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Parra LG, Erjavec LC, Casali CI, Zerpa Velazquez A, Weber K, Setton-Avruj CP, Fernández Tome MDC. Cytosolic phospholipase A 2 regulates lipid homeostasis under osmotic stress through PPARγ. FEBS J 2024; 291:722-743. [PMID: 37947039 DOI: 10.1111/febs.16998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 10/03/2023] [Accepted: 10/20/2023] [Indexed: 11/12/2023]
Abstract
Physiologically, renal medullary cells are surrounded by a hyperosmolar interstitium. However, different pathological situations can induce abrupt changes in environmental osmolality, causing cell stress. Therefore, renal cells must adapt to survive in this new condition. We previously demonstrated that, among the mechanisms involved in osmoprotection, renal cells upregulate triglyceride biosynthesis (which helps preserve glycerophospholipid synthesis and membrane homeostasis) and cyclooxygenase-2 (which generates prostaglandins from arachidonic acid) to maintain lipid metabolism in renal tissue. Herein, we evaluated whether hyperosmolality modulates phospholipase A2 (PLA2 ) activity, leading to arachidonic acid release from membrane glycerophospholipid, and investigated its possible role in hyperosmolality-induced triglyceride synthesis and accumulation. We found that hyperosmolality induced PLA2 expression and activity in Madin-Darby canine kidney cells. Cytosolic PLA2 (cPLA2) inhibition, but not secreted or calcium-independent PLA2 (sPLA2 or iPLA2 , respectively), prevented triglyceride synthesis and reduced cell survival. Inhibition of prostaglandin synthesis with indomethacin not only failed to prevent hyperosmolality-induced triglyceride synthesis but also exacerbated it. Similar results were observed with the peroxisomal proliferator activated receptor gamma (PPARγ) agonist rosiglitazone. Furthermore, hyperosmolality increased free intracellular arachidonic acid levels, which were even higher when prostaglandin synthesis was inhibited by indomethacin. Blocking PPARγ with GW-9662 prevented the effects of both indomethacin and rosiglitazone on triglyceride synthesis and even reduced hyperosmolality-induced triglyceride synthesis, suggesting that arachidonic acid may stimulate triglyceride synthesis through PPARγ activation. These results highlight the role of cPLA2 in osmoprotection, since it is essential to provide arachidonic acid, which is involved in PPARγ-regulated triglyceride synthesis, thus guaranteeing cell survival.
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Affiliation(s)
- Leandro Gastón Parra
- Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina
- Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini (IQUIFIB)-Facultad de Farmacia y Bioquímica, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Luciana Cecilia Erjavec
- Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina
- Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini (IQUIFIB)-Facultad de Farmacia y Bioquímica, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Cecilia Irene Casali
- Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina
- Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini (IQUIFIB)-Facultad de Farmacia y Bioquímica, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Andrea Zerpa Velazquez
- Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina
| | - Karen Weber
- Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina
| | - Clara Patricia Setton-Avruj
- Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini (IQUIFIB)-Facultad de Farmacia y Bioquímica, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
- Departaemento de Química Biológica, Cátedra de Química Biológica Patológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina
| | - María Del Carmen Fernández Tome
- Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina
- Instituto de Química y Fisicoquímica Biológicas Prof. Dr. Alejandro C. Paladini (IQUIFIB)-Facultad de Farmacia y Bioquímica, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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Péter M, Gudmann P, Kóta Z, Török Z, Vígh L, Glatz A, Balogh G. Lipids and Trehalose Actively Cooperate in Heat Stress Management of Schizosaccharomyces pombe. Int J Mol Sci 2021; 22:13272. [PMID: 34948069 DOI: 10.3390/ijms222413272] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/04/2021] [Accepted: 12/08/2021] [Indexed: 01/22/2023] Open
Abstract
Homeostatic maintenance of the physicochemical properties of cellular membranes is essential for life. In yeast, trehalose accumulation and lipid remodeling enable rapid adaptation to perturbations, but their crosstalk was not investigated. Here we report about the first in-depth, mass spectrometry-based lipidomic analysis on heat-stressed Schizosaccharomyces pombe mutants which are unable to synthesize (tps1Δ) or degrade (ntp1Δ) trehalose. Our experiments provide data about the role of trehalose as a membrane protectant in heat stress. We show that under conditions of trehalose deficiency, heat stress induced a comprehensive, distinctively high-degree lipidome reshaping in which structural, signaling and storage lipids acted in concert. In the absence of trehalose, membrane lipid remodeling was more pronounced and increased with increasing stress dose. It could be characterized by decreasing unsaturation and increasing acyl chain length, and required de novo synthesis of stearic acid (18:0) and very long-chain fatty acids to serve membrane rigidification. In addition, we detected enhanced and sustained signaling lipid generation to ensure transient cell cycle arrest as well as more intense triglyceride synthesis to accommodate membrane lipid-derived oleic acid (18:1) and newly synthesized but unused fatty acids. We also demonstrate that these changes were able to partially substitute for the missing role of trehalose and conferred measurable stress tolerance to fission yeast cells.
