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Wang L, Klionsky DJ, Shen HM. The emerging mechanisms and functions of microautophagy. Nat Rev Mol Cell Biol 2023; 24:186-203. [PMID: 36097284 DOI: 10.1038/s41580-022-00529-z] [Citation(s) in RCA: 105] [Impact Index Per Article: 105.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2022] [Indexed: 02/08/2023]
Abstract
'Autophagy' refers to an evolutionarily conserved process through which cellular contents, such as damaged organelles and protein aggregates, are delivered to lysosomes for degradation. Different forms of autophagy have been described on the basis of the nature of the cargoes and the means used to deliver them to lysosomes. At present, the prevailing categories of autophagy in mammalian cells are macroautophagy, microautophagy and chaperone-mediated autophagy. The molecular mechanisms and biological functions of macroautophagy and chaperone-mediated autophagy have been extensively studied, but microautophagy has received much less attention. In recent years, there has been a growth in research on microautophagy, first in yeast and then in mammalian cells. Here we review this form of autophagy, focusing on selective forms of microautophagy. We also discuss the upstream regulatory mechanisms, the crosstalk between macroautophagy and microautophagy, and the functional implications of microautophagy in diseases such as cancer and neurodegenerative disorders in humans. Future research into microautophagy will provide opportunities to develop novel interventional strategies for autophagy- and lysosome-related diseases.
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Affiliation(s)
- Liming Wang
- School of Biomedical Sciences, Hunan University, Changsha, China
| | - Daniel J Klionsky
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
| | - Han-Ming Shen
- Faculty of Health Sciences, Ministry of Education Frontiers Science Center for Precision Oncology, University of Macau, Macau, China. .,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
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2
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Konstantinidis G, Tavernarakis N. Autophagy of the Nucleus in Health and Disease. Front Cell Dev Biol 2022; 9:814955. [PMID: 35047516 PMCID: PMC8762222 DOI: 10.3389/fcell.2021.814955] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 12/06/2021] [Indexed: 12/27/2022] Open
Abstract
Nucleophagy is an organelle-selective subtype of autophagy that targets nuclear material for degradation. The macroautophagic delivery of micronuclei to the vacuole, together with the nucleus-vacuole junction-dependent microautophagic degradation of nuclear material, were first observed in yeast. Nuclear pore complexes and ribosomal DNA are typically excluded during conventional macronucleophagy and micronucleophagy, indicating that degradation of nuclear cargo is tightly regulated. In mammals, similarly to other autophagy subtypes, nucleophagy is crucial for cellular differentiation and development, in addition to enabling cells to respond to various nuclear insults and cell cycle perturbations. A common denominator of all nucleophagic processes characterized in diverse organisms is the dependence on the core autophagic machinery. Here, we survey recent studies investigating the autophagic processing of nuclear components. We discuss nucleophagic events in the context of pathology, such as neurodegeneration, cancer, DNA damage, and ageing.
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Affiliation(s)
- Georgios Konstantinidis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Greece.,Department of Basic Sciences, School of Medicine, University of Crete, Heraklion, Greece
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3
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Moon EJ, Petersson K, Oleina MM. The importance of hypoxia in radiotherapy for the immune response, metastatic potential and FLASH-RT. Int J Radiat Biol 2022; 98:439-451. [PMID: 34726575 PMCID: PMC7612434 DOI: 10.1080/09553002.2021.1988178] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE Hypoxia (low oxygen) is a common feature of solid tumors that has been intensely studied for more than six decades. Here we review the importance of hypoxia to radiotherapy with a particular focus on the contribution of hypoxia to immune responses, metastatic potential and FLASH radiotherapy, active areas of research by leading women in the field. CONCLUSION Although hypoxia-driven metastasis and immunosuppression can negatively impact clinical outcome, understanding these processes can also provide tumor-specific vulnerabilities that may be therapeutically exploited. The different oxygen tensions present in tumors and normal tissues may underpin the beneficial FLASH sparing effect seen in normal tissue and represents a perfect example of advances in the field that can leverage tumor hypoxia to improve future radiotherapy treatments.
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Affiliation(s)
- Eui Jung Moon
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, OX3 7DQ, UK,Equal Contribution and to whom correspondence should be addressed. ; :
| | - Kristoffer Petersson
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, OX3 7DQ, UK,Radiation Physics, Department of Haematology, Oncology and Radiation Physics, Skåne University Hospital, Sweden,Equal Contribution and to whom correspondence should be addressed. ; :
| | - Monica M. Oleina
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, OX3 7DQ, UK,Equal Contribution and to whom correspondence should be addressed. ; :
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4
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Liu C, Gu L, Ding J, Meng Q, Li N, Dai G, Li Q, Wu X. Autophagy in skin barrier and immune-related skin diseases. J Dermatol 2021; 48:1827-1837. [PMID: 34655245 DOI: 10.1111/1346-8138.16185] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 09/15/2021] [Accepted: 09/24/2021] [Indexed: 12/15/2022]
Abstract
Autophagy is a process which is highly conserved in eukaryotes to degrade or recycle cytoplasmic components through lysosomes to maintain cellular homeostasis. Recent studies have shown that autophagy also plays critical roles in cell apoptosis, inflammation, pathogen clearance, and so on under stressed conditions and thereby has been linked to a variety of human disorders. The skin is the largest organ of the body and serves as the first line of defense against environmental insult. Skin as a nutrient-poor environment requires recycling of limited resources via the autophagy machinery to maintain homeostasis. Therefore, dysregulation of autophagy has been linked to skin diseases. In this review, we describe the molecular machinery and regulation of autophagy, discuss its role in keratinocytes and skin barrier, skin immune cells, and immune-related skin diseases including autoimmune skin disorders, allergic skin diseases, infectious skin disorders, and antitumor immunity against skin tumor. Finally, we highlight the potential of autophagy as a therapeutic target for immune-related skin diseases, and delivery of autophagy-related molecules (such as inducers, inhibitors, or nucleic acid molecules) by virtue of physical materials (such as nanoparticles) or biological materials (such as peptides) to skin topically may obtain clinical benefits in immune-related skin diseases. Moreover, developing autophagy-related gene product-based biomarkers may be promising to diagnose immune-related skin diseases.
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Affiliation(s)
- Chi Liu
- Department of Geriatrics Center & National Clinical Research Center for Aging and Medicine, Jing'an District Centre Hospital of Shanghai, Fudan University, Shanghai, China.,Department of Cardiology, School of Medicine, Tongji Hospital, Tongji University, Shanghai, China
| | - Lei Gu
- Department of Internal Medicine, Shanghai Shende Hospital, Shanghai, China
| | - Jie Ding
- Department of Gerontology, Jing'an District Centre Hospital of Shanghai, Fudan University, Shanghai, China
| | - Qianchao Meng
- Innovation Research Institute of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Nan Li
- Department of Geriatrics Center & National Clinical Research Center for Aging and Medicine, Jing'an District Centre Hospital of Shanghai, Fudan University, Shanghai, China
| | - Guifeng Dai
- Department of Geriatrics Center & National Clinical Research Center for Aging and Medicine, Jing'an District Centre Hospital of Shanghai, Fudan University, Shanghai, China
| | - Qinying Li
- Department of Rehabilitation Medicine, Jing'an District Center Hospital of Shanghai, Fudan University, Shanghai, China
| | - Xueyong Wu
- Department of Geriatrics Center & National Clinical Research Center for Aging and Medicine, Jing'an District Centre Hospital of Shanghai, Fudan University, Shanghai, China
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5
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Mijaljica D, Klionsky DJ. The necessity of nucleophagic modality. Autophagy 2021; 18:443-448. [PMID: 34643473 DOI: 10.1080/15548627.2021.1971380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Nucleophagy, the selective subtype of autophagy that predominantly targets only a selected and (nonessential) portion of the nucleus, and rarely the nucleus in its entirety, for degradation, reinforces the paradigm that nucleophagy recycling is a meticulous and highly delicate process guarded by fail-safe mechanisms. Our goal in this commentary is to encourage autophagy researchers and other scientists to explore nucleophagy blind spots and gain advanced insights into the diverse roles of this process and its selective modality as they pertain to intranuclear quality control and cellular homeostasis. Identifying and deciphering nucleophagic signaling, regulation, molecular mechanism(s) and its mediators, cargo composition and nuclear membrane dynamics under numerous physiological and/or pathological settings will provide important advances in our understanding of this critical type of organelle-selective autophagy.Abbreviations: INM, inner nuclear membrane; LN, late nucleophagy; mRNA, messenger RNA; NE, nuclear envelope; NL, nuclear lamina; NPC(s), nuclear pore complex(es); NVJ(s), nucleus-vacuole junction(s); ONM, outer nuclear membrane; PMN, piecemeal microautophagy of the nucleus; PND, programmed nuclear death; PNuD, programmed nuclear destruction; rDNA/rRNA, ribosomal DNA/RNA.
