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Shang JN, Yu CG, Li R, Xi Y, Jian YJ, Xu N, Chen S. The nonautophagic functions of autophagy-related proteins. Autophagy 2024; 20:720-734. [PMID: 37682088 PMCID: PMC11062363 DOI: 10.1080/15548627.2023.2254664] [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: 03/09/2023] [Accepted: 08/30/2023] [Indexed: 09/09/2023] Open
Abstract
ABBREVIATIONS ATG: autophagy related; BECN1: beclin 1; cAMP: cyclic adenosine monophosphate; dsDNA: double-stranded DNA; EMT: epithelial-mesenchymal transition; IFN: interferon; ISCs: intestinal stem cells; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MAPK/JNK: mitogen-activated protein kinase/c-Jun N-terminal kinases; MTOR: mechanistic target of rapamycin kinase; STING1: stimulator of interferon response cGAMP interactor 1; UVRAG: UV radiation resistance associated; VPS: vacuolar protein sorting.
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Affiliation(s)
- Jia-Ni Shang
- Laboratory of Molecular and Cellular Biology, Institute of Metabolism and Health, School of Basic Medical Sciences, Henan University School of Medicine, Kaifeng, Henan, PR China
| | - Chen-Ge Yu
- Laboratory of Molecular and Cellular Biology, Institute of Metabolism and Health, School of Basic Medical Sciences, Henan University School of Medicine, Kaifeng, Henan, PR China
| | - Rui Li
- Laboratory of Molecular and Cellular Biology, Institute of Metabolism and Health, School of Basic Medical Sciences, Henan University School of Medicine, Kaifeng, Henan, PR China
| | - Yan Xi
- Laboratory of Molecular and Cellular Biology, Institute of Metabolism and Health, School of Basic Medical Sciences, Henan University School of Medicine, Kaifeng, Henan, PR China
| | - Yue Jenny Jian
- Nanjing Foreign Language School, Nanjing, Jiangsu, PR China
| | - Nan Xu
- Laboratory of Molecular and Cellular Biology, Institute of Metabolism and Health, School of Basic Medical Sciences, Henan University School of Medicine, Kaifeng, Henan, PR China
| | - Su Chen
- Laboratory of Molecular and Cellular Biology, Institute of Metabolism and Health, School of Basic Medical Sciences, Henan University School of Medicine, Kaifeng, Henan, PR China
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2
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Xiong Q, Feng R, Fischer S, Karow M, Stumpf M, Meßling S, Nitz L, Müller S, Clemen CS, Song N, Li P, Wu C, Eichinger L. Proteasomes of Autophagy-Deficient Cells Exhibit Alterations in Regulatory Proteins and a Marked Reduction in Activity. Cells 2023; 12:1514. [PMID: 37296637 PMCID: PMC10252828 DOI: 10.3390/cells12111514] [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: 04/03/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023] Open
Abstract
Autophagy and the ubiquitin proteasome system are the two major processes for the clearance and recycling of proteins and organelles in eukaryotic cells. Evidence is accumulating that there is extensive crosstalk between the two pathways, but the underlying mechanisms are still unclear. We previously found that autophagy 9 (ATG9) and 16 (ATG16) proteins are crucial for full proteasomal activity in the unicellular amoeba Dictyostelium discoideum. In comparison to AX2 wild-type cells, ATG9-and ATG16- cells displayed a 60%, and ATG9-/16- cells a 90%, decrease in proteasomal activity. Mutant cells also showed a significant increase in poly-ubiquitinated proteins and contained large ubiquitin-positive protein aggregates. Here, we focus on possible reasons for these results. Reanalysis of published tandem mass tag-based quantitative proteomic results of AX2, ATG9-, ATG16-, and ATG9-/16- cells revealed no change in the abundance of proteasomal subunits. To identify possible differences in proteasome-associated proteins, we generated AX2 wild-type and ATG16- cells expressing the 20S proteasomal subunit PSMA4 as GFP-tagged fusion protein, and performed co-immunoprecipitation experiments followed by mass spectrometric analysis. The results revealed no significant differences in the abundance of proteasomes between the two strains. However, we found enrichment as well as depletion of proteasomal regulators and differences in the ubiquitination of associated proteins for ATG16-, as compared to AX2 cells. Recently, proteaphagy has been described as a means to replace non-functional proteasomes. We propose that autophagy-deficient D. discoideum mutants suffer from inefficient proteaphagy, which results in the accumulation of modified, less-active, and also of inactive, proteasomes. As a consequence, these cells exhibit a dramatic decrease in proteasomal activity and deranged protein homeostasis.
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Affiliation(s)
- Qiuhong Xiong
- Shanxi Provincial Key Laboratory of Medical Molecular Cell Biology, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institutes of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China
| | - Rong Feng
- Shanxi Provincial Key Laboratory of Medical Molecular Cell Biology, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institutes of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China
| | - Sarah Fischer
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Malte Karow
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Maria Stumpf
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Susanne Meßling
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Leonie Nitz
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Stefan Müller
- CECAD Proteomics Facility, Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Christoph S. Clemen
- Institute of Aerospace Medicine, German Aerospace Center (DLR), 51147 Cologne, Germany
- Institute of Vegetative Physiology, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Ning Song
- Shanxi Provincial Key Laboratory of Medical Molecular Cell Biology, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institutes of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China
| | - Ping Li
- Shanxi Provincial Key Laboratory of Medical Molecular Cell Biology, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institutes of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China
| | - Changxin Wu
- Shanxi Provincial Key Laboratory of Medical Molecular Cell Biology, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institutes of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China
| | - Ludwig Eichinger
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
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3
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Kim WD, Wilson-Smillie MLDM, Thanabalasingam A, Lefrancois S, Cotman SL, Huber RJ. Autophagy in the Neuronal Ceroid Lipofuscinoses (Batten Disease). Front Cell Dev Biol 2022; 10:812728. [PMID: 35252181 PMCID: PMC8888908 DOI: 10.3389/fcell.2022.812728] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 01/24/2022] [Indexed: 12/22/2022] Open
Abstract
The neuronal ceroid lipofuscinoses (NCLs), also referred to as Batten disease, are a family of neurodegenerative diseases that affect all age groups and ethnicities around the globe. At least a dozen NCL subtypes have been identified that are each linked to a mutation in a distinct ceroid lipofuscinosis neuronal (CLN) gene. Mutations in CLN genes cause the accumulation of autofluorescent lipoprotein aggregates, called ceroid lipofuscin, in neurons and other cell types outside the central nervous system. The mechanisms regulating the accumulation of this material are not entirely known. The CLN genes encode cytosolic, lysosomal, and integral membrane proteins that are associated with a variety of cellular processes, and accumulated evidence suggests they participate in shared or convergent biological pathways. Research across a variety of non-mammalian and mammalian model systems clearly supports an effect of CLN gene mutations on autophagy, suggesting that autophagy plays an essential role in the development and progression of the NCLs. In this review, we summarize research linking the autophagy pathway to the NCLs to guide future work that further elucidates the contribution of altered autophagy to NCL pathology.
