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Henis-Korenblit S, Meléndez A. Methods to Determine the Role of Autophagy Proteins in C. elegans Aging. Methods Mol Biol 2019; 1880:561-586. [PMID: 30610723 DOI: 10.1007/978-1-4939-8873-0_37] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
This chapter describes methods for the analysis of autophagy proteins in C. elegans aging. We discuss the strains to be considered, the methods for the delivery of double-stranded RNA, and the methods to measure autophagy levels, autophagic flux, and degradation by autophagy.
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Affiliation(s)
- Sivan Henis-Korenblit
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
| | - Alicia Meléndez
- Department of Biology, Queens College, The City University of New York, Flushing, NY, USA.
- Biology and Biochemistry PhD Programs, The Graduate Center of the City University of New York, New York, NY, USA.
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Approaches for Studying Autophagy in Caenorhabditis elegans. Cells 2017; 6:cells6030027. [PMID: 28867808 PMCID: PMC5617973 DOI: 10.3390/cells6030027] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 08/25/2017] [Accepted: 08/26/2017] [Indexed: 01/10/2023] Open
Abstract
Macroautophagy (hereafter referred to as autophagy) is an intracellular degradative process, well conserved among eukaryotes. By engulfing cytoplasmic constituents into the autophagosome for degradation, this process is involved in the maintenance of cellular homeostasis. Autophagy induction triggers the formation of a cup-shaped double membrane structure, the phagophore, which progressively elongates and encloses materials to be removed. This double membrane vesicle, which is called an autophagosome, fuses with lysosome and forms the autolysosome. The inner membrane of the autophagosome, along with engulfed compounds, are degraded by lysosomal enzymes, which enables the recycling of carbohydrates, amino acids, nucleotides, and lipids. In response to various factors, autophagy can be induced for non-selective degradation of bulk cytoplasm. Autophagy is also able to selectively target cargoes and organelles such as mitochondria or peroxisome, functioning as a quality control system. The modification of autophagy flux is involved in developmental processes such as resistance to stress conditions, aging, cell death, and multiple pathologies. So, the use of animal models is essential for understanding these processes in the context of different cell types throughout the entire lifespan. For almost 15 years, the nematode Caenorhabditis elegans has emerged as a powerful model to analyze autophagy in physiological or pathological contexts. This review presents a rapid overview of physiological processes involving autophagy in Caenorhabditis elegans, the different assays used to monitor autophagy, their drawbacks, and specific tools for the analyses of selective autophagy.
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Palmisano NJ, Meléndez A. RNAi-Mediated Inactivation of Autophagy Genes in Caenorhabditis elegans. Cold Spring Harb Protoc 2016; 2016:pdb.prot086520. [PMID: 26832686 PMCID: PMC8103221 DOI: 10.1101/pdb.prot086520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
RNA interference (RNAi) is a process that results in the sequence-specific silencing of endogenous mRNA through the introduction of double-stranded RNA (dsRNA). In the nematode Caenorhabditis elegans, RNA inactivation can be used at any specific developmental stage or during adulthood to inhibit a given target gene. Investigators can take advantage of the fact that, in C. elegans, RNAi is unusual in that it is systemic, meaning that dsRNA can spread throughout the animal and can affect virtually all tissues except neurons. Here, we describe a protocol for the most common method to achieve RNAi in C. elegans, which is to feed them bacteria that express dsRNA complementary to a specific target gene. This method has various advantages, including the availability of libraries that essentially cover the whole genome, the ability to treat animals at any developmental stage, and that it is relatively cost effective. We also discuss how RNAi specific to autophagy genes has proven to be an excellent method to study the role of these genes in autophagy, as well as other cellular and developmental processes, while also highlighting the caveats that must be applied.
