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Edwin RK, Acharya LP, Maity SK, Chakrabarti P, Tantia O, Joshi MB, Satyamoorthy K, Parsa KVL, Misra P. TGS1/PIMT knockdown reduces lipid accumulation in adipocytes, limits body weight gain and promotes insulin sensitivity in mice. Biochim Biophys Acta Mol Basis Dis 2024; 1870:166896. [PMID: 37751782 DOI: 10.1016/j.bbadis.2023.166896] [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: 06/15/2023] [Revised: 09/16/2023] [Accepted: 09/20/2023] [Indexed: 09/28/2023]
Abstract
PRIP Interacting protein with Methyl Transferase domain (PIMT/TGS1) is an integral upstream coactivator in the peroxisome proliferator-activated receptor gamma (PPARγ) transcriptional apparatus. PPARγ activation alleviates insulin resistance but promotes weight gain. Herein, we show how PIMT regulates body weight while promoting insulin sensitivity in diet induced obese mice. In vitro, we observed enhanced PIMT levels during adipogenesis. Knockdown of PIMT in 3T3-L1 results in reduced lipid accumulation and alters PPARγ regulated gene expression. Intraperitoneal injection of shPIMT lentivirus in high fat diet (HFD)-fed mice caused reduced adipose tissue size and decreased expression of lipid markers. This was accompanied by significantly lower levels of inflammation, hypertrophy and hyperplasia in the different adipose depots (eWAT and iWAT). Notably, PIMT depletion limits body weight gain in HFD-fed mice along with improved impaired oral glucose clearance. It also enhanced insulin sensitivity revealed by assessment of important insulin resistance markers and increased adiponectin levels. In addition, reduced PIMT levels did not alter the serum free fatty acid and TNFα levels. Finally, the relevance of our studies to human obesity is suggested by our finding that PIMT was upregulated in adipose tissue of obese patients along with crucial fat marker genes. We speculate that PIMT may be a potential target in maintaining energy metabolism, thus regulating obesity.
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Affiliation(s)
- Rebecca Kristina Edwin
- Centre for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Gachibowli, Hyderabad 500046, India; Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka 576104, India
| | - Lavanya Prakash Acharya
- Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka 576104, India
| | - Sujay K Maity
- Indian Institute of Chemical Biology (CSIR-IICB), 4, Raja Subodh Chandra Mallick Rd, Poddar Nagar, Jadavpur, Kolkata, West Bengal 700032, India
| | - Partha Chakrabarti
- Indian Institute of Chemical Biology (CSIR-IICB), 4, Raja Subodh Chandra Mallick Rd, Poddar Nagar, Jadavpur, Kolkata, West Bengal 700032, India
| | - Om Tantia
- Institute of Laparoscopic Surgery Group of Hospitals, DD - 6, Sector I, Salt Lake City, Kolkata 700064, West Bengal, India
| | - Manjunath B Joshi
- Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka 576104, India
| | - Kapaettu Satyamoorthy
- Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka 576104, India; SDM College of Medical Sciences and Hospital, Shri Dharmasthala Manjunatheshwara (SDM) University, Manjushree Nagar, Sattur, Dharwad, Karnataka 580009, India.
| | - Kishore V L Parsa
- Centre for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Gachibowli, Hyderabad 500046, India.
| | - Parimal Misra
- Centre for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Gachibowli, Hyderabad 500046, India.
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Myers MN, Abou-Rjeileh U, Chirivi M, Parales-Girón J, Lock AL, Tam J, Zachut M, Contreras GA. Cannabinoid-1 receptor activation modulates lipid mobilization and adipogenesis in the adipose tissue of dairy cows. J Dairy Sci 2023; 106:3650-3661. [PMID: 36907764 DOI: 10.3168/jds.2022-22556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 11/27/2022] [Indexed: 03/12/2023]
Abstract
Amplified adipose tissue (AT) lipolysis and suppressed lipogenesis characterize the periparturient period of dairy cows. The intensity of lipolysis recedes with the progression of lactation; however, when lipolysis is excessive and prolonged, disease risk is exacerbated and productivity compromised. Interventions that minimize lipolysis while maintaining adequate supply of energy and enhancing lipogenesis may improve periparturient cows' health and lactation performance. Cannabinoid-1 receptor (CB1R) activation in rodent AT enhances the lipogenic and adipogenic capacity of adipocytes, yet the effects in dairy cow AT remain unknown. Using a synthetic CB1R agonist and an antagonist, we determined the effects of CB1R stimulation on lipolysis, lipogenesis, and adipogenesis in the AT of dairy cows. Adipose tissue explants were collected from healthy, nonlactating and nongestating (NLNG; n = 6) or periparturient (n = 12) cows at 1 wk before parturition and at 2 and 3 wk postpartum (PP1 and PP2, respectively). Explants were treated with the β-adrenergic agonist isoproterenol (1 μM) in the presence of the CB1R agonist arachidonyl-2'-chloroethylamide (ACEA) ± the CB1R antagonist rimonabant (RIM). Lipolysis was quantified based on glycerol release. We found that ACEA reduced lipolysis in NLNG cows; however, it did not exhibit a direct effect on AT lipolysis in periparturient cows. Inhibition of CB1R with RIM in postpartum cow AT did not alter lipolysis. To evaluate adipogenesis and lipogenesis, preadipocytes isolated from NLNG cows' AT were induced to differentiate in the presence or absence of ACEA ± RIM for 4 and 12 d. Live cell imaging, lipid accumulation, and expressions of key adipogenic and lipogenic markers were assessed. Preadipocytes treated with ACEA had higher adipogenesis, whereas ACEA+RIM reduced it. Adipocytes treated with ACEA and RIM for 12 d exhibited enhanced lipogenesis compared with untreated cells (control). Lipid content was reduced in ACEA+RIM but not with RIM alone. Collectively, our results support that lipolysis may be reduced by CB1R stimulation in NLNG cows but not in periparturient cows. In addition, our findings demonstrate that adipogenesis and lipogenesis are enhanced by activation of CB1R in the AT of NLNG dairy cows. In summary, we provide initial evidence which supports that the sensitivity of the AT endocannabinoid system to endocannabinoids, and its ability to modulate AT lipolysis, adipogenesis, and lipogenesis, vary based on dairy cows' lactation stage.
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Affiliation(s)
- Madison N Myers
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824
| | - Ursula Abou-Rjeileh
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824
| | - Miguel Chirivi
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824
| | - Jair Parales-Girón
- Department of Animal Science, College of Agriculture and Natural Resources, Michigan State University, East Lansing 48824
| | - Adam L Lock
- Department of Animal Science, College of Agriculture and Natural Resources, Michigan State University, East Lansing 48824
| | - Joseph Tam
- Obesity and Metabolism Laboratory, Institute for Drug Research, School of Pharmacy, Faculty of Medicine, the Hebrew University of Jerusalem, Jerusalem, Israel 9112001
| | - Maya Zachut
- Department of Ruminant Science, Institute of Animal Sciences, Volcani Institute, Rishon LeZion, Israel 7505101
| | - G Andres Contreras
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824.
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Prenylcysteine Oxidase 1 Is a Key Regulator of Adipogenesis. Antioxidants (Basel) 2023; 12:antiox12030542. [PMID: 36978789 PMCID: PMC10045348 DOI: 10.3390/antiox12030542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 02/18/2023] [Accepted: 02/19/2023] [Indexed: 02/24/2023] Open
Abstract
The process of adipogenesis involves the differentiation of preadipocytes into mature adipocytes. Excessive adipogenesis promotes obesity, a condition that increasingly threatens global health and contributes to the rapid rise of obesity-related diseases. We have recently shown that prenylcysteine oxidase 1 (PCYOX1) is a regulator of atherosclerosis-disease mechanisms, which acts through mechanisms not exclusively related to its pro-oxidant activity. To address the role of PCYOX1 in the adipogenic process, we extended our previous observations confirming that Pcyox1−/−/Apoe−/− mice fed a high-fat diet for 8 or 12 weeks showed significantly lower body weight, when compared to Pcyox1+/+/Apoe−/− mice, due to an evident reduction in visceral adipose content. We herein assessed the role of PCYOX1 in adipogenesis. Here, we found that PCYOX1 is expressed in adipose tissue, and, independently from its pro-oxidant enzymatic activity, is critical for adipogenesis. Pcyox1 gene silencing completely prevented the differentiation of 3T3-L1 preadipocytes, by acting as an upstream regulator of several key players, such as FABP4, PPARγ, C/EBPα. Proteomic analysis, performed by quantitative label-free mass spectrometry, further strengthened the role of PCYOX1 in adipogenesis by expanding the list of its downstream targets. Finally, the absence of Pcyox1 reduces the inflammatory markers in adipose tissue. These findings render PCYOX1 a novel adipogenic factor with possible pathophysiological or therapeutic potential.
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Rosiglitazone Reverses Inflammation in Epididymal White Adipose Tissue in Hormone-Sensitive Lipase-Knockout Mice. J Lipid Res 2022; 64:100305. [PMID: 36273647 PMCID: PMC9760656 DOI: 10.1016/j.jlr.2022.100305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/05/2022] [Accepted: 09/25/2022] [Indexed: 11/06/2022] Open
Abstract
Hormone-sensitive lipase (HSL) plays a crucial role in intracellular lipolysis, and loss of HSL leads to diacylglycerol (DAG) accumulation, reduced FA mobilization, and impaired PPARγ signaling. Hsl knockout mice exhibit adipose tissue inflammation, but the underlying mechanisms are still not clear. Here, we investigated if and to what extent HSL loss contributes to endoplasmic reticulum (ER) stress and adipose tissue inflammation in Hsl knockout mice. Furthermore, we were interested in how impaired PPARγ signaling affects the development of inflammation in epididymal white adipose tissue (eWAT) and inguinal white adipose tissue (iWAT) of Hsl knockout mice and if DAG and ceramide accumulation contribute to adipose tissue inflammation and ER stress. Ultrastructural analysis showed a markedly dilated ER in both eWAT and iWAT upon loss of HSL. In addition, Hsl knockout mice exhibited macrophage infiltration and increased F4/80 mRNA expression, a marker of macrophage activation, in eWAT, but not in iWAT. We show that treatment with rosiglitazone, a PPARγ agonist, attenuated macrophage infiltration and ameliorated inflammation of eWAT, but expression of ER stress markers remained unchanged, as did DAG and ceramide levels in eWAT. Taken together, we show that HSL loss promoted ER stress in both eWAT and iWAT of Hsl knockout mice, but inflammation and macrophage infiltration occurred mainly in eWAT. Also, PPARγ activation reversed inflammation but not ER stress and DAG accumulation. These data indicate that neither reduction of DAG levels nor ER stress contribute to the reversal of eWAT inflammation in Hsl knockout mice.
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Hormone sensitive lipase ablation promotes bone regeneration. Biochim Biophys Acta Mol Basis Dis 2022; 1868:166449. [PMID: 35618183 DOI: 10.1016/j.bbadis.2022.166449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 04/08/2022] [Accepted: 05/13/2022] [Indexed: 02/07/2023]
Abstract
There is an inverse relationship between the differentiation of mesenchymal stem cells (MSCs) along either an adipocyte or osteoblast lineage, with lineage differentiation known to be mediated by transcription factors PPARγ and Runx2, respectively. Endogenous ligands for PPARγ are generated during the hydrolysis of triacylglycerols to fatty acids through the actions of lipases such as hormone sensitive lipase (HSL). To examine whether reduced production of endogenous PPARγ ligands would influence bone regeneration, we examined the effects of HSL knockout on fracture repair in mice using a tibial mono-cortical defect as a model. We found an improved rate of fracture repair in HSL-ko mice documented by serial μCT and bone histomorphometry compared to wild-type (WT) mice. Similarly, accelerated rates of bone regeneration were observed with a calvarial model where implantation of bone grafts from HSL-ko mice accelerated bone regeneration at the injury site. Further analysis revealed improved MSC differentiation down osteoblast and chondrocyte lineage with inhibition of HSL. MSC recruitment to the injury site was greater in HSL-ko mice than WT. Finally, we used single cell RNAseq to understand the osteoimmunological differences between WT and HSL-ko mice and found changes in the pre-osteoclast population. Our study shows HSL-ko mice as an interesting model to study improvements to bone injury repair. Furthermore, our study highlights the potential importance of pre-osteoclasts and osteoclasts in bone repair.
