251
|
Santaguida S, Vasile E, White E, Amon A. Aneuploidy-induced cellular stresses limit autophagic degradation. Genes Dev 2015; 29:2010-21. [PMID: 26404941 PMCID: PMC4604343 DOI: 10.1101/gad.269118.115] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 09/04/2015] [Indexed: 11/24/2022]
Abstract
An unbalanced karyotype, a condition known as aneuploidy, has a profound impact on cellular physiology and is a hallmark of cancer. Aneuploid cells experience a number of stresses that are caused by aneuploidy-induced proteomic changes. How the aneuploidy-associated stresses affect cells and whether cells respond to them are only beginning to be understood. Here we show that autophagosomal cargo such as protein aggregates accumulate within lysosomes in aneuploid cells. This causes a lysosomal stress response. Aneuploid cells activate the transcription factor TFEB, a master regulator of autophagic and lysosomal gene expression, thereby increasing the expression of genes needed for autophagy-mediated protein degradation. Accumulation of autophagic cargo within the lysosome and activation of TFEB-responsive genes are also observed in cells in which proteasome function is inhibited, suggesting that proteotoxic stress causes TFEB activation. Our results reveal a TFEB-mediated lysosomal stress response as a universal feature of the aneuploid state.
Collapse
Affiliation(s)
- Stefano Santaguida
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138, USA
| | - Eliza Vasile
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138, USA
| | - Eileen White
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903-2681 USA
| | - Angelika Amon
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138, USA
| |
Collapse
|
252
|
Gruia AT, Suciu M, Barbu-Tudoran L, Azghadi SMR, Cristea MI, Nica DV, Vaduva A, Muntean D, Mic AA, Mic FA. Mesenchymal Stromal Cells Differentiating to Adipocytes Accumulate Autophagic Vesicles Instead of Functional Lipid Droplets. J Cell Physiol 2015; 231:863-75. [DOI: 10.1002/jcp.25177] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/28/2015] [Indexed: 12/25/2022]
Affiliation(s)
- Alexandra T. Gruia
- Regional Center for Immunology of Transplantation; Clinical Emergency County Hospital; 10 Iosif Bulbuca Blvd. 300736 Timisoara Romania
| | - Maria Suciu
- Department of Functional Sciences; “Victor Babes” University of Medicine and Pharmacy; 2 Eftimie Murgu Sq. 300041 Timisoara Romania
| | | | - Seyed Mohammad Reza Azghadi
- Department of Functional Sciences; “Victor Babes” University of Medicine and Pharmacy; 2 Eftimie Murgu Sq. 300041 Timisoara Romania
| | - Mirabela I. Cristea
- Regional Center for Immunology of Transplantation; Clinical Emergency County Hospital; 10 Iosif Bulbuca Blvd. 300736 Timisoara Romania
| | - Dragos V. Nica
- Department of Functional Sciences; “Victor Babes” University of Medicine and Pharmacy; 2 Eftimie Murgu Sq. 300041 Timisoara Romania
- Faculty of Animal Sciences and Biotechnologies; Banat's University of Agricultural Sciences and Veterinary Medicine; Timisoara Romania
| | - Adrian Vaduva
- Department of Microscopical Morphology-Morphopathology; “Victor Babes” University of Medicine and Pharmacy; 2 Eftimie Murgu Square, 300041 Timisoara Romania
| | - Danina Muntean
- Department of Pathophysiology; “Victor Babeş” University of Medicine and Pharmacy of Timişoara; 14 Tudor Vladimirescu st. 300173 Timisoara Romania
| | - Ani Aurora Mic
- Department of Functional Sciences; “Victor Babes” University of Medicine and Pharmacy; 2 Eftimie Murgu Sq. 300041 Timisoara Romania
- INCD “Victor Babes” Bucuresti; Romania
| | - Felix A. Mic
- Department of Functional Sciences; “Victor Babes” University of Medicine and Pharmacy; 2 Eftimie Murgu Sq. 300041 Timisoara Romania
| |
Collapse
|
253
|
Biological and Nutritional Properties of Palm Oil and Palmitic Acid: Effects on Health. Molecules 2015; 20:17339-61. [PMID: 26393565 PMCID: PMC6331788 DOI: 10.3390/molecules200917339] [Citation(s) in RCA: 181] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/02/2015] [Accepted: 09/09/2015] [Indexed: 12/13/2022] Open
Abstract
A growing body of evidence highlights the close association between nutrition and human health. Fat is an essential macronutrient, and vegetable oils, such as palm oil, are widely used in the food industry and highly represented in the human diet. Palmitic acid, a saturated fatty acid, is the principal constituent of refined palm oil. In the last few decades, controversial studies have reported potential unhealthy effects of palm oil due to the high palmitic acid content. In this review we provide a concise and comprehensive update on the functional role of palm oil and palmitic acid in the development of obesity, type 2 diabetes mellitus, cardiovascular diseases and cancer. The atherogenic potential of palmitic acid and its stereospecific position in triacylglycerols are also discussed.
Collapse
|
254
|
Mitter SK, Song C, Qi X, Mao H, Rao H, Akin D, Lewin A, Grant M, Dunn W, Ding J, Bowes Rickman C, Boulton M. Dysregulated autophagy in the RPE is associated with increased susceptibility to oxidative stress and AMD. Autophagy 2015; 10:1989-2005. [PMID: 25484094 DOI: 10.4161/auto.36184] [Citation(s) in RCA: 333] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Autophagic dysregulation has been suggested in a broad range of neurodegenerative diseases including age-related macular degeneration (AMD). To test whether the autophagy pathway plays a critical role to protect retinal pigmented epithelial (RPE) cells against oxidative stress, we exposed ARPE-19 and primary cultured human RPE cells to both acute (3 and 24 h) and chronic (14 d) oxidative stress and monitored autophagy by western blot, PCR, and autophagosome counts in the presence or absence of autophagy modulators. Acute oxidative stress led to a marked increase in autophagy in the RPE, whereas autophagy was reduced under chronic oxidative stress. Upregulation of autophagy by rapamycin decreased oxidative stress-induced generation of reactive oxygen species (ROS), whereas inhibition of autophagy by 3-methyladenine (3-MA) or by knockdown of ATG7 or BECN1 increased ROS generation, exacerbated oxidative stress-induced reduction of mitochondrial activity, reduced cell viability, and increased lipofuscin. Examination of control human donor specimens and mice demonstrated an age-related increase in autophagosome numbers and expression of autophagy proteins. However, autophagy proteins, autophagosomes, and autophagy flux were significantly reduced in tissue from human donor AMD eyes and 2 animal models of AMD. In conclusion, our data confirm that autophagy plays an important role in protection of the RPE against oxidative stress and lipofuscin accumulation and that impairment of autophagy is likely to exacerbate oxidative stress and contribute to the pathogenesis of AMD.
Collapse
Key Words
- 3-MA, 3-methyladenine
- ACTB, β-actin
- AMD, age-related macular degeneration
- APOE4, apolipoprotein E4
- FACS, fluorescence-activated cell sorting
- FBS, fetal bovine serum
- GFP, green fluorescent protein
- GSH, glutathione, reduced
- GSSG, glutathione, oxidized
- H2O2, hydrogen peroxide
- HFC, high fat, cholesterol-enriched diet
- LC3, microtubule-associated protein 1 light chain 3
- MMP, mitochondrial membrane potential
- MTT, 3-(4 5-dimethylthiazol-3-yl)-2, 5-diphenyl tetrazolium bromide
- ND, normal (rodent) diet
- POS, photoreceptor outer segments
- ROS, reactive oxygen species
- RPE
- RPE, retinal pigmented epithelium
- SOD2/MnSOD, superoxide dismutase 2, mitochondrial
- UPS, ubiquitin-proteasome system
- age-related macular degeneration
- aging
- autophagy
- oxidative stress
Collapse
Affiliation(s)
- Sayak K Mitter
- a Department of Ophthalmology ; Indiana University School of Medicine ; Indianapolis , IN USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
255
|
Stinkens R, Goossens GH, Jocken JWE, Blaak EE. Targeting fatty acid metabolism to improve glucose metabolism. Obes Rev 2015; 16:715-57. [PMID: 26179344 DOI: 10.1111/obr.12298] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/23/2015] [Accepted: 05/10/2015] [Indexed: 12/15/2022]
Abstract
Disturbances in fatty acid metabolism in adipose tissue, liver, skeletal muscle, gut and pancreas play an important role in the development of insulin resistance, impaired glucose metabolism and type 2 diabetes mellitus. Alterations in diet composition may contribute to prevent and/or reverse these disturbances through modulation of fatty acid metabolism. Besides an increased fat mass, adipose tissue dysfunction, characterized by an altered capacity to store lipids and an altered secretion of adipokines, may result in lipid overflow, systemic inflammation and excessive lipid accumulation in non-adipose tissues like liver, skeletal muscle and the pancreas. These impairments together promote the development of impaired glucose metabolism, insulin resistance and type 2 diabetes mellitus. Furthermore, intrinsic functional impairments in either of these organs may contribute to lipotoxicity and insulin resistance. The present review provides an overview of fatty acid metabolism-related pathways in adipose tissue, liver, skeletal muscle, pancreas and gut, which can be targeted by diet or food components, thereby improving glucose metabolism.
Collapse
Affiliation(s)
- R Stinkens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - G H Goossens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - J W E Jocken
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - E E Blaak
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| |
Collapse
|
256
|
Watson GW, Wickramasekara S, Fang Y, Palomera-Sanchez Z, Maier CS, Williams DE, Dashwood RH, Perez VI, Ho E. Analysis of autophagic flux in response to sulforaphane in metastatic prostate cancer cells. Mol Nutr Food Res 2015; 59:1954-61. [PMID: 26108801 DOI: 10.1002/mnfr.201500283] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 06/11/2015] [Accepted: 06/16/2015] [Indexed: 12/21/2022]
Abstract
SCOPE The phytochemical sulforaphane (SF) has been shown to decrease prostate cancer metastases in a genetic mouse model of prostate carcinogenesis, though the mechanism of action is not fully known. SF has been reported to stimulate autophagy, and modulation of autophagy has been proposed to influence SF cytotoxicity; however, no conclusions about autophagy can be drawn without assessing autophagic flux, which has not been characterized in prostate cancer cells following SF treatment. METHODS AND RESULTS We conducted an investigation to assess the impact of SF on autophagic flux in two metastatic prostate cancer cell lines at a concentration shown to decrease metastasis in vivo. Autophagic flux was assessed by multiple autophagy related proteins and substrates. We found that SF can stimulate autophagic flux and cell death only at high concentrations, above what has been observed in vivo. CONCLUSION These results suggest that SF does not directly stimulate autophagy or cell death in metastatic prostate cancer cells under physiologically relevant conditions, but instead supports the involvement of in vivo factors as important effectors of SF-mediated prostate cancer suppression.