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3
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Tan SY, Little HC, Sarver DC, Watkins PA, Wong GW. CTRP12 inhibits triglyceride synthesis and export in hepatocytes by suppressing HNF-4α and DGAT2 expression. FEBS Lett 2020; 594:3227-3239. [PMID: 32749667 DOI: 10.1002/1873-3468.13895] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/21/2020] [Accepted: 07/25/2020] [Indexed: 12/15/2022]
Abstract
C1q/TNF-related protein 12 (CTRP12) is an antidiabetic adipokine whose circulating levels are reduced in obesity and diabetes. Although partial and complete loss-of-function mouse models suggest a role for CTRP12 in modulating lipid metabolism and adiposity, its effect on cellular lipid metabolism remains poorly defined. Here, we demonstrate a direct action of CTRP12 in regulating lipid synthesis and secretion. In hepatoma cells and primary mouse hepatocytes, CTRP12 treatment inhibits triglyceride synthesis by suppressing glycerophosphate acyltransferase (GPAT) and diacylglycerol acyltransferase (DGAT) expression. CTRP12 treatment also downregulates the expression of hepatocyte nuclear factor-4α (HNF-4α) and its target gene microsomal triglyceride transfer protein (MTTP), leading to reduced very-low-density lipoprotein (VLDL)-triglyceride export from hepatocytes. Consistent with the in vitro findings, overexpressing CTRP12 lowers fasting and postprandial serum triglyceride levels in mice. These results underscore the important function of CTRP12 in lipid metabolism in hepatocytes.
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Affiliation(s)
- Stefanie Y Tan
- Department of Physiology and Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Pfizer, 1 Portland St., Cambridge, MA, 02139, USA
| | - Hannah C Little
- Department of Physiology and Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Dylan C Sarver
- Department of Physiology and Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Paul A Watkins
- Department of Neurology and Biological Chemistry, Johns Hopkins University School of Medicine, and Hugo W. Moser Research Institute at Kennedy Krieger, Baltimore, MD, USA
| | - G William Wong
- Department of Physiology and Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Mendez-Garcia C, Trini A, Browne V, Kochansky CJ, Pontiggia L, D'mello AP. Decreased liver triglyceride content in adult rats exposed to protein restriction during gestation and lactation: roles of hepatic lipogenesis and lipid utilization in muscle and adipose tissue. Can J Physiol Pharmacol 2019; 97:952-962. [PMID: 31238009 DOI: 10.1139/cjpp-2018-0646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Protein restriction throughout pregnancy and lactation reduces liver triglyceride (TG) content in adult male rat offspring. The study determined the contribution of hepatic lipogenesis to the reduction in liver TG content. Rats received either control or protein-restricted diets throughout pregnancy and lactation. Offspring were sacrificed on day 65. Hepatic fatty acid uptake and de novo fatty acid and TG biosynthesis were similar between control and low-protein (LP) offspring. These results indicate that hepatic lipogenesis cannot mediate the decrease in liver TG content in LP offspring. We then determined whether increased lipid utilization in adipose tissue and muscle was responsible for the decrease in liver TG content. There was suggestive evidence of increased sympathetic nervous system tone in epididymal adipose tissue of LP offspring that increased fatty acid uptake, TG lipolysis, and utilization of fatty acids in mitochondrial thermogenesis. Measurement of similar parameters demonstrated that such alterations do not occur in gastrocnemius muscle, another major lipid-utilizing tissue. Our results suggest that the decrease in liver TG content in LP offspring is likely due to increased diversion of fatty acids to white and brown adipose tissue depots and their enhanced utilization to fuel mitochondrial thermogenesis.