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Kim J, Lee M. RMR-Related DNAJC6 Expression Suppresses Adipogenesis in 3T3-L1 Cells. Cells 2022; 11:cells11081331. [PMID: 35456010 PMCID: PMC9031806 DOI: 10.3390/cells11081331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/10/2022] [Accepted: 03/29/2022] [Indexed: 02/04/2023] Open
Abstract
Obesity causes various complications such as type 2 diabetes, hypertension, fatty liver, cardiovascular diseases, and cancer. In a pilot GWAS study, we screened the DNAJC6 gene which is significantly related to the resting metabolic rate (RMR) in childhood obesity. With DNAJC6-overexpressed 3T3-L1 cells (TgHsp), we investigated the new obesity mechanism caused by an energy imbalance. After differentiation, lipid droplets (Oil red O staining) were not formed in TgHsp cells compared to the control. TgHsp preadipocyte fibroblast morphology was also not clearly observed in the cell morphology assay (DAPI/BODIPY). In TgHsp cells, the expression of PPARγ, C/EBPα, and aP2 (adipogenesis-related biomarkers) decreased 3-, 39-, and 200-fold, respectively. The expression of the adipokines leptin and adiponectin from adipose tissues also decreased 2.4- and 840-fold, respectively. In addition, the levels of pHSL(Ser563) and free glycerol, which are involved in lipolysis, were significantly lower in TgHsp cells than in the control. The reduction in insulin receptor expression in TgHsp cells suppressed insulin signaling systems such as AKT phosphorylation, and GLUT4 expression. Degradation of IRS-1 in 3T3-L1 adipocytes was caused by chronic exposure to insulin, but not TgHsp. Mitochondrial functions such as oxygen consumption and ATP production, as well as proton leak and UCP1 protein expression, decreased in TgHsp cells compared to the control. Moreover, autophagy was observed by increasing autophagosomal proteins, LC3, on Day 8 of differentiation in TgHsp cells. Through our first report on the DNAJC6 gene related to RMR, we found a new mechanism related to energy metabolism in obesity. DNAJC6 expression positively suppressed adipogenesis, leading to the subsequent resistance of lipolysis, adipokine expression, insulin signaling, and mitochondrial functions.
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Affiliation(s)
- Juhee Kim
- Department of Food & Nutrition, Sungshin Women’s University, Seoul 01133, Korea;
- Medical Research Institute, Kangbuk Samsung Hospital, Seoul 04514, Korea
| | - Myoungsook Lee
- Department of Food & Nutrition, Sungshin Women’s University, Seoul 01133, Korea;
- Research Institute of Obesity Sciences, Sungshin Women’s University, Kangbuk-ku, Seoul 01133, Korea
- Correspondence: ; Tel.: +82-2-920-7211
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Li Y, Li Z, Ngandiri DA, Llerins Perez M, Wolf A, Wang Y. The Molecular Brakes of Adipose Tissue Lipolysis. Front Physiol 2022; 13:826314. [PMID: 35283787 PMCID: PMC8907745 DOI: 10.3389/fphys.2022.826314] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/10/2022] [Indexed: 12/11/2022] Open
Abstract
Adaptation to changes in energy availability is pivotal for the survival of animals. Adipose tissue, the body’s largest reservoir of energy and a major source of metabolic fuel, exerts a buffering function for fluctuations in nutrient availability. This functional plasticity ranges from energy storage in the form of triglycerides during periods of excess energy intake to energy mobilization via lipolysis in the form of free fatty acids for other organs during states of energy demands. The subtle balance between energy storage and mobilization is important for whole-body energy homeostasis; its disruption has been implicated as contributing to the development of insulin resistance, type 2 diabetes and cancer cachexia. As a result, adipocyte lipolysis is tightly regulated by complex regulatory mechanisms involving lipases and hormonal and biochemical signals that have opposing effects. In thermogenic brown and brite adipocytes, lipolysis stimulation is the canonical way for the activation of non-shivering thermogenesis. Lipolysis proceeds in an orderly and delicately regulated manner, with stimulation through cell-surface receptors via neurotransmitters, hormones, and autocrine/paracrine factors that activate various intracellular signal transduction pathways and increase kinase activity. The subsequent phosphorylation of perilipins, lipases, and cofactors initiates the translocation of key lipases from the cytoplasm to lipid droplets and enables protein-protein interactions to assemble the lipolytic machinery on the scaffolding perilipins at the surface of lipid droplets. Although activation of lipolysis has been well studied, the feedback fine-tuning is less well appreciated. This review focuses on the molecular brakes of lipolysis and discusses some of the divergent fine-tuning strategies in the negative feedback regulation of lipolysis, including delicate negative feedback loops, intermediary lipid metabolites-mediated allosteric regulation and dynamic protein–protein interactions. As aberrant adipocyte lipolysis is involved in various metabolic diseases and releasing the brakes on lipolysis in thermogenic adipocytes may activate thermogenesis, targeting adipocyte lipolysis is thus of therapeutic interest.
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Activation of Cx43 Hemichannels Induces the Generation of Ca 2+ Oscillations in White Adipocytes and Stimulates Lipolysis. Int J Mol Sci 2021; 22:ijms22158095. [PMID: 34360859 PMCID: PMC8347185 DOI: 10.3390/ijms22158095] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 12/11/2022] Open
Abstract
The aim of the study was to investigate the mechanisms of Ca2+ oscillation generation upon activation of connexin-43 and regulation of the lipolysis/lipogenesis balance in white adipocytes through vesicular ATP release. With fluorescence microscopy it was revealed that a decrease in the concentration of extracellular calcium ([Ca2+]ex) results in two types of Ca2+ responses in white adipocytes: Ca2+ oscillations and transient Ca2+ signals. It was found that activation of the connexin half-channels is involved in the generation of Ca2+ oscillations, since the blockers of the connexin hemichannels-carbenoxolone, octanol, proadifen and Gap26-as well as Cx43 gene knockdown led to complete suppression of these signals. The activation of Cx43 in response to the reduction of [Ca2+]ex was confirmed by TIRF microscopy. It was shown that in response to the activation of Cx43, ATP-containing vesicles were released from the adipocytes. This process was suppressed by knockdown of the Cx43 gene and by bafilomycin A1, an inhibitor of vacuolar ATPase. At the level of intracellular signaling, the generation of Ca2+ oscillations in white adipocytes in response to a decrease in [Ca2+]ex occurred due to the mobilization of the Ca2+ ions from the thapsigargin-sensitive Ca2+ pool of IP3R as a result of activation of the purinergic P2Y1 receptors and phosphoinositide signaling pathway. After activation of Cx43 and generation of the Ca2+ oscillations, changes in the expression levels of key genes and their encoding proteins involved in the regulation of lipolysis were observed in white adipocytes. This effect was accompanied by a decrease in the number of adipocytes containing lipid droplets, while inhibition or knockdown of Cx43 led to inhibition of lipolysis and accumulation of lipid droplets. In this study, we investigated the mechanism of Ca2+ oscillation generation in white adipocytes in response to a decrease in the concentration of Ca2+ ions in the external environment and established an interplay between periodic Ca2+ modes and the regulation of the lipolysis/lipogenesis balance.
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Pajed L, Taschler U, Tilp A, Hofer P, Kotzbeck P, Kolleritsch S, Radner FPW, Pototschnig I, Wagner C, Schratter M, Eder S, Huetter S, Schreiber R, Haemmerle G, Eichmann TO, Schweiger M, Hoefler G, Kershaw EE, Lass A, Schoiswohl G. Advanced lipodystrophy reverses fatty liver in mice lacking adipocyte hormone-sensitive lipase. Commun Biol 2021; 4:323. [PMID: 33692445 PMCID: PMC7946939 DOI: 10.1038/s42003-021-01858-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 02/16/2021] [Indexed: 11/09/2022] Open
Abstract
Modulation of adipocyte lipolysis represents an attractive approach to treat metabolic diseases. Lipolysis mainly depends on two enzymes: adipose triglyceride lipase and hormone-sensitive lipase (HSL). Here, we investigated the short- and long-term impact of adipocyte HSL on energy homeostasis using adipocyte-specific HSL knockout (AHKO) mice. AHKO mice fed high-fat-diet (HFD) progressively developed lipodystrophy accompanied by excessive hepatic lipid accumulation. The increased hepatic triglyceride deposition was due to induced de novo lipogenesis driven by increased fatty acid release from adipose tissue during refeeding related to defective insulin signaling in adipose tissue. Remarkably, the fatty liver of HFD-fed AHKO mice reversed with advanced age. The reversal of fatty liver coincided with a pronounced lipodystrophic phenotype leading to blunted lipolytic activity in adipose tissue. Overall, we demonstrate that impaired adipocyte HSL-mediated lipolysis affects systemic energy homeostasis in AHKO mice, whereby with older age, these mice reverse their fatty liver despite advanced lipodystrophy.
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Affiliation(s)
- Laura Pajed
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Ulrike Taschler
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Anna Tilp
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Peter Hofer
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Petra Kotzbeck
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, Graz, Austria
| | | | - Franz P W Radner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | | | - Carina Wagner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | | | - Sandra Eder
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Sabrina Huetter
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Guenter Haemmerle
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Thomas O Eichmann
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
- Center for Explorative Lipidomics, BioTechMed-Graz, Graz, Austria
| | - Martina Schweiger
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Gerald Hoefler
- Diagnostic & Research Institute of Pathology, Medical University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Erin E Kershaw
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Achim Lass
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Gabriele Schoiswohl
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.
- Department of Pharmacology and Toxicology, University of Graz, Graz, Austria.
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Tyrosol May Prevent Obesity by Inhibiting Adipogenesis in 3T3-L1 Preadipocytes. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:4794780. [PMID: 33376578 PMCID: PMC7746459 DOI: 10.1155/2020/4794780] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/08/2020] [Accepted: 11/19/2020] [Indexed: 02/07/2023]
Abstract
Tyrosol (TR), a major polyphenol found in extra virgin olive oil (EVOO), exerts several antioxidant effects. However, only scarce evidences are present regarding its activity on adipocytes and obesity. This study evaluated the role of TR in adipogenesis. Murine 3T3-L1 preadipocytes were incubated with TR (300 and 500 μM), and TR administration inhibited adipogenesis by downregulation of several adipogenic factors (leptin and aP2) and transcription factors (C/EBPα, PPARγ, SREBP1c, and Glut4) and by modulation of the histone deacetylase sirtuin 1. After complete differentiation, adipocytes treated with 300 and 500 μM TR showed a reduction of 20% and 30% in lipid droplets, respectively. Intracellular triglycerides were significantly reduced after TR treatment (p < 0.05). Mature adipocytes treated with TR at 300 and 500 μM showed a marked decrease in the inflammatory state and oxidative stress as shown by the modulation of specific biomarkers (TNF, IL6, ROS, and SOD2). TR treatment also acted on the early stage of differentiation by reducing cell proliferation (~40%) and inducing cell cycle arrest during Mitotic Expansion Clonal (first 48 h of differentiation), as shown by the increase in both S1 phase and p21 protein expression. We also showed that TR induced lipolysis by activating the AMPK-ATGL-HSL pathway. In conclusion, we provided evidence that TR reduces 3T3-L1 differentiation through downregulation of adipogenic proteins, inflammation, and oxidative stress. Moreover, TR may trigger adipose tissue browning throughout the induction of the AMPK-ATGL-UCP1 pathway and, subsequently, may have promise as a potential therapeutic agent for the treatment and prevention of obesity.
