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Liu L, Tang Y, Zhou Z, Huang Y, Zhang R, Lyu H, Xiao S, Guo D, Ali DW, Michalak M, Chen XZ, Zhou C, Tang J. Membrane Curvature: The Inseparable Companion of Autophagy. Cells 2023; 12:1132. [PMID: 37190041 PMCID: PMC10136490 DOI: 10.3390/cells12081132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 04/06/2023] [Accepted: 04/10/2023] [Indexed: 05/17/2023] Open
Abstract
Autophagy is a highly conserved recycling process of eukaryotic cells that degrades protein aggregates or damaged organelles with the participation of autophagy-related proteins. Membrane bending is a key step in autophagosome membrane formation and nucleation. A variety of autophagy-related proteins (ATGs) are needed to sense and generate membrane curvature, which then complete the membrane remodeling process. The Atg1 complex, Atg2-Atg18 complex, Vps34 complex, Atg12-Atg5 conjugation system, Atg8-phosphatidylethanolamine conjugation system, and transmembrane protein Atg9 promote the production of autophagosomal membranes directly or indirectly through their specific structures to alter membrane curvature. There are three common mechanisms to explain the change in membrane curvature. For example, the BAR domain of Bif-1 senses and tethers Atg9 vesicles to change the membrane curvature of the isolation membrane (IM), and the Atg9 vesicles are reported as a source of the IM in the autophagy process. The amphiphilic helix of Bif-1 inserts directly into the phospholipid bilayer, causing membrane asymmetry, and thus changing the membrane curvature of the IM. Atg2 forms a pathway for lipid transport from the endoplasmic reticulum to the IM, and this pathway also contributes to the formation of the IM. In this review, we introduce the phenomena and causes of membrane curvature changes in the process of macroautophagy, and the mechanisms of ATGs in membrane curvature and autophagosome membrane formation.
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Affiliation(s)
- Lei Liu
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
- National “111” Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China
| | - Yu Tang
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
- National “111” Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China
| | - Zijuan Zhou
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
- National “111” Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China
| | - Yuan Huang
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Rui Zhang
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Hao Lyu
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Shuai Xiao
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Dong Guo
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Declan William Ali
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Xing-Zhen Chen
- Membrane Protein Disease Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Cefan Zhou
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Jingfeng Tang
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
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Schreiber A, Collins BC, Davis C, Enchev RI, Sedra A, D'Antuono R, Aebersold R, Peter M. Multilayered regulation of autophagy by the Atg1 kinase orchestrates spatial and temporal control of autophagosome formation. Mol Cell 2021; 81:5066-5081.e10. [PMID: 34798055 PMCID: PMC8693860 DOI: 10.1016/j.molcel.2021.10.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 07/23/2021] [Accepted: 10/26/2021] [Indexed: 12/26/2022]
Abstract
Autophagy is a conserved intracellular degradation pathway exerting various cytoprotective and homeostatic functions by using de novo double-membrane vesicle (autophagosome) formation to target a wide range of cytoplasmic material for vacuolar/lysosomal degradation. The Atg1 kinase is one of its key regulators, coordinating a complex signaling program to orchestrate autophagosome formation. Combining in vitro reconstitution and cell-based approaches, we demonstrate that Atg1 is activated by lipidated Atg8 (Atg8-PE), stimulating substrate phosphorylation along the growing autophagosomal membrane. Atg1-dependent phosphorylation of Atg13 triggers Atg1 complex dissociation, enabling rapid turnover of Atg1 complex subunits at the pre-autophagosomal structure (PAS). Moreover, Atg1 recruitment by Atg8-PE self-regulates Atg8-PE levels in the growing autophagosomal membrane by phosphorylating and thus inhibiting the Atg8-specific E2 and E3. Our work uncovers the molecular basis for positive and negative feedback imposed by Atg1 and how opposing phosphorylation and dephosphorylation events underlie the spatiotemporal regulation of autophagy.
