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Reis HBD, Carvalho ME, Espigolan R, Poleti MD, Ambrizi DR, Berton MP, Ferraz JBS, de Mattos Oliveira EC, Eler JP. Genome-Wide Association (GWAS) Applied to Carcass and Meat Traits of Nellore Cattle. Metabolites 2023; 14:6. [PMID: 38276296 PMCID: PMC10818672 DOI: 10.3390/metabo14010006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/14/2023] [Accepted: 11/22/2023] [Indexed: 01/27/2024] Open
Abstract
The meat market has enormous importance for the world economy, and the quality of the product offered to the consumer is fundamental for the success of the sector. In this study, we analyzed a database which contained information on 2470 animals from a commercial farm in the state of São Paulo, Brazil. Of this total, 2181 animals were genotyped, using 777,962 single-nucleotide polymorphisms (SNPs). After quality control analysis, 468,321 SNPs provided information on the number of genotyped animals. Genome-wide association analyses (GWAS) were performed for the characteristics of the rib eye area (REA), subcutaneous fat thickness (SFT), shear force at 7 days' ageing (SF7), and intramuscular fat (IMF), with the aid of the single-step genomic best linear unbiased prediction (ssGBLUP) method, with the purpose of identifying possible genomic windows (~1 Mb) responsible for explaining at least 0.5% of the genetic variance of the traits under analysis (≥0.5%). These genomic regions were used in a gene search and enrichment analyses using MeSH terms. The distributed heritability coefficients were 0.14, 0.20, 0.18, and 0.21 for REA, SFT, SF7, and IMF, respectively. The GWAS results indicated significant genomic windows for the traits of interest in a total of 17 chromosomes. Enrichment analyses showed the following significant terms (FDR ≤ 0.05) associated with the characteristics under study: for the REA, heat stress disorders and life cycle stages; for SFT, insulin and nonesterified fatty acids; for SF7, apoptosis and heat shock proteins (HSP27); and for IMF, metalloproteinase 2. In addition, KEGG (Kyoto encyclopedia of genes and genomes) enrichment analysis allowed us to highlight important metabolic pathways related to the studied phenotypes, such as the growth hormone synthesis, insulin-signaling, fatty acid metabolism, and ABC transporter pathways. The results obtained provide a better understanding of the molecular processes involved in the expression of the studied characteristics and may contribute to the design of selection strategies and future studies aimed at improving the productivity of Nellore cattle.
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Affiliation(s)
- Hugo Borges Dos Reis
- Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering (FZEA), University of Sao Paulo, Av. Duque de Caxias Norte, 225, Pirassununga 13635-900, SP, Brazil; (M.E.C.); (M.D.P.); (J.B.S.F.)
| | - Minos Esperândio Carvalho
- Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering (FZEA), University of Sao Paulo, Av. Duque de Caxias Norte, 225, Pirassununga 13635-900, SP, Brazil; (M.E.C.); (M.D.P.); (J.B.S.F.)
| | - Rafael Espigolan
- Department of Animal Science and Biological Sciences, Federal University of Santa Maria (UFSM), Av. Independencia, 3751, Palmeira das Missões 98300-000, RS, Brazil
| | - Mirele Daiana Poleti
- Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering (FZEA), University of Sao Paulo, Av. Duque de Caxias Norte, 225, Pirassununga 13635-900, SP, Brazil; (M.E.C.); (M.D.P.); (J.B.S.F.)
| | - Dewison Ricardo Ambrizi
- Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering (FZEA), University of Sao Paulo, Av. Duque de Caxias Norte, 225, Pirassununga 13635-900, SP, Brazil; (M.E.C.); (M.D.P.); (J.B.S.F.)
| | - Mariana Piatto Berton
- School of Agricultural and Veterinary Studies (FCAV), São Paulo State University, Jaboticabal 14884-900, SP, Brazil;
| | - José Bento Sterman Ferraz
- Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering (FZEA), University of Sao Paulo, Av. Duque de Caxias Norte, 225, Pirassununga 13635-900, SP, Brazil; (M.E.C.); (M.D.P.); (J.B.S.F.)
| | - Elisângela Chicaroni de Mattos Oliveira
- Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering (FZEA), University of Sao Paulo, Av. Duque de Caxias Norte, 225, Pirassununga 13635-900, SP, Brazil; (M.E.C.); (M.D.P.); (J.B.S.F.)
| | - Joanir Pereira Eler
- Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering (FZEA), University of Sao Paulo, Av. Duque de Caxias Norte, 225, Pirassununga 13635-900, SP, Brazil; (M.E.C.); (M.D.P.); (J.B.S.F.)
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Kim J, Bai H. Peroxisomal Stress Response and Inter-Organelle Communication in Cellular Homeostasis and Aging. Antioxidants (Basel) 2022; 11:192. [PMID: 35204075 PMCID: PMC8868334 DOI: 10.3390/antiox11020192] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/15/2022] [Accepted: 01/16/2022] [Indexed: 12/20/2022] Open
Abstract
Peroxisomes are key regulators of cellular and metabolic homeostasis. These organelles play important roles in redox metabolism, the oxidation of very-long-chain fatty acids (VLCFAs), and the biosynthesis of ether phospholipids. Given the essential role of peroxisomes in cellular homeostasis, peroxisomal dysfunction has been linked to various pathological conditions, tissue functional decline, and aging. In the past few decades, a variety of cellular signaling and metabolic changes have been reported to be associated with defective peroxisomes, suggesting that many cellular processes and functions depend on peroxisomes. Peroxisomes communicate with other subcellular organelles, such as the nucleus, mitochondria, endoplasmic reticulum (ER), and lysosomes. These inter-organelle communications are highly linked to the key mechanisms by which cells surveil defective peroxisomes and mount adaptive responses to protect them from damages. In this review, we highlight the major cellular changes that accompany peroxisomal dysfunction and peroxisomal inter-organelle communication through membrane contact sites, metabolic signaling, and retrograde signaling. We also discuss the age-related decline of peroxisomal protein import and its role in animal aging and age-related diseases. Unlike other organelle stress response pathways, such as the unfolded protein response (UPR) in the ER and mitochondria, the cellular signaling pathways that mediate stress responses to malfunctioning peroxisomes have not been systematically studied and investigated. Here, we coin these signaling pathways as "peroxisomal stress response pathways". Understanding peroxisomal stress response pathways and how peroxisomes communicate with other organelles are important and emerging areas of peroxisome research.