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Affiliation(s)
- Nicholas J. Palmisano
- Queens College-CUNY, Department of Biology, Flushing, NY, USA
- The Graduate Center, The City University of New York, New York, USA
| | - Alicia Meléndez
- Queens College-CUNY, Department of Biology, Flushing, NY, USA
- The Graduate Center, The City University of New York, New York, USA
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Duarte-Silva S, Neves-Carvalho A, Soares-Cunha C, Teixeira-Castro A, Oliveira P, Silva-Fernandes A, Maciel P. Lithium chloride therapy fails to improve motor function in a transgenic mouse model of Machado-Joseph disease. THE CEREBELLUM 2015; 13:713-27. [PMID: 25112410 DOI: 10.1007/s12311-014-0589-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The accumulation of misfolded proteins in neurons, leading to the formation of cytoplasmic and nuclear aggregates, is a common theme in age-related neurodegenerative diseases, possibly due to disturbances of the proteostasis and insufficient activity of cellular protein clearance pathways. Lithium is a well-known autophagy inducer that exerts neuroprotective effects in different conditions and has been proposed as a promising therapeutic agent for several neurodegenerative diseases. We tested the efficacy of chronic lithium (10.4 mg/kg) treatment in a transgenic mouse model of Machado-Joseph disease, an inherited neurodegenerative disease, caused by an expansion of a polyglutamine tract within the protein ataxin-3. A battery of behavioral tests was used to assess disease progression. In spite of activating autophagy, as suggested by the increased levels of Beclin-1, Atg7, and LC3-II, and a reduction in the p62 protein levels, lithium administration showed no overall beneficial effects in this model concerning motor performance, showing a positive impact only in the reduction of tremors at 24 weeks of age. Our results do not support lithium chronic treatment as a promising strategy for the treatment of Machado-Joseph disease (MJD).
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Affiliation(s)
- Sara Duarte-Silva
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus Gualtar, 4710-057, Braga, Portugal
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Wilkinson DS, Jariwala JS, Anderson E, Mitra K, Meisenhelder J, Chang JT, Ideker T, Hunter T, Nizet V, Dillin A, Hansen M. Phosphorylation of LC3 by the Hippo kinases STK3/STK4 is essential for autophagy. Mol Cell 2015; 57:55-68. [PMID: 25544559 PMCID: PMC4373083 DOI: 10.1016/j.molcel.2014.11.019] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 10/13/2014] [Accepted: 11/18/2014] [Indexed: 11/17/2022]
Abstract
The protein LC3 is indispensible for the cellular recycling process of autophagy and plays critical roles during cargo recruitment, autophagosome biogenesis, and completion. Here, we report that LC3 is phosphorylated at threonine 50 (Thr(50)) by the mammalian Sterile-20 kinases STK3 and STK4. Loss of phosphorylation at this site blocks autophagy by impairing fusion of autophagosomes with lysosomes, and compromises the ability of cells to clear intracellular bacteria, an established cargo for autophagy. Strikingly, mutation of LC3 mimicking constitutive phosphorylation at Thr(50) reverses the autophagy block in STK3/STK4-deficient cells and restores their capacity to clear bacteria. Loss of STK3/STK4 impairs autophagy in diverse species, indicating that these kinases are conserved autophagy regulators. We conclude that phosphorylation of LC3 by STK3/STK4 is an essential step in the autophagy process. Since several pathological conditions, including bacterial infections, display aberrant autophagy, we propose that pharmacological agents targeting this regulatory circuit hold therapeutic potential.
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Affiliation(s)
- Deepti S Wilkinson
- Sanford-Burnham Medical Research Institute, Development, Aging, and Regeneration Program, La Jolla, CA 92037, USA
| | - Jinel S Jariwala
- Sanford-Burnham Medical Research Institute, Development, Aging, and Regeneration Program, La Jolla, CA 92037, USA
| | - Ericka Anderson
- Department of Pediatrics, School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Koyel Mitra
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | | | - Jessica T Chang
- Sanford-Burnham Medical Research Institute, Development, Aging, and Regeneration Program, La Jolla, CA 92037, USA
| | - Trey Ideker
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Tony Hunter
- Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Victor Nizet
- Department of Pediatrics, School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Andrew Dillin
- The Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA
| | - Malene Hansen
- Sanford-Burnham Medical Research Institute, Development, Aging, and Regeneration Program, La Jolla, CA 92037, USA.
