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Rosas-Paz M, Zamora-Bello A, Torres-Ramírez N, Villarreal-Huerta D, Romero-Aguilar L, Pardo JP, El Hafidi M, Sandoval G, Segal-Kischinevzky C, González J. Nitrogen limitation-induced adaptive response and lipogenesis in the Antarctic yeast Rhodotorula mucilaginosa M94C9. Front Microbiol 2024; 15:1416155. [PMID: 39161597 PMCID: PMC11330776 DOI: 10.3389/fmicb.2024.1416155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 07/02/2024] [Indexed: 08/21/2024] Open
Abstract
The extremotolerant red yeast Rhodotorula mucilaginosa displays resilience to diverse environmental stressors, including cold, osmolarity, salinity, and oligotrophic conditions. Particularly, this yeast exhibits a remarkable ability to accumulate lipids and carotenoids in response to stress conditions. However, research into lipid biosynthesis has been hampered by limited genetic tools and a scarcity of studies on adaptive responses to nutrient stressors stimulating lipogenesis. This study investigated the impact of nitrogen stress on the adaptive response in Antarctic yeast R. mucilaginosa M94C9. Varied nitrogen availability reveals a nitrogen-dependent modulation of biomass and lipid droplet production, accompanied by significant ultrastructural changes to withstand nitrogen starvation. In silico analysis identifies open reading frames of genes encoding key lipogenesis enzymes, including acetyl-CoA carboxylase (Acc1), fatty acid synthases 1 and 2 (Fas1/Fas2), and acyl-CoA diacylglycerol O-acyltransferase 1 (Dga1). Further investigation into the expression profiles of RmACC1, RmFAS1, RmFAS2, and RmDGA1 genes under nitrogen stress revealed that the prolonged up-regulation of the RmDGA1 gene is a molecular indicator of lipogenesis. Subsequent fatty acid profiling unveiled an accumulation of oleic and palmitic acids under nitrogen limitation during the stationary phase. This investigation enhances our understanding of nitrogen stress adaptation and lipid biosynthesis, offering valuable insights into R. mucilaginosa M94C9 for potential industrial applications in the future.
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Affiliation(s)
- Miguel Rosas-Paz
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Posgrado en Ciencias Biológicas, Unidad de Posgrado, Circuito de Posgrados, Ciudad Universitaria, Mexico City, Mexico
| | - Alberto Zamora-Bello
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Posgrado en Ciencias Bioquímicas, Unidad de Posgrado, Ciudad Universitaria, Mexico City, Mexico
| | - Nayeli Torres-Ramírez
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Diana Villarreal-Huerta
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Posgrado en Ciencias Biológicas, Unidad de Posgrado, Circuito de Posgrados, Ciudad Universitaria, Mexico City, Mexico
| | - Lucero Romero-Aguilar
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Juan Pablo Pardo
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Mohammed El Hafidi
- Departamento de Biomedicina Cardiovascular, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico
| | - Georgina Sandoval
- Laboratorio de Innovación en Bioenergéticos y Bioprocesos Avanzados, Unidad de Biotecnología Industrial, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco A. C., Guadalajara, Mexico
| | - Claudia Segal-Kischinevzky
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - James González
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
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2
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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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3
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Prado LG, Camara NOS, Barbosa AS. Cell lipid biology in infections: an overview. Front Cell Infect Microbiol 2023; 13:1148383. [PMID: 37868347 PMCID: PMC10587689 DOI: 10.3389/fcimb.2023.1148383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 09/22/2023] [Indexed: 10/24/2023] Open
Abstract
Lipids are a big family of molecules with a vast number of functions in the cell membranes, within the cytoplasm, and extracellularly. Lipid droplets (LDs) are the most common storage organelles and are present in almost every tissue type in the body. They also have structural functions serving as building blocks of cellular membranes and may be precursors of other molecules such as hormones, and lipoproteins, and as messengers in signal transduction. Fatty acids (FAs), such as sterol esters and triacylglycerols, are stored in LDs and are used in β-oxidation as fuel for tricarboxylic acid cycle (TCA) and adenosine triphosphate (ATP) generation. FA uptake and entrance in the cytoplasm are mediated by membrane receptors. After a cytoplasmic round of α- and β-oxidation, FAs are guided into the mitochondrial matrix by the L-carnitine shuttle system, where they are fully metabolized, and enter the TCA cycle. Pathogen infections may lead to impaired lipid metabolism, usage of membrane phospholipids, and LD accumulation in the cytoplasm of infected cells. Otherwise, bacterial pathogens may use lipid metabolism as a carbon source, thus altering the reactions and leading to cellular and organelles malfunctioning. This review aims to describe cellular lipid metabolism and alterations that occur upon infections.
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Affiliation(s)
- Luan Gavião Prado
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, Brazil
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Niels Olsen Saraiva Camara
- Laboratório de Imunobiologia de Transplantes, Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
- Disciplina de Nefrologia, Departamento de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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4
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Jusović M, Starič P, Jarc Jovičić E, Petan T. The Combined Inhibition of Autophagy and Diacylglycerol Acyltransferase-Mediated Lipid Droplet Biogenesis Induces Cancer Cell Death during Acute Amino Acid Starvation. Cancers (Basel) 2023; 15:4857. [PMID: 37835551 PMCID: PMC10571868 DOI: 10.3390/cancers15194857] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 09/25/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
Lipid droplets (LDs) are dynamic organelles involved in the management of fatty acid trafficking and metabolism. Recent studies suggest that autophagy and LDs serve complementary roles in the protection against nutrient stress, but the autophagy-LD interplay in cancer cells is not well understood. Here, we examined the relationship between autophagy and LDs in starving HeLa cervical cancer- and MDA-MB-231 breast cancer cells. We found that acute amino acid depletion induces autophagy and promotes diacylglycerol acyltransferase 1 (DGAT1)-mediated LD accumulation in HeLa cells. Inhibition of autophagy via late-stage autophagy inhibitors, or by knocking down autophagy-related 5 (ATG5), reduced LD accumulation in amino acid-starved cancer cells, suggesting that autophagy contributes to LD biogenesis. On the contrary, knockdown of adipose triglyceride lipase (ATGL) increased LD accumulation, suggesting that LD breakdown is mediated by lipolysis under these conditions. Concurrent inhibition of autophagy by silencing ATG5 and of LD biogenesis using DGAT inhibitors was effective in killing starving HeLa cells, whereas cell survival was not compromised by suppression of ATGL-mediated lipolysis. Autophagy-dependent LD biogenesis was also observed in the aggressive triple-negative MDA-MB-231 breast cancer cells deprived of amino acids, but these cells were not sensitized to starvation by the combined inhibition of LD biogenesis and autophagy. These findings reveal that while targeting autophagy-driven and DGAT-mediated LD biogenesis reduces the resilience of HeLa cervical cancer cells to amino acid deprivation, this strategy may not be successful in other cancer cell types.
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Affiliation(s)
- Maida Jusović
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia; (M.J.); (P.S.); (E.J.J.)
- Jožef Stefan International Postgraduate School, SI-1000 Ljubljana, Slovenia
| | - Pia Starič
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia; (M.J.); (P.S.); (E.J.J.)
| | - Eva Jarc Jovičić
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia; (M.J.); (P.S.); (E.J.J.)
- Jožef Stefan International Postgraduate School, SI-1000 Ljubljana, Slovenia
| | - Toni Petan
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia; (M.J.); (P.S.); (E.J.J.)
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5
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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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6
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A Perspective on the Link between Mitochondria-Associated Membranes (MAMs) and Lipid Droplets Metabolism in Neurodegenerative Diseases. BIOLOGY 2023; 12:biology12030414. [PMID: 36979106 PMCID: PMC10045954 DOI: 10.3390/biology12030414] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/03/2023] [Accepted: 03/06/2023] [Indexed: 03/11/2023]
Abstract
Mitochondria interact with the endoplasmic reticulum (ER) through contacts called mitochondria-associated membranes (MAMs), which control several processes, such as the ER stress response, mitochondrial and ER dynamics, inflammation, apoptosis, and autophagy. MAMs represent an important platform for transport of non-vesicular phospholipids and cholesterol. Therefore, this region is highly enriched in proteins involved in lipid metabolism, including the enzymes that catalyze esterification of cholesterol into cholesteryl esters (CE) and synthesis of triacylglycerols (TAG) from fatty acids (FAs), which are then stored in lipid droplets (LDs). LDs, through contact with other organelles, prevent the toxic consequences of accumulation of unesterified (free) lipids, including lipotoxicity and oxidative stress, and serve as lipid reservoirs that can be used under multiple metabolic and physiological conditions. The LDs break down by autophagy releases of stored lipids for energy production and synthesis of membrane components and other macromolecules. Pathological lipid deposition and autophagy disruption have both been reported to occur in several neurodegenerative diseases, supporting that lipid metabolism alterations are major players in neurodegeneration. In this review, we discuss the current understanding of MAMs structure and function, focusing on their roles in lipid metabolism and the importance of autophagy in LDs metabolism, as well as the changes that occur in neurogenerative diseases.
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7
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Capitanio C, Bieber A, Wilfling F. How Membrane Contact Sites Shape the Phagophore. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2023; 6:25152564231162495. [PMID: 37366413 PMCID: PMC10243513 DOI: 10.1177/25152564231162495] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 02/15/2023] [Accepted: 02/18/2023] [Indexed: 06/28/2023]
Abstract
During macroautophagy, phagophores establish multiple membrane contact sites (MCSs) with other organelles that are pivotal for proper phagophore assembly and growth. In S. cerevisiae, phagophore contacts have been observed with the vacuole, the ER, and lipid droplets. In situ imaging studies have greatly advanced our understanding of the structure and function of these sites. Here, we discuss how in situ structural methods like cryo-CLEM can give unprecedented insights into MCSs, and how they help to elucidate the structural arrangements of MCSs within cells. We further summarize the current knowledge of the contact sites in autophagy, focusing on autophagosome biogenesis in the model organism S. cerevisiae.
