1
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Tang Y, Majewska M, Leß B, Mehmeti I, Wollnitzke P, Semleit N, Levkau B, Saba JD, van Echten-Deckert G, Gurgul-Convey E. The fate of intracellular S1P regulates lipid droplet turnover and lipotoxicity in pancreatic beta-cells. J Lipid Res 2024; 65:100587. [PMID: 38950680 PMCID: PMC11345310 DOI: 10.1016/j.jlr.2024.100587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 06/07/2024] [Accepted: 06/22/2024] [Indexed: 07/03/2024] Open
Abstract
Lipotoxicity has been considered the main cause of pancreatic beta-cell failure during type 2 diabetes development. Lipid droplets (LD) are believed to regulate the beta-cell sensitivity to free fatty acids (FFA), but the underlying molecular mechanisms are largely unclear. Accumulating evidence points, however, to an important role of intracellular sphingosine-1-phosphate (S1P) metabolism in lipotoxicity-mediated disturbances of beta-cell function. In the present study, we compared the effects of an increased irreversible S1P degradation (S1P-lyase, SPL overexpression) with those associated with an enhanced S1P recycling (overexpression of S1P phosphatase 1, SGPP1) on LD formation and lipotoxicity in rat INS1E beta-cells. Interestingly, although both approaches led to a reduced S1P concentration, they had opposite effects on the susceptibility to FFA. Overexpression of SGPP1 prevented FFA-mediated caspase-3 activation by a mechanism involving an enhanced lipid storage capacity and prevention of oxidative stress. In contrast, SPL overexpression limited LD biogenesis, content, and size, while accelerating lipophagy. This was associated with FFA-induced hydrogen peroxide formation, mitochondrial fragmentation, and dysfunction, as well as ER stress. These changes coincided with the upregulation of proapoptotic ceramides but were independent of lipid peroxidation rate. Also in human EndoC-βH1 beta-cells, suppression of SPL with simultaneous overexpression of SGPP1 led to a similar and even more pronounced LD phenotype as that in INS1E-SGPP1 cells. Thus, intracellular S1P turnover significantly regulates LD content and size and influences beta-cell sensitivity to FFA.
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Affiliation(s)
- Yadi Tang
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Mariola Majewska
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Britta Leß
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Ilir Mehmeti
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Philipp Wollnitzke
- Institute of Molecular Medicine III, University Hospital Düsseldorf and Heinrich Heine University, Düsseldorf, Germany
| | - Nina Semleit
- Institute of Molecular Medicine III, University Hospital Düsseldorf and Heinrich Heine University, Düsseldorf, Germany
| | - Bodo Levkau
- Institute of Molecular Medicine III, University Hospital Düsseldorf and Heinrich Heine University, Düsseldorf, Germany
| | - Julie D Saba
- Division of Hematology/Oncology, Department of Pediatrics, University of California. San Francisco, Oakland, CA, USA
| | | | - Ewa Gurgul-Convey
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany.
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2
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Chiariello A, Rossetti L, Valente S, Pasquinelli G, Sollazzo M, Iommarini L, Porcelli AM, Tognocchi M, Conte G, Santoro A, Kwiatkowska KM, Garagnani P, Salvioli S, Conte M. Downregulation of PLIN2 in human dermal fibroblasts impairs mitochondrial function in an age-dependent fashion and induces cell senescence via GDF15. Aging Cell 2024; 23:e14111. [PMID: 38650174 PMCID: PMC11113257 DOI: 10.1111/acel.14111] [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: 12/01/2023] [Revised: 01/29/2024] [Accepted: 01/31/2024] [Indexed: 04/25/2024] Open
Abstract
Perilipin 2 (PLIN2) is a lipid droplet (LD)-coating protein playing important roles in lipid homeostasis and suppression of lipotoxicity in different tissues and cell types. Recently, a role for PLIN2 in supporting mitochondrial function has emerged. PLIN2 dysregulation is involved in many metabolic disorders and age-related diseases. However, the exact consequences of PLIN2 dysregulation are not yet completely understood. In this study, we knocked down (KD) PLIN2 in primary human dermal fibroblasts (hDFs) from young (mean age 29 years) and old (mean age 71 years) healthy donors. We have found that PLIN2 KD caused a decline of mitochondrial function only in hDFs from young donors, while mitochondria of hDFs from old donors (that are already partially impaired) did not significantly worsen upon PLIN2 KD. This mitochondrial impairment is associated with the increased expression of the stress-related mitokine growth differentiation factor 15 (GDF15) and the induction of cell senescence. Interestingly, the simultaneous KD of PLIN2 and GDF15 abrogated the induction of cell senescence, suggesting that the increase in GDF15 is the mediator of this phenomenon. Moreover, GDF15 KD caused a profound alteration of gene expression, as observed by RNA-Seq analysis. After a more stringent analysis, this alteration remained statistically significant only in hDFs from young subjects, further supporting the idea that cells from old and young donors react differently when undergoing manipulation of either PLIN2 or GDF15 genes, with the latter being likely a downstream mediator of the former.