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Affiliation(s)
- Claudia Mendez-Garcia
- Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, USA
| | - Afsana Trini
- Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, USA
| | - Veron Browne
- Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, USA
| | - Christopher J Kochansky
- Pharmacokinetics, Pharmacodynamics, and Drug Metabolism (PPDM), Merck & Co., Inc. P.O. Box 4, 770 Sumneytown Pike, WP75A-203, West Point, PA 19486, USA
| | - Laura Pontiggia
- Department of Mathematics, Physics, and Statistics, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, USA
| | - Anil P D'mello
- Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, USA
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Satoh S, Onomura D, Ueda Y, Dansako H, Honda M, Kaneko S, Kato N. Ribavirin-induced down-regulation of CCAAT/enhancer-binding protein α leads to suppression of lipogenesis. Biochem J 2019; 476:137-49. [PMID: 30552141 DOI: 10.1042/BCJ20180680] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 12/04/2018] [Accepted: 12/14/2018] [Indexed: 12/24/2022]
Abstract
Recently, we demonstrated that the anti-viral drug ribavirin (RBV) had the ability to suppress lipogenesis through down-regulation of retinoid X receptor α (RXRα) under the control of the intracellular GTP-level and AMP-activated protein kinase-related kinases, especially microtubule affinity regulating kinase 4 (MARK4). RXRα-overexpression attenuated but did not abolish lipogenesis suppression by RBV, implying that additional factor(s) were involved in this suppressive effect. In the present study, we found that the protein level, but not the mRNA level, of CCAAT/enhancer-binding protein α (C/EBPα) was down-regulated by RBV in hepatic cells. Treatment with proteasome inhibitor attenuated RBV-induced down-regulation of C/EBPα, suggesting that RBV promoted degradation of C/EBPα protein via the ubiquitin-proteasome pathway. Depletion of intracellular GTP through inosine monophosphate dehydrogenase inhibition by RBV led to down-regulation of C/EBPα. In contrast, down-regulation of C/EBPα by RBV was independent of RXRα and MARK4. Knockdown of C/EBPα reduced the intracellular neutral lipid levels and the expression of genes related to the triglyceride (TG) synthesis pathway, especially glycerol-3-phosphate acyltransferase, mitochondrial (GPAM), which encodes the first rate-limiting TG enzyme. Overexpression of C/EBPα yielded the opposite results. We also observed that RBV decreased GPAM expression. Moreover, overexpression of GPAM attenuated RBV-induced reduction in the intracellular neutral lipid levels. These data suggest that down-regulation of C/EBPα by RBV leads to the reduction in GPAM expression, which contributes to the suppression of lipogenesis. Our findings about the mechanism of RBV action in lipogenesis suppression will provide new insights for therapy against the active lipogenesis involved in hepatic steatosis and hepatocellular carcinomas.
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Morgan-Bathke M, Chen L, Oberschneider E, Harteneck D, Jensen MD. More insights into a human adipose tissue GPAT activity assay. Adipocyte 2016; 5:93-6. [PMID: 27144101 DOI: 10.1080/21623945.2015.1068977] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 06/24/2015] [Accepted: 06/25/2015] [Indexed: 10/23/2022] Open
Abstract
Adipose tissue fatty acid storage varies according to sex, adipose tissue depot and degree of fat gain. However, the mechanism(s) for these variations is not completely understood. We recently published findings based on the glycerol 3-phosphate acyltransferase (GPAT) enzyme activity assay we optimized for use with human adipose tissue. These findings include a decrease in total GPAT and GPAT1 as a function of adipocyte size in both omental and subcutaneous adipose tissue and a strong, positive correlations between ACS, GPAT, and DGAT activities for both sexes and depots and between these storage factors and palmitate storage rates into TAG. The aim of this commentary is to expand upon the data from our recent publication. We describe here additional details on the optimization of the GPAT enzyme activity assay, a correlation between DGAT and percentage palmitate in the diacylglycerol fraction, and sex differences in fatty acid storage factors and storage rates into TAG at high palmitate concentrations.
