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Yang Y, Xiang Y, Niu Y. An Overview of the Molecular Mechanisms and Functions of Autophagic Pathways in Plants. PLANT SIGNALING & BEHAVIOR 2021; 16:1977527. [PMID: 34617497 PMCID: PMC9208794 DOI: 10.1080/15592324.2021.1977527] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 08/29/2021] [Accepted: 08/31/2021] [Indexed: 06/13/2023]
Abstract
Autophagy is an evolutionarily conserved pathway for the degradation of damaged or toxic components. Under normal conditions, autophagy maintains cellular homeostasis. It can be triggered by senescence and various stresses. In the process of autophagy, autophagy-related (ATG) proteins not only function as central signal regulators but also participate in the development of complex survival mechanisms when plants suffer from adverse environments. Therefore, ATGs play significant roles in metabolism, development and stress tolerance. In the past decade, both the molecular mechanisms of autophagy and a large number of components involved in the assembly of autophagic vesicles have been identified. In recent studies, an increasing number of components, mechanisms, and receptors have appeared in the autophagy pathway. In this paper, we mainly review the recent progress of research on the molecular mechanisms of plant autophagy, as well as its function under biotic stress and abiotic stress.
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Affiliation(s)
- Yang Yang
- Moe Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences,Lanzhou University, Lanzhou, China
| | - Yun Xiang
- Moe Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences,Lanzhou University, Lanzhou, China
| | - Yue Niu
- Moe Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences,Lanzhou University, Lanzhou, China
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2
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Research Progress of ATGs Involved in Plant Immunity and NPR1 Metabolism. Int J Mol Sci 2021; 22:ijms222212093. [PMID: 34829975 PMCID: PMC8623690 DOI: 10.3390/ijms222212093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 11/04/2021] [Accepted: 11/04/2021] [Indexed: 12/12/2022] Open
Abstract
Autophagy is an important pathway of degrading excess and abnormal proteins and organelles through their engulfment into autophagosomes that subsequently fuse with the vacuole. Autophagy-related genes (ATGs) are essential for the formation of autophagosomes. To date, about 35 ATGs have been identified in Arabidopsis, which are involved in the occurrence and regulation of autophagy. Among these, 17 proteins are related to resistance against plant pathogens. The transcription coactivator non-expressor of pathogenesis-related genes 1 (NPR1) is involved in innate immunity and acquired resistance in plants, which regulates most salicylic acid (SA)-responsive genes. This paper mainly summarizes the role of ATGs and NPR1 in plant immunity and the advancement of research on ATGs in NPR1 metabolism, providing a new idea for exploring the relationship between ATGs and NPR1.
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3
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Autophagy Dances with Phytohormones upon Multiple Stresses. PLANTS 2020; 9:plants9081038. [PMID: 32824209 PMCID: PMC7463709 DOI: 10.3390/plants9081038] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/11/2020] [Accepted: 08/14/2020] [Indexed: 12/12/2022]
Abstract
Autophagy is an evolutionarily conserved process for turning over unwanted cellular components, thus promoting nutrient recycling and maintaining cellular homeostasis, which eventually enables plants to survive unfavorable growth conditions. In addition to plant growth and development, previous studies have demonstrated that autophagy is involved in the responses to various environmental challenges through interplaying with multiple phytohormones, including abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA). In this review, we summarize the advances made in their synergistic interactions in response to multiple abiotic and biotic stresses; we also discuss the remaining issues and perspectives regarding their crosstalk.