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Affiliation(s)
- Antonio Chiariello
- Department of Medical and Surgical Sciences (DIMEC)University of BolognaBolognaItaly
| | - Luca Rossetti
- Department of Medical and Surgical Sciences (DIMEC)University of BolognaBolognaItaly
- Interdepartmental Centre “Alma Mater Research Institute on Global Challenges and Climate Change (Alma Climate)”University of BolognaBolognaItaly
| | - Sabrina Valente
- Department of Medical and Surgical Sciences (DIMEC)University of BolognaBolognaItaly
| | - Gianandrea Pasquinelli
- Department of Medical and Surgical Sciences (DIMEC)University of BolognaBolognaItaly
- IRCCS Azienda Ospedaliero‐Universitaria di BolognaBolognaItaly
| | - Manuela Sollazzo
- Department of Pharmacy and Biotechnology (FABIT)University of BolognaBolognaItaly
| | - Luisa Iommarini
- Department of Pharmacy and Biotechnology (FABIT)University of BolognaBolognaItaly
| | - Anna Maria Porcelli
- Department of Pharmacy and Biotechnology (FABIT)University of BolognaBolognaItaly
| | - Monica Tognocchi
- Department of Agriculture, Food and EnvironmentUniversity of PisaPisaItaly
| | - Giuseppe Conte
- Department of Agriculture, Food and EnvironmentUniversity of PisaPisaItaly
| | - Aurelia Santoro
- Department of Medical and Surgical Sciences (DIMEC)University of BolognaBolognaItaly
| | | | - Paolo Garagnani
- Department of Medical and Surgical Sciences (DIMEC)University of BolognaBolognaItaly
- IRCCS Azienda Ospedaliero‐Universitaria di BolognaBolognaItaly
| | - Stefano Salvioli
- Department of Medical and Surgical Sciences (DIMEC)University of BolognaBolognaItaly
- IRCCS Azienda Ospedaliero‐Universitaria di BolognaBolognaItaly
| | - Maria Conte
- Department of Medical and Surgical Sciences (DIMEC)University of BolognaBolognaItaly
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3
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Enkler L, Spang A. Functional interplay of lipid droplets and mitochondria. FEBS Lett 2024; 598:1235-1251. [PMID: 38268392 DOI: 10.1002/1873-3468.14809] [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: 10/12/2023] [Revised: 12/12/2023] [Accepted: 01/04/2024] [Indexed: 01/26/2024]
Abstract
Our body stores energy mostly in form of fatty acids (FAs) in lipid droplets (LDs). From there the FAs can be mobilized and transferred to peroxisomes and mitochondria. This transfer is dependent on close opposition of LDs and mitochondria and peroxisomes and happens at membrane contact sites. However, the composition and the dynamics of these contact sites is not well understood, which is in part due to the dependence on the metabolic state of the cell and on the cell- and tissue-type. Here, we summarize the current knowledge on the contacts between lipid droplets and mitochondria both in mammals and in the yeast Saccharomyces cerevisiae, in which various contact sites are well studied. We discuss possible functions of the contact site and their implication in disease.
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Affiliation(s)
| | - Anne Spang
- Biozentrum, University of Basel, Switzerland
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4
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Kovacs M, Geltinger F, Schartel L, Pöschl S, Briza P, Paschinger M, Boros K, Felder TK, Wimmer H, Duschl J, Rinnerthaler M. Ola1p trafficking indicates an interaction network between mitochondria, lipid droplets, and stress granules in times of stress. J Lipid Res 2023; 64:100473. [PMID: 37949369 PMCID: PMC10757043 DOI: 10.1016/j.jlr.2023.100473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 09/25/2023] [Accepted: 11/01/2023] [Indexed: 11/12/2023] Open
Abstract
Protein aggregates arise naturally under normal physiological conditions, but their formation is accelerated by age or stress-induced protein misfolding. When the stressful event dissolves, these aggregates are removed by mechanisms, such as aggrephagy, chaperone-mediated autophagy, refolding attempts, or the proteasome. It was recently shown that mitochondria in yeast cells may support these primarily cytosolic processes. Protein aggregates attach to mitochondria, and misfolded proteins are transported into the matrix and degraded by mitochondria-specific proteases. Using a proximity labeling method and colocalization with an established stress granule (SG) marker, we were able to show that these mitochondria-localized aggregates that harbor the "super aggregator" Ola1p are, in fact, SGs. Our in vivo and in vitro studies have revealed that Ola1p can be transferred from mitochondria to lipid droplets (LDs). This "mitochondria to LD" aggregate transfer dampens proteotoxic effects. The LD-based protein aggregate removal system gains importance when other proteolytic systems fail. Furthermore, we were able to show that the distribution of SGs is drastically altered in LD-deficient yeast cells, demonstrating that LDs play a role in the SG life cycle.