Collapse
Affiliation(s)
- Gregory W Watson
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, OR, USA.,Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | | | - Yufeng Fang
- Genetics, Bioinformatics & Computational Biology, Virginia Tech, Blacksburg, VA, USA
| | | | - Claudia S Maier
- Department of Chemistry, Oregon State University, Corvallis, OR, USA
| | - David E Williams
- Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA.,Linus Pauling Institute, Oregon State University, Corvallis, OR, USA
| | - Roderick H Dashwood
- Center for Epigenetics and Disease Prevention, Institute of Biosciences and Technology, Texas A&M Science Center, Houston, TX, USA.,Department of Nutrition & Food Science, Texas A&M University, College Station, TX, USA.,Department of Clinical Cancer Prevention, MD Anderson Cancer Center, Houston, TX, USA.,Department of Molecular & Cellular Medicine, Texas A&M University College of Medicine, College Station, TX, USA
| | - Viviana I Perez
- Linus Pauling Institute, Oregon State University, Corvallis, OR, USA.,Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, USA
| | - Emily Ho
- Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA.,Linus Pauling Institute, Oregon State University, Corvallis, OR, USA
| |
Collapse
|
257
|
Schroeder B, McNiven MA. Importance of endocytic pathways in liver function and disease. Compr Physiol 2015; 4:1403-17. [PMID: 25428849 DOI: 10.1002/cphy.c140001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hepatocellular endocytosis is a highly dynamic process responsible for the internalization of a variety of different receptor ligand complexes, trophic factors, lipids, and, unfortunately, many different pathogens. The uptake of these external agents has profound effects on seminal cellular processes including signaling cascades, migration, growth, and proliferation. The hepatocyte, like other well-polarized epithelial cells, possesses a host of different endocytic mechanisms and entry routes to ensure the selective internalization of cargo molecules. These pathways include receptor-mediated endocytosis, lipid raft associated endocytosis, caveolae, or fluid-phase uptake, although there are likely many others. Understanding and defining the regulatory mechanisms underlying these distinct entry routes, sorting and vesicle formation, as well as the postendocytic trafficking pathways is of high importance especially in the liver, as their mis-regulation can contribute to aberrant liver pathology and liver diseases. Further, these processes can be "hijacked" by a variety of different infectious agents and viruses. This review provides an overview of common components of the endocytic and postendocytic trafficking pathways utilized by hepatocytes. It will also discuss in more detail how these general themes apply to liver-specific processes including iron homeostasis, HBV infection, and even hepatic steatosis.
Collapse
Affiliation(s)
- Barbara Schroeder
- Department of Biochemistry and Molecular Biology, Center for Basic Research in Digestive Diseases, Mayo Clinic and Foundation, Rochester, Minnesota
| | | |
Collapse
|
258
|
Zheng C, Sun Q, Zhang L, Guo S, Zheng M, Tang Y, Wu J, Wu J, Liu W, Su Z, Chen X. Autophagosome activity in macrophage for atherosclerotic plaques in ApoE−/− mice enhanced by Tiaozhi Tongmai Granules. JOURNAL OF TRADITIONAL CHINESE MEDICAL SCIENCES 2015. [DOI: 10.1016/j.jtcms.2016.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
259
|
Aon MA, Tocchetti CG, Bhatt N, Paolocci N, Cortassa S. Protective mechanisms of mitochondria and heart function in diabetes. Antioxid Redox Signal 2015; 22:1563-86. [PMID: 25674814 PMCID: PMC4449630 DOI: 10.1089/ars.2014.6123] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
SIGNIFICANCE The heart depends on continuous mitochondrial ATP supply and maintained redox balance to properly develop force, particularly under increased workload. During diabetes, however, myocardial energetic-redox balance is perturbed, contributing to the systolic and diastolic dysfunction known as diabetic cardiomyopathy (DC). CRITICAL ISSUES How these energetic and redox alterations intertwine to influence the DC progression is still poorly understood. Excessive bioavailability of both glucose and fatty acids (FAs) play a central role, leading, among other effects, to mitochondrial dysfunction. However, where and how this nutrient excess affects mitochondrial and cytoplasmic energetic/redox crossroads remains to be defined in greater detail. RECENT ADVANCES We review how high glucose alters cellular redox balance and affects mitochondrial DNA. Next, we address how lipid excess, either stored in lipid droplets or utilized by mitochondria, affects performance in diabetic hearts by influencing cardiac energetic and redox assets. Finally, we examine how the reciprocal energetic/redox influence between mitochondrial and cytoplasmic compartments shapes myocardial mechanical activity during the course of DC, focusing especially on the glutathione and thioredoxin systems. FUTURE DIRECTIONS Protecting mitochondria from losing their ability to generate energy, and to control their own reactive oxygen species emission is essential to prevent the onset and/or to slow down DC progression. We highlight mechanisms enforced by the diabetic heart to counteract glucose/FAs surplus-induced damage, such as lipid storage, enhanced mitochondria-lipid droplet interaction, and upregulation of key antioxidant enzymes. Learning more on the nature and location of mechanisms sheltering mitochondrial functions would certainly help in further optimizing therapies for human DC.
Collapse
Affiliation(s)
- Miguel A Aon
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Carlo G Tocchetti
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Niraj Bhatt
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Nazareno Paolocci
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sonia Cortassa
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| |
Collapse
|
260
|
Deciphering non-alcoholic fatty liver disease through metabolomics. Biochem Soc Trans 2015; 42:1447-52. [PMID: 25233430 DOI: 10.1042/bst20140138] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver disorders in industrialized countries. NAFLD develops in the absence of alcohol abuse and encompasses a wide spectrum of disorders ranging from benign fatty liver to non-alcoholic steatohepatitis (NASH). NASH often leads to fibrosis, cirrhosis and, finally, hepatocellular carcinoma (HCC). Therefore the earlier NAFLD is diagnosed, the better the patient's outlook. A tightly connected basic and applied research is essential to find the molecular mechanisms that accompany illness and to translate them into the clinic. From the simple starting point for triacylglycerol (TG) accumulation in the liver to the more complex implications of phospholipids in membrane biophysics, the influence of lipids may be the clue to understand NAFLD pathophysiology. Nowadays, it is achievable to diagnose non-invasively the initial symptoms to stop, revert or even prevent disease development. In this context, merging metabolomics with other techniques and the interpretation of the huge information obtained resembles the 'Rosetta stone' to decipher the pathological metabolic fluxes that must be targeted to find a cure. In the present review, we have tackled the application of metabolomics to find out the metabolic fluxes that underlie membrane integrity in NAFLD.
Collapse
|
261
|
Robey RB, Weisz J, Kuemmerle NB, Salzberg AC, Berg A, Brown DG, Kubik L, Palorini R, Al-Mulla F, Al-Temaimi R, Colacci A, Mondello C, Raju J, Woodrick J, Scovassi AI, Singh N, Vaccari M, Roy R, Forte S, Memeo L, Salem HK, Amedei A, Hamid RA, Williams GP, Lowe L, Meyer J, Martin FL, Bisson WH, Chiaradonna F, Ryan EP. Metabolic reprogramming and dysregulated metabolism: cause, consequence and/or enabler of environmental carcinogenesis? Carcinogenesis 2015; 36 Suppl 1:S203-31. [PMID: 26106140 PMCID: PMC4565609 DOI: 10.1093/carcin/bgv037] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 02/21/2015] [Accepted: 02/24/2015] [Indexed: 12/20/2022] Open
Abstract
Environmental contributions to cancer development are widely accepted, but only a fraction of all pertinent exposures have probably been identified. Traditional toxicological approaches to the problem have largely focused on the effects of individual agents at singular endpoints. As such, they have incompletely addressed both the pro-carcinogenic contributions of environmentally relevant low-dose chemical mixtures and the fact that exposures can influence multiple cancer-associated endpoints over varying timescales. Of these endpoints, dysregulated metabolism is one of the most common and recognizable features of cancer, but its specific roles in exposure-associated cancer development remain poorly understood. Most studies have focused on discrete aspects of cancer metabolism and have incompletely considered both its dynamic integrated nature and the complex controlling influences of substrate availability, external trophic signals and environmental conditions. Emerging high throughput approaches to environmental risk assessment also do not directly address the metabolic causes or consequences of changes in gene expression. As such, there is a compelling need to establish common or complementary frameworks for further exploration that experimentally and conceptually consider the gestalt of cancer metabolism and its causal relationships to both carcinogenesis and the development of other cancer hallmarks. A literature review to identify environmentally relevant exposures unambiguously linked to both cancer development and dysregulated metabolism suggests major gaps in our understanding of exposure-associated carcinogenesis and metabolic reprogramming. Although limited evidence exists to support primary causal roles for metabolism in carcinogenesis, the universality of altered cancer metabolism underscores its fundamental biological importance, and multiple pleiomorphic, even dichotomous, roles for metabolism in promoting, antagonizing or otherwise enabling the development and selection of cancer are suggested.