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11
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Adipocyte lipolysis: from molecular mechanisms of regulation to disease and therapeutics. Biochem J 2020; 477:985-1008. [PMID: 32168372 DOI: 10.1042/bcj20190468] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/19/2020] [Accepted: 02/26/2020] [Indexed: 12/20/2022]
Abstract
Fatty acids (FAs) are stored safely in the form of triacylglycerol (TAG) in lipid droplet (LD) organelles by professional storage cells called adipocytes. These lipids are mobilized during adipocyte lipolysis, the fundamental process of hydrolyzing TAG to FAs for internal or systemic energy use. Our understanding of adipocyte lipolysis has greatly increased over the past 50 years from a basic enzymatic process to a dynamic regulatory one, involving the assembly and disassembly of protein complexes on the surface of LDs. These dynamic interactions are regulated by hormonal signals such as catecholamines and insulin which have opposing effects on lipolysis. Upon stimulation, patatin-like phospholipase domain containing 2 (PNPLA2)/adipocyte triglyceride lipase (ATGL), the rate limiting enzyme for TAG hydrolysis, is activated by the interaction with its co-activator, alpha/beta hydrolase domain-containing protein 5 (ABHD5), which is normally bound to perilipin 1 (PLIN1). Recently identified negative regulators of lipolysis include G0/G1 switch gene 2 (G0S2) and PNPLA3 which interact with PNPLA2 and ABHD5, respectively. This review focuses on the dynamic protein-protein interactions involved in lipolysis and discusses some of the emerging concepts in the control of lipolysis that include allosteric regulation and protein turnover. Furthermore, recent research demonstrates that many of the proteins involved in adipocyte lipolysis are multifunctional enzymes and that lipolysis can mediate homeostatic metabolic signals at both the cellular and whole-body level to promote inter-organ communication. Finally, adipocyte lipolysis is involved in various diseases such as cancer, type 2 diabetes and fatty liver disease, and targeting adipocyte lipolysis is of therapeutic interest.
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Boscaini S, Cabrera‐Rubio R, Nychyk O, Roger Speakman J, Francis Cryan J, David Cotter P, Nilaweera KN. Age- and duration-dependent effects of whey protein on high-fat diet-induced changes in body weight, lipid metabolism, and gut microbiota in mice. Physiol Rep 2020; 8:e14523. [PMID: 32748559 PMCID: PMC7399378 DOI: 10.14814/phy2.14523] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/01/2020] [Accepted: 07/03/2020] [Indexed: 02/07/2023] Open
Abstract
Bovine whey protein has been demonstrated to exert a positive effect on energy balance, lipid metabolism, and nutrient absorption. Additionally, it affects gut microbiota configuration. Thus, whey protein is considered as good dietary candidate to prevent or ameliorate metabolic diseases, such as obesity. However, the relationship that links energy balance, metabolism, and intestinal microbial population mediated by whey protein intake remains poorly understood. In this study, we investigated the beneficial effects attributed to whey protein in the context of high-fat diet (HFD) in mice at two different ages, with short or longer durations of whey protein supplementation. Here, a 5-week dietary intervention with HFD in combination with either whey protein isolate (WPI) or the control nonwhey milk protein casein (CAS) was performed using 5-week or 10-week-old C57BL/6J mice. Notably, the younger mice had no prior history of ingestion of WPI, while older mice did. 5-week-old HFD-WPI-fed mice showed a decrease in weight gain and changes in the expression of genes within the epidydimal white adipose tissue including those encoding leptin, inflammatory marker CD68, fasting-induced adipose factor FIAF and enzymes involved in fatty acids catabolism, relative to HFD-CAS-fed mice. Differences in β-diversity and higher proportions of Lactobacillus murinus, and related functions, were evident within the gut microbiota of HFD-WPI mice. However, none of these changes were observed in mice that started the HFD dietary intervention at 10-weeks-old, with an extended period of WPI supplementation. These results suggest that the effect of whey protein on mouse body weight, adipose tissue, and intestinal parameters depends on diet duration and stage of life during which the diet is provided. In some instances, WPI influences gut microbiota composition and functional potential, which might orchestrate observed metabolic and physiological modifications.
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Affiliation(s)
- Serena Boscaini
- Food Biosciences DepartmentTeagasc Food Research Centre, MooreparkFermoyIreland
- APC Microbiome IrelandUniversity College CorkCorkIreland
- Department of Anatomy and NeuroscienceUniversity College CorkCorkIreland
| | - Raul Cabrera‐Rubio
- Food Biosciences DepartmentTeagasc Food Research Centre, MooreparkFermoyIreland
- APC Microbiome IrelandUniversity College CorkCorkIreland
| | - Oleksandr Nychyk
- Food Biosciences DepartmentTeagasc Food Research Centre, MooreparkFermoyIreland
| | - John Roger Speakman
- State Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
- Institute of Biological and Environmental SciencesUniversity of AberdeenAberdeenScotland
| | - John Francis Cryan
- APC Microbiome IrelandUniversity College CorkCorkIreland
- Department of Anatomy and NeuroscienceUniversity College CorkCorkIreland
| | - Paul David Cotter
- Food Biosciences DepartmentTeagasc Food Research Centre, MooreparkFermoyIreland
- APC Microbiome IrelandUniversity College CorkCorkIreland
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13
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Asano M, Nakano F, Nakatsukasa E, Tsuduki T. The 1975 type Japanese diet improves the gut microbial flora and inhibits visceral fat accumulation in mice. Biosci Biotechnol Biochem 2020; 84:1475-1485. [PMID: 32255390 DOI: 10.1080/09168451.2020.1747973] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In this study, the 1975 type Japanese diet was prepared and its effects and related mechanism were examined in mice. Mice were assigned to three experimental groups, the CD group fed a control diet, the MD group fed a modern Japanese diet (MD), and the JD group fed the 1975 type Japanese diet (JD) for 4 weeks. MD and JD were low protein, high fat, and high carbohydrate diets compared to the CD. Total white adipose tissue weights were significantly increased in the MD group compared to those in the CD group and were decreased in the JD group compared to those in the MD group. In the JD group, adipocyte hypertrophy was inhibited and Hsl mRNA expression was enhanced in epididymal adipose tissue and the number of bacteria associated with the production of short chain fatty acids was increased. Therefore, the JD inhibits lipid accumulation in white adipose tissue. ABBREVIATIONS Actb: β-actin; ALT: alanine aminotransferase; ANOVA: analyses of variance; AST: aspartate aminotransferase; Fas: fatty acid synthase; G6pdx: glucose 6-phosphate dehydrogenase; HE: hematoxylin and eosin; HOMA-IR: Homeostatic model assessment for insulin resistance; Hsl: hormone-sensitive lipase; JD: 1975 type Japanese diet; Leptin: leptin; MD: modern Japanese diet; Me: malic enzyme; NEFA: non-esterified fatty acids; PL: phospholipids; Pparδ: peroxisome proliferator-activated receptor delta; Pparγ: peroxisome proliferator-activated receptor gamma; qRT-PCR: quantitative reverse transcriptase polymerase chain reaction; SAMP8: senescence-accelerated prone 8; SEM: standard error of the mean; Srebp1c: Sterol regulatory element binding protein 1c; TBARS: thiobarbituric acid reactive substance; TC: total cholesterol; TG: Triacylglycerol; V3: variable regions 3.
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Affiliation(s)
- Masaki Asano
- Laboratory of Food and Biomolecular Science, Graduate School of Agriculture, Tohoku University , Sendai, Japan
| | - Fumika Nakano
- Laboratory of Food and Biomolecular Science, Graduate School of Agriculture, Tohoku University , Sendai, Japan
| | - Eriko Nakatsukasa
- Laboratory of Food and Biomolecular Science, Graduate School of Agriculture, Tohoku University , Sendai, Japan
| | - Tsuyoshi Tsuduki
- Laboratory of Food and Biomolecular Science, Graduate School of Agriculture, Tohoku University , Sendai, Japan
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14
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Rosas-Ballina M, Guan XL, Schmidt A, Bumann D. Classical Activation of Macrophages Leads to Lipid Droplet Formation Without de novo Fatty Acid Synthesis. Front Immunol 2020; 11:131. [PMID: 32132994 PMCID: PMC7040478 DOI: 10.3389/fimmu.2020.00131] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 01/17/2020] [Indexed: 01/17/2023] Open
Abstract
Altered lipid metabolism in macrophages is associated with various important inflammatory conditions. Although lipid metabolism is an important target for therapeutic intervention, the metabolic requirement involved in lipid accumulation during pro-inflammatory activation of macrophages remains incompletely characterized. We show here that macrophage activation with IFNγ results in increased aerobic glycolysis, iNOS-dependent inhibition of respiration, and accumulation of triacylglycerol. Surprisingly, metabolite tracing with 13C-labeled glucose revealed that the glucose contributed to the glycerol groups in triacylglycerol (TAG), rather than to de novo synthesis of fatty acids. This is in stark contrast to the otherwise similar metabolism of cancer cells, and previous results obtained in activated macrophages and dendritic cells. Our results establish a novel metabolic pathway whereby glucose provides glycerol to the headgroup of TAG during classical macrophage activation.
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Affiliation(s)
| | - Xue Li Guan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Alexander Schmidt
- Proteomics Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Dirk Bumann
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
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15
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Song L, Zhou H, Yu W, Ding X, Yang L, Wu J, Song C. Effects of Phytosterol Ester on the Fatty Acid Profiles in Rats with Nonalcoholic Fatty Liver Disease. J Med Food 2020; 23:161-172. [PMID: 31913753 DOI: 10.1089/jmf.2019.4468] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Both serum and hepatic fatty acid (FA) compositions differ among nonalcoholic hepatic steatosis, nonalcoholic steatohepatitis, and healthy subjects. The severity of the above liver disease is closely associated with the concentration and composition of FAs. Our previous study found that phytosterol ester (PSE) could alleviate hepatic steatosis in nonalcoholic fatty liver disease rats. The aims of this work were to explore the effects of PSE (0.05/100 g·body weight) on FA profiles and the mRNA levels of FA metabolism-related genes. Compared with a high-fat diet alone group, PSE treatment significantly decreased hepatic saturated fatty acid levels (P < .05) and increased monounsaturated fatty acid (especially C16:1 n-7) levels in the liver, serum, and adipose tissue and polyunsaturated fatty acid levels in the serum and liver (P < .05) after 12 weeks of intervention. In particular, PSE treatment increased the level of C22:5 n-3, an FA that was negatively correlated with the degree of hepatic steatosis in the serum, liver, and adipose tissue. The increases in some unsaturated fatty acids are probably related to the upregulation of stearoyl-coenzyme A desaturase-1 and fatty acid desaturase-1.
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Affiliation(s)
- Lihua Song
- Department of Food Science and Technology, Bor S. Luh Food Safety Research Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Haiyue Zhou
- Department of Food Science and Technology, Bor S. Luh Food Safety Research Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Wenjuan Yu
- Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai, China
| | - Xinwen Ding
- Department of Food Science and Technology, Bor S. Luh Food Safety Research Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Li Yang
- Department of Food Science and Technology, Bor S. Luh Food Safety Research Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Jiayi Wu
- Department of Food Science and Technology, Bor S. Luh Food Safety Research Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Chenwei Song
- Department of Food Science and Technology, Bor S. Luh Food Safety Research Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
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16
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Mottillo EP, Zhang H, Yang A, Zhou L, Granneman JG. Genetically-encoded sensors to detect fatty acid production and trafficking. Mol Metab 2019; 29:55-64. [PMID: 31668392 PMCID: PMC6726923 DOI: 10.1016/j.molmet.2019.08.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/09/2019] [Accepted: 08/14/2019] [Indexed: 02/09/2023] Open
Abstract
OBJECTIVE Fatty acids are important for biological function; however, in excess, they can cause metabolic dysregulation. Methods to image and detect fatty acids in real time are lacking. Therefore, the current study examined the dynamics of fatty acid trafficking and signaling utilizing novel fluorescent and luminescent approaches. METHODS We generated fluorescent and luminescent-based genetically-encoded sensors based upon the ligand-dependent interaction between PPARα and SRC-1 to image and detect cellular dynamics of fatty acid trafficking. RESULTS The use of a fluorescent sensor demonstrates that fatty acids traffic rapidly from lipid droplets to the nucleus. Both major lipases ATGL and HSL contribute to fatty acid signaling from lipid droplet to nucleus, however, their dynamics differ. Furthermore, direct activation of lipolysis, independent of receptor-mediated signaling is sufficient to promote lipid droplet to nuclear trafficking of fatty acids. A luminescent-based sensor that reports intracellular fatty acid levels is amenable to high-throughput analysis. CONCLUSIONS Fatty acids traffic from lipid droplets to the nucleus within minutes of stimulated lipolysis. Genetically-encoded fluorescent and luminescent based sensors can be used to probe the dynamics of fatty acid trafficking and signaling.