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Affiliation(s)
- Anne Schreiber
- Cellular Degradation Systems Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT London, UK; Institute of Biochemistry, ETH Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland.
| | - Ben C Collins
- Institute of Molecular Systems Biology, ETH Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland; School of Biological Sciences, Queen's University of Belfast, 19 Chlorine Gardens, BT9 5DL Belfast, UK
| | - Colin Davis
- Cellular Degradation Systems Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT London, UK
| | - Radoslav I Enchev
- Institute of Biochemistry, ETH Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland; Visual Biochemistry Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT London, UK
| | - Angie Sedra
- Institute of Biochemistry, ETH Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Rocco D'Antuono
- Crick Advanced Light Microscopy (CALM) STP, The Francis Crick Institute, 1 Midland Road, NW1 1AT London, UK
| | - Ruedi Aebersold
- Institute of Molecular Systems Biology, ETH Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Matthias Peter
- Institute of Biochemistry, ETH Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland.
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Licheva M, Raman B, Kraft C, Reggiori F. Phosphoregulation of the autophagy machinery by kinases and phosphatases. Autophagy 2021; 18:104-123. [PMID: 33970777 PMCID: PMC8865292 DOI: 10.1080/15548627.2021.1909407] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic cells use post-translational modifications to diversify and dynamically coordinate the function and properties of protein networks within various cellular processes. For example, the process of autophagy strongly depends on the balanced action of kinases and phosphatases. Highly conserved from the budding yeast Saccharomyces cerevisiae to humans, autophagy is a tightly regulated self-degradation process that is crucial for survival, stress adaptation, maintenance of cellular and organismal homeostasis, and cell differentiation and development. Many studies have emphasized the importance of kinases and phosphatases in the regulation of autophagy and identified many of the core autophagy proteins as their direct targets. In this review, we summarize the current knowledge on kinases and phosphatases acting on the core autophagy machinery and discuss the relevance of phosphoregulation for the overall process of autophagy.
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Affiliation(s)
- Mariya Licheva
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Babu Raman
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, AV Groningen, The Netherlands
| | - Claudine Kraft
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, AV Groningen, The Netherlands
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Wang F, Zhang R, Feng W, Tsuchiya D, Ballew O, Li J, Denic V, Lacefield S. Autophagy of an Amyloid-like Translational Repressor Regulates Meiotic Exit. Dev Cell 2020; 52:141-151.e5. [PMID: 31991104 DOI: 10.1016/j.devcel.2019.12.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 09/26/2019] [Accepted: 12/26/2019] [Indexed: 12/30/2022]
Abstract
We explored the potential for autophagy to regulate budding yeast meiosis. Following pre-meiotic DNA replication, we blocked autophagy by chemical inhibition of Atg1 kinase or engineered degradation of Atg14 and observed homologous chromosome segregation followed by sister chromatid separation; cells then underwent additional rounds of spindle formation and disassembly without DNA re-replication, leading to aberrant chromosome segregation. Analysis of cell-cycle regulators revealed that autophagy inhibition prevents meiosis II-specific expression of Clb3 and leads to the aberrant persistence of Clb1 and Cdc5, two substrates of a meiotic ubiquitin ligase activated by Ama1. Lastly, we found that during meiosis II, autophagy degrades Rim4, an amyloid-like translational repressor whose timed clearance regulates protein production from its mRNA targets, which include CLB3 and AMA1. Strikingly, engineered Clb3 or Ama1 production restored meiotic termination in the absence of autophagy. Thus, autophagy destroys a master regulator of meiotic gene expression to enable irreversible meiotic exit.
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Affiliation(s)
- Fei Wang
- Department of Internal Medicine, Center for Autophagy Research, UT Southwestern Medical Center, Dallas, TX, USA.
| | - Rudian Zhang
- Department of Internal Medicine, Center for Autophagy Research, UT Southwestern Medical Center, Dallas, TX, USA
| | - Wenzhi Feng
- Department of Internal Medicine, Center for Autophagy Research, UT Southwestern Medical Center, Dallas, TX, USA
| | - Dai Tsuchiya
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Olivia Ballew
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Jiajia Li
- Department of Internal Medicine, Center for Autophagy Research, UT Southwestern Medical Center, Dallas, TX, USA
| | - Vladimir Denic
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
| | - Soni Lacefield
- Department of Biology, Indiana University, Bloomington, IN, USA.