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Affiliation(s)
- William D. Kim
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | | | - Aruban Thanabalasingam
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | - Stephane Lefrancois
- Centre Armand-Frappier Santé Biotechnologie, Institut National de La Recherche Scientifique, Laval, QC, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
- Centre D'Excellence en Recherche sur Les Maladies Orphelines–Fondation Courtois (CERMO-FC), Université Du Québec à Montréal (UQAM), Montréal, QC, Canada
| | - Susan L. Cotman
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Harvard Medical School, Boston, MA, United States
| | - Robert J. Huber
- Department of Biology, Trent University, Peterborough, ON, Canada
- *Correspondence: Robert J. Huber,
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4
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Vincent O, Antón-Esteban L, Bueno-Arribas M, Tornero-Écija A, Navas MÁ, Escalante R. The WIPI Gene Family and Neurodegenerative Diseases: Insights From Yeast and Dictyostelium Models. Front Cell Dev Biol 2021; 9:737071. [PMID: 34540850 PMCID: PMC8442847 DOI: 10.3389/fcell.2021.737071] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 08/12/2021] [Indexed: 02/01/2023] Open
Abstract
WIPIs are a conserved family of proteins with a characteristic 7-bladed β-propeller structure. They play a prominent role in autophagy, but also in other membrane trafficking processes. Mutations in human WIPI4 cause several neurodegenerative diseases. One of them is BPAN, a rare disease characterized by developmental delay, motor disorders, and seizures. Autophagy dysfunction is thought to play an important role in this disease but the precise pathological consequences of the mutations are not well established. The use of simple models such as the yeast Saccharomyces cerevisiae and the social amoeba Dictyostelium discoideum provides valuable information on the molecular and cellular function of these proteins, but also sheds light on possible pathways that may be relevant in the search for potential therapies. Here, we review the function of WIPIs as well as disease-causing mutations with a special focus on the information provided by these simple models.
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Affiliation(s)
- Olivier Vincent
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC/UAM, Madrid, Spain
| | - Laura Antón-Esteban
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC/UAM, Madrid, Spain
| | | | - Alba Tornero-Écija
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC/UAM, Madrid, Spain
| | - María-Ángeles Navas
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Ricardo Escalante
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC/UAM, Madrid, Spain
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5
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Tornero-Écija A, Tábara LC, Bueno-Arribas M, Antón-Esteban L, Navarro-Gómez C, Sánchez I, Vincent O, Escalante R. A Dictyostelium model for BPAN disease reveals a functional relationship between the WDR45/WIPI4 homolog Wdr45l and Vmp1 in the regulation of autophagy-associated PtdIns3P and ER stress. Autophagy 2021; 18:661-677. [PMID: 34328055 PMCID: PMC9037511 DOI: 10.1080/15548627.2021.1953262] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PROPPINs are conserved PtdIns3P-binding proteins required for autophagosome biogenesis that fold into a characteristic group of seven-bladed beta-propellers. Mutations in WDR45/WIPI4, a human member of this family, lead to BPAN, a rare form of neurodegeneration. We have generated mutants for the two PROPPIN proteins present in the model system Dictyostelium discoideum (Atg18 and Wdr45l) and characterized their function. Lack of Wdr45l greatly impairs autophagy, while Atg18 only causes subtle defects in the maturation of autolysosomes. The strong phenotype of the Wdr45l mutant is strikingly similar to that observed in Dictyostelium cells lacking Vmp1, an ER protein required for omegasome formation. Common phenotypes include impaired growth in axenic medium, lack of aggregation, and local enrichment of PtdIns3P as determined by the use of lipid reporters. In addition, Vmp1 and Wdr45l mutants show a chronically active response to ER stress. For both mutants, this altered PtdIns3P localization can be prevented by the additional mutation of the upstream regulator Atg1, which also leads to recovery of axenic growth and reduction of ER stress. We propose that, in addition to an autophagy defect, local autophagy-associated PtdIns3P accumulation might contribute to the pathogenesis of BPAN by disrupting ER homeostasis. The introduction of BPAN-associated mutations in Dictyostelium Wdr45l reveals the impact of pathogenic residues on the function and localization of the protein.
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Affiliation(s)
- Alba Tornero-Écija
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | - Luis-Carlos Tábara
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | - Miranda Bueno-Arribas
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | - Laura Antón-Esteban
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | | | - Irene Sánchez
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | - Olivier Vincent
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | - Ricardo Escalante
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
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6
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McLaren MD, Mathavarajah S, Kim WD, Yap SQ, Huber RJ. Aberrant Autophagy Impacts Growth and Multicellular Development in a Dictyostelium Knockout Model of CLN5 Disease. Front Cell Dev Biol 2021; 9:657406. [PMID: 34291044 PMCID: PMC8287835 DOI: 10.3389/fcell.2021.657406] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 05/28/2021] [Indexed: 12/22/2022] Open
Abstract
Mutations in CLN5 cause a subtype of neuronal ceroid lipofuscinosis (NCL) called CLN5 disease. While the precise role of CLN5 in NCL pathogenesis is not known, recent work revealed that the protein has glycoside hydrolase activity. Previous work on the Dictyostelium discoideum homolog of human CLN5, Cln5, revealed its secretion during the early stages of development and its role in regulating cell adhesion and cAMP-mediated chemotaxis. Here, we used Dictyostelium to examine the effect of cln5-deficiency on various growth and developmental processes during the life cycle. During growth, cln5– cells displayed reduced cell proliferation, cytokinesis, viability, and folic acid-mediated chemotaxis. In addition, the growth of cln5– cells was severely impaired in nutrient-limiting media. Based on these findings, we assessed autophagic flux in growth-phase cells and observed that loss of cln5 increased the number of autophagosomes suggesting that the basal level of autophagy was increased in cln5– cells. Similarly, loss of cln5 increased the amounts of ubiquitin-positive proteins. During the early stages of multicellular development, the aggregation of cln5– cells was delayed and loss of the autophagy genes, atg1 and atg9, reduced the extracellular amount of Cln5. We also observed an increased amount of intracellular Cln5 in cells lacking the Dictyostelium homolog of the human glycoside hydrolase, hexosaminidase A (HEXA), further supporting the glycoside hydrolase activity of Cln5. This observation was also supported by our finding that CLN5 and HEXA expression are highly correlated in human tissues. Following mound formation, cln5– development was precocious and loss of cln5 affected spore morphology, germination, and viability. When cln5– cells were developed in the presence of the autophagy inhibitor ammonium chloride, the formation of multicellular structures was impaired, and the size of cln5– slugs was reduced relative to WT slugs. These results, coupled with the aberrant autophagic flux observed in cln5– cells during growth, support a role for Cln5 in autophagy during the Dictyostelium life cycle. In total, this study highlights the multifaceted role of Cln5 in Dictyostelium and provides insight into the pathological mechanisms that may underlie CLN5 disease.