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Wilfling F, Thiam AR, Olarte MJ, Wang J, Beck R, Gould TJ, Allgeyer ES, Pincet F, Bewersdorf J, Farese RV, Walther TC. Arf1/COPI machinery acts directly on lipid droplets and enables their connection to the ER for protein targeting. eLife 2014; 3:e01607. [PMID: 24497546 PMCID: PMC3913038 DOI: 10.7554/elife.01607] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Lipid droplets (LDs) are ubiquitous organelles that store neutral lipids, such as triacylglycerol (TG), as reservoirs of metabolic energy and membrane precursors. The Arf1/COPI protein machinery, known for its role in vesicle trafficking, regulates LD morphology, targeting of specific proteins to LDs and lipolysis through unclear mechanisms. Recent evidence shows that Arf1/COPI can bud nano-LDs (∼60 nm diameter) from phospholipid-covered oil/water interfaces in vitro. We show that Arf1/COPI proteins localize to cellular LDs, are sufficient to bud nano-LDs from cellular LDs, and are required for targeting specific TG-synthesis enzymes to LD surfaces. Cells lacking Arf1/COPI function have increased amounts of phospholipids on LDs, resulting in decreased LD surface tension and impairment to form bridges to the ER. Our findings uncover a function for Arf1/COPI proteins at LDs and suggest a model in which Arf1/COPI machinery acts to control ER-LD connections for localization of key enzymes of TG storage and catabolism. DOI: http://dx.doi.org/10.7554/eLife.01607.001.
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Affiliation(s)
- Florian Wilfling
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
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Poursharifi P, Lapointe M, Fisette A, Lu H, Roy C, Munkonda MN, Fairlie DP, Cianflone K. C5aR and C5L2 act in concert to balance immunometabolism in adipose tissue. Mol Cell Endocrinol 2014; 382:325-333. [PMID: 24397921 DOI: 10.1016/j.mce.2013.10.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 10/15/2013] [Indexed: 12/24/2022]
Abstract
Recent studies suggested that the immunometabolic receptors; C5aR and C5L2, constitutively self-associate into homo-/heterodimers and that acylation stimulating protein (ASP/C3adesArg) or C5a treatment of adipocytes increased their colocalization. The present study evaluates the C5aR contribution in adipocytes to the metabolic and immune responses elicited by ligand stimulation. The effects of C5a, ASP, and insulin on cytokine production, triglyceride synthesis (TGS), and key signaling pathways were evaluated in isolated primary adipocytes and cultured 3T3-L1 differentiated adipocytes. In addition, mRNA expression of IRS1 and PGC1α was compared in adipose tissue samples from WT vs. C5aRKO mice. Both C5a and ASP directly increased MCP-1 (238±4%; P<0.001, and 377±2% vs. basal 100%; P<0.001, respectively) and KC (413±11%; P<0.001, and 529±16%; P<0.001 vs. basal 100%, respectively) secretion, TGS (131±1%; P<0.001, and 152±6%; P<0.001, vs. basal 100% respectively), and Akt/NFκB phosphorylation pathways in adipocytes. However, in C5aRKO adipocytes, C5a effects were disrupted, while stimulatory effects of ASP were mostly maintained. Addition of C5a completely blocked ASP signaling and activity in both C5aRKO and WT adipocytes as well as 3T3-L1 adipocytes. Furthermore, C5aRKO adipocytes revealed impaired insulin stimulation of cytokine production, with partial impairment of signaling and TGS stimulation, consistent with decreased IRS1 and PGC1α mRNA expression in adipose tissue. These observations indicate the importance of C5aR in adipose tissue metabolism and immunity, which may be regulated through heterodimerization with C5L2.
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Affiliation(s)
- Pegah Poursharifi
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Québec, QC, Canada; Department of Medicine, Laval University, Québec, QC, Canada
| | - Marc Lapointe
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Québec, QC, Canada
| | - Alexandre Fisette
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Québec, QC, Canada; Department of Medicine, Laval University, Québec, QC, Canada
| | - Huiling Lu
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Québec, QC, Canada
| | - Christian Roy
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Québec, QC, Canada; Department of Medicine, Laval University, Québec, QC, Canada
| | - Mercedes Nancy Munkonda
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Québec, QC, Canada; Department of Medicine, Laval University, Québec, QC, Canada
| | - David P Fairlie
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Katherine Cianflone
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Québec, QC, Canada; Department of Medicine, Laval University, Québec, QC, Canada.
