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Autophagy Is Required for Maturation of Surfactant-Containing Lamellar Bodies in the Lung and Swim Bladder. Cell Rep 2020; 33:108477. [PMID: 33296658 DOI: 10.1016/j.celrep.2020.108477] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 10/20/2020] [Accepted: 11/11/2020] [Indexed: 01/02/2023] Open
Abstract
Autophagy is an intracellular degradation system, but its physiological functions in vertebrates are not yet fully understood. Here, we show that autophagy is required for inflation of air-filled organs: zebrafish swim bladder and mouse lung. In wild-type zebrafish swim bladder and mouse lung type II pulmonary epithelial cells, autophagosomes are formed and frequently fuse with lamellar bodies. The lamellar body is a lysosome-related organelle that stores a phospholipid-containing surfactant complex that lines the air-liquid interface and reduces surface tension. We find that autophagy is critical for maturation of the lamellar body. Accordingly, atg-deficient zebrafish fail to maintain their position in the water, and type-II-pneumocyte-specific Fip200-deficient mice show neonatal lethality with respiratory failure. Autophagy suppression does not affect synthesis of the surfactant phospholipid, suggesting that autophagy supplies lipids and membranes to lamellar bodies. These results demonstrate an evolutionarily conserved role of autophagy in lamellar body maturation.
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52
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Lim HJ. Autophagy in the uterine vessel microenvironment: Balancing vasoactive factors. Clin Exp Reprod Med 2020; 47:263-268. [PMID: 33227184 PMCID: PMC7711101 DOI: 10.5653/cerm.2020.04126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 10/14/2020] [Indexed: 11/23/2022] Open
Abstract
Autophagy, which has the literal meaning of self-eating, is a cellular catabolic process executed by arrays of conserved proteins in eukaryotes. Autophagy is dynamically ongoing at a basal level, presumably in all cells, and often carries out distinct functions depending on the cell type. Therefore, although a set of common genes and proteins is involved in this process, the outcome of autophagic activation or deficit requires scrutiny regarding how it affects cells in a specific pathophysiological context. The uterus is a complex organ that carries out multiple tasks under the influence of cyclic changes of ovarian steroid hormones. Several major populations of cells are present in the uterus, and the interactions among them drive complex physiological tasks. Mouse models with autophagic deficits in the uterus are very limited, but provide an initial glimpse at how autophagy plays a distinct role in different uterine tissues. Herein, we review recent research findings on the role of autophagy in the uterine mesenchyme in mouse models.
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53
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Autophagy and Redox Homeostasis in Parkinson's: A Crucial Balancing Act. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:8865611. [PMID: 33224433 PMCID: PMC7671810 DOI: 10.1155/2020/8865611] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/23/2020] [Accepted: 10/14/2020] [Indexed: 12/13/2022]
Abstract
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated primarily from endogenous biochemical reactions in mitochondria, endoplasmic reticulum (ER), and peroxisomes. Typically, ROS/RNS correlate with oxidative damage and cell death; however, free radicals are also crucial for normal cellular functions, including supporting neuronal homeostasis. ROS/RNS levels influence and are influenced by antioxidant systems, including the catabolic autophagy pathways. Autophagy is an intracellular lysosomal degradation process by which invasive, damaged, or redundant cytoplasmic components, including microorganisms and defunct organelles, are removed to maintain cellular homeostasis. This process is particularly important in neurons that are required to cope with prolonged and sustained operational stress. Consequently, autophagy is a primary line of protection against neurodegenerative diseases. Parkinson's is caused by the loss of midbrain dopaminergic neurons (mDANs), resulting in progressive disruption of the nigrostriatal pathway, leading to motor, behavioural, and cognitive impairments. Mitochondrial dysfunction, with associated increases in oxidative stress, and declining proteostasis control, are key contributors during mDAN demise in Parkinson's. In this review, we analyse the crosstalk between autophagy and redoxtasis, including the molecular mechanisms involved and the detrimental effect of an imbalance in the pathogenesis of Parkinson's.
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54
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Kaludercic N, Maiuri MC, Kaushik S, Fernández ÁF, de Bruijn J, Castoldi F, Chen Y, Ito J, Mukai R, Murakawa T, Nah J, Pietrocola F, Saito T, Sebti S, Semenzato M, Tsansizi L, Sciarretta S, Madrigal-Matute J. Comprehensive autophagy evaluation in cardiac disease models. Cardiovasc Res 2020; 116:483-504. [PMID: 31504266 PMCID: PMC7064050 DOI: 10.1093/cvr/cvz233] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 08/01/2019] [Accepted: 08/22/2019] [Indexed: 12/24/2022] Open
Abstract
Autophagy is a highly conserved recycling mechanism essential for maintaining cellular homeostasis. The pathophysiological role of autophagy has been explored since its discovery 50 years ago, but interest in autophagy has grown exponentially over the last years. Many researchers around the globe have found that autophagy is a critical pathway involved in the pathogenesis of cardiac diseases. Several groups have created novel and powerful tools for gaining deeper insights into the role of autophagy in the aetiology and development of pathologies affecting the heart. Here, we discuss how established and emerging methods to study autophagy can be used to unravel the precise function of this central recycling mechanism in the cardiac system.
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Affiliation(s)
- Nina Kaludercic
- Neuroscience Institute, Department of Biomedical Sciences, National Research Council of Italy (CNR), 35131, Padova, Italy
| | - Maria Chiara Maiuri
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Descartes, Université Paris Diderot, 75006, Paris, France
| | - Susmita Kaushik
- Department of Developmental and Molecular Biology, Institute for Aging Studies, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Álvaro F Fernández
- Center for Autophagy Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Jenny de Bruijn
- Department of Pathology, Cardiovascular Research Institute (CARIM), Maastricht University, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands; Institute of Molecular Cardiovascular Research (IMCAR), RWTH Aachen, University, Pauwelsstrase 30, 52074, Aachen, Germany
| | - Francesca Castoldi
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Descartes, Université Paris Diderot, 75006, Paris, France
| | - Yun Chen
- Departments of Medicine (Cardiology) and Cell Biology, Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Jumpei Ito
- The School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, London SE5 9NU, UK
| | - Risa Mukai
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, Newark, NY, USA
| | - Tomokazu Murakawa
- The School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, London SE5 9NU, UK
| | - Jihoon Nah
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, Newark, NY, USA
| | - Federico Pietrocola
- Cellular Plasticity and Disease Laboratory. Institute for Research in Biomedicine (IRB Barcelona), Barcelona; Institute of Science and Technology (BIST), Barcelona, Spain
| | - Toshiro Saito
- Department of Surgery and Clinical Science, Graduate School of Medicine, Yamaguchi University, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
| | - Salwa Sebti
- Center for Autophagy Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Martina Semenzato
- Department of Biology, University of Padua, Via U Bassi 58B, 35121, Padua, Italy.,Venetian Institute of Molecular Medicine, Via Orus 2, 35129, Padua, Italy
| | - Lorenza Tsansizi
- Department of Biology, University of Padua, Via U Bassi 58B, 35121, Padua, Italy.,Venetian Institute of Molecular Medicine, Via Orus 2, 35129, Padua, Italy
| | - Sebastiano Sciarretta
- Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, 04100, Latina, LT, Italy.,Department of AngioCardioNeurology, IRCCS Neuromed, 86077, Pozzilli, IS, Italy
| | - Julio Madrigal-Matute
- Department of Developmental and Molecular Biology, Institute for Aging Studies, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
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55
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Simpson JE, Gammoh N. The impact of autophagy during the development and survival of glioblastoma. Open Biol 2020; 10:200184. [PMID: 32873152 PMCID: PMC7536068 DOI: 10.1098/rsob.200184] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 07/30/2020] [Indexed: 02/07/2023] Open
Abstract
Glioblastoma is the most common and aggressive adult brain tumour, with poor median survival and limited treatment options. Following surgical resection and chemotherapy, recurrence of the disease is inevitable. Genomic studies have identified key drivers of glioblastoma development, including amplifications of receptor tyrosine kinases, which drive tumour growth. To improve treatment, it is crucial to understand survival response processes in glioblastoma that fuel cell proliferation and promote resistance to treatment. One such process is autophagy, a catabolic pathway that delivers cellular components sequestered into vesicles for lysosomal degradation. Autophagy plays an important role in maintaining cellular homeostasis and is upregulated during stress conditions, such as limited nutrient and oxygen availability, and in response to anti-cancer therapy. Autophagy can also regulate pro-growth signalling and metabolic rewiring of cancer cells in order to support tumour growth. In this review, we will discuss our current understanding of how autophagy is implicated in glioblastoma development and survival. When appropriate, we will refer to findings derived from the role of autophagy in other cancer models and predict the outcome of manipulating autophagy during glioblastoma treatment.