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Affiliation(s)
- Emilio P Mottillo
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
| | - Huamei Zhang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Alexander Yang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Li Zhou
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - James G Granneman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
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17
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Jones PH, Deng B, Winkler J, Zirnheld AL, Ehringer S, Shetty V, Cox M, Nguyen H, Shen WJ, Huang TT, Wang E. Over-expression of miR-34c leads to early-life visceral fat accumulation and insulin resistance. Sci Rep 2019; 9:13844. [PMID: 31554925 PMCID: PMC6761099 DOI: 10.1038/s41598-019-50191-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 08/15/2019] [Indexed: 12/13/2022] Open
Abstract
Overweight children and adolescents are at high risk for adult and late life obesity. This report investigates some underlying mechanisms contributing to obesity during early life in an animal model. We generated a strain of transgenic mice, cU2, overexpressing human microRNA 34c, a microRNA functionally implicated in adipogenesis. Male and female cU2 mice exhibit significant weight gain, accompanied by marked increase in abdominal fat mass and metabolic abnormalities, including reduction of both glucose clearance rate and insulin sensitivity, as early as two months of age. Adipogenesis derailment at this early age is suggested by decreased expression of adiponectin, the fat mass and obesity-associated gene, and the adiponectin receptor R1, coupled with a reduction of the brown fat biomarker PAT2 and the adipogenesis inhibitor SIRT1. Notably, adiponectin is an important adipokine and an essential regulator of glucose and fatty acid homeostasis. cU2 mice may provide a crucial animal model for investigating the role of miR-34c in early onset insulin resistance and visceral fat mass increase, contributing to accelerated body weight gain and metabolic disorders. Intervention in this dysregulation may open a new preventive strategy to control early-life weight gain and abnormal insulin resistance, and thus prevalent adult and late life obesity.
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Affiliation(s)
| | - Brian Deng
- Palo Alto Veterans Institute for Research, Palo Alto, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | | | | | | | | | - Matthew Cox
- Advanced Genomic Technology, LLC, Louisville, KY, USA
| | - Huy Nguyen
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | - Wen-Jun Shen
- Department of Endocrinology, Stanford University School of Medicine, Stanford, CA, USA.,Geriatric Research, Education, and Clinical Center, VA Palo Alto Health Care System, Palo Alto, CA, USA
| | - Ting-Ting Huang
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA. .,Geriatric Research, Education, and Clinical Center, VA Palo Alto Health Care System, Palo Alto, CA, USA.
| | - Eugenia Wang
- Advanced Genomic Technology, LLC, Louisville, KY, USA
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18
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Zhang D, Bai J, Ma Z, Ma X, Cao X, Li F. Regulatory roles of adiponectin receptor 1 and 2 in sheep preadipocytes during adipocyte differentiation. ITALIAN JOURNAL OF ANIMAL SCIENCE 2019. [DOI: 10.1080/1828051x.2019.1568838] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Derong Zhang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
- Gansu Engineering Research Center for Animal Cell, Northwest Minzu University, Lanzhou, China
| | - Jialin Bai
- Gansu Engineering Research Center for Animal Cell, Northwest Minzu University, Lanzhou, China
| | - Zhongren Ma
- Gansu Engineering Research Center for Animal Cell, Northwest Minzu University, Lanzhou, China
| | - Xiaoxia Ma
- Gansu Engineering Research Center for Animal Cell, Northwest Minzu University, Lanzhou, China
| | - Xin Cao
- Experiment Center of Northwest Minzu University, Lanzhou, China
| | - Fadi Li
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
- College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
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19
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Of mice and men: The physiological role of adipose triglyceride lipase (ATGL). Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:880-899. [PMID: 30367950 PMCID: PMC6439276 DOI: 10.1016/j.bbalip.2018.10.008] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/18/2018] [Accepted: 10/19/2018] [Indexed: 12/12/2022]
Abstract
Adipose triglyceride lipase (ATGL) has been discovered 14 years ago and revised our view on intracellular triglyceride (TG) mobilization – a process termed lipolysis. ATGL initiates the hydrolysis of TGs to release fatty acids (FAs) that are crucial energy substrates, precursors for the synthesis of membrane lipids, and ligands of nuclear receptors. Thus, ATGL is a key enzyme in whole-body energy homeostasis. In this review, we give an update on how ATGL is regulated on the transcriptional and post-transcriptional level and how this affects the enzymes' activity in the context of neutral lipid catabolism. In depth, we highlight and discuss the numerous physiological functions of ATGL in lipid and energy metabolism. Over more than a decade, different genetic mouse models lacking or overexpressing ATGL in a cell- or tissue-specific manner have been generated and characterized. Moreover, pharmacological studies became available due to the development of a specific murine ATGL inhibitor (Atglistatin®). The identification of patients with mutations in the human gene encoding ATGL and their disease spectrum has underpinned the importance of ATGL in humans. Together, mouse models and human data have advanced our understanding of the physiological role of ATGL in lipid and energy metabolism in adipose and non-adipose tissues, and of the pathophysiological consequences of ATGL dysfunction in mice and men. Summary of mouse models with genetic or pharmacological manipulation of ATGL. Summary of patients with mutations in the human gene encoding ATGL. In depth discussion of the role of ATGL in numerous physiological processes in mice and men.
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20
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Porskjær Christensen L, Bahij El-Houri R. Development of an In Vitro Screening Platform for the Identification of Partial PPARγ Agonists as a Source for Antidiabetic Lead Compounds. Molecules 2018; 23:molecules23102431. [PMID: 30248999 PMCID: PMC6222920 DOI: 10.3390/molecules23102431] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 09/18/2018] [Accepted: 09/20/2018] [Indexed: 01/02/2023] Open
Abstract
Type 2 diabetes (T2D) is a metabolic disorder where insulin-sensitive tissues show reduced sensitivity towards insulin and a decreased glucose uptake (GU), which leads to hyperglycaemia. Peroxisome proliferator-activated receptor (PPAR)γ plays an important role in lipid and glucose homeostasis and is one of the targets in the discovery of drugs against T2D. Activation of PPARγ by agonists leads to a conformational change in the ligand-binding domain, a process that alters the transcription of several target genes involved in glucose and lipid metabolism. Depending on the ligands, they can induce different sets of genes that depends of their recruitment of coactivators. The activation of PPARγ by full agonists such as the thiazolidinediones leads to improved insulin sensitivity but also to severe side effects probably due to their behavior as full agonists. Partial PPARγ agonists are compounds with diminished agonist efficacy compared to full agonist that may exhibit the same antidiabetic effect as full agonists without inducing the same magnitude of side effects. In this review, we describe a screening platform for the identification of partial PPARγ agonists from plant extracts that could be promising lead compounds for the development of antidiabetic drugs. The screening platform includes a series of in vitro bioassays, such as GU in adipocytes, PPARγ-mediated transactivation, adipocyte differentiation and gene expression as well as in silico docking for partial PPARγ agonism.
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Affiliation(s)
- Lars Porskjær Christensen
- Department of Chemistry and Bioscience, Faculty of Engineering and Science, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg Ø, Denmark.
| | - Rime Bahij El-Houri
- Department of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
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21
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Xu M, Chang HH, Jung X, Moro A, Chou CEN, King J, Hines OJ, Sinnett-Smith J, Rozengurt E, Eibl G. Deficiency in hormone-sensitive lipase accelerates the development of pancreatic cancer in conditional KrasG12D mice. BMC Cancer 2018; 18:797. [PMID: 30086728 PMCID: PMC6081906 DOI: 10.1186/s12885-018-4713-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 07/31/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Hormone sensitive lipase (HSL) is a neutral lipase that preferentially catalyzes the hydrolysis of diacylglycerol contributing to triacylglycerol breakdown in the adipose tissue. HSL has been implicated to play a role in tumor cachexia, a debilitating syndrome characterized by progressive loss of adipose tissue. Consequently, pharmacological inhibitors of HSL have been proposed for the treatment of cancer-associated cachexia. In the present study we used the conditional KrasG12D (KC) mouse model of pancreatic ductal adenocarcinoma (PDAC) with a deficiency in HSL to determine the impact of HSL suppression on the development of PDAC. METHODS KC;Hsl+/+ and KC;Hsl-/- mice were fed standard rodent chow for 20 weeks. At sacrifice, the incidence of PDAC was determined and inflammation in the mesenteric adipose tissue and pancreas was assessed histologically and by immunofluorescence. To determine statistical significance, ANOVA and two-tailed Student's t-tests were performed. To compare PDAC incidence, a two-sided Fisher's exact test was used. RESULTS Compared to KC;Hsl+/+ mice, KC;Hsl-/- mice gained similar weight and displayed adipose tissue and pancreatic inflammation. In addition, KC;Hsl-/- mice had reduced levels of plasma insulin and leptin. Importantly, the increased adipose tissue and pancreatic inflammation was associated with a significant increase in PDAC incidence in KC;Hsl-/- mice. CONCLUSIONS HSL deficiency is associated with adipose tissue and pancreatic inflammation and accelerates PDAC development in the KC mouse model.
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Affiliation(s)
- Mu Xu
- Departments of Surgery, David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, CHS 72-236, Los Angeles, CA, 90095, USA
| | - Hui-Hua Chang
- Departments of Surgery, David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, CHS 72-236, Los Angeles, CA, 90095, USA.,CURE: Digestive Diseases Research Center, University of California at Los Angeles, Los Angeles, USA
| | - Xiaoman Jung
- Departments of Surgery, David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, CHS 72-236, Los Angeles, CA, 90095, USA
| | - Aune Moro
- Departments of Surgery, David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, CHS 72-236, Los Angeles, CA, 90095, USA
| | - Caroline Ei Ne Chou
- Departments of Surgery, David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, CHS 72-236, Los Angeles, CA, 90095, USA
| | - Jonathan King
- Departments of Surgery, David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, CHS 72-236, Los Angeles, CA, 90095, USA
| | - O Joe Hines
- Departments of Surgery, David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, CHS 72-236, Los Angeles, CA, 90095, USA
| | - James Sinnett-Smith
- Departments of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.,CURE: Digestive Diseases Research Center, University of California at Los Angeles, Los Angeles, USA
| | - Enrique Rozengurt
- Departments of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.,CURE: Digestive Diseases Research Center, University of California at Los Angeles, Los Angeles, USA
| | - Guido Eibl
- Departments of Surgery, David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, CHS 72-236, Los Angeles, CA, 90095, USA. .,CURE: Digestive Diseases Research Center, University of California at Los Angeles, Los Angeles, USA.