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Affiliation(s)
- Melanie Kovacs
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Florian Geltinger
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria; Institute of Functional Anatomy, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Lukas Schartel
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria; Biocentre, Departments of Biology and Chemistry, Johannes Gutenberg University and Institute of Molecular Biology, Mainz, Germany
| | - Simon Pöschl
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Peter Briza
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Manuel Paschinger
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Kitti Boros
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Thomas Klaus Felder
- Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, Austria
| | - Herbert Wimmer
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Jutta Duschl
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
| | - Mark Rinnerthaler
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria.
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5
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Sharma R, Diwan B. Lipids and the hallmarks of ageing: From pathology to interventions. Mech Ageing Dev 2023; 215:111858. [PMID: 37652278 DOI: 10.1016/j.mad.2023.111858] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/21/2023] [Accepted: 08/28/2023] [Indexed: 09/02/2023]
Abstract
Lipids are critical structural and functional architects of cellular homeostasis. Change in systemic lipid profile is a clinical indicator of underlying metabolic pathologies, and emerging evidence is now defining novel roles of lipids in modulating organismal ageing. Characteristic alterations in lipid metabolism correlate with age, and impaired systemic lipid profile can also accelerate the development of ageing phenotype. The present work provides a comprehensive review of the extent of lipids as regulators of the modern hallmarks of ageing viz., cellular senescence, chronic inflammation, gut dysbiosis, telomere attrition, genome instability, proteostasis and autophagy, epigenetic alterations, and stem cells dysfunctions. Current evidence on the modulation of each of these hallmarks has been discussed with emphasis on inherent age-dependent deficiencies in lipid metabolism as well as exogenous lipid changes. There appears to be sufficient evidence to consider impaired lipid metabolism as key driver of the ageing process although much of knowledge is yet fragmented. Considering dietary lipids, the type and quantity of lipids in the diet is a significant, but often overlooked determinant that governs the effects of lipids on ageing. Further research using integrative approaches amidst the known aging hallmarks is highly desirable for understanding the therapeutics of lipids associated with ageing.
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Affiliation(s)
- Rohit Sharma
- Nutrigerontology Laboratory, Faculty of Applied Sciences & Biotechnology, Shoolini University, Solan 173229, India.
| | - Bhawna Diwan
- Nutrigerontology Laboratory, Faculty of Applied Sciences & Biotechnology, Shoolini University, Solan 173229, India
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6
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Valencia-Olvera AC, Balu D, Faulk N, Amiridis A, Wang Y, Pham C, Avila-Munoz E, York JM, Thatcher GRJ, LaDu MJ. Inhibition of ACAT as a Therapeutic Target for Alzheimer's Disease Is Independent of ApoE4 Lipidation. Neurotherapeutics 2023; 20:1120-1137. [PMID: 37157042 PMCID: PMC10457278 DOI: 10.1007/s13311-023-01375-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2023] [Indexed: 05/10/2023] Open
Abstract
APOE4, encoding apolipoprotein E4 (apoE4), is the greatest genetic risk factor for Alzheimer's disease (AD), compared to the common APOE3. While the mechanism(s) underlying APOE4-induced AD risk remains unclear, increasing the lipidation of apoE4 is an important therapeutic target as apoE4-lipoproteins are poorly lipidated compared to apoE3-lipoproteins. ACAT (acyl-CoA: cholesterol-acyltransferase) catalyzes the formation of intracellular cholesteryl-ester droplets, reducing the intracellular free cholesterol (FC) pool. Thus, inhibiting ACAT increases the FC pool and facilitates lipid secretion to extracellular apoE-containing lipoproteins. Previous studies using commercial ACAT inhibitors, including avasimibe (AVAS), as well as ACAT-knock out (KO) mice, exhibit reduced AD-like pathology and amyloid precursor protein (APP) processing in familial AD (FAD)-transgenic (Tg) mice. However, the effects of AVAS with human apoE4 remain unknown. In vitro, AVAS induced apoE efflux at concentrations of AVAS measured in the brains of treated mice. AVAS treatment of male E4FAD-Tg mice (5xFAD+/-APOE4+/+) at 6-8 months had no effect on plasma cholesterol levels or distribution, the original mechanism for AVAS treatment of CVD. In the CNS, AVAS reduced intracellular lipid droplets, indirectly demonstrating target engagement. Surrogate efficacy was demonstrated by an increase in Morris water maze measures of memory and postsynaptic protein levels. Amyloid-beta peptide (Aβ) solubility/deposition and neuroinflammation were reduced, critical components of APOE4-modulated pathology. However, there was no increase in apoE4 levels or apoE4 lipidation, while amyloidogenic and non-amyloidogenic processing of APP were significantly reduced. This suggests that the AVAS-induced reduction in Aβ via reduced APP processing was sufficient to reduce AD pathology, as apoE4-lipoproteins remained poorly lipidated.