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Affiliation(s)
| | - Daniel J Klionsky
- Department of Molecular, Cellular, and Developmental Biology, and the Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
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6
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Molecular mechanisms of mammalian autophagy. Biochem J 2021; 478:3395-3421. [PMID: 34554214 DOI: 10.1042/bcj20210314] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/19/2021] [Accepted: 07/28/2021] [Indexed: 02/06/2023]
Abstract
The ubiquitin-proteasome pathway (UPP) and autophagy play integral roles in cellular homeostasis. As part of their normal life cycle, most proteins undergo ubiquitination for some form of redistribution, localization and/or functional modulation. However, ubiquitination is also important to the UPP and several autophagic processes. The UPP is initiated after specific lysine residues of short-lived, damaged or misfolded proteins are conjugated to ubiquitin, which targets these proteins to proteasomes. Autophagy is the endosomal/lysosomal-dependent degradation of organelles, invading microbes, zymogen granules and macromolecules such as protein, carbohydrates and lipids. Autophagy can be broadly separated into three distinct subtypes termed microautophagy, chaperone-mediated autophagy and macroautophagy. Although autophagy was once thought of as non-selective bulk degradation, advancements in the field have led to the discovery of several selective forms of autophagy. Here, we focus on the mechanisms of primary and selective mammalian autophagy pathways and highlight the current knowledge gaps in these molecular pathways.
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7
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Pink1/PARK2/mROS-Dependent Mitophagy Initiates the Sensitization of Cancer Cells to Radiation. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:5595652. [PMID: 34306311 PMCID: PMC8279859 DOI: 10.1155/2021/5595652] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 05/26/2021] [Accepted: 06/20/2021] [Indexed: 01/10/2023]
Abstract
Autophagy plays a double-edged sword for cancer; particularly, mitophagy plays important roles in the selective degradation of damaged mitochondria. However, whether mitophagy is involved in killing effects of tumor cells by ionizing radiation (IR) and its underlying mechanism remain elusive. The purpose is to evaluate the effects of mitochondrial ROS (mROS) on autophagy after IR; furthermore, we hypothesized that KillerRed (KR) targeting mitochondria could induce mROS generation, subsequent mitochondrial depolarization, accumulation of Pink1, and recruitment of PARK2 to promote the mitophagy. Thereby, we would achieve a new strategy to enhance mROS accumulation and clarify the roles and mechanisms of radiosensitization by KR and IR. Our data demonstrated that IR might cause autophagy of both MCF-7 and HeLa cells, which is related to mitochondria and mROS, and the ROS scavenger N-acetylcysteine (NAC) could reduce the effects. Based on the theory, mitochondrial targeting vector sterile α- and HEAT/armadillo motif-containing protein 1- (Sarm1-) mtKR has been successfully constructed, and we found that ROS levels have significantly increased after light exposure. Furthermore, mitochondrial depolarization of HeLa cells was triggered, such as the decrease of Na+K+ ATPase, Ca2+Mg2+ ATPase, and mitochondrial respiratory complex I and III activities, and mitochondrial membrane potential (MMP) has significantly decreased, and voltage-dependent anion channel 1 (VDAC1) protein has significantly increased in the mitochondria. Additionally, HeLa cell proliferation was obviously inhibited, and the cell autophagic rates dramatically increased, which referred to the regulation of the Pink1/PARK2 pathway. These results indicated that mitophagy induced by mROS can initiate the sensitization of cancer cells to IR and might be regulated by the Pink1/PARK2 pathway.
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8
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Lee CP, Chen MR. Conquering the Nuclear Envelope Barriers by EBV Lytic Replication. Viruses 2021; 13:702. [PMID: 33919628 PMCID: PMC8073350 DOI: 10.3390/v13040702] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/14/2021] [Accepted: 04/14/2021] [Indexed: 12/14/2022] Open
Abstract
The nuclear envelope (NE) of eukaryotic cells has a highly structural architecture, comprising double lipid-bilayer membranes, nuclear pore complexes, and an underlying nuclear lamina network. The NE structure is held in place through the membrane-bound LINC (linker of nucleoskeleton and cytoskeleton) complex, spanning the inner and outer nuclear membranes. The NE functions as a barrier between the nucleus and cytoplasm and as a transverse scaffold for various cellular processes. Epstein-Barr virus (EBV) is a human pathogen that infects most of the world's population and is associated with several well-known malignancies. Within the nucleus, the replicated viral DNA is packaged into capsids, which subsequently egress from the nucleus into the cytoplasm for tegumentation and final envelopment. There is increasing evidence that viral lytic gene expression or replication contributes to the pathogenesis of EBV. Various EBV lytic proteins regulate and modulate the nuclear envelope structure in different ways, especially the viral BGLF4 kinase and the nuclear egress complex BFRF1/BFRF2. From the aspects of nuclear membrane structure, viral components, and fundamental nucleocytoplasmic transport controls, this review summarizes our findings and recently updated information on NE structure modification and NE-related cellular processes mediated by EBV.
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Affiliation(s)
- Chung-Pei Lee
- School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei 112303, Taiwan;
| | - Mei-Ru Chen
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei 100233, Taiwan
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9
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Abstract
Autophagy is an adaptive catabolic process functioning to promote cell survival in the event of inappropriate living conditions such as nutrient shortage and to cope with diverse cytotoxic insults. It is regarded as one of the key survival mechanisms of living organisms. Cells undergo autophagy to accomplish the lysosomal digestion of intracellular materials including damaged proteins, organelles, and foreign bodies, in a bulk, non-selective or a cargo-specific manner. Studies in the past decades have shed light on the association of autophagy pathways with various diseases and also highlighted the therapeutic value of autophagy modulation. Hence, it is crucial to develop effective approaches for monitoring intracellular autophagy dynamics, as a comprehensive account of methodology establishment is far from complete. In this review, we aim to provide an overview of the major current fluorescence-based techniques utilized for visualizing, sensing or measuring autophagic activities in cells or tissues, which are categorized firstly by targets detected and further by the types of fluorescence tools. We will mainly focus on the working mechanisms of these techniques, put emphasis on the insight into their roles in biomedical science and provide perspectives on the challenges and future opportunities in this field.
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Affiliation(s)
- Siyang Ding
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne Victoria 3086, Australia.
