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Schott MB, Rozeveld CN, Bhatt S, Crossman B, Krueger EW, Weller SG, Rasineni K, Casey CA, McNiven MA. Ethanol disrupts hepatocellular lipophagy by altering Rab5-centric LD-lysosome trafficking. Hepatol Commun 2024; 8:e0446. [PMID: 38780316 PMCID: PMC11124685 DOI: 10.1097/hc9.0000000000000446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 02/23/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Previous reports suggest that lipid droplets (LDs) in the hepatocyte can be catabolized by a direct engulfment from nearby endolysosomes (microlipophagy). Further, it is likely that this process is compromised by chronic ethanol (EtOH) exposure leading to hepatic steatosis. This study investigates the hepatocellular machinery supporting microlipophagy and EtOH-induced alterations in this process with a focus on the small, endosome-associated, GTPase Rab5. METHODS AND RESULTS Here we report that this small Ras-related GTPase is a resident component of LDs, and its activity is important for hepatocellular LD-lysosome proximity and physical interactions. We find that Rab5 siRNA knockdown causes an accumulation of LDs in hepatocytes by inhibiting lysosome dependent LD catabolism. Importantly, Rab5 appears to support this process by mediating the recruitment of early endosomal and or multivesicular body compartments to the LD surface before lysosome fusion. Interestingly, while wild-type or a constituently active GTPase form (Q79L) of Rab5 supports LD-lysosome transport, this process is markedly reduced in cells expressing a GTPase dead (S34N) Rab5 protein or in hepatocytes exposed to chronic EtOH. CONCLUSIONS These findings support the novel premise of an early endosomal/multivesicular body intermediate compartment on the LD surface that provides a "docking" site for lysosomal trafficking, not unlike the process that occurs during the hepatocellular degradation of endocytosed ligands that is also known to be compromised by EtOH exposure.
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Affiliation(s)
- Micah B. Schott
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Cody N. Rozeveld
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Saumya Bhatt
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Bridget Crossman
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
| | - Eugene W. Krueger
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
| | - Shaun G. Weller
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
| | - Karuna Rasineni
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Veterans’ Affairs, VA-Nebraska-Western Iowa Health Care System, Omaha, Nebraska, USA
| | - Carol A. Casey
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Veterans’ Affairs, VA-Nebraska-Western Iowa Health Care System, Omaha, Nebraska, USA
| | - Mark A. McNiven
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
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2
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Cullen JK, Yap PY, Ferguson B, Bruce ZC, Koyama M, Handoko H, Hendrawan K, Simmons JL, Brooks KM, Johns J, Wilson ES, de Souza MMA, Broit N, Stewart P, Shelley D, McMahon T, Ogbourne SM, Nguyen TH, Lim YC, Pagani A, Appendino G, Gordon VA, Reddell PW, Boyle GM, Parsons PG. Tigilanol tiglate is an oncolytic small molecule that induces immunogenic cell death and enhances the response of both target and non-injected tumors to immune checkpoint blockade. J Immunother Cancer 2024; 12:e006602. [PMID: 38658031 PMCID: PMC11043783 DOI: 10.1136/jitc-2022-006602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2024] [Indexed: 04/26/2024] Open
Abstract
BACKGROUND Tigilanol tiglate (TT) is a protein kinase C (PKC)/C1 domain activator currently being developed as an intralesional agent for the treatment of various (sub)cutaneous malignancies. Previous work has shown that intratumoral (I.T.) injection of TT causes vascular disruption with concomitant tumor ablation in several preclinical models of cancer, in addition to various (sub)cutaneous tumors presenting in the veterinary clinic. TT has completed Phase I dose escalation trials, with some patients showing signs of abscopal effects. However, the exact molecular details underpinning its mechanism of action (MoA), together with its immunotherapeutic potential in oncology remain unclear. METHODS A combination of microscopy, luciferase assays, immunofluorescence, immunoblotting, subcellular fractionation, intracellular ATP assays, phagocytosis assays and mixed lymphocyte reactions were used to probe the MoA of TT in vitro. In vivo studies with TT used MM649 xenograft, CT-26 and immune checkpoint inhibitor refractory B16-F10-OVA tumor bearing mice, the latter with or without anti-programmed cell death 1 (PD-1)/anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) mAb treatment. The effect of TT at injected and non-injected tumors was also assessed. RESULTS Here, we show that TT induces the death of endothelial and cancer cells at therapeutically relevant concentrations via a caspase/gasdermin E-dependent pyroptopic pathway. At therapeutic doses, our data demonstrate that TT acts as a lipotoxin, binding to and promoting mitochondrial/endoplasmic reticulum (ER) dysfunction (leading to unfolded protein responsemt/ER upregulation) with subsequent ATP depletion, organelle swelling, caspase activation, gasdermin E cleavage and induction of terminal necrosis. Consistent with binding to ER membranes, we found that TT treatment promoted activation of the integrated stress response together with the release/externalization of damage-associated molecular patterns (HMGB1, ATP, calreticulin) from cancer cells in vitro and in vivo, characteristics indicative of immunogenic cell death (ICD). Confirmation of ICD in vivo was obtained through vaccination and rechallenge experiments using CT-26 colon carcinoma tumor bearing mice. Furthermore, TT also reduced tumor volume, induced immune cell infiltration, as well as improved survival in B16-F10-OVA tumor bearing mice when combined with immune checkpoint blockade. CONCLUSIONS These data demonstrate that TT is an oncolytic small molecule with multiple targets and confirms that cell death induced by this compound has the potential to augment antitumor responses to immunotherapy.
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Affiliation(s)
- Jason K Cullen
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
- The University of Queensland, Brisbane, Queensland, Australia
- QBiotics Group Limited, Brisbane, Queensland, Australia
| | - Pei-Yi Yap
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Blake Ferguson
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Zara C Bruce
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Motoko Koyama
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Herlina Handoko
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Kevin Hendrawan
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Jacinta L Simmons
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
- The University of Queensland, Brisbane, Queensland, Australia
| | - Kelly M Brooks
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Jenny Johns
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Emily S Wilson
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | | | - Natasa Broit
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Praphaporn Stewart
- University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
| | - Daniel Shelley
- University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
| | - Tracey McMahon
- University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
| | - Steven M Ogbourne
- QBiotics Group Limited, Brisbane, Queensland, Australia
- University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
| | - Tam Hong Nguyen
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Yi Chieh Lim
- Danish Cancer Society Research Centre, Copenhagen DK, Denmark
| | - Alberto Pagani
- Dipartimento di Scienze del Farmaco, Università Degli Studi del Piemonte Orientale, Novara, Italy
| | - Giovanni Appendino
- Dipartimento di Scienze del Farmaco, Università Degli Studi del Piemonte Orientale, Novara, Italy
| | | | | | - Glen M Boyle
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
- The University of Queensland, Brisbane, Queensland, Australia
| | - Peter G Parsons
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
- QBiotics Group Limited, Brisbane, Queensland, Australia
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3
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Brownstein AJ, Veliova M, Acin-Perez R, Villalobos F, Petcherski A, Tombolato A, Liesa M, Shirihai OS. Mitochondria isolated from lipid droplets of white adipose tissue reveal functional differences based on lipid droplet size. Life Sci Alliance 2024; 7:e202301934. [PMID: 38056907 PMCID: PMC10700548 DOI: 10.26508/lsa.202301934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 12/08/2023] Open
Abstract
Recent studies in brown adipose tissue (BAT) described a unique subpopulation of mitochondria bound to lipid droplets (LDs), which were termed PeriDroplet Mitochondria (PDM). PDM can be isolated from BAT by differential centrifugation and salt washes. Contrary to BAT, this approach has so far not led to the successful isolation of PDM from white adipose tissue (WAT). Here, we developed a method to isolate PDM from WAT with high yield and purity by an optimized proteolytic treatment that preserves the respiratory function of mitochondria. Using this approach, we show that, contrary to BAT, WAT PDM have lower respiratory and ATP synthesis capacities compared with WAT cytoplasmic mitochondria (CM). Furthermore, by isolating PDM from LDs of different sizes, we found a negative correlation between LD size and the respiratory capacity of their PDM in WAT. Thus, our new isolation method reveals tissue-specific characteristics of PDM and establishes the existence of heterogeneity in PDM function determined by LD size.
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Affiliation(s)
- Alexandra J Brownstein
- David Geffen School of Medicine, Department of Medicine (Endocrinology) and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
- Molecular Cellular Integrative Physiology Interdepartmental Graduate Program, University of California, Los Angeles, CA, USA
| | - Michaela Veliova
- David Geffen School of Medicine, Department of Medicine (Endocrinology) and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Rebeca Acin-Perez
- David Geffen School of Medicine, Department of Medicine (Endocrinology) and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Frankie Villalobos
- David Geffen School of Medicine, Department of Medicine (Endocrinology) and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Anton Petcherski
- David Geffen School of Medicine, Department of Medicine (Endocrinology) and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Alberto Tombolato
- David Geffen School of Medicine, Department of Medicine (Endocrinology) and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Marc Liesa
- David Geffen School of Medicine, Department of Medicine (Endocrinology) and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
- Department of Cells and Tissues, Institut de Biologia Molecular de Barcelona, IBMB, CSIC, Barcelona, Spain
| | - Orian S Shirihai
- David Geffen School of Medicine, Department of Medicine (Endocrinology) and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
- Molecular Cellular Integrative Physiology Interdepartmental Graduate Program, University of California, Los Angeles, CA, USA
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4
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Speer NO, Braun RJ, Reynolds EG, Brudnicka A, Swanson JM, Henne WM. Tld1 is a regulator of triglyceride lipolysis that demarcates a lipid droplet subpopulation. J Cell Biol 2024; 223:e202303026. [PMID: 37889293 PMCID: PMC10609110 DOI: 10.1083/jcb.202303026] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 09/09/2023] [Accepted: 10/06/2023] [Indexed: 10/28/2023] Open
Abstract
Cells store lipids in the form of triglyceride (TG) and sterol ester (SE) in lipid droplets (LDs). Distinct pools of LDs exist, but a pervasive question is how proteins localize to and convey functions to LD subsets. Here, we show that the yeast protein YDR275W/Tld1 (for TG-associated LD protein 1) localizes to a subset of TG-containing LDs and reveal it negatively regulates lipolysis. Mechanistically, Tld1 LD targeting requires TG, and it is mediated by two distinct hydrophobic regions (HRs). Molecular dynamics simulations reveal that Tld1's HRs interact with TG on LDs and adopt specific conformations on TG-rich LDs versus SE-rich LDs in yeast and human cells. Tld1-deficient yeast display no defect in LD biogenesis but exhibit elevated TG lipolysis dependent on lipase Tgl3. Remarkably, overexpression of Tld1, but not LD protein Pln1/Pet10, promotes TG accumulation without altering SE pools. Finally, we find that Tld1-deficient cells display altered LD mobilization during extended yeast starvation. We propose that Tld1 senses TG-rich LDs and regulates lipolysis on LD subpopulations.
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Affiliation(s)
- Natalie Ortiz Speer
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - R. Jay Braun
- Department of Chemistry, University of Utah, Salt Lake City, UT, USA
| | - Emma Grace Reynolds
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Alicja Brudnicka
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | - W. Mike Henne
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
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5
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Engin A. Lipid Storage, Lipolysis, and Lipotoxicity in Obesity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1460:97-129. [PMID: 39287850 DOI: 10.1007/978-3-031-63657-8_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2024]
Abstract
The ratio of free fatty acid (FFA) turnover decreases significantly with the expansion of white adipose tissue. Adipose tissue and dietary saturated fatty acid levels significantly correlate with an increase in fat cell size and number. The G0/G1 switch gene 2 increases lipid content in adipocytes and promotes adipocyte hypertrophy through the restriction of triglyceride (triacylglycerol: TAG) turnover. Hypoxia in obese adipose tissue due to hypertrophic adipocytes results in excess deposition of extracellular matrix (ECM) components. Cluster of differentiation (CD) 44, as the main receptor of the extracellular matrix component regulates cell-cell and cell-matrix interactions including diet-induced insulin resistance. Excess TAGs, sterols, and sterol esters are surrounded by the phospholipid monolayer surface and form lipid droplets (LDs). Once LDs are formed, they grow up because of the excessive amount of intracellular FFA stored and reach a final size. The ratio of FFA turnover/lipolysis decreases significantly with increases in the degree of obesity. Dysfunctional adipose tissue is unable to expand further to store excess dietary lipids, increased fluxes of plasma FFAs lead to ectopic fatty acid deposition and lipotoxicity. Reduced neo-adipogenesis and dysfunctional lipid-overloaded adipocytes are hallmarks of hypertrophic obesity linked to insulin resistance. Obesity-associated adipocyte death exhibits feature of necrosis-like programmed cell death. Adipocyte death is a prerequisite for the transition from hypertrophic to hyperplastic obesity. Increased adipocyte number in obesity has life-long effects on white adipose tissue mass. The positive correlation between the adipose tissue volume and magnetic resonance imaging proton density fat fraction estimation is used for characterization of the obesity phenotype, as well as the risk stratification and selection of appropriate treatment strategies. In obese patients with type 2 diabetes, visceral adipocytes exposed to chronic/intermittent hyperglycemia develop a new microRNAs' (miRNAs') expression pattern. Visceral preadipocytes memorize the effect of hyperglycemia via changes in miRNAs' expression profile and contribute to the progression of diabetic phenotype. Nonsteroidal anti-inflammatory drugs, metformin, and statins can be beneficial in treating the local or systemic consequences of white adipose tissue inflammation. Rapamycin inhibits leptin-induced LD formation. Collectively, in this chapter, the concept of adipose tissue remodeling in response to adipocyte death or adipogenesis, and the complexity of LD interactions with the other cellular organelles are reviewed. Furthermore, clinical perspective of fat cell turnover in obesity is also debated.