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Affiliation(s)
- Ana C. Valencia-Olvera
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - Deebika Balu
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - Naomi Faulk
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612 USA
| | | | - Yueting Wang
- Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, IL 60612 USA
- Present Address: AbbVie Inc., 1 N. Waukegan Road, North Chicago, IL 60064 USA
| | - Christine Pham
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - Eva Avila-Munoz
- Syneos Health, Av. Gustavo Baz 309, La Loma, Tlalnepantla de Baz, 54060 Mexico
| | - Jason M. York
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - Gregory R. J. Thatcher
- Department of Pharmacology & Toxicology, University of Arizona, 1703 E Mabel St., Tucson, AZ 85721 USA
| | - Mary Jo LaDu
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612 USA
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7
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Bresgen N, Kovacs M, Lahnsteiner A, Felder TK, Rinnerthaler M. The Janus-Faced Role of Lipid Droplets in Aging: Insights from the Cellular Perspective. Biomolecules 2023; 13:912. [PMID: 37371492 PMCID: PMC10301655 DOI: 10.3390/biom13060912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/22/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
It is widely accepted that nine hallmarks-including mitochondrial dysfunction, epigenetic alterations, and loss of proteostasis-exist that describe the cellular aging process. Adding to this, a well-described cell organelle in the metabolic context, namely, lipid droplets, also accumulates with increasing age, which can be regarded as a further aging-associated process. Independently of their essential role as fat stores, lipid droplets are also able to control cell integrity by mitigating lipotoxic and proteotoxic insults. As we will show in this review, numerous longevity interventions (such as mTOR inhibition) also lead to strong accumulation of lipid droplets in Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, and mammalian cells, just to name a few examples. In mammals, due to the variety of different cell types and tissues, the role of lipid droplets during the aging process is much more complex. Using selected diseases associated with aging, such as Alzheimer's disease, Parkinson's disease, type II diabetes, and cardiovascular disease, we show that lipid droplets are "Janus"-faced. In an early phase of the disease, lipid droplets mitigate the toxicity of lipid peroxidation and protein aggregates, but in a later phase of the disease, a strong accumulation of lipid droplets can cause problems for cells and tissues.
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Affiliation(s)
- Nikolaus Bresgen
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria; (N.B.)
| | - Melanie Kovacs
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria; (N.B.)
| | - Angelika Lahnsteiner
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria; (N.B.)
| | - Thomas Klaus Felder
- Department of Laboratory Medicine, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Mark Rinnerthaler
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria; (N.B.)
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8
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Papsdorf K, Miklas JW, Hosseini A, Cabruja M, Morrow CS, Savini M, Yu Y, Silva-García CG, Haseley NR, Murphy LM, Yao P, de Launoit E, Dixon SJ, Snyder MP, Wang MC, Mair WB, Brunet A. Lipid droplets and peroxisomes are co-regulated to drive lifespan extension in response to mono-unsaturated fatty acids. Nat Cell Biol 2023; 25:672-684. [PMID: 37127715 PMCID: PMC10185472 DOI: 10.1038/s41556-023-01136-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 03/23/2023] [Indexed: 05/03/2023]
Abstract
Dietary mono-unsaturated fatty acids (MUFAs) are linked to longevity in several species. But the mechanisms by which MUFAs extend lifespan remain unclear. Here we show that an organelle network involving lipid droplets and peroxisomes is critical for MUFA-induced longevity in Caenorhabditis elegans. MUFAs upregulate the number of lipid droplets in fat storage tissues. Increased lipid droplet number is necessary for MUFA-induced longevity and predicts remaining lifespan. Lipidomics datasets reveal that MUFAs also modify the ratio of membrane lipids and ether lipids-a signature associated with decreased lipid oxidation. In agreement with this, MUFAs decrease lipid oxidation in middle-aged individuals. Intriguingly, MUFAs upregulate not only lipid droplet number but also peroxisome number. A targeted screen identifies genes involved in the co-regulation of lipid droplets and peroxisomes, and reveals that induction of both organelles is optimal for longevity. Our study uncovers an organelle network involved in lipid homeostasis and lifespan regulation, opening new avenues for interventions to delay aging.
