the exocrine pancreas. Thus, via identification of this autophagy protein, we describe an unexpected molecular mechanism of ER-phagy and provide evidence that this may be physiologically relevant in ER luminal proteostasis. CCPG1 is an ER stress-inducible ER-phagy cargo receptor in mammals CCPG1 binds directly to ATG8 proteins and FIP200 via distinct peptide motifs CCPG1 lysosomal degradation and ER-phagy both require these interactions CCPG1 maintains normal ER luminal proteostasis in pancreatic acinar cells in vivo
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Affiliation(s)
- Matthew D Smith
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Margaret E Harley
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Alain J Kemp
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Jimi Wills
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Martin Lee
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Mark Arends
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Alex von Kriegsheim
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Christian Behrends
- Munich Cluster for Systems Neurology (SyNergy), Ludwig-Maximilians-University Munich, München, Germany
| | - Simon Wilkinson
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK.
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247
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Ranaghan MJ, Durney MA, Mesleh MF, McCarren PR, Garvie CW, Daniels DS, Carey KL, Skepner AP, Levine B, Perez JR. The Autophagy-Related Beclin-1 Protein Requires the Coiled-Coil and BARA Domains To Form a Homodimer with Submicromolar Affinity. Biochemistry 2017; 56:6639-6651. [PMID: 29185708 DOI: 10.1021/acs.biochem.7b00936] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Beclin-1 (BECN1) is an essential component of macroautophagy. This process is a highly conserved survival mechanism that recycles damaged cellular components or pathogens by encasing them in a bilayer vesicle that fuses with a lysosome to allow degradation of the vesicular contents. Mutations or altered expression profiles of BECN1 have been linked to various cancers and neurodegenerative diseases. Viruses, including HIV and herpes simplex virus 1 (HSV-1), are also known to specifically target BECN1 as a means of evading host defense mechanisms. Autophagy is regulated by the interaction between BECN1 and Bcl-2, a pro-survival protein in the apoptotic pathway that stabilizes the BECN1 homodimer. Disruption of the homodimer by phosphorylation or competitive binding promotes autophagy through an unknown mechanism. We report here the first recombinant synthesis (3-5 mg/L in an Escherichia coli culture) and characterization of full-length, human BECN1. Our analysis reveals that full-length BECN1 exists as a soluble homodimer (KD ∼ 0.45 μM) that interacts with Bcl-2 (KD = 4.3 ± 1.2 μM) and binds to lipid membranes. Dimerization is proposed to be mediated by a coiled-coil region of BECN1. A construct lacking the C-terminal BARA domain but including the coiled-coil region exhibits a homodimer KD 3.5-fold weaker than that of full-length BECN1, indicating that both the BARA domain and the coiled-coil region of BECN1 contribute to dimer formation. Using site-directed mutagenesis, we show that residues at the C-terminus of the coiled-coil region previously shown to interact with the BARA domain play a key role in dimerization and mutations weaken the interface by ∼5-fold.
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Affiliation(s)
- Matthew J Ranaghan
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard , 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Michael A Durney
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard , 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Michael F Mesleh
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard , 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Patrick R McCarren
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard , 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Colin W Garvie
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard , 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Douglas S Daniels
- Department of Chemistry, University of Dayton , 300 College Park, Dayton, Ohio 45469, United States
| | - Kimberly L Carey
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard , 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Adam P Skepner
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard , 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Beth Levine
- Center for Autophagy Research, Department of Internal Medicine, and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center , Dallas, Texas 75390, United States
| | - Jose R Perez
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard , 415 Main Street, Cambridge, Massachusetts 02142, United States
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248
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The mammalian ULK1 complex and autophagy initiation. Essays Biochem 2017; 61:585-596. [PMID: 29233870 PMCID: PMC5869855 DOI: 10.1042/ebc20170021] [Citation(s) in RCA: 458] [Impact Index Per Article: 65.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/03/2017] [Accepted: 11/06/2017] [Indexed: 02/07/2023]
Abstract
Autophagy is a vital lysosomal degradation pathway that serves as a quality control mechanism. It rids the cell of damaged, toxic or excess cellular components, which if left to persist could be detrimental to the cell. It also serves as a recycling pathway to maintain protein synthesis under starvation conditions. A key initial event in autophagy is formation of the autophagosome, a unique double-membrane organelle that engulfs the cytosolic cargo destined for degradation. This step is mediated by the serine/threonine protein kinase ULK1 (unc-51-like kinase 1), which functions in a complex with at least three protein partners: FIP200 (focal adhesion kinase family interacting protein of 200 kDa), ATG (autophagy-related protein) 13 (ATG13), and ATG101. In this artcile, we focus on the regulation of the ULK1 complex during autophagy initiation. The complex pattern of upstream pathways that converge on ULK1 suggests that this complex acts as a node, converting multiple signals into autophagosome formation. Here, we review our current understanding of this regulation and in turn discuss what happens downstream, once the ULK1 complex becomes activated.
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249
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Autophagy’s secret life: secretion instead of degradation. Essays Biochem 2017; 61:637-647. [DOI: 10.1042/ebc20170024] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 11/07/2017] [Accepted: 11/07/2017] [Indexed: 01/02/2023]
Abstract
Autophagy is conventionally described as a degradative, catabolic pathway and a tributary to the lysosomal system where the cytoplasmic material sequestered by autophagosomes gets degraded. However, autophagosomes or autophagosome-related organelles do not always follow this route. It has recently come to light that autophagy can terminate in cytosolic protein secretion or release of sequestered material from the cells, rather than in their degradation. In this review, we address this relatively new but growing aspect of autophagy as a complex pathway, which is far more versatile than originally anticipated.
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250
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Wang Z, Long QY, Chen L, Fan JD, Wang ZN, Li LY, Wu M, Chen X. Inhibition of H3K4 demethylation induces autophagy in cancer cell lines. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:2428-2437. [DOI: 10.1016/j.bbamcr.2017.08.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 07/29/2017] [Accepted: 08/07/2017] [Indexed: 12/20/2022]
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