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Wu L, Jin W, Yu H, Liu B. Modulating autophagy to treat diseases: A revisited review on in silico methods. J Adv Res 2024; 58:175-191. [PMID: 37192730 PMCID: PMC10982871 DOI: 10.1016/j.jare.2023.05.002] [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: 12/30/2022] [Revised: 05/05/2023] [Accepted: 05/09/2023] [Indexed: 05/18/2023] Open
Abstract
BACKGROUND Autophagy refers to the conserved cellular catabolic process relevant to lysosome activity and plays a vital role in maintaining the dynamic equilibrium of intracellular matter by degrading harmful and abnormally accumulated cellular components. Accumulating evidence has recently revealed that dysregulation of autophagy by genetic and exogenous interventions may disrupt cellular homeostasis in human diseases. In silico approaches as powerful aids to experiments have also been extensively reported to play their critical roles in the storage, prediction, and analysis of massive amounts of experimental data. Thus, modulating autophagy to treat diseases by in silico methods would be anticipated. AIM OF REVIEW Here, we focus on summarizing the updated in silico approaches including databases, systems biology network approaches, omics-based analyses, mathematical models, and artificial intelligence (AI) methods that sought to modulate autophagy for potential therapeutic purposes, which will provide a new insight into more promising therapeutic strategies. KEY SCIENTIFIC CONCEPTS OF REVIEW Autophagy-related databases are the data basis of the in silico method, storing a large amount of information about DNA, RNA, proteins, small molecules and diseases. The systems biology approach is a method to systematically study the interrelationships among biological processes including autophagy from a macroscopic perspective. Omics-based analyses are based on high-throughput data to analyze gene expression at different levels of biological processes involving autophagy. mathematical models are visualization methods to describe the dynamic process of autophagy, and its accuracy is related to the selection of parameters. AI methods use big data related to autophagy to predict autophagy targets, design targeted small molecules, and classify diverse human diseases for potential therapeutic applications.
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Affiliation(s)
- Lifeng Wu
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Wenke Jin
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Haiyang Yu
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China; Haihe Laboratory of Modern Chinese Medicine, Tianjin 301617, China.
| | - Bo Liu
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
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2
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Li GL, Han YQ, Su BQ, Yu HS, Zhang S, Yang GY, Wang J, Liu F, Ming SL, Chu BB. Porcine reproductive and respiratory syndrome virus 2 hijacks CMA-mediated lipolysis through upregulation of small GTPase RAB18. PLoS Pathog 2024; 20:e1012123. [PMID: 38607975 PMCID: PMC11014436 DOI: 10.1371/journal.ppat.1012123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 03/14/2024] [Indexed: 04/14/2024] Open
Abstract
RAB GTPases (RABs) control intracellular membrane trafficking with high precision. In the present study, we carried out a short hairpin RNA (shRNA) screen focused on a library of 62 RABs during infection with porcine reproductive and respiratory syndrome virus 2 (PRRSV-2), a member of the family Arteriviridae. We found that 13 RABs negatively affect the yield of PRRSV-2 progeny virus, whereas 29 RABs have a positive impact on the yield of PRRSV-2 progeny virus. Further analysis revealed that PRRSV-2 infection transcriptionally regulated RAB18 through RIG-I/MAVS-mediated canonical NF-κB activation. Disrupting RAB18 expression led to the accumulation of lipid droplets (LDs), impaired LDs catabolism, and flawed viral replication and assembly. We also discovered that PRRSV-2 co-opts chaperone-mediated autophagy (CMA) for lipolysis via RAB18, as indicated by the enhanced associations between RAB18 and perlipin 2 (PLIN2), CMA-specific lysosomal associated membrane protein 2A (LAMP2A), and heat shock protein family A (Hsp70) member 8 (HSPA8/HSC70) during PRRSV-2 infection. Knockdown of HSPA8 and LAMP2A impacted on the yield of PRRSV-2 progeny virus, implying that the virus utilizes RAB18 to promote CMA-mediated lipolysis. Importantly, we determined that the C-terminal domain (CTD) of HSPA8 could bind to the switch II domain of RAB18, and the CTD of PLIN2 was capable of associating with HSPA8, suggesting that HSPA8 facilitates the interaction between RAB18 and PLIN2 in the CMA process. In summary, our findings elucidate how PRRSV-2 hijacks CMA-mediated lipid metabolism through innate immune activation to enhance the yield of progeny virus, offering novel insights for the development of anti-PRRSV-2 treatments.
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Affiliation(s)
- Guo-Li Li
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan Province, China
- Key Laboratory of Animal Biochemistry and Nutrition, Zhengzhou, Henan Province, Ministry of Agriculture and Rural Affairs of the People’s Republic of China
- Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, Henan Province, China
| | - Ying-Qian Han
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan Province, China
- Key Laboratory of Animal Biochemistry and Nutrition, Zhengzhou, Henan Province, Ministry of Agriculture and Rural Affairs of the People’s Republic of China
- Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, Henan Province, China
| | - Bing-Qian Su
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan Province, China
- Key Laboratory of Animal Biochemistry and Nutrition, Zhengzhou, Henan Province, Ministry of Agriculture and Rural Affairs of the People’s Republic of China
- Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, Henan Province, China
| | - Hai-Shen Yu
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan Province, China
- Key Laboratory of Animal Biochemistry and Nutrition, Zhengzhou, Henan Province, Ministry of Agriculture and Rural Affairs of the People’s Republic of China
- Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, Henan Province, China
| | - Shuang Zhang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan Province, China
- Key Laboratory of Animal Biochemistry and Nutrition, Zhengzhou, Henan Province, Ministry of Agriculture and Rural Affairs of the People’s Republic of China
- Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, Henan Province, China
| | - Guo-Yu Yang
- Key Laboratory of Animal Biochemistry and Nutrition, Zhengzhou, Henan Province, Ministry of Agriculture and Rural Affairs of the People’s Republic of China
- Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, Henan Province, China
| | - Jiang Wang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan Province, China
- Key Laboratory of Animal Biochemistry and Nutrition, Zhengzhou, Henan Province, Ministry of Agriculture and Rural Affairs of the People’s Republic of China
- Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, Henan Province, China
- Ministry of Education Key Laboratory for Animal Pathogens and Biosafety, Zhengzhou, Henan Province, China
| | - Fang Liu
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan Province, China
| | - Sheng-Li Ming
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan Province, China
- Key Laboratory of Animal Biochemistry and Nutrition, Zhengzhou, Henan Province, Ministry of Agriculture and Rural Affairs of the People’s Republic of China
- Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, Henan Province, China
| | - Bei-Bei Chu
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan Province, China
- Key Laboratory of Animal Biochemistry and Nutrition, Zhengzhou, Henan Province, Ministry of Agriculture and Rural Affairs of the People’s Republic of China
- Key Laboratory of Veterinary Biotechnology of Henan Province, Zhengzhou, Henan Province, China
- Ministry of Education Key Laboratory for Animal Pathogens and Biosafety, Zhengzhou, Henan Province, China
- International Joint Research Center of National Animal Immunology, Henan Agricultural University, Zhengzhou, Henan Province, China
- Longhu Advanced Immunization Laboratory, Zhengzhou, Henan Province, China
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3
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Aljuraysi S, Platt M, Pulix M, Poptani H, Plagge A. Microcephaly with a disproportionate hippocampal reduction, stem cell loss and neuronal lipid droplet symptoms in Trappc9 KO mice. Neurobiol Dis 2024; 192:106431. [PMID: 38331351 DOI: 10.1016/j.nbd.2024.106431] [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: 12/04/2023] [Revised: 01/23/2024] [Accepted: 02/04/2024] [Indexed: 02/10/2024] Open
Abstract
Mutations of the human TRAFFICKING PROTEIN PARTICLE COMPLEX SUBUNIT 9 (TRAPPC9) cause a neurodevelopmental disorder characterised by microcephaly and intellectual disability. Trappc9 constitutes a subunit specific to the intracellular membrane-associated TrappII complex. The TrappII complex interacts with Rab11 and Rab18, the latter being specifically associated with lipid droplets (LDs). Here we used non-invasive imaging to characterise Trappc9 knock-out (KO) mice as a model of the human hereditary disorder. KOs developed postnatal microcephaly with many grey and white matter regions being affected. In vivo magnetic resonance imaging (MRI) identified a disproportionately stronger volume reduction in the hippocampus, which was associated with a significant loss of Sox2-positive neural stem and progenitor cells. Diffusion tensor imaging indicated a reduced organisation or integrity of white matter areas. Trappc9 KOs displayed behavioural abnormalities in several tests related to exploration, learning and memory. Trappc9-deficient primary hippocampal neurons accumulated a larger LD volume per cell following Oleic Acid stimulation, and the coating of LDs by Perilipin-2 was much reduced. Additionally, Trappc9 KOs developed obesity, which was significantly more severe in females than in males. Our findings indicate that, beyond previously reported Rab11-related vesicle transport defects, dysfunctions in LD homeostasis might contribute to the neurobiological symptoms of Trappc9 deficiency.
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Affiliation(s)
- Sultan Aljuraysi
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK; Department of Physiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Mark Platt
- Department of Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK; Centre for Preclinical Imaging, University of Liverpool, Liverpool, UK
| | - Michela Pulix
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Harish Poptani
- Department of Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK; Centre for Preclinical Imaging, University of Liverpool, Liverpool, UK.
| | - Antonius Plagge
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK; Centre for Preclinical Imaging, University of Liverpool, Liverpool, UK.
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4
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Kiss RS, Chicoine J, Khalil Y, Sladek R, Chen H, Pisaturo A, Martin C, Dale JD, Brudenell TA, Kamath A, Kyei-Boahen J, Hafiane A, Daliah G, Alecki C, Hopes TS, Heier M, Aligianis IA, Lebrun JJ, Aspden J, Paci E, Kerksiek A, Lütjohann D, Clayton P, Wills JC, von Kriegsheim A, Nilsson T, Sheridan E, Handley MT. Comparative proximity biotinylation implicates the small GTPase RAB18 in sterol mobilization and biosynthesis. J Biol Chem 2023; 299:105295. [PMID: 37774976 PMCID: PMC10641524 DOI: 10.1016/j.jbc.2023.105295] [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: 03/16/2023] [Revised: 09/14/2023] [Accepted: 09/17/2023] [Indexed: 10/01/2023] Open
Abstract
Loss of functional RAB18 causes the autosomal recessive condition Warburg Micro syndrome. To better understand this disease, we used proximity biotinylation to generate an inventory of potential RAB18 effectors. A restricted set of 28 RAB18 interactions were dependent on the binary RAB3GAP1-RAB3GAP2 RAB18-guanine nucleotide exchange factor complex. Twelve of these 28 interactions are supported by prior reports, and we have directly validated novel interactions with SEC22A, TMCO4, and INPP5B. Consistent with a role for RAB18 in regulating membrane contact sites, interactors included groups of microtubule/membrane-remodeling proteins, membrane-tethering and docking proteins, and lipid-modifying/transporting proteins. Two of the putative interactors, EBP and OSBPL2/ORP2, have sterol substrates. EBP is a Δ8-Δ7 sterol isomerase, and ORP2 is a lipid transport protein. This prompted us to investigate a role for RAB18 in cholesterol biosynthesis. We found that the cholesterol precursor and EBP-product lathosterol accumulates in both RAB18-null HeLa cells and RAB3GAP1-null fibroblasts derived from an affected individual. Furthermore, de novo cholesterol biosynthesis is impaired in cells in which RAB18 is absent or dysregulated or in which ORP2 expression is disrupted. Our data demonstrate that guanine nucleotide exchange factor-dependent Rab interactions are highly amenable to interrogation by proximity biotinylation and may suggest that Micro syndrome is a cholesterol biosynthesis disorder.
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Affiliation(s)
- Robert S Kiss
- Cardiovascular Health Across the Lifespan (CHAL) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.
