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Da Graça J, Delevoye C, Morel E. Morphodynamical adaptation of the endolysosomal system to stress. FEBS J 2024. [PMID: 38706230 DOI: 10.1111/febs.17154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 03/28/2024] [Accepted: 04/25/2024] [Indexed: 05/07/2024]
Abstract
In eukaryotes, the spatiotemporal control of endolysosomal organelles is central to the maintenance of homeostasis. By providing an interface between the cytoplasm and external environment, the endolysosomal system is placed at the forefront of the response to a wide range of stresses faced by cells. Endosomes are equipped with a dedicated set of membrane-associated proteins that ensure endosomal functions as well as crosstalk with the secretory or the autophagy pathways. Morphodynamical processes operate through local spatialization of subdomains, enabling specific remodeling and membrane contact capabilities. Consequently, the plasticity of endolysosomal organelles can be considered a robust and flexible tool exploited by cells to cope with homeostatic deviations. In this review, we provide insights into how the cellular responses to various stresses (osmotic, UV, nutrient deprivation, or pathogen infections) rely on the adaptation of the endolysosomal system morphodynamics.
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Affiliation(s)
- Juliane Da Graça
- Université Paris Cité, INSERM UMR-S1151, CNRS UMR-S8253, Institut Necker Enfants Malades, France
| | - Cédric Delevoye
- Université Paris Cité, INSERM UMR-S1151, CNRS UMR-S8253, Institut Necker Enfants Malades, France
- Institut Curie, PSL Research University, CNRS, UMR144, Structure and Membrane Compartments, Paris, France
| | - Etienne Morel
- Université Paris Cité, INSERM UMR-S1151, CNRS UMR-S8253, Institut Necker Enfants Malades, France
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2
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Miyano T, Suzuki A, Sakamoto N. Actin cytoskeletal reorganization is involved in hyperosmotic stress-induced autophagy in tubular epithelial cells. Biochem Biophys Res Commun 2023; 663:1-7. [PMID: 37116392 DOI: 10.1016/j.bbrc.2023.04.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 04/14/2023] [Accepted: 04/20/2023] [Indexed: 04/30/2023]
Abstract
Tubular epithelial cells are routinely exposed to severe changes in osmolarity. Although the autophagic activity of cells is an indispensable process to maintain cellular homeostasis and respond to stressors, the effect of hyperosmotic stress on autophagic activity in tubular epithelial cells remains unknown. The aim of this study was to determine the effect of hyperosmotic stress on autophagy in rat kidney tubular epithelial cells focusing on the role of actin and microtubule cytoskeletons. Normal rat kidney (NRK)-52E cells exposed to mannitol-induced hyperosmotic stress. As a result, NRK-52E cells showed elevated protein levels of the autophagosome marker LC3-II, indicating enhancement of the autophagic flux. Hyperosmotic stress also transiently decreased cell volume and caused the reorganization of actin and microtubule cytoskeletal structures in NRK-52E cells. The inhibition of the actin cytoskeleton reorganization by cytochalasin D impaired the increase in the levels of LC3-II; however, disassembly of the microtubules following treatment with nocodazole did not affect the increase. These results indicate that hyperosmotic stress can induce autophagy mediated by the reorganization of the actin cytoskeleton in tubular epithelial cells.
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Affiliation(s)
- Takashi Miyano
- Department of Mechanical Systems Engineering, Graduate School of Systems Design, Tokyo Metropolitan University, Tokyo, Japan.
| | - Atsushi Suzuki
- Department of Mechanical Systems Engineering, Graduate School of Systems Design, Tokyo Metropolitan University, Tokyo, Japan
| | - Naoya Sakamoto
- Department of Mechanical Systems Engineering, Graduate School of Systems Design, Tokyo Metropolitan University, Tokyo, Japan.