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10
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Almendáriz-Palacios C, Gillespie ZE, Janzen M, Martinez V, Bridger JM, Harkness TAA, Mousseau DD, Eskiw CH. The Nuclear Lamina: Protein Accumulation and Disease. Biomedicines 2020; 8:E188. [PMID: 32630170 PMCID: PMC7400325 DOI: 10.3390/biomedicines8070188] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/23/2020] [Accepted: 06/26/2020] [Indexed: 02/06/2023] Open
Abstract
Cellular health is reliant on proteostasis-the maintenance of protein levels regulated through multiple pathways modulating protein synthesis, degradation and clearance. Loss of proteostasis results in serious disease and is associated with aging. One proteinaceous structure underlying the nuclear envelope-the nuclear lamina-coordinates essential processes including DNA repair, genome organization and epigenetic and transcriptional regulation. Loss of proteostasis within the nuclear lamina results in the accumulation of proteins, disrupting these essential functions, either via direct interactions of protein aggregates within the lamina or by altering systems that maintain lamina structure. Here we discuss the links between proteostasis and disease of the nuclear lamina, as well as how manipulating specific proteostatic pathways involved in protein clearance could improve cellular health and prevent/reverse disease.
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Affiliation(s)
- Carla Almendáriz-Palacios
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada; (C.A.-P.); (V.M.)
| | - Zoe E. Gillespie
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada; (Z.E.G.); (M.J.); (T.A.A.H.)
| | - Matthew Janzen
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada; (Z.E.G.); (M.J.); (T.A.A.H.)
| | - Valeria Martinez
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada; (C.A.-P.); (V.M.)
| | - Joanna M. Bridger
- Centre for Genome Engineering and Maintenance, College of Health, Life and Medical Sciences, Brunel University London, Kingston Lane, Uxbridge UB8 3PH, UK;
| | - Troy A. A. Harkness
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada; (Z.E.G.); (M.J.); (T.A.A.H.)
| | - Darrell D. Mousseau
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK S7N 5A5, Canada;
| | - Christopher H. Eskiw
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada; (C.A.-P.); (V.M.)
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada; (Z.E.G.); (M.J.); (T.A.A.H.)
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11
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Kohler V, Aufschnaiter A, Büttner S. Closing the Gap: Membrane Contact Sites in the Regulation of Autophagy. Cells 2020; 9:E1184. [PMID: 32397538 PMCID: PMC7290522 DOI: 10.3390/cells9051184] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 12/14/2022] Open
Abstract
In all eukaryotic cells, intracellular organization and spatial separation of incompatible biochemical processes is established by individual cellular subcompartments in form of membrane-bound organelles. Virtually all of these organelles are physically connected via membrane contact sites (MCS), allowing interorganellar communication and a functional integration of cellular processes. These MCS coordinate the exchange of diverse metabolites and serve as hubs for lipid synthesis and trafficking. While this of course indirectly impacts on a plethora of biological functions, including autophagy, accumulating evidence shows that MCS can also directly regulate autophagic processes. Here, we focus on the nexus between interorganellar contacts and autophagy in yeast and mammalian cells, highlighting similarities and differences. We discuss MCS connecting the ER to mitochondria or the plasma membrane, crucial for early steps of both selective and non-selective autophagy, the yeast-specific nuclear-vacuolar tethering system and its role in microautophagy, the emerging function of distinct autophagy-related proteins in organellar tethering as well as novel MCS transiently emanating from the growing phagophore and mature autophagosome.
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Affiliation(s)
- Verena Kohler
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden;
| | - Andreas Aufschnaiter
- Department of Biochemistry and Biophysics, Stockholm University, 106 91 Stockholm, Sweden;
| | - Sabrina Büttner
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden;
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
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12
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Joshi V, Upadhyay A, Prajapati VK, Mishra A. How autophagy can restore proteostasis defects in multiple diseases? Med Res Rev 2020; 40:1385-1439. [PMID: 32043639 DOI: 10.1002/med.21662] [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: 06/28/2019] [Revised: 01/03/2020] [Accepted: 01/28/2020] [Indexed: 12/12/2022]
Abstract
Cellular evolution develops several conserved mechanisms by which cells can tolerate various difficult conditions and overall maintain homeostasis. Autophagy is a well-developed and evolutionarily conserved mechanism of catabolism, which endorses the degradation of foreign and endogenous materials via autolysosome. To decrease the burden of the ubiquitin-proteasome system (UPS), autophagy also promotes the selective degradation of proteins in a tightly regulated way to improve the physiological balance of cellular proteostasis that may get perturbed due to the accumulation of misfolded proteins. However, the diverse as well as selective clearance of unwanted materials and regulations of several cellular mechanisms via autophagy is still a critical mystery. Also, the failure of autophagy causes an increase in the accumulation of harmful protein aggregates that may lead to neurodegeneration. Therefore, it is necessary to address this multifactorial threat for in-depth research and develop more effective therapeutic strategies against lethal autophagy alterations. In this paper, we discuss the most relevant and recent reports on autophagy modulations and their impact on neurodegeneration and other complex disorders. We have summarized various pharmacological findings linked with the induction and suppression of autophagy mechanism and their promising preclinical and clinical applications to provide therapeutic solutions against neurodegeneration. The conclusion, key questions, and future prospectives sections summarize fundamental challenges and their possible feasible solutions linked with autophagy mechanism to potentially design an impactful therapeutic niche to treat neurodegenerative diseases and imperfect aging.
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Affiliation(s)
- Vibhuti Joshi
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Karwar, India
| | - Arun Upadhyay
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Karwar, India
| | - Vijay K Prajapati
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Ajmer, India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Karwar, India
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13
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Capitanchik C, Dixon CR, Swanson SK, Florens L, Kerr ARW, Schirmer EC. Analysis of RNA-Seq datasets reveals enrichment of tissue-specific splice variants for nuclear envelope proteins. Nucleus 2019; 9:410-430. [PMID: 29912636 PMCID: PMC7000147 DOI: 10.1080/19491034.2018.1469351] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Laminopathies yield tissue-specific pathologies, yet arise from mutation of ubiquitously-expressed genes. A little investigated hypothesis to explain this is that the mutated proteins or their partners have tissue-specific splice variants. To test this, we analyzed RNA-Seq datasets, finding novel isoforms or isoform tissue-specificity for: Lap2, linked to cardiomyopathy; Nesprin 2, linked to Emery-Dreifuss muscular dystrophy and Lmo7, that regulates the Emery-Dreifuss muscular dystrophy linked emerin gene. Interestingly, the muscle-specific Lmo7 exon is rich in serine phosphorylation motifs, suggesting regulatory function. Muscle-specific splice variants in non-nuclear envelope proteins linked to other muscular dystrophies were also found. Nucleoporins tissue-specific variants were found for Nup54, Nup133, Nup153 and Nup358/RanBP2. RT-PCR confirmed novel Lmo7 and RanBP2 variants and specific knockdown of the Lmo7 variantreduced myogenic index. Nuclear envelope proteins were enriched for tissue-specific splice variants compared to the rest of the genome, suggesting that splice variants contribute to its tissue-specific functions.