| | - Jarred Chicoine
- Metabolic Disorders and Complications (MEDIC) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Youssef Khalil
- Genetics and Genomic Medicine, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Robert Sladek
- Metabolic Disorders and Complications (MEDIC) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - He Chen
- Cardiovascular Health Across the Lifespan (CHAL) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Alessandro Pisaturo
- Cardiovascular Health Across the Lifespan (CHAL) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Cyril Martin
- Cardiovascular Health Across the Lifespan (CHAL) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Jessica D Dale
- Leeds Institute of Medical Research, St James's University Hospital, Leeds, United Kingdom
| | - Tegan A Brudenell
- Leeds Institute of Medical Research, St James's University Hospital, Leeds, United Kingdom
| | - Archith Kamath
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, United Kingdom; Division of Medical Sciences, University of Oxford, Oxford, United Kingdom
| | - Jeffrey Kyei-Boahen
- Department of Medicine, McGill University Health Centre, CHAL Research Program, Montreal, Canada
| | - Anouar Hafiane
- Department of Medicine, McGill University Health Centre, CHAL Research Program, Montreal, Canada
| | - Girija Daliah
- Department of Medicine, McGill University Health Centre, Cancer Research Program, Montreal, Canada
| | - Célia Alecki
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Tayah S Hopes
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Martin Heier
- Department of Clinical Neuroscience for Children, Oslo University Hospital, Oslo, Norway
| | - Irene A Aligianis
- Medical and Developmental Genetics, Medical Research Council Human Genetics Unit, Edinburgh, United Kingdom
| | - Jean-Jacques Lebrun
- Department of Medicine, McGill University Health Centre, Cancer Research Program, Montreal, Canada
| | - Julie Aspden
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Emanuele Paci
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Anja Kerksiek
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Dieter Lütjohann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Peter Clayton
- Genetics and Genomic Medicine, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Jimi C Wills
- Cancer Research United Kingdom Edinburgh Centre, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, United Kingdom; Firefinch Software Ltd, Edinburgh, United Kingdom
| | - Alex von Kriegsheim
- Cancer Research United Kingdom Edinburgh Centre, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, United Kingdom
| | - Tommy Nilsson
- Cancer Research Program (CRP), Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Eamonn Sheridan
- Leeds Institute of Medical Research, St James's University Hospital, Leeds, United Kingdom
| | - Mark T Handley
- Leeds Institute of Medical Research, St James's University Hospital, Leeds, United Kingdom; Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.
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5
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Su P, Chen JG, Tang DH. Exercise against nonalcoholic fatty liver disease: Possible role and mechanism of lipophagy. Life Sci 2023; 327:121837. [PMID: 37301321 DOI: 10.1016/j.lfs.2023.121837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/25/2023] [Accepted: 06/05/2023] [Indexed: 06/12/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease worldwide. NAFLD is prevalent in about 30% of people worldwide. The lack of physical activity is considered as one of the risks for NAFLD, and approximately one-third of NAFLD patients hardly engage in physical activity. It is acknowledged that exercise is one of the optimal non-pharmacological methods for preventing and treating NAFLD. Different forms of exercise such as aerobic exercise, resistance exercise and even simply physical activity in a higher level can be beneficial in reducing liver lipid accumulation and disease progression for NAFLD patients. In NAFLD patients, exercise is helpful in lowering steatosis and enhancing liver function. The mechanisms underlying the prevention and treatment of NAFLD by exercise are various and complex. Current studies on the mechanisms have focused on the pro-lipolytic, anti-inflammatory, and antioxidant and lipophagy. Promotion of lipophagy is regarded as an important mechanism for prevention and improvement of NAFLD by exercise. Recent studies have investigated the above mechanism, yet the potential mechanism has not been completely elucidated. Thus, in this review, we cover the recent advances of exercise-promoted lipophagy in NAFLD treatment and prevention. Furthermore, given the fact that exercise activates SIRT1, we discuss the possible regulatory mechanisms of lipophagy by SIRT1 during exercise. These mechanisms need to be verified by further experimental studies.
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Affiliation(s)
- Pei Su
- Department of College of P.E. and Sport, Beijing Normal University, No. 19, Xinjiekouwai St, Haidian District, Beijing 100875, People's Republic of China.
| | - Jian-Gang Chen
- Department of College of P.E. and Sport, Beijing Normal University, No. 19, Xinjiekouwai St, Haidian District, Beijing 100875, People's Republic of China.
| | - Dong-Hui Tang
- Department of College of P.E. and Sport, Beijing Normal University, No. 19, Xinjiekouwai St, Haidian District, Beijing 100875, People's Republic of China.
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6
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Chen WF, Wang HF, Wang Y, Liu ZG, Xu BH. AmAtg2B-Mediated Lipophagy Regulates Lipolysis of Pupae in Apis mellifera. Int J Mol Sci 2023; 24:2096. [PMID: 36768418 PMCID: PMC9916532 DOI: 10.3390/ijms24032096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/23/2022] [Accepted: 12/29/2022] [Indexed: 01/21/2023] Open
Abstract
Lipophagy plays an important role in regulating lipid metabolism in mammals. The exact function of autophagy-related protein 2 (Atg2) has been investigated in mammals, but research on the existence and functions of Atg2 in Apis mellifera (AmAtg2) is still limited. Here, autophagy occurred in honeybee pupae, which targeted lipid droplets (LDs) in fat body, namely lipophagy, which was verified by co-localization of LDs with microtubule-associated protein 1A/1B light chain 3 beta (LC3). Moreover, AmAtg2 homolog B (AmAtg2B) was expressed specifically in pupal fat body, which indicated that AmAtg2B might have special function in fat body. Further, AmAtg2B antibody neutralization and AmAtg2B knock-down were undertaken to verify the functions in pupae. Results showed that low expression of AmAtg2B at the protein and transcriptional levels led to lipophagy inhibition, which down-regulated the expression levels of proteins and genes related to lipolysis. Altogether, results in this study systematically revealed that AmAtg2B interfered with lipophagy and then caused abnormal lipolysis in the pupal stage.
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Affiliation(s)
| | | | | | | | - Bao-Hua Xu
- College of Animal Science and Technology, Shandong Agricultural University, Tai’an 271018, China
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Ge S, Zhang RX, Wang YF, Sun P, Chu J, Li J, Sun P, Wang J, Hetherington AM, Liang YK. The Arabidopsis Rab protein RABC1 affects stomatal development by regulating lipid droplet dynamics. THE PLANT CELL 2022; 34:4274-4292. [PMID: 35929087 PMCID: PMC9614440 DOI: 10.1093/plcell/koac239] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 07/13/2022] [Indexed: 05/13/2023]
Abstract
Lipid droplets (LDs) are evolutionarily conserved organelles that serve as hubs of cellular lipid and energy metabolism in virtually all organisms. Mobilization of LDs is important in light-induced stomatal opening. However, whether and how LDs are involved in stomatal development remains unknown. We show here that Arabidopsis thaliana LIPID DROPLETS AND STOMATA 1 (LDS1)/RABC1 (At1g43890) encodes a member of the Rab GTPase family that is involved in regulating LD dynamics and stomatal morphogenesis. The expression of RABC1 is coordinated with the different phases of stomatal development. RABC1 targets to the surface of LDs in response to oleic acid application in a RABC1GEF1-dependent manner. RABC1 physically interacts with SEIPIN2/3, two orthologues of mammalian seipin, which function in the formation of LDs. Disruption of RABC1, RABC1GEF1, or SEIPIN2/3 resulted in aberrantly large LDs, severe defects in guard cell vacuole morphology, and stomatal function. In conclusion, these findings reveal an aspect of LD function and uncover a role for lipid metabolism in stomatal development in plants.
