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Zhang P, Verity MA, Reue K. Lipin-1 regulates autophagy clearance and intersects with statin drug effects in skeletal muscle. Cell Metab 2014; 20:267-79. [PMID: 24930972 PMCID: PMC4170588 DOI: 10.1016/j.cmet.2014.05.003] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/03/2014] [Accepted: 04/21/2014] [Indexed: 02/04/2023]
Abstract
LPIN1 encodes lipin-1, a phosphatidic acid phosphatase (PAP) enzyme that catalyzes the dephosphorylation of phosphatidic acid to form diacylglycerol. Homozygous LPIN1 gene mutations cause severe rhabdomyolysis, and heterozygous LPIN1 missense mutations may promote statin-induced myopathy. We demonstrate that lipin-1-related myopathy in the mouse is associated with a blockade in autophagic flux and accumulation of aberrant mitochondria. Lipin-1 PAP activity is required for maturation of autolysosomes, through its activation of the protein kinase D (PKD)-Vps34 phosphatidylinositol 3-kinase signaling cascade. Statin treatment also reduces PKD activation and autophagic flux, which are compounded by diminished mammalian target of rapamycin (mTOR) abundance in lipin-1-haploinsufficent and -deficient muscle. Lipin-1 restoration in skeletal muscle prevents myonecrosis and statin toxicity in vivo, and activated PKD rescues autophagic flux in lipin-1-deficient cells. Our findings identify lipin-1 PAP activity as a component of the macroautophagy pathway and define the basis for lipin-1-related myopathies.
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Affiliation(s)
- Peixiang Zhang
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - M Anthony Verity
- Division of Neuropathology, Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Karen Reue
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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52
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Region specific mitochondrial impairment in mice with widespread overexpression of alpha-synuclein. Neurobiol Dis 2014; 70:204-13. [PMID: 25016198 DOI: 10.1016/j.nbd.2014.06.017] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 06/17/2014] [Accepted: 06/22/2014] [Indexed: 11/21/2022] Open
Abstract
Parkinson's disease (PD) is characterized by the progressive degeneration of nigrostriatal dopaminergic neurons leading to motor deficits. The mechanisms underlying the preferential vulnerability of nigrostriatal dopaminergic neurons in PD remain poorly understood. Recent evidence supports a role for mitochondrial dysfunction and increased oxidative stress in PD pathogenesis. Genetic and pathological studies also point to alpha-synuclein as a critical factor in both familial and sporadic forms of the disease; alpha-synuclein pathology affects mitochondrial function but is widespread in PD brain, raising the question of its role in the greater vulnerability of nigrostriatal neurons in PD. We have examined mitochondrial function and oxidative damage in mice overexpressing human wild type alpha-synuclein broadly throughout the nervous system under the Thy1 promoter (Thy1-aSyn mice) between 4 and 8months of age. Similar levels of alpha-synuclein accumulation in mitochondria were detected in the ventral midbrain, striatum and cortex of Thy1-aSyn mice. However, analysis of mitochondrial respiration using Seahorse XF analyzer showed defects in mitochondrial respiratory complexes I, II, IV and V specifically in the midbrain, and IV and V in the striatum, of Thy1-aSyn mice compared to wild type littermates; mitochondrial complex I activity assay by ELISA confirmed a 40% inhibition specifically in the ventral midbrain. Mitochondrial dysfunction can contribute to oxidative stress and we observed a 40% increase in 4-hydroxynenal and 2-fold increase in malondialdehyde levels, indicative of a high level of lipid peroxidation, specifically in the ventral midbrain of Thy1-aSyn mice. The levels of peroxiredoxin 2, a neuronal antioxidant enzyme that is involved in removal of H2O2 and other toxic peroxides were decreased in the midbrain whereas its oxidized form increased 4-fold, suggesting that antioxidant defenses were compromised in this region. In contrast, peroxiredoxin 2 increased in the striatum and cortex, which may contribute to their protection in the presence of high levels of alpha-synuclein. Thus, in mice over-expressing alpha-synuclein, mitochondrial dysfunction occurred preferentially in nigrostriatal dopaminergic neurons many months before striatal dopamine loss occurs at 14months of age. This may contribute to a higher level of oxidative stress that overwhelms antioxidant defense in these neurons, leading to their increased vulnerability in PD.