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Affiliation(s)
- Cristina Capitanio
- Department of Molecular Machines and
Signaling, Max Planck Institute of Biochemistry, Martinsried, Germany
- Aligning Science Across Parkinson's (ASAP)
Collaborative Research Network, Chevy Chase, MD, USA
| | - Anna Bieber
- Department of Molecular Machines and
Signaling, Max Planck Institute of Biochemistry, Martinsried, Germany
- Aligning Science Across Parkinson's (ASAP)
Collaborative Research Network, Chevy Chase, MD, USA
| | - Florian Wilfling
- Mechanisms of Cellular Quality Control, Max Planck Institute of Biophysics, Frankfurt a. M., Germany
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8
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Bonatto D. The multiple roles of lipid metabolism in yeast physiology during beer fermentation. Genet Mol Biol 2022; 45:e20210325. [PMID: 36149459 PMCID: PMC9511687 DOI: 10.1590/1678-4685-gmb-2021-0325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 07/17/2022] [Indexed: 11/21/2022] Open
Abstract
The ability of brewing yeasts (Saccharomyces cerevisiae and Saccharomyces pastorianus) to cope with the toxic effects of ethanol during beer fermentation depends on the modulation of lipid and lipid droplets (LDs) biosynthesis, which affects membrane fluidity. However, it has been demonstrated that lipids and LDs can modulate different biological mechanisms associated to ethanol tolerance, including proteostasis and autophagy, leading to the hypothesis that lipid and LDs biosynthesis are integrative processes necessary for ethanol tolerance in yeast. Supporting this hypothesis, a transcriptome and systems biology analyses indicated the upregulation of autophagy, lipid biosynthesis, and proteostasis (ALP)-associated genes in lager yeast during beer fermentation, whose respective proteins interact in a shortest-pathway ALP network. These results indicated a cross-communication between various pathways linked to inter-organelle autophagy, lipid metabolism, and proteostasis (ALP) during lager beer fermentation, thus highlighting the importance of lipids for beer fermentation.
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Affiliation(s)
- Diego Bonatto
- Universidade Federal do Rio Grande do Sul, Centro de Biotecnologia da UFRGS, Laboratório de Biologia Molecular e Computacional, Departamento de Biologia Molecular e Biotecnologia, Porto Alegre, RS, Brazil
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9
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Ranganathan PR, Narayanan AK, Nawada N, Rao MJ, Reju KS, Priya SC, Gujarathi T, Manjithaya R, Venkata Rao DK. Diacylglycerol kinase alleviates autophagic degradation of the endoplasmic reticulum in SPT10-deficient yeast to enhance triterpene biosynthesis. FEBS Lett 2022; 596:1778-1794. [PMID: 35661158 DOI: 10.1002/1873-3468.14418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/12/2022] [Accepted: 05/18/2022] [Indexed: 11/08/2022]
Abstract
A recent study showed that deletion of the gene encoding the transcription regulator SuPpressor of Ty10 (SPT10) increases total phospholipids, and our previous study established a critical link between phospholipids and the mevalonate/ergosterol (MEV/ERG) pathway, which synthesizes triterpenes. This study aims to use spt10Δ yeast to improve triterpene production. Though MEV/ERG pathway was highly expressed in spt10Δ yeast, results showed insufficient accumulation of key metabolites and also revealed massive endoplasmic reticulum (ER) degradation. We found a stable, massive ER structure when we overexpressed diacylglycerol kinase1 (DGK1OE ) in spt10Δ yeast. Analyses of ER-stress and autophagy suggest that DGK1OE in the spt10Δ strain decreased autophagy, resulting in increased MEV/ERG pathway activity. Heterologous expression of β-amyrin synthase showed significant production of the triterpene β-amyrin in DGK1OE spt10Δ yeast. Overall, our study provides a strategic approach to improve triterpene production by increasing ER biogenesis while limiting ER degradation.
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Affiliation(s)
- Poornima Ramani Ranganathan
- Biochemistry laboratory, CSIR-Central Institute of Medicinal & Aromatic Plants, Research Center, GKVK (post), Allalasandra, India.,Academy of Scientific and Innovative Research (AcSIR), Kamla Nehru Nagar, Sector 19, Ghaziabad, Uttar Pradesh-201 002, India
| | - Ananth Krishna Narayanan
- Biochemistry laboratory, CSIR-Central Institute of Medicinal & Aromatic Plants, Research Center, GKVK (post), Allalasandra, India.,Academy of Scientific and Innovative Research (AcSIR), Kamla Nehru Nagar, Sector 19, Ghaziabad, Uttar Pradesh-201 002, India
| | - Niveditha Nawada
- Biochemistry laboratory, CSIR-Central Institute of Medicinal & Aromatic Plants, Research Center, GKVK (post), Allalasandra, India.,Academy of Scientific and Innovative Research (AcSIR), Kamla Nehru Nagar, Sector 19, Ghaziabad, Uttar Pradesh-201 002, India
| | - Monala Jayaprakash Rao
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore-560064, India
| | - Kalyani Sai Reju
- Biochemistry laboratory, CSIR-Central Institute of Medicinal & Aromatic Plants, Research Center, GKVK (post), Allalasandra, India
| | - S Chaithra Priya
- Biochemistry laboratory, CSIR-Central Institute of Medicinal & Aromatic Plants, Research Center, GKVK (post), Allalasandra, India
| | - Tejal Gujarathi
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore-560064, India
| | - Ravi Manjithaya
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore-560064, India
| | - D K Venkata Rao
- Biochemistry laboratory, CSIR-Central Institute of Medicinal & Aromatic Plants, Research Center, GKVK (post), Allalasandra, India.,Academy of Scientific and Innovative Research (AcSIR), Kamla Nehru Nagar, Sector 19, Ghaziabad, Uttar Pradesh-201 002, India
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10
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Guo X, Zhou S, Yang Z, Li ZA, Hu W, Dai L, Liang W, Wang X. Comprehensive Analysis of Sterol O-Acyltransferase 1 as a Prognostic Biomarker and Its Association With Immune Infiltration in Glioma. Front Oncol 2022; 12:896433. [PMID: 35646697 PMCID: PMC9133349 DOI: 10.3389/fonc.2022.896433] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 04/11/2022] [Indexed: 12/30/2022] Open
Abstract
Metabolic reprogramming is a hallmark of glioma, and sterol O-acyltransferase 1 (SOAT1) is an essential target for metabolic therapy. However, the prognostic value of SOAT1 and its association with immune infiltration has not been fully elucidated. Using RNA-seq and clinical data of glioma patients from The Cancer Genome Atlas (TCGA), SOAT1 was found to be correlated with poor prognosis in glioma and the advanced malignancy of clinicopathological characteristics. Next, the correlation between SOAT1 expression and tumor-infiltrating immune cells was performed using the single-sample GSEA algorithm, gene expression profiling interactive analysis (GEPIA), and tumor immune estimation resource version 2 (TIMER2.0); it was found that SOAT1 expression was positively correlated with multiple tumor-infiltrating immune cells. To further verify these results, immunofluorescence was conducted on paraffin-embedded glioma specimens, and a positive trend of the correlation between SOAT1 expression and Treg infiltration was observed in this cohort. Finally, differentially expressed gene analysis, and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to explore the biological processes and signaling pathways that SOAT1 may be involved in during glioma pathogenesis. A protein-protein interaction network was established, and co-expression analysis was conducted to investigate the regulatory mechanism of SOAT1 in glioma. To the best of our knowledge, this is the first comprehensive study reporting that SOAT1 may serve as a novel prognostic biomarker associated with immune infiltrates, providing a novel perspective for glioma metabolic therapy.
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Affiliation(s)
- Xuyang Guo
- Department of Neurosurgery, The Fifth Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Henan International Joint Laboratory of Glioma Metabolism and Microenvironment Research, Zhengzhou, China
| | - Shaolong Zhou
- Department of Neurosurgery, The Fifth Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Henan International Joint Laboratory of Glioma Metabolism and Microenvironment Research, Zhengzhou, China
| | - Zhuo Yang
- Department of Neurosurgery, The Fifth Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Henan International Joint Laboratory of Glioma Metabolism and Microenvironment Research, Zhengzhou, China
| | - Zi-An Li
- Department of Neurosurgery, The Fifth Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Henan International Joint Laboratory of Glioma Metabolism and Microenvironment Research, Zhengzhou, China
| | - Weihua Hu
- Henan International Joint Laboratory of Glioma Metabolism and Microenvironment Research, Zhengzhou, China
| | - Lirui Dai
- Department of Neurosurgery, The Fifth Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Henan International Joint Laboratory of Glioma Metabolism and Microenvironment Research, Zhengzhou, China
| | - Wulong Liang
- Henan International Joint Laboratory of Glioma Metabolism and Microenvironment Research, Zhengzhou, China
| | - Xinjun Wang
- Department of Neurosurgery, The Fifth Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Henan International Joint Laboratory of Glioma Metabolism and Microenvironment Research, Zhengzhou, China
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11
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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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Long M, Sanchez-Martinez A, Longo M, Suomi F, Stenlund H, Johansson AI, Ehsan H, Salo VT, Montava-Garriga L, Naddafi S, Ikonen E, Ganley IG, Whitworth AJ, McWilliams TG. DGAT1 activity synchronises with mitophagy to protect cells from metabolic rewiring by iron depletion. EMBO J 2022; 41:e109390. [PMID: 35411952 PMCID: PMC9108618 DOI: 10.15252/embj.2021109390] [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: 08/05/2021] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 12/28/2022] Open
Abstract
Mitophagy removes defective mitochondria via lysosomal elimination. Increased mitophagy coincides with metabolic reprogramming, yet it remains unknown whether mitophagy is a cause or consequence of such state changes. The signalling pathways that integrate with mitophagy to sustain cell and tissue integrity also remain poorly defined. We performed temporal metabolomics on mammalian cells treated with deferiprone, a therapeutic iron chelator that stimulates PINK1/PARKIN-independent mitophagy. Iron depletion profoundly rewired the metabolome, hallmarked by remodelling of lipid metabolism within minutes of treatment. DGAT1-dependent lipid droplet biosynthesis occurred several hours before mitochondrial clearance, with lipid droplets bordering mitochondria upon iron chelation. We demonstrate that DGAT1 inhibition restricts mitophagy in vitro, with impaired lysosomal homeostasis and cell viability. Importantly, genetic depletion of DGAT1 in vivo significantly impaired neuronal mitophagy and locomotor function in Drosophila. Our data define iron depletion as a potent signal that rapidly reshapes metabolism and establishes an unexpected synergy between lipid homeostasis and mitophagy that safeguards cell and tissue integrity.
