1
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Yang LM, Zheng Q, Liu XJ, Li XX, Veronica L, Chen Q, Zhao ZH, Wang SY. Exosome-Transmitted miR-224-5p Promotes Colorectal Cancer Cell Proliferation via Targeting ULK2 in p53-Dependent Manner. Biomed Environ Sci 2024; 37:71-84. [PMID: 38326722 DOI: 10.3967/bes2023.144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 08/01/2023] [Indexed: 02/09/2024]
Abstract
Objective To investigate the role and molecular mechanism of exosomal miR-224-5p in colorectal cancer (CRC). Methods The miR-224-5p expression in CRC patient tissues and cell-derived exosomes was measured by laser capture microdissection and qRT-PCR, respectively. Dual-luciferase reporter gene assay was used to determine the target gene of miR-224-5p. The protein expressions of p53 and unc-51 like kinase 2 (ULK2) in CRC cells were detected by western blot. Flow cytometry was used to detect cell cycle and apoptosis. Cell proliferation was measured by CCK8 and EdU assay. Results The miR-224-5p expression was upregulated in CRC tissues and increased progressively with the rise of CRC stage. CRC cells secreted extracellular miR-224-5p mainly in an exosome-dependent manner, and then miR-224-5p could be transferred to surrounding tumor cells to regulate cell proliferation in the form of autocrine or paracrine. Moreover, ULK2 was characterized as a direct target of miR-224-5p and was downregulated in CRC tissues. Interestingly, ULK2 inhibited CRC cell proliferation in a p53-dependent manner. Furthermore, exosome-derived miR-224-5p partially reversed the proliferation regulation of ULK2 on CRC cells. Conclusion Our findings demonstrate that exosome-transmitted miR-224-5p promotes p53-dependent cell proliferation by targeting ULK2 in CRC, which may offer promising targets for CRC prevention and therapy.
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Affiliation(s)
- Le Mei Yang
- Department of Pathology, School of Basic Medicine, Fudan University, Shanghai 200032, China
| | - Qi Zheng
- Department of Pathology, School of Basic Medicine, Fudan University, Shanghai 200032, China;Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin 9054, New Zealand
| | - Xiao Jia Liu
- Department of Pathology, School of Basic Medicine, Fudan University, Shanghai 200032, China;Department of Pathology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Xian Xian Li
- Department of Pathology, School of Basic Medicine, Fudan University, Shanghai 200032, China;Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Lim Veronica
- Teladoc Health Inc, Shanghai 200335, China;Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Qi Chen
- Department of Pathology, School of Basic Medicine, Fudan University, Shanghai 200032, China
| | - Zhong Hua Zhao
- Department of Pathology, School of Basic Medicine, Fudan University, Shanghai 200032, China
| | - Shu Yang Wang
- Department of Pathology, School of Basic Medicine, Fudan University, Shanghai 200032, China;Shanghai Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention, Shanghai 200032, China
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2
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Vaughan RM, Dickson BM, Martin KR, MacKeigan JP. Molecular dynamics simulations provide insights into ULK-101 potency and selectivity toward autophagic kinases ULK1/2. bioRxiv 2023:2023.12.01.569261. [PMID: 38077086 PMCID: PMC10705459 DOI: 10.1101/2023.12.01.569261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Kinase domains are highly conserved within protein kinases in both sequence and structure. Many factors, including phosphorylation, amino acid substitutions or mutations, and small molecule inhibitor binding, influence conformations of the kinase domain and enzymatic activity. The serine/threonine kinases ULK1 and ULK2 are highly conserved with N- and C-terminal domains, phosphate-binding P-loops, αC-helix, regulatory and catalytic spines, and activation loop DFG and APE motifs. Here, we performed molecular dynamics (MD) simulations to understand better the potency and selectivity of the ULK1/2 small molecule inhibitor, ULK-101. We observed stable bound states for ULK-101 to the adenosine triphosphate (ATP)-binding site of ULK2, coordinated by hydrogen bonding with the hinge backbone and the catalytic lysine sidechain. Notably, ULK-101 occupies a hydrophobic pocket associated with the N-terminus of the αC-helix. Large movements in the P-loop are also associated with ULK-101 inhibitor binding and exit from ULK2. Our data further suggests that ULK-101 could induce a folded P-loop conformation and hydrophobic pocket reflected in its nanomolar potency and kinome selectivity.
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Affiliation(s)
- Robert M. Vaughan
- Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Bradley M. Dickson
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Katie R. Martin
- Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Jeffrey P. MacKeigan
- Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
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3
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Moscat J, Cuervo AM, Diaz-Meco MT. Immunosurveillance, interferon, and autophagic networking in cancer: the PRKCI- ULK2 paradigm. Autophagy 2022; 18:226-227. [PMID: 34895031 PMCID: PMC8865275 DOI: 10.1080/15548627.2021.1991192] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 01/31/2023] Open
Abstract
The mechanisms controlling immunosurveillance and immunoevasion often operate simultaneously to the triggering of the oncogenic signaling that results in tumor initiation. The resolution of the balance between anti-cancer immune responses and pro-tumorigenic pathways determines if a tumor cell survives and can remodel the microenvironment to reinforce immunosuppression or is eliminated by the immune system. Cancer cells must endure a toxic and metabolically challenging milieu. In its various forms, autophagy provides a way for transformed cells to survive by promoting catabolism and detoxification. Mounting evidence suggests that the boundaries between cancer immunity and mitogenic and metabolic programs are diffuse, with the same molecules likely serving several diverse roles in immunity and metabolism during tumor initiation and progression. Our recent data provide mechanistic detail and functional relevance of a new paradigm whereby the same signaling elements control immunity and autophagy in cancer.