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Affiliation(s)
| | - Jason W Miklas
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Amir Hosseini
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Matias Cabruja
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Christopher S Morrow
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Marzia Savini
- Department of Molecular and Human Genetics, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
| | - Yong Yu
- Department of Molecular and Human Genetics, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, China
| | - Carlos G Silva-García
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | | | | | - Pallas Yao
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | | | - Scott J Dixon
- Department of Biology, Stanford University, Stanford, CA, USA
| | | | - Meng C Wang
- Department of Molecular and Human Genetics, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - William B Mair
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Anne Brunet
- Department of Genetics, Stanford University, Stanford, CA, USA.
- Glenn Laboratories for the Biology of Aging, Stanford University, Stanford, CA, USA.
- Wu Tsai Institute of Neurosciences, Stanford University, Stanford, CA, USA.
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9
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Krawczyk HE, Sun S, Doner NM, Yan Q, Lim MSS, Scholz P, Niemeyer PW, Schmitt K, Valerius O, Pleskot R, Hillmer S, Braus GH, Wiermer M, Mullen RT, Ischebeck T. SEED LIPID DROPLET PROTEIN1, SEED LIPID DROPLET PROTEIN2, and LIPID DROPLET PLASMA MEMBRANE ADAPTOR mediate lipid droplet-plasma membrane tethering. THE PLANT CELL 2022; 34:2424-2448. [PMID: 35348751 PMCID: PMC9134073 DOI: 10.1093/plcell/koac095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/14/2022] [Indexed: 05/27/2023]
Abstract
Membrane contact sites (MCSs) are interorganellar connections that allow for the direct exchange of molecules, such as lipids or Ca2+ between organelles, but can also serve to tether organelles at specific locations within cells. Here, we identified and characterized three proteins of Arabidopsis thaliana that form a lipid droplet (LD)-plasma membrane (PM) tethering complex in plant cells, namely LD-localized SEED LD PROTEIN (SLDP) 1 and SLDP2 and PM-localized LD-PLASMA MEMBRANE ADAPTOR (LIPA). Using proteomics and different protein-protein interaction assays, we show that both SLDPs associate with LIPA. Disruption of either SLDP1 and SLDP2 expression, or that of LIPA, leads to an aberrant clustering of LDs in Arabidopsis seedlings. Ectopic co-expression of one of the SLDPs with LIPA is sufficient to reconstitute LD-PM tethering in Nicotiana tabacum pollen tubes, a cell type characterized by dynamically moving LDs in the cytosolic streaming. Furthermore, confocal laser scanning microscopy revealed both SLDP2.1 and LIPA to be enriched at LD-PM contact sites in seedlings. These and other results suggest that SLDP and LIPA interact to form a tethering complex that anchors a subset of LDs to the PM during post-germinative seedling growth in Arabidopsis.