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Jenzer C, Simionato E, Legouis R. Tools and methods to analyze autophagy in C. elegans. Methods 2014; 75:162-71. [PMID: 25484340 DOI: 10.1016/j.ymeth.2014.11.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/24/2014] [Accepted: 11/25/2014] [Indexed: 11/27/2022] Open
Abstract
For a long time, autophagy has been mainly studied in yeast or mammalian cell lines, and assays for analyzing autophagy in these models have been well described. More recently, the involvement of autophagy in various physiological functions has been investigated in multicellular organisms. Modification of autophagy flux is involved in developmental processes, resistance to stress conditions, aging, cell death and multiple pathologies. So, the use of animal models is essential to understand these processes in the context of different cell types and during the whole life. For ten years, the nematode Caenorhabditis elegans has emerged as a powerful model to analyze autophagy in physiological or pathological contexts. In this article, we present some of the established approaches and the emerging tools available to monitor and manipulate autophagy in C. elegans, and discuss their advantages and limitations.
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Affiliation(s)
- Céline Jenzer
- Centre de Génétique Moléculaire, CNRS UPR3404, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, 1 Avenue de la Terrasse, 91198 Gif sur Yvette, France
| | - Elena Simionato
- Centre de Génétique Moléculaire, CNRS UPR3404, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, 1 Avenue de la Terrasse, 91198 Gif sur Yvette, France
| | - Renaud Legouis
- Centre de Génétique Moléculaire, CNRS UPR3404, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, 1 Avenue de la Terrasse, 91198 Gif sur Yvette, France.
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Nikoletopoulou V, Kyriakakis E, Tavernarakis N. Cellular and molecular longevity pathways: the old and the new. Trends Endocrinol Metab 2014; 25:212-23. [PMID: 24388148 DOI: 10.1016/j.tem.2013.12.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 11/26/2013] [Accepted: 12/02/2013] [Indexed: 01/08/2023]
Abstract
Human lifespan has been increasing steadily during modern times, mainly due to medical advancements that combat infant mortality and various life-threatening diseases. However, this gratifying longevity rise is accompanied by growing incidences of devastating age-related pathologies. Understanding the cellular and molecular mechanisms that underlie aging and regulate longevity is of utmost relevance towards offsetting the impact of age-associated disorders and increasing the quality of life for the elderly. Several evolutionarily conserved pathways that modulate lifespan have been identified in organisms ranging from yeast to primates. Here we survey recent findings highlighting the interplay of various genetic, epigenetic, and cell-specific factors, and also symbiotic relationships, as longevity determinants. We further discuss outstanding matters within the framework of emerging, integrative views of aging.
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Affiliation(s)
- Vassiliki Nikoletopoulou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion 71110, Crete, Greece
| | - Emmanouil Kyriakakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion 71110, Crete, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion 71110, Crete, Greece.
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Heestand BN, Shen Y, Liu W, Magner DB, Storm N, Meharg C, Habermann B, Antebi A. Dietary restriction induced longevity is mediated by nuclear receptor NHR-62 in Caenorhabditis elegans. PLoS Genet 2013; 9:e1003651. [PMID: 23935515 PMCID: PMC3723528 DOI: 10.1371/journal.pgen.1003651] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Accepted: 06/04/2013] [Indexed: 11/18/2022] Open
Abstract
Dietary restriction (DR) extends lifespan in a wide variety of species, yet the underlying mechanisms are not well understood. Here we show that the Caenorhabditis elegans HNF4α-related nuclear hormone receptor NHR-62 is required for metabolic and physiologic responses associated with DR-induced longevity. nhr-62 mediates the longevity of eat-2 mutants, a genetic mimetic of dietary restriction, and blunts the longevity response of DR induced by bacterial food dilution at low nutrient levels. Metabolic changes associated with DR, including decreased Oil Red O staining, decreased triglyceride levels, and increased autophagy are partly reversed by mutation of nhr-62. Additionally, the DR fatty acid profile is altered in nhr-62 mutants. Expression profiles reveal that several hundred genes induced by DR depend on the activity of NHR-62, including a putative lipase required for the DR response. This study provides critical evidence of nuclear hormone receptor regulation of the DR longevity response, suggesting hormonal and metabolic control of life span. Dietary restriction extends the life span of diverse species across taxa, yet the underlying mechanisms are poorly understood. In humans there are clear health benefits associated with DR such as improved serum cholesterol and lipid levels. In Caenorhabditis elegans, genes implicated in the TOR pathway, autophagy, protein synthesis and energy homeostasis have been shown to modulate the dietary restriction response; however their mechanism of action is still unclear. In this work, we find that the C. elegans nuclear hormone receptor, nhr-62, is required for longevity in multiple DR regimens, providing the first evidence of a nuclear receptor required for DR-induced longevity. Additionally, nhr-62 is required for physiologic changes associated with DR, including increased autophagy and decreased levels of triglycerides, possibly through lipolysis. Moreover, nhr-62 is responsible for regulating hundreds of genes under DR, as measured by qPCR and RNA-seq. Importantly, this work is the first to report transcriptome analysis of DR in C. elegans and the first to provide functional evidence that nuclear receptors are key regulators of the DR longevity response, which imply hormonal and metabolic control of longevity, possibly through alterations in fat metabolism, lipolysis, and autophagy.