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Affiliation(s)
- Maeve Long
- Translational Stem Cell Biology & Metabolism Program, Research Programs Unit, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
| | | | - Marianna Longo
- MRC Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, The Sir James Black Centre, University of Dundee, Dundee, UK
| | - Fumi Suomi
- Translational Stem Cell Biology & Metabolism Program, Research Programs Unit, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
| | - Hans Stenlund
- Swedish Metabolomics Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Annika I Johansson
- Swedish Metabolomics Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Homa Ehsan
- Translational Stem Cell Biology & Metabolism Program, Research Programs Unit, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
| | - Veijo T Salo
- Translational Stem Cell Biology & Metabolism Program, Research Programs Unit, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland.,Department of Anatomy, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Lambert Montava-Garriga
- MRC Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, The Sir James Black Centre, University of Dundee, Dundee, UK
| | - Seyedehshima Naddafi
- Translational Stem Cell Biology & Metabolism Program, Research Programs Unit, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
| | - Elina Ikonen
- Translational Stem Cell Biology & Metabolism Program, Research Programs Unit, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland.,Department of Anatomy, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Ian G Ganley
- MRC Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, The Sir James Black Centre, University of Dundee, Dundee, UK
| | | | - Thomas G McWilliams
- Translational Stem Cell Biology & Metabolism Program, Research Programs Unit, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland.,Department of Anatomy, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
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13
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Liao PC, Yang EJ, Borgman T, Boldogh IR, Sing CN, Swayne TC, Pon LA. Touch and Go: Membrane Contact Sites Between Lipid Droplets and Other Organelles. Front Cell Dev Biol 2022; 10:852021. [PMID: 35281095 PMCID: PMC8908909 DOI: 10.3389/fcell.2022.852021] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 02/03/2022] [Indexed: 12/26/2022] Open
Abstract
Lipid droplets (LDs) have emerged not just as storage sites for lipids but as central regulators of metabolism and organelle quality control. These critical functions are achieved, in part, at membrane contact sites (MCS) between LDs and other organelles. MCS are sites of transfer of cellular constituents to or from LDs for energy mobilization in response to nutrient limitations, as well as LD biogenesis, expansion and autophagy. Here, we describe recent findings on the mechanisms underlying the formation and function of MCS between LDs and mitochondria, ER and lysosomes/vacuoles and the role of the cytoskeleton in promoting LD MCS through its function in LD movement and distribution in response to environmental cues.
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Affiliation(s)
- Pin-Chao Liao
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan
| | - Emily J. Yang
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Taylor Borgman
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States
| | - Istvan R. Boldogh
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, United States
| | - Cierra N. Sing
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States
| | - Theresa C. Swayne
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, United States
| | - Liza A. Pon
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States
- *Correspondence: Liza A. Pon,
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14
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Flores-Cotera LB, Chávez-Cabrera C, Martínez-Cárdenas A, Sánchez S, García-Flores OU. Deciphering the mechanism by which the yeast Phaffia rhodozyma responds adaptively to environmental, nutritional, and genetic cues. J Ind Microbiol Biotechnol 2021; 48:kuab048. [PMID: 34302341 PMCID: PMC8788774 DOI: 10.1093/jimb/kuab048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 07/16/2021] [Indexed: 11/13/2022]
Abstract
Phaffia rhodozyma is a basidiomycetous yeast that synthesizes astaxanthin (ASX), which is a powerful and highly valuable antioxidant carotenoid pigment. P. rhodozyma cells accrue ASX and gain an intense red-pink coloration when faced with stressful conditions such as nutrient limitations (e.g., nitrogen or copper), the presence of toxic substances (e.g., antimycin A), or are affected by mutations in the genes that are involved in nitrogen metabolism or respiration. Since cellular accrual of ASX occurs under a wide variety of conditions, this yeast represents a valuable model for studying the growth conditions that entail oxidative stress for yeast cells. Recently, we proposed that ASX synthesis can be largely induced by conditions that lead to reduction-oxidation (redox) imbalances, particularly the state of the NADH/NAD+ couple together with an oxidative environment. In this work, we review the multiple known conditions that elicit ASX synthesis expanding on the data that we formerly examined. When considered alongside the Mitchell's chemiosmotic hypothesis, the study served to rationalize the induction of ASX synthesis and other adaptive cellular processes under a much broader set of conditions. Our aim was to propose an underlying mechanism that explains how a broad range of divergent conditions converge to induce ASX synthesis in P. rhodozyma. The mechanism that links the induction of ASX synthesis with the occurrence of NADH/NAD+ imbalances may help in understanding how other organisms detect any of a broad array of stimuli or gene mutations, and then adaptively respond to activate numerous compensatory cellular processes.
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Affiliation(s)
- Luis B Flores-Cotera
- Department of Biotechnology and Bioengineering, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, México city 07360, México
| | - Cipriano Chávez-Cabrera
- Department of Biotechnology and Bioengineering, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, México city 07360, México
| | - Anahi Martínez-Cárdenas
- Department of Biotechnology and Bioengineering, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, México city 07360, México
| | - Sergio Sánchez
- Department of Molecular Biology and Biotechnology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México city 04510, México
| | - Oscar Ulises García-Flores
- Department of Biotechnology and Bioengineering, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, México city 07360, México
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15
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Heinz D, Krotova E, Hamann A, Osiewacz HD. Simultaneous Ablation of the Catalytic AMPK α-Subunit SNF1 and Mitochondrial Matrix Protease CLPP Results in Pronounced Lifespan Extension. Front Cell Dev Biol 2021; 9:616520. [PMID: 33748105 PMCID: PMC7969656 DOI: 10.3389/fcell.2021.616520] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 01/27/2021] [Indexed: 12/21/2022] Open
Abstract
Organismic aging is known to be controlled by genetic and environmental traits. Pathways involved in the control of cellular metabolism play a crucial role. Previously, we identified a role of PaCLPP, a mitochondrial matrix protease, in the control of the mitochondrial energy metabolism, aging, and lifespan of the fungal aging model Podospora anserina. Most surprisingly, we made the counterintuitive observation that the ablation of this component of the mitochondrial quality control network leads to lifespan extension. In the current study, we investigated the role of energy metabolism of P. anserina. An age-dependent metabolome analysis of the wild type and a PaClpP deletion strain verified differences and changes of various metabolites in cultures of the PaClpP mutant and the wild type. Based on these data, we generated and analyzed a PaSnf1 deletion mutant and a ΔPaSnf1/ΔPaClpP double mutant. In both mutants PaSNF1, the catalytic α-subunit of AMP-activated protein kinase (AMPK) is ablated. PaSNF1 was found to be required for the development of fruiting bodies and ascospores and the progeny of sexual reproduction of this ascomycete and impact mitochondrial dynamics and autophagy. Most interestingly, while the single PaSnf1 deletion mutant is characterized by a slight lifespan increase, simultaneous deletion of PaSnf1 and PaClpP leads to a pronounced lifespan extension. This synergistic effect is strongly reinforced in the presence of the mating-type "minus"-linked allele of the rmp1 gene. Compared to the wild type, culture temperature of 35°C instead of the standard laboratory temperature of 27°C leads to a short-lived phenotype of the ΔPaSnf1/ΔPaClpP double mutant. Overall, our study provides novel evidence for complex interactions of different molecular pathways involved in mitochondrial quality control, gene expression, and energy metabolism in the control of organismic aging.
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Affiliation(s)
| | | | | | - Heinz D. Osiewacz
- Institute of Molecular Biosciences, J.W. Goethe University, Frankfurt am Main, Germany
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16
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Amino acid starvation inhibits autophagy in lipid droplet-deficient cells through mitochondrial dysfunction. Biochem J 2021; 477:3613-3623. [PMID: 32886124 DOI: 10.1042/bcj20200551] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/03/2020] [Accepted: 09/04/2020] [Indexed: 12/18/2022]
Abstract
Lipid droplets are ubiquitous organelles in eukaryotes that act as storage sites for neutral lipids. Under normal growth conditions, they are not required in the yeast Saccharomyces cerevisiae. However, recent works have shown that lipid droplets are required for autophagy to proceed in response to nitrogen starvation and that they play an essential role in maintaining ER homeostasis. Autophagy is a major catabolic pathway that helps degradation and recycling of potentially harmful proteins and organelles. It can be pharmacologically induced by rapamycin even in the absence of lipid droplets. Here, we show that amino acid starvation is responsible for autophagy failure in lipid droplet-deficient yeast. It not only fails to induce autophagy but also inhibits rapamycin-induced autophagy. The general amino acid control pathway is not involved in this paradoxical effect of amino acid shortage. We correlate the autophagy failure with mitochondria aggregation and we show that amino acid starvation-induced autophagy is restored in lipid droplet-deficient yeast by increasing mitochondrial biomass physiologically (respiration) or genetically (REG1 deletion). Our results establish a new functional link between lipid droplets, ER and mitochondria during nitrogen starvation-induced autophagy.
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17
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Schepers J, Behl C. Lipid droplets and autophagy-links and regulations from yeast to humans. J Cell Biochem 2021; 122:602-611. [PMID: 33522032 DOI: 10.1002/jcb.29889] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 12/04/2020] [Accepted: 12/28/2020] [Indexed: 12/22/2022]
Abstract
Recent advances in the yeast Saccharomyces cerevisiae and higher eukaryotes have been increasingly connecting lipid droplet (LD) dynamics to the regulation of autophagy. In this review we will discuss implications that connect LD de novo synthesis and LD mobilization to autophagy and how autophagy is regulated by these mechanisms. Elucidating these connections might pose a chance to further understand autophagy induction and membrane biogenesis for the growing autophagosome under different conditions. Increasing our understanding of these mechanisms might provide a chance to understand several conditions that might be related to LD dysregulation and, possibly, as a consequence of this, dysregulation of autophagy.
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Affiliation(s)
- Jana Schepers
- The Autophagy Lab, Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Christian Behl
- The Autophagy Lab, Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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18
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Ogasawara Y, Cheng J, Tatematsu T, Uchida M, Murase O, Yoshikawa S, Ohsaki Y, Fujimoto T. Long-term autophagy is sustained by activation of CCTβ3 on lipid droplets. Nat Commun 2020; 11:4480. [PMID: 32900992 PMCID: PMC7479109 DOI: 10.1038/s41467-020-18153-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 08/07/2020] [Indexed: 12/12/2022] Open
Abstract
Macroautophagy initiates by formation of isolation membranes, but the source of phospholipids for the membrane biogenesis remains elusive. Here, we show that autophagic membranes incorporate newly synthesized phosphatidylcholine, and that CTP:phosphocholine cytidylyltransferase β3 (CCTβ3), an isoform of the rate-limiting enzyme in the Kennedy pathway, plays an essential role. In starved mouse embryo fibroblasts, CCTβ3 is initially recruited to autophagic membranes, but upon prolonged starvation, it concentrates on lipid droplets that are generated from autophagic degradation products. Omegasomes and isolation membranes emanate from around those lipid droplets. Autophagy in prolonged starvation is suppressed by knockdown of CCTβ3 and is enhanced by its overexpression. This CCTβ3-dependent mechanism is also present in U2OS, an osteosarcoma cell line, and autophagy and cell survival in starvation are decreased by CCTβ3 depletion. The results demonstrate that phosphatidylcholine synthesis through CCTβ3 activation on lipid droplets is crucial for sustaining autophagy and long-term cell survival.
