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Tang J, Robichaux MA, Wu KL, Pei J, Nguyen NT, Zhou Y, Wensel TG, Xiao H. Single-Atom Fluorescence Switch: A General Approach toward Visible-Light-Activated Dyes for Biological Imaging. J Am Chem Soc 2019; 141:14699-14706. [PMID: 31450884 DOI: 10.1021/jacs.9b06237] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Photoactivatable fluorophores afford powerful molecular tools to improve the spatial and temporal resolution of subcellular structures and dynamics. By performing a single sulfur-for-oxygen atom replacement within common fluorophores, we have developed a facile and general strategy to obtain photoactivatable fluorogenic dyes across a broad spectral range. Thiocarbonyl substitution within fluorophores results in significant loss of fluorescence via a photoinduced electron transfer-quenching mechanism as suggested by theoretical calculations. Significantly, upon exposure to air and visible light residing in their absorption regime (365-630 nm), thio-caged fluorophores can be efficiently desulfurized to their oxo derivatives, thus restoring strong emission of the fluorophores. The effective photoactivation makes thio-caged fluorophores promising candidates for super-resolution imaging, which was realized by photoactivated localization microscopy (PALM) with low-power activation light under physiological conditions in the absence of cytotoxic additives (e.g., thiols, oxygen scavengers), a feature superior to traditional PALM probes. The versatility of this thio-caging strategy was further demonstrated by multicolor super-resolution imaging of lipid droplets and proteins of interest.
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Affiliation(s)
| | - Michael A Robichaux
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology , Baylor College of Medicine , Houston , Texas 77030 , United States
| | | | | | - Nhung T Nguyen
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine , Texas A&M University , Houston , Texas 77030 , United States
| | - Yubin Zhou
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine , Texas A&M University , Houston , Texas 77030 , United States
| | - Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology , Baylor College of Medicine , Houston , Texas 77030 , United States
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Abstract
Significance: Alterations in adipose tissue function have profound consequences on whole body energy homeostasis because this tissue is central for fat accumulation, energy expenditure, glucose and insulin metabolism, and hormonal regulation. With the obesity reaching epidemic proportions globally, it is important to understand the mechanisms leading to adipose tissue malfunction. Recent Advances: Autophagy has originally been viewed as an adaptive response to cellular stress, but in recent years this process was shown to regulate important cellular processes. In adipose tissue, autophagy is a key regulator of white adipose tissue (WAT) and brown adipose tissue (BAT) adipogenesis, and dysregulated autophagy impairs fat accumulation both in vitro and in vivo. Animal studies have also suggested an important role for autophagy and mitophagy during the transition from beige to white fat. Human studies have provided evidence for altered autophagy in WAT, and these alterations correlated with the degree of insulin resistance. Critical Issues: Despite these important advances in the study of autophagy in adipose tissue, we still do not understand the physiological role of autophagy in mature white and brown adipocytes. Furthermore, several human studies involving autophagy assessment were performed on whole adipose tissue, which complicates the interpretation of the results considering the cellular heterogeneity of this tissue. Future Directions: Future studies will undoubtedly expand our understanding of the role of autophagy in fully differentiated adipocytes, and uncover novel cross-talks between this tissue and other organs in regulating lipid metabolism, redox signaling, energy homeostasis, and insulin sensitivity.
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Affiliation(s)
- Maroua Ferhat
- Program in Molecular Medicine, Department of Nutrition and Integrative Physiology, College of Health, University of Utah, Salt Lake City, Utah
| | - Katsuhiko Funai
- Program in Molecular Medicine, Department of Nutrition and Integrative Physiology, College of Health, University of Utah, Salt Lake City, Utah
| | - Sihem Boudina
- Program in Molecular Medicine, Department of Nutrition and Integrative Physiology, College of Health, University of Utah, Salt Lake City, Utah
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103
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Harsh S, Heryanto C, Eleftherianos I. Intestinal lipid droplets as novel mediators of host-pathogen interaction in Drosophila. Biol Open 2019; 8:bio.039040. [PMID: 31278163 PMCID: PMC6679391 DOI: 10.1242/bio.039040] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Lipid droplets (LDs) are lipid-carrying multifunctional organelles, which might also interact with pathogens and influence the host immune response. However, the exact nature of these interactions remains currently unexplored. Here we show that systemic infection of Drosophila adult flies with non-pathogenic Escherichia coli, the extracellular bacterial pathogen Photorhabdus luminescens or the facultative intracellular pathogen Photorhabdus asymbiotica results in intestinal steatosis marked by lipid accumulation in the midgut. Accumulation of LDs in the midgut also correlates with increased whole-body lipid levels characterized by increased expression of genes regulating lipogenesis. The lipid-enriched midgut further displays reduced expression of the enteroendocrine-secreted hormone, Tachykinin. The observed lipid accumulation requires the Gram-negative cell wall pattern recognition molecule, PGRP-LC, but not PGRP-LE, for the humoral immune response. Altogether, our findings indicate that Drosophila LDs are inducible organelles, which can serve as markers for inflammation and, depending on the nature of the challenge, they can dictate the outcome of the infection. Summary: Lipid droplets are inducible organelles, act as inflammatory markers and, depending on the nature of challenge, can dictate the outcome of the infection.
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Affiliation(s)
- Sneh Harsh
- Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, Washington DC 20052, USA
| | - Christa Heryanto
- Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, Washington DC 20052, USA
| | - Ioannis Eleftherianos
- Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, Washington DC 20052, USA
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104
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Milon A, Kaczmarczyk M, Pawlicki P, Bilinska B, Duliban M, Gorowska-Wojtowicz E, Tworzydlo W, Kotula-Balak M. Do estrogens regulate lipid status in testicular steroidogenic Leydig cell? Acta Histochem 2019; 121:611-618. [PMID: 31126612 DOI: 10.1016/j.acthis.2019.04.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/26/2019] [Accepted: 04/26/2019] [Indexed: 12/24/2022]
Abstract
In this study mouse Leydig cell (MA-10) were treated with G-protein coupled membrane estrogen receptor antagonist (G-15; 10 nM). Cells were analyzed by Western blotting for expression of estrogen-related receptors (ERRα, β and γ), steroidogenic markers (lutropin receptor; LHR and 3β-hydroxysteroid dehydrogenase; 3β-HSD) and lipid droplet markers (perilipin; PLIN and microtubule-associated protein 1 A/1B-light chain 3; LC3). Concomitantly, microscopic analyses by light microscope (immunofluorescent staining for lipid droplets, PLIN and LC3) as well as by electron microscope (for lipid droplet ultrastructure) were utilized. For analysis of cholesterol content, cAMP level and progesterone secretion, G-15, estrogen receptor (ER) antagonist (ICI 182,780; 10 μM), 17β-estradiol (10 mM) and, bisphenol A (BPA; 10 nM) were used alone or in combinations. We revealed no changes in ERRs expression but alterations in ERRβ and γ localization in G-15-treated cells when compared to control. Partial translocation of ERRβ and γ from the cell nucleus to cytoplasm was observed. Decreased expression of LHR, 3β-HSD, PLIN and LC3 was detected. Moreover, in treated cells large lipid droplets and differences in their distribution were found. Very strong signal of co-localization for PLIN and LC3 was found in treated cells when compared to control. In ultrastructure of treated cells, degenerating lipid droplets and double membrane indicating on presence of lipophagosome were observed. We found, that only (i) BPA and G-15 did not effect on cholesterol content, (ii) BPA, G-15 and ICI did not effect on cAMP level and (iii) BPA, ICI alone and in combination, and BPA with G-15 did not modulate progesterone secretion. These findings showed complex and diverse estrogen effects on mouse Leydig cells at various steps of steroid hormone production (cholesterol storage, release and processing). Lipid homeostasis and metabolism in these cells were affected by endogenous and exogenous estrogen, interactions of receptors (GPER, ER and ERR) and GPER and ER antagonists.
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Affiliation(s)
- A Milon
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - M Kaczmarczyk
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - P Pawlicki
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - B Bilinska
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - M Duliban
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - E Gorowska-Wojtowicz
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - W Tworzydlo
- Department of Developmental Biology and Invertebrate Morphology Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - M Kotula-Balak
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland.
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105
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Utilization of Clarified Butter Sediment Waste as a Feedstock for Cost-Effective Production of Biodiesel. Foods 2019; 8:foods8070234. [PMID: 31261933 PMCID: PMC6678320 DOI: 10.3390/foods8070234] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 06/27/2019] [Accepted: 06/28/2019] [Indexed: 02/06/2023] Open
Abstract
The rising demand and cost of fossil fuels (diesel and gasoline), together with the need for sustainable, alternative, and renewable energy sources have increased the interest for biomass-based fuels such as biodiesel. Among renewable sources of biofuels, biodiesel is particularly attractive as it can be used in conventional diesel engines without any modification. Oleaginous yeasts are excellent oil producers that can grow easily on various types of hydrophilic and hydrophobic waste streams that are used as feedstock for single cell oils and subsequently biodiesel production. In this study, cultivation of Rhodosporidium kratochvilovae on a hydrophobic waste (clarified butter sediment waste medium (CBM)) resulted in considerably high lipid accumulation (70.74% w/w). Maximum cell dry weight and total lipid production were 15.52 g/L and 10.98 g/L, respectively, following cultivation in CBM for 144 h. Neutral lipids were found to accumulate in the lipid bodies of cells, as visualized by BODIPY staining and fluorescence microscopy. Cells grown in CBM showed large and dispersed lipid droplets in the intracellular compartment. The fatty acid profile of biodiesel obtained after transesterification was analyzed by gas chromatography-mass spectrometry (GC–MS), while its quality was determined to comply with ASTM 6751 and EN 14214 international standards. Hence, clarified sediment waste can be exploited as a cost-effective renewable feedstock for biodiesel production.
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106
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Ashoka AH, Ashokkumar P, Kovtun YP, Klymchenko AS. Solvatochromic Near-Infrared Probe for Polarity Mapping of Biomembranes and Lipid Droplets in Cells under Stress. J Phys Chem Lett 2019; 10:2414-2421. [PMID: 31021640 DOI: 10.1021/acs.jpclett.9b00668] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Can polarity-sensitive fluorescent dyes monitor the response of live cells to fundamental stress conditions, such as deprivation from nutrition and oxidative stress? To address this question, we developed a push-pull dioxaborine probe (DXB-NIR) for biomembranes and lipid droplets featuring strong solvatochromism in the far-red to near-infrared region, high fluorescence brightness, photostability, and two-photon absorption cross section, reaching 13800 GM at 930 nm. In model membranes, DXB-NIR exhibits unprecedented 80 nm shift between liquid ordered and disordered membrane phases, allowing robust imaging of separated membrane microdomains. Two-color imaging of live cells with DXB-NIR enables polarity mapping in plasma membranes, endoplasmic reticulum, and lipid droplets, which reveals that starvation and oxidative stress produce an increase in the local polarity, and this change is different for each of the studied cell compartments. Thus, by pushing the limits of existing solvatochromic dyes, we introduce a concept of polarity mapping for monitoring the response of cells to stress.