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Affiliation(s)
- Bree N. Heestand
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Yidong Shen
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Wei Liu
- Department of Molecular and Cellular Biology, Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, United States of America
| | | | - Nadia Storm
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Caroline Meharg
- Max Planck Institute for Biology of Ageing, Cologne, Germany
- Institute for Global Food Security, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom
| | | | - Adam Antebi
- Max Planck Institute for Biology of Ageing, Cologne, Germany
- Department of Molecular and Cellular Biology, Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, United States of America
- Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- * E-mail:
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O'Rourke EJ, Kuballa P, Xavier R, Ruvkun G. ω-6 Polyunsaturated fatty acids extend life span through the activation of autophagy. Genes Dev 2013; 27:429-40. [PMID: 23392608 DOI: 10.1101/gad.205294.112] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Adaptation to nutrient scarcity depends on the activation of metabolic programs to efficiently use internal reserves of energy. Activation of these programs in abundant food regimens can extend life span. However, the common molecular and metabolic changes that promote adaptation to nutritional stress and extend life span are mostly unknown. Here we present a response to fasting, enrichment of ω-6 polyunsaturated fatty acids (PUFAs), which promotes starvation resistance and extends Caenorhabditis elegans life span. Upon fasting, C. elegans induces the expression of a lipase, which in turn leads to an enrichment of ω-6 PUFAs. Supplementing C. elegans culture media with these ω-6 PUFAs increases their resistance to starvation and extends their life span in conditions of food abundance. Supplementation of C. elegans or human epithelial cells with these ω-6 PUFAs activates autophagy, a cell recycling mechanism that promotes starvation survival and slows aging. Inactivation of C. elegans autophagy components reverses the increase in life span conferred by supplementing the C. elegans diet with these fasting-enriched ω-6 PUFAs. We propose that the salubrious effects of dietary supplementation with ω-3/6 PUFAs (fish oils) that have emerged from epidemiological studies in humans may be due to a similar activation of autophagic programs.
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Affiliation(s)
- Eyleen J O'Rourke
- Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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Schiavi A, Torgovnick A, Kell A, Megalou E, Castelein N, Guccini I, Marzocchella L, Gelino S, Hansen M, Malisan F, Condò I, Bei R, Rea SL, Braeckman BP, Tavernarakis N, Testi R, Ventura N. Autophagy induction extends lifespan and reduces lipid content in response to frataxin silencing in C. elegans. Exp Gerontol 2013; 48:191-201. [PMID: 23247094 PMCID: PMC3572394 DOI: 10.1016/j.exger.2012.12.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 12/04/2012] [Indexed: 02/02/2023]
Abstract
Severe mitochondria deficiency leads to a number of devastating degenerative disorders, yet, mild mitochondrial dysfunction in different species, including the nematode Caenorhabditis elegans, can have pro-longevity effects. This apparent paradox indicates that cellular adaptation to partial mitochondrial stress can induce beneficial responses, but how this is achieved is largely unknown. Complete absence of frataxin, the mitochondrial protein defective in patients with Friedreich's ataxia, is lethal in C. elegans, while its partial deficiency extends animal lifespan in a p53 dependent manner. In this paper we provide further insight into frataxin control of C. elegans longevity by showing that a substantial reduction of frataxin protein expression is required to extend lifespan, affect sensory neurons functionality, remodel lipid metabolism and trigger autophagy. We find that Beclin and p53 genes are required to induce autophagy and concurrently reduce lipid storages and extend animal lifespan in response to frataxin suppression. Reciprocally, frataxin expression modulates autophagy in the absence of p53. Human Friedreich ataxia-derived lymphoblasts also display increased autophagy, indicating an evolutionarily conserved response to reduced frataxin expression. In sum, we demonstrate a causal connection between induction of autophagy and lifespan extension following reduced frataxin expression, thus providing the rationale for investigating autophagy in the pathogenesis and treatment of Friedreich's ataxia and possibly other human mitochondria-associated disorders.
