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Raza S, Rajak S, Yen PM, Sinha RA. Autophagy and hepatic lipid metabolism: mechanistic insight and therapeutic potential for MASLD. NPJ METABOLIC HEALTH AND DISEASE 2024; 2:19. [PMID: 39100919 PMCID: PMC11296953 DOI: 10.1038/s44324-024-00022-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Accepted: 07/04/2024] [Indexed: 08/06/2024]
Abstract
Metabolic dysfunction-associated steatotic liver disease (MASLD) originates from a homeostatic imbalance in hepatic lipid metabolism. Increased fat deposition in the liver of people suffering from MASLD predisposes them to develop further metabolic derangements, including diabetes mellitus, metabolic dysfunction-associated steatohepatitis (MASH), and other end-stage liver diseases. Unfortunately, only limited pharmacological therapies exist for MASLD to date. Autophagy, a cellular catabolic process, has emerged as a primary mechanism of lipid metabolism in mammalian hepatocytes. Furthermore, preclinical studies with autophagy modulators have shown promising results in resolving MASLD and mitigating its progress into deleterious liver pathologies. In this review, we discuss our current understanding of autophagy-mediated hepatic lipid metabolism, its therapeutic modulation for MASLD treatment, and current limitations and scope for clinical translation.
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Affiliation(s)
- Sana Raza
- Department of Endocrinology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014 India
| | - Sangam Rajak
- Department of Endocrinology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014 India
| | - Paul M. Yen
- Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore, 169857 Singapore
| | - Rohit A. Sinha
- Department of Endocrinology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014 India
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2
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Kang N, Tan J, Yan S, Lin L, Gao Q. General autophagy-dependent and -independent lipophagic processes collaborate to regulate the overall level of lipophagy in yeast. Autophagy 2024; 20:1523-1536. [PMID: 38425021 PMCID: PMC11210923 DOI: 10.1080/15548627.2024.2325297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 02/26/2024] [Indexed: 03/02/2024] Open
Abstract
ABBREVIATION AP: autophagosome; ATG: autophagy related; CMA: chaperone-mediated autophagy; ESCRT: endosomal sorting complex required for transport; FA: fatty acid; LD: lipid droplet; Ld microdomains: liquid-disordered microdomains; NL: neutral lipid.
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Affiliation(s)
- Na Kang
- School of Biomedical Sciences, Hunan University, Changsha, Hunan, China
| | - Jinling Tan
- School of Biomedical Sciences, Hunan University, Changsha, Hunan, China
| | - Sisi Yan
- School of Biomedical Sciences, Hunan University, Changsha, Hunan, China
| | - Leiying Lin
- School of Biomedical Sciences, Hunan University, Changsha, Hunan, China
| | - Qiang Gao
- Hunan Key Laboratory of Animal Models and Molecular Medicine, School of Biomedical Sciences, Hunan University, Changsha, Hunan, China
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3
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Shen Y, Li T, Sun C, Cheng X, Chen Z, Wang G, Yang X. Atg7 autophagy-independent role on governing neural stem cell fate could be potentially applied for regenerative medicine. Cell Death Differ 2024:10.1038/s41418-024-01330-5. [PMID: 38898232 DOI: 10.1038/s41418-024-01330-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 06/11/2024] [Accepted: 06/12/2024] [Indexed: 06/21/2024] Open
Abstract
A literature review showed that Atg7 biological role was associated with the development and pathogenesis of nervous system, but very few reports focused on Atg7 role on neurogenesis at the region of spinal cord, so that we are committed to explore the subject. Atg7 expression in neural tube is incrementally increased during neurogenesis. Atg7 neural-specific knockout mice demonstrated the impaired motor function and imbalance of neuronal and glial cell differentiation during neurogenesis, which was similarly confirmed in primary neurosphere culture and reversely verified by Atg7 overexpression in unilateral neural tubes of gastrula chicken embryos. Furthermore, activating autophagy in neural stem cells (NSCs) of neurospheres did not rescue Atg7 deficiency-suppressed neuronal differentiation, but Atg7 overexpression on the basis of autophagy inhibition could reverse Atg7 deficiency-suppressed neuronal differentiation, which provides evidence for the existence of Atg7 role of autophagy-independent function. The underlying mechanism is that Atg7 deficiency directly caused the alteration of cell cycle length of NSCs, which is controlled by Atg7 through specifically binding Mdm2, thereby affecting neuronal differentiation during neurogenesis. Eventually, the effect of overexpressing Atg7-promoting neuronal differentiation was proved in spinal cord injury model as well. Taken together, this study revealed that Atg7 was involved in regulating neurogenesis by a non-autophagic signaling process, and this finding also shed light on the potential application in regenerative medicine.
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Affiliation(s)
- Yao Shen
- International Joint Laboratory for Embryonic Development & Prenatal Medicine, Division of Histology and Embryology, School of Medicine, Jinan University, Guangzhou, 510632, China
| | - Tingting Li
- International Joint Laboratory for Embryonic Development & Prenatal Medicine, Division of Histology and Embryology, School of Medicine, Jinan University, Guangzhou, 510632, China
| | - Chengyang Sun
- International Joint Laboratory for Embryonic Development & Prenatal Medicine, Division of Histology and Embryology, School of Medicine, Jinan University, Guangzhou, 510632, China
| | - Xin Cheng
- International Joint Laboratory for Embryonic Development & Prenatal Medicine, Division of Histology and Embryology, School of Medicine, Jinan University, Guangzhou, 510632, China
| | - Zhi Chen
- International Joint Laboratory for Embryonic Development & Prenatal Medicine, Division of Histology and Embryology, School of Medicine, Jinan University, Guangzhou, 510632, China
| | - Guang Wang
- International Joint Laboratory for Embryonic Development & Prenatal Medicine, Division of Histology and Embryology, School of Medicine, Jinan University, Guangzhou, 510632, China.
- Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, 510632, China.
- Guangdong-Hong Kong Metabolism & Reproduction Joint Laboratory, Guangdong Second Provincial General Hospital, School of Medicine, Jinan University, Guangzhou, 510220, China.
| | - Xuesong Yang
- International Joint Laboratory for Embryonic Development & Prenatal Medicine, Division of Histology and Embryology, School of Medicine, Jinan University, Guangzhou, 510632, China.
- Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, 510632, China.
- Clinical Research Center, Clifford Hospital, Guangzhou, 511496, China.
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Wang Y, Hu Y, Xu R, Jin X, Jiao W. Plin2 inhibits autophagy via activating AKT/mTOR pathway in non-small cell lung cancer. Exp Cell Res 2024; 435:113955. [PMID: 38301990 DOI: 10.1016/j.yexcr.2024.113955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 01/13/2024] [Accepted: 01/25/2024] [Indexed: 02/03/2024]
Abstract
Perilipin 2 (Plin2) is known to be dysregulated in several human malignancies, which facilitates cancer progression. Recent studies have found that the abnormal expression of Plin2 is associated with poor prognosis of non-small cell lung cancer (NSCLC). However, the specific role of Plin2 and its underlying mechanism remain unclear. This study revealed that Plin2 expression was low in NSCLC tissues, and its relatively higher expression indicated larger tumor size and poorer prognosis. In vitro experiments proved that Plin2 promoted NSCLC cellular proliferation and inhibited autophagy by activating the AKT/mTOR pathway. Meanwhile, treatment with the AKT phosphorylation promoter or inhibitor neutralized the influence of Plin2 depletion or over-expression on proliferation and autophagy, respectively. In vivo study showed that Plin2 stimulated subcutaneous tumorigenesis of NSCLC cells in nude mice. Collectively, this study clarified the carcinogenic role of Plin2 and its molecular mechanism in NSCLC progression, which may facilitate a targeted therapy in the future.
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Affiliation(s)
- Yawei Wang
- Department of Thoracic Surgery, The Affiliated Hospital of Qingdao University, No.16 of Jiangsu Road, Qingdao, 266000, China
| | - Ye Hu
- Department of Nephrology, Qingdao Eighth People's Hospital, No.84 of Fengshan Road, Qingdao, 266121, China
| | - Rongjian Xu
- Department of Thoracic Surgery, The Affiliated Hospital of Qingdao University, No.16 of Jiangsu Road, Qingdao, 266000, China
| | - Xiangfeng Jin
- Department of Thoracic Surgery, The Affiliated Hospital of Qingdao University, No.16 of Jiangsu Road, Qingdao, 266000, China
| | - Wenjie Jiao
- Department of Thoracic Surgery, The Affiliated Hospital of Qingdao University, No.16 of Jiangsu Road, Qingdao, 266000, China.
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Yang N, Zhang J, Guo J, Xiang Q, Huang Y, Wen J, Liu Q, Hu T, Chen Y, Rao C. Revealing the mechanism of Zanthoxylum armatum DC. extract-induced liver injury in mice based on lipidomics. JOURNAL OF ETHNOPHARMACOLOGY 2024; 319:117086. [PMID: 37634752 DOI: 10.1016/j.jep.2023.117086] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/19/2023] [Accepted: 08/23/2023] [Indexed: 08/29/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Zanthoxylum armatum DC. (Z. armatum) is an herbal medicine with various active ingredients and pharmacological effects. However, modern studies found that Z. armatum is hepatotoxic. The liver is the target organ for toxic effects and an important site for lipid metabolism. The effects of Z. armatum on lipid level and metabolism in the liver are still unclear. AIM OF THE STUDY This study aimed to analyze hepatic lipid levels, lipid metabolites and metabolic pathways of action of Z. armatum based on lipidomics, to investigate the potential hepatotoxic mechanism of Z. armatum. MATERIALS AND METHODS Different doses (62, 96, and 150 mg/kg) of the methanolic extract of Z. armatum (MZADC) were administered to ICR mice by gavage. The hepatotoxicity of MZADC was assessed by the liver index, serum biochemical measurements, and histopathological examination. Lipid levels measured by the serum lipid index were evaluated in the mice. Lipidomics was used to screen for differential lipid metabolism markers and lipid metabolism pathways in the liver. Western blot analysis was performed to investigate the effects of MZADC on the liver. RESULTS Liver index values and serum alanine transaminase and aspartate transaminase levels were increased in the MZADC group. Histopathology examination revealed hepatocyte necrosis, watery degeneration of the hepatocytes, and hepatic cord rupture in the livers of mice. Serum levels of low-density lipoprotein cholesterol, cholesterol, and triglycerides were elevated, and high-density lipoprotein cholesterol levels were decreased. Lipidomics screening for markers of differential lipid metabolism in the liver, and altered profiles of differential metabolites indicated that glycerophospholipid metabolism, linoleic acid metabolism, alpha-linolenic acid metabolism, glycosylphosphatidylinositol-anchored biosynthesis, sphingolipid metabolism and arachidonic acid metabolic pathways were significantly associated with MZADC-induced liver injury. Western blots confirmed that the protein expression of LC3, Beclin-1, ATG5, ATG12 and ATG16L1 was decreased, and p62 was increased in the MZADC group. The proportion of p-PI3K/PI3K and p-AKT/AKT was increased. CONCLUSIONS The liver injury induced by MZADC involved many different lipid metabolites and lipid metabolic pathways, which may be related to autophagy. This study provides a new perspective on the hepatotoxicity study of Z. armatum and provides a reference for the safe application of Z. armatum in the medicine and food fields.
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Affiliation(s)
- Nannan Yang
- School of Public Health, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China
| | - Jian Zhang
- School of Public Health, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China
| | - Jiafu Guo
- School of Public Health, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China
| | - Qiwen Xiang
- School of Public Health, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China
| | - Yan Huang
- Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China
| | - Jiayu Wen
- School of Public Health, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China
| | - Qiuyan Liu
- School of Public Health, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China
| | - Tingting Hu
- School of Public Health, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China
| | - Yan Chen
- School of Public Health, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China; Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China.
| | - Chaolong Rao
- School of Public Health, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China; Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China; R&D Center for Efficiency, Safety and Application in Chinese Materia Medica with Medical and Edible Values, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China.
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6
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Han Y, Yang H, Liu Z, Hu C, Lamine I, Liu Z, Gao P, Sui Y, Zheng P, Zhang H, Jia X. Tetrabromobisphenol a and its alternative tetrachlorobisphenol a induce oxidative stress, lipometabolism disturbance, and autophagy in the liver of male Pelophylax nigromaculatus. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 903:166421. [PMID: 37619733 DOI: 10.1016/j.scitotenv.2023.166421] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 07/30/2023] [Accepted: 08/17/2023] [Indexed: 08/26/2023]
Abstract
Tetrabromobisphenol A (TBBPA) and tetrachlorobisphenol A (TCBPA) have been widely used as flame retardants. However, their potential health risks to organisms have raised concerns, particularly for liver toxicity. Present study aimed to explore the toxic effects of TCBPA and TBBPA on black-spotted frogs (Pelophylax nigromaculatus) liver oxidative stress, autophagy, and lipid accumulation. After exposure to 0.001, 0.01, 0.1, and 1 mg/L TBBPA and TCBPA for 14 days, the content of cholesterol and triglyceride were significantly elevated. In addition, the malondialdehyde level rose greatly in dose dependent. However, the glutathione level declined in high TBBPA groups (0.01 and 0.1 mg/L). Furthermore, expressions of Beclin1, Atg5, and Atg7 were significantly increased, while p62 was markedly declined, respectively. Results obstained suggested that TBBPA and TCBPA exposure induced liver toxicity in black-spotted frog. This study provided insights into the toxicity mechanism of bisphenol flame retardants in amphibians and will aid in the ecological risk assessment of flame retardants.
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Affiliation(s)
- Yu Han
- Hangzhou Normal University, Hangzhou, 311121, China
| | - Hongmei Yang
- Hangzhou Normal University, Hangzhou, 311121, China
| | - Zhiqun Liu
- Hangzhou Normal University, Hangzhou, 311121, China
| | - Chao Hu
- Hangzhou Normal University, Hangzhou, 311121, China
| | - Imane Lamine
- Laboratory of Aquatic Systems, Marine and Continental Ecosystems, Department of Biology, Faculty of Sciences, Ibn Zohr University, Agadir 80000, Morocco
| | - Zhiquan Liu
- Hangzhou Normal University, Hangzhou, 311121, China
| | - Panpan Gao
- Hangzhou Normal University, Hangzhou, 311121, China
| | - Yanming Sui
- School of Marine and Biological Engineering, Yancheng Institute of Technology, Yancheng, 224002, China
| | - Pei Zheng
- Dianshan branch of Ecological Environment Bureau, Zhoushan, 316299, China
| | | | - Xiuying Jia
- Hangzhou Normal University, Hangzhou, 311121, China; Hangzhou City University, Hangzhou, 310015, China.