Collapse
Affiliation(s)
- R Brooks Robey
- Research and Development Service, Veterans Affairs Medical Center, White River Junction, VT 05009, USA, Departments of Medicine and of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH 03756, USA,
| | - Judith Weisz
- Departments of Gynecology and Pathology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Nancy B Kuemmerle
- Research and Development Service, Veterans Affairs Medical Center, White River Junction, VT 05009, USA, Departments of Medicine and of
| | - Anna C Salzberg
- Departments of Gynecology and Pathology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Arthur Berg
- Departments of Gynecology and Pathology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Dustin G Brown
- Department of Environmental and Radiological Health Sciences, Colorado State University/Colorado School of Public Health, Fort Collins, CO 80523, USA
| | - Laura Kubik
- Nicholas School of the Environment, Duke University, Durham, NC 27708, USA
| | - Roberta Palorini
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, 20126, Italy, SYSBIO Center for Systems Biology, Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan 20126, Italy
| | - Fahd Al-Mulla
- Department of Pathology, Kuwait University, Safat 13110, Kuwait
| | | | - Annamaria Colacci
- Center for Environmental Carcinogenesis and Risk Assessment, Environmental Protection and Health Prevention Agency, Bologna, 40126, Italy
| | - Chiara Mondello
- Institute of Molecular Genetics, National Research Council, Pavia 27100, Italy
| | - Jayadev Raju
- Toxicology Research Division, Bureau of Chemical Safety Food Directorate, Health Products and Food Branch Health Canada, Ottawa, Ontario K1A0K9, Canada
| | - Jordan Woodrick
- Molecular Oncology Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20057 USA
| | - A Ivana Scovassi
- Institute of Molecular Genetics, National Research Council, Pavia 27100, Italy
| | - Neetu Singh
- Advanced Molecular Science Research Centre, King George's Medical University, Lucknow Uttar Pradesh 226003, India
| | - Monica Vaccari
- Center for Environmental Carcinogenesis and Risk Assessment, Environmental Protection and Health Prevention Agency, Bologna, 40126, Italy
| | - Rabindra Roy
- Molecular Oncology Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20057 USA
| | - Stefano Forte
- Mediterranean Institute of Oncology, Viagrande 95029, Italy
| | - Lorenzo Memeo
- Mediterranean Institute of Oncology, Viagrande 95029, Italy
| | - Hosni K Salem
- Urology Department, kasr Al-Ainy School of Medicine, Cairo University, El Manial, Cairo, 12515, Egypt
| | - Amedeo Amedei
- Department of Experimental and Clinical Medicine, University of Firenze, Firenze, 50134, Italy
| | - Roslida A Hamid
- Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia
| | - Graeme P Williams
- Department of Molecular Medicine, University of Reading, Reading RG6 6UB, UK
| | - Leroy Lowe
- Centre for Biophotonics, LEC, Lancaster University, Bailrigg, Lancaster LA1 4YQ, UK, Getting to Know Cancer, Truro, Nova Scotia B2N 1X5, Canada, and
| | - Joel Meyer
- Nicholas School of the Environment, Duke University, Durham, NC 27708, USA
| | - Francis L Martin
- Centre for Biophotonics, LEC, Lancaster University, Bailrigg, Lancaster LA1 4YQ, UK
| | - William H Bisson
- Environmental and Molecular Toxicology, Environmental Health Science Center, Oregon State University, Corvallis, OR 97331, USA
| | - Ferdinando Chiaradonna
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, 20126, Italy, SYSBIO Center for Systems Biology, Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan 20126, Italy
| | - Elizabeth P Ryan
- Department of Environmental and Radiological Health Sciences, Colorado State University/Colorado School of Public Health, Fort Collins, CO 80523, USA
| |
Collapse
|
262
|
Abstract
The metabolism of malignant cells is profoundly altered in order to maintain their survival and proliferation in adverse microenvironmental conditions. Autophagy is an intracellular recycling process that maintains basal levels of metabolites and biosynthetic intermediates under starvation or other forms of stress, hence serving as an important mechanism for metabolic adaptation in cancer cells. Although it is widely acknowledged that autophagy sustains metabolism in neoplastic cells under duress, many questions remain with regard to the mutual relationship between autophagy and metabolism in cancer. Importantly, autophagy has often been described as a "double-edged sword" that can either impede or promote cancer initiation and progression. Here, we overview such a dual function of autophagy in tumorigenesis and our current understanding of the coordinated regulation of autophagy and cancer cell metabolism in the control of tumor growth, progression, and resistance to therapy.
Collapse
|
263
|
Ríos-Marco P, Ríos A, Jiménez-López JM, Carrasco MP, Marco C. Cholesterol homeostasis and autophagic flux in perifosine-treated human hepatoblastoma HepG2 and glioblastoma U-87 MG cell lines. Biochem Pharmacol 2015; 96:10-9. [PMID: 25934232 DOI: 10.1016/j.bcp.2015.04.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 04/23/2015] [Indexed: 12/20/2022]
Abstract
Perifosine exerts an antiproliferative effect on HepG2 and U-87 MG cells and also interferes with the transport of cholesterol from the plasma membrane to the endoplasmic reticulum (ER). Recently we demonstrated that exposure of U-87 MG cells to perifosine causes an accumulation of autophagosomes. We have now expanded the study to establish the molecular mechanism by which perifosine interferes with the autophagic process. Using transmission electron microscopy, we report that the treatment of HepG2 and U-87 MG cells with perifosine causes an intense cytoplasmic vacuolization identified as autophagic vesicles. The accumulation of autophagosomes induced by perifosine is due to a blockage of the autophagic flux, thereby affecting cell proliferation. Perifosine also provokes a differential ER stress response in the HepG2 and U-87 MG cell lines. We have also demonstrated a relationship between the deregulation of cholesterol transport and the inhibition of the autophagic flux prompted by perifosine. Thus our findings clearly demonstrate that perifosine impairs the autophagic flux in HepG2 and U-87 MG cells, which is related to defects in intracellular cholesterol transport. Our study is relevant for anticancer therapy because tumour cells exhibit autophagy as a pro-survival mechanism. Further research to identify the precise mechanisms of autophagy maturation and the role of cholesterol may provide new insights into the antiproliferative action of perifosine.
Collapse
Affiliation(s)
- Pablo Ríos-Marco
- Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, Granada 18071, Spain(2)
| | - Antonio Ríos
- Department of Cell Biology, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, Granada 18071, Spain(3)
| | - José M Jiménez-López
- Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, Granada 18071, Spain(2)
| | - María P Carrasco
- Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, Granada 18071, Spain(2).
| | - Carmen Marco
- Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, Granada 18071, Spain(2).
| |
Collapse
|
264
|
Ghosh A, Jana M, Modi K, Gonzalez FJ, Sims KB, Berry-Kravis E, Pahan K. Activation of peroxisome proliferator-activated receptor α induces lysosomal biogenesis in brain cells: implications for lysosomal storage disorders. J Biol Chem 2015; 290:10309-24. [PMID: 25750174 PMCID: PMC4400343 DOI: 10.1074/jbc.m114.610659] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 03/04/2015] [Indexed: 11/06/2022] Open
Abstract
Lysosomes are ubiquitous membrane-enclosed organelles filled with an acidic interior and are central to the autophagic, endocytic, or phagocytic pathway. In contrast to its classical function as the waste management machinery, lysosomes are now considered to be an integral part of various cellular signaling processes. The diverse functionality of this single organelle requires a very complex and coordinated regulation of its activity with transcription factor EB (TFEB), a master regulator of lysosomal biogenesis, at its core. However, mechanisms by which TFEB is regulated are poorly understood. This study demonstrates that gemfibrozil, an agonist of peroxisome proliferator-activated receptor (PPAR) α, alone and in conjunction with all-trans-retinoic acid is capable of enhancing TFEB in brain cells. We also observed that PPARα, but not PPARβ and PPARγ, is involved in gemfibrozil-mediated up-regulation of TFEB. Reporter assay and chromatin immunoprecipitation studies confirmed the recruitment of retinoid X receptor α, PPARα, and PGC1α on the PPAR-binding site on the Tfeb promoter as well. Subsequently, the drug-mediated induction of TFEB caused an increase in lysosomal protein and the lysosomal abundance in cell. Collectively, this study reinforces the link between lysosomal biogenesis and lipid metabolism with TFEB at the crossroads. Furthermore, gemfibrozil may be of therapeutic value in the treatment of lysosomal storage disorders in which autophagy-lysosome pathway plays an important role.
Collapse
Affiliation(s)
| | | | - Khushbu Modi
- From the Departments of Neurological Sciences and
| | - Frank J Gonzalez
- the Laboratory of Metabolism, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Katherine B Sims
- the Department of Neurology, Harvard Medical School, Boston, Massachusetts 02114, and
| | - Elizabeth Berry-Kravis
- Pediatrics, Neurological Sciences, and Biochemistry, Rush University Medical Center, Chicago, Illinois 60612
| | - Kalipada Pahan
- From the Departments of Neurological Sciences and the Division of Research and Development, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois 60612
| |
Collapse
|
265
|
The role of oxidative stress and autophagy in atherosclerosis. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2015:130315. [PMID: 25866599 PMCID: PMC4381688 DOI: 10.1155/2015/130315] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Revised: 03/01/2015] [Accepted: 03/02/2015] [Indexed: 02/07/2023]
Abstract
Atherosclerosis is a multifactorial, multistep disorder of large- and medium-sized arteries involving, in addition to age, gender and menopausal status, a complex interplay between lifestyle and genetic risk factors. Atherosclerosis usually begins with the diffusion and retention of atherogenic lipoproteins into the subendothelial space of the artery wall where they become oxidized by local enzymes and accumulate, leading to the formation of a cushion called atheroma or atheromatous or fibrofatty plaque, composed of a mixture of macrophages, lymphocytes, smooth muscle cells (SMCs), cholesterol cleft, necrotic debris, and lipid-laden foam cells. The pathogenesis of atherosclerosis still remains incompletely understood but emerging evidence suggests that it may involve multiple cellular events, including endothelial cell (EC) dysfunction, inflammation, proliferation of vascular SMCs, matrix (ECM) alteration, and neovascularization. Actually, a growing body of evidence indicates that autophagy along with the chronic and acute overproduction of reactive oxygen species (ROS) is integral to the development and progression of the disease and may represent fruitful avenues for biological investigation and for the identification of new therapeutic targets. In this review, we give an overview of ROS and autophagy in atherosclerosis as background to understand their potential role in this vascular disease.
Collapse
|
266
|
Guo R, Xu X, Babcock SA, Zhang Y, Ren J. Aldehyde dedydrogenase-2 plays a beneficial role in ameliorating chronic alcohol-induced hepatic steatosis and inflammation through regulation of autophagy. J Hepatol 2015; 62:647-56. [PMID: 25457208 PMCID: PMC4336638 DOI: 10.1016/j.jhep.2014.10.009] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/08/2014] [Accepted: 10/08/2014] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS Mitochondrial aldehyde dehydrogenase (ALDH2) plays a critical role in the detoxification of the ethanol metabolite acetaldehyde. This study was designed to examine the impact of global ALDH2 overexpression on alcohol-induced hepatic steatosis. METHODS Wild type Friend virus B (FVB) and ALDH2 transgenic mice were placed on a 4% alcohol or control diet for 12 weeks. Serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), bilirubin and cholesterol, hepatic triglyceride, steatosis, fat metabolism-related proteins, pro-inflammatory cytokines, glutathione (GSH), oxidized glutathione (GSSG), autophagy and autophagy signalling were examined. The role of autophagy was evaluated in alcohol dehydrogenase 1 (ADH1)-transfected human hepatocellular liver carcinoma cells (VA-13) treated with or without the autophagy inducer rapamycin and lysosomal inhibitors. RESULTS Chronic alcohol intake led to elevated AST-, ALT-levels, bilirubin, AST/ALT ratio, cholesterol, hepatic triglycerides and hepatic fat deposition as evidenced by H&E and Oil Red O staining. Hepatic fat deposition was associated with disturbed levels of fat metabolism-related proteins (fatty acid synthase, SCD1), upregulated interleukin-6, TNF-α, cyclooxygenase, oxidative stress, and loss of autophagy, effects which were attenuated or ablated by the ALDH2 transgene. Moreover, ethanol (100 mM) and acetaldehyde (100 and 500 μM) increased levels of IL-6 and IFN-γ, and suppressed autophagy in VA-13 cells, effects which were markedly alleviated by rapamycin. In addition, lysosomal inhibitors mimicked ethanol-induced p62 accumulation with little additive effect with ethanol. Ethanol significantly suppressed LC3 conversion in the presence of lysosomal inhibitors. CONCLUSIONS In summary, our results revealed that ALDH2 plays a beneficial role in ameliorating chronic alcohol intake-induced hepatic steatosis and inflammation through regulation of autophagy.
