51
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Sun C, Jiang L, Liu Y, Shen H, Weiss SJ, Zhou Y, Rui L. Adipose Snail1 Regulates Lipolysis and Lipid Partitioning by Suppressing Adipose Triacylglycerol Lipase Expression. Cell Rep 2016; 17:2015-2027. [PMID: 27851965 PMCID: PMC5131732 DOI: 10.1016/j.celrep.2016.10.070] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/25/2016] [Accepted: 10/19/2016] [Indexed: 12/14/2022] Open
Abstract
Lipolysis provides metabolic fuel; however, aberrant adipose lipolysis results in ectopic lipid accumulation and lipotoxicity. While adipose triacylglycerol lipase (ATGL) catalyzes the first step of lipolysis, its regulation is not fully understood. Here, we demonstrate that adipocyte Snail1 suppresses both ATGL expression and lipolysis. Adipose Snail1 levels are higher in fed mice than in fasted mice and higher in obese mice as opposed to lean mice. Insulin increases Snail1 levels in both murine and human adipocytes, wherein Snail1 binds to the ATGL promoter to repress its expression. Importantly, adipocyte-specific deletion of Snail1 increases adipose ATGL expression and lipolysis, resulting in decreased fat mass and increased liver fat content in mice fed either a normal chow diet or a high-fat diet. Thus, we have identified a Snail1-ATGL axis that regulates adipose lipolysis and fatty acid release, thereby governing lipid partitioning between adipose and non-adipose tissues.
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MESH Headings
- 3T3-L1 Cells
- Adipocytes, White/drug effects
- Adipocytes, White/metabolism
- Adipocytes, White/pathology
- Adipose Tissue, White/drug effects
- Adipose Tissue, White/metabolism
- Animals
- Cell Size/drug effects
- Diet, High-Fat
- Down-Regulation/drug effects
- Down-Regulation/genetics
- Epigenesis, Genetic/drug effects
- Fatty Liver/metabolism
- Fatty Liver/pathology
- Gene Deletion
- Humans
- Insulin/pharmacology
- Lipase/genetics
- Lipase/metabolism
- Lipolysis/drug effects
- Liver/drug effects
- Liver/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Obesity/metabolism
- Obesity/pathology
- Organ Specificity
- Promoter Regions, Genetic/genetics
- Snail Family Transcription Factors/metabolism
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Affiliation(s)
- Chengxin Sun
- School of Life Sciences, University of Northeast Normal University, Changchun 130024, China; Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Lin Jiang
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Yan Liu
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Hong Shen
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Stephen J Weiss
- Life Sciences Institute, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Yifa Zhou
- School of Life Sciences, University of Northeast Normal University, Changchun 130024, China.
| | - Liangyou Rui
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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52
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Chen G, Yu D, Nian X, Liu J, Koenig RJ, Xu B, Sheng L. LncRNA SRA promotes hepatic steatosis through repressing the expression of adipose triglyceride lipase (ATGL). Sci Rep 2016; 6:35531. [PMID: 27759039 PMCID: PMC5069493 DOI: 10.1038/srep35531] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 09/30/2016] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD), the most common form of chronic liver disease, manifests as an over-accumulation of hepatic fat. We have recently shown that mice with genetic knockout of a long non-coding RNA (lncRNA) steroid receptor RNA activator (SRA) (SRAKO) are resistant to high fat diet-induced obesity with a phenotype that includes improved glucose tolerance and attenuated hepatic steatosis. The underlying mechanism was investigated in the present study. We found that hepatic levels of SRA and adipose triglyceride lipase (ATGL), a major hepatic triacylglycerol (TAG) hydrolase, were inversely regulated by fasting in mice, and the expression of liver ATGL was induced by SRAKO under normal and high fat diet (HFD) feeding. Loss of SRA in primary hepatocytes or a hepatocyte cell line upregulates, but forced expression of SRA inhibits ATGL expression and free fatty acids (FFA) β-oxidation. SRA inhibits ATGL promoter activity, primarily by inhibiting the otherwise-inductive effects of the transcription factor, forkhead box protein O1 (FoxO1). Our data reveal a novel function of SRA in promoting hepatic steatosis through repression of ATGL expression.