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Affiliation(s)
- Atilla Engin
- Faculty of Medicine, Department of General Surgery, Gazi University, Besevler, Ankara, Turkey.
- Mustafa Kemal Mah. 2137. Sok. 8/14, 06520, Cankaya, Ankara, Turkey.
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6
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Kumar M, Knapp JA, Gupta K, Ryan TA. Isolation and Lipidomic Profiling of Neuronal Lipid Droplets: Unveiling the Lipid Landscape for insights into Neurodegenerative Disorders. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571527. [PMID: 38168251 PMCID: PMC10760103 DOI: 10.1101/2023.12.13.571527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Recent advances have expanded the role of lipid droplets (LDs) beyond passive lipid storage, implicating their involvement in various metabolic processes across mammalian tissues. Neuronal LDs, long debated in existence, have been identified in several neural structures, raising questions about their contribution to neurodegenerative disorders. Elucidating the specific chemical makeup of these organelles within neurons is critical for understanding their implication in neural pathologies. This study outlines an improved methodology to stimulate and isolate mature LDs from cultured primary neurons, offering insights into their unique lipid-protein composition. Integrating this method with high-throughput techniques may unveil disease-specific alterations in lipid metabolism, providing avenues for potential therapeutic interventions.
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Affiliation(s)
- Mukesh Kumar
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Justin A Knapp
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Kallol Gupta
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, Maryland 20815, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
- Nanobiology Institute, Yale University, West Haven, CT 06516, USA
| | - Timothy A. Ryan
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, Maryland 20815, USA
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7
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Krohn J, Domart F, Do TT, Dresbach T. The synaptic vesicle protein Mover/TPRG1L is associated with lipid droplets in astrocytes. Glia 2023; 71:2799-2814. [PMID: 37539560 DOI: 10.1002/glia.24452] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 07/06/2023] [Accepted: 07/24/2023] [Indexed: 08/05/2023]
Abstract
Crucial brain functions such as neurotransmission, myelination, and signaling pose a high demand for lipids. Lipid dysregulation is associated with neuroinflammation and neurodegeneration. Astrocytes protect neurons from lipid induced damage by accumulating and metabolizing toxic lipids in organelles called lipid droplets (LDs). LDs have long been considered as lipid storage compartments in adipocytes, but less is known about their biogenesis and composition in the brain. In particular, proteins covering the LD surface are not yet fully identified. Here, we report that the presynaptic protein Mover/TPRG1L, which regulates the probability of neurotransmitter release in neurons, is a component of the LD coat in astrocytes. Using conventional and super-resolution microscopy, we demonstrate that Mover surrounds naive and oleic acid induced astrocytic LDs. We confirm the identity of astrocytic LDs using the neutral lipid stains Bodipy and LipidTox, as well as immunofluorescence for perilipin-2, a known component of the LD coat. In astrocytes, recombinant Mover was sufficient to induce an accumulation of LDs. Furthermore, we identified point mutations that abolish targeting to LDs and show similarities in the required binding sequences for association to the presynapse and LDs. Our results show that Mover is not only a presynaptic protein but also a candidate for LD regulation. This highlights the dual role of Mover in synaptic transmission and regulation of astrocytic LDs, which may be particularly important in the context of lipid-related neurological disorders.
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Affiliation(s)
- Jeremy Krohn
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Georg-August University of Göttingen, Göttingen, Germany
| | - Florelle Domart
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Georg-August University of Göttingen, Göttingen, Germany
| | - Thanh Thao Do
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Georg-August University of Göttingen, Göttingen, Germany
| | - Thomas Dresbach
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Georg-August University of Göttingen, Göttingen, Germany
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8
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Zhao P, Zhao Z, Yu Z, Chen L, Jin Y, Wu J, Ren Z. Application of synthetic lipid droplets in metabolic diseases. Clin Transl Med 2023; 13:e1441. [PMID: 37997538 PMCID: PMC10668006 DOI: 10.1002/ctm2.1441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 09/16/2023] [Accepted: 10/01/2023] [Indexed: 11/25/2023] Open
Abstract
BACKGROUND The study and synthesis of membrane organelles are becoming increasingly important, not only as simplified cellular models for corresponding molecular and metabolic studies but also for applications in synthetic biology of artificial cells and drug delivery vehicles. Lipid droplets (LDs) are central organelles in cellular lipid metabolism and are involved in almost all metabolic processes. Multiple studies have also demonstrated a high correlation between LDs and metabolic diseases. During these processes, LDs reveal a highly dynamic character, with their lipid fraction, protein composition and subcellular localisation constantly changing in response to metabolic demands. However, the molecular mechanisms underlying these functions have not been fully understood due to the limitations of cell biology approaches. Fortunately, developments in synthetic biology have provided a huge breakthrough for metabolism research, and methods for in vitro synthesis of LDs have been successfully established, with great advances in protein binding, lipid function, membrane dynamics and enzymatic reactions. AIMS AND METHODS In this review, we provide a comprehensive overview of the assembly and function of endogenous LDs, from the generation of lipid molecules to how they are assembled into LDs in the endoplasmic reticulum. In particular, we highlight two major classes of synthetic LD models for fabrication techniques and their recent advances in biology and explore their roles and challenges in achieving real applications of artificial LDs in the future.
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Affiliation(s)
- Pengxiang Zhao
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
- College of Animal Science and TechnologyShandong Agricultural UniversityTaianShandongP. R. China
| | - Zichen Zhao
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
| | - Ziwei Yu
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
| | - Lupeng Chen
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
| | - Yi Jin
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
| | - Jian Wu
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
- Frontiers Science Center for Animal Breeding and Sustainable ProductionWuhanHubeiP. R. China
| | - Zhuqing Ren
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
- Frontiers Science Center for Animal Breeding and Sustainable ProductionWuhanHubeiP. R. China
- Hubei Hongshan LaboratoryWuhanHubeiP. R. China
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9
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Speer NO, Braun RJ, Reynolds E, Brudnicka A, Swanson J, Henne WM. Tld1 is a novel regulator of triglyceride lipolysis that demarcates a lipid droplet subpopulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.07.531595. [PMID: 36945645 PMCID: PMC10028886 DOI: 10.1101/2023.03.07.531595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
Cells store lipids in the form of triglyceride (TG) and sterol-ester (SE) in lipid droplets (LDs). Distinct pools of LDs exist, but a pervasive question is how proteins localize to and convey functions to LD subsets. Here, we show the yeast protein YDR275W/Tld1 (for TG-associated LD protein 1) localizes to a subset of TG-containing LDs, and reveal it negatively regulates lipolysis. Mechanistically, Tld1 LD targeting requires TG, and is mediated by two distinct hydrophobic regions (HRs). Molecular dynamics simulations reveal Tld1 HRs interact with TG on LDs and adopt specific conformations on TG-rich LDs versus SE-rich LDs in yeast and human cells. Tld1-deficient yeast display no defect in LD biogenesis, but exhibit elevated TG lipolysis dependent on lipase Tgl3. Remarkably, over-expression of Tld1, but not LD protein Pln1/Pet10, promotes TG accumulation without altering SE pools. Finally, we find Tld1-deficient cells display altered LD mobilization during extended yeast starvation. We propose Tld1 senses TG-rich LDs and regulates lipolysis on LD subpopulations.
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10
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Dunn KJ, Berger AJ. Three-dimensional angular scattering simulations inform analysis of scattering from single cells. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:086501. [PMID: 37564163 PMCID: PMC10411915 DOI: 10.1117/1.jbo.28.8.086501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/16/2023] [Accepted: 07/21/2023] [Indexed: 08/12/2023]
Abstract
Significance Organelle sizes, which are indicative of cellular status, have implications for drug development and immunology research. At the single cell level, such information could be used to study the heterogeneity of cell response to drugs or pathogens. Aim Angularly resolved elastic light scattering is known to be sensitive to changes in organelle size distribution. We developed a Mie theory-based simulation of angular scattering from single cells to quantify the effects of noise on scattering and size estimates. Approach We simulated randomly sampled organelle sizes (drawn from a log normal distribution), interference between different organelles' scattering, and detector noise. We quantified each noise source's effect upon the estimated mean and standard deviation of organelle size distributions. Results The results demonstrate that signal-to-noise ratio in the angular scattering increased with the number of scatterers, cell area, and exposure time and decreased with the size distribution width. The error in estimating the mean of the size distributions remained below 5% for nearly all experimental parameters tested, but the widest size distribution tested (standard deviation of 600 nm) reached 20%. Conclusions The simulator revealed that sparse sampling of a broad size distribution can dominate the mismatch between actual and predicted size parameters. Alternative estimation strategies could reduce the discrepancy.
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Affiliation(s)
- Kaitlin J. Dunn
- University of Rochester, Institute of Optics, Rochester, New York, United States
| | - Andrew J. Berger
- University of Rochester, Institute of Optics, Rochester, New York, United States
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11
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Hammoudeh N, Soukkarieh C, Murphy DJ, Hanano A. Mammalian lipid droplets: structural, pathological, immunological and anti-toxicological roles. Prog Lipid Res 2023; 91:101233. [PMID: 37156444 DOI: 10.1016/j.plipres.2023.101233] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 04/30/2023] [Accepted: 05/05/2023] [Indexed: 05/10/2023]
Abstract
Mammalian lipid droplets (LDs) are specialized cytosolic organelles consisting of a neutral lipid core surrounded by a membrane made up of a phospholipid monolayer and a specific population of proteins that varies according to the location and function of each LD. Over the past decade, there have been significant advances in the understanding of LD biogenesis and functions. LDs are now recognized as dynamic organelles that participate in many aspects of cellular homeostasis plus other vital functions. LD biogenesis is a complex, highly-regulated process with assembly occurring on the endoplasmic reticulum although aspects of the underpinning molecular mechanisms remain elusive. For example, it is unclear how many enzymes participate in the biosynthesis of the neutral lipid components of LDs and how this process is coordinated in response to different metabolic cues to promote or suppress LD formation and turnover. In addition to enzymes involved in the biosynthesis of neutral lipids, various scaffolding proteins play roles in coordinating LD formation. Despite their lack of ultrastructural diversity, LDs in different mammalian cell types are involved in a wide range of biological functions. These include roles in membrane homeostasis, regulation of hypoxia, neoplastic inflammatory responses, cellular oxidative status, lipid peroxidation, and protection against potentially toxic intracellular fatty acids and lipophilic xenobiotics. Herein, the roles of mammalian LDs and their associated proteins are reviewed with a particular focus on their roles in pathological, immunological and anti-toxicological processes.
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Affiliation(s)
- Nour Hammoudeh
- Department of Animal Biology, Faculty of Sciences, University of Damascus, Damascus, Syria
| | - Chadi Soukkarieh
- Department of Animal Biology, Faculty of Sciences, University of Damascus, Damascus, Syria
| | - Denis J Murphy
- School of Applied Sciences, University of South Wales, Pontypridd, CF37 1DL, Wales, United Kingdom..
| | - Abdulsamie Hanano
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), P.O. Box 6091, Damascus, Syria..
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12
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Arumugam MK, Perumal SK, Rasineni K, Donohue TM, Osna NA, Kharbanda KK. Lipidomic Analysis of Liver Lipid Droplets after Chronic Alcohol Consumption with and without Betaine Supplementation. BIOLOGY 2023; 12:462. [PMID: 36979154 PMCID: PMC10045066 DOI: 10.3390/biology12030462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 03/04/2023] [Accepted: 03/08/2023] [Indexed: 03/19/2023]
Abstract
The earliest manifestation of alcohol-associated liver disease is hepatic steatosis, which is characterized by fat accumulation in specialized organelles called lipid droplets (LDs). Our previous studies reported that alcohol consumption elevates the numbers and sizes of LDs in hepatocytes, which is attenuated by simultaneous treatment with the methyl group donor, betaine. Here, we examined changes in the hepatic lipidome with respect to LD size and dynamics in male Wistar rats fed for 6 weeks with control or ethanol-containing liquid diets that were supplemented with or without 10 mg betaine/mL. At the time of sacrifice, three hepatic LD fractions, LD1 (large droplets), LD2 (medium-sized droplets), and LD3 (small droplets) were isolated from each rat. Untargeted lipidomic analyses revealed that each LD fraction of ethanol-fed rats had higher phospholipids, cholesteryl esters, diacylglycerols, ceramides, and hexosylceramides compared with the corresponding fractions of pair-fed controls. Interestingly, the ratio of phosphatidylcholine to phosphatidylethanolamine (the two most abundant phospholipids on the LD surface) was lower in LD1 fraction compared with LD3 fraction, irrespective of treatment; however, this ratio was significantly lower in ethanol LD fractions compared with their respective control fractions. Betaine supplementation significantly attenuated the ethanol-induced lipidomic changes. These were mainly associated with the regulation of LD surface phospholipids, ceramides, and glycerolipid metabolism in different-sized LD fractions. In conclusion, our results show that ethanol-induced changes in the hepatic LD lipidome likely stabilizes larger-sized LDs during steatosis development. Furthermore, betaine supplementation could effectively reduce the size and dynamics of LDs to attenuate alcohol-associated hepatic steatosis.