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Chen WF, Chi XP, Song HY, Wang HF, Wang Y, Liu ZG, Xu BH. Ame-miR-980-3p participates in autophagy-mediated midgut remodelling in Apis mellifera via targeting Atg2B. INSECT MOLECULAR BIOLOGY 2023; 32:748-760. [PMID: 37658706 DOI: 10.1111/imb.12869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 08/14/2023] [Indexed: 09/03/2023]
Abstract
Autophagy is a process that serves to degrade damaged proteins and organelles, thereby promoting cell homeostasis, differentiation, development and survival. Many miRNAs have been found to have regulatory roles in autophagy. In insects, it has been shown that autophagy is involved in hormone-regulated programmed cell death during metamorphic midgut remodelling. However, whether this is also true during the remodelling of the honey bee midgut is unclear. In the present study, we explored the relationship between autophagy and midgut remodelling and sought to identify miRNAs involved in this physiological process. We found that autophagy occurred during midgut remodelling and that the inhibition of autophagy resulted in midgut dysplasia in prepupae. Differentially expressed miRNAs enriched in the autophagy signalling pathway during midgut remodelling were identified by small RNA-seq. Ame-miR-980-3p, which targets the autophagy-related gene Atg2B, was screened out. Furthermore, abnormal expression of ame-miR-980-3p in the pupal stage led to the thinning of the midgut wall of newly emerged bees (NE). When ame-miR-980-3p expression was inhibited, the intestinal villi of NE bees became significantly shorter and sparse, and the lipid signal in the peritrophic matrix of Pb almost disappeared, indicating that the adult midgut was underdeveloped and the lipid absorption ability was weakened. Taken together, ame-miR-980-3p targeted Atg2B to participate in the regulation of midgut autophagy in the pupae, and the abnormal expression of ame-miR-980-3p would interfere with cell proliferation and death in the process of midgut remodelling, hinder the formation of adult midgut and eventually lead to adult midgut dysplasia and affect the lipid absorption function of the midgut in Apis mellifera.
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Affiliation(s)
- Wen-Feng Chen
- College of Animal Science and Technology, Shandong Agricultural University, Taian, China
| | - Xue-Peng Chi
- College of Animal Science and Technology, Shandong Agricultural University, Taian, China
| | - Hong-Yu Song
- College of Animal Science and Technology, Shandong Agricultural University, Taian, China
| | - Hong-Fang Wang
- College of Animal Science and Technology, Shandong Agricultural University, Taian, China
| | - Ying Wang
- College of Animal Science and Technology, Shandong Agricultural University, Taian, China
| | - Zhen-Guo Liu
- College of Animal Science and Technology, Shandong Agricultural University, Taian, China
| | - Bao-Hua Xu
- College of Animal Science and Technology, Shandong Agricultural University, Taian, China
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Omrane M, Ben M'Barek K, Santinho A, Nguyen N, Nag S, Melia TJ, Thiam AR. LC3B is lipidated to large lipid droplets during prolonged starvation for noncanonical autophagy. Dev Cell 2023; 58:1266-1281.e7. [PMID: 37315562 PMCID: PMC10686041 DOI: 10.1016/j.devcel.2023.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 12/23/2022] [Accepted: 05/17/2023] [Indexed: 06/16/2023]
Abstract
Lipid droplets (LDs) store lipids that can be utilized during times of scarcity via autophagic and lysosomal pathways, but how LDs and autophagosomes interact remained unclear. Here, we discovered that the E2 autophagic enzyme, ATG3, localizes to the surface of certain ultra-large LDs in differentiated murine 3T3-L1 adipocytes or Huh7 human liver cells undergoing prolonged starvation. Subsequently, ATG3 lipidates microtubule-associated protein 1 light-chain 3B (LC3B) to these LDs. In vitro, ATG3 could bind alone to purified and artificial LDs to mediate this lipidation reaction. We observed that LC3B-lipidated LDs were consistently in close proximity to collections of LC3B-membranes and were lacking Plin1. This phenotype is distinct from macrolipophagy, but it required autophagy because it disappeared following ATG5 or Beclin1 knockout. Our data suggest that extended starvation triggers a noncanonical autophagy mechanism, similar to LC3B-associated phagocytosis, in which the surface of large LDs serves as an LC3B lipidation platform for autophagic processes.
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Affiliation(s)
- Mohyeddine Omrane
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 75005 Paris, France
| | - Kalthoum Ben M'Barek
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 75005 Paris, France
| | - Alexandre Santinho
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 75005 Paris, France
| | - Nathan Nguyen
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Shanta Nag
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Thomas J Melia
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 75005 Paris, France.
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De Mazière A, van der Beek J, van Dijk S, de Heus C, Reggiori F, Koike M, Klumperman J. An optimized protocol for immuno-electron microscopy of endogenous LC3. Autophagy 2022; 18:3004-3022. [PMID: 35387562 PMCID: PMC9673964 DOI: 10.1080/15548627.2022.2056864] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
MAP1LC3/LC3 (microtubule associated protein 1 light chain 3) is widely used as marker of autophagic compartments at different stages of maturation. Electron microscopy (EM) combined with immunolabeling is the only technique that can reveal the ultrastructural identity of LC3-labeled compartments. However, immuno-EM of endogenous LC3 proteins has proven difficult. Here, we test a panel of commercially available antibodies and apply different labeling conditions to present an optimized procedure for LC3 immuno-EM. Using ultrathin cryosections and protein A-colloidal gold or gold enhancement labeling, we localize endogenous LC3 in starved cells or tissues in the presence or absence of the proton pump inhibitor bafilomycin A1. We localize LC3 to early and late stage autophagic compartments that can be classified by their morphology. By on-section correlative light-electron microscopy (CLEM) we show that comparable fluorescent LC3-positive puncta can represent different autophagic intermediates. We also show that our approach is sufficiently robust to label endogenous LC3 simultaneously with other lysosomal and autophagy markers, LAMP1 or SQSTM1/p62, and can be used for quantitative approaches. Thus, we demonstrate that bafilomycin A1 treatment from 2.5 up to 24 h does not inhibit fusion between autophagosomes and lysosomes, but leads to the accumulation of LC3-positive material inside autolysosomes. Together, this is the first study presenting an extensive overview of endogenous LC3 localization at ultrastructural resolution without the need for cell permeabilization and using a commercially available antibody. This provides researchers with a tool to study canonical and non-canonical roles of LC3 in native conditions.Abbreviations: BafA1: bafilomycin A1; BSA: bovine serum albumin; BSA-c: acetylated BSA; BSA5: BSA conjugated to 5-nm gold particles; CLEM: correlative light-electron microscopy; EGFP: enhanced green fluorescent protein; EM: electron microscopy; FBS: fetal bovine serum; FSG: fish skin gelatin; GA: glutaraldehyde; IF: immunofluorescence; LAMP1: lysosomal associated membrane protein 1; LC3s: LC3 proteins; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; ON: overnight; PAG: protein A-conjugated gold particles; PAG1-3: PAG5, PAG10, PAG15, protein A conjugated to 1-3-, 5-, 10-, or 15-nm gold particles; PB: Sorensen's phosphate buffer; PBS: phosphate-buffered saline; PFA: paraformaldehyde; RT: room temperature.
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Affiliation(s)
- Ann De Mazière
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Jan van der Beek
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Suzanne van Dijk
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Cecilia de Heus
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells & Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Masato Koike
- Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Judith Klumperman
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands,CONTACT Judith Klumperman Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
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10
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Berardi DE, Bock-Hughes A, Terry AR, Drake LE, Bozek G, Macleod KF. Lipid droplet turnover at the lysosome inhibits growth of hepatocellular carcinoma in a BNIP3-dependent manner. SCIENCE ADVANCES 2022; 8:eabo2510. [PMID: 36223464 PMCID: PMC9555787 DOI: 10.1126/sciadv.abo2510] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 08/23/2022] [Indexed: 05/12/2023]
Abstract
Hepatic steatosis is a major etiological factor in hepatocellular carcinoma (HCC), but factors causing lipid accumulation leading to HCC are not understood. We identify BNIP3 (a mitochondrial cargo receptor) as an HCC suppressor that mitigates against lipid accumulation to attenuate tumor cell growth. Targeted deletion of Bnip3 decreased tumor latency and increased tumor burden in a mouse model of HCC. This was associated with increased lipid in bnip3-/- HCC at early stages of disease, while lipid did not accumulate until later in tumorigenesis in wild-type mice, as Bnip3 expression was attenuated. Low BNIP3 expression in human HCC similarly correlated with increased lipid content and worse prognosis than HCC expressing high BNIP3. BNIP3 suppressed HCC cell growth by promoting lipid droplet turnover at the lysosome in a manner dependent on BNIP3 binding LC3. We have termed this process "mitolipophagy" because it involves the coordinated autophagic degradation of lipid droplets with mitochondria.
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Affiliation(s)
- Damian E. Berardi
- The Ben May Department for Cancer Research, The Gordon Center for Integrative Sciences, W-338, The University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA
| | - Althea Bock-Hughes
- The Ben May Department for Cancer Research, The Gordon Center for Integrative Sciences, W-338, The University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA
- The Committee on Molecular Metabolism and Nutrition, The University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA
| | - Alexander R. Terry
- The Ben May Department for Cancer Research, The Gordon Center for Integrative Sciences, W-338, The University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA
| | - Lauren E. Drake
- The Ben May Department for Cancer Research, The Gordon Center for Integrative Sciences, W-338, The University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA
| | - Grazyna Bozek
- The Ben May Department for Cancer Research, The Gordon Center for Integrative Sciences, W-338, The University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA
| | - Kay F. Macleod
- The Ben May Department for Cancer Research, The Gordon Center for Integrative Sciences, W-338, The University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA
- The Committee on Molecular Metabolism and Nutrition, The University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA
- The Committee on Cancer Biology, The University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA
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Xu C, Fan J. Links between autophagy and lipid droplet dynamics. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:2848-2858. [PMID: 35560198 DOI: 10.1093/jxb/erac003] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 01/06/2022] [Indexed: 06/15/2023]
Abstract
Autophagy is a catabolic process in which cytoplasmic components are delivered to vacuoles or lysosomes for degradation and nutrient recycling. Autophagy-mediated degradation of membrane lipids provides a source of fatty acids for the synthesis of energy-rich, storage lipid esters such as triacylglycerol (TAG). In eukaryotes, storage lipids are packaged into dynamic subcellular organelles, lipid droplets. In times of energy scarcity, lipid droplets can be degraded via autophagy in a process termed lipophagy to release fatty acids for energy production via fatty acid β-oxidation. On the other hand, emerging evidence suggests that lipid droplets are required for the efficient execution of autophagic processes. Here, we review recent advances in our understanding of metabolic interactions between autophagy and TAG storage, and discuss mechanisms of lipophagy. Free fatty acids are cytotoxic due to their detergent-like properties and their incorporation into lipid intermediates that are toxic at high levels. Thus, we also discuss how cells manage lipotoxic stresses during autophagy-mediated mobilization of fatty acids from lipid droplets and organellar membranes for energy generation.
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Affiliation(s)
- Changcheng Xu
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Jilian Fan
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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12
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Yin D, Lin D, Xie Y, Gong A, Jiang P, Wu J. Neuregulin-1β Alleviates Sepsis-Induced Skeletal Muscle Atrophy by Inhibiting Autophagy via AKT/mTOR Signaling Pathway in Rats. Shock 2022; 57:397-407. [PMID: 34559744 DOI: 10.1097/shk.0000000000001860] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Several studies have shown that excessive protein degradation is a major cause of skeletal muscle atrophy induced by sepsis, and autophagy is the main pathway participating in protein degradation. However, the role of autophagy in sepsis is still controversial. Previously, we found that neuregulin-1β (NRG-1β) alleviated sepsis-induced diaphragm atrophy through the phosphatidylinositol-3 kinase signaling pathway. Akt/mechanistic target of rapamycin (mTOR) is a classic signaling pathway to regulate autophagy, which maintains intracellular homeostasis. This study aimed to investigate whether NRG-1β could alleviate sepsis-induced skeletal muscle atrophy by regulating autophagy. METHODS L6 rat myoblast cells were differentiated using 2% fetal bovine serum into myotubes, which were divided into four groups: Con group treated with normal serum; Sep group treated with septic serum to form a sepsis cell model; septic serum + NRG-1β (SN) group treated with septic serum for 24 h followed by injection with NRG-1β and incubation for another 48 h; and serum+NRG-1β+LY294002 group, in which the PI3K inhibitor LY294002 was added 30 min before NRG-1β, and other treatments were similar to those in SN group. Effects of NRG-1β were also evaluated in vivo using Sprague-Dawley (SD) rats, in which sepsis was induced by cecal ligation and puncture (CLP). RESULTS In L6 myotubes treated with septic serum, the expression of autophagy-related proteins UNC-51 like kinase 1, p-Beclin-1, and Beclin-1, and the ratio of LC3B II/I were highly increased, while protein p62 expression was decreased, indicating that autophagy was excessively activated. Moreover, NRG-1 expression was decreased, as detected by confocal immunofluorescence and western blotting. Upon exogenous addition of NRG-1β, autophagy was inhibited by the activation of Akt/mTOR signaling pathway, and cell viability was also increased. These effects disappeared in the presence of LY294002. In SD rats, sepsis was induced by CLP. NRG-1β was shown to inhibit autophagy in these rats via the Akt/mTOR pathway, leading to increased body weight of the septic SD rats and alleviation of atrophy of the tibialis anterior muscle. CONCLUSION NRG-1β could alleviate sepsis-induced skeletal muscle atrophy by inhibiting autophagy via the AKT/mTOR signaling pathway.