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Affiliation(s)
- Meagan D McLaren
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | | | - William D Kim
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | - Shyong Q Yap
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | - Robert J Huber
- Department of Biology, Trent University, Peterborough, ON, Canada
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7
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RNA seq and quantitative proteomic analysis of Dictyostelium knock-out cells lacking the core autophagy proteins ATG9 and/or ATG16. BMC Genomics 2021; 22:444. [PMID: 34126926 PMCID: PMC8204557 DOI: 10.1186/s12864-021-07756-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 05/26/2021] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Autophagy is an evolutionary ancient mechanism that sequesters substrates for degradation within autolysosomes. The process is driven by many autophagy-related (ATG) proteins, including the core members ATG9 and ATG16. However, the functions of these two core ATG proteins still need further elucidation. Here, we applied RNAseq and tandem mass tag (TMT) proteomic approaches to identify differentially expressed genes (DEGs) and proteins (DEPs) in Dictyostelium discoideum ATG9‾, ATG16‾ and ATG9‾/16‾ strains in comparison to AX2 wild-type cells. RESULT In total, we identified 332 (279 up and 53 down), 639 (487 up and 152 down) and 260 (114 up and 146 down) DEGs and 124 (83 up and 41 down), 431 (238 up and 193 down) and 677 (347 up and 330 down) DEPs in ATG9‾, ATG16‾ and ATG9‾/16‾ strains, respectively. Thus, in the single knock-out strains, the number of DEGs was higher than the number of DEPs while in the double knock-out strain the number of DEPs was higher. Comparison of RNAseq and proteomic data further revealed, that only a small proportion of the transcriptional changes were reflected on the protein level. Gene ontology (GO) analysis revealed an enrichment of DEPs involved in lipid metabolism and oxidative phosphorylation. Furthermore, we found increased expression of the anti-oxidant enzymes glutathione reductase (gsr) and catalase A (catA) in ATG16‾ and ATG9‾/16‾ cells, respectively, indicating adaptation to excess reactive oxygen species (ROS). CONCLUSIONS Our study provides the first combined transcriptome and proteome analysis of ATG9‾, ATG16‾ and ATG9‾/16‾ cells. Our results suggest, that most changes in protein abundance were not caused by transcriptional changes, but were rather due to changes in protein homeostasis. In particular, knock-out of atg9 and/or atg16 appears to cause dysregulation of lipid metabolism and oxidative phosphorylation.
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Xiong Q, Li X, Li W, Chen G, Xiao H, Li P, Wu C. WDR45 Mutation Impairs the Autophagic Degradation of Transferrin Receptor and Promotes Ferroptosis. Front Mol Biosci 2021; 8:645831. [PMID: 34012978 PMCID: PMC8126626 DOI: 10.3389/fmolb.2021.645831] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 04/06/2021] [Indexed: 12/11/2022] Open
Abstract
WDR45 is an autophagy-related protein that involves in the formation of autophagosome. Mutations in WDR45 lead to the impairment of autophagy which is associated with the human β-propeller protein-associated neurodegeneration (BPAN). However, the relationship between autophagy and brain iron accumulation in patients with BPAN remains unclear. Here, we demonstrated that transferrin receptor (TfRC) which is critical for the iron import of cells was degraded via autophagy. TfRC was accumulated after the inhibition of autophagy by treatment with autophagic inhibitor chloroquine or knockdown of ATG2A. The intracellular iron content was increased in cells overexpressing TfRC or mutant WDR45, however, ferritin H (FTH) chain was decreased. Increased TfRC and simultaneously decreased FTH consequently resulted in an elevated level of ferrous iron (Fe2+) which further promoted cell ferroptosis, demonstrated by the increased lipid peroxidation and reactive oxygen species (ROS) and the decreased glutathione peroxidase 4 (GPX4) and cell viability. Taken together, these findings provide a piece of important evidence that WDR45 deficiency impairs autophagic degradation of TfRC, therefore leading to iron accumulation, and the elevated iron promotes ferroptosis which may contribute to the progression of BPAN.
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Affiliation(s)
- Qiuhong Xiong
- Institutes of Biomedical Sciences, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan, China
| | - Xin Li
- Institutes of Biomedical Sciences, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan, China
| | - Wenjing Li
- Institutes of Biomedical Sciences, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan, China
| | - Guangxin Chen
- Institutes of Biomedical Sciences, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan, China
| | - Han Xiao
- Institutes of Biomedical Sciences, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan, China
| | - Ping Li
- Institutes of Biomedical Sciences, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan, China
| | - Changxin Wu
- Institutes of Biomedical Sciences, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan, China
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Valenzuela C, Gil M, Urrutia ÍM, Sabag A, Enninga J, Santiviago CA. SopB- and SifA-dependent shaping of the Salmonella-containing vacuole proteome in the social amoeba Dictyostelium discoideum. Cell Microbiol 2020; 23:e13263. [PMID: 32945061 DOI: 10.1111/cmi.13263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 09/07/2020] [Accepted: 09/09/2020] [Indexed: 02/06/2023]
Abstract
The ability of Salmonella to survive and replicate within mammalian host cells involves the generation of a membranous compartment known as the Salmonella-containing vacuole (SCV). Salmonella employs a number of effector proteins that are injected into host cells for SCV formation using its type-3 secretion systems encoded in SPI-1 and SPI-2 (T3SS-1 and T3SS-2, respectively). Recently, we reported that S. Typhimurium requires T3SS-1 and T3SS-2 to survive in the model amoeba Dictyostelium discoideum. Despite these findings, the involved effector proteins have not been identified yet. Therefore, we evaluated the role of two major S. Typhimurium effectors SopB and SifA during D. discoideum intracellular niche formation. First, we established that S. Typhimurium resides in a vacuolar compartment within D. discoideum. Next, we isolated SCVs from amoebae infected with wild type or the ΔsopB and ΔsifA mutant strains of S. Typhimurium, and we characterised the composition of this compartment by quantitative proteomics. This comparative analysis suggests that S. Typhimurium requires SopB and SifA to modify the SCV proteome in order to generate a suitable intracellular niche in D. discoideum. Accordingly, we observed that SopB and SifA are needed for intracellular survival of S. Typhimurium in this organism. Thus, our results provide insight into the mechanisms employed by Salmonella to survive intracellularly in phagocytic amoebae.
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Affiliation(s)
- Camila Valenzuela
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.,Dynamics of Host-Pathogen Interactions Unit, Institut Pasteur, Paris, France.,CNRS UMR3691, Paris, France
| | - Magdalena Gil
- Dynamics of Host-Pathogen Interactions Unit, Institut Pasteur, Paris, France.,CNRS UMR3691, Paris, France
| | - Ítalo M Urrutia
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Andrea Sabag
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Jost Enninga
- Dynamics of Host-Pathogen Interactions Unit, Institut Pasteur, Paris, France.,CNRS UMR3691, Paris, France
| | - Carlos A Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
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10
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Shin WH, Park JH, Chung KC. The central regulator p62 between ubiquitin proteasome system and autophagy and its role in the mitophagy and Parkinson's disease. BMB Rep 2020. [PMID: 31818366 PMCID: PMC6999829 DOI: 10.5483/bmbrep.2020.53.1.283] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The ubiquitin-proteasome system (UPS) and autophagy are two major degradative pathways of proteins in eukaryotic cells. As about 30% of newly synthesized proteins are known to be misfolded under normal cell conditions, the precise and timely operation of the UPS and autophagy to remove them as well as their tightly controlled regulation, is so important for proper cell function and survival. In the UPS, target proteins are labeled by small proteins called ubiquitin, which are then transported to the proteasome complex for degradation. Alternatively, many greatly damaged proteins are believed to be delivered to the lysosome for autophagic degradation. Although these autophagy and UPS pathways have not been considered to be directly related, many recent studies proposed their close link and dynamic interconversion. In this review, we’ll focus on the several regulatory molecules that function in both UPS and autophagy and their crosstalk. Among the proposed multiple modulators, we will take a closer look at the so-called main connector of UPS-autophagy regulation, p62. Last, the functional role of p62 in the mitophagy and its implication for the pathogenesis of Parkinson’s disease, one of the major neurodegenerative diseases, will be briefly reviewed.