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Abstract
Long-chain fatty acyl-coenzyme As (CoAs) are critical regulatory molecules and metabolic intermediates. The initial step in their synthesis is the activation of fatty acids by one of 13 long-chain acyl-CoA synthetase isoforms. These isoforms are regulated independently and have different tissue expression patterns and subcellular locations. Their acyl-CoA products regulate metabolic enzymes and signaling pathways, become oxidized to provide cellular energy, and are incorporated into acylated proteins and complex lipids such as triacylglycerol, phospholipids, and cholesterol esters. Their differing metabolic fates are determined by a network of proteins that channel the acyl-CoAs toward or away from specific metabolic pathways and serve as the basis for partitioning. This review evaluates the evidence for acyl-CoA partitioning by reviewing experimental data on proteins that are believed to contribute to acyl-CoA channeling, the metabolic consequences of loss of these proteins, and the potential role of maladaptive acyl-CoA partitioning in the pathogenesis of metabolic disease and carcinogenesis.
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Syamsunarno MRAA, Iso T, Yamaguchi A, Hanaoka H, Putri M, Obokata M, Sunaga H, Koitabashi N, Matsui H, Maeda K, Endo K, Tsushima Y, Yokoyama T, Kurabayashi M. Fatty acid binding protein 4 and 5 play a crucial role in thermogenesis under the conditions of fasting and cold stress. PLoS One 2014; 9:e90825. [PMID: 24603714 PMCID: PMC3946242 DOI: 10.1371/journal.pone.0090825] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 02/04/2014] [Indexed: 12/30/2022] Open
Abstract
Hypothermia is rapidly induced during cold exposure when thermoregulatory mechanisms, including fatty acid (FA) utilization, are disturbed. FA binding protein 4 (FABP4) and FABP5, which are abundantly expressed in adipose tissues and macrophages, have been identified as key molecules in the pathogenesis of overnutrition-related diseases, such as insulin resistance and atherosclerosis. We have recently shown that FABP4/5 are prominently expressed in capillary endothelial cells in the heart and skeletal muscle and play a crucial role in FA utilization in these tissues. However, the role of FABP4/5 in thermogenesis remains to be determined. In this study, we showed that thermogenesis is severely impaired in mice lacking both FABP4 and FABP5 (DKO mice), as manifested shortly after cold exposure during fasting. In DKO mice, the storage of both triacylglycerol in brown adipose tissue (BAT) and glycogen in skeletal muscle (SkM) was nearly depleted after fasting, and a biodistribution analysis using 125I-BMIPP revealed that non-esterified FAs (NEFAs) are not efficiently taken up by BAT despite the robustly elevated levels of serum NEFAs. In addition to the severe hypoglycemia observed in DKO mice during fasting, cold exposure did not induce the uptake of glucose analogue 18F-FDG by BAT. These findings strongly suggest that DKO mice exhibit pronounced hypothermia after fasting due to the depletion of energy storage in BAT and SkM and the reduced supply of energy substrates to these tissues. In conclusion, FABP4/5 play an indispensable role in thermogenesis in BAT and SkM. Our study underscores the importance of FABP4/5 for overcoming life-threatening environments, such as cold and starvation.
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Affiliation(s)
| | - Tatsuya Iso
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Gunma, Japan
- Education and Research Support Center, Gunma University Graduate School of Medicine, Gunma, Japan
- * E-mail:
| | - Aiko Yamaguchi
- Department of Bioimaging Information Analysis, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Hirofumi Hanaoka
- Department of Molecular Imaging and Radiotherapy, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
| | - Mirasari Putri
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Gunma, Japan
- Department of Public Health, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Masaru Obokata
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Hiroaki Sunaga
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Gunma, Japan
| | - Norimichi Koitabashi
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Hiroki Matsui
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Gunma, Japan
| | - Kazuhisa Maeda
- Department of Complementary and Alternative Medicine, Graduate School of Medicine, Osaka University Hospital, Osaka, Japan
| | - Keigo Endo
- Department of Bioimaging Information Analysis, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Yoshito Tsushima
- Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Tomoyuki Yokoyama
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Gunma, Japan
| | - Masahiko Kurabayashi
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Gunma, Japan
- Education and Research Support Center, Gunma University Graduate School of Medicine, Gunma, Japan
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55
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Hindle AG, Martin SL. Intrinsic circannual regulation of brown adipose tissue form and function in tune with hibernation. Am J Physiol Endocrinol Metab 2014; 306:E284-99. [PMID: 24326419 PMCID: PMC3920013 DOI: 10.1152/ajpendo.00431.2013] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Winter hibernators repeatedly cycle between cold torpor and rewarming supported by nonshivering thermogenesis in brown adipose tissue (BAT). In contrast, summer animals are homeotherms, undergoing reproduction, growth, and fattening. This life history confers variability to BAT recruitment and activity. To address the components underlying prewinter enhancement and winter activation, we interrogated the BAT proteome in 13-lined ground squirrels among three summer and five winter states. We also examined mixed physiology in fall and spring individuals to test for ambient temperature and seasonal effects, as well as the timing of seasonal transitions. BAT form and function differ circannually in these animals, as evidenced by morphology and proteome dynamics. This intrinsic pattern distinguished homeothermic groups and early vs. late winter hibernators. Homeothermic variation derived from postemergence delay in growth and substrate biosynthesis. The heterothermic proteome varied less despite extreme winter physiological shifts and was optimized to exploit lipids by enhanced fatty acid binding, β-oxidation, and mitochondrial protein translocation. Surprisingly, ambient temperature did not affect the BAT proteome during transition seasons; rather, the pronounced summer-winter shift preceded environmental changes and phenotypic progression. During fall transition, differential regulation of two fatty acid binding proteins provides further evidence of recruitment and separates proteomic preparation from successful hibernation. Abundance of FABP4 correlates with torpor bout length throughout the year, clarifying its potential function in hibernation. Metabolically active BAT is a target for treating human obesity and metabolic disorders. Understanding the hibernator's extreme and seasonally distinct recruitment and activation control strategies offers untapped potential to identify novel, therapeutically relevant regulatory pathways.