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Affiliation(s)
- Jinoh Kim
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Hua Bai
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
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Boontem P, Yamashima T. Hydroxynonenal causes Langerhans cell degeneration in the pancreas of Japanese macaque monkeys. PLoS One 2021; 16:e0245702. [PMID: 34748564 PMCID: PMC8575276 DOI: 10.1371/journal.pone.0245702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 09/18/2021] [Indexed: 11/21/2022] Open
Abstract
Background For their functions of insulin biosynthesis and glucose- and fatty acid- mediated insulin secretion, Langerhans β-cells require an intracellular milieu rich in oxygen. This requirement makes β-cells, with their constitutively low antioxidative defense, susceptible to the oxidative stress. Although much progress has been made in identifying its molecular basis in experimental systems, whether the oxidative stress due to excessive fatty acids plays a crucial role in the Langerhans cell degeneration in primates is still debated. Methods Focusing on Hsp70.1, which has dual functions as molecular chaperone and lysosomal stabilizer, the mechanism of lipotoxicity to Langerhans cells was studied using macaque monkeys after the consecutive injections of the lipid peroxidation product ‘hydroxynonenal’. Based on the ‘calpain-cathepsin hypothesis’ formulated in 1998, calpain activation, Hsp70.1 cleavage, and lysosomal integrity were studied by immunofluorescence histochemistry, electron microscopy, and Western blotting. Results Light microscopy showed more abundant vacuole formation in the hydroxynonenal-treated islet cells than the control cells. Electron microscopy showed that vacuolar changes, which were identified as enlarged rough ER, occurred mainly in β-cells followed by δ-cells. Intriguingly, both cell types showed a marked decrease in insulin and somatostatin granules. Furthermore, they exhibited marked increases in peroxisomes, autophagosomes/autolysosomes, lysosomal and peroxisomal membrane rupture/permeabilization, and mitochondrial degeneration. Disrupted peroxisomes were often localized in the close vicinity of degenerating mitochondria or autolysosomes. Immunofluorescence histochemical analysis showed an increased co-localization of activated μ-calpain and Hsp70.1 with the extralysosomal release of cathepsin B. Western blotting showed increases in μ-calpain activation, Hsp70.1 cleavage, and expression of the hydroxynonenal receptor GPR109A. Conclusions Taken together, these data implicate hydroxynonenal in both oxidation of Hsp70.1 and activation of μ-calpain. The calpain-mediated cleavage of the carbonylated Hsp70.1, may cause lysosomal membrane rupture/permeabilization. The low defense of primate Langerhans cells against hydroxynonenal and peroxisomally-generated hydrogen peroxide, was presumably overwhelmed to facilitate cell degeneration.
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Affiliation(s)
| | - Tetsumori Yamashima
- Departments of Cell Metabolism and Nutrition, Kanazawa, Japan
- Psychiatry and Behavioral Science, Kanazawa, Japan
- * E-mail:
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Bharath LP, Rockhold JD, Conway R. Selective Autophagy in Hyperglycemia-Induced Microvascular and Macrovascular Diseases. Cells 2021; 10:cells10082114. [PMID: 34440882 PMCID: PMC8392047 DOI: 10.3390/cells10082114] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/07/2021] [Accepted: 08/13/2021] [Indexed: 02/06/2023] Open
Abstract
Dysregulation of autophagy is an important underlying cause in the onset and progression of many metabolic diseases, including diabetes. Studies in animal models and humans show that impairment in the removal and the recycling of organelles, in particular, contributes to cellular damage, functional failure, and the onset of metabolic diseases. Interestingly, in certain contexts, inhibition of autophagy can be protective. While the inability to upregulate autophagy can play a critical role in the development of diseases, excessive autophagy can also be detrimental, making autophagy an intricately regulated process, the altering of which can adversely affect organismal health. Autophagy is indispensable for maintaining normal cardiac and vascular structure and function. Patients with diabetes are at a higher risk of developing and dying from vascular complications. Autophagy dysregulation is associated with the development of heart failure, many forms of cardiomyopathy, atherosclerosis, myocardial infarction, and microvascular complications in diabetic patients. Here, we review the recent findings on selective autophagy in hyperglycemia and diabetes-associated microvascular and macrovascular complications.
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Mechanisms and Functions of Pexophagy in Mammalian Cells. Cells 2021; 10:cells10051094. [PMID: 34063724 PMCID: PMC8147788 DOI: 10.3390/cells10051094] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/28/2021] [Accepted: 05/01/2021] [Indexed: 12/17/2022] Open
Abstract
Peroxisomes play essential roles in diverse cellular metabolism functions, and their dynamic homeostasis is maintained through the coordination of peroxisome biogenesis and turnover. Pexophagy, selective autophagic degradation of peroxisomes, is a major mechanism for removing damaged and/or superfluous peroxisomes. Dysregulation of pexophagy impairs the physiological functions of peroxisomes and contributes to the progression of many human diseases. However, the mechanisms and functions of pexophagy in mammalian cells remain largely unknown compared to those in yeast. This review focuses on mammalian pexophagy and aims to advance the understanding of the roles of pexophagy in human health and diseases. Increasing evidence shows that ubiquitination can serve as a signal for pexophagy, and ubiquitin-binding receptors, substrates, and E3 ligases/deubiquitinases involved in pexophagy have been described. Alternatively, pexophagy can be achieved in a ubiquitin-independent manner. We discuss the mechanisms of these ubiquitin-dependent and ubiquitin-independent pexophagy pathways and summarize several inducible conditions currently used to study pexophagy. We highlight several roles of pexophagy in human health and how its dysregulation may contribute to diseases.
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Niture S, Lin M, Rios-Colon L, Qi Q, Moore JT, Kumar D. Emerging Roles of Impaired Autophagy in Fatty Liver Disease and Hepatocellular Carcinoma. Int J Hepatol 2021; 2021:6675762. [PMID: 33976943 PMCID: PMC8083829 DOI: 10.1155/2021/6675762] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 03/16/2021] [Accepted: 04/06/2021] [Indexed: 02/07/2023] Open
Abstract
Autophagy is a conserved catabolic process that eliminates dysfunctional cytosolic biomolecules through vacuole-mediated sequestration and lysosomal degradation. Although the molecular mechanisms that regulate autophagy are not fully understood, recent work indicates that dysfunctional/impaired autophagic functions are associated with the development and progression of nonalcoholic fatty liver disease (NAFLD), alcoholic fatty liver disease (AFLD), and hepatocellular carcinoma (HCC). Autophagy prevents NAFLD and AFLD progression through enhanced lipid catabolism and decreasing hepatic steatosis, which is characterized by the accumulation of triglycerides and increased inflammation. However, as both diseases progress, autophagy can become impaired leading to exacerbation of both pathological conditions and progression into HCC. Due to the significance of impaired autophagy in these diseases, there is increased interest in studying pathways and targets involved in maintaining efficient autophagic functions as potential therapeutic targets. In this review, we summarize how impaired autophagy affects liver function and contributes to NAFLD, AFLD, and HCC progression. We will also explore how recent discoveries could provide novel therapeutic opportunities to effectively treat these diseases.