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Affiliation(s)
- Charlotte Capitanchik
- a The Wellcome Centre for Cell Biology and Institute of Cell Biology , University of Edinburgh , Edinburgh , UK
| | - Charles R Dixon
- a The Wellcome Centre for Cell Biology and Institute of Cell Biology , University of Edinburgh , Edinburgh , UK
| | - Selene K Swanson
- b Stowers Institute for Medical Research , Kansas City , MO , USA
| | - Laurence Florens
- b Stowers Institute for Medical Research , Kansas City , MO , USA
| | - Alastair R W Kerr
- a The Wellcome Centre for Cell Biology and Institute of Cell Biology , University of Edinburgh , Edinburgh , UK
| | - Eric C Schirmer
- a The Wellcome Centre for Cell Biology and Institute of Cell Biology , University of Edinburgh , Edinburgh , UK
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14
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rDNA Condensation Promotes rDNA Separation from Nucleolar Proteins Degraded for Nucleophagy after TORC1 Inactivation. Cell Rep 2019; 28:3423-3434.e2. [DOI: 10.1016/j.celrep.2019.08.059] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 06/12/2019] [Accepted: 08/20/2019] [Indexed: 12/20/2022] Open
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15
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Li Y, Jiang X, Zhang Y, Gao Z, Liu Y, Hu J, Hu X, Li L, Shi J, Gao N. Nuclear accumulation of UBC9 contributes to SUMOylation of lamin A/C and nucleophagy in response to DNA damage. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2019; 38:67. [PMID: 30744690 PMCID: PMC6371487 DOI: 10.1186/s13046-019-1048-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 01/17/2019] [Indexed: 12/28/2022]
Abstract
BACKGROUND Macroautophagy (hereafter referred to as autophagy) is an evolutionarily conserved intracellular mechanism for lysosomal degradation of damaged cellular components. The specific degradation of nuclear components by the autophagy pathway is called nucleophagy. Most studies have focused on autophagic turnover of cytoplasmic materials, and little is known about the role of autophagy in the degradation of nuclear components. METHODS Human MDA-MB-231 and MCF-7 breast cancer cell lines were used as model systems in vitro. Induction of nucleophagy by nuclear DNA leakage was determined by western blot and immunofluorescence analyses. The interaction and colocalization of LC3 and lamin A/C was determined by immunoprecipitation and immunofluorescence. The role of the SUMO E2 ligase, UBC9, on the regulation of SUMOylation of lamin A/C and nucleophagy was determined by siRNA silencing of UBC9, and analyzed by immunoprecipitation and immunofluorescence. RESULTS DNA damage induced nuclear accumulation of UBC9 ligase which resulted in SUMOylation of lamin A/C and that SUMOylation of this protein was required for the interaction between the autophagy protein LC3 and lamin A/C, which was required for nucleophagy. Knockdown of UBC9 prevented SUMOylation of lamin A/C and LC3-lamin A/C interaction. This attenuated nucleophagy which degraded nuclear components lamin A/C and leaked nuclear DNA mediated by DNA damage. CONCLUSIONS Our findings suggest that nuclear DNA leakage activates nucleophagy through UBC9-mediated SUMOylation of lamin A/C, leading to degradation of nuclear components including lamin A/C and leaked nuclear DNA.
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Affiliation(s)
- Yunong Li
- College of Pharmacy, Army Medical University, Chongqing, 400038, China
| | - Xiuxing Jiang
- College of Pharmacy, Army Medical University, Chongqing, 400038, China
| | - Yanhao Zhang
- College of Pharmacy, Army Medical University, Chongqing, 400038, China
| | - Ziyi Gao
- Greater Philadelphia Pharmacy, Philadelphia, USA
| | - Yanxia Liu
- College of Pharmacy, Army Medical University, Chongqing, 400038, China
| | - Jinjiao Hu
- College of Pharmacy, Army Medical University, Chongqing, 400038, China
| | - Xiaoye Hu
- College of Pharmacy, Army Medical University, Chongqing, 400038, China
| | - Lirong Li
- College of Pharmacy, Army Medical University, Chongqing, 400038, China
| | - Jingshan Shi
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China.
| | - Ning Gao
- College of Pharmacy, Army Medical University, Chongqing, 400038, China. .,Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China.
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16
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Veeran S, Cui G, Shu B, Yi X, Zhong G. Curcumin-induced autophagy and nucleophagy in Spodoptera frugiperda Sf9 insect cells occur via PI3K/AKT/TOR pathways. J Cell Biochem 2019; 120:2119-2137. [PMID: 30242882 DOI: 10.1002/jcb.27520] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 07/30/2018] [Indexed: 01/24/2023]
Abstract
Compounds from plants or microbes are important resources for new natural pesticides against a wide variety of pests. The growing attention on the role of autophagy (type II cell death) in regulation of insect toxicology has propelled researchers to investigate autophagic cell death pathways. Our previous study proved that the cytotoxic effect of curcumin in Spodoptera frugiperda cells is regulated by autophagy. However, the signaling pathways and molecular mechanisms had not been determined. The current study elucidates curcumin inhibition of survival signaling by blocking the activation of PI3K/AKT/TOR pathways to induce autophagy in S. frugiperda cells. The result demonstrates that nucleophagy associated with cell death following the curcumin treatment. Following the curcumin treatment, Atg8/LC3 immunostaining in both nucleus and cytoplasm was markedly increased. Further, messenger RNA expression level of Atg8 and Atg1 genes regulation by curcumin was examined using quantitative reverse transcription polymerase chain reaction, and the result exhibited increased level of expression after curcumin treatment in a time-dependent manner. Our current study provides new insights to the autophagy occurring via PI3K/AKT/TOR pathways in S. frugiperda Sf9 insect cells induced by curcumin. Taken together, our results show for the first time that curcumin induced nucleophagy in lepidopteron insect cell line.
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Affiliation(s)
- Sethuraman Veeran
- Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture, South China Agricultural University, Guangzhou, China.,Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, China
| | - Gaofeng Cui
- Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture, South China Agricultural University, Guangzhou, China.,Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, China
| | - Benshui Shu
- Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture, South China Agricultural University, Guangzhou, China.,Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, China
| | - Xin Yi
- Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture, South China Agricultural University, Guangzhou, China.,Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, China
| | - Guohua Zhong
- Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture, South China Agricultural University, Guangzhou, China.,Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, China
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17
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Liu GT, Kung HN, Chen CK, Huang C, Wang YL, Yu CP, Lee CP. Improving nuclear envelope dynamics by EBV BFRF1 facilitates intranuclear component clearance through autophagy. FASEB J 2018; 32:3968-3983. [PMID: 29481305 DOI: 10.1096/fj.201701253r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Although a vesicular nucleocytoplasmic transport system is believed to exist in eukaryotic cells, the features of this pathway are mostly unknown. Here, we report that the BFRF1 protein of the Epstein-Barr virus improves vesicular transport of nuclear envelope (NE) to facilitate the translocation and clearance of nuclear components. BFRF1 expression induces vesicles that selectively transport nuclear components to the cytoplasm. With the use of aggregation-prone proteins as tools, we found that aggregated nuclear proteins are dispersed when these BFRF1-induced vesicles are formed. BFRF1-containing vesicles engulf the NE-associated aggregates, exit through from the NE, and putatively fuse with autophagic vacuoles. Chemical treatment and genetic ablation of autophagy-related factors indicate that autophagosome formation and autophagy-linked FYVE protein-mediated autophagic proteolysis are involved in this selective clearance of nuclear proteins. Remarkably, vesicular transport, elicited by BFRF1, also attenuated nuclear aggregates accumulated in neuroblastoma cells. Accordingly, induction of NE-derived vesicles by BFRF1 facilitates nuclear protein translocation and clearance, suggesting that autophagy-coupled transport of nucleus-derived vesicles can be elicited for nuclear component catabolism in mammalian cells.-Liu, G.-T., Kung, H.-N., Chen, C.-K., Huang, C., Wang, Y.-L., Yu, C.-P., Lee, C.-P. Improving nuclear envelope dynamics by EBV BFRF1 facilitates intranuclear component clearance through autophagy.