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Affiliation(s)
- Allyson G Hindle
- Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado
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56
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Pessentheiner AR, Pelzmann HJ, Walenta E, Schweiger M, Groschner LN, Graier WF, Kolb D, Uno K, Miyazaki T, Nitta A, Rieder D, Prokesch A, Bogner-Strauss JG. NAT8L (N-acetyltransferase 8-like) accelerates lipid turnover and increases energy expenditure in brown adipocytes. J Biol Chem 2013; 288:36040-51. [PMID: 24155240 PMCID: PMC3861652 DOI: 10.1074/jbc.m113.491324] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
NAT8L (N-acetyltransferase 8-like) catalyzes the formation of N-acetylaspartate (NAA) from acetyl-CoA and aspartate. In the brain, NAA delivers the acetate moiety for synthesis of acetyl-CoA that is further used for fatty acid generation. However, its function in other tissues remained elusive. Here, we show for the first time that Nat8l is highly expressed in adipose tissues and murine and human adipogenic cell lines and is localized in the mitochondria of brown adipocytes. Stable overexpression of Nat8l in immortalized brown adipogenic cells strongly increases glucose incorporation into neutral lipids, accompanied by increased lipolysis, indicating an accelerated lipid turnover. Additionally, mitochondrial mass and number as well as oxygen consumption are elevated upon Nat8l overexpression. Concordantly, expression levels of brown marker genes, such as Prdm16, Cidea, Pgc1α, Pparα, and particularly UCP1, are markedly elevated in these cells. Treatment with a PPARα antagonist indicates that the increase in UCP1 expression and oxygen consumption is PPARα-dependent. Nat8l knockdown in brown adipocytes has no impact on cellular triglyceride content, lipogenesis, or oxygen consumption, but lipolysis and brown marker gene expression are increased; the latter is also observed in BAT of Nat8l-KO mice. Interestingly, the expression of ATP-citrate lyase is increased in Nat8l-silenced adipocytes and BAT of Nat8l-KO mice, indicating a compensatory mechanism to sustain the acetyl-CoA pool once Nat8l levels are reduced. Taken together, our data show that Nat8l impacts on the brown adipogenic phenotype and suggests the existence of the NAT8L-driven NAA metabolism as a novel pathway to provide cytosolic acetyl-CoA for lipid synthesis in adipocytes.
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Affiliation(s)
- Ariane R. Pessentheiner
- From the Institute for Genomics and Bioinformatics, Graz University of Technology, Petergasse 14, 8010 Graz, Austria, ,the Institute of Biochemistry, Graz University of Technology, Petergasse 12, 8010 Graz, Austria
| | - Helmut J. Pelzmann
- From the Institute for Genomics and Bioinformatics, Graz University of Technology, Petergasse 14, 8010 Graz, Austria, ,the Institute of Biochemistry, Graz University of Technology, Petergasse 12, 8010 Graz, Austria
| | - Evelyn Walenta
- From the Institute for Genomics and Bioinformatics, Graz University of Technology, Petergasse 14, 8010 Graz, Austria
| | - Martina Schweiger
- the Institute for Molecular Biosciences, University of Graz, Heinrichstrasse 31, 8010 Graz, Austria
| | | | | | - Dagmar Kolb
- Institute of Cell Biology, Histology, and Embryology, Medical University of Graz, Harrachgasse 21, 8010 Graz, Austria, ,the Core Facility Ultrastructure Analysis, Center for Medical Research, Medical University of Graz, Stiftingtalstrasse 24, 8010 Graz, Austria
| | - Kyosuke Uno
- the Department of Pharmaceutical Therapy and Neuropharmacology, Faculty of Pharmaceutical Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan, and
| | - Toh Miyazaki
- the Department of Pharmaceutical Therapy and Neuropharmacology, Faculty of Pharmaceutical Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan, and
| | - Atsumi Nitta