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Affiliation(s)
| | - Noor Gammoh
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road South, Edinburgh EH4 2XR, UK
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56
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Huang Q, Liu Y, Zhang S, Yap YT, Li W, Zhang D, Gardner A, Zhang L, Song S, Hess RA, Zhang Z. Autophagy core protein ATG5 is required for elongating spermatid development, sperm individualization and normal fertility in male mice. Autophagy 2020; 17:1753-1767. [PMID: 32677505 DOI: 10.1080/15548627.2020.1783822] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Spermiogenesis is the longest phase of spermatogenesis, with dramatic morphological changes and a final step of spermiation, which involves protein degradation and the removal of excess cytoplasm; therefore, we hypothesized that macroautophagy/autophagy might be involved in the process. To test this hypothesis, we examined the function of ATG5, a core autophagy protein in male germ cell development. Floxed Atg5 and Stra8- iCre mice were crossed to conditionally inactivate Atg5 in male germ cells. In Atg5flox/flox; Stra8- iCre mutant mice, testicular expression of the autophagosome marker LC3A/B-II was significantly reduced, and expression of autophagy receptor SQSTM1/p62 was significantly increased, indicating a decrease in testicular autophagy activity. The fertility of mutant mice was dramatically reduced with about 70% being infertile. Sperm counts and motility were also significantly reduced compared to controls. Histological examination of the mutant testes revealed numerous, large residual bodies in the lumen of stages after their normal resorption within the seminiferous epithelium. The cauda epididymal lumen was filled with sloughed germ cells, large cytoplasmic bodies, and spermatozoa with disorganized heads and tails. Examination of cauda epididymal sperm by electron microscopy revealed misshapen sperm heads, a discontinuous accessory structure in the mid-piece and abnormal acrosome formation and loss of sperm individualization. Immunofluorescence staining of epididymal sperm showed abnormal mitochondria and acrosome distribution in the mutant mice. ATG5 was shown to induce autophagy by mediating multiple signals to maintain normal developmental processes. Our study demonstrated ATG5 is essential for male fertility and is involved in various aspects of spermiogenesis.Abbreviations: AKAP4: a-kinase anchoring protein 4; ATG5: autophagy-related 5; ATG7: autophagy-related 7; ATG10: autophagy-related 10; ATG12: autophagy-related 12; cKO: conditional knockout; DDX4: DEAD-box helicase 4; MAP1LC3/LC3/tg8: microtubule-associated protein 1 light chain 3; PBS: phosphate-buffered saline; PIWIL2/MILI: piwi like RNA-mediated gene silencing 2; RT-PCR: reverse transcription-polymerase chain reaction; SQSTM1/p62: sequestosome 1; TBC: tubulobulbar complexes; WT: wild type.
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Affiliation(s)
- Qian Huang
- School of Public Health, Wuhan University of Science and Technology, Wuhan, Hubei, China.,Department of Physiology, Wayne State University, Detroit, MI, USA
| | - Yunhao Liu
- School of Public Health, Wuhan University of Science and Technology, Wuhan, Hubei, China
| | - Shiyang Zhang
- School of Public Health, Wuhan University of Science and Technology, Wuhan, Hubei, China.,Department of Physiology, Wayne State University, Detroit, MI, USA
| | - Yi Tian Yap
- Department of Physiology, Wayne State University, Detroit, MI, USA
| | - Wei Li
- Department of Physiology, Wayne State University, Detroit, MI, USA
| | - David Zhang
- School of Arts and Sciences, College of William and Mary, Williamsburg, VA, USA
| | - Ahmad Gardner
- Department of Physiology, Wayne State University, Detroit, MI, USA.,Detroit High School, Detroit, MI, USA
| | - Ling Zhang
- School of Public Health, Wuhan University of Science and Technology, Wuhan, Hubei, China
| | - Shizheng Song
- School of Public Health, Wuhan University of Science and Technology, Wuhan, Hubei, China
| | - Rex A Hess
- Comparative Biosciences, College of Veterinary Medicine, University of Illinois, Urbana, IL, USA
| | - Zhibing Zhang
- Department of Physiology, Wayne State University, Detroit, MI, USA.,Department of Obstetrics/Gynecology, Wayne State University, Detroit, MI, USA
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57
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Yahyavy S, Valizadeh A, Saki G, Khorsandi L. Taurine induces autophagy and inhibits oxidative stress in mice Leydig cells. JBRA Assist Reprod 2020; 24:250-256. [PMID: 32155016 PMCID: PMC7365531 DOI: 10.5935/1518-0557.20190079] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVES This study evaluated taurine (TAU) effects on autophagy, apoptosis and oxidative stress in mice Leydig TM3 cells. METHODS We treated TM3 cells with TAU (100 µg/mL) or 3-Methyladenine (3-MA, an autophagy inhibitor) for 24 h, and assessed cell viability, testosterone level, oxidative stress, apoptosis, and autophagy. RESULTS The results showed that TAU markedly increased cell viability, testosterone levels, expression of autophagy-related genes and percentage of LC3-II-positive cells. TAU significantly reduced malondialdehyde (MDA) contents and reactive oxygen species (ROS) levels and increased the activities of SOD (superoxide dismutase) and CAT (Catalase) enzymes in the TM3 cells. TAU in the presence of autophagy inhibitor (3-MA) increased oxidative stress and decreased testosterone levels. CONCLUSION The results showed that autophagy might be involved in TAU-increased testosterone levels in mice Leydig TM3 cells.
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Affiliation(s)
- Shokofeh Yahyavy
- Cellular and Molecular Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Department of Anatomical Sciences, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Armita Valizadeh
- Department of Anatomical Sciences, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Ghasem Saki
- Department of Anatomical Sciences, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Layasadat Khorsandi
- Cellular and Molecular Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Department of Anatomical Sciences, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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58
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Abstract
Autophagy degrades the cytoplasmic contents engulfed by autophagosomes. Besides providing energy and building blocks during starvation via random degradation, autophagy selectively targets cytotoxic components to prevent a wide range of diseases. This preventive activity of autophagy is supported by many studies using animal models and reports identifying several mutations in autophagy-related genes that are associated with human genetic disorders, which have been published in the past decade. Here, we summarize the molecular mechanisms of autophagosome biogenesis involving the proteins responsible for these genetic disorders, demonstrating a role for autophagy in human health. These findings will help elucidate the underlying mechanisms of autophagy-related diseases and develop future medications.
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Affiliation(s)
- Tsuyoshi Kawabata
- Department of Stem Cell Biology, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, 852-8523 Japan
| | - Tamotsu Yoshimori
- Department of Genetics, Graduate School of Medicine, Osaka University, Osaka, 565-0871 Japan
- Department of Intracellular Membrane Dynamics, Graduate School of Frontier Biosciences, Osaka University, Osaka, 565-0871 Japan
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59
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Martens S, Fracchiolla D. Activation and targeting of ATG8 protein lipidation. Cell Discov 2020; 6:23. [PMID: 32377373 PMCID: PMC7198486 DOI: 10.1038/s41421-020-0155-1] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 03/03/2020] [Indexed: 12/19/2022] Open
Abstract
ATG8 family proteins are evolutionary conserved ubiquitin-like modifiers, which become attached to the headgroup of the membrane lipid phosphatidylethanolamine in a process referred to as lipidation. This reaction is carried out analogous to the conjugation of ubiquitin to its target proteins, involving the E1-like ATG7, the E2-like ATG3 and the E3-like ATG12-ATG5-ATG16 complex, which determines the site of lipidation. ATG8 lipidation is a hallmark of autophagy where these proteins are involved in autophagosome formation, the fusion of autophagosomes with lysosomes and cargo selection. However, it has become evident that ATG8 lipidation also occurs in processes that are not directly related to autophagy. Here we discuss recent insights into the targeting of ATG8 lipidation in autophagy and other pathways with special emphasis on the recruitment and activation of the E3-like complex.
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Affiliation(s)
- Sascha Martens
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9/5, 1030 Vienna, Austria
| | - Dorotea Fracchiolla
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9/5, 1030 Vienna, Austria
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60
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Bell K, Rosignol I, Sierra-Filardi E, Rodriguez-Muela N, Schmelter C, Cecconi F, Grus F, Boya P. Age related retinal Ganglion cell susceptibility in context of autophagy deficiency. Cell Death Discov 2020; 6:21. [PMID: 32337073 PMCID: PMC7165178 DOI: 10.1038/s41420-020-0257-4] [Citation(s) in RCA: 11] [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: 02/07/2020] [Accepted: 03/25/2020] [Indexed: 12/26/2022] Open
Abstract
Glaucoma is a common age-related disease leading to progressive retinal ganglion cell (RGC) death, visual field defects and vision loss and is the second leading cause of blindness in the elderly worldwide. Mitochondrial dysfunction and impaired autophagy have been linked to glaucoma and induction of autophagy shows neuroprotective effects in glaucoma animal models. We have shown that autophagy decreases with aging in the retina and that autophagy can be neuroprotective for RGCs, but it is currently unknown how aging and autophagy deficiency impact RGCs susceptibility and survival. Using the optic nerve crush model in young and olWelcome@1234d Ambra1 +/gt (autophagy/beclin-1 regulator 1+/gt) mice we analysed the contribution of autophagy deficiency on retinal ganglion cell survival in an age dependent context. Interestingly, old Ambra1 +/gt mice showed decreased RGC survival after optic nerve crush in comparison to old Ambra1 +/+, an effect that was not observed in the young animals. Proteomics and mRNA expression data point towards altered oxidative stress response and mitochondrial alterations in old Ambra1 +/gt animals. This effect is intensified after RGC axonal damage, resulting in reduced oxidative stress response showing decreased levels of Nqo1, as well as failure of Nrf2 induction in the old Ambra1 +/gt. Old Ambra1 +/gt also failed to show increase in Bnip3l and Bnip3 expression after optic nerve crush, a response that is found in the Ambra1 +/+ controls. Primary RGCs derived from Ambra1 +/gt mice show decreased neurite projection and increased levels of apoptosis in comparison to Ambra1 +/+ animals. Our results lead to the conclusion that oxidative stress response pathways are altered in old Ambra1 +/gt mice leading to impaired damage responses upon additional external stress factors.