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Affiliation(s)
- Jorge Moscat
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Ana Maria Cuervo
- Departments of Medicine and of Developmental and Molecular Biology and Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Maria T. Diaz-Meco
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
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4
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Abstract
Defects in macroautophagy/autophagy are implicated in the pathogenesis of neuromuscular and heart diseases. To precisely define the roles of autophagy-related genes in skeletal and cardiac muscles, we generated muscle-specific rb1cc1- and atg14-conditional knockout (cKO) mice by using Ckm/Ckmm2-Cre and compared their phenotypes to those of ulk1 ulk2-conditional double-knockout (cDKO) mice. atg14-cKO mice developed hypertrophic cardiomyopathy, which was associated with abnormal accumulation of autophagic cargoes in the heart and early mortality. Skeletal muscles of both atg14-cKO and rb1cc1-cKO mice showed features of autophagic vacuolar myopathy with ubiquitin+ SQSTM1+ deposits, but only those of rb1cc1-cKO mice showed TARDBP/TDP-43+ pathology and other features of the inclusion body myopathy-like disease we previously described in ulk1 ulk2-cDKO mice. Herein, we highlight tissue-specific differences between skeletal and cardiac muscles in their reliance on core autophagy proteins and unique roles for ULK1-ULK2 and RB1CC1 among these proteins in the development of TARDBP+ pathology.ABBREVIATIONS:AVM: autophagic vacuolar myopathy; cDKO: conditional double knockout; cKO: conditional knockout; H&E: hematoxylin and eosin; IBM: inclusion body myopathy; mtDNA: mitochondrial DNA; PFA: paraformaldehyde; RNP: ribonucleoprotein; TBST: Tris-buffered saline with 0.2% Triton X-100.
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Affiliation(s)
- Dongfang Li
- Departments of Pathology, St. Jude Children's Research Hospital, Memphis, TN, USA.,Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Peter Vogel
- Departments of Pathology, St. Jude Children's Research Hospital, Memphis, TN, USA.,Veterinary Pathology Core, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Xiujie Li-Harms
- Departments of Pathology, St. Jude Children's Research Hospital, Memphis, TN, USA.,Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Bo Wang
- Departments of Pathology, St. Jude Children's Research Hospital, Memphis, TN, USA.,Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA.,State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian Province, Fujian Province, China
| | - Mondira Kundu
- Departments of Pathology, St. Jude Children's Research Hospital, Memphis, TN, USA.,Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
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5
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Abstract
Toxic copper accumulation causes Wilson disease, but trace amounts of copper are required for cellular and organismal survival. In a recent paper Tsang et al. (Nat Cell Biol, doi: 10.1038/s41556-020-0481-4) demonstrate that copper binds with high affinity to a designated interaction site in the pro-autophagic kinases ULK1 and ULK2. Chelation of copper or genetic deletion of this copper-binding site inhibits autophagy and hence reduces the fitness of KRAS-induced cancers. These findings suggest that copper chelation might constitute a novel therapeutic intervention on autophagy-dependent malignancies.
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Affiliation(s)
- Hans Zischka
- Institute of Molecular Toxicology and Pharmacology, Helmholtz Center Munich, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.,Technical University Munich, School of Medicine, Institute of Toxicology and Environmental Hygiene, Biedersteiner Strasse 29, 80802 Munich, Germany
| | - Guido Kroemer
- Centre de Recherche des Cordeliers, Equipe labellisée par la Ligue contre le cancer, Université de Paris, Sorbonne Université, Inserm U1138, Institut Universitaire de France, Paris, France.,Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France.,Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France.,Suzhou Institute for Systems Medicine, Chinese Academy of Medical Sciences, Suzhou, China.,Karolinska Institute, Department of Women's and Children's Health, Karolinska University Hospital, Stockholm, Sweden
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6
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Stefely JA, Zhang Y, Freiberger EC, Kwiecien NW, Thomas HE, Davis AM, Lowry ND, Vincent CE, Shishkova E, Clark NA, Medvedovic M, Coon JJ, Pagliarini DJ, Mercer CA. Mass spectrometry proteomics reveals a function for mammalian CALCOCO1 in MTOR-regulated selective autophagy. Autophagy 2020; 16:2219-2237. [PMID: 31971854 DOI: 10.1080/15548627.2020.1719746] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Macroautophagy/autophagy is suppressed by MTOR (mechanistic target of rapamycin kinase) and is an anticancer target under active investigation. Yet, MTOR-regulated autophagy remains incompletely mapped. We used proteomic profiling to identify proteins in the MTOR-autophagy axis. Wild-type (WT) mouse cell lines and cell lines lacking individual autophagy genes (Atg5 or Ulk1/Ulk2) were treated with an MTOR inhibitor to induce autophagy and cultured in media with either glucose or galactose. Mass spectrometry proteome profiling revealed an elevation of known autophagy proteins and candidates for new autophagy components, including CALCOCO1 (calcium binding and coiled-coil domain protein 1). We show that CALCOCO1 physically interacts with MAP1LC3C, a key protein in the machinery of autophagy. Genetic deletion of CALCOCO1 disrupted autophagy of the endoplasmic reticulum (reticulophagy). Together, these results reveal a role for CALCOCO1 in MTOR-regulated selective autophagy. More generally, the resource generated by this work provides a foundation for establishing links between the MTOR-autophagy axis and proteins not previously linked to this pathway. Abbreviations: ATG: autophagy-related; CALCOCO1: calcium binding and coiled-coil domain protein 1; CALCOCO2/NDP52: calcium binding and coiled-coil domain protein 2; CLIR: MAP1LC3C-interacting region; CQ: chloroquine; KO: knockout; LIR: MAP1LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MEF: mouse embryonic fibroblast; MLN: MLN0128 ATP-competitive MTOR kinase inhibitor; MTOR: mechanistic target of rapamycin kinase; reticulophagy: selective autophagy of the endoplasmic reticulum; TAX1BP1/CALCOCO3: TAX1 binding protein 1; ULK: unc 51-like autophagy activating kinase; WT: wild-type.