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Affiliation(s)
- Alfonso Schiavi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
- Institute of Clinical Chemistry and Laboratory Medicine of the Heinrich Heine University, and the IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Alessandro Torgovnick
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
- Institute of Clinical Chemistry and Laboratory Medicine of the Heinrich Heine University, and the IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Alison Kell
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Evgenia Megalou
- IMBB, Foundation for Research and Technology, Heraklion 71110, Crete, Greece
| | | | - Ilaria Guccini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Laura Marzocchella
- Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata", 00133 Rome, Italy
| | - Sara Gelino
- Sanford-Burnham Medical Research Institute, Graduate School of Biomedical Sciences, Del E. Webb Neuroscience, Aging and Stem Cell Research Center, Program of Development and Aging, La Jolla, CA, USA
| | - Malene Hansen
- Sanford-Burnham Medical Research Institute, Graduate School of Biomedical Sciences, Del E. Webb Neuroscience, Aging and Stem Cell Research Center, Program of Development and Aging, La Jolla, CA, USA
| | - Florence Malisan
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Ivano Condò
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Roberto Bei
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Shane L. Rea
- Sam and Ann Barshop Institute for Longevity and Aging Studies and the Department of Physiology, UTHSCSA, San Antonio, TX, USA
| | | | | | - Roberto Testi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Natascia Ventura
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
- Institute of Clinical Chemistry and Laboratory Medicine of the Heinrich Heine University, and the IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
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Lapierre LR, Silvestrini MJ, Nuñez L, Ames K, Wong S, Le TT, Hansen M, Meléndez A. Autophagy genes are required for normal lipid levels in C. elegans. Autophagy 2013; 9:278-86. [PMID: 23321914 DOI: 10.4161/auto.22930] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Autophagy is a cellular catabolic process in which various cytosolic components are degraded. For example, autophagy can mediate lipolysis of neutral lipid droplets. In contrast, we here report that autophagy is required to facilitate normal levels of neutral lipids in C. elegans. Specifically, by using multiple methods to detect lipid droplets including CARS microscopy, we observed that mutants in the gene bec- 1 (VPS30/ATG6/BECN1), a key regulator of autophagy, failed to store substantial neutral lipids in their intestines during development. Moreover, loss of bec-1 resulted in a decline in lipid levels in daf-2 [insulin/IGF-1 receptor (IIR) ortholog] mutants and in germline-less glp-1/Notch animals, both previously recognized to accumulate neutral lipids and have increased autophagy levels. Similarly, inhibition of additional autophagy genes, including unc-51/ULK1/ATG1 and lgg-1/ATG8/MAP1LC3A/LC3 during development, led to a reduction in lipid content. Importantly, the decrease in fat accumulation observed in animals with reduced autophagy did not appear to be due to a change in food uptake or defecation. Taken together, these observations suggest a broader role for autophagy in lipid remodeling in C. elegans.
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Affiliation(s)
- Louis R Lapierre
- Sanford-Burnham Medical Research Institute; Del E. Webb Neuroscience, Aging and Stem Cell Research Center, Program of Development and Aging, La Jolla, CA USA
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Abstract
This chapter is dedicated to the study of aging in Caenorhabditis elegans (C. elegans). The assays are divided into two sections. In the first section, we describe detailed protocols for performing life span analysis in solid and liquid medium. In the second section, we describe various assays for measuring age-related changes. Our laboratory has been involved in several fruitful collaborations with non-C. elegans researchers keen on testing a role for their favorite gene in modulating aging (Carrano et al., 2009; Dong et al., 2007; Raices et al., 2008; Wolff et al., 2006). But even with the guidance of trained worm biologists, this undertaking can be daunting. We hope that this chapter will serve as a worthy compendium for those researchers who may or may not have immediate access to laboratories studying C. elegans.
