1
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Dowaidar M. Guidelines for the role of autophagy in drug delivery vectors uptake pathways. Heliyon 2024; 10:e30238. [PMID: 38707383 PMCID: PMC11066435 DOI: 10.1016/j.heliyon.2024.e30238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/22/2024] [Accepted: 04/22/2024] [Indexed: 05/07/2024] Open
Abstract
The process of autophagy refers to the intracellular absorption of cytoplasm (such as proteins, nucleic acids, tiny molecules, complete organelles, and so on) into the lysosome, followed by the breakdown of that cytoplasm. The majority of cellular proteins are degraded by a process called autophagy, which is both a naturally occurring activity and one that may be induced by cellular stress. Autophagy is a system that can save cells' integrity in stressful situations by restoring metabolic basics and getting rid of subcellular junk. This happens as a component of an endurance response. This mechanism may have an effect on disease, in addition to its contribution to the homeostasis of individual cells and tissues as well as the control of development in higher species. The main aim of this study is to discuss the guidelines for the role of autophagy in drug delivery vector uptake pathways. In this paper, we discuss the meaning and concept of autophagy, the mechanism of autophagy, the role of autophagy in drug delivery vectors, autophagy-modulating drugs, nanostructures for delivery systems of autophagy modulators, etc. Later in this paper, we talk about how to deliver chemotherapeutics, siRNA, and autophagy inducers and inhibitors. We also talk about how hard it is to make a drug delivery system that takes nanocarriers' roles as autophagy modulators into account.
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Affiliation(s)
- Moataz Dowaidar
- Bioengineering Department, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, 31261, Saudi Arabia
- Interdisciplinary Research Center for Hydrogen Technologies and Carbon Management, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, 31261, Saudi Arabia
- Biosystems and Machines Research Center, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, 31261, Saudi Arabia
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2
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Macher M, Obermeier A, Fabritz S, Kube M, Kempf H, Dietz H, Platzman I, Spatz JP. An Efficient Method for the Production of High-Purity Bioinspired Large Unilamellar Vesicles. ACS Synth Biol 2024; 13:781-791. [PMID: 38423534 PMCID: PMC10949243 DOI: 10.1021/acssynbio.3c00540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 02/13/2024] [Accepted: 02/13/2024] [Indexed: 03/02/2024]
Abstract
In order to recapitulate complex eukaryotic compartmentalization, synthetic biology aims to recreate cellular membrane-lined compartments from the bottom-up. Many important cellular organelles and cell-produced extracellular vesicles are in the size range of several hundreds of nanometers. Although attaining a fundamental characterization and mimicry of their cellular functions is a compelling goal, the lack of methods for controlled vesicle formation in this size range has hindered full understanding. Here, we show the optimization of a simple and efficient protocol for the production of large unilamellar vesicles (LUVs) with a median diameter in the range of 450-550 nm with high purity. Importantly, we rely on commercial reagents and common laboratory equipment. We thoroughly characterize the influence of different experimental parameters on the concentration and size of the resulting vesicles and assess changes in their lipid composition and surface charge. We provide guidance for researchers to optimize LUV production further to suit specific applications.
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Affiliation(s)
- Meline Macher
- Max
Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69121, Germany
- Max
Planck School Matter to Life, Jahnstraße 29, Heidelberg 69121, Germany
- Institute
of Molecular Systems Engineering and Advanced Materials, Im Neuenheimer Feld 225, Heidelberg 69120, Germany
| | - Amelie Obermeier
- Max
Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69121, Germany
| | - Sebastian Fabritz
- Max
Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69121, Germany
| | - Massimo Kube
- Technical
University of Munich, Am Coulombwall 4a, Garching 85748, Germany
| | - Hannah Kempf
- Max
Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69121, Germany
| | - Hendrik Dietz
- Max
Planck School Matter to Life, Jahnstraße 29, Heidelberg 69121, Germany
- Technical
University of Munich, Am Coulombwall 4a, Garching 85748, Germany
| | - Ilia Platzman
- Max
Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69121, Germany
- Institute
of Molecular Systems Engineering and Advanced Materials, Im Neuenheimer Feld 225, Heidelberg 69120, Germany
| | - Joachim P. Spatz
- Max
Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69121, Germany
- Max
Planck School Matter to Life, Jahnstraße 29, Heidelberg 69121, Germany
- Institute
of Molecular Systems Engineering and Advanced Materials, Im Neuenheimer Feld 225, Heidelberg 69120, Germany
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3
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The metabolite alpha-ketobutyrate extends lifespan by promoting peroxisomal function in C. elegans. Nat Commun 2023; 14:240. [PMID: 36646719 PMCID: PMC9842765 DOI: 10.1038/s41467-023-35899-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 01/06/2023] [Indexed: 01/18/2023] Open
Abstract
Metabolism is intimately linked to aging. There is a growing number of studies showing that endogenous metabolites may delay aging and improve healthspan. Through the analysis of existing transcriptome data, we discover a link between activation of the transsulfuration pathway and a transcriptional program involved in peroxisome function and biogenesis in long-lived glp-1(e2141ts) mutant Caenorhabditis elegans worms. Subsequently, we show that supplementation with α-ketobutyrate, an intermediate of the transsulfuration pathway, extends lifespan in wild-type worms. Alpha-ketobutyrate augments the production of NAD+ via the lactate dehydrogenase LDH-1, leading to SIR-2.1/SIRT1-mediated enhanced peroxisome function and biogenesis, along with a concomitant increase in the expression of acox-1.2/ACOX1 in the peroxisomal fatty acid β-oxidation pathway. ACOX-1.2/ACOX1 promotes H2O2 formation, thereby resulting in activation of SKN-1/NRF2. This transcription factor in turn extends the lifespan of worms by driving expression of autophagic and lysosomal genes. Finally, we show that α-ketobutyrate also delays the cellular senescence in fibroblast cells through the SIRT1-ACOX1-H2O2-NRF2 pathway. This finding uncovers a previously unknown role for α-ketobutyrate in organismal lifespan and healthspan by coordinating the NAD+-SIRT1 signaling and peroxisomal function.
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4
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Ohsawa S, Oku M, Yurimoto H, Sakai Y. Regulation of Peroxisome Homeostasis by Post-Translational Modification in the Methylotrophic Yeast Komagataella phaffii. Front Cell Dev Biol 2022; 10:887806. [PMID: 35517506 PMCID: PMC9061947 DOI: 10.3389/fcell.2022.887806] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
The methylotrophic yeast Komagataella phaffii (synoym Pichia pastoris) can grow on methanol with an associated proliferation of peroxisomes, which are subsequently degraded by pexophagy upon depletion of methanol. Two cell wall integrity and stress response component (WSC) family proteins (Wsc1 and Wsc3) sense the extracellular methanol concentration and transmit the methanol signal to Rom2. This stimulates the activation of transcription factors (Mxr1, Trm1, and Mit1 etc.), leading to the induction of methanol-metabolizing enzymes (methanol-induced gene expression) and synthesis of huge peroxisomes. Methanol-induced gene expression is repressed by the addition of ethanol (ethanol repression). This repression is not conducted directly by ethanol but rather by acetyl-CoA synthesized from ethanol by sequential reactions, including alcohol and aldehyde dehydrogenases, and acetyl-CoA synthetase. During ethanol repression, Mxr1 is inactivated by phosphorylation. Peroxisomes are degraded by pexophagy on depletion of methanol and this event is triggered by phosphorylation of Atg30 located at the peroxisome membrane. In the presence of methanol, Wsc1 and Wsc3 repress pexophagy by transmitting the methanol signal via the MAPK cascade to the transcription factor Rlm1, which induces phosphatases involved in dephosphorylation of Atg30. Upon methanol consumption, repression of Atg30 phosphorylation is released, resulting in initiation of pexophagy. Physiological significance of these machineries involved in peroxisome homeostasis and their post-translational modification is also discussed in association with the lifestyle of methylotrophic yeast in the phyllosphere.
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Affiliation(s)
- Shin Ohsawa
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Masahide Oku
- Department of Bioscience and Biotechnology, Faculty of Bioenvironmental Science, Kyoto University of Advanced Science, Kyoto, Japan
| | - Hiroya Yurimoto
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Yasuyoshi Sakai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
- *Correspondence: Yasuyoshi Sakai,
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5
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Kumar R, Shroff A, Nazarko TY. Komagataella phaffii Cue5 Piggybacks on Lipid Droplets for Its Vacuolar Degradation during Stationary Phase Lipophagy. Cells 2022; 11:215. [PMID: 35053331 PMCID: PMC8774080 DOI: 10.3390/cells11020215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 02/06/2023] Open
Abstract
Recently, we developed Komagataella phaffii (formerly Pichia pastoris) as a model for lipophagy, the selective autophagy of lipid droplets (LDs). We found that lipophagy pathways induced by acute nitrogen (N) starvation and in stationary (S) phase have different molecular mechanisms. Moreover, both types of lipophagy are independent of Atg11, the scaffold protein that interacts with most autophagic receptors and, therefore, is essential for most types of selective autophagy in yeast. Since yeast aggrephagy, the selective autophagy of ubiquitinated protein aggregates, is also independent of Atg11 and utilizes the ubiquitin-binding receptor, Cue5, we studied the relationship of K. phaffii Cue5 with differentially induced LDs and lipophagy. While there was no relationship of Cue5 with LDs and lipophagy under N-starvation conditions, Cue5 accumulated on LDs in S-phase and degraded together with LDs via S-phase lipophagy. The accumulation of Cue5 on LDs and its degradation by S-phase lipophagy strongly depended on the ubiquitin-binding CUE domain and Prl1, the positive regulator of lipophagy 1. However, unlike Prl1, which is required for S-phase lipophagy, Cue5 was dispensable for it suggesting that Cue5 is rather a new substrate of this pathway. We propose that a similar mechanism (Prl1-dependent accumulation on LDs) might be employed by Prl1 to recruit another ubiquitin-binding protein that is essential for S-phase lipophagy.