- the Department of Pharmaceutical Therapy and Neuropharmacology, Faculty of Pharmaceutical Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan, and
| | - Dietmar Rieder
- the Division of Bioinformatics, Biocenter, Innsbruck Medical University, Innrain 80, 6020 Innsbruck, Austria
| | - Andreas Prokesch
- From the Institute for Genomics and Bioinformatics, Graz University of Technology, Petergasse 14, 8010 Graz, Austria, ,the Institute of Biochemistry, Graz University of Technology, Petergasse 12, 8010 Graz, Austria
| | - Juliane G. Bogner-Strauss
- From the Institute for Genomics and Bioinformatics, Graz University of Technology, Petergasse 14, 8010 Graz, Austria, ,the Institute of Biochemistry, Graz University of Technology, Petergasse 12, 8010 Graz, Austria, , To whom correspondence should be addressed: Petersgasse 14/5, 8010 Graz, Austria. Tel.: 43-316-873-5337; E-mail:
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57
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Xiong D, He H, James J, Tokunaga C, Powers C, Huang Y, Osinska H, Towbin JA, Purevjav E, Balschi JA, Javadov S, McGowan FX, Strauss AW, Khuchua Z. Cardiac-specific VLCAD deficiency induces dilated cardiomyopathy and cold intolerance. Am J Physiol Heart Circ Physiol 2013; 306:H326-38. [PMID: 24285112 DOI: 10.1152/ajpheart.00931.2012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The very long-chain acyl-CoA dehydrogenase (VLCAD) enzyme catalyzes the first step of mitochondrial β-oxidation. Patients with VLCAD deficiency present with hypoketotic hypoglycemia and cardiomyopathy, which can be exacerbated by fasting and/or cold stress. Global VLCAD knockout mice recapitulate these phenotypes: mice develop cardiomyopathy, and cold exposure leads to rapid hypothermia and death. However, the contribution of different tissues to development of these phenotypes has not been studied. We generated cardiac-specific VLCAD-deficient (cVLCAD(-/-)) mice by Cre-mediated ablation of the VLCAD in cardiomyocytes. By 6 mo of age, cVLCAD(-/-) mice demonstrated increased end-diastolic and end-systolic left ventricular dimensions and decreased fractional shortening. Surprisingly, selective VLCAD gene ablation in cardiomyocytes was sufficient to evoke severe cold intolerance in mice who rapidly developed severe hypothermia, bradycardia, and markedly depressed cardiac function in response to fasting and cold exposure (+5°C). We conclude that cardiac-specific VLCAD deficiency is sufficient to induce cold intolerance and cardiomyopathy and is associated with reduced ATP production. These results provide strong evidence that fatty acid oxidation in myocardium is essential for maintaining normal cardiac function under these stress conditions.
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Affiliation(s)
- Dingding Xiong
- Heart Institute of Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
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Nakamura Y, Sato T, Shiimura Y, Miura Y, Kojima M. FABP3 and brown adipocyte-characteristic mitochondrial fatty acid oxidation enzymes are induced in beige cells in a different pathway from UCP1. Biochem Biophys Res Commun 2013; 441:42-6. [PMID: 24129192 DOI: 10.1016/j.bbrc.2013.10.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 10/04/2013] [Indexed: 11/19/2022]
Abstract
Cold exposure and β3-adrenergic receptor agonist (CL316,243) treatment induce the production of beige cells, which express brown adipocytes(BA)-specific UCP1 protein, in white adipose tissue (WAT). It remains unclear whether the beige cells, which have different gene expression patterns from BA, express BA-characteristic fatty acid oxidation (FAO) proteins. Here we found that 5 day cold exposure and CL316,243 treatment of WAT, but not CL316,243 treatment of primary adipocytes of C57BL/6J mice, increased mRNA levels of BA-characteristic FAO proteins. These results suggest that BA-characteristic FAO proteins are induced in beige cells in a different pathway from UCP1.