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Affiliation(s)
- Madan Kumar Arumugam
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Center for Molecular and Nanomedical Sciences, Sathyabama Institute of Science and Technology, Chennai 600119, India
| | - Sathish Kumar Perumal
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Karuna Rasineni
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Terrence M. Donohue
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Natalia A. Osna
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kusum K. Kharbanda
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
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13
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Paul A, Chanclón B, Brännmark C, Wittung-Stafshede P, Olofsson CS, Asterholm IW, Parekh SH. Comparing lipid remodeling of brown adipose tissue, white adipose tissue, and liver after one-week high fat diet intervention with quantitative Raman microscopy. J Cell Biochem 2023; 124:382-395. [PMID: 36715685 DOI: 10.1002/jcb.30372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/20/2022] [Accepted: 01/09/2023] [Indexed: 01/31/2023]
Abstract
Brown adipose tissue (BAT) consists of highly metabolically active adipocytes that catabolize nutrients to produce heat. Playing an active role in triacylglycerol (TAG) clearance, research has shown that dietary fatty acids can modulate the TAG chemistry deposition in BAT after weeks-long dietary intervention, similar to what has been shown in white adipose tissue (WAT). Our objective was to compare the influence of sustained, nonchronic dietary intervention (a 1-week interval) on WAT and interscapular BAT lipid metabolism and deposition in situ. We use quantitative, label-free chemical microscopy to show that 1 week of high fat diet (HFD) intervention results in dramatically larger lipid droplet (LD) growth in BAT (and liver) compared to LD growth in inguinal WAT (IWAT). Moreover, BAT showed lipid remodeling as increased unsaturated TAGs in LDs, resembling the dietary lipid composition, while WAT (and liver) did not show lipid remodeling on this time scale. Concurrently, expression of genes involved in lipid metabolism, particularly desaturases, was reduced in BAT and liver from HFD-fed mice after 1 week. Our data show that BAT lipid chemistry remodels exceptionally fast to dietary lipid intervention compared WAT, which further points towards a role in TAG clearance.
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Affiliation(s)
- Alexandra Paul
- Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA
| | - Belén Chanclón
- Department of Physiology (Metabolic Physiology), Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Cecilia Brännmark
- Department of Physiology (Metabolic Physiology), Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Pernilla Wittung-Stafshede
- Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Charlotta S Olofsson
- Department of Physiology (Metabolic Physiology), Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Ingrid Wernstedt Asterholm
- Department of Physiology (Metabolic Physiology), Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Sapun H Parekh
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Mainz, Germany
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14
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Amarasinghe I, Phillips W, Hill AF, Cheng L, Helbig KJ, Willms E, Monson EA. Cellular communication through extracellular vesicles and lipid droplets. JOURNAL OF EXTRACELLULAR BIOLOGY 2023; 2:e77. [PMID: 38938415 PMCID: PMC11080893 DOI: 10.1002/jex2.77] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/06/2023] [Accepted: 02/15/2023] [Indexed: 06/29/2024]
Abstract
Cellular communication is essential for effective coordination of biological processes. One major form of intercellular communication occurs via the release of extracellular vesicles (EVs). These vesicles mediate intercellular communication through the transfer of their cargo and are actively explored for their role in various diseases and their potential therapeutic and diagnostic applications. Conversely, lipid droplets (LDs) are vesicles that transfer cargo within cells. Lipid droplets play roles in various diseases and evidence for their ability to transfer cargo between cells is emerging. To date, there has been little interdisciplinary research looking at the similarities and interactions between these two classes of small lipid vesicles. This review will compare the commonalities and differences between EVs and LDs including their biogenesis and secretion, isolation and characterisation methodologies, composition, and general heterogeneity and discuss challenges and opportunities in both fields.
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Affiliation(s)
- Irumi Amarasinghe
- School of Agriculture, Biomedicine and EnvironmentLa Trobe UniversityMelbourneAustralia
| | - William Phillips
- School of Agriculture, Biomedicine and EnvironmentLa Trobe UniversityMelbourneAustralia
- La Trobe Institute for Molecular SciencesLa Trobe UniversityMelbourneAustralia
| | - Andrew F. Hill
- Institute for Health and SportVictoria UniversityFootscrayVictoriaAustralia
| | - Lesley Cheng
- School of Agriculture, Biomedicine and EnvironmentLa Trobe UniversityMelbourneAustralia
- La Trobe Institute for Molecular SciencesLa Trobe UniversityMelbourneAustralia
| | - Karla J. Helbig
- School of Agriculture, Biomedicine and EnvironmentLa Trobe UniversityMelbourneAustralia
| | - Eduard Willms
- School of Agriculture, Biomedicine and EnvironmentLa Trobe UniversityMelbourneAustralia
- La Trobe Institute for Molecular SciencesLa Trobe UniversityMelbourneAustralia
| | - Ebony A. Monson
- School of Agriculture, Biomedicine and EnvironmentLa Trobe UniversityMelbourneAustralia
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15
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de Almeida ME, Nielsen J, Petersen MH, Wentorf EK, Pedersen NB, Jensen K, Højlund K, Ørtenblad N. Altered intramuscular network of lipid droplets and mitochondria in type 2 diabetes. Am J Physiol Cell Physiol 2023; 324:C39-C57. [PMID: 36409174 DOI: 10.1152/ajpcell.00470.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Excessive storage of lipid droplets (LDs) in skeletal muscles is a hallmark of type 2 diabetes. However, LD morphology displays a high degree of subcellular heterogeneity and varies between single muscle fibers, which impedes the current understanding of lipid-induced insulin resistance. Using quantitative transmission electron microscopy (TEM), we conducted a comprehensive single-fiber morphological analysis to investigate the intramuscular network of LDs and mitochondria, and the effects of 8 wk of high-intensity interval training (HIIT) targeting major muscle groups, in patients with type 2 diabetes and nondiabetic obese and lean controls. We found that excessive storage of intramuscular lipids in patients with type 2 diabetes was exclusively explained by extremely large LDs situated in distinct muscle fibers with a location-specific deficiency in subsarcolemmal mitochondria. After HIIT, this intramuscular deficiency was improved by a remodeling of LD size and subcellular distribution and mitochondrial content. Analysis of LD morphology further revealed that individual organelles were better described as ellipsoids than spheres. Moreover, physical contact between LD and mitochondrial membranes indicated a dysfunctional interplay between organelles in the diabetic state. Taken together, type 2 diabetes should be recognized as a metabolic disease with high cellular heterogeneity in intramuscular lipid storage, underlining the relevance of single-cell technologies in clinical research. Furthermore, HIIT changed intramuscular LD storage toward nondiabetic characteristics.
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Affiliation(s)
- Martin Eisemann de Almeida
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark.,Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
| | - Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Maria Houborg Petersen
- Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark.,Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Emil Kleis Wentorf
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Niklas Bigum Pedersen
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Kurt Jensen
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Kurt Højlund
- Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
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16
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Mak KM, Wu C, Cheng CP. Lipid droplets, the Holy Grail of hepatic stellate cells: In health and hepatic fibrosis. Anat Rec (Hoboken) 2022; 306:983-1010. [PMID: 36516055 DOI: 10.1002/ar.25138] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/07/2022] [Accepted: 11/29/2022] [Indexed: 12/15/2022]
Abstract
Lipid droplets (LDs) are distinct morphological markers of hepatic stellate cells (HSCs). They are composed of a core of predominantly retinyl esters and triacylglycerols surrounded by a phospholipid layer; the latter harbors perilipins 2, 3, and 5, which help control LD lipolysis. Electron microscopy distinguishes between Types I and II LDs. Type I LDs are surrounded by acid phosphatase-positive lysosomes, which likely digest LDs. LD count and retinoid concentration are modulated by vitamin A intake. Alcohol consumption depletes hepatic retinoids and HSC LDs, with concomitant transformation of HSCs to fibrogenic myofibroblast-like cells. LD loss and accompanying HSC activation occur in HSC cell culture models. Loss of LDs is a consequence of and not a prerequisite for HSC activation. LDs are endowed with enzymes for synthesizing retinyl esters and triacylglycerols as well as neutral lipases and lysosomal acid lipase for breaking down LDs. HSCs have two distinct metabolic LD pools: an "original" pool in quiescent HSCs and a "new" pool emerging in HSC activation; this two-pool model provides a platform for analyzing LD dynamics in HSC activation. Besides lipolysis, LDs are degraded by lipophagy; however, the coordination between and relative contributions of these two pathways to LD removal are unclear. While induction of autophagy accelerates LD loss in quiescent HSCs and promotes HSC activation, blocking autophagy impairs LD degradation and inhibits HSC activation and fibrosis. This article is a critique of five decades of investigations into the morphology, molecular structure, synthesis, and degradation of LDs associated with HSC activation and fibrosis.
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Affiliation(s)
- Ki M Mak
- Department of Medical Education and Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Catherine Wu
- Department of Medical Education and Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Christopher P Cheng
- Department of Medical Education and Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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17
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Kislev N, Eidelheit S, Perlmutter S, Benayahu D. How to follow lipid droplets dynamics during adipocyte metabolism. J Cell Physiol 2022; 237:4157-4168. [PMID: 35986713 PMCID: PMC9804707 DOI: 10.1002/jcp.30857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 07/07/2022] [Accepted: 08/03/2022] [Indexed: 01/09/2023]
Abstract
Lipid droplets (LDs) are important cellular organelles due to their ability to accumulate and store lipids. LD dynamics are associated with various cellular and metabolic processes. Accurate monitoring of LD's size and shape is of prime importance as it indicates the metabolic status of the cells. Unintrusive continuous quantification techniques have a clear advantage in analyzing LDs as they measure and monitor the cells' metabolic function and droplets over time. Here, we present a novel machine-learning-based method for LDs analysis by segmentation of phase-contrast images of differentiated adipocytes (in vitro) and adipose tissue (in vivo). We developed a new workflow based on the ImageJ waikato environment for knowledge analysis segmentation plugin, which provides an accurate, label-free, live single-cell, and organelle quantification of LD-related parameters. By applying the new method on differentiating 3T3-L1 cells, the size of LDs was analyzed over time in differentiated adipocytes and their correlation with other morphological parameters. Moreover, we analyzed the LDs dynamics during catabolic changes such as lipolysis and lipophagy and demonstrated its ability to identify different cellular subpopulations based on their structural, numerical, and spatial variability. This analysis was also implemented on unstained ex vivo adipose tissues to measure adipocyte size, an important readout of the tissue's metabolism. The presented approach can be applied in different LD-related metabolic conditions to provide a better understanding of LD biogenesis and function in vivo and in vitro while serving as a new platform that enables rapid and accurate screening of data sets.
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Affiliation(s)
- Nadav Kislev
- Department of Cell and Developmental Biology, Sackler School of MedicineTel Aviv UniversityTel AvivIsrael
| | - Shira Eidelheit
- Department of Cell and Developmental Biology, Sackler School of MedicineTel Aviv UniversityTel AvivIsrael
| | - Shaked Perlmutter
- Department of Cell and Developmental Biology, Sackler School of MedicineTel Aviv UniversityTel AvivIsrael
| | - Dafna Benayahu
- Department of Cell and Developmental Biology, Sackler School of MedicineTel Aviv UniversityTel AvivIsrael
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18
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Mirza AH. Study of trioleoylglycerol two-layer and adiposome cross-section mimicking four-layer systems through atomic-level simulations. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2022; 9:064701. [PMID: 36484071 PMCID: PMC9726221 DOI: 10.1063/4.0000168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 11/08/2022] [Indexed: 06/17/2023]
Abstract
Adiposomes are artificially prepared lipid droplet (LD)-mimetic structures, which, unlike LDs, do not harbor proteins. The dynamics of interaction between triacylglycerols (TAGs), drug molecule, and phospholipids in adiposomes is currently not well-established. Trioleoylglycerol (TOG) molecule was divided into three parts: two oleoyl tails and one 2-monooleoylglycerol (MOG). Forcefield parameters for two oleoyl tails were adopted from the AMBER18 repository while that of the MOG forcefield was taken from the literature. Charge correction was performed on the MOG forcefield before its utilization. After charge correction, the resulting TOG molecule had zero charge. TOG bilayer (2L) and tetralayer (4L) systems were prepared and simulated. TOG bilayer (2L) systems-modeled from two different initial conformations, the TOG3 conformation and the TOG2:1 conformation-showed that TOG2:1 conformation was more prevailing irrespective of the starting conformation and was subsequently used in further simulations. The hydrated TOG 2L system showed TOG-water solution solubility of 0.051 mol L-1 which is near experimental values. This validated the correct parameterization of the TOG molecule. The simulations of 4L systems showed stable membrane behaviors toward the end of simulations. It was also observed that in the 4L system, the TOG molecules showed the formation of micelles with the drug molecule. Almost six TOGs remained continuously in contact with the drug molecule throughout the simulation. The availability of charge-corrected TOG parameterization is expected to equip future studies with a framework for molecular dynamics simulations of adiposomes and/or LDs at the atomic level.