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Affiliation(s)
- Ravinder Kumar
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA;
| | - Ankit Shroff
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA;
| | - Taras Y. Nazarko
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA;
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA;
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6
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Ohsawa S, Inoue K, Isoda T, Oku M, Yurimoto H, Sakai Y. The methanol sensor Wsc1 and MAPK Mpk1 suppress degradation of methanol-induced peroxisomes in methylotrophic yeast. J Cell Sci 2021; 134:jcs.254714. [PMID: 33771930 DOI: 10.1242/jcs.254714] [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: 09/21/2020] [Accepted: 03/17/2021] [Indexed: 12/13/2022] Open
Abstract
In nature, methanol is produced during the hydrolysis of pectin in plant cell walls. Methanol on plant leaves shows circadian dynamics, to which methanol-utilizing phyllosphere microorganisms adapt. In the methylotrophic yeast Komagataella phaffii (Kp; also known as Pichia pastoris), the plasma membrane protein KpWsc1 senses environmental methanol concentrations and transmits this information to induce the expression of genes for methanol metabolism and the formation of huge peroxisomes. In this study, we show that KpWsc1 and its downstream MAPK, KpMpk1, negatively regulate pexophagy in the presence of methanol concentrations greater than 0.15%. Although KpMpk1 was not necessary for expression of methanol-inducible genes and peroxisome biogenesis, KpMpk1, the transcription factor KpRlm1 and phosphatases were found to suppress pexophagy by controlling phosphorylation of KpAtg30, the key factor in regulation of pexophagy. We reveal at the molecular level how the single methanol sensor KpWsc1 commits the cell to peroxisome synthesis and degradation according to the methanol concentration, and we discuss the physiological significance of regulating pexophagy for survival in the phyllosphere. This article has an associated First Person interview with Shin Ohsawa, joint first author of the paper.
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Affiliation(s)
- Shin Ohsawa
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto 606-8502, Japan
| | - Koichi Inoue
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto 606-8502, Japan
| | - Takahiro Isoda
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto 606-8502, Japan
| | - Masahide Oku
- Department of Bioscience and Biotechnology, Faculty of Bioenvironmental Science, Kyoto University of Advanced Science, Sogabecho Nanjo Otani, Kameoka 621-8555, Japan
| | - Hiroya Yurimoto
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto 606-8502, Japan
| | - Yasuyoshi Sakai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto 606-8502, Japan.,Research Unit for Physiological Chemistry, the Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto 606-8502, Japan
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7
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BiFC Method Based on Intraorganellar Protein Crowding Detects Oleate-Dependent Peroxisomal Targeting of Pichia pastoris Malate Dehydrogenase. Int J Mol Sci 2021; 22:ijms22094890. [PMID: 34063066 PMCID: PMC8124512 DOI: 10.3390/ijms22094890] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/24/2021] [Accepted: 04/29/2021] [Indexed: 12/15/2022] Open
Abstract
The maintenance of intracellular NAD+/NADH homeostasis across multiple, subcellular compartments requires the presence of NADH-shuttling proteins, which circumvent the lack of permeability of organelle membranes to these cofactors. Very little is known regarding these proteins in the methylotrophic yeast, Pichia pastoris. During the study of the subcellular locations of these shuttling proteins, which often have dual subcellular locations, it became necessary to develop new ways to detect the weak peroxisomal locations of some of these proteins. We have developed a novel variation of the traditional Bimolecular Fluorescence Complementation (BiFC), called divergent BiFC, to detect intraorganellar colocalization of two noninteracting proteins based on their proximity-based protein crowding within a small subcellular compartment, rather than on the traditional protein–protein interactions expected for BiFC. This method is used to demonstrate the partially peroxisomal location of one such P. pastoris NADH-shuttling protein, malate dehydrogenase B, only when cells are grown in oleate, but not when grown in methanol or glucose. We discuss the mode of NADH shuttling in P. pastoris and the physiological basis of the medium-dependent compartmentalization of PpMdhB.
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8
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Nitrogen Starvation and Stationary Phase Lipophagy Have Distinct Molecular Mechanisms. Int J Mol Sci 2020; 21:ijms21239094. [PMID: 33260464 PMCID: PMC7730393 DOI: 10.3390/ijms21239094] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/24/2020] [Accepted: 11/26/2020] [Indexed: 01/06/2023] Open
Abstract
In yeast, the selective autophagy of intracellular lipid droplets (LDs) or lipophagy can be induced by either nitrogen (N) starvation or carbon limitation (e.g., in the stationary (S) phase). We developed the yeast, Komagataella phaffii (formerly Pichia pastoris), as a new lipophagy model and compared the N-starvation and S-phase lipophagy in over 30 autophagy-related mutants using the Erg6-GFP processing assay. Surprisingly, two lipophagy pathways had hardly overlapping stringent molecular requirements. While the N-starvation lipophagy strictly depended on the core autophagic machinery (Atg1-Atg9, Atg18, and Vps15), vacuole fusion machinery (Vam7 and Ypt7), and vacuolar proteolysis (proteinases A and B), only Atg6 and proteinases A and B were essential for the S-phase lipophagy. The rest of the proteins were only partially required in the S-phase. Moreover, we isolated the prl1 (for the positive regulator of lipophagy 1) mutant affected in the S-phase lipophagy, but not N-starvation lipophagy. The prl1 defect was at a stage of delivery of the LDs from the cytoplasm to the vacuole, further supporting the mechanistically different nature of the two lipophagy pathways. Taken together, our results suggest that N-starvation and S-phase lipophagy have distinct molecular mechanisms.
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9
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Mahalingam SS, Shukla N, Farré JC, Zientara-Rytter K, Subramani S. Balancing the Opposing Principles That Govern Peroxisome Homeostasis. Trends Biochem Sci 2020; 46:200-212. [PMID: 33046344 DOI: 10.1016/j.tibs.2020.09.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/14/2020] [Accepted: 09/22/2020] [Indexed: 12/12/2022]
Abstract
Despite major advances in our understanding of players and mechanisms involved in peroxisome biogenesis and peroxisome degradation, very few studies have focused on unraveling the multi-layered connections between, and the coordination of, these two opposing processes that regulate peroxisome homeostasis. The intersection between these processes also provides exciting avenues for future research. This review highlights the links between peroxisome biogenesis and degradation, incorporating an integrative approach that is critical not only for a mechanistic understanding, but also for manipulating the balance between these processes in relevant disease models.
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Affiliation(s)
- Shanmuga S Mahalingam
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, USA
| | - Nandini Shukla
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, USA
| | - Jean-Claude Farré
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, USA
| | - Katarzyna Zientara-Rytter
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, USA
| | - Suresh Subramani
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, USA.
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10
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Pourhanifeh MH, Mahjoubin-Tehran M, Karimzadeh MR, Mirzaei HR, Razavi ZS, Sahebkar A, Hosseini N, Mirzaei H, Hamblin MR. Autophagy in cancers including brain tumors: role of MicroRNAs. Cell Commun Signal 2020; 18:88. [PMID: 32517694 PMCID: PMC7285723 DOI: 10.1186/s12964-020-00587-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 04/27/2020] [Indexed: 12/14/2022] Open
Abstract
Autophagy has a crucial role in many cancers, including brain tumors. Several types of endogenous molecules (e.g. microRNAs, AKT, PTEN, p53, EGFR, and NF1) can modulate the process of autophagy. Recently miRNAs (small non-coding RNAs) have been found to play a vital role in the regulation of different cellular and molecular processes, such as autophagy. Deregulation of these molecules is associated with the development and progression of different pathological conditions, including brain tumors. It was found that miRNAs are epigenetic regulators, which influence the level of proteins coded by the targeted mRNAs with any modification of the genetic sequences. It has been revealed that various miRNAs (e.g., miR-7-1-3p, miR-340, miR-17, miR-30a, miR-224-3p, and miR-93), as epigenetic regulators, can modulate autophagy pathways within brain tumors. A deeper understanding of the underlying molecular targets of miRNAs, and their function in autophagy pathways could contribute to the development of new treatment methods for patients with brain tumors. In this review, we summarize the various miRNAs, which are involved in regulating autophagy in brain tumors. Moreover, we highlight the role of miRNAs in autophagy-related pathways in different cancers. Video abstract
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Affiliation(s)
| | - Maryam Mahjoubin-Tehran
- Student Research Committee, Mashhad University of Medical Sciences, Mashhad, Iran.,Department of Medical Biotechnology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mohammad Reza Karimzadeh
- Department of Medical Genetics, School of Medicine, Bam University of Medical Sciences, Bam, Iran
| | - Hamid Reza Mirzaei
- Department of Medical Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Zahra Sadat Razavi
- Student Research Committee, Kashan University of Medical Sciences, Kashan, Iran.,School of Medicine, Kashan University of Medical Sciences, Kashan, Iran
| | - Amirhossein Sahebkar
- Neurogenic Inflammation Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.,School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Nayyerehsadat Hosseini
- Medical Genetics Research Center, Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hamed Mirzaei
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran.
| | - Michael R Hamblin
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, 40 Blossom Street, Boston, MA, 02114, USA.