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Affiliation(s)
| | | | - Yi-Fei Wang
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
- Hubei Hongshan Laboratory, Wuhan 430070, China
| | - Pengyue Sun
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
- Hubei Hongshan Laboratory, Wuhan 430070, China
| | - Jiaheng Chu
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jiao Li
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Peng Sun
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jianbo Wang
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Alistair M Hetherington
- School of Biological Sciences, Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
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Schmitt D, Bozkurt S, Henning‐Domres P, Huesmann H, Eimer S, Bindila L, Behrends C, Boyle E, Wilfling F, Tascher G, Münch C, Behl C, Kern A. Lipid and protein content profiling of isolated native autophagic vesicles. EMBO Rep 2022; 23:e53065. [PMID: 36215690 PMCID: PMC9724672 DOI: 10.15252/embr.202153065] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 09/16/2022] [Accepted: 09/20/2022] [Indexed: 11/07/2022] Open
Abstract
Autophagy is responsible for clearance of an extensive portfolio of cargoes, which are sequestered into vesicles, called autophagosomes, and are delivered to lysosomes for degradation. The pathway is highly dynamic and responsive to several stress conditions. However, the phospholipid composition and protein contents of human autophagosomes under changing autophagy rates are elusive so far. Here, we introduce an antibody-based FACS-mediated approach for the isolation of native autophagic vesicles and ensured the quality of the preparations. Employing quantitative lipidomics, we analyze phospholipids present within human autophagic vesicles purified upon basal autophagy, starvation, and proteasome inhibition. Importantly, besides phosphoglycerides, we identify sphingomyelin within autophagic vesicles and show that the phospholipid composition is unaffected by the different conditions. Employing quantitative proteomics, we obtain cargo profiles of autophagic vesicles isolated upon the different treatment paradigms. Interestingly, starvation shows only subtle effects, while proteasome inhibition results in the enhanced presence of ubiquitin-proteasome pathway factors within autophagic vesicles. Thus, here we present a powerful method for the isolation of native autophagic vesicles, which enabled profound phospholipid and cargo analyses.
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Affiliation(s)
- Daniel Schmitt
- The Autophagy Lab, Institute of PathobiochemistryUniversity Medical Center of the Johannes Gutenberg UniversityMainzGermany
| | - Süleyman Bozkurt
- Institute of Biochemistry II, Faculty of MedicineGoethe UniversityFrankfurt am MainGermany
| | - Pascale Henning‐Domres
- The Autophagy Lab, Institute of PathobiochemistryUniversity Medical Center of the Johannes Gutenberg UniversityMainzGermany
| | - Heike Huesmann
- The Autophagy Lab, Institute of PathobiochemistryUniversity Medical Center of the Johannes Gutenberg UniversityMainzGermany
| | - Stefan Eimer
- Department of Structural Cell BiologyInstitute for Cell Biology and Neuroscience, Goethe UniversityFrankfurt am MainGermany
| | - Laura Bindila
- Clinical Lipidomics Unit, Institute of Physiological ChemistryUniversity Medical Center of the Johannes Gutenberg UniversityMainzGermany
| | - Christian Behrends
- Munich Cluster for Systems Neurology (SyNergy)Ludwig‐Maximilians‐UniversityMunichGermany
| | - Emily Boyle
- Mechanisms of Cellular Quality ControlMax Planck Institute of BiophysicsFrankfurt am MainGermany
| | - Florian Wilfling
- Mechanisms of Cellular Quality ControlMax Planck Institute of BiophysicsFrankfurt am MainGermany
| | - Georg Tascher
- Institute of Biochemistry II, Faculty of MedicineGoethe UniversityFrankfurt am MainGermany
| | - Christian Münch
- Institute of Biochemistry II, Faculty of MedicineGoethe UniversityFrankfurt am MainGermany
| | - Christian Behl
- The Autophagy Lab, Institute of PathobiochemistryUniversity Medical Center of the Johannes Gutenberg UniversityMainzGermany
| | - Andreas Kern
- The Autophagy Lab, Institute of PathobiochemistryUniversity Medical Center of the Johannes Gutenberg UniversityMainzGermany
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Metabolic and immune-sensitive contacts between lipid droplets and endoplasmic reticulum reconstituted in vitro. Proc Natl Acad Sci U S A 2022; 119:e2200513119. [PMID: 35675423 PMCID: PMC9214533 DOI: 10.1073/pnas.2200513119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The intricate membranous network inside cells, with the endoplasmic reticulum (ER) at its center, allows coordinated cellular function by transmitting information across membrane contact sites (MCSs) that form between diverse kinds of cellular organelles and the ER. Unfortunately, these submicroscopic MCSs remain poorly understood and difficult to visualize and manipulate inside cells. We developed an in vitro assay to form MCSs between lipid droplets and an ER-mimicking microsomal membrane purified from rat liver. An optical trap is used to demonstrate physical tethering at the MCS, which changes dramatically in response to metabolic state and immune activation under control of Rab18 GTPase and phosphatidic acid. This assay can potentially be adapted to understand abnormal MCS formation in various disorders. Coordinated cell function requires a variety of subcellular organelles to exchange proteins and lipids across physical contacts that are also referred to as membrane contact sites. Such organelle-to-organelle contacts also evoke interest because they can appear in response to metabolic changes, immune activation, and possibly other stimuli. The microscopic size and complex, crowded geometry of these contacts, however, makes them difficult to visualize, manipulate, and understand inside cells. To address this shortcoming, we deposited endoplasmic reticulum (ER)-enriched microsomes purified from rat liver or from cultured cells on a coverslip in the form of a proteinaceous planar membrane. We visualized real-time lipid and protein exchange across contacts that form between this ER-mimicking membrane and lipid droplets (LDs) purified from the liver of rat. The high-throughput imaging possible in this geometry reveals that in vitro LD–ER contacts increase dramatically when the metabolic state is changed by feeding the animal and also when the immune system is activated. Contact formation in both cases requires Rab18 GTPase and phosphatidic acid, thus revealing common molecular targets operative in two very different biological pathways. An optical trap is used to demonstrate physical tethering of individual LDs to the ER-mimicking membrane and to estimate the strength of this tether. These methodologies can potentially be adapted to understand and target abnormal contact formation between different cellular organelles in the context of neurological and metabolic disorders or pathogen infection.