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22
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Kimmel AR, Sztalryd C. The Perilipins: Major Cytosolic Lipid Droplet-Associated Proteins and Their Roles in Cellular Lipid Storage, Mobilization, and Systemic Homeostasis. Annu Rev Nutr 2017; 36:471-509. [PMID: 27431369 DOI: 10.1146/annurev-nutr-071813-105410] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The discovery by Dr. Constantine Londos of perilipin 1, the major scaffold protein at the surface of cytosolic lipid droplets in adipocytes, marked a fundamental conceptual change in the understanding of lipolytic regulation. Focus then shifted from the enzymatic activation of lipases to substrate accessibility, mediated by perilipin-dependent protein sequestration and recruitment. Consequently, the lipid droplet became recognized as a unique, metabolically active cellular organelle and its surface as the active site for novel protein-protein interactions. A new area of investigation emerged, centered on lipid droplets' biology and their role in energy homeostasis. The perilipin family is of ancient origin and has expanded to include five mammalian genes and a growing list of evolutionarily conserved members. Universally, the perilipins modulate cellular lipid storage. This review provides a summary that connects the perilipins to both cellular and whole-body homeostasis.
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Affiliation(s)
- Alan R Kimmel
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, Maryland 20892;
| | - Carole Sztalryd
- The Geriatric Research Education and Clinical Center, Baltimore Veterans Affairs Medical Center, Baltimore, Maryland 21201.,Division of Endocrinology, Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland 21201;
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23
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Takanashi M, Taira Y, Okazaki S, Takase S, Kimura T, Li CC, Xu PF, Noda A, Sakata I, Kumagai H, Ikeda Y, Iizuka Y, Yahagi N, Shimano H, Osuga JI, Ishibashi S, Kadowaki T, Okazaki H. Role of Hormone-sensitive Lipase in Leptin-Promoted Fat Loss and Glucose Lowering. J Atheroscler Thromb 2017; 24:1105-1116. [PMID: 28413180 PMCID: PMC5684476 DOI: 10.5551/jat.39552] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Aim: Myriad biological effects of leptin may lead to broad therapeutic applications for various metabolic diseases, including diabetes and its complications; however, in contrast to its anorexic effect, the molecular mechanisms underlying adipopenic and glucose-lowering effects of leptin have not been fully understood. Here we aim to clarify the role of hormone-sensitive lipase (HSL) in leptin's action. Methods: Wild-type (WT) and HSL-deficient (HSLKO) mice were made hyperleptinemic by two commonly-used methods: adenovirus-mediated overexpression of leptin and continuous subcutaneous infusion of leptin by osmotic pumps. The amount of food intake, body weights, organ weights, and parameters of glucose and lipid metabolism were measured. Results: Hyperleptinemia equally suppressed the food intake in WT and HSLKO mice. On the other hand, leptin-mediated fat loss and glucose-lowering were significantly blunted in the absence of HSL when leptin was overexpressed by recombinant adenovirus carrying leptin. By osmotic pumps, the fat-losing and glucose-lowering effects of leptin were milder due to lower levels of hyperleptinemia; although the difference between WT and HSLKO mice did not reach statistical significance, HSLKO mice had a tendency to retain more fat than WT mice in the face of hyperleptinemia. Conclusions: We clarify for the first time the role of HSL in leptin's effect using a genetic model: leptin-promoted fat loss and glucose-lowering are at least in part mediated via HSL-mediated lipolysis. Further studies to define the pathophysiological role of adipocyte lipases in leptin action may lead to a new therapeutic approach to circumvent leptin resistance.
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Affiliation(s)
- Mikio Takanashi
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Yoshino Taira
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Sachiko Okazaki
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Satoru Takase
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Takeshi Kimura
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Cheng Cheng Li
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Peng Fei Xu
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Akari Noda
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Ichiro Sakata
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University
| | - Hidetoshi Kumagai
- Department of Cardiovascular Medicine, Graduate School of Medicine, The University of Tokyo
| | - Yuichi Ikeda
- Department of Cardiovascular Medicine, Graduate School of Medicine, The University of Tokyo
| | - Yoko Iizuka
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Naoya Yahagi
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Hitoshi Shimano
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Jun-Ichi Osuga
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University
| | - Shun Ishibashi
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University
| | - Takashi Kadowaki
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Hiroaki Okazaki
- Departments of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
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Kroon T, Baccega T, Olsén A, Gabrielsson J, Oakes ND. Nicotinic acid timed to feeding reverses tissue lipid accumulation and improves glucose control in obese Zucker rats[S]. J Lipid Res 2016; 58:31-41. [PMID: 27875257 DOI: 10.1194/jlr.m068395] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 10/17/2016] [Indexed: 12/23/2022] Open
Abstract
Nicotinic acid (NiAc) is a potent inhibitor of lipolysis, acutely reducing plasma free fatty acid (FFA) concentrations. However, a major FFA rebound is seen during rapid NiAc washout, and sustained exposure is associated with tolerance development, with FFAs returning to pretreatment levels. Our aim was to find a rational NiAc dosing regimen that preserves FFA lowering, sufficient to reverse nonadipose tissue lipid accumulation and improve metabolic control, in obese Zucker rats. We compared feeding-period versus fasting-period NiAc dosing for 5 days: 12 h subcutaneous infusion (programmable, implantable mini-pumps) terminated by gradual withdrawal. It was found that NiAc timed to feeding decreased triglycerides in liver (-47%; P < 0.01) and heart (-38%; P < 0.05) and reduced plasma fructosamine versus vehicle. During oral glucose tolerance test, plasma FFA levels were reduced with amelioration of hyperglycemia and hypertriglyceridemia. Furthermore, timing NiAc to feeding resulted in a general downregulation of de novo lipogenesis (DNL) genes in liver. By contrast, NiAc timed to fasting did not reduce tissue lipids, ameliorate glucose intolerance or dyslipidemia, or alter hepatic DNL genes. In conclusion, NiAc dosing regimen has a major impact on metabolic control in obese Zucker rats. Specifically, a well-defined NiAc exposure, timed to feeding periods, profoundly improves the metabolic phenotype of this animal model.
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Affiliation(s)
- Tobias Kroon
- Division of Pharmacology and Toxicology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden .,AstraZeneca R&D, CVMD iMed, Gothenburg, Sweden
| | | | - Arne Olsén
- AstraZeneca R&D, CVMD iMed, Gothenburg, Sweden
| | - Johan Gabrielsson
- Division of Pharmacology and Toxicology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Cocktail supplement with rosiglitazone: a novel inducer for chicken preadipocyte differentiation in vitro. Biosci Rep 2016; 36:BSR20160049. [PMID: 27638500 PMCID: PMC5293590 DOI: 10.1042/bsr20160049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Revised: 09/12/2016] [Accepted: 09/15/2016] [Indexed: 01/13/2023] Open
Abstract
Chicken preadipocytes cultured in cocktail supplement with rosiglitazone resulted in a marked increase in lipid droplet accumulation, glycerol-3-phosphate dehydrogenase (GPDH) activity and mRNA expression of adipocyte fatty acid-binding protein (aP2), G0/G1 switch gene 2 (G0S2), peroxisome proliferator-activated receptor γ (PPARγ) and lipolysis. The present study provides a novel induction method for in vitro chicken preadipocyte differentiation. The preadipocyte differentiation biological process involves a cascade of transcriptional events that culminates in the expression of peroxisome proliferator-activated receptor (PPAR) γ. The differentiation cocktail [insulin (INS), dexamethasone (DEX) and isobutylmethylxanthine (IBMX)] can induce preadipocyte differentiation in mammals, but it is insufficient for chicken (Gallus gallus) adipogenesis. Oleate can induce chicken preadipocyte differentiation, but these differentiated preadipocytes may not be fully functional. The objective of the current study was to evaluate whether chicken preadipocytes can be induced to mature adipocytes by a novel induction method using differentiation cocktail supplemented with PPARγ agonist(s). Chicken preadipocytes cultured in cocktail supplemented with rosiglitazone or troglitazone resulted in a marked increase in lipid droplet accumulation (P<0.05), glycerol-3-phosphate dehydrogenase (GPDH) activity (P<0.05), mRNA expression level of adipocyte fatty acid-binding protein (aP2; P<0.05), G0/G1 switch gene 2 (G0S2; P<0.05) and lipolysis (P<0.05). In addition, supplementation of the cocktail with rosiglitazone promoted PPARγ mRNA expression (P<0.05). In conclusion, our data indicated that chicken preadipocytes can be induced to mature adipocytes using differentiation cocktail supplemented with rosiglitazone. The results of the present study provide a novel induction method for in vitro chicken preadipocyte differentiation.
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PPARγ regulates exocrine pancreas lipase. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1921-1928. [PMID: 27663184 DOI: 10.1016/j.bbalip.2016.09.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 09/12/2016] [Accepted: 09/15/2016] [Indexed: 12/30/2022]
Abstract
AIM Pancreatic lipase (triacylglycerol lipase EC 3.1.1.3) is an essential enzyme in hydrolysis of dietary fat. Dietary fat, especially polyunsaturated fatty acids (PUFA), regulate pancreatic lipase (PNLIP); however, the molecular mechanism underlying this regulation is mostly unknown. As PUFA are known to regulate expression of proliferator-activated receptor gamma (PPARγ), and as we identified in-silico putative PPARγ binding sites within the putative PNLIP promoter sequence, we hypothesized that PUFA regulation of PNLIP might be mediated by PPARγ. MATERIALS AND METHODS We used in silico bioinformatics tools, reporter luciferase assay, PPARγ agonists and antagonists, PPARγ overexpression in exocrine pancreas AR42J and primary cells to study PPARγ regulation of PNLIP. RESULTS Using in silico bioinformatics tools we mapped PPARγ binding sites (PPRE) to the putative promoter region of PNLIP. Reporter luciferase assay in AR42J rat exocrine pancreas acinar cells transfected with various constructs of the putative PNLIP promoter showed that PNLIP transcription is significantly enhanced by PPARγ dose-dependently, reaching maximal levels with multi PPRE sites. This effect was significantly augmented in the presence of PPARγ agonists and reduced by PPARγ antagonists or mutagenesis abrogating PPRE sites. Over-expression of PPARγ significantly elevated PNLIP transcript and protein levels in AR42J cells and in primary pancreas cells. Moreover, PNLIP expression was up-regulated by PPARγ agonists (pioglitazone and 15dPGJ2) and significantly down-regulated by PPARγ antagonists in non-transfected rat exocrine pancreas AR42J cell line cells. CONCLUSION PPARγ transcriptionally regulates PNLIP gene expression. This transcript regulation resolves part of the missing link between dietary PUFA direct regulation of PNLIP.
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Yeganeh A, Taylor CG, Tworek L, Poole J, Zahradka P. Trans-10,cis-12 conjugated linoleic acid (CLA) interferes with lipid droplet accumulation during 3T3-L1 preadipocyte differentiation. Int J Biochem Cell Biol 2016; 76:39-50. [PMID: 27131602 DOI: 10.1016/j.biocel.2016.04.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 04/14/2016] [Accepted: 04/25/2016] [Indexed: 12/22/2022]
Abstract
In this study, we hypothesize that the biologically active isomers of conjugated linoleic acid (CLA), cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) CLA, have different effects on early and late stages 3T3-L1 preadipocyte differentiation. Both c9-t11 and t10-c12CLA stimulated early stage pre-adipocyte differentiation (day 2), while t10-c12CLA inhibited late differentiation (day 8) as determined by lipid droplet numbers and both perilipin-1 levels and phosphorylation state. At day 8, the adipokines adiponectin, chemerin and adipsin were all reduced in t10-c12CLA treated cells versus control cells. Immunofluorescence microscopy showed perilipin-1 was present solely on lipid droplets on day 8 in t10-c12 treated 3T3-L1 cells, whereas preilipin-1 was also located in the perinuclear region in control and c9-t11 treated cells. The t10-c12CLA isomer also decreased levels of hormone-sensitive lipase and inhibited lipolysis. These findings indicate that the decrease in lipid droplets caused by t10-c12CLA is the result of an inhibition of lipid droplet production during adipogenesis rather than a stimulation of lipolysis. Additionally, treatment with Gö6976 blocked the effect of t10-c12CLA on perilipin-1 phosphorylation, implicating PKCα in perilipin-1 phosphorylation, and thus a regulator of triglyceride catabolism. These data are supported by evidence that t10-c12CLA activated PKCα. These are the first data to show that CLA isomers can affect lipid droplet dynamics in adipocytes through PKCα.