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Affiliation(s)
- Anila Hoskere Ashoka
- Laboratoire de Bioimagerie et Pathologies , UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg , Strasbourg , CS 60024 , France
| | - Pichandi Ashokkumar
- Laboratoire de Bioimagerie et Pathologies , UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg , Strasbourg , CS 60024 , France
| | - Yuriy P Kovtun
- Institute of Organic Chemistry , National Academy of Sciences of Ukraine , 5 Murmanska Street , 02094 Kyiv , Ukraine
| | - Andrey S Klymchenko
- Laboratoire de Bioimagerie et Pathologies , UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg , Strasbourg , CS 60024 , France
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107
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Pandey V, Hatzimanikatis V. Investigating the deregulation of metabolic tasks via Minimum Network Enrichment Analysis (MiNEA) as applied to nonalcoholic fatty liver disease using mouse and human omics data. PLoS Comput Biol 2019; 15:e1006760. [PMID: 31002661 PMCID: PMC6493771 DOI: 10.1371/journal.pcbi.1006760] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 05/01/2019] [Accepted: 01/06/2019] [Indexed: 01/07/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is associated with metabolic syndromes spanning a wide spectrum of diseases, from simple steatosis to the more complex nonalcoholic steatohepatitis. To identify the deregulation that occurs in metabolic processes at the molecular level that give rise to these various NAFLD phenotypes, algorithms such as pathway enrichment analysis (PEA) can be used. These analyses require the use of predefined pathway maps, which are composed of reactions describing metabolic processes/subsystems. Unfortunately, the annotation of the metabolic subsystems can differ depending on the pathway database used, making these approaches subject to biases associated with different pathway annotations, and these methods cannot capture the balancing of cofactors and byproducts through the complex nature and interactions of genome-scale metabolic networks (GEMs). Here, we introduce a framework entitled Minimum Network Enrichment Analysis (MiNEA) that is applied to GEMs to generate all possible alternative minimal networks (MiNs), which are possible and feasible networks composed of all the reactions pertaining to various metabolic subsystems that can synthesize a target metabolite. We applied MiNEA to investigate deregulated MiNs and to identify key regulators in different NAFLD phenotypes, such as a fatty liver and liver inflammation, in both humans and mice by integrating condition-specific transcriptomics data from liver samples. We identified key deregulations in the synthesis of cholesteryl esters, cholesterol, and hexadecanoate in both humans and mice, and we found that key regulators of the hydrogen peroxide synthesis network were regulated differently in humans and mice. We further identified which MiNs demonstrate the general and specific characteristics of the different NAFLD phenotypes. MiNEA is applicable to any GEM and to any desired target metabolite, making MiNEA flexible enough to study condition-specific metabolism for any given disease or organism. This work aims to introduce a network-based enrichment analysis using metabolic networks and transcriptomics data. Previous pathways/subsystems enrichment methods use predefined gene annotations of metabolic processes and gene annotations can differ based on different resources and can produce bias in pathway definitions. Thus, we introduce a framework, Minimum Network Enrichment Analysis (MiNEA), which first finds all possible minimal-size networks for a given metabolic process/task and then identifies deregulated minimal networks using deregulated genes between two conditions. MiNEA also identifies the deregulation in key reactions that are overlapped across all possible minimal-size networks. We applied MiNEA to identify deregulated metabolic tasks and their synthesis networks in the steatosis and the nonalcoholic steatohepatitis (NASH) diseases using a metabolic network and transcriptomics data of mouse and human liver samples. We identified key regulators of NASH for the synthesis networks of hydrogen peroxide and ceramide in both humans and mice. We also identified opposite deregulation in NASH for the phosphatidylserine synthesis network between humans and mice. MiNEA finds synthesis networks for a given target metabolite and due to this it is flexible to study deregulation in different phenotypes. MiNEA can be widely applicable for studying context-specific metabolism for any organism because the metabolic networks and context-specific gene expression data are now available for many organisms.
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Affiliation(s)
- Vikash Pandey
- Laboratory of Computational Systems Biotechnology, EPFL, Lausanne, Switzerland
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108
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Brettschneider J, Correnti JM, Lin C, Williams B, Oranu A, Kuriakose A, McIver-Jenkins D, Haba A, Kaneza I, Jeon S, Scorletti E, Carr RM. Rapid Lipid Droplet Isolation Protocol Using a Well-established Organelle Isolation Kit. J Vis Exp 2019. [PMID: 31058903 DOI: 10.3791/59290] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Lipid droplets (LDs) are bioactive organelles found within the cytosol of the most eukaryotic and some prokaryotic cells. LDs are composed of neutral lipids encased by a monolayer of phospholipids and proteins. Hepatic LD lipids, such as ceramides, and proteins are implicated in several diseases that cause hepatic steatosis. Although previous methods have been established for LD isolation, they require a time-consuming preparation of reagents and are not designed for the isolation of multiple subcellular compartments. We sought to establish a new protocol to enable the isolation of LDs, endoplasmic reticulum (ER), and lysosomes from a single mouse liver. Further, all reagents used in the protocol presented here are commercially available and require minimal reagent preparation without sacrificing LD purity. Here we present data comparing this new protocol to a standard sucrose gradient protocol, demonstrating comparable purity, morphology, and yield. Additionally, we can isolate ER and lysosomes using the same sample, providing detailed insight into the formation and intracellular flux of lipids and their associated proteins.
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Affiliation(s)
- Jascha Brettschneider
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Jason M Correnti
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Chelsea Lin
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Bianca Williams
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Amanke Oranu
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Amy Kuriakose
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Dru McIver-Jenkins
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Abigail Haba
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Isabelle Kaneza
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Sookyoung Jeon
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Eleonora Scorletti
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania
| | - Rotonya M Carr
- Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania;
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109
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Shah M, Bharadwaj MSK, Gupta A, Kumar R, Kumar S. Chicken viperin inhibits Newcastle disease virus infection in vitro: A possible interaction with the viral matrix protein. Cytokine 2019; 120:28-40. [PMID: 31003187 DOI: 10.1016/j.cyto.2019.04.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 03/28/2019] [Accepted: 04/12/2019] [Indexed: 02/06/2023]
Abstract
Viperin is an interferon-inducible protein that helps in protecting mammals against various virus infections. Viperin is a highly conserved member of the interferon-stimulated genes (ISG) family in many species. Viperin has been shown to play a pivotal role in the innate immunity of chicken; however, its role has not been explored in its antiviral potential. Newcastle disease virus (NDV) is the causative agent of an infectious disease in poultry. In the present study, we have shown the anti-NDV effect of chicken viperin (cViperin). The impact of cViperin upon NDV infection was investigated in chicken embryo fibroblast. The modeling of the cViperin protein was done using I-TASSER and ZDOCK is used to predict the possible interaction with the matrix protein of NDV. The interaction was further confirmed by co-immunoprecipitation assay using recombinant matrix protein of NDV with the recombinant cViperin. The recombinant NDV expressing cViperin showed reduced replication of the virus upon its growth kinetics. Our results suggest downregulation of NDV replication in the presence of cViperin. The study will be critical to elaborate our understanding of the chicken innate immune system which could help develop antiviral strategies against NDV infection.
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Affiliation(s)
- Manisha Shah
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - M S K Bharadwaj
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Anjali Gupta
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Rakesh Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Sachin Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
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110
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Patel A, Matsakas L. A comparative study on de novo and ex novo lipid fermentation by oleaginous yeast using glucose and sonicated waste cooking oil. ULTRASONICS SONOCHEMISTRY 2019; 52:364-374. [PMID: 30559080 DOI: 10.1016/j.ultsonch.2018.12.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/04/2018] [Accepted: 12/07/2018] [Indexed: 05/23/2023]
Abstract
There are only a few reports available about the assimilation of hydrophobic substrates by microorganisms, however, it is well known that oleaginous microorganisms are capable of utilizing both hydrophilic and hydrophobic substrates and accumulate lipids via two different pathways namely de novo and ex novo lipid synthesis, respectively. In the present study, an oleaginous yeast, Cryptococcus curvatus, was investigated for its potentials to utilize a waste substrate of hydrophobic nature (waste cooking oil - WCO) and compared with its ability to utilize a hydrophilic carbon source (glucose). To facilitate the utilization of WCO by C. curvatus, the broth was sonicated to form a stable oil-in-water emulsion without adding any emulsifier, which was then compared with WCO samples without any ultrasound treatment (unsonicated) for the yeast cultivation. Ultrasonication reduces the size of hydrophobic substrates and improves their miscibility in an aqueous broth making them easily assimilated by oleaginous yeast. Under de novo lipid fermentation, the yeast synthesized 9.93 ± 0.84 g/L of cell dry weight and 5.23 ± 0.49 g/L lipids (lipid content of 52.66 ± 0.93% w/w) when cultivated on 40 g/L of glucose (C/N ratio of 40). The amount of cell dry weight, lipid concentration, and lipid content were considerably higher during the ex novo lipid synthesis. More specifically, the highest lipid content achieved was 70.13 ± 1.65% w/w with a corresponding dry cell weight and lipid concentration of 18.62 ± 0.76 g/L and 13.06 ± 0.92 g/L respectively, when grown on 20 g/L sonicated WCO. The highest lipid concentration, however, was observed when the yeast was cultivated on 40 g/L sonicated WCO. Under these conditions, 20.34 g/L lipids were produced with a lipid content of 57.05% w/w. On the other hand, lipid production with unsonicated WCO was significant lower, reaching 11.16 ± 1.02 g/L (69.14 ± 1.34% w/w of lipid content) and 12.21 ± 1.34 g/L (47.39 ± 1.67% w/w of lipid content) for 20 g/L and 40 g/L of WCO, respectively. This underpins the significance of the sonication treatment, especially at elevated WCO concentrations, to improve the accessibility of the yeast to the WCO. Sonication treatment that was used in this study assisted the utilization of WCO without the need to add emulsifiers, thus reducing the need for chemicals and in turn has a positive impact on the production costs. The microbial lipids produced presented a different fatty acid composition compared to the WCO, making them more suitable for biodiesel production as suggested by the theoretical estimation of the biodiesel properties.
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Affiliation(s)
- Alok Patel
- Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental, and Natural Resources Engineering, Luleå University of Technology, SE-971 87 Luleå, Sweden
| | - Leonidas Matsakas
- Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental, and Natural Resources Engineering, Luleå University of Technology, SE-971 87 Luleå, Sweden.
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111
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Boschi F, Rizzatti V, Zoico E, Montanari T, Zamboni M, Sbarbati A, Colitti M. Relationship between lipid droplets size and integrated optical density. Eur J Histochem 2019; 63. [PMID: 30907383 PMCID: PMC6444373 DOI: 10.4081/ejh.2019.3017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 03/09/2019] [Indexed: 12/19/2022] Open
Abstract
Lipid accumulation is largely investigated due to its role in many human diseases. The attention is mainly focused on the lipid droplets (LDs), spherical cytoplasmic organelles which are devoted to the storage of the lipids. The amount of lipid content is often evaluated by measuring LDs size and/or the integrated optical density (IOD) in cultured cells. Both evaluations are directly associated to the lipid content and therefore they are correlated to each other, but a lack of theoretical relationship between size and IOD was observed in literature. Here we investigated the size-IOD relationship of LDs observed in microscopical images of cultured cells. The experimental data were obtained from immature and differentiated 3T3-L1 murine cells, which have been extensively used in studies on adipogenesis. A simple model based on the spherical shape of the LDs and the Lambert-Beer law, which describes the light absorption by an optical thick material, leads to a mathematical relationship. Despite only light rays’ absorption was considered in the model, neglecting their scattering, a very good agreement between the theoretical curve and the experimental data was found. Moreover, a computational simulation corroborates the model indicating the validity of the mathematically theoretical relationship between size and IOD. The theoretical model could be used to calculate the absorption coefficient in the LDs population and it could be applied to seek for morphologically and functionally LDs subpopulations. The identification of LDs dynamic by measuring size and IOD could be related to different pathophysiological conditions and useful for understand cellular lipid-associated diseases.
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112
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Zhao Y, Chen Z, Wu Y, Tsukui T, Ma X, Zhang X, Chiba H, Hui SP. Separating and Profiling Phosphatidylcholines and Triglycerides from Single Cellular Lipid Droplet by In-Tip Solvent Microextraction Mass Spectrometry. Anal Chem 2019; 91:4466-4471. [PMID: 30773008 DOI: 10.1021/acs.analchem.8b05122] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The analysis of lipid droplets (LDs) by mass spectrometry at the single LD level is still an analytical challenge. In this work, we developed a novel technique termed in-tip solvent microextraction mass spectrometry for the separation and profiling of phosphatidylcholines and triglycerides within a single LD. This method has been successfully used to analyze LDs in mammalian cells and to compare the profiles of triglycerides and phosphatidylcholines in LDs induced at different conditions. Our method has the potential to be applied to such fields as fundamental lipid biology to further our understanding on the mechanisms of lipid production, lipid packaging, and their pathophysiological roles.