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Affiliation(s)
- Yuta Ogasawara
- Laboratory of Molecular Cell Biology, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo, Tokyo, 113-8421, Japan
| | - Jinglei Cheng
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Tsuyako Tatematsu
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Misaki Uchida
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Omi Murase
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Shogo Yoshikawa
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Yuki Ohsaki
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Toyoshi Fujimoto
- Laboratory of Molecular Cell Biology, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo, Tokyo, 113-8421, Japan.
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19
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Li D, Yang SG, He CW, Zhang ZT, Liang Y, Li H, Zhu J, Su X, Gong Q, Xie Z. Excess diacylglycerol at the endoplasmic reticulum disrupts endomembrane homeostasis and autophagy. BMC Biol 2020; 18:107. [PMID: 32859196 PMCID: PMC7453538 DOI: 10.1186/s12915-020-00837-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 07/24/2020] [Indexed: 01/22/2023] Open
Abstract
Background When stressed, eukaryotic cells produce triacylglycerol (TAG) to store nutrients and mobilize autophagy to combat internal damage. We and others previously reported that in yeast, elimination of TAG synthesizing enzymes inhibits autophagy under nitrogen starvation, yet the underlying mechanism has remained elusive. Results Here, we show that disruption of TAG synthesis led to diacylglycerol (DAG) accumulation and its relocation from the vacuolar membrane to the endoplasmic reticulum (ER). We further show that, beyond autophagy, ER-accumulated DAG caused severe defects in the endomembrane system, including disturbing the balance of ER-Golgi protein trafficking, manifesting in bulging of ER and loss of the Golgi apparatus. Genetic or chemical manipulations that increase consumption or decrease supply of DAG reversed these defects. In contrast, increased amounts of precursors of glycerolipid synthesis, including phosphatidic acid and free fatty acids, did not replicate the effects of excess DAG. We also provide evidence that the observed endomembrane defects do not rely on Golgi-produced DAG, Pkc1 signaling, or the unfolded protein response. Conclusions This work identifies DAG as the critical lipid molecule responsible for autophagy inhibition under condition of defective TAG synthesis and demonstrates the disruption of ER and Golgi function by excess DAG as the potential cause of the autophagy defect.
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Affiliation(s)
- Dan Li
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, #800 Dong-Chuan Road, Shanghai, 200240, People's Republic of China
| | - Shu-Gao Yang
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou, Jiangsu, People's Republic of China
| | - Cheng-Wen He
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, #800 Dong-Chuan Road, Shanghai, 200240, People's Republic of China
| | - Zheng-Tan Zhang
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, #800 Dong-Chuan Road, Shanghai, 200240, People's Republic of China
| | - Yongheng Liang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - Hui Li
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, #800 Dong-Chuan Road, Shanghai, 200240, People's Republic of China
| | - Jing Zhu
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, #800 Dong-Chuan Road, Shanghai, 200240, People's Republic of China
| | - Xiong Su
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou, Jiangsu, People's Republic of China.
| | - Qingqiu Gong
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, #800 Dong-Chuan Road, Shanghai, 200240, People's Republic of China.
| | - Zhiping Xie
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, #800 Dong-Chuan Road, Shanghai, 200240, People's Republic of China.
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20
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Yang M, Li C, Yang S, Xiao Y, Xiong X, Chen W, Zhao H, Zhang Q, Han Y, Sun L. Mitochondria-Associated ER Membranes - The Origin Site of Autophagy. Front Cell Dev Biol 2020; 8:595. [PMID: 32766245 PMCID: PMC7378804 DOI: 10.3389/fcell.2020.00595] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/18/2020] [Indexed: 12/21/2022] Open
Abstract
Autophagy is a process of intracellular self-recycling and degradation that plays an important role in maintaining cell homeostasis. However, the molecular mechanism of autophagy remains to be further studied. Mitochondria-associated endoplasmic reticulum membranes (MAMs) are the region of the ER that mediate communication between the ER and mitochondria. MAMs have been demonstrated to be involved in autophagy, Ca2+ transport and lipid metabolism. Here, we discuss the composition and function of MAMs, more specifically, to emphasize the role of MAMs in regulating autophagy. Finally, some key information that may be useful for future research is summarized.
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Affiliation(s)
- Ming Yang
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Chenrui Li
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Shikun Yang
- Department of Nephrology, The Third Xiangya Hospital of Central South University, Changsha, China
| | - Ying Xiao
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Xiaofen Xiong
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Wei Chen
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Hao Zhao
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Qin Zhang
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Yachun Han
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Lin Sun
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, China
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21
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Emerging roles of ATG proteins and membrane lipids in autophagosome formation. Cell Discov 2020; 6:32. [PMID: 32509328 PMCID: PMC7248066 DOI: 10.1038/s41421-020-0161-3] [Citation(s) in RCA: 149] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/21/2020] [Indexed: 12/12/2022] Open
Abstract
Autophagosome biogenesis is a dynamic membrane event, which is executed by the sequential function of autophagy-related (ATG) proteins. Upon autophagy induction, a cup-shaped membrane structure appears in the cytoplasm, then elongates sequestering cytoplasmic materials, and finally forms a closed double membrane autophagosome. However, how this complex vesicle formation event is strictly controlled and achieved is still enigmatic. Recently, there is accumulating evidence showing that some ATG proteins have the ability to directly interact with membranes, transfer lipids between membranes and regulate lipid metabolism. A novel role for various membrane lipids in autophagosome formation is also emerging. Here, we highlight past and recent key findings on the function of ATG proteins related to autophagosome biogenesis and consider how ATG proteins control this dynamic membrane formation event to organize the autophagosome by collaborating with membrane lipids.
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22
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Seena S, Sobral O, Cano A. Metabolomic, functional, and ecologic responses of the common freshwater fungus Neonectria lugdunensis to mine drainage stress. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 718:137359. [PMID: 32092520 DOI: 10.1016/j.scitotenv.2020.137359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/14/2020] [Accepted: 02/14/2020] [Indexed: 06/10/2023]
Abstract
Metal contamination of watersheds is a global problem. Here, we conducted litter decomposition studies with Neonectria lugdunensis, a cosmopolitan aquatic fungus. Fungal isolates from four reference (non-impacted) and six metal-contaminated streams (due to mine drainage) were exposed to mine drainage and reference stream waters in Central Portugal. Impact of mine drainage waters on N. lugdunensis hyphae was investigated by performing metabolomic profiling of 200 lipids and 25 amino acids (AA) with ultra-high performance liquid chromatography-mass spectrometry. In parallel, functional response of N. lugdunensis isolates was assessed through expression profiles of a functional gene, cellobiohydrolase I (CbhI). Ecological performance via leaf mass loss was also determined. Exposure to mine drainage waters altered the concentration of numerous AA and lipids. Most strikingly, a gradual increase in the concentration of the triacylglycerols (TAG) with shorter acyl chains and lesser unsaturation was observed after the exposure to mine drainage waters. In addition, the changes in the concentration of numerous TAG, lysophosphatidylcholines, and AA were more significant in the isolates from the metal-contaminated streams after exposure to mine drainage water. CbhI gene of the isolates from reference streams was down-regulated by metal stress, while those from metal-contaminated streams remained unaffected. Finally, leaf mass loss was influenced by both exposure to mine drainage waters and the origin of isolates. Overall, our study demonstrates unique functional signatures displayed by fungi under metal stress and the relevant role that fungal AA and lipids play to cope with metal toxicity.
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Affiliation(s)
- Sahadevan Seena
- MARE - Marine and Environmental Sciences Centre, University of Coimbra, PT-3004-517 Coimbra, Portugal; CBMA - Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
| | - Olímpia Sobral
- MARE - Marine and Environmental Sciences Centre, University of Coimbra, PT-3004-517 Coimbra, Portugal; CBMA - Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Ainara Cano
- ONE WAY LIVER, S.L., Parque Tecnológico de Bizkaia, edif.502- plta 0, 48160 Derio, Bizkaia, Spain
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23
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Kohler V, Aufschnaiter A, Büttner S. Closing the Gap: Membrane Contact Sites in the Regulation of Autophagy. Cells 2020; 9:E1184. [PMID: 32397538 PMCID: PMC7290522 DOI: 10.3390/cells9051184] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 12/14/2022] Open
Abstract
In all eukaryotic cells, intracellular organization and spatial separation of incompatible biochemical processes is established by individual cellular subcompartments in form of membrane-bound organelles. Virtually all of these organelles are physically connected via membrane contact sites (MCS), allowing interorganellar communication and a functional integration of cellular processes. These MCS coordinate the exchange of diverse metabolites and serve as hubs for lipid synthesis and trafficking. While this of course indirectly impacts on a plethora of biological functions, including autophagy, accumulating evidence shows that MCS can also directly regulate autophagic processes. Here, we focus on the nexus between interorganellar contacts and autophagy in yeast and mammalian cells, highlighting similarities and differences. We discuss MCS connecting the ER to mitochondria or the plasma membrane, crucial for early steps of both selective and non-selective autophagy, the yeast-specific nuclear-vacuolar tethering system and its role in microautophagy, the emerging function of distinct autophagy-related proteins in organellar tethering as well as novel MCS transiently emanating from the growing phagophore and mature autophagosome.
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Affiliation(s)
- Verena Kohler
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden;
| | - Andreas Aufschnaiter
- Department of Biochemistry and Biophysics, Stockholm University, 106 91 Stockholm, Sweden;
| | - Sabrina Büttner
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden;
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
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24
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Nakatogawa H. Mechanisms governing autophagosome biogenesis. Nat Rev Mol Cell Biol 2020; 21:439-458. [PMID: 32372019 DOI: 10.1038/s41580-020-0241-0] [Citation(s) in RCA: 435] [Impact Index Per Article: 108.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2020] [Indexed: 12/20/2022]
Abstract
Autophagosomes are double-membrane vesicles newly formed during autophagy to engulf a wide range of intracellular material and transport this autophagic cargo to lysosomes (or vacuoles in yeasts and plants) for subsequent degradation. Autophagosome biogenesis responds to a plethora of signals and involves unique and dynamic membrane processes. Autophagy is an important cellular mechanism allowing the cell to meet various demands, and its disruption compromises homeostasis and leads to various diseases, including metabolic disorders, neurodegeneration and cancer. Thus, not surprisingly, the elucidation of the molecular mechanisms governing autophagosome biogenesis has attracted considerable interest. Key molecules and organelles involved in autophagosome biogenesis, including autophagy-related (ATG) proteins and the endoplasmic reticulum, have been discovered, and their roles and relationships have been investigated intensely. However, several fundamental questions, such as what supplies membranes/lipids to build the autophagosome and how the membrane nucleates, expands, bends into a spherical shape and finally closes, have proven difficult to address. Nonetheless, owing to recent studies with new approaches and technologies, we have begun to unveil the mechanisms underlying these processes on a molecular level. We now know that autophagosome biogenesis is a highly complex process, in which multiple proteins and lipids from various membrane sources, supported by the formation of membrane contact sites, cooperate with biophysical phenomena, including membrane shaping and liquid-liquid phase separation, to ensure seamless segregation of the autophagic cargo. Together, these studies pave the way to obtaining a holistic view of autophagosome biogenesis.