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Affiliation(s)
- Azadeh Yeganeh
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, Winnipeg, Canada
| | - Carla G Taylor
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Canada; Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, Winnipeg, Canada
| | - Leslee Tworek
- Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, Winnipeg, Canada
| | - Jenna Poole
- Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, Winnipeg, Canada
| | - Peter Zahradka
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Canada; Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, Winnipeg, Canada.
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28
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Zhou P, Robles-Murguia M, Mathew D, Duffield GE. Impaired Thermogenesis and a Molecular Signature for Brown Adipose Tissue in Id2 Null Mice. J Diabetes Res 2016; 2016:6785948. [PMID: 27144179 PMCID: PMC4842059 DOI: 10.1155/2016/6785948] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 03/06/2016] [Accepted: 03/16/2016] [Indexed: 11/18/2022] Open
Abstract
Inhibitor of DNA binding 2 (ID2) is a helix-loop-helix transcriptional repressor rhythmically expressed in many adult tissues. Our previous studies have demonstrated that Id2 null mice have sex-specific elevated glucose uptake in brown adipose tissue (BAT). Here we further explored the role of Id2 in the regulation of core body temperature over the circadian cycle and the impact of Id2 deficiency on genes involved in insulin signaling and adipogenesis in BAT. We discovered a reduced core body temperature in Id2-/- mice. Moreover, in Id2-/- BAT, 30 genes including Irs1, PPARs, and PGC-1s were identified as differentially expressed in a sex-specific pattern. These data provide valuable insights into the impact of Id2 deficiency on energy homeostasis of mice in a sex-specific manner.
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Affiliation(s)
- Peng Zhou
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Maricela Robles-Murguia
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Deepa Mathew
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Giles E. Duffield
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA
- *Giles E. Duffield:
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Morigny P, Houssier M, Mouisel E, Langin D. Adipocyte lipolysis and insulin resistance. Biochimie 2015; 125:259-66. [PMID: 26542285 DOI: 10.1016/j.biochi.2015.10.024] [Citation(s) in RCA: 271] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 10/30/2015] [Indexed: 12/15/2022]
Abstract
Obesity-induced insulin resistance is a major risk factor for the development of type 2 diabetes. Basal fat cell lipolysis (i.e., fat cell triacylglycerol breakdown into fatty acids and glycerol in the absence of stimulatory factors) is elevated during obesity and is closely associated with insulin resistance. Inhibition of adipocyte lipolysis may therefore be a promising therapeutic strategy for treating insulin resistance and preventing obesity-associated type 2 diabetes. In this review, we explore the relationship between adipose lipolysis and insulin sensitivity. After providing an overview of the components of fat cell lipolytic machinery, we describe the hypotheses that may support the causality between lipolysis and insulin resistance. Excessive circulating fatty acids may ectopically accumulate in insulin-sensitive tissues and impair insulin action. Increased basal lipolysis may also modify the secretory profile of adipose tissue, influencing whole body insulin sensitivity. Finally, excessive fatty acid release may also worsen adipose tissue inflammation, a well-known parameter contributing to insulin resistance. Partial genetic or pharmacologic inhibition of fat cell lipases in mice as well as short term clinical trials using antilipolytic drugs in humans support the benefit of fat cell lipolysis inhibition on systemic insulin sensitivity and glucose metabolism, which occurs without an increase of fat mass. Modulation of fatty acid fluxes and, putatively, of fat cell secretory pattern may explain the amelioration of insulin sensitivity whereas changes in adipose tissue immune response do not seem involved.
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Affiliation(s)
- Pauline Morigny
- INSERM, UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, UMR1048, Paul Sabatier University, France
| | - Marianne Houssier
- INSERM, UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, UMR1048, Paul Sabatier University, France
| | - Etienne Mouisel
- INSERM, UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, UMR1048, Paul Sabatier University, France
| | - Dominique Langin
- INSERM, UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, UMR1048, Paul Sabatier University, France; Toulouse University Hospitals, Department of Clinical Biochemistry, Toulouse, France.
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30
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Hypophagia and metabolic adaptations in mice with defective ATGL-mediated lipolysis cause resistance to HFD-induced obesity. Proc Natl Acad Sci U S A 2015; 112:13850-5. [PMID: 26508640 DOI: 10.1073/pnas.1516004112] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adipose triglyceride lipase (ATGL) initiates intracellular triglyceride (TG) catabolism. In humans, ATGL deficiency causes neutral lipid storage disease with myopathy (NLSDM) characterized by a systemic TG accumulation. Mice with a genetic deletion of ATGL (AKO) also accumulate TG in many tissues. However, neither NLSDM patients nor AKO mice are exceedingly obese. This phenotype is unexpected considering the importance of the enzyme for TG catabolism in white adipose tissue (WAT). In this study, we identified the counteracting mechanisms that prevent excessive obesity in the absence of ATGL. We used "healthy" AKO mice expressing ATGL exclusively in cardiomyocytes (AKO/cTg) to circumvent the cardiomyopathy and premature lethality observed in AKO mice. AKO/cTg mice were protected from high-fat diet (HFD)-induced obesity despite complete ATGL deficiency in WAT and normal adipocyte differentiation. AKO/cTg mice were highly insulin sensitive under hyperinsulinemic-euglycemic clamp conditions, eliminating insulin insensitivity as a possible protective mechanism. Instead, reduced food intake and altered signaling by peroxisome proliferator-activated receptor-gamma (PPAR-γ) and sterol regulatory element binding protein-1c in WAT accounted for the phenotype. These adaptations led to reduced lipid synthesis and storage in WAT of HFD-fed AKO/cTg mice. Treatment with the PPAR-γ agonist rosiglitazone reversed the phenotype. These results argue for the existence of an adaptive interdependence between lipolysis and lipid synthesis. Pharmacological inhibition of ATGL may prove useful to prevent HFD-induced obesity and insulin resistance.
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31
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Taschler U, Schreiber R, Chitraju C, Grabner GF, Romauch M, Wolinski H, Haemmerle G, Breinbauer R, Zechner R, Lass A, Zimmermann R. Adipose triglyceride lipase is involved in the mobilization of triglyceride and retinoid stores of hepatic stellate cells. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:937-45. [PMID: 25732851 PMCID: PMC4408194 DOI: 10.1016/j.bbalip.2015.02.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 02/05/2015] [Accepted: 02/22/2015] [Indexed: 01/04/2023]
Abstract
Hepatic stellate cells (HSCs) store triglycerides (TGs) and retinyl ester (RE) in cytosolic lipid droplets. RE stores are degraded following retinoid starvation or in response to pathogenic stimuli resulting in HSC activation. At present, the major enzymes catalyzing lipid degradation in HSCs are unknown. In this study, we investigated whether adipose triglyceride lipase (ATGL) is involved in RE catabolism of HSCs. Additionally, we compared the effects of ATGL deficiency and hormone-sensitive lipase (HSL) deficiency, a known RE hydrolase (REH), on RE stores in liver and adipose tissue. We show that ATGL degrades RE even in the presence of TGs, implicating that these substrates compete for ATGL binding. REH activity was stimulated and inhibited by comparative gene identification-58 and G0/G1 switch gene-2, respectively, the physiological regulators of ATGL activity. In cultured primary murine HSCs, pharmacological inhibition of ATGL, but not HSL, increased RE accumulation. In mice globally lacking ATGL or HSL, RE contents in white adipose tissue were decreased or increased, respectively, while plasma retinol and liver RE levels remained unchanged. In conclusion, our study shows that ATGL acts as REH in HSCs promoting the degradation of RE stores in addition to its established function as TG lipase. HSL is the predominant REH in adipocytes but does not affect lipid mobilization in HSCs. ATGL possesses retinyl ester and triacylglycerol hydrolase activity. The lack of ATGL activity causes increased triacylglycerol and retinyl ester storage in hepatic stellate cells. ATGL acts as retinyl ester and triacylglycerol lipase in hepatic stellate cells.
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Affiliation(s)
- Ulrike Taschler
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria
| | | | - Gernot F Grabner
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria
| | - Matthias Romauch
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria
| | - Heimo Wolinski
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria
| | - Guenter Haemmerle
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria
| | - Rolf Breinbauer
- Institute of Organic Chemistry, Graz University of Technology, Graz 8010, Austria
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria
| | - Achim Lass
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria.
| | - Robert Zimmermann
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria.
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Agarwal N, Balasubramanyam A. Viral mechanisms of adipose dysfunction: lessons from HIV-1 Vpr. Adipocyte 2015; 4:55-9. [PMID: 26167403 DOI: 10.4161/adip.29852] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 07/07/2014] [Accepted: 07/07/2014] [Indexed: 01/02/2023] Open
Abstract
HIV-associated lipodystrophy is a heterogeneous, evolving condition associated with fundamental defects in adipose tissue differentiation, turnover and function. Although many antiretroviral drugs can affect adipose tissues adversely, clinical evidence suggests that factors associated with the virus per se could play a role. We have focused on the possibility that an HIV accessory protein, viral protein R (Vpr) could dysregulate metabolically critical transcription factors to cause the adipose dysfunction. In a recent study published in Science Translational Medicine, we utilized 2 animal models to show that Vpr, produced in tissues that sequester HIV after antiretroviral therapy, can act in a paracrine or endocrine fashion to disrupt adipocyte differentiation and function by inhibiting PPARγ target gene expression and activating glucocorticoid target gene expression. The phenotypic consequences included many features typical of the human syndrome, including accelerated lipolysis, increased macrophage infiltration in adipose tissue, diminished size of white adipose depots and hepatic steatosis. In this commentary, we summarize the background, results, and implications of these studies, and raise important questions for future investigation. More broadly, these studies suggest that chronic viral infections may be a causative factor in the pathogenesis of some forms of lipid metabolic disease, insulin resistance, and diabetes.
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33
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El-Houri RB, Kotowska D, Christensen KB, Bhattacharya S, Oksbjerg N, Wolber G, Kristiansen K, Christensen LP. Polyacetylenes from carrots (Daucus carota) improve glucose uptake in vitro in adipocytes and myotubes. Food Funct 2015; 6:2135-44. [DOI: 10.1039/c5fo00223k] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Falcarinol and falcarindiol isolated from a carrot extract stimulate glucose uptake in adipocytes and myotubes, and may represent scaffolds for novel partial PPARγ agonists.
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Affiliation(s)
- Rime B. El-Houri
- Department of Chemical Engineering
- Biotechnology and Environmental Technology
- University of Southern Denmark
- 5230 Odense M
- Denmark
| | - Dorota Kotowska
- Department of Biology
- University of Copenhagen
- 2200 Copenhagen N
- Denmark
| | - Kathrine B. Christensen
- Department of Chemical Engineering
- Biotechnology and Environmental Technology
- University of Southern Denmark
- 5230 Odense M
- Denmark
| | | | - Niels Oksbjerg
- Department of Food Science
- Aarhus University
- 8830 Tjele
- Denmark
| | - Gerhard Wolber
- Computer-Aided Drug Design
- Institute of Pharmacy
- Medicinal and Pharmaceutical Chemistry
- Freie Universität Berlin
- 14195 Berlin
| | | | - Lars P. Christensen
- Department of Chemical Engineering
- Biotechnology and Environmental Technology
- University of Southern Denmark
- 5230 Odense M
- Denmark
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Fuchs CD, Claudel T, Trauner M. Role of metabolic lipases and lipolytic metabolites in the pathogenesis of NAFLD. Trends Endocrinol Metab 2014; 25:576-85. [PMID: 25183341 DOI: 10.1016/j.tem.2014.08.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 08/06/2014] [Accepted: 08/06/2014] [Indexed: 12/12/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most frequent chronic liver disease in Western countries, ranging from simple steatosis to steatohepatitis, cirrhosis, and hepatocellular cancer. Although the mechanisms underlying disease progression are incompletely understood, lipotoxic events in the liver resulting in inflammation and fibrosis appear to be central. Free fatty acids and their metabolites are potentially lipotoxic mediators triggering liver injury, suggesting a central role for metabolic lipases. These enzymes are major players in lipid partitioning between tissues and within cells, and provide ligands for nuclear receptors (NRs). We discuss the potential role of intracellular lipases and their lipolytic products in NAFLD. Because tissue-specific modulation of lipases is currently impossible, targeting NRs with ligands may open novel therapeutic perspectives.