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Affiliation(s)
- Yuki Nakamura
- Department of Molecular Genetics, Institute of Life Science, Kurume University, 1-1 Hyakunen-kouen, Kurume 839-0864, Japan
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Rebl A, Verleih M, Köbis JM, Kühn C, Wimmers K, Köllner B, Goldammer T. Transcriptome profiling of gill tissue in regionally bred and globally farmed rainbow trout strains reveals different strategies for coping with thermal stress. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2013; 15:445-460. [PMID: 23547003 DOI: 10.1007/s10126-013-9501-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 01/22/2013] [Indexed: 06/02/2023]
Abstract
Thermal stress can pose a major challenge to salmonid fish. A 4x44K oligonucleotide microarray approach was used to screen for genetically determined variations of a temperature stress response during acclimation in fish gills, a highly specialized and complex organ responsible for gas and electrolyte exchange as well as excretion. The comparison addressed transcriptional changes in the local breeding strain BORN and imported (TCO) rainbow trout after graded 2-week acclimation to 8 and 23 °C. Besides well-characterized mediators of thermoregulation such as genes encoding cold-inducible RNA-binding protein and heat shock proteins, the present microarray study suggests several new candidate genes commonly regulated in gills of the two trout lines. Having identified the differential expression of thermoregulated genes as duplicated paralogues, they were subsequently validated in a gill cell model. Moreover, the comparison of transcriptome profiles provides evidence for distinctively employed expression patterns. The induction of genes encoding factors of the early innate immunity in BORN trout upon warming contrasts with the increased expression of adaptive immune genes in import trout. Cold acclimation induced genes assigned to the functional categories "cell death" and "ion channel activity" in import trout, but repressed "lipid metabolism." This manuscript provides an overview of the genes of the multifunctional gills in rainbow trout that are mandated after temperature change, suggesting links between the different temperature-dependent pathways and gene networks.
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Affiliation(s)
- Alexander Rebl
- Institut für Genombiologie, Leibniz-Institut für Nutztierbiologie-FBN, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
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60
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Responses of brown adipose tissue to diet-induced obesity, exercise, dietary restriction and ephedrine treatment. ACTA ACUST UNITED AC 2013; 65:549-57. [DOI: 10.1016/j.etp.2012.04.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 04/03/2012] [Indexed: 11/18/2022]
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61
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Chappuis S, Ripperger JA, Schnell A, Rando G, Jud C, Wahli W, Albrecht U. Role of the circadian clock gene Per2 in adaptation to cold temperature. Mol Metab 2013; 2:184-93. [PMID: 24049733 DOI: 10.1016/j.molmet.2013.05.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 05/02/2013] [Accepted: 05/03/2013] [Indexed: 01/12/2023] Open
Abstract
Adaptive thermogenesis allows mammals to resist to cold. For instance, in brown adipose tissue (BAT) the facultative uncoupling of the proton gradient from ATP synthesis in mitochondria is used to generate systemic heat. However, this system necessitates an increase of the Uncoupling protein 1 (Ucp1) and its activation by free fatty acids. Here we show that mice without functional Period2 (Per2) were cold sensitive because their adaptive thermogenesis system was less efficient. Upon cold-exposure, Heat shock factor 1 (HSF1) induced Per2 in the BAT. Subsequently, PER2 as a co-activator of PPARα increased expression of Ucp1. PER2 also increased Fatty acid binding protein 3 (Fabp3), a protein important to transport free fatty acids from the plasma to mitochondria to activate UCP1. Hence, in BAT PER2 is important for the coordination of the molecular response of mice exposed to cold by synchronizing UCP1 expression and its activation.
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Key Words
- Adrβ3, beta-adrenergic receptor 3
- BAT, brown adipose tissue
- BMAL1, brain and muscle ARNT-like factor
- Brown adipose tissue
- CLOCK, circadian locomotor output cycles kaput
- ChIP, chromatin immunoprecipitation
- FABP3, fatty acid binding protein 3
- FFA, free fatty acids
- HSE, heat shock element
- HSF1, heat shock factor 1
- Humidity
- NPAS2, neuronal PAS-domain containing protein 2
- PGC-1, PPAR-coactivator -1
- PPAR, peroxisome proliferator-activated receptor
- PPRE, PPAR element
- Per2, Period2
- RXR, retinoid X receptor
- SCN, suprachiasmatic nuclei
- Season
- TAG, triglycerides
- UCP1, uncoupling protein 1
- WAT, white adipose tissue
- WT, wild-type
- ZT, zeitgeber time
- luc, luciferase
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Affiliation(s)
- Sylvie Chappuis
- Department of Biology, Unit of Biochemistry, University of Fribourg, Switzerland
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α-Lipoic acid ameliorates mitochondrial impairment and reverses apoptosis in FABP3-overexpressing embryonic cancer cells. J Bioenerg Biomembr 2013; 45:459-66. [DOI: 10.1007/s10863-013-9506-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 03/11/2013] [Indexed: 12/31/2022]
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63
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Williams KJ, Argus JP, Zhu Y, Wilks MQ, Marbois BN, York AG, Kidani Y, Pourzia AL, Akhavan D, Lisiero DN, Komisopoulou E, Henkin AH, Soto H, Chamberlain BT, Vergnes L, Jung ME, Torres JZ, Liau LM, Christofk HR, Prins RM, Mischel PS, Reue K, Graeber TG, Bensinger SJ. An essential requirement for the SCAP/SREBP signaling axis to protect cancer cells from lipotoxicity. Cancer Res 2013; 73:2850-62. [PMID: 23440422 DOI: 10.1158/0008-5472.can-13-0382-t] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The sterol regulatory element-binding proteins (SREBP) are key transcriptional regulators of lipid metabolism and cellular growth. It has been proposed that SREBP signaling regulates cellular growth through its ability to drive lipid biosynthesis. Unexpectedly, we find that loss of SREBP activity inhibits cancer cell growth and viability by uncoupling fatty acid synthesis from desaturation. Integrated lipid profiling and metabolic flux analysis revealed that cancer cells with attenuated SREBP activity maintain long-chain saturated fatty acid synthesis, while losing fatty acid desaturation capacity. We traced this defect to the uncoupling of fatty acid synthase activity from stearoyl-CoA desaturase 1 (SCD1)-mediated desaturation. This deficiency in desaturation drives an imbalance between the saturated and monounsaturated fatty acid pools resulting in severe lipotoxicity. Importantly, replenishing the monounsaturated fatty acid pool restored growth to SREBP-inhibited cells. These studies highlight the importance of fatty acid desaturation in cancer growth and provide a novel mechanistic explanation for the role of SREBPs in cancer metabolism.