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Deneubourg C, Ramm M, Smith LJ, Baron O, Singh K, Byrne SC, Duchen MR, Gautel M, Eskelinen EL, Fanto M, Jungbluth H. The spectrum of neurodevelopmental, neuromuscular and neurodegenerative disorders due to defective autophagy. Autophagy 2022; 18:496-517. [PMID: 34130600 PMCID: PMC9037555 DOI: 10.1080/15548627.2021.1943177] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 06/10/2021] [Indexed: 12/15/2022] Open
Abstract
Primary dysfunction of autophagy due to Mendelian defects affecting core components of the autophagy machinery or closely related proteins have recently emerged as an important cause of genetic disease. This novel group of human disorders may present throughout life and comprises severe early-onset neurodevelopmental and more common adult-onset neurodegenerative disorders. Early-onset (or congenital) disorders of autophagy often share a recognizable "clinical signature," including variable combinations of neurological, neuromuscular and multisystem manifestations. Structural CNS abnormalities, cerebellar involvement, spasticity and peripheral nerve pathology are prominent neurological features, indicating a specific vulnerability of certain neuronal populations to autophagic disturbance. A typically biphasic disease course of late-onset neurodegeneration occurring on the background of a neurodevelopmental disorder further supports a role of autophagy in both neuronal development and maintenance. Additionally, an associated myopathy has been characterized in several conditions. The differential diagnosis comprises a wide range of other multisystem disorders, including mitochondrial, glycogen and lysosomal storage disorders, as well as ciliopathies, glycosylation and vesicular trafficking defects. The clinical overlap between the congenital disorders of autophagy and these conditions reflects the multiple roles of the proteins and/or emerging molecular connections between the pathways implicated and suggests an exciting area for future research. Therapy development for congenital disorders of autophagy is still in its infancy but may result in the identification of molecules that target autophagy more specifically than currently available compounds. The close connection with adult-onset neurodegenerative disorders highlights the relevance of research into rare early-onset neurodevelopmental conditions for much more common, age-related human diseases.Abbreviations: AC: anterior commissure; AD: Alzheimer disease; ALR: autophagic lysosomal reformation; ALS: amyotrophic lateral sclerosis; AMBRA1: autophagy and beclin 1 regulator 1; AMPK: AMP-activated protein kinase; ASD: autism spectrum disorder; ATG: autophagy related; BIN1: bridging integrator 1; BPAN: beta-propeller protein associated neurodegeneration; CC: corpus callosum; CHMP2B: charged multivesicular body protein 2B; CHS: Chediak-Higashi syndrome; CMA: chaperone-mediated autophagy; CMT: Charcot-Marie-Tooth disease; CNM: centronuclear myopathy; CNS: central nervous system; DNM2: dynamin 2; DPR: dipeptide repeat protein; DVL3: disheveled segment polarity protein 3; EPG5: ectopic P-granules autophagy protein 5 homolog; ER: endoplasmic reticulum; ESCRT: homotypic fusion and protein sorting complex; FIG4: FIG4 phosphoinositide 5-phosphatase; FTD: frontotemporal dementia; GBA: glucocerebrosidase; GD: Gaucher disease; GRN: progranulin; GSD: glycogen storage disorder; HC: hippocampal commissure; HD: Huntington disease; HOPS: homotypic fusion and protein sorting complex; HSPP: hereditary spastic paraparesis; LAMP2A: lysosomal associated membrane protein 2A; MEAX: X-linked myopathy with excessive autophagy; mHTT: mutant huntingtin; MSS: Marinesco-Sjoegren syndrome; MTM1: myotubularin 1; MTOR: mechanistic target of rapamycin kinase; NBIA: neurodegeneration with brain iron accumulation; NCL: neuronal ceroid lipofuscinosis; NPC1: Niemann-Pick disease type 1; PD: Parkinson disease; PtdIns3P: phosphatidylinositol-3-phosphate; RAB3GAP1: RAB3 GTPase activating protein catalytic subunit 1; RAB3GAP2: RAB3 GTPase activating non-catalytic protein subunit 2; RB1: RB1-inducible coiled-coil protein 1; RHEB: ras homolog, mTORC1 binding; SCAR20: SNX14-related ataxia; SENDA: static encephalopathy of childhood with neurodegeneration in adulthood; SNX14: sorting nexin 14; SPG11: SPG11 vesicle trafficking associated, spatacsin; SQSTM1: sequestosome 1; TBC1D20: TBC1 domain family member 20; TECPR2: tectonin beta-propeller repeat containing 2; TSC1: TSC complex subunit 1; TSC2: TSC complex subunit 2; UBQLN2: ubiquilin 2; VCP: valosin-containing protein; VMA21: vacuolar ATPase assembly factor VMA21; WDFY3/ALFY: WD repeat and FYVE domain containing protein 3; WDR45: WD repeat domain 45; WDR47: WD repeat domain 47; WMS: Warburg Micro syndrome; XLMTM: X-linked myotubular myopathy; ZFYVE26: zinc finger FYVE-type containing 26.
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Affiliation(s)
- Celine Deneubourg
- Department of Basic and Clinical Neuroscience, IoPPN, King’s College London, London, UK
| | - Mauricio Ramm
- Institute of Biomedicine, University of Turku, Turku, Finland
| | - Luke J. Smith
- Randall Division of Cell and Molecular Biophysics, Muscle Signalling Section, King’s College London, London, UK
| | - Olga Baron
- Wolfson Centre for Age-Related Diseases, King’s College London, London, UK
| | - Kritarth Singh
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Susan C. Byrne
- Department of Paediatric Neurology, Neuromuscular Service, Evelina’s Children Hospital, Guy’s & St. Thomas’ Hospital NHS Foundation Trust, London, UK
| | - Michael R. Duchen
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Mathias Gautel
- Randall Division of Cell and Molecular Biophysics, Muscle Signalling Section, King’s College London, London, UK
| | - Eeva-Liisa Eskelinen
- Institute of Biomedicine, University of Turku, Turku, Finland
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, Helsinki, Finland
| | - Manolis Fanto
- Department of Basic and Clinical Neuroscience, IoPPN, King’s College London, London, UK
| | - Heinz Jungbluth
- Department of Basic and Clinical Neuroscience, IoPPN, King’s College London, London, UK
- Randall Division of Cell and Molecular Biophysics, Muscle Signalling Section, King’s College London, London, UK
- Department of Paediatric Neurology, Neuromuscular Service, Evelina’s Children Hospital, Guy’s & St. Thomas’ Hospital NHS Foundation Trust, London, UK
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11
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Olarte MJ, Swanson JMJ, Walther TC, Farese RV. The CYTOLD and ERTOLD pathways for lipid droplet-protein targeting. Trends Biochem Sci 2022; 47:39-51. [PMID: 34583871 PMCID: PMC8688270 DOI: 10.1016/j.tibs.2021.08.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 01/03/2023]
Abstract
Lipid droplets (LDs) are the main organelles for lipid storage, and their surfaces contain unique proteins with diverse functions, including those that facilitate the deposition and mobilization of LD lipids. Among organelles, LDs have an unusual structure with an organic, hydrophobic oil phase covered by a phospholipid monolayer. The unique properties of LD monolayer surfaces require proteins to localize to LDs by distinct mechanisms. Here we review the two pathways known to mediate direct LD protein localization: the CYTOLD pathway mediates protein targeting from the cytosol toLDs, and the ERTOLD pathway functions in protein targeting from the endoplasmic reticulum toLDs. We describe the emerging principles for each targeting pathway in animal cells and highlight open questions in the field.