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4
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Wojciechowska N, Smugarzewska I, Marzec-Schmidt K, Zarzyńska-Nowak A, Bagniewska-Zadworna A. Occurrence of autophagy during pioneer root and stem development in Populus trichocarpa. PLANTA 2019; 250:1789-1801. [PMID: 31451904 DOI: 10.1007/s00425-019-03265-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 08/19/2019] [Indexed: 05/26/2023]
Abstract
Autophagy is involved in developmentally programmed cell death and is identified during the early development of phloem, as well as xylem with a dual role, as both an inducer and executioner of cell death. The regulation of primary and secondary development of roots and stems is important for the establishment of root systems and for the overall survival of trees. The molecular and cellular basis of the autophagic processes, which are used at distinct moments during the growth of both organs, is crucial to understand the regulation of their development. To address this, we use Populus trichocarpa seedlings grown in a rhizotron system to examine the autophagy processes involved in root and stem development. To monitor the visual aspects of autophagy, transmission electron microscopy (TEM) and immunolocalization of AuTophaGy-related protein (ATG8) enabled observations of the phenomenon at a structural level. To gain further insight into the autophagy process at the protein and molecular level, we evaluated the expression of ATG gene transcripts and ATG protein levels. Alternations in the expression level of specific ATG genes and localization of ATG8 proteins were observed during the course of root or stem primary and secondary development. Specifically, ATG8 was present in the cells exhibiting autophagy, during the differentiation and early development of xylem and phloem tissues, including both xylary and extraxylary fibers. Ultrastructural observations revealed tonoplast invagination with the formation of autophagic-like bodies. Additionally, the accumulation of autophagosomes was identifiable during the differentiation of xylem in both organs, long before the commencement of cell death. Taken together, these results provide evidence in support of the dual role of autophagy in developmental PCD. A specific role of the controller of cell death, which is a committed step with the release of hydrolytic enzymes from the vacuole and final digestion of protoplast, from which there is no return once initiated, is only attributed to mega-autophagy.
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Affiliation(s)
- Natalia Wojciechowska
- Department of General Botany, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland
| | - Iga Smugarzewska
- Department of General Botany, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland
| | - Katarzyna Marzec-Schmidt
- Department of General Botany, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland
| | - Aleksandra Zarzyńska-Nowak
- Department of Virology and Bacteriology, Institute of Plant Protection-National Research Institute, Wł. Węgorka 20, 60-318, Poznań, Poland
| | - Agnieszka Bagniewska-Zadworna
- Department of General Botany, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland.
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5
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Liu G, Zeng H, Li X, Wei Y, Shi H. Functional Analysis of MaWRKY24 in Transcriptional Activation of Autophagy-Related Gene 8f/g and Plant Disease Susceptibility to Soil-Borne Fusarium oxysporum f. sp. cubense. Pathogens 2019; 8:pathogens8040264. [PMID: 31775365 PMCID: PMC6963284 DOI: 10.3390/pathogens8040264] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 11/16/2019] [Accepted: 11/20/2019] [Indexed: 11/16/2022] Open
Abstract
WRKYs play important roles in plant development and stress responses. Although MaWRKYs have been comprehensively identified in the banana (Musa acuminata), their in vivo roles and direct targets remain elusive. In this study, a transcript profile analysis indicated the common regulation of MaWRKYs transcripts in response to fungal pathogen Fusarium oxysporum f. sp. cubense (Foc). Among these MaWRKYs, MaWRKY24 was chosen for further analysis due to its higher expression in response to Foc. The specific nucleus subcellular location and transcription activated activity on W-box indicated that MaWRKY24 was a transcription factor. The correlation analysis of gene expression indicated that MaWRKYs were closely related to autophagy-associated genes (MaATG8s). Further analysis showed that MaWRKY24 directly regulated the transcriptional level of MaATG8f/g through binding to W-box in their promoters, as evidenced by quantitative real-time Polymerase Chain Reaction (PCR), dual luciferase assay, and electrophoretic mobility shift assay. In addition, overexpression of MaWRKY24 and MaATG8f/g resulted in disease susceptibility to Foc, which might be related to the activation of autophagic activity. This study highlights the positive regulation of MaWRKY24 in transcriptional activation of autophagy-related gene 8f/g in the banana and their common roles in disease susceptibility to soil-borne Foc, indicating the effects of MaWRKY24 on autophagy and disease susceptibility.