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Affiliation(s)
- Hitoshi Nakatogawa
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan.
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25
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Zhang Y, Huang N, Lu H, Huang J, Jin H, Shi J, Jin F. Icariin protects against sodium azide-induced neurotoxicity by activating the PI3K/Akt/GSK-3β signaling pathway. PeerJ 2020; 8:e8955. [PMID: 32341897 PMCID: PMC7179568 DOI: 10.7717/peerj.8955] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/21/2020] [Indexed: 01/22/2023] Open
Abstract
Background Icariin (ICA) is one of the major active flavonoids extracted from the traditional Chinese herb Epimedium brevicornum Maxim and has been shown to have neuroprotective effects. This study was designed to investigate the effect of ICA on sodium azide (NaN3)-induced rat adrenal pheochromocytoma (PC12) cell damage and to further examine the underlying mechanisms. Methods To explore its possible mechanism, we used NaN3 (50 mM)-induced neuronal PC12 cell damage. Cell viability was evaluated by CCK-8 and lactate dehydrogenase (LDH) assays. Mitochondrial membrane potential (MMP) was detected by JC-1. Glucose concentration was assessed by the glucose oxidase method. The role of ICA in the PI3K/Akt/GSK-3β signaling pathway was explored by Western blotting. Results The results indicate that pretreatment with ICA reduced NaN3-induced cell damage and significantly reduced the leakage rate of LDH in PC12 cells. ICA pretreatment increased the MMP and a decrease in glucose concentration indicate increased glucose consumption. Furthermore, the protein levels of p-PI3K (p85), PI3K-110α, p-Ser473-Akt and p-Ser9-GSK-3β were markedly decreased in PC12 cells after NaN3 treatment for 24 h, whereas these effects were reverted after pretreatment with ICA. Tau phosphorylation at the Ser396/404 and Thr217 sites was significantly decreased by pretreatment with ICA. Conclusions These results suggest that ICA protects against NaN3-induced neurotoxicity in PC12 cells by activating the PI3K/Akt/GSK-3β signaling pathway.
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Affiliation(s)
- Ying Zhang
- Key Laboratory of Basic Pharmacology and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, Guizhou, China.,Department of Pharmacy, People's Hospital of Zhongmu, Zhengzhou, Henan, China
| | - Nanqu Huang
- National Drug Clinical Trial Institution, The Third Affiliated Hospital of Zunyi Medical University (The First People's Hospital of Zunyi), Zunyi, Guizhou, China
| | - Hao Lu
- Key Laboratory of Basic Pharmacology and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, Guizhou, China
| | - Juan Huang
- Key Laboratory of Basic Pharmacology and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, Guizhou, China.,School of Public Health, Zunyi Medical University, Zunyi, Guizhou, China
| | - Hai Jin
- Institute of Digestive Diseases of Affiliated Hospital, Zunyi Medical University, Zunyi, Guizhou, China
| | - Jingshan Shi
- Key Laboratory of Basic Pharmacology and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, Guizhou, China
| | - Feng Jin
- Key Laboratory of Basic Pharmacology and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, Guizhou, China
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26
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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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27
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Araiza-Villanueva MG, Olicón-Hernández DR, Pardo JP, Vázquez-Meza H, Guerra-Sánchez G. Monitoring of the enzymatic activity of intracellular lipases of Ustilago maydis expressed during the growth under nitrogen limitation and its correlation in lipolytic reactions. GRASAS Y ACEITES 2019. [DOI: 10.3989/gya.1049182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Under nitrogen starvation, Ustilago maydis forms lipid droplets (LDs). Although the dynamics of these organelles are known in the literature, the identity of the lipases implicated in their degradation is unknown. We determined lipase activity and identified the intracellular lipases expressed during growth under nitrogen starvation and YPD media by zymograms. The results showed that cytosolic extracts exhibited higher lipase activity when cells were grown in YPD. Under nitrogen starvation, lipase activity was not detected after 24 h of culture, resulting in lipid accumulation in LDs. This suggests that these lipases could be implicated in LD degradation. In the zymogram, two bands, one of 25 and the other of 37 kDa, presented lipase activity. The YPD extracts showed lipase activity in olive and almond oils, which contain triacylglycerols with mono and polyunsaturated fatty acids. This is the first report about U. maydis cytosolic lipases involved in LD degradation.
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Gross AS, Zimmermann A, Pendl T, Schroeder S, Schoenlechner H, Knittelfelder O, Lamplmayr L, Santiso A, Aufschnaiter A, Waltenstorfer D, Ortonobes Lara S, Stryeck S, Kast C, Ruckenstuhl C, Hofer SJ, Michelitsch B, Woelflingseder M, Müller R, Carmona-Gutierrez D, Madl T, Büttner S, Fröhlich KU, Shevchenko A, Eisenberg T. Acetyl-CoA carboxylase 1-dependent lipogenesis promotes autophagy downstream of AMPK. J Biol Chem 2019; 294:12020-12039. [PMID: 31209110 PMCID: PMC6690696 DOI: 10.1074/jbc.ra118.007020] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 05/31/2019] [Indexed: 12/16/2022] Open
Abstract
Autophagy, a membrane-dependent catabolic process, ensures survival of aging cells and depends on the cellular energetic status. Acetyl-CoA carboxylase 1 (Acc1) connects central energy metabolism to lipid biosynthesis and is rate-limiting for the de novo synthesis of lipids. However, it is unclear how de novo lipogenesis and its metabolic consequences affect autophagic activity. Here, we show that in aging yeast, autophagy levels highly depend on the activity of Acc1. Constitutively active Acc1 (acc1S/A) or a deletion of the Acc1 negative regulator, Snf1 (yeast AMPK), shows elevated autophagy levels, which can be reversed by the Acc1 inhibitor soraphen A. Vice versa, pharmacological inhibition of Acc1 drastically reduces cell survival and results in the accumulation of Atg8-positive structures at the vacuolar membrane, suggesting late defects in the autophagic cascade. As expected, acc1S/A cells exhibit a reduction in acetate/acetyl-CoA availability along with elevated cellular lipid content. However, concomitant administration of acetate fails to fully revert the increase in autophagy exerted by acc1S/A. Instead, administration of oleate, while mimicking constitutively active Acc1 in WT cells, alleviates the vacuolar fusion defects induced by Acc1 inhibition. Our results argue for a largely lipid-dependent process of autophagy regulation downstream of Acc1. We present a versatile genetic model to investigate the complex relationship between acetate metabolism, lipid homeostasis, and autophagy and propose Acc1-dependent lipogenesis as a fundamental metabolic path downstream of Snf1 to maintain autophagy and survival during cellular aging.
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Affiliation(s)
- Angelina S Gross
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Andreas Zimmermann
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria; Central Lab Gracia, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Tobias Pendl
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Sabrina Schroeder
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria; BioTechMed-Graz, 8010 Graz, Austria
| | - Hannes Schoenlechner
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Oskar Knittelfelder
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Laura Lamplmayr
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Ana Santiso
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Andreas Aufschnaiter
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria; Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, 114 19 Stockholm, Sweden
| | - Daniel Waltenstorfer
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Sandra Ortonobes Lara
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Sarah Stryeck
- Gottfried Schatz Research Center for Cell Signaling, Metabolism, and Aging, Institute of Molecular Biology and Biochemistry, Medical University of Graz, 8036 Graz, Austria
| | - Christina Kast
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Christoph Ruckenstuhl
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Sebastian J Hofer
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria; BioTechMed-Graz, 8010 Graz, Austria
| | - Birgit Michelitsch
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria; Division of Plastic, Aesthetic, and Reconstructive Surgery, Department of Surgery, Medical University of Graz, 8036 Graz, Austria
| | | | - Rolf Müller
- Helmholtz Institute for Pharmaceutical Research Saarland, 66123 Saarbrücken, Germany
| | | | - Tobias Madl
- BioTechMed-Graz, 8010 Graz, Austria; Gottfried Schatz Research Center for Cell Signaling, Metabolism, and Aging, Institute of Molecular Biology and Biochemistry, Medical University of Graz, 8036 Graz, Austria
| | - Sabrina Büttner
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria; Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, 114 19 Stockholm, Sweden
| | - Kai-Uwe Fröhlich
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Andrej Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Tobias Eisenberg
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria; Central Lab Gracia, NAWI Graz, University of Graz, 8010 Graz, Austria; BioTechMed-Graz, 8010 Graz, Austria.
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Lie S, Banks P, Lawless C, Lydall D, Petersen J. The contribution of non-essential Schizosaccharomyces pombe genes to fitness in response to altered nutrient supply and target of rapamycin activity. Open Biol 2019; 8:rsob.180015. [PMID: 29720420 PMCID: PMC5990653 DOI: 10.1098/rsob.180015] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 04/06/2018] [Indexed: 12/12/2022] Open
Abstract
Nutrient fluctuations in the cellular environment promote changes in cell metabolism and growth to adapt cell proliferation accordingly. The target of rapamycin (TOR) signalling network plays a key role in the coordination of growth and cell proliferation with the nutrient environment and, importantly, nutrient limitation reduces TOR complex 1 (TORC1) signalling. We have performed global quantitative fitness profiling of the collection of Schizosaccharomyces pombe strains from which non-essential genes have been deleted. We identified genes that regulate fitness when cells are grown in a nutrient-rich environment compared with minimal environments, with varying nitrogen sources including ammonium, glutamate and proline. In addition, we have performed the first global screen for genes that regulate fitness when both TORC1 and TORC2 signalling is reduced by Torin1. Analysis of genes whose deletions altered fitness when nutrients were limited, or when TOR signalling was compromised, identified a large number of genes that regulate transmembrane transport, transcription and chromatin organization/regulation and vesicle-mediated transport. The ability to tolerate reduced TOR signalling placed demands upon a large number of biological processes including autophagy, mRNA metabolic processing and nucleocytoplasmic transport. Importantly, novel biological processes and all processes known to be regulated by TOR were identified in our screens. In addition, deletion of 62 genes conserved in humans gave rise to strong sensitivity or resistance to Torin1, and 29 of these 62 genes have novel links to TOR signalling. The identification of chromatin and transcriptional regulation, nutritional uptake and transport pathways in this powerful genetic model now paves the way for a molecular understanding of how cells adapt to the chronic and acute fluctuations in nutrient supply that all eukaryotes experience at some stage, and which is a key feature of cancer cells within solid tumours.
