201
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Vanier MT. Complex lipid trafficking in Niemann-Pick disease type C. J Inherit Metab Dis 2015; 38:187-99. [PMID: 25425283 DOI: 10.1007/s10545-014-9794-4] [Citation(s) in RCA: 184] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 10/31/2014] [Accepted: 11/09/2014] [Indexed: 10/24/2022]
Abstract
Niemann-Pick disease type C (NPC) is an atypical lysosomal storage disease resulting from mutations in one of two genes, either NPC1 or NPC2. Although a neurovisceral disorder, it is above all a neurodegenerative disease in the vast majority of patients. Not an enzyme deficiency, it is currently conceived as a lipid trafficking disorder. Impaired egress of cholesterol from the late endosomal/lysosomal (LE/L) compartment is a specific and key element of the pathogenesis, but other lipids, more specially sphingolipids, are also involved, and there are indications for further abnormalities. The full function of the NPC1 and NPC2 proteins is still unclear. This review provides a reappraisal of lipid storage and lysosomal enzymes activities in tissues/cells from NPC patients and animal models. It summarizes the current knowledge on the NPC1 and NPC2 proteins and their function in transport of cholesterol within the late endosomal-lysosomal compartment, with emphasis on differences between systemic organs and the brain; it also discusses regulation by membrane lipids of the NPC2-mediated cholesterol trafficking, interplay between cholesterol and sphingomyelin, the metabolic origin of glycosphingolipids stored in brain, and the putative role of free sphingoid bases in pathogenesis. Brief mention is finally made of diseases affecting other genes that were very recently shown to impact the "NPC pathway".
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Affiliation(s)
- Marie T Vanier
- Institut National de la Santé et de la Recherche Médicale U820, Université Lyon-1 EA4611, Faculté de Médecine Lyon-Est, 7 Rue G. Paradin, 69008, Lyon, France,
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202
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Toops KA, Tan LX, Jiang Z, Radu RA, Lakkaraju A. Cholesterol-mediated activation of acid sphingomyelinase disrupts autophagy in the retinal pigment epithelium. Mol Biol Cell 2014; 26:1-14. [PMID: 25378587 PMCID: PMC4279221 DOI: 10.1091/mbc.e14-05-1028] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
How autophagy is regulated in the postmitotic retinal pigment epithelium (RPE) is unclear. Visual cycle metabolites and cholesterol that accumulate in the RPE inhibit autophagic flux by activating acid sphingomyelinase (ASMase). Increased ceramide promotes tubulin acetylation, which prevents autophagosome traffic. ASMase inhibition restores RPE autophagy. Autophagy is an essential mechanism for clearing damaged organelles and proteins within the cell. As with neurodegenerative diseases, dysfunctional autophagy could contribute to blinding diseases such as macular degeneration. However, precisely how inefficient autophagy promotes retinal damage is unclear. In this study, we investigate innate mechanisms that modulate autophagy in the retinal pigment epithelium (RPE), a key site of insult in macular degeneration. High-speed live imaging of polarized adult primary RPE cells and data from a mouse model of early-onset macular degeneration identify a mechanism by which lipofuscin bisretinoids, visual cycle metabolites that progressively accumulate in the RPE, disrupt autophagy. We demonstrate that bisretinoids trap cholesterol and bis(monoacylglycero)phosphate, an acid sphingomyelinase (ASMase) cofactor, within the RPE. ASMase activation increases cellular ceramide, which promotes tubulin acetylation on stabilized microtubules. Live-imaging data show that autophagosome traffic and autophagic flux are inhibited in RPE with acetylated microtubules. Drugs that remove excess cholesterol or inhibit ASMase reverse this cascade of events and restore autophagosome motility and autophagic flux in the RPE. Because accumulation of lipofuscin bisretinoids and abnormal cholesterol homeostasis are implicated in macular degeneration, our studies suggest that ASMase could be a potential therapeutic target to ensure the efficient autophagy that maintains RPE health.
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Affiliation(s)
- Kimberly A Toops
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, McPherson Eye Research Institute, and
| | - Li Xuan Tan
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53706
| | - Zhichun Jiang
- Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90024
| | - Roxana A Radu
- Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90024
| | - Aparna Lakkaraju
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, McPherson Eye Research Institute, and Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53706
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203
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Abstract
Aging dogs and cats show neurodegenerative features that are similar to human aging and Alzheimer disease. Neuropathologic changes with age may be linked to signs of cognitive dysfunction both in the laboratory and in a clinic setting. Less is known about cat brain aging and cognition and this represents an area for further study. Neurodegenerative diseases such as lysosomal storage diseases in dogs and cats also show similar features of human aging, suggesting some common underlying pathogenic mechanisms and also suggesting pathways that can be modified to promote healthy brain aging.