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Affiliation(s)
| | | | | | | | - Haitao Shi
- Correspondence: ; Tel.: +86-898-66160721
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6
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Sadhu A, Moriyasu Y, Acharya K, Bandyopadhyay M. Nitric oxide and ROS mediate autophagy and regulate Alternaria alternata toxin-induced cell death in tobacco BY-2 cells. Sci Rep 2019; 9:8973. [PMID: 31222105 PMCID: PMC6586778 DOI: 10.1038/s41598-019-45470-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 05/09/2019] [Indexed: 11/25/2022] Open
Abstract
Synergistic interaction of nitric oxide (NO) and reactive oxygen species (ROS) is essential to initiate cell death mechanisms in plants. Though autophagy is salient in either restricting or promoting hypersensitivity response (HR)-related cell death, the crosstalk between the reactive intermediates and autophagy during hypersensitivity response is paradoxical. In this investigation, the consequences of Alternaria alternata toxin (AaT) in tobacco BY-2 cells were examined. At 3 h, AaT perturbed intracellular ROS homeostasis, altered antioxidant enzyme activities, triggered mitochondrial depolarization and induced autophagy. Suppression of autophagy by 3-Methyladenine caused a decline in cell viability in AaT treated cells, which indicated the vital role of autophagy in cell survival. After 24 h, AaT facilitated Ca2+ influx with an accumulation of reactive oxidant intermediates and NO, to manifest necrotic cell death. Inhibition of NO accumulation by 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) decreased the level of necrotic cell death, and induced autophagy, which suggests NO accumulation represses autophagy and facilitates necrotic cell death at 24 h. Application of N-acetyl-L-cysteine at 3 h, confirmed ROS to be the key initiator of autophagy, and together with cPTIO for 24 h, revealed the combined effects of NO and ROS is required for necrotic HR cell death.
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Affiliation(s)
- Abhishek Sadhu
- Plant Molecular Cytogenetics Laboratory, Centre of Advanced Study, Department of Botany, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, West Bengal, India
| | - Yuji Moriyasu
- Graduate School of Science and Engineering, Saitama University, Shimo-Okubo 255, Saitama, 338-8570, Japan
| | - Krishnendu Acharya
- Molecular and Applied Mycology and Plant Pathology Laboratory, Centre of Advanced Study, Department of Botany, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, West Bengal, India
| | - Maumita Bandyopadhyay
- Plant Molecular Cytogenetics Laboratory, Centre of Advanced Study, Department of Botany, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, West Bengal, India.
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7
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Signorelli S, Tarkowski ŁP, Van den Ende W, Bassham DC. Linking Autophagy to Abiotic and Biotic Stress Responses. TRENDS IN PLANT SCIENCE 2019; 24:413-430. [PMID: 30824355 PMCID: PMC6475611 DOI: 10.1016/j.tplants.2019.02.001] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 02/01/2019] [Accepted: 02/04/2019] [Indexed: 05/05/2023]
Abstract
Autophagy is a process in which cellular components are delivered to lytic vacuoles to be recycled and has been demonstrated to promote abiotic/biotic stress tolerance. Here, we review how the responses triggered by stress conditions can affect autophagy and its signaling pathways. Besides the role of SNF-related kinase 1 (SnRK1) and TOR kinases in the regulation of autophagy, abscisic acid (ABA) and its signaling kinase SnRK2 have emerged as key players in the induction of autophagy under stress conditions. Furthermore, an interplay between reactive oxygen species (ROS) and autophagy is observed, ROS being able to induce autophagy and autophagy able to reduce ROS production. We also highlight the importance of osmotic adjustment for the successful performance of autophagy and discuss the potential role of GABA in plant survival and ethylene (ET)-induced autophagy.
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Affiliation(s)
- Santiago Signorelli
- Laboratory of Molecular Plant Biology, KU Leuven, Leuven, Belgium; Departamento de Biología Vegetal, Facultad de Agronomía, Universidad de la República, Montevideo 12900, Uruguay.
| | | | - Wim Van den Ende
- Laboratory of Molecular Plant Biology, KU Leuven, Leuven, Belgium
| | - Diane C Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
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Wei Y, Liu W, Hu W, Liu G, Wu C, Liu W, Zeng H, He C, Shi H. Genome-wide analysis of autophagy-related genes in banana highlights MaATG8s in cell death and autophagy in immune response to Fusarium wilt. PLANT CELL REPORTS 2017; 36:1237-1250. [PMID: 28451821 DOI: 10.1007/s00299-017-2149-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 04/22/2017] [Indexed: 05/02/2023]
Abstract
MaATG8s play important roles in hypersensitive-like cell death and immune response, and autophagy is essential for disease resistance against Foc in banana. Autophagy is responsible for the degradation of damaged cytoplasmic constituents in the lysosomes or vacuoles. Although the effects of autophagy have been extensively revealed in model plants, the possible roles of autophagy-related gene in banana remain unknown. In this study, 32 MaATGs were identified in the draft genome, and the profiles of several MaATGs in response to fungal pathogen Fusarium oxysporum f. sp. cubense (Foc) were also revealled. We found that seven MaATG8s were commonly regulated by Foc. Through transient expression in Nicotiana benthamiana leaves, we highlight the novel roles of MaATG8s in conferring hypersensitive-like cell death, and MaATG8s-mediated hypersensitive response-like cell death is dependent on autophagy. Notablly, autophagy inhibitor 3-methyladenine (3-MA) treatment resulted in decreased disease resistance in response to Foc4, and the effect of 3-MA treatment could be rescued by exogenous salicylic acid, jasmonic acid and ethylene, indicating the involvement of autophagy-mediated plant hormones in banana resistance to Fusarium wilt. Taken together, this study may extend our understanding the putative role of MaATG8s in hypersensitive-like cell death and the essential role of autophagy in immune response against Foc in banana.