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Affiliation(s)
- Woo Hyun Shin
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Joon Hyung Park
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Kwang Chul Chung
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
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11
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Karow M, Fischer S, Meßling S, Konertz R, Riehl J, Xiong Q, Rijal R, Wagle P, S. Clemen C, Eichinger L. Functional Characterisation of the Autophagy ATG12~5/16 Complex in Dictyostelium discoideum. Cells 2020; 9:cells9051179. [PMID: 32397394 PMCID: PMC7290328 DOI: 10.3390/cells9051179] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 05/04/2020] [Accepted: 05/06/2020] [Indexed: 12/21/2022] Open
Abstract
Macroautophagy, a highly conserved and complex intracellular degradative pathway, involves more than 20 core autophagy (ATG) proteins, among them the hexameric ATG12~5/16 complex, which is part of the essential ubiquitin-like conjugation systems in autophagy. Dictyostelium discoideumatg5 single, atg5/12 double, and atg5/12/16 triple gene knock-out mutant strains displayed similar defects in the conjugation of ATG8 to phosphatidylethanolamine, development, and cell viability upon nitrogen starvation. This implies that ATG5, 12 and 16 act as a functional unit in canonical autophagy. Macropinocytosis of TRITC dextran and phagocytosis of yeast were significantly decreased in ATG5¯ and ATG5¯/12¯ and even further in ATG5¯/12¯/16¯ cells. In contrast, plaque growth on Klebsiella aerogenes was about twice as fast for ATG5¯ and ATG5¯/12¯/16¯ cells in comparison to AX2, but strongly decreased for ATG5¯/12¯ cells. Along this line, phagocytic uptake of Escherichia coli was significantly reduced in ATG5¯/12¯ cells, while no difference in uptake, but a strong increase in membrane association of E. coli, was seen for ATG5¯ and ATG5¯/12¯/16¯ cells. Proteasomal activity was also disturbed in a complex fashion, consistent with an inhibitory activity of ATG16 in the absence of ATG5 and/or ATG12. Our results confirm the essential function of the ATG12~5/16 complex in canonical autophagy, and furthermore are consistent with autophagy-independent functions of the complex and its individual components. They also strongly support the placement of autophagy upstream of the ubiquitin-proteasome system (UPS), as a fully functional UPS depends on autophagy.
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Affiliation(s)
- Malte Karow
- Centre for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany; (M.K.); (S.F.); (S.M.); (R.K.); (J.R.)
| | - Sarah Fischer
- Centre for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany; (M.K.); (S.F.); (S.M.); (R.K.); (J.R.)
| | - Susanne Meßling
- Centre for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany; (M.K.); (S.F.); (S.M.); (R.K.); (J.R.)
| | - Roman Konertz
- Centre for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany; (M.K.); (S.F.); (S.M.); (R.K.); (J.R.)
| | - Jana Riehl
- Centre for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany; (M.K.); (S.F.); (S.M.); (R.K.); (J.R.)
| | - Qiuhong Xiong
- Institute of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China;
| | - Ramesh Rijal
- Department of Biology, Texas A&M University, College Station, TX 77843-3474, USA;
| | - Prerana Wagle
- Bioinformatics Core Facility, CECAD Research Center, University of Cologne, 50931 Cologne, Germany;
| | - Christoph S. Clemen
- Institute of Aerospace Medicine, German Aerospace Center (DLR), 51147 Cologne, Germany;
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, 50931 Cologne, Germany
- Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Ludwig Eichinger
- Centre for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany; (M.K.); (S.F.); (S.M.); (R.K.); (J.R.)
- Correspondence: ; Tel.: +49-221-478-6928; Fax: +49-221-478-97524
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12
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Autophagy-Independent Functions of the Autophagy Machinery. Cell 2020; 177:1682-1699. [PMID: 31199916 PMCID: PMC7173070 DOI: 10.1016/j.cell.2019.05.026] [Citation(s) in RCA: 540] [Impact Index Per Article: 135.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/11/2019] [Accepted: 05/13/2019] [Indexed: 02/07/2023]
Abstract
Macroautophagy (herein referred to as autophagy) is an evolutionary ancient mechanism that culminates with the lysosomal degradation of superfluous or potentially dangerous cytosolic entities. Over the past 2 decades, the molecular mechanisms underlying several variants of autophagy have been characterized in detail. Accumulating evidence suggests that most, if not all, components of the molecular machinery for autophagy also mediate autophagy-independent functions. Here, we discuss emerging data on the non-autophagic functions of autophagy-relevant proteins.
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13
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Zhang Z, Guo M, Li Y, Shen M, Kong D, Shao J, Ding H, Tan S, Chen A, Zhang F, Zheng S. RNA-binding protein ZFP36/TTP protects against ferroptosis by regulating autophagy signaling pathway in hepatic stellate cells. Autophagy 2019; 16:1482-1505. [PMID: 31679460 DOI: 10.1080/15548627.2019.1687985] [Citation(s) in RCA: 245] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Ferroptosis is a recently discovered form of programmed cell death, but its regulatory mechanisms remain poorly understood. Here, we show that the RNA-binding protein ZFP36/TTP (ZFP36 ring finger protein) plays a crucial role in regulating ferroptosis in hepatic stellate cells (HSCs). Upon exposure to ferroptosis-inducing compounds, the ubiquitin ligase FBXW7/CDC4 (F-box and WD repeat domain containing 7) decreased ZFP36 protein expression by recognizing SFSGLPS motif. FBXW7 plasmid contributed to classical ferroptotic events, whereas ZFP36 plasmid impaired FBXW7 plasmid-induced HSC ferroptosis. Interestingly, ZFP36 plasmid inhibited macroautophagy/autophagy activation by destabilizing ATG16L1 (autophagy related 16 like 1) mRNA. ATG16L1 plasmid eliminated the inhibitory action of ZFP36 plasmid on ferroptosis, and FBXW7 plasmid enhanced the effect of ATG16L1 plasmid on autophagy. Importantly, ZFP36 plasmid promoted ATG16L1 mRNA decay via binding to the AU-rich elements (AREs) within the 3'-untranslated region. The internal mutation of the ARE region abrogated the ZFP36-mediated ATG16L1 mRNA instability, and prevented ZFP36 plasmid-mediated ferroptosis resistance. In mice, treatment with erastin and sorafenib alleviated murine liver fibrosis by inducing HSC ferroptosis. HSC-specific overexpression of Zfp36 impaired erastin- or sorafenib-induced HSC ferroptosis. Noteworthy, we analyzed the effect of sorafenib on HSC ferroptosis in fibrotic patients with hepatocellular carcinoma receiving sorafenib monotherapy. Attractively, sorafenib monotherapy led to ZFP36 downregulation, ferritinophagy activation, and ferroptosis induction in human HSCs. Overall, these results revealed novel molecular mechanisms and signaling pathways of ferroptosis, and also identified ZFP36-autophagy-dependent ferroptosis as a potential target for the treatment of liver fibrosis. ABBREVIATIONS ARE: AU-rich elements; ATG: autophagy related; BECN1: beclin 1; CHX: cycloheximide; COL1A1: collagen type I alpha 1 chain; ELAVL1/HuR: ELAV like RNA binding protein 1; FBXW7/CDC4: F-box and WD repeat domain containing 7; FN1: fibronectin 1; FTH1: ferritin heavy chain 1; GPX4/PHGPx: glutathione peroxidase 4; GSH: glutathione; HCC: hepatocellular carcinoma; HSC: hepatic stellate cell; LSEC: liver sinusoidal endothelial cell; MAP1LC3A: microtubule associated protein 1 light chain 3 alpha; MDA: malondialdehyde; NCOA4: nuclear receptor coactivator 4; PTGS2/COX2: prostaglandin-endoperoxide synthase 2; RBP: RNA-binding protein; ROS: reactive oxygen species; SLC7A11/xCT: solute carrier family 7 member 11; SQSTM1/p62: sequestosome 1; TNF: tumor necrosis factor; TP53/p53: tumor protein p53; UTR: untranslated region; ZFP36/TTP: ZFP36 ring finger protein.