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Affiliation(s)
- Jonathan A Stefely
- Morgridge Institute for Research , Madison, WI, USA.,Medical Scientist Training Program, School of Medicine and Public Health, University of Wisconsin-Madison , Madison, WI, USA.,Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati , Cincinnati, OH, USA
| | - Yu Zhang
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati , Cincinnati, OH, USA
| | - Elyse C Freiberger
- Department of Chemistry, University ofWisconsin-Madison , Madison, WI, USA.,Department of Biomolecular Chemistry, University ofWisconsin-Madison , Madison, WI, USA.,Genome Center of Wisconsin , Madison, WI, USA.,Department of Biochemistry, University ofWisconsin-Madison , Madison, Madison, WI, USA
| | - Nicholas W Kwiecien
- Department of Chemistry, University ofWisconsin-Madison , Madison, WI, USA.,Department of Biomolecular Chemistry, University ofWisconsin-Madison , Madison, WI, USA.,Genome Center of Wisconsin , Madison, WI, USA.,Department of Biochemistry, University ofWisconsin-Madison , Madison, Madison, WI, USA
| | - Hala Elnakat Thomas
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati , Cincinnati, OH, USA
| | - Alexander M Davis
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati , Cincinnati, OH, USA
| | - Nathaniel D Lowry
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati , Cincinnati, OH, USA
| | - Catherine E Vincent
- Genome Center of Wisconsin , Madison, WI, USA.,Department of Chemistry, Hartwick College , Oneonta, NY, USA
| | | | - Nicholas A Clark
- Division of Biostatistics and Bioinformatics, Department of Environmental Health, University of Cincinnati , Cincinnati, OH, USA
| | - Mario Medvedovic
- Division of Biostatistics and Bioinformatics, Department of Environmental Health, University of Cincinnati , Cincinnati, OH, USA
| | - Joshua J Coon
- Morgridge Institute for Research , Madison, WI, USA.,Department of Chemistry, University ofWisconsin-Madison , Madison, WI, USA.,Department of Biomolecular Chemistry, University ofWisconsin-Madison , Madison, WI, USA.,Genome Center of Wisconsin , Madison, WI, USA
| | - David J Pagliarini
- Morgridge Institute for Research , Madison, WI, USA.,Department of Biochemistry, University ofWisconsin-Madison , Madison, Madison, WI, USA
| | - Carol A Mercer
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati , Cincinnati, OH, USA
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7
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Anwar T, Liu X, Suntio T, Marjamäki A, Biazik J, Chan EYW, Varjosalo M, Eskelinen EL. ER-Targeted Beclin 1 Supports Autophagosome Biogenesis in the Absence of ULK1 and ULK2 Kinases. Cells 2019; 8:cells8050475. [PMID: 31108943 PMCID: PMC6562811 DOI: 10.3390/cells8050475] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/10/2019] [Accepted: 05/15/2019] [Indexed: 12/14/2022] Open
Abstract
Autophagy transports cytoplasmic material and organelles to lysosomes for degradation and recycling. Beclin 1 forms a complex with several other autophagy proteins and functions in the initiation phase of autophagy, but the exact role of Beclin 1 subcellular localization in autophagy initiation is still unclear. In order to elucidate the role of Beclin 1 localization in autophagosome biogenesis, we generated constructs that target Beclin 1 to the endoplasmic reticulum (ER) or mitochondria. Our results confirmed the proper organelle-specific targeting of the engineered Beclin 1 constructs, and the proper formation of autophagy-regulatory Beclin 1 complexes. The ULK kinases are required for autophagy initiation upstream of Beclin 1, and autophagosome biogenesis is severely impaired in ULK1/ULK2 double knockout cells. We tested whether Beclin 1 targeting facilitated its ability to rescue autophagosome formation in ULK1/ULK2 double knockout cells. ER-targeted Beclin 1 was most effective in the rescue experiments, while mitochondria-targeted and non-targeted Beclin 1 also showed an ability to rescue, but with lower activity. However, none of the constructs was able to increase autophagic flux in the knockout cells. We also showed that wild type Beclin 1 was enriched on the ER during autophagy induction, and that ULK1/ULK2 facilitated the ER-enrichment of Beclin 1 under basal conditions. The results suggest that one of the functions of ULK kinases may be to enhance Beclin 1 recruitment to the ER to drive autophagosome formation.