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Affiliation(s)
- Yunxie Wei
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources and College of Biology, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Wen Liu
- Biotechnology Research Center, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang, 443002, Hubei, China
| | - Wei Hu
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, Hainan, China
| | - Guoyin Liu
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources and College of Biology, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Chunjie Wu
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources and College of Biology, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Wei Liu
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources and College of Biology, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Hongqiu Zeng
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources and College of Biology, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Chaozu He
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources and College of Biology, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Haitao Shi
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources and College of Biology, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China.
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Zheng Y, Qiu Y, Gunderson JEC, Schulman BA. Production of Human ATG Proteins for Lipidation Assays. Methods Enzymol 2016; 587:97-113. [PMID: 28253979 DOI: 10.1016/bs.mie.2016.09.055] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Humans express several orthologs of yeast Atg8, in the LC3 and GABARAP families, which play crucial roles in autophagy through their covalent ligation to lipids, typically phosphatidylethanolamine (PE), in a process known as lipidation. Lipidation of LC3 and GABARAP regulates numerous facets of the autophagy process, including regulating expansion of the phagophore membrane, recruiting selected cargoes for degradation, and providing an autophagosome membrane-bound platform mediating dynamic interactions with other regulatory proteins. LC3 and GABARAP are families of related ubiquitin-like proteins (UBLs) (referred to here collectively as LC3/GABARAP), and their lipidation involves a divergent UBL conjugation cascade including ATG7, ATG3, and ATG12~ATG5-ATG16L1 acting as E1, E2, and E3 enzymes, respectively. ATG7 initiates LC3/GABARAP conjugation by catalyzing their C-terminal adenylation and conjugation to the catalytic cysteine of ATG3. Ultimately, the ATG12~ATG5-ATG16L1 complex catalyzes LC3/GABARAP ligation to a primary amino group on PE or other acceptor lipids. This chapter describes methods for expressing and purifying human LC3 or GABARAP, ATG7, ATG3, and the ATG12~ATG5-ATG16L1 complex for in vitro studies of LC3/GABARAP lipidation.
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Affiliation(s)
- Y Zheng
- St. Jude Children's Research Hospital, Memphis, TN, United States; University of Tennessee Health Science Center, Memphis, TN, United States
| | - Y Qiu
- St. Jude Children's Research Hospital, Memphis, TN, United States
| | - J E C Gunderson
- St. Jude Children's Research Hospital, Memphis, TN, United States; Hendrix College, Conway, AR, United States
| | - B A Schulman
- St. Jude Children's Research Hospital, Memphis, TN, United States; University of Tennessee Health Science Center, Memphis, TN, United States; Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, TN United States.
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10
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Xiong J. Atg7 in development and disease: panacea or Pandora's Box? Protein Cell 2015; 6:722-34. [PMID: 26404030 PMCID: PMC4598325 DOI: 10.1007/s13238-015-0195-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 07/13/2015] [Indexed: 01/15/2023] Open
Abstract
Macroautophagy is an evolutionarily conserved intracellular degradation system used by life ranging from yeasts to mammals. The core autophagic machinery is composed of ATG (autophagy-related) protein constituents. One particular member of the ATG protein family, Atg7, has been the focus of recent research. Atg7 acts as an E1-like activating enzyme facilitating both microtubule-associated protein light chain 3 (LC3)-phosphatidylethanolamine and ATG12 conjugation. Thus, Atg7 stands at the hub of these two ubiquitin-like systems involving LC3 and Atg12 in autophagic vesicle expansion. In this review, I focus on the pleiotropic function of Atg7 in development, maintenance of health, and alternations of such control in disease.