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Affiliation(s)
- Zili Zhang
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine , Nanjing, China
| | - Mei Guo
- Department of Pathogenic biology and Immunology, Medical School, Southeast University , Nanjing, China
| | - Yujia Li
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine , Nanjing, China
| | - Min Shen
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine , Nanjing, China
| | - Desong Kong
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine , Nanjing, China
| | - Jiangjuan Shao
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine , Nanjing, China
| | - Hai Ding
- Department of Integrated TCM and Western Medicine, Nanjing Hospital Affiliated to Nanjing University of Chinese Medicine , Nanjing, China
| | - Shanzhong Tan
- Department of Integrated TCM and Western Medicine, Nanjing Hospital Affiliated to Nanjing University of Chinese Medicine , Nanjing, China
| | - Anping Chen
- Department of Pathology, School of Medicine, Saint Louis University , St Louis, USA
| | - Feng Zhang
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine , Nanjing, China.,Jiangsu Key Laboratory of Therapeutic Material of Chinese Medicine, Nanjing University of Chinese Medicine , Nanjing, China
| | - Shizhong Zheng
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Nanjing University of Chinese Medicine , Nanjing, China.,Jiangsu Key Laboratory of Therapeutic Material of Chinese Medicine, Nanjing University of Chinese Medicine , Nanjing, China
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14
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Maurya R, Kumar R, Saran S. AMPKα promotes basal autophagy induction in Dictyostelium discoideum. J Cell Physiol 2019; 235:4941-4953. [PMID: 31680241 DOI: 10.1002/jcp.29373] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 10/07/2019] [Indexed: 01/24/2023]
Abstract
Autophagy is a degradation process, wherein long-lived proteins, damaged organelles, and protein aggregates are degraded to maintain cellular homeostasis. Upon starvation, 5'-AMP-activated protein kinase (AMPK) initiates autophagy. We show that ampkα- cells exhibit 50% reduction in pinocytosis and display defective phagocytosis. Re-expression of AMPKα in ampkα- cells co-localizes with red fluorescence protein-tagged bacteria. The ampkα- cells show reduced cell survival and autophagic flux under basal and starvation conditions. Co-immunoprecipitation studies show conservation of the AMPK-ATG1 axis in basal autophagy. Computational analyses suggest that the N-terminal region of DdATG1 is amenable for interaction with AMPK. Furthermore, β-actin was found to be a novel interacting partner of AMPK, attributed to the alteration in macropinocytosis and phagocytosis in the absence of AMPK. Additionally, ampkα- cells exhibit enhanced poly-ubiquitinated protein levels and allied large ubiquitin-positive protein aggregates. Our findings suggest that AMPK provides links among pinocytosis, phagocytosis, autophagy, and is a requisite for basal autophagy in Dictyostelium.
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Affiliation(s)
- Ranjana Maurya
- Molecular Cell and Developmental Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Rakesh Kumar
- Molecular Cell and Developmental Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Shweta Saran
- Molecular Cell and Developmental Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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15
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Sharma D, Otto G, Warren EC, Beesley P, King JS, Williams RSB. Gamma secretase orthologs are required for lysosomal activity and autophagic degradation in Dictyostelium discoideum, independent of PSEN (presenilin) proteolytic function. Autophagy 2019; 15:1407-1418. [PMID: 30806144 PMCID: PMC6613883 DOI: 10.1080/15548627.2019.1586245] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mutations in the γ-secretase complex are strongly associated with familial Alzheimer disease. Both proteolytic and non-proteolytic functions for the γ-secretase complex have been previously described in mammalian model organisms, but their relative contributions to disease pathology remain unclear. Here, we dissect the roles of orthologs of the γ-secretase components in the model system Dictyostelium, focusing on endocytosis, lysosomal activity and autophagy. In this model, we show that the orthologs of PSEN (psenA and psenB), Ncstn (nicastrin) and Aph-1 (gamma-secretase subunit Aph-1), are necessary for optimal fluid-phase uptake by macropinocytosis and in multicellular development under basic pH conditions. Disruption of either psenA/B or Aph-1 proteins also leads to disrupted phagosomal proteolysis as well as decreased autophagosomal acidification and autophagic flux. This indicates a general defect in lysosomal trafficking and degradation, which we show leads to the accumulation of ubiquitinated protein aggregates in cells lacking psenA/B and Aph-1 proteins. Importantly, we find that all the endocytic defects observed in Dictyostelium PSEN ortholog mutants can be fully rescued by proteolytically inactive Dictyostelium psenB and human PSEN1 proteins. Our data therefore demonstrates an evolutionarily conserved non-proteolytic role for presenilin, and γ-secretase component orthologs, in maintaining Dictyostelium lysosomal trafficking and autophagy. Abbreviations: Atg8: autophagy protein 8a; Aph-1: gamma-secretase subunit Aph-1; crtA: calreticulin; ER: endoplasmic reticulum; GFP: green fluorescent protein; GSK3B: glycogen synthase kinase 3 beta; Ncstn: nicastrin; PSEN1: presenilin 1; psenA and psenB: Dictyostelium presenilin A and B; TRITC; tetramethylrhodamine isothiocyanate.
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Affiliation(s)
- Devdutt Sharma
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Grant Otto
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Eleanor C Warren
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Philip Beesley
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Jason S King
- b Department of Biomedical Sciences , University of Sheffield , Sheffield , UK
| | - Robin S B Williams
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
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16
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Functional Characterization of Ubiquitin-Like Core Autophagy Protein ATG12 in Dictyostelium discoideum. Cells 2019; 8:cells8010072. [PMID: 30669443 PMCID: PMC6356199 DOI: 10.3390/cells8010072] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/15/2019] [Accepted: 01/17/2019] [Indexed: 12/12/2022] Open
Abstract
Autophagy is a highly conserved intracellular degradative pathway that is crucial for cellular homeostasis. During autophagy, the core autophagy protein ATG12 plays, together with ATG5 and ATG16, an essential role in the expansion of the autophagosomal membrane. In this study we analyzed gene replacement mutants of atg12 in Dictyostelium discoideum AX2 wild-type and ATG16‾ cells. RNAseq analysis revealed a strong enrichment of, firstly, autophagy genes among the up-regulated genes and, secondly, genes implicated in cell motility and phagocytosis among the down-regulated genes in the generated ATG12‾, ATG16‾ and ATG12‾/16‾ cells. The mutant strains showed similar defects in fruiting body formation, autolysosome maturation, and cellular viability, implying that ATG12 and ATG16 act as a functional unit in canonical autophagy. In contrast, ablation of ATG16 or of ATG12 and ATG16 resulted in slightly more severe defects in axenic growth, macropinocytosis, and protein homeostasis than ablation of only ATG12, suggesting that ATG16 fulfils an additional function in these processes. Phagocytosis of yeast, spore viability, and maximal cell density were much more affected in ATG12‾/16‾ cells, indicating that both proteins also have cellular functions independent of each other. In summary, we show that ATG12 and ATG16 fulfil autophagy-independent functions in addition to their role in canonical autophagy.