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Yogosawa S, Izumi T. Roles of activin receptor-like kinase 7 signaling and its target, peroxisome proliferator-activated receptor γ, in lean and obese adipocytes. Adipocyte 2013; 2:246-50. [PMID: 24052900 PMCID: PMC3774700 DOI: 10.4161/adip.24974] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/06/2013] [Accepted: 05/08/2013] [Indexed: 11/25/2022] Open
Abstract
We recently discovered a novel signaling pathway involving activin receptor-like kinase 7 (ALK7), one of the type I transforming growth factor-β receptors. ALK7 and activated Smads 2, 3, and 4 inhibit the master regulators of adipogenesis, CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ) specifically in differentiated adipocytes, but surprisingly increase both the adipocyte size and lipid content by suppressing lipolysis. Here, we show that, although both transcription factors are suppressed by ALK7 in either the obese or lean state, PPARγ, but not C/EBPα, is further suppressed under obesity through an ALK7-independent pathway. As a result, PPARγ and adipose lipolytic activities are severely downregulated in obesity. Reactivation of PPARγ by ALK7 inactivation leads to downregulation of inflammatory adipocytokines and upregulation of adiponectin. We propose that PPARγ promotes lipid turnover and remodeling by stimulating both triglyceride synthesis and breakdown in differentiated adipocytes. Finally, we discuss the physiological and evolutionary roles of the ALK7-signaling pathway and consider it as a potential target of therapy for obesity.
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Mastrocola R, Collino M, Rogazzo M, Medana C, Nigro D, Boccuzzi G, Aragno M. Advanced glycation end products promote hepatosteatosis by interfering with SCAP-SREBP pathway in fructose-drinking mice. Am J Physiol Gastrointest Liver Physiol 2013; 305:G398-407. [PMID: 23868406 DOI: 10.1152/ajpgi.00450.2012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Clinical studies have linked the increased consumption of fructose to the development of obesity, dyslipidemia, and impaired glucose tolerance, and a role in hepatosteatosis development is presumed. Fructose can undergo a nonenzymatic reaction from which advanced glycation end products (AGEs) are derived, leading to the formation of dysfunctional, fructosylated proteins; however, the in vivo formation of AGEs from fructose is still less known than that from glucose. In the present study C57Bl/6J mice received 15% (wt/vol) fructose (FRT) or 15% (wt/vol) glucose (GLC) in water to drink for 30 wk, resembling human habit to consume sugary drinks. At the end of the protocol both FRT- and GLC-drinking mice had increased fasting glycemia, glucose intolerance, altered plasma lipid profile, and marked hepatosteatosis. FRT mice had higher hepatic triglycerides deposition than GLC, paralleled by a greater increased expression and activity of the sterol regulatory element-binding protein 1 (SREBP1), the transcription factor responsible for the de novo lipogenesis, and of its activating protein SCAP. LC-MS analysis showed a different pattern of AGE production in liver tissue between FRT and GLC mice, with larger amount of carboxymethyl lysine (CML) generated by fructose. Double immunofluorescence and coimmunoprecipitation analysis revealed an interaction between CML and SCAP that could lead to prolonged activation of SREBP1. Overall, the high levels of CML and activation of SCAP/SREBP pathway associated to high fructose exposure here reported may suggest a key role of this signaling pathway in mediating fructose-induced lipogenesis.
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Affiliation(s)
- Raffaella Mastrocola
- Dept. of Clinical and Biological Sciences, Experimental Medicine and Clinical Pathology Unit, Univ. of Turin, C.so Raffaello 30, 10125 Torino, Italy.