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Affiliation(s)
- Ahmed Hammad Mirza
- Department of Biosciences, COMSATS University Islamabad, Sahiwal Campus, Sahiwal 57000, Pakistan
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19
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Getiye Y, Rice TA, Phillips BD, Carrillo DF, He G. Dysregulated lipolysis and lipophagy in lipid droplets of macrophages from high fat diet-fed obese mice. J Cell Mol Med 2022; 26:4825-4836. [PMID: 35962606 PMCID: PMC9465182 DOI: 10.1111/jcmm.17513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/14/2022] [Accepted: 07/23/2022] [Indexed: 11/30/2022] Open
Abstract
Obesity is associated with lipid droplet (LD) accumulation, dysregulated lipolysis and chronic inflammation. Previously, the caspase recruitment domain‐containing protein 9 (CARD9) has been identified as a potential contributor to obesity‐associated abnormalities including cardiac dysfunction. In the current study, we explored a positive feedback signalling cycle of dysregulated lipolysis, CARD9‐associated inflammation, impaired lipophagy and excessive LD accumulation in sustaining the chronic inflammation associated with obesity. C57BL/6 WT and CARD9−/− mice were fed with normal diet (ND, 12% fat) or a high fat diet (HFD, 45% fat) for 5 months. Staining of LDs from peritoneal macrophages (PMs) revealed a significant increase in the number of cells with LD and the number of LD per cell in the HFD‐fed WT but not CARD9−/− obese mice. Rather, CARD9 KO significantly increased the mean LD size. WT obese mice showed down regulation of lipolytic proteins with increased diacylglycerol (DAG) content, and CARD9 KO normalized DAG with restored lipolytic protein expression. The build‐up of DAG in the WT obese mice is further associated with activation of PKCδ, NF‐κB and p38 MAPK inflammatory signalling in a CARDD9‐dependent manner. Inhibition of adipose triglyceride lipase (ATGL) by Atglistatin (Atg) resulted in similar effects as in CARD9−/− mice. Interestingly, CARD9 KO and Atg treatment enhanced lipophagy. In conclusion, HFD feeding likely initiated a positive feedback signalling loop from dysregulated lipolysis, CARD9‐dependent inflammation, impaired lipophagy, to excessive LD accumulation and sustained inflammation. CARD9 KO and Atg treatment protected against the chronic inflammation by interrupting this feedforward cycle.
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Affiliation(s)
- Yohannes Getiye
- School of Pharmacy, College of Health Sciences, University of Wyoming, Laramie, Wyoming, USA
| | - Tatiana Angel Rice
- School of Pharmacy, College of Health Sciences, University of Wyoming, Laramie, Wyoming, USA
| | - Brandon D Phillips
- School of Pharmacy, College of Health Sciences, University of Wyoming, Laramie, Wyoming, USA
| | - Daniel Fidel Carrillo
- School of Pharmacy, College of Health Sciences, University of Wyoming, Laramie, Wyoming, USA
| | - Guanglong He
- School of Pharmacy, College of Health Sciences, University of Wyoming, Laramie, Wyoming, USA
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20
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Kou Y, Geng F, Guo D. Lipid Metabolism in Glioblastoma: From De Novo Synthesis to Storage. Biomedicines 2022; 10:1943. [PMID: 36009491 PMCID: PMC9405736 DOI: 10.3390/biomedicines10081943] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/01/2022] [Accepted: 08/06/2022] [Indexed: 12/12/2022] Open
Abstract
Glioblastoma (GBM) is the most lethal primary brain tumor. With limited therapeutic options, novel therapies are desperately needed. Recent studies have shown that GBM acquires large amounts of lipids for rapid growth through activation of sterol regulatory element-binding protein 1 (SREBP-1), a master transcription factor that regulates fatty acid and cholesterol synthesis, and cholesterol uptake. Interestingly, GBM cells divert substantial quantities of lipids into lipid droplets (LDs), a specific storage organelle for neutral lipids, to prevent lipotoxicity by increasing the expression of diacylglycerol acyltransferase 1 (DGAT1) and sterol-O-acyltransferase 1 (SOAT1), which convert excess fatty acids and cholesterol to triacylglycerol and cholesteryl esters, respectively. In this review, we will summarize recent progress on our understanding of lipid metabolism regulation in GBM to promote tumor growth and discuss novel strategies to specifically induce lipotoxicity to tumor cells through disrupting lipid storage, a promising new avenue for treating GBM.
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Affiliation(s)
- Yongjun Kou
- Department of Radiation Oncology, Ohio State Comprehensive Cancer Center, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, College of Medicine at The Ohio State University, Columbus, OH 43012, USA
| | - Feng Geng
- Department of Radiation Oncology, Ohio State Comprehensive Cancer Center, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, College of Medicine at The Ohio State University, Columbus, OH 43012, USA
| | - Deliang Guo
- Department of Radiation Oncology, Ohio State Comprehensive Cancer Center, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, College of Medicine at The Ohio State University, Columbus, OH 43012, USA
- Center for Cancer Metabolism, James Comprehensive Cancer Center at The Ohio State University, Columbus, OH 43210, USA
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21
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Nardo WD, Miotto PM, Bayliss J, Nie S, Keenan SN, Montgomery MK, Watt MJ. Proteomic analysis reveals exercise training induced remodelling of hepatokine secretion and uncovers syndecan-4 as a regulator of hepatic lipid metabolism. Mol Metab 2022; 60:101491. [PMID: 35381388 PMCID: PMC9034320 DOI: 10.1016/j.molmet.2022.101491] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 03/22/2022] [Accepted: 03/29/2022] [Indexed: 11/04/2022] Open
Abstract
Objective Non-alcoholic fatty liver disease (NAFLD) is linked to impaired lipid metabolism and systemic insulin resistance, which is partly mediated by altered secretion of liver proteins known as hepatokines. Regular physical activity can resolve NAFLD and improve its metabolic comorbidities, however, the effects of exercise training on hepatokine secretion and the metabolic impact of exercise-regulated hepatokines in NAFLD remain unresolved. Herein, we examined the effect of endurance exercise training on hepatocyte secreted proteins with the aim of identifying proteins that regulate metabolism and reduce NAFLD severity. Methods C57BL/6 mice were fed a high-fat diet for six weeks to induce NAFLD. Mice were exercise trained for a further six weeks, while the control group remained sedentary. Hepatocytes were isolated two days after the last exercise bout, and intracellular and secreted proteins were detected using label-free mass spectrometry. Hepatocyte secreted factors were applied to skeletal muscle and liver ex vivo and insulin action and fatty acid metabolism were assessed. Syndecan-4 (SDC4), identified as an exercise-responsive hepatokine, was overexpressed in the livers of mice using adeno-associated virus. Whole-body energy homeostasis was assessed by indirect calorimetry and skeletal muscle and liver metabolism was assessed using radiometric techniques. Results Proteomics analysis detected 2657 intracellular and 1593 secreted proteins from mouse hepatocytes. Exercise training remodelled the hepatocyte proteome, with differences in 137 intracellular and 35 secreted proteins. Bioinformatic analysis of hepatocyte secreted proteins revealed enrichment of tumour suppressive proteins and proteins involved in lipid metabolism and mitochondrial function, and suppression of oncogenes and regulators of oxidative stress. Hepatocyte secreted factors from exercise trained mice improved insulin action in skeletal muscle and increased hepatic fatty acid oxidation. Hepatocyte-specific overexpression of SDC4 reduced hepatic steatosis, which was associated with reduced hepatic fatty acid uptake, and blunted pro-inflammatory and pro-fibrotic gene expression. Treating hepatocytes with recombinant ectodomain of SDC4 (secreted form) recapitulated these effects with reduced fatty acid uptake, lipid storage and lipid droplet accumulation. Conclusions Remodelling of hepatokine secretion is an adaptation to regular exercise training that induces changes in metabolism in the liver and skeletal muscle. SDC4 is a novel exercise-responsive hepatokine that decreases fatty acid uptake and reduces steatosis in the liver. By understanding the proteomic changes in hepatocytes with exercise, these findings have potential for the discovery of new therapeutic targets for NAFLD. Exercise training remodels hepatokine secretion. Exercise regulated secreted factors improve insulin action in skeletal muscle. Syndecan-4 (SDC4) is a novel exercise-induced hepatokine. SDC4 reduces hepatic fatty acid uptake and hepatic steatosis.
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22
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Huang W, Gao F, Zhang Y, Chen T, Xu C. Lipid Droplet-Associated Proteins in Cardiomyopathy. ANNALS OF NUTRITION AND METABOLISM 2021; 78:1-13. [PMID: 34856540 DOI: 10.1159/000520122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 10/08/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND The heart requires a high rate of fatty-acid oxidation (FAO) to meet its energy needs. Neutral lipids are the main source of energy for the heart and are stored in lipid droplets (LDs), which are cytosolic organelles that primarily serve to store neutral lipids and regulate cellular lipid metabolism. LD-associated proteins (LDAPs) are proteins either located on the surface of the LDs or reside in the cytosol and contribute to lipid metabolism. Therefore, abnormal cardiac lipid accumulation or FAO can alter the redox state of the heart, resulting in cardiomyopathy, a group of diseases that negatively affect the myocardial function, thereby leading to heart failure and even cardiac death. SUMMARY LDs, along with LDAPs, are pivotal for modulating heart lipid homeostasis. The proper cardiac development and the maintenance of its normal function depend largely on lipid homeostasis regulated by LDs and LDAPs. Overexpression or deletion of specific LDAPs can trigger myocardial dysfunction and may contribute to the development of cardiomyopathy. Extensive connections and interactions may also exist between LDAPs. Key Message: In this review, the various mechanisms involved in LDAP-mediated regulation of lipid metabolism, the association between cardiac development and lipid metabolism, as well as the role of LDAPs in cardiomyopathy progression are discussed.
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Affiliation(s)
- Weiwei Huang
- Obstetrics and Gynecology Hospital, Fudan University, Shanghai, China.,Department of Physiology and Pathophysiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Fei Gao
- Department of Physiology and Pathophysiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yuting Zhang
- Department of Physiology and Pathophysiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Tianhui Chen
- Department of Ophthalmology and Vision Science, Eye and ENT Hospital of Fudan University, Shanghai, China.,Key Laboratory of Myopia of State Health Ministry, and Key Laboratory of Visual Impairment and Restoration of Shanghai, Shanghai, China
| | - Chen Xu
- Department of Physiology and Pathophysiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
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Abstract
Lipid droplets (LDs) are endoplasmic reticulum-derived organelles that consist of a core of neutral lipids encircled by a phospholipid monolayer decorated with proteins. As hubs of cellular lipid and energy metabolism, LDs are inherently involved in the etiology of prevalent metabolic diseases such as obesity and nonalcoholic fatty liver disease. The functions of LDs are regulated by a unique set of associated proteins, the LD proteome, which includes integral membrane and peripheral proteins. These proteins control key activities of LDs such as triacylglycerol synthesis and breakdown, nutrient sensing and signal integration, and interactions with other organelles. Here we review the mechanisms that regulate the composition of the LD proteome, such as pathways that mediate selective and bulk LD protein degradation and potential connections between LDs and cellular protein quality control.
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Affiliation(s)
- Melissa A Roberts
- Department of Molecular and Cell Biology and Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720, USA;
| | - James A Olzmann
- Department of Molecular and Cell Biology and Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720, USA; .,Chan Zuckerberg Biohub, San Francisco, California 94158, USA
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24
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Chen HK, Rosset SL, Wang LH, Chen CS. The characteristics of host lipid body biogenesis during coral-dinoflagellate endosymbiosis. PeerJ 2021; 9:e11652. [PMID: 34221732 PMCID: PMC8234918 DOI: 10.7717/peerj.11652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/31/2021] [Indexed: 11/25/2022] Open
Abstract
Intracellular lipid body (LB) biogenesis depends on the symbiosis between coral hosts and their Symbiodinaceae. Therefore, understanding the mechanism(s) behind LB biosynthesis in corals can portentially elucide the drivers of cellular regulation during endosymbiosis. This study assessed LB formation in the gastrodermal tissue layer of the hermatypic coral Euphyllia glabrescens. Diel rhythmicity in LB size and distribution was observed; solar irradiation onset at sunrise initiated an increase in LB formation, which continued throughout the day and peaked after sunset at 18:00. The LBs migrated from the area near the mesoglea to the gastrodermal cell border near the coelenteron. Micro-LB biogenesis occurred in the endoplasmic reticulum (ER) of the host gastrodermal cells. A transcriptomic analysis of genes related to lipogenesis indicated that binding immunoglobulin protein (BiP) plays a key role in metabolic signaling pathways. The diel rhythmicity of LB biogenesis was correlated with ER-localized BiP expression. BiP expression peaked during the period with the largest increase in LB formation, thereby indicating that the chaperoning reaction of abnormal protein folding inside the host ER is likely involved in LB biosynthesis. These findings suggest that the host ER, central to LB formation, potentially facilitates the regulation of endosymbiosis between coral hosts and Symbiodiniaceae.