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Affiliation(s)
- Katharina Bell
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
- Experimental and Translational Ophthalmology, Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Ines Rosignol
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
| | - Elena Sierra-Filardi
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
| | - Natalia Rodriguez-Muela
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
- Deutsche Zentrum für Neurodegenerative Erkrankungen e.V, DZNE/German Center for Neurodegenerative Diseases, Dresden, Germany
| | - Carsten Schmelter
- Experimental and Translational Ophthalmology, Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Francesco Cecconi
- Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Franz Grus
- Experimental and Translational Ophthalmology, Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Patricia Boya
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
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61
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Sánchez-Díaz M, Nicolás-Ávila JÁ, Cordero MD, Hidalgo A. Mitochondrial Adaptations in the Growing Heart. Trends Endocrinol Metab 2020; 31:308-319. [PMID: 32035734 DOI: 10.1016/j.tem.2020.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 11/22/2019] [Accepted: 01/09/2020] [Indexed: 12/14/2022]
Abstract
The heart pumps blood throughout the whole life of an organism, without rest periods during which to replenish energy or detoxify. Hence, cardiomyocytes, the working units of the heart, have mechanisms to ensure constitutive production of energy and detoxification to preserve fitness and function for decades. Even more challenging, the heart must adapt to the varying conditions of the organism from fetal life to adulthood, old age, and pathological stress. Mitochondria are at the nexus of these processes by producing not only energy but also metabolites and oxidative byproducts that can activate alarm signals and be toxic to the cell. We review basic concepts about cardiac mitochondria with a focus on their remarkable adaptations, including elimination, throughout the mammalian lifetime.
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Affiliation(s)
- María Sánchez-Díaz
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain
| | | | - Mario D Cordero
- Cátedra de Reproducción y Genética Humana del Instituto para el Estudio de la Biología de la Reproducción Humana (INEBIR), 41009 Sevilla, Spain; Universidad Europea del Atlántico (UNEATLANTICO), and Fundación Universitaria Iberoamericana (FUNIBER), 39011 Santander, Spain.
| | - Andrés Hidalgo
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain; Institute for Cardiovascular Prevention (IPEK), Ludwig-Maximillians-Universität, Munich, Germany.
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62
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Suresh SN, Chakravorty A, Giridharan M, Garimella L, Manjithaya R. Pharmacological Tools to Modulate Autophagy in Neurodegenerative Diseases. J Mol Biol 2020; 432:2822-2842. [PMID: 32105729 DOI: 10.1016/j.jmb.2020.02.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 02/03/2020] [Accepted: 02/12/2020] [Indexed: 12/11/2022]
Abstract
Considerable evidences suggest a link between autophagy dysfunction, protein aggregation, and neurodegenerative diseases. Given that autophagy is a conserved intracellular housekeeping process, modulation of autophagy flux in various model organisms have highlighted its importance for maintaining proteostasis. In postmitotic cells such as neurons, compromised autophagy is sufficient to cause accumulation of ubiquitinated aggregates, neuronal dysfunction, degeneration, and loss of motor coordination-all hallmarks of neurodegenerative diseases. Reciprocally, enhanced autophagy flux augments cellular and organismal health, in addition to extending life span. These genetic studies not-withstanding a plethora of small molecule modulators of autophagy flux have been reported that alleviate disease symptoms in models of neurodegenerative diseases. This review summarizes the potential of such molecules to be, perhaps, one of the first autophagy drugs for treating these currently incurable diseases.
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Affiliation(s)
- S N Suresh
- Centre for Brain Research, Indian Institute of Science, Bangalore, 560012, Karnataka, India
| | - Anushka Chakravorty
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, Karnataka, India
| | - Mridhula Giridharan
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, Karnataka, India
| | - Lakshmi Garimella
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, Karnataka, India
| | - Ravi Manjithaya
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, Karnataka, India; Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, Karnataka, India.
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63
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Sukseree S, Schwarze UY, Gruber R, Gruber F, Quiles Del Rey M, Mancias JD, Bartlett JD, Tschachler E, Eckhart L. ATG7 is essential for secretion of iron from ameloblasts and normal growth of murine incisors during aging. Autophagy 2020; 16:1851-1857. [PMID: 31880208 DOI: 10.1080/15548627.2019.1709764] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The incisors of rodents comprise an iron-rich enamel and grow throughout adult life, making them unique models of iron metabolism and tissue homeostasis during aging. Here, we deleted Atg7 (autophagy related 7) in murine ameloblasts, i.e. the epithelial cells that produce enamel. The absence of ATG7 blocked the transport of iron from ameloblasts into the maturing enamel, leading to a white instead of yellow surface of maxillary incisors. In aging mice, lack of ATG7 was associated with the growth of ectopic incisors inside severely deformed primordial incisors. These results suggest that 2 characteristic features of rodent incisors, i.e. deposition of iron on the enamel surface and stable growth during aging, depend on autophagic activity in ameloblasts. Abbreviations: ATG5: autophagy related 5; ATG7: autophagy related 7; CMV: cytomegalovirus; Cre: Cre recombinase; CT: computed tomography; FTH1: ferritin heavy polypeptide 1; GFP: green fluorescent protein; KRT5: keratin 5; KRT14: keratin 14; LGALS3: lectin, galactose binding, soluble 3; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; NCOA4: nuclear receptor coactivator 4; NRF2: nuclear factor, erythroid 2 like 2; SQSTM1: sequestosome 1.
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Affiliation(s)
- Supawadee Sukseree
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
| | | | - Reinhard Gruber
- Department of Oral Biology, Medical University of Vienna , Vienna, Austria
| | - Florian Gruber
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
| | - Maria Quiles Del Rey
- Division of Genomic Stability and DNA Repair, Department of Radiation Oncology, Dana-Farber Cancer Institute , Boston, MA, USA
| | - Joseph D Mancias
- Division of Genomic Stability and DNA Repair, Department of Radiation Oncology, Dana-Farber Cancer Institute , Boston, MA, USA
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State University , Columbus, OH, USA
| | - Erwin Tschachler
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
| | - Leopold Eckhart
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
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Zheng X, Yang Z, Gu Q, Xia F, Fu Y, Liu P, Yin XM, Li M. The protease activity of human ATG4B is regulated by reversible oxidative modification. Autophagy 2020; 16:1838-1850. [PMID: 31880198 DOI: 10.1080/15548627.2019.1709763] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Macroautophagy/autophagy plays a pivotal role in cytoplasmic material recycling and metabolic turnover, in which ATG4B functions as a "scissor" for processing pro-LC3 and lipidated LC3 to drive the autophagy progress. Mounting evidence has demonstrated the tight connection between ROS and autophagy during various pathological situations. Coincidentally, several studies have shown that ATG4B is potentially regulated by redox modification, but the underlying molecular mechanism and its relationship with autophagy is ambiguous. In this study, we verified that ATG4B activity was definitely regulated in a reversible redox manner. We also determined that Cys292 and Cys361 are essential sites of ATG4B to form reversible intramolecular disulfide bonds that respond to oxidative stress. Interestingly, we unraveled a new phenomenon that ATG4B concurrently formed disulfide-linked oligomers at Cys292 and Cys361, and that both sites underwent redox modifications thereby modulating ATG4B activity. Finally, increased autophagic flux and decreased oxidation sensitivity were observed in Cys292 and Cys361 double site-mutated cells under normal growth conditions. In conclusion, our research reveals a novel molecular mechanism that oxidative modification at Cys292 and Cys361 sites regulates ATG4B function, which modulates autophagy.Abbreviations: Air-ox: air-oxidation; ATG4B: autophagy related 4B cysteine peptidase; BCNU: 1,3-bis(2-chloroethyl)-1-nitrosourea; CBB: Coomassie Brilliant Blue; CM: complete medium; CQ: chloroquine; DTT: dithiothreitol; GSH: reduced glutathione; GSNO: S-nitrosoglutathione; GSSG: oxidized glutathione; HMW: high molecular weight; H2O2: hydrogen peroxide; NAC: N-acetyl-L-cysteine; NEM: N-ethylmaleimide; PE: phosphatidylethanolamine; PTM: post-translational modification; ROS, reactive oxygen species; WT: wild type.