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Affiliation(s)
- Gang Chen
- Department of Hepatobiliary Surgery, The First Affiliated Hospital, Wenzhou Medical University, Wenzhou 325000, China
| | - Dongsheng Yu
- Department of Pharmacology, School of Basic Medical Science, Nanjing Medical University, 140 Hanzhong Rd., Nanjing, Jiangsu, 210029, China
| | - Xue Nian
- Department of Pharmacology, School of Basic Medical Science, Nanjing Medical University, 140 Hanzhong Rd., Nanjing, Jiangsu, 210029, China
| | - Junyi Liu
- Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Ronald J Koenig
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, MI 48109-5678, USA
| | - Bin Xu
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, MI 48109-5678, USA
| | - Liang Sheng
- Department of Pharmacology, School of Basic Medical Science, Nanjing Medical University, 140 Hanzhong Rd., Nanjing, Jiangsu, 210029, China
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53
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Ren G, Cairl N, Kim JY, Smas CM. Data on regulation of the gene for the adipocyte-enriched micropeptide Adig/Smaf1 by qPCR analysis and luciferase reporter assay. Data Brief 2016; 9:635-641. [PMID: 27766294 PMCID: PMC5067096 DOI: 10.1016/j.dib.2016.09.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/30/2016] [Accepted: 09/20/2016] [Indexed: 11/30/2022] Open
Abstract
This article describes qPCR analysis for the Adig/Smaf1 gene in multiple in vitro adipocyte differentiation models including white and brown adipogenesis, cell lines and primary cultures. The article also contains qPCR data for transcript levels of Adig/Smaf1 in a wide panel of murine tissues. Expression of Adig/Smaf1 transcript in white and brown adipose tissue in fasted and refed mice is reported and also data for Adig/Smaf1 transcript expression in genetically obese ob/ob mice. Data on the effects of siRNA-mediated knockdown of Srebp1c on Adig/Smaf1 transcript levels in 3T3-L1 adipocytes are shown. Luciferase reporter assays provide data for regulation of an ~ 2 kb fragment of the 5′ flanking region of Adig/Smaf1 gene by PPARγ/RXRα. This data is related to a research article describing Adig/Smaf1 protein expression, “Expression, regulation and functional assessment of the 80 amino acid Small Adipocyte Factor 1 (Smaf1) protein in adipocytes” (G. Ren, P. Eskandari, S. Wang, C.M. Smas, 2016) [1].
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Affiliation(s)
- Gang Ren
- University of Toledo College of Medicine, Department of Biochemistry and Cancer Biology and the Center for Diabetes and Endocrine Research, Toledo, OH, USA
| | - Nicholas Cairl
- University of Toledo College of Medicine, Department of Biochemistry and Cancer Biology and the Center for Diabetes and Endocrine Research, Toledo, OH, USA
| | - Ji Young Kim
- University of Toledo College of Medicine, Department of Biochemistry and Cancer Biology and the Center for Diabetes and Endocrine Research, Toledo, OH, USA
| | - Cynthia M Smas
- University of Toledo College of Medicine, Department of Biochemistry and Cancer Biology and the Center for Diabetes and Endocrine Research, Toledo, OH, USA
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54
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Lee JH, Han JS, Kong J, Ji Y, Lv X, Lee J, Li P, Kim JB. Protein Kinase A Subunit Balance Regulates Lipid Metabolism in Caenorhabditis elegans and Mammalian Adipocytes. J Biol Chem 2016; 291:20315-28. [PMID: 27496951 DOI: 10.1074/jbc.m116.740464] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Indexed: 11/06/2022] Open
Abstract
Protein kinase A (PKA) is a cyclic AMP (cAMP)-dependent protein kinase composed of catalytic and regulatory subunits and involved in various physiological phenomena, including lipid metabolism. Here we demonstrated that the stoichiometric balance between catalytic and regulatory subunits is crucial for maintaining basal PKA activity and lipid homeostasis. To uncover the potential roles of each PKA subunit, Caenorhabditis elegans was used to investigate the effects of PKA subunit deficiency. In worms, suppression of PKA via RNAi resulted in severe phenotypes, including shortened life span, decreased egg laying, reduced locomotion, and altered lipid distribution. Similarly, in mammalian adipocytes, suppression of PKA regulatory subunits RIα and RIIβ via siRNAs potently stimulated PKA activity, leading to potentiated lipolysis without increasing cAMP levels. Nevertheless, insulin exerted anti-lipolytic effects and restored lipid droplet integrity by antagonizing PKA action. Together, these data implicate the importance of subunit stoichiometry as another regulatory mechanism of PKA activity and lipid metabolism.