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11
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Germain K, Kim PK. Pexophagy: A Model for Selective Autophagy. Int J Mol Sci 2020; 21:ijms21020578. [PMID: 31963200 PMCID: PMC7013971 DOI: 10.3390/ijms21020578] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/09/2020] [Accepted: 01/13/2020] [Indexed: 01/03/2023] Open
Abstract
The removal of damaged or superfluous organelles from the cytosol by selective autophagy is required to maintain organelle function, quality control and overall cellular homeostasis. Precisely how substrate selectivity is achieved, and how individual substrates are degraded during selective autophagy in response to both extracellular and intracellular cues is not well understood. The aim of this review is to highlight pexophagy, the autophagic degradation of peroxisomes, as a model for selective autophagy. Peroxisomes are dynamic organelles whose abundance is rapidly modulated in response to metabolic demands. Peroxisomes are routinely turned over by pexophagy for organelle quality control yet can also be degraded by pexophagy in response to external stimuli such as amino acid starvation or hypoxia. This review discusses the molecular machinery and regulatory mechanisms governing substrate selectivity during both quality-control pexophagy and pexophagy in response to external stimuli, in yeast and mammalian systems. We draw lessons from pexophagy to infer how the cell may coordinate the degradation of individual substrates by selective autophagy across different cellular cues.
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Affiliation(s)
- Kyla Germain
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Peter K. Kim
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Correspondence: ; Tel.: +1-416-813-5983
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12
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Khandia R, Dadar M, Munjal A, Dhama K, Karthik K, Tiwari R, Yatoo MI, Iqbal HMN, Singh KP, Joshi SK, Chaicumpa W. A Comprehensive Review of Autophagy and Its Various Roles in Infectious, Non-Infectious, and Lifestyle Diseases: Current Knowledge and Prospects for Disease Prevention, Novel Drug Design, and Therapy. Cells 2019; 8:cells8070674. [PMID: 31277291 PMCID: PMC6678135 DOI: 10.3390/cells8070674] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/04/2019] [Accepted: 06/04/2019] [Indexed: 02/05/2023] Open
Abstract
Autophagy (self-eating) is a conserved cellular degradation process that plays important roles in maintaining homeostasis and preventing nutritional, metabolic, and infection-mediated stresses. Autophagy dysfunction can have various pathological consequences, including tumor progression, pathogen hyper-virulence, and neurodegeneration. This review describes the mechanisms of autophagy and its associations with other cell death mechanisms, including apoptosis, necrosis, necroptosis, and autosis. Autophagy has both positive and negative roles in infection, cancer, neural development, metabolism, cardiovascular health, immunity, and iron homeostasis. Genetic defects in autophagy can have pathological consequences, such as static childhood encephalopathy with neurodegeneration in adulthood, Crohn's disease, hereditary spastic paraparesis, Danon disease, X-linked myopathy with excessive autophagy, and sporadic inclusion body myositis. Further studies on the process of autophagy in different microbial infections could help to design and develop novel therapeutic strategies against important pathogenic microbes. This review on the progress and prospects of autophagy research describes various activators and suppressors, which could be used to design novel intervention strategies against numerous diseases and develop therapeutic drugs to protect human and animal health.
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Affiliation(s)
- Rekha Khandia
- Department of Genetics, Barkatullah University, Bhopal 462 026, Madhya Pradesh, India
| | - Maryam Dadar
- Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj 31975/148, Iran
| | - Ashok Munjal
- Department of Genetics, Barkatullah University, Bhopal 462 026, Madhya Pradesh, India.
| | - Kuldeep Dhama
- Division of Pathology, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly 243 122, Uttar Pradesh, India.
| | - Kumaragurubaran Karthik
- Central University Laboratory, Tamil Nadu Veterinary and Animal Sciences University, Madhavaram Milk Colony, Chennai, Tamil Nadu 600051, India
| | - Ruchi Tiwari
- Department of Veterinary Microbiology and Immunology, College of Veterinary Sciences, UP Pandit Deen Dayal Upadhayay Pashu Chikitsa Vigyan Vishwavidyalay Evum Go-Anusandhan Sansthan (DUVASU), Mathura, Uttar Pradesh 281 001, India
| | - Mohd Iqbal Yatoo
- Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shalimar, Srinagar 190025, Jammu and Kashmir, India
| | - Hafiz M N Iqbal
- Tecnologico de Monterrey, School of Engineering and Sciences, Campus Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N. L., CP 64849, Mexico
| | - Karam Pal Singh
- Division of Pathology, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly 243 122, Uttar Pradesh, India
| | - Sunil K Joshi
- Department of Pediatrics, Division of Hematology, Oncology and Bone Marrow Transplantation, University of Miami School of Medicine, Miami, FL 33136, USA.
| | - Wanpen Chaicumpa
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
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13
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Zientara-Rytter K, Subramani S. Mechanistic Insights into the Role of Atg11 in Selective Autophagy. J Mol Biol 2019; 432:104-122. [PMID: 31238043 DOI: 10.1016/j.jmb.2019.06.017] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/11/2019] [Accepted: 06/13/2019] [Indexed: 12/19/2022]
Abstract
Macroautophagy (referred to hereafter as autophagy) is an intracellular degradation pathway in which the formation of a double-membrane vesicle called the autophagosome is a key event in the transport of multiple cytoplasmic cargo (e.g., proteins, protein aggregates, lipid droplets or organelles) to the vacuole (lysosome in mammals) for degradation and recycling. During this process, autophagosomes are formed de novo by membrane fusion events leading to phagophore formation initiated at the phagophore assembly site. In yeast, Atg11 and Atg17 function as protein scaffolds, essential for selective and non-selective types of autophagy, respectively. While Atg17 functions in non-selective autophagy are well-defined in the literature, less attention is concentrated on recent findings regarding the roles of Atg11 in selective autophagy. Here, we summarize current knowledge about the Atg11 scaffold protein and review recent findings in the context of its role in selective autophagy initiation and autophagosome formation.
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Affiliation(s)
- Katarzyna Zientara-Rytter
- Section of Molecular Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA.
| | - Suresh Subramani
- Section of Molecular Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
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14
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Luo M, Zhuang X. Review: Selective degradation of peroxisome by autophagy in plants: Mechanisms, functions, and perspectives. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 274:485-491. [PMID: 30080638 DOI: 10.1016/j.plantsci.2018.06.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 06/28/2018] [Accepted: 06/29/2018] [Indexed: 06/08/2023]
Abstract
Peroxisome, a single-membrane organelle conserved in eukaryotic, is responsible for a series of oxidative reactions with its specific enzymatic components. A counterbalance between peroxisome biogenesis and degradation is crucial for the homeostasis of peroxisomes. One such degradation mechanism, termed pexophagy, is a type of selective autophagic process to deliver the excess/damaged peroxisomes into the vacuole. In plants, pexophagy is involved in the remodeling of seedlings and quality control of peroxisomes. Here, we describe the recent advance in plant pexophagy, with a focus to discuss the key regulators in plants in comparison with those in yeast and mammals, as well as future directions for pexophagy studies in plants.
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Affiliation(s)
- Mengqian Luo
- Centre for Cell & Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Xiaohong Zhuang
- Centre for Cell & Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
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15
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Cargo recognition and degradation by selective autophagy. Nat Cell Biol 2018; 20:233-242. [PMID: 29476151 DOI: 10.1038/s41556-018-0037-z] [Citation(s) in RCA: 722] [Impact Index Per Article: 120.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 01/05/2018] [Indexed: 12/12/2022]
Abstract
Macroautophagy, initially described as a non-selective nutrient recycling process, is essential for the removal of multiple cellular components. In the past three decades, selective autophagy has been characterized as a highly regulated and specific degradation pathway for removal of unwanted cytosolic components and damaged and/or superfluous organelles. Here, we discuss different types of selective autophagy, emphasizing the role of ligand receptors and scaffold proteins in providing cargo specificity, and highlight unanswered questions in the field.
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16
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Abstract
Peroxisome abundance is tightly regulated according to the physiological contexts, through regulations of both proliferation and degradation of the organelles. Here, we describe detailed methods to analyze processes for autophagic degradation of peroxisomes, termed pexophagy, in yeast organisms. The assay systems include a method for biochemical detection of pexophagy completion, and one for microscopic visualization of specialized membrane structures acting in pexophagy. As a model yeast organism utilized in studies of pexophagy, the methylotrophic yeast Komagataella phaffii (Pichia pastoris) is referred to in this chapter and related information on the studies with baker's yeast (Saccharomyces cerevisiae) is also included. The described techniques facilitate elucidation of molecular machineries for pexophagy and understanding of peroxisome-selective autophagic pathways.
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17
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Active Interaction Mapping Reveals the Hierarchical Organization of Autophagy. Mol Cell 2017; 65:761-774.e5. [PMID: 28132844 DOI: 10.1016/j.molcel.2016.12.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 11/21/2016] [Accepted: 12/22/2016] [Indexed: 12/15/2022]
Abstract
We have developed a general progressive procedure, Active Interaction Mapping, to guide assembly of the hierarchy of functions encoding any biological system. Using this process, we assemble an ontology of functions comprising autophagy, a central recycling process implicated in numerous diseases. A first-generation model, built from existing gene networks in Saccharomyces, captures most known autophagy components in broad relation to vesicle transport, cell cycle, and stress response. Systematic analysis identifies synthetic-lethal interactions as most informative for further experiments; consequently, we saturate the model with 156,364 such measurements across autophagy-activating conditions. These targeted interactions provide more information about autophagy than all previous datasets, producing a second-generation ontology of 220 functions. Approximately half are previously unknown; we confirm roles for Gyp1 at the phagophore-assembly site, Atg24 in cargo engulfment, Atg26 in cytoplasm-to-vacuole targeting, and Ssd1, Did4, and others in selective and non-selective autophagy. The procedure and autophagy hierarchy are at http://atgo.ucsd.edu/.