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Affiliation(s)
- Xueping Zheng
- School of Pharmaceutical Sciences, Sun Yat-Sen University, National-Local Joint Engineering Lab of Druggability and New Drugs Evaluation, Guangdong Engineering Laboratory of Druggability and New Drug Evaluation, Provincial Key Laboratory of New Drug Design and Evaluation , Guangzhou, Guangdong, China
| | - Zuolong Yang
- School of Pharmaceutical Sciences, Sun Yat-Sen University, National-Local Joint Engineering Lab of Druggability and New Drugs Evaluation, Guangdong Engineering Laboratory of Druggability and New Drug Evaluation, Provincial Key Laboratory of New Drug Design and Evaluation , Guangzhou, Guangdong, China
| | - Qianqian Gu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, National-Local Joint Engineering Lab of Druggability and New Drugs Evaluation, Guangdong Engineering Laboratory of Druggability and New Drug Evaluation, Provincial Key Laboratory of New Drug Design and Evaluation , Guangzhou, Guangdong, China
| | - Fan Xia
- School of Pharmaceutical Sciences, Sun Yat-Sen University, National-Local Joint Engineering Lab of Druggability and New Drugs Evaluation, Guangdong Engineering Laboratory of Druggability and New Drug Evaluation, Provincial Key Laboratory of New Drug Design and Evaluation , Guangzhou, Guangdong, China
| | - Yuanyuan Fu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, National-Local Joint Engineering Lab of Druggability and New Drugs Evaluation, Guangdong Engineering Laboratory of Druggability and New Drug Evaluation, Provincial Key Laboratory of New Drug Design and Evaluation , Guangzhou, Guangdong, China
| | - Peiqing Liu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, National-Local Joint Engineering Lab of Druggability and New Drugs Evaluation, Guangdong Engineering Laboratory of Druggability and New Drug Evaluation, Provincial Key Laboratory of New Drug Design and Evaluation , Guangzhou, Guangdong, China
| | - Xiao-Ming Yin
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine , Indianapolis, IN, USA
| | - Min Li
- School of Pharmaceutical Sciences, Sun Yat-Sen University, National-Local Joint Engineering Lab of Druggability and New Drugs Evaluation, Guangdong Engineering Laboratory of Druggability and New Drug Evaluation, Provincial Key Laboratory of New Drug Design and Evaluation , Guangzhou, Guangdong, China
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65
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Dong G, Zhang Z, Duan K, Shi W, Huang R, Wang B, Luo L, Zhang Y, Ruan H, Huang H. Beclin 1 deficiency causes hepatic cell apoptosis via endoplasmic reticulum stress in zebrafish larvae. FEBS Lett 2019; 594:1155-1165. [PMID: 31823348 DOI: 10.1002/1873-3468.13712] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 11/26/2019] [Accepted: 11/28/2019] [Indexed: 01/05/2023]
Abstract
Beclin 1/Atg6 is an essential autophagy gene, and deficiency of this gene in organisms leads to impaired autophagic flux, usually with cell apoptosis; however, the causative mechanism of cell apoptosis is not clear. Here, we knocked out the beclin 1 gene in zebrafish and found that autophagic flux is disrupted in mutants. Beclin 1-deficient zebrafish live through embryogenesis but die at larval stage. We found accumulated protein aggregates and vigorous apoptosis in mutant larvae, predominantly in the liver. The hepatic cell apoptosis in mutants results from an endoplasmic reticulum (ER) stress response; however, it is not the leading cause of mutant larval lethality. Our work proposes that ER stress induces cell apoptosis in Beclin 1-deficient organisms.
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Affiliation(s)
- Guoping Dong
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environments and Bio-Resources of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China
| | - Zhe Zhang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environments and Bio-Resources of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China
| | - Kun Duan
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environments and Bio-Resources of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China
| | - Wenpeng Shi
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environments and Bio-Resources of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China
| | - Rui Huang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environments and Bio-Resources of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China
| | - Bangjun Wang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environments and Bio-Resources of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China
| | - Lingfei Luo
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environments and Bio-Resources of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China
| | - Yaoguang Zhang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environments and Bio-Resources of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China
| | - Hua Ruan
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environments and Bio-Resources of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China
| | - Honghui Huang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environments and Bio-Resources of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, China
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66
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Stead ER, Castillo-Quan JI, Miguel VEM, Lujan C, Ketteler R, Kinghorn KJ, Bjedov I. Agephagy - Adapting Autophagy for Health During Aging. Front Cell Dev Biol 2019; 7:308. [PMID: 31850344 PMCID: PMC6892982 DOI: 10.3389/fcell.2019.00308] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 11/12/2019] [Indexed: 12/11/2022] Open
Abstract
Autophagy is a major cellular recycling process that delivers cellular material and entire organelles to lysosomes for degradation, in a selective or non-selective manner. This process is essential for the maintenance of cellular energy levels, components, and metabolites, as well as the elimination of cellular molecular damage, thereby playing an important role in numerous cellular activities. An important function of autophagy is to enable survival under starvation conditions and other stresses. The majority of factors implicated in aging are modifiable through the process of autophagy, including the accumulation of oxidative damage and loss of proteostasis, genomic instability and epigenetic alteration. These primary causes of damage could lead to mitochondrial dysfunction, deregulation of nutrient sensing pathways and cellular senescence, finally causing a variety of aging phenotypes. Remarkably, advances in the biology of aging have revealed that aging is a malleable process: a mild decrease in signaling through nutrient-sensing pathways can improve health and extend lifespan in all model organisms tested. Consequently, autophagy is implicated in both aging and age-related disease. Enhancement of the autophagy process is a common characteristic of all principal, evolutionary conserved anti-aging interventions, including dietary restriction, as well as inhibition of target of rapamycin (TOR) and insulin/IGF-1 signaling (IIS). As an emerging and critical process in aging, this review will highlight how autophagy can be modulated for health improvement.
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Affiliation(s)
- Eleanor R Stead
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Jorge I Castillo-Quan
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Boston, MA, United States
| | | | - Celia Lujan
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Robin Ketteler
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Kerri J Kinghorn
- Institute of Healthy Ageing, University College London, London, United Kingdom.,Department of Genetics, Evolution and Environment, University College London, London, United Kingdom.,Institute of Neurology, University College London, London, United Kingdom
| | - Ivana Bjedov
- UCL Cancer Institute, University College London, London, United Kingdom
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67
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Abstract
Cardiovascular diseases are the most prominent maladies in aging societies. Indeed, aging promotes the structural and functional declines of both the heart and the blood circulation system. In this review, we revise the contribution of known longevity pathways to cardiovascular health and delineate the possibilities to interfere with them. In particular, we evaluate autophagy, the intracellular catabolic recycling system associated with life- and health-span extension. We present genetic models, pharmacological interventions, and dietary strategies that block, reduce, or enhance autophagy upon age-related cardiovascular deterioration. Caloric restriction or caloric restriction mimetics like metformin, spermidine, and rapamycin (all of which trigger autophagy) are among the most promising cardioprotective interventions during aging. We conclude that autophagy is a fundamental process to ensure cardiac and vascular health during aging and outline its putative therapeutic importance.
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Affiliation(s)
- Mahmoud Abdellatif
- From the Department of Cardiology, Medical University of Graz, Austria (M.A., S.S.)
| | - Simon Sedej
- From the Department of Cardiology, Medical University of Graz, Austria (M.A., S.S.).,BioTechMed Graz, Austria (S.S., D.C.-G., F.M.)
| | - Didac Carmona-Gutierrez
- BioTechMed Graz, Austria (S.S., D.C.-G., F.M.).,Institute of Molecular Biosciences, NAWI Graz, University of Graz, Austria (D.C.-G., F.M.)
| | - Frank Madeo
- BioTechMed Graz, Austria (S.S., D.C.-G., F.M.).,Institute of Molecular Biosciences, NAWI Graz, University of Graz, Austria (D.C.-G., F.M.)
| | - Guido Kroemer
- Equipe 11 Labellisée Ligue Contre le Cancer, Centre de Recherche des Cordeliers, Paris, France (G.K.).,Cell Biology and Metabolomics Platforms, Gustave Roussy Comprehensive Cancer Center, Villejuif, France (G.K.).,INSERM, U1138, Paris, France (G.K.).,Université Paris Descartes, Sorbonne Paris Cité, France (G.K.).,Université Pierre et Marie Curie, Paris, France (G.K.).,Pôle de Biologie, Hôpital Européen Georges Pompidou, Paris, France (G.K.).,Department of Women's and Children's Health, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden (G.K.)
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68
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Suomi F, McWilliams T. Autophagy in the mammalian nervous system: a primer for neuroscientists. Neuronal Signal 2019; 3:NS20180134. [PMID: 32269837 PMCID: PMC7104325 DOI: 10.1042/ns20180134] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 07/06/2019] [Accepted: 08/05/2019] [Indexed: 12/12/2022] Open
Abstract
Autophagy refers to the lysosomal degradation of damaged or superfluous components and is essential for metabolic plasticity and tissue integrity. This evolutionarily conserved process is particularly vital to mammalian post-mitotic cells such as neurons, which face unique logistical challenges and must sustain homoeostasis over decades. Defective autophagy has pathophysiological importance, especially for human neurodegeneration. The present-day definition of autophagy broadly encompasses two distinct yet related phenomena: non-selective and selective autophagy. In this minireview, we focus on established and emerging concepts in the field, paying particular attention to the physiological significance of macroautophagy and the burgeoning world of selective autophagy pathways in the context of the vertebrate nervous system. By highlighting established basics and recent breakthroughs, we aim to provide a useful conceptual framework for neuroscientists interested in autophagy, in addition to autophagy enthusiasts with an eye on the nervous system.