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Affiliation(s)
- Claudia D Fuchs
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Thierry Claudel
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Michael Trauner
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
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35
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Albert JS, Yerges-Armstrong LM, Horenstein RB, Pollin TI, Sreenivasan UT, Chai S, Blaner WS, Snitker S, O'Connell JR, Gong DW, Breyer RJ, Ryan AS, McLenithan JC, Shuldiner AR, Sztalryd C, Damcott CM. Null mutation in hormone-sensitive lipase gene and risk of type 2 diabetes. N Engl J Med 2014; 370:2307-2315. [PMID: 24848981 PMCID: PMC4096982 DOI: 10.1056/nejmoa1315496] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Lipolysis regulates energy homeostasis through the hydrolysis of intracellular triglycerides and the release of fatty acids for use as energy substrates or lipid mediators in cellular processes. Genes encoding proteins that regulate energy homeostasis through lipolysis are thus likely to play an important role in determining susceptibility to metabolic disorders. METHODS We sequenced 12 lipolytic-pathway genes in Old Order Amish participants whose fasting serum triglyceride levels were at the extremes of the distribution and identified a novel 19-bp frameshift deletion in exon 9 of LIPE, encoding hormone-sensitive lipase (HSL), a key enzyme for lipolysis. We genotyped the deletion in DNA from 2738 Amish participants and performed association analyses to determine the effects of the deletion on metabolic traits. We also obtained biopsy specimens of abdominal subcutaneous adipose tissue from 2 study participants who were homozygous for the deletion (DD genotype), 10 who were heterozygous (ID genotype), and 7 who were noncarriers (II genotype) for assessment of adipose histologic characteristics, lipolysis, enzyme activity, cytokine release, and messenger RNA (mRNA) and protein levels. RESULTS Carriers of the mutation had dyslipidemia, hepatic steatosis, systemic insulin resistance, and diabetes. In adipose tissue from study participants with the DD genotype, the mutation resulted in the absence of HSL protein, small adipocytes, impaired lipolysis, insulin resistance, and inflammation. Transcription factors responsive to peroxisome-proliferator-activated receptor γ (PPAR-γ) and downstream target genes were down-regulated in adipose tissue from participants with the DD genotype, altering the regulation of pathways influencing adipogenesis, insulin sensitivity, and lipid metabolism. CONCLUSIONS These findings indicate the physiological significance of HSL in adipocyte function and the regulation of systemic lipid and glucose homeostasis and underscore the severe metabolic consequences of impaired lipolysis. (Funded by the National Institutes of Health and others).
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Affiliation(s)
- Jessica S Albert
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Laura M Yerges-Armstrong
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Richard B Horenstein
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Toni I Pollin
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Urmila T Sreenivasan
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Sumbul Chai
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - William S Blaner
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Soren Snitker
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Jeffrey R O'Connell
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Da-Wei Gong
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Richard J Breyer
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Alice S Ryan
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - John C McLenithan
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Alan R Shuldiner
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Carole Sztalryd
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
| | - Coleen M Damcott
- Program for Personalized and Genomic Medicine and Department of Medicine, University of Maryland School of Medicine (J.S.A., L.M.Y.-A., R.B.H., T.I.P., U.T.S., S.C., S.S., J.R.O., D.-W.G., J.C.M., A.R.S., C.S., C.M.D.), and the Geriatrics Research and Education Clinical Center (D.-W.G., A.S.R., A.R.S., C.S.), Department of Radiology and Nuclear Medicine (R.J.B.), and the Veterans Affairs (VA) Research Service, Department of Medicine, Division of Gerontology and Geriatric Medicine (A.S.R.), Baltimore VA Medical Center - all in Baltimore; and the Department of Medicine, Columbia University, New York (W.S.B.)
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Perilipins: lipid droplet coat proteins adapted for tissue-specific energy storage and utilization, and lipid cytoprotection. Biochimie 2013; 96:96-101. [PMID: 24036367 DOI: 10.1016/j.biochi.2013.08.026] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 08/28/2013] [Indexed: 12/18/2022]
Abstract
Cytosolic lipid storage droplets are primary functional organelles that regulate cellular lipid metabolism and homeostasis. Paradoxically, excess lipid stores are linked to both adaptive (fasting and chronic exercise) and mal-adaptive (obesity and related health complications) conditions. Thus, collective metabolic and physiological processes must balance lipid storage and utilization with prevention of lipocytotoxicity and compounding tissue dysfunctions, urging the need to further define the connection of mammalian lipid droplet function and lipid homeostasis. The perilipins are a multi-protein family that targets lipid droplet surfaces and regulates lipid storage and hydrolysis. Study of perilipin functions has provided insight into the physiological roles of cytosolic lipid droplets and their relationship with obesity-related pathologies. Here, we review the current knowledge of the multiple perilipin proteins in regulating tissue-specific lipid droplets and associations with tissue and systemic energetics.
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Rohm M, Sommerfeld A, Strzoda D, Jones A, Sijmonsma TP, Rudofsky G, Wolfrum C, Sticht C, Gretz N, Zeyda M, Leitner L, Nawroth PP, Stulnig TM, Berriel Diaz M, Vegiopoulos A, Herzig S. Transcriptional cofactor TBLR1 controls lipid mobilization in white adipose tissue. Cell Metab 2013; 17:575-85. [PMID: 23499424 DOI: 10.1016/j.cmet.2013.02.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 12/14/2012] [Accepted: 02/05/2013] [Indexed: 11/30/2022]
Abstract
Lipid mobilization (lipolysis) in white adipose tissue (WAT) critically controls lipid turnover and adiposity in humans. While the acute regulation of lipolysis has been studied in detail, the transcriptional determinants of WAT lipolytic activity remain still largely unexplored. Here we show that the genetic inactivation of transcriptional cofactor transducin beta-like-related 1(TBLR1) blunts the lipolytic response of white adipocytes through the impairment of cAMP-dependent signal transduction. Indeed, mice lacking TBLR1 in adipocytes are defective in fasting-induced lipid mobilization and, when placed on a high-fat-diet, show aggravated adiposity, glucose intolerance, and insulin resistance. TBLR1 levels are found to increase under lipolytic conditions in WAT of both human patients and mice, correlating with serum free fatty acids (FFAs). As a critical regulator of WAT cAMP signaling and lipid mobilization, proper activity of TBLR1 in adipocytes might thus represent a critical molecular checkpoint for the prevention of metabolic dysfunction in subjects with obesity-related disorders.
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Affiliation(s)
- Maria Rohm
- Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance and Network Aging Research, German Cancer Research Center (DKFZ) Heidelberg, Center for Molecular Biology (ZMBH) and University Hospital, Heidelberg University, 69120 Heidelberg, Germany
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Abstract
All organisms use fatty acids (FAs) for energy substrates and as precursors for membrane and signaling lipids. The most efficient way to transport and store FAs is in the form of triglycerides (TGs); however, TGs are not capable of traversing biological membranes and therefore need to be cleaved by TG hydrolases ("lipases") before moving in or out of cells. This biochemical process is generally called "lipolysis." Intravascular lipolysis degrades lipoprotein-associated TGs to FAs for their subsequent uptake by parenchymal cells, whereas intracellular lipolysis generates FAs and glycerol for their release (in the case of white adipose tissue) or use by cells (in the case of other tissues). Although the importance of lipolysis has been recognized for decades, many of the key proteins involved in lipolysis have been uncovered only recently. Important new developments include the discovery of glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1), the molecule that moves lipoprotein lipase from the interstitial spaces to the capillary lumen, and the discovery of adipose triglyceride lipase (ATGL) and comparative gene identification-58 (CGI-58) as crucial molecules in the hydrolysis of TGs within cells. This review summarizes current views of lipolysis and highlights the relevance of this process to human disease.
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Affiliation(s)
- Stephen G. Young
- Department of Medicine
- Department of Human Genetics, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
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Partial inhibition of adipose tissue lipolysis improves glucose metabolism and insulin sensitivity without alteration of fat mass. PLoS Biol 2013; 11:e1001485. [PMID: 23431266 PMCID: PMC3576369 DOI: 10.1371/journal.pbio.1001485] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 01/08/2013] [Indexed: 02/08/2023] Open
Abstract
Partial inhibition of adipose tissue lipolysis does not increase fat mass but improves glucose metabolism and insulin sensitivity through modulation of fatty acid turnover and induction of fat cell de novo lipogenesis. When energy is needed, white adipose tissue (WAT) provides fatty acids (FAs) for use in peripheral tissues via stimulation of fat cell lipolysis. FAs have been postulated to play a critical role in the development of obesity-induced insulin resistance, a major risk factor for diabetes and cardiovascular disease. However, whether and how chronic inhibition of fat mobilization from WAT modulates insulin sensitivity remains elusive. Hormone-sensitive lipase (HSL) participates in the breakdown of WAT triacylglycerol into FAs. HSL haploinsufficiency and treatment with a HSL inhibitor resulted in improvement of insulin tolerance without impact on body weight, fat mass, and WAT inflammation in high-fat-diet–fed mice. In vivo palmitate turnover analysis revealed that blunted lipolytic capacity is associated with diminution in FA uptake and storage in peripheral tissues of obese HSL haploinsufficient mice. The reduction in FA turnover was accompanied by an improvement of glucose metabolism with a shift in respiratory quotient, increase of glucose uptake in WAT and skeletal muscle, and enhancement of de novo lipogenesis and insulin signalling in liver. In human adipocytes, HSL gene silencing led to improved insulin-stimulated glucose uptake, resulting in increased de novo lipogenesis and activation of cognate gene expression. In clinical studies, WAT lipolytic rate was positively and negatively correlated with indexes of insulin resistance and WAT de novo lipogenesis gene expression, respectively. In obese individuals, chronic inhibition of lipolysis resulted in induction of WAT de novo lipogenesis gene expression. Thus, reduction in WAT lipolysis reshapes FA fluxes without increase of fat mass and improves glucose metabolism through cell-autonomous induction of fat cell de novo lipogenesis, which contributes to improved insulin sensitivity. In periods of energy demand, mobilization of fat stores in mammals (i.e., adipose tissue lipolysis) is essential to provide energy in the form of fatty acids. In excess, however, fatty acids induce resistance to the action of insulin, which serves to regulate glucose metabolism in skeletal muscle and liver. Insulin resistance (or low insulin sensitivity) is believed to be a cornerstone of the complications of obesity such as type 2 diabetes and cardiovascular diseases. In this study, our clinical observation of natural variation in fat cell lipolysis in individuals reveals that a high lipolytic rate is associated with low insulin sensitivity. Furthermore, partial genetic and pharmacologic inhibition of hormone-sensitive lipase, one of the enzymes involved in the breakdown of white adipose tissue lipids, results in improvement of insulin sensitivity in mice without gain in body weight and fat mass. We undertake a series of mechanistic studies in mice and in human fat cells to show that blunted lipolytic capacity increases the synthesis of new fatty acids from glucose in fat cells, a pathway that has recently been shown by others to be a major determinant of whole body insulin sensitivity. In conclusion, partial inhibition of adipose tissue lipolysis is a plausible strategy in the treatment of obesity-related insulin resistance.
