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Williamson CD, Guardia CM, De Pace R, Bonifacino JS, Saric A. Measurement of Lysosome Positioning by Shell Analysis and Line Scan. Methods Mol Biol 2022; 2473:285-306. [PMID: 35819772 PMCID: PMC11072972 DOI: 10.1007/978-1-0716-2209-4_19] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Lysosomes are membrane-bound organelles that degrade diverse biomolecules and regulate a multitude of other essential processes including cell growth and metabolism, signaling, plasma membrane repair and infection. Such diverse functions of lysosomes are highly coordinated in space and time and are therefore tightly coupled to the directional transport of the organelles within the cytoplasm. Thus, robust quantitative assessments of lysosome positioning within the cell provide a valuable tool for researchers interested in understanding these multifunctional organelles. Here, we present point-by-point methodology to measure lysosome positioning by two straight forward and widely used techniques: shell analysis and line scan.
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Affiliation(s)
- Chad D Williamson
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Carlos M Guardia
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Raffaella De Pace
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Juan S Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Amra Saric
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.
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Saric A, Freeman SA, Williamson CD, Jarnik M, Guardia CM, Fernandopulle MS, Gershlick DC, Bonifacino JS. SNX19 restricts endolysosome motility through contacts with the endoplasmic reticulum. Nat Commun 2021; 12:4552. [PMID: 34315878 PMCID: PMC8316374 DOI: 10.1038/s41467-021-24709-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [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: 07/07/2020] [Accepted: 06/24/2021] [Indexed: 12/12/2022] Open
Abstract
The ability of endolysosomal organelles to move within the cytoplasm is essential for the performance of their functions. Long-range movement involves coupling of the endolysosomes to motor proteins that carry them along microtubule tracks. This movement is influenced by interactions with other organelles, but the mechanisms involved are incompletely understood. Herein we show that the sorting nexin SNX19 tethers endolysosomes to the endoplasmic reticulum (ER), decreasing their motility and contributing to their concentration in the perinuclear area of the cell. Tethering depends on two N-terminal transmembrane domains that anchor SNX19 to the ER, and a PX domain that binds to phosphatidylinositol 3-phosphate on the endolysosomal membrane. Two other domains named PXA and PXC negatively regulate the interaction of SNX19 with endolysosomes. These studies thus identify a mechanism for controlling the motility and positioning of endolysosomes that involves tethering to the ER by a sorting nexin.
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Affiliation(s)
- Amra Saric
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Chad D Williamson
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Michal Jarnik
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Carlos M Guardia
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Michael S Fernandopulle
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - David C Gershlick
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Juan S Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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Abstract
Eukaryotic cells employ diverse uptake mechanisms depending on their specialized functions. While such mechanisms vary widely in their defining criteria: scale, molecular machinery utilized, cargo selection, and cargo destination, to name a few, they all result in the internalization of extracellular solutes and fluid into membrane-bound endosomes. Upon scission from the plasma membrane, this compartment is immediately subjected to extensive remodeling which involves tubulation and vesiculation/budding of the limiting endomembrane. This is followed by a maturation process involving concomitant retrograde transport by microtubule-based motors and graded fusion with late endosomes and lysosomes, organelles that support the degradation of the internalized content. Here we review an important determinant for sorting and trafficking in early endosomes and in lysosomes; the control of tension on the endomembrane. Remodeling of endomembranes is opposed by high tension (caused by high hydrostatic pressure) and supported by the relief of tension. We describe how the timely and coordinated efflux of major solutes along the endocytic pathway affords the cell control over such tension. The channels and transporters that expel the smallest components of the ingested medium from the early endocytic fluid are described in detail as these systems are thought to enable endomembrane deformation by curvature-sensing/generating coat proteins. We also review similar considerations for the lysosome where resident hydrolases liberate building blocks from luminal macromolecules and transporters flux these organic solutes to orchestrate trafficking events. How the cell directs organellar trafficking based on the luminal contents of organelles of the endocytic pathway is not well-understood, however, we propose that the control over membrane tension by solute transport constitutes one means for this to ensue.