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Affiliation(s)
- Deepti S Wilkinson
- Howard Hughes Medical Institute, Glenn Center for Aging Research, Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
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Lapierre LR, Gelino S, Meléndez A, Hansen M. Autophagy and lipid metabolism coordinately modulate life span in germline-less C. elegans. Curr Biol 2011; 21:1507-14. [PMID: 21906946 DOI: 10.1016/j.cub.2011.07.042] [Citation(s) in RCA: 262] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 06/23/2011] [Accepted: 07/28/2011] [Indexed: 11/28/2022]
Abstract
BACKGROUND The cellular recycling process of autophagy is emerging as a key player in several longevity pathways in Caenorhabditis elegans. Here, we identify a role for autophagy in long-lived animals lacking a germline and show that autophagy and lipid metabolism work interdependently to modulate aging in this longevity model. RESULTS Germline removal extends life span in C. elegans via genes such as the lipase LIPL-4; however, less is known of the cellular basis for this life-span extension. Here, we show that germline loss induces autophagy gene expression via the forkhead box A (FOXA) transcription factor PHA-4 and that autophagy is required to extend longevity. We identify a novel link between autophagy and LIPL-4, because autophagy is required to maintain high lipase activity in germline-deficient animals. Reciprocally, lipl-4 is required for autophagy induction. Coordination between autophagy and lipolysis is further supported by the finding that inhibition of TOR (target of rapamycin), a major negative regulator of autophagy, induces lipl-4 expression, and TOR levels are reduced in germline-less animals. TOR may therefore function as a common upstream regulator of both autophagy and lipl-4 expression in germline-less animals. Importantly, we find that the link between autophagy and LIPL-4 is relevant to longevity, because autophagy is induced in animals overexpressing LIPL-4 and autophagy is required for their long life span, recapitulating observations in germline-less animals. CONCLUSIONS Collectively, our data offer a novel mechanism by which autophagy and the lipase LIPL-4 interdependently modulate aging in germline-deficient C. elegans by maintaining lipid homeostasis to prolong life span.
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Affiliation(s)
- Louis R Lapierre
- Program of Development and Aging, Del E. Webb Neuroscience, Aging and Stem Cell Research Center, USA
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14
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Ruck A, Attonito J, Garces KT, Núnez L, Palmisano NJ, Rubel Z, Bai Z, Nguyen KC, Sun L, Grant BD, Hall DH, Meléndez A. The Atg6/Vps30/Beclin 1 ortholog BEC-1 mediates endocytic retrograde transport in addition to autophagy in C. elegans. Autophagy 2011; 7:386-400. [PMID: 21183797 PMCID: PMC3108013 DOI: 10.4161/auto.7.4.14391] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 12/05/2010] [Accepted: 12/06/2010] [Indexed: 02/05/2023] Open
Abstract
Autophagy and endocytosis are dynamic and tightly regulated processes that contribute to many fundamental aspects of biology including survival, longevity, and development. However, the molecular links between autophagy and endocytosis are not well understood. Here, we report that BEC-1, the C. elegans ortholog of Atg6/Vps30/Beclin1, a key regulator of the autophagic machinery, also contributes to endosome function. In particular we identify a defect in retrograde transport from endosomes to the Golgi in bec-1 mutants. MIG-14/Wntless is normally recycled from endosomes to the Golgi through the action of the retromer complex and its associated factor RME-8. Lack of retromer or RME-8 activity results in the aberrant transport of MIG-14/Wntless to the lysosome where it is degraded. Similarly, we find that lack of bec-1 also results in mislocalization and degradation of MIG-14::GFP, reduced levels of RME-8 on endosomal membranes, and the accumulation of morphologically abnormal endosomes. A similar phenotype was observed in animals treated with dsRNA against vps-34. We further identify a requirement for BEC-1 in the clearance of apoptotic corpses in the hermaphrodite gonad, suggesting a role for BEC-1 in phagosome maturation, a process that appears to depend upon retrograde transport. In addition, autophagy genes may also be required for cell corpse clearance, as we find that RNAi against atg-18 or unc-51 also results in a lack of cell corpse clearance.