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Affiliation(s)
- Hannah Elisa Krawczyk
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Siqi Sun
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Nathan M Doner
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Qiqi Yan
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Molecular Biology of Plant-Microbe Interactions Research Group, University of Göttingen, Göttingen, Germany
| | - Magdiel Sheng Satha Lim
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Patricia Scholz
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Philipp William Niemeyer
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Kerstin Schmitt
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Oliver Valerius
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Roman Pleskot
- Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic
| | - Stefan Hillmer
- Electron Microscopy Core Facility, Heidelberg University, Heidelberg, Germany
| | - Gerhard H Braus
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Marcel Wiermer
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Molecular Biology of Plant-Microbe Interactions Research Group, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Till Ischebeck
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
- Institute of Plant Biology and Biotechnology (IBBP), Green Biotechnology, University of Münster, Münster, Germany
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10
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Picca A, Guerra F, Calvani R, Romano R, Coelho-Junior HJ, Damiano FP, Bucci C, Marzetti E. Circulating Mitochondrial DNA and Inter-Organelle Contact Sites in Aging and Associated Conditions. Cells 2022; 11:cells11040675. [PMID: 35203322 PMCID: PMC8870554 DOI: 10.3390/cells11040675] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/11/2022] [Accepted: 02/14/2022] [Indexed: 02/07/2023] Open
Abstract
Mitochondria are primarily involved in cell bioenergetics, regulation of redox homeostasis, and cell death/survival signaling. An immunostimulatory property of mitochondria has also been recognized which is deployed through the extracellular release of entire or portioned organelle and/or mitochondrial DNA (mtDNA) unloading. Dynamic homo- and heterotypic interactions involving mitochondria have been described. Each type of connection has functional implications that eventually optimize mitochondrial activity according to the bioenergetic demands of a specific cell/tissue. Inter-organelle communications may also serve as molecular platforms for the extracellular release of mitochondrial components and subsequent ignition of systemic inflammation. Age-related chronic inflammation (inflamm-aging) has been associated with mitochondrial dysfunction and increased extracellular release of mitochondrial components—in particular, cell-free mtDNA. The close relationship between mitochondrial dysfunction and cellular senescence further supports the central role of mitochondria in the aging process and its related conditions. Here, we provide an overview of (1) the mitochondrial genetic system and the potential routes for generating and releasing mtDNA intermediates; (2) the pro-inflammatory pathways elicited by circulating mtDNA; (3) the participation of inter-organelle contacts to mtDNA homeostasis; and (4) the link of these processes with senescence and age-associated conditions.
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Affiliation(s)
- Anna Picca
- Fondazione Policlinico Universitario “Agostino Gemelli” IRCCS, 00168 Rome, Italy; (A.P.); (F.P.D.); (E.M.)
| | - Flora Guerra
- Department of Biological and Environmental Sciences and Technologies, Università del Salento, 73100 Lecce, Italy; (F.G.); (R.R.); (C.B.)
| | - Riccardo Calvani
- Fondazione Policlinico Universitario “Agostino Gemelli” IRCCS, 00168 Rome, Italy; (A.P.); (F.P.D.); (E.M.)
- Correspondence: ; Tel.: +39-06-3015-5559; Fax: +39-06-3051-911
| | - Roberta Romano
- Department of Biological and Environmental Sciences and Technologies, Università del Salento, 73100 Lecce, Italy; (F.G.); (R.R.); (C.B.)
| | - Hélio José Coelho-Junior
- Department of Geriatrics and Orthopedics, Università Cattolica del Sacro Cuore, 00168 Rome, Italy;
| | - Francesco P. Damiano
- Fondazione Policlinico Universitario “Agostino Gemelli” IRCCS, 00168 Rome, Italy; (A.P.); (F.P.D.); (E.M.)
| | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies, Università del Salento, 73100 Lecce, Italy; (F.G.); (R.R.); (C.B.)
| | - Emanuele Marzetti
- Fondazione Policlinico Universitario “Agostino Gemelli” IRCCS, 00168 Rome, Italy; (A.P.); (F.P.D.); (E.M.)
- Department of Geriatrics and Orthopedics, Università Cattolica del Sacro Cuore, 00168 Rome, Italy;
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11
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Schürmanns L, Hamann A, Osiewacz HD. Lifespan Increase of Podospora anserina by Oleic Acid Is Linked to Alterations in Energy Metabolism, Membrane Trafficking and Autophagy. Cells 2022; 11:cells11030519. [PMID: 35159328 PMCID: PMC8834509 DOI: 10.3390/cells11030519] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 01/27/2022] [Accepted: 01/29/2022] [Indexed: 12/02/2022] Open
Abstract
The maintenance of cellular homeostasis over time is essential to avoid the degeneration of biological systems leading to aging and disease. Several interconnected pathways are active in this kind of quality control. One of them is autophagy, the vacuolar degradation of cellular components. The absence of the sorting nexin PaATG24 (SNX4 in other organisms) has been demonstrated to result in impairments in different types of autophagy and lead to a shortened lifespan. In addition, the growth rate and the size of vacuoles are strongly reduced. Here, we report how an oleic acid diet leads to longevity of the wild type and a PaAtg24 deletion mutant (ΔPaAtg24). The lifespan extension is linked to altered membrane trafficking, which abrogates the observed autophagy defects in ΔPaAtg24 by restoring vacuole size and the proper localization of SNARE protein PaSNC1. In addition, an oleic acid diet leads to an altered use of the mitochondrial respiratory chain: complex I and II are bypassed, leading to reduced reactive oxygen species (ROS) production. Overall, our study uncovers multiple effects of an oleic acid diet, which extends the lifespan of P. anserina and provides perspectives to explain the positive nutritional effects on human aging.