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Affiliation(s)
- Fumi Suomi
- Translational Stem Cell Biology and Metabolism Program, Research Programs Unit, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Haartmaninkatu 8, Helsinki 00290, Finland
| | - Thomas G. McWilliams
- Translational Stem Cell Biology and Metabolism Program, Research Programs Unit, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Haartmaninkatu 8, Helsinki 00290, Finland
- Department of Anatomy, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Haartmaninkatu 8, Helsinki 00290, Finland
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69
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Lystad AH, Simonsen A. Mechanisms and Pathophysiological Roles of the ATG8 Conjugation Machinery. Cells 2019; 8:E973. [PMID: 31450711 PMCID: PMC6769624 DOI: 10.3390/cells8090973] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 08/19/2019] [Accepted: 08/20/2019] [Indexed: 12/18/2022] Open
Abstract
Since their initial discovery around two decades ago, the yeast autophagy-related (Atg)8 protein and its mammalian homologues of the light chain 3 (LC3) and γ-aminobutyric acid receptor associated proteins (GABARAP) families have been key for the tremendous expansion of our knowledge about autophagy, a process in which cytoplasmic material become targeted for lysosomal degradation. These proteins are ubiquitin-like proteins that become directly conjugated to a lipid in the autophagy membrane upon induction of autophagy, thus providing a marker of the pathway, allowing studies of autophagosome biogenesis and maturation. Moreover, the ATG8 proteins function to recruit components of the core autophagy machinery as well as cargo for selective degradation. Importantly, comprehensive structural and biochemical in vitro studies of the machinery required for ATG8 protein lipidation, as well as their genetic manipulation in various model organisms, have provided novel insight into the molecular mechanisms and pathophysiological roles of the mATG8 proteins. Recently, it has become evident that the ATG8 proteins and their conjugation machinery are also involved in intracellular pathways and processes not related to autophagy. This review focuses on the molecular functions of ATG8 proteins and their conjugation machinery in autophagy and other pathways, as well as their links to disease.
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Affiliation(s)
- Alf Håkon Lystad
- Department of Molecular Medicine, Institute of Basic Medical Sciences and Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, 1112 Blindern, 0317 Oslo, Norway.
| | - Anne Simonsen
- Department of Molecular Medicine, Institute of Basic Medical Sciences and Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, 1112 Blindern, 0317 Oslo, Norway.
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70
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Pan X, Neufeld TP, O'Connor MB. A Tissue- and Temporal-Specific Autophagic Switch Controls Drosophila Pre-metamorphic Nutritional Checkpoints. Curr Biol 2019; 29:2840-2851.e4. [PMID: 31422886 DOI: 10.1016/j.cub.2019.07.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 05/24/2019] [Accepted: 07/10/2019] [Indexed: 01/28/2023]
Abstract
Properly timed production of steroid hormones by endocrine tissues regulates juvenile-to-adult transitions in both mammals (puberty) and holometabolous insects (metamorphosis). Nutritional conditions influence the temporal control of the transition, but the mechanisms responsible are ill defined. Here we demonstrate that autophagy acts as an endocrine organ-specific, nutritionally regulated gating mechanism to help ensure productive metamorphosis in Drosophila. Autophagy in the endocrine organ is specifically stimulated by nutrient restriction at the early, but not the late, third-instar larva stage. The timing of autophagy induction correlates with the nutritional checkpoints, which inhibit precocious metamorphosis during nutrient restriction in undersized larvae. Suppression of autophagy causes dysregulated pupariation of starved larvae, which leads to pupal lethality, whereas forced autophagy induction results in developmental delay/arrest in well-fed animals. Induction of autophagy disrupts production of the steroid hormone ecdysone at the time of pupariation not by destruction of hormone biosynthetic capacity but rather by limiting the availability of the steroid hormone precursor cholesterol in the endocrine cells via a lipophagy mechanism. Interestingly, autophagy in the endocrine organ functions by interacting with the endolysosome system, yet shows multiple features not fully consistent with a canonical autophagy process. Taken together, our findings demonstrate an autophagy mechanism in endocrine cells that helps shape the nutritional checkpoints and guarantee a successful juvenile-to-adult transition in animals confronting nutritional stress.
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Affiliation(s)
- Xueyang Pan
- Department of Genetics, Cell Biology and Development and the Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Thomas P Neufeld
- Department of Genetics, Cell Biology and Development and the Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Michael B O'Connor
- Department of Genetics, Cell Biology and Development and the Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, USA.
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71
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Chino H, Hatta T, Natsume T, Mizushima N. Intrinsically Disordered Protein TEX264 Mediates ER-phagy. Mol Cell 2019; 74:909-921.e6. [PMID: 31006538 DOI: 10.1016/j.molcel.2019.03.033] [Citation(s) in RCA: 209] [Impact Index Per Article: 41.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 02/14/2019] [Accepted: 03/27/2019] [Indexed: 12/20/2022]
Abstract
Certain proteins and organelles can be selectively degraded by autophagy. Typical substrates and receptors of selective autophagy have LC3-interacting regions (LIRs) that bind to autophagosomal LC3 and GABARAP family proteins. Here, we performed a differential interactome screen using wild-type LC3B and a LIR recognition-deficient mutant and identified TEX264 as a receptor for autophagic degradation of the endoplasmic reticulum (ER-phagy). TEX264 is an ER protein with a single transmembrane domain and a LIR motif. TEX264 interacts with LC3 and GABARAP family proteins more efficiently and is expressed more ubiquitously than previously known ER-phagy receptors. ER-phagy is profoundly blocked by deletion of TEX264 alone and almost completely by additional deletion of FAM134B and CCPG1. A long intrinsically disordered region of TEX264 is required for its ER-phagy receptor function to bridge the gap between the ER and autophagosomal membranes independently of its amino acid sequence. These results suggest that TEX264 is a major ER-phagy receptor.
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Affiliation(s)
- Haruka Chino
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; Department of Respiratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Tomohisa Hatta
- Molecular Profiling Research Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), Tokyo 135-0064, Japan
| | - Tohru Natsume
- Molecular Profiling Research Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), Tokyo 135-0064, Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
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72
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Watch What You (Self-) Eat: Autophagic Mechanisms that Modulate Metabolism. Cell Metab 2019; 29:803-826. [PMID: 30943392 PMCID: PMC6450419 DOI: 10.1016/j.cmet.2019.03.003] [Citation(s) in RCA: 188] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 02/07/2019] [Accepted: 03/04/2019] [Indexed: 02/07/2023]
Abstract
Autophagy is an evolutionarily conserved lysosome- or vacuole-dependent catabolic pathway in eukaryotes. Autophagy functions basally for cellular quality control and is induced to act as an alternative source of basic metabolites during nutrient deprivation. These functions of autophagy are intimately connected to the regulation of metabolism, and the metabolic status of the cell in turn controls the nature and extent of autophagic induction. Here, we highlight the co-regulation of autophagy and metabolism with a special focus on selective autophagy that, along with bulk autophagy, plays a central role in regulating and rewiring metabolic circuits. We outline the metabolic signals that activate these pathways, the mechanisms involved, and the downstream effects and implications while recognizing yet unanswered questions. We also discuss the role of autophagy in the development and maintenance of adipose tissue, an emerging player in systemic metabolic homeostasis, and describe what is currently known about the complex relationship between autophagy and cancer.
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73
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Rai S, Arasteh M, Jefferson M, Pearson T, Wang Y, Zhang W, Bicsak B, Divekar D, Powell PP, Naumann R, Beraza N, Carding SR, Florey O, Mayer U, Wileman T. The ATG5-binding and coiled coil domains of ATG16L1 maintain autophagy and tissue homeostasis in mice independently of the WD domain required for LC3-associated phagocytosis. Autophagy 2019; 15:599-612. [PMID: 30403914 PMCID: PMC6526875 DOI: 10.1080/15548627.2018.1534507] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 09/28/2018] [Accepted: 10/05/2018] [Indexed: 11/11/2022] Open
Abstract
Macroautophagy/autophagy delivers damaged proteins and organelles to lysosomes for degradation, and plays important roles in maintaining tissue homeostasis by reducing tissue damage. The translocation of LC3 to the limiting membrane of the phagophore, the precursor to the autophagosome, during autophagy provides a binding site for autophagy cargoes, and facilitates fusion with lysosomes. An autophagy-related pathway called LC3-associated phagocytosis (LAP) targets LC3 to phagosome and endosome membranes during uptake of bacterial and fungal pathogens, and targets LC3 to swollen endosomes containing particulate material or apoptotic cells. We have investigated the roles played by autophagy and LAP in vivo by exploiting the observation that the WD domain of ATG16L1 is required for LAP, but not autophagy. Mice lacking the linker and WD domains, activate autophagy, but are deficient in LAP. The LAP-/- mice survive postnatal starvation, grow at the same rate as littermate controls, and are fertile. The liver, kidney, brain and muscle of these mice maintain levels of autophagy cargoes such as LC3 and SQSTM1/p62 similar to littermate controls, and prevent accumulation of SQSTM1 inclusions and tissue damage associated with loss of autophagy. The results suggest that autophagy maintains tissue homeostasis in mice independently of LC3-associated phagocytosis. Further deletion of glutamate E230 in the coiled-coil domain required for WIPI2 binding produced mice with defective autophagy that survived neonatal starvation. Analysis of brain lysates suggested that interactions between WIPI2 and ATG16L1 were less critical for autophagy in the brain, which may allow a low level of autophagy to overcome neonatal lethality. Abbreviations: CCD: coiled-coil domain; CYBB/NOX2: cytochrome b-245: beta polypeptide; GPT/ALT: glutamic pyruvic transaminase: soluble; LAP: LC3-associated phagocytosis; LC3: microtubule-associated protein 1 light chain 3; MEF: mouse embryonic fibroblast; NOD: nucleotide-binding oligomerization domain; NADPH: nicotinamide adenine dinucleotide phosphate; RUBCN/Rubicon: RUN domain and cysteine-rich domain containing Beclin 1-interacting protein; SLE: systemic lupus erythematosus; SQSTM1/p62: sequestosome 1; TLR: toll-like receptor; TMEM: transmembrane protein; TRIM: tripartite motif-containing protein; UVRAG: UV radiation resistance associated gene; WD: tryptophan-aspartic acid; WIPI: WD 40 repeat domain: phosphoinositide interacting.