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Affiliation(s)
- Kevin J Williams
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles 90095, USA
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64
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Gender-dependent gene expressions in brown adipose tissue of lean and obese rats fed a high fat diet. BIOTECHNOL BIOPROC E 2012. [DOI: 10.1007/s12257-012-0332-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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65
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Abstract
Objective: A better understanding of the processes influencing energy expenditure could provide new therapeutic strategies for reducing obesity. As the metabolic activity of the brown adipose tissue (BAT) and skeletal muscle is an important determinant of overall energy expenditure and adiposity, we investigated the role of genes that could influence cellular bioenergetics in these two tissues. Design: We screened for genes that are induced in both the BAT and skeletal muscle during acute adaptive thermogenesis in the mouse by microarray. We used C57BL/6J mice as well as the primary and immortalized brown adipocytes and C2C12 myocytes to validate the microarray data. Further characterization included gene expression, mitochondrial density, cellular respiration and substrate utilization. We also used a Hybrid Mouse Diversity Panel to assess in vivo effects on obesity and body fat content. Results: We identified the transcription factor Zbtb16 (also known as Plzf and Zfp14) as being induced in both the BAT and skeletal muscle during acute adaptive thermogenesis. Zbtb16 overexpression in brown adipocytes led to the induction of components of the thermogenic program, including genes involved in fatty acid oxidation, glycolysis and mitochondrial function. Enhanced Zbtb16 expression also increased mitochondrial number, as well as the respiratory capacity and uncoupling. These effects were accompanied by decreased triglyceride content and increased carbohydrate utilization in brown adipocytes. Natural variation in Zbtb16 mRNA levels in multiple tissues across a panel of >100 mouse strains was inversely correlated with body weight and body fat content. Conclusion: Our results implicate Zbtb16 as a novel determinant of substrate utilization in brown adipocytes and of adiposity in vivo.
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Control of mitochondrial metabolism and systemic energy homeostasis by microRNAs 378 and 378*. Proc Natl Acad Sci U S A 2012; 109:15330-5. [PMID: 22949648 DOI: 10.1073/pnas.1207605109] [Citation(s) in RCA: 233] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Obesity and metabolic syndrome are associated with mitochondrial dysfunction and deranged regulation of metabolic genes. Peroxisome proliferator-activated receptor γ coactivator 1β (PGC-1β) is a transcriptional coactivator that regulates metabolism and mitochondrial biogenesis through stimulation of nuclear hormone receptors and other transcription factors. We report that the PGC-1β gene encodes two microRNAs (miRNAs), miR-378 and miR-378*, which counterbalance the metabolic actions of PGC-1β. Mice genetically lacking miR-378 and miR-378* are resistant to high-fat diet-induced obesity and exhibit enhanced mitochondrial fatty acid metabolism and elevated oxidative capacity of insulin-target tissues. Among the many targets of these miRNAs, carnitine O-acetyltransferase, a mitochondrial enzyme involved in fatty acid metabolism, and MED13, a component of the Mediator complex that controls nuclear hormone receptor activity, are repressed by miR-378 and miR-378*, respectively, and are elevated in the livers of miR-378/378* KO mice. Consistent with these targets as contributors to the metabolic actions of miR-378 and miR-378*, previous studies have implicated carnitine O-acetyltransferase and MED13 in metabolic syndrome and obesity. Our findings identify miR-378 and miR-378* as integral components of a regulatory circuit that functions under conditions of metabolic stress to control systemic energy homeostasis and the overall oxidative capacity of insulin target tissues. Thus, these miRNAs provide potential targets for pharmacologic intervention in obesity and metabolic syndrome.