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12
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Kovacs M, Geltinger F, Verwanger T, Weiss R, Richter K, Rinnerthaler M. Lipid Droplets Protect Aging Mitochondria and Thus Promote Lifespan in Yeast Cells. Front Cell Dev Biol 2021; 9:774985. [PMID: 34869375 PMCID: PMC8640092 DOI: 10.3389/fcell.2021.774985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/26/2021] [Indexed: 12/20/2022] Open
Abstract
Besides their role as a storage for neutral lipids and sterols, there is increasing evidence that lipid droplets (LDs) are involved in cellular detoxification. LDs are in close contact to a broad variety of organelles where protein- and lipid exchange is mediated. Mitochondria as a main driver of the aging process produce reactive oxygen species (ROS), which damage several cellular components. LDs as highly dynamic organelles mediate a potent detoxification mechanism by taking up toxic lipids and proteins. A stimulation of LDs induced by the simultaneously overexpression of Lro1p and Dga1p (both encoding acyltransferases) prolongs the chronological as well as the replicative lifespan of yeast cells. The increased number of LDs reduces mitochondrial fragmentation as well as mitochondrial ROS production, both phenotypes that are signs of aging. Strains with an altered LD content or morphology as in the sei1∆ or lro1∆ mutant lead to a reduced replicative lifespan. In a yeast strain defective for the LON protease Pim1p, which showed an enhanced ROS production, increased doubling time and an altered mitochondrial morphology, a LRO1 overexpression resulted in a partially reversion of this "premature aging" phenotype.
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Affiliation(s)
| | | | | | | | | | - Mark Rinnerthaler
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
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13
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Eigenfeld M, Kerpes R, Becker T. Understanding the Impact of Industrial Stress Conditions on Replicative Aging in Saccharomyces cerevisiae. FRONTIERS IN FUNGAL BIOLOGY 2021; 2:665490. [PMID: 37744109 PMCID: PMC10512339 DOI: 10.3389/ffunb.2021.665490] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 03/30/2021] [Indexed: 09/26/2023]
Abstract
In yeast, aging is widely understood as the decline of physiological function and the decreasing ability to adapt to environmental changes. Saccharomyces cerevisiae has become an important model organism for the investigation of these processes. Yeast is used in industrial processes (beer and wine production), and several stress conditions can influence its intracellular aging processes. The aim of this review is to summarize the current knowledge on applied stress conditions, such as osmotic pressure, primary metabolites (e.g., ethanol), low pH, oxidative stress, heat on aging indicators, age-related physiological changes, and yeast longevity. There is clear evidence that yeast cells are exposed to many stressors influencing viability and vitality, leading to an age-related shift in age distribution. Currently, there is a lack of rapid, non-invasive methods allowing the investigation of aspects of yeast aging in real time on a single-cell basis using the high-throughput approach. Methods such as micromanipulation, centrifugal elutriator, or biotinylation do not provide real-time information on age distributions in industrial processes. In contrast, innovative approaches, such as non-invasive fluorescence coupled flow cytometry intended for high-throughput measurements, could be promising for determining the replicative age of yeast cells in fermentation and its impact on industrial stress conditions.
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Affiliation(s)
| | - Roland Kerpes
- Research Group Beverage and Cereal Biotechnology, Institute of Brewing and Beverage Technology, Technical University of Munich, Freising, Germany
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14
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Felder T, Geltinger F, Rinnerthaler M. Lipid droplets meet aging. Aging (Albany NY) 2021; 13:7709-7710. [PMID: 33755592 PMCID: PMC8034894 DOI: 10.18632/aging.202883] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 03/06/2021] [Indexed: 12/30/2022]
Affiliation(s)
- Thomas Felder
- Department of Biosciences, Division of Genetics, University of Salzburg, Salzburg, 5020, Austria
| | - Florian Geltinger
- Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, 5020, Austria
| | - Mark Rinnerthaler
- Department of Biosciences, Division of Genetics, University of Salzburg, Salzburg, 5020, Austria
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15
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Chee WY, Kurahashi Y, Kim J, Miura K, Okuzaki D, Ishitani T, Kajiwara K, Nada S, Okano H, Okada M. β-catenin-promoted cholesterol metabolism protects against cellular senescence in naked mole-rat cells. Commun Biol 2021; 4:357. [PMID: 33742113 PMCID: PMC7979689 DOI: 10.1038/s42003-021-01879-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 02/19/2021] [Indexed: 02/01/2023] Open
Abstract
The naked mole-rat (NMR; Heterocephalus glaber) exhibits cancer resistance and an exceptionally long lifespan of approximately 30 years, but the mechanism(s) underlying increased longevity in NMRs remains unclear. In the present study, we report unique mechanisms underlying cholesterol metabolism in NMR cells, which may be responsible for their anti-senescent properties. NMR fibroblasts expressed β-catenin abundantly; this high expression was linked to increased accumulation of cholesterol-enriched lipid droplets. Ablation of β-catenin or inhibition of cholesterol synthesis abolished lipid droplet formation and induced senescence-like phenotypes accompanied by increased oxidative stress. β-catenin ablation downregulated apolipoprotein F and the LXR/RXR pathway, which are involved in cholesterol transport and biogenesis. Apolipoprotein F ablation also suppressed lipid droplet accumulation and promoted cellular senescence, indicating that apolipoprotein F mediates β-catenin signaling in NMR cells. Thus, we suggest that β-catenin in NMRs functions to offset senescence by regulating cholesterol metabolism, which may contribute to increased longevity in NMRs.