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Affiliation(s)
- Amra Saric
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Center for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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Imbert PRC, Saric A, Pedram K, Bertozzi CR, Grinstein S, Freeman SA. An Acquired and Endogenous Glycocalyx Forms a Bidirectional "Don't Eat" and "Don't Eat Me" Barrier to Phagocytosis. Curr Biol 2020; 31:77-89.e5. [PMID: 33096038 DOI: 10.1016/j.cub.2020.09.082] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 08/28/2020] [Accepted: 09/28/2020] [Indexed: 12/11/2022]
Abstract
Macrophages continuously survey their environment in search of pathogens or apoptotic corpses or debris. Targets intended for clearance expose ligands that initiate their phagocytosis ("eat me" signals), while others avoid phagocytosis by displaying inhibitory ligands ("don't eat me" signals). We report that such ligands can be obscured by the glycosaminoglycans and glycoproteins that coat pathogenic as well as malignant phagocytic targets. In addition, a reciprocal barrier of self-synthesized or acquired glycocalyx components on the macrophage surface shrouds phagocytic receptors, curtailing their ability to engage particles. The coating layers of macrophages and their targets hinder phagocytosis by both steric and electrostatic means. Their removal by enzymatic means is shown to markedly enhance phagocytic efficiency. In particular, we show that the removal of mucins, which are overexpressed in cancer cells, facilitates their clearance. These results shed light on the physical barriers that modulate phagocytosis, which have been heretofore underappreciated. VIDEO ABSTRACT.
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Affiliation(s)
- Paul R C Imbert
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON M5G 0A4, Canada
| | - Amra Saric
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kayvon Pedram
- Department of Chemistry and Stanford ChEM-H, Stanford University, Stanford, CA 94305, USA
| | - Carolyn R Bertozzi
- Department of Chemistry and Stanford ChEM-H, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford, CA 94305, USA
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, Canada; Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
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Freeman SA, Uderhardt S, Saric A, Collins RF, Buckley CM, Mylvaganam S, Boroumand P, Plumb J, Germain RN, Ren D, Grinstein S. Lipid-gated monovalent ion fluxes regulate endocytic traffic and support immune surveillance. Science 2019; 367:301-305. [PMID: 31806695 DOI: 10.1126/science.aaw9544] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 10/08/2019] [Accepted: 11/25/2019] [Indexed: 12/21/2022]
Abstract
Despite ongoing (macro)pinocytosis of extracellular fluid, the volume of the endocytic pathway remains unchanged. To investigate the underlying mechanism, we used high-resolution video imaging to analyze the fate of macropinosomes formed by macrophages in vitro and in situ. Na+, the primary cationic osmolyte internalized, exited endocytic vacuoles via two-pore channels, accompanied by parallel efflux of Cl- and osmotically coupled water. The resulting shrinkage caused crenation of the membrane, which fostered recruitment of curvature-sensing proteins. These proteins stabilized tubules and promoted their elongation, driving vacuolar remodeling, receptor recycling, and resolution of the organelles. Failure to resolve internalized fluid impairs the tissue surveillance activity of resident macrophages. Thus, osmotically driven increases in the surface-to-volume ratio of endomembranes promote traffic between compartments and help to ensure tissue homeostasis.
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Affiliation(s)
- Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.