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18
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Cao L, Fu M, Kumar S, Kumar A. Methamphetamine potentiates HIV-1 gp120-mediated autophagy via Beclin-1 and Atg5/7 as a pro-survival response in astrocytes. Cell Death Dis 2016; 7:e2425. [PMID: 27763640 PMCID: PMC5133984 DOI: 10.1038/cddis.2016.317] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 08/05/2016] [Accepted: 08/23/2016] [Indexed: 01/02/2023]
Abstract
Methamphetamine (METH), a commonly used controlled substance, is known to exacerbate neuropathological dysfunction in HIV-infected individuals. The neuropathological manifestation results from cell death or dysfunction in the central nervous system (CNS) wherein autophagy is expected to have an important role. Autophagy is generally considered protective during deprivation/stress. However, excessive autophagy can be destructive, leading to autophagic cell death. This study was designed to investigate if METH and HIV-1 gp120 interact to induce autophagy in SVGA astrocytes, and whether autophagy is epiphenomenal or it has a role in METH- and gp120-induced cytotoxicity. We found that METH and gp120 IIIb caused an increase in LC3II level in astrocytes in a dose- and time-dependent manner, and the level of LC3II was further increased when the cells were treated with METH and gp120 IIIb in combination. Next, we sought to explore the mechanism by which METH and gp120 induce the autophagic response. We found that METH induces autophagy via opioid and metabotropic glutamate receptor type 5 (mGluR5) receptors. Other than that, signaling proteins Akt, mammalian target of rapamycin (mTOR), Beclin-1, Atg5 and Atg7 were involved in METH and gp120-mediated autophagy. In addition, long-term treatment of METH and gp120 IIIb resulted in cell death, which was exacerbated by inhibition of autophagy. This suggests that autophagy functions as a protective response against apoptosis caused by METH and gp120. This study is novel and clinically relevant because METH abuse among HIV-infected populations is highly prevalent and is known to cause exacerbated neuroAIDS.
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Affiliation(s)
- Lu Cao
- Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Mingui Fu
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Santosh Kumar
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Anil Kumar
- Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, MO, USA
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19
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Kikuma T, Tadokoro T, Maruyama JI, Kitamoto K. AoAtg26, a putative sterol glucosyltransferase, is required for autophagic degradation of peroxisomes, mitochondria, and nuclei in the filamentous fungus Aspergillus oryzae. Biosci Biotechnol Biochem 2016; 81:384-395. [PMID: 27696999 DOI: 10.1080/09168451.2016.1240603] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Autophagy is a conserved process in eukaryotic cells for degradation of cellular proteins and organelles. In filamentous fungi, autophagic degradation of organelles such as peroxisomes, mitochondria, and nuclei occurs in basal cells after the prolonged culture, but its mechanism is not well understood. Here, we functionally analyzed the filamentous fungus Aspergillus oryzae AoAtg26, an ortholog of the sterol glucosyltransferase PpAtg26 involved in pexophagy in the yeast Pichia pastoris. Deletion of Aoatg26 caused a severe decrease in conidiation and aerial hyphae formation, which is typically observed in the autophagy-deficient A. oryzae strains. In addition, cup-shaped AoAtg8-positive membrane structures were accumulated in the Aoatg26 deletion strain, indicating that autophagic process is impaired. Indeed, the Aoatg26 deletion strain was defective in the degradation of peroxisomes, mitochondria, and nuclei. Taken together, AoAtg26 plays an important role for autophagic degradation of organelles in A. oryzae, which may physiologically contribute to the differentiation in filamentous fungi.
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Affiliation(s)
- Takashi Kikuma
- a Department of Biotechnology , The University of Tokyo , Tokyo , Japan
| | - Takayuki Tadokoro
- a Department of Biotechnology , The University of Tokyo , Tokyo , Japan
| | - Jun-Ichi Maruyama
- a Department of Biotechnology , The University of Tokyo , Tokyo , Japan
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20
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Farré JC, Subramani S. Mechanistic insights into selective autophagy pathways: lessons from yeast. Nat Rev Mol Cell Biol 2016; 17:537-52. [PMID: 27381245 PMCID: PMC5549613 DOI: 10.1038/nrm.2016.74] [Citation(s) in RCA: 271] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Autophagy has burgeoned rapidly as a field of study because of its evolutionary conservation, the diversity of intracellular cargoes degraded and recycled by this machinery, the mechanisms involved, as well as its physiological relevance to human health and disease. This self-eating process was initially viewed as a non-selective mechanism used by eukaryotic cells to degrade and recycle macromolecules in response to stress; we now know that various cellular constituents, as well as pathogens, can also undergo selective autophagy. In contrast to non-selective autophagy, selective autophagy pathways rely on a plethora of selective autophagy receptors (SARs) that recognize and direct intracellular protein aggregates, organelles and pathogens for specific degradation. Although SARs themselves are not highly conserved, their modes of action and the signalling cascades that activate and regulate them are. Recent yeast studies have provided novel mechanistic insights into selective autophagy pathways, revealing principles of how various cargoes can be marked and targeted for selective degradation.
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Affiliation(s)
- Jean-Claude Farré
- University of California, 3326 Bonner Hall, 9500 Gilman Drive, San Diego, La Jolla, California 92093-0322, USA
| | - Suresh Subramani
- University of California, 3326 Bonner Hall, 9500 Gilman Drive, San Diego, La Jolla, California 92093-0322, USA
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21
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Pexophagy in yeasts. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:992-8. [DOI: 10.1016/j.bbamcr.2015.09.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 09/16/2015] [Accepted: 09/21/2015] [Indexed: 01/07/2023]
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22
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Sibirny AA. Yeast peroxisomes: structure, functions and biotechnological opportunities. FEMS Yeast Res 2016; 16:fow038. [DOI: 10.1093/femsyr/fow038] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2016] [Indexed: 01/02/2023] Open
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23
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Noda NN, Mizushima N. Atg101: Not Just an Accessory Subunit in the Autophagy-initiation Complex. Cell Struct Funct 2016; 41:13-20. [DOI: 10.1247/csf.15013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Nobuo N. Noda
- Laboratory of Structural Chemistry and Biology, Institute of Microbial Chemistry (BIKAKEN)
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo
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24
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Brown AI, Rutenberg AD. Cluster coarsening on drops exhibits strong and sudden size-selectivity. SOFT MATTER 2015; 11:3786-3793. [PMID: 25846269 DOI: 10.1039/c5sm00284b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Autophagy, an important process for degradation of cellular components, requires the targeting of autophagy receptor proteins to potential substrates. Receptor proteins have been observed to form clusters on membranes. To understand how receptor clusters might affect autophagy selectivity, we model cluster coarsening on a polydisperse collection of spherical drop-like substrates. Our model receptor corresponds to NBR1, which supports peroxisome autophagy. We recover dynamical scaling of cluster sizes, but find that changing the drop size distribution changes the cluster-size scaling distribution. The magnitude of this effect is similar to how changing the spatial-dimension affects scaling in bulk systems. We also observe a sudden onset of size-selection of the remaining drops with clusters, due to clusters evaporating from smaller drops and growing on larger drops. This coarsening-driven size selection provides a physical mechanism for autophagy selectivity, and may explain reports of size selection during peroxisome degradation.
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Affiliation(s)
- Aidan I Brown
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, CanadaB3H 4R2.
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25
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Tadokoro T, Kikuma T, Kitamoto K. Functional analysis of AoAtg11 in selective autophagy in the filamentous fungus Aspergillus oryzae. Fungal Biol 2015; 119:560-7. [PMID: 26058532 DOI: 10.1016/j.funbio.2015.03.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 02/17/2015] [Accepted: 03/03/2015] [Indexed: 12/19/2022]
Abstract
Autophagy is a highly conserved cellular degradation process in eukaryotes and consists of both non-selective and selective types. Selective autophagic processes include pexophagy, mitophagy, and the cytoplasm-to-vacuole targeting (Cvt) pathway of yeast, in which particular vacuolar proteins, such as aminopeptidase I (Ape1), are selectively transported to vacuoles. Although selective autophagy has been mainly studied in the yeasts Saccharomyces cerevisiae and Pichia pastoris, there is evidence for selective autophagy in filamentous fungi; however, the details are poorly understood. In S. cerevisiae, Atg11 is a selective autophagy-specific protein that recognizes and transports substrates to the pre-autophagosomal structure (PAS). Here, we first identified an ATG11 homologue in the filamentous fungus Aspergillus oryzae and analyzed the localization of the corresponding protein, designated AoAtg11, fused to enhanced green fluorescent protein (EGFP). Imaging analysis revealed that AoAtg11-EGFP was localized to PAS-like structures. We next constructed an Aoatg11 disruptant of A. oryzae and showed that AoAtg11 is involved in pexophagy and mitophagy. In addition, AoAtg11 was found to be dispensable for non-selective autophagy and for transporting AoApe1 to vacuoles. Taken together, these results suggest that AoAtg11 is a selective autophagy-specific protein in A. oryzae, and has distinct molecular functions from that of S. cerevisiae Atg11.