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Affiliation(s)
- Dandan Yin
- Department of Anesthesiology, Affiliated Hospital of Jiangsu University, Zhenjiang City, Jiangsu Province, China
| | - Dawei Lin
- Department of Anesthesiology, Affiliated Hospital of Jiangsu University, Zhenjiang City, Jiangsu Province, China
| | - Yunbin Xie
- Department of Anesthesiology, The First People's Hospital of Changzhou, Changzhou City, Jiangsu Province, China
| | - Aihua Gong
- School of Medicine, Jiangsu University, Zhenjiang City, Jiangsu Province, China
| | - Peng Jiang
- Department of Anesthesiology, Affiliated Hospital of Jiangsu University, Zhenjiang City, Jiangsu Province, China
| | - Jin Wu
- Department of Anesthesiology, Affiliated Hospital of Jiangsu University, Zhenjiang City, Jiangsu Province, China
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13
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Fader Kaiser CM, Romano PS, Vanrell MC, Pocognoni CA, Jacob J, Caruso B, Delgui LR. Biogenesis and Breakdown of Lipid Droplets in Pathological Conditions. Front Cell Dev Biol 2022; 9:826248. [PMID: 35198567 PMCID: PMC8860030 DOI: 10.3389/fcell.2021.826248] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 12/22/2021] [Indexed: 12/17/2022] Open
Abstract
Lipid droplets (LD) have long been considered as mere fat drops; however, LD have lately been revealed to be ubiquitous, dynamic and to be present in diverse organelles in which they have a wide range of key functions. Although incompletely understood, the biogenesis of eukaryotic LD initiates with the synthesis of neutral lipids (NL) by enzymes located in the endoplasmic reticulum (ER). The accumulation of NL leads to their segregation into nanometric nuclei which then grow into lenses between the ER leaflets as they are further filled with NL. The lipid composition and interfacial tensions of both ER and the lenses modulate their shape which, together with specific ER proteins, determine the proneness of LD to bud from the ER toward the cytoplasm. The most important function of LD is the buffering of energy. But far beyond this, LD are actively integrated into physiological processes, such as lipid metabolism, control of protein homeostasis, sequestration of toxic lipid metabolic intermediates, protection from stress, and proliferation of tumours. Besides, LD may serve as platforms for pathogen replication and defense. To accomplish these functions, from biogenesis to breakdown, eukaryotic LD have developed mechanisms to travel within the cytoplasm and to establish contact with other organelles. When nutrient deprivation occurs, LD undergo breakdown (lipolysis), which begins with the LD-associated members of the perilipins family PLIN2 and PLIN3 chaperone-mediated autophagy degradation (CMA), a specific type of autophagy that selectively degrades a subset of cytosolic proteins in lysosomes. Indeed, PLINs CMA degradation is a prerequisite for further true lipolysis, which occurs via cytosolic lipases or by lysosome luminal lipases when autophagosomes engulf portions of LD and target them to lysosomes. LD play a crucial role in several pathophysiological processes. Increased accumulation of LD in non-adipose cells is commonly observed in numerous infectious diseases caused by intracellular pathogens including viral, bacterial, and parasite infections, and is gradually recognized as a prominent characteristic in a variety of cancers. This review discusses current evidence related to the modulation of LD biogenesis and breakdown caused by intracellular pathogens and cancer.
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Affiliation(s)
- Claudio M Fader Kaiser
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Patricia S Romano
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - M Cristina Vanrell
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Cristian A Pocognoni
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Julieta Jacob
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Benjamín Caruso
- Instituto de Investigaciones Biologicas y Tecnologicas, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Cordoba, Cordoba, Argentina
| | - Laura R Delgui
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
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14
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Autophagy Improves ARA-Rich TAG Accumulation in Mortierella alpina by Regulating Resource Allocation. Microbiol Spectr 2022; 10:e0130021. [PMID: 35138146 PMCID: PMC8881083 DOI: 10.1128/spectrum.01300-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The present study was designed to explore the possibility of improving lipid production in oleaginous filamentous fungus Mortierella alpina based on an autophagy regulation strategy. According to multiomics information, vacuolate-centered macroautophagy was identified as the main type of autophagy in M. alpina under nitrogen-limited conditions. Mutation of autophagy-related gene MAatg8 led to impaired fatty acid synthesis, while overexpression of both MAatg8 and phosphatidylserine decarboxylases (MApsd2) showed promoting effects on fatty acid synthesis. MAatg8 overexpression strain with external supply of ethanolamine significantly increased arachidonic acid (ARA)-rich triacylglycerol (TAG) and biomass synthesis in M. alpina, and the final fatty acid content increased by approximately 110% compared with that in the wild-type strain. Metabolomics and lipidomics analyses revealed that cell autophagy enhanced the recycling of preformed carbon, nitrogen, and lipid in mycelium, and the released carbon skeleton and energy were contributed to the accumulation of TAG in M. alpina. This study suggests that regulation of autophagy-related MAatg8-phosphatidylethanolamine (MAatg8-PE) conjugation system could be a promising strategy for attaining higher lipid production and biomass growth. The mechanism of autophagy in regulating nitrogen limitation-induced lipid accumulation elucidated in this study provides a reference for development of autophagy-based strategies for improving nutrient use efficiency and high value-added lipid production by oleaginous microorganism. IMPORTANCE Studies have indicated that functional oil accumulation occurs in oleaginous microorganisms under nitrogen limitation. However, until now, large-scale application of nitrogen-deficiency strategies was limited by low biomass. Therefore, the identification of the critical nodes of nitrogen deficiency-induced lipid accumulation is urgently needed to further guide functional oil production. The significance of our research is in uncovering the function of cell autophagy in the ARA-rich TAG accumulation of oleaginous fungus M. alpina and demonstrating the feasibility of improving lipid production based on an autophagy regulation strategy at the molecular and omics levels. Our study proves that regulation of cell autophagy through the MAatg8-PE conjugation system-related gene overexpression or exogenous supply of ethanolamine would be an efficient strategy to increase and maintain biomass productivity when high TAG content is obtained under nitrogen deficiency, which could be useful for the development of new strategies that will achieve more biomass and maximal lipid productivity.
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15
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Faghfouri AH, Khajebishak Y, Payahoo L, Faghfuri E, Alivand M. PPAR-gamma agonists: Potential modulators of autophagy in obesity. Eur J Pharmacol 2021; 912:174562. [PMID: 34655597 DOI: 10.1016/j.ejphar.2021.174562] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/21/2021] [Accepted: 10/11/2021] [Indexed: 12/15/2022]
Abstract
Autophagy pathways are involved in the pathogenesis of some obesity related health problems. As obesity is a nutrient sufficiency condition, autophagy process can be altered in obesity through AMP activated protein kinase (AMPK) inhibition. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) as the main modulator of adipogenesis process can be effective in the regulation of obesity related phenotypes. As well, it has been revealed that PPAR-gamma and its agonists can regulate autophagy in different normal or cancer cells. However, their effects on autophagy modulation in obesity have been investigated in the limited number of studies. In the current comprehensive mechanistic review, we aimed to investigate the possible mechanisms of action of PPAR-gamma on the process of autophagy in obesity through narrating the effects of PPAR-gamma on autophagy in the non-obesity conditions. Moreover, mode of action of PPAR-gamma agonists on autophagy related implications comprehensively reviewed in the various studies. Understanding the different effects of PPAR-gamma agonists on autophagy in obesity can help to develop a new approach to management of obesity.
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Affiliation(s)
- Amir Hossein Faghfouri
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Community Nutrition, Faculty of Nutrition, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Yaser Khajebishak
- Department of Nutrition, Maragheh University of Medical Sciences, Maragheh, I.R., Iran
| | - Laleh Payahoo
- Department of Nutrition, Maragheh University of Medical Sciences, Maragheh, I.R., Iran
| | - Elnaz Faghfuri
- Digestive Disease Research Center, Ardabil University of Medical Sciences, Ardabil, Iran.
| | - Mohammadreza Alivand
- Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
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16
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Zhang CJ, Zhu N, Long J, Wu HT, Wang YX, Liu BY, Liao DF, Qin L. Celastrol induces lipophagy via the LXRα/ABCA1 pathway in clear cell renal cell carcinoma. Acta Pharmacol Sin 2021; 42:1472-1485. [PMID: 33303989 PMCID: PMC8379158 DOI: 10.1038/s41401-020-00572-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 11/03/2020] [Indexed: 12/17/2022] Open
Abstract
Celastrol is a triterpene derived from the traditional Chinese medicine Tripterygium wilfordii Hook f, which displays potential anticancer activity. In the present study, we investigated the anticancer effects of celastrol against clear cell renal cell carcinoma (ccRCC) and the underlying mechanisms. Using Cancer Genome Atlas (TCGA) database and genotype-tissue expression (GTEx) database we conducted a bioinformatics analysis, which showed that the mRNA levels of liver-X receptors α (LXRα) and ATP-binding cassette transporter A1 (ABCA1) in ccRCC tissues were significantly lower than those in adjacent normal tissues. This result was confirmed by immunoblotting analysis of 4 ccRCC clinical specimens, which showed that the protein expression of LXRα and ABCA1 was downregulated. Similar results were obtained in a panel of ccRCC cell lines (786-O, A498, SN12C, and OS-RC-2). In 786-O and SN12C cells, treatment with celastrol (0.25-2.0 μM) concentration-dependently inhibited the cell proliferation, migration, and invasion as well as the epithelial-mesenchymal transition (EMT) process. Furthermore, we demonstrated that celastrol inhibited the invasion of 786-O cells through reducing lipid accumulation; celastrol concentration-dependently promoted autophagy to reduce lipid storage. Moreover, we revealed that celastrol dramatically activated LXRα signaling, and degraded lipid droplets by inducing lipophagy in 786-O cells. Finally, celastrol promoted cholesterol efflux from 786-O cells via ABCA1. In high-fat diet-promoted ccRCC cell line 786-O xenograft model, administration of celastrol (0.25, 0.5, 1.0 mg·kg-1·d-1, for 4 weeks, i.p.) dose-dependently inhibited the tumor growth with upregulated LXRα and ABCA1 protein in tumor tissue. In conclusion, this study reveals that celastrol triggers lipophagy in ccRCC by activating LXRα, promotes ABCA1-mediated cholesterol efflux, suppresses EMT progress, and ultimately inhibits cell proliferation, migration, and invasion as well as tumor growth. Thus, our study provides evidence that celastrol can be used as a lipid metabolism-based anticancer therapeutic approach.
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Affiliation(s)
- Chan-Juan Zhang
- Division of Stem Cell Regulation and Application, School of Pharmacy, Hunan University of Chinese Medicine, Changsha, 410208, China
| | - Neng Zhu
- Department of Urology, The First Hospital of Hunan University of Chinese Medicine, Changsha, 410007, China
| | - Jia Long
- Division of Stem Cell Regulation and Application, School of Pharmacy, Hunan University of Chinese Medicine, Changsha, 410208, China
| | - Hong-Tao Wu
- Department of Urology, The Second XiangYa Hospital of Central South University, Changsha, 410011, China
| | - Yu-Xiang Wang
- Division of Stem Cell Regulation and Application, School of Pharmacy, Hunan University of Chinese Medicine, Changsha, 410208, China
| | - Bi-Yuan Liu
- Department of Immunology, School of Medicine, Hunan University of Chinese Medicine, Changsha, 410208, China
| | - Duan-Fang Liao
- Division of Stem Cell Regulation and Application, School of Pharmacy, Hunan University of Chinese Medicine, Changsha, 410208, China
| | - Li Qin
- Division of Stem Cell Regulation and Application, School of Pharmacy, Hunan University of Chinese Medicine, Changsha, 410208, China.
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17
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Ramos VDM, Kowaltowski AJ, Kakimoto PA. Autophagy in Hepatic Steatosis: A Structured Review. Front Cell Dev Biol 2021; 9:657389. [PMID: 33937257 PMCID: PMC8081956 DOI: 10.3389/fcell.2021.657389] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 03/16/2021] [Indexed: 01/18/2023] Open
Abstract
Steatosis is the accumulation of neutral lipids in the cytoplasm. In the liver, it is associated with overeating and a sedentary lifestyle, but may also be a result of xenobiotic toxicity and genetics. Non-alcoholic fatty liver disease (NAFLD) defines an array of liver conditions varying from simple steatosis to inflammation and fibrosis. Over the last years, autophagic processes have been shown to be directly associated with the development and progression of these conditions. However, the precise role of autophagy in steatosis development is still unclear. Specifically, autophagy is necessary for the regulation of basic metabolism in hepatocytes, such as glycogenolysis and gluconeogenesis, response to insulin and glucagon signaling, and cellular responses to free amino acid contents. Also, genetic knockout models for autophagy-related proteins suggest a critical relationship between autophagy and hepatic lipid metabolism, but some results are still ambiguous. While autophagy may seem necessary to support lipid oxidation in some contexts, other evidence suggests that autophagic activity can lead to lipid accumulation instead. This structured literature review aims to critically discuss, compare, and organize results over the last 10 years regarding rodent steatosis models that measured several autophagy markers, with genetic and pharmacological interventions that may help elucidate the molecular mechanisms involved.
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Affiliation(s)
| | | | - Pamela A. Kakimoto
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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18
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Zhang A, Meng Y, Li Q, Liang Y. The endosomal sorting complex required for transport complex negatively regulates Erg6 degradation under specific glucose restriction conditions. Traffic 2021; 21:488-502. [PMID: 32378292 DOI: 10.1111/tra.12732] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 12/20/2022]
Abstract
Lipid droplets (LDs) are cytosolic fat storage organelles that play roles in lipid metabolism, trafficking and signaling. Breakdown of LDs in Saccharomyces cerevisiae is mainly achieved by lipolysis and lipophagy. In this study, we found that the endosomal sorting complex required for transport (ESCRT) in S. cerevisiae negatively regulated the turnover of a LD marker, Erg6, under both simplified glucose restriction (GR) and acute glucose restriction (AGR) conditions by monitoring the localization and degradation of Erg6. Loss of Vps27, Snf7 or Vps4, representative subunits of the ESCRT machinery, facilitated the delivery of Erg6-GFP to vacuoles and its degradation depending on the lipophagy protein Atg15 under simplified GR. Additionally, the lipolysis proteins Tgl3 and Tgl4 were also involved in the enhanced vacuolar localization and degradation of Erg6-GFP in vps4Δ cells. Furthermore, we found that Atg14, which is required for the formation of putatively liquid-ordered (Lo) membrane domains on the vacuole that act as preferential internalization sites for LDs, abundantly localized to vacuolar membranes in ESCRT mutants. Most importantly, the depletion or overexpression of Atg14 correspondingly abolished or promoted the observed Erg6 degradation in ESCRT mutant cells. We propose that Atg14 together with other proteins promotes Erg6 degradation in ESCRT mutant cells under specific glucose restriction conditions. These results shed new light on the regulation of ESCRT on LD turnover.