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Affiliation(s)
- Alexander Ruck
- Department of Biology; Queens College; Flushing, NY USA
- The Graduate Center; The City University of New York; New York, NY USA
| | - John Attonito
- Department of Biology; Queens College; Flushing, NY USA
| | | | - Lizbeth Núnez
- Department of Biology; Queens College; Flushing, NY USA
| | - Nicholas J Palmisano
- Department of Biology; Queens College; Flushing, NY USA
- The Graduate Center; The City University of New York; New York, NY USA
| | - Zahava Rubel
- Department of Biology; Queens College; Flushing, NY USA
| | - Zhiyong Bai
- Department of Molecular Biology and Biochemistry; Rutgers University; Piscataway, NJ USA
| | - Ken C.Q Nguyen
- Center for C. elegans Anatomy; Albert Einstein College of Medicine; Bronx, NY USA
| | - Lei Sun
- Center for C. elegans Anatomy; Albert Einstein College of Medicine; Bronx, NY USA
- Center for Biological Imaging; Institute of Biophysics; Chinese Academy of Sciences; Beijing, China
| | - Barth D Grant
- Department of Molecular Biology and Biochemistry; Rutgers University; Piscataway, NJ USA
| | - David H Hall
- Center for C. elegans Anatomy; Albert Einstein College of Medicine; Bronx, NY USA
| | - Alicia Meléndez
- Department of Biology; Queens College; Flushing, NY USA
- The Graduate Center; The City University of New York; New York, NY USA
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15
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Schreiber MA, Pierce-Shimomura JT, Chan S, Parry D, McIntire SL. Manipulation of behavioral decline in Caenorhabditis elegans with the Rag GTPase raga-1. PLoS Genet 2010; 6:e1000972. [PMID: 20523893 PMCID: PMC2877737 DOI: 10.1371/journal.pgen.1000972] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 04/27/2010] [Indexed: 01/08/2023] Open
Abstract
Normal aging leads to an inexorable decline in motor performance, contributing to medical morbidity and decreased quality of life. While much has been discovered about genetic determinants of lifespan, less is known about modifiers of age-related behavioral decline and whether new gene targets may be found which extend vigorous activity, with or without extending lifespan. Using Caenorhabditis elegans, we have developed a model of declining neuromuscular function and conducted a screen for increased behavioral activity in aged animals. In this model, behavioral function suffers from profound reductions in locomotory frequency, but coordination is strikingly preserved until very old age. By screening for enhancers of locomotion at advanced ages we identified the ras-related Rag GTPase raga-1 as a novel modifier of behavioral aging. raga-1 loss of function mutants showed vigorous swimming late in life. Genetic manipulations revealed that a gain of function raga-1 curtailed behavioral vitality and shortened lifespan, while a dominant negative raga-1 lengthened lifespan. Dietary restriction results indicated that a raga-1 mutant is relatively protected from the life-shortening effects of highly concentrated food, while RNAi experiments suggested that raga-1 acts in the highly conserved target of rapamycin (TOR) pathway in C. elegans. Rag GTPases were recently shown to mediate nutrient-dependent activation of TOR. This is the first demonstration of their dramatic effects on behavior and aging. This work indicates that novel modulators of behavioral function can be identified in screens, with implications for future study of the clinical amelioration of age-related decline.
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Affiliation(s)
- Matthew A. Schreiber
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California San Francisco, Emeryville, California, United States of America
- * E-mail: (SLM); (MAS)
| | - Jonathan T. Pierce-Shimomura
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California San Francisco, Emeryville, California, United States of America
| | - Stefan Chan
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California San Francisco, Emeryville, California, United States of America
| | - Dianne Parry
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California San Francisco, Emeryville, California, United States of America
| | - Steven L. McIntire
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California San Francisco, Emeryville, California, United States of America
- * E-mail: (SLM); (MAS)
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