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17
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Bozzaro S, Buracco S, Peracino B, Eichinger L. Dictyostelium Host Response to Legionella Infection: Strategies and Assays. Methods Mol Biol 2019; 1921:347-370. [PMID: 30694504 DOI: 10.1007/978-1-4939-9048-1_23] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The professional phagocyte Dictyostelium discoideum is a well-established model organism to study host-pathogen interactions. Dictyostelium amoebae grow as separate, independent cells; they divide by binary fission and take up bacteria and yeast via phagocytosis. In the year 2000, D. discoideum was described by two groups as a novel system for genetic analysis of host-pathogen interactions for the intracellular pathogen Legionella pneumophila. Since then additional microbial pathogens that can be studied in D. discoideum have been reported. The organism has various advantages for the dissection of the complex cross-talk between a host and a pathogen. A fully sequenced and well-curated genome is available, there are excellent molecular genetic tools on the market, and the generation of targeted multiple gene knock-outs as well as the realization of untargeted genetic screens is generally straightforward. Dictyostelium also offers easy cultivation, and the cells are suitable for cell biological studies, which in combination with in vivo expression of fluorescence-tagged proteins allows the investigation of the dynamics of bacterial uptake and infection. Furthermore, a large mutant collection is available at the Dictyostelium stock center, favoring the identification of host resistance or susceptibility genes. Here, we briefly describe strategies to identify host cell factors important during an infection, followed by protocols for cell culture and storage, uptake and infection, and confocal microscopy of infected cells.
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Affiliation(s)
- Salvatore Bozzaro
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Italy.
| | - Simona Buracco
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Italy
| | - Barbara Peracino
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Italy
| | - Ludwig Eichinger
- Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
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18
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Xiong Q, Li W, Li P, Yang M, Wu C, Eichinger L. The Role of ATG16 in Autophagy and The Ubiquitin Proteasome System. Cells 2018; 8:cells8010002. [PMID: 30577509 PMCID: PMC6356889 DOI: 10.3390/cells8010002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/17/2018] [Accepted: 12/18/2018] [Indexed: 02/07/2023] Open
Abstract
Autophagy and the ubiquitin proteasome system (UPS) are the two major cellular degradation pathways, which are critical for the maintenance of cell homeostasis. The two pathways differ in their mechanisms and clients. The evolutionary conserved ATG16 plays a key role in autophagy and appears to link autophagy with the UPS. Here, we review the role of ATG16 in different species. We summarize the current knowledge of its functions in autophagosome membrane expansion and autophagosome formation, in Crohn’s disease, and in bacterial sequestration. In addition, we provide information on its autophagy-independent functions and its role in the crosstalk between autophagy and the UPS.
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Affiliation(s)
- Qiuhong Xiong
- Institute of Biomedical Sciences, Shanxi University, No.92 Wucheng Road, Taiyuan 030006, China.
| | - Wenjing Li
- Institute of Biomedical Sciences, Shanxi University, No.92 Wucheng Road, Taiyuan 030006, China.
| | - Ping Li
- Institute of Biomedical Sciences, Shanxi University, No.92 Wucheng Road, Taiyuan 030006, China.
| | - Min Yang
- Institute of Biomedical Sciences, Shanxi University, No.92 Wucheng Road, Taiyuan 030006, China.
| | - Changxin Wu
- Institute of Biomedical Sciences, Shanxi University, No.92 Wucheng Road, Taiyuan 030006, China.
| | - Ludwig Eichinger
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany.
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19
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Xiong Q, Fischer S, Karow M, Müller R, Meßling S, Eichinger L. ATG16 mediates the autophagic degradation of the 19S proteasomal subunits PSMD1 and PSMD2. Eur J Cell Biol 2018; 97:523-532. [PMID: 30269947 DOI: 10.1016/j.ejcb.2018.09.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 08/06/2018] [Accepted: 09/10/2018] [Indexed: 12/27/2022] Open
Abstract
Autophagy and the ubiquitin proteasome system are the two major cellular processes for protein and organelle recycling and clearance in eukaryotic cells. Evidence is accumulating that these two pathways are interrelated through adaptor proteins. Here, we found that PSMD1 and PSMD2, both components of the 19S regulatory particle of the proteasome, directly interact with Dictyostelium discoideum autophagy 16 (ATG16), a core autophagosomal protein. ATG16 is composed of an N-terminal domain, which is responsible for homo-dimerization and binding to ATG5 and a C-terminal β-propeller structure. Deletion analysis of ATG16 showed that the N-terminal half of ATG16 interacted directly only with PSMD1, while the C-terminal half interacted with both, PSMD1 and PSMD2. RFP-tagged PSMD1 as well as PSMD2 were enriched in large puncta, reminiscent of autophagosomes, in wild-type cells. These puncta were absent in atg16‾ and atg9‾/16‾ cells and weaker and less frequent in atg9‾ cells, showing that ATG16 was crucial and the autophagic process important for their formation. Co-expression of ATG16-GFP or GFP-ATG8a(LC3) with RFP-PSMD1 or RFP-PSMD2, respectively, in atg16‾ or wild-type cells revealed many instances of co-localization, suggesting that RFP-PSMD1 or RFP-PSMD2 positive puncta constitute autophagosomes. LysoTracker® labeling and a proteolytic cleavage assay confirmed that PSMD1 and PSMD2 were present in lysosomes in wild-type cells. In vivo, ATG16 is required for their enrichment in ATG8a positive puncta, which mature into autolysosomes. We propose that ATG16 links autophagy and the ubiquitin proteasome system.
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Affiliation(s)
- Qiuhong Xiong
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany.; Institute of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, 030006 Taiyuan, Shanxi, China
| | - Sarah Fischer
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Malte Karow
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Rolf Müller
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Susanne Meßling
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Ludwig Eichinger
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany..