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Affiliation(s)
- Ao Zhang
- College of Life Sciences, Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture and Rural Affairs, Nanjing Agricultural University, Nanjing, China
| | - Ying Meng
- College of Life Sciences, Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture and Rural Affairs, Nanjing Agricultural University, Nanjing, China
| | - Qunli Li
- College of Life Sciences, Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture and Rural Affairs, Nanjing Agricultural University, Nanjing, China
| | - Yongheng Liang
- College of Life Sciences, Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture and Rural Affairs, Nanjing Agricultural University, Nanjing, China
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19
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Liu Z, Liu M, Fan M, Pan S, Li S, Chen M, Wang H. Metabolomic-proteomic combination analysis reveals the targets and molecular pathways associated with hydrogen sulfide alleviating NAFLD. Life Sci 2020; 264:118629. [PMID: 33131747 DOI: 10.1016/j.lfs.2020.118629] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 10/10/2020] [Accepted: 10/17/2020] [Indexed: 01/03/2023]
Abstract
AIMS Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease worldwide. Exogenous H2S has been shown to effectively mitigate NAFLD, although little is known about the underlying targets and molecular mechanisms. METHODS C57BL/6 mice were fed with normal fat diet (NFD) or high fat diet (HFD) for a total 16 weeks, and HFD-fed mice were treated with saline or NaHS beginning in 12th week. The combination analysis of metabolomics and proteomics of liver tissues was firstly performed to discover the candidate targets and potential molecular pathways involved in H2S mitigating the NAFLD. KEY FINDINGS Compared with NaCl, H2S relieved NAFLD by reducing liver weight, body weight and lipid accumulation in liver, and improving liver pathology and serum biochemical parameters. There were 40 overlapping metabolites in the intersection analysis between comparative analysis of HFD + NaCl vs NFD and HFD + NaHS vs HFD + NaCl based on liver metabolomics. Moreover, a total of 58 proteins were obtained whose changes were reversed after treatment with H2S. A combined analysis of liver metabolomics and proteomics was then conducted, revealing 8 shared molecular pathways, as well as the enrichment of unsaturated fatty acids. In addition, Plin2 may also be a potential target of H2S via the regulation of lipid droplet degradation in alleviating NAFLD. SIGNIFICANCE We performed the first study combining metabolomics and proteomics to explore the mechanisms behind the alleviation of NAFLD by H2S. Our results not only provide evidence that H2S alleviates NAFLD but also reveals its possible molecular mechanisms and targets.
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Affiliation(s)
- Zhangnan Liu
- Joint National Laboratory for Antibody Drug Engineering, Key Laboratory of Cellular and Molecular Immunology of Henan Province, Institute of Translational Medicine, School of Basic Medicine, Henan University, Kaifeng 475004, China
| | - Meichen Liu
- Joint National Laboratory for Antibody Drug Engineering, Key Laboratory of Cellular and Molecular Immunology of Henan Province, Institute of Translational Medicine, School of Basic Medicine, Henan University, Kaifeng 475004, China
| | - Ming Fan
- Joint National Laboratory for Antibody Drug Engineering, Key Laboratory of Cellular and Molecular Immunology of Henan Province, Institute of Translational Medicine, School of Basic Medicine, Henan University, Kaifeng 475004, China
| | - Sijing Pan
- Joint National Laboratory for Antibody Drug Engineering, Key Laboratory of Cellular and Molecular Immunology of Henan Province, Institute of Translational Medicine, School of Basic Medicine, Henan University, Kaifeng 475004, China
| | - Shaowei Li
- Joint National Laboratory for Antibody Drug Engineering, Key Laboratory of Cellular and Molecular Immunology of Henan Province, Institute of Translational Medicine, School of Basic Medicine, Henan University, Kaifeng 475004, China
| | - Mingliang Chen
- School of Basic Medicine, Henan University, Kaifeng 475004, China.
| | - Huijuan Wang
- Joint National Laboratory for Antibody Drug Engineering, Key Laboratory of Cellular and Molecular Immunology of Henan Province, Institute of Translational Medicine, School of Basic Medicine, Henan University, Kaifeng 475004, China.
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20
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Kaludercic N, Maiuri MC, Kaushik S, Fernández ÁF, de Bruijn J, Castoldi F, Chen Y, Ito J, Mukai R, Murakawa T, Nah J, Pietrocola F, Saito T, Sebti S, Semenzato M, Tsansizi L, Sciarretta S, Madrigal-Matute J. Comprehensive autophagy evaluation in cardiac disease models. Cardiovasc Res 2020; 116:483-504. [PMID: 31504266 PMCID: PMC7064050 DOI: 10.1093/cvr/cvz233] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 08/01/2019] [Accepted: 08/22/2019] [Indexed: 12/24/2022] Open
Abstract
Autophagy is a highly conserved recycling mechanism essential for maintaining cellular homeostasis. The pathophysiological role of autophagy has been explored since its discovery 50 years ago, but interest in autophagy has grown exponentially over the last years. Many researchers around the globe have found that autophagy is a critical pathway involved in the pathogenesis of cardiac diseases. Several groups have created novel and powerful tools for gaining deeper insights into the role of autophagy in the aetiology and development of pathologies affecting the heart. Here, we discuss how established and emerging methods to study autophagy can be used to unravel the precise function of this central recycling mechanism in the cardiac system.
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Affiliation(s)
- Nina Kaludercic
- Neuroscience Institute, Department of Biomedical Sciences, National Research Council of Italy (CNR), 35131, Padova, Italy
| | - Maria Chiara Maiuri
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Descartes, Université Paris Diderot, 75006, Paris, France
| | - Susmita Kaushik
- Department of Developmental and Molecular Biology, Institute for Aging Studies, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Álvaro F Fernández
- Center for Autophagy Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Jenny de Bruijn
- Department of Pathology, Cardiovascular Research Institute (CARIM), Maastricht University, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands; Institute of Molecular Cardiovascular Research (IMCAR), RWTH Aachen, University, Pauwelsstrase 30, 52074, Aachen, Germany
| | - Francesca Castoldi
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Descartes, Université Paris Diderot, 75006, Paris, France
| | - Yun Chen
- Departments of Medicine (Cardiology) and Cell Biology, Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Jumpei Ito
- The School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, London SE5 9NU, UK
| | - Risa Mukai
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, Newark, NY, USA
| | - Tomokazu Murakawa
- The School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, London SE5 9NU, UK
| | - Jihoon Nah
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, Newark, NY, USA
| | - Federico Pietrocola
- Cellular Plasticity and Disease Laboratory. Institute for Research in Biomedicine (IRB Barcelona), Barcelona; Institute of Science and Technology (BIST), Barcelona, Spain
| | - Toshiro Saito
- Department of Surgery and Clinical Science, Graduate School of Medicine, Yamaguchi University, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
| | - Salwa Sebti
- Center for Autophagy Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Martina Semenzato
- Department of Biology, University of Padua, Via U Bassi 58B, 35121, Padua, Italy.,Venetian Institute of Molecular Medicine, Via Orus 2, 35129, Padua, Italy
| | - Lorenza Tsansizi
- Department of Biology, University of Padua, Via U Bassi 58B, 35121, Padua, Italy.,Venetian Institute of Molecular Medicine, Via Orus 2, 35129, Padua, Italy
| | - Sebastiano Sciarretta
- Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, 04100, Latina, LT, Italy.,Department of AngioCardioNeurology, IRCCS Neuromed, 86077, Pozzilli, IS, Italy
| | - Julio Madrigal-Matute
- Department of Developmental and Molecular Biology, Institute for Aging Studies, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
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Zhang X, Wu D, Wang C, Luo Y, Ding X, Yang X, Silva F, Arenas S, Weaver JM, Mandell M, Deretic V, Liu M. Sustained activation of autophagy suppresses adipocyte maturation via a lipolysis-dependent mechanism. Autophagy 2020; 16:1668-1682. [PMID: 31840569 PMCID: PMC8386625 DOI: 10.1080/15548627.2019.1703355] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Dysregulation of macroautophagy/autophagy is implicated in obesity and insulin resistance. However, it remains poorly defined how autophagy regulates adipocyte development. Using adipose-specific rptor/raptor knockout (KO), atg7 KO and atg7 rptor double-KO mice, we show that inhibiting MTORC1 by RPTOR deficiency led to autophagic sequestration of lipid droplets, formation of LD-containing lysosomes, and elevation of basal and isoproterenol-induced lipolysis in vivo and in primary adipocytes. Despite normal differentiation at an early phase, progressive degradation and shrinkage of cellular LDs and downregulation of adipogenic markers PPARG and PLIN1 occurred in terminal differentiation of rptor KO adipocytes, which was rescued by inhibiting lipolysis or lysosome. In contrast, inactivating autophagy by depletion of ATG7 protected adipocytes against RPTOR deficiency-induced formation of LD-containing lysosomes, LD degradation, and downregulation of adipogenic markers in vitro. Ultimately, atg7 rptor double-KO mice displayed decreased lipolysis, restored adipose tissue development, and upregulated thermogenic gene expression in brown and inguinal adipose tissue compared to RPTOR-deficient mice in vivo. Collectively, our study demonstrates that autophagy plays an important role in regulating adipocyte maturation via a lipophagy and lipolysis-dependent mechanism. ABBREVIATIONS ATG7: autophagy related 7; BAT: brown adipose tissue; CEBPB/C/EBPβ: CCAAT enhancer binding protein beta; DGAT1: diacylglycerol O-acyltransferase 1; eWAT: epididymal white adipose tissue; iWAT: inguinal white adipose tissue; KO: knockout; LD: lipid droplet; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; MTORC1: mechanistic target of rapamycin kinase complex 1; PLIN1: perepilin 1; PNPLA2/ATGL: patatin-like phospholipase domain containing 2; PPARG/PPARγ: peroxisome proliferator activated receptor gamma; RPTOR: regulatory associated protein of MTOR complex1; TG: triglyceride; ULK1: unc-51 like kinase 1; UCP1: uncoupling protein 1; WAT: white adipose tissue.
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Affiliation(s)
- Xing Zhang
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Dandan Wu
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Chunqing Wang
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Yan Luo
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Xiaofeng Ding
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Xin Yang
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Floyd Silva
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Sara Arenas
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - John Michael Weaver
- Autophagy Inflammation and Metabolism Center for Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Michael Mandell
- Autophagy Inflammation and Metabolism Center for Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Vojo Deretic
- Autophagy Inflammation and Metabolism Center for Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Meilian Liu
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA,CONTACT Meilian Liu Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, USA
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22
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Kim HS, Ren G, Kim T, Bhatnagar S, Yang Q, Bahk YY, Kim JA. Metformin reduces saturated fatty acid-induced lipid accumulation and inflammatory response by restoration of autophagic flux in endothelial cells. Sci Rep 2020; 10:13523. [PMID: 32782332 PMCID: PMC7419289 DOI: 10.1038/s41598-020-70347-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 07/03/2020] [Indexed: 02/06/2023] Open
Abstract
Autophagy, an integral part of the waste recycling process, plays an important role in cellular physiology and pathophysiology. Impaired autophagic flux causes ectopic lipid deposition, which is defined as the accumulation of lipids in non-adipose tissue. Ectopic lipid accumulation is observed in patients with cardiometabolic syndrome, including obesity, diabetes, insulin resistance, and cardiovascular complications. Metformin is the first line of treatment for type 2 diabetes, and one of the underlying mechanisms for the anti-diabetic effect of metformin is mediated by the stimulation of AMP-activated protein kinase (AMPK). Because the activation of AMPK is crucial for the initiation of autophagy, we hypothesize that metformin reduces the accumulation of lipid droplets by increasing autophagic flux in vascular endothelial cells. Incubation of vascular endothelial cells with saturated fatty acid (SFA) increased the accumulation of lipid droplets and impaired autophagic flux. We observed that the accumulation of lipid droplets was reduced, and the autophagic flux was enhanced by treatment with metformin. The knock-down of AMPKα by using siRNA blunted the effect of metformin. Furthermore, treatment with SFA or inhibition of autophagy increased leukocyte adhesion, whereas treatment with metformin decreased the SFA-induced leukocyte adhesion. The results suggest a novel mechanism by which metformin protects vascular endothelium from SFA-induced ectopic lipid accumulation and pro-inflammatory responses. In conclusion, improving autophagic flux may be a therapeutic strategy to protect endothelial function from dyslipidemia and diabetic complications.
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Affiliation(s)
- Hae-Suk Kim
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, Comprehensive Diabetes Center, University of Alabama at Birmingham, 1825 University Blvd, Birmingham, AL, 35294, USA
| | - Guang Ren
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, Comprehensive Diabetes Center, University of Alabama at Birmingham, 1825 University Blvd, Birmingham, AL, 35294, USA
| | - Teayoun Kim
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, Comprehensive Diabetes Center, University of Alabama at Birmingham, 1825 University Blvd, Birmingham, AL, 35294, USA
| | - Sushant Bhatnagar
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, Comprehensive Diabetes Center, University of Alabama at Birmingham, 1825 University Blvd, Birmingham, AL, 35294, USA
| | - Qinglin Yang
- Department of Nutrition, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Young Yil Bahk
- Department of Biotechnology, College of Biomedical and Health Science, Konkuk University, Chungju, 27478, Republic of Korea
| | - Jeong-A Kim
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, Comprehensive Diabetes Center, University of Alabama at Birmingham, 1825 University Blvd, Birmingham, AL, 35294, USA.
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23
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Multifarious roles of lipid droplets in autophagy - Target, product, and what else? Semin Cell Dev Biol 2020; 108:47-54. [PMID: 32169402 DOI: 10.1016/j.semcdb.2020.02.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/12/2020] [Accepted: 02/29/2020] [Indexed: 01/09/2023]
Abstract
Lipid droplets (LDs) are not an inert storage of excessive lipids, but play various roles in cellular lipid metabolism. Autophagy involves several mechanisms for the degradation of cellular components, and is related to many aspects of lipid metabolism. LD and autophagic membranes often distribute in proximity, but their relationship is complex. LDs can be degraded by autophagy, but LDs are also generated as a result of autophagy or support the execution of autophagy. Moreover, several proteins crucial for autophagy were shown to affect different aspects of LD formation. This article aims to categorize this multifaceted and seemingly entangled LD-autophagy relationship and to discuss unresolved issues.