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Affiliation(s)
- Tahira Anwar
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, 00014 Helsinki, Finland.
| | - Xiaonan Liu
- Institute of Biotechnology & HiLIFE, University of Helsinki, 00014 Helsinki, Finland.
| | - Taina Suntio
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland.
| | - Annika Marjamäki
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, 00014 Helsinki, Finland.
| | - Joanna Biazik
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, 00014 Helsinki, Finland.
| | - Edmond Y W Chan
- Department of Biomedical and Molecular Sciences and Department of Pathology and Molecular Medicine, Queen's University, Kingston, ON K7L 3N6, Canada.
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK.
| | - Markku Varjosalo
- Institute of Biotechnology & HiLIFE, University of Helsinki, 00014 Helsinki, Finland.
| | - Eeva-Liisa Eskelinen
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, 00014 Helsinki, Finland.
- Institute of Biomedicine, University of Turku, 20520 Turku, Finland.
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8
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Wang B, Maxwell BA, Joo JH, Gwon Y, Messing J, Mishra A, Shaw TI, Ward AL, Quan H, Sakurada SM, Pruett-Miller SM, Bertorini T, Vogel P, Kim HJ, Peng J, Taylor JP, Kundu M. ULK1 and ULK2 Regulate Stress Granule Disassembly Through Phosphorylation and Activation of VCP/p97. Mol Cell 2019; 74:742-757.e8. [PMID: 30979586 DOI: 10.1016/j.molcel.2019.03.027] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 02/08/2019] [Accepted: 03/22/2019] [Indexed: 12/22/2022]
Abstract
Disturbances in autophagy and stress granule dynamics have been implicated as potential mechanisms underlying inclusion body myopathy (IBM) and related disorders. Yet the roles of core autophagy proteins in IBM and stress granule dynamics remain poorly characterized. Here, we demonstrate that disrupted expression of the core autophagy proteins ULK1 and ULK2 in mice causes a vacuolar myopathy with ubiquitin and TDP-43-positive inclusions; this myopathy is similar to that caused by VCP/p97 mutations, the most common cause of familial IBM. Mechanistically, we show that ULK1/2 localize to stress granules and phosphorylate VCP, thereby increasing VCP's activity and ability to disassemble stress granules. These data suggest that VCP dysregulation and defective stress granule disassembly contribute to IBM-like disease in Ulk1/2-deficient mice. In addition, stress granule disassembly is accelerated by an ULK1/2 agonist, suggesting ULK1/2 as targets for exploiting the higher-order regulation of stress granules for therapeutic intervention of IBM and related disorders.
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Affiliation(s)
- Bo Wang
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Brian A Maxwell
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Joung Hyuck Joo
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Youngdae Gwon
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - James Messing
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Ashutosh Mishra
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Timothy I Shaw
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Amber L Ward
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Honghu Quan
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Sadie Miki Sakurada
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Center for Advanced Genome Engineering, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Shondra M Pruett-Miller
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Center for Advanced Genome Engineering, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Tulio Bertorini
- Department of Neurology, University of Tennessee Heath Science Center, Memphis, TN 38163, USA
| | - Peter Vogel
- Veterinary Pathology Core, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Hong Joo Kim
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Junmin Peng
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - J Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Mondira Kundu
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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9
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Chaikuad A, Koschade SE, Stolz A, Zivkovic K, Pohl C, Shaid S, Ren H, Lambert LJ, Cosford NDP, Brandts CH, Knapp S. Conservation of structure, function and inhibitor binding in UNC-51-like kinase 1 and 2 (ULK1/2). Biochem J 2019; 476:875-87. [PMID: 30782972 DOI: 10.1042/BCJ20190038] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 02/14/2019] [Accepted: 02/19/2019] [Indexed: 12/20/2022]
Abstract
Autophagy is essential for cellular homeostasis and when deregulated this survival mechanism has been associated with disease development. Inhibition of autophagy initiation by inhibiting the kinase ULK1 (Unc-51-like autophagy activating kinase 1) has been proposed as a potential cancer therapy. While inhibitors and crystal structures of ULK1 have been reported, little is known about the other closely related kinase ULK2 (Unc-51-like autophagy activating kinase 2). Here, we present the crystal structure of ULK2 in complex with ATP competitive inhibitors. Surprisingly, the ULK2 structure revealed a dimeric assembly reminiscent of dimeric arrangements of auto-activating kinases suggesting a role for this association in ULK activation. Screening of a kinase focused library of pre-clinical and clinical compounds revealed several potent ULK1/2 inhibitors and good correlation of inhibitor-binding behavior with both ULK kinases. Aurora A was identified as a major off-target of currently used ULK1 inhibitors. Autophagic flux assays demonstrated that this off-target activity by strongly inducing autophagy in different cellular systems conferred an additional layer of complexity in the interpretation of cellular data. The data presented here provide structural models and chemical starting points for the development of ULK1/2 dual inhibitors with improved selectivity for future exploitation of autophagy inhibition.