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20
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Song L, Rijal R, Karow M, Stumpf M, Hahn O, Park L, Insall R, Schröder R, Hofmann A, Clemen CS, Eichinger L. Expression of N471D strumpellin leads to defects in the endolysosomal system. Dis Model Mech 2018; 11:dmm033449. [PMID: 30061306 PMCID: PMC6177004 DOI: 10.1242/dmm.033449] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 07/09/2018] [Indexed: 12/11/2022] Open
Abstract
Hereditary spastic paraplegias (HSPs) are genetically diverse and clinically characterised by lower limb weakness and spasticity. The N471D and several other point mutations of human strumpellin (Str; also known as WASHC5), a member of the Wiskott-Aldrich syndrome protein and SCAR homologue (WASH) complex, have been shown to cause a form of HSP known as spastic paraplegia 8 (SPG8). To investigate the molecular functions of wild-type (WT) and N417D Str, we generated Dictyostelium Str- cells and ectopically expressed StrWT-GFP or StrN471D-GFP in Str- and WT cells. Overexpression of both proteins apparently caused a defect in cell division, as we observed a clear increase in multinucleate cells. Real-time PCR analyses revealed no transcriptional changes in WASH complex subunits in Str- cells, but western blots showed a twofold decrease in the SWIP subunit. GFP-trap experiments in conjunction with mass-spectrometric analysis revealed many previously known, as well as new, Str-interacting proteins, and also proteins that no longer bind to StrN471D At the cellular level, Str- cells displayed defects in cell growth, phagocytosis, macropinocytosis, exocytosis and lysosomal function. Expression of StrWT-GFP in Str- cells rescued all observed defects. In contrast, expression of StrN471D-GFP could not rescue lysosome morphology and exocytosis of indigestible material. Our results underscore a key role for the WASH complex and its core subunit, Str, in the endolysosomal system, and highlight the fundamental importance of the Str N471 residue for maintaining lysosome morphology and dynamics. Our data indicate that the SPG8-causing N471D mutation leads to a partial loss of Str function in the endolysosomal system. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Lin Song
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Ramesh Rijal
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
- Department of Biology, Texas A&M University, College Station, TX 3258, USA
| | - Malte Karow
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Maria Stumpf
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Oliver Hahn
- Max Planck Institute for Biology of Ageing, Biological Mechanisms of Ageing, 50931 Cologne, Germany
| | - Laura Park
- CR-UK Beatson Institute, Institute of Cancer Sciences, Glasgow University, Glasgow G12 8QQ, UK
| | - Robert Insall
- CR-UK Beatson Institute, Institute of Cancer Sciences, Glasgow University, Glasgow G12 8QQ, UK
| | - Rolf Schröder
- Institute of Neuropathology, University Hospital Erlangen, 91054 Erlangen, Germany
| | - Andreas Hofmann
- Structural Chemistry Program, Eskitis Institute, Griffith University, N75 Don Young Road, Nathan, QLD 4111, Australia
- Faculty of Veterinary Science, The University of Melbourne, Parkville, VIC 3030, Australia
| | - Christoph S Clemen
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
| | - Ludwig Eichinger
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
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21
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Swart AL, Harrison CF, Eichinger L, Steinert M, Hilbi H. Acanthamoeba and Dictyostelium as Cellular Models for Legionella Infection. Front Cell Infect Microbiol 2018; 8:61. [PMID: 29552544 PMCID: PMC5840211 DOI: 10.3389/fcimb.2018.00061] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 02/13/2018] [Indexed: 12/20/2022] Open
Abstract
Environmental bacteria of the genus Legionella naturally parasitize free-living amoebae. Upon inhalation of bacteria-laden aerosols, the opportunistic pathogens grow intracellularly in alveolar macrophages and can cause a life-threatening pneumonia termed Legionnaires' disease. Intracellular replication in amoebae and macrophages takes place in a unique membrane-bound compartment, the Legionella-containing vacuole (LCV). LCV formation requires the bacterial Icm/Dot type IV secretion system, which translocates literally hundreds of "effector" proteins into host cells, where they modulate crucial cellular processes for the pathogen's benefit. The mechanism of LCV formation appears to be evolutionarily conserved, and therefore, amoebae are not only ecologically significant niches for Legionella spp., but also useful cellular models for eukaryotic phagocytes. In particular, Acanthamoeba castellanii and Dictyostelium discoideum emerged over the last years as versatile and powerful models. Using genetic, biochemical and cell biological approaches, molecular interactions between amoebae and Legionella pneumophila have recently been investigated in detail with a focus on the role of phosphoinositide lipids, small and large GTPases, autophagy components and the retromer complex, as well as on bacterial effectors targeting these host factors.
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Affiliation(s)
- A Leoni Swart
- Institute of Medical Microbiology, Medical Faculty, University of Zurich, Zurich, Switzerland
| | - Christopher F Harrison
- Max von Pettenkofer Institute, Medical Faculty, Ludwig-Maximilians University Munich, Munich, Germany
| | - Ludwig Eichinger
- Institute for Biochemistry I, Medical Faculty, University Hospital Cologne, Cologne, Germany
| | - Michael Steinert
- Department of Life Sciences, Institute of Microbiology, Technical University of Braunschweig, Braunschweig, Germany
| | - Hubert Hilbi
- Institute of Medical Microbiology, Medical Faculty, University of Zurich, Zurich, Switzerland
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22
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Methods to Monitor and Quantify Autophagy in the Social Amoeba Dictyostelium discoideum. Cells 2017; 6:cells6030018. [PMID: 28671610 PMCID: PMC5617964 DOI: 10.3390/cells6030018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 12/30/2022] Open
Abstract
Autophagy is a eukaryotic catabolic pathway that degrades and recycles cellular components to maintain homeostasis. It can target protein aggregates, superfluous biomolecular complexes, dysfunctional and damaged organelles, as well as pathogenic intracellular microbes. Autophagy is a dynamic process in which the different stages from initiation to final degradation of cargo are finely regulated. Therefore, the study of this process requires the use of a palette of techniques, which are continuously evolving and whose interpretation is not trivial. Here, we present the social amoeba Dictyostelium discoideum as a relevant model to study autophagy. Several methods have been developed based on the tracking and observation of autophagosomes by microscopy, analysis of changes in expression of autophagy genes and proteins, and examination of the autophagic flux with various techniques. In this review, we discuss the pros and cons of the currently available techniques to assess autophagy in this organism.
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Meßling S, Matthias J, Xiong Q, Fischer S, Eichinger L. The two Dictyostelium discoideum autophagy 8 proteins have distinct autophagic functions. Eur J Cell Biol 2017; 96:312-324. [PMID: 28413119 DOI: 10.1016/j.ejcb.2017.03.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/23/2017] [Accepted: 03/23/2017] [Indexed: 12/16/2022] Open
Abstract
Autophagy is a highly conserved cellular degradation pathway which is crucial for various cellular processes. The autophagic process is subdivided in the initiation, autophagosome maturation and lysosomal degradation phases and involves more than forty core and accessory autophagy-related (ATG) proteins. Autophagy 8 (ATG8, in mammals LC3) is a well-established marker of autophagy and is linked to the autophagic membrane from initiation until fusion with the lysosome. We generated single and double knock-out mutants of the two Dictyostelium paralogues, ATG8a and ATG8b, as well as strains that expressed RFP-ATG8a and/or GFP-ATG8b, RFP-ATG8b, RFP-GFP-ATG8a or RFP-GFP-ATG8b in different knock-out mutants. The ATG8b¯ mutant displayed only subtle phenotypic changes in comparison to AX2 wild-type cells. In contrast, deletion of ATG8a resulted in a complex phenotype with delayed development, reduced growth, phagocytosis and cell viability, an increase in ubiquitinylated proteins and a concomitant decrease in proteasomal activity. The phenotype of the ATG8a¯/b¯ strain was, except for cell viability, in all aforementioned aspects more severe, showing that both proteins function in parallel during most analysed cellular processes. Immunofluorescence analysis of knock-out strains expressing either RFP-GFP-ATG8a or RFP-GFP-ATG8b suggests a crucial function for ATG8b in autophagosome-lysosome fusion. Quantitative analysis of strains expressing RFP-ATG8a, RFP-ATG8b, or RFP-ATG8a and GFP-ATG8b revealed that ATG8b generally localised to small and large vesicles, whereas ATG8a preferentially co-localised with ATG8b on large vesicles, indicating that ATG8b associated with nascent autophagosomes before ATG8a, which is supported by previous results (Matthias et al., 2016). Deconvoluted confocal fluorescence images showed that ATG8b localised around ATG8a and was presumably mainly present on the outer membrane of the autophagosome while ATG8a appears to be mainly associated with the inner membrane. In summary, our data show that ATG8a and ATG8b have distinct functions and are involved in canonical as well as non-canonical autophagy. The data further suggest that ATG8b predominantly acts as adapter for the autophagy machinery at the outer and ATG8a as cargo receptor at the inner membrane of the autophagosome.
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Affiliation(s)
- Susanne Meßling
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Jan Matthias
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Qiuhong Xiong
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Sarah Fischer
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Ludwig Eichinger
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany.