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Affiliation(s)
- Suryakant Niture
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University Durham, NC 27707, USA
| | - Minghui Lin
- The Fourth People's Hospital of Ningxia Hui Autonomous Region, Yinchuan, China 750021
| | - Leslimar Rios-Colon
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University Durham, NC 27707, USA
| | - Qi Qi
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University Durham, NC 27707, USA
| | - John T. Moore
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University Durham, NC 27707, USA
| | - Deepak Kumar
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University Durham, NC 27707, USA
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Miller DR, Thorburn A. Autophagy and organelle homeostasis in cancer. Dev Cell 2021; 56:906-918. [PMID: 33689692 PMCID: PMC8026727 DOI: 10.1016/j.devcel.2021.02.010] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/11/2021] [Accepted: 02/09/2021] [Indexed: 12/16/2022]
Abstract
Beginning with the earliest studies of autophagy in cancer, there have been indications that autophagy can both promote and inhibit cancer growth and progression; autophagy regulation of organelle homeostasis is similarly complicated. In this review we discuss pro- and antitumor effects of organelle-targeted autophagy and how this contributes to several hallmarks of cancer, such as evading cell death, genomic instability, and altered metabolism. Typically, the removal of damaged or dysfunctional organelles prevents tumor development but can also aid in proliferation or drug resistance in established tumors. By better understanding how organelle-specific autophagy takes place and can be manipulated, it may be possible to go beyond the brute-force approach of trying to manipulate all autophagy in order to improve therapeutic targeting of this process in cancer.
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Affiliation(s)
- Dannah R Miller
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Andrew Thorburn
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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Autophagy Dysfunction in Alzheimer's Disease: Mechanistic Insights and New Therapeutic Opportunities. Biol Psychiatry 2020; 87:797-807. [PMID: 31262433 DOI: 10.1016/j.biopsych.2019.05.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 04/24/2019] [Accepted: 05/11/2019] [Indexed: 01/05/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive memory loss due to aberrant accumulation of misfolded proteins inside and outside neurons and glial cells, leading to a loss of cellular protein homeostasis. Today, no therapy is available to block or slow down AD progression, and the mechanisms of the disease are not fully understood. Autophagy is an intracellular degradation pathway crucial to maintaining cellular homeostasis by clearing damaged organelles, pathogens, and unwanted protein aggregates. In recent years, autophagy dysfunction has gained considerable attention in AD and other neurodegenerative diseases because it has been linked to the accumulation of misfolded proteins that ultimately causes neuronal death in many of these disorders. Interestingly, autophagy-activating compounds have also shown some promising results in both clinical trials and preclinical studies. This review aims at summarizing the current knowledge on autophagy dysfunction in the context of AD pathophysiology, providing recent mechanistic insights on AD-mediated autophagic flux disruption and highlighting potential and novel therapeutic opportunities that target this system for AD therapy.
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Ke PY. Mitophagy in the Pathogenesis of Liver Diseases. Cells 2020; 9:cells9040831. [PMID: 32235615 PMCID: PMC7226805 DOI: 10.3390/cells9040831] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/25/2020] [Accepted: 03/27/2020] [Indexed: 02/07/2023] Open
Abstract
Autophagy is a catabolic process involving vacuolar sequestration of intracellular components and their targeting to lysosomes for degradation, thus supporting nutrient recycling and energy regeneration. Accumulating evidence indicates that in addition to being a bulk, nonselective degradation mechanism, autophagy may selectively eliminate damaged mitochondria to promote mitochondrial turnover, a process termed “mitophagy”. Mitophagy sequesters dysfunctional mitochondria via ubiquitination and cargo receptor recognition and has emerged as an important event in the regulation of liver physiology. Recent studies have shown that mitophagy may participate in the pathogenesis of various liver diseases, such as liver injury, liver steatosis/fatty liver disease, hepatocellular carcinoma, viral hepatitis, and hepatic fibrosis. This review summarizes the current knowledge on the molecular regulations and functions of mitophagy in liver physiology and the roles of mitophagy in the development of liver-related diseases. Furthermore, the therapeutic implications of targeting hepatic mitophagy to design a new strategy to cure liver diseases are discussed.
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Affiliation(s)
- Po-Yuan Ke
- Department of Biochemistry & Molecular Biology and Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan; ; Tel.: +886-3-211-8800 (ext. 5115); Fax: +886-3-211-8700
- Liver Research Center, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan
- Division of Allergy, Immunology, and Rheumatology, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan
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Lakkaraju A, Umapathy A, Tan LX, Daniele L, Philp NJ, Boesze-Battaglia K, Williams DS. The cell biology of the retinal pigment epithelium. Prog Retin Eye Res 2020; 78:100846. [PMID: 32105772 PMCID: PMC8941496 DOI: 10.1016/j.preteyeres.2020.100846] [Citation(s) in RCA: 185] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 02/19/2020] [Accepted: 02/23/2020] [Indexed: 02/07/2023]
Abstract
The retinal pigment epithelium (RPE), a monolayer of post-mitotic polarized epithelial cells, strategically situated between the photoreceptors and the choroid, is the primary caretaker of photoreceptor health and function. Dysfunction of the RPE underlies many inherited and acquired diseases that cause permanent blindness. Decades of research have yielded valuable insight into the cell biology of the RPE. In recent years, new technologies such as live-cell imaging have resulted in major advancement in our understanding of areas such as the daily phagocytosis and clearance of photoreceptor outer segment tips, autophagy, endolysosome function, and the metabolic interplay between the RPE and photoreceptors. In this review, we aim to integrate these studies with an emphasis on appropriate models and techniques to investigate RPE cell biology and metabolism, and discuss how RPE cell biology informs our understanding of retinal disease.
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Affiliation(s)
- Aparna Lakkaraju
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Ankita Umapathy
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Li Xuan Tan
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Lauren Daniele
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Nancy J Philp
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David S Williams
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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Germain K, Kim PK. Pexophagy: A Model for Selective Autophagy. Int J Mol Sci 2020; 21:ijms21020578. [PMID: 31963200 PMCID: PMC7013971 DOI: 10.3390/ijms21020578] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/09/2020] [Accepted: 01/13/2020] [Indexed: 01/03/2023] Open
Abstract
The removal of damaged or superfluous organelles from the cytosol by selective autophagy is required to maintain organelle function, quality control and overall cellular homeostasis. Precisely how substrate selectivity is achieved, and how individual substrates are degraded during selective autophagy in response to both extracellular and intracellular cues is not well understood. The aim of this review is to highlight pexophagy, the autophagic degradation of peroxisomes, as a model for selective autophagy. Peroxisomes are dynamic organelles whose abundance is rapidly modulated in response to metabolic demands. Peroxisomes are routinely turned over by pexophagy for organelle quality control yet can also be degraded by pexophagy in response to external stimuli such as amino acid starvation or hypoxia. This review discusses the molecular machinery and regulatory mechanisms governing substrate selectivity during both quality-control pexophagy and pexophagy in response to external stimuli, in yeast and mammalian systems. We draw lessons from pexophagy to infer how the cell may coordinate the degradation of individual substrates by selective autophagy across different cellular cues.