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Zhang Y, Xie Y, Liu W, Deng W, Peng D, Wang C, Xu H, Ruan C, Deng Y, Guo Y, Lu C, Yi C, Ren J, Xue Y. DeepPhagy: a deep learning framework for quantitatively measuring autophagy activity in Saccharomyces cerevisiae. Autophagy 2019; 16:626-640. [PMID: 31204567 DOI: 10.1080/15548627.2019.1632622] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Seeing is believing. The direct observation of GFP-Atg8 vacuolar delivery under confocal microscopy is one of the most useful end-point measurements for monitoring yeast macroautophagy/autophagy. However, manually labelling individual cells from large-scale sets of images is time-consuming and labor-intensive, which has greatly hampered its extensive use in functional screens. Herein, we conducted a time-course analysis of nitrogen starvation-induced autophagy in wild-type and knockout mutants of 35 AuTophaGy-related (ATG) genes in Saccharomyces cerevisiae and obtained 1,944 confocal images containing > 200,000 cells. We manually labelled 8,078 autophagic and 18,493 non-autophagic cells as a benchmark dataset and developed a new deep learning tool for autophagy (DeepPhagy), which exhibited superior accuracy in recognizing autophagic cells compared to other existing methods, with an area under the curve (AUC) value of 0.9710 from 10-fold cross-validations. We further used DeepPhagy to automatically analyze all the images and quantitatively classified the autophagic phenotypes of the 35 atg knockout mutants into 3 classes. The high consistency in our computational and biochemical results indicated the reliability of DeepPhagy for measuring autophagic activity. Moreover, we used DeepPhagy to analyze 3 additional types of autophagic phenotypes, including the targeting of Atg1-GFP to the vacuole, the vacuolar delivery of GFP-Atg19, and the disintegration of autophagic bodies indicated by GFP-Atg8, all with satisfying accuracies. Taken together, our study not only enables the GFP-Atg8 fluorescence assay to become a quantitative measurement for analyzing autophagic phenotypes in S. cerevisiae but also demonstrates that deep learning-based methods could potentially be applied to different types of autophagy.Abbreviations: Ac: accuracy; ALP: alkaline phosphatase; ALR: autophagic lysosomal reformation; ATG: AuTophaGy-related; AUC: area under the curve; CNN: convolutional neural network; Cvt: cytoplasm-to-vacuole targeting; DeepPhagy: deep learning for autophagy; fc_2: second fully connected; GFP: green fluorescent protein; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3 beta; HAT: histone acetyltransferase; HemI: Heat map Illustrator; JRE: Java Runtime Environment; KO: knockout; LRN: local response normalization; MCC: Mathew Correlation Coefficient; OS: operating system; PAS: phagophore assembly site; PC: principal component; PCA: principal component analysis; PPI: protein-protein interaction; Pr: precision; QPSO: Quantum-behaved Particle Swarm Optimization; ReLU: rectified linear unit; RF: random forest; ROC: receiver operating characteristic; ROI: region of interest; SD: systematic derivation; SGD: stochastic gradient descent; Sn: sensitivity; Sp: specificity; SRG: seeded region growing; t-SNE: t-distributed stochastic neighbor embedding; 2D: 2-dimensional; WT: wild-type.