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Affiliation(s)
- Guan-Ting Liu
- School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
| | - Hsiu-Ni Kung
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan; and
| | - Chung-Kuan Chen
- School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
| | - Cheng Huang
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yung-Li Wang
- School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
| | - Cheng-Pu Yu
- School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
| | - Chung-Pei Lee
- School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
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18
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Evolution of tools and methods for monitoring autophagic flux in mammalian cells. Biochem Soc Trans 2018; 46:97-110. [DOI: 10.1042/bst20170102] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 12/06/2017] [Accepted: 12/11/2017] [Indexed: 01/07/2023]
Abstract
Autophagy is an evolutionarily conserved lysosome-mediated degradation and recycling process, which functions in cellular homeostasis and stress adaptation. The process is highly dynamic and involves autophagosome synthesis, cargo recognition and transport, autophagosome–lysosome fusion, and cargo degradation. The multistep nature of autophagy makes it challenging to quantify, and it is important to consider not only the number of autophagosomes within a cell but also the autophagic degradative activity. The rate at which cargos are recognized, segregated, and degraded through the autophagy pathway is defined as autophagic flux. In practice, methods to measure autophagic flux typically evaluate the lysosome-mediated cargo degradation step by leveraging known autophagy markers such as MAP1LC3B (microtubule-associated proteins 1A/1B light chain 3 beta) or lysosome-dependent fluorescent agents. In this review, we summarize the tools and methods used in mammalian cultured cells pertaining to these two approaches, and highlight innovations that have led to their evolution in recent years. We also discuss the potential limitations of these approaches and recommend using a combination of strategies and multiple different autophagy markers to reliably evaluate autophagic flux in mammalian cells.
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19
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Zhou M, Ji H, Fu N, Chen L, Xia Y. Nucleophagy in Human Disease: Beyond the Physiological Role [Retraction]. TOHOKU J EXP MED 2018; 244:75-81. [DOI: 10.1620/tjem.244.75] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Ming Zhou
- Department of Hematology, Hunan Provincial People’s Hospital, The First Affiliated Hospital of Hunan Normal University
| | - Hongwen Ji
- Department of Anesthesiology, Transfusion Medicine, Fuwai Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College
| | - Nian Fu
- Department of Gastroenterology, Affiliated Nanhua Hospital, University of South China
| | - Linxi Chen
- Institute of Pharmacy and Pharmacology, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China
| | - Yong Xia
- Affiliated Hospital of Xiangnan University
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20
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Kisurina-Evgenieva OP, Sutiagina OI, Onishchenko GE. Biogenesis of Micronuclei. BIOCHEMISTRY (MOSCOW) 2017; 81:453-64. [PMID: 27297896 DOI: 10.1134/s0006297916050035] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The presence of micronuclei in a cell is an indicator of DNA damage and genetic instability. In this review, mechanisms of emergence of micronuclei, their functional activity, and pathways of elimination are discussed. It is supposed that morphological and functional varieties of micronuclei as well as their degradation pathways can be determined by the chromosomal material localized inside these cell structures.
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21
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Randolph ME, Phillips BL, Choo HJ, Vest KE, Vera Y, Pavlath GK. Pharyngeal Satellite Cells Undergo Myogenesis Under Basal Conditions and Are Required for Pharyngeal Muscle Maintenance. Stem Cells 2016; 33:3581-95. [PMID: 26178867 DOI: 10.1002/stem.2098] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 05/15/2015] [Accepted: 06/01/2015] [Indexed: 12/19/2022]
Abstract
The pharyngeal muscles of the nasal, oral, and laryngeal pharynxes are required for swallowing. Pharyngeal muscles are preferentially affected in some muscular dystrophies yet spared in others. Muscle stem cells, called satellite cells, may be critical factors in the development of pharyngeal muscle disorders; however, very little is known about pharyngeal satellite cells (PSC) and their role in pharyngeal muscles. We show that PSC are distinct from the commonly studied hindlimb satellite cells both transcriptionally and biologically. Under basal conditions PSC proliferate, progress through myogenesis, and fuse with pharyngeal myofibers. Furthermore, PSC exhibit biologic differences dependent on anatomic location in the pharynx. Importantly, PSC are required to maintain myofiber size and myonuclear number in pharyngeal myofibers. Together, these results demonstrate that PSC are critical for pharyngeal muscle maintenance and suggest that satellite cell impairment could contribute to pharyngeal muscle pathology associated with various muscular dystrophies and aging.
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Affiliation(s)
| | | | - Hyo-Jung Choo
- Department of Pharmacology, Emory University, Atlanta, Georgia, USA
| | - Katherine E Vest
- Department of Pharmacology, Emory University, Atlanta, Georgia, USA
| | - Yandery Vera
- Department of Pharmacology, Emory University, Atlanta, Georgia, USA
| | - Grace K Pavlath
- Department of Pharmacology, Emory University, Atlanta, Georgia, USA
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22
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Luo M, Zhao X, Song Y, Cheng H, Zhou R. Nuclear autophagy: An evolutionarily conserved mechanism of nuclear degradation in the cytoplasm. Autophagy 2016; 12:1973-1983. [PMID: 27541589 DOI: 10.1080/15548627.2016.1217381] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Macroautophagy/autophagy is a catabolic process that is essential for cellular homeostasis. Studies on autophagic degradation of cytoplasmic components have generated interest in nuclear autophagy. Although its mechanisms and roles have remained elusive, tremendous progress has been made toward understanding nuclear autophagy. Nuclear autophagy is evolutionarily conserved in eukaryotes that may target various nuclear components through a series of processes, including nuclear sensing, nuclear export, autophagic substrate encapsulation and autophagic degradation in the cytoplasm. However, the molecular processes and regulatory mechanisms involved in nuclear autophagy remain largely unknown. Numerous studies have highlighted the importance of nuclear autophagy in physiological and pathological processes such as cancer. This review focuses on current advances in nuclear autophagy and provides a summary of its research history and landmark discoveries to offer new perspectives.
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Affiliation(s)
- Majing Luo
- a Hubei Key Laboratory of Cell Homeostasis, Laboratory of Molecular and Developmental Genetics, College of Life Sciences , Wuhan University , Wuhan , China
| | - Xueya Zhao
- a Hubei Key Laboratory of Cell Homeostasis, Laboratory of Molecular and Developmental Genetics, College of Life Sciences , Wuhan University , Wuhan , China
| | - Ying Song
- a Hubei Key Laboratory of Cell Homeostasis, Laboratory of Molecular and Developmental Genetics, College of Life Sciences , Wuhan University , Wuhan , China
| | - Hanhua Cheng
- a Hubei Key Laboratory of Cell Homeostasis, Laboratory of Molecular and Developmental Genetics, College of Life Sciences , Wuhan University , Wuhan , China
| | - Rongjia Zhou
- a Hubei Key Laboratory of Cell Homeostasis, Laboratory of Molecular and Developmental Genetics, College of Life Sciences , Wuhan University , Wuhan , China
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23
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Kobayashi S. Choose Delicately and Reuse Adequately: The Newly Revealed Process of Autophagy. Biol Pharm Bull 2016; 38:1098-103. [PMID: 26235572 DOI: 10.1248/bpb.b15-00096] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Autophagy is a degradation system for intracellular components. One of the roles of autophagy is the prompt removal of damaged organelles. Another unique role is to supply resources that maintain metabolism in response to the cellular nutritional state. Precise management of all the components in the autophagic system is essential for cellular health. Especially important are the selectivity of target cargos for autophagy, and the coordination of autophagy with the lysosomal catabolic process. This review outlines our current understanding of autophagy and discusses potential therapeutic perspectives. Emphasis will be given to lysosomal function as a central controller of metabolism, and to selective autophagy as a key mechanism for the efficient removal of dysfunctional organelles.