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Affiliation(s)
- Shashank Rai
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
| | - Maryam Arasteh
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
| | - Matthew Jefferson
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
| | - Timothy Pearson
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
| | - Yingxue Wang
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
| | - Weijiao Zhang
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
| | - Bertalan Bicsak
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
| | - Devina Divekar
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
| | - Penny P. Powell
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
| | - Ronald Naumann
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | | | | | - Oliver Florey
- Signalling Programme, Babraham Institute, Cambridge, UK
| | - Ulrike Mayer
- School of Biological Sciences, University of East Anglia, Norwich, Norfolk, UK
| | - Thomas Wileman
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
- Quadram Institute Bioscience, Norwich, Norfolk, UK
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74
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Hui KK, Takashima N, Watanabe A, Chater TE, Matsukawa H, Nekooki-Machida Y, Nilsson P, Endo R, Goda Y, Saido TC, Yoshikawa T, Tanaka M. GABARAPs dysfunction by autophagy deficiency in adolescent brain impairs GABA A receptor trafficking and social behavior. SCIENCE ADVANCES 2019; 5:eaau8237. [PMID: 30989111 PMCID: PMC6457945 DOI: 10.1126/sciadv.aau8237] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 02/20/2019] [Indexed: 05/02/2023]
Abstract
Dysfunctional mTOR signaling is associated with the pathogenesis of neurodevelopmental and neuropsychiatric disorders. However, it is unclear what molecular mechanisms and pathogenic mediators are involved and whether mTOR-regulated autophagy continues to be crucial beyond neurodevelopment. Here, we selectively deleted Atg7 in forebrain GABAergic interneurons in adolescent mice and unexpectedly found that these mice showed a set of behavioral deficits similar to Atg7 deletion in forebrain excitatory neurons. By unbiased quantitative proteomic analysis, we identified γ-aminobutyric acid receptor-associated protein-like 2 (GABARAPL2) to differentially form high-molecular weight species in autophagy-deficient brains. Further functional analyses revealed a novel pathogenic mechanism involving the p62-dependent sequestration of GABARAP family proteins, leading to the reduction of surface GABAA receptor levels. Our work demonstrates a novel physiological role for autophagy in regulating GABA signaling beyond postnatal neurodevelopment, providing a potential mechanism for the reduced inhibitory inputs observed in neurodevelopmental and neuropsychiatric disorders with mTOR hyperactivation.
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Affiliation(s)
- Kelvin K. Hui
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Noriko Takashima
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Akiko Watanabe
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Thomas E. Chater
- Laboratory for Synaptic Plasticity and Connectivity, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Hiroshi Matsukawa
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
- Laboratory for Behavioral Genetics, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Yoko Nekooki-Machida
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Per Nilsson
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
- Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge 141 57, Sweden
| | - Ryo Endo
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Yukiko Goda
- Laboratory for Synaptic Plasticity and Connectivity, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Takaomi C. Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Takeo Yoshikawa
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Motomasa Tanaka
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
- Corresponding author.
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75
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Autophagy in corneal health and disease: A concise review. Ocul Surf 2019; 17:186-197. [DOI: 10.1016/j.jtos.2019.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 12/21/2018] [Accepted: 01/23/2019] [Indexed: 01/01/2023]
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76
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Autophagy and Its Role in Protein Secretion: Implications for Cancer Therapy. Mediators Inflamm 2018; 2018:4231591. [PMID: 30622432 PMCID: PMC6304875 DOI: 10.1155/2018/4231591] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 09/26/2018] [Accepted: 10/02/2018] [Indexed: 12/11/2022] Open
Abstract
Autophagy is a protein and organelle degradation pathway important for the maintenance of cytoplasmic homeostasis and for providing nutrients for survival in response to stress conditions. Recently, autophagy has been shown to be important for the secretion of diverse proteins involved in inflammation, intercellular signaling, and cancer progression. The role of autophagy in cancer depends on the stage of tumorigenesis, serving a tumor-suppressor role before transformation and a tumor-survival function once a tumor is established. We review recent evidence demonstrating the complexity of autophagy regulation during cancer, considering the interaction of autophagy with protein secretion pathways. Autophagy manipulation during cancer treatment is likely to affect protein secretion andinter-cellular signaling either to the neighboring cancer cells or to the antitumoral immune response. This will be an important consideration during cancer therapy since several clinical trials are trying to manipulate autophagy in combination with chemotherapy for the treatment of diverse types of cancers.
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77
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Ye X, Zhou XJ, Zhang H. Exploring the Role of Autophagy-Related Gene 5 ( ATG5) Yields Important Insights Into Autophagy in Autoimmune/Autoinflammatory Diseases. Front Immunol 2018; 9:2334. [PMID: 30386331 PMCID: PMC6199349 DOI: 10.3389/fimmu.2018.02334] [Citation(s) in RCA: 181] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 09/19/2018] [Indexed: 12/31/2022] Open
Abstract
Autophagy is a highly conserved process that degrades certain intracellular contents in both physiological and pathological conditions. Autophagy-related proteins (ATG) are key players in this pathway, among which ATG5 is indispensable in both canonical and non-canonical autophagy. Recent studies demonstrate that ATG5 modulates the immune system and crosstalks with apoptosis. However, our knowledge of the pathogenesis and regulatory mechanisms of autophagy in various immune related diseases is lacking. Thus, a deeper understanding of ATG5's role in the autophagy mechanism may shed light on the link between autophagy and the immune response, and lead to the development of new therapies for autoimmune diseases and autoinflammatory diseases. In this focused review, we discuss the latest insights into the role of ATG5 in autoimmunity. Although these studies are at a relatively early stage, ATG5 may eventually come to be regarded as a “guardian of immune integrity.” Notably, accumulating evidence indicates that other ATG genes may have similar functions.
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Affiliation(s)
- Xin Ye
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
| | - Xu-Jie Zhou
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
| | - Hong Zhang
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
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78
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Folkerts H, Hilgendorf S, Vellenga E, Bremer E, Wiersma VR. The multifaceted role of autophagy in cancer and the microenvironment. Med Res Rev 2018; 39:517-560. [PMID: 30302772 PMCID: PMC6585651 DOI: 10.1002/med.21531] [Citation(s) in RCA: 140] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 07/12/2018] [Accepted: 07/18/2018] [Indexed: 12/12/2022]
Abstract
Autophagy is a crucial recycling process that is increasingly being recognized as an important factor in cancer initiation, cancer (stem) cell maintenance as well as the development of resistance to cancer therapy in both solid and hematological malignancies. Furthermore, it is being recognized that autophagy also plays a crucial and sometimes opposing role in the complex cancer microenvironment. For instance, autophagy in stromal cells such as fibroblasts contributes to tumorigenesis by generating and supplying nutrients to cancerous cells. Reversely, autophagy in immune cells appears to contribute to tumor‐localized immune responses and among others regulates antigen presentation to and by immune cells. Autophagy also directly regulates T and natural killer cell activity and is required for mounting T‐cell memory responses. Thus, within the tumor microenvironment autophagy has a multifaceted role that, depending on the context, may help drive tumorigenesis or may help to support anticancer immune responses. This multifaceted role should be taken into account when designing autophagy‐based cancer therapeutics. In this review, we provide an overview of the diverse facets of autophagy in cancer cells and nonmalignant cells in the cancer microenvironment. Second, we will attempt to integrate and provide a unified view of how these various aspects can be therapeutically exploited for cancer therapy.
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Affiliation(s)
- Hendrik Folkerts
- Department of Hematology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Susan Hilgendorf
- Department of Hematology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Edo Vellenga
- Department of Hematology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Edwin Bremer
- Department of Hematology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Valerie R Wiersma
- Department of Hematology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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79
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Mani K, Javaheri A, Diwan A. Lysosomes Mediate Benefits of Intermittent Fasting in Cardiometabolic Disease: The Janitor Is the Undercover Boss. Compr Physiol 2018; 8:1639-1667. [PMID: 30215867 DOI: 10.1002/cphy.c180005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Adaptive responses that counter starvation have evolved over millennia to permit organismal survival, including changes at the level of individual organelles, cells, tissues, and organ systems. In the past century, a shift has occurred away from disease caused by insufficient nutrient supply toward overnutrition, leading to obesity and diabetes, atherosclerosis, and cardiometabolic disease. The burden of these diseases has spurred interest in fasting strategies that harness physiological responses to starvation, thus limiting tissue injury during metabolic stress. Insights gained from animal and human studies suggest that intermittent fasting and chronic caloric restriction extend lifespan, decrease risk factors for cardiometabolic and inflammatory disease, limit tissue injury during myocardial stress, and activate a cardioprotective metabolic program. Acute fasting activates autophagy, an intricately orchestrated lysosomal degradative process that sequesters cellular constituents for degradation, and is critical for cardiac homeostasis during fasting. Lysosomes are dynamic cellular organelles that function as incinerators to permit autophagy, as well as degradation of extracellular material internalized by endocytosis, macropinocytosis, and phagocytosis. The last decade has witnessed an explosion of knowledge that has shaped our understanding of lysosomes as central regulators of cellular metabolism and the fasting response. Intriguingly, lysosomes also store nutrients for release during starvation; and function as a nutrient sensing organelle to couple activation of mammalian target of rapamycin to nutrient availability. This article reviews the evidence for how the lysosome, in the guise of a janitor, may be the "undercover boss" directing cellular processes for beneficial effects of intermittent fasting and restoring homeostasis during feast and famine. © 2018 American Physiological Society. Compr Physiol 8:1639-1667, 2018.