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Affiliation(s)
- Hung-Kai Chen
- National Museum of Marine Biology and Aquarium, Pingtung, Taiwan
| | - Sabrina L Rosset
- National Museum of Marine Biology and Aquarium, Pingtung, Taiwan
| | - Li-Hsueh Wang
- National Museum of Marine Biology and Aquarium, Pingtung, Taiwan.,Graduate Institute of Marine Biology, National Dong-Hwa University, Pingtung, Taiwan
| | - Chii-Shiarng Chen
- National Museum of Marine Biology and Aquarium, Pingtung, Taiwan.,Graduate Institute of Marine Biology, National Dong-Hwa University, Pingtung, Taiwan.,Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
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25
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Zembroski AS, Andolino C, Buhman KK, Teegarden D. Proteomic Characterization of Cytoplasmic Lipid Droplets in Human Metastatic Breast Cancer Cells. Front Oncol 2021; 11:576326. [PMID: 34141606 PMCID: PMC8204105 DOI: 10.3389/fonc.2021.576326] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 05/10/2021] [Indexed: 12/19/2022] Open
Abstract
One of the characteristic features of metastatic breast cancer is increased cellular storage of neutral lipid in cytoplasmic lipid droplets (CLDs). CLD accumulation is associated with increased cancer aggressiveness, suggesting CLDs contribute to metastasis. However, how CLDs contribute to metastasis is not clear. CLDs are composed of a neutral lipid core, a phospholipid monolayer, and associated proteins. Proteins that associate with CLDs regulate both cellular and CLD metabolism; however, the proteome of CLDs in metastatic breast cancer and how these proteins may contribute to breast cancer progression is unknown. Therefore, the purpose of this study was to identify the proteome and assess the characteristics of CLDs in the MCF10CA1a human metastatic breast cancer cell line. Utilizing shotgun proteomics, we identified over 1500 proteins involved in a variety of cellular processes in the isolated CLD fraction. Interestingly, unlike other cell lines such as adipocytes or enterocytes, the most enriched protein categories were involved in cellular processes outside of lipid metabolism. For example, cell-cell adhesion was the most enriched category of proteins identified, and many of these proteins have been implicated in breast cancer metastasis. In addition, we characterized CLD size and area in MCF10CA1a cells using transmission electron microscopy. Our results provide a hypothesis-generating list of potential players in breast cancer progression and offers a new perspective on the role of CLDs in cancer.
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Affiliation(s)
- Alyssa S Zembroski
- Department of Nutrition Science, Purdue University, West Lafayette, IN, United States
| | - Chaylen Andolino
- Department of Nutrition Science, Purdue University, West Lafayette, IN, United States
| | - Kimberly K Buhman
- Department of Nutrition Science, Purdue University, West Lafayette, IN, United States
| | - Dorothy Teegarden
- Department of Nutrition Science, Purdue University, West Lafayette, IN, United States
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26
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Wang HC, Liu KY, Wang LT, Hsu SH, Wang SC, Huang SK. Aryl hydrocarbon receptor promotes lipid droplet biogenesis and metabolic shift in respiratory Club cells. Hum Cell 2021; 34:785-799. [PMID: 33683656 DOI: 10.1007/s13577-021-00491-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 01/14/2021] [Indexed: 10/22/2022]
Abstract
Club cells are critical in maintaining airway integrity via, in part, secretion of immunomodulatory Club cell 10 kd protein (CC10) and xenobiotic detoxification. Aryl hydrocarbon receptor (AhR) is important in xenobiotic metabolism, but its role in Club cell function is unclear. To this end, an AhR ligand, 6-formylindolo[3,2-b]carbazole (FICZ, 10 nM) was found to induce, in a ligand and AhR-dependent manner, endoplasmic reticulum stress, phospholipid remodeling, free fatty acid and triglyceride synthesis, leading to perilipin 2-dependent lipid droplet (LD) biogenesis in a Club cell-like cell line, NL20. The increase in LDs was due, in part, to the blockade of adipose triglyceride lipase to LDs, while perilipin 5 facilitated LDs-mitochondria connection, leading to the breakdown of LDs via mitochondrial β-oxidation and acetyl-coA generation. In FICZ-treated cells, increased CC10 secretion and its intracellular association with LDs were noted. Administration of low (0.28 ng), medium (1.42 ng), and high (7.10 ng) doses of FICZ in C57BL/6 mice significantly enhanced lipopolysaccharide (LPS, 0.1 μg)-induced airway inflammation, mucin secretion, pro-inflammatory cytokines and CC10 in the bronchoalveolar lavage fluids, as compared to those seen in mice receiving LPS alone, suggesting the importance of AhR signaling in controlling the metabolic homeostasis and functions of Club cells.
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Affiliation(s)
- Hsueh-Chun Wang
- Graduate Institute of Biomedical Sciences, China Medical University, 91 Hsueh-Shih Rd, North District, Taichung, 40402, Taiwan.
- Research Center for Cancer Biology, China Medical University, Taichung, Taiwan.
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, 40402, Taiwan.
| | - Kwei-Yan Liu
- Department of Allergy, The Third Affiliated Hospital of Shenzhen University, Shenzhen, 518020, China
| | - Li-Ting Wang
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Shih-Hsien Hsu
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Shao-Chun Wang
- Graduate Institute of Biomedical Sciences, China Medical University, 91 Hsueh-Shih Rd, North District, Taichung, 40402, Taiwan
- Research Center for Cancer Biology, China Medical University, Taichung, Taiwan
- Center for Molecular Medicine, China Medical University Hospital, Taichung, 40447, Taiwan
| | - Shau-Ku Huang
- National Institute of Environmental Health Sciences, National Health Research Institutes, No. 35, Keyan Road, Zhunan, Miaoli County, 35053, Taiwan.
- Division of Allergy and Clinical Immunology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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27
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Monson EA, Whelan DR, Helbig KJ. Lipid Droplet Motility Increases Following Viral Immune Stimulation. Int J Mol Sci 2021; 22:4418. [PMID: 33922664 PMCID: PMC8122965 DOI: 10.3390/ijms22094418] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/15/2022] Open
Abstract
Lipid droplets (LDs) have traditionally been thought of as solely lipid storage compartments for cells; however, in the last decade, they have emerged as critical organelles in health and disease. LDs are highly dynamic within cells, and their movement is critical in organelle-organelle interactions. Their dynamics are known to change during cellular stress or nutrient deprivation; however, their movement during pathogen infections, especially at very early timepoints, is under-researched. This study aimed to track LD dynamics in vitro, in an astrocytic model of infection. Cells were either stimulated with a dsRNA viral mimic, poly I:C, or infected with the RNA virus, Zika virus. Individual LDs within infected cells were analysed to determine displacement and speed, and average LD characteristics for multiple individual cells calculated. Both LD displacement and mean speed were significantly enhanced in stimulated cells over a time course of infection with an increase seen as early as 2 h post-infection. With the emerging role for LDs during innate host responses, understanding their dynamics is critical to elucidate how these organelles influence the outcome of viral infection.
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Affiliation(s)
- Ebony A. Monson
- Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Melbourne 3086, Australia;
| | - Donna R. Whelan
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3086, Australia
| | - Karla J. Helbig
- Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Melbourne 3086, Australia;
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28
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Cui L, Liu P. Two Types of Contact Between Lipid Droplets and Mitochondria. Front Cell Dev Biol 2020; 8:618322. [PMID: 33385001 PMCID: PMC7769837 DOI: 10.3389/fcell.2020.618322] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 11/25/2020] [Indexed: 12/11/2022] Open
Abstract
Lipid droplets (LDs) and mitochondria are essential organelles involved in cellular lipid metabolism and energy homeostasis. Accumulated studies have revealed that the physical contact between these two organelles is important for their functions. Current understanding of the contact between cellular organelles is highly dynamic, fitting a "kiss-and-run" model. The same pattern of contact between LDs and mitochondria has been reported and several proteins are found to mediate this contact, such as perilipin1 (PLIN1) and PLIN5. Another format of the contact has also been found and termed anchoring. LD-anchored mitochondria (LDAM) are identified in oxidative tissues including brown adipose tissue (BAT), skeletal muscle, and heart muscle, and this anchoring between these two organelles is conserved from mouse to monkey. Moreover, this anchoring is generated during the brown/beige adipocyte differentiation. In this review, we will summarize previous studies on the interaction between LDs and mitochondria, categorize the types of the contacts into dynamic and stable/anchored, present their similarities and differences, discuss their potential distinct molecular mechanism, and finally propose a working hypothesis that may explain why and how cells use two patterns of contact between LDs and mitochondria.
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Affiliation(s)
- Liujuan Cui
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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29
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Kongmanas K, Punyadee N, Wasuworawong K, Songjaeng A, Prommool T, Pewkliang Y, Manocheewa S, Thiemmeca S, Sa-ngiamsuntorn K, Puttikhunt C, Faull KF, Hongeng S, Avirutnan P. Immortalized stem cell-derived hepatocyte-like cells: An alternative model for studying dengue pathogenesis and therapy. PLoS Negl Trop Dis 2020; 14:e0008835. [PMID: 33216752 PMCID: PMC7717553 DOI: 10.1371/journal.pntd.0008835] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 12/04/2020] [Accepted: 09/29/2020] [Indexed: 12/31/2022] Open
Abstract
Suitable cell models are essential to advance our understanding of the pathogenesis of liver diseases and the development of therapeutic strategies. Primary human hepatocytes (PHHs), the most ideal hepatic model, are commercially available, but they are expensive and vary from lot-to-lot which confounds their utility. We have recently developed an immortalized hepatocyte-like cell line (imHC) from human mesenchymal stem cells, and tested it for use as a substitute model for hepatotropic infectious diseases. With a special interest in liver pathogenesis of viral infection, herein we determined the suitability of imHC as a host cell target for dengue virus (DENV) and as a model for anti-viral drug testing. We characterized the kinetics of DENV production, cellular responses to DENV infection (apoptosis, cytokine production and lipid droplet metabolism), and examined anti-viral drug effects in imHC cells with comparisons to the commonly used hepatoma cell lines (HepG2 and Huh-7) and PHHs. Our results showed that imHC cells had higher efficiencies in DENV replication and NS1 secretion as compared to HepG2 and Huh-7 cells. The kinetics of DENV infection in imHC cells showed a slower rate of apoptosis than the hepatoma cell lines and a certain similarity of cytokine profiles to PHHs. In imHC, DENV-induced alterations in levels of lipid droplets and triacylglycerols, a major component of lipid droplets, were more apparent than in hepatoma cell lines, suggesting active lipid metabolism in imHC. Significantly, responses to drugs with DENV inhibitory effects were greater in imHC cells than in HepG2 and Huh-7 cells. In conclusion, our findings suggest superior suitability of imHC as a new hepatocyte model for studying mechanisms underlying viral pathogenesis, liver diseases and drug effects. A model system resembling normal human liver cells is needed for advancement of hepatotropic infectious disease research. Here we show that immortalized cells (imHC) derived from human stem cells have a higher efficiency of DENV replication and a lower rate of cell death in response to DENV infection than the cancer cell-derived model systems currently used. The imHC also have active fat metabolism and respond well to anti-viral drug treatment, making them an attractive model for the initial stage of drug discovery and testing.
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Affiliation(s)
- Kessiri Kongmanas
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Siriraj Metabolomics and Phenomics Center, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Nuntaya Punyadee
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Kasima Wasuworawong
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Adisak Songjaeng
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Tanapan Prommool
- Molecular Biology of Dengue and Flaviviruses Research Team, Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok, Thailand
| | - Yongyut Pewkliang
- Excellent Center for Drug Discovery, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Siriphan Manocheewa
- Siriraj Metabolomics and Phenomics Center, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Somchai Thiemmeca
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Graduate Program in Immunology, Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | | | - Chunya Puttikhunt
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Molecular Biology of Dengue and Flaviviruses Research Team, Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok, Thailand
| | - Kym Francis Faull
- Pasarow Mass Spectrometry Laboratory, Jane and Terry Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, California, United States of America
| | - Suradej Hongeng
- Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Panisadee Avirutnan
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Siriraj Metabolomics and Phenomics Center, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Molecular Biology of Dengue and Flaviviruses Research Team, Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok, Thailand
- * E-mail:
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30
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Friend or Foe: Lipid Droplets as Organelles for Protein and Lipid Storage in Cellular Stress Response, Aging and Disease. Molecules 2020; 25:molecules25215053. [PMID: 33143278 PMCID: PMC7663626 DOI: 10.3390/molecules25215053] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 02/06/2023] Open
Abstract
Lipid droplets (LDs) were considered as a mere lipid storage organelle for a long time. Recent evidence suggests that LDs are in fact distinct and dynamic organelles with a specialized proteome and functions in many cellular roles. As such, LDs contribute to cellular signaling, protein and lipid homeostasis, metabolic diseases and inflammation. In line with the multitude of functions, LDs interact with many cellular organelles including mitochondria, peroxisomes, lysosomes, the endoplasmic reticulum and the nucleus. LDs are highly mobile and dynamic organelles and impaired motility disrupts the interaction with other organelles. The reduction of interorganelle contacts results in a multitude of pathophysiologies and frequently in neurodegenerative diseases. Contacts not only supply lipids for β-oxidation in mitochondria and peroxisomes, but also may include the transfer of toxic lipids as well as misfolded and harmful proteins to LDs. Furthermore, LDs assist in the removal of protein aggregates when severe proteotoxic stress overwhelms the proteasomal system. During imbalance of cellular lipid homeostasis, LDs also support cellular detoxification. Fine-tuning of LD function is of crucial importance and many diseases are associated with dysfunctional LDs. We summarize the current understanding of LDs and their interactions with organelles, providing a storage site for harmful proteins and lipids during cellular stress, aging inflammation and various disease states.