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Affiliation(s)
- Jianhua Xiong
- Center for Molecular Medicine, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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11
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Ye Y, Tan S, Zhou X, Li X, Jundt MC, Lichter N, Hidebrand A, Dhasarathy A, Wu M. Inhibition of p-IκBα Ubiquitylation by Autophagy-Related Gene 7 to Regulate Inflammatory Responses to Bacterial Infection. J Infect Dis 2015; 212:1816-26. [PMID: 26022442 DOI: 10.1093/infdis/jiv301] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 05/14/2015] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Klebsiella pneumoniae causes serious infections and healthcare burdens in humans. We have previously reported that the deficiency of autophagy-related gene (Atg) 7 in macrophages (murine alveolar macrophage cell line [MH-S]) induced irregular host immunity against K. pneumoniae and worsened pathologic effects in the lung. In the current study, we investigated the molecular mechanism by which Atg7 influenced K. pneumoniae-induced inflammatory responses. METHODS Expression levels of Atg7, ubiquitin (Ub), and tumor necrosis factor (TNF) α and phosphorylation of IκBα (p-IκBα) were determined with immunoblotting. Ubiquitylation of p-IκBα was determined with immunoprecipitation. RESULTS We noted an interaction between Atg7 and p-IκBα, which was decreased in MH-S after K. pneumoniae infection, whereas the interaction between Ub and p-IκBα was increased. Knock-down of Atg7 with small interfering RNA increased p-IκBα ubiquitylation, promoted nuclear factor κB translocation into the nucleus, and increased the production of TNF-α. Moreover, knock-down of Ub with lentivirus-short hairpin RNA Ub particles decreased binding of p-IκBα to Ub and inhibited TNF-α expression in the primary alveolar macrophages and lung tissue of atg7-knockout mice on K. pneumoniae infection. CONCLUSIONS Loss of Atg7 switched binding of p-IκBα from Atg7 to Ub, resulting in increased ubiquitylation of p-IκBα and intensified inflammatory responses against K. pneumoniae. Our findings not only reveal a regulatory role of Atg7 in ubiquitylation of p-IκBα but also indicate potential therapeutic targets for K. pneumoniae control.
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Affiliation(s)
- Yan Ye
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks
| | - Shirui Tan
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks Laboratory of Biochemistry and Molecular Biology, School of Life Sciences, Yunnan University, Kunming
| | - Xikun Zhou
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks State Key Laboratory of Biotherapy, Sichuan University, Chengdu, China
| | - Xuefeng Li
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks State Key Laboratory of Biotherapy, Sichuan University, Chengdu, China
| | - Michael C Jundt
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks
| | - Natalie Lichter
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks
| | - Alec Hidebrand
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks
| | - Archana Dhasarathy
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks
| | - Min Wu
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks
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12
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Li X, Ye Y, Zhou X, Huang C, Wu M. Atg7 enhances host defense against infection via downregulation of superoxide but upregulation of nitric oxide. THE JOURNAL OF IMMUNOLOGY 2014; 194:1112-21. [PMID: 25535282 DOI: 10.4049/jimmunol.1401958] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic bacterium that can cause serious infection in immunocompromised individuals. Although autophagy may augment immune responses against P. aeruginosa infection in macrophages, the critical components and their role of autophagy in host defense are largely unknown. In this study, we show that P. aeruginosa infection-induced autophagy activates JAK2/STAT1α and increases NO production. Knocking down Atg7 resulted in increased IFN-γ release, excessive reactive oxygen species, and increased Src homology-2 domain-containing phosphatase 2 activity, which led to lowered phosphorylation of JAK2/STAT1α and subdued expression of NO synthase 2 (NOS2). In addition, we demonstrated the physiological relevance of dysregulated NO under Atg7 deficiency as atg7(-/-) mice were more susceptible to P. aeruginosa infection with increased mortality and severe lung injury than wild-type mice. Furthermore, P. aeruginosa-infected atg7(-/-) mice exhibited increased oxidation but decreased bacterial clearance in the lung and other organs compared with wild-type mice. Mechanistically, atg7 deficiency suppressed NOS2 activity by downmodulating JAK2/STAT1α, leading to decreased NO both in vitro and in vivo. Taken together, these findings revealed that the JAK2/STAT1α/NOS2 dysfunction leads to dysregulated immune responses and worsened disease phenotypes.