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Affiliation(s)
- Kartik Mani
- John Cochran VA Medical Center, St. Louis, Missouri, USA.,Center for Cardiovascular Research and Division of Cardiology in Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Ali Javaheri
- Center for Cardiovascular Research and Division of Cardiology in Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Abhinav Diwan
- Center for Cardiovascular Research and Division of Cardiology in Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, USA
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80
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Smith MD, Wilkinson S. CCPG1, an unconventional cargo receptor for ER-phagy, maintains pancreatic acinar cell health. Mol Cell Oncol 2018; 5:e1441631. [PMID: 30263939 PMCID: PMC6154861 DOI: 10.1080/23723556.2018.1441631] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 01/23/2018] [Accepted: 01/24/2018] [Indexed: 06/08/2023]
Abstract
ER stress-mediated induction of a new vertebrate-specific autophagy cargo receptor, CCPG1 (cell-cycle progression gene 1), drives degradation of endoplasmic reticulum. CCPG1 acts via ATG8-family interaction and, non-canonically, via discrete interactions with FIP200. CCPG1 ameliorates ER stress in the exocrine pancreas. This has potential implications for inflammation and cancer, discussed here.
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Affiliation(s)
- Matthew D. Smith
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, EH4 2XR, United Kingdom
| | - Simon Wilkinson
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, EH4 2XR, United Kingdom
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81
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Lüningschrör P, Sendtner M. Autophagy in the presynaptic compartment. Curr Opin Neurobiol 2018; 51:80-85. [DOI: 10.1016/j.conb.2018.02.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/20/2018] [Accepted: 02/26/2018] [Indexed: 11/28/2022]
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82
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Cassidy LD, Young ARJ, Pérez-Mancera PA, Nimmervoll B, Jaulim A, Chen HC, McIntyre DJO, Brais R, Ricketts T, Pacey S, De La Roche M, Gilbertson RJ, Rubinsztein DC, Narita M. A novel Atg5-shRNA mouse model enables temporal control of Autophagy in vivo. Autophagy 2018; 14:1256-1266. [PMID: 29999454 PMCID: PMC6103714 DOI: 10.1080/15548627.2018.1458172] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 03/14/2018] [Accepted: 03/21/2018] [Indexed: 01/23/2023] Open
Abstract
Macroautophagy/autophagy is an evolutionarily conserved catabolic pathway whose modulation has been linked to diverse disease states, including age-associated disorders. Conventional and conditional whole-body knockout mouse models of key autophagy genes display perinatal death and lethal neurotoxicity, respectively, limiting their applications for in vivo studies. Here, we have developed an inducible shRNA mouse model targeting Atg5, allowing us to dynamically inhibit autophagy in vivo, termed ATG5i mice. The lack of brain-associated shRNA expression in this model circumvents the lethal phenotypes associated with complete autophagy knockouts. We show that ATG5i mice recapitulate many of the previously described phenotypes of tissue-specific knockouts. While restoration of autophagy in the liver rescues hepatomegaly and other pathologies associated with autophagy deficiency, this coincides with the development of hepatic fibrosis. These results highlight the need to consider the potential side effects of systemic anti-autophagy therapies.
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Affiliation(s)
- Liam D. Cassidy
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Andrew RJ. Young
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | | | - Birgit Nimmervoll
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Adil Jaulim
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Hung-Chang Chen
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | | | - Rebecca Brais
- Department of Histopathology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Thomas Ricketts
- Cambridge Institute for Medical Research, Department of Medical Genetics, Cambridge, UK
| | - Simon Pacey
- Department of Oncology, University of Cambridge, Cambridge, UK
| | - Maike De La Roche
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | | | - David C. Rubinsztein
- Cambridge Institute for Medical Research, Department of Medical Genetics, Cambridge, UK
- UK Dementia Research Institute, Cambridge Biomedical Campus, Cambridge Biomedical Campus, Cambridge, UK
| | - Masashi Narita
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
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83
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Neuronal Preconditioning Requires the Mitophagic Activity of C-terminus of HSC70-Interacting Protein. J Neurosci 2018; 38:6825-6840. [PMID: 29934347 DOI: 10.1523/jneurosci.0699-18.2018] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/08/2018] [Accepted: 06/13/2018] [Indexed: 11/21/2022] Open
Abstract
The C terminus of HSC70-interacting protein (CHIP, STUB1) is a ubiquitously expressed cytosolic E3-ubiquitin ligase. CHIP-deficient mice exhibit cardiovascular stress and motor dysfunction before premature death. This phenotype is more consistent with animal models in which master regulators of autophagy are affected rather than with the mild phenotype of classic E3-ubiquitin ligase mutants. The cellular and biochemical events that contribute to neurodegeneration and premature aging in CHIP KO models remain poorly understood. Electron and fluorescent microscopy demonstrates that CHIP deficiency is associated with greater numbers of mitochondria, but these organelles are swollen and misshapen. Acute bioenergetic stress triggers CHIP induction and relocalization to mitochondria, where it plays a role in the removal of damaged organelles. This mitochondrial clearance is required for protection following low-level bioenergetic stress in neurons. CHIP expression overlaps with stabilization of the redox stress sensor PTEN-inducible kinase 1 (PINK1) and is associated with increased LC3-mediated mitophagy. Introducing human promoter-driven vectors with mutations in either the E3 ligase or tetracopeptide repeat domains of CHIP in primary neurons derived from CHIP-null animals enhances CHIP accumulation at mitochondria. Exposure to autophagy inhibitors suggests that the increase in mitochondrial CHIP is likely due to diminished clearance of these CHIP-tagged organelles. Proteomic analysis of WT and CHIP KO mouse brains (four male, four female per genotype) reveals proteins essential for maintaining energetic, redox, and mitochondrial homeostasis undergo significant genotype-dependent expression changes. Together, these data support the use of CHIP-deficient animals as a predictive model of age-related degeneration with selective neuronal proteotoxicity and mitochondrial failure.SIGNIFICANCE STATEMENT Mitochondria are recognized as central determinants of neuronal function and survival. We demonstrate that C terminus of HSC70-Interacting Protein (CHIP) is critical for neuronal responses to stress. CHIP upregulation and localization to mitochondria is required for mitochondrial autophagy (mitophagy). Unlike other disease-associated E3 ligases such as Parkin and Mahogunin, CHIP controls homeostatic and stress-induced removal of mitochondria. Although CHIP deletion results in greater numbers of mitochondria, these organelles have distorted inner membranes without clear cristae. Neuronal cultures derived from animals lacking CHIP are more vulnerable to acute injuries and transient loss of CHIP renders neurons incapable of mounting a protective response after low-level stress. Together, these data suggest that CHIP is an essential regulator of mitochondrial number, cell signaling, and survival.
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84
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Gao F, Li G, Liu C, Gao H, Wang H, Liu W, Chen M, Shang Y, Wang L, Shi J, Xia W, Jiao J, Gao F, Li J, Chen L, Li W. Autophagy regulates testosterone synthesis by facilitating cholesterol uptake in Leydig cells. J Cell Biol 2018; 217:2103-2119. [PMID: 29618492 PMCID: PMC5987723 DOI: 10.1083/jcb.201710078] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 02/01/2018] [Accepted: 03/05/2018] [Indexed: 12/12/2022] Open
Abstract
High levels of autophagy exist in Leydig cells of the testis, but its physiological function is unknown. Gao et al. now show that autophagy promotes uptake of cholesterol, an essential precursor for testosterone synthesis, by removing the NHERF2 negative regulator of the high-density lipoprotein receptor SR-BI. Testosterone is indispensable for sexual development and maintaining male characteristics, and deficiency of this hormone results in primary or late-onset hypogonadism (LOH). Testosterone is primarily produced in Leydig cells, where autophagy has been reported to be extremely active. However, the functional role of autophagy in testosterone synthesis remains unknown. In this study, we show that steroidogenic cell–specific disruption of autophagy influenced the sexual behavior of aging male mice because of a reduction in serum testosterone, which is similar to the symptoms of LOH. The decline in testosterone was caused mainly by a defect in cholesterol uptake in autophagy-deficient Leydig cells. Further studies revealed that once autophagic flux was disrupted, Na+/H+ exchanger regulatory factor 2 (NHERF2) accumulated in Leydig cells, resulting in the down-regulation of scavenger receptor class B, type I (SR-BI) and eventually leading to insufficient cholesterol supply. Collectively, these results reveal that autophagy promotes cholesterol uptake into Leydig cells by eliminating NHERF2, suggesting that dysfunction of autophagy might be causal in the loss of testosterone production in some patients.