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Affiliation(s)
- Satoru Kobayashi
- Department of Biomedical Sciences, New York Institute of Technology College of
Osteopathic Medicine
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24
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Meseroll RA, Cohen-Fix O. The Malleable Nature of the Budding Yeast Nuclear Envelope: Flares, Fusion, and Fenestrations. J Cell Physiol 2016; 231:2353-60. [PMID: 26909870 DOI: 10.1002/jcp.25355] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 02/19/2016] [Indexed: 11/10/2022]
Abstract
In eukaryotes, the nuclear envelope (NE) physically separates nuclear components and activities from rest of the cell. The NE also provides rigidity to the nucleus and contributes to chromosome organization. At the same time, the NE is highly dynamic; it must change shape and rearrange its components during development and throughout the cell cycle, and its morphology can be altered in response to mutation and disease. Here we focus on the NE of budding yeast, Saccharomyces cerevisiae, which has several unique features: it remains intact throughout the cell cycle, expands symmetrically during interphase, elongates during mitosis and, expands asymmetrically during mitotic delay. Moreover, its NE is safely breached during mating and when large structures, such as nuclear pore complexes and the spindle pole body, are embedded into its double membrane. The budding yeast NE lacks lamins and yet the nucleus is capable of maintaining a spherical shape throughout interphase. Despite these eccentricities, studies of the budding yeast NE have uncovered interesting, and likely conserved, processes that contribute to NE dynamics. In particular, we discuss the processes that drive and enable NE expansion and the dramatic changes in the NE that lead to extensions and fenestrations. J. Cell. Physiol. 231: 2353-2360, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Rebecca A Meseroll
- The Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Orna Cohen-Fix
- The Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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25
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Hellberg T, Paßvogel L, Schulz KS, Klupp BG, Mettenleiter TC. Nuclear Egress of Herpesviruses: The Prototypic Vesicular Nucleocytoplasmic Transport. Adv Virus Res 2016; 94:81-140. [PMID: 26997591 DOI: 10.1016/bs.aivir.2015.10.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Herpesvirus particles mature in two different cellular compartments. While capsid assembly and packaging of the genomic linear double-stranded DNA occur in the nucleus, virion formation takes place in the cytoplasm by the addition of numerous tegument proteins as well as acquisition of the viral envelope by budding into cellular vesicles derived from the trans-Golgi network containing virally encoded glycoproteins. To gain access to the final maturation compartment, herpesvirus nucleocapsids have to cross a formidable barrier, the nuclear envelope (NE). Since the ca. 120 nm diameter capsids are unable to traverse via nuclear pores, herpesviruses employ a vesicular transport through both leaflets of the NE. This process involves proteins which support local dissolution of the nuclear lamina to allow access of capsids to the inner nuclear membrane (INM), drive vesicle formation from the INM and mediate inclusion of the capsid as well as scission of the capsid-containing vesicle (also designated as "primary virion"). Fusion of the vesicle membrane (i.e., the "primary envelope") with the outer nuclear membrane subsequently results in release of the nucleocapsid into the cytoplasm for continuing virion morphogenesis. While this process has long been thought to be unique for herpesviruses, a similar pathway for nuclear egress of macromolecular complexes has recently been observed in Drosophila. Thus, herpesviruses may have coopted a hitherto unrecognized cellular mechanism of vesicle-mediated nucleocytoplasmic transport. This could have far reaching consequences for our understanding of cellular functions as again unraveled by the study of viruses.
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Affiliation(s)
- Teresa Hellberg
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Lars Paßvogel
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Katharina S Schulz
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Barbara G Klupp
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Thomas C Mettenleiter
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany.
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26
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Matsuhara H, Yamamoto A. Autophagy is required for efficient meiosis progression and proper meiotic chromosome segregation in fission yeast. Genes Cells 2015; 21:65-87. [DOI: 10.1111/gtc.12320] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 11/04/2015] [Indexed: 12/11/2022]
Affiliation(s)
- Hirotada Matsuhara
- Graduate School of Science and Technology; Shizuoka University; 836 Ohya Suruga-ku Shizuoka 422-8529 Japan
| | - Ayumu Yamamoto
- Graduate School of Science and Technology; Shizuoka University; 836 Ohya Suruga-ku Shizuoka 422-8529 Japan
- Faculty of Science; Shizuoka University; 836 Ohya Suruga-ku Shizuoka 422-8529 Japan
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27
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Cenni V, Capanni C, Mattioli E, Columbaro M, Wehnert M, Ortolani M, Fini M, Novelli G, Bertacchini J, Maraldi NM, Marmiroli S, D'Apice MR, Prencipe S, Squarzoni S, Lattanzi G. Rapamycin treatment of Mandibuloacral dysplasia cells rescues localization of chromatin-associated proteins and cell cycle dynamics. Aging (Albany NY) 2015; 6:755-70. [PMID: 25324471 PMCID: PMC4233654 DOI: 10.18632/aging.100680] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Lamin A is a key component of the nuclear lamina produced through post-translational processing of its precursor known as prelamin A. LMNA mutations leading to farnesylated prelamin A accumulation are known to cause lipodystrophy, progeroid and developmental diseases, including Mandibuloacral dysplasia, a mild progeroid syndrome with partial lipodystrophy and altered bone turnover. Thus, degradation of prelamin A is expected to improve the disease phenotype. Here, we show different susceptibilities of prelamin A forms to proteolysis and further demonstrate that treatment with rapamycin efficiently and selectively triggers lysosomal degradation of farnesylated prelamin A, the most toxic processing intermediate. Importantly, rapamycin treatment of Mandibuloacral dysplasia cells, which feature very low levels of the NAD-dependent sirtuin SIRT-1 in the nuclear matrix, restores SIRT-1 localization and distribution of chromatin markers, elicits release of the transcription factor Oct-1 and determines shortening of the prolonged S-phase. These findings indicate the drug as a possible treatment for Mandibuloacral dysplasia.