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Affiliation(s)
- Xuefeng Li
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203; and State Key Laboratory of Biotherapy/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, People's Republic of China
| | - Yan Ye
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203; and
| | - Xikun Zhou
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203; and State Key Laboratory of Biotherapy/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, People's Republic of China
| | - Canhua Huang
- State Key Laboratory of Biotherapy/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, People's Republic of China
| | - Min Wu
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203; and
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13
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Ye Y, Li X, Wang W, Ouedraogo KC, Li Y, Gan C, Tan S, Zhou X, Wu M. Atg7 deficiency impairs host defense against Klebsiella pneumoniae by impacting bacterial clearance, survival and inflammatory responses in mice. Am J Physiol Lung Cell Mol Physiol 2014; 307:L355-63. [PMID: 24993132 DOI: 10.1152/ajplung.00046.2014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Klebsiella pneumoniae (Kp) is a Gram-negative bacterium that can cause serious infections in humans. Autophagy-related gene 7 (Atg7) has been implicated in certain bacterial infections; however, the role of Atg7 in macrophage-mediated immunity against Kp infection has not been elucidated. Here we showed that Atg7 expression was significantly increased in murine alveolar macrophages (MH-S) upon Kp infection, indicating that Atg7 participated in host defense. Knocking down Atg7 with small-interfering RNA increased bacterial burdens in MH-S cells. Using cell biology assays and whole animal imaging analysis, we found that compared with wild-type mice atg7 knockout (KO) mice exhibited increased susceptibility to Kp infection, with decreased survival rates, decreased bacterial clearance, and intensified lung injury. Moreover, Kp infection induced excessive proinflammatory cytokines and superoxide in the lung of atg7 KO mice. Similarly, silencing Atg7 in MH-S cells markedly increased expression levels of proinflammatory cytokines. Collectively, these findings reveal that Atg7 offers critical resistance to Kp infection by modulating both systemic and local production of proinflammatory cytokines.
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Affiliation(s)
- Yan Ye
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota
| | - Xuefeng Li
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota
| | - Wenxue Wang
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota
| | - Kiswendsida Claude Ouedraogo
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota
| | - Yi Li
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota
| | - Changpei Gan
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota
| | - Shirui Tan
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota
| | - Xikun Zhou
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota
| | - Min Wu
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota
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Lv X, Pu X, Qin G, Zhu T, Lin H. The roles of autophagy in development and stress responses in Arabidopsis thaliana. Apoptosis 2014; 19:905-21. [DOI: 10.1007/s10495-014-0981-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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15
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Li F, Vierstra RD. Autophagy: a multifaceted intracellular system for bulk and selective recycling. TRENDS IN PLANT SCIENCE 2012; 17:526-37. [PMID: 22694835 DOI: 10.1016/j.tplants.2012.05.006] [Citation(s) in RCA: 250] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 04/30/2012] [Accepted: 05/02/2012] [Indexed: 05/18/2023]
Abstract
Plants have evolved sophisticated mechanisms to recycle intracellular constituents. One gaining in appreciation is autophagy, which involves specialized vesicles engulfing and delivering unwanted cytoplasmic material to the vacuole for breakdown. Central to this process is the ubiquitin-fold protein autophagy (ATG)-8, which becomes tethered to the developing autophagic membranes by lipidation. Here, we review data showing that the ATG8 moiety provides a docking site not only for proteins that help shape the enclosing vesicles and promote their fusion with the tonoplast, but also for a host of receptors that recruit appropriate autophagic cargo. The identity of these receptors has dramatically altered the view of autophagy as being a relatively nonspecific mechanism to one that may selectively sequester aggregated proteins, protein complexes, organelles, and even invading pathogens.