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Affiliation(s)
- Kyla Germain
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Peter K. Kim
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Correspondence: ; Tel.: +1-416-813-5983
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Autophagy in bone homeostasis and the onset of osteoporosis. Bone Res 2019; 7:28. [PMID: 31666998 PMCID: PMC6804951 DOI: 10.1038/s41413-019-0058-7] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/28/2019] [Accepted: 06/02/2019] [Indexed: 02/06/2023] Open
Abstract
Autophagy is an evolutionarily conserved intracellular process, in which domestic cellular components are selectively digested for the recycling of nutrients and energy. This process is indispensable for cell homeostasis maintenance and stress responses. Both genetic and functional studies have demonstrated that multiple proteins involved in autophagic activities are critical to the survival, differentiation, and functioning of bone cells, including osteoblasts, osteocytes, and osteoclasts. Dysregulation at the level of autophagic activity consequently disturbs the balance between bone formation and bone resorption and mediates the onset and progression of multiple bone diseases, including osteoporosis. This review aims to introduce the topic of autophagy, summarize the understanding of its relevance in bone physiology, and discuss its role in the onset of osteoporosis and therapeutic potential.
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Ke PY. Diverse Functions of Autophagy in Liver Physiology and Liver Diseases. Int J Mol Sci 2019; 20:E300. [PMID: 30642133 PMCID: PMC6358975 DOI: 10.3390/ijms20020300] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 01/05/2019] [Accepted: 01/08/2019] [Indexed: 01/09/2023] Open
Abstract
Autophagy is a catabolic process by which eukaryotic cells eliminate cytosolic materials through vacuole-mediated sequestration and subsequent delivery to lysosomes for degradation, thus maintaining cellular homeostasis and the integrity of organelles. Autophagy has emerged as playing a critical role in the regulation of liver physiology and the balancing of liver metabolism. Conversely, numerous recent studies have indicated that autophagy may disease-dependently participate in the pathogenesis of liver diseases, such as liver hepatitis, steatosis, fibrosis, cirrhosis, and hepatocellular carcinoma. This review summarizes the current knowledge on the functions of autophagy in hepatic metabolism and the contribution of autophagy to the pathophysiology of liver-related diseases. Moreover, the impacts of autophagy modulation on the amelioration of the development and progression of liver diseases are also discussed.
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Affiliation(s)
- Po-Yuan Ke
- Department of Biochemistry & Molecular Biology and Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan.
- Liver Research Center, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan.
- Division of Allergy, Immunology, and Rheumatology, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan.
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Abstract
Peroxisomes are ubiquitous and highly dynamic organelles that play a central role in the metabolism of lipids and reactive oxygen species. The importance of peroxisomal metabolism is illustrated by severe peroxisome biogenesis disorders in which functional peroxisomes are absent or disorders caused by single peroxisomal enzyme deficiencies. These multisystemic diseases manifest specific clinical and biochemical disturbances that originate from the affected peroxisomal pathways. An emerging role of the peroxisome has been identified in many types of diseases, including cancer, neurodegenerative disorders, aging, obesity, and diabetes. Peroxisome homeostasis is achieved via a tightly regulated interplay between peroxisome biogenesis and degradation via selective autophagy, which is commonly known as "pexophagy". Dysregulation of either peroxisome biogenesis or pexophagy may be detrimental to the health of cells and contribute to the pathophysiology of these diseases. Autophagy is an evolutionary conserved catabolic process for non-selective degradation of macromolecules and organelles in response to various stressors. In selective autophagy, specific cargo-recognizing receptors connect the cargo to the core autophagic machinery, and additional posttranslational modifications such as ubiquitination and phosphorylation regulate this process. Several stress conditions have been shown to stimulate pexophagy and decrease peroxisome abundance. However, our understanding of the mechanisms that particularly regulate mammalian pexophagy has been limited. In recent years considerable progress has been made uncovering signaling pathways, autophagy receptors and adaptors as well as posttranslational modifications involved in pexophagy. In this review, which is published back-to-back with a peroxisome review by Islinger et al. [(Histochem Cell Biol 137:547-574, 2018). The peroxisome: an update on mysteries 2.0], we focus on recent novel findings on the underlying molecular mechanisms of pexophagy in yeast and mammalian cells and highlight concerns and gaps in our knowledge.
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Walker CL, Pomatto LCD, Tripathi DN, Davies KJA. Redox Regulation of Homeostasis and Proteostasis in Peroxisomes. Physiol Rev 2018; 98:89-115. [PMID: 29167332 PMCID: PMC6335096 DOI: 10.1152/physrev.00033.2016] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 06/19/2017] [Accepted: 06/21/2017] [Indexed: 02/08/2023] Open
Abstract
Peroxisomes are highly dynamic intracellular organelles involved in a variety of metabolic functions essential for the metabolism of long-chain fatty acids, d-amino acids, and many polyamines. A byproduct of peroxisomal metabolism is the generation, and subsequent detoxification, of reactive oxygen and nitrogen species, particularly hydrogen peroxide (H2O2). Because of its relatively low reactivity (as a mild oxidant), H2O2 has a comparatively long intracellular half-life and a high diffusion rate, all of which makes H2O2 an efficient signaling molecule. Peroxisomes also have intricate connections to mitochondria, and both organelles appear to play important roles in regulating redox signaling pathways. Peroxisomal proteins are also subject to oxidative modification and inactivation by the reactive oxygen and nitrogen species they generate, but the peroxisomal LonP2 protease can selectively remove such oxidatively damaged proteins, thus prolonging the useful lifespan of the organelle. Peroxisomal homeostasis must adapt to the metabolic state of the cell, by a combination of peroxisome proliferation, the removal of excess or badly damaged organelles by autophagy (pexophagy), as well as by processes of peroxisome inheritance and motility. More recently the tumor suppressors ataxia telangiectasia mutate (ATM) and tuberous sclerosis complex (TSC), which regulate mTORC1 signaling, have been found to regulate pexophagy in response to variable levels of certain reactive oxygen and nitrogen species. It is now clear that any significant loss of peroxisome homeostasis can have devastating physiological consequences. Peroxisome dysregulation has been implicated in several metabolic diseases, and increasing evidence highlights the important role of diminished peroxisomal functions in aging processes.