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Affiliation(s)
- Shervi Lie
- Flinders Centre for Innovation in Cancer, College of Medicine & Public Health, Flinders University, Bedford Park, Adelaide, South Australia 5042, Australia
| | - Peter Banks
- High Throughput Screening Facility, Newcastle Biomedicine, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Conor Lawless
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - David Lydall
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - Janni Petersen
- Flinders Centre for Innovation in Cancer, College of Medicine & Public Health, Flinders University, Bedford Park, Adelaide, South Australia 5042, Australia .,South Australia Health and Medical Research Institute, North Terrace, PO Box 11060, Adelaide, South Australia 5000, Australia
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30
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Parzych KR, Klionsky DJ. Vacuolar hydrolysis and efflux: current knowledge and unanswered questions. Autophagy 2018; 15:212-227. [PMID: 30422029 DOI: 10.1080/15548627.2018.1545821] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Hydrolysis within the vacuole in yeast and the lysosome in mammals is required for the degradation and recycling of a multitude of substrates, many of which are delivered to the vacuole/lysosome by autophagy. In humans, defects in lysosomal hydrolysis and efflux can have devastating consequences, and contribute to a class of diseases referred to as lysosomal storage disorders. Despite the importance of these processes, many of the proteins and regulatory mechanisms involved in hydrolysis and efflux are poorly understood. In this review, we describe our current knowledge of the vacuolar/lysosomal degradation and efflux of a vast array of substrates, focusing primarily on what is known in the yeast Saccharomyces cerevisiae. We also highlight many unanswered questions, the answers to which may lead to new advances in the treatment of lysosomal storage disorders. Abbreviations: Ams1: α-mannosidase; Ape1: aminopeptidase I; Ape3: aminopeptidase Y; Ape4: aspartyl aminopeptidase; Atg: autophagy related; Cps1: carboxypeptidase S; CTNS: cystinosin, lysosomal cystine transporter; CTSA: cathepsin A; CTSD: cathepsin D; Cvt: cytoplasm-to-vacuole targeting; Dap2: dipeptidyl aminopeptidase B; GS-bimane: glutathione-S-bimane; GSH: glutathione; LDs: lipid droplets; MVB: multivesicular body; PAS: phagophore assembly site; Pep4: proteinase A; PolyP: polyphosphate; Prb1: proteinase B; Prc1: carboxypeptidase Y; V-ATPase: vacuolar-type proton-translocating ATPase; VTC: vacuolar transporter chaperone.
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Affiliation(s)
- Katherine R Parzych
- a Life Sciences Institute, and Department of Molecular, Cellular and Developmental Biology , University of Michigan , Ann Arbor , MI , USA
| | - Daniel J Klionsky
- a Life Sciences Institute, and Department of Molecular, Cellular and Developmental Biology , University of Michigan , Ann Arbor , MI , USA
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31
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Jurkiewicz P, Melser S, Maucourt M, Ayeb H, Veljanovski V, Maneta-Peyret L, Hooks M, Rolin D, Moreau P, Batoko H. The multistress-induced Translocator protein (TSPO) differentially modulates storage lipids metabolism in seeds and seedlings. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 96:274-286. [PMID: 30003614 DOI: 10.1111/tpj.14028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 06/28/2018] [Accepted: 07/03/2018] [Indexed: 05/11/2023]
Abstract
Translocator proteins (TSPO) are conserved membrane proteins extensively studied in mammals, but their function is still unclear. Angiosperm TSPO are transiently induced by abiotic stresses in vegetative tissues. We showed previously that constitutive expression of the Arabidopsis TSPO (AtTSPO) could be detrimental to the cell. Degradation of AtTSPO requires an active autophagy pathway. We show here that genetic modifications of TSPO expression in plant and yeast cells reduce the levels of cytoplasmic lipid droplets (LD). Transgenic Arabidopsis seedlings overexpressing AtTSPO contain less LD as compared with wild type (WT). LD levels were increased in Arabidopsis AtTSPO knockout (KO) seedlings. Deletion of the Schizosaccharomyces pombe TSPO resulted in an increase in LD level in the cell. As compared with the WT, the mutant strain was more sensitive to cerulenin, an inhibitor of fatty acids and sterol biosynthesis. We found that in contrast with seedlings, overexpression of AtTSPO (OE) resulted in an up to 50% increase in seeds fatty acids as compared with WT. A time course experiment revealed that after 4 days of seed imbibition, the levels of triacylglycerol (TAG) was still higher in the OE seeds as compared with WT or KO seeds. However, the de novo synthesis of phospholipids and TAG after 24 h of imbibition was substantially reduced in OE seeds as compared with WT or KO seeds. Our findings support a plant TSPO role in energy homeostasis in a tissue-specific manner, enhancing fatty acids and LD accumulation in mature seeds and limiting LD levels in seedlings.
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Affiliation(s)
- Pawel Jurkiewicz
- Louvain Institute of Biomolecular Science and Technology (LIBST), UCLouvain, Croix du Sud 4-5, L7.07.14, 1348, Louvain-la-Neuve, Belgium
| | - Su Melser
- UMR 5200 Membrane Biogenesis Laboratory, CNRS-University of Bordeaux, INRA Bordeaux Aquitaine, 33140, Villenave d'Ornon, France
| | - Mickaël Maucourt
- Plateforme Métabolome Bordeaux, MetaboHUB, Bordeaux Functional Genomic Center, IBVM, CS 20032 F-33140, Villenave d'Ornon, France
| | - Haitham Ayeb
- Louvain Institute of Biomolecular Science and Technology (LIBST), UCLouvain, Croix du Sud 4-5, L7.07.14, 1348, Louvain-la-Neuve, Belgium
| | - Vasko Veljanovski
- Louvain Institute of Biomolecular Science and Technology (LIBST), UCLouvain, Croix du Sud 4-5, L7.07.14, 1348, Louvain-la-Neuve, Belgium
| | - Lilly Maneta-Peyret
- UMR 5200 Membrane Biogenesis Laboratory, CNRS-University of Bordeaux, INRA Bordeaux Aquitaine, 33140, Villenave d'Ornon, France
| | - Mark Hooks
- Plateforme Métabolome Bordeaux, MetaboHUB, Bordeaux Functional Genomic Center, IBVM, CS 20032 F-33140, Villenave d'Ornon, France
| | - Dominique Rolin
- Plateforme Métabolome Bordeaux, MetaboHUB, Bordeaux Functional Genomic Center, IBVM, CS 20032 F-33140, Villenave d'Ornon, France
| | - Patrick Moreau
- UMR 5200 Membrane Biogenesis Laboratory, CNRS-University of Bordeaux, INRA Bordeaux Aquitaine, 33140, Villenave d'Ornon, France
- Bordeaux Imaging Center, UMS 3420 CNRS, US4 INSERM, University of Bordeaux, 33000, Bordeaux, France
| | - Henri Batoko
- Louvain Institute of Biomolecular Science and Technology (LIBST), UCLouvain, Croix du Sud 4-5, L7.07.14, 1348, Louvain-la-Neuve, Belgium
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Zhu X, Cai J, Zhou F, Wu Z, Li D, Li Y, Xie Z, Zhou Y, Liang Y. Genome-wide screening of budding yeast with honokiol to associate mitochondrial function with lipid metabolism. Traffic 2018; 19:867-878. [PMID: 30120820 DOI: 10.1111/tra.12611] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 08/11/2018] [Accepted: 08/13/2018] [Indexed: 12/24/2022]
Abstract
Honokiol (HNK), an important medicinal component of Magnolia officinalis, is reported to possess pharmacological activities against a variety of diseases. However, the molecular mechanisms of HNK medicinal functions are not fully clear. To systematically study the mechanisms of HNK action, we screened a yeast mutant library based on the conserved nature of its genes among eukaryotes. We identified genes associated with increased resistance or sensitivity to HNK after mutation. After functional classification of these genes, we found that most HNK-resistant strains in the largest functional category were petites with mutations in mitochondrial genes, indicating that mitochondria were related to HNK resistance. Additional analysis showed that resistance of petite mutants to HNK was associated with upregulation of the ATP-binding cassette transporter Pdr5, which pumps out HNK. We also found that several HNK-sensitive mitochondria mutants were not petites, and had larger lipid droplets (LDs). Furthermore, HNK treatment on wild-type yeast cells seemed to disrupt mitochondrial morphology, induced triacylglycerol synthesis, and generated supersized LDs surrounded by mitochondria and endoplasmic reticulum (ER). These changes are also applied to atp7Δ mutant if no carbon resource was available. These results suggested that HNK treatment partly impaired normal mitochondrial function to form larger LDs by altering lipid metabolism.