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31
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Nuber S, Nam AY, Rajsombath MM, Cirka H, Hronowski X, Wang J, Hodgetts K, Kalinichenko LS, Müller CP, Lambrecht V, Winkler J, Weihofen A, Imberdis T, Dettmer U, Fanning S, Selkoe DJ. A Stearoyl-Coenzyme A Desaturase Inhibitor Prevents Multiple Parkinson Disease Phenotypes in α-Synuclein Mice. Ann Neurol 2020; 89:74-90. [PMID: 32996158 PMCID: PMC7756464 DOI: 10.1002/ana.25920] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 09/25/2020] [Accepted: 09/25/2020] [Indexed: 12/20/2022]
Abstract
Objective Parkinson disease (PD) has useful symptomatic treatments that do not slow the neurodegenerative process, and no significant disease‐modifying treatments are approved. A key therapeutic target in PD is α‐synuclein (αS), which is both genetically implicated and accumulates in Lewy bodies rich in vesicles and other lipid membranes. Reestablishing αS homeostasis is a central goal in PD. Based on previous lipidomic analyses, we conducted a mouse trial of a stearoyl–coenzyme A desaturase (SCD) inhibitor (“5b”) that prevented αS‐positive vesicular inclusions and cytotoxicity in cultured human neurons. Methods Oral dosing and brain activity of 5b were established in nontransgenic mice. 5b in drinking water was given to mice expressing wild‐type human αS (WT) or an amplified familial PD αS mutation (E35K + E46K + E61K ["3K"]) beginning near the onset of nigral and cortical neurodegeneration and the robust PD‐like motor syndrome in 3K. Motor phenotypes, brain cytopathology, and SCD‐related lipid changes were quantified in 5b‐ versus placebo‐treated mice. Outcomes were compared to effects of crossing 3K to SCD1−/− mice. Results 5b treatment reduced αS hyperphosphorylation in E46K‐expressing human neurons, in 3K neural cultures, and in both WT and 3K αS mice. 5b prevented subtle gait deficits in WT αS mice and the PD‐like resting tremor and progressive motor decline of 3K αS mice. 5b also increased αS tetramers and reduced proteinase K‐resistant lipid‐rich aggregates. Similar benefits accrued from genetically deleting 1 SCD allele, providing target validation. Interpretation Prolonged reduction of brain SCD activity prevented PD‐like neuropathology in multiple PD models. Thus, an orally available SCD inhibitor potently ameliorates PD phenotypes, positioning this approach to treat human α‐synucleinopathies. ANN NEUROL 2021;89:74–90
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Affiliation(s)
- Silke Nuber
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Alice Y Nam
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Molly M Rajsombath
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Haley Cirka
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | | | - Junmin Wang
- Chemical Biology & Proteomics, Biogen, Cambridge, MA, USA
| | - Kevin Hodgetts
- Laboratory for Drug Discovery in Neurodegeneration, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Liubov S Kalinichenko
- Department of Psychiatry and Psychotherapy, University Clinic, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Christian P Müller
- Department of Psychiatry and Psychotherapy, University Clinic, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Vera Lambrecht
- Division of Molecular Neurology, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Jürgen Winkler
- Division of Molecular Neurology, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Andreas Weihofen
- Neurodegenerative Diseases Research Unit, Biogen, Cambridge, MA, USA
| | - Thibaut Imberdis
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Ulf Dettmer
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Saranna Fanning
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Dennis J Selkoe
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
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32
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Korovila I, Jung T, Deubel S, Grune T, Ott C. Punicalagin Attenuates Palmitate-Induced Lipid Droplet Content by Simultaneously Improving Autophagy in Hepatocytes. Mol Nutr Food Res 2020; 64:e2000816. [PMID: 32918380 DOI: 10.1002/mnfr.202000816] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Indexed: 12/17/2022]
Abstract
SCOPE Several studies show that excessive lipid intake can cause hepatic steatosis. To investigate lipotoxicity on cellular level, palmitate (PA) is often used to highly increase lipid droplets (LDs). One way to remove LDs is autophagy, while it is controversially discussed if autophagy is also affected by PA. It is aimed to investigate whether PA-induced LD accumulation can impair autophagy and punicalagin, a natural autophagy inducer from pomegranate, can improve it. METHODS AND RESULTS To verify the role of autophagy in LD degradation, HepG2 cells are treated with PA and analyzed for LD and perilipin 2 content in presence of autophagy inducer Torin 1 and inhibitor 3-Methyladenine. PA alone seems to initially induce autophagy-related proteins but impairs autophagic-flux in a time-dependent manner, considering 6 and 24 h PA. To examine whether punicalagin can prevent autophagy impairment, cells are cotreated for 24 h with PA and punicalagin. Results show that punicalagin preserves expression of autophagy-related proteins and autophagic flux, while simultaneously decreasing LDs and perilipin 2. CONCLUSION Data provide new insights into the role of PA-induced excessive LD content on autophagy and suggest autophagy-inducing properties of punicalagin, indicating that punicalagin can be a health-beneficial compound for future research on lipotoxicity in liver.
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Affiliation(s)
- Ioanna Korovila
- Department of Molecular Toxicology, German Institute of Human Nutrition (DIfE) Potsdam-Rehbruecke, Nuthetal, 14558, Germany
| | - Tobias Jung
- Department of Molecular Toxicology, German Institute of Human Nutrition (DIfE) Potsdam-Rehbruecke, Nuthetal, 14558, Germany.,German Centre for Cardiovascular Research (DZHK), partner site Berlin, Berlin, 13347, Germany
| | - Stefanie Deubel
- Department of Molecular Toxicology, German Institute of Human Nutrition (DIfE) Potsdam-Rehbruecke, Nuthetal, 14558, Germany
| | - Tilman Grune
- Department of Molecular Toxicology, German Institute of Human Nutrition (DIfE) Potsdam-Rehbruecke, Nuthetal, 14558, Germany.,German Centre for Cardiovascular Research (DZHK), partner site Berlin, Berlin, 13347, Germany.,Institute of Nutrition, University of Potsdam, Nuthetal, 14558, Germany.,NutriAct-Competence Cluster Nutrition Research Berlin-Potsdam, Cluster-Office NutriAct, Nuthetal, 14558, Germany.,German Center for Diabetes Research (DZD), Munich, Neuherberg, 85764, Germany
| | - Christiane Ott
- Department of Molecular Toxicology, German Institute of Human Nutrition (DIfE) Potsdam-Rehbruecke, Nuthetal, 14558, Germany.,German Centre for Cardiovascular Research (DZHK), partner site Berlin, Berlin, 13347, Germany
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33
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Hammoudeh N, Soukkarieh C, Murphy DJ, Hanano A. Involvement of hepatic lipid droplets and their associated proteins in the detoxification of aflatoxin B 1 in aflatoxin-resistance BALB/C mouse. Toxicol Rep 2020; 7:795-804. [PMID: 32642446 PMCID: PMC7334552 DOI: 10.1016/j.toxrep.2020.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 06/04/2020] [Accepted: 06/11/2020] [Indexed: 12/14/2022] Open
Abstract
The highly potent carcinogen, Aflatoxin B1, induces liver cancer in many animals including humans but some mice strains are highly resistant. This murine resistance is due to a rapid detoxification of AFB1. Hepatic lipid droplets (LDs) ultimately impact the liver functions but their potential role in AFB1 detoxification has not been addressed. This study describes the structural and functional impacts on hepatic LDs in BALB/C mice after exposure to 44 (low dose) or 663 (high dose) μg AFB1/kg of body weight. After 7 days, the liver of AFB1-dosed mice did not accumulate any detectable AFB1 or its metabolites and this was associated with a net increase in gene transcripts of the AhR-mediating pathway. Of particular interest, the livers of high-dose mice accumulated many more LDs than those of low-dose mice. This was accompanied with a net increase in transcript levels of LD-associated protein-encoding genes including Plin2, Plin3 and Cideb and an alteration in the LDs lipid profiles that could be likely due to the induction of lipoxygenase and cyclooxygenase genes. Interestingly, our data suggest that hepatic LDs catalyze the in vitro activation of AFB1 into AFB1-exo-8,9-epoxide and subsequent hydrolysis of this epoxide into its corresponding dihydrodiol. Finally, transcript levels of CYP1A2, CYP1B1, GSTA3 and EH1 genes were elevated in livers of high-dose mice. These data suggest new roles for hepatic LDs in the trapping and detoxifying of aflatoxins.
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Affiliation(s)
- Nour Hammoudeh
- Department of Animal Biology, Damascus University, Damascus, Syria
| | - Chadi Soukkarieh
- Department of Animal Biology, Damascus University, Damascus, Syria
| | - Denis J Murphy
- Genomics and Computational Biology Group, University of South Wales, Wales, United Kingdom
| | - Abdulsamie Hanano
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), P.O. Box 6091, Damascus, Syria
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34
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Popkova Y, Dannenberger D, Schiller J, Engel KM. Differences in the lipid patterns during maturation of 3T3-L1 adipocytes investigated by thin-layer chromatography, gas chromatography, and mass spectrometric approaches. Anal Bioanal Chem 2019; 412:2237-2249. [PMID: 31797017 DOI: 10.1007/s00216-019-02243-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/21/2019] [Accepted: 10/28/2019] [Indexed: 12/16/2022]
Abstract
Populations of industrialized countries have registered a dramatically increasing prevalence in obesity for many years. Despite continuous research, mechanisms involved in the storage and utilization of chemical energy in adipocytes are still under investigation. Adipocytes have the task to store excessive energy in the form of triacylglycerols (TG) and it is already well-known that the fatty acyl composition of TG is largely determined by the composition of the diet. In contrast to TG, the composition of adipocyte phospholipids was less comprehensively investigated. In this study, the compositions of the most abundant phospholipid classes of 3T3-L1 undifferentiated (preadipocytes) and differentiated cells (adipocytes) were determined. The lipid fractions were isolated by normal phase high-performance thin-layer chromatography and subsequently analyzed by electrospray ionization mass spectrometry. Additionally, the fatty acyl (FA) compositions were determined by gas chromatography. The positions of the FA residues were additionally confirmed by phospholipase A2 digestion. The advantages and disadvantages of the different analytical approaches will be discussed. It will be shown that undifferentiated 3T3-L1 and mature adipocytes differ extremely regarding their compositions. This goes along with an increase in odd-chain fatty acids. Graphical abstract.
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Affiliation(s)
- Yulia Popkova
- Institute for Medical Physics and Biophysics, Medical Faculty, Leipzig University, Härtelstr. 16-18, 04107, Leipzig, Germany.
| | - Dirk Dannenberger
- Leibniz Institute for Farm Animal Biology, Institute of Muscle Biology and Growth, Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany
| | - Jürgen Schiller
- Institute for Medical Physics and Biophysics, Medical Faculty, Leipzig University, Härtelstr. 16-18, 04107, Leipzig, Germany
| | - Kathrin M Engel
- Institute for Medical Physics and Biophysics, Medical Faculty, Leipzig University, Härtelstr. 16-18, 04107, Leipzig, Germany
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35
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Geltinger F, Tevini J, Briza P, Geiser A, Bischof J, Richter K, Felder T, Rinnerthaler M. The transfer of specific mitochondrial lipids and proteins to lipid droplets contributes to proteostasis upon stress and aging in the eukaryotic model system Saccharomyces cerevisiae. GeroScience 2019; 42:19-38. [PMID: 31676965 PMCID: PMC7031196 DOI: 10.1007/s11357-019-00103-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 09/11/2019] [Indexed: 01/12/2023] Open
Abstract
Originally Lipid droplets (LDs) were considered as being droplets for lipid storage only. Increasing evidence, however, demonstrates that LDs fulfill a pleiotropy of additional functions. Among them is the modulation of protein as well as lipid homeostasis. Under unfavorable pro-oxidative conditions, proteins can form aggregates which may exceed the overall proteolytic capacity of the proteasome. After stress termination LDs can adjust and support the removal of these aggregates. Additionally, LDs interact with mitochondria, specifically take over certain proteins and thus prevent apoptosis. LDs, which are loaded with these harmful proteins, are subsequently eliminated via lipophagy. Recently it was demonstrated that this autophagic process is a modulator of longevity. LDs do not only eliminate potentially dangerous proteins, but they are also able to prevent lipotoxicity by storing specific lipids. In the present study we used the model organism Saccharomyces cerevisiae to compare the proteome as well as lipidome of mitochondria and LDs under different conditions: replicative aging, stress and apoptosis. In this context we found an accumulation of proteins at LDs, supporting the role of LDs in proteostasis. Additionally, the composition of main lipid classes such as phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols, phosphatidylglycerols, triacylglycerols, ceramides, phosphatidic acids and ergosterol of LDs and mitochondria changed during stress conditions and aging.
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Affiliation(s)
- Florian Geltinger
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Julia Tevini
- Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, Austria
| | - Peter Briza
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Amrito Geiser
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Johannes Bischof
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Klaus Richter
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Thomas Felder
- Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, Austria.
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria.
| | - Mark Rinnerthaler
- Department of Biosciences, University of Salzburg, Salzburg, Austria.