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Affiliation(s)
- Takayuki Tadokoro
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takashi Kikuma
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Katsuhiko Kitamoto
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
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26
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Burnett SF, Farré JC, Nazarko TY, Subramani S. Peroxisomal Pex3 activates selective autophagy of peroxisomes via interaction with the pexophagy receptor Atg30. J Biol Chem 2015; 290:8623-31. [PMID: 25694426 DOI: 10.1074/jbc.m114.619338] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Pexophagy is a process that selectively degrades peroxisomes by autophagy. The Pichia pastoris pexophagy receptor Atg30 is recruited to peroxisomes under peroxisome proliferation conditions. During pexophagy, Atg30 undergoes phosphorylation, a prerequisite for its interactions with the autophagy scaffold protein Atg11 and the ubiquitin-like protein Atg8. Atg30 is subsequently shuttled to the vacuole along with the targeted peroxisome for degradation. Here, we defined the binding site for Atg30 on the peroxisomal membrane protein Pex3 and uncovered a role for Pex3 in the activation of Atg30 via phosphorylation and in the recruitment of Atg11 to the receptor protein complex. Pex3 is classically a docking protein for other proteins that affect peroxisome biogenesis, division, and segregation. We conclude that Pex3 has a role beyond simple docking of Atg30 and that its interaction with Atg30 regulates pexophagy in the yeast P. pastoris.
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Affiliation(s)
- Sarah F Burnett
- From the Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093-0322
| | - Jean-Claude Farré
- From the Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093-0322
| | - Taras Y Nazarko
- From the Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093-0322
| | - Suresh Subramani
- From the Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093-0322
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27
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Nazarko TY, Ozeki K, Till A, Ramakrishnan G, Lotfi P, Yan M, Subramani S. Peroxisomal Atg37 binds Atg30 or palmitoyl-CoA to regulate phagophore formation during pexophagy. ACTA ACUST UNITED AC 2014; 204:541-57. [PMID: 24535825 PMCID: PMC3926955 DOI: 10.1083/jcb.201307050] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The acyl-CoA–binding protein Atg37 is a new component of the pexophagic receptor protein complex that regulates the recruitment of Atg11 by Atg30 in the peroxisomal membrane during pexophagy Autophagy is a membrane trafficking pathway that sequesters proteins and organelles into autophagosomes. The selectivity of this pathway is determined by autophagy receptors, such as the Pichia pastoris autophagy-related protein 30 (Atg30), which controls the selective autophagy of peroxisomes (pexophagy) through the assembly of a receptor protein complex (RPC). However, how the pexophagic RPC is regulated for efficient formation of the phagophore, an isolation membrane that sequesters the peroxisome from the cytosol, is unknown. Here we describe a new, conserved acyl-CoA–binding protein, Atg37, that is an integral peroxisomal membrane protein required specifically for pexophagy at the stage of phagophore formation. Atg30 recruits Atg37 to the pexophagic RPC, where Atg37 regulates the recruitment of the scaffold protein, Atg11. Palmitoyl-CoA competes with Atg30 for Atg37 binding. The human orthologue of Atg37, acyl-CoA–binding domain containing protein 5 (ACBD5), is also peroxisomal and is required specifically for pexophagy. We suggest that Atg37/ACBD5 is a new component and positive regulator of the pexophagic RPC.
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Affiliation(s)
- Taras Y Nazarko
- Section of Molecular Biology, Division of Biological Sciences, and 2 San Diego Center for Systems Biology, University of California, San Diego, La Jolla, CA 92093
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28
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Abstract
Autophagy is a primarily degradative pathway that takes place in all eukaryotic cells. It is used for recycling cytoplasm to generate macromolecular building blocks and energy under stress conditions, to remove superfluous and damaged organelles to adapt to changing nutrient conditions and to maintain cellular homeostasis. In addition, autophagy plays a critical role in cytoprotection by preventing the accumulation of toxic proteins and through its action in various aspects of immunity including the elimination of invasive microbes and its participation in antigen presentation. The most prevalent form of autophagy is macroautophagy, and during this process, the cell forms a double-membrane sequestering compartment termed the phagophore, which matures into an autophagosome. Following delivery to the vacuole or lysosome, the cargo is degraded and the resulting macromolecules are released back into the cytosol for reuse. The past two decades have resulted in a tremendous increase with regard to the molecular studies of autophagy being carried out in yeast and other eukaryotes. Part of the surge in interest in this topic is due to the connection of autophagy with a wide range of human pathophysiologies including cancer, myopathies, diabetes and neurodegenerative disease. However, there are still many aspects of autophagy that remain unclear, including the process of phagophore formation, the regulatory mechanisms that control its induction and the function of most of the autophagy-related proteins. In this review, we focus on macroautophagy, briefly describing the discovery of this process in mammalian cells, discussing the current views concerning the donor membrane that forms the phagophore, and characterizing the autophagy machinery including the available structural information.
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Affiliation(s)
- Yuchen Feng
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ding He
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Zhiyuan Yao
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Daniel J Klionsky
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
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29
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Deng Y, Qu Z, Naqvi NI. The role of snx41-based pexophagy in magnaporthe development. PLoS One 2013; 8:e79128. [PMID: 24302988 PMCID: PMC3841179 DOI: 10.1371/journal.pone.0079128] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 09/18/2013] [Indexed: 11/18/2022] Open
Abstract
Pexophagy, the degradation of peroxisomes via selective autophagy, depends on Atg20/Snx42 function in Saccharomyces cerevisiae. Besides its role in selective autophagy, Atg20/Snx42 is also involved in an autophagy-independent endosomal retrieval trafficking, in cooperation with two other sorting nexins, Snx41 and Snx4. Recently, we reported that the sorting nexin MoSnx41, which showed high sequence similarity to yeast Snx41 and Snx42/Atg20 proteins, regulates the gamma-glutamyl cycle and GSH production and is essential for conidiation and pathogenicity in Magnaporthe oryzae. Pexophagy was also found to be defective in Mosnx41Δ mutant. These findings indicate that MoSnx41 likely serves combined functions of Snx42/Atg20 and Snx41 in M. oryzae.. In this study, we performed complementation analyses and demonstrate that MoSnx41 alone serves the dual function of protein sorting (ScSnx41) and pexophagy (ScSnx42/Atg20). To study the potential biological function of pexophagy in fungal pathogenic life cycle, we created deletion mutants of potential pexophagy-specific genes, and characterized them in terms of pexophagy, conidiation and pathogenesis. We identified Pex14 as an essential protein for pexophagy in M. oryzae. Overall, our results show that pexophagy per se is not essential for asexual development or virulence in M. oryzae.
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Affiliation(s)
- Yizhen Deng
- Temasek Life Sciences Laboratory, and Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- * E-mail: (YD); (NN)
| | - Ziwei Qu
- Temasek Life Sciences Laboratory, and Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Naweed I. Naqvi
- Temasek Life Sciences Laboratory, and Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- * E-mail: (YD); (NN)
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30
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Nordgren M, Wang B, Apanasets O, Fransen M. Peroxisome degradation in mammals: mechanisms of action, recent advances, and perspectives. Front Physiol 2013; 4:145. [PMID: 23785334 PMCID: PMC3682127 DOI: 10.3389/fphys.2013.00145] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 05/30/2013] [Indexed: 12/18/2022] Open
Abstract
Peroxisomes are remarkably dynamic organelles that participate in a diverse array of cellular processes, including the metabolism of lipids and reactive oxygen species. In order to regulate peroxisome function in response to changing nutritional and environmental stimuli, new organelles need to be formed and superfluous and dysfunctional organelles have to be selectively removed. Disturbances in any of these processes have been associated with the etiology and progression of various congenital neurodegenerative and age-related human disorders. The aim of this review is to critically explore our current knowledge of how peroxisomes are degraded in mammalian cells and how defects in this process may contribute to human disease. Some of the key issues highlighted include the current concepts of peroxisome removal, the peroxisome quality control mechanisms, the initial triggers for peroxisome degradation, the factors for dysfunctional peroxisome recognition, and the regulation of peroxisome homeostasis. We also dissect the functional and mechanistic relationship between different forms of selective organelle degradation and consider how lysosomal dysfunction may lead to defects in peroxisome turnover. In addition, we draw lessons from studies on other organisms and extrapolate this knowledge to mammals. Finally, we discuss the potential pathological implications of dysfunctional peroxisome degradation for human health.
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Affiliation(s)
- Marcus Nordgren
- Laboratory of Lipid Biochemistry and Protein Interactions, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven Leuven, Vlaams-Brabant, Belgium
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31
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Manivannan S, de Boer R, Veenhuis M, van der Klei IJ. Lumenal peroxisomal protein aggregates are removed by concerted fission and autophagy events. Autophagy 2013; 9:1044-56. [PMID: 23614977 DOI: 10.4161/auto.24543] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We demonstrated that in the yeast Hansenula polymorpha peroxisome fission and degradation are coupled processes that are important to remove intra-organellar protein aggregates. Protein aggregates were formed in peroxisomes upon synthesis of a mutant catalase variant. We showed that the introduction of these aggregates in the peroxisomal lumen had physiological disadvantages as it affected growth and caused enhanced levels of reactive oxygen species. Formation of the protein aggregates was followed by asymmetric peroxisome fission to separate the aggregate from the mother organelle. Subsequently, these small, protein aggregate-containing organelles were degraded by autophagy. In line with this observation we showed that the degradation of the protein aggregates was strongly reduced in dnm1 and pex11 cells in which peroxisome fission is reduced. Moreover, this process was dependent on Atg1 and Atg11.
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Phosphorylation of mitophagy and pexophagy receptors coordinates their interaction with Atg8 and Atg11. EMBO Rep 2013; 14:441-9. [PMID: 23559066 DOI: 10.1038/embor.2013.40] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 03/08/2013] [Accepted: 03/12/2013] [Indexed: 12/31/2022] Open
Abstract
The selective autophagy receptors Atg19 and Atg32 interact with two proteins of the core autophagic machinery: the scaffold protein Atg11 and the ubiquitin-like protein Atg8. We found that the Pichia pastoris pexophagy receptor, Atg30, also interacts with Atg8. Both Atg30 and Atg32 interactions are regulated by phosphorylation close to Atg8-interaction motifs. Extending this finding to Saccharomyces cerevisiae, we confirmed phosphoregulation for the mitophagy and pexophagy receptors, Atg32 and Atg36. Each Atg30 molecule must interact with both Atg8 and Atg11 for full functionality, and these interactions occur independently and not simultaneously, but rather in random order. We present a common model for the phosphoregulation of selective autophagy receptors.