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24
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Joshi V, Upadhyay A, Prajapati VK, Mishra A. How autophagy can restore proteostasis defects in multiple diseases? Med Res Rev 2020; 40:1385-1439. [PMID: 32043639 DOI: 10.1002/med.21662] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 01/03/2020] [Accepted: 01/28/2020] [Indexed: 12/12/2022]
Abstract
Cellular evolution develops several conserved mechanisms by which cells can tolerate various difficult conditions and overall maintain homeostasis. Autophagy is a well-developed and evolutionarily conserved mechanism of catabolism, which endorses the degradation of foreign and endogenous materials via autolysosome. To decrease the burden of the ubiquitin-proteasome system (UPS), autophagy also promotes the selective degradation of proteins in a tightly regulated way to improve the physiological balance of cellular proteostasis that may get perturbed due to the accumulation of misfolded proteins. However, the diverse as well as selective clearance of unwanted materials and regulations of several cellular mechanisms via autophagy is still a critical mystery. Also, the failure of autophagy causes an increase in the accumulation of harmful protein aggregates that may lead to neurodegeneration. Therefore, it is necessary to address this multifactorial threat for in-depth research and develop more effective therapeutic strategies against lethal autophagy alterations. In this paper, we discuss the most relevant and recent reports on autophagy modulations and their impact on neurodegeneration and other complex disorders. We have summarized various pharmacological findings linked with the induction and suppression of autophagy mechanism and their promising preclinical and clinical applications to provide therapeutic solutions against neurodegeneration. The conclusion, key questions, and future prospectives sections summarize fundamental challenges and their possible feasible solutions linked with autophagy mechanism to potentially design an impactful therapeutic niche to treat neurodegenerative diseases and imperfect aging.
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Affiliation(s)
- Vibhuti Joshi
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Karwar, India
| | - Arun Upadhyay
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Karwar, India
| | - Vijay K Prajapati
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Ajmer, India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Karwar, India
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25
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Przygodda F, Lautherbach N, Buzelle SL, Goncalves DA, Assis AP, Paula-Gomes S, Garófalo MAR, Heck LC, Matsuo FS, Mota RF, Osako MK, Kettelhut IC, Navegantes LC. Sympathetic innervation suppresses the autophagic-lysosomal system in brown adipose tissue under basal and cold-stimulated conditions. J Appl Physiol (1985) 2020; 128:855-871. [PMID: 32027543 DOI: 10.1152/japplphysiol.00065.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The sympathetic nervous system (SNS) activates cAMP signaling and promotes trophic effects on brown adipose tissue (BAT) through poorly understood mechanisms. Because norepinephrine has been found to induce antiproteolytic effects on muscle and heart, we hypothesized that the SNS could inhibit autophagy in interscapular BAT (IBAT). Here, we describe that selective sympathetic denervation of rat IBAT kept at 25°C induced atrophy, and in parallel dephosphorylated forkhead box class O (FoxO), and increased cathepsin activity, autophagic flux, autophagosome formation, and expression of autophagy-related genes. Conversely, cold stimulus (4°C) for up to 72 h induced thermogenesis and IBAT hypertrophy, an anabolic effect that was associated with inhibition of cathepsin activity, autophagic flux, and autophagosome formation. These effects were abrogated by sympathetic denervation, which also upregulated Gabarapl1 mRNA. In addition, the cold-driven sympathetic activation stimulated the mechanistic target of rapamycin (mTOR) pathway, leading to the enhancement of protein synthesis, evaluated in vivo by puromycin incorporation, and to the inhibitory phosphorylation of Unc51-like kinase-1, a key protein in the initiation of autophagy. This coincided with a higher content of exchange protein-1 directly activated by cAMP (Epac1), a cAMP effector, and phosphorylation of Akt at Thr308, all these effects being abolished by denervation. Systemic treatment with norepinephrine for 72 h mimicked most of the cold effects on IBAT. These data suggest that the noradrenergic sympathetic inputs to IBAT restrain basal autophagy via suppression of FoxO and, in the setting of cold, stimulate protein synthesis via the Epac/Akt/mTOR-dependent pathway and suppress the autophagosome formation, probably through posttranscriptional mechanisms.NEW & NOTEWORTHY The underlying mechanisms related to the anabolic role of sympathetic innervation on brown adipose tissue (BAT) are unclear. We show that sympathetic denervation activates autophagic-lysosomal degradation, leading to a loss of mitochondrial proteins and BAT atrophy. Conversely, cold-driven sympathetic activation suppresses autophagy and stimulates protein synthesis, leading to BAT hypertrophy. Given its high-potential capacity for heat production, understanding the mechanisms that contribute to BAT mass is important to optimize chances of survival for endotherms in cold ambients.
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Affiliation(s)
- Franciele Przygodda
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Natalia Lautherbach
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Samyra Lopes Buzelle
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Dawit Albieiro Goncalves
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.,Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Ana Paula Assis
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Sílvia Paula-Gomes
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | | | - Lilian Carmo Heck
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Flávia Sayuri Matsuo
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Ryerson Fonseca Mota
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Mariana Kiomy Osako
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Isis C Kettelhut
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Luiz C Navegantes
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
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26
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Wang H, Xu GB, Hernández-Saavedra D, Chen H, Pan YX. A Low Protein Diet during Gestation and Lactation Increases Hepatic Lipid Accumulation through Autophagy and Histone Deacetylase. Am J Physiol Endocrinol Metab 2020; 319:E11-E25. [PMID: 31910026 DOI: 10.1152/ajpendo.00263.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study examined the mechanism of a low protein (LP) diet on hepatic lipid metabolism during gestation and lactation. Timed-pregnant Sprague-Dawley rats were fed a control or an LP diet during gestation and lactation. LP dams had increased hepatic triglyceride accumulation and significantly higher aspartate/alanine transaminase ratio, accompanied by a decrease in circulating very low-density/low-density lipoprotein ratio. LC3B (Microtubule Associated Protein 1 Light Chain 3 Beta) expression was stimulated in LP dams along with increased histone acetylation. LP diet-induced co-localization of the LC3 binding motif-interacting proteins APOB or MTTP with LC3B, suggesting autophagic degradation. HDAC3 is found necessary to prevent lipid accumulation in response to amino acid deprivation in HepG2 cells. LC3B-mediated APOB protein degradation is related to increases in lipid accumulation. Conclusion: HDAC3 regulated LC3B-induced lipid accumulation potentially through autophagic degradation of APOB and MTTP in response to amino acid limitation caused by a low protein diet.
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Affiliation(s)
- Huan Wang
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Guanying Bianca Xu
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Diego Hernández-Saavedra
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Hong Chen
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL USA; Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL
| | - Yuan-Xiang Pan
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL USA; Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL USA; Illinois Informatics Institute, University of Illinois at Urbana-Champaign, Urbana, IL
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27
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Takahashi SS, Sou YS, Saito T, Kuma A, Yabe T, Sugiura Y, Lee HC, Suematsu M, Yokomizo T, Koike M, Terai S, Mizushima N, Waguri S, Komatsu M. Loss of autophagy impairs physiological steatosis by accumulation of NCoR1. Life Sci Alliance 2020; 3:e201900513. [PMID: 31879337 PMCID: PMC6932742 DOI: 10.26508/lsa.201900513] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 12/18/2019] [Accepted: 12/18/2019] [Indexed: 02/02/2023] Open
Abstract
Lipid droplets (LDs) are dynamic organelles that store neutral lipids during times of energy excess, such as after a meal. LDs serve as an energy reservoir during fasting and have a buffering capacity that prevents lipotoxicity. Autophagy and the autophagic machinery have been proposed to play a role in LD biogenesis, but the underlying molecular mechanism remains unclear. Here, we show that when nuclear receptor co-repressor 1 (NCoR1), which inhibits the transactivation of nuclear receptors, accumulates because of autophagy suppression, LDs decrease in size and number. Ablation of ATG7, a gene essential for autophagy, suppressed the expression of gene targets of liver X receptor α, a nuclear receptor responsible for fatty acid and triglyceride synthesis in an NCoR1-dependent manner. LD accumulation in response to fasting and after hepatectomy was hampered by the suppression of autophagy. These results suggest that autophagy controls physiological hepatosteatosis by fine-tuning NCoR1 protein levels.
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Affiliation(s)
- Shun-Saku Takahashi
- Division of Gastroenterology and Hepatology, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata, Japan
| | - Yu-Shin Sou
- Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Tetsuya Saito
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Akiko Kuma
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, the University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takayuki Yabe
- Department of Anatomy and Histology, Fukushima Medical University School of Medicine, Hikarigaoka, Fukushima, Japan
| | - Yuki Sugiura
- Department of Biochemistry, Keio University School of Medicine, Tokyo, Japan
| | - Hyeon-Cheol Lee
- Department of Biochemistry, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Makoto Suematsu
- Department of Biochemistry, Keio University School of Medicine, Tokyo, Japan
| | - Takehiko Yokomizo
- Department of Biochemistry, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Masato Koike
- Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Shuji Terai
- Division of Gastroenterology and Hepatology, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata, Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, the University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Satoshi Waguri
- Department of Anatomy and Histology, Fukushima Medical University School of Medicine, Hikarigaoka, Fukushima, Japan
| | - Masaaki Komatsu
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
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28
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Jarc E, Petan T. Lipid Droplets and the Management of Cellular Stress. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2019; 92:435-452. [PMID: 31543707 PMCID: PMC6747940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Lipid droplets are cytosolic fat storage organelles present in most eukaryotic cells. Long regarded merely as inert fat reservoirs, they are now emerging as major regulators of cellular metabolism. They act as hubs that coordinate the pathways of lipid uptake, distribution, storage, and use in the cell. Recent studies have revealed that they are also essential components of the cellular stress response. One of the hallmark characteristics of lipid droplets is their capacity to buffer excess lipids and to finely tune their subsequent release based on specific cellular requirements. This simple feature of lipid droplet biology, buffering and delayed release of lipids, forms the basis for their pleiotropic roles in the cellular stress response. In stressed cells, lipid droplets maintain energy and redox homeostasis and protect against lipotoxicity by sequestering toxic lipids into their neutral lipid core. Their mobility and dynamic interactions with mitochondria enable an efficient delivery of fatty acids for optimal energy production. Lipid droplets are also involved in the maintenance of membrane and organelle homeostasis by regulating membrane composition, preventing lipid peroxidation and removing damaged proteins and lipids. Finally, they also engage in a symbiotic relationship with autophagy and act as reservoirs of bioactive lipids that regulate inflammation and immunity. Thus, lipid droplets are central managers of lipid metabolism that function as safeguards against various types of cellular stress.
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Affiliation(s)
- Eva Jarc
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana, Slovenia,Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Toni Petan
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana, Slovenia,To whom all correspondence should be addressed: Toni Petan, Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia; Tel: +386 1 477 3713, Fax: +386 1 477 3984,
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29
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Autophagy differentially regulates macrophage lipid handling depending on the lipid substrate (oleic acid vs. acetylated-LDL) and inflammatory activation state. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:158527. [PMID: 31520777 DOI: 10.1016/j.bbalip.2019.158527] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 09/01/2019] [Accepted: 09/08/2019] [Indexed: 12/17/2022]
Abstract
The regulation of lipid droplet (LD) dynamics by autophagy in naïve macrophages is complex: Inhibiting autophagosome initiation steps attenuates oleic acid (OA) induced LD (OA-LD) biogenesis, whereas interfering with later-autophagosome maturation/lysosomal steps accelerates OA-LD biogenesis rate, but not OA-LD degradation. Here we hypothesized that regulation of macrophage lipid handling by autophagy may be lipid-substrate and activation-state-specific. Using automated quantitative live-cell imaging, initial LD biogenesis rate was ~30% slower when the lipid source was acetylated low density lipoprotein (acLDL) compared to OA. Yet, both were similarly affected by triacsin-C, an inhibitor of acyl-CoA synthase, which inhibited, and etomoxir, an inhibitor of acylcarnitine palmitoyl transferase (fatty acid oxidation), which augmented, LD biogenesis rates. An autophagy inducing peptide, Tat-Beclin1, enhanced the degradation, and inhibited (by 37%) the biogenesis of acLDL induced LD (acLDL-LD). Yet, Tat-Beclin1 increased OA-LD biogenesis rate by 70%. When macrophages were pre-activated with LPS + INFG they exhibited increased autophagosome number and area, and reduced BECN1 and ATG14 protein levels, which associated with a markedly attenuated autophagic flux. Concomitantly, OA-LD and acLDL-LD biogenesis rates increased 3 and 7.4-fold, respectively, but could not be further modulated by Tat-Beclin1, as observed in non-activated/naïve macrophages. We propose that macrophage autophagy, and/or components of its machinery, differentially regulate LD/foam-cell biogenesis depending on the lipid-source, and that inflammatory activation uncouples autophagy from LD biogenesis.
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30
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Lee DH, Ahn J, Jang YJ, Ha TY, Jung CH. Oleic acid-induced defective autolysosome shows impaired lipid degradation. Biochem Biophys Res Commun 2019; 513:553-559. [DOI: 10.1016/j.bbrc.2019.04.040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 04/04/2019] [Indexed: 12/24/2022]
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31
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Joshi AS, Cohen S. Lipid Droplet and Peroxisome Biogenesis: Do They Go Hand-in-Hand? Front Cell Dev Biol 2019; 7:92. [PMID: 31214588 PMCID: PMC6554619 DOI: 10.3389/fcell.2019.00092] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/14/2019] [Indexed: 01/19/2023] Open
Abstract
All eukaryotic cells contain membrane bound structures called organelles. Each organelle has specific composition and function. Some of the organelles are generated de novo in a cell. The endoplasmic reticulum (ER) is a major contributor of proteins and membranes for most of the organelles. In this mini review, we discuss de novo biogenesis of two such organelles, peroxisomes and lipid droplets (LDs), that are formed in the ER membrane. LDs and peroxisomes are highly conserved ubiquitously present membrane-bound organelles. Both these organelles play vital roles in lipid metabolism and human health. Here, we discuss the current understanding of de novo biogenesis of LDs and peroxisomes, recent advances on how biogenesis of both the organelles might be linked, physical interaction between LDs and peroxisomes and other organelles, and their physiological importance.