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Affiliation(s)
- Woei-Yaw Chee
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Yuriko Kurahashi
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Junhyeong Kim
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Kyoko Miura
- grid.274841.c0000 0001 0660 6749Department of Aging and Longevity Research, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Daisuke Okuzaki
- grid.136593.b0000 0004 0373 3971Genome Information Research Center, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan ,grid.136593.b0000 0004 0373 3971Human Immunology Lab, WPI Immunology Frontier Research Center, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Osaka, Japan
| | - Tohru Ishitani
- grid.136593.b0000 0004 0373 3971Department of Homeostatic Regulation, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Kentaro Kajiwara
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Shigeyuki Nada
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Hideyuki Okano
- grid.26091.3c0000 0004 1936 9959Department of Physiology, Keio University School of Medicine, Shinjuku-ku, Tokyo Japan
| | - Masato Okada
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
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16
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Loving BA, Tang M, Neal MC, Gorkhali S, Murphy R, Eckel RH, Bruce KD. Lipoprotein Lipase Regulates Microglial Lipid Droplet Accumulation. Cells 2021; 10:cells10020198. [PMID: 33498265 PMCID: PMC7909280 DOI: 10.3390/cells10020198] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/12/2021] [Accepted: 01/15/2021] [Indexed: 12/18/2022] Open
Abstract
Microglia become increasingly dysfunctional with aging and contribute to the onset of neurodegenerative disease (NDs) through defective phagocytosis, attenuated cholesterol efflux, and excessive secretion of pro-inflammatory cytokines. Dysfunctional microglia also accumulate lipid droplets (LDs); however, the mechanism underlying increased LD load is unknown. We have previously shown that microglia lacking lipoprotein lipase (LPL KD) are polarized to a pro-inflammatory state and have impaired lipid uptake and reduced fatty acid oxidation (FAO). Here, we also show that LPL KD microglia show excessive accumulation of LD-like structures. Moreover, LPL KD microglia display a pro-inflammatory lipidomic profile, increased cholesterol ester (CE) content, and reduced cholesterol efflux at baseline. We also show reduced expression of genes within the canonical cholesterol efflux pathway. Importantly, PPAR agonists (rosiglitazone and bezafibrate) rescued the LD-associated phenotype in LPL KD microglia. These data suggest that microglial-LPL is associated with lipid uptake, which may drive PPAR signaling and cholesterol efflux to prevent inflammatory lipid distribution and LD accumulation. Moreover, PPAR agonists can reverse LD accumulation, and therefore may be beneficial in aging and in the treatment of NDs.
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Affiliation(s)
- Bailey A. Loving
- Department of Radiation Oncology, Oakland University William Beaumont School of Medicine, Royal Oak, MI 48309, USA;
| | - Maoping Tang
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA; (M.T.); (M.C.N.); (S.G.); (R.H.E.)
| | - Mikaela C. Neal
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA; (M.T.); (M.C.N.); (S.G.); (R.H.E.)
| | - Sachi Gorkhali
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA; (M.T.); (M.C.N.); (S.G.); (R.H.E.)
| | - Robert Murphy
- Department of Pharmacology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - Robert H. Eckel
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA; (M.T.); (M.C.N.); (S.G.); (R.H.E.)
| | - Kimberley D. Bruce
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA; (M.T.); (M.C.N.); (S.G.); (R.H.E.)
- Correspondence:
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17
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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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