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Affiliation(s)
- Cheryl L Walker
- Center for Precision Environmental Health and Departments of Molecular & Cellular Biology and Medicine, Baylor College of Medicine, Houston, Texas; and Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center and Division of Molecular & Computational Biology, Department of Biological Sciences of the Dornsife College of Letters, Arts, and Sciences, The University of Southern California, Los Angeles, California
| | - Laura C D Pomatto
- Center for Precision Environmental Health and Departments of Molecular & Cellular Biology and Medicine, Baylor College of Medicine, Houston, Texas; and Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center and Division of Molecular & Computational Biology, Department of Biological Sciences of the Dornsife College of Letters, Arts, and Sciences, The University of Southern California, Los Angeles, California
| | - Durga Nand Tripathi
- Center for Precision Environmental Health and Departments of Molecular & Cellular Biology and Medicine, Baylor College of Medicine, Houston, Texas; and Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center and Division of Molecular & Computational Biology, Department of Biological Sciences of the Dornsife College of Letters, Arts, and Sciences, The University of Southern California, Los Angeles, California
| | - Kelvin J A Davies
- Center for Precision Environmental Health and Departments of Molecular & Cellular Biology and Medicine, Baylor College of Medicine, Houston, Texas; and Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center and Division of Molecular & Computational Biology, Department of Biological Sciences of the Dornsife College of Letters, Arts, and Sciences, The University of Southern California, Los Angeles, California
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Colasante C, Chen J, Ahlemeyer B, Bonilla-Martinez R, Karnati S, Baumgart-Vogt E. New insights into the distribution, protein abundance and subcellular localisation of the endogenous peroxisomal biogenesis proteins PEX3 and PEX19 in different organs and cell types of the adult mouse. PLoS One 2017; 12:e0183150. [PMID: 28817674 PMCID: PMC5560687 DOI: 10.1371/journal.pone.0183150] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 07/31/2017] [Indexed: 11/19/2022] Open
Abstract
Peroxisomes are ubiquitous organelles mainly involved in ROS and lipid metabolism. Their abundance, protein composition and metabolic function vary depending on the cell type and adjust to different intracellular and environmental factors such as oxidative stress or nutrition. The biogenesis and proliferation of these important organelles are regulated by proteins belonging to the peroxin (PEX) family. PEX3, an integral peroxisomal membrane protein, and the cytosolic shuttling receptor PEX19 are thought to be responsible for the early steps of peroxisome biogenesis and assembly of their matrix protein import machinery. Recently, both peroxins were suggested to be also involved in the autophagy of peroxisomes (pexophagy). Despite the fact that distribution and intracellular abundance of these proteins might regulate the turnover of the peroxisomal compartment in a cell type-specific manner, a comprehensive analysis of the endogenous PEX3 and PEX19 distribution in different organs is still missing. In this study, we have therefore generated antibodies against endogenous mouse PEX3 and PEX19 and analysed their abundance and subcellular localisation in various mouse organs, tissues and cell types and compared it to the one of three commonly used peroxisomal markers (PEX14, ABCD3 and catalase). Our results revealed that the abundance of PEX3, PEX19, PEX14, ABCD3 and catalase strongly varies in the analysed organs and cell types, suggesting that peroxisome abundance, biogenesis and matrix protein import are independently regulated. We further found that in some organs, such as heart and skeletal muscle, the majority of the shuttling receptor PEX19 is bound to the peroxisomal membrane and that a strong variability exists in the cell type-specific ratio of cytosol- and peroxisome-associated PEX19. In conclusion, our results indicate that peroxisomes in various cell types are heterogeneous with regards to their matrix, membrane and biogenesis proteins.
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Affiliation(s)
- Claudia Colasante
- Institute for Anatomy and Cell Biology, Division of Medical Cell Biology, Justus Liebig University of Giessen, Giessen, Germany
| | - Jiangping Chen
- Institute for Anatomy and Cell Biology, Division of Medical Cell Biology, Justus Liebig University of Giessen, Giessen, Germany
| | - Barbara Ahlemeyer
- Institute for Anatomy and Cell Biology, Division of Medical Cell Biology, Justus Liebig University of Giessen, Giessen, Germany
| | - Rocio Bonilla-Martinez
- Institute for Anatomy and Cell Biology, Division of Medical Cell Biology, Justus Liebig University of Giessen, Giessen, Germany
| | - Srikanth Karnati
- Institute for Anatomy and Cell Biology, Division of Medical Cell Biology, Justus Liebig University of Giessen, Giessen, Germany
| | - Eveline Baumgart-Vogt
- Institute for Anatomy and Cell Biology, Division of Medical Cell Biology, Justus Liebig University of Giessen, Giessen, Germany
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Cavallini G, Donati A, Taddei M, Bergamini E. Peroxisomes proliferation and pharmacological stimulation of autophagy in rat liver: evidence to support that autophagy may remove the "older" peroxisomes. Mol Cell Biochem 2017; 431:97-102. [PMID: 28255846 DOI: 10.1007/s11010-017-2979-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 02/24/2017] [Indexed: 01/25/2023]
Abstract
Like mitochondria, peroxisomes produce reactive oxygen species (ROS), compounds which have been implicated to play an important role in many degenerative diseases and aging itself, and an exaggerated ROS production might occur in altered or older organelles. Growing evidence shows that autophagy, a required function in cell housekeeping during fasting, can remove damaged macromolecules, organelles, and membranes selectively. Proliferation of peroxisomes can be enhanced in liver cells by perfluorooctanoic acid (PFOA), which causes a marked increase of the Acyl-CoA oxidase (ACOX) activity and no significant change in urate oxidase (UOX) activity. The administration of antilipolytic drugs to fasted animals was shown to intensify autophagy. Here we tested the hypothesis that autophagy may distinguish and remove older from younger peroxisomes in rat liver. Male Sprague-Dawley rats were given PFOA (150 mg/kg body weight) or vehicle. Animals were sacrificed at different times following PFOA administration, and 3 h after the induction of autophagy with the antilipolytic agent 3,5-dimethyl pyrazole (DMP, 12 mg/kg body weight). The levels of ACOX and UOX activity were measured in the liver tissue. Results showed that autophagy caused a parallel, significant decrease in both enzymes activity in control rats, and that in PFOA-treated rats the effects were different and changed with PFOA time administration. Changes are compatible with the hypothesis that newly formed ACOX-rich peroxisomes are resistant to pexophagy and that sensitivity to pexophagy increases with increasing peroxisomal "age." In conclusion, there is indirect evidence supporting the hypothesis that autophagy may recognize and degrade older peroxisomes.
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Affiliation(s)
- Gabriella Cavallini
- Interdepartmental Research Centre on Biology and Pathology of Aging, University of Pisa, Via Roma 55, 56126, Pisa, Italy.