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36
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Ugrankar R, Bowerman J, Hariri H, Chandra M, Chen K, Bossanyi MF, Datta S, Rogers S, Eckert KM, Vale G, Victoria A, Fresquez J, McDonald JG, Jean S, Collins BM, Henne WM. Drosophila Snazarus Regulates a Lipid Droplet Population at Plasma Membrane-Droplet Contacts in Adipocytes. Dev Cell 2019; 50:557-572.e5. [PMID: 31422916 PMCID: PMC7446143 DOI: 10.1016/j.devcel.2019.07.021] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 04/22/2019] [Accepted: 07/17/2019] [Indexed: 01/22/2023]
Abstract
Adipocytes store nutrients as lipid droplets (LDs), but how they organize their LD stores to balance lipid uptake, storage, and mobilization remains poorly understood. Here, using Drosophila fat body (FB) adipocytes, we characterize spatially distinct LD populations that are maintained by different lipid pools. We identify peripheral LDs (pLDs) that make close contact with the plasma membrane (PM) and are maintained by lipophorin-dependent lipid trafficking. pLDs are distinct from larger cytoplasmic medial LDs (mLDs), which are maintained by FASN1-dependent de novo lipogenesis. We find that sorting nexin CG1514 or Snazarus (Snz) associates with pLDs and regulates LD homeostasis at ER-PM contact sites. Loss of SNZ perturbs pLD organization, whereas Snz over-expression drives LD expansion, triacylglyceride production, starvation resistance, and lifespan extension through a DESAT1-dependent pathway. We propose that Drosophila adipocytes maintain spatially distinct LD populations and identify Snz as a regulator of LD organization and inter-organelle crosstalk.
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Affiliation(s)
- Rupali Ugrankar
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Jade Bowerman
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Hanaa Hariri
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Mintu Chandra
- Institute for Molecular Bioscience, the University of Queensland, St. Lucia, QLD 4072, Australia
| | - Kevin Chen
- Institute for Molecular Bioscience, the University of Queensland, St. Lucia, QLD 4072, Australia
| | - Marie-France Bossanyi
- Department of Anatomy and Cell Biology, University of Sherbrooke, 2500 Boulevard de l'Universite, Sherbrooke, QC J1K 2R1, Canada
| | - Sanchari Datta
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Sean Rogers
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Kaitlyn M Eckert
- Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Gonçalo Vale
- Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Alexia Victoria
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | | | - Jeffrey G McDonald
- Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Molecular Genetics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Steve Jean
- Department of Anatomy and Cell Biology, University of Sherbrooke, 2500 Boulevard de l'Universite, Sherbrooke, QC J1K 2R1, Canada
| | - Brett M Collins
- Institute for Molecular Bioscience, the University of Queensland, St. Lucia, QLD 4072, Australia
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA.
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37
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Schott MB, Weller SG, Schulze RJ, Krueger EW, Drizyte-Miller K, Casey CA, McNiven MA. Lipid droplet size directs lipolysis and lipophagy catabolism in hepatocytes. J Cell Biol 2019; 218:3320-3335. [PMID: 31391210 PMCID: PMC6781454 DOI: 10.1083/jcb.201803153] [Citation(s) in RCA: 176] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 09/18/2018] [Accepted: 07/17/2019] [Indexed: 12/20/2022] Open
Abstract
Lipid droplet (LD) catabolism in hepatocytes is mediated by a combination of lipolysis and a selective autophagic mechanism called lipophagy, but the relative contributions of these seemingly distinct pathways remain unclear. We find that inhibition of lipolysis, lipophagy, or both resulted in similar overall LD content but dramatic differences in LD morphology. Inhibition of the lipolysis enzyme adipose triglyceride lipase (ATGL) resulted in large cytoplasmic LDs, whereas lysosomal inhibition caused the accumulation of numerous small LDs within the cytoplasm and degradative acidic vesicles. Combined inhibition of ATGL and LAL resulted in large LDs, suggesting that lipolysis targets these LDs upstream of lipophagy. Consistent with this, ATGL was enriched in larger-sized LDs, whereas lipophagic vesicles were restricted to small LDs as revealed by immunofluorescence, electron microscopy, and Western blot of size-separated LDs. These findings provide new evidence indicating a synergistic relationship whereby lipolysis targets larger-sized LDs to produce both size-reduced and nascently synthesized small LDs that are amenable for lipophagic internalization.
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Affiliation(s)
- Micah B Schott
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Shaun G Weller
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Ryan J Schulze
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Eugene W Krueger
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Kristina Drizyte-Miller
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Carol A Casey
- Department of Internal Medicine and Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE.,Research Service, Department of Veterans Affairs, Nebraska-Western Iowa Health Care System, Omaha, NE
| | - Mark A McNiven
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
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38
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Liu Q, Zhou Z, Liu P, Zhang S. Comparative proteomic study of liver lipid droplets and mitochondria in mice housed at different temperatures. FEBS Lett 2019; 593:2118-2138. [PMID: 31234227 PMCID: PMC6771624 DOI: 10.1002/1873-3468.13509] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/11/2019] [Accepted: 06/14/2019] [Indexed: 01/18/2023]
Abstract
Laboratory mice are standardly housed at around 23 °C, setting them under chronic cold stress. Metabolic changes in the liver in mice housed at thermoneutral, standard and cold temperatures remain unknown. In the present study, we isolated lipid droplets and mitochondria from their livers in a comparative proteomic study aiming to investigate the changes. According to proteomic analysis, mitochondrial tricarboxylic acid cycle (TCA cycle) and retinol metabolism are enhanced, whereas oxidative phosphorylation is not affected obviously under cold conditions, suggesting that liver mitochondria may increase TCA cycle capacity in biosynthetic pathways, as well as retinol metabolism, to help the liver to adapt. Based on proteomic and immunoblotting results, perilipin 5 and major urinary proteins are increased significantly, whereas mitochondrial pyruvate carrier is decreased dramatically under cold conditions, indicating their involvement in liver adaptation.
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Affiliation(s)
- Qingfeng Liu
- School of Basic Medical Sciences, Southwest Medical University, Luzhou, China
| | - Ziyun Zhou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Pingsheng Liu
- School of Basic Medical Sciences, Southwest Medical University, Luzhou, China.,National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Shuyan Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
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39
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Mechanisms of lipid droplet biogenesis. Biochem J 2019; 476:1929-1942. [DOI: 10.1042/bcj20180021] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 06/11/2019] [Accepted: 06/13/2019] [Indexed: 12/28/2022]
Abstract
Abstract
Lipid droplets (LDs) are organelles that compartmentalize nonbilayer-forming lipids in the aqueous cytoplasm of cells. They are ubiquitous in most organisms, including in animals, protists, plants and microorganisms. In eukaryotes, LDs are believed to be derived by a budding and scission process from the surface of the endoplasmic reticulum, and this occurs concomitantly with the accumulation of neutral lipids, most often triacylglycerols and steryl esters. Overall, the mechanisms underlying LD biogenesis are difficult to generalize, in part because of the involvement of different sets of both evolutionarily conserved and organism-specific LD-packaging proteins. Here, we briefly compare and contrast these proteins and the allied processes responsible for LD biogenesis in cells of animals, yeasts and plants.
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40
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Wang Y, Kory N, BasuRay S, Cohen JC, Hobbs HH. PNPLA3, CGI-58, and Inhibition of Hepatic Triglyceride Hydrolysis in Mice. Hepatology 2019; 69:2427-2441. [PMID: 30802989 PMCID: PMC6563103 DOI: 10.1002/hep.30583] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 02/16/2019] [Indexed: 12/12/2022]
Abstract
A variant (148M) in patatin-like phospholipase domain-containing protein 3 (PNPLA3) is a major risk factor for fatty liver disease. Despite its clinical importance, the pathogenic mechanism linking the variant to liver disease remains poorly defined. Previously, we showed that PNPLA3(148M) accumulates to high levels on hepatic lipid droplets (LDs). Here we examined the effect of that accumulation on triglyceride (TG) hydrolysis by adipose triglyceride lipase (ATGL), the major lipase in the liver. As expected, overexpression of ATGL in cultured hepatoma (HuH-7) cells depleted the cells of LDs, but unexpectedly, co-expression of PNPLA3(wild type [WT] or 148M) with ATGL inhibited that depletion. The inhibitory effect of PNPLA3 was not caused by the displacement of ATGL from LDs. We tested the hypothesis that PNPLA3 interferes with ATGL activity by interacting with its cofactor, comparative gene identification-58 (CGI-58). Evidence supporting such an interaction came from two findings. First, co-expression of PNPLA3 and CGI-58 resulted in LD depletion in cultured cells, but expression of PNPLA3 alone did not. Second, PNPLA3 failed to localize to hepatic LDs in liver-specific Cgi-58 knockout (KO) mice. Moreover, overexpression of PNPLA3(148M) increased hepatic TG levels in WT, but not in Cgi-58 KO mice. Thus, the pro-steatotic effects of PNPLA3 required the presence of CGI-58. Co-immunoprecipitation and pulldown experiments in livers of mice and in vitro using purified proteins provided evidence that PNPLA3 and CGI-58 can interact directly. Conclusion: Taken together, these findings are consistent with a model in which PNPLA3(148M) promotes steatosis by CGI-58-dependent inhibition of ATGL on LDs.
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Affiliation(s)
- Yang Wang
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Nora Kory
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Soumik BasuRay
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Jonathan C. Cohen
- Department of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTX,The Center for Human NutritionUniversity of Texas Southwestern Medical CenterDallas TX
| | - Helen H. Hobbs
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX,Department of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTX,Howard Hughes Medical InstituteUniversity of Texas Southwestern Medical CenterDallasTX
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41
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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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42
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Benador IY, Veliova M, Liesa M, Shirihai OS. Mitochondria Bound to Lipid Droplets: Where Mitochondrial Dynamics Regulate Lipid Storage and Utilization. Cell Metab 2019; 29:827-835. [PMID: 30905670 PMCID: PMC6476311 DOI: 10.1016/j.cmet.2019.02.011] [Citation(s) in RCA: 173] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 01/21/2019] [Accepted: 02/21/2019] [Indexed: 01/09/2023]
Abstract
The isolation and biochemical characterization of lipid droplet (LD)-associated mitochondria revealed the capacity of the cell to produce and maintain distinct mitochondrial populations carrying disparate proteome and dissimilar capacities to oxidize fatty acids and pyruvate. With mitochondrial motility being a central parameter determining mitochondrial fusion, adherence to LDs provides a mechanism by which peridroplet mitochondria (PDM) remain segregated from cytoplasmic mitochondria (CM). The existence of metabolically distinct subpopulations provides an explanation for the capacity of mitochondria within the individual cell to be involved simultaneously in fatty acid oxidation and LD formation. The mechanisms that deploy mitochondria to the LD and the dysfunctions that result from unbalanced proportions of PDM and CM remain to be explored. Understanding the roles and regulation of mitochondrial tethering to LDs offers new points of intervention in metabolic diseases.
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Affiliation(s)
- Ilan Y Benador
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Michaela Veliova
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Marc Liesa
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; UCLA Molecular Biology Institute, Los Angeles, CA, USA.
| | - Orian S Shirihai
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, MA, USA.
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43
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Chali F, Milior G, Marty S, Morin-Brureau M, Le Duigou C, Savary E, Blugeon C, Jourdren L, Miles R. Lipid markers and related transcripts during excitotoxic neurodegeneration in kainate-treated mice. Eur J Neurosci 2019; 50:1759-1778. [PMID: 30767299 DOI: 10.1111/ejn.14375] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 01/30/2019] [Accepted: 01/31/2019] [Indexed: 12/16/2022]
Abstract
Lipid homeostasis is dysregulated in some neurodegenerative diseases and after brain injuries due to excess glutamate or lack of oxygen. However the kinetics and cell specificity of dysregulation in different groups of lipids during excitotoxic neuronal death are not clear. Here we examined the changes during excitotoxic neuronal death induced by injecting kainic acid (KA) into the CA1 region of mouse hippocampus. We compared neuronal loss and glial cell proliferation with changes in lipid-related transcripts and markers for different lipid groups, over 12 days after KA-treatment. As neurons showed initial signs of damage, transcripts and proteins linked to fatty acid oxidation were up-regulated. Cholesterol biosynthesis induced by transcripts controlled by the transcription factor Srebp2 seems to be responsible for a transient increase in neuronal free cholesterol at 1 to 2 days. In microglia, but not in neurons, Perilipin-2 associated lipid droplets were induced and properties of Nile red emissions suggest lipid contents change over time. After microglial expression of phagocytotic markers at 2 days, some neutral lipid deposits co-localized with lysosome markers of microglia and were detected within putative phagocytotic cups. These data delineate distinct lipid signals in neurons and glial cells during excitotoxic processes from initial neuronal damage to engagement of the lysosome-phagosome system.