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10
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Abstract
Autophagy is an evolutionary conserved, degradative process from single-cell eukaryotes, such as Saccharomyces cerevisiae, to higher mammals, such as humans. The regulation of autophagy has been elucidated through the combined study of yeast, Caenorhabditis elegans, mice, Drosophila melanogaster, and humans. MTOR, the major negative regulator of autophagy, and activating nutrient kinases, such as 5'-AMP-activated protein kinase (AMPK), interact with the autophagy regulatory complex: ULK1/2, RB1CC1, ATG13, and ATG101. The ULK1/2 complex induces autophagy by phosphorylating downstream autophagy complexes, such as the BECN1 PIK3 signaling complex that leads to the creation of LC3+ autophagosomes. We highlight in this review various reports of autophagy induction that are independent of these regulators. We discuss reports of MTOR-independent, AMPK-independent, ULK1/2-independent, and BECN1-PIK3C3-independent autophagy. We illustrate that autophagy induction and the components required vary by the nature of the induction signal and type of cell and do not always require canonical members of the autophagy signaling pathway. We illustrate that rather than thinking of autophagy as a linear pathway, it is better to think of autophagy induction as an interconnecting web of key regulators, many of which can induce autophagy through different requirements depending on the type and length of induction signals.
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Affiliation(s)
- Angel F Corona Velazquez
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - William T Jackson
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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11
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Corona Velazquez A, Corona AK, Klein KA, Jackson WT. Poliovirus induces autophagic signaling independent of the ULK1 complex. Autophagy 2018; 14:1201-1213. [PMID: 29929428 PMCID: PMC6103675 DOI: 10.1080/15548627.2018.1458805] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 12/07/2017] [Accepted: 03/26/2018] [Indexed: 12/31/2022] Open
Abstract
Poliovirus (PV), like many positive-strand RNA viruses, subverts the macroautophagy/autophagy pathway to promote its own replication. Here, we investigate whether the virus uses the canonical autophagic signaling complex, consisting of the ULK1/2 kinases, ATG13, RB1CC1, and ATG101, to activate autophagy. We find that the virus sends autophagic signals independent of the ULK1 complex, and that the members of the autophagic complex are not required for normal levels of viral replication. We also show that the SQSTM1/p62 receptor protein is not degraded in a conventional manner during infection, but is likely cleaved in a manner similar to that shown for coxsackievirus B3. This means that SQSTM1, normally used to monitor autophagic degradation, cannot be used to accurately monitor degradation during poliovirus infection. In fact, autophagic degradation may be affected by the loss of SQSTM1 at the same time as autophagic signals are being sent. Finally, we demonstrate that ULK1 and ULK2 protein levels are greatly reduced during PV infection, and ATG13, RB1CC1, and ATG101 protein levels are reduced as well. Surprisingly, autophagic signaling appears to increase as ULK1 levels decrease. Overexpression of wild-type or dominant-negative ULK1 constructs does not affect virus replication, indicating that ULK1 degradation may be a side effect of the ULK1-independent signaling mechanism used by PV, inducing complex instability. This demonstration of ULK1-independent autophagic signaling is novel and leads to a model by which the virus is signaling to generate autophagosomes downstream of ULK1, while at the same time, cleaving cargo receptors, which may affect cargo loading and autophagic degradative flux. Our data suggest that PV has a finely-tuned relationship with the autophagic machinery, generating autophagosomes without using the primary autophagy signaling pathway. ABBREVIATIONS ACTB - actin beta; ATG13 - autophagy related 13; ATG14 - autophagy related 14; ATG101 - autophagy related 101; BECN1 - beclin 1; CVB3 - coxsackievirus B3; DMV - double-membraned vesicles; EM - electron microscopy; EMCV - encephalomyocarditis virus; EV-71 - enterovirus 71; FMDV - foot and mouth disease virus; GFP - green fluorescent protein; MAP1LC3B/LC3B - microtubule associated protein 1 light chain 3 beta; MOI - multiplicity of infection; MTOR - mechanistic target of rapamycin kinase; PIK3C3 - phosphatidylinositol 3-kinase catalytic subunit type 3; PRKAA2 - protein kinase AMP-activated catalytic subunit alpha 2; PSMG1 - proteasome assembly chaperone 1; PSMG2 - proteasome assembly chaperone 2PV - poliovirus; RB1CC1 - RB1 inducible coiled-coil 1; SQSTM1 - sequestosome 1; ULK1 - unc-51 like autophagy activating kinase 1; ULK2 - unc-51 like autophagy activating kinase 2; WIPI1 - WD repeat domain, phosphoinositide interacting 1.
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Affiliation(s)
- Angel Corona Velazquez
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Abigail K. Corona
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kathryn A. Klein
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - William T. Jackson
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
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12
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Ran M, Li Z, Cao R, Weng B, Peng F, He C, Chen B. miR-26a suppresses autophagy in swine Sertoli cells by targeting ULK2. Reprod Domest Anim 2018; 53:864-871. [PMID: 29761550 DOI: 10.1111/rda.13177] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 02/24/2018] [Indexed: 12/28/2022]
Abstract
A large number of microRNAs (miRNAs) have been detected from porcine testicular tissues thanks to the development of high-throughput sequencing technology. However, the regulatory roles of most identified miRNAs in swine testicular development or spermatogenesis are poorly understood. In our previous study, ULK2 (uncoordinated-51-like kinase 2) was predicted as a target gene of miR-26a. In this study, we aimed to investigate the role of miR-26a in swine Sertoli cell autophagy. The relative expression of miR-26a and ULK2 levels has a significant negative correlation (R2 = .5964, p ≤ .01) in nine developmental stages of swine testicular tissue. Dual-luciferase reporter assay results show that miR-26a directly targets the 3'UTR of the ULK2 gene (position 618-624). In addition, both the mRNA and protein expression of ULK2 were downregulated by miR-26a in swine Sertoli cells. These results indicate that miR-26a targets the ULK2 gene and downregulates its expression in swine Sertoli cells. Based on the expression of marker genes (LC3, p62 and Beclin-1), overexpression of miR-26a or knock-down of ULK2 inhibits swine Sertoli cell autophagy. Taken together, these findings demonstrate that miR-26a suppresses autophagy in swine Sertoli cells by targeting ULK2.