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Manteiga S, Choi K, Jayaraman A, Lee K. Systems biology of adipose tissue metabolism: regulation of growth, signaling and inflammation. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2013; 5:425-47. [PMID: 23408581 DOI: 10.1002/wsbm.1213] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Adipose tissue (AT) depots actively regulate whole body energy homeostasis by orchestrating complex communications with other physiological systems as well as within the tissue. Adipocytes readily respond to hormonal and nutritional inputs to store excess nutrients as intracellular lipids or mobilize the stored fat for utilization. Co-ordinated regulation of metabolic pathways balancing uptake, esterification, and hydrolysis of lipids is accomplished through positive and negative feedback interactions of regulatory hubs comprising several pleiotropic protein kinases and nuclear receptors. Metabolic regulation in adipocytes encompasses biogenesis and remodeling of uniquely large lipid droplets (LDs). The regulatory hubs also function as energy and nutrient sensors, and integrate metabolic regulation with intercellular signaling. Over-nutrition causes hypertrophic expansion of adipocytes, which, through incompletely understood mechanisms, initiates a cascade of metabolic and signaling events leading to tissue remodeling and immune cell recruitment. Macrophage activation and polarization toward a pro-inflammatory phenotype drives a self-reinforcing cycle of pro-inflammatory signals in the AT, establishing an inflammatory state. Sustained inflammation accelerates lipolysis and elevates free fatty acids in circulation, which robustly correlates with development of obesity-related diseases. The adipose regulatory network coupling metabolism, growth, and signaling of multiple cell types is exceedingly complex. While components of the regulatory network have been individually studied in exquisite detail, systems approaches have rarely been utilized to comprehensively assess the relative engagements of the components. Thus, need and opportunity exist to develop quantitative models of metabolic and signaling networks to achieve a more complete understanding of AT biology in both health and disease.
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Affiliation(s)
- Sara Manteiga
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA, USA
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Extracellular Matrix Remodeling and Mechanical Stresses as Modulators of Adipose Tissue Metabolism and Inflammation. THE MECHANOBIOLOGY OF OBESITY AND RELATED DISEASES 2013. [DOI: 10.1007/8415_2013_172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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TSUDUKI T, KITANO Y, HONMA T, KIJIMA R, IKEDA I. High Dietary Fat Intake during Lactation Promotes Development of Diet-Induced Obesity in Male Offspring of Mice. J Nutr Sci Vitaminol (Tokyo) 2013; 59:384-92. [DOI: 10.3177/jnsv.59.384] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Zechner R, Zimmermann R, Eichmann TO, Kohlwein SD, Haemmerle G, Lass A, Madeo F. FAT SIGNALS--lipases and lipolysis in lipid metabolism and signaling. Cell Metab 2012; 15:279-91. [PMID: 22405066 PMCID: PMC3314979 DOI: 10.1016/j.cmet.2011.12.018] [Citation(s) in RCA: 765] [Impact Index Per Article: 63.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 11/18/2011] [Accepted: 12/07/2011] [Indexed: 12/01/2022]
Abstract
Lipolysis is defined as the catabolism of triacylglycerols stored in cellular lipid droplets. Recent discoveries of essential lipolytic enzymes and characterization of numerous regulatory proteins and mechanisms have fundamentally changed our perception of lipolysis and its impact on cellular metabolism. New findings that lipolytic products and intermediates participate in cellular signaling processes and that "lipolytic signaling" is particularly important in many nonadipose tissues unveil a previously underappreciated aspect of lipolysis, which may be relevant for human disease.
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Affiliation(s)
- Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Austria.
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Adipocyte pyruvate dehydrogenase kinase 4 expression is associated with augmented PPARγ upregulation in early-life programming of later obesity. FEBS Open Bio 2012; 2:32-6. [PMID: 23650578 PMCID: PMC3642103 DOI: 10.1016/j.fob.2012.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 02/14/2012] [Accepted: 02/17/2012] [Indexed: 01/08/2023] Open
Abstract
We studied adipocytes from 8-week-old control rat offspring (CON) or rat offspring subjected to maternal low (8%) protein (MLP) feeding during pregnancy/lactation, a procedure predisposing to obesity. Acute exposure to isoproterenol or adenosine enhanced PDK4 and PPARγ mRNA gene expression in CON and MLP adipocytes. Enhanced adipocyte Pdk4 expression correlated with increased PPARγ expression. Higher levels of PDK4 and PPARγ were observed in MLP adipocytes. SCD1 is a PPARγ target. Isoproterenol enhanced adipocyte PDK4 and SCD1 gene expression in parallel. This could reflect augmented PPARγ expression together with enhanced lipolytic stimulation to supply endogenous PPARγ ligands, allowing enhanced adipocyte PDK4 and SCD1 expression via PPARγ activation. In contrast, the effect of adenosine to increase PDK4 expression is independent of stimulation of lipolysis and, as SCD1 expression was unaffected by adenosine, unlikely to reflect PPARγ activation. Increased adipocyte expression of both PDK4 and SCD1 in the MLP model could participate as components of a "thrifty" phenotype, favouring the development of obesity.
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Key Words
- ADO, adenosine
- Adipose tissue
- BSA, bovine serum albumin
- CON, control
- HSL, hormone-sensitive lipase
- ISO, isoproterenol
- KRHB, Krebs–Ringer HEPES buffer
- Lipogenesis
- MLP, maternal low protein
- NEFA, non-esterified fatty acid
- PC, pyruvate carboxylase
- PDC, pyruvate dehydrogenase complex
- PDK, pyruvate dehydrogenase kinase
- PEPCK, phosphoenolpyruvate carboxykinase
- PPAR, peroxisome proliferator-activated receptor
- Programming
- Pyruvate dehydrogenase complex
- SCD, stearoyl-CoA desaturase
- TAG, triacylglycerol
- WAT, white adipose tissue
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Fernandez C, Schuhmann K, Herzog R, Fielding B, Frayn K, Shevchenko A, James P, Holm C, Ström K. Altered desaturation and elongation of fatty acids in hormone-sensitive lipase null mice. PLoS One 2011; 6:e21603. [PMID: 21738729 PMCID: PMC3126817 DOI: 10.1371/journal.pone.0021603] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 06/03/2011] [Indexed: 01/10/2023] Open
Abstract
Background Hormone-sensitive lipase (HSL) is expressed predominantly in adipose tissue, where it plays an important role in catecholamine-stimulated hydrolysis of stored lipids, thus mobilizing fatty acids. HSL exhibits broad substrate specificity and besides acylglycerides it hydrolyzes cholesteryl esters, retinyl esters and lipoidal esters. Despite its role in fatty acid mobilization, HSL null mice have been shown to be resistant to diet-induced obesity. The aim of this study was to define lipid profiles in plasma, white adipose tissue (WAT) and liver of HSL null mice, in order to better understand the role of this multifunctional enzyme. Methodology/Principal Findings This study used global and targeted lipidomics and expression profiling to reveal changed lipid profiles in WAT, liver and plasma as well as altered expression of desaturases and elongases in WAT and liver of HSL null mice on high fat diet. Decreased mRNA levels of stearoyl-CoA desaturase 1 and 2 in WAT were consistent with a lowered ratio of 16∶1n7/16∶0 and 18∶1n9/18∶0 in WAT and plasma. In WAT, increased ratio of 18∶0/16∶0 could be linked to elevated mRNA levels of the Elovl1 elongase. Conclusions This study illustrates the importance of HSL for normal lipid metabolism in response to a high fat diet. HSL deficiency greatly influences the expression of elongases and desaturases, resulting in altered lipid profiles in WAT, liver and plasma. Finally, altered proportions of palmitoleate, a recently-suggested lipokine, in tissue and plasma of HSL null mice, could be an important factor mediating and contributing to the changed lipid profile, and possibly also to the decreased insulin sensitivity seen in HSL null mice.
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Affiliation(s)
- Céline Fernandez
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Kai Schuhmann
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Ronny Herzog
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Barbara Fielding
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, United Kingdom
| | - Keith Frayn
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, United Kingdom
| | - Andrej Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Peter James
- Department of Immunotechnology, Lund University, Lund, Sweden
| | - Cecilia Holm
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Kristoffer Ström
- Department of Experimental Medical Science, Lund University, Lund, Sweden
- * E-mail:
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Girousse A, Langin D. Adipocyte lipases and lipid droplet-associated proteins: insight from transgenic mouse models. Int J Obes (Lond) 2011; 36:581-94. [PMID: 21673652 DOI: 10.1038/ijo.2011.113] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Adipose tissue lipolysis is the catabolic process whereby stored triacylglycerol (TAG) is broken down by lipases into fatty acids and glycerol. Here, we review recent insights from transgenic mouse models. Genetic manipulations affecting lipases are considered first, followed by transgenic models of lipase co-factors and lastly non-lipase lipid droplet (LD)-associated proteins. The central role of hormone-sensitive lipase (HSL), long considered to be the sole rate-limiting enzyme of TAG hydrolysis, has been revised since the discovery of adipose triglyceride lipase (ATGL). It is now accepted that ATGL initiates TAG breakdown producing diacylglycerol, which is subsequently hydrolyzed by HSL. Furthermore, lipase activities are modulated by co-factors whose deletion causes severe metabolic disturbances. Another major advance has come from the description of the involvement of non-lipase proteins in the regulation of lipolysis. The role of perilipins has been extensively investigated. Other newly discovered LD-associated proteins have also been shown to regulate lipolysis.
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Affiliation(s)
- A Girousse
- Laboratoire de Recherche sur les Obésités, INSERM U1048-I2MC, Equipe 4, Toulouse, France
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Wang H, Sztalryd C. Oxidative tissue: perilipin 5 links storage with the furnace. Trends Endocrinol Metab 2011; 22:197-203. [PMID: 21632259 PMCID: PMC3122074 DOI: 10.1016/j.tem.2011.03.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 03/25/2011] [Accepted: 03/30/2011] [Indexed: 10/18/2022]
Abstract
Cellular energy homeostasis is a crucial function of oxidative tissues and is altered in obesity, a continuously rising health problem. Lipid droplets (LD) are thought to play a central role in lipid homeostasis by mediating the transient storage of fatty acids in the form of triglyceride, while preventing high levels of toxic lipid intermediates or oxidized lipids that mediate cellular lipotoxicity. Members of the perilipin protein family coating LD surfaces have been found to serve important regulatory and structural functions crucial to the regulation of lipid stores. This review examines the results of studies on one of the newest members of the perilipin family, perilipin 5, which has emerged as a putative key player in LD function in oxidative tissues.
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Affiliation(s)
- Hong Wang
- The Geriatric Research, Education and Clinical Center, Baltimore Veterans Affairs Health Care Center, and Division of Endocrinology, Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland 21201, USA
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Shen WJ, Liu LF, Patel S, Kraemer FB. Hormone-sensitive lipase-knockout mice maintain high bone density during aging. FASEB J 2011; 25:2722-30. [PMID: 21566206 DOI: 10.1096/fj.11-181016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We tested the hypothesis that the actions of hormone-sensitive lipase (HSL) affect the microenvironment of the bone marrow and that removal of HSL function by gene deletion maintains high bone mass in aging mice. We compared littermate control wild-type (WT) and HSL(-/-) mice during aging for changes in serum biochemical values, trabecular bone density using micro-computed tomography, bone histomorphometry, and characteristics of primary bone marrow cells and preosteoblasts. There is a regulated expression of HSL and genes involved in lipid metabolism in the bone marrow during aging. HSL(-/-) mice have increased serum levels of insulin and osteocalcin with decreased leptin levels. Compared with the marked adipocyte infiltration in WT bone marrow (65% by area) at 14 mo, HSL(-/-) mice have fewer (16%, P<0.05) and smaller adipocytes in bone marrow. While peak bone density is similar, HSL(-/-) mice maintain a higher bone density (bone volume/total volume 6.1%) with age than WT mice (2.6%, P<0.05). Primary osteoblasts from HSL(-/-) mice show increased growth rates and higher osteogenic potential, manifested by increased expression of Runx2 (3.5-fold, P<0.05) and osteocalcin (4-fold, P<0.05). The absence of HSL directs cells within the bone marrow toward osteoblast differentiation and favors the maintenance of bone density with aging.
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Affiliation(s)
- Wen-Jun Shen
- Division of Endocrinology, Stanford University, Stanford, CA 94305-5103, USA
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