| | - Stefan Uderhardt
- Lymphocyte Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.,Department of Internal Medicine 3 - Rheumatology and Immunology, Universitätsklinikum Erlangen and Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Amra Saric
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Richard F Collins
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Catherine M Buckley
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.,Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Sivakami Mylvaganam
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Parastoo Boroumand
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Jonathan Plumb
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Ronald N Germain
- Lymphocyte Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Dejian Ren
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada. .,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
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Hipolito VEB, Diaz JA, Tandoc KV, Oertlin C, Ristau J, Chauhan N, Saric A, Mclaughlan S, Larsson O, Topisirovic I, Botelho RJ. Enhanced translation expands the endo-lysosome size and promotes antigen presentation during phagocyte activation. PLoS Biol 2019; 17:e3000535. [PMID: 31800587 PMCID: PMC6913987 DOI: 10.1371/journal.pbio.3000535] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 12/16/2019] [Accepted: 11/04/2019] [Indexed: 02/06/2023] Open
Abstract
The mechanisms that govern organelle adaptation and remodelling remain poorly defined. The endo-lysosomal system degrades cargo from various routes, including endocytosis, phagocytosis, and autophagy. For phagocytes, endosomes and lysosomes (endo-lysosomes) are kingpin organelles because they are essential to kill pathogens and process and present antigens. During phagocyte activation, endo-lysosomes undergo a morphological transformation, going from a collection of dozens of globular structures to a tubular network in a process that requires the phosphatidylinositol-3-kinase-AKT-mechanistic target of rapamycin (mTOR) signalling pathway. Here, we show that the endo-lysosomal system undergoes an expansion in volume and holding capacity during phagocyte activation within 2 h of lipopolysaccharides (LPS) stimulation. Endo-lysosomal expansion was paralleled by an increase in lysosomal protein levels, but this was unexpectedly largely independent of the transcription factor EB (TFEB) and transcription factor E3 (TFE3), which are known to scale up lysosome biogenesis. Instead, we demonstrate a hitherto unappreciated mechanism of acute organelle expansion via mTOR Complex 1 (mTORC1)-dependent increase in translation, which appears to be mediated by both S6Ks and 4E-BPs. Moreover, we show that stimulation of RAW 264.7 macrophage cell line with LPS alters translation of a subset but not all of mRNAs encoding endo-lysosomal proteins, thereby suggesting that endo-lysosome expansion is accompanied by functional remodelling. Importantly, mTORC1-dependent increase in translation activity was necessary for efficient and rapid antigen presentation by dendritic cells. Collectively, we identified a previously unknown and functionally relevant mechanism for endo-lysosome expansion that relies on mTORC1-dependent translation to stimulate endo-lysosome biogenesis in response to an infection signal. Activation of phagocytes rapidly expands the endo-lysosomal system and promotes antigen presentation. Endo-lysosome expansion was driven by mTORC1-dependent enhanced translation, revealing regulated translation as a mechanism to remodel membrane organelles in response to external signals and stresses.
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Affiliation(s)
- Victoria E. B. Hipolito
- Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Jacqueline A. Diaz
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Kristofferson V. Tandoc
- Department of Experimental Medicine, McGill University, Montréal, Quebec, Canada
- The Lady Davis Institute, Jewish General Hospital, Montréal, Quebec, Canada
| | - Christian Oertlin
- Department of Oncology-Pathology, Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Johannes Ristau
- Department of Oncology-Pathology, Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Neha Chauhan
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Amra Saric
- Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Shannon Mclaughlan
- The Lady Davis Institute, Jewish General Hospital, Montréal, Quebec, Canada
| | - Ola Larsson
- Department of Oncology-Pathology, Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Ivan Topisirovic