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Affiliation(s)
- Farah Chali
- Inserm U1127, CNRS UMR7225, Sorbonne Université, UPMC Université Paris 6 UMR S1127, Institut du Cerveau et de la Moelle Epinière, CHU Pitié-Salpêtrière, Paris, France
| | - Giampaolo Milior
- Inserm U1127, CNRS UMR7225, Sorbonne Université, UPMC Université Paris 6 UMR S1127, Institut du Cerveau et de la Moelle Epinière, CHU Pitié-Salpêtrière, Paris, France
| | - Serge Marty
- Inserm U1127, CNRS UMR7225, Sorbonne Université, UPMC Université Paris 6 UMR S1127, Institut du Cerveau et de la Moelle Epinière, CHU Pitié-Salpêtrière, Paris, France
| | - Mélanie Morin-Brureau
- Inserm U1127, CNRS UMR7225, Sorbonne Université, UPMC Université Paris 6 UMR S1127, Institut du Cerveau et de la Moelle Epinière, CHU Pitié-Salpêtrière, Paris, France
| | - Caroline Le Duigou
- Inserm U1127, CNRS UMR7225, Sorbonne Université, UPMC Université Paris 6 UMR S1127, Institut du Cerveau et de la Moelle Epinière, CHU Pitié-Salpêtrière, Paris, France
| | - Etienne Savary
- Inserm U1127, CNRS UMR7225, Sorbonne Université, UPMC Université Paris 6 UMR S1127, Institut du Cerveau et de la Moelle Epinière, CHU Pitié-Salpêtrière, Paris, France
| | - Corinne Blugeon
- Institut de Biologie de l'École normale supérieure (IBENS), École Normale Supérieure, CNRS, INSERM PSL Université Paris, Paris, France
| | - Laurent Jourdren
- Institut de Biologie de l'École normale supérieure (IBENS), École Normale Supérieure, CNRS, INSERM PSL Université Paris, Paris, France
| | - Richard Miles
- Inserm U1127, CNRS UMR7225, Sorbonne Université, UPMC Université Paris 6 UMR S1127, Institut du Cerveau et de la Moelle Epinière, CHU Pitié-Salpêtrière, Paris, France
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44
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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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45
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Neutral Lipid Storage Diseases as Cellular Model to Study Lipid Droplet Function. Cells 2019; 8:cells8020187. [PMID: 30795549 PMCID: PMC6406896 DOI: 10.3390/cells8020187] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 02/14/2019] [Accepted: 02/19/2019] [Indexed: 01/10/2023] Open
Abstract
Neutral lipid storage disease with myopathy (NLSDM) and with ichthyosis (NLSDI) are rare autosomal recessive disorders caused by mutations in the PNPLA2 and in the ABHD5/CGI58 genes, respectively. These genes encode the adipose triglyceride lipase (ATGL) and α-β hydrolase domain 5 (ABHD5) proteins, which play key roles in the function of lipid droplets (LDs). LDs, the main cellular storage sites of triacylglycerols and sterol esters, are highly dynamic organelles. Indeed, LDs are critical for both lipid metabolism and energy homeostasis. Partial or total PNPLA2 or ABHD5/CGI58 knockdown is characteristic of the cells of NLSD patients; thus, these cells are natural models with which one can unravel LD function. In this review we firstly summarize genetic and clinical data collected from NLSD patients, focusing particularly on muscle, skin, heart, and liver damage due to impaired LD function. Then, we discuss how NLSD cells were used to investigate and expand the current structural and functional knowledge of LDs.
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46
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Collot M, Bou S, Fam TK, Richert L, Mély Y, Danglot L, Klymchenko AS. Probing Polarity and Heterogeneity of Lipid Droplets in Live Cells Using a Push–Pull Fluorophore. Anal Chem 2018; 91:1928-1935. [DOI: 10.1021/acs.analchem.8b04218] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Mayeul Collot
- Laboratoire de Biophotonique et Pathologies, Faculté de Pharmacie, UMR 7021 CNRS, Université de Strasbourg, 74, Route du Rhin, 67401 Cedex, Illkirch, France
| | - Sophie Bou
- Laboratoire de Biophotonique et Pathologies, Faculté de Pharmacie, UMR 7021 CNRS, Université de Strasbourg, 74, Route du Rhin, 67401 Cedex, Illkirch, France
| | - Tkhe Kyong Fam
- Laboratoire de Biophotonique et Pathologies, Faculté de Pharmacie, UMR 7021 CNRS, Université de Strasbourg, 74, Route du Rhin, 67401 Cedex, Illkirch, France
| | - Ludovic Richert
- Laboratoire de Biophotonique et Pathologies, Faculté de Pharmacie, UMR 7021 CNRS, Université de Strasbourg, 74, Route du Rhin, 67401 Cedex, Illkirch, France
| | - Yves Mély
- Laboratoire de Biophotonique et Pathologies, Faculté de Pharmacie, UMR 7021 CNRS, Université de Strasbourg, 74, Route du Rhin, 67401 Cedex, Illkirch, France
| | - Lydia Danglot
- Institut Jacques Monod, University Paris Diderot, Sorbonne Paris Cité, CNRS UMR 7592, 75013 Paris, France
- Membrane Traffic in Healthy and Diseased Brain, INSERM U894, Institute of Psychiatry and Neuroscience of Paris, 102 rue de la Santé, 75 014 Paris, France
| | - Andrey S. Klymchenko
- Laboratoire de Biophotonique et Pathologies, Faculté de Pharmacie, UMR 7021 CNRS, Université de Strasbourg, 74, Route du Rhin, 67401 Cedex, Illkirch, France
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47
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Pirola CJ, Garaycoechea M, Flichman D, Arrese M, San Martino J, Gazzi C, Castaño GO, Sookoian S. Splice variant rs72613567 prevents worst histologic outcomes in patients with nonalcoholic fatty liver disease. J Lipid Res 2018; 60:176-185. [PMID: 30323112 DOI: 10.1194/jlr.p089953] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 10/04/2018] [Indexed: 12/12/2022] Open
Abstract
Hydroxysteroid 17-β dehydrogenase 13 (HSD17B13) is a lipid droplet-associated protein; its gene-encoding variants affect the chronic liver diseases, including nonalcoholic fatty liver disease (NAFLD). To estimate the effect of rs72613567, a splice variant with an adenine insertion (A-INS), on NAFLD susceptibility and severity, we performed a case-control study with 609 individuals. We investigated the effect of carrying the A-INS allele in 356 patients with biopsy-proven disease and explored the relationship between rs72613567 genotypes and the hepatic transcriptome. The A-INS allele protected against NAFLD [odds ratio (OR) per adenine allele = 0.667; 95% CI, 0.486-0.916; P = 0.012]; this effect was nonsignificant when logistic regression analysis included BMI. The A-INS allele protected against nonalcoholic steatohepatitis (NASH) (OR = 0.612; 95% CI, 0.388-0.964; P = 0.033), ballooning degeneration (OR = 0.474; 95% CI, 0.267-0.842; P = 0.01), lobular inflammation (OR = 0.475; 95% CI, 0.275-0.821; P = 0.007), and fibrosis (OR = 0.590; 95% CI, 0.361-0.965; P = 0.035). In patients carrying A-INS, HSD17B13 levels decreased proportionally to allele dosage. Whole-transcriptome genotype profiling showed overrepresented immune response-related pathways. Thus, the rs72613567 A-INS allele reduces the risk of NASH and progressive liver damage and may become a therapeutic target.
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Affiliation(s)
- Carlos J Pirola
- Institute of Medical Research A. Lanari, School of Medicine, University of Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina .,Departments of Molecular Genetics and Biology of Complex Diseases, University of Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina.,Department of Surgery and Centro de Medicina Translacional (CEMET), Hospital de Alta Complejidad en Red "El Cruce", Florencio Varela, Buenos Aires, Argentina
| | - Martin Garaycoechea
- Department of Surgery and Centro de Medicina Translacional (CEMET), Hospital de Alta Complejidad en Red "El Cruce", Florencio Varela, Buenos Aires, Argentina
| | - Diego Flichman
- Department of Virology, School of Pharmacy and Biochemistry, University of Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - Marco Arrese
- Department of Gastroenterology, School of Medicine and Centro de Envejecimiento y Regeneración (CARE), Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Julio San Martino
- Department of Pathology, Hospital Diego Thompson, San Martin, Buenos Aires, Argentina
| | - Carla Gazzi
- Pathology Department, Institute of Medical Research A. Lanari, School of Medicine, University of Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - Gustavo O Castaño
- Liver Unit, Medicine and Surgery Department, Hospital Abel Zubizarreta, Ciudad Autónoma de Buenos Aires, Argentina
| | - Silvia Sookoian
- Institute of Medical Research A. Lanari, School of Medicine, University of Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina .,Clinical and Molecular Hepatology, National Scientific and Technical Research Council (CONICET), Institute of Medical Research (IDIM), University of Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
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48
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Zhang C, Liu P. The New Face of the Lipid Droplet: Lipid Droplet Proteins. Proteomics 2018; 19:e1700223. [DOI: 10.1002/pmic.201700223] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 08/13/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Congyan Zhang
- National Laboratory of BiomacromoleculesCAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of Sciences Beijing 100101 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Pingsheng Liu
- National Laboratory of BiomacromoleculesCAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of Sciences Beijing 100101 China
- University of Chinese Academy of Sciences Beijing 100049 China
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49
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Kretzschmar FK, Mengel LA, Müller AO, Schmitt K, Blersch KF, Valerius O, Braus GH, Ischebeck T. PUX10 Is a Lipid Droplet-Localized Scaffold Protein That Interacts with CELL DIVISION CYCLE48 and Is Involved in the Degradation of Lipid Droplet Proteins. THE PLANT CELL 2018; 30:2137-2160. [PMID: 30087207 PMCID: PMC6181012 DOI: 10.1105/tpc.18.00276] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/12/2018] [Accepted: 07/31/2018] [Indexed: 05/07/2023]
Abstract
The number of known proteins associated with plant lipid droplets (LDs) is small compared with other organelles. Many aspects of LD biosynthesis and degradation are unknown, and identifying and characterizing candidate LD proteins could help elucidate these processes. Here, we analyzed the proteome of LD-enriched fractions isolated from tobacco (Nicotiana tabacum) pollen tubes. Proteins that were highly enriched in comparison with the total or cytosolic fraction were further tested for LD localization via transient expression in pollen tubes. One of these proteins, PLANT UBX DOMAIN-CONTAINING PROTEIN10 (PUX10), is a member of the plant UBX domain-containing (PUX) protein family. This protein localizes to LDs via a unique hydrophobic polypeptide sequence and can recruit the AAA-type ATPase CELL DIVISION CYCLE48 (CDC48) protein via its UBX domain. PUX10 is conserved in Arabidopsis thaliana and expressed in embryos, pollen tubes, and seedlings. In pux10 knockout mutants in Arabidopsis, LD size is significantly increased. Proteomic analysis of pux10 mutants revealed a delayed degradation of known LD proteins, some of which possessed ubiquitination sites. We propose that PUX10 is involved in a protein degradation pathway at LDs, mediating an interaction between polyubiquitinated proteins targeted for degradation and downstream effectors such as CDC48.
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Affiliation(s)
- Franziska K Kretzschmar
- Department of Plant Biochemistry, Georg-August-University, Albrecht-von-Haller-Institute for Plant Sciences, 37077 Göttingen, Germany
| | - Laura A Mengel
- Department of Plant Biochemistry, Georg-August-University, Albrecht-von-Haller-Institute for Plant Sciences, 37077 Göttingen, Germany
| | - Anna O Müller
- Department of Plant Biochemistry, Georg-August-University, Albrecht-von-Haller-Institute for Plant Sciences, 37077 Göttingen, Germany
| | - Kerstin Schmitt
- Department of Molecular Microbiology and Genetics, Georg-August-University, Institute for Microbiology and Genetics, 37077 Göttingen, Germany
| | - Katharina F Blersch
- Department of Plant Biochemistry, Georg-August-University, Albrecht-von-Haller-Institute for Plant Sciences, 37077 Göttingen, Germany
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics, Georg-August-University, Institute for Microbiology and Genetics, 37077 Göttingen, Germany
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics, Georg-August-University, Institute for Microbiology and Genetics, 37077 Göttingen, Germany
| | - Till Ischebeck
- Department of Plant Biochemistry, Georg-August-University, Albrecht-von-Haller-Institute for Plant Sciences, 37077 Göttingen, Germany
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50
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Deruyffelaere C, Purkrtova Z, Bouchez I, Collet B, Cacas JL, Chardot T, Gallois JL, D'Andrea S. PUX10 Is a CDC48A Adaptor Protein That Regulates the Extraction of Ubiquitinated Oleosins from Seed Lipid Droplets in Arabidopsis. THE PLANT CELL 2018; 30:2116-2136. [PMID: 30087208 PMCID: PMC6181022 DOI: 10.1105/tpc.18.00275] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/06/2018] [Accepted: 07/31/2018] [Indexed: 05/19/2023]
Abstract
Postgerminative mobilization of neutral lipids stored in seed lipid droplets (LDs) is preceded by the degradation of oleosins, the major structural LD proteins that stabilize LDs in dry seeds. We previously showed that Arabidopsis thaliana oleosins are marked for degradation by ubiquitination and are extracted from LDs before proteolysis. However, the mechanisms underlying the dislocation of these LD-anchored proteins from the LD monolayer are yet unknown. Here, we report that PUX10, a member of the plant UBX-domain containing (PUX) protein family, is an integral LD protein that associates with a subpopulation of LDs during seed germination. In pux10 mutant seedlings, PUX10 deficiency impaired the degradation of ubiquitinated oleosins and prevented the extraction of ubiquitinated oleosins from LDs. We also showed that PUX10 interacts with ubiquitin and CDC48A, the AAA ATPase Cell Division Cycle 48, through its UBA and UBX domains, respectively. Collectively, these results strongly suggest that PUX10 is an adaptor recruiting CDC48A to ubiquitinated oleosins, thus facilitating the dislocation of oleosins from LDs by the segregase activity of CDC48A. We propose that PUX10 and CDC48A are core components of a LD-associated degradation machinery, which we named the LD-associated degradation system. Importantly, PUX10 is also the first determinant of a LD subpopulation described in plants, suggesting functional differentiation of LDs in Arabidopsis seedlings.
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Affiliation(s)
- Carine Deruyffelaere
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000 Versailles, France
| | - Zita Purkrtova
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000 Versailles, France
| | - Isabelle Bouchez
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000 Versailles, France
| | - Boris Collet
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000 Versailles, France
| | - Jean-Luc Cacas
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000 Versailles, France
| | - Thierry Chardot
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000 Versailles, France
| | | | - Sabine D'Andrea
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000 Versailles, France
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