Collapse
Affiliation(s)
- Rui Guo
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, USA
| | - Xihui Xu
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, USA
| | - Sara A Babcock
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, USA
| | - Yingmei Zhang
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, USA; Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an, China; Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai, China.
| | - Jun Ren
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, USA; Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai, China.
| |
Collapse
|
267
|
Autophagy induction halts axonal degeneration in a mouse model of X-adrenoleukodystrophy. Acta Neuropathol 2015; 129:399-415. [PMID: 25549970 PMCID: PMC4331612 DOI: 10.1007/s00401-014-1378-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 12/11/2014] [Accepted: 12/19/2014] [Indexed: 01/25/2023]
Abstract
X-linked adrenoleukodystrophy (X-ALD) is a rare neurometabolic disease characterized by the accumulation of very long chain fatty acids (VLCFAs) due to a loss of function of the peroxisomal transporter ABCD1. Here, using in vivo and in vitro models, we demonstrate that autophagic flux was impaired due to elevated mammalian target of rapamycin (mTOR) signaling, which contributed to X-ALD pathogenesis. We also show that excess VLCFAs downregulated autophagy in human fibroblasts. Furthermore, mTOR inhibition by a rapamycin derivative (temsirolimus) restored autophagic flux and inhibited the axonal degenerative process as well as the associated locomotor impairment in the Abcd1−/Abcd2−/− mouse model. This process was mediated through the restoration of proteasome function and redox as well as metabolic homeostasis. These findings provide the first evidence that links impaired autophagy to X-ALD, which may yield a therapy based on autophagy activators for adrenomyeloneuropathy patients.
Collapse
|
268
|
Wang D, Tian M, Qi Y, Chen G, Xu L, Zou X, Wang K, Dong H, Lu F. Jinlida granule inhibits palmitic acid induced-intracellular lipid accumulation and enhances autophagy in NIT-1 pancreatic β cells through AMPK activation. JOURNAL OF ETHNOPHARMACOLOGY 2015; 161:99-107. [PMID: 25510732 DOI: 10.1016/j.jep.2014.12.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/06/2014] [Accepted: 12/01/2014] [Indexed: 06/04/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Jinlida granule (JLDG), composed of seventeen Chinese medical herbs, is a widely used Chinese herbal prescription for treating diabetes mellitus. However, the mechanism underlying this effect remains unclear. To determine the main components in JLDG and to explore the effect of JLDG on autophagy and lipid accumulation in NIT-1 pancreatic β cells exposed to politic acid (PA) through AMP activated protein kinase (AMPK) signaling pathway. MATERIALS AND METHODS JLDG was prepared and the main components contained in the granules were identified by ultra performance liquid chromatography (UPLC) fingerprint. Intracellular lipid accumulation in NIT-1 cells was induced by culturing with medium containing PA. Intracellular lipid droplets were observed by Oil Red O staining and triglyceride (TG) content was measured by colorimetric assay. The formation of autophagosomes was observed under transmission electron microscope. The expression of AMPK and phospho-AMPK (pAMPK) proteins as well as its downstream fatty acid metabolism-related proteins (fatty acid synthase, FAS; acetyl-coA carboxylase, ACC; carnitine acyltransferase 1, CPT-1) and autophagy-related genes (mammal target of rapamycin, mTOR; tuberous sclerosis complex 1, TSC1; microtubule-associated protein 1 light chain 3, LC3-II) were determined by Western blot. The expression of sterol regulating element binding protein 1c (SREBP-1c) mRNA was examined by real time PCR (RT-PCR). RESULTS Our data showed that JLDG could significantly reduce PA-induced intracellular lipid accumulation in NIT-1 pancreatic β cells. This effect was associated with increased protein expression of pAMPK and AMPK in NIT-1 cells. Treatment with JLDG also decreased the expression of AMPK downstream lipogenic genes (SREBP-1c mRNA, FAS and ACC proteins) whereas increased the expression of fatty acid oxidation gene (CPT-1 protein). Additionally, JLDG-treated cells displayed a markedly increase in the number of autophagosomes which was accompanied by the down-regulation of mTOR and the up-regulation of TSC1 and LC3-II proteins expression. However, when AMPK phosphorylation was inhibited by Compound C, JLDG supplementation did not exhibit any effect on the expression of these AMPK downstream molecules in NIT-1 cells. CONCLUSIONS The results suggest that JLDG could reduce intracellular lipid accumulation and enhance the autophagy in NIT-1 pancreatic β cells cultured with PA. The mechanism is possibly mediated by AMPK activation.
Collapse
Affiliation(s)
- Dingkun Wang
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Min Tian
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Yuan Qi
- Shijiazhuang YiLing Pharmaceutical Co., Ltd., Shijiazhuang, Hebei 050035, China
| | - Guang Chen
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Lijun Xu
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Xin Zou
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Kaifu Wang
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Hui Dong
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
| | - Fuer Lu
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
| |
Collapse
|
269
|
Hashemi HF, Goodman JM. The life cycle of lipid droplets. Curr Opin Cell Biol 2015; 33:119-24. [PMID: 25703629 DOI: 10.1016/j.ceb.2015.02.002] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 01/28/2015] [Accepted: 02/02/2015] [Indexed: 01/14/2023]
Abstract
Proteomic studies have revealed many potential functions of cytoplasmic lipid droplets, and recent activity has confirmed that these bona fide organelles are central not only for lipid storage and metabolism, but for development, immunity, and pathogenesis by several microbes. There has been a burst of recent activity on the assembly, maintenance and turnover of lipid droplets that reveals fresh insights. This review summarizes several novel findings in initiation of lipid droplet assembly, protein targeting, droplet fusion, and turnover of droplets through lipophagy.
Collapse
Affiliation(s)
- Hayaa F Hashemi
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9041, United States
| | - Joel M Goodman
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9041, United States.
| |
Collapse
|
270
|
From Human-Induced Pluripotent Stem Cells to Liver Disease Modeling: A Focus on Dyslipidemia. CURRENT PATHOBIOLOGY REPORTS 2015. [DOI: 10.1007/s40139-015-0067-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
271
|
Cha YH, Yook JI, Kim HS, Kim NH. Catabolic metabolism during cancer EMT. Arch Pharm Res 2015; 38:313-20. [PMID: 25634102 DOI: 10.1007/s12272-015-0567-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/20/2015] [Indexed: 01/16/2023]
Abstract
Aerobic glycolysis is widely accepted as the glucose metabolism for production of biomass such as nucleotides, amino acids, and fatty acids which underlie the anabolic process of cancer cell proliferation. The epithelial-mesenchymal transition (EMT) is a complex cellular mechanism for invasion and metastatic progression in cancer cells. While Snail-mediated EMT regulated by major oncogenic signaling has been well-studied over the last decade, metabolic reprogramming during the EMT has not. In this work, we emphasize the importance of catabolic metabolism for cancer cell survival during cancer cell EMT. Because specific catabolic processes such as autophage and fatty acid oxidation have been well explained, we mainly focus on the general aspects of energy metabolism promoting cancer cell survival under metabolic stress. We also revisit the role of mitochondria in catabolism as oxidative phosphorylation in cancer has long been underestimated. Considering the highly inefficient process of metastatic progression and profound metabolic stress following matrix detachment of solid cancer, catabolic reprogramming during the EMT may play an important role in overcoming metastatic inefficiency of cancer cells.
Collapse
Affiliation(s)
- Yong Hoon Cha
- Department of Oral Pathology, Oral Cancer Research Institute, Yonsei University College of Dentistry, Seoul, 120-752, Korea
| | | | | | | |
Collapse
|
272
|
Abstract
Autophagy is a catabolic process mediated by incorporation of cellular material into cytosolic membrane vesicles for lysosomal degradation. It is crucial for maintaining cell viability and homeostasis in response to numerous stressful conditions. In this Review, the role of autophagy in both normal biology and disease is discussed. Emphasis is given to the interplay of autophagy with nutrient signaling through the ULK1 autophagy pre-initiation complex. Furthermore, related cellular processes utilizing components of the canonical autophagy pathway are discussed due to their potential roles in nutrient scavenging. Finally, the role of autophagy in cancer and its potential as a cancer therapeutic target are considered.
Collapse
|
273
|
Abstract
Accumulation of triacylglycerols within the cytoplasm of hepatocytes to the degree that lipid droplets are visible microscopically is called liver steatosis. Most commonly, it occurs when there is an imbalance between the delivery or synthesis of fatty acids in the liver and their disposal through oxidative pathways or secretion into the blood as a component of triacylglycerols in very low density lipoprotein. This disorder is called nonalcoholic fatty liver disease (NAFLD) in the absence of alcoholic abuse and viral hepatitis, and it is often associated with insulin resistance, obesity and type 2 diabetes. Also, liver steatosis can be induced by many other causes including excessive alcohol consumption, infection with genotype 3 hepatitis C virus and certain medications. Whereas hepatic triacylglycerol accumulation was once considered the ultimate effector of hepatic lipotoxicity, triacylglycerols per se are quite inert and do not induce insulin resistance or cellular injury. Rather, lipotoxic injury in the liver appears to be mediated by the global ongoing fatty acid enrichment in the liver, paralleling the development of insulin resistance. A considerable number of fatty acid metabolites may be responsible for hepatic lipotoxicity and liver injury. Additional key contributors include hepatic cytosolic lipases and the "lipophagy" of lipid droplets, as sources of hepatic fatty acids. The specific origin of the lipids, mainly triacylglycerols, accumulating in liver has been unraveled by recent kinetic studies, and identifying the origin of the accumulated triacylglycerols in the liver of patients with NAFLD may direct the prevention and treatment of this condition.
Collapse
Affiliation(s)
- David Q-H Wang
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Saint Louis University School of Medicine, St. Louis, Missouri
| | | | | |
Collapse
|
274
|
Alexaki A, Gupta SD, Majumder S, Kono M, Tuymetova G, Harmon JM, Dunn TM, Proia RL. Autophagy regulates sphingolipid levels in the liver. J Lipid Res 2014; 55:2521-31. [PMID: 25332431 DOI: 10.1194/jlr.m051862] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Sphingolipid levels are tightly regulated to maintain cellular homeostasis. During pathologic conditions such as in aging, inflammation, and metabolic and neurodegenerative diseases, levels of some sphingolipids, including the bioactive metabolite ceramide, are elevated. Sphingolipid metabolism has been linked to autophagy, a critical catabolic process in both normal cell function and disease; however, the in vivo relevance of the interaction is not well-understood. Here, we show that blocking autophagy in the liver by deletion of the Atg7 gene, which is essential for autophagosome formation, causes an increase in sphingolipid metabolites including ceramide. We also show that overexpression of serine palmitoyltransferase to elevate de novo sphingolipid biosynthesis induces autophagy in the liver. The results reveal autophagy as a process that limits excessive ceramide levels and that is induced by excessive elevation of de novo sphingolipid synthesis in the liver. Dysfunctional autophagy may be an underlying mechanism causing elevations in ceramide that may contribute to pathogenesis in diseases.