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Affiliation(s)
- Amit S. Joshi
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Sarah Cohen
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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32
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Saito T, Kuma A, Sugiura Y, Ichimura Y, Obata M, Kitamura H, Okuda S, Lee HC, Ikeda K, Kanegae Y, Saito I, Auwerx J, Motohashi H, Suematsu M, Soga T, Yokomizo T, Waguri S, Mizushima N, Komatsu M. Autophagy regulates lipid metabolism through selective turnover of NCoR1. Nat Commun 2019; 10:1567. [PMID: 30952864 PMCID: PMC6450892 DOI: 10.1038/s41467-019-08829-3] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Accepted: 01/29/2019] [Indexed: 01/11/2023] Open
Abstract
Selective autophagy ensures the removal of specific soluble proteins, protein aggregates, damaged mitochondria, and invasive bacteria from cells. Defective autophagy has been directly linked to metabolic disorders. However how selective autophagy regulates metabolism remains largely uncharacterized. Here we show that a deficiency in selective autophagy is associated with suppression of lipid oxidation. Hepatic loss of Atg7 or Atg5 significantly impairs the production of ketone bodies upon fasting, due to decreased expression of enzymes involved in β-oxidation following suppression of transactivation by PPARα. Mechanistically, nuclear receptor co-repressor 1 (NCoR1), which interacts with PPARα to suppress its transactivation, binds to the autophagosomal GABARAP family proteins and is degraded by autophagy. Consequently, loss of autophagy causes accumulation of NCoR1, suppressing PPARα activity and resulting in impaired lipid oxidation. These results suggest that autophagy contributes to PPARα activation upon fasting by promoting degradation of NCoR1 and thus regulates β-oxidation and ketone bodies production. Defective autophagy has been associated with metabolic disorders. Here Saito et al. show that autophagy promotes the selective degradation of NCoR1, a repressor of lipid metabolism regulator PPARα, in response to starvation, and thus induces the expression of enzymes involved in lipid oxidation and the production of ketone bodies.
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Affiliation(s)
- Tetsuya Saito
- Department of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata, 951-8510, Japan
| | - Akiko Kuma
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Department of Genetics, Graduate School of Medicine, Osaka University, Suita, Osaka, 565-0871, Japan.,Japan Science and Technology Agency, PRESTO, Saitama, 332-0012, Japan
| | - Yuki Sugiura
- Japan Science and Technology Agency, PRESTO, Saitama, 332-0012, Japan.,Department of Biochemistry, Keio University School of Medicine, Tokyo, 160-8582, Japan
| | - Yoshinobu Ichimura
- Department of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata, 951-8510, Japan
| | - Miki Obata
- Department of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata, 951-8510, Japan
| | - Hiroshi Kitamura
- Department of Gene Expression Regulation, Institute of Development, Aging and Cancer, Tohoku University, Sendai, 980-8575, Japan
| | - Shujiro Okuda
- Bioinformatics Laboratory, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata, 951-8510, Japan
| | - Hyeon-Cheol Lee
- Department of Biochemistry, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Kazutaka Ikeda
- Laboratory for Metabolomics, RIKEN Center for Integrative Medical Sciences (IMS), Yokohama, Kanagawa, 230-0045, Japan
| | - Yumi Kanegae
- Core Research Facilities of Basic Science (Molecular Genetics), Research Center for Medical Science, Jikei University School of Medicine, Tokyo, 105-8461, Japan
| | - Izumu Saito
- Laboratory of Molecular Genetics, Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan.,Laboratory of Virology, Institute of Microbial Chemistry, Shinagawa-ku, Tokyo, 141-0021, Japan
| | - Johan Auwerx
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Hozumi Motohashi
- Department of Gene Expression Regulation, Institute of Development, Aging and Cancer, Tohoku University, Sendai, 980-8575, Japan
| | - Makoto Suematsu
- Department of Biochemistry, Keio University School of Medicine, Tokyo, 160-8582, Japan
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0052, Japan
| | - Takehiko Yokomizo
- Department of Biochemistry, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Satoshi Waguri
- Department of Anatomy and Histology, Fukushima Medical University School of Medicine, Hikarigaoka, Fukushima, 960-1295, Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masaaki Komatsu
- Department of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata, 951-8510, Japan. .,Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, 113-8421, Japan.
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Yan R, Niu CY, Tian Y. Roles of Autophagy and Protein Kinase C-epsilon in Lipid Metabolism of Nonalcoholic Fatty Liver Cell Models. Arch Med Res 2018; 49:381-390. [PMID: 30573200 DOI: 10.1016/j.arcmed.2018.11.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 10/16/2018] [Accepted: 11/23/2018] [Indexed: 01/30/2023]
Abstract
OBJECTIVE To investigate interaction between autophagy and PKC-ε in lipid metabolism of NAFLD cell models. METHODS HL-7702 cells and SK-HEP-1 cells were cultured in vitro as NAFLD cell models and treated with RAPA to induce autophagy. 3-MA was used to inhibit cell autophagy. And HL-7702 and SK-HEP-1 cell were ordinary cultured as control groups. Cell viability was determined by MTT colorimetric assay. The levels of TG, TC and PKC-ε were detected by ELISA. PKC-ε was detected by IF. LC3-II/LC3-I, P62, IRS-1, IRS-2, PI3Kp85, mTOR were detected by Western-blot. SPSS 20 software was used for statistical analysis. RESULTS The values of PKC-ε were the highest in the steatosis groups (HL-7702 cells were 91.10%, SK-HEP-1 cells were 98.20%). Compared with the steatosis groups, the LC3-II/LC3-I ratio in the induced autophagy groups increased obviously (p <0.05). P62/β-actin grayscale ratio of the induced autophagy groups decreased significantly compared with the steatosis group (p <0.05). MTOR/β-actin grayscale ratio in the induced autophagy groups were significantly lower than those in the steatosis groups (p <0.05). PI3Kp85, IRS-1 and IRS-2/β-actin grayscale ratio of the induced autophagy groups increased significantly compared with the steatosis group (p <0.05). CONCLUSION Up-regulation of autophagy can promote the elimination of liver fat; while down-regulation can promote lipid accumulation. The expression of PKC-ε is positively related to the degree of hepatic steatosis. PI3K was involved in both autophagy and IR induced by PKC-ε. PKC-ε might participate in hepatocyte autophagy by regulating PI3K.
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Affiliation(s)
- Rong Yan
- Department of Gastroenterology, First Affiliated Hospital of Xi'an Medical University, Xi'an, Shaanxi Province, China.
| | - Chun-Yan Niu
- Department of Gastroenterology, Xiang'an Hospital of Xiamen University, Xiamen, Fujian Province, China
| | - Yu Tian
- Clinical Laboratory, First Affiliated Hospital of Xi'an Medical University, Xi'an, Shaanxi Province, China
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Zhang L, Yao Z, Ji G. Herbal Extracts and Natural Products in Alleviating Non-alcoholic Fatty Liver Disease via Activating Autophagy. Front Pharmacol 2018; 9:1459. [PMID: 30618753 PMCID: PMC6297257 DOI: 10.3389/fphar.2018.01459] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 11/29/2018] [Indexed: 12/14/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease world-wide, and currently therapeutic options for NAFLD are limited. Herbal medicine (HM) may offer an attractive alternative for the treatment of NAFLD. Recent years have witnessed a growing interest in the autophagy-inducing agents, and autophagy activation has been recognized as an efficient strategy in managing NAFLD and related complications. Pharmacological studies have demonstrated certain potential of HM extracts and natural products in inducing autophagy, which might contribute to the efficacy of HM in preventing and treating NAFLD. This review aims to summarize current understanding of mechanisms of HM extracts and natural products in preventing and treating NAFLD. Specially, we focused on mechanisms by which autophagy can target the main pathogenesis events associated with NAFLD, including hepatic steatosis, inflammation, oxidative stress, and apoptosis. It is hoped that this brief review can provide a general understanding of HM extracts and natural products in treating NAFLD, and raise awareness of potential clinical application of HM in general.
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Affiliation(s)
- Li Zhang
- Institute of Digestive Diseases, China-Canada Center of Research for Digestive Diseases, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Zemin Yao
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada
| | - Guang Ji
- Institute of Digestive Diseases, China-Canada Center of Research for Digestive Diseases, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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Ke PY. The Multifaceted Roles of Autophagy in Flavivirus-Host Interactions. Int J Mol Sci 2018; 19:ijms19123940. [PMID: 30544615 PMCID: PMC6321027 DOI: 10.3390/ijms19123940] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 12/05/2018] [Accepted: 12/05/2018] [Indexed: 02/06/2023] Open
Abstract
Autophagy is an evolutionarily conserved cellular process in which intracellular components are eliminated via lysosomal degradation to supply nutrients for organelle biogenesis and metabolic homeostasis. Flavivirus infections underlie multiple human diseases and thus exert an immense burden on public health worldwide. Mounting evidence indicates that host autophagy is subverted to modulate the life cycles of flaviviruses, such as hepatitis C virus, dengue virus, Japanese encephalitis virus, West Nile virus and Zika virus. The diverse interplay between autophagy and flavivirus infection not only regulates viral growth in host cells but also counteracts host stress responses induced by viral infection. In this review, we summarize the current knowledge on the role of autophagy in the flavivirus life cycle. We also discuss the impacts of virus-induced autophagy on the pathogeneses of flavivirus-associated diseases and the potential use of autophagy as a therapeutic target for curing flavivirus infections and related human diseases.
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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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36
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Niture S, Gyamfi MA, Kedir H, Arthur E, Ressom H, Deep G, Kumar D. Serotonin induced hepatic steatosis is associated with modulation of autophagy and notch signaling pathway. Cell Commun Signal 2018; 16:78. [PMID: 30409162 PMCID: PMC6225666 DOI: 10.1186/s12964-018-0282-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 10/09/2018] [Indexed: 01/08/2023] Open
Abstract
Background Besides its neurotransmitter and vasoconstriction functions, serotonin is an important mediator of numerous biological processes in peripheral tissues including cell proliferation, steatosis, and fibrogenesis. Recent reports indicate that serotonin may promote tumor growth in liver cancer, however, the molecular mechanisms remain elusive. n this study, we investigated the role and molecular signaling mechanisms mediated by serotonin in liver cancer cell survival, drug resistance, and steatosis. Methods Effect of serotonin on modulation of cell survival/proliferation was determined by MTT/WST1 assay. Effect of serotonin on the regulation of autophagy biomarkers and lipid/fatty acid proteins expression, AKT/mTOR and Notch signaling was evaluated by immunoblotting. The role of serotonin in normal human hepatocytes and liver cancer cell steatosis was analyzed by Oil Red O staining. The mRNA expression levels of lipid/fatty acid proteins and serotonin receptors were validated by qRT-PCR. The important roles of autophagy, Notch signaling, serotonin receptors and serotonin re-uptake proteins on serotonin-mediated cell steatosis were investigated by using selective inhibitors or antagonists. The association of peripheral serotonin, autophagy, and hepatic steatosis was also investigated using chronic EtOH fed mouse model. Results Exposure of liver cancer cells to serotonin induced Notch signaling and autophagy, independent of AKT/mTOR pathway. Also, serotonin enhanced cancer cell proliferation/survival and drug resistance. Furthermore, serotonin treatment up-regulated the expression of lipogenic proteins and increased steatosis in liver cancer cells. Inhibition of autophagy or Notch signaling reduced serotonin-mediated cell steatosis. Treatment with serotonin receptor antagonists 5-HTr1B and 5-HTr2B reduced serotonin-mediated cell steatosis; in contrast, treatment with selective serotonin reuptake inhibitors (SSRIs) increased steatosis. In addition, mice fed with chronic EtOH resulted in increased serum serotonin levels which were associated with the induction of hepatic steatosis and autophagy. Conclusions Serotonin regulates liver cancer cell steatosis, cells survival, and may promote liver carcinogenesis by activation of Notch signaling and autophagy. Electronic supplementary material The online version of this article (10.1186/s12964-018-0282-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Suryakant Niture
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University Durham, 1801 Fayetteville St, Durham, NC, 27707, USA
| | - Maxwell A Gyamfi
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University Durham, 1801 Fayetteville St, Durham, NC, 27707, USA
| | - Habib Kedir
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University Durham, 1801 Fayetteville St, Durham, NC, 27707, USA
| | - Elena Arthur
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University Durham, 1801 Fayetteville St, Durham, NC, 27707, USA
| | - Habtom Ressom
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20008, USA
| | - Gagan Deep
- Wake Forest Baptist Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, NC, 27109, USA
| | - Deepak Kumar
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University Durham, 1801 Fayetteville St, Durham, NC, 27707, USA. .,Department of Pharmaceutical Sciences, North Carolina Central University, Durham, NC, 27707, USA. .,Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20008, USA.
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37
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Petan T, Jarc E, Jusović M. Lipid Droplets in Cancer: Guardians of Fat in a Stressful World. Molecules 2018; 23:molecules23081941. [PMID: 30081476 PMCID: PMC6222695 DOI: 10.3390/molecules23081941] [Citation(s) in RCA: 217] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 07/31/2018] [Accepted: 08/01/2018] [Indexed: 12/12/2022] Open
Abstract
Cancer cells possess remarkable abilities to adapt to adverse environmental conditions. Their survival during severe nutrient and oxidative stress depends on their capacity to acquire extracellular lipids and the plasticity of their mechanisms for intracellular lipid synthesis, mobilisation, and recycling. Lipid droplets, cytosolic fat storage organelles present in most cells from yeast to men, are emerging as major regulators of lipid metabolism, trafficking, and signalling in various cells and tissues exposed to stress. Their biogenesis is induced by nutrient and oxidative stress and they accumulate in various cancers. Lipid droplets act as switches that coordinate lipid trafficking and consumption for different purposes in the cell, such as energy production, protection against oxidative stress or membrane biogenesis during rapid cell growth. They sequester toxic lipids, such as fatty acids, cholesterol and ceramides, thereby preventing lipotoxic cell damage and engage in a complex relationship with autophagy. Here, we focus on the emerging mechanisms of stress-induced lipid droplet biogenesis; their roles during nutrient, lipotoxic, and oxidative stress; and the relationship between lipid droplets and autophagy. The recently discovered principles of lipid droplet biology can improve our understanding of the mechanisms that govern cancer cell adaptability and resilience to stress.