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Affiliation(s)
- Yaoyao Zhao
- Graduate School of Health Science , Hokkaido University , Sapporo 060-0812 , Japan
| | - Zhen Chen
- Graduate School of Health Science , Hokkaido University , Sapporo 060-0812 , Japan
| | - Yue Wu
- Graduate School of Health Science , Hokkaido University , Sapporo 060-0812 , Japan
| | - Takayuki Tsukui
- Department of Nutrition , Sapporo University of Health Sciences , Sapporo 007-0894 , Japan
| | - Xiaoxiao Ma
- Department of Precision Instrument , Tsinghua University , Beijing 100084 , P.R. China
| | - Xinrong Zhang
- Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Department of Chemistry , Tsinghua University , Beijing 100084 , P.R. China
| | - Hitoshi Chiba
- Department of Nutrition , Sapporo University of Health Sciences , Sapporo 007-0894 , Japan
| | - Shu-Ping Hui
- Graduate School of Health Science , Hokkaido University , Sapporo 060-0812 , Japan
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113
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Datta S, Liu Y, Hariri H, Bowerman J, Henne WM. Cerebellar ataxia disease-associated Snx14 promotes lipid droplet growth at ER-droplet contacts. J Cell Biol 2019; 218:1335-1351. [PMID: 30765438 PMCID: PMC6446855 DOI: 10.1083/jcb.201808133] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 12/29/2018] [Accepted: 01/28/2019] [Indexed: 01/22/2023] Open
Abstract
Lipid droplets (LDs) are nutrient reservoirs used by cells to maintain homeostasis. Nascent droplets form on the endoplasmic reticulum (ER) and grow following an influx of exogenous fatty acids (FAs). The budding of LDs requires extensive ER-LD crosstalk, but how this is regulated remains poorly understood. Here, we show that sorting nexin protein Snx14, an ER-resident protein associated with the cerebellar ataxia SCAR20, localizes to ER-LD contacts following FA treatment, where it promotes LD maturation. Using proximity-based APEX technology and topological dissection, we show that Snx14 accumulates specifically at ER-LD contacts independently of Seipin, where it remains ER-anchored and binds LDs in trans. SNX14KO cells exhibit perturbed LD morphology, whereas Snx14 overexpression promotes LD biogenesis and extends ER-LD contacts. Multi-time point imaging reveals that Snx14 is recruited to ER microdomains containing the fatty acyl-CoA ligase ACSL3, where nascent LDs bud. We propose that Snx14 is a novel marker for ER-LD contacts and regulates FA-stimulated LD growth.
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Affiliation(s)
- Sanchari Datta
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Yang Liu
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Hanaa Hariri
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Jade Bowerman
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - W Mike Henne
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
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114
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Phosphatidic acid as a limiting host metabolite for the proliferation of the microsporidium Tubulinosema ratisbonensis in Drosophila flies. Nat Microbiol 2019; 4:645-655. [DOI: 10.1038/s41564-018-0344-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 12/07/2018] [Indexed: 12/18/2022]
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115
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Binh TD, Pham TLA, Men TT, Dang TTP, Kamei K. LSD-2 dysfunction induces dFoxO-dependent cell death in the wing of Drosophila melanogaster. Biochem Biophys Res Commun 2018; 509:491-497. [PMID: 30595382 DOI: 10.1016/j.bbrc.2018.12.132] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 12/18/2018] [Indexed: 11/27/2022]
Abstract
Lipid storage droplet-2 (LSD-2) of Drosophila melanogaster is a member of the lipid storage droplet membrane surface-binding protein family. LSD-2 is detected in many specific tissues: germline precursor cells, fat body, and is associated with lipid metabolism, lipid storage, and regulation of lipid droplet transport. However, the roles of this gene in development remain unclear. To investigate these functions, we performed tissue-specific knockdown of Lsd-2 in Drosophila using the combination of GAL4/UAS system and RNAi. Here we report that the knockdown of Lsd-2 in the wing led to abnormal wing phenotype and cell death in the wing pouch of 3rd-instar larvae, suggesting an essential role of Lsd-2 in development of the Drosophila wing. This function of Lsd-2 is dependent on the transcription factor dFoxO, as dFoxO depletion suppresses cell death and the abnormal wing pattern formation induced by Lsd-2-knockdown. Furthermore, Lsd-2-knockdown up-regulated the expression of the dFoxO transcription target reaper, which constitutes a pro-apoptosis gene. This study provides the first evidence that Lsd-2-knockdown causes cell death mediated by dfoxO.
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Affiliation(s)
- Tran Duy Binh
- Department of Functional Chemistry, Kyoto Institute of Technology, Kyoto, 606-8585, Japan.
| | - Tuan L A Pham
- Department of Functional Chemistry, Kyoto Institute of Technology, Kyoto, 606-8585, Japan.
| | - Tran Thanh Men
- Department of Biology, Cantho University, Cantho City, 900000, Viet Nam.
| | - Thao T P Dang
- Department of Molecular and Environmental Biotechnology, University of Natural Science, Vietnam National University-HCM, Ho Chi Minh City, 700000, Viet Nam.
| | - Kaeko Kamei
- Department of Functional Chemistry, Kyoto Institute of Technology, Kyoto, 606-8585, Japan.
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116
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Mignolet A, Wood BR, Goormaghtigh E. Intracellular investigation on the differential effects of 4 polyphenols on MCF-7 breast cancer cells by Raman imaging. Analyst 2018; 143:258-269. [PMID: 29214243 DOI: 10.1039/c7an01460k] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The past decades have seen significant interest in the study of polyphenolic compounds as potential therapeutic agents in medicine because they display a vast array of cellular effects beneficial to treat or manage a plethora of chronic diseases including inflammatory diseases, cardiovascular abnormalities and several types of cancer. These compounds act at different stages of carcinogenesis but deciphering their mode of action is a complex task. Live MCF-7 breast cancer cells were investigated using Raman imaging to evaluate the perturbations induced after incubating cells with four different polyphenols: EGCG, gallic acid, resveratrol and tannic acid. First, clear spectral changes could be observed between the spectra of the cytoplasm and the nucleus of live MCF-7 cancer cells demonstrating a difference in their respective global chemical composition. The treatments induced significant modifications in the cells but no clear common pattern of modifications from the 4 drugs could be observed in the cell spectra in the 1800-600 cm-1 region. The high spatial resolution of Raman confocal microscopy enabled both the nucleus and cytoplasm to be independently targeted to study the impact of the polyphenols on the cell line. Positive spectral variations at 2851 cm-1 and 2920 cm-1 as well as in the 1460-1420 cm-1 and 1660-1650 cm-1 spectral regions inside cell cytoplasm reflected an increase of the lipid content after exposure to polyphenols. Lipid accumulation appears to be an early biomarker of drug-induced cell stress and subsequent apoptosis. Interestingly an increase of cytochrome c into the cytosol was also induced by EGCG. These multiple events are possibly associated with cell apoptosis. In conclusion, Raman micro-spectroscopy provides a complementary spectroscopic method to realize biological investigations on live cancer cells and to evaluate the effects of polyphenols at the subcellular level.
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Affiliation(s)
- A Mignolet
- Center for Structural Biology and Bioinformatics, Laboratory for the Structure and Function of Biological Membranes; Université Libre de Bruxelles, Campus Plaine, Bld du Triomphe 2, CP206/2, B1050 Brussels, Belgium
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117
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Breher-Esch S, Sahini N, Trincone A, Wallstab C, Borlak J. Genomics of lipid-laden human hepatocyte cultures enables drug target screening for the treatment of non-alcoholic fatty liver disease. BMC Med Genomics 2018; 11:111. [PMID: 30547786 PMCID: PMC6295111 DOI: 10.1186/s12920-018-0438-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/23/2018] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is a major health burden in need for new medication. To identify potential drug targets a genomic study was performed in lipid-laden primary human hepatocyte (PHH) and human hepatoma cell cultures. METHODS PHH, HuH7 and HepG2 hepatoma cell cultures were treated with lipids and/or TNFα. Intracellular lipid load was quantified with the ORO assay. The Affymetrix HG-U133+ array system was employed to perform transcriptome analysis. The lipid droplet (LD) growth and fusion was determined by fluorescence microscopy. LD associated proteins were imaged by confocal immunofluorescence microscopy and confirmed by Western immunoblotting. Bioinformatics defined perturbed metabolic pathways. RESULTS Whole genome expression profiling identified 227, 1031 and 571 significant regulated genes. Likewise, the combined lipid and TNFα treatment of PHH, HuH7 and HepG2 cell cultures revealed 154, 1238 and 278 differentially expressed genes. Although genomic responses differed among in-vitro systems, commonalities were ascertained by filtering the data for LD associated gene regulations. Among others the LD-growth and fusion associated cell death inducing DFFA like effector C (CIDEC), perilipins (PLIN2, PLIN3), the synaptosome-associated-protein 23 and the vesicle associated membrane protein 3 were strongly up-regulated. Likewise, the PPAR targets pyruvate-dehydrogenase-kinase-4 and angiopoietin-like-4 were up-regulated as was hypoxia-inducible lipid droplet-associated (HILPDA), flotilin and FGF21. Their inhibition ameliorates triglyceride and cholesterol accumulation. TNFα treatment elicited strong induction of the chemokine CXCL8, the kinases MAP3K8, MAP4K4 and negative regulators of cytokine signaling, i.e. SOCS2&SOCS3. Live cell imaging of DsRED calreticulin plasmid transfected HuH7 cells permitted an assessment of LD growth and fusion and confocal immunofluorescence microscopy evidenced induced LD-associated PLIN2, CIDEC, HIF1α, HILPDA, JAK1, PDK4 and ROCK2 expression. Notwithstanding, CPT1A protein was repressed to protect mitochondria from lipid overload. Pharmacological inhibition of the GTPase-dynamin and the fatty acid transporter-2 reduced lipid uptake by 28.5 and 35%, respectively. Finally, a comparisons of in-vitro/NAFLD patient biopsy findings confirmed common gene regulations thus demonstrating clinical relevance. CONCLUSION The genomics of fat-laden hepatocytes revealed LD-associated gene regulations and perturbed metabolic pathways. Immunofluorescence microscopy confirmed expression of coded proteins to provide a rationale for therapeutic intervention strategies. Collectively, the in-vitro system permits testing of drug candidates.
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Affiliation(s)
- Stephanie Breher-Esch
- Centre for Pharmacology and Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Nishika Sahini
- Centre for Pharmacology and Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Anna Trincone
- Centre for Pharmacology and Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Christin Wallstab
- Institute of Biochemistry, Charité - University Medicine Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Jürgen Borlak
- Centre for Pharmacology and Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
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118
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Ezetimibe inhibits dengue virus infection in Huh-7 cells by blocking the cholesterol transporter Niemann–Pick C1-like 1 receptor. Antiviral Res 2018; 160:151-164. [DOI: 10.1016/j.antiviral.2018.10.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 10/25/2018] [Accepted: 10/26/2018] [Indexed: 12/29/2022]
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119
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Lipid accumulation facilitates mitotic slippage-induced adaptation to anti-mitotic drug treatment. Cell Death Discov 2018; 4:109. [PMID: 30510774 PMCID: PMC6258763 DOI: 10.1038/s41420-018-0127-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/08/2018] [Accepted: 11/12/2018] [Indexed: 02/06/2023] Open
Abstract
Aberrant lipid accumulation is a hallmark of cancer known to contribute to its aggressiveness and malignancy. Emerging studies have demonstrated context-dependent changes in lipid metabolism during chemotherapy. However, there is little known regarding the mechanisms linking lipid metabolism to chemotherapy-induced cell fates. Here, we describe lipid accumulation in cells following antimitotic drug treatment. Cells arrested in mitosis, as well as cells that escaped mitotic arrest and underwent mitotic slippage, showed elevated cytoplasmic lipid droplets. Interestingly, we found that TOFA, a lipid biosynthesis inhibitor that targets acetyl-CoA carboxylase (ACC) and blocks lipid accumulation, promoted early slippage, reduced cellular stress and enhanced survival of antimitotic-treated cells. Our work previously revealed that cells that survive after mitotic slippage can become senescent and confer pro-tumourigenic effects through paracrine signalling. Modulating lipid biosynthesis in cells post slippage by TOFA amplified their inflammatory secretion profiles and accelerated the development of tumourigenic behaviour, particularly cell migration and invasion, in a paracrine-dependent manner. In contrast to TOFA, inhibition of lipid accumulation by C75, a drug targeting fatty acid synthase (FASN), significantly reduced the production of pro-tumourigenic factors and associated phenotypic effects. This suggests that discrete lipid biosynthesis pathways could contribute differentially to the regulation of pro-tumourigenic inflammation. The divergent effects of TOFA and C75 may be attributed to the opposing regulation of Malonyl-CoA, an intermediate in fatty acid synthesis that serves as a mediator of fatty acid oxidation. Taken together, our data reveal a previously unappreciated role for lipid accumulation in the cellular adaptation to antimitotic drug treatment. Targeting lipid biosynthesis in cells post slippage may reprogramme its secretory profile such that it not only negates tumour-promoting effects, but may also promote anti-tumour inflammation for clearance of post-slippage senescent cells.