Collapse
Affiliation(s)
- Aikaterini Alexaki
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Sita D Gupta
- Departments of Biochemistry Uniformed Services University of the Health Sciences, Bethesda, MD 20184
| | - Saurav Majumder
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Mari Kono
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Galina Tuymetova
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Jeffrey M Harmon
- Molecular Biology and Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, MD 20184
| | - Teresa M Dunn
- Departments of Biochemistry Uniformed Services University of the Health Sciences, Bethesda, MD 20184
| | - Richard L Proia
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| |
Collapse
|
275
|
Abstract
Autophagy is a conserved cellular process that plays an important role in cardiovascular homeostasis. Basal levels of autophagy are required for the maintenance of organellar quality control. Autophagy is dynamically regulated in the heart in the fasting to re-feeding transition. Insulin signaling plays an important role in the regulation of myocardial fuel metabolism, mitochondrial function and cellular growth. Recent studies have suggested an important role for insulin signaling in the regulation of myocardial autophagy. This dynamic regulation of autophagy induction during fasting may contribute to organellar homeostasis and if perturbed under conditions of hyperinsulinemia could contribute to accelerated cardiac aging.
Collapse
Affiliation(s)
- Christian Riehle
- Fraternal Order of Eagles Diabetes Research Center, Division of Endocrinology and Metabolism, Roy J. and Lucille A. Carver College of Medicine, University of Iowa
| | | |
Collapse
|
276
|
Sha H, Sun S, Francisco AB, Ehrhardt N, Xue Z, Liu L, Lawrence P, Mattijssen F, Guber RD, Panhwar MS, Brenna JT, Shi H, Xue B, Kersten S, Bensadoun A, Péterfy M, Long Q, Qi L. The ER-associated degradation adaptor protein Sel1L regulates LPL secretion and lipid metabolism. Cell Metab 2014; 20:458-70. [PMID: 25066055 PMCID: PMC4156539 DOI: 10.1016/j.cmet.2014.06.015] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 03/17/2014] [Accepted: 06/06/2014] [Indexed: 10/25/2022]
Abstract
Sel1L is an essential adaptor protein for the E3 ligase Hrd1 in the endoplasmic reticulum (ER)-associated degradation (ERAD), a universal quality-control system in the cell; but its physiological role remains unclear. Here we show that mice with adipocyte-specific Sel1L deficiency are resistant to diet-induced obesity and exhibit postprandial hypertriglyceridemia. Further analyses reveal that Sel1L is indispensable for the secretion of lipoprotein lipase (LPL), independent of its role in Hrd1-mediated ERAD and ER homeostasis. Sel1L physically interacts with and stabilizes the LPL maturation complex consisting of LPL and lipase maturation factor 1 (LMF1). In the absence of Sel1L, LPL is retained in the ER and forms protein aggregates, which are degraded primarily by autophagy. The Sel1L-mediated control of LPL secretion is also seen in other LPL-expressing cell types including cardiac myocytes and macrophages. Thus, our study reports a role of Sel1L in LPL secretion and systemic lipid metabolism.
Collapse
Affiliation(s)
- Haibo Sha
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Shengyi Sun
- Graduate Program in Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, NY 14853, USA
| | - Adam B Francisco
- Department of Animal Science, Cornell University, Ithaca, NY 14853, USA
| | - Nicole Ehrhardt
- Department of Biomedical Sciences, Medical Genetics Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Zhen Xue
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Lei Liu
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Peter Lawrence
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Frits Mattijssen
- Nutrition Metabolism and Genomics Group, Wageningen University, Wageningen 6703HD, the Netherlands
| | - Robert D Guber
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Muhammad S Panhwar
- Weill Cornell Medical College in Qatar, P.O. Box 24144, Education City, Doha, Qatar
| | - J Thomas Brenna
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Hang Shi
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Bingzhong Xue
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Sander Kersten
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA; Nutrition Metabolism and Genomics Group, Wageningen University, Wageningen 6703HD, the Netherlands
| | - André Bensadoun
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Miklós Péterfy
- Department of Biomedical Sciences, Medical Genetics Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA; Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Qiaoming Long
- Laboratory Animal Research Center, Medical College of Soochow University, Suzhou, Jiangsu 215006, China
| | - Ling Qi
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA; Graduate Program in Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, NY 14853, USA.
| |
Collapse
|
277
|
Lee KW, Thiyagarajan V, Sie HW, Cheng MF, Tsai MJ, Chia YC, Weng CF. Synergistic effect of natural compounds on the fatty acid-induced autophagy of activated hepatic stellate cells. J Nutr Biochem 2014; 25:903-13. [DOI: 10.1016/j.jnutbio.2014.04.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 03/23/2014] [Accepted: 04/06/2014] [Indexed: 01/22/2023]
|
278
|
Autophagy in HCV infection: keeping fat and inflammation at bay. BIOMED RESEARCH INTERNATIONAL 2014; 2014:265353. [PMID: 25162004 PMCID: PMC4138948 DOI: 10.1155/2014/265353] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 07/11/2014] [Indexed: 12/14/2022]
Abstract
Hepatitis C virus (HCV) infection is one of the main causes of chronic liver disease. Viral persistence and pathogenesis rely mainly on the ability of HCV to deregulate specific host processes, including lipid metabolism and innate immunity. Recently, autophagy has emerged as a cellular pathway, playing a role in several aspects of HCV infection. This review summarizes current knowledge on the molecular mechanisms that link the HCV life cycle with autophagy machinery. In particular, we discuss the role of HCV/autophagy interaction in dysregulating inflammation and lipid homeostasis and its potential for translational applications in the treatment of HCV-infected patients.
Collapse
|
279
|
Aon MA, Bhatt N, Cortassa SC. Mitochondrial and cellular mechanisms for managing lipid excess. Front Physiol 2014; 5:282. [PMID: 25132820 PMCID: PMC4116787 DOI: 10.3389/fphys.2014.00282] [Citation(s) in RCA: 164] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 07/10/2014] [Indexed: 12/16/2022] Open
Abstract
Current scientific debates center on the impact of lipids and mitochondrial function on diverse aspects of human health, nutrition and disease, among them the association of lipotoxicity with the onset of insulin resistance in skeletal muscle, and with heart dysfunction in obesity and diabetes. Mitochondria play a fundamental role in aging and in prevalent acute or chronic diseases. Lipids are main mitochondrial fuels however these molecules can also behave as uncouplers and inhibitors of oxidative phosphorylation. Knowledge about the functional composition of these contradictory effects and their impact on mitochondrial-cellular energetics/redox status is incomplete. Cells store fatty acids (FAs) as triacylglycerol and package them into cytoplasmic lipid droplets (LDs). New emerging data shows the LD as a highly dynamic storage pool of FAs that can be used for energy reserve. Lipid excess packaging into LDs can be seen as an adaptive response to fulfilling energy supply without hindering mitochondrial or cellular redox status and keeping low concentration of lipotoxic intermediates. Herein we review the mechanisms of action and utilization of lipids by mitochondria reported in liver, heart and skeletal muscle under relevant physiological situations, e.g., exercise. We report on perilipins, a family of proteins that associate with LDs in response to loading of cells with lipids. Evidence showing that in addition to physical contact, mitochondria and LDs exhibit metabolic interactions is presented and discussed. A hypothetical model of channeled lipid utilization by mitochondria is proposed. Direct delivery and channeled processing of lipids in mitochondria could represent a reliable and efficient way to maintain reactive oxygen species (ROS) within levels compatible with signaling while ensuring robust and reliable energy supply.
Collapse
Affiliation(s)
- Miguel A Aon
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine Baltimore, MD, USA
| | - Niraj Bhatt
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine Baltimore, MD, USA
| | - Sonia C Cortassa
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine Baltimore, MD, USA
| |
Collapse
|
280
|
Wang CW, Miao YH, Chang YS. A sterol-enriched vacuolar microdomain mediates stationary phase lipophagy in budding yeast. ACTA ACUST UNITED AC 2014; 206:357-66. [PMID: 25070953 PMCID: PMC4121974 DOI: 10.1083/jcb.201404115] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During stationary phase growth in yeast, a feed-forward loop exists in which lipophagy stimulates vacuolar microdomain formation, which, in turn, further promotes lipophagy. Stationary phase (stat-phase) is a poorly understood physiological state under which cells arrest proliferation and acquire resistance to multiple stresses. Lipid droplets (LDs), organelles specialized for cellular lipid homeostasis, increase in size and number at the onset of stat-phase. However, little is known about the dynamics of LDs under this condition. In this paper, we reveal the passage of LDs from perinuclear endoplasmic reticulum association to entry into vacuoles during the transition to stat-phase. We show that the process requires the core autophagy machinery and a subset of autophagy-related (Atg) proteins involved in selective autophagy. Notably, the process that we term stat-phase lipophagy is mediated through a sterol-enriched vacuolar microdomain whose formation and integrity directly affect LD translocation. Intriguingly, cells defective in stat-phase lipophagy showed disrupted vacuolar microdomains, implying that LD contents, likely sterol esters, contribute to the maintenance of vacuolar microdomains. Together, we propose a feed-forward loop in which lipophagy stimulates vacuolar microdomain formation, which in turn promotes lipophagy during stat-phase.
Collapse
Affiliation(s)
- Chao-Wen Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yu-Hsuan Miao
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yi-Shun Chang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| |
Collapse
|
281
|
Contributions of metabolic dysregulation and inflammation to nonalcoholic steatohepatitis, hepatic fibrosis, and cancer. Curr Opin Oncol 2014; 26:100-7. [PMID: 24275855 DOI: 10.1097/cco.0000000000000042] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE OF REVIEW We review accumulating evidence that nonalcoholic steatohepatitis (NASH), a more advanced form of nonalcoholic fatty liver disease (NAFLD), predisposes patients to the risk of developing hepatocellular carcinoma (HCC), and we summarize recent advances in the elucidation of cancer-promoting pathways in NASH. We highlight the potential role of progenitor cells and hepatic stellate cells (HSCs) in promoting the early events that could culminate in cancer, as well as the emerging contribution of the gut-liver axis in promoting inflammation, senescence, and tumor growth in NASH and HCC. Finally, we review the role of bile acid receptors, vitamin D, and protective cellular pathways such as autophagy. RECENT FINDINGS Studies have recently uncovered roles for gut microbiota, bile acid receptors and vitamin D in regulating the progression from NAFLD to HCC. Intriguing findings linking senescence and autophagy in hepatic stellate cells to HCC have also been discovered, as well as a link between dysregulated progenitor cell regulation and HCC. SUMMARY NAFLD is the most common cause of chronic liver disease in the United States and Western Europe. The lack of definitive mechanisms underlying development of NASH among patients with NAFLD and its progression to HCC limit diagnosis and management, but new findings are paving the way for better biomarkers and therapies.