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Affiliation(s)
- Vittoria Cenni
- National Research Council of Italy, Institute of Molecular Genetics, IGM-CNR-IOR, Bologna, Italy. Rizzoli Orthopedic Institute, Laboratory of Musculoskeletal Cell Biology, Bologna, Italy
| | - Cristina Capanni
- National Research Council of Italy, Institute of Molecular Genetics, IGM-CNR-IOR, Bologna, Italy. Rizzoli Orthopedic Institute, Laboratory of Musculoskeletal Cell Biology, Bologna, Italy
| | - Elisabetta Mattioli
- National Research Council of Italy, Institute of Molecular Genetics, IGM-CNR-IOR, Bologna, Italy. Rizzoli Orthopedic Institute, Laboratory of Musculoskeletal Cell Biology, Bologna, Italy
| | - Marta Columbaro
- Rizzoli Orthopedic Institute, Laboratory of Musculoskeletal Cell Biology, Bologna, Italy
| | - Manfred Wehnert
- Institute of Human Genetics, University of Greifswald, Germany
| | - Michela Ortolani
- National Research Council of Italy, Institute of Molecular Genetics, IGM-CNR-IOR, Bologna, Italy
| | - Milena Fini
- Rizzoli Orthopedic Institute, Laboratory of Preclinical and Surgical Studies and BITTA, RIT, Bologna, Italy
| | - Giuseppe Novelli
- Department of Biomedicine and Prevention, Tor Vergata University, Rome, Italy
| | - Jessika Bertacchini
- Department of Laboratory, CEIA, University of Modena and Reggio Emilia, Modena, Italy
| | - Nadir M Maraldi
- National Research Council of Italy, Institute of Molecular Genetics, IGM-CNR-IOR, Bologna, Italy
| | - Sandra Marmiroli
- Department of Laboratory, CEIA, University of Modena and Reggio Emilia, Modena, Italy
| | - Maria Rosaria D'Apice
- Department of Biomedicine and Prevention, Tor Vergata University, Rome, Italy. Fondazione Policlinico Tor Vergata, Rome, Italy
| | - Sabino Prencipe
- National Research Council of Italy, Institute of Molecular Genetics, IGM-CNR-IOR, Bologna, Italy. Rizzoli Orthopedic Institute, Laboratory of Musculoskeletal Cell Biology, Bologna, Italy
| | - Stefano Squarzoni
- National Research Council of Italy, Institute of Molecular Genetics, IGM-CNR-IOR, Bologna, Italy. Rizzoli Orthopedic Institute, Laboratory of Musculoskeletal Cell Biology, Bologna, Italy
| | - Giovanna Lattanzi
- National Research Council of Italy, Institute of Molecular Genetics, IGM-CNR-IOR, Bologna, Italy. Rizzoli Orthopedic Institute, Laboratory of Musculoskeletal Cell Biology, Bologna, Italy
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28
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Carou MC, Cruzans PR, Maruri A, Stockert JC, Lombardo DM. Apoptosis in ovarian granulosa cells of cattle: morphological features and clearance by homologous phagocytosis. Acta Histochem 2015; 117:92-103. [PMID: 25511683 DOI: 10.1016/j.acthis.2014.11.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 11/10/2014] [Accepted: 11/13/2014] [Indexed: 01/05/2023]
Abstract
Apoptosis is involved in many physiological processes of the ovary, such as recruitment of prenatal germ cells, follicular atresia, ovulation, and luteolysis. Based on the need for the involvement of phagocytic cells to achieve apoptosis clearance and that follicular atresia is triggered by weak apoptotic stimuli, we postulate that granulosa cells engullng apoptotic corpses (ACs) must carry out this macrophagic process. Since apoptosis was early defined in terms of morphological aspects, here we describe apoptosis induced by a GnRH analog (leuprolide acetate, LA) at histological level on bovine granulosa cells (primary culture, CPGB, and an established cell line, BGC-1). We observed two main types of apoptosis. In type A, the whole cell or most of it is compacted into a single large AC that is then engulfed by neighboring cells or simply detached. In type B, small portions of cells, either with or without nuclear material, become ACs that are also phagocytosed. Apoptosis and homologous phagocytosis were confirmed by TUNEL and immunocytochemistry for Bax and active caspase 3. Induction of apoptosis was significant in BGC-1 cells treated for 24 h with 100 nM LA. CPGB cells showed two types of response with different doses of LA. Fetal calf serum was necessary to find apoptosis induced by LA.
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29
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Lan YY, Londoño D, Bouley R, Rooney MS, Hacohen N. Dnase2a deficiency uncovers lysosomal clearance of damaged nuclear DNA via autophagy. Cell Rep 2014; 9:180-192. [PMID: 25284779 DOI: 10.1016/j.celrep.2014.08.074] [Citation(s) in RCA: 174] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 07/30/2014] [Accepted: 08/28/2014] [Indexed: 12/22/2022] Open
Abstract
Deficiencies in DNA-degrading nucleases lead to accumulation of self DNA and induction of autoimmunity in mice and in monogenic and polygenic human diseases. However, the sources of DNA and the mechanisms that trigger immunity remain unclear. We analyzed mice deficient for the lysosomal nuclease Dnase2a and observed elevated levels of undegraded DNA in both phagocytic and nonphagocytic cells. In nonphagocytic cells, the excess DNA originated from damaged DNA in the nucleus based on colocalization studies, live-cell imaging, and exacerbation by DNA-damaging agents. Removal of damaged DNA by Dnase2a required nuclear export and autophagy-mediated delivery of the DNA to lysosomes. Finally, DNA was found to accumulate in Dnase2a(-/-) or autophagy-deficient cells and induce inflammation via the Sting cytosolic DNA-sensing pathway. Our results reveal a cell-autonomous process for removal of damaged nuclear DNA with implications for conditions with elevated DNA damage, such as inflammation, cancer, and chemotherapy.
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Affiliation(s)
- Yuk Yuen Lan
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, 149 13(th) Street, Charlestown, MA 02129, USA; Broad Institute, 415 Main Street, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Diana Londoño
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, 149 13(th) Street, Charlestown, MA 02129, USA
| | - Richard Bouley
- Center for Systems Biology, Program in Membrane Biology and Nephrology Division, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA
| | - Michael S Rooney
- Broad Institute, 415 Main Street, Cambridge, MA 02142, USA; Harvard/MIT Division of Health Sciences and Technology, Cambridge, MA 02139, USA
| | - Nir Hacohen
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, 149 13(th) Street, Charlestown, MA 02129, USA; Broad Institute, 415 Main Street, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
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30
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Hönscher C, Ungermann C. A close-up view of membrane contact sites between the endoplasmic reticulum and the endolysosomal system: from yeast to man. Crit Rev Biochem Mol Biol 2014; 49:262-8. [PMID: 24382115 DOI: 10.3109/10409238.2013.875512] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Maintenance of organelle identity is crucial for the functionality of eukaryotic cells. Hence, transfer reactions between different compartments must be highly efficient and tightly regulated at the same time. Membrane contact sites (MCSs) represent an important route for inter-organelle transport and communication independent of vesicular trafficking. Due to extensive research, the mechanistic understanding of these sites increases constantly. However, how the formation and the versatile functions of MCSs are regulated is mainly unclear. Within this review, we focus on one well-known MCS, the nucleus-vacuole junction in yeast and discuss its analogy to endoplasmic reticulum-late endosome contacts in metazoan. Formation of the junction in yeast requires Vac8, a protein that is involved in various cellular processes at the yeast vacuole and a target of multiple posttranslational modifications. We discuss the possibility that dual functionality of proteins involved in contact formation is a common principle to coordinate inter-organelle transfer with organellar biogenesis.
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Affiliation(s)
- Carina Hönscher
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück , Osnabrück , Germany
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31
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Serum non-coding RNAs as biomarkers for osteoarthritis progression after ACL injury. Osteoarthritis Cartilage 2012; 20:1631-7. [PMID: 22944527 PMCID: PMC3478481 DOI: 10.1016/j.joca.2012.08.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 08/09/2012] [Accepted: 08/22/2012] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The aim of this study was to examine serum non-coding RNAs as potential biomarkers for cartilage damage associated with anterior cruciate ligament (ACL) injury. METHODS Serum was obtained from 80 patients 1 year after surgery for ACL injury and 60 normal donors without overt skeletal injury. Total serum RNA was isolated, small non-coding RNAs profiled by TaqMan array MicroRNA (miRNA) analysis and individual small RNA assays performed by quantitative TaqMan RT-PCR (qPCR). Semi-quantitative magnetic resonance imaging (MRI) analysis was performed using Whole Organ Magnetic Resonance Knee Score (WORMS) scoring for analysis of cartilage damage. RESULTS Initial TaqMan array miRNA profiling showed an increased serum concentration of a small nucleolar RNA (snoRNA), U48, in five patients with cartilage damage compared with that in five patients without cartilage damage and six normal donors. Independent qPCR analysis of snoRNAs in serum from all patients and normal donors showed a strong association between the serum level of another snoRNA, U38, and cartilage damage in ACL injury patients and together with snoRNA, U48, clear distinction between ACL injury patients and normal donors. CONCLUSION SnoRNAs U38 and U48 are significantly elevated in the serum of patients developing cartilage damage at 1 year after ACL injury. Serum levels of U38 have the potential to facilitate early diagnosis of patients with cartilage damage after ACL injury. This study suggests serum non-coding RNAs may serve as novel noninvasive biomarkers for the detection and assessment of cartilage damage after ACL injury.