- Department of Experimental Medicine, McGill University, Montréal, Quebec, Canada
- The Lady Davis Institute, Jewish General Hospital, Montréal, Quebec, Canada
- Gerald Bronfman Department of Oncology, McGill University, Montréal, Quebec, Canada
- Department of Biochemistry, McGill University, Montréal, Quebec, Canada
| | - Roberto J. Botelho
- Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
- * E-mail:
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Ismail F, Boulias C, Phadke C, Dagher J, Ethans K, Khan O, Kleiner G, Pi Shan RL, Liem N, Lo A, McNeil S, Mills P, Petitclerc M, Reebye R, Ryan W, Saric A, Satkunam L, Sharma S, Sirois G, Stacey P, Wein T, Winston P. Early Botulinum Toxin Injections for Spasticity Management Post-stroke: A Delphi-based Canadian Consensus. Arch Phys Med Rehabil 2019. [DOI: 10.1016/j.apmr.2019.10.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Sharma G, Guardia CM, Roy A, Vassilev A, Saric A, Griner LN, Marugan J, Ferrer M, Bonifacino JS, DePamphilis ML. A family of PIKFYVE inhibitors with therapeutic potential against autophagy-dependent cancer cells disrupt multiple events in lysosome homeostasis. Autophagy 2019; 15:1694-1718. [PMID: 30806145 DOI: 10.1080/15548627.2019.1586257] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [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: 12/18/2022] Open
Abstract
High-throughput screening identified 5 chemical analogs (termed the WX8-family) that disrupted 3 events in lysosome homeostasis: (1) lysosome fission via tubulation without preventing homotypic lysosome fusion; (2) trafficking of molecules into lysosomes without altering lysosomal acidity, and (3) heterotypic fusion between lysosomes and autophagosomes. Remarkably, these compounds did not prevent homotypic fusion between lysosomes, despite the fact that homotypic fusion required some of the same machinery essential for heterotypic fusion. These effects varied 400-fold among WX8-family members, were time and concentration dependent, reversible, and resulted primarily from their ability to bind specifically to the PIKFYVE phosphoinositide kinase. The ability of the WX8-family to prevent lysosomes from participating in macroautophagy/autophagy suggested they have therapeutic potential in treating autophagy-dependent diseases. In fact, the most potent family member (WX8) was 100-times more lethal to 'autophagy-addicted' melanoma A375 cells than the lysosomal inhibitors hydroxychloroquine and chloroquine. In contrast, cells that were insensitive to hydroxychloroquine and chloroquine were also insensitive to WX8. Therefore, the WX8-family of PIKFYVE inhibitors provides a basis for developing drugs that could selectively kill autophagy-dependent cancer cells, as well as increasing the effectiveness of established anti-cancer therapies through combinatorial treatments. Abbreviations: ACTB: actin beta; Baf: bafilomycin A1; BECN1: beclin 1; BODIPY: boron-dipyrromethene; BORC: BLOC-1 related complex; BRAF: B-Raf proto-oncogene, serine/threonine kinase; BSA: bovine serum albumin; CTSD: cathepsin D; CQ: chloroquine; DNA: deoxyribonucleic acid; EC50: half maximal effective concentration; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; HCQ: hydroxychloroquine; HOPS complex: homotypic fusion and protein sorting complex; Kd: equilibrium binding constant; IC50: half maximal inhibitory concentration; KO: knockout; LAMP1: lysosomal associated membrane protein 1; MAP1LC3A: microtubule associated protein 1 light chain 3 alpha; MES: 2-(N-morpholino)ethanesulphonic acid; MTOR: mechanistic target of rapamycin kinase; μM: micromolar; NDF: 3-methylbenzaldehyde (2,6-dimorpholin-4-ylpyrimidin-4-yl)hydrazine;NEM: N-ethylmaleimide; NSF: N-ethylmaleimide sensitive factor; PBS: phosphate-buffered saline; PIKFYVE: phosphoinositide kinase, FYVE-type zinc finger containing; PIP4K2C: phosphatidylinositol-5-phosphate 4-kinase type 2 gamma; PtdIns3P: phosphatidylinositol 3-phosphate; PtdIns(3,5)P2: phosphatidylinositol 3,5-biphosphate; RFP: red fluorescent protein; RPS6: ribosomal protein S6; RPS6KB1: ribosomal protein S6 kinase B1; SQSTM1: sequestosome 1; TWEEN 20: polysorbate 20; V-ATPase: vacuolar-type H+-translocating ATPase; VPS39: VPS39 subunit of HOPS complex; VPS41: VPS41 subunit of HOPS complex; WWL: benzaldehyde [2,6-di(4-morpholinyl)-4-pyrimidinyl]hydrazone; WX8: 1H-indole-3-carbaldehyde [4-anilino-6-(4-morpholinyl)-1,3,5-triazin-2-yl]hydrazine; XBA: N-(3-chloro-4-fluorophenyl)-4,6-dimorpholino-1,3,5-triazin-2-amine hydrochloride; XB6: N-(4-ethylphenyl)-4,6-dimorpholino-1,3,5-triazin-2-amine hydrochloride.