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120
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Kyle JE, Clair G, Bandyopadhyay G, Misra RS, Zink EM, Bloodsworth KJ, Shukla AK, Du Y, Lillis J, Myers JR, Ashton J, Bushnell T, Cochran M, Deutsch G, Baker ES, Carson JP, Mariani TJ, Xu Y, Whitsett JA, Pryhuber G, Ansong C. Cell type-resolved human lung lipidome reveals cellular cooperation in lung function. Sci Rep 2018; 8:13455. [PMID: 30194354 PMCID: PMC6128932 DOI: 10.1038/s41598-018-31640-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/26/2018] [Indexed: 12/21/2022] Open
Abstract
Cell type-resolved proteome analyses of the brain, heart and liver have been reported, however a similar effort on the lipidome is currently lacking. Here we applied liquid chromatography-tandem mass spectrometry to characterize the lipidome of major lung cell types isolated from human donors, representing the first lipidome map of any organ. We coupled this with cell type-resolved proteomics of the same samples (available at Lungmap.net). Complementary proteomics analyses substantiated the functional identity of the isolated cells. Lipidomics analyses showed significant variations in the lipidome across major human lung cell types, with differences most evident at the subclass and intra-subclass (i.e. total carbon length of the fatty acid chains) level. Further, lipidomic signatures revealed an overarching posture of high cellular cooperation within the human lung to support critical functions. Our complementary cell type-resolved lipid and protein datasets serve as a rich resource for analyses of human lung function.
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Affiliation(s)
- Jennifer E Kyle
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Geremy Clair
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Gautam Bandyopadhyay
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA
| | - Ravi S Misra
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA
| | - Erika M Zink
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Kent J Bloodsworth
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Anil K Shukla
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Yina Du
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Jacquelyn Lillis
- Genomics Research Center, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA
| | - Jason R Myers
- Genomics Research Center, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA
| | - John Ashton
- Genomics Research Center, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA
| | - Timothy Bushnell
- Flow Cytometry Core Facility, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA
| | - Matthew Cochran
- Flow Cytometry Core Facility, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA
| | - Gail Deutsch
- Department of Pathology, Seattle Children's Hospital, Seattle, WA, 98105, USA
| | - Erin S Baker
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - James P Carson
- Texas Advanced Computing Center, University of Texas at Austin, Austin, TX, 78712, USA
| | - Thomas J Mariani
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA
| | - Yan Xu
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Jeffrey A Whitsett
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Gloria Pryhuber
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA
| | - Charles Ansong
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA.
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121
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Maldonado EM, Fisher CP, Mazzatti DJ, Barber AL, Tindall MJ, Plant NJ, Kierzek AM, Moore JB. Multi-scale, whole-system models of liver metabolic adaptation to fat and sugar in non-alcoholic fatty liver disease. NPJ Syst Biol Appl 2018; 4:33. [PMID: 30131870 PMCID: PMC6102210 DOI: 10.1038/s41540-018-0070-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 07/30/2018] [Accepted: 07/31/2018] [Indexed: 12/11/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a serious public health issue associated with high fat, high sugar diets. However, the molecular mechanisms mediating NAFLD pathogenesis are only partially understood. Here we adopt an iterative multi-scale, systems biology approach coupled to in vitro experimentation to investigate the roles of sugar and fat metabolism in NAFLD pathogenesis. The use of fructose as a sweetening agent is controversial; to explore this, we developed a predictive model of human monosaccharide transport, signalling and metabolism. The resulting quantitative model comprising a kinetic model describing monosaccharide transport and insulin signalling integrated with a hepatocyte-specific genome-scale metabolic network (GSMN). Differential kinetics for the utilisation of glucose and fructose were predicted, but the resultant triacylglycerol production was predicted to be similar for monosaccharides; these predictions were verified by in vitro data. The role of physiological adaptation to lipid overload was explored through the comprehensive reconstruction of the peroxisome proliferator activated receptor alpha (PPARα) regulome integrated with a hepatocyte-specific GSMN. The resulting qualitative model reproduced metabolic responses to increased fatty acid levels and mimicked lipid loading in vitro. The model predicted that activation of PPARα by lipids produces a biphasic response, which initially exacerbates steatosis. Our data support the evidence that it is the quantity of sugar rather than the type that is critical in driving the steatotic response. Furthermore, we predict PPARα-mediated adaptations to hepatic lipid overload, shedding light on potential challenges for the use of PPARα agonists to treat NAFLD.
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Affiliation(s)
- Elaina M. Maldonado
- School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH UK
| | - Ciarán P. Fisher
- Certara UK Limited, Simcyp Division, Level 2-Acero, 1 Concourse Way, Sheffield, S1 2BJ UK
| | | | - Amy L. Barber
- School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH UK
| | - Marcus J. Tindall
- Department of Mathematics and Statistics, University of Reading, Berkshire, RG6 6AX UK
- Institute of Cardiovascular and Metabolic Research, University of Reading, Berkshire, RG6 6UR UK
| | - Nicholas J. Plant
- School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH UK
- Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire, LS2 9JT UK
| | - Andrzej M. Kierzek
- School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH UK
- Certara UK Limited, Simcyp Division, Level 2-Acero, 1 Concourse Way, Sheffield, S1 2BJ UK
| | - J. Bernadette Moore
- School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH UK
- School of Food Science & Nutrition, University of Leeds, Leeds, West Yorkshire, LS2 9JT UK
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122
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Ekanayake V, Nisan D, Ryzhov P, Yao Y, Marassi FM. Lipoprotein Particle Formation by Proapoptotic tBid. Biophys J 2018; 115:533-542. [PMID: 30017071 DOI: 10.1016/j.bpj.2018.06.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/13/2018] [Accepted: 06/19/2018] [Indexed: 10/28/2022] Open
Abstract
The interactions of Bcl-2 family proteins with intracellular lipids are essential for the regulation of apoptosis, a mechanism of programmed cell death that is central to the health and development of multicellular organisms. Bid and its caspase-8 cleavage product, tBid, promote the permeabilization of the mitochondrial outer membrane and sequester antiapoptotic Bcl-2 proteins to counter their cytoprotective activity. Bid and tBid also promote lipid exchange, a characteristic trait of apoptosis. Here, we show that tBid is capable of associating with phospholipids to form soluble, nanometer-sized lipoprotein particles that retain binding affinity for the antiapoptotic protein Bcl-xL. The tBid lipoprotein particles form with a lipid/protein stoichiometry in the range of 20/1 and have a diameter of ∼11.5 nm. Lipoparticle-bound tBid retains an α-helical structure and binds Bcl-xL through its third Bcl-2 homology motif, forming a soluble, lipid-associated heteroprotein complex. The results shed light on the role of lipids in mediating Bcl-2 protein mobility and interactions.
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Affiliation(s)
- Vindana Ekanayake
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Danielle Nisan
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Pavel Ryzhov
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Yong Yao
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Francesca M Marassi
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California.
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123
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Trypanosoma cruzi epimastigotes store cholesteryl esters in lipid droplets after cholesterol endocytosis. Mol Biochem Parasitol 2018; 224:6-16. [PMID: 30016698 DOI: 10.1016/j.molbiopara.2018.07.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 07/05/2018] [Accepted: 07/10/2018] [Indexed: 11/21/2022]
Abstract
The Chagas disease agent Trypanosoma cruzi proliferates in the insect vector as highly endocytic epimastigotes that store nutrients, including lipids in reservosomes (lysosome related compartments). Although nutrient storage is important for epimastigote transformation into infective metacyclics, the epimastigote lipid droplets (LDs) remain uncharacterized. Here, we characterized the epimastigote LDs and examined their relationship with the endocytic pathway. Fluorescence microscopy using BODIPY showed that LDs have high neutral lipid content and harbor Rab18, differently from other lipid-rich organelles (such as reservosomes). Using transmission electron microscopy (TEM), we observed a close relationship between LDs and the endoplasmic reticulum, mitochondria and glycosomes. We developed a reproducible protocol to isolate LDs, and showed (by HTPLC and GC/MS analyses) that they have 89% neutral lipids and 11% phospholipids, which are likely to form the LD monolayer seen by TEM. The LD neutral lipids were mostly sterols, although triacylglycerol, diacylglycerol, monoacylglycerol and free fatty acids (FFA) were also found. Endocytosis of 3H-labeled cholesterol-BSA showed that internalized cholesterol is stored in LDs mostly in the cholesteryl ester form. Together, these results suggest that exogenous cholesterol internalized by endocytosis reaches the reservosomes and is then stored into LDs after esterification.
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124
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Keyhani NO. Lipid biology in fungal stress and virulence: Entomopathogenic fungi. Fungal Biol 2018; 122:420-429. [DOI: 10.1016/j.funbio.2017.07.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 07/11/2017] [Accepted: 07/13/2017] [Indexed: 12/17/2022]
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125
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Wang G, Kim WK, Cline MA, Gilbert ER. Factors affecting adipose tissue development in chickens: A review. Poult Sci 2018; 96:3687-3699. [PMID: 28938790 DOI: 10.3382/ps/pex184] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 06/13/2017] [Indexed: 12/12/2022] Open
Abstract
The intense genetic selection for rapid growth in broilers has resulted in an increase in voluntary feed intake and growth rate, accompanied by increased fat deposition in adipose tissue depots throughout the body. Adipose tissue expansion is a result of the formation of adipocytes (several processes collectively referred to as adipogenesis) and cellular accumulation of triacylglycerols inside lipid droplets. In mammals, different anatomical depots are metabolically distinct. The molecular and cellular mechanisms underlying adipose tissue development have been characterized in mammalian models, whereas information in avian species is scarce. The purpose of this review is to describe factors regulating adipogenesis in chickens, with an emphasis on dietary factors and the broiler. Results from many studies have demonstrated effects of dietary nutrient composition on adipose tissue development and lipid metabolism. Transcription factors, such as peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding proteins α and β, and sterol regulatory element binding proteins orchestrate a series of cellular events that lead to an increase in activity of fatty acid transport proteins and enzymes that are responsible for triacylglycerol synthesis. Understanding the mechanisms underlying adipose tissue development may provide a practical strategy to affect body composition of the commercial broiler while providing insights on diets that maximize conversion into muscle rather than fat and affect depot-dependent deposition of lipids. Because of the propensity to overeat and become obese, the broiler chicken also represents an attractive biomedical model for eating disorders and obesity in humans.
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Affiliation(s)
- Guoqing Wang
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia 24061
| | - Woo Kyun Kim
- Department of Poultry Science, University of Georgia, Athens, GA 30602
| | - Mark A Cline
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia 24061
| | - Elizabeth R Gilbert
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia 24061
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126
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Xu S, Zhang X, Liu P. Lipid droplet proteins and metabolic diseases. Biochim Biophys Acta Mol Basis Dis 2018; 1864:1968-1983. [DOI: 10.1016/j.bbadis.2017.07.019] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 07/14/2017] [Accepted: 07/19/2017] [Indexed: 12/13/2022]
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127
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Romero-Aguilar L, Montero-Lomeli M, Pardo JP, Guerra-Sánchez G. Lipid Index Determination by Liquid Fluorescence Recovery in the Fungal Pathogen Ustilago Maydis. J Vis Exp 2018. [PMID: 29683447 DOI: 10.3791/57279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The article shows how to implement the LD index assay, which is a sensitive microplate assay to determine the accumulation of triacylglycerols (TAGs) in lipid droplets (LDs). LD index is obtained without lipid extraction. It allows measuring the LDs content in high-throughput experiments under different conditions such as growth in rich or nitrogen depleted media. Albeit the method was described for the first time to study the lipid droplet metabolism in Saccharomyces cerevisiae, it was successfully applied to the basidiomycete Ustilago maydis. Interestingly, and because LDs are organelles phylogenetically conserved in eukaryotic cells, the method can be applied to a large variety of cells, from yeast to mammalian cells. The LD index is based on the liquid fluorescence recovery assay (LFR) of the BODIPY 493/503 under quenching conditions, by the addition of cells fixed with formaldehyde. Potassium iodine is used as a fluorescence quencher. The ratio between the fluorescence and the optical density slopes is named LD index. Slopes are calculated from the straight lines obtained when BODIPY fluorescence and optical density at 600 nm (OD600) are plotted against sample addition. Optimal data quality is reflected by correlation coefficients equal or above 0.9 (r ≥ 0.9). Multiple samples can be read simultaneously as it can be implemented in a microplate. Since BODIPY 493/503 is a lipophilic fluorescent dye that partitions into the lipid droplets, it can be used in many types of cells that accumulate LDs.