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Affiliation(s)
- Charles H Vite
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Section of Neurology & Neurosurgery, Department of Clinical Studies - Philadelphia, 3900 Delancey Street, Philadelphia, PA 19104, USA
| | - Elizabeth Head
- Department of Pharmacology & Nutritional Sciences, Sanders-Brown Center on Aging, University of Kentucky, 800 South Limestone Street, 203 Sanders Brown Building, Lexington, KY 40515, USA.
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204
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Hawkins A, Guttentag SH, Deterding R, Funkhouser WK, Goralski JL, Chatterjee S, Mulugeta S, Beers MF. A non-BRICHOS SFTPC mutant (SP-CI73T) linked to interstitial lung disease promotes a late block in macroautophagy disrupting cellular proteostasis and mitophagy. Am J Physiol Lung Cell Mol Physiol 2014; 308:L33-47. [PMID: 25344067 DOI: 10.1152/ajplung.00217.2014] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mutation of threonine for isoleucine at codon 73 (I73T) in the human surfactant protein C (hSP-C) gene (SFTPC) accounts for a significant portion of SFTPC mutations associated with interstitial lung disease (ILD). Cell lines stably expressing tagged primary translation product of SP-C isoforms were generated to test the hypothesis that deposition of hSP-C(I73T) within the endosomal system promotes disruption of a key cellular quality control pathway, macroautophagy. By fluorescence microscopy, wild-type hSP-C (hSP-C(WT)) colocalized with exogenously expressed human ATP binding cassette class A3 (hABCA3), an indicator of normal trafficking to lysosomal-related organelles. In contrast, hSP-C(I73T) was dissociated from hABCA3 but colocalized to the plasma membrane as well as the endosomal network. Cells expressing hSP-C(I73T) exhibited increases in size and number of cytosolic green fluorescent protein/microtubule-associated protein 1 light-chain 3 (LC3) vesicles, some of which colabeled with red fluorescent protein from the gene dsRed/hSP-C(I73T). By transmission electron microscopy, hSP-C(I73T) cells contained abnormally large autophagic vacuoles containing organellar and proteinaceous debris, which phenocopied ultrastructural changes in alveolar type 2 cells in a lung biopsy from a SFTPC I73T patient. Biochemically, hSP-C(I73T) cells exhibited increased expression of Atg8/LC3, SQSTM1/p62, and Rab7, consistent with a distal block in autophagic vacuole maturation, confirmed by flux studies using bafilomycin A1 and rapamycin. Functionally, hSP-C(I73T) cells showed an impaired degradative capacity for an aggregation-prone huntingtin-1 reporter substrate. The disruption of autophagy-dependent proteostasis was accompanied by increases in mitochondria biomass and parkin expression coupled with a decrease in mitochondrial membrane potential. We conclude that hSP-C(I73T) induces an acquired block in macroautophagy-dependent proteostasis and mitophagy, which could contribute to the increased vulnerability of the lung epithelia to second-hit injury as seen in ILD.