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Affiliation(s)
- Toni Petan
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana SI-1000, Slovenia.
| | - Eva Jarc
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana SI-1000, Slovenia.
- Jožef Stefan International Postgraduate School, Ljubljana SI-1000, Slovenia.
| | - Maida Jusović
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana SI-1000, Slovenia.
- Jožef Stefan International Postgraduate School, Ljubljana SI-1000, Slovenia.
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38
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Yu ZK, Yang B, Zhang Y, Li LS, Zhao JN, Hao W. Modified Huangqi Chifeng decoction inhibits excessive autophagy to protect against Doxorubicin-induced nephrotic syndrome in rats via the PI3K/mTOR signaling pathway. Exp Ther Med 2018; 16:2490-2498. [PMID: 30210600 PMCID: PMC6122515 DOI: 10.3892/etm.2018.6492] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Accepted: 06/15/2018] [Indexed: 12/12/2022] Open
Abstract
The aim of the present study was to investigate whether modified Huangqi Chifeng decoction (MHCD) could be an effective treatment against Doxorubicin-induced nephrosis in rats and whether it regulates autophagy via the phosphoinositide-3 kinase/mammalian target of rapamycin (PI3K/mTOR) signaling pathway. A total of 40 male Sprague-Dawley rats were randomly divided into blank, model, telmisartan and MHCD groups. The rat model of nephrosis was induced by intragastric administration of Doxorubicin for 8 weeks. Rats were housed in metabolic cages and urine was collected once every 2 weeks to measure 24-h protein levels. Blood samples were obtained from the abdominal aorta and levels of albumin (ALB), total cholesterol (TCH), triacylglyceride (TG) and serum creatinine (Scr) were assessed. Renal pathological changes were examined using hematoxylin-eosin, Masson's trichome and periodic acid-Schiff staining. Podocytes and autophagosomes were observed using an electron microscope. The expression and distribution of microtubule-associated proteins 1A/1B light chain 3B (LC3), LC3-I, LC3-II, beclin-1, PI3K and mTOR were determined using immunohistochemistry and western blotting. At weeks 6 and 8, 24-h proteinuria significantly decreased in the MHCD group compared with the model group (P<0.05). Compared with the model group, the MHCD group exhibited significantly reduced levels of TG, TCH and Scr, as well as significantly increased ALB levels (P<0.05). MHCD was demonstrated to prevent glomerular and podocyte injury. The number of autophagosomes was significantly decreased and the expression of beclin-1, LC3, LC3-I and LC3-II was inhibited following MHCD treatment compared with the model group (P<0.05). MHCD treatment significantly increased the expression of PI3K and mTOR in Doxorubicin nephrotic rats compared with the model group (P<0.05). In conclusion, MHCD was demonstrated to ameliorate proteinuria and protect against glomerular and podocyte injury by inhibiting excessive autophagy via the PI3K/mTOR signaling pathway.
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Affiliation(s)
- Zi-Kai Yu
- Department of Nephropathy, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, P.R. China
| | - Bin Yang
- Department of Pathology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, P.R. China
| | - Yu Zhang
- Department of Nephropathy, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, P.R. China
| | - Liu-Sheng Li
- Department of Nephropathy, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, P.R. China
| | - Jin-Ning Zhao
- Experimental Research Center, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, P.R. China
| | - Wei Hao
- Experimental Research Center, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, P.R. China
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Abstract
PURPOSE OF REVIEW Intracellular lipid metabolism is a complex interplay of exogenous lipid handling, trafficking, storage, lipolysis, and export. Recent work has implicated the cellular degradative process called autophagy in several aspects of lipid metabolism. We will discuss both the classical and novel roles of autophagy and the autophagic machinery in this setting. RECENT FINDINGS The delivery of lipid droplets to lysosomes for hydrolysis, named lipophagy, was the first described functional role for autophagy in lipid metabolism. The molecular machinery and regulation of this selective form of macroautophagy is beginning to be discovered and has the potential to shed enormous light on intracellular lipolysis. Yet, the autophagic machinery appears to also be coopted for alternative roles that include interaction with cytosolic lipolysis pathways, supply and expansion of lipid droplets, and lipoprotein trafficking. Additionally, lesser studied forms of autophagy called microautophagy and chaperone-mediated autophagy have distinct roles in lipid handling that also intersect with classical macroautophagy. The integration of current knowledge in these areas into a holistic understanding of intracellular lipid metabolism will be a goal of this review. SUMMARY As the field of autophagy has evolved and expanded to include functional roles in various aspects of cellular degradation, so has its role in intracellular lipid metabolism. Understanding the mechanisms underlying these classical and alternative roles of autophagy will not only enhance our knowledge in lipid biology but also provide new avenues of translation to human lipid disorders.
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Affiliation(s)
- Xiangyu Zhang
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- John Cochran VA Medical Center, St. Louis, Missouri, USA
| | - Trent D. Evans
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Se-Jin Jeong
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- John Cochran VA Medical Center, St. Louis, Missouri, USA
| | - Babak Razani
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
- John Cochran VA Medical Center, St. Louis, Missouri, USA
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40
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Gao F, Su Q, Yang W, Pang S, Wang S, Cui Y, Zhang J, Yan B. Functional variants in the LC3B gene promoter in acute myocardial infarction. J Cell Biochem 2018; 119:7339-7349. [PMID: 29761913 DOI: 10.1002/jcb.27035] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 04/05/2018] [Indexed: 11/07/2022]
Abstract
Acute myocardial infarction (AMI) is a common disease mainly caused by atherosclerosis, for which genetic causes remain largely unknown. Recently, low frequency and rare genetic variants have been proposed as risk factors. Autophagy has been involved in many cellular processes, such as lipid metabolism and inflammation, and implicated in human diseases, including cardiovascular diseases. In previous studies, we have reported reduced levels of LC3B, a core protein and a marker for autophagy, in AMI patients. In this study, the LC3B gene promoter was genetically and functionally analyzed in large cohorts of AMI patients (n = 383) and healthy controls (n = 390). A total of 25 DNA sequence variants (DSVs) including SNPs were found. Seven DSVs and three SNPs were only identified in AMI patients. All the DSVs and SNPs (except one) significantly decreased the transcriptional activity of the LC3B gene promoter in both HEK-293 and H9c2 cells (P < 0.05). Further electrophoretic mobility shift assay suggested that the DSVs affected the binding of transcription factors. In contrast, the DSVs and SNPs found only in controls or in both AMI patients and controls did not significantly affected LC3B gene promoter activity (P > 0.05). Therefore, our data suggested that the DSVs identified in AMI patients may change LC3B level by affecting the transcriptional activity of LC3B gene promoter, contributing to the AMI development. Upregulation of the LC3B gene expression may provide a novel and potential therapy for AMI patients.
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Affiliation(s)
- Feng Gao
- Department of Medicine, Shandong University School of Medicine, Jinan, Shandong, China
| | - Qiang Su
- Department of Medicine, Shandong University School of Medicine, Jinan, Shandong, China
| | - Wentao Yang
- Department of Medicine, Shandong University School of Medicine, Jinan, Shandong, China
| | - Shuchao Pang
- Shandong Provincial Key Laboratory of Cardiac Disease Diagnosis and Treatment, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong, China
| | - Shuai Wang
- Department of Medicine, Shandong University School of Medicine, Jinan, Shandong, China
| | - Yinghua Cui
- Division of Cardiology, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong, China.,The Center for Molecular Genetics of Cardiovascular Diseases, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong, China
| | - Jinguo Zhang
- Division of Cardiology, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong, China.,The Center for Molecular Genetics of Cardiovascular Diseases, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong, China
| | - Bo Yan
- Shandong Provincial Key Laboratory of Cardiac Disease Diagnosis and Treatment, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong, China.,The Center for Molecular Genetics of Cardiovascular Diseases, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong, China.,Shandong Provincial Sino-US Cooperation Research Center for Translational Medicine, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong, China
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Coradetti ST, Pinel D, Geiselman GM, Ito M, Mondo SJ, Reilly MC, Cheng YF, Bauer S, Grigoriev IV, Gladden JM, Simmons BA, Brem RB, Arkin AP, Skerker JM. Functional genomics of lipid metabolism in the oleaginous yeast Rhodosporidium toruloides. eLife 2018. [PMID: 29521624 PMCID: PMC5922974 DOI: 10.7554/elife.32110] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The basidiomycete yeast Rhodosporidium toruloides (also known as Rhodotorula toruloides) accumulates high concentrations of lipids and carotenoids from diverse carbon sources. It has great potential as a model for the cellular biology of lipid droplets and for sustainable chemical production. We developed a method for high-throughput genetics (RB-TDNAseq), using sequence-barcoded Agrobacterium tumefaciens T-DNA insertions. We identified 1,337 putative essential genes with low T-DNA insertion rates. We functionally profiled genes required for fatty acid catabolism and lipid accumulation, validating results with 35 targeted deletion strains. We identified a high-confidence set of 150 genes affecting lipid accumulation, including genes with predicted function in signaling cascades, gene expression, protein modification and vesicular trafficking, autophagy, amino acid synthesis and tRNA modification, and genes of unknown function. These results greatly advance our understanding of lipid metabolism in this oleaginous species and demonstrate a general approach for barcoded mutagenesis that should enable functional genomics in diverse fungi. The fungus Rhodosporidium toruloides can grow on substances extracted from plant matter that is inedible to humans such as corn stalks, wood pulp, and grasses. Under some growth conditions, the fungus can accumulate massive stores of hydrocarbon-rich fats and pigments. A community of scientists and engineers has begun genetically modifying R. toruloides to convert these naturally produced fats and pigments into fuels, chemicals and medicines. These could form sustainable replacements for products made from petroleum or harvested from threatened animal and plant species. Fungi, plants, animals and other eukaryotes store fat in specialized compartments called lipid droplets. The genes that control the metabolism – the production, use and storage – of fat in lipid bodies have been studied in certain eukaryotes, including species of yeast. However, R. toruloides is only distantly related to the most well-studied of these species. This means that we cannot be certain that a gene will play the same role in R. toruloides as in those species. To assemble the most comprehensive list possible of the genes in R. toruloides that affect the production, use, or storage of fat in lipid bodies, Coradetti, Pinel et al. constructed a population of hundreds of thousands of mutant fungal strains, each with its own unique DNA ‘barcode’. The effects that mutations in over 6,000 genes had on growth and fat accumulation in these fungi were measured simultaneously in several experiments. This general approach is not new, but technical limitations had, until now, restricted its use in fungi to a few species. Coradetti, Pinel et al. identified hundreds of genes that affected the ability of R. toruloides to metabolise fat. Many of these genes were related to genes with known roles in fat metabolism in other eukaryotes. Other genes are involved in different cell processes, such as the recycling of waste products in the cell. Their identification adds weight to the view that the links between these cellular processes and fat metabolism are deep and widespread amongst eukaryotes. Finally, some of the genes identified by Coradetti, Pinel et al. are not closely related to any well-studied genes. Further study of these genes could help us to understand why R. toruloides can accumulate much larger amounts of fat than most other fungi. The methods developed by Coradetti, Pinel et al. should be possible to implement in many species of fungi. As a result these techniques may eventually contribute to the development of new treatments for human fungal diseases, the protection of important food crops, and a deeper understanding of the roles various fungi play in the broader ecosystem.
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Affiliation(s)
| | - Dominic Pinel
- Energy Biosciences Institute, Berkeley, United States
| | | | - Masakazu Ito
- Energy Biosciences Institute, Berkeley, United States
| | - Stephen J Mondo
- United States Department of Energy Joint Genome Institute, Walnut Creek, United States
| | - Morgann C Reilly
- Joint BioEnergy Institute, Emeryville, United States.,Chemical and Biological Processes Development Group, Pacific Northwest National Laboratory, Richland, United States
| | - Ya-Fang Cheng
- Energy Biosciences Institute, Berkeley, United States
| | - Stefan Bauer
- Energy Biosciences Institute, Berkeley, United States
| | - Igor V Grigoriev
- United States Department of Energy Joint Genome Institute, Walnut Creek, United States.,Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, United States
| | | | - Blake A Simmons
- Joint BioEnergy Institute, Emeryville, United States.,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Rachel B Brem
- The Buck Institute for Research on Aging, Novato, United States.,Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States
| | - Adam P Arkin
- Energy Biosciences Institute, Berkeley, United States.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, United States.,Department of Bioengineering, University of California, Berkeley, Berkeley, United States
| | - Jeffrey M Skerker
- Energy Biosciences Institute, Berkeley, United States.,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, United States.,Department of Bioengineering, University of California, Berkeley, Berkeley, United States
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42
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Hints on ATGL implications in cancer: beyond bioenergetic clues. Cell Death Dis 2018; 9:316. [PMID: 29472527 PMCID: PMC5833653 DOI: 10.1038/s41419-018-0345-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/22/2018] [Accepted: 01/23/2018] [Indexed: 12/21/2022]
Abstract
Among metabolic rearrangements occurring in cancer cells, lipid metabolism alteration has become a hallmark, aimed at sustaining accelerated proliferation. In particular, fatty acids (FAs) are dramatically required by cancer cells as signalling molecules and membrane building blocks, beyond bioenergetics. Along with de novo biosynthesis, free FAs derive from dietary sources or from intracellular lipid droplets, which represent the storage of triacylglycerols (TAGs). Adipose triglyceride lipase (ATGL) is the rate-limiting enzyme of lipolysis, catalysing the first step of intracellular TAGs hydrolysis in several tissues. However, the roles of ATGL in cancer are still neglected though a putative tumour suppressor function of ATGL has been envisaged, as its expression is frequently reduced in different human cancers (e.g., lung, muscle, and pancreas). In this review, we will introduce lipid metabolism focusing on ATGL functions and regulation in normal cell physiology providing also speculative perspectives on potential non-energetic functions of ATGL in cancer. In particular, we will discuss how ATGL is implicated, mainly through the peroxisome proliferator-activated receptor-α (PPAR-α) signalling, in inflammation, redox homoeostasis and autophagy, which are well-known processes deregulated during cancer formation and/or progression.