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Affiliation(s)
- Fengyi Gao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,School of Biotechnology and Food, Shangqiu Normal University, Shangqiu, China
| | - Guoping Li
- The Ministry of Health Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, China
| | - Chao Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Hui Gao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Hao Wang
- Reproductive and Genetic Medical Center, Department of Urology, Peking University First Hospital, Beijing, China
| | - Weixiao Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Min Chen
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Yongliang Shang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Lina Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jian Shi
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Wenlong Xia
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jianwei Jiao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Fei Gao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Jian Li
- The Ministry of Health Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, China
| | - Liang Chen
- Reproductive and Genetic Medical Center, Department of Urology, Peking University First Hospital, Beijing, China
| | - Wei Li
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China .,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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85
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Azarnia Tehran D, Kuijpers M, Haucke V. Presynaptic endocytic factors in autophagy and neurodegeneration. Curr Opin Neurobiol 2018; 48:153-159. [DOI: 10.1016/j.conb.2017.12.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 12/01/2017] [Accepted: 12/22/2017] [Indexed: 12/31/2022]
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86
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Kulkarni VV, Maday S. Compartment-specific dynamics and functions of autophagy in neurons. Dev Neurobiol 2017; 78:298-310. [PMID: 29197160 DOI: 10.1002/dneu.22562] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 11/13/2017] [Accepted: 11/16/2017] [Indexed: 02/06/2023]
Abstract
Autophagy is a lysosomal degradation pathway that is critical to maintaining neuronal homeostasis and viability. Autophagy sequesters damaged and aged cellular components from the intracellular environment, and shuttles these diverse macromolecules to lysosomes for destruction. This active surveillance of the quality of the cytoplasm and organelles is essential in neurons to sustain their long-term functionality and viability. Indeed, defective autophagy is linked to neurodevelopmental abnormalities and neurodegeneration in mammals. Here, we review the mechanisms of autophagy in neurons and functional roles for autophagy in neuronal homeostasis. We focus on the compartment-specific dynamics of autophagy in neurons, and how autophagy might perform non-canonical functions critical for neurons. We suggest the existence of multiple populations of autophagosomes with compartment-specific functions important for neural activity and function. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 298-310, 2018.
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Affiliation(s)
- Vineet Vinay Kulkarni
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, 19104
| | - Sandra Maday
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, 19104
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87
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Abstract
Autophagy is an evolutionarily conserved mechanism by which cytoplasmic elements are degraded intracellularly. Autophagy has also emerged as a major regulator of cardiac homeostasis and function. Autophagy preserves cardiac structure and function under baseline conditions and is activated during stress, limiting damage under most conditions. It reduces injury and preserves cardiac function during ischemia. It also reduces chronic ischemic remodeling and mediates the cardiac adaptation to pressure overload by restricting misfolded protein accumulation, mitochondrial dysfunction, and oxidative stress. Impairment of autophagy is involved in the development of diabetes and aging-induced cardiac abnormalities. Autophagy defects contribute to the development of cardiac proteinopathy and doxorubicin-induced cardiomyopathy. However, massive activation of autophagy may be detrimental for the heart in certain stress conditions, such as reperfusion injury. In this review, we discuss recent evidence supporting the important role of autophagy and mitophagy in the regulation of cardiac homeostasis and adaptation to stress.
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Affiliation(s)
- Sebastiano Sciarretta
- Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, 04100 Latina, Italy.,Department of AngioCardioNeurology, IRCCS Neuromed, 86077 Pozzilli, Italy
| | - Yasuhiro Maejima
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, Graduate School of Medical and Dental Sciences, Tokyo 113-8510, Japan
| | - Daniela Zablocki
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA;
| | - Junichi Sadoshima
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA;
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88
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Abstract
Discovery of yeast autophagy-related (ATG) genes and subsequent identification of their homologs in other organisms have enabled researchers to investigate physiological functions of macroautophagy/autophagy using genetic techniques. Specific identification of autophagy-related structures is important to evaluate autophagic activity, and specific ablation of autophagy-related genes is a critical means to determine the requirements of autophagy. Here, we review currently available mouse models, particularly focusing on autophagy (and mitophagy) indicator models and systemic autophagy-related gene-knockout mouse models.
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Affiliation(s)
- Akiko Kuma
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
- Division of Cancer Biology, National Cancer Center Research Institute, Tokyo, Japan
- CONTACT Akiko Kuma Division of Cancer Biology, National Cancer Center Research Institute, 5-1-1 Tsukiji Chuo-ku, Tokyo 104-0045 Japan
| | - Masaaki Komatsu
- Department of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
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89
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Mainz L, Rosenfeldt MT. Autophagy and cancer - insights from mouse models. FEBS J 2017; 285:792-808. [PMID: 28921866 DOI: 10.1111/febs.14274] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/10/2017] [Accepted: 09/13/2017] [Indexed: 01/09/2023]
Abstract
(Macro-)autophagy is an evolutionary conserved 'self-digestion program' that serves to maintain cellular metabolism and is implicated in many pathological processes such as cancer. In recent years, an increasing number of studies in murine cancer models have provided a plethora of sometimes conflicting results about the role of autophagy in cancer biology. This review summarizes these studies and raises awareness that there are situations in which autophagy blockage might indeed reduce tumor growth, but that sometimes the exact opposite is the case. It is therefore vital to mimic patient conditions in preclinical mouse experiments as thoroughly as possible before commencing clinical trials.
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Affiliation(s)
- Laura Mainz
- Institute for Pathology, Germany & Comprehensive Cancer Center Mainfranken, University of Wuerzburg, Germany
| | - Mathias T Rosenfeldt
- Institute for Pathology, Germany & Comprehensive Cancer Center Mainfranken, University of Wuerzburg, Germany
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90
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Pharmacological modulation of autophagy: therapeutic potential and persisting obstacles. Nat Rev Drug Discov 2017; 16:487-511. [PMID: 28529316 DOI: 10.1038/nrd.2017.22] [Citation(s) in RCA: 600] [Impact Index Per Article: 85.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Autophagy is central to the maintenance of organismal homeostasis in both physiological and pathological situations. Accordingly, alterations in autophagy have been linked to clinically relevant conditions as diverse as cancer, neurodegeneration and cardiac disorders. Throughout the past decade, autophagy has attracted considerable attention as a target for the development of novel therapeutics. However, such efforts have not yet generated clinically viable interventions. In this Review, we discuss the therapeutic potential of autophagy modulators, analyse the obstacles that have limited their development and propose strategies that may unlock the full therapeutic potential of autophagy modulation in the clinic.
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91
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Lassen KG, Xavier RJ. Genetic control of autophagy underlies pathogenesis of inflammatory bowel disease. Mucosal Immunol 2017; 10:589-597. [PMID: 28327616 PMCID: PMC6069523 DOI: 10.1038/mi.2017.18] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 02/19/2017] [Indexed: 02/04/2023]
Abstract
Autophagy contributes to cellular homeostasis in the face of nutrient deprivation and other cellular stresses. Cell type-specific functions for autophagy are critical in maintaining homeostasis at both the tissue level and at the whole-organism level. Recent work has highlighted the ways in which human genetic variants modulate autophagy to alter epithelial and immune responses in inflammatory bowel disease.
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Affiliation(s)
- K G Lassen
- Broad Institute, Cambridge, Massachusetts, USA
- Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - R J Xavier
- Broad Institute, Cambridge, Massachusetts, USA
- Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, USA
- Gastrointestinal Unit and Center for the Study of Inflammatory Bowel Disease, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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92
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Takayama K, Matsuura A, Itakura E. Dissection of ubiquitinated protein degradation by basal autophagy. FEBS Lett 2017; 591:1199-1211. [PMID: 28369861 PMCID: PMC5435929 DOI: 10.1002/1873-3468.12641] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 03/16/2017] [Accepted: 03/25/2017] [Indexed: 11/23/2022]
Abstract
Basal autophagy plays an essential role as a protein quality control system. Although it has been demonstrated that the loss of autophagy results in the accumulation of ubiquitin‐positive aggregates and the development of neurodegenerative diseases, the precise autophagy substrate(s) remain unclear. Here, we determined whether ubiquitinated proteins are direct substrates for basal autophagy using a fluorescent ratiometric probe for ubiquitin. We show that the degradation of polyubiquitinated proteins is not dependent on basal autophagy. Although ubiquitin‐positive aggregates are observed in autophagy knockout cultured cells, the aggregates consist of soluble and mobile polyubiquitinated proteins, which are trapped by p62 without an increase in the total amount of ubiquitinated proteins. These results suggest that ubiquitinated proteins are not major targets for basal autophagy.
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Affiliation(s)
- Kaori Takayama
- Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Japan
| | - Akira Matsuura
- Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Japan
| | - Eisuke Itakura
- Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Japan
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93
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Towers CG, Thorburn A. Therapeutic Targeting of Autophagy. EBioMedicine 2016; 14:15-23. [PMID: 28029600 PMCID: PMC5161418 DOI: 10.1016/j.ebiom.2016.10.034] [Citation(s) in RCA: 211] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 10/20/2016] [Accepted: 10/20/2016] [Indexed: 01/19/2023] Open
Abstract
Autophagy is a catabolic process that facilitates nutrient recycling via degradation of damaged organelles and proteins through lysosomal mediated degradation. Alterations in this complex, and tightly regulated process, lead to disease. Autophagy is widely accepted as cytoprotective against neurodegenerative diseases and a variety of clinical interventions are moving forward to increase autophagy as a therapeutic intervention. Autophagy has both positive and negative roles in cancer and this has led to controversy over whether or how autophagy manipulation should be attempted in cancer therapy. Nevertheless, cancer is the disease where most current activity in trying to manipulate autophagy for therapy is taking place and dozens of clinical trials are using autophagy inhibition with Chloroquine or Hydroxychloroquine in combination with other drugs for the treatment of multiple neoplasms. Here, we review recent literature implicating autophagy in neurodegenerative diseases and cancer and highlight some of the opportunities, controversies and potential pitfalls of therapeutically targeting autophagy.
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Affiliation(s)
- Christina G Towers
- Department of Pharmacology, University of Colorado School of Medicine, 12801 E. 17th Ave, Aurora, CO 80045, USA
| | - Andrew Thorburn
- Department of Pharmacology, University of Colorado School of Medicine, 12801 E. 17th Ave, Aurora, CO 80045, USA.
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