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3
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McCormick JJ, King KE, Rutherford MM, Meade RD, Notley SR, Akerman AP, Dokladny K, Kenny GP. Effect of extracellular hyperosmolality during normothermia and hyperthermia on the autophagic response in peripheral blood mononuclear cells from young men. J Appl Physiol (1985) 2022; 132:995-1004. [PMID: 35238651 DOI: 10.1152/japplphysiol.00661.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Heat-stress induced dehydration is associated with extracellular hyperosmolality. To counteract the associated stress, cells employ cytoprotective mechanisms, including autophagy, however, the autophagic response to hyperosmotic stress has yet to be evaluated in humans. Thus, we investigated autophagy and associated cellular stress pathways (the heat shock response [HSR], apoptosis, and the acute inflammatory response) to isosmotic and hyperosmotic conditions with and without hyperthermia in twelve young men (mean [SD]; 25 [5] years). Participants received a 90-min intravenous infusion of either isosmotic (ISO; 0.9% NaCl; serum osmolality of 293 [4] mOsm/kg) or hyperosmotic (HYP; 3.0% NaCl; 300 [6] mOsm/kg) saline, followed by passive whole-body heating using a water perfused suit to increase esophageal temperature by ~0.8⁰C. Peripheral blood mononuclear cells were harvested at baseline (pre-infusion), post-infusion, and after heating, and changes in protein content were analyzed via Western blotting. Post-infusion, the LC3-II/I ratio was higher in HYP compared to ISO infusion (p<0.001), although no other protein changes were observed (all p>0.050). Following passive heating, autophagy increased in HYP, as demonstrated by an increase in LC3-II from baseline (p=0.004) and an elevated LC3-II/I ratio compared to ISO (p=0.035), and a decrease in p62 when compared to the ISO condition (p=0.019). This was accompanied by an elevation in cleaved caspase-3 following heating in the HYP condition (p<0.010), however, the HSR and acute inflammatory response did not change under any condition (all p>0.050). Taken together, our findings indicate that serum hyperosmolality induces autophagy and apoptotic signaling during mild hyperthermia with minimal autophagic activation during normothermia.
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Affiliation(s)
- James J McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Maura M Rutherford
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada.,Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, United States
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Ashley P Akerman
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Karol Dokladny
- Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico, United States
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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4
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Protective effect and mechanism of betaine against hyperosmotic stress in porcine intestinal epithelium. J Funct Foods 2021. [DOI: 10.1016/j.jff.2021.104838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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5
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Liang D, Lin WJ, Ren M, Qiu J, Yang C, Wang X, Li N, Zeng T, Sun K, You L, Yan L, Wang W. m 6A reader YTHDC1 modulates autophagy by targeting SQSTM1 in diabetic skin. Autophagy 2021; 18:1318-1337. [PMID: 34657574 PMCID: PMC9225222 DOI: 10.1080/15548627.2021.1974175] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Dysregulation of macroautophagy/autophagy contributes to the delay of wound healing in diabetic skin. N6-methyladenosine (m6A) RNA modification is known to play a critical role in regulating autophagy. In this study, it was found that SQSTM1/p62 (sequestosome 1), an autophagy receptor, was significantly downregulated in two human keratinocyte cells lines with short-term high-glucose treatment, as well as in the epidermis of diabetic patients and a db/db mouse model with long-term hyperglycemia. Knockdown of SQSTM1 led to the impairment of autophagic flux, which was consistent with the results of high-glucose treatment in keratinocytes. Moreover, the m6A reader protein YTHDC1 (YTH domain containing 1), which interacted with SQSTM1 mRNA, was downregulated in keratinocytes under both the acute and chronic effects of hyperglycemia. Knockdown of YTHDC1 affected biological functions of keratinocytes, which included increased apoptosis rates and impaired wound-healing capacity. In addition, knockdown of endogenous YTHDC1 resulted in a blockade of autophagic flux in keratinocytes, while overexpression of YTHDC1 rescued the blockade of autophagic flux induced by high glucose. In vivo, knockdown of endogenous Ythdc1 or