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Affiliation(s)
- Arie Hawkins
- Pulmonary, Allergy, and Critical Care Division, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Susan H Guttentag
- Department of Pediatrics; Monroe Carell Jr. Children's Hospital, Vanderbilt University, Nashville, Tennessee
| | - Robin Deterding
- Department of Pediatrics; University of Colorado School of Medicine, Denver, Colorado
| | - William K Funkhouser
- Department of Pathology and Lab Medicine; University of North Carolina, Chapel Hill, North Carolina
| | - Jennifer L Goralski
- Departments of Medicine and Pediatrics; University of North Carolina, Chapel Hill, North Carolina
| | - Shampa Chatterjee
- Institute for Environmental Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Surafel Mulugeta
- Pulmonary, Allergy, and Critical Care Division, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania;
| | - Michael F Beers
- Pulmonary, Allergy, and Critical Care Division, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania
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205
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Yang DS, Stavrides P, Saito M, Kumar A, Rodriguez-Navarro JA, Pawlik M, Huo C, Walkley SU, Saito M, Cuervo AM, Nixon RA. Defective macroautophagic turnover of brain lipids in the TgCRND8 Alzheimer mouse model: prevention by correcting lysosomal proteolytic deficits. ACTA ACUST UNITED AC 2014; 137:3300-18. [PMID: 25270989 DOI: 10.1093/brain/awu278] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Autophagy, the major lysosomal pathway for the turnover of intracellular organelles is markedly impaired in neurons in Alzheimer's disease and Alzheimer mouse models. We have previously reported that severe lysosomal and amyloid neuropathology and associated cognitive deficits in the TgCRND8 Alzheimer mouse model can be ameliorated by restoring lysosomal proteolytic capacity and autophagy flux via genetic deletion of the lysosomal protease inhibitor, cystatin B. Here we present evidence that macroautophagy is a significant pathway for lipid turnover, which is defective in TgCRND8 brain where lipids accumulate as membranous structures and lipid droplets within giant neuronal autolysosomes. Levels of multiple lipid species including several sphingolipids (ceramide, ganglioside GM3, GM2, GM1, GD3 and GD1a), cardiolipin, cholesterol and cholesteryl esters are elevated in autophagic vacuole fractions and lysosomes isolated from TgCRND8 brain. Lipids are localized in autophagosomes and autolysosomes by double immunofluorescence analyses in wild-type mice and colocalization is increased in TgCRND8 mice where abnormally abundant GM2 ganglioside-positive granules are detected in neuronal lysosomes. Cystatin B deletion in TgCRND8 significantly reduces the number of GM2-positive granules and lowers the levels of GM2 and GM3 in lysosomes, decreases lipofuscin-related autofluorescence, and eliminates giant lipid-containing autolysosomes while increasing numbers of normal-sized autolysosomes/lysosomes with reduced content of undigested components. These findings have identified macroautophagy as a previously unappreciated route for delivering membrane lipids to lysosomes for turnover, a function that has so far been considered to be mediated exclusively through the endocytic pathway, and revealed that autophagic-lysosomal dysfunction in TgCRND8 brain impedes lysosomal turnover of lipids as well as proteins. The amelioration of lipid accumulation in TgCRND8 by removing cystatin B inhibition on lysosomal proteases suggests that enhancing lysosomal proteolysis improves the overall environment of the lysosome and its clearance functions, which may be possibly relevant to a broader range of lysosomal disorders beyond Alzheimer's disease.
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Affiliation(s)
- Dun-Sheng Yang
- 1 Centre for Dementia Research, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA 2 Department of Psychiatry, New York University Langone Medical Centre, 550 First Avenue, New York, NY 10016, USA
| | - Philip Stavrides
- 1 Centre for Dementia Research, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA
| | - Mitsuo Saito
- 1 Centre for Dementia Research, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA 2 Department of Psychiatry, New York University Langone Medical Centre, 550 First Avenue, New York, NY 10016, USA
| | - Asok Kumar
- 1 Centre for Dementia Research, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA 2 Department of Psychiatry, New York University Langone Medical Centre, 550 First Avenue, New York, NY 10016, USA
| | - Jose A Rodriguez-Navarro
- 3 Department of Developmental and Molecular Biology, Institute for Ageing Studies, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Monika Pawlik
- 1 Centre for Dementia Research, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA
| | - Chunfeng Huo
- 1 Centre for Dementia Research, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA
| | - Steven U Walkley
- 4 Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Mariko Saito
- 1 Centre for Dementia Research, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA 2 Department of Psychiatry, New York University Langone Medical Centre, 550 First Avenue, New York, NY 10016, USA
| | - Ana M Cuervo
- 3 Department of Developmental and Molecular Biology, Institute for Ageing Studies, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Ralph A Nixon
- 1 Centre for Dementia Research, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA 2 Department of Psychiatry, New York University Langone Medical Centre, 550 First Avenue, New York, NY 10016, USA 5 Department of Cell Biology, New York University Langone Medical Centre, 550 First Avenue, New York, NY 10016, USA
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206
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Sofola-Adesakin O, Castillo-Quan JI, Rallis C, Tain LS, Bjedov I, Rogers I, Li L, Martinez P, Khericha M, Cabecinha M, Bähler J, Partridge L. Lithium suppresses Aβ pathology by inhibiting translation in an adult Drosophila model of Alzheimer's disease. Front Aging Neurosci 2014; 6:190. [PMID: 25126078 PMCID: PMC4115666 DOI: 10.3389/fnagi.2014.00190] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 07/10/2014] [Indexed: 01/28/2023] Open
Abstract
The greatest risk factor for Alzheimer's disease (AD) is age, and changes in the ageing nervous system are likely contributors to AD pathology. Amyloid beta (Aβ) accumulation, which occurs as a result of the amyloidogenic processing of amyloid precursor protein (APP), is thought to initiate the pathogenesis of AD, eventually leading to neuronal cell death. Previously, we developed an adult-onset Drosophila model of AD. Mutant Aβ42 accumulation led to increased mortality and neuronal dysfunction in the adult flies. Furthermore, we showed that lithium reduced Aβ42 protein, but not mRNA, and was able to rescue Aβ42-induced toxicity. In the current study, we investigated the mechanism/s by which lithium modulates Aβ42 protein levels and Aβ42 induced toxicity in the fly model. We found that lithium caused a reduction in protein synthesis in Drosophila and hence the level of Aβ42. At both the low and high doses tested, lithium rescued the locomotory defects induced by Aβ42, but it rescued lifespan only at lower doses, suggesting that long-term, high-dose lithium treatment may have induced toxicity. Lithium also down-regulated translation in the fission yeast Schizosaccharomyces pombe associated with increased chronological lifespan. Our data highlight a role for lithium and reduced protein synthesis as potential therapeutic targets for AD pathogenesis.