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Mijaljica D, Prescott M, Devenish RJ. A late form of nucleophagy in Saccharomyces cerevisiae. PLoS One 2012; 7:e40013. [PMID: 22768199 PMCID: PMC3386919 DOI: 10.1371/journal.pone.0040013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 06/04/2012] [Indexed: 12/19/2022] Open
Abstract
Autophagy encompasses several processes by which cytosol and organelles can be delivered to the vacuole/lysosome for breakdown and recycling. We sought to investigate autophagy of the nucleus (nucleophagy) in the yeast Saccharomyces cerevisiae by employing genetically encoded fluorescent reporters. The use of such a nuclear reporter, n-Rosella, proved the basis of robust assays based on either following its accumulation (by confocal microscopy), or degradation (by immunoblotting), within the vacuole. We observed the delivery of n-Rosella to the vacuole only after prolonged periods of nitrogen starvation. Dual labeling of cells with Nvj1p-EYFP, a nuclear membrane reporter of piecemeal micronucleophagy of the nucleus (PMN), and the nucleoplasm-targeted NAB35-DsRed.T3 allowed us to detect PMN soon after the commencement of nitrogen starvation whilst delivery to the vacuole of the nucleoplasm reporter was observed only after prolonged periods of nitrogen starvation. This later delivery of nuclear components to the vacuole has been designated LN (late nucleophagy). Only a very few cells showed simultaneous accumulation of both reporters (Nvj1p-EYFP and NAB35-DsRed.T3) in the vacuole. We determined, therefore, that delivery of the two respective nuclear reporters to the vacuole is temporally and spatially separated. Furthermore, our data suggest that LN is mechanistically distinct from PMN because it can occur in nvj1Δ and vac8Δ cells, and does not require ATG11. Nevertheless, a subset of the components of the core macroautophagic machinery is required for LN as it is efficiently inhibited in null mutants of several autophagy-related genes (ATG) specifying such components. Moreover, the inhibition of LN in some mutants is accompanied by alterations in nuclear morphology.
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Affiliation(s)
- Dalibor Mijaljica
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Victoria, Australia
| | - Mark Prescott
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Victoria, Australia
| | - Rodney J. Devenish
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Victoria, Australia
- * E-mail:
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33
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Nezis IP. Selective autophagy in Drosophila. Int J Cell Biol 2012; 2012:146767. [PMID: 22567011 PMCID: PMC3332208 DOI: 10.1155/2012/146767] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 02/01/2012] [Accepted: 02/03/2012] [Indexed: 11/26/2022] Open
Abstract
Autophagy is an evolutionarily conserved process of cellular self-eating and is a major pathway for degradation of cytoplasmic material by the lysosomal machinery. Autophagy functions as a cellular response in nutrient starvation, but it is also associated with the removal of protein aggregates and damaged organelles and therefore plays an important role in the quality control of proteins and organelles. Although it was initially believed that autophagy occurs randomly in the cell, during the last years, there is growing evidence that sequestration and degradation of cytoplasmic material by autophagy can be selective. Given the important role of autophagy and selective autophagy in several disease-related processes such as neurodegeneration, infections, and tumorigenesis, it is important to understand the molecular mechanisms of selective autophagy, especially at the organismal level. Drosophila is an excellent genetically modifiable model organism exhibiting high conservation in the autophagic machinery. However, the regulation and mechanisms of selective autophagy in Drosophila have been largely unexplored. In this paper, I will present an overview of the current knowledge about selective autophagy in Drosophila.
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Affiliation(s)
- Ioannis P. Nezis
- Department of Biochemistry, Institute for Cancer Research, Oslo University Hospital, Montebello, 0310 Oslo, Norway
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, 0310 Oslo, Norway
- Laboratory of Cell Biology, Department of Biological Applications and Technologies, University of Ioannina, 45110 Ioannina, Greece
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The many faces of mitochondrial autophagy: making sense of contrasting observations in recent research. Int J Cell Biol 2012; 2012:431684. [PMID: 22550491 PMCID: PMC3328949 DOI: 10.1155/2012/431684] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 12/21/2011] [Indexed: 11/17/2022] Open
Abstract
Research into the selective autophagic degradation of mitochondria—mitophagy—has intensified in recent years, yielding significant insights into the function, mechanism, and regulation of this process in the eukaryotic cell. However, while some molecular players in budding yeast, such as Atg32p, Uth1p, and Aup1p, have been identified, studies further interrogating the mechanistic and regulatory features of mitophagy have yielded inconsistent and sometimes conflicting results. In this review, we focus on the current understanding of mitophagy mechanism, induction, and regulation in yeast, and suggest that differences in experimental conditions used in the various studies of mitophagy may contribute to the observed discrepancies. Consideration and understanding of these differences may help place the mechanism and regulation of mitophagy in context, and further indicate the intricate role that this essential process plays in the life and death of eukaryotic cells.
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35
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Implications of therapy-induced selective autophagy on tumor metabolism and survival. Int J Cell Biol 2012; 2012:872091. [PMID: 22550492 PMCID: PMC3328951 DOI: 10.1155/2012/872091] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 01/14/2012] [Indexed: 01/13/2023] Open
Abstract
Accumulating evidence indicates that therapies designed to trigger apoptosis in tumor cells cause mitochondrial depolarization, nuclear damage, and the accumulation of misfolded protein aggregates, resulting in the activation of selective forms of autophagy. These selective forms of autophagy, including mitophagy, nucleophagy, and ubiquitin-mediated autophagy, counteract apoptotic signals by removing damaged cellular structures and by reprogramming cellular energy metabolism to cope with therapeutic stress. As a result, the efficacies of numerous current cancer therapies may be improved by combining them with adjuvant treatments that exploit or disrupt key metabolic processes induced by selective forms of autophagy. Targeting these metabolic irregularities represents a promising approach to improve clinical responsiveness to cancer treatments given the inherently elevated metabolic demands of many tumor types. To what extent anticancer treatments promote selective forms of autophagy and the degree to which they influence metabolism are currently under intense scrutiny. Understanding how the activation of selective forms of autophagy influences cellular metabolism and survival provides an opportunity to target metabolic irregularities induced by these pathways as a means of augmenting current approaches for treating cancer.
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Mijaljica D, Prescott M, Devenish RJ. The intriguing life of autophagosomes. Int J Mol Sci 2012; 13:3618-3635. [PMID: 22489171 PMCID: PMC3317731 DOI: 10.3390/ijms13033618] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 03/02/2012] [Accepted: 03/07/2012] [Indexed: 12/14/2022] Open
Abstract
Autophagosomes are double-membrane vesicles characteristic of macroautophagy, a degradative pathway for cytoplasmic material and organelles terminating in the lysosomal or vacuole compartment for mammals and yeast, respectively. This highly dynamic, multi-step process requires significant membrane reorganization events at different stages of the macroautophagic process. Such events include exchange and flow of lipids and proteins between membranes and vesicles (e.g., during initiation and growth of the phagophore), vesicular positioning and trafficking within the cell (e.g., autophagosome location and movement) and fusion of autophagosomes with the boundary membranes of the degradative compartment. Here, we review current knowledge on the contribution of different organelles to the formation of autophagosomes, their trafficking and fate within the cell. We will consider some of the unresolved questions related to the molecular mechanisms that regulate the "life and death" of the autophagosome.
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Affiliation(s)
- Dalibor Mijaljica
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton campus, Victoria 3800, Australia; E-Mails: (D.M.); (M.P.)
| | - Mark Prescott
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton campus, Victoria 3800, Australia; E-Mails: (D.M.); (M.P.)
| | - Rodney J. Devenish
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton campus, Victoria 3800, Australia; E-Mails: (D.M.); (M.P.)
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