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Affiliation(s)
- Jung Hyun Lee
- From the Department of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, 08862 Seoul, Korea
| | - Ji Seul Han
- From the Department of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, 08862 Seoul, Korea
| | - Jinuk Kong
- From the Department of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, 08862 Seoul, Korea
| | - Yul Ji
- From the Department of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, 08862 Seoul, Korea
| | - Xuchao Lv
- the MOE Key Laboratory of Bioinformatics and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China and
| | - Junho Lee
- From the Department of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, 08862 Seoul, Korea, the Department of Biophysics and Chemical Biology, Seoul National University, Seoul 08862, Korea
| | - Peng Li
- the MOE Key Laboratory of Bioinformatics and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China and
| | - Jae Bum Kim
- From the Department of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, 08862 Seoul, Korea,
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55
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Kim J, Sun Q, Yue Y, Yoon KS, Whang KY, Marshall Clark J, Park Y. 4,4'-Dichlorodiphenyltrichloroethane (DDT) and 4,4'-dichlorodiphenyldichloroethylene (DDE) promote adipogenesis in 3T3-L1 adipocyte cell culture. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2016; 131:40-5. [PMID: 27265825 DOI: 10.1016/j.pestbp.2016.01.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 01/12/2016] [Accepted: 01/18/2016] [Indexed: 05/05/2023]
Abstract
4,4'-Dichlorodiphenyltrichloroethane (DDT), a chlorinated hydrocarbon insecticide, was extensively used in the 1940s and 1950s. DDT is mainly metabolically converted into 4,4'-dichlorodiphenyldichloroethylene (DDE). Even though most countries banned DDT in the 1970s, due to the highly lipophilic nature and very stable characteristics, DDT and its metabolites are present ubiquitously in the environment, including food. Recently, there are publications on relationships between exposure to insecticides, including DDT and DDE, and weight gain and altered glucose homeostasis. However, there are limited reports regarding DDT or DDE and adipogenesis, thus we investigated effects of DDT and DDE on adipogenesis using 3T3-L1 adipocytes. Treatment of DDT or DDE resulted in increased lipid accumulation accompanied by increased expression of CCAAT/enhancer-binding protein α (C/EBPα), peroxisome-proliferator activated receptor-γ (PPARγ), fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), adipose triglyceride lipase, and leptin. Moreover, treatment of DDT or DDE increased protein levels of C/EBPα, PPARγ, AMP-activated protein kinase-α (AMPKα), and ACC, while significant decrease of phosphorylated forms of AMPKα and ACC were observed. These finding suggest that increased lipid accumulation caused by DDT and DDE may mediate AMPKα pathway in 3T3-L1 adipocytes.
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Affiliation(s)
- Jonggun Kim
- Division of Biotechnology, Korea University, Seoul 136-713, Republic of Korea
| | - Quancai Sun
- Department of Food Science, University of Massachusetts, Amherst, 102 Holdsworth Way, Amherst, MA 01003, United States
| | - Yiren Yue
- Department of Food Science, University of Massachusetts, Amherst, 102 Holdsworth Way, Amherst, MA 01003, United States
| | - Kyong Sup Yoon
- Department of Biological Sciences and Environmental Sciences Program, Southern Illinois University, Edwardsville, IL 62026, United States
| | - Kwang-Youn Whang
- Division of Biotechnology, Korea University, Seoul 136-713, Republic of Korea
| | - J Marshall Clark
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, 637 North Pleasant Street, Amherst, MA 01003, United States
| | - Yeonhwa Park
- Department of Food Science, University of Massachusetts, Amherst, 102 Holdsworth Way, Amherst, MA 01003, United States.