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Affiliation(s)
- Ying Zhang
- Department of Bioinformatics and Systems Biology, Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Bioinformatics and Molecular Imaging Key Laboratory, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Yubin Xie
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wenzhong Liu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wankun Deng
- Department of Bioinformatics and Systems Biology, Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Bioinformatics and Molecular Imaging Key Laboratory, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Di Peng
- Department of Bioinformatics and Systems Biology, Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Bioinformatics and Molecular Imaging Key Laboratory, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Chenwei Wang
- Department of Bioinformatics and Systems Biology, Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Bioinformatics and Molecular Imaging Key Laboratory, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Haodong Xu
- Department of Bioinformatics and Systems Biology, Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Bioinformatics and Molecular Imaging Key Laboratory, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Chen Ruan
- Department of Bioinformatics and Systems Biology, Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Bioinformatics and Molecular Imaging Key Laboratory, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Yongjie Deng
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yaping Guo
- Department of Bioinformatics and Systems Biology, Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Bioinformatics and Molecular Imaging Key Laboratory, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Chenjun Lu
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou, China
| | - Cong Yi
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cell Biology, Zhejiang University School of Medicine, Hangzhou, China
| | - Jian Ren
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yu Xue
- Department of Bioinformatics and Systems Biology, Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Bioinformatics and Molecular Imaging Key Laboratory, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
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Role of Some Natural Antioxidants in the Modulation of Some Proteins Expressions against Sodium Fluoride-Induced Renal Injury. BIOMED RESEARCH INTERNATIONAL 2018; 2018:5614803. [PMID: 30050936 PMCID: PMC6046187 DOI: 10.1155/2018/5614803] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 05/28/2018] [Accepted: 06/06/2018] [Indexed: 12/28/2022]
Abstract
Background The aim of the present work is to find the effects of N-acetylcysteine (NAC) and/or thymoquinone (THQ) in the protection against acute renal injury induced by sodium fluoride (NaF). Method Rats were distributed into five groups: G1 was normal (control), G2 was intoxicated with 10mg/kg NaF i.p., G3 was treated with 10mg THQ /kg, G4 was treated with 20mg NAC /kg, and G5 was treated with a combination of THQ and NAC. The previous treatments were given daily along with NaF for four weeks orally. Result Rats intoxicated with NaF showed a significant increase in serum urea, creatinine, uric acid, renal lipid peroxidation, nitric oxide, and TNF-α levels, whereas the activity of superoxide dismutase (SOD) and glutathione (GSH) level was reduced. The expressions of Toll-like receptor-4 (TLR4), Lipocalin, vascular adhesion molecule-1(VCAM-1), and BAX proteins were upregulated, whereas Bcl-2 and NF-E2-related factor 2 (Nrf2) proteins expressions were downregulated. DNA fragmentation was also amplified. Histological analysis revealed that NaF caused a destructive renal cortex in the form of the glomerular corpuscle, the obliterated proximal and distal convoluted tubules, vacuolization in tubular cells focal necrosis, and cell infiltration. THQ and NAC supplementation counteracted NaF-induced nephrotoxicity as reflected by the increase in renal GSH and SOD. THQ and NAC ameliorated all the altered proteins expressions, improved renal architecture, and declined DNA fragmentation. Conclusion The role of oxidative stress in the enhancement of NaF toxicity suggested the renoprotective effects of NAC and THQ against the toxicity of fluoride via multiple mechanisms.
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Gómez-Sánchez R, Sánchez-Wandelmer J, Reggiori F. Monitoring the Formation of Autophagosomal Precursor Structures in Yeast Saccharomyces cerevisiae. Methods Enzymol 2017; 588:323-365. [DOI: 10.1016/bs.mie.2016.09.085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Wen X, Klionsky DJ. An overview of macroautophagy in yeast. J Mol Biol 2016; 428:1681-99. [PMID: 26908221 DOI: 10.1016/j.jmb.2016.02.021] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 02/15/2016] [Accepted: 02/16/2016] [Indexed: 12/19/2022]
Abstract
Macroautophagy is an evolutionarily conserved dynamic pathway that functions primarily in a degradative manner. A basal level of macroautophagy occurs constitutively, but this process can be further induced in response to various types of stress including starvation, hypoxia and hormonal stimuli. The general principle behind macroautophagy is that cytoplasmic contents can be sequestered within a transient double-membrane organelle, an autophagosome, which subsequently fuses with a lysosome or vacuole (in mammals, or yeast and plants, respectively), allowing for degradation of the cargo followed by recycling of the resulting macromolecules. Through this basic mechanism, macroautophagy has a critical role in cellular homeostasis; however, either insufficient or excessive macroautophagy can seriously compromise cell physiology, and thus, it needs to be properly regulated. In fact, a wide range of diseases are associated with dysregulation of macroautophagy. There has been substantial progress in understanding the regulation and molecular mechanisms of macroautophagy in different organisms; however, many questions concerning some of the most fundamental aspects of macroautophagy remain unresolved. In this review, we summarize current knowledge about macroautophagy mainly in yeast, including the mechanism of autophagosome biogenesis, the function of the core macroautophagic machinery, the regulation of macroautophagy and the process of cargo recognition in selective macroautophagy, with the goal of providing insights into some of the key unanswered questions in this field.