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Affiliation(s)
- Lucero Romero-Aguilar
- Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional; Facultad de Medicina, Universidad Nacional Autónoma de México
| | - Mónica Montero-Lomeli
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro
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128
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Becerra-Ruiz M, Vargas V, Jara P, Tirapegui C, Carrasco C, Nuñez M, Lezana N, Galdámez A, Vilches-Herrera M. Blue-Fluorescent Probes for Lipid Droplets Based on Dihydrochromeno-Fused Pyrazolo- and Pyrrolopyridines. European J Org Chem 2018. [DOI: 10.1002/ejoc.201701633] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Martín Becerra-Ruiz
- Department of Chemistry; Faculty of Sciences; University of Chile; Las Palmeras 3425, Nunoa 7500008 Santiago Chile
| | - Victor Vargas
- Department of Chemistry; Faculty of Sciences; University of Chile; Las Palmeras 3425, Nunoa 7500008 Santiago Chile
| | - Patricio Jara
- Department of Chemistry; Faculty of Sciences; University of Chile; Las Palmeras 3425, Nunoa 7500008 Santiago Chile
| | - Cristian Tirapegui
- Faculty of Chemistry and Biology; University of Santiago de Chile; Av. Lib. Bernardo O' Higgins 3363, Est. Central Santiago Chile
- Instituto de Ciencias Químicas Aplicadas; Facultad de Ingeniería; Universidad Autónoma de Chile; El Llano Subercaseaux 2801, San Miguel Santiago Chile
| | - Carlos Carrasco
- Department of Biology; Faculty of Sciences; University of Chile; Las Palmeras 3425, Nunoa 7500008 Santiago Chile
| | - Marco Nuñez
- Department of Biology; Faculty of Sciences; University of Chile; Las Palmeras 3425, Nunoa 7500008 Santiago Chile
| | - Nicolás Lezana
- Department of Chemistry; Faculty of Sciences; University of Chile; Las Palmeras 3425, Nunoa 7500008 Santiago Chile
| | - Antonio Galdámez
- Department of Chemistry; Faculty of Sciences; University of Chile; Las Palmeras 3425, Nunoa 7500008 Santiago Chile
| | - Marcelo Vilches-Herrera
- Department of Chemistry; Faculty of Sciences; University of Chile; Las Palmeras 3425, Nunoa 7500008 Santiago Chile
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129
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Escorcia W, Ruter DL, Nhan J, Curran SP. Quantification of Lipid Abundance and Evaluation of Lipid Distribution in Caenorhabditis elegans by Nile Red and Oil Red O Staining. J Vis Exp 2018. [PMID: 29553519 DOI: 10.3791/57352] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Caenorhabditis elegans is an exceptional model organism in which to study lipid metabolism and energy homeostasis. Many of its lipid genes are conserved in humans and are associated with metabolic syndrome or other diseases. Examination of lipid accumulation in this organism can be carried out by fixative dyes or label-free methods. Fixative stains like Nile red and oil red O are inexpensive, reliable ways to quantitatively measure lipid levels and to qualitatively observe lipid distribution across tissues, respectively. Moreover, these stains allow for high-throughput screening of various lipid metabolism genes and pathways. Additionally, their hydrophobic nature facilitates lipid solubility, reduces interaction with surrounding tissues, and prevents dissociation into the solvent. Though these methods are effective at examining general lipid content, they do not provide detailed information about the chemical composition and diversity of lipid deposits. For these purposes, label-free methods such as GC-MS and CARS microscopy are better suited, their costs notwithstanding.
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Affiliation(s)
- Wilber Escorcia
- Leonard Davis School of Gerontology, University of Southern California
| | - Dana L Ruter
- Leonard Davis School of Gerontology, University of Southern California; Molecular & Computational Biology Section, University of Southern California; Integrative Program for Biological & Genome Sciences, University of North Carolina at Chapel Hill
| | - James Nhan
- Leonard Davis School of Gerontology, University of Southern California; Molecular & Computational Biology Section, University of Southern California
| | - Sean P Curran
- Leonard Davis School of Gerontology, University of Southern California; Molecular & Computational Biology Section, University of Southern California;
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130
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Tsai CH, Uygun S, Roston R, Shiu SH, Benning C. Recovery from N Deprivation Is a Transcriptionally and Functionally Distinct State in Chlamydomonas. PLANT PHYSIOLOGY 2018; 176:2007-2023. [PMID: 29288234 PMCID: PMC5841715 DOI: 10.1104/pp.17.01546] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 12/26/2017] [Indexed: 05/20/2023]
Abstract
Facing adverse conditions such as nitrogen (N) deprivation, microalgae enter cellular quiescence, a reversible cell cycle arrest with drastic changes in metabolism allowing cells to remain viable. Recovering from N deprivation and quiescence is an active and orderly process as we are showing here for Chlamydomonas reinhardtii We conducted comparative transcriptomics on this alga to discern processes relevant to quiescence in the context of N deprivation and recovery following refeeding. A mutant with slow recovery from N deprivation, compromised hydrolysis of triacylglycerols7 (cht7), was included to better define the regulatory processes governing the respective transitions. We identified an ordered set of biological processes with expression patterns that showed sequential reversal following N resupply and uncovered acclimation responses specific to the recovery phase. Biochemical assays and microscopy validated selected inferences made based on the transcriptional analyses. These comprise (1) the restoration of N source preference and cellular bioenergetics during the early stage of recovery; (2) flagellum-based motility in the mid to late stage of recovery; and (3) recovery phase-specific gene groups cooperating in the rapid replenishment of chloroplast proteins. In the cht7 mutant, a large number of programmed responses failed to readjust in a timely manner. Finally, evidence is provided for the involvement of the cAMP-protein kinase A pathway in gating the recovery. We conclude that the recovery from N deprivation represents not simply a reversal of processes directly following N deprivation, but a distinct cellular state.
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Affiliation(s)
- Chia-Hong Tsai
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Sahra Uygun
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Genetics Program, Michigan State University, East Lansing, Michigan 48824
| | - Rebecca Roston
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
| | - Shin-Han Shiu
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Genetics Program, Michigan State University, East Lansing, Michigan 48824
| | - Christoph Benning
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
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131
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Liu Y, Leslie PL, Jin A, Itahana K, Graves LM, Zhang Y. p32 regulates ER stress and lipid homeostasis by down-regulating GCS1 expression. FASEB J 2018; 32:3892-3902. [PMID: 29465311 DOI: 10.1096/fj.201701004rr] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Sustained endoplasmic reticulum (ER) stress plays a major role in the development of many metabolic diseases, including cardiovascular disease, nonalcoholic fatty liver disease, insulin resistance, obesity, and diabetes. p32 is a multicompartmental protein involved in the regulation of oxidative phosphorylation and glucose oxidation. p32 ablation is associated with resistance to age-associated and diet-induced obesity through a mechanism that remains largely unknown. Here, we show that p32 promotes lipid biosynthesis by modulating fatty acid-induced ER stress. We found that p32 interacts with endoplasmic reticulum-anchored enzyme mannosyl-oligosaccharide glucosidase I (GCS1), an ER lumen-anchored glucosidase that is essential for the processing of N-linked glycoproteins, and reduces GCS1 in a lysosome-dependent manner. We demonstrate that increased GCS1 expression alleviates fatty acid-induced ER stress and is critical for suppressing ER stress-associated lipogenic gene activation, as demonstrated by the down-regulation of Srebp1, Fasn, and Acc. Consistently, suppression of p32 leads to increased GCS1 expression and alleviates fatty acid-induced ER stress, resulting in reduced lipid accumulation. Thus, p32 and GCS1 are regulators of ER function and lipid homeostasis and are potential therapeutic targets for the treatment of obesity and diabetes.-Liu, Y., Leslie, P. L., Jin, A., Itahana, K., Graves, L. M., Zhang, Y. p32 regulates ER stress and lipid homeostasis by down-regulating GCS1 expression.
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Affiliation(s)
- Yong Liu
- Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical College, Xuzhou, China
| | - Patrick L Leslie
- Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; and
| | - Aiwen Jin
- Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Koji Itahana
- Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Lee M Graves
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Yanping Zhang
- Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical College, Xuzhou, China.,Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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132
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O'Harte FPM, Parthsarathy V, Hogg C, Flatt PR. Apelin-13 analogues show potent in vitro and in vivo insulinotropic and glucose lowering actions. Peptides 2018; 100:219-228. [PMID: 29412822 DOI: 10.1016/j.peptides.2017.12.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 12/01/2017] [Accepted: 12/04/2017] [Indexed: 01/08/2023]
Abstract
Nine structurally modified apelin-13 analogues were assessed for their in vitro and acute in vivo antidiabetic potential. Stability was assessed in mouse plasma and insulinotropic efficacy tested in cultured pancreatic BRIN-BD11 cells and isolated mouse pancreatic islets. Intracellular Ca2+ and cAMP production in BRIN-BD11 cells was determined, as was glucose uptake in 3T3-L1 adipocytes. Acute antihyperglycemic effects of apelin analogues were assessed following i.p. glucose tolerance tests (ipGGT, 18 mmol/kg) in normal and diet-induced-obese (DIO) mice and on food intake in normal mice. Apelin analogues all showed enhanced in vitro stability (up to 5.8-fold, t½ = 12.8 h) in mouse plasma compared to native apelin-13 (t½ = 2.1 h). Compared to glucose controls, stable analogues exhibited enhanced insulinotropic responses from BRIN-BD11 cells (up to 4.7-fold, p < 0.001) and isolated mouse islets (up to 5.3-fold) for 10-7 M apelin-13 amide (versus 7.6-fold for 10-7 M GLP-1). Activation of APJ receptors on BRIN-BD11 cells increased intracellular Ca2+ (up to 3.0-fold, p < 0.001) and cAMP (up to 1.7-fold, p < 0.01). Acute ipGTT showed improved insulinotropic and glucose disposal responses in normal and DIO mice (p < 0.05 and p < 0.01, respectively). Apelin-13 amide and (pGlu)apelin-13 amide were the most effective analogues exhibiting acute, dose-dependent and persistent biological actions. Both analogues stimulated insulin-independent glucose uptake by differentiated adipocytes (2.9-3.3-fold, p < 0.05) and inhibited food intake (26-33%, p < 0.001), up to 180 min in mice, versus saline. In contrast, (Ala13)apelin-13 and (Val13)apelin-13 inhibited insulin secretion, suppressed beta-cell signal transduction and stimulated food intake in mice. Thus, stable analogues of apelin-13 have potential for diabetes/obesity therapy.
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Affiliation(s)
- F P M O'Harte
- The SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK.
| | - V Parthsarathy
- The SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK
| | - C Hogg
- The SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK
| | - P R Flatt
- The SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK
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133
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Taurino M, Costantini S, De Domenico S, Stefanelli F, Ruano G, Delgadillo MO, Sánchez-Serrano JJ, Sanmartín M, Santino A, Rojo E. SEIPIN Proteins Mediate Lipid Droplet Biogenesis to Promote Pollen Transmission and Reduce Seed Dormancy. PLANT PHYSIOLOGY 2018; 176:1531-1546. [PMID: 29203558 PMCID: PMC5813562 DOI: 10.1104/pp.17.01430] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 11/30/2017] [Indexed: 05/08/2023]
Abstract
Lipid droplets (LDs) are ubiquitous organelles in plant cells, but their physiological roles are largely unknown. To gain insight into the function of LDs in plants, we have characterized the Arabidopsis homologs of SEIPIN proteins, which are crucial factors for LD biogenesis in yeast and animals. SEIPIN1 is expressed almost exclusively in embryos, while SEIPIN2 and SEIPIN3 have broader expression profiles with maximal levels in embryos and pollen, where LDs accumulate most abundantly. Genetic analysis demonstrates that all three SEIPINs contribute to proper LD biogenesis in embryos, whereas in pollen, only SEIPIN2 and SEIPIN3 play a significant role. The double seipin2 seipin3 and triple seipin mutants accumulate extremely enlarged LDs in seeds and pollen, which hinders their subsequent mobilization during germination. Interestingly, electron microscopy analysis reveals the presence of nuclear LDs attached to type I nucleoplasmic reticulum in triple seipin mutant embryos, supporting that SEIPINs are essential for maintaining the correct polarity of LD budding at the nuclear envelope, restricting it to the outer membrane. In pollen, the perturbations in LD biogenesis and turnover are coupled to reduced germination in vitro and with lower fertilization efficiency in vivo. In seeds, germination per se is not affected in seipin2 seipin3 and triple seipin mutants, but there is a striking increase in seed dormancy levels. Our findings reveal the relevance of SEIPIN-dependent LD biogenesis in pollen transmission and in adjusting the timing of seed germination, two key adaptive traits of great importance in agriculture.