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56
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Zhu XY, Ma S, Eirin A, Woollard JR, Hickson LJ, Sun D, Lerman A, Lerman LO. Functional Plasticity of Adipose-Derived Stromal Cells During Development of Obesity. Stem Cells Transl Med 2016; 5:893-900. [PMID: 27177576 PMCID: PMC4922846 DOI: 10.5966/sctm.2015-0240] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 03/04/2016] [Indexed: 01/03/2023] Open
Abstract
This study examined the hypothesis that microenvironmental inflammatory changes during development of metabolic disorders in obesity affect adipose-derived stromal cell (ASC) function. It was found that adipose tissue inflammation promotes an increase in resident adipocyte progenitors and upregulated tumor necrosis factor-α enhances ASC adipogenesis. Thus, adipose tissue anti-inflammatory strategies might be a novel target to attenuate obesity and its complications. Obesity is a major risk factor for a number of chronic diseases, including diabetes, cardiovascular diseases, and cancer. Expansion of the adipose mass requires adipocyte precursor cells that originate from multipotent adipose-derived stromal cells (ASCs), which in turn also participate in repair activities. ASC function might decline in a disease milieu, but it remains unclear whether ASC function varies during the development of obesity. We tested the hypothesis that microenvironmental inflammatory changes during development of metabolic disorders in obesity affect ASC function. Domestic pigs were fed with an atherogenic (n = 7) or normal (n = 7) diet for 16 weeks. Abdominal adipose tissue biopsies were collected after 8, 12, and 16 weeks of diet for ASC isolation and immunohistochemistry of in situ ASCs and tumor necrosis factor-α (TNF-α). Longitudinal changes in proliferation, differentiation, and anti-inflammatory functions of ASCs were assessed. At 16 weeks, upregulated TNF-α expression in adipose tissue from obese pigs was accompanied by increased numbers of adipocyte progenitors (CD24+/CD34+) in adipose tissue and enlarged adipocyte size. In vitro, ASCs from obese pigs showed enhanced adipogenic and osteogenic propensity, which was abolished by anti-TNF-α treatment, whereas lean ASCs treated with TNF-α showed enhanced adipogenesis. Furthermore, obese ASCs showed increased senescence compared with lean ASCs, whereas their immunomodulatory capacity was preserved. Adipose tissue inflammation promotes an increase in resident adipocyte progenitors and upregulated TNF-α enhances ASC adipogenesis. Thus, adipose tissue anti-inflammatory strategies might be a novel target to attenuate obesity and its complications. Significance Adipose-derived stromal cell (ASC) function might decline in a disease milieu, but it remains unclear whether ASC function varies during the development of obesity. This study tested the hypothesis that microenvironmental inflammatory changes during development of metabolic disorders in obesity affect ASC function. It was found that ASCs show increased propensity for differentiation into adipocytes, which is partly mediated by upregulated tumor necrosis factor-α (TNF-α), likely in their adipose tissue microenvironment. Furthermore, TNF-α magnified obese ASC senescence, although it did not regulate their anti-inflammatory properties. Thus, adipose tissue inflammation might be a novel therapeutic target to avert ASC maldifferentiation and senescence.