Collapse
|
282
|
Abstract
PURPOSE OF REVIEW Autophagy is an evolutionarily conserved cellular programme for the turnover of organelles, proteins, and other macromolecules, involving the lysosomal degradation pathway. Emerging evidence suggests that autophagy can play a central role in human metabolism as well as impact diverse cellular processes including organelle homeostasis, cell death and proliferation, lipid and glycogen metabolism, and the regulation of inflammation and immune responses. The purpose of this review is to examine recent evidence for the role of autophagy in cellular metabolism, and its relevance to select human diseases that involve disorders of metabolism. RECENT FINDINGS Recent studies suggest that autophagy may play multiple roles in metabolic diseases, including diabetes and its complications, metabolic syndrome and obesity, myopathies and other inborn errors of metabolism, as well as other diseases that may involve altered mitochondrial function. SUMMARY Strategies aimed at modulating autophagy may lead to therapies for diseases in which altered cellular and tissue metabolism play a key role.
Collapse
Affiliation(s)
- Stefan W. Ryter
- Weil Cornell Medical College, New York, NY 525 East 68th Street Room M-522, Box 130, New York, NY 10065
- Correspondence should be addressed to: Stefan W. Ryter, PhD. Weil Cornell Medical College, New York, NY 525 East 68th Street Room M-522, Box 130, New York, NY 10065. Tel: 212-746-4720, Fax: 212-746-8793
| | - Michael Koo
- Weil Cornell Medical College, New York, NY 525 East 68th Street Room M-522, Box 130, New York, NY 10065
| | - Augustine M.K. Choi
- Weil Cornell Medical College, New York, NY 525 East 68th Street Room M-522, Box 130, New York, NY 10065
| |
Collapse
|
283
|
Palmitic acid and oleic acid differentially regulate choline transporter-like 1 levels and glycerolipid metabolism in skeletal muscle cells. Lipids 2014; 49:731-44. [PMID: 24972900 DOI: 10.1007/s11745-014-3925-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 06/16/2014] [Indexed: 12/20/2022]
Abstract
Choline is an essential nutrient required for the biosynthesis of membrane lipid phosphatidylcholine (PtdCho). Here we elucidate the mechanism of how palmitic acid (PAM) and oleic acid (OLA) regulate choline transporter-like protein 1 (CTL1/SLC44A1) function. We evaluated the mechanism of extracellular and intracellular transport of choline, and their contribution to PtdCho and other glycerolipid-diacylglycerol (DAG) and triacylglycerol (TAG) homeostasis in differentiated skeletal muscle cells. PAM reduces total and plasma membrane CTL1/SLC44A1 protein by lysosomal degradation, and limits the choline uptake while increasing DAG and TAG synthesis. OLA maintains total and plasma membrane CTL1/SLC44A1, but increases PtdCho synthesis more than PAM. OLA does not increase the rate of DAG synthesis, but does increase TAG content. Thus, the CTL1/SLC44A1 presence at the plasma membrane regulates choline requirements in accordance with the type of fatty acid. The increased PtdCho and TAG turnover by OLA stimulates cell growth and offers a specific protection mechanism from the excess of intracellular DAG and autophagy. This protection was present after OLA treatments, but not after PAM treatments. The mitochondrial choline uptake was reduced by both FA; however, the regulation is complex and guided not only by the presence of the mitochondrial CTL1/SLC44A1 protein but also by the membrane potential and general mitochondrial function.
Collapse
|
284
|
Kwanten WJ, Martinet W, Michielsen PP, Francque SM. Role of autophagy in the pathophysiology of nonalcoholic fatty liver disease: A controversial issue. World J Gastroenterol 2014; 20:7325-7338. [PMID: 24966603 PMCID: PMC4064078 DOI: 10.3748/wjg.v20.i23.7325] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Revised: 12/24/2013] [Accepted: 01/08/2014] [Indexed: 02/06/2023] Open
Abstract
Autophagy is a mechanism involved in cellular homeostasis under basal and stressed conditions delivering cytoplasmic content to the lysosomes for degradation to macronutrients. The potential role of autophagy in disease is increasingly recognised and investigated in the last decade. Nowadays it is commonly accepted that autophagy plays a role in the hepatic lipid metabolism. Hence, dysfunction of autophagy may be an underlying cause of non-alcoholic fatty liver disease. However, controversy of the exact role of autophagy in the lipid metabolism exists: some publications report a lipolytic function of autophagy, whereas others claim a lipogenic function. This review aims to give an update of the present knowledge on autophagy in the hepatic lipid metabolism, hepatic insulin resistance, steatohepatitis and hepatic fibrogenesis.
Collapse
|
285
|
Dias FF, Zarantonello VC, Parreira GG, Chiarini-Garcia H, Melo RCN. The intriguing ultrastructure of lipid body organelles within activated macrophages. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2014; 20:869-878. [PMID: 24786359 DOI: 10.1017/s143192761400066x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Macrophages are widely distributed immune system cells with essential functions in tissue homeostasis, apoptotic cell clearance, and first defense in infections. A distinguishing feature of activated macrophages participating in different situations such as inflammatory and metabolic diseases is the presence of increased numbers of lipid-rich organelles, termed lipid bodies (LBs) or lipid droplets, in their cytoplasm. LBs are considered structural markers of activated macrophages and are involved in different functions such as lipid metabolism, intracellular trafficking, and synthesis of inflammatory mediators. In this review, we revisit the distinct morphology of LB organelles actively formed within macrophages in response to infections and cell clearance, taking into account new insights provided by ultrastructural studies. We also discuss the LB interactions within macrophages, revealed by transmission electron microscopy, with a focus on the remarkable LB-phagosome association and discuss potential links between structural aspects and function.
Collapse
Affiliation(s)
- Felipe F Dias
- 1Laboratory of Cellular Biology,Department of Biology,Federal University of Juiz de Fora (UFJF),Juiz de Fora,MG 36036-900,Brazil
| | - Victor C Zarantonello
- 1Laboratory of Cellular Biology,Department of Biology,Federal University of Juiz de Fora (UFJF),Juiz de Fora,MG 36036-900,Brazil
| | - Gleydes G Parreira
- 2Laboratory of Structural Biology and Reproduction,Federal University of Minas Gerais (UFMG),Belo Horizonte,MG 31270-901,Brazil
| | - Hélio Chiarini-Garcia
- 2Laboratory of Structural Biology and Reproduction,Federal University of Minas Gerais (UFMG),Belo Horizonte,MG 31270-901,Brazil
| | - Rossana C N Melo
- 1Laboratory of Cellular Biology,Department of Biology,Federal University of Juiz de Fora (UFJF),Juiz de Fora,MG 36036-900,Brazil
| |
Collapse
|
286
|
Karsli-Uzunbas G, Guo JY, Price S, Teng X, Laddha SV, Khor S, Kalaany NY, Jacks T, Chan CS, Rabinowitz JD, White E. Autophagy is required for glucose homeostasis and lung tumor maintenance. Cancer Discov 2014; 4:914-27. [PMID: 24875857 DOI: 10.1158/2159-8290.cd-14-0363] [Citation(s) in RCA: 410] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
UNLABELLED Macroautophagy (autophagy hereafter) recycles intracellular components to sustain mitochondrial metabolism that promotes the growth, stress tolerance, and malignancy of lung cancers, suggesting that autophagy inhibition may have antitumor activity. To assess the functional significance of autophagy in both normal and tumor tissue, we conditionally deleted the essential autophagy gene, autophagy related 7 (Atg7), throughout adult mice. Here, we report that systemic ATG7 ablation caused susceptibility to infection and neurodegeneration that limited survival to 2 to 3 months. Moreover, upon fasting, autophagy-deficient mice suffered fatal hypoglycemia. Prior autophagy ablation did not alter the efficiency of non-small cell lung cancer (NSCLC) initiation by activation of oncogenic Kras(G12D) and deletion of the Trp53 tumor suppressor. Acute autophagy ablation in mice with preexisting NSCLC, however, blocked tumor growth, promoted tumor cell death, and generated more benign disease (oncocytomas). This antitumor activity occurred before destruction of normal tissues, suggesting that acute autophagy inhibition may be therapeutically beneficial in cancer. SIGNIFICANCE We systemically ablated cellular self-cannibalization by autophagy in adult mice and determined that it is dispensable for short-term survival, but required to prevent fatal hypoglycemia and cachexia during fasting, delineating a new role for autophagy in metabolism. Importantly, acute, systemic autophagy ablation was selectively destructive to established tumors compared with normal tissues, thereby providing the preclinical evidence that strategies to inhibit autophagy may be therapeutically advantageous for RAS-driven cancers.
Collapse
Affiliation(s)
- Gizem Karsli-Uzunbas
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey. Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey
| | - Jessie Yanxiang Guo
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey. Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey
| | - Sandy Price
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey
| | - Xin Teng
- Department of Chemistry, Princeton University, Princeton, New Jersey
| | - Saurabh V Laddha
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey
| | - Sinan Khor
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey. Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey
| | - Nada Y Kalaany
- Division of Endocrinology, Center for Basic and Translational Obesity Research, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Tyler Jacks
- Koch Institute for Integrative Cancer Research and Department of Biology, MIT, Cambridge, Massachusetts. Howard Hughes Medical Institute, MIT, Cambridge, Massachusetts
| | - Chang S Chan
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey. Deparment of Medicine, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey
| | - Joshua D Rabinowitz
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey. Department of Chemistry, Princeton University, Princeton, New Jersey
| | - Eileen White
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey. Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey.
| |
Collapse
|
287
|
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
Collapse
|
288
|
Arrese EL, Saudale FZ, Soulages JL. Lipid Droplets as Signaling Platforms Linking Metabolic and Cellular Functions. Lipid Insights 2014; 7:7-16. [PMID: 25221429 PMCID: PMC4161058 DOI: 10.4137/lpi.s11128] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The main cells of the adipose tissue of animals, adipocytes, are characterized by the presence of large cytosolic lipid droplets (LDs) that store triglyceride (TG) and cholesterol. However, most cells have LDs and the ability to store lipids. LDs have a well-known central role in storage and provision of fatty acids and cholesterol. However, the complexity of the regulation of lipid metabolism on the surface of the LDs is still a matter of intense study. Beyond this role, a number of recent studies have suggested that LDs have major functions in other cellular processes, such as protein storage and degradation, infection, and immunity. Thus, our perception of LDs has been radically transformed from simple globules of fat to highly dynamic organelles of unexpected complexity. Here, we compiled some recent evidence supporting the emerging view that LDs act as platforms connecting a number of relevant metabolic and cellular functions.