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Affiliation(s)
- Marco Taurino
- Institute of Sciences of Food Production C.N.R. Unit of Lecce, via Monteroni, 73100 Lecce, Italy
| | - Sara Costantini
- Institute of Sciences of Food Production C.N.R. Unit of Lecce, via Monteroni, 73100 Lecce, Italy
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
| | - Stefania De Domenico
- Institute of Sciences of Food Production C.N.R. Unit of Lecce, via Monteroni, 73100 Lecce, Italy
| | - Francesco Stefanelli
- Institute of Sciences of Food Production C.N.R. Unit of Lecce, via Monteroni, 73100 Lecce, Italy
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
| | - Guillermo Ruano
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
- Universidad Politécnica de Madrid, E-28223 Madrid, Spain
| | | | | | - Maite Sanmartín
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
| | - Angelo Santino
- Institute of Sciences of Food Production C.N.R. Unit of Lecce, via Monteroni, 73100 Lecce, Italy
- Address correspondence to or
| | - Enrique Rojo
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
- Address correspondence to or
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134
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Monson EA, Crosse KM, Das M, Helbig KJ. Lipid droplet density alters the early innate immune response to viral infection. PLoS One 2018; 13:e0190597. [PMID: 29293661 PMCID: PMC5749834 DOI: 10.1371/journal.pone.0190597] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 12/17/2017] [Indexed: 12/30/2022] Open
Abstract
The cellular localisation of many innate signalling events following viral infection has yet to be elucidated, however there has been a few cases in which membranes of certain cellular organelles have acted as platforms to these events. Of these, lipid droplets (LDs) have recently been identified as signalling platforms for innate TLR7 and 9 signalling. Despite their wide range of similar roles in various metabolic pathways, LDs have been overlooked as potential platforms for antiviral innate signalling events. This study established an in vitro model to evaluate the efficiency of the early innate immune response in cells with reduced LD content to the viral mimics, dsDNA and dsRNA, and Sendai viral infection. Using RT-qPCR, the expression of IFN-β and IFN-λ was quantified following stimulation along with the expression of specific ISGs. Luciferase based assays evaluated the combined expression of ISRE-promoter driven ISGs under IFN-β stimulation. Cellular LD content did not alter the entry of fluorescently labelled viral mimics into cells, but significantly decreased the ability of both Huh-7 and HeLa cells to produce type I and III IFN, as well as downstream ISG expression, indicative of an impeded innate immune response. This observation was also seen during Sendai virus infection of HeLa cells, where both control and LD reduced cells replicated the virus to the same level, but a significantly impaired type I and III IFN response was observed in the LD reduced cells. In addition to altered IFN production, cells with reduced LD content exhibited decreased expression of specific antiviral ISGs: Viperin, IFIT-1 and OAS-1 under IFN-β stimulation; However the overall induction of the ISRE-promoter was not effected. This study implicates a role for LDs in an efficient early innate host response to viral infection and future work will endeavour to determine the precise role these important organelles play in induction of an antiviral response.
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Affiliation(s)
- Ebony A Monson
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria
| | - Keaton M Crosse
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria
| | - Mithun Das
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria
| | - Karla J Helbig
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria
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135
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Yanina IY, Popov AP, Bykov AV, Meglinski IV, Tuchin VV. Monitoring of temperature-mediated phase transitions of adipose tissue by combined optical coherence tomography and Abbe refractometry. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-9. [PMID: 29297209 DOI: 10.1117/1.jbo.23.1.016003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 12/12/2017] [Indexed: 06/07/2023]
Abstract
Observation of temperature-mediated phase transitions between lipid components of the adipose tissues has been performed by combined use of the Abbe refractometry and optical coherence tomography. The phase transitions of the lipid components were clearly observed in the range of temperatures from 24°C to 60°C, and assessed by quantitatively monitoring the changes of the refractive index of 1- to 2-mm-thick porcine fat tissue slices. The developed approach has a great potential as an alternative method for obtaining accurate information on the processes occurring during thermal lipolysis.
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Affiliation(s)
- Irina Y Yanina
- Saratov State University, Research-Educational Institute of Optics and Biophotonics, Saratov, Russia
- Tomsk State University, Interdisciplinary Laboratory of Biophotonics, Tomsk, Russia
| | - Alexey P Popov
- University of Oulu, Optoelectronics and Measurement Techniques Research Unit, Oulu, Finland
- ITMO University, Terahertz Biomedicine Laboratory, St. Petersburg, Russia
| | - Alexander V Bykov
- University of Oulu, Optoelectronics and Measurement Techniques Research Unit, Oulu, Finland
- ITMO University, Terahertz Biomedicine Laboratory, St. Petersburg, Russia
| | - Igor V Meglinski
- University of Oulu, Optoelectronics and Measurement Techniques Research Unit, Oulu, Finland
- ITMO University, Terahertz Biomedicine Laboratory, St. Petersburg, Russia
- Irkutsk State University, Institute of Biology, Irkutsk, Russia
| | - Valery V Tuchin
- Saratov State University, Research-Educational Institute of Optics and Biophotonics, Saratov, Russia
- Tomsk State University, Interdisciplinary Laboratory of Biophotonics, Tomsk, Russia
- ITMO University, Laboratory of Femtomedicine, St. Petersburg, Russia
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136
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Alfaro IE, Albornoz A, Molina A, Moreno J, Cordero K, Criollo A, Budini M. Chaperone Mediated Autophagy in the Crosstalk of Neurodegenerative Diseases and Metabolic Disorders. Front Endocrinol (Lausanne) 2018; 9:778. [PMID: 30766511 PMCID: PMC6365421 DOI: 10.3389/fendo.2018.00778] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022] Open
Abstract
Chaperone Mediated Autophagy (CMA) is a lysosomal-dependent protein degradation pathway. At least 30% of cytosolic proteins can be degraded by this process. The two major protein players of CMA are LAMP-2A and HSC70. While LAMP-2A works as a receptor for protein substrates at the lysosomal membrane, HSC70 specifically binds protein targets and takes them for CMA degradation. Because of the broad spectrum of proteins able to be degraded by CMA, this pathway has been involved in physiological and pathological processes such as lipid and carbohydrate metabolism, and neurodegenerative diseases, respectively. Both, CMA, and the mentioned processes, are affected by aging and by inadequate nutritional habits such as a high fat diet or a high carbohydrate diet. Little is known regarding about CMA, which is considered a common regulation factor that links metabolism with neurodegenerative disorders. This review summarizes what is known about CMA, focusing on its molecular mechanism, its role in protein, lipid and carbohydrate metabolism. In addition, the review will discuss how CMA could be linked to protein, lipids and carbohydrate metabolism within neurodegenerative diseases. Furthermore, it will be discussed how aging and inadequate nutritional habits can have an impact on both CMA activity and neurodegenerative disorders.
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Affiliation(s)
- Iván E. Alfaro
- Fundación Ciencia & Vida, Santiago, Chile
- *Correspondence: Iván E. Alfaro
| | | | - Alfredo Molina
- Dentistry Faculty, Institute in Dentistry Sciences, University of Chile, Santiago, Chile
| | - José Moreno
- Dentistry Faculty, Institute in Dentistry Sciences, University of Chile, Santiago, Chile
| | - Karina Cordero
- Dentistry Faculty, Institute in Dentistry Sciences, University of Chile, Santiago, Chile
| | - Alfredo Criollo
- Dentistry Faculty, Institute in Dentistry Sciences, University of Chile, Santiago, Chile
- Autophagy Research Center (ARC), Santiago, Chile
- Advanced Center for Chronic Diseases (ACCDiS), University of Chile, Santiago, Chile
| | - Mauricio Budini
- Dentistry Faculty, Institute in Dentistry Sciences, University of Chile, Santiago, Chile
- Autophagy Research Center (ARC), Santiago, Chile
- Mauricio Budini
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137
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Cabirol-Pol MJ, Khalil B, Rival T, Faivre-Sarrailh C, Besson MT. Glial lipid droplets and neurodegeneration in a Drosophila model of complex I deficiency. Glia 2017; 66:874-888. [PMID: 29285794 DOI: 10.1002/glia.23290] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 01/09/2023]
Abstract
Mitochondrial defects associated with respiratory chain complex I deficiency lead to heterogeneous fatal syndromes. While the role of NDUFS8, an essential subunit of the core assembly of the complex I, is established in mitochondrial diseases, the mechanisms underlying neuropathology are poorly understood. We developed a Drosophila model of NDUFS8 deficiency by knocking down the expression of its fly homologue in neurons or in glial cells. Downregulating ND23 in neurons resulted in shortened lifespan, and decreased locomotion. Although total brain ATP levels were decreased, histological analysis did not reveal any signs of neurodegeneration except for photoreceptors of the retina. Interestingly, ND23 deficiency-associated phenotypes were rescued by overexpressing the glucose transporter hGluT3 demonstrating that boosting glucose metabolism in neurons was sufficient to bypass altered mitochondrial functions and to confer neuroprotection. We then analyzed the consequences of ND23 knockdown in glial cells. In contrast to neuronal knockdown, loss of ND23 in glia did not lead to significant behavioral defects nor to reduced lifespan, but induced brain degeneration, as visualized by numerous vacuoles found all over the nervous tissue. This phenotype was accompanied by the massive accumulation of lipid droplets at the cortex-neuropile boundaries, suggesting an alteration of lipid metabolism in glia. These results demonstrate that complex I deficiency triggers metabolic alterations both in neurons and glial cells which may contribute to the neuropathology.
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Affiliation(s)
| | - Bilal Khalil
- Aix Marseille Université, CNRS, CRN2M-UMR7286, 13344 Marseille cedex 15, Marseille, France.,Department of Neuroscience, Mayo Clinic Florida, Jacksonville, Florida
| | - Thomas Rival
- Aix Marseille Université, CNRS, IBDM UMR 7288, Marseille, France
| | | | - Marie Thérèse Besson
- Aix Marseille Université, CNRS, CRN2M-UMR7286, 13344 Marseille cedex 15, Marseille, France
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138
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Florencio-Silva R, Sasso GRS, Sasso-Cerri E, Simões MJ, Cerri PS. Effects of estrogen status in osteocyte autophagy and its relation to osteocyte viability in alveolar process of ovariectomized rats. Biomed Pharmacother 2017; 98:406-415. [PMID: 29276969 DOI: 10.1016/j.biopha.2017.12.089] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 12/05/2017] [Accepted: 12/18/2017] [Indexed: 12/13/2022] Open
Abstract
Estrogen maintains osteocyte viability, whereas its deficiency induces osteocyte apoptosis. As autophagy is important for osteocyte viability, we hypothesized whether the anti-apoptotic effect of estrogen is related to autophagy in osteocytes. Thirty adult female rats were sham-operated (SHAM) or ovariectomized (OVX). After three weeks, twelve rats of SHAM and OVX groups were killed before treatment (basal period), whereas the remaining rats received estrogen (OVXE) or vehicle (OVX) for 45 days. Fragments of maxilla containing alveolar process of the first molars were embedded in paraffin or Araldite. Paraffin-sections were stained with hematoxylin/eosin for histomorphometry, or subjected to the silver impregnation method for morphological analysis of osteocyte cytoplasmic processes. Autophagy was analyzed by immunohistochemical detections of beclin-1, MAP-LC3α and p62, whereas apoptosis was evaluated by immunohistochemical detections of cleaved caspase-3 and BAX, TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labeling) method and by ultrastructural analysis. Araldite-semithin sections were subjected to the Sudan-black method for detection of lipids. OVX-basal group showed high frequency of caspase-3-, TUNEL- and p62-positive osteocytes accompanied with low frequency of beclin-1- and MAP-LC3α-positive osteocytes. At 45 days, OVXE group exhibited higher number of osteocytes, higher frequency of beclin-1- and MAP-LC3α-positive osteocytes, and lower frequency of caspase-3, BAX-, TUNEL- and p62-positive osteocytes than OVX group. Significant reduction in bone area was observed in the OVX compared to OVXE and SHAM groups. The highest frequency of Sudan-Black-positive osteocytes and osteocytes with scarce cytoplasmic processes, or showing apoptotic features were mainly observed in OVX groups. Our results indicate that estrogen deficiency decreases autophagy and increases apoptosis, whereas estrogen replacement enhances osteocyte viability by inhibiting apoptosis and maintaining autophagy in alveolar process osteocytes. These results suggest that the anti-apoptotic effect of estrogen may be, at least in part, related to autophagy regulation in osteocytes.
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Affiliation(s)
- Rinaldo Florencio-Silva
- Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departamento de Morfologia e Genética, Disciplina de Histologia e Biologia Estrutural, São Paulo, SP, Brazil
| | - Gisela R S Sasso
- Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departmento de Ginecologia, São Paulo, SP, Brazil
| | - Estela Sasso-Cerri
- São Paulo State University (UNESP), School of Dentistry, Araraquara - Laboratory of Histology and Embryology, Araraquara, SP, Brazil
| | - Manuel J Simões
- Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departamento de Morfologia e Genética, Disciplina de Histologia e Biologia Estrutural, São Paulo, SP, Brazil
| | - Paulo S Cerri
- São Paulo State University (UNESP), School of Dentistry, Araraquara - Laboratory of Histology and Embryology, Araraquara, SP, Brazil.