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Affiliation(s)
- M Ran
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, Hunan, China.,Hunan Provincial Key Laboratory for Genetic Improvement of Domestic Animal, Changsha, China
| | - Z Li
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, Hunan, China.,Hunan Provincial Key Laboratory for Genetic Improvement of Domestic Animal, Changsha, China
| | - R Cao
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, Hunan, China.,Hunan Provincial Key Laboratory for Genetic Improvement of Domestic Animal, Changsha, China
| | - B Weng
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, Hunan, China.,Hunan Provincial Key Laboratory for Genetic Improvement of Domestic Animal, Changsha, China
| | - F Peng
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, Hunan, China.,Hunan Provincial Key Laboratory for Genetic Improvement of Domestic Animal, Changsha, China
| | - C He
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, Hunan, China.,Hunan Provincial Key Laboratory for Genetic Improvement of Domestic Animal, Changsha, China
| | - B Chen
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, Hunan, China.,Hunan Provincial Key Laboratory for Genetic Improvement of Domestic Animal, Changsha, China
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Hao K, Zhao S, Cui D, Zhang Y, Jiang C, Jing Y, Xia S, Han B. Androgen receptor antagonist bicalutamide induces autophagy and apoptosis via ULK2 upregulation in human bladder cancer cells. Int J Clin Exp Pathol 2017; 10:7603-7615. [PMID: 31966605 PMCID: PMC6965281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 04/23/2017] [Indexed: 06/10/2023]
Abstract
Studies have demonstrated a close link between autophagy and bladder cancer. The androgen receptor (AR) has also been found to be closely involved in bladder cancer progression. Although androgen ablation and AR antagonism have been proposed as potential methods for bladder cancer therapy, the mechanisms underlying their effects remain poorly understood. This study was designed to assess the effects of the AR antagonist bicalutamide on autophagy and apoptosis in bladder cancer cells. The results indicated that the AR has an inhibitory effect on autophagy in bladder cancer cells. Using different tests, we observed that bicalutamide promotes apoptosis in these cells and positively modulates autophagy in UM-UC-3 cells by upregulating ULK2. In addition, ULK2 knockdown inhibited autophagy and apoptosis in bladder cancer cells. Autophagy promotion by rapamycin enhanced apoptosis in bladder cancer cells, especially in AR-positive UM-UC-3 cells when AR signaling was inhibited by bicalutamide. These findings suggest that the AR antagonist bicalutamide induces autophagy and apoptosis in bladder cancer cells and may have potential in bladder cancer therapy because it upregulates autophagic flux by targeting the AR and its downstream gene ULK2.
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Affiliation(s)
- Kuiyuan Hao
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Sheng Zhao
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Di Cui
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Yu Zhang
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Chenyi Jiang
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Yifeng Jing
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Shujie Xia
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Bangmin Han
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China
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14
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Li Z, Li J, Tang N. Long noncoding RNA Malat1 is a potent autophagy inducer protecting brain microvascular endothelial cells against oxygen-glucose deprivation/reoxygenation-induced injury by sponging miR-26b and upregulating ULK2 expression. Neuroscience 2017; 354:1-10. [PMID: 28433650 DOI: 10.1016/j.neuroscience.2017.04.017] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 04/04/2017] [Accepted: 04/12/2017] [Indexed: 12/30/2022]
Abstract
Brain microvascular endothelial cell (BMEC) injury induced by ischemia-reperfusion (I/R) is the initial stage of blood-brain barrier (BBB) disruption, which results in a poor prognosis in ischemic stroke patients. Autophagy has been shown to have protective effects on BMECs against cerebral ischemic insults. However, molecular mechanism of BMEC autophagy during I/R is unclear. Long noncoding RNAs (lncRNAs) are emerging as new factors involved in cell autophagy. LncRNA Malat1 is one of the most highly upregulated I/R or OGD/R-responsive endothelial lncRNA and plays a protective role in BMECs against cerebral ischemic insults. Oxygen-glucose deprivation/reoxygenation (OGD/R) is used to mimic I/R injury in vitro. Based on these findings, we hypothesized that Malat1 might play a protective role by enhancing BMEC autophagy. We performed GFP-LC3 puncta formation, LC3 conversion, p62 expression, and cell death assays, and the results were consistent with our hypothesis that Malat1 promoted BMEC autophagy and survival under OGD/R condition. We further explored the molecular mechanisms by which Malat1 exerted regulatory effects, and found that Malat1 served as an endogenous sponge to downregulate miR-26b expression by binding directly to miR-26b. Furthermore, Malat1 overturned the inhibitory effect of miR-26b on BMEC autophagy and survival, which involved in promoting the expression of miR-26b target ULK2. Collectively, our study illuminated a new Malat1-miR-26b-ULK2 regulatory axis in which Malat1 served as a competing endogenous RNA by sponging miR-26b and upregulating ULK2 expression, thereby promoting BMEC autophagy and survival under OGD/R condition.