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11
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Peterson JM, Seldin MM, Wei Z, Aja S, Wong GW. CTRP3 attenuates diet-induced hepatic steatosis by regulating triglyceride metabolism. Am J Physiol Gastrointest Liver Physiol 2013; 305:G214-24. [PMID: 23744740 PMCID: PMC3742855 DOI: 10.1152/ajpgi.00102.2013] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
CTRP3 is a secreted plasma protein of the C1q family that helps regulate hepatic gluconeogenesis and is downregulated in a diet-induced obese state. However, the role of CTRP3 in regulating lipid metabolism has not been established. Here, we used a transgenic mouse model to address the potential function of CTRP3 in ameliorating high-fat diet-induced metabolic stress. Both transgenic and wild-type mice fed a high-fat diet showed similar body weight gain, food intake, and energy expenditure. Despite similar adiposity to wild-type mice upon diet-induced obesity (DIO), CTRP3 transgenic mice were strikingly resistant to the development of hepatic steatosis, had reduced serum TNF-α levels, and demonstrated a modest improvement in systemic insulin sensitivity. Additionally, reduced hepatic triglyceride levels were due to decreased expression of enzymes (GPAT, AGPAT, and DGAT) involved in triglyceride synthesis. Importantly, short-term daily administration of recombinant CTRP3 to DIO mice for 5 days was sufficient to improve the fatty liver phenotype, evident as reduced hepatic triglyceride content and expression of triglyceride synthesis genes. Consistent with a direct effect on liver cells, recombinant CTRP3 treatment reduced fatty acid synthesis and neutral lipid accumulation in cultured rat H4IIE hepatocytes. Together, these results establish a novel role for CTRP3 hormone in regulating hepatic lipid metabolism and highlight its protective function and therapeutic potential in attenuating hepatic steatosis.
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Affiliation(s)
- Jonathan M. Peterson
- 1Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland; ,3Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, Maryland; and ,4Department of Health Sciences, School of Public Health, East Tennessee State University, Johnson City, Tennessee
| | - Marcus M. Seldin
- 1Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland; ,3Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Zhikui Wei
- 1Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland; ,3Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Susan Aja
- 2Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland; ,3Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - G. William Wong
- 1Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland; ,3Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
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Serrano-Wu MH, Coppola GM, Gong Y, Neubert AD, Chatelain R, Clairmont KB, Commerford R, Cosker T, Daniels T, Hou Y, Jain M, Juedes M, Li L, Mullarkey T, Rocheford E, Sung MJ, Tyler A, Yang Q, Yoon T, Hubbard BK. Intestinally Targeted Diacylglycerol Acyltransferase 1 (DGAT1) Inhibitors Robustly Suppress Postprandial Triglycerides. ACS Med Chem Lett 2012; 3:411-5. [PMID: 24900485 DOI: 10.1021/ml3000512] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Accepted: 04/04/2012] [Indexed: 01/15/2023] Open
Abstract
High DGAT1 expression levels in the small intestine highlight the critical role this enzyme plays in nutrient absorption. Identification of inhibitors which predominantly inhibit DGAT1 in the gut is an attractive drug discovery strategy with anticipated benefits of reduced systemic toxicity. In this report we describe our discovery and optimization of DGAT1 inhibitors whose plasma exposure is minimized by the action of transporters, including the P-glycoprotein transporter. The impact of this unique absorption profile on efficacy in rat and dog efficacy models is presented.