| | - Alessio Donati
- Interdepartmental Research Centre on Biology and Pathology of Aging, University of Pisa, Via Roma 55, 56126, Pisa, Italy
| | - Michele Taddei
- Interdepartmental Research Centre on Biology and Pathology of Aging, University of Pisa, Via Roma 55, 56126, Pisa, Italy
| | - Ettore Bergamini
- Interdepartmental Research Centre on Biology and Pathology of Aging, University of Pisa, Via Roma 55, 56126, Pisa, Italy
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Wang Q, You T, Fan H, Wang Y, Chu T, Poncz M, Zhu L. Rapamycin and bafilomycin A1 alter autophagy and megakaryopoiesis. Platelets 2016; 28:82-89. [PMID: 27534900 DOI: 10.1080/09537104.2016.1204436] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Autophagy is an effective strategy for cell development by recycling cytoplasmic constituents. Genetic deletion of autophagy mediator Atg7 in hematopoietic stem cells (HSCs) can lead to failure of megakaryopoiesis and enhanced autophagy has been implicated in various hematological disorders such as immune thrombocytopenia and myelodysplastic syndrome. Here, we examined the hypothesis that optimal autophagy is essential for megakaryopoiesis and thrombopoiesis by altering autophagy using pharmacological approaches. When autophagy was induced by rapamycin or inhibited by bafilomycin A1 in fetal liver cells, we observed a significant decrease in high ploidy megakaryocytes, a reduction of CD41 and CD61 co-expressing cells, and less proplatelet or platelet formation. Additionally, reduced cell size was shown in megakaryocytes derived from rapamycin, but not bafilomycin A1-treated mouse fetal liver cells. However, when autophagy was altered in mature megakaryocytes, we observed no significant change in proplatelet formation, which was consistent with normal platelet counts, megakaryocyte numbers, and ploidy in Atg7flox/flox PF4-Cre mice with megakaryocyte- and platelet-specific deletion of autophagy-related gene Atg7. Therefore, our findings suggest that either induction or inhibition of autophagy in the early stage of megakaryopoiesis suppresses megakaryopoiesis and thrombopoiesis.
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Affiliation(s)
- Qi Wang
- a Cyrus Tang Hematology Center , Soochow University , Suzhou , China.,b Collaborative Innovation Center of Hematology , Soochow University , Suzhou , China
| | - Tao You
- a Cyrus Tang Hematology Center , Soochow University , Suzhou , China.,d Jiangsu Institute of Hematology of The First Affiliated Hospital , Soochow University , Suzhou , China
| | - Hongqiong Fan
- a Cyrus Tang Hematology Center , Soochow University , Suzhou , China
| | - Yinyan Wang
- a Cyrus Tang Hematology Center , Soochow University , Suzhou , China
| | - Tinatian Chu
- a Cyrus Tang Hematology Center , Soochow University , Suzhou , China.,d Jiangsu Institute of Hematology of The First Affiliated Hospital , Soochow University , Suzhou , China
| | - Mortimer Poncz
- f Department of Pediatrics, Children's Hospital of Philadelphia , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Li Zhu
- a Cyrus Tang Hematology Center , Soochow University , Suzhou , China.,b Collaborative Innovation Center of Hematology , Soochow University , Suzhou , China.,c MOH Key Lab of Thrombosis and Hemostasis , Soochow University , Suzhou , China.,e Jiangsu Key Lab of Preventive and translational Medicine for Geriatric Diseases , Soochow University , Suzhou , China
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Abstract
SIGNIFICANCE Peroxisomes are organelles present in most eukaryotic cells. The organs with the highest density of peroxisomes are the liver and kidneys. Peroxisomes possess more than fifty enzymes and fulfill a multitude of biological tasks. They actively participate in apoptosis, innate immunity, and inflammation. In recent years, a considerable amount of evidence has been collected to support the involvement of peroxisomes in the pathogenesis of kidney injury. RECENT ADVANCES The nature of the two most important peroxisomal tasks, beta-oxidation of fatty acids and hydrogen peroxide turnover, functionally relates peroxisomes to mitochondria. Further support for their communication and cooperation is furnished by the evidence that both organelles share the components of their division machinery. Until recently, the majority of studies on the molecular mechanisms of kidney injury focused primarily on mitochondria and neglected peroxisomes. CRITICAL ISSUES The aim of this concise review is to introduce the reader to the field of peroxisome biology and to provide an overview of the evidence about the contribution of peroxisomes to the development and progression of kidney injury. The topics of renal ischemia-reperfusion injury, endotoxin-induced kidney injury, diabetic nephropathy, and tubulointerstitial fibrosis, as well as the potential therapeutic implications of peroxisome activation, are addressed in this review. FUTURE DIRECTIONS Despite recent progress, further studies are needed to elucidate the molecular mechanisms induced by dysfunctional peroxisomes and the role of the dysregulated mitochondria-peroxisome axis in the pathogenesis of renal injury. Antioxid. Redox Signal. 25, 217-231.
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Affiliation(s)
- Radovan Vasko
- Department of Nephrology and Rheumatology, University Medical Center Göttingen , Göttingen, Germany
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20
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Peroxisome homeostasis: Mechanisms of division and selective degradation of peroxisomes in mammals. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:984-91. [DOI: 10.1016/j.bbamcr.2015.09.032] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 09/25/2015] [Accepted: 09/28/2015] [Indexed: 12/25/2022]
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Wang X, Li S, Liu Y, Ma C. Redox regulated peroxisome homeostasis. Redox Biol 2014; 4:104-8. [PMID: 25545794 PMCID: PMC4309859 DOI: 10.1016/j.redox.2014.12.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/13/2014] [Accepted: 12/15/2014] [Indexed: 11/15/2022] Open
Abstract
Peroxisomes are ubiquitous organelles present in nearly all eukaryotic cells. Conserved functions of peroxisomes encompass beta-oxidation of fatty acids and scavenging of reactive oxygen species generated from diverse peroxisomal metabolic pathways. Peroxisome content, number, and size can change quickly in response to environmental and/or developmental cues. To achieve efficient peroxisome homeostasis, peroxisome biogenesis and degradation must be orchestrated. We review the current knowledge on redox regulated peroxisome biogenesis and degradation with an emphasis on yeasts and plants. Conserved functions of peroxisomes include β-oxidation of fatty acids and scavenging of ROS. Peroxisome homeostasis is achieved by coordinating biogenesis and degradation. Repression of peroxisome biogenesis under oxidative stress. Superfluous and oxidative damaged peroxisomes are degraded by pexophagy.
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Affiliation(s)
- Xiaofeng Wang
- College of Life Sciences, Shandong Normal University, Wenhua East Road 88, Jinan, Shandong 250014, China
| | - Shuo Li
- College of Life Sciences, Shandong Normal University, Wenhua East Road 88, Jinan, Shandong 250014, China
| | - Yu Liu
- College of Life Sciences, Shandong Normal University, Wenhua East Road 88, Jinan, Shandong 250014, China
| | - Changle Ma
- College of Life Sciences, Shandong Normal University, Wenhua East Road 88, Jinan, Shandong 250014, China.