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Affiliation(s)
- Gaurav Sharma
- Division of Developmental Biology, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Carlos M Guardia
- Cell Biology and Neurobiology Branch, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Ajit Roy
- Division of Developmental Biology, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Alex Vassilev
- Division of Developmental Biology, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Amra Saric
- Cell Biology and Neurobiology Branch, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Lori N Griner
- Division of Developmental Biology, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Juan Marugan
- Division of Pre-Clinical Innovation, NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health , Rockville , MD , USA
| | - Marc Ferrer
- Division of Pre-Clinical Innovation, NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health , Rockville , MD , USA
| | - Juan S Bonifacino
- Cell Biology and Neurobiology Branch, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Melvin L DePamphilis
- Division of Developmental Biology, National Institute of Child Health & Human Development, National Institutes of Health , Bethesda , MD , USA
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Hipolito VEB, Diaz JA, Tandoc KV, Saric A, Toposiviric I, Botelho RJ. mTOR induces lysosome expansion by selective translation of lysosomal transcripts during phagocyte activation. The Journal of Immunology 2018. [DOI: 10.4049/jimmunol.200.supp.170.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
The molecular mechanisms that govern and adapt organelle number, size, morphology and activities to suit the needs of many cell types and the conditions that a cell may encounter remain poorly defined. Lysosomes are organelles that degrade cargo from a variety of routes including endocytosis, phagocytosis and autophagy. Lysosomes have emerged as a signalling platform that senses and couples stress signals such as nutrient deprivation to regulatory kinase hubs like mTOR and AMPK to modulate metabolic activity. For phagocytes and antigen-presenting cells like macrophages and dendritic cells, lysosomes are a kingpin organelle since they are essential to kill and process pathogens, and present antigens. During phagocyte activation, lysosomes undergo a striking reorganization, changing from dozens of globular structures to a tubular network, in a process that requires the phosphatidylinositol-3-kinase-Akt-mTOR signalling pathway. Ultimately, lysosome tubulation is thought to promote pinocytic retention and antigen presentation. We show that lysosome tubulation is accompanied by a rapid boost in lysosome volume and holding capacity during phagocyte activation with lipopolysaccharides. Unexpectedly, lysosome expansion was paralleled with the induction of lysosomal proteins, which was independent of TFEB and TFE3, transcription factors known to scale up lysosome biogenesis. Instead, we demonstrate a hitherto unappreciated mechanism of lysosome expansion via mTOR-dependent increase in translation of mRNAs encoding key lysosomal proteins including LAMP1 and V-ATPase subunits. Collectively, we identified a mechanism of rapid organelle expansion and remodelling driven by selective enhancement of protein synthesis.
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Richard S, Boucher M, Saric A, Herbet A, Lalatonne Y, Petit PX, Mériaux S, Boquet D, Motte L. Optimization of pegylated iron oxide nanoplatforms for antibody coupling and bio-targeting. J Mater Chem B 2017; 5:2896-2907. [PMID: 32263983 DOI: 10.1039/c6tb03080g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PEGylation has been established as a valuable strategy to minimize nanoparticle clearance by the reticulo-endothelial system due to hydrophilicity and steric repulsion of PEG chains. In this study we functionalized superparamagnetic iron oxide nanoparticle surface with two PEG differing in their length (n = 23 and 44) and terminal functionality, COOH and CH3. By varying the ratio of the two different PEG, we optimized the molecular architecture of the nanoplatform to obtain maximum stability and low toxicity under physiological conditions. The best nanoplatform was evaluated as MRI contrast for mouse brain vascularization imaging at 7 T. The carboxylic acid functions of the nanoplatform were used to covalently bind an antibody, Ab. This antibody, labeled with a fluorophore, targets the ETA receptor, a G-protein-coupled receptor involved in the endothelin axis and overexpressed in various solid tumours, including ovarian, prostate, colon, breast, bladder and lung cancers. In vitro studies, performed by flow cytometry and magnetic quantification, showed the targeting efficiency of the Ab-nanoplatforms. Clearly, an imaging tracer for cancer diagnosis from a bimodal contrast agent (fluorescence and MRI) was thus obtained.
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Affiliation(s)
- S Richard
- Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057, CNRS and Université Paris Diderot, 75205 Paris Cedex 05, France
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11
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Abstract
Cellular components sequestered by autophagosomes during macroautophagy must be degraded and their components recycled in order to maintain homeostasis. To this end cells orchestrate the fusion of autophagosomes with lysosomes, degradative organelles that are rich in hydrolases. Most of the lysosomal enzymes function optimally at low pH, and products of macromolecular catabolism are cotransported with protons across the autolysosomal membrane. These functions are facilitated by the ability of lysosomes to pump protons inward, acidifying their lumen. Clearly, proper homeostasis of the luminal pH is crucial for autolysosomal function. We describe a method for the measurement of the absolute pH of individual autolysosomes in live cells. This technique involves measurement of the fluorescence of a pH-sensitive probe initially delivered to lysosomes and subsequently determined to have reached autolysosomes. By measuring the fluorescence at two separate wavelengths and calculating their ratio, potential artifacts introduced by photobleaching or by changes in autolysosome size, shape, or positioning are minimized. Combining such ratio determinations with an in situ calibration procedure enables absolute measurements of pH, which are superior to the qualitative estimates obtained with fluorescent weak bases such as LysoTracker.