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Affiliation(s)
- Faqiang Li
- Department of Genetics, 425-G Henry Mall, University of Wisconsin-Madison, Madison, WI 53706, USA
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16
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Role of macroautophagy in nutrient homeostasis during fungal development and pathogenesis. Cells 2012; 1:449-63. [PMID: 24710485 PMCID: PMC3901100 DOI: 10.3390/cells1030449] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/07/2012] [Accepted: 07/17/2012] [Indexed: 11/29/2022] Open
Abstract
Macroautophagy is a non-selective, bulk degradation process conserved in eukaryotes. Response to starvation stress and/or regulation of nutrient breakdown/utilization is the major intracellular function of macroautophagy. Recent studies have revealed requirement for autophagy in diverse functions such as nutrient homeostasis, organelle degradation and programmed cell death in filamentous fungal pathogens, for proper morphogenesis and differentiation during critical steps of infection. In this review, we aim to summarize the physiological functions of autophagy in fungal virulence, with an emphasis on nutrient homeostasis in opportunistic human fungal pathogens and in the rice-blast fungus, Magnaporthe oryzae. We briefly summarize the role of autophagy on the host side: for resistance to, or subversion by, the pathogens.
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17
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Insights into noncanonical E1 enzyme activation from the structure of autophagic E1 Atg7 with Atg8. Nat Struct Mol Biol 2011; 18:1323-30. [PMID: 22056771 DOI: 10.1038/nsmb.2165] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 09/27/2011] [Indexed: 12/11/2022]
Abstract
Autophagy is the degradation of cellular organelles via the lysosomal pathway. The autophagic ubiquitin-like (Ubl) molecule Atg8 is activated by the E1-like enzyme Atg7. As this noncanonical E1 enzyme's domain organization is unique among Ubl-activating E1 enzymes, the structural basis for its interactions with Atg8 and partner E2 enzymes remains obscure. Here we present the structure of the N-terminal domain of Atg7, revealing a unique protein fold and interactions with both autophagic E2 enzymes Atg3 and Atg10. The structure of the C-terminal domain of Atg7 in complex with Atg8 shows the mode of dimerization and mechanism of recognition of Atg8. Notably, the catalytic cysteine residue in Atg7 is positioned close to the C-terminal glycine of Atg8, its target for thioester formation, potentially eliminating the need for large conformational rearrangements characteristic of other E1s.
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Wang Y, Wu Y, Tang D. The autophagy gene, ATG18a, plays a negative role in powdery mildew resistance and mildew-induced cell death in Arabidopsis. PLANT SIGNALING & BEHAVIOR 2011; 6:1408-10. [PMID: 21847024 PMCID: PMC3258078 DOI: 10.4161/psb.6.9.16967] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 07/08/2011] [Accepted: 07/08/2011] [Indexed: 05/18/2023]
Abstract
Autophagy is a conserved intracellular recycling system that traffics cellular organelles and cytosolic proteins within lysosomes for reuse or breakdown in eukaryotes. Increased evidence indicates that autophagy is involved in programmed cell death and disease resistance in plants. We recently showed that atg2, atg5, atg7 and atg10 displayed early senescence and cell death in later growth stage under nutrient-rich conditions in Arabidopsis thaliana. These mutants also exhibited powdery mildew resistance and mildew-induced cell death. Salicylic acid (SA) signaling is required for atg2-mediated powdery mildew resistance, however, inactivation of SA signaling is not sufficient to fully suppress powdery mildew-induced cell death in atg2 mutant1. Here, we show that atg18a-2 is also resistant to the powdery mildew pathogen, Golovinomyces cichoracearum, and it shows mildew-induced cell death similar to the atg2 mutant. Taken together, our study reveals that autophagy plays important roles in suppression of cell death and defense response to the biotrophic pathogen, the powdery mildew fungus. Future work on autophagy in plants will shine light on how autophagy is involved in cell death and defense response in plants.
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Affiliation(s)
- Yiping Wang
- State Key Laboratory of Plant Cell and Chromosome Engineering; Institute of Genetics and Developmental Biology; Chinese Academy of Sciences; Beijing, China
- Graduate University of Chinese Academy of Sciences; Beijing, China
| | - Yingying Wu
- State Key Laboratory of Plant Cell and Chromosome Engineering; Institute of Genetics and Developmental Biology; Chinese Academy of Sciences; Beijing, China
- Graduate University of Chinese Academy of Sciences; Beijing, China
| | - Dingzhong Tang
- State Key Laboratory of Plant Cell and Chromosome Engineering; Institute of Genetics and Developmental Biology; Chinese Academy of Sciences; Beijing, China
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