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139
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Lounis MA, Bergeron KF, Burhans MS, Ntambi JM, Mounier C. Oleate activates SREBP-1 signaling activity in SCD1-deficient hepatocytes. Am J Physiol Endocrinol Metab 2017; 313:E710-E720. [PMID: 28851735 PMCID: PMC5814596 DOI: 10.1152/ajpendo.00151.2017] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 08/01/2017] [Accepted: 08/15/2017] [Indexed: 01/06/2023]
Abstract
Stearoyl-CoA desaturase-1 (SCD1) is a key player in lipid metabolism. SCD1 catalyzes the synthesis of monounsaturated fatty acids (MUFA). MUFA are then incorporated into triacylglycerols and phospholipids. Previous studies have shown that Scd1 deficiency in mice induces metabolic changes in the liver characterized by a decrease in de novo lipogenesis and an increase in β-oxidation. Interestingly, Scd1-deficient mice show a decrease in the expression and maturation of the principal lipogenic transcription factor sterol receptor element binding protein-1 (SREBP-1). The mechanisms mediating this effect on de novo lipogenesis and β-oxidation have not been fully elucidated. We evaluated the role of SCD1 on de novo lipogenesis and β-oxidation in HepG2 cells. We also used Scd1-deficient mice and two strains of transgenic mice that produce either oleate (GLS5) or palmitoleate (GLS3) in a liver-specific manner. We demonstrate that the expression of β-oxidation markers increases in SCD1-deficient hepatocytes and suggest that this is due to an increase in cellular polyunsaturated fatty acid content. We also show that the changes in the level of SREBP-1 expression, for both the precursor and the mature forms, are mainly due to the lack of oleate in SCD1-deficient hepatocytes. Indeed, oleate treatment of cultured HepG2 cells or hepatic oleate production in chow-fed GLS5 mice can restore SREBP-1 expression and increase hepatic de novo lipogenesis. Finally, we show that oleate specifically increases SREBP-1 nuclear accumulation, suggesting a central role for oleate in SREBP-1 signaling activity.
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Affiliation(s)
- Mohamed A Lounis
- BioMed Research Center, Biological Sciences Department, University of Quebec in Montreal, Montreal, Quebec, Canada
| | - Karl-F Bergeron
- BioMed Research Center, Biological Sciences Department, University of Quebec in Montreal, Montreal, Quebec, Canada
| | - Maggie S Burhans
- Nutritional Sciences Department, University of Wisconsin-Madison, Madison, Wisconsin; and
| | - James M Ntambi
- Nutritional Sciences Department, University of Wisconsin-Madison, Madison, Wisconsin; and
- Biochemistry Department, University of Wisconsin-Madison, Madison, Wisconsin
| | - Catherine Mounier
- BioMed Research Center, Biological Sciences Department, University of Quebec in Montreal, Montreal, Quebec, Canada;
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140
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Melatonin promotes triacylglycerol accumulation via MT2 receptor during differentiation in bovine intramuscular preadipocytes. Sci Rep 2017; 7:15080. [PMID: 29118419 PMCID: PMC5678110 DOI: 10.1038/s41598-017-12780-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 09/14/2017] [Indexed: 12/22/2022] Open
Abstract
Melatonin (N-acetyl-5-methoxytryptamine) is a derivative of tryptophan which is produced and secreted mainly by the pineal gland and regulates a variety of important central and peripheral actions. To examine the potential effects of melatonin on the proliferation and differentiation of bovine intramuscular preadipocytes (BIPs), BIPs were incubated with different concentrations of melatonin. Melatonin supplementation at 1 mM significantly increased peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein (C/EBP) β, and C/EBPα expression and promoted the differentiation of BIPs into adipocytes with large lipid droplets and high cellular triacylglycerol (TAG) levels. Melatonin also significantly enhanced lipolysis and up-regulated the expression of lipolytic genes and proteins, including hormone sensitive lipase (HSL), adipocyte triglyceride lipase (ATGL), and perilipin 1 (PLIN1). Moreover, melatonin reduced intracellular reactive oxygen species (ROS) levels by increasing the expression levels and activities of superoxide dismutase 1 (SOD1) and glutathione peroxidase 4 (GPX4). Finally, the positive effects of melatonin on adipogenesis, lipolysis, and redox status were reversed by treatment with luzindole, anantagonist of nonspecific melatonin receptors 1 (MT1) and 2 (MT2), and 4-phenyl-2-propionamidotetraline (4P-PDOT), a selective MT2 antagonist. These results reveal that melatonin promotes TAG accumulation via MT2 receptor during differentiation in BIPs.
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141
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Prudovsky I, Anunciado-Koza RP, Jacobs CG, Kacer D, Siviski ME, Koza RA. Mesoderm-specific transcript localization in the ER and ER-lipid droplet interface supports a role in adipocyte hypertrophy. J Cell Biochem 2017; 119:2636-2645. [PMID: 29058774 DOI: 10.1002/jcb.26429] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/17/2017] [Indexed: 01/16/2023]
Abstract
Highly variable expression of mesoderm-specific transcript (Mest) in adipose tissue among genetically homogeneous mice fed an obesogenic diet, and its positive association with fat mass expansion, suggests that Mest is an epigenetic determinant for the development of obesity. Although the mechanisms by which MEST augments fat accumulation in adipocytes have not been elucidated, it has sequence homology and catalytic peptide motifs which suggests that it functions as an epoxide hydrolase or as a glycerol- or acylglycerol-3-phosphate acyltransferase. To better understand MEST function, detailed studies were performed to precisely define the intracellular organelle localization of MEST using immunofluorescence confocal microscopy. Lentiviral-mediated expression of a C-terminus Myc-DDK-tagged MEST fusion protein expressed in 3T3-L1 preadipocytes/adipocytes, and ear-derived mesenchymal stem cells (EMSC) from mice was observed in the endoplasmic reticulum (ER) membranes and is consistent with previous studies showing endogenous MEST in the membrane fraction of adipose tissue. MEST was not associated with the Golgi apparatus or mitochondria; however, frequent contacts were observed between MEST-positive ER and mitochondria. MEST-positive domains were also shown on the plasma membrane (PM) of non-permeabilized cells but they did not co-localize with ER-PM bridges. Post-adipogenic differentiated 3T3-L1 adipocytes and EMSC showed significant co-localization of MEST with the lipid droplet surface marker perilipin at contact points between the ER and lipid droplet. Identification of MEST as an ER-specific protein that co-localizes with lipid droplets in cells undergoing adipogenic differentiation supports a function for MEST in the facilitation of lipid accumulation and storage in adipocytes.
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Affiliation(s)
- Igor Prudovsky
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine.,The Graduate School of Biomedical Science and Engineering, University of Maine, Orono, Maine
| | - Rea P Anunciado-Koza
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
| | - Chester G Jacobs
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
| | - Doreen Kacer
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
| | - Matthew E Siviski
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine.,The Graduate School of Biomedical Science and Engineering, University of Maine, Orono, Maine
| | - Robert A Koza
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine.,The Graduate School of Biomedical Science and Engineering, University of Maine, Orono, Maine
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142
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Mirheydari M, Mann EK, Kooijman EE. Interaction of a model apolipoprotein, apoLp-III, with an oil-phospholipid interface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:396-406. [PMID: 29030246 DOI: 10.1016/j.bbamem.2017.10.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/22/2017] [Accepted: 10/08/2017] [Indexed: 01/29/2023]
Abstract
Lipid droplets are "small" organelles that play an important role in de novo synthesis of new membrane, and steroid hormones, as well as in energy storage. The way proteins interact specifically with the oil-(phospho-)lipid monolayer interface of lipid droplets is a relatively unexplored but crucial question. Here, we use our home built liquid droplet tensiometer to mimic intracellular lipid droplets and study protein-lipid interactions at this interface. As model neutral lipid binding protein, we use apoLp-III, an amphipathic α-helix bundle protein. This domain is also found in proteins from the perilipin family and in apoE. Protein binding to the monolayer is studied by the decrease in the oil/water surface tension. Previous work used POPC (one of the major lipids found on lipid droplets) to form the phospholipid monolayer on the triolein surface. Here we expand this work by incorporating other lipids with different physico-chemical properties to study the effect of charge and lipid head-group size. This study sheds light on the affinity of this important protein domain to interact with lipids.
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Affiliation(s)
- Mona Mirheydari
- Physics Department, Kent State University, Kent, OH 44242, United States.
| | - Elizabeth K Mann
- Physics Department, Kent State University, Kent, OH 44242, United States
| | - Edgar E Kooijman
- Department of Biological Sciences, Kent State University, Kent, OH 44242, United States
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143
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Solovchenko A, Neverov K. Carotenogenic response in photosynthetic organisms: a colorful story. PHOTOSYNTHESIS RESEARCH 2017; 133:31-47. [PMID: 28251441 DOI: 10.1007/s11120-017-0358-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 02/13/2017] [Indexed: 05/16/2023]
Abstract
Carotenoids are a diverse group of terpenoid pigments ubiquitous in and essential for functioning of phototrophs. Most of the researchers in the field are focused on the primary carotenoids serving light harvesting, photoprotection, and supporting the structural integrity of the photosynthetic apparatus (PSA) within the thylakoid membranes. A distinct group of the pigments functionally and structurally uncoupled from the PSA and accumulating outside of the thylakoids is called secondary carotenoids. Induction of the biosynthesis and massive accumulation of the latter termed as secondary carotenogenesis and carotenogenic response (CR), respectively, is a major though insufficiently studied stress response discovered in many phototrophic organisms ranging from single-celled algae to terrestrial higher plants. The CR protects cell by means of optical shielding of cell structures vulnerable photodamage, consumption of potentially harmful dioxygen, augmenting sink capacity of photoassimilates, and exerting an antioxidant effect. The secondary carotenoids exhibit a remarkable photostability in situ. Therefore, the CR-based photoprotective mechanism, unlike, e.g., antioxidant enzyme-based protection in the chloroplast, does not require continuous investment of energy and metabolites making it highly suitable for long-term stress acclimation in phototrophs. Capability of the CR determines the strategy of acclimation of photosynthetic organisms to different stresses such as excessive irradiance, drought, extreme temperatures, and salinities. Build-up of the CR might be accompanied by gradual disengagement of 'classical' active (energy-dependent) photoprotective mechanisms such as non-photochemical quenching. In addition to that, the CR has great ecological significance. Illustrious examples of this are extremely stress-tolerant 'snow' algae and conifer species developing red coloration during winter. The CR has also considerable practical implications since the secondary carotenoids exert a plethora of beneficial effects on human and animal health. The carotenogenic microalgae are the richest biotechnological sources of natural value-added carotenoids such as astaxanthin and β-carotene. In the present review, we summarize current functional, mechanistic, and ecological insights into the CR in a broad range of organisms suggesting that it is obviously more widespread and important stress response than it is currently thought to be.
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Affiliation(s)
- Alexei Solovchenko
- Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia, 119234.
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276.
| | - Konstantin Neverov
- Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia, 119234
- A.N.Bach Institute of Biochemistry, Biotechnology Research Center, Russian Academy of Sciences, Moscow, Russia, 117071
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144
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Gavgiotaki E, Filippidis G, Markomanolaki H, Kenanakis G, Agelaki S, Georgoulias V, Athanassakis I. Distinction between breast cancer cell subtypes using third harmonic generation microscopy. JOURNAL OF BIOPHOTONICS 2017; 10:1152-1162. [PMID: 27753229 DOI: 10.1002/jbio.201600173] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 09/10/2016] [Accepted: 09/30/2016] [Indexed: 06/06/2023]
Abstract
Third Harmonic Generation (THG) microscopy as a non-invasive, label free imaging methodology, allows linkage of lipid profiles with various breast cancer cells. The collected THG signal arise mostly from the lipid droplets and the membrane lipid bilayer. Quantification of THG signal can accurately distinguish HER2-positive cells. Further analysis using Fourier transform infrared (FTIR) spectra reveals cancer-specific profiles, correlating lipid raft-corresponding spectra to THG signal, associating thus THG to chemical information. THG imaging of a cancer cell.