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Affiliation(s)
- Zhijun Li
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430010, China.
| | - Jing Li
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430010, China
| | - Na Tang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430010, China
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Blessing AM, Rajapakshe K, Reddy Bollu L, Shi Y, White MA, Pham AH, Lin C, Jonsson P, Cortes CJ, Cheung E, La Spada AR, Bast RC, Merchant FA, Coarfa C, Frigo DE. Transcriptional regulation of core autophagy and lysosomal genes by the androgen receptor promotes prostate cancer progression. Autophagy 2016; 13:506-521. [PMID: 27977328 DOI: 10.1080/15548627.2016.1268300] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AR (androgen receptor) signaling is crucial for the development and maintenance of the prostate as well as the initiation and progression of prostate cancer. Despite the AR's central role in prostate cancer progression, it is still unclear which AR-mediated processes drive the disease. Here, we identified 4 core autophagy genes: ATG4B, ATG4D, ULK1, and ULK2, in addition to the transcription factor TFEB, a master regulator of lysosomal biogenesis and function, as transcriptional targets of AR in prostate cancer. These findings were significant in light of our recent observation that androgens promoted prostate cancer cell growth in part through the induction of autophagy. Expression of these 5 genes was essential for maximal androgen-mediated autophagy and cell proliferation. In addition, expression of each of these 5 genes alone or in combination was sufficient to increase prostate cancer cell growth independent of AR activity. Further, bioinformatic analysis demonstrated that the expression of these genes correlated with disease progression in 3 separate clinical cohorts. Collectively, these findings demonstrate a functional role for increased autophagy in prostate cancer progression, provide a mechanism for how autophagy is augmented, and highlight the potential of targeting this process for the treatment of advanced prostate cancer.
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Affiliation(s)
- Alicia M Blessing
- a Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry , University of Houston , Houston , TX , USA.,b Department of Experimental Therapeutics , The University of Texas M.D. Anderson Cancer Center , Houston , TX , USA
| | - Kimal Rajapakshe
- c Department of Molecular and Cellular Biology , Baylor College of Medicine , Houston , TX , USA
| | - Lakshmi Reddy Bollu
- d Department of Clinical Cancer Prevention , The University of Texas M.D. Anderson Cancer Center , Houston , TX , USA
| | - Yan Shi
- a Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry , University of Houston , Houston , TX , USA
| | - Mark A White
- a Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry , University of Houston , Houston , TX , USA
| | - Alexander H Pham
- a Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry , University of Houston , Houston , TX , USA
| | - Chenchu Lin
- a Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry , University of Houston , Houston , TX , USA
| | - Philip Jonsson
- a Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry , University of Houston , Houston , TX , USA
| | - Constanza J Cortes
- e Departments of Cellular and Molecular Medicine , Neurosciences, and Pediatrics, Division of Biological Sciences, Institute for Genomic Medicine, Sanford Consortium for Regenerative Medicine, University of California , San Diego, La Jolla , CA , USA
| | - Edwin Cheung
- f Faculty of Health Sciences, University of Macau , Taipa , Macau , China
| | - Albert R La Spada
- e Departments of Cellular and Molecular Medicine , Neurosciences, and Pediatrics, Division of Biological Sciences, Institute for Genomic Medicine, Sanford Consortium for Regenerative Medicine, University of California , San Diego, La Jolla , CA , USA
| | - Robert C Bast
- b Department of Experimental Therapeutics , The University of Texas M.D. Anderson Cancer Center , Houston , TX , USA
| | - Fatima A Merchant
- g Department of Engineering Technology , University of Houston , Houston , TX , USA
| | - Cristian Coarfa
- c Department of Molecular and Cellular Biology , Baylor College of Medicine , Houston , TX , USA
| | - Daniel E Frigo
- a Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry , University of Houston , Houston , TX , USA.,h Genomic Medicine Program, The Houston Methodist Research Institute , Houston , TX , USA
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16
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Shukla S, Patric IRP, Patil V, Shwetha SD, Hegde AS, Chandramouli BA, Arivazhagan A, Santosh V, Somasundaram K. Methylation silencing of ULK2, an autophagy gene, is essential for astrocyte transformation and tumor growth. J Biol Chem 2014; 289:22306-18. [PMID: 24923441 DOI: 10.1074/jbc.m114.567032] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glioblastoma (GBM) is the most aggressive type of brain tumor and shows very poor prognosis. Here, using genome-wide methylation analysis, we show that G-CIMP+ and G-CIMP-subtypes enrich distinct classes of biological processes. One of the hypermethylated genes in GBM, ULK2, an upstream autophagy inducer, was found to be down-regulated in GBM. Promoter hypermethylation of ULK2 was confirmed by bisulfite sequencing. GBM and glioma cell lines had low levels of ULK2 transcripts, which could be reversed upon methylation inhibitor treatment. ULK2 promoter methylation and transcript levels showed significant negative correlation. Ectopic overexpression of ULK2-induced autophagy, which further enhanced upon nutrient starvation or temozolomide chemotherapy. ULK2 also inhibited the growth of glioma cells, which required autophagy induction as kinase mutant of ULK2 failed to induce autophagy and inhibit growth. Furthermore, ULK2 induced autophagy and inhibited growth in Ras-transformed immortalized Baby Mouse Kidney (iBMK) ATG5(+/+) but not in autophagy-deficient ATG5(-/-) cells. Growth inhibition due to ULK2 induced high levels of autophagy under starvation or chemotherapy utilized apoptotic cell death but not at low levels of autophagy. Growth inhibition by ULK2 also appears to involve catalase degradation and reactive oxygen species generation. ULK2 overexpression inhibited anchorage independent growth, inhibited astrocyte transformation in vitro and tumor growth in vivo. Of all autophagy genes, we found ULK2 and its homologue ULK1 were only down-regulated in all grades of glioma. Thus these results altogether suggest that inhibition of autophagy by ULK1/2 down-regulation is essential for glioma development.