Collapse
Affiliation(s)
- Estela L Arrese
- Department of Biochemistry and Molecular Biology; Oklahoma State University; Stillwater, OK, 74078, USA
| | - Fredy Z Saudale
- Department of Biochemistry and Molecular Biology; Oklahoma State University; Stillwater, OK, 74078, USA
| | - Jose L Soulages
- Department of Biochemistry and Molecular Biology; Oklahoma State University; Stillwater, OK, 74078, USA
| |
Collapse
|
289
|
Avanesov AS, Ma S, Pierce KA, Yim SH, Lee BC, Clish CB, Gladyshev VN. Age- and diet-associated metabolome remodeling characterizes the aging process driven by damage accumulation. eLife 2014; 3:e02077. [PMID: 24843015 PMCID: PMC4003482 DOI: 10.7554/elife.02077] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Aging is thought to be associated with increased molecular damage, but representative markers vary across conditions and organisms, making it difficult to assess properties of cumulative damage throughout lifespan. We used nontargeted metabolite profiling to follow age-associated trajectories of >15,000 metabolites in Drosophila subjected to control and lifespan-extending diets. We find that aging is associated with increased metabolite diversity and low-abundance molecules, suggesting they include cumulative damage. Remarkably, the number of detected compounds leveled-off in late-life, and this pattern associated with survivorship. Fourteen percent of metabolites showed age-associated changes, which decelerated in late-life and long-lived flies. In contrast, known metabolites changed in abundance similarly to nontargeted metabolites and transcripts, but did not increase in diversity. Targeted profiling also revealed slower metabolism and accumulation of lifespan-limiting molecules. Thus, aging is characterized by gradual metabolome remodeling, and condition- and advanced age-associated deceleration of this remodeling is linked to mortality and molecular damage.DOI: http://dx.doi.org/10.7554/eLife.02077.001.
Collapse
Affiliation(s)
- Andrei S Avanesov
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, United States
| | - Siming Ma
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, United States
| | | | - Sun Hee Yim
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, United States
| | - Byung Cheon Lee
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, United States
| | | | - Vadim N Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, United States Broad Institute, Cambridge, United States
| |
Collapse
|
290
|
Escoté X, Fajas L. Metabolic adaptation to cancer growth: from the cell to the organism. Cancer Lett 2014; 356:171-5. [PMID: 24709629 DOI: 10.1016/j.canlet.2014.03.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 03/20/2014] [Accepted: 03/28/2014] [Indexed: 01/03/2023]
Abstract
Tumour cells proliferate much faster than normal cells; nearly all anticancer treatments are toxic to both cell types, limiting their efficacy. The altered metabolism resulting from cellular transformation and cancer progression supports cellular proliferation and survival, but leaves cancer cells dependent on a continuous supply of energy and nutrients. Hence, many metabolic enzymes have become targets for new cancer therapies. In addition to its well-described roles in cell-cycle progression and cancer, the cyclin/CDK-pRB-E2F1 pathway contributes to lipid synthesis, glucose production, insulin secretion, and glycolytic metabolism, with strong effects on overall metabolism. Notably, these cell-cycle regulators trigger the adaptive "metabolic switch" that underlies proliferation.
Collapse
Affiliation(s)
- Xavier Escoté
- Department of Physiology, Université de Lausanne, Lausanne, Switzerland.
| | - Lluís Fajas
- Department of Physiology, Université de Lausanne, Lausanne, Switzerland.
| |
Collapse
|
291
|
Kiss RS, Nilsson T. Rab proteins implicated in lipid storage and mobilization. J Biomed Res 2014; 28:169-77. [PMID: 25013400 PMCID: PMC4085554 DOI: 10.7555/jbr.28.20140029] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 02/28/2014] [Indexed: 12/28/2022] Open
Abstract
Abnormal intracellular accumulation or transport of lipids contributes greatly to the pathogenesis of human diseases. In the liver, excess accumulation of triacylglycerol (TG) leads to fatty liver disease encompassing steatosis, steatohepatitis and fibrosis. This places individuals at risk of developing cirrhosis, hepatocellular carcinoma or hepatic decompensation and also contributes to the emergence of insulin resistance and dyslipidemias affecting many other organs. Excessive accumulation of TG in adipose tissue contributes to insulin resistance as well as to the release of cytokines attracting leucocytes leading to a pro-inflammatory state. Pathological accumulation of cholesteryl ester (CE) in macrophages in the arterial wall is the progenitor of atherosclerotic plaques and heart disease. Overconsumption of dietary fat, cholesterol and carbohydrates explains why these diseases are on the increase yet offers few clues for how to prevent or treat individuals. Dietary regimes have proven futile and barring surgery, no realistic alternatives are at hand as effective drugs are few and not without side effects. Overweight and obesity-related diseases are no longer restricted to the developed world and as such, constitute a global problem. Development of new drugs and treatment strategies are a priority yet requires as a first step, elucidation of the molecular pathophysiology underlying each associated disease state. The lipid droplet (LD), an up to now overlooked intracellular organelle, appears at the heart of each pathophysiology linking key regulatory and metabolic processes as well as constituting the site of storage of both TGs and CEs. As the molecular machinery and mechanisms of LDs of each cell type are being elucidated, regulatory proteins used to control various cellular processes are emerging. Of these and the subject of this review, small GTPases belonging to the Rab protein family appear as important molecular switches used in the regulation of the intracellular trafficking and storage of lipids.
Collapse
Affiliation(s)
- Robert Scott Kiss
- Department of Medicine, McGill University, Montreal, Canada; ; Research Institute of McGill University Health Centre, Montreal, Canada
| | - Tommy Nilsson
- Department of Medicine, McGill University, Montreal, Canada; ; Research Institute of McGill University Health Centre, Montreal, Canada
| |
Collapse
|
292
|
Abstract
Far from now are the days when investigators raced to identify the proteolytic system responsible for the degradation of their favorite protein. Nowadays, it is well accepted that a given protein can be degraded by different systems depending on factors such as cell type, cellular conditions, or functionality of each proteolytic pathway. The realization of this sharing of substrates among pathways has also helped to unveil deeper levels of communication among the different proteolytic systems. Thus, cells often respond to blockage of one degradative mechanism by upregulating any of the other available pathways. In addition, effectors and regulators of one proteolytic system can be degraded by a different proteolytic pathway that exerts, in this way, a regulatory function. In this mini review, we describe the different levels of cross-talk among autophagic pathways and the ubiquitin/proteasome system. We also provide examples of how this proteolytic communication is used for compensatory purposes in different pathological conditions and discuss the possible therapeutic potential of targeting the modulators of the cross-talk among proteolytic pathways.
Collapse
Affiliation(s)
- Caroline Park
- Department of Developmental and Molecular Biology, Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY, USA
| | | |
Collapse
|
293
|
Webb AE, Brunet A. FOXO transcription factors: key regulators of cellular quality control. Trends Biochem Sci 2014; 39:159-69. [PMID: 24630600 DOI: 10.1016/j.tibs.2014.02.003] [Citation(s) in RCA: 408] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 02/05/2014] [Accepted: 02/07/2014] [Indexed: 12/13/2022]
Abstract
FOXO transcription factors are conserved regulators of longevity downstream of insulin signaling. These transcription factors integrate signals emanating from nutrient deprivation and stress stimuli to coordinate programs of genes involved in cellular metabolism and resistance to oxidative stress. Here, we discuss emerging evidence for a pivotal role of FOXO factors in promoting the expression of genes involved in autophagy and the ubiquitin-proteasome system--two cell clearance processes that are essential for maintaining organelle and protein homeostasis (proteostasis). The ability of FOXO to maintain cellular quality control appears to be critical in processes and pathologies where damaged proteins and organelles accumulate, including aging and neurodegenerative diseases.
Collapse
Affiliation(s)
- Ashley E Webb
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Anne Brunet
- Department of Genetics, Stanford University, Stanford, CA 94305, USA; Glenn Laboratories for the Biology of Aging at Stanford, Stanford, CA 94305, USA.
| |
Collapse
|
294
|
Sahini N, Borlak J. Recent insights into the molecular pathophysiology of lipid droplet formation in hepatocytes. Prog Lipid Res 2014; 54:86-112. [PMID: 24607340 DOI: 10.1016/j.plipres.2014.02.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 02/17/2014] [Accepted: 02/21/2014] [Indexed: 12/11/2022]
Abstract
Triacyglycerols are a major energy reserve of the body and are normally stored in adipose tissue as lipid droplets (LDs). The liver, however, stores energy as glycogen and digested triglycerides in the form of fatty acids. In stressed condition such as obesity, imbalanced nutrition and drug induced liver injury hepatocytes accumulate excess lipids in the form of LDs whose prolonged storage leads to disease conditions most notably non-alcoholic fatty liver disease (NAFLD). Fatty liver disease has become a major health burden with more than 90% of obese, nearly 70% of overweight and about 25% of normal weight patients being affected. Notably, research in recent years has shown LD as highly dynamic organelles for maintaining lipid homeostasis through fat storage, protein sorting and other molecular events studied in adipocytes and other cells of living organisms. This review focuses on the molecular events of LD formation in hepatocytes and the importance of cross talk between different cell types and their signalling in NAFLD as to provide a perspective on molecular mechanisms as well as possibilities for different therapeutic intervention strategies.
Collapse
Affiliation(s)
- Nishika Sahini
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625 Hannover, Germany
| | - Jürgen Borlak
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625 Hannover, Germany.
| |
Collapse
|
295
|
Selective inhibition of PI3K/Akt/mTOR signaling pathway regulates autophagy of macrophage and vulnerability of atherosclerotic plaque. PLoS One 2014; 9:e90563. [PMID: 24599185 PMCID: PMC3944201 DOI: 10.1371/journal.pone.0090563] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 01/31/2014] [Indexed: 12/21/2022] Open
Abstract
Macrophage infiltration contributes to the instability of atherosclerotic plaques. In the present study, we investigated whether selective inhibition of PI3K/Akt/mTOR signaling pathway can enhance the stability of atherosclerotic plaques by activation of macrophage autophagy. In vitro study, selective inhibitors or siRNA of PI3K/Akt/mTOR pathways were used to treat the rabbit's peritoneal primary macrophage cells. Inflammation related cytokines secreted by macrophages were measured. Ultrastructure changes of macrophages were examined by transmission electron microscope. mRNA or protein expression levels of autophagy related gene Beclin 1, protein 1 light chain 3 II dots (LC3-II) or Atg5-Atg12 conjugation were assayed by quantitative RT-PCR or Western blot. In vivo study, vulnerable plaque models were established in 40 New Zealand White rabbits and then drugs or siRNA were given for 8 weeks to inhibit the PI3K/Akt/mTOR signaling pathway. Intravascular ultrasound (IVUS) was performed to observe the plaque imaging. The ultrastructure of the abdominal aortic atherosclerosis lesions were analyzed with histopathology. RT-PCR or Western blot methods were used to measure the expression levels of corresponding autophagy related molecules. We found that macrophage autophagy was induced in the presence of Akt inhibitor, mTOR inhibitor and mTOR-siRNA in vitro study, while PI3K inhibitor had the opposite role. In vivo study, we found that macrophage autophagy increased significantly and the rabbits had lower plaque rupture incidence, lower plaque burden and decreased vulnerability index in the inhibitors or siRNA treated groups. We made a conclusion that selective inhibition of the Akt/mTOR signal pathway can reduce macrophages and stabilize the vulnerable atherosclerotic plaques by promoting macrophage autophagy.