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Affiliation(s)
- Xiang-Yang Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Shuangtao Ma
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - John R Woollard
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - LaTonya J Hickson
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Dong Sun
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Amir Lerman
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
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57
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miR-155 Deletion in Female Mice Prevents Diet-Induced Obesity. Sci Rep 2016; 6:22862. [PMID: 26953132 PMCID: PMC4782173 DOI: 10.1038/srep22862] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 02/22/2016] [Indexed: 12/28/2022] Open
Abstract
Obesity is a growing epidemic in developed countries. Obese individuals are susceptible to comorbidities, including cardiovascular disease and metabolic disorder. Increasing the ability of adipose tissue to expend excess energy could improve protection from obesity. One promising target is microRNA (miR)-155-5p. We demonstrate that deletion of miR-155 (-5p and -3p) in female mice prevents diet-induced obesity. Body weight gain did not differ between wild-type (WT) and miR-155 knockout (KO) mice fed control diet (CD); however, miR-155 KO mice fed high-fat diet (HFD) gained 56% less body weight and 74% less gonadal white adipose tissue (WAT) than WT mice. Enhanced WAT thermogenic potential, brown adipose tissue differentiation, and/or insulin sensitivity might underlie this obesity resistance. Indeed, miR-155 KO mice on HFD had 21% higher heat release than WT HFD mice. Compared to WT adipocytes, miR-155 KO adipocytes upregulated brown (Ucp1, Cidea, Pparg) and white (Fabp4, Pnpla2, AdipoQ, Fasn) adipogenic genes, and glucose metabolism genes (Glut4, Irs1). miR-155 deletion abrogated HFD-induced adipocyte hypertrophy and WAT inflammation. Therefore, miR-155 deletion increases adipogenic, insulin sensitivity, and energy uncoupling machinery, while limiting inflammation in WAT, which together could restrict HFD-induced fat accumulation. Our results identify miR-155 as a novel candidate target for improving obesity resistance.
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58
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Ishibashi K, Nehashi K, Oshima T, Ohkura N, Atsumi GI. Differentiation with elaidate tends to impair insulin-dependent glucose uptake and GLUT4 translocation in 3T3-L1 adipocytes. Int J Food Sci Nutr 2016; 67:99-110. [DOI: 10.3109/09637486.2016.1144721] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Kenichi Ishibashi
- Department of Molecular Physiology and Pathology, School of Pharma-Sciences, Teikyo University, Tokyo, Japan
| | - Kana Nehashi
- Department of Molecular Physiology and Pathology, School of Pharma-Sciences, Teikyo University, Tokyo, Japan
| | - Toshiyuki Oshima
- Department of Molecular Physiology and Pathology, School of Pharma-Sciences, Teikyo University, Tokyo, Japan
| | - Naoki Ohkura
- Department of Molecular Physiology and Pathology, School of Pharma-Sciences, Teikyo University, Tokyo, Japan
| | - Gen-Ichi Atsumi
- Department of Molecular Physiology and Pathology, School of Pharma-Sciences, Teikyo University, Tokyo, Japan
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59
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Jocken JWE, Goossens GH, Popeijus H, Essers Y, Hoebers N, Blaak EE. Contribution of lipase deficiency to mitochondrial dysfunction and insulin resistance in hMADS adipocytes. Int J Obes (Lond) 2015; 40:507-13. [PMID: 26471343 DOI: 10.1038/ijo.2015.211] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 09/02/2015] [Accepted: 09/21/2015] [Indexed: 12/16/2022]
Abstract
BACKGROUND/OBJECTIVES Adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) are key enzymes involved in intracellular lipid catabolism. We have previously shown decreased expression and activity of these lipases in adipose tissue of obese insulin resistant individuals. Here we hypothesized that lipase deficiency might impact on insulin sensitivity and metabolic homeostasis in adipocytes not just by enhancing lipid accumulation, but also by altering lipid and carbohydrate catabolism in a peroxisome proliferator-activated nuclear receptor (PPAR)-dependent manner. METHODS To address our hypothesis, we performed a series of in vitro experiments in a human white adipocyte model, the human multipotent adipose-derived stem (hMADS) cells, using genetic (siRNA) and pharmacological knockdown of ATGL and/or HSL. RESULTS We show that ATGL and HSL knockdown in hMADS adipocytes disrupted mitochondrial respiration, which was accompanied by a decreased oxidative phosphorylation (OxPhos) protein content. This lead to a reduced exogenous and endogenous palmitate oxidation following ATGL knockdown, but not in HSL deficient adipocytes. ATGL deficiency was followed by excessive triacylglycerol accumulation, and HSL deficiency further increased diacylglycerol accumulation. Both single and double lipase knockdown reduced insulin-stimulated glucose uptake, which was attributable to impaired insulin signaling. These effects were accompanied by impaired activation of the nuclear receptor PPARα, and restored on PPARα agonist treatment. CONCLUSIONS The present study indicates that lipase deficiency in human white adipocytes contributes to mitochondrial dysfunction and insulin resistance, in a PPARα-dependent manner. Therefore, modulation of adipose tissue lipases may provide a promising strategy to reverse insulin resistance in obese and type 2 diabetic patients.