Sqstm1 inhibited autophagy in the epidermis and delayed wound healing. Interestingly, we found that a decrease of YTHDC1 drove SQSTM1 mRNA degradation in the nucleus. Furthermore, the results revealed that YTHDC1 interacted and cooperated with ELAVL1/HuR (ELAV like RNA binding protein 1) in modulating the expression of SQSTM1. Collectively, this study uncovered a previously unrecognized function for YTHDC1 in modulating autophagy via regulating the stability of SQSTM1 nuclear mRNA in diabetic keratinocytes. Abbreviations: ACTB: actin beta; AGEs: glycation end products; AL: autolysosome; AP: autophagosome; ATG: autophagy related; AKT: AKT serine/threonine kinase; ANOVA: analysis of variance; BECN1: beclin 1; Co-IP: co-immunoprecipitation; DEGs: differentially expressed genes; DM: diabetes mellitus; ELAVL1: ELAV like RNA binding protein 1; FTO: FTO alpha-ketoglutarate dependent dioxygenase; G: glucose; HaCaT: human keratinocyte; GO: Gene Ontology; GSEA: Gene Set Enrichment Analysis; HE: hematoxylin-eosin; IHC: immunohistochemical; IRS: immunoreactive score; KEAP1: kelch like ECH associated protein 1; KEGG: Kyoto Encyclopedia of Genes and Genomes; m6A: N6-methyladenosine; M: mannitol; MANOVA: multivariate analysis of variance; MAP1LC3: microtubule associated protein 1 light chain 3; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MeRIP: methylated RNA immunoprecipitation; METTL3: methyltransferase 3, N6-adenosine-methytransferase complex catalytic subunit; MTOR: mechanistic target of rapamycin kinase; MTORC1: mechanistic target of rapamycin complex 1; NBR1: NBR1 autophagy cargo receptor; NFE2L2: nuclear factor, erythroid 2 like 2; NG: normal glucose; NHEK: normal human epithelial keratinocyte; OE: overexpressing; p-: phospho-; PI: propidium iodide; PPIN: Protein-Protein Interaction Network; RBPs: RNA binding proteins; RIP: RNA immunoprecipitation; RNA-seq: RNA-sequence; RNU6–1: RNA, U6 small nuclear 1; ROS: reactive oxygen species; siRNAs: small interfering RNAs; SQSTM1: sequestosome 1; SRSF: serine and arginine rich splicing factor; T2DM: type 2 diabetes mellitus; TEM: transmission electron microscopy; TUBB: tubulin beta class I; WT: wild-type; YTHDC1: YTH domain containing 1.
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Affiliation(s)
- Diefei Liang
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Wei-Jye Lin
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Medical Research Center of Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Meng Ren
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Junxiong Qiu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Department of Cardiovascular Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Chuan Yang
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Xiaoyi Wang
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Na Li
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Tingting Zeng
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Kan Sun
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Lili You
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Li Yan
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Wei Wang
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
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Ouyang Y, Wu Q, Li J, Sun S, Sun S. S-adenosylmethionine: A metabolite critical to the regulation of autophagy. Cell Prolif 2020; 53:e12891. [PMID: 33030764 PMCID: PMC7653241 DOI: 10.1111/cpr.12891] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/21/2020] [Accepted: 08/04/2020] [Indexed: 02/06/2023] Open
Abstract
Autophagy is a mechanism that enables cells to maintain cellular homeostasis by removing damaged materials and mobilizing energy reserves in conditions of starvation. Although nutrient availability strongly impacts the process of autophagy, the specific metabolites that regulate autophagic responses have not yet been determined. Recent results indicate that S-adenosylmethionine (SAM) represents a critical inhibitor of methionine starvation-induced autophagy. SAM is primarily involved in four key metabolic pathways: transmethylation, transsulphuration, polyamine synthesis and 5'-deoxyadenosyl 5'-radical-mediated biochemical transformations. SAM is the sole methyl group donor involved in the methylation of DNA, RNA and histones, modulating the autophagic process by mediating epigenetic effects. Moreover, the metabolites of SAM, such as homocysteine, glutathione, decarboxylated SAM and spermidine, also exert important influences on the regulation of autophagy. From our perspective, nuclear-cytosolic SAM is a conserved metabolic inhibitor that connects cellular metabolic status and the regulation of autophagy. In the future, SAM might be a new target of autophagy regulators and be widely used in the treatment of various diseases.