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Affiliation(s)
- A Saric
- Ryerson University, Toronto, ON, Canada
| | - S Grinstein
- Hospital for Sick Children, Toronto, ON, Canada; Keenan Research Centre, St. Michael's Hospital, Toronto, ON, Canada.
| | - S A Freeman
- Hospital for Sick Children, Toronto, ON, Canada
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Wong H, Jaumouillé V, Freeman S, Doodnauth S, Schlam D, Canton J, Mukovozov I, Saric A, Grinstein S, Robinson L. Chemokine Signaling Enhances CD36 Responsiveness toward Oxidized Low-Density Lipoproteins and Accelerates Foam Cell Formation. Cell Rep 2016; 14:2859-71. [DOI: 10.1016/j.celrep.2016.02.071] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 12/22/2015] [Accepted: 02/16/2016] [Indexed: 02/07/2023] Open
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Saric A, Hipolito VEB, Kay JG, Canton J, Antonescu CN, Botelho RJ. mTOR controls lysosome tubulation and antigen presentation in macrophages and dendritic cells. Mol Biol Cell 2015; 27:321-33. [PMID: 26582390 PMCID: PMC4713134 DOI: 10.1091/mbc.e15-05-0272] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 11/13/2015] [Indexed: 01/09/2023] Open
Abstract
Macrophages and dendritic cells exposed to lipopolysaccharide (LPS) convert their lysosomes from small, punctate organelles into a network of tubules. Tubular lysosomes have been implicated in phagosome maturation, retention of fluid phase, and antigen presentation. There is a growing appreciation that lysosomes act as sensors of stress and the metabolic state of the cell through the kinase mTOR. Here we show that LPS stimulates mTOR and that mTOR is required for LPS-induced lysosome tubulation and secretion of major histocompatibility complex II in macrophages and dendritic cells. Specifically, we show that the canonical phosphatidylinositol 3-kinase-Akt-mTOR signaling pathway regulates LPS-induced lysosome tubulation independently of IRAK1/4 and TBK. Of note, we find that LPS treatment augmented the levels of membrane-associated Arl8b, a lysosomal GTPase required for tubulation that promotes kinesin-dependent lysosome movement to the cell periphery, in an mTOR-dependent manner. This suggests that mTOR may interface with the Arl8b-kinesin machinery. To further support this notion, we show that mTOR antagonists can block outward movement of lysosomes in cells treated with acetate but have no effect in retrograde movement upon acetate removal. Overall our work provides tantalizing evidence that mTOR plays a role in controlling lysosome morphology and trafficking by modulating microtubule-based motor activity in leukocytes.
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Affiliation(s)
- Amra Saric
- Molecular Science Program and Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Victoria E B Hipolito
- Molecular Science Program and Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Jason G Kay
- Department of Oral Biology, University at Buffalo, Buffalo, NY 14214
| | - Johnathan Canton
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Costin N Antonescu
- Molecular Science Program and Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Roberto J Botelho
- Molecular Science Program and Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
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Dayam RM, Saric A, Shilliday RE, Botelho RJ. The Phosphoinositide-Gated Lysosomal Ca2+Channel, TRPML1, Is Required for Phagosome Maturation. Traffic 2015; 16:1010-26. [DOI: 10.1111/tra.12303] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 05/15/2015] [Accepted: 05/17/2015] [Indexed: 12/27/2022]
Affiliation(s)
- Roya M. Dayam
- Department of Chemistry and Biology; Ryerson University; Toronto Ontario M5B2K3 Canada
- Molecular Science Program; Ryerson University; Toronto Ontario M5B2K3 Canada
| | - Amra Saric
- Department of Chemistry and Biology; Ryerson University; Toronto Ontario M5B2K3 Canada
- Molecular Science Program; Ryerson University; Toronto Ontario M5B2K3 Canada
| | - Ryan E. Shilliday
- Department of Chemistry and Biology; Ryerson University; Toronto Ontario M5B2K3 Canada
| | - Roberto J. Botelho
- Department of Chemistry and Biology; Ryerson University; Toronto Ontario M5B2K3 Canada
- Molecular Science Program; Ryerson University; Toronto Ontario M5B2K3 Canada
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