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Affiliation(s)
- Oyinkan Sofola-Adesakin
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
- Max Planck Institute for Biology of AgeingCologne, Germany
| | - Jorge I. Castillo-Quan
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
- Max Planck Institute for Biology of AgeingCologne, Germany
| | - Charalampos Rallis
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
| | - Luke S. Tain
- Max Planck Institute for Biology of AgeingCologne, Germany
| | - Ivana Bjedov
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
- Laboratory of Molecular Biology of Cancer, UCL Cancer InstituteLondon, UK
| | - Iain Rogers
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
| | - Li Li
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
| | - Pedro Martinez
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
- Max Planck Institute for Biology of AgeingCologne, Germany
| | - Mobina Khericha
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
- Max Planck Institute for Biology of AgeingCologne, Germany
| | - Melissa Cabecinha
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
| | - Jürg Bähler
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
| | - Linda Partridge
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College LondonLondon, UK
- Max Planck Institute for Biology of AgeingCologne, Germany
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207
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Improved neuroprotection using miglustat, curcumin and ibuprofen as a triple combination therapy in Niemann–Pick disease type C1 mice. Neurobiol Dis 2014; 67:9-17. [DOI: 10.1016/j.nbd.2014.03.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 02/18/2014] [Accepted: 03/02/2014] [Indexed: 02/07/2023] Open
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208
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Carroll B, Korolchuk VI, Sarkar S. Amino acids and autophagy: cross-talk and co-operation to control cellular homeostasis. Amino Acids 2014; 47:2065-88. [PMID: 24965527 DOI: 10.1007/s00726-014-1775-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 05/29/2014] [Indexed: 12/13/2022]
Abstract
Maintenance of amino acid homeostasis is important for healthy cellular function, metabolism and growth. Intracellular amino acid concentrations are dynamic; the high demand for protein synthesis must be met with constant dietary intake, followed by cellular influx, utilization and recycling of nutrients. Autophagy is a catabolic process via which superfluous or damaged proteins and organelles are delivered to the lysosome and degraded to release free amino acids into the cytoplasm. Furthermore, autophagy is specifically activated in response to amino acid starvation via two key signaling cascades: the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) and the general control nonderepressible 2 (GCN2) pathways. These pathways are key regulators of the integration between anabolic (amino acid depleting) and catabolic (such as autophagy which is amino acid replenishing) processes to ensure intracellular amino acid homeostasis. Here, we discuss the key roles that amino acids, along with energy (ATP, glucose) and oxygen, are playing in cellular growth and proliferation. We further explore how sophisticated methods are employed by cells to sense intracellular amino acid concentrations, how amino acids can act as a switch to dictate the temporal and spatial activation of anabolic and catabolic processes and how autophagy contributes to the replenishment of free amino acids, all to ensure cell survival. Relevance of these molecular processes to cellular and organismal physiology and pathology is also discussed.
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Affiliation(s)
- Bernadette Carroll
- Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, NE4 5PL, UK
| | - Viktor I Korolchuk
- Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, NE4 5PL, UK.
| | - Sovan Sarkar
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA, 02142, USA.