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Affiliation(s)
- Yang Ouyang
- Department of Breast and Thyroid SurgeryRenmin Hospital of Wuhan UniversityWuhanChina
| | - Qi Wu
- Department of Breast and Thyroid SurgeryRenmin Hospital of Wuhan UniversityWuhanChina
| | - Juanjuan Li
- Department of Breast and Thyroid SurgeryRenmin Hospital of Wuhan UniversityWuhanChina
| | - Si Sun
- Department of Clinical LaboratoryRenmin Hospital of Wuhan UniversityWuhanChina
| | - Shengrong Sun
- Department of Breast and Thyroid SurgeryRenmin Hospital of Wuhan UniversityWuhanChina
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7
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Tan YL, Ho HK. Hypothermia Advocates Functional Mitochondria and Alleviates Oxidative Stress to Combat Acetaminophen-Induced Hepatotoxicity. Cells 2020; 9:cells9112354. [PMID: 33114500 PMCID: PMC7693152 DOI: 10.3390/cells9112354] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 10/21/2020] [Accepted: 10/21/2020] [Indexed: 12/16/2022] Open
Abstract
For years, moderate hypothermia (32 °C) has been proposed as an unorthodox therapy for liver injuries, with proven hepatoprotective potential. Yet, limited mechanistic understanding has largely denied its acceptance over conventional pharmaceuticals for hepatoprotection. Today, facing a high prevalence of acetaminophen-induced liver injury (AILI) which accounts for the highest incidence of acute liver failure, hypothermia was evaluated as a potential therapy to combat AILI. For which, transforming growth factor-α transgenic mouse hepatocytes (TAMH) were subjected to concomitant 5 mM acetaminophen toxicity and moderate hypothermic conditioning for 24 h. Thereafter, its impact on mitophagy, mitochondrial biogenesis, glutathione homeostasis and c-Jun N-terminal kinase (JNK) signaling pathways were investigated. In the presence of AILI, hypothermia displayed simultaneous mitophagy and mitochondrial biogenesis to conserve functional mitochondria. Furthermore, antioxidant response was apparent with higher glutathione recycling and repressed JNK activation. These effects were, however, unremarkable with hypothermia alone without liver injury. This may suggest an adaptive response of hypothermia only to the injured sites, rendering it favorable as a potential targeted therapy. In fact, its cytoprotective effects were displayed in other DILI of similar pathology as acetaminophen i.e., valproate- and diclofenac-induced liver injury and this further corroborates the mechanistic findings of hypothermic actions on AILI.
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Affiliation(s)
- Yeong Lan Tan
- Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore 117543, Singapore;
- NUS Graduate School for Integrative Sciences & Engineering, Centre for Life Sciences, National University of Singapore, Singapore 119077, Singapore
| | - Han Kiat Ho
- Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore 117543, Singapore;
- NUS Graduate School for Integrative Sciences & Engineering, Centre for Life Sciences, National University of Singapore, Singapore 119077, Singapore
- Correspondence:
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López-Hernández T, Haucke V, Maritzen T. Endocytosis in the adaptation to cellular stress. Cell Stress 2020; 4:230-247. [PMID: 33024932 PMCID: PMC7520666 DOI: 10.15698/cst2020.10.232] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/24/2020] [Accepted: 07/29/2020] [Indexed: 12/11/2022] Open
Abstract
Cellular life is challenged by a multitude of stress conditions, triggered for example by alterations in osmolarity, oxygen or nutrient supply. Hence, cells have developed sophisticated stress responses to cope with these challenges. Some of these stress programs such as the heat shock response are understood in great detail, while other aspects remain largely elusive including potential stress-dependent adaptations of the plasma membrane proteome. The plasma membrane is not only the first point of encounter for many types of environmental stress, but given the diversity of receptor proteins and their associated molecules also represents the site at which many cellular signal cascades originate. Since these signaling pathways affect virtually all aspects of cellular life, changes in the plasma membrane proteome appear ideally suited to contribute to the cellular adaptation to stress. The most rapid means to alter the cell surface proteome in response to stress is by alterations in endocytosis. Changes in the overall endocytic flux or in the endocytic regulation of select proteins conceivably can help to counteract adverse environmental conditions. In this review we summarize recent data regarding stress-induced changes in endocytosis and discuss how these changes might contribute to the cellular adaptation to stress in different systems. Future studies will be needed to uncover the underlying mechanisms in detail and to arrive at a coherent picture.
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Affiliation(s)
- Tania López-Hernández
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
- Freie Universität Berlin, Faculty of Biology, Chemistry, Pharmacy, 14195 Berlin, Germany
| | - Tanja Maritzen
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
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9
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Endocytic regulation of cellular ion homeostasis controls lysosome biogenesis. Nat Cell Biol 2020; 22:815-827. [PMID: 32601373 DOI: 10.1038/s41556-020-0535-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 05/21/2020] [Indexed: 12/24/2022]
Abstract
Lysosomes serve as cellular degradation and signalling centres that coordinate metabolism in response to intracellular cues and extracellular signals. Lysosomal capacity is adapted to cellular needs by transcription factors, such as TFEB and TFE3, which activate the expression of lysosomal and autophagy genes. Nuclear translocation and activation of TFEB are induced by a variety of conditions such as starvation, lysosome stress and lysosomal storage disorders. How these various cues are integrated remains incompletely understood. Here, we describe a pathway initiated at the plasma membrane that controls lysosome biogenesis via the endocytic regulation of intracellular ion homeostasis. This pathway is based on the exo-endocytosis of NHE7, a Na+/H+ exchanger mutated in X-linked intellectual disability, and serves to control intracellular ion homeostasis and thereby Ca2+/calcineurin-mediated activation of TFEB and downstream lysosome biogenesis in response to osmotic stress to promote the turnover of toxic proteins and cell survival.