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Substrate recognition in selective autophagy and the ubiquitin-proteasome system. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:163-81. [PMID: 23545414 DOI: 10.1016/j.bbamcr.2013.03.019] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 03/15/2013] [Accepted: 03/20/2013] [Indexed: 12/21/2022]
Abstract
Dynamic protein turnover through regulated protein synthesis and degradation ensures cellular growth, proliferation, differentiation and adaptation. Eukaryotic cells utilize two mechanistically distinct but largely complementary systems - the 26S proteasome and the lysosome (or vacuole in yeast and plants) - to effectively target a wide range of proteins for degradation. The concerted action of the ubiquitination machinery and the 26S proteasome ensures the targeted and tightly regulated degradation of a subset of commonly short-lived cellular proteins. Autophagy is a distinct degradation pathway, which transports a highly heterogeneous set of cargos in dedicated vesicles, called autophagosomes, to the lysosome. There the cargo becomes degraded and its molecular building blocks are recycled. While general autophagy randomly engulfs portions of the cytosol, selective autophagy employs dedicated cargo adaptors to specifically enrich the forming autophagosomes for a certain type of cargo as a response to various intra- or extracellular signals. Selective autophagy targets a wide range of cargos including long-lived proteins and protein complexes, organelles, protein aggregates and even intracellular microbes. In this review we summarize available data on cargo recognition mechanisms operating in selective autophagy and the ubiquitin-proteasome system (UPS), and emphasize their differences and common themes. Moreover, we derive general regulatory principles underlying cargo recognition in selective autophagy, and describe the system-wide crosstalk between these two cellular protein degradation systems. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.
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Mizuno Y, Ninomiya Y, Nakachi Y, Iseki M, Iwasa H, Akita M, Tsukui T, Shimozawa N, Ito C, Toshimori K, Nishimukai M, Hara H, Maeba R, Okazaki T, Alodaib ANA, Amoudi MA, Jacob M, Alkuraya FS, Horai Y, Watanabe M, Motegi H, Wakana S, Noda T, Kurochkin IV, Mizuno Y, Schönbach C, Okazaki Y. Tysnd1 deficiency in mice interferes with the peroxisomal localization of PTS2 enzymes, causing lipid metabolic abnormalities and male infertility. PLoS Genet 2013; 9:e1003286. [PMID: 23459139 PMCID: PMC3573110 DOI: 10.1371/journal.pgen.1003286] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 12/12/2012] [Indexed: 12/03/2022] Open
Abstract
Peroxisomes are subcellular organelles involved in lipid metabolic processes, including those of very-long-chain fatty acids and branched-chain fatty acids, among others. Peroxisome matrix proteins are synthesized in the cytoplasm. Targeting signals (PTS or peroxisomal targeting signal) at the C-terminus (PTS1) or N-terminus (PTS2) of peroxisomal matrix proteins mediate their import into the organelle. In the case of PTS2-containing proteins, the PTS2 signal is cleaved from the protein when transported into peroxisomes. The functional mechanism of PTS2 processing, however, is poorly understood. Previously we identified Tysnd1 (Trypsin domain containing 1) and biochemically characterized it as a peroxisomal cysteine endopeptidase that directly processes PTS2-containing prethiolase Acaa1 and PTS1-containing Acox1, Hsd17b4, and ScpX. The latter three enzymes are crucial components of the very-long-chain fatty acids β-oxidation pathway. To clarify the in vivo functions and physiological role of Tysnd1, we analyzed the phenotype of Tysnd1(-/-) mice. Male Tysnd1(-/-) mice are infertile, and the epididymal sperms lack the acrosomal cap. These phenotypic features are most likely the result of changes in the molecular species composition of choline and ethanolamine plasmalogens. Tysnd1(-/-) mice also developed liver dysfunctions when the phytanic acid precursor phytol was orally administered. Phyh and Agps are known PTS2-containing proteins, but were identified as novel Tysnd1 substrates. Loss of Tysnd1 interferes with the peroxisomal localization of Acaa1, Phyh, and Agps, which might cause the mild Zellweger syndrome spectrum-resembling phenotypes. Our data established that peroxisomal processing protease Tysnd1 is necessary to mediate the physiological functions of PTS2-containing substrates.
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Affiliation(s)
- Yumi Mizuno
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Yuichi Ninomiya
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Yutaka Nakachi
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Mioko Iseki
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Hiroyasu Iwasa
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Masumi Akita
- Division of Morphological Science, Biomedical Research Center, Saitama Medical University, Iruma-gun, Saitama, Japan
| | - Tohru Tsukui
- Experimental Animal Laboratory, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Nobuyuki Shimozawa
- Division of Genomics Research, Life Science Research Center, Gifu University, Gifu, Japan
| | - Chizuru Ito
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Kiyotaka Toshimori
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Megumi Nishimukai
- Laboratory of Nutritional Biochemistry, Research Group of Food Science, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Hiroshi Hara
- Laboratory of Nutritional Biochemistry, Research Group of Food Science, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Ryouta Maeba
- Department of Biochemistry, Teikyo University School of Medicine, Itabashi-ku, Tokyo, Japan
| | - Tomoki Okazaki
- Department of Biochemistry, Teikyo University School of Medicine, Itabashi-ku, Tokyo, Japan
| | - Ali Nasser Ali Alodaib
- Developmental Genetics Department, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
- The National Newborn Screening Laboratory, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
| | - Mohammed Al Amoudi
- Developmental Genetics Department, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
- The National Newborn Screening Laboratory, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
| | - Minnie Jacob
- Developmental Genetics Department, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
- The National Newborn Screening Laboratory, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
| | - Fowzan S. Alkuraya
- Developmental Genetics Department, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
- Department of Pediatrics, King Khalid University Hospital and College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia
- Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Kingdom of Saudi Arabia
| | - Yasushi Horai
- Department of Internal Medicine, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan
| | - Mitsuhiro Watanabe
- Department of Internal Medicine, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan
- Graduate School of Media and Governance, Keio University, Tokyo, Japan
- Faculty of Environment and Information Studies, Keio University, Tokyo, Japan
| | - Hiromi Motegi
- Team for Advanced Development and Evaluation of Human Disease Models, Japan Mouse Clinic, BioResource Center (BRC), Tsukuba, Ibaraki, Japan
| | - Shigeharu Wakana
- The Japan Mouse Clinic, RIKEN BioResource Center (BRC), Tsukuba, Ibaraki, Japan
| | - Tetsuo Noda
- Team for Advanced Development and Evaluation of Human Disease Models, Japan Mouse Clinic, BioResource Center (BRC), Tsukuba, Ibaraki, Japan
- The Cancer Institute of the Japanese Foundation for Cancer Research, Koto-ku, Tokyo, Japan
| | - Igor V. Kurochkin
- Genome and Gene Expression Data Analysis Division, Bioinformatics Institute, A*STAR, Singapore, Republic of Singapore
| | - Yosuke Mizuno
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Christian Schönbach
- Division of Genomics and Genetics, School of Biological Sciences, Nanyang Technological University, Singapore, Republic of Singapore
| | - Yasushi Okazaki
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
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Polupanov AS, Nazarko VY, Sibirny AA. Gss1 protein of the methylotrophic yeast Pichia pastoris is involved in glucose sensing, pexophagy and catabolite repression. Int J Biochem Cell Biol 2012; 44:1906-18. [DOI: 10.1016/j.biocel.2012.07.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 06/29/2012] [Accepted: 07/17/2012] [Indexed: 10/28/2022]
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Mijaljica D, Nazarko TY, Brumell JH, Huang WP, Komatsu M, Prescott M, Simonsen A, Yamamoto A, Zhang H, Klionsky DJ, Devenish RJ. Receptor protein complexes are in control of autophagy. Autophagy 2012; 8:1701-5. [PMID: 22874568 DOI: 10.4161/auto.21332] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In autophagic processes a variety of cargos is delivered to the degradative compartment of cells. Recent progress in autophagy research has provided support for the notion that when autophagic processes are operating in selective mode, a receptor protein complex will process the cargo. Here we present a concept of receptor protein complexes as comprising a functional tetrad of components: a ligand, a receptor, a scaffold and an Atg8 family protein. Our current understanding of each of the four components and their interaction in the context of cargo selection are considered in turn.