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209
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Szatmári Z, Sass M. The autophagic roles of Rab small GTPases and their upstream regulators: a review. Autophagy 2014; 10:1154-66. [PMID: 24915298 DOI: 10.4161/auto.29395] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Macroautophagy is an evolutionarily conserved degradative process of eukaryotic cells. Double-membrane vesicles called autophagosomes sequester portions of cytoplasm and undergo fusion with the endolysosomal pathway in order to degrade their content. There is growing evidence that members of the small GTPase RAB protein family-the well-known regulators of membrane trafficking and fusion events-play key roles in the regulation of the autophagic process. Despite numerous studies focusing on the functions of RAB proteins in autophagy, the importance of their upstream regulators in this process emerged only in the past few years. In this review, we summarize recent advances on the effects of RABs and their upstream modulators in the regulation of autophagy. Moreover, we discuss how impairment of these proteins alters the autophagic process leading to several generally known human diseases.
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Affiliation(s)
- Zsuzsanna Szatmári
- Department of Anatomy, Cell and Developmental Biology; Eötvös Loránd University; Budapest, Hungary
| | - Miklós Sass
- Department of Anatomy, Cell and Developmental Biology; Eötvös Loránd University; Budapest, Hungary
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210
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Genetic and chemical correction of cholesterol accumulation and impaired autophagy in hepatic and neural cells derived from Niemann-Pick Type C patient-specific iPS cells. Stem Cell Reports 2014; 2:866-80. [PMID: 24936472 PMCID: PMC4050353 DOI: 10.1016/j.stemcr.2014.03.014] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 03/25/2014] [Accepted: 03/31/2014] [Indexed: 12/17/2022] Open
Abstract
Niemann-Pick type C (NPC) disease is a fatal inherited lipid storage disorder causing severe neurodegeneration and liver dysfunction with only limited treatment options for patients. Loss of NPC1 function causes defects in cholesterol metabolism and has recently been implicated in deregulation of autophagy. Here, we report the generation of isogenic pairs of NPC patient-specific induced pluripotent stem cells (iPSCs) using transcription activator-like effector nucleases (TALENs). We observed decreased cell viability, cholesterol accumulation, and dysfunctional autophagic flux in NPC1-deficient human hepatic and neural cells. Genetic correction of a disease-causing mutation rescued these defects and directly linked NPC1 protein function to impaired cholesterol metabolism and autophagy. Screening for autophagy-inducing compounds in disease-affected human cells showed cell type specificity. Carbamazepine was found to be cytoprotective and effective in restoring the autophagy defects in both NPC1-deficient hepatic and neuronal cells and therefore may be a promising treatment option with overall benefit for NPC disease. Generation of Niemann-Pick type C (NPC) disease patient-specific iPSCs NPC1 hepatic and neuronal cells show defects in cholesterol and autophagic flux TALEN-mediated genetic correction rescues the cholesterol and autophagy defects Autophagy inducers can restore functional autophagy and increase cell viability
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211
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Gabandé-Rodríguez E, Boya P, Labrador V, Dotti CG, Ledesma MD. High sphingomyelin levels induce lysosomal damage and autophagy dysfunction in Niemann Pick disease type A. Cell Death Differ 2014; 21:864-75. [PMID: 24488099 DOI: 10.1038/cdd.2014.4] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 12/13/2013] [Accepted: 12/23/2013] [Indexed: 12/19/2022] Open
Abstract
Niemann Pick disease type A (NPA), which is caused by loss of function mutations in the acid sphingomyelinase (ASM) gene, is a lysosomal storage disorder leading to neurodegeneration. Yet, lysosomal dysfunction and its consequences in the disease are poorly characterized. Here we show that undegraded molecules build up in neurons of acid sphingomyelinase knockout mice and in fibroblasts from NPA patients in which autophagolysosomes accumulate. The latter is not due to alterations in autophagy initiation or autophagosome-lysosome fusion but because of inefficient autophago-lysosomal clearance. This, in turn, can be explained by lysosomal membrane permeabilization leading to cytosolic release of Cathepsin B. High sphingomyelin (SM) levels account for these effects as they can be induced in control cells on addition of the lipid and reverted on SM-lowering strategies in ASM-deficient cells. These results unveil a relevant role for SM in autophagy modulation and characterize autophagy anomalies in NPA, opening new perspectives for therapeutic interventions.
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Affiliation(s)
| | - P Boya
- Centro Investigaciones Biológicas, CSIC, Madrid 28040, Spain
| | - V Labrador
- Centro Biología Molecular Severo Ochoa, CSIC-UAM, Madrid 28049, Spain
| | - C G Dotti
- Centro Biología Molecular Severo Ochoa, CSIC-UAM, Madrid 28049, Spain
| | - M D Ledesma
- Centro Biología Molecular Severo Ochoa, CSIC-UAM, Madrid 28049, Spain
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