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Affiliation(s)
- Xiaolong Zhu
- College of Life Sciences, Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture and Rural Affairs, Nanjing Agricultural University, Nanjing, China.,Central Laboratory of Yijishan Hospital, Wannan Medical College, Wuhu, China
| | - Juan Cai
- College of Life Sciences, Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture and Rural Affairs, Nanjing Agricultural University, Nanjing, China
| | - Fan Zhou
- College of Life Sciences, Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture and Rural Affairs, Nanjing Agricultural University, Nanjing, China
| | - Zulin Wu
- College of Life Sciences, Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture and Rural Affairs, Nanjing Agricultural University, Nanjing, China
| | - Dan Li
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Technology, Shanghai Jiao Tong University, Shanghai, China
| | - Youbin Li
- School of Pharmacy, Hainan Medical University, Haikou, China
| | - Zhiping Xie
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Technology, Shanghai Jiao Tong University, Shanghai, China
| | - Yiting Zhou
- Department of Biochemistry and Molecular Biology, Dr. Li Dak Sam & Yap Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Hangzhou, 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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Nitrogen-starvation triggers cellular accumulation of triacylglycerol in Metarhizium robertsii. Fungal Biol 2018; 122:410-419. [DOI: 10.1016/j.funbio.2017.07.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/13/2017] [Accepted: 07/06/2017] [Indexed: 01/11/2023]
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34
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Priyadarshini L, Aggarwal A. Astaxanthin inhibits cytokines production and inflammatory gene expression by suppressing IκB kinase-dependent nuclear factor κB activation in pre and postpartum Murrah buffaloes during different seasons. Vet World 2018; 11:782-788. [PMID: 30034170 PMCID: PMC6048090 DOI: 10.14202/vetworld.2018.782-788] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 05/04/2018] [Indexed: 11/17/2022] Open
Abstract
AIM We examined regulatory function of astaxanthin on mRNA expression of nuclear factor κB (NF-κB) p65, interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ) in peripheral blood mononuclear cells in pre and postpartum Murrah buffaloes during summer (temperature-humidity index [THI]=86; relative humidity [RH]=24) and winter (THI=58.74; RH=73) seasons. MATERIALS AND METHODS A total of 32 Murrah buffaloes apparently healthy and in their one to four parity were selected from National Dairy Research Institute herd and equally distributed randomly into four groups (control and supplemented groups of buffaloes during summer and winter season, respectively). All groups were fed according to the nutrient requirement of buffaloes (ICAR, 2013). The treatment group was supplemented with astaxanthin at 0.25 mg/kg body weight/animal/day during the period 30 days before expected date of calving and up to 30 days postpartum. RESULTS There was downregulation of NF-κB p65 gene in all the groups. NF-κB p65 mRNA expression was lower (p<0.05) in treatment than control group from prepartum to postpartum during summer, while mRNA expression was low only on day 21 after calving during winter season. The mRNA expression of IL-6, TNF-α, and IFN-γ was lower (p<0.05) in treatment than a control group of buffaloes during summer and winter seasons. The mRNA expression of NFkB p65, IL-6, TNF-α, and IFN-γ was higher (p<0.05) in summer than in winter seasons. CONCLUSION The xanthophyll carotenoid astaxanthin a reddish-colored C-40 compound is a powerful broad-ranging antioxidant that naturally occurs in a wide variety of living organisms, such as microalgae, fungi, crustaceans, and complex plants. Astaxanthin blocked nuclear translocation of NF-κB p65 subunit and IκBα degradation, which correlated with its inhibitory effect on IκB kinase (IKK) activity. These results suggest that astaxanthin, probably due to its antioxidant activity, inhibits the production of inflammatory mediators by blocking NF-κB activation and as a consequent suppression of IKK activity and IκB-degradation.
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Affiliation(s)
- Lakshmi Priyadarshini
- Animal Physiology Division, ICAR-National Dairy Research Institute, Karnal - 132 001, Haryana, India
| | - Anjali Aggarwal
- Animal Physiology Division, ICAR-National Dairy Research Institute, Karnal - 132 001, Haryana, India
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Graef M. Lipid droplet-mediated lipid and protein homeostasis in budding yeast. FEBS Lett 2018; 592:1291-1303. [PMID: 29397034 PMCID: PMC5947121 DOI: 10.1002/1873-3468.12996] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 01/24/2018] [Accepted: 01/25/2018] [Indexed: 12/25/2022]
Abstract
Lipid droplets are conserved specialized organelles that store neutral lipids. Our view on this unique organelle has evolved from a simple fat deposit to a highly dynamic and functionally diverse hub—one that mediates the buffering of fatty acid stress and the adaptive reshaping of lipid metabolism to promote membrane and organelle homeostasis and the integrity of central proteostasis pathways, including autophagy, which ensure stress resistance and cell survival. This Review will summarize the recent developments in the budding yeast Saccharomyces cerevisiae, as this model organism has been instrumental in deciphering the fundamental mechanisms and principles of lipid droplet biology and interconnecting lipid droplets with many unanticipated cellular functions applicable to many other cell systems.
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Affiliation(s)
- Martin Graef
- Max Planck Institute for Biology of Ageing, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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DGAT1-Dependent Lipid Droplet Biogenesis Protects Mitochondrial Function during Starvation-Induced Autophagy. Dev Cell 2017; 42:9-21.e5. [PMID: 28697336 DOI: 10.1016/j.devcel.2017.06.003] [Citation(s) in RCA: 323] [Impact Index Per Article: 46.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 04/25/2017] [Accepted: 06/02/2017] [Indexed: 01/22/2023]
Abstract
Lipid droplets (LDs) provide an "on-demand" source of fatty acids (FAs) that can be mobilized in response to fluctuations in nutrient abundance. Surprisingly, the amount of LDs increases during prolonged periods of nutrient deprivation. Why cells store FAs in LDs during an energy crisis is unknown. Our data demonstrate that mTORC1-regulated autophagy is necessary and sufficient for starvation-induced LD biogenesis. The ER-resident diacylglycerol acyltransferase 1 (DGAT1) selectively channels autophagy-liberated FAs into new, clustered LDs that are in close proximity to mitochondria and are lipolytically degraded. However, LDs are not required for FA delivery to mitochondria but instead function to prevent acylcarnitine accumulation and lipotoxic dysregulation of mitochondria. Our data support a model in which LDs provide a lipid buffering system that sequesters FAs released during the autophagic degradation of membranous organelles, reducing lipotoxicity. These findings reveal an unrecognized aspect of the cellular adaptive response to starvation, mediated by LDs.
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Barbosa AD, Siniossoglou S. Function of lipid droplet-organelle interactions in lipid homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1459-1468. [DOI: 10.1016/j.bbamcr.2017.04.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/31/2017] [Accepted: 04/02/2017] [Indexed: 12/20/2022]
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Souza LDS, Simioni C, Bouzon ZL, Schneider RDCDS, Gressler P, Miotto MC, Rossi MJ, Rörig LR. Morphological and ultrastructural characterization of the acidophilic and lipid-producer strain Chlamydomonas acidophila LAFIC-004 (Chlorophyta) under different culture conditions. PROTOPLASMA 2017; 254:1385-1398. [PMID: 27696020 DOI: 10.1007/s00709-016-1030-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 09/20/2016] [Indexed: 05/18/2023]
Abstract
Chlamydomonas acidophila LAFIC-004 is an acidophilic strain of green microalgae isolated from coal mining drainage. In the present work, this strain was cultivated in acidic medium (pH 3.6) under phototrophic, mixotrophic, and heterotrophic regimes to determine the best condition for growth and lipid production, simultaneously assessing possible morphological and ultrastructural alterations in the cells. For heterotrophic and mixotrophic treatments, two organic carbon sources were tested: 1 % glucose and 1 % sodium acetate. Lipid content and fatty acid profiles were only determined in phototrophic condition. The higher growth rates were achieved in phototrophic conditions, varying from 0.18 to 0.82 day-1. Glucose did not result in significant growth increase in either mixotrophic or heterotrophic conditions, and acetate proved to be toxic to the strain in both conditions. Oil content under phototrophic condition was 15.9 % at exponential growth phase and increased to 54.63 % at stationary phase. Based on cell morphology (flow cytometry and light microscopy) and ultrastructure (transmission electron microscopy), similar characteristics were observed between phototrophic and mixotrophic conditions with glucose evidencing many lipid bodies, starch granules, and intense fluorescence. Under the tested conditions, mixotrophic and heterotrophic modes did not result in increased neutral lipid fluorescence. It can be concluded that the strain is a promising lipid producer when grown until stationary phase in acidic medium and under a phototrophic regime, presenting a fatty acid profile suitable for biodiesel production. The ability to grow this strain in acidic mining residues suggests a potential for bioremediation with production of useful biomass.
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Affiliation(s)
- Luana Dos S Souza
- Post Graduate Program in Biotechnology and Biosciences, Federal University of Santa Catarina, 88049-900, CP 476, Florianópolis, SC, Brazil.
| | - Carmen Simioni
- Postdoctoral Research of Post-Graduate Program in Cell Biology and Development, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, 88049-900, CP 476, Florianópolis, SC, Brazil
| | - Zenilda L Bouzon
- Central Laboratory of Electron Microscopy, Federal University of Santa Catarina, 88049-900, CP 476, Florianópolis, SC, Brazil
| | - Rosana de Cassia da S Schneider
- Department of Chemistry and Physics, Graduate Program in Environmental Technology, University of Santa Cruz do Sul, 96815-900, Santa Cruz do Sul, RS, Brazil
| | - Pablo Gressler
- Post Graduate Program in Biotechnology and Biosciences, Federal University of Santa Catarina, 88049-900, CP 476, Florianópolis, SC, Brazil
| | - Maria Cecília Miotto
- Post Graduate Program in Biotechnology and Biosciences, Federal University of Santa Catarina, 88049-900, CP 476, Florianópolis, SC, Brazil
| | - Marcio J Rossi
- Bioprocess Laboratory, Department of Microbiology and Parasitology, Federal University of Santa Catarina, 88049-900, CP 476, Florianópolis, SC, Brazil
| | - Leonardo R Rörig
- Phycology Laboratory, Botany Department, Federal University of Santa Catarina, 88049-900, CP 476, Florianópolis, SC, Brazil
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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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40
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Cristobal-Sarramian A, Radulovic M, Kohlwein S. Methods to Measure Lipophagy in Yeast. Methods Enzymol 2017; 588:395-412. [DOI: 10.1016/bs.mie.2016.09.087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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41
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Sinha RA, Singh BK, Zhou J, Xie S, Farah BL, Lesmana R, Ohba K, Tripathi M, Ghosh S, Hollenberg AN, Yen PM. Loss of ULK1 increases RPS6KB1-NCOR1 repression of NR1H/LXR-mediated Scd1 transcription and augments lipotoxicity in hepatic cells. Autophagy 2016; 13:169-186. [PMID: 27846372 PMCID: PMC5240836 DOI: 10.1080/15548627.2016.1235123] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Lipotoxicity caused by saturated fatty acids (SFAs) induces tissue damage and inflammation in metabolic disorders. SCD1 (stearoyl-coenzyme A desaturase 1) converts SFAs to mono-unsaturated fatty acids (MUFAs) that are incorporated into triglycerides and stored in lipid droplets. SCD1 thus helps protect hepatocytes from lipotoxicity and its reduced expression is associated with increased lipotoxic injury in cultured hepatic cells and mouse models. To further understand the role of SCD1 in lipotoxicity, we examined the regulation of Scd1 in hepatic cells treated with palmitate, and found that NR1H/LXR (nuclear receptor subfamily 1 group H) ligand, GW3965, induced Scd1 expression and lipid droplet formation to improve cell survival. Surprisingly, ULK1/ATG1 (unc-51 like kinase) played a critical role in protecting hepatic cells from SFA-induced lipotoxicity via a novel mechanism that did not involve macroautophagy/autophagy. Specific loss of Ulk1 blocked the induction of Scd1 gene transcription by GW3965, decreased lipid droplet formation, and increased apoptosis in hepatic cells exposed to palmitate. Knockdown of ULK1 increased RPS6KB1 (ribosomal protein S6 kinase, polypeptide 1) signaling that, in turn, induced NCOR1 (nuclear receptor co-repressor 1) nuclear uptake, interaction with NR1H/LXR, and recruitment to the Scd1 promoter. These events abrogated the stimulation of Scd1 gene expression by GW3965, and increased lipotoxicity in hepatic cells. In summary, we have identified a novel autophagy-independent role of ULK1 that regulates NR1H/LXR signaling, Scd1 expression, and intracellular lipid homeostasis in hepatic cells exposed to a lipotoxic environment.