Collapse
|
296
|
Kim KH, Lee MS. Autophagy as a crosstalk mediator of metabolic organs in regulation of energy metabolism. Rev Endocr Metab Disord 2014; 15:11-20. [PMID: 24085381 DOI: 10.1007/s11154-013-9272-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Autophagy plays an important role in the regulation of cellular homeostasis through elimination of aggregated proteins, damaged organelles, and intracellular pathogens. Autophagy also contributes to the maintenance of energy balance through degradation of energy reserves such as lipids, glycogen, and proteins in the setting of increased energy demand. Recent studies have suggested that autophagy, or its deficiency, is implicated in the pathogenesis of insulin resistance, obesity, and diabetes. These effects of autophagy or its deficiency in regulation of energy metabolism are mediated not only by cell-autonomous effects, such as direct autophagic degradation of energy stores or intracellular organelles (endoplasmic reticulum and mitochondria) but also by non-cell-autonomous effects, such as induction/suppression of secreted factors or changes of sympathetic tone. In the present review, we highlight a recent surge in the research on the autophagy in the regulation of energy homeostasis, with a focus on its role as a mediator for crosstalk between metabolic organs.
Collapse
Affiliation(s)
- Kook Hwan Kim
- Department of Medicine and Samsung Advanced Institute for Health Sciences and Technology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Gangnam-gu, Seoul, 135-710, Korea
| | | |
Collapse
|
297
|
Lettieri Barbato D, Vegliante R, Desideri E, Ciriolo MR. Managing lipid metabolism in proliferating cells: new perspective for metformin usage in cancer therapy. Biochim Biophys Acta Rev Cancer 2014; 1845:317-24. [PMID: 24569230 DOI: 10.1016/j.bbcan.2014.02.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 02/18/2014] [Indexed: 01/01/2023]
Abstract
Cancer cells metabolically adapt to undergo cellular proliferation. Lipids, besides their well-known role as energy storage, represent the major building blocks for the synthesis of neo-generated membranes. There is increasing evidence that cancer cells show specific alterations in different aspects of lipid metabolism. The changes of expression and activity of lipid metabolising enzymes are directly regulated by the activity of oncogenic signals. The dependence of tumour cells on the deregulated lipid metabolism suggests that proteins involved in this process could be excellent chemotherapeutic targets for cancer treatment. Due to its rare side effects in non-cancerous cells, metformin has been recently revaluated as a potential anti-tumourigenic drug, which negatively affects lipid biosynthetic pathways. In this review we summarised the emerging molecular events linking the anti-proliferative effect of metformin with lipid metabolism in cancer cells.
Collapse
Affiliation(s)
- Daniele Lettieri Barbato
- Dept. of Biology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Rolando Vegliante
- Dept. of Biology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Enrico Desideri
- Dept. of Biology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Maria Rosa Ciriolo
- Dept. of Biology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy; IRCCS San Raffaele, Biochemistry of Ageing, Via di Val Cannuta, 00166 Rome, Italy.
| |
Collapse
|
298
|
Wang X, Li L, Niu X, Dang X, Li P, Qu L, Bi X, Gao Y, Hu Y, Li M, Qiao W, Peng Z, Pan L. mTOR enhances foam cell formation by suppressing the autophagy pathway. DNA Cell Biol 2014; 33:198-204. [PMID: 24512183 DOI: 10.1089/dna.2013.2164] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Recently, autophagy has drawn more attention in cardiovascular disease as it has important roles in lipid metabolism. Mammalian target of rapamycin (mTOR) is a key regulator of autophagy; however, its effect on atherosclerosis and the underlying mechanism remains undefined. In this study, an obvious upregulation of mTOR and p-mTOR protein was observed in macrophage-derived foam cells. Blocking mTOR expression with specific small interference RNA (siRNA) dramatically suppressed foam cell formation, accompanied by a decrease of lipid deposition. Further mechanistic analysis indicated that suppressing mTOR expression significantly upregulated autophagic marker LC3 expression and downregulated autophagy substrate p62 levels, indicating that mTOR silencing triggered autophagosome formation. Moreover, blocking mTOR expression obviously accelerated neutral lipid delivery to lysosome and cholesterol efflux from foam cells, implying that mTOR could induce macrophage foam cell formation by suppressing autophagic pathway. Further, mTOR silencing significantly upregulated ULK1 expression, which was accounted for mTOR-induced foam cell formation via autophagic pathway as treatment with ULK1 siRNA dampened LC3-II levels and increased p62 expression, concomitant with lipid accumulation and decreased cholesterol efflux from foam cells. Together, our data provide an insight into how mTOR accelerates the pathological process of atherosclerosis. Accordingly, blocking mTOR levels may be a promising therapeutic agent against atherosclerotic complications.
Collapse
Affiliation(s)
- Xiaochuang Wang
- 1 Department of Emergency Medicine, The Second Affiliated Hospital of Medical College, Xi'an Jiaotong University , Xi'an, People's Republic of China
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
299
|
Pavlovic Z, Zhu L, Pereira L, Singh RK, Cornell RB, Bakovic M. Isoform-specific and protein kinase C-mediated regulation of CTP:phosphoethanolamine cytidylyltransferase phosphorylation. J Biol Chem 2014; 289:9053-64. [PMID: 24519946 DOI: 10.1074/jbc.m113.544932] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CTP:phosphoethanolamine cytidylyltransferase (Pcyt2) is the main regulatory enzyme for de novo biosynthesis of phosphatidylethanolamine by the CDP-ethanolamine pathway. There are two isoforms of Pcyt2, -α and -β; however, very little is known about their specific roles in this important metabolic pathway. We previously demonstrated increased phosphatidylethanolamine biosynthesis subsequent to elevated activity and phosphorylation of Pcyt2α and -β in MCF-7 breast cancer cells grown under conditions of serum deficiency. Mass spectroscopy analyses of Pcyt2 provided evidence for isoform-specific as well as shared phosphorylations. Pcyt2β was specifically phosphorylated at the end of the first cytidylyltransferase domain. Pcyt2α was phosphorylated within the α-specific motif that is spliced out in Pcyt2β and on two PKC consensus serine residues, Ser-215 and Ser-223. Single and double mutations of PKC consensus sites reduced Pcyt2α phosphorylation, activity, and phosphatidylethanolamine synthesis by 50-90%. The phosphorylation and activity of endogenous Pcyt2 were dramatically increased with phorbol esters and reduced by specific PKC inhibitors. In vitro translated Pcyt2α was phosphorylated by PKCα, PKCβI, and PKCβII. Pcyt2α Ser-215 was also directly phosphorylated with PKCα. Mapping of the Pcyt2α- and -β-phosphorylated sites to the solved structure of a human Pcyt2β showed that they clustered within and flanking the central linker region that connects the two catalytic domains and is a novel regulatory segment not present in other cytidylyltransferases. This study is the first to demonstrate differences in phosphorylation between Pcyt2 isoforms and to uncover the role of the PKC-regulated phosphorylation.
Collapse
Affiliation(s)
- Zvezdan Pavlovic
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Ontario N1G 2W1 and
| | | | | | | | | | | |
Collapse
|
300
|
Rubio N, Verrax J, Dewaele M, Verfaillie T, Johansen T, Piette J, Agostinis P. p38(MAPK)-regulated induction of p62 and NBR1 after photodynamic therapy promotes autophagic clearance of ubiquitin aggregates and reduces reactive oxygen species levels by supporting Nrf2-antioxidant signaling. Free Radic Biol Med 2014; 67:292-303. [PMID: 24269898 DOI: 10.1016/j.freeradbiomed.2013.11.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 10/13/2013] [Accepted: 11/12/2013] [Indexed: 12/30/2022]
Abstract
Emerging evidence indicates that oxidative stress instigates the formation of ubiquitin (Ub) aggregates, substrates of autophagy, through a process requiring the ubiquitin binding adaptors p62/SQSTM1 and NBR1. Here, we have investigated the role of p62 and NBR1 in cell survival after hypericin-mediated photodynamic therapy (Hyp-PDT), a procedure known to incite robust reactive oxygen species (ROS)-based endoplasmic reticulum stress and autophagy pathways. We found that Hyp-PDT stimulated the formation of p62- and NBR1-associated Ub aggregates in normal and cancer cells, which were ultimately removed by autophagy, through a mechanism partially regulated by p38(MAPK). In line with this, genetic or pharmacological p38(MAPK) inhibition reduced p62 and NBR1 levels and aggregate formation and impaired Nrf2 activation, thus increasing photo-oxidative stress and cell death. p62-deficient cells, or cells lacking p62 and with reduced levels of NBR1 (through siRNA knockdown), also displayed reduced aggregate formation but exhibited attenuated ROS levels, reduced caspase activation, and improved survival after Hyp-PDT. The increased resistance to photo-oxidative stress exhibited by cells lacking p62 and/or NBR1 was overruled by the inhibition of p38(MAPK), which restored cytotoxic ROS levels, thus indicating the relevance of this signal in the control of cell viability. Taken together these findings provide evidence that in photodynamically treated cells a p38(MAPK)-regulated pathway coordinates the p62/NBR1-mediated clearance of cytosolic aggregates and mitigates PDT-induced proteotoxicity. They also reveal that a functional p38(MAPK)-Nrf2 signal is required to keep ROS levels in check and protect against PDT-induced proteotoxicity, independent of aggregate formation.
Collapse
Affiliation(s)
- Noemí Rubio
- Cell Death Research & Therapy Laboratory, Cellular and Molecular Medicine Department, KU Leuven - University of Leuven, 3000 Leuven, Belgium; Virology and Immunology Unit, GiGA-R, GiGA B34, University of Liège, 4000 Liège, Belgium
| | - Julien Verrax
- Cell Death Research & Therapy Laboratory, Cellular and Molecular Medicine Department, KU Leuven - University of Leuven, 3000 Leuven, Belgium
| | - Michael Dewaele
- Cell Death Research & Therapy Laboratory, Cellular and Molecular Medicine Department, KU Leuven - University of Leuven, 3000 Leuven, Belgium
| | - Tom Verfaillie
- Cell Death Research & Therapy Laboratory, Cellular and Molecular Medicine Department, KU Leuven - University of Leuven, 3000 Leuven, Belgium
| | - Terje Johansen
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø, 9037 Tromsø, Norway
| | - Jacques Piette
- Virology and Immunology Unit, GiGA-R, GiGA B34, University of Liège, 4000 Liège, Belgium.
| | - Patrizia Agostinis
- Cell Death Research & Therapy Laboratory, Cellular and Molecular Medicine Department, KU Leuven - University of Leuven, 3000 Leuven, Belgium.
| |
Collapse
|