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Affiliation(s)
- Xin Wen
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Daniel J Klionsky
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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Zhu J, Deng S, Lu P, Bu W, Li T, Yu L, Xie Z. The Ccl1-Kin28 kinase complex regulates autophagy under nitrogen starvation. J Cell Sci 2015; 129:135-44. [PMID: 26567215 DOI: 10.1242/jcs.177071] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 11/06/2015] [Indexed: 01/15/2023] Open
Abstract
Starvation triggers global alterations in the synthesis and turnover of proteins. Under such conditions, the recycling of essential nutrients by using autophagy is indispensable for survival. By screening known kinases in the yeast genome, we newly identified a regulator of autophagy, the Ccl1-Kin28 kinase complex (the equivalent of the mammalian cyclin-H-Cdk7 complex), which is known to play key roles in RNA-polymerase-II-mediated transcription. We show that inactivation of Ccl1 caused complete block of autophagy. Interestingly, Ccl1 itself was subject to proteasomal degradation, limiting the level of autophagy during prolonged starvation. We present further evidence that the Ccl1-Kin28 complex regulates the expression of Atg29 and Atg31, which is crucial in the assembly of the Atg1 kinase complex. The identification of this previously unknown regulatory pathway sheds new light on the complex signaling network that governs autophagy activity.
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Affiliation(s)
- Jing Zhu
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Shuangsheng Deng
- School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Puzhong Lu
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Wenting Bu
- Division of Structure Biology & Biochemistry, School of Biological Sciences, Nanyang Technological University, Singapore 138673, Singapore
| | - Tian Li
- School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Li Yu
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Zhiping Xie
- Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
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Popelka H, Klionsky DJ. Post-translationally-modified structures in the autophagy machinery: an integrative perspective. FEBS J 2015; 282:3474-88. [PMID: 26108642 DOI: 10.1111/febs.13356] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 06/11/2015] [Accepted: 06/19/2015] [Indexed: 01/10/2023]
Abstract
Autophagy is a self-cleaning process that occurs at a constitutive basal level, and is upregulated in response to stress. Macroautophagy (hereafter autophagy) is the most robust type of autophagy, where cargo (specific or nonspecific) is engulfed within a double-membrane structure termed an autophagosome. This process needs to be tightly regulated to maintain normal cellular homeostasis and prevent dysfunction; therefore, a fuller knowledge of the mechanisms of autophagy regulation is crucial for understanding the entire pathway. The autophagy-related proteins are the primary components that carry out autophagy. Many of these proteins are conserved from yeast to humans. A number of significant discoveries with regard to protein functional domains, protein-protein interactions or post-translational modifications of proteins involved in autophagy have been reported in parallel with, or followed by, solving the NMR or crystal structures of autophagy proteins or their protein domains. In the present review, we summarize structural insights gathered to date on the proteins of the autophagy machinery that are modulated by a post-translational modification, specifically phosphorylation, acetylation, ubiquitination and/or SUMOylation. For each protein, we link the reported results with information on the propensity of the corresponding amino acid sequence toward order/disorder. This integrative approach yields a comprehensive overview for each post-translationally modified protein, and also reveals areas for further investigation.
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Affiliation(s)
- Hana Popelka
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
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