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Affiliation(s)
- Rohit Anthony Sinha
- a Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School , Singapore
| | - Brijesh K Singh
- a Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School , Singapore
| | - Jin Zhou
- a Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School , Singapore
| | - Sherwin Xie
- a Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School , Singapore
| | - Benjamin L Farah
- a Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School , Singapore
| | - Ronny Lesmana
- a Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School , Singapore.,b Department of Physiology , Universitas Padjadjaran , Bandung , Indonesia
| | - Kenji Ohba
- a Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School , Singapore
| | - Madhulika Tripathi
- c Stroke Trial Unit, National Neuroscience Institute Singapore , Singapore
| | - Sujoy Ghosh
- a Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School , Singapore
| | - Anthony N Hollenberg
- d Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School , Boston , MA USA
| | - Paul M Yen
- a Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School , Singapore
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Shatz O, Holland P, Elazar Z, Simonsen A. Complex Relations Between Phospholipids, Autophagy, and Neutral Lipids. Trends Biochem Sci 2016; 41:907-923. [PMID: 27595473 DOI: 10.1016/j.tibs.2016.08.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/28/2016] [Accepted: 08/01/2016] [Indexed: 11/27/2022]
Abstract
Research in the past decade has established the importance of autophagy to a large number of physiological processes and pathophysiological conditions. Originally characterized as a pathway responsible for protein turnover and recycling of amino acids in times of starvation, it has been recently recognized as a major regulator of lipid metabolism. Different lipid species play various roles in the regulation of autophagosomal biogenesis, both as membrane constituents and as signaling platforms. Distinct types of autophagy, in turn, facilitate specific steps in metabolic pathways of different lipid classes, best exemplified in recent studies on neutral lipid dynamics. We review the emerging notion of intricate links between phospholipids, autophagy, and neutral lipids.
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Affiliation(s)
- Oren Shatz
- Department of Biomolecular Sciences, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Petter Holland
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
| | - Zvulun Elazar
- Department of Biomolecular Sciences, Weizmann Institute of Science, 76100 Rehovot, Israel.
| | - Anne Simonsen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway.
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43
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Régnacq M, Voisin P, Sere YY, Wan B, Soeroso VM, Bernard M, Camougrand N, Bernard FX, Barrault C, Bergès T. Increased fatty acid synthesis inhibits nitrogen starvation-induced autophagy in lipid droplet-deficient yeast. Biochem Biophys Res Commun 2016; 477:33-39. [DOI: 10.1016/j.bbrc.2016.06.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 06/03/2016] [Indexed: 12/13/2022]
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44
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Short B. Survival of the fattest. J Biophys Biochem Cytol 2016. [DOI: 10.1083/jcb.2126if] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lipid droplets regulate autophagy and cell survival by maintaining ER function in starving cells.
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45
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Velázquez AP, Tatsuta T, Ghillebert R, Drescher I, Graef M. Lipid droplet-mediated ER homeostasis regulates autophagy and cell survival during starvation. J Cell Biol 2016; 212:621-31. [PMID: 26953354 PMCID: PMC4792078 DOI: 10.1083/jcb.201508102] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 02/10/2016] [Indexed: 12/14/2022] Open
Abstract
Biochemical, cytological, and lipidomic approaches show that lipid droplets are dispensable as membrane sources for autophagy, but are required for ER homeostasis by buffering fatty acid synthesis and ER stress and maintaining phospholipid composition to allow autophagy regulation and autophagosome biogenesis. Lipid droplets (LDs) are conserved organelles for intracellular neutral lipid storage. Recent studies suggest that LDs function as direct lipid sources for autophagy, a central catabolic process in homeostasis and stress response. Here, we demonstrate that LDs are dispensable as a membrane source for autophagy, but fulfill critical functions for endoplasmic reticulum (ER) homeostasis linked to autophagy regulation. In the absence of LDs, yeast cells display alterations in their phospholipid composition and fail to buffer de novo fatty acid (FA) synthesis causing chronic stress and morphologic changes in the ER. These defects compromise regulation of autophagy, including formation of multiple aberrant Atg8 puncta and drastically impaired autophagosome biogenesis, leading to severe defects in nutrient stress survival. Importantly, metabolically corrected phospholipid composition and improved FA resistance of LD-deficient cells cure autophagy and cell survival. Together, our findings provide novel insight into the complex interrelation between LD-mediated lipid homeostasis and the regulation of autophagy potentially relevant for neurodegenerative and metabolic diseases.
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Affiliation(s)
| | - Takashi Tatsuta
- Institute for Genetics, University of Cologne, 50931 Cologne, Germany Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, 50931 Cologne, Germany
| | - Ruben Ghillebert
- Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Ingmar Drescher
- Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Martin Graef
- Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, 50931 Cologne, Germany
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46
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Production of Palmitoleic and Linoleic Acid in Oleaginous and Nonoleaginous Yeast Biomass. Int J Anal Chem 2016; 2016:7583684. [PMID: 27022398 PMCID: PMC4789058 DOI: 10.1155/2016/7583684] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 01/25/2016] [Accepted: 02/01/2016] [Indexed: 11/23/2022] Open
Abstract
We investigated the possibility of utilizing both oleaginous yeast species accumulating large amounts of lipids (Yarrowia lipolytica, Rhodotorula glutinis, Trichosporon cutaneum, and Candida sp.) and traditional biotechnological nonoleaginous ones (Kluyveromyces polysporus, Torulaspora delbrueckii, and Saccharomyces cerevisiae) as potential producers of dietetically important major fatty acids. The main objective was to examine the cultivation conditions that would induce a high ratio of dietary fatty acids and biomass. Though genus-dependent, the type of nitrogen source had a higher influence on biomass yield than the C/N ratio. The nitrogen source leading to the highest lipid accumulation was potassium nitrate, followed by ammonium sulfate, which is an ideal nitrogen source supporting, in both oleaginous and nonoleaginous species, sufficient biomass growth with concomitantly increased lipid accumulation. All yeast strains displayed high (70–90%) content of unsaturated fatty acids in total cell lipids. The content of dietary fatty acids of interest, namely, palmitoleic acid and linoleic acid, reached in Kluyveromyces and Trichosporon strains over 50% of total fatty acids and the highest yield, over 280 mg per g of dry cell weight of these fatty acids, was observed in Trichosporon with ammonium sulfate as nitrogen source at C/N ratio 70.
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47
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Gao Q, Goodman JM. The lipid droplet-a well-connected organelle. Front Cell Dev Biol 2015; 3:49. [PMID: 26322308 PMCID: PMC4533013 DOI: 10.3389/fcell.2015.00049] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 07/24/2015] [Indexed: 12/19/2022] Open
Abstract
Our knowledge of inter-organellar communication has grown exponentially in recent years. This review focuses on the interactions that cytoplasmic lipid droplets have with other organelles. Twenty-five years ago droplets were considered simply particles of coalesced fat. Ten years ago there were hints from proteomics studies that droplets might interact with other structures to share lipids and proteins. Now it is clear that the droplets interact with many if not most cellular structures to maintain cellular homeostasis and to buffer against insults such as starvation. The evidence for this statement, as well as probes to understand the nature and results of droplet interactions, are presented.
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Affiliation(s)
- Qiang Gao
- Department of Pharmacology, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Joel M Goodman
- Department of Pharmacology, University of Texas Southwestern Medical Center Dallas, TX, USA
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Moldavski O, Amen T, Levin-Zaidman S, Eisenstein M, Rogachev I, Brandis A, Kaganovich D, Schuldiner M. Lipid Droplets Are Essential for Efficient Clearance of Cytosolic Inclusion Bodies. Dev Cell 2015; 33:603-10. [PMID: 26004510 DOI: 10.1016/j.devcel.2015.04.015] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 02/17/2015] [Accepted: 04/21/2015] [Indexed: 11/24/2022]
Abstract
Exposing cells to folding stress causes a subset of their proteins to misfold and accumulate in inclusion bodies (IBs). IB formation and clearance are both active processes, but little is known about their mechanism. To shed light on this issue, we performed a screen with over 4,000 fluorescently tagged yeast proteins for co-localization with a model misfolded protein that marks IBs during folding stress. We identified 13 proteins that co-localize to IBs. Remarkably, one of these IB proteins, the uncharacterized and conserved protein Iml2, exhibited strong physical interactions with lipid droplet (LD) proteins. Indeed, we here show that IBs and LDs are spatially and functionally linked. We further demonstrate a mechanism for IB clearance via a sterol-based metabolite emanating from LDs. Our findings therefore uncover a function for Iml2 and LDs in regulating a critical stage of cellular proteostasis.
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Affiliation(s)
- Ofer Moldavski
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Triana Amen
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Smadar Levin-Zaidman
- Electron Microscopy Unit, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Miriam Eisenstein
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ilana Rogachev
- Department for Biological Services, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Alexander Brandis
- Department for Biological Services, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Daniel Kaganovich
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
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49
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Barbosa AD, Savage DB, Siniossoglou S. Lipid droplet-organelle interactions: emerging roles in lipid metabolism. Curr Opin Cell Biol 2015; 35:91-7. [PMID: 25988547 DOI: 10.1016/j.ceb.2015.04.017] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 04/27/2015] [Accepted: 04/28/2015] [Indexed: 01/02/2023]
Abstract
Cellular homeostasis depends on the precisely coordinated use of lipids as fuels for energy production, building blocks for membrane biogenesis or chemical signals for intra-cellular and inter-cellular communication. Lipid droplets (LDs) are universally conserved dynamic organelles that can store and mobilize fatty acids and other lipid species for their multiple cellular roles. Increasing evidence suggests that contact zones between LDs and other organelles play important roles in the trafficking of lipids and in the regulation of lipid metabolism. Here we review recent advances regarding the nature and functional relevance of interactions between LDs and other organelles-particularly the endoplasmic reticulum (ER), LDs, mitochondria and vacuoles-that highlight their importance for lipid metabolism.
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Affiliation(s)
- Antonio Daniel Barbosa
- Cambridge Institute for Medical Research, University of Cambridge, CB2 0XY Cambridge, United Kingdom
| | - David B Savage
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Cambridge CB2 0QQ, United Kingdom
| | - Symeon Siniossoglou
- Cambridge Institute for Medical Research, University of Cambridge, CB2 0XY Cambridge, United Kingdom.
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