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23
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Yamashita SI, Abe K, Tatemichi Y, Fujiki Y. The membrane peroxin PEX3 induces peroxisome-ubiquitination-linked pexophagy. Autophagy 2014; 10:1549-64. [PMID: 25007327 DOI: 10.4161/auto.29329] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Peroxisomes are degraded by a selective type of autophagy known as pexophagy. Several different types of pexophagy have been reported in mammalian cells. However, the mechanisms underlying how peroxisomes are recognized by autophagy-related machinery remain elusive. PEX3 is a peroxisomal membrane protein (PMP) that functions in the import of PMPs into the peroxisomal membrane and has been shown to interact with pexophagic receptor proteins during pexophagy in yeast. Thus, PEX3 is important not only for peroxisome biogenesis, but also for peroxisome degradation. However, whether PEX3 is involved in the degradation of peroxisomes in mammalian cells is unclear. Here, we report that high levels of PEX3 expression induce pexophagy. In PEX3-loaded cells, peroxisomes are ubiquitinated, clustered, and degraded in lysosomes. Peroxisome targeting of PEX3 is essential for the initial step of this degradation pathway. The degradation of peroxisomes is inhibited by treatment with autophagy inhibitors or siRNA against NBR1, which encodes an autophagic receptor protein. These results indicate that ubiquitin- and NBR1-mediated pexophagy is induced by increased expression of PEX3 in mammalian cells. In addition, another autophagic receptor protein, SQSTM1/p62, is required only for the clustering of peroxisomes. Expression of a PEX3 mutant with substitution of all lysine and cysteine residues by arginine and alanine, respectively, also induces peroxisome ubiquitination and degradation, hence suggesting that ubiquitination of PEX3 is dispensable for pexophagy and an endogenous, unidentified peroxisomal protein is ubiquitinated on the peroxisomal membrane.
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Affiliation(s)
- Shun-ichi Yamashita
- Department of Biology; Faculty of Sciences; Kyushu University Graduate School; Fukuoka, Japan
| | - Kakeru Abe
- Graduate School of Systems Life Sciences; Kyushu University Graduate School; Fukuoka, Japan
| | - Yuki Tatemichi
- Graduate School of Systems Life Sciences; Kyushu University Graduate School; Fukuoka, Japan
| | - Yukio Fujiki
- Department of Biology; Faculty of Sciences; Kyushu University Graduate School; Fukuoka, Japan
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24
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Hale AN, Ledbetter DJ, Gawriluk TR, Rucker EB. Autophagy: regulation and role in development. Autophagy 2014; 9:951-72. [PMID: 24121596 DOI: 10.4161/auto.24273] [Citation(s) in RCA: 252] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Autophagy is an evolutionarily conserved cellular process through which long-lived proteins and damaged organelles are recycled to maintain energy homeostasis. These proteins and organelles are sequestered into a double-membrane structure, or autophagosome, which subsequently fuses with a lysosome in order to degrade the cargo. Although originally classified as a type of programmed cell death, autophagy is more widely viewed as a basic cell survival mechanism to combat environmental stressors. Autophagy genes were initially identified in yeast and were found to be necessary to circumvent nutrient stress and starvation. Subsequent elucidation of mammalian gene counterparts has highlighted the importance of this process to normal development. This review provides an overview of autophagy, the types of autophagy, its regulation and its known impact on development gleaned primarily from murine models.
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Affiliation(s)
- Amber N Hale
- Department of Biology; University of Kentucky; Lexington, KY USA
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Abstract
SIGNIFICANCE Autophagy is a highly conserved eukaryotic cellular recycling process. Through the degradation of cytoplasmic organelles, proteins, and macromolecules, and the recycling of the breakdown products, autophagy plays important roles in cell survival and maintenance. Accordingly, dysfunction of this process contributes to the pathologies of many human diseases. RECENT ADVANCES Extensive research is currently being done to better understand the process of autophagy. In this review, we describe current knowledge of the morphology, molecular mechanism, and regulation of mammalian autophagy. CRITICAL ISSUES At the mechanistic and regulatory levels, there are still many unanswered questions and points of confusion that have yet to be resolved. FUTURE DIRECTIONS Through further research, a more complete and accurate picture of the molecular mechanism and regulation of autophagy will not only strengthen our understanding of this significant cellular process, but will aid in the development of new treatments for human diseases in which autophagy is not functioning properly.
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Affiliation(s)
- Katherine R Parzych
- Department of Molecular, Cellular and Developmental Biology, Life Sciences Institute, University of Michigan , Ann Arbor, Michigan
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Jang I, Park S, Cho JW, Yigitkanli K, van Leyen K, Roth J. Genetic ablation and short-duration inhibition of lipoxygenase results in increased macroautophagy. Exp Cell Res 2013; 321:276-87. [PMID: 24291223 DOI: 10.1016/j.yexcr.2013.11.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Revised: 11/09/2013] [Accepted: 11/19/2013] [Indexed: 12/24/2022]
Abstract
12/15-lipoxygenase (12/15-LOX) is involved in organelle homeostasis by degrading mitochondria in maturing red blood cells and by eliminating excess peroxisomes in liver. Furthermore, 12/15-LOX contributes to diseases by exacerbating oxidative stress-related injury, notably in stroke. Nonetheless, it is unclear what the consequences are of abolishing 12/15-LOX activity. Mice in which the alox15 gene has been ablated do not show an obvious phenotype, and LOX enzyme inhibition is not overtly detrimental. We show here that liver histology is also unremarkable. However, electron microscopy demonstrated that 12/15-LOX knockout surprisingly leads to increased macroautophagy in the liver. Not only macroautophagy but also mitophagy and pexophagy were increased in hepatocytes, which otherwise showed unaltered fine structure and organelle morphology. These findings were substantiated by immunofluorescence showing significantly increased number of LC3 puncta and by Western blotting demonstrating a significant increase for LC3-II protein in both liver and brain homogenates of 12/15-LOX knockout mice. Inhibition of 12/15-LOX activity by treatment with four structurally different inhibitors had similar effects in cultured HepG2 hepatoma cells and SH-SY5Y neuroblastoma cells with significantly increased autophagy discernable already after 2 hours. Hence, our study reveals a link between ablation or inhibition of 12/15-LOX and stimulation of macroautophagy. The enhanced macroautophagy may be related to the known tissue-protective effects of LOX ablation or inhibition under various diseased conditions caused by oxidative stress and ischemia. This could provide an important cleaning mechanism of cells and tissues to prevent accumulation of damaged mitochondria and other cellular components.
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Affiliation(s)
- Insook Jang
- Department of Integrated OMICS for Biomedical Science, WCU Program of Graduate School, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, South Korea
| | - Sujin Park
- Department of Integrated OMICS for Biomedical Science, WCU Program of Graduate School, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, South Korea
| | - Jin Won Cho
- Department of Integrated OMICS for Biomedical Science, WCU Program of Graduate School, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, South Korea
| | - Kazim Yigitkanli
- Neuroprotection Research Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Klaus van Leyen
- Neuroprotection Research Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Jürgen Roth
- Department of Integrated OMICS for Biomedical Science, WCU Program of Graduate School, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, South Korea.