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43
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Abstract
Long considered inert fat storage depots, it has become clear that lipid droplets (LDs) are bona fide organelles. Like other organelles, they have a characteristic complement of proteins and lipids, and undergo a life cycle that includes biogenesis, maturation, interactions with other organelles, and turnover. I will discuss recent insights into mechanisms governing the life cycle of LDs, and compare and contrast the LD life cycle with that of other metabolic organelles such as mitochondria, peroxisomes, and autophagosomes, highlighting open questions in the field.
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Affiliation(s)
- Sarah Cohen
- University of North Carolina, Chapel Hill, NC, United States.
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44
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Zhang Y, Meng F, Sun X, Sun X, Hu M, Cui P, Vestin E, Li X, Li W, Wu XK, Jansson JO, Shao LR, Billig H. Hyperandrogenism and insulin resistance contribute to hepatic steatosis and inflammation in female rat liver. Oncotarget 2018; 9:18180-18197. [PMID: 29719598 PMCID: PMC5915065 DOI: 10.18632/oncotarget.24477] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/25/2018] [Indexed: 02/06/2023] Open
Abstract
Women with polycystic ovary syndrome (PCOS) are at high risk for nonalcoholic fatty liver disease (NAFLD). While insulin resistance is a common trait for both PCOS and NAFLD, hyperandrogenism is also considered to be a key factor contributing to PCOS, and the molecular mechanisms behind the interactions between insulin resistance and hyperandrogenism in the female liver remain largely unexplored. Using chronic treatment with insulin and/or human chorionic gonadotropin (hCG), we showed that all female rats with different treatments induced imbalance between de novo lipogenesis and mitochondrial β-oxidation via the Pparα/β–Srebp1/2–Acc1 axis, resulting in varying degrees of hepatic steatosis. Given the fact that hepatic lipid metabolism and inflammation are tightly linked processes, we found that hCG-induced hyperandrogenic rats had strongly aggravated hepatic inflammation. Further mechanistic investigations revealed that dysregulation of the IRS–PI3K–Akt signaling axis that integrated aberrant inflammatory, apoptotic and autophagic responses in the liver was strongly associated with hyperandrogenism itself or combined with insulin resistance. Additionally, we found that hCG-treated and insulin+hCG-induced rats developed visceral adipose tissue inflammation characterized by the presence of “crown like” structure and increased inflammatory gene expression. Because a more pronounced hepatic steatosis, inflammatory responses, and hepatocyte cell damage were observed in insulin+hCG-induced PCOS-like rats, our finding suggest that NAFLD seen in PCOS patients is dependent of hyperandrogenism and insulin resistance.
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Affiliation(s)
- Yuehui Zhang
- Department of Obstetrics and Gynecology, Key Laboratory and Unit of Infertility in Chinese Medicine, First Affiliated Hospital, Heilongjiang University of Chinese Medicine, 150040 Harbin, China.,Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Fanci Meng
- Department of Obstetrics and Gynecology, Key Laboratory and Unit of Infertility in Chinese Medicine, First Affiliated Hospital, Heilongjiang University of Chinese Medicine, 150040 Harbin, China
| | - Xiaoyan Sun
- Department of Obstetrics and Gynecology, Key Laboratory and Unit of Infertility in Chinese Medicine, First Affiliated Hospital, Heilongjiang University of Chinese Medicine, 150040 Harbin, China
| | - Xue Sun
- Department of Obstetrics and Gynecology, Key Laboratory and Unit of Infertility in Chinese Medicine, First Affiliated Hospital, Heilongjiang University of Chinese Medicine, 150040 Harbin, China
| | - Min Hu
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Peng Cui
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden.,Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Shanghai Medical College and Institute of Acupuncture Research (WHO Collaborating Center for Traditional Medicine), Institute of Brain Science, Fudan University, 200032 Shanghai, China.,Institute of Integrative Medicine of Fudan University, 200032 Shanghai, China
| | - Edvin Vestin
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Xin Li
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden.,Department of Gynecology, Obstetrics and Gynecology Hospital of Fudan University, 200011 Shanghai, China.,Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, 200011 Shanghai, China
| | - Wei Li
- Department of Obstetrics and Gynecology, Key Laboratory and Unit of Infertility in Chinese Medicine, First Affiliated Hospital, Heilongjiang University of Chinese Medicine, 150040 Harbin, China
| | - Xiao-Ke Wu
- Department of Obstetrics and Gynecology, Key Laboratory and Unit of Infertility in Chinese Medicine, First Affiliated Hospital, Heilongjiang University of Chinese Medicine, 150040 Harbin, China
| | - John-Olov Jansson
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Linus R Shao
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Håkan Billig
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
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45
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Wang S, Wang K, Wang H, Han J, Sun H. Autophagy is essential for flavopiridol‑induced cytotoxicity against MCF‑7 breast cancer cells. Mol Med Rep 2017; 16:9715-9720. [PMID: 29039550 DOI: 10.3892/mmr.2017.7815] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Accepted: 09/11/2017] [Indexed: 12/09/2022] Open
Abstract
Flavopiridol (FP) exerts antitumoral effects by triggering tumor cell cycle arrest and cytotoxicity in human breast cancer cell lines. The potent antitumor activity of FP is through its inhibition of cyclin‑dependent kinases; however, this may not be the only mechanism of action. The present study aimed to investigate whether FP is able to induce autophagy and to examine the effects of autophagy on cell death in FP‑treated MCF‑7 human breast cancer cells. MCF‑7 cells were treated with either FP alone or FP in combination with chloroquine (CQ). Expression levels of autophagy‑related protein LC3B‑II and p62/sequestosome 1 (SQSTM1) were used to monitor autophagic flux. MCF‑7 cells were transfected with autophagy‑related 5 (ATG5) small interfering (si)RNA to block autophagy. Cell viability and cell cycle status were determined. Following incubation with FP, MCF‑7 cells exhibited significantly higher autophagy compared with untreated control cells, and the level of autophagy is comparable with cells under rapamycin induction, which was verified by immunodetection of LC3B‑II and p62/SQSTM1 expression and inhibition by CQ. The addition of CQ treatment or ATG5‑siRNA transfection against autophagy components attenuated the cytotoxic effects of FP treatment of MCF‑7 cells. Furthermore, this autophagy inhibition did not impair the FP‑induced cell cycle arrest. These results revealed that autophagy may be involved in FP‑induced MCF‑7 cell death and autophagy inhibition enhanced the tumor cell pro‑survival ability. It is possibly that potential autophagy regulatory drugs may be used as a chemotherapy adjuvant.
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Affiliation(s)
- Shuo Wang
- Nephrology Department, Central Hospital of Zibo, Zibo, Shandong 255036, P.R. China
| | - Kai Wang
- Nuclear Medicine Department, Central Hospital of Zibo, Zibo, Shandong 255036, P.R. China
| | - Huaiquan Wang
- Nuclear Medicine Department, Central Hospital of Zibo, Zibo, Shandong 255036, P.R. China
| | - Jiankui Han
- Nuclear Medicine Department, Qilu Hospital, Jinan, Shandong 250012, P.R. China
| | - Hukui Sun
- Nuclear Medicine Department, Central Hospital of Zibo, Zibo, Shandong 255036, P.R. China
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46
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Adipose tissue conditioned media support macrophage lipid-droplet biogenesis by interfering with autophagic flux. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1001-1012. [DOI: 10.1016/j.bbalip.2017.06.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 06/04/2017] [Accepted: 06/19/2017] [Indexed: 01/20/2023]
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47
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Zechner R, Madeo F, Kratky D. Cytosolic lipolysis and lipophagy: two sides of the same coin. Nat Rev Mol Cell Biol 2017; 18:671-684. [DOI: 10.1038/nrm.2017.76] [Citation(s) in RCA: 258] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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48
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Martinet W, Roth L, De Meyer GRY. Standard Immunohistochemical Assays to Assess Autophagy in Mammalian Tissue. Cells 2017; 6:E17. [PMID: 28665306 PMCID: PMC5617963 DOI: 10.3390/cells6030017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 06/20/2017] [Accepted: 06/26/2017] [Indexed: 12/31/2022] Open
Abstract
Autophagy is a highly conserved lysosomal degradation pathway with major impact on diverse human pathologies. Despite the development of different methodologies to detect autophagy both in vitro and in vivo, monitoring autophagy in tissue via immunohistochemical techniques is hampered due to the lack of biomarkers. Immunohistochemical detection of a punctate pattern of ATG8/MAP1LC3 proteins is currently the most frequently used approach to detect autophagy in situ, but it depends on a highly sensitive detection method and is prone to misinterpretation. Moreover, reliable MAP1LC3 immunohistochemical staining requires correct tissue processing and high-quality, isoform-specific antibodies. Immunohistochemical analysis of other autophagy-related protein targets such as SQSTM1, ubiquitin, ATG5 or lysosomal proteins is not recommended as marker for autophagic activity in tissue for multiple reasons including aspecific labeling of cellular structures and a lack of differential protein expression during autophagy initiation. To better understand the role of autophagy in human disease, novel biomarkers for visualization of the autophagic process with standard histology techniques are urgently needed.
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Affiliation(s)
- Wim Martinet
- Laboratory of Physiopharmacology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
| | - Lynn Roth
- Laboratory of Physiopharmacology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
| | - Guido R Y De Meyer
- Laboratory of Physiopharmacology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
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49
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Tsai TH, Chen E, Li L, Saha P, Lee HJ, Huang LS, Shelness GS, Chan L, Chang BHJ. The constitutive lipid droplet protein PLIN2 regulates autophagy in liver. Autophagy 2017; 13:1130-1144. [PMID: 28548876 DOI: 10.1080/15548627.2017.1319544] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Excess triglyceride (TG) accumulation in the liver underlies fatty liver disease, a highly prevalent ailment. TG occurs in the liver sequestered in lipid droplets, the major lipid storage organelle. Lipid droplets are home to the lipid droplet proteins, the most abundant of which are the perilipins (PLINs), encoded by 5 different genes, Plin1 to Plin5. Of the corresponding gene products, PLIN2 is the only constitutive and ubiquitously expressed lipid droplet protein that has been used as a protein marker for lipid droplets. We and others reported that plin2-/- mice have an ∼60% reduction in TG content, and are protected against fatty liver disease. Here we show that PLIN2 overexpression protects lipid droplets against macroautophagy/autophagy, whereas PLIN2 deficiency enhances autophagy and depletes hepatic TG. The enhanced autophagy in plin2-/- mice protects against severe ER stress-induced hepatosteatosis and hepatocyte apoptosis. In contrast, hepatic TG depletion resulting from other genetic and pharmacological manipulations has no effect on autophagy. Importantly, PLIN2 deficiency lowers cellular TG content in wild-type mouse embryonic fibroblasts (MEFs) via enhanced autophagy, but does not affect cellular TG content in atg7-/- MEFs that are devoid of autophagic function. Conversely, adenovirus-shAtg7-mediated hepatic Atg7 knockdown per se does not alter the hepatic TG level, suggesting a more complex regulation in vivo. In sum, PLIN2 guards its own house, the lipid droplet. PLIN2 overexpression protects against autophagy, and its downregulation stimulates TG catabolism via autophagy.
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Affiliation(s)
- Tsung-Huang Tsai
- a Departments of Medicine, Baylor College of Medicine , Houston , TX , USA
| | - Elaine Chen
- b Molecular and Cellular Biology , Baylor College of Medicine , Houston , TX , USA
| | - Lan Li
- a Departments of Medicine, Baylor College of Medicine , Houston , TX , USA
| | - Pradip Saha
- a Departments of Medicine, Baylor College of Medicine , Houston , TX , USA.,b Molecular and Cellular Biology , Baylor College of Medicine , Houston , TX , USA
| | - Hsiao-Ju Lee
- a Departments of Medicine, Baylor College of Medicine , Houston , TX , USA
| | - Li-Shin Huang
- c Department of Medicine , Columbia University , New York , NY , USA
| | - Gregory S Shelness
- d Department of Internal Medicine , Section on Molecular Medicine, Wake Forest School of Medicine , Winston-Salem , NC , USA
| | - Lawrence Chan
- a Departments of Medicine, Baylor College of Medicine , Houston , TX , USA.,b Molecular and Cellular Biology , Baylor College of Medicine , Houston , TX , USA
| | - Benny Hung-Junn Chang
- a Departments of Medicine, Baylor College of Medicine , Houston , TX , USA.,b Molecular and Cellular Biology , Baylor College of Medicine , Houston , TX , USA
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50
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Maeda Y, Oku M, Sakai Y. Autophagy-independent function of Atg8 in lipid droplet dynamics in yeast. J Biochem 2017; 161:339-348. [PMID: 28003432 DOI: 10.1093/jb/mvw078] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 10/11/2016] [Indexed: 01/05/2023] Open
Abstract
Dynamic features of lipid droplets include growth and degradation of the organelle. Autophagy, a system for the transport of cytoplasmic components to be degraded into the lysosome/vacuole, is regarded to be responsible for the degradation of lipid droplets. Atg8 protein in the yeast Saccharomyces cerevisiae is recruited to membrane structures synthesized during autophagy via a lipidation process. In this study, we report a novel function of Atg8 in lipid droplet dynamics. We found that loss of Atg8 specifically resulted in a decrease in the quantity of lipid droplets in cells at stationary phase. This protein was detected in a lipid droplet fraction independent of its lipidation. Loss of Atg8 hemifusion activity also caused a decrease in the quantity of lipid droplets. Consistent with these results, isolated lipid droplets underwent assembly into large clusters when incubated with Atg8 possessing hemifusion activity. The loss of Atg8 did not reduce the quantity of lipid droplets in a mutant defective in lipolysis, another system for lipid droplet degradation, which strongly suggests the function of Atg8 in antagonizing lipolysis. Together these results indicate a specific function of Atg8 in maintaining the quantity of lipid droplets that is independent of its autophagic function.
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Affiliation(s)
- Yuichiro Maeda
- Division of Applied Life Sciences, Graduate School of Agriculture
| | - Masahide Oku
- Division of Applied Life Sciences, Graduate School of Agriculture
| | - Yasuyoshi Sakai
- Division of Applied Life Sciences, Graduate School of Agriculture
- Research Unit for Physiological Chemistry, the Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kitashirakawa-Oiwake, Kyoto, Sakyo 606-8502, Japan
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