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Affiliation(s)
- Sudhanshu Shukla
- From the Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - Irene Rosita Pia Patric
- From the Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - Vikas Patil
- From the Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - Shivayogi D Shwetha
- Neuropathology, National Institute of Mental Health and Neuro Sciences, Bangalore 560029, India
| | - Alangar S Hegde
- the Sri Satya Sai Institute of Higher Medical Sciences, Bangalore 560066, India, and
| | | | | | - Vani Santosh
- Neuropathology, National Institute of Mental Health and Neuro Sciences, Bangalore 560029, India
| | - Kumaravel Somasundaram
- From the Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India,
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17
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Ro SH, Jung CH, Hahn WS, Xu X, Kim YM, Yun YS, Park JM, Kim KH, Seo M, Ha TY, Arriaga EA, Bernlohr DA, Kim DH. Distinct functions of Ulk1 and Ulk2 in the regulation of lipid metabolism in adipocytes. Autophagy 2013; 9:2103-14. [PMID: 24135897 DOI: 10.4161/auto.26563] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
ULK1 (unc-51 like kinase 1) is a serine/threonine protein kinase that plays a key role in regulating the induction of autophagy. Recent studies using autophagy-defective mouse models, such as atg5- or atg7-deficient mice, revealed an important function of autophagy in adipocyte differentiation. Suppression of adipogenesis in autophagy-defective conditions has made it difficult to study the roles of autophagy in metabolism of differentiated adipocytes. In this study, we established autophagy defective-differentiated 3T3-L1 adipocytes, and investigated the roles of Ulk1 and its close homolog Ulk2 in lipid and glucose metabolism using the established adipocytes. Through knockdown approaches, we determined that Ulk1 and Ulk2 are important for basal and MTORC1 inhibition-induced autophagy, basal lipolysis, and mitochondrial respiration. However, unlike other autophagy genes (Atg5, Atg13, Rb1cc1/Fip200, and Becn1) Ulk1 was dispensable for adipogenesis without affecting the expression of CCAAT/enhancer binding protein ? (CEBPA) and peroxisome proliferation-activated receptor gamma (PPARG). Ulk1 knockdown reduced fatty acid oxidation and enhanced fatty acid uptake, the metabolic changes that could contribute to adipogenesis, whereas Ulk2 knockdown had opposing effects. We also found that the expression levels of insulin receptor (INSR), insulin receptor substrate 1 (IRS1), and glucose transporter 4 (SLC2A4/GLUT4) were increased in Ulk1-silenced adipocytes, which was accompanied by upregulation of insulin-stimulated glucose uptake. These results suggest that ULK1, albeit its important autophagic role, regulates lipid metabolism and glucose uptake in adipocytes distinctly from other autophagy proteins.
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Affiliation(s)
- Seung-Hyun Ro
- Department of Biochemistry, Molecular Biology and Biophysics; University of Minnesota; Minneapolis, MN USA
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Abstract
Macroautophagy, commonly referred to as autophagy, is a protein degradation pathway that occurs constitutively in cells, but can also be induced by stressors such as nutrient starvation or protein aggregation. Autophagy has been implicated in multiple disease mechanisms including neurodegeneration and cancer, with both tumor suppressive and oncogenic roles. Uncoordinated 51-like kinase 1 (ULK1) is a critical autophagy protein near the apex of the hierarchal regulatory pathway that receives signals from the master nutrient sensors MTOR and AMP-activated protein kinase (AMPK). In mammals, ULK1 has a close homolog, ULK2, although their functional distinctions have been unclear. Here, we show that ULK1 and ULK2 both function to support autophagy activation following nutrient starvation. Increased autophagy following amino acid or glucose starvation was disrupted only upon combined loss of ULK1 and ULK2 in mouse embryonic fibroblasts. Generation of PtdIns3P and recruitment of WIPI2 or ZFYVE1/DFCP1 to the phagophore following amino acid starvation was blocked by combined Ulk1/2 double knockout. Autophagy activation following glucose starvation did not involve recruitment of either WIPI1 or WIPI2 to forming autophagosomes. Consistent with a PtdIns3P-independent mechanism, glucose-dependent autophagy was resistant to wortmannin. Our findings support functional redundancy between ULK1 and ULK2 for nutrient-dependent activation of autophagy and furthermore highlight the differential pathways that respond to amino acid and glucose deprivation.
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Affiliation(s)
- Fiona McAlpine
- London Research Institute; Cancer Research UK; Secretory Pathways Laboratory; London, UK
| | - Leon E. Williamson
- Strathclyde Institute of Pharmacy and Biomedical Sciences; RICAS Group; University of Strathclyde; Glasgow, Scotland
| | - Sharon A. Tooze
- London Research Institute; Cancer Research UK; Secretory Pathways Laboratory; London, UK
| | - Edmond Y.W. Chan
- Strathclyde Institute of Pharmacy and Biomedical Sciences; RICAS Group; University of Strathclyde; Glasgow, Scotland
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