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Affiliation(s)
- Maria-Jesus Olarte
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | | | - Tobias C Walther
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA.
| | - Robert V Farese
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA.
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12
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Mailler E, Guardia CM, Bai X, Jarnik M, Williamson CD, Li Y, Maio N, Golden A, Bonifacino JS. The autophagy protein ATG9A enables lipid mobilization from lipid droplets. Nat Commun 2021; 12:6750. [PMID: 34799570 PMCID: PMC8605025 DOI: 10.1038/s41467-021-26999-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 10/26/2021] [Indexed: 01/18/2023] Open
Abstract
The multispanning membrane protein ATG9A is a scramblase that flips phospholipids between the two membrane leaflets, thus contributing to the expansion of the phagophore membrane in the early stages of autophagy. Herein, we show that depletion of ATG9A does not only inhibit autophagy but also increases the size and/or number of lipid droplets in human cell lines and C. elegans. Moreover, ATG9A depletion blocks transfer of fatty acids from lipid droplets to mitochondria and, consequently, utilization of fatty acids in mitochondrial respiration. ATG9A localizes to vesicular-tubular clusters (VTCs) that are tightly associated with an ER subdomain enriched in another multispanning membrane scramblase, TMEM41B, and also in close proximity to phagophores, lipid droplets and mitochondria. These findings indicate that ATG9A plays a critical role in lipid mobilization from lipid droplets to autophagosomes and mitochondria, highlighting the importance of ATG9A in both autophagic and non-autophagic processes.
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Affiliation(s)
- Elodie Mailler
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Carlos M Guardia
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Xiaofei Bai
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Michal Jarnik
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Chad D Williamson
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Yan Li
- Proteomics Core Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Nunziata Maio
- Metals Biology and Molecular Medicine Group, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - Andy Golden
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Juan S Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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13
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Hello from the other side: Membrane contact of lipid droplets with other organelles and subsequent functional implications. Prog Lipid Res 2021; 85:101141. [PMID: 34793861 DOI: 10.1016/j.plipres.2021.101141] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/10/2021] [Accepted: 11/10/2021] [Indexed: 02/06/2023]
Abstract
Lipid droplets (LDs) are ubiquitous organelles that play crucial roles in response to physiological and environmental cues. The identification of several neutral lipid synthesizing and regulatory protein complexes have propelled significant advance on the mechanisms of LD biogenesis in the endoplasmic reticulum (ER). Increasing evidence suggests that distinct proteins and regulatory factors, which localize to membrane contact sites (MCS), are involved not only in interorganellar lipid exchange and transport, but also function in other important cellular processes, including autophagy, mitochondrial dynamics and inheritance, ion signaling and inter-regulation of these MCS. More and more tethers and molecular determinants are associated to MCS and to a diversity of cellular and pathophysiological processes, demonstrating the dynamics and importance of these junctions in health and disease. The conjugation of lipids with proteins in supramolecular complexes is known to be paramount for many biological processes, namely membrane biosynthesis, cell homeostasis, regulation of organelle division and biogenesis, and cell growth. Ultimately, this physical organization allows the contact sites to function as crucial metabolic hubs that control the occurrence of chemical reactions. This leads to biochemical and metabolite compartmentalization for the purposes of energetic efficiency and cellular homeostasis. In this review, we will focus on the structural and functional aspects of LD-organelle interactions and how they ensure signaling exchange and metabolites transfer between organelles.
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14
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Heymans V, Kunath S, Hajieva P, Moosmann B. Cell Culture Characterization of Prooxidative Chain-Transfer Agents as Novel Cytostatic Drugs. Molecules 2021; 26:molecules26216743. [PMID: 34771157 PMCID: PMC8586999 DOI: 10.3390/molecules26216743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/01/2021] [Accepted: 11/04/2021] [Indexed: 11/16/2022] Open
Abstract
Prooxidative therapy is a well-established concept in infectiology and parasitology, in which prooxidative drugs like artemisinin and metronidazole play a pivotal clinical role. Theoretical considerations and earlier studies have indicated that prooxidative therapy might also represent a promising strategy in oncology. Here, we have investigated a novel class of prooxidative drugs, namely chain-transfer agents, as cytostatic agents in a series of human tumor cell lines in vitro. We have found that different chain-transfer agents of the lipophilic thiol class (like dodecane-1-thiol) elicited half-maximal effective concentrations in the low micromolar range in SY5Y cells (human neuroblastoma), Hela cells (human cervical carcinoma), HEK293 cells (immortalized human kidney), MCF7 cells (human breast carcinoma), and C2C12 cells (mouse myoblast). In contrast, HepG2 cells (human hepatocellular carcinoma) were resistant to toxicity, presumably through their high detoxification capacity for thiol groups. Cytotoxicity was undiminished by hypoxic culture conditions, but substantially lowered after cellular differentiation. Compared to four disparate, clinically used reference compounds in vitro (doxorubicin, actinomycin D, 5-fluorouracil, and hydroxyurea), chain-transfer agents emerged as comparably potent on a molar basis and on a maximum-effect basis. Our results indicate that chain-transfer agents possess a promising baseline profile as cytostatic drugs and should be explored further for anti-tumor chemotherapy.