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24
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Mesquita A, Cardenal-Muñoz E, Dominguez E, Muñoz-Braceras S, Nuñez-Corcuera B, Phillips BA, Tábara LC, Xiong Q, Coria R, Eichinger L, Golstein P, King JS, Soldati T, Vincent O, Escalante R. Autophagy in Dictyostelium: Mechanisms, regulation and disease in a simple biomedical model. Autophagy 2016; 13:24-40. [PMID: 27715405 DOI: 10.1080/15548627.2016.1226737] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Autophagy is a fast-moving field with an enormous impact on human health and disease. Understanding the complexity of the mechanism and regulation of this process often benefits from the use of simple experimental models such as the social amoeba Dictyostelium discoideum. Since the publication of the first review describing the potential of D. discoideum in autophagy, significant advances have been made that demonstrate both the experimental advantages and interest in using this model. Since our previous review, research in D. discoideum has shed light on the mechanisms that regulate autophagosome formation and contributed significantly to the study of autophagy-related pathologies. Here, we review these advances, as well as the current techniques to monitor autophagy in D. discoideum. The comprehensive bioinformatics search of autophagic proteins that was a substantial part of the previous review has not been revisited here except for those aspects that challenged previous predictions such as the composition of the Atg1 complex. In recent years our understanding of, and ability to investigate, autophagy in D. discoideum has evolved significantly and will surely enable and accelerate future research using this model.
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Affiliation(s)
- Ana Mesquita
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain.,b University of Cincinnati College of Medicine , Cincinnati , OH , USA
| | - Elena Cardenal-Muñoz
- c Départment de Biochimie , Faculté des Sciences, Université de Genève , Switzerland
| | - Eunice Dominguez
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain.,d Departamento de Genética Molecular , Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Mexico City , México
| | - Sandra Muñoz-Braceras
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
| | | | - Ben A Phillips
- e Department of Biomedical Sciences , University of Sheffield , UK
| | - Luis C Tábara
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
| | - Qiuhong Xiong
- f Center for Biochemistry, Medical Faculty, University of Cologne , Cologne , Germany
| | - Roberto Coria
- d Departamento de Genética Molecular , Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Mexico City , México
| | - Ludwig Eichinger
- f Center for Biochemistry, Medical Faculty, University of Cologne , Cologne , Germany
| | - Pierre Golstein
- g Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2 , Inserm, U1104, CNRS UMR7280, Marseille , France
| | - Jason S King
- e Department of Biomedical Sciences , University of Sheffield , UK
| | - Thierry Soldati
- c Départment de Biochimie , Faculté des Sciences, Université de Genève , Switzerland
| | - Olivier Vincent
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
| | - Ricardo Escalante
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
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Mesquita A, Tábara LC, Martinez-Costa O, Santos-Rodrigo N, Vincent O, Escalante R. Dissecting the function of Atg1 complex in Dictyostelium autophagy reveals a connection with the pentose phosphate pathway enzyme transketolase. Open Biol 2016; 5:rsob.150088. [PMID: 26246495 PMCID: PMC4554924 DOI: 10.1098/rsob.150088] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The network of protein–protein interactions of the Dictyostelium discoideum autophagy pathway was investigated by yeast two-hybrid screening of the conserved autophagic proteins Atg1 and Atg8. These analyses confirmed expected interactions described in other organisms and also identified novel interactors that highlight the complexity of autophagy regulation. The Atg1 kinase complex, an essential regulator of autophagy, was investigated in detail here. The composition of the Atg1 complex in D. discoideum is more similar to mammalian cells than to Saccharomyces cerevisiae as, besides Atg13, it contains Atg101, a protein not conserved in this yeast. We found that Atg101 interacts with Atg13 and genetic disruption of these proteins in Dictyostelium leads to an early block in autophagy, although the severity of the developmental phenotype and the degree of autophagic block is higher in Atg13-deficient cells. We have also identified a protein containing zinc-finger B-box and FNIP motifs that interacts with Atg101. Disruption of this protein increases autophagic flux, suggesting that it functions as a negative regulator of Atg101. We also describe the interaction of Atg1 kinase with the pentose phosphate pathway enzyme transketolase (TKT). We found changes in the activity of endogenous TKT activity in strains lacking or overexpressing Atg1, suggesting the presence of an unsuspected regulatory pathway between autophagy and the pentose phosphate pathway in Dictyostelium that seems to be conserved in mammalian cells.
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Affiliation(s)
- Ana Mesquita
- Instituto de Investigaciones Biomédicas Alberto Sols, CSIC/UAM, Madrid, Spain
| | - Luis C Tábara
- Instituto de Investigaciones Biomédicas Alberto Sols, CSIC/UAM, Madrid, Spain
| | | | | | - Olivier Vincent
- Instituto de Investigaciones Biomédicas Alberto Sols, CSIC/UAM, Madrid, Spain
| | - Ricardo Escalante
- Instituto de Investigaciones Biomédicas Alberto Sols, CSIC/UAM, Madrid, Spain
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26
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Bühler A, Kustermann M, Bummer T, Rottbauer W, Sandri M, Just S. Atrogin-1 Deficiency Leads to Myopathy and Heart Failure in Zebrafish. Int J Mol Sci 2016; 17:ijms17020187. [PMID: 26840306 PMCID: PMC4783921 DOI: 10.3390/ijms17020187] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/13/2016] [Accepted: 01/18/2016] [Indexed: 12/21/2022] Open
Abstract
Orchestrated protein synthesis and degradation is fundamental for proper cell function. In muscle, impairment of proteostasis often leads to severe cellular defects finally interfering with contractile function. Here, we analyze for the first time the role of Atrogin-1, a muscle-specific E3 ubiquitin ligase known to be involved in the regulation of protein degradation via the ubiquitin proteasome and the autophagy/lysosome systems, in the in vivo model system zebrafish (Danio rerio). We found that targeted inactivation of zebrafish Atrogin-1 leads to progressive impairment of heart and skeletal muscle function and disruption of muscle structure without affecting early cardiogenesis and skeletal muscle development. Autophagy is severely impaired in Atrogin-1-deficient zebrafish embryos resulting in the disturbance of the cytoarchitecture of cardiomyocytes and skeletal muscle cells. These observations are consistent with molecular and ultrastructural findings in an Atrogin-1 knockout mouse and demonstrate that the zebrafish is a suitable vertebrate model to study the molecular mechanisms of Atrogin-1-mediated autophagic muscle pathologies and to screen for novel therapeutically active substances in high-throughput in vivo small compound screens (SCS).
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Affiliation(s)
- Anja Bühler
- Molecular Cardiology, University of Ulm, 89081 Ulm, Germany.
| | | | - Tiziana Bummer
- Molecular Cardiology, University of Ulm, 89081 Ulm, Germany.
| | - Wolfgang Rottbauer
- Department of Internal Medicine II, University of Ulm, 89081 Ulm, Germany.
| | - Marco Sandri
- Department of Biomedical Sciences, University of Padova, 35129 Padova, Italy.
| | - Steffen Just
- Molecular Cardiology, University of Ulm, 89081 Ulm, Germany.
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The two Dictyostelium autophagy eight proteins, ATG8a and ATG8b, associate with the autophagosome in succession. Eur J Cell Biol 2016; 95:15-25. [DOI: 10.1016/j.ejcb.2015.10.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 10/27/2015] [Accepted: 10/29/2015] [Indexed: 12/19/2022] Open
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