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Affiliation(s)
- Michael H. Serrano-Wu
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Gary M. Coppola
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Yongjin Gong
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Alan D. Neubert
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Ricardo Chatelain
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Kevin B. Clairmont
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Renee Commerford
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Theresa Cosker
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Thomas Daniels
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Ying Hou
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Monish Jain
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Marlene Juedes
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Lisha Li
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Tara Mullarkey
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Erik Rocheford
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Moo Je Sung
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Andrew Tyler
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Qing Yang
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Taeyoung Yoon
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
| | - Brian K. Hubbard
- Departments
of Global Discovery Chemistry, ‡Cardiovascular and Metabolism, §Metabolism and Pharmacokinetics, and ∥Translational
Sciences, Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge Massachusetts
02139, United States
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13
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Oh YT, Oh KS, Choi YM, Jokiaho A, Donovan C, Choi S, Kang I, Youn JH. Continuous 24-h nicotinic acid infusion in rats causes FFA rebound and insulin resistance by altering gene expression and basal lipolysis in adipose tissue. Am J Physiol Endocrinol Metab 2011; 300:E1012-21. [PMID: 21386057 PMCID: PMC3118587 DOI: 10.1152/ajpendo.00650.2010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Nicotinic acid (NA) has been used as a lipid drug for five decades. The lipid-lowering effects of NA are attributed to its ability to suppress lipolysis in adipocytes and lower plasma FFA levels. However, plasma FFA levels often rebound during NA treatment, offsetting some of the lipid-lowering effects of NA and/or causing insulin resistance, but the underlying mechanisms are unclear. The present study was designed to determine whether a prolonged, continuous NA infusion in rats produces a FFA rebound and/or insulin resistance. NA infusion rapidly lowered plasma FFA levels (>60%, P < 0.01), and this effect was maintained for ≥5 h. However, when this infusion was extended to 24 h, plasma FFA levels rebounded to the levels of saline-infused control rats. This was not due to a downregulation of NA action, because when the NA infusion was stopped, plasma FFA levels rapidly increased more than twofold (P < 0.01), indicating that basal lipolysis was increased. Microarray analysis revealed many changes in gene expression in adipose tissue, which would contribute to the increase in basal lipolysis. In particular, phosphodiesterase-3B gene expression decreased significantly, which would increase cAMP levels and thus lipolysis. Hyperinsulinemic glucose clamps showed that insulin's action on glucose metabolism was improved during 24-h NA infusion but became impaired with increased plasma FFA levels after cessation of NA infusion. In conclusion, a 24-h continuous NA infusion in rats resulted in an FFA rebound, which appeared to be due to altered gene expression and increased basal lipolysis in adipose tissue. In addition, our data support a previous suggestion that insulin resistance develops as a result of FFA rebound during NA treatment. Thus, the present study provides an animal model and potential molecular mechanisms of FFA rebound and insulin resistance, observed in clinical studies with chronic NA treatment.
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Affiliation(s)
- Young Taek Oh
- Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, Los Angeles, CA 90089, USA
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14
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Villanueva CJ, Monetti M, Shih M, Zhou P, Watkins SM, Bhanot S, Farese RV. Specific role for acyl CoA:Diacylglycerol acyltransferase 1 (Dgat1) in hepatic steatosis due to exogenous fatty acids. Hepatology 2009; 50:434-42. [PMID: 19472314 PMCID: PMC3097135 DOI: 10.1002/hep.22980] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
UNLABELLED Nonalcoholic fatty liver disease, characterized by the accumulation of triacylglycerols (TGs) and other lipids in the liver, often accompanies obesity and is a risk factor for nonalcoholic steatohepatitis and fibrosis. To treat or prevent fatty liver, a thorough understanding of hepatic fatty acid and TG metabolism is crucial. To investigate the role of acyl CoA:diacylglycerol acyltransferase 1 (DGAT1), a key enzyme of TG synthesis, in fatty liver development, we studied mice with global and liver-specific knockout of Dgat1. DGAT1 was required for hepatic steatosis induced by a high-fat diet and prolonged fasting, which are both characterized by delivery of exogenous fatty acids to the liver. Studies in primary hepatocytes showed that DGAT1 deficiency protected against hepatic steatosis by reducing synthesis and increasing the oxidation of fatty acids. In contrast, lipodystrophy (aP2-SREBP-1c436) and liver X receptor activation (T0901317), which increase de novo fatty acid synthesis in liver, caused steatosis independently of DGAT1. Pharmacologic inhibition of Dgat1 with antisense oligonucleotides protected against fatty liver induced by a high-fat diet. CONCLUSION Our findings identify a specific role for hepatic DGAT1 in esterification of exogenous fatty acids and indicate that DGAT1 contributes to hepatic steatosis induced by this mechanism.
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Affiliation(s)
- Claudio J. Villanueva
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94158, Biomedical Sciences Graduate Program, University of California, San Francisco, California 94158
| | - Mara Monetti
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94158
| | - Michelle Shih
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94158, Biomedical Sciences Graduate Program, University of California, San Francisco, California 94158
| | - Ping Zhou
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94158
| | | | - Sanjay Bhanot
- Isis Pharmaceuticals, Inc., Carlsbad, California 92008
| | - Robert V. Farese
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94158, Department of Medicine and of Biochemistry & Biophysics, University of California, San Francisco, California 94158, Diabetes Center, University of California, San Francisco, California 94158, Biomedical Sciences Graduate Program, University of California, San Francisco, California 94158
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