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Affiliation(s)
- Victoria Heymans
- Evolutionary Biochemistry and Redox Medicine, Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany; (V.H.); (S.K.)
| | - Sascha Kunath
- Evolutionary Biochemistry and Redox Medicine, Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany; (V.H.); (S.K.)
| | - Parvana Hajieva
- Institute for Translational Medicine, MSH Medical School Hamburg, 20457 Hamburg, Germany;
| | - Bernd Moosmann
- Evolutionary Biochemistry and Redox Medicine, Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany; (V.H.); (S.K.)
- Correspondence: ; Tel.: +49-6131-39-26707
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15
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Barz S, Kriegenburg F, Sánchez-Martín P, Kraft C. Small but mighty: Atg8s and Rabs in membrane dynamics during autophagy. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119064. [PMID: 34048862 PMCID: PMC8261831 DOI: 10.1016/j.bbamcr.2021.119064] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 05/04/2021] [Accepted: 05/21/2021] [Indexed: 11/17/2022]
Abstract
Autophagy is a degradative pathway during which autophagosomes are formed that enwrap cytosolic material destined for turnover within the lytic compartment. Autophagosome biogenesis requires controlled lipid and membrane rearrangements to allow the formation of an autophagosomal seed and its subsequent elongation into a fully closed and fusion-competent double membrane vesicle. Different membrane remodeling events are required, which are orchestrated by the distinct autophagy machinery. An important player among these autophagy proteins is the small lipid-modifier Atg8. Atg8 proteins facilitate various aspects of autophagosome formation and serve as a binding platform for autophagy factors. Also Rab GTPases have been implicated in autophagosome biogenesis. As Atg8 proteins interact with several Rab GTPase regulators, they provide a possible link between autophagy progression and Rab GTPase activity. Here, we review central aspects in membrane dynamics during autophagosome biogenesis with a focus on Atg8 proteins and selected Rab GTPases.
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Affiliation(s)
- Saskia Barz
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, 79104 Freiburg, Germany
| | - Franziska Kriegenburg
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Pablo Sánchez-Martín
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Claudine Kraft
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
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16
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Interactions of Lipid Droplets with the Intracellular Transport Machinery. Int J Mol Sci 2021; 22:ijms22052776. [PMID: 33803444 PMCID: PMC7967230 DOI: 10.3390/ijms22052776] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 02/27/2021] [Accepted: 02/27/2021] [Indexed: 12/16/2022] Open
Abstract
Historically, studies of intracellular membrane trafficking have focused on the secretory and endocytic pathways and their major organelles. However, these pathways are also directly implicated in the biogenesis and function of other important intracellular organelles, the best studied of which are peroxisomes and lipid droplets. There is a large recent body of work on these organelles, which have resulted in the introduction of new paradigms regarding the roles of membrane trafficking organelles. In this review, we discuss the roles of membrane trafficking in the life cycle of lipid droplets. This includes the complementary roles of lipid phase separation and proteins in the biogenesis of lipid droplets from endoplasmic reticulum (ER) membranes, and the attachment of mature lipid droplets to membranes by lipidic bridges and by more conventional protein tethers. We also discuss the catabolism of neutral lipids, which in part results from the interaction of lipid droplets with cytosolic molecules, but with important roles for both macroautophagy and microautophagy. Finally, we address their eventual demise, which involves interactions with the autophagocytotic machinery. We pay particular attention to the roles of small GTPases, particularly Rab18, in these processes.
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17
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Schepers J, Behl C. Lipid droplets and autophagy-links and regulations from yeast to humans. J Cell Biochem 2021; 122:602-611. [PMID: 33522032 DOI: 10.1002/jcb.29889] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 12/04/2020] [Accepted: 12/28/2020] [Indexed: 12/22/2022]
Abstract
Recent advances in the yeast Saccharomyces cerevisiae and higher eukaryotes have been increasingly connecting lipid droplet (LD) dynamics to the regulation of autophagy. In this review we will discuss implications that connect LD de novo synthesis and LD mobilization to autophagy and how autophagy is regulated by these mechanisms. Elucidating these connections might pose a chance to further understand autophagy induction and membrane biogenesis for the growing autophagosome under different conditions. Increasing our understanding of these mechanisms might provide a chance to understand several conditions that might be related to LD dysregulation and, possibly, as a consequence of this, dysregulation of autophagy.
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Affiliation(s)
- Jana Schepers
- The Autophagy Lab, Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Christian Behl
- The Autophagy Lab, Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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18
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Deng S, Liu J, Wu X, Lu W. Golgi Apparatus: A Potential Therapeutic Target for Autophagy-Associated Neurological Diseases. Front Cell Dev Biol 2020; 8:564975. [PMID: 33015059 PMCID: PMC7509445 DOI: 10.3389/fcell.2020.564975] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 08/17/2020] [Indexed: 12/13/2022] Open
Abstract
Autophagy has dual effects in human diseases: appropriate autophagy may protect cells from stress, while excessive autophagy may cause cell death. Additionally, close interactions exist between autophagy and the Golgi. This review outlines recent advances regarding the role of the Golgi apparatus in autophagy. The signaling processes of autophagy are dependent on the normal function of the Golgi. Specifically, (i) autophagy-related protein 9 is mainly located in the Golgi and forms new autophagosomes in response to stressors; (ii) Golgi fragmentation is induced by Golgi-related proteins and accompanied with autophagy induction; and (iii) the endoplasmic reticulum-Golgi intermediate compartment and the reticular trans-Golgi network play essential roles in autophagosome formation to provide a template for lipidation of microtubule-associated protein 1A/1B-light chain 3 and induce further ubiquitination. Golgi-related proteins regulate formation of autophagosomes, and disrupted formation of autophagy can influence Golgi function. Notably, aberrant autophagy has been demonstrated to be implicated in neurological diseases. Thus, targeted therapies aimed at protecting the Golgi or regulating Golgi proteins might prevent or ameliorate autophagy-related neurological diseases. Further studies are needed to investigate the potential application of Golgi therapy in autophagy-based neurological diseases.