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Mouse lipin-1 and lipin-2 cooperate to maintain glycerolipid homeostasis in liver and aging cerebellum. Proc Natl Acad Sci U S A 2012; 109:E2486-95. [PMID: 22908270 DOI: 10.1073/pnas.1205221109] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The three lipin phosphatidate phosphatase (PAP) enzymes catalyze a step in glycerolipid biosynthesis, the conversion of phosphatidate to diacylglycerol. Lipin-1 is critical for lipid synthesis and homeostasis in adipose tissue, liver, muscle, and peripheral nerves. Little is known about the physiological role of lipin-2, the predominant lipin protein present in liver and the deficient gene product in the rare disorder Majeed syndrome. By using lipin-2-deficient mice, we uncovered a functional relationship between lipin-1 and lipin-2 that operates in a tissue-specific and age-dependent manner. In liver, lipin-2 deficiency led to a compensatory increase in hepatic lipin-1 protein and elevated PAP activity, which maintained lipid homeostasis under basal conditions, but led to diet-induced hepatic triglyceride accumulation. As lipin-2-deficient mice aged, they developed ataxia and impaired balance. This was associated with the combination of lipin-2 deficiency and an age-dependent reduction in cerebellar lipin-1 levels, resulting in altered cerebellar phospholipid composition. Similar to patients with Majeed syndrome, lipin-2-deficient mice developed anemia, but did not show evidence of osteomyelitis, suggesting that additional environmental or genetic components contribute to the bone abnormalities observed in patients. Combined lipin-1 and lipin-2 deficiency caused embryonic lethality. Our results reveal functional interactions between members of the lipin family in vivo, and a unique role for lipin-2 in central nervous system biology that may be particularly important with advancing age. Additionally, as has been observed in mice and humans with lipin-1 deficiency, the pathophysiology in lipin-2 deficiency is associated with dysregulation of lipid intermediates.
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Abstract
PURPOSE OF REVIEW The finding that brown adipose tissue (BAT) is present in adults brought BAT physiology into the focus of many researchers interested in energy metabolism. Here, we review recent insight into how BAT develops, functions and might help to treat metabolic disorders in humans. RECENT FINDINGS BAT is under control of the nervous system, and several pathways have been identified that allow direct manipulation of BAT biology. In addition, some brown adipocytes arise from a distinct subset of white adipocyte precursors and studies were performed that characterize the development of these 'brite' adipocytes. Importantly, progress has been made in understanding how BAT takes up and dissipates nutrients that in metabolic disorders are present in excess. Finally, as it seems that BAT activity declines with age and obesity, we review findings that might shed light on how humans could sustain or increase BAT activity, thus preventing or treating obesity, hyperlipidemia and type 2 diabetes. SUMMARY BAT is a powerful organ that controls the development of metabolic disease. These powers are boosted by mechanisms that turn white into brown fat and enhance lipid flux into BAT. However, in humans, it remains unclear what was the first: metabolic disease or decreased BAT activity.
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Affiliation(s)
- Alexander Bartelt
- Department of Biochemistry and Molecular Cell Biology Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Current world literature. Lipid metabolism. Curr Opin Lipidol 2012; 23:248-254. [PMID: 22576583 DOI: 10.1097/mol.0b013e3283543033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Townsend K, Tseng YH. Brown adipose tissue: Recent insights into development, metabolic function and therapeutic potential. Adipocyte 2012; 1:13-24. [PMID: 23700507 PMCID: PMC3661118 DOI: 10.4161/adip.18951] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Obesity is currently a global pandemic, and is associated with increased mortality and co-morbidities including many metabolic diseases. Obesity is characterized by an increase in adipose mass due to increased energy intake, decreased energy expenditure, or both. While white adipose tissue is specialized for energy storage, brown adipose tissue has a high concentration of mitochondria and uniquely expresses uncoupling protein 1, enabling it to be specialized for energy expenditure and thermogenesis. Although brown fat was once considered only necessary in babies, recent morphological and imaging studies have provided evidence that, contrary to prior belief, this tissue is present and active in adult humans. In recent years, the topic of brown adipose tissue has been reinvigorated with many new studies regarding brown adipose tissue differentiation, function and therapeutic promise. This review summarizes the recent advances, discusses the emerging questions and offers perspective on the potential therapeutic applications targeting this tissue.