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Affiliation(s)
- Evangelia Gavgiotaki
- Institute of Electronic Structure and Laser, Foundation for Research and Technology, Heraklion, 71110, Crete, Greece
- Medical School, University of Crete, Heraklion, 71003, Crete, Greece
| | - George Filippidis
- Institute of Electronic Structure and Laser, Foundation for Research and Technology, Heraklion, 71110, Crete, Greece
| | | | - George Kenanakis
- Institute of Electronic Structure and Laser, Foundation for Research and Technology, Heraklion, 71110, Crete, Greece
| | - Sofia Agelaki
- Medical School, University of Crete, Heraklion, 71003, Crete, Greece
| | | | - Irene Athanassakis
- Department of Biology, University of Crete, Heraklion, 71409, Crete, Greece
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145
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Tirinato L, Pagliari F, Limongi T, Marini M, Falqui A, Seco J, Candeloro P, Liberale C, Di Fabrizio E. An Overview of Lipid Droplets in Cancer and Cancer Stem Cells. Stem Cells Int 2017; 2017:1656053. [PMID: 28883835 PMCID: PMC5572636 DOI: 10.1155/2017/1656053] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 06/08/2017] [Accepted: 07/05/2017] [Indexed: 02/06/2023] Open
Abstract
For decades, lipid droplets have been considered as the main cellular organelles involved in the fat storage, because of their lipid composition. However, in recent years, some new and totally unexpected roles have been discovered for them: (i) they are active sites for synthesis and storage of inflammatory mediators, and (ii) they are key players in cancer cells and tissues, especially in cancer stem cells. In this review, we summarize the main concepts related to the lipid droplet structure and function and their involvement in inflammatory and cancer processes.
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Affiliation(s)
- L. Tirinato
- German Cancer Research Center (DKFZ), Heidelberg, Baden-Württemberg, Germany
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - F. Pagliari
- Biological and Environmental Science and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - T. Limongi
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
- Department of Applied Science and Technology (DISAT), Politecnico di Torino, Torino, Italy
| | - M. Marini
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - A. Falqui
- Biological and Environmental Science and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - J. Seco
- German Cancer Research Center (DKFZ), Heidelberg, Baden-Württemberg, Germany
| | - P. Candeloro
- BioNEM Lab, Department of Experimental and Clinical Medicine, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | - C. Liberale
- Biological and Environmental Science and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - E. Di Fabrizio
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
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146
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Rasineni K, Donohue TM, Thomes PG, Yang L, Tuma DJ, McNiven MA, Casey CA. Ethanol-induced steatosis involves impairment of lipophagy, associated with reduced Dynamin2 activity. Hepatol Commun 2017; 1:501-512. [PMID: 29152606 PMCID: PMC5678901 DOI: 10.1002/hep4.1063] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 05/11/2017] [Accepted: 05/17/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Lipid droplets (LDs), the organelles central to alcoholic steatosis, are broken down by lipophagy, a specialized form of autophagy. Here, we hypothesize that ethanol administration retards lipophagy by down-regulating Dynamin 2 (Dyn2), a protein that facilitates lysosome re-formation, contributing to hepatocellular steatosis. METHODS Primary hepatocytes were isolated from male Wistar rats fed Lieber-DeCarli control or EtOH liquid diets for 6-8 wk. Hepatocytes were incubated in complete medium (fed) or nutrient-free medium (fasting) with or without the Dyn2 inhibitor Dynasore or the Src inhibitor SU6656. Phosphorylated (active) forms of Src and Dyn2, and markers of autophagy were quantified by Western Blot. Co-localization of LDs-with autophagic machinery was determined by confocal microscopy. RESULTS In hepatocytes from pair-fed rats, LD breakdown was accelerated during fasting, as judged by smaller LDs and lower TG content when compared to hepatocytes in complete media. Fasting-induced TG loss in control hepatocytes was significantly blocked by either SU6656 or Dynasore. Compared to controls, hepatocytes from EtOH-fed rats had 66% and 40% lower content of pSrc and pDyn2, respectively, coupled with lower rate of fasting-induced TG loss. This slower rate of fasting-induced TG loss was blocked in cells co-incubated with Dynasore. Microscopic examination of EtOH-fed rat hepatocytes revealed increased co-localization of the autophagosome marker LC3 on LDs with a concomitant decrease in lysosome marker LAMP1. Whole livers and LD fractions of EtOH-fed rats exhibited simultaneous increase in LC3II and p62 over that of controls, indicating a block in lipophagy. CONCLUSION Chronic ethanol administration slowed the rate of hepatocyte lipophagy, owing in part to lower levels of phosphorylated Src kinase available to activate its substrate, Dyn2, thereby causing depletion of lysosomes for LD breakdown.
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Affiliation(s)
- Karuna Rasineni
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
| | - Terrence M. Donohue
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNE
- Department of Pathology and MicrobiologyCollege of Medicine, University of Nebraska Medical CenterOmahaNE
- Center for Environmental ToxicologyCollege of Public Health, University of Nebraska Medical CenterOmahaNE
| | - Paul G. Thomes
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
| | - Li Yang
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
- Tongji HospitalTongji University School of MedicineShanghaiChina
| | - Dean J. Tuma
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
| | - Mark A. McNiven
- Department of Biochemistry and Molecular BiologyMayo Clinic College of MedicineRochesterMN
| | - Carol A. Casey
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNE
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147
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The Role of Lipid Bodies in the Microglial Aging Process and Related Diseases. Neurochem Res 2017; 42:3140-3148. [PMID: 28699057 DOI: 10.1007/s11064-017-2351-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 02/22/2017] [Accepted: 07/07/2017] [Indexed: 01/08/2023]
Abstract
Lipid bodies (LBs) have long been considered to be organelles merely for the storage of neutral lipids. However, recent studies have shown the significance of LBs in signal transduction, especially in glial cells, including microglia. Microglial cells are the resident mononuclear phagocytes in the central nervous system and have a close relationship with the aging process and neurodegenerative diseases. Evidence suggests that LBs accumulate and are remodeled during the aging process and the development of neuroinflammatory conditions. However, the mechanisms underlying the formation of LBs under these conditions and the mechanism by which LB remodeling influences the progression of neurodegeneration remain to be clarified. In this review, we have summarized the findings from recent studies with the aim of further elucidating these issues.
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148
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Ben M'barek K, Ajjaji D, Chorlay A, Vanni S, Forêt L, Thiam AR. ER Membrane Phospholipids and Surface Tension Control Cellular Lipid Droplet Formation. Dev Cell 2017; 41:591-604.e7. [PMID: 28579322 DOI: 10.1016/j.devcel.2017.05.012] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 04/08/2017] [Accepted: 05/10/2017] [Indexed: 10/19/2022]
Abstract
Cells convert excess energy into neutral lipids that are made in the endoplasmic reticulum (ER) bilayer. The lipids are then packaged into spherical or budded lipid droplets (LDs) covered by a phospholipid monolayer containing proteins. LDs play a key role in cellular energy metabolism and homeostasis. A key unanswered question in the life of LDs is how they bud off from the ER. Here, we tackle this question by studying the budding of artificial LDs from model membranes. We find that the bilayer phospholipid composition and surface tension are key parameters of LD budding. Phospholipids have differential LD budding aptitudes, and those inducing budding decrease the bilayer tension. We observe that decreasing tension favors the egress of neutral lipids from the bilayer and LD budding. In cells, budding conditions favor the formation of small LDs. Our discovery reveals the importance of altering ER physical chemistry for controlled cellular LD formation.
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Affiliation(s)
- Kalthoum Ben M'barek
- Laboratoire de Physique Statistique, Département de Physique de l'ENS, École Normale Supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Université Paris 06, CNRS, 75005 Paris, France
| | - Dalila Ajjaji
- Laboratoire de Physique Statistique, Département de Physique de l'ENS, École Normale Supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Université Paris 06, CNRS, 75005 Paris, France
| | - Aymeric Chorlay
- Laboratoire de Physique Statistique, Département de Physique de l'ENS, École Normale Supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Université Paris 06, CNRS, 75005 Paris, France
| | - Stefano Vanni
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Lionel Forêt
- Laboratoire de Physique Statistique, Département de Physique de l'ENS, École Normale Supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Université Paris 06, CNRS, 75005 Paris, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique Statistique, Département de Physique de l'ENS, École Normale Supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Université Paris 06, CNRS, 75005 Paris, France.
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149
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Nolan SJ, Romano JD, Coppens I. Host lipid droplets: An important source of lipids salvaged by the intracellular parasite Toxoplasma gondii. PLoS Pathog 2017; 13:e1006362. [PMID: 28570716 PMCID: PMC5469497 DOI: 10.1371/journal.ppat.1006362] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 06/13/2017] [Accepted: 04/18/2017] [Indexed: 12/13/2022] Open
Abstract
Toxoplasma is an obligate intracellular parasite that replicates in mammalian cells within a parasitophorous vacuole (PV) that does not fuse with any host organelles. One mechanism developed by the parasite for nutrient acquisition is the attraction of host organelles to the PV. Here, we examined the exploitation of host lipid droplets (LD), ubiquitous fat storage organelles, by Toxoplasma. We show that Toxoplasma replication is reduced in host cells that are depleted of LD, or impaired in TAG lipolysis or fatty acid catabolism. In infected cells, the number of host LD and the expression of host LD-associated genes (ADRP, DGAT2), progressively increase until the onset of parasite replication. Throughout infection, the PV are surrounded by host LD. Toxoplasma is capable of accessing lipids stored in host LD and incorporates these lipids into its own membranes and LD. Exogenous addition of oleic acid stimulates LD biogenesis in the host cell and results in the overaccumulation of neutral lipids in very large LD inside the parasite. To access LD-derived lipids, Toxoplasma intercepts and internalizes within the PV host LD, some of which remaining associated with Rab7, which become wrapped by an intravacuolar network of membranes (IVN). Mutant parasites impaired in IVN formation display diminished capacity of lipid uptake from host LD. Moreover, parasites lacking an IVN-localized phospholipase A2 are less proficient in salvaging lipids from host LD in the PV, suggesting a major contribution of the IVN for host LD processing in the PV and, thus lipid content release. Interestingly, gavage of parasites with lipids unveils, for the first time, the presence in Toxoplasma of endocytic-like structures containing lipidic material originating from the PV lumen. This study highlights the reliance of Toxoplasma on host LD for its intracellular development and the parasite’s capability in scavenging neutral lipids from host LD. Toxoplasma is an obligate intracellular pathogen that multiplies in mammalian cells within a specialized compartment, named the parasitophorous vacuole (PV). While the vacuole does not fuse with host organelles, the parasite scavenges nutrients, including lipids, from these compartments. Present in all mammalian cells, lipid droplets (LD) are dynamic structures that store neutral lipids. Whether Toxoplasma targets host LD for their nutritional content remains to be investigated. We demonstrate that the parasite relies on host LD lipids and their lipolytic enzymatic activities to grow. Toxoplasma salvages lipids from host LD, which surround the PV and, at least partially, accesses these lipids by intercepting and engulfing within the PV host Rab7-associated LD. In the PV lumen, a parasite lipase releases lipids from host LD, thus making them available to the parasite. Exogenous addition of fatty acids stimulates host LD biogenesis and results in the accumulation of enlarged LD containing neutral lipids in Toxoplasma. This study highlights the ability of Toxoplasma to scavenge and store lipids from host LD. Interestingly, exposure of Toxoplasma to excess lipids reveals, for the first time, coated invaginations of the parasite’s plasma membrane and cytoplasmic vesicles containing lipids originating from the PV lumen, potentially involved in endocytosis.
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Affiliation(s)
- Sabrina J. Nolan
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Julia D. Romano
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
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150
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Lipid droplets accumulation and other biochemical changes induced in the fungal pathogen Ustilago maydis under nitrogen-starvation. Arch Microbiol 2017; 199:1195-1209. [PMID: 28550409 DOI: 10.1007/s00203-017-1388-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 04/28/2017] [Accepted: 05/16/2017] [Indexed: 10/19/2022]
Abstract
In many organisms, the growth under nitrogen-deprivation or a poor nitrogen source impacts on the carbon flow distribution and causes accumulation of neutral lipids, which are stored as lipid droplets (LDs). Efforts are in progress to find the mechanism of LDs synthesis and degradation, and new organisms capable of accumulating large amounts of lipids for biotechnological applications. In this context, when Ustilago maydis was cultured in the absence of a nitrogen source, there was a large accumulation of lipid bodies containing mainly triacylglycerols. The most abundant fatty acids in lipid bodies at the stationary phase were palmitic, linoleic, and oleic acids, and they were synthesized de novo by the fatty-acid synthase. In regard to the production of NADPH for the synthesis of fatty acids, the cytosolic NADP+-dependent isocitrate dehydrogenase and the glucose-6-phosphate and 6-phosphogluconate dehydrogenases couple showed the highest specific activities, with a lower activity of the malic enzyme. The ATP-citrate lyase activity was not detected in any of the culture conditions, which points to a different mechanism for the transfer of acetyl-CoA into the cytosol. Protein and RNA contents decreased when U. maydis was grown without a nitrogen source. Due to the significant accumulation of triacylglycerols and the particular composition of fatty acids, U. maydis can be considered an alternative model for biotechnological applications.
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