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Affiliation(s)
- Shuwen Deng
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jia Liu
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Xiaomei Wu
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Wei Lu
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
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19
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Xie Y, Li J, Kang R, Tang D. Interplay Between Lipid Metabolism and Autophagy. Front Cell Dev Biol 2020; 8:431. [PMID: 32582708 PMCID: PMC7283384 DOI: 10.3389/fcell.2020.00431] [Citation(s) in RCA: 105] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/08/2020] [Indexed: 12/11/2022] Open
Abstract
Autophagy is a self-eating process of using lysosomes to degrade macromolecular substances (e.g., proteins and organelles) that are damaged, degenerated, or aging. Lipid metabolism is the synthesis and degradation of lipids (e.g., triglycerides, steroids, and phospholipids) to generate energy or produce the structural components of cell membranes. There is a complex interplay between lipid metabolism (e.g., digestion, absorption, catabolism, biosynthesis, and peroxidation) and autophagy machinery, leading to the modulation of cell homeostasis, including cell survival and death. In particular, lipid metabolism is involved in the formation of autophagic membrane structures (e.g., phagophores and autophagosomes) during stress. Moreover, autophagy, especially selective autophagy (e.g., lipophagy, ferritinophagy, clockophagy, and mitophagy), promotes lipid catabolism or lipid peroxidation-induced ferroptosis through the degradation of various substances within the cell. A better understanding of the mechanisms of autophagy and possible links to lipid metabolism will undoubtedly promote potential treatments for a variety of diseases.
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Affiliation(s)
- Yangchun Xie
- Department of Oncology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jingbo Li
- Department of Surgery, UT Southwestern Medical Center, Dallas, TX, United States
| | - Rui Kang
- Department of Surgery, UT Southwestern Medical Center, Dallas, TX, United States
| | - Daolin Tang
- Department of Surgery, UT Southwestern Medical Center, Dallas, TX, United States
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20
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Besemer AS, Maus J, Ax MDA, Stein A, Vo S, Freese C, Nalbach K, von Hilchen C, Pfalzgraf IF, Koziollek-Drechsler I, Silva B, Huesmann H, Boukhallouk F, Florin L, Kern A, Behl C, Clement AM. Receptor-mediated endocytosis 8 (RME-8)/DNAJC13 is a novel positive modulator of autophagy and stabilizes cellular protein homeostasis. Cell Mol Life Sci 2020; 78:645-660. [PMID: 32322926 PMCID: PMC7873018 DOI: 10.1007/s00018-020-03521-y] [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: 10/07/2019] [Revised: 03/20/2020] [Accepted: 04/06/2020] [Indexed: 12/15/2022]
Abstract
The cellular protein homeostasis (proteostasis) network responds effectively to insults. In a functional screen in C. elegans, we recently identified the gene receptor-mediated endocytosis 8 (rme-8; human ortholog: DNAJC13) as a component of the proteostasis network. Accumulation of aggregation-prone proteins, such as amyloid-β 42 (Aβ), α-synuclein, or mutant Cu/Zn-superoxide dismutase (SOD1), were aggravated upon the knockdown of rme-8/DNAJC13 in C. elegans and in human cell lines, respectively. DNAJC13 is involved in endosomal protein trafficking and associated with the retromer and the WASH complex. As both complexes have been linked to autophagy, we investigated the role of DNAJC13 in this degradative pathway. In knockdown and overexpression experiments, DNAJC13 acts as a positive modulator of autophagy. In contrast, the overexpression of the Parkinson’s disease-associated mutant DNAJC13(N855S) did not enhance autophagy. Reduced DNAJC13 levels affected ATG9A localization at and its transport from the recycling endosome. As a consequence, ATG9A co-localization at LC3B-positive puncta under steady-state and autophagy-induced conditions is impaired. These data demonstrate a novel function of RME-8/DNAJC13 in cellular homeostasis by modulating ATG9A trafficking and autophagy.
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Affiliation(s)
- Anna S Besemer
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Joanna Maus
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Mirjam D A Ax
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Anna Stein
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Stella Vo
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Christian Freese
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Karsten Nalbach
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Christian von Hilchen
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Ines F Pfalzgraf
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Ingrid Koziollek-Drechsler
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Beate Silva
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Heike Huesmann
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Fatima Boukhallouk
- Institute of Medical Microbiology and Hygiene, University Medical Center of the Johannes Gutenberg-University, 55101 Mainz, Germany
| | - Luise Florin
- Institute for Virology and Research Center for Immunotherapy (FZI), University Medical Center of the Johannes Gutenberg-University, 55101 Mainz, Germany
| | - Andreas Kern
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany
| | - Christian Behl
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany.
| | - Albrecht M Clement
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany.
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21
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Abstract
The de novo synthesis of autophagic vesicles is strongly dependent on sufficient lipid supply. Recently, the RAB GTPase RAB18 was shown to affect autophagy by mediating fatty acid release from lipid droplets, which are lipid sources for autophagosome formation. The stable loss of RAB18 interfered with fatty acid release from the lipid reservoirs and provoked autophagy network adaptations aiming to maintain autophagic activity under lipid limiting conditions.
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Affiliation(s)
- Andreas Kern
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg University Mainz , Mainz, Germany
| | - Christian Behl
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg University Mainz , Mainz, Germany
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22
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Abstract
Lipid droplets have a unique structure among organelles consisting of a dense hydrophobic core of neutral lipids surrounded by a single layer of phospholipids decorated with various proteins. Often labeled merely as passive fat storage repositories, they in fact have a remarkably dynamic life cycle. Being formed within the endoplasmic reticulum membrane, lipid droplets rapidly grow, shrink, traverse the cytosol, and engage in contacts with other organelles to exchange proteins and lipids. Their lipid and protein composition changes dynamically in response to cellular states and nutrient availability. Remarkably, their biogenesis is induced when cells experience various forms of nutrient, energy, and redox imbalances, including lipid excess and complete nutrient deprivation. Cancer cells are continuously exposed to nutrient and oxygen fluctuations and have the capacity to switch between alternative nutrient acquisition and metabolic pathways in order to strive even during severe stress. Their supply of lipids is ensured by a series of nutrient uptake and scavenging mechanisms, upregulation of de novo lipid synthesis, repurposing of their structural lipids via enzymatic remodeling, or lipid recycling through autophagy. Importantly, most of these pathways of lipid acquisition converge at lipid droplets, which combine different lipid fluxes and control their usage based on specific cellular needs. It is thus not surprising that lipid droplet breakdown is an elaborately regulated process that occurs via a complex interplay of neutral lipases and autophagic degradation. Cancer cells employ lipid droplets to ensure energy production and redox balance, modulate autophagy, drive membrane synthesis, and control its composition, thereby minimizing stress and fostering tumor progression. As regulators of (poly)unsaturated fatty acid trafficking, lipid droplets are also emerging as modulators of lipid peroxidation and sensitivity to ferroptosis. Clearly, dysregulated lipid droplet turnover may also be detrimental to cancer cells, which should provide potential therapeutic opportunities in the future. In this review, we explore how lipid droplets consolidate lipid acquisition and trafficking pathways in order to match lipid supply with the requirements for cancer cell survival, growth, and metastasis.
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