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Affiliation(s)
- Kristy Townsend
- Joslin Diabetes Center and Harvard Medical School; Boston, MA USA
| | - Yu-Hua Tseng
- Joslin Diabetes Center and Harvard Medical School; Boston, MA USA
- Harvard Stem Cell Institute; Harvard University; Cambridge, MA USA
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Wadhwani NS, Manglekar RR, Dangat KD, Kulkarni AV, Joshi SR. Effect of maternal micronutrients (folic acid, vitamin B12) and omega 3 fatty acids on liver fatty acid desaturases and transport proteins in Wistar rats. Prostaglandins Leukot Essent Fatty Acids 2012; 86:21-7. [PMID: 22133376 DOI: 10.1016/j.plefa.2011.10.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 10/20/2011] [Accepted: 10/22/2011] [Indexed: 11/20/2022]
Abstract
A disturbed fatty acid metabolism increases the risk of adult non-communicable diseases. This study examines the effect of maternal micronutrients on the fatty acid composition, desaturase activity, mRNA levels of fatty acid desaturases and transport proteins in the liver. Pregnant female rats were divided into 6 groups at 2 levels of folic acid both in the presence and absence of vitamin B(12). The vitamin B(12) deficient groups were supplemented with omega 3 fatty acid. An imbalance of maternal micronutrients reduces liver docosahexaenoic acid, increases Δ5 desaturase activity but decreases mRNA levels, decreases Δ6 desaturase activity but not mRNA levels as compared to control. mRNA level of Δ5 desaturase reverts back to the levels of the control group as a result of omega 3 fatty acid supplementation. Our data for the first time indicates that maternal micronutrients differentially alter the activity and expression of fatty acid desaturases in the liver.
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Affiliation(s)
- Nisha S Wadhwani
- Interactive Research School for Health Affairs, Bharati Vidyapeeth University, Pune, India
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Yang J, Bromage TG, Zhao Q, Xu BH, Gao WL, Tian HF, Tang HJ, Liu DW, Zhao XQ. Functional evolution of leptin of Ochotona curzoniae in adaptive thermogenesis driven by cold environmental stress. PLoS One 2011; 6:e19833. [PMID: 21698227 PMCID: PMC3116822 DOI: 10.1371/journal.pone.0019833] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 04/18/2011] [Indexed: 12/20/2022] Open
Abstract
Background Environmental stress can accelerate the directional selection and evolutionary rate of specific stress-response proteins to bring about new or altered functions, enhancing an organism's fitness to challenging environments. Plateau pika (Ochotona curzoniae), an endemic and keystone species on Qinghai-Tibetan Plateau, is a high hypoxia and low temperature tolerant mammal with high resting metabolic rate and non-shivering thermogenesis to cope in this harsh plateau environment. Leptin is a key hormone related to how these animals regulate energy homeostasis. Previous molecular evolutionary analysis helped to generate the hypothesis that adaptive evolution of plateau pika leptin may be driven by cold stress. Methodology/Principal Findings To test the hypothesis, recombinant pika leptin was first purified. The thermogenic characteristics of C57BL/6J mice injected with pika leptin under warm (23±1°C) and cold (5±1°C) acclimation is investigated. Expression levels of genes regulating adaptive thermogenesis in brown adipose tissue and the hypothalamus are compared between pika leptin and human leptin treatment, suggesting that pika leptin has adaptively and functionally evolved. Our results show that pika leptin regulates energy homeostasis via reduced food intake and increased energy expenditure under both warm and cold conditions. Compared with human leptin, pika leptin demonstrates a superior induced capacity for adaptive thermogenesis, which is reflected in a more enhanced β-oxidation, mitochondrial biogenesis and heat production. Moreover, leptin treatment combined with cold stimulation has a significant synergistic effect on adaptive thermogenesis, more so than is observed with a single cold exposure or single leptin treatment. Conclusions/Significance These findings support the hypothesis that cold stress has driven the functional evolution of plateau pika leptin as an ecological adaptation to the Qinghai-Tibetan Plateau.
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Affiliation(s)
- Jie Yang
- Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, Hebei, People's Republic of China
| | - Timothy G. Bromage
- Department of Biomaterials and Biomimetics, Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York, United States of America
| | - Qian Zhao
- Graduate School of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Bao Hong Xu
- Microbiology Department, Shijiazhuang Center for Disease Control and Prevention, Shijiazhuang, Hebei, People's Republic of China
| | - Wei Li Gao
- Microbiology Department, Shijiazhuang Center for Disease Control and Prevention, Shijiazhuang, Hebei, People's Republic of China
| | - Hui Fang Tian
- Microbiology Department, Shijiazhuang Center for Disease Control and Prevention, Shijiazhuang, Hebei, People's Republic of China
| | - Hui Jun Tang
- Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, Hebei, People's Republic of China
| | - Dian Wu Liu
- Department of Epidemiology and Statistics, School of Public Health, Hebei Medical University, Shijiazhuang, Hebei, People's Republic of China
- * E-mail: (DWL); (XQZ)
| | - Xin Quan Zhao
- Key Laboratory of Qinghai-Tibetan Plateau Biological Evolution and Adaptation, Northwest Plateau Institute of Biology, The Chinese Academy of Sciences, Xining, Qinghai, People's Republic of China
- * E-mail: (DWL); (XQZ)
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