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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, Australia
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Jiang Q, Zhao L, Dai J, Wu Q. Analysis of autophagy genes in microalgae: Chlorella as a potential model to study mechanism of autophagy. PLoS One 2012; 7:e41826. [PMID: 22848622 PMCID: PMC3407069 DOI: 10.1371/journal.pone.0041826] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 06/26/2012] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Microalgae, with the ability to mitigate CO(2) emission and produce carbohydrates and lipids, are considered one of the most promising resources for producing bioenergy. Recently, we discovered that autophagy plays a critical role in the metabolism of photosynthetic system and lipids production. So far, more than 30-autophagy related (ATG) genes in all subtypes of autophagy have been identified. However, compared with yeast and mammals, in silico and experimental research of autophagy pathways in microalgae remained limited and fragmentary. PRINCIPAL FINDINGS In this article, we performed a genome-wide analysis of ATG genes in 7 microalgae species and explored their distributions, domain structures and evolution. Eighteen "core autophagy machinery" proteins, four mammalian-specific ATG proteins and more than 30 additional proteins (including "receptor-adaptor" complexes) in all subtypes of autophagy were analyzed. Data revealed that receptor proteins in cytoplasm-to-vacuole targeting and mitophagy seem to be absent in microalgae. However, most of the "core autophagy machinery" and mammalian-specific proteins are conserved among microalgae, except for the ATG9-cycling system in Chlamydomonas reinhardtii and the second ubiquitin-like protein conjugation complex in several algal species. The catalytic and binding residues in ATG3, ATG5, ATG7, ATG8, ATG10 and ATG12 are also conserved and the phylogenetic tree of ATG8 coincides well with the phylogenies. Chlorella contains the entire set of the core autophagy machinery. In addition, RT-PCR analysis verified that all crucial ATG genes tested are expressed during autophagy in both Chlorella and Chlamydomonas reinhardtii. Finally, we discovered that addition of 3-Methyladenine (a PI3K specific inhibitor) could suppress the formation of autophagic vacuoles in Chlorella. CONCLUSIONS Taken together, Chlorella may represent a potential model organism to investigate autophagy pathways in photosynthetic eukaryotes. The study will not only promote understanding of the general features of autophagic pathways, but also benefit the production of Chlorella-derived biofuel with future commercial applications.
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Affiliation(s)
- Qiao Jiang
- MOE Key Laboratory of Bioinformatics and Center for Epigenetics and Chromatin, School of Life Sciences, Tsinghua University, Beijing, China
| | - Li Zhao
- MOE Key Laboratory of Bioinformatics and Center for Epigenetics and Chromatin, School of Life Sciences, Tsinghua University, Beijing, China
| | - Junbiao Dai
- MOE Key Laboratory of Bioinformatics and Center for Epigenetics and Chromatin, School of Life Sciences, Tsinghua University, Beijing, China
- * E-mail: (JD); (QW)
| | - Qingyu Wu
- MOE Key Laboratory of Bioinformatics and Center for Epigenetics and Chromatin, School of Life Sciences, Tsinghua University, Beijing, China
- * E-mail: (JD); (QW)
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Abstract
Autophagy, a highly conserved lysosomal degradation pathway, was initially characterized as a bulk degradation system induced in response to starvation. In recent years, autophagy has emerged also as a highly selective pathway, targeting various cargoes such as aggregated proteins and damaged organelles for degradation. The key factors involved in selective autophagy are autophagy receptors and adaptor proteins, which connect the cargo to the core autophagy machinery. In this review, we discuss the current knowledge about the only mammalian adaptor protein identified thus far, autophagy-linked FYVE protein (ALFY). ALFY is a large, scaffolding, multidomain protein implicated in the selective degradation of ubiquitinated protein aggregates by autophagy. We also comment on the possible role of ALFY in the context of disease.
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Autophagy: more than a nonselective pathway. Int J Cell Biol 2012; 2012:219625. [PMID: 22666256 PMCID: PMC3362037 DOI: 10.1155/2012/219625] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 02/07/2012] [Indexed: 12/11/2022] Open
Abstract
Autophagy is a catabolic pathway conserved among eukaryotes that allows cells to rapidly eliminate large unwanted structures such as aberrant protein aggregates, superfluous or damaged organelles, and invading pathogens. The hallmark of this transport pathway is the sequestration of the cargoes that have to be degraded in the lysosomes by double-membrane vesicles called autophagosomes. The key actors mediating the biogenesis of these carriers are the autophagy-related genes (ATGs). For a long time, it was assumed that autophagy is a bulk process. Recent studies, however, have highlighted the capacity of this pathway to exclusively eliminate specific structures and thus better fulfil the catabolic necessities of the cell. We are just starting to unveil the regulation and mechanism of these selective types of autophagy, but what it is already clearly emerging is that structures targeted to destruction are accurately enwrapped by autophagosomes through the action of specific receptors and adaptors. In this paper, we will briefly discuss the impact that the selective types of autophagy have had on our understanding of autophagy.
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Deng YZ, Qu Z, He Y, Naqvi NI. Sorting nexin Snx41 is essential for conidiation and mediates glutathione-based antioxidant defense during invasive growth in Magnaporthe oryzae. Autophagy 2012; 8:1058-70. [PMID: 22561104 DOI: 10.4161/auto.20217] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The sorting nexins Atg20/Snx42 and Snx41 regulate membrane traffic and endosomal protein sorting and are essential for Cvt and/or pexophagy in yeast. Previously, we showed that macroautophagy is necessary for conidiation in the rice-blast fungus Magnaporthe oryzae. Here, we analyzed the physiological function(s) of selective autophagy in Magnaporthe through targeted deletion of MGG_12832, an ortholog of yeast SNX41 and ATG20/SNX42. Loss of MGG_12832 (hereafter SNX41) abolished conidia formation and pathogenesis in M. oryzae. Snx41-GFP localized as dynamic puncta or short tubules that are partially associated with autophagosomes and/or autophagic vacuoles. PX domain, but not macroautophagy per se, was required for such localization of Snx41-GFP in Magnaporthe. Although not required for nonselective autophagy, Snx41 was essential for pexophagy in Magnaporthe. We identified Oxp1, an ATP-dependent oxoprolinase in the gamma-glutamyl cycle, as a binding partner and potential retrieval target of Snx41-dependent protein sorting. The substrate of Oxp1, 5-oxoproline, could partially restore conidiation in the snx41Δ. Exogenous glutathione, a product of the gamma-glutamyl cycle, significantly restored pathogenicity in the snx41Δ mutant, likely through counteracting the oxidative stress imposed by the host. We propose that the gamma-glutamyl cycle and glutathione biosynthesis are subject to regulation by Snx41-dependent vesicular trafficking, and mediate antioxidant defense crucial for in planta growth and pathogenic differentiation of Magnaporthe at the onset of blast disease in rice.
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Affiliation(s)
- Yi Zhen Deng
- Temasek Life Sciences Laboratory, and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore
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41
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Pexophagy: the selective degradation of peroxisomes. Int J Cell Biol 2012; 2012:512721. [PMID: 22536249 PMCID: PMC3320016 DOI: 10.1155/2012/512721] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Accepted: 11/23/2011] [Indexed: 12/18/2022] Open
Abstract
Peroxisomes are single-membrane-bounded organelles present in the majority of eukaryotic cells. Despite the existence of great diversity among different species, cell types, and under different environmental conditions, peroxisomes contain enzymes involved in β-oxidation of fatty acids and the generation, as well as detoxification, of hydrogen peroxide. The exigency of all eukaryotic cells to quickly adapt to different environmental factors requires the ability to precisely and efficiently control peroxisome number and functionality. Peroxisome homeostasis is achieved by the counterbalance between organelle biogenesis and degradation. The selective degradation of superfluous or damaged peroxisomes is facilitated by several tightly regulated pathways. The most prominent peroxisome degradation system uses components of the general autophagy core machinery and is therefore referred to as “pexophagy.” In this paper we focus on recent developments in pexophagy and provide an overview of current knowledge and future challenges in the field. We compare different modes of pexophagy and mention shared and distinct features of pexophagy in yeast model systems, mammalian cells, and other organisms.
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42
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Kondo-Okamoto N, Noda NN, Suzuki SW, Nakatogawa H, Takahashi I, Matsunami M, Hashimoto A, Inagaki F, Ohsumi Y, Okamoto K. Autophagy-related protein 32 acts as autophagic degron and directly initiates mitophagy. J Biol Chem 2012; 287:10631-10638. [PMID: 22308029 PMCID: PMC3323008 DOI: 10.1074/jbc.m111.299917] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 01/30/2012] [Indexed: 12/22/2022] Open
Abstract
Autophagy-related degradation selective for mitochondria (mitophagy) is an evolutionarily conserved process that is thought to be critical for mitochondrial quality and quantity control. In budding yeast, autophagy-related protein 32 (Atg32) is inserted into the outer membrane of mitochondria with its N- and C-terminal domains exposed to the cytosol and mitochondrial intermembrane space, respectively, and plays an essential role in mitophagy. Atg32 interacts with Atg8, a ubiquitin-like protein localized to the autophagosome, and Atg11, a scaffold protein required for selective autophagy-related pathways, although the significance of these interactions remains elusive. In addition, whether Atg32 is the sole protein necessary and sufficient for initiation of autophagosome formation has not been addressed. Here we show that the Atg32 IMS domain is dispensable for mitophagy. Notably, when anchored to peroxisomes, the Atg32 cytosol domain promoted autophagy-dependent peroxisome degradation, suggesting that Atg32 contains a module compatible for other organelle autophagy. X-ray crystallography reveals that the Atg32 Atg8 family-interacting motif peptide binds Atg8 in a conserved manner. Mutations in this binding interface impair association of Atg32 with the free form of Atg8 and mitophagy. Moreover, Atg32 variants, which do not stably interact with Atg11, are strongly defective in mitochondrial degradation. Finally, we demonstrate that Atg32 forms a complex with Atg8 and Atg11 prior to and independent of isolation membrane generation and subsequent autophagosome formation. Taken together, our data implicate Atg32 as a bipartite platform recruiting Atg8 and Atg11 to the mitochondrial surface and forming an initiator complex crucial for mitophagy.
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Affiliation(s)
- Noriko Kondo-Okamoto
- Laboratory of Mitochondrial Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Nobuo N Noda
- Department of Structural Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan, and
| | - Sho W Suzuki
- Frontier Research Center, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Hitoshi Nakatogawa
- Frontier Research Center, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Ikuko Takahashi
- Frontier Research Center, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Miou Matsunami
- Frontier Research Center, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Ayako Hashimoto
- Laboratory of Mitochondrial Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Fuyuhiko Inagaki
- Department of Structural Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan, and
| | - Yoshinori Ohsumi
- Frontier Research Center, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Koji Okamoto
- Laboratory of Mitochondrial Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan,.