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Substrate recognition in selective autophagy and the ubiquitin-proteasome system. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:163-81. [PMID: 23545414 DOI: 10.1016/j.bbamcr.2013.03.019] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 03/15/2013] [Accepted: 03/20/2013] [Indexed: 12/21/2022]
Abstract
Dynamic protein turnover through regulated protein synthesis and degradation ensures cellular growth, proliferation, differentiation and adaptation. Eukaryotic cells utilize two mechanistically distinct but largely complementary systems - the 26S proteasome and the lysosome (or vacuole in yeast and plants) - to effectively target a wide range of proteins for degradation. The concerted action of the ubiquitination machinery and the 26S proteasome ensures the targeted and tightly regulated degradation of a subset of commonly short-lived cellular proteins. Autophagy is a distinct degradation pathway, which transports a highly heterogeneous set of cargos in dedicated vesicles, called autophagosomes, to the lysosome. There the cargo becomes degraded and its molecular building blocks are recycled. While general autophagy randomly engulfs portions of the cytosol, selective autophagy employs dedicated cargo adaptors to specifically enrich the forming autophagosomes for a certain type of cargo as a response to various intra- or extracellular signals. Selective autophagy targets a wide range of cargos including long-lived proteins and protein complexes, organelles, protein aggregates and even intracellular microbes. In this review we summarize available data on cargo recognition mechanisms operating in selective autophagy and the ubiquitin-proteasome system (UPS), and emphasize their differences and common themes. Moreover, we derive general regulatory principles underlying cargo recognition in selective autophagy, and describe the system-wide crosstalk between these two cellular protein degradation systems. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.
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Abstract
Peroxisomes are remarkably versatile cell organelles whose size, shape, number, and protein content can vary greatly depending on the organism, the developmental stage of the organism’s life cycle, and the environment in which the organism lives. The main functions usually associated with peroxisomes include the metabolism of lipids and reactive oxygen species. However, in recent years, it has become clear that these organelles may also act as intracellular signaling platforms that mediate developmental decisions by modulating extraperoxisomal concentrations of several second messengers. To fulfill their functions, peroxisomes physically and functionally interact with other cell organelles, including mitochondria and the endoplasmic reticulum. Defects in peroxisome dynamics can lead to organelle dysfunction and have been associated with various human disorders. The purpose of this paper is to thoroughly summarize and discuss the current concepts underlying peroxisome formation, multiplication, and degradation. In addition, this paper will briefly highlight what is known about the interplay between peroxisomes and other cell organelles and explore the physiological and pathological implications of this interorganellar crosstalk.
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Affiliation(s)
- Marc Fransen
- Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, P.O. Box 601, 3000 Leuven, Belgium
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29
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Pexophagy: the selective degradation of peroxisomes. Int J Cell Biol 2012; 2012:512721. [PMID: 22536249 PMCID: PMC3320016 DOI: 10.1155/2012/512721] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Accepted: 11/23/2011] [Indexed: 12/18/2022] Open
Abstract
Peroxisomes are single-membrane-bounded organelles present in the majority of eukaryotic cells. Despite the existence of great diversity among different species, cell types, and under different environmental conditions, peroxisomes contain enzymes involved in β-oxidation of fatty acids and the generation, as well as detoxification, of hydrogen peroxide. The exigency of all eukaryotic cells to quickly adapt to different environmental factors requires the ability to precisely and efficiently control peroxisome number and functionality. Peroxisome homeostasis is achieved by the counterbalance between organelle biogenesis and degradation. The selective degradation of superfluous or damaged peroxisomes is facilitated by several tightly regulated pathways. The most prominent peroxisome degradation system uses components of the general autophagy core machinery and is therefore referred to as “pexophagy.” In this paper we focus on recent developments in pexophagy and provide an overview of current knowledge and future challenges in the field. We compare different modes of pexophagy and mention shared and distinct features of pexophagy in yeast model systems, mammalian cells, and other organisms.
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30
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Islinger M, Grille S, Fahimi HD, Schrader M. The peroxisome: an update on mysteries. Histochem Cell Biol 2012; 137:547-74. [DOI: 10.1007/s00418-012-0941-4] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2012] [Indexed: 12/31/2022]
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Cuervo AM, Macian F. Autophagy, nutrition and immunology. Mol Aspects Med 2011; 33:2-13. [PMID: 21982744 DOI: 10.1016/j.mam.2011.09.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 09/24/2011] [Indexed: 01/05/2023]
Abstract
Turnover of cellular components in lysosomes or autophagy is an essential mechanism for cellular quality control. Added to this cleaning role, autophagy has recently been shown to participate in the dynamic interaction of cells with the surrounding environment by acting as a point of integration of extracellular cues. In this review, we focus on the relationship between autophagy and two types of environmental factors: nutrients and pathogens. We describe their direct effect on autophagy and discuss how the autophagic reaction to these stimuli allows cells to accommodate the requirements of the cellular response to stress, including those specific to the immune responses.
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Affiliation(s)
- Ana Maria Cuervo
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Extending the knowledge in histochemistry and cell biology. Histochem Cell Biol 2009; 133:1-40. [PMID: 19946696 DOI: 10.1007/s00418-009-0665-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2009] [Indexed: 01/21/2023]
Abstract
Central to modern Histochemistry and Cell Biology stands the need for visualization of cellular and molecular processes. In the past several years, a variety of techniques has been achieved bridging traditional light microscopy, fluorescence microscopy and electron microscopy with powerful software-based post-processing and computer modeling. Researchers now have various tools available to investigate problems of interest from bird's- up to worm's-eye of view, focusing on tissues, cells, proteins or finally single molecules. Applications of new approaches in combination with well-established traditional techniques of mRNA, DNA or protein analysis have led to enlightening and prudent studies which have paved the way toward a better understanding of not only physiological but also pathological processes in the field of cell biology. This review is intended to summarize articles standing for the progress made in "histo-biochemical" techniques and their manifold applications.
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Huybrechts SJ, Van Veldhoven PP, Brees C, Mannaerts GP, Los GV, Fransen M. Peroxisome dynamics in cultured mammalian cells. Traffic 2009; 10:1722-33. [PMID: 19719477 DOI: 10.1111/j.1600-0854.2009.00970.x] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Despite the identification and characterization of various proteins that are essential for peroxisome biogenesis, the origin and the turnover of peroxisomes are still unresolved critical issues. In this study, we used the HaloTag technology as a new approach to examine peroxisome dynamics in cultured mammalian cells. This technology is based on the formation of a covalent bond between the HaloTag protein--a mutated bacterial dehalogenase which is fused to the protein of interest--and a synthetic haloalkane ligand that contains a fluorophore or affinity tag. By using cell-permeable ligands of distinct fluorescence, it is possible to image distinct pools of newly synthesized proteins, generated from a single genetic HaloTag-containing construct, at different wavelengths. Here, we show that peroxisomes display an age-related heterogeneity with respect to their capacity to incorporate newly synthesized proteins. We also demonstrate that these organelles do not exchange their protein content. In addition, we present evidence that the matrix protein content of pre-existing peroxisomes is not evenly distributed over new organelles. Finally, we show that peroxisomes in cultured mammalian cells, under basal growth conditions, have a half-life of approximately 2 days and are mainly degraded by an autophagy-related mechanism. The implications of these findings are discussed.
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Affiliation(s)
- Sofie J Huybrechts
- Katholieke Universiteit Leuven, Faculteit Geneeskunde, Departement Moleculaire Celbiologie, LIPIT, Campus Gasthuisberg (O&N 1), Leuven, Belgium
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