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10
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Singha B, Laski J, Ramos Valdés Y, Liu E, DiMattia GE, Shepherd TG. Inhibiting ULK1 kinase decreases autophagy and cell viability in high-grade serous ovarian cancer spheroids. Am J Cancer Res 2020; 10:1384-1399. [PMID: 32509386 PMCID: PMC7269771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 02/27/2020] [Indexed: 06/11/2023] Open
Abstract
Metastasis in high-grade serous ovarian cancer (HGSOC) occurs through an unconventional route that involves exfoliation of cancer cells from primary tumors and peritoneal dissemination via multicellular clusters or spheroids. Previously, we demonstrated autophagy induction in HGSOC spheroids grown in vitro and in spheroids collected from ovarian cancer patient ascites; thus, we speculate that autophagy may contribute to spheroid cell survival and overall disease progression. Hence, in this study we sought to evaluate whether ULK1 (unc-51-like kinase-1), a serine-threonine kinase critical for stress-induced autophagy, is important for autophagy regulation in HGSOC spheroids. We demonstrate that HGSOC spheroids have increased ULK1 protein expression that parallels autophagy activation. ULK1 knockdown increased p62 accumulation and decreased LC3-II/I ratio in HGSOC spheroids. In addition, knocking down ATG13, a protein that regulates ULK1 activity via complex formation, phenocopied our ULK1 knockdown results. HGSOC spheroids were blocked in autophagic flux due to ULK1 and ATG13 knockdown as determined by an mCherry-eGFP-LC3B fluorescence reporter. These observations were recapitulated when HGSOC spheroids were treated with an ULK1 kinase inhibitor, MRT68921. Autophagy regulation in normal human fallopian tube epithelial FT190 cells, however, may bypass ULK1, since MRT68921 reduced viability in HGSOC spheroids but not in FT190 cells. Interestingly, ULK1 mRNA expression is negatively correlated with patient survival among stage III and stage IV serous ovarian cancer patients. As we observed using established HGSOC cell lines, cultured spheroids using our new, patient-derived HGSOC cells were also sensitive to ULK1 inhibition and demonstrated reduced cell viability to MRT68921 treatment. These results demonstrate the importance of ULK1 for autophagy induction in HGSOC spheroids and therefore justifies further evaluation of MRT68921, and other novel ULK1 inhibitors, as potential therapeutics against metastatic HGSOC.
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Affiliation(s)
- Bipradeb Singha
- The Mary & John Knight Translational Ovarian Cancer Research Unit, London Regional Cancer ProgramLondon, Ontario, Canada
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, Western UniversityLondon, Ontario, Canada
| | - Jeremi Laski
- The Mary & John Knight Translational Ovarian Cancer Research Unit, London Regional Cancer ProgramLondon, Ontario, Canada
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, Western UniversityLondon, Ontario, Canada
| | - Yudith Ramos Valdés
- The Mary & John Knight Translational Ovarian Cancer Research Unit, London Regional Cancer ProgramLondon, Ontario, Canada
| | - Elaine Liu
- The Mary & John Knight Translational Ovarian Cancer Research Unit, London Regional Cancer ProgramLondon, Ontario, Canada
| | - Gabriel E DiMattia
- The Mary & John Knight Translational Ovarian Cancer Research Unit, London Regional Cancer ProgramLondon, Ontario, Canada
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western UniversityLondon, Ontario, Canada
- Department of Oncology, Schulich School of Medicine and Dentistry, The University of Western OntarioLondon, Ontario, Canada
| | - Trevor G Shepherd
- The Mary & John Knight Translational Ovarian Cancer Research Unit, London Regional Cancer ProgramLondon, Ontario, Canada
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, Western UniversityLondon, Ontario, Canada
- Department of Obstetrics & Gynaecology, Schulich School of Medicine and Dentistry, Western UniversityLondon, Ontario, Canada
- Department of Oncology, Schulich School of Medicine and Dentistry, The University of Western OntarioLondon, Ontario, Canada
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