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Sibirny AA. Mechanisms of autophagy and pexophagy in yeasts. BIOCHEMISTRY (MOSCOW) 2011; 76:1279-90. [DOI: 10.1134/s0006297911120017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Abstract
The mitochondrion is an organelle that carries out a number of important metabolic processes such as fatty acid oxidation, the citric acid cycle, and oxidative phosphorylation. However, this multitasking organelle also generates reactive oxygen species (ROS), which can cause oxidative stress resulting in self-damage. This type of mitochondrial damage can lead to the further production of ROS and a resulting downward spiral with regard to mitochondrial capability. This is extremely problematic because the accumulation of dysfunctional mitochondria is related to aging, cancer, and neurodegenerative diseases. Accordingly, appropriate quality control of this organelle is important to maintain proper cellular homeostasis. It has been thought that selective mitochondria autophagy (mitophagy) contributes to the maintenance of mitochondrial quality by eliminating damaged or excess mitochondria, although little is known about the mechanism. Recent studies in yeast identified several mitophagy-related proteins, which have been characterized with regard to their function and regulation. In this article, we review recent advances in the physiology and molecular mechanism of mitophagy and discuss the similarities and differences of this degradation process between yeast and mammalian cells.
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Affiliation(s)
- Tomotake Kanki
- Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
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45
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Dziedzic SA, Caplan AB. Identification of autophagy genes participating in zinc-induced necrotic cell death in Saccharomyces cerevisiae. Autophagy 2011; 7:490-500. [PMID: 21317551 DOI: 10.4161/auto.7.5.14872] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Eukaryotes use a common set of genes to perform two mechanistically similar autophagic processes. Bulk autophagy harvests proteins nonselectively and reuses their constitutents when nutrients are scarce. In contrast, different forms of selective autophagy target protein aggregates or damaged organelles that threaten to interfere with growth. Yeast uses one form of selective autophagy, called cytoplasm-to-vacuole targeting (Cvt), to engulf two vacuolar enzymes in Cvt vesicles ("CVT-somes") within which they are transported to vacuoles for maturation. While both are dispensable normally, bulk and selective autophagy help sustain life under stressful conditions. Consistent with this view, knocking out several genes participating in Cvt and specialized autophagic pathways heightened the sensitivity of Saccharomyces cerevisiae to inhibitory levels of Zn(2+). The loss of other autophagic genes, and genes responsible for apoptotic cell death, had no such effect. Unexpectedly, the loss of members of a third set of autophagy genes heightened cellular resistance to zinc as if they encoded proteins that actively contributed to zinc-induced cell death. Further studies showed that both sensitive and resistant strains accumulated similar amounts of H2O2 during zinc treatments, but that more sensitive strains showed signs of necrosis sooner. Although zinc lethality depended on autophagic proteins, studies with several reporter genes failed to reveal increased autophagic activity. In fact, microscopy analysis indicated that Zn(2+) partially inhibited fusion of Cvt vesicles with vacuoles. Further studies into how the loss of autophagic processes suppressed necrosis in yeast might reveal whether a similar process could occur in plants and animals.
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Affiliation(s)
- Slawomir A Dziedzic
- Department of Microbiology, Molecular Biology, and Biochemistry, University of Idaho, Moscow, ID, USA
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Nazarko VY, Nazarko TY, Farré JC, Stasyk OV, Warnecke D, Ulaszewski S, Cregg JM, Sibirny AA, Subramani S. Atg35, a micropexophagy-specific protein that regulates micropexophagic apparatus formation in Pichia pastoris. Autophagy 2011; 7:375-85. [PMID: 21169734 DOI: 10.4161/auto.7.4.14369] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Autophagy-related (Atg) pathways deliver cytosol and organelles to the vacuole in double-membrane vesicles called autophagosomes, which are formed at the phagophore assembly site (PAS), where most of the core Atg proteins assemble. Atg28 is a component of the core autophagic machinery partially required for all Atg pathways in Pichia pastoris. This coiled-coil protein interacts with Atg17 and is essential for micropexophagy. However, the role of Atg28 in micropexophagy was unknown. We used the yeast two-hybrid system to search for Atg28 interaction partners from P. pastoris and identified a new Atg protein, named Atg35. The atg35∆ mutant was not affected in macropexophagy, cytoplasm-to-vacuole targeting or general autophagy. However, both Atg28 and Atg35 were required for micropexophagy and for the formation of the micropexophagic apparatus (MIPA). This requirement correlated with a stronger expression of both proteins on methanol and glucose. Atg28 mediated the interaction of Atg35 with Atg17. Trafficking of overexpressed Atg17 from the peripheral ER to the nuclear envelope was required to organize a peri-nuclear structure (PNS), the site of Atg35 colocalization during micropexophagy. In summary, Atg35 is a new Atg protein that relocates to the PNS and specifically regulates MIPA formation during micropexophagy.
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Abstract
The accumulation of protein aggregates in neurons appears to be a basic feature of neurodegenerative disease. In Huntington's Disease (HD), a progressive and ultimately fatal neurodegenerative disorder caused by an expansion of the polyglutamine repeat within the protein Huntingtin (Htt), the immediate proximal cause of disease is well understood. However, the cellular mechanisms which modulate the rate at which fragments of Htt containing polyglutamine accumulate in neurons is a central issue in the development of approaches to modulate the rate and extent of neuronal loss in this disease. We have recently found that Htt is phosphorylated by the kinase IKK on serine (S) 13, activating its phosphorylation on S16 and its acetylation and poly-SUMOylation, modifications that modulate its clearance by the proteasome and lysosome in cells. In the discussion here I suggest that Htt may have a normal function in the lysosomal mechanism of selective macroautophagy involved in its own degradation which may share some similarity with the yeast cytoplasm to vacuole targeting (Cvt) pathway. Pharmacologic activation of this pathway may be useful early in disease progression to treat HD and other neurodegenerative diseases characterized by the accumulation of disease proteins.
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Affiliation(s)
- Joan S Steffan
- Department of Psychiatry and Human Behavior, University of California, Irvine, CA, USA.
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48
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Abstract
Autophagy is a major catabolic pathway in eukaryotes, which is required for the lysosomal/vacuolar degradation of cytoplasmic proteins and organelles. Interest in the autophagy pathway has recently gained momentum largely owing to identification of multiple autophagy-related genes and recognition of its involvement in various physiological conditions. Here we review current knowledge of the molecular mechanisms regulating autophagy in mammals and yeast, specifically the biogenesis of autophagosomes and the selectivity of their cargo recruitment. We discuss the different steps of autophagy, from the signal transduction events that regulate it to the completion of this pathway by fusion with the lysosome/vacuole. We also review research on the origin of the autophagic membrane, the molecular mechanism of autophagosome formation, and the roles of two ubiquitin-like protein families and other structural elements that are essential for this process. Finally, we discuss the various modes of autophagy and highlight their functional relevance for selective degradation of specific cargos.
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Affiliation(s)
- Hilla Weidberg
- Department of Biological Chemistry, The Weizmann Institute of Science, 76100 Rehovot, Israel
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49
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Abstract
The essential role of peroxisomes in fatty acid oxidation, anaplerotic metabolism, and hydrogen peroxide turnover is well established. Recent findings suggest that these and other related biochemical processes governed by the organelle may also play a critical role in regulating cellular aging. The goal of this review is to summarize and integrate into a model the evidence that peroxisome metabolism actually helps define the replicative and chronological age of a eukaryotic cell. In this model, peroxisomal reactive oxygen species (ROS) are seen as altering organelle biogenesis and function, and eliciting changes in the dynamic communication networks that exist between peroxisomes and other cellular compartments. At low levels, peroxisomal ROS activate an anti-aging program in the cell; at concentrations beyond a specific threshold, a pro-aging course is triggered.
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Affiliation(s)
- Vladimir I Titorenko
- Department of Biology, Concordia University, 7141 Sherbrooke Street, West, SP Building, Office SP-501-9, Montreal, Quebec H4B1R6, Canada.
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Reumann S, Voitsekhovskaja O, Lillo C. From signal transduction to autophagy of plant cell organelles: lessons from yeast and mammals and plant-specific features. PROTOPLASMA 2010; 247:233-56. [PMID: 20734094 DOI: 10.1007/s00709-010-0190-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2010] [Accepted: 07/28/2010] [Indexed: 05/08/2023]
Abstract
Autophagy is an evolutionarily conserved intracellular process for the vacuolar degradation of cytoplasmic constituents. The central structures of this pathway are newly formed double-membrane vesicles (autophagosomes) that deliver excess or damaged cell components into the vacuole or lysosome for proteolytic degradation and monomer recycling. Cellular remodeling by autophagy allows organisms to survive extensive phases of nutrient starvation and exposure to abiotic and biotic stress. Autophagy was initially studied by electron microscopy in diverse organisms, followed by molecular and genetic analyses first in yeast and subsequently in mammals and plants. Experimental data demonstrate that the basic principles, mechanisms, and components characterized in yeast are conserved in mammals and plants to a large extent. However, distinct autophagy pathways appear to differ between kingdoms. Even though direct information remains scarce particularly for plants, the picture is emerging that the signal transduction cascades triggering autophagy and the mechanisms of organelle turnover evolved further in higher eukaryotes for optimization of nutrient recycling. Here, we summarize new research data on nitrogen starvation-induced signal transduction and organelle autophagy and integrate this knowledge into plant physiology.
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Affiliation(s)
- Sigrun Reumann
- Centre for Organelle Research, University of Stavanger, 4021 Stavanger, Norway.
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