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Affiliation(s)
- J W E Jocken
- Department of Human Biology, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - G H Goossens
- Department of Human Biology, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - H Popeijus
- Department of Human Biology, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Y Essers
- Department of Human Biology, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - N Hoebers
- Department of Human Biology, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - E E Blaak
- Department of Human Biology, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
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60
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Lei X, Callaway M, Zhou H, Yang Y, Chen W. Obesity associated Lyplal1 gene is regulated in diet induced obesity but not required for adipocyte differentiation. Mol Cell Endocrinol 2015; 411:207-13. [PMID: 25958046 DOI: 10.1016/j.mce.2015.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 04/30/2015] [Accepted: 05/01/2015] [Indexed: 02/08/2023]
Abstract
Obesity and its associated morbidities represent one of the major and most rapidly expanding health epidemics in the world. Recent genome-wide association studies (GWAS) have identified several variants in LYPLAL1 gene that are significantly associated with central obesity preferentially in females. However, the exact function of this gene in adipose tissue development and obesity remains completely uncharacterized. We found murine Lyplal1 gene demonstrated a depot and sex-specific expression profile in white adipose tissues (WAT), and was significantly reduced in the epididymal and retroperitoneal fats in a murine model of high fat diet induced obesity (DIO). Lyplal1 mRNA was mildly up-regulated during adipogenesis and enriched in mature adipocytes through a PPARγ-independent mechanism. However, overexpression and knockdown of Lyplal1 did not significantly perturb adipocyte differentiation, triacylglycerol accumulation and/or insulin signaling. These data highlight a depot-specific marked reduction of Lyplal1 transcripts in diet induced obesity but a dispensable role of Lyplal1 in adipose tissue development.
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Affiliation(s)
- Xinnuo Lei
- College of Veterinary Medicine, Hunan Agricultural University, Changsha, Hunan Province 410128, China; Department of Physiology, Georgia Regents University, Augusta, GA 30912, USA
| | - Mayson Callaway
- Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, USA
| | - Hongyi Zhou
- Department of Physiology, Georgia Regents University, Augusta, GA 30912, USA
| | - Yi Yang
- College of Veterinary Medicine, Hunan Agricultural University, Changsha, Hunan Province 410128, China
| | - Weiqin Chen
- Department of Physiology, Georgia Regents University, Augusta, GA 30912, USA.
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61
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Ramanadham S, Ali T, Ashley JW, Bone RN, Hancock WD, Lei X. Calcium-independent phospholipases A2 and their roles in biological processes and diseases. J Lipid Res 2015; 56:1643-68. [PMID: 26023050 DOI: 10.1194/jlr.r058701] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Indexed: 12/24/2022] Open
Abstract
Among the family of phospholipases A2 (PLA2s) are the Ca(2+)-independent PLA2s (iPLA2s) and they are designated group VI iPLA2s. In relation to secretory and cytosolic PLA2s, the iPLA2s are more recently described and details of their expression and roles in biological functions are rapidly emerging. The iPLA2s or patatin-like phospholipases (PNPLAs) are intracellular enzymes that do not require Ca(2+) for activity, and contain lipase (GXSXG) and nucleotide-binding (GXGXXG) consensus sequences. Though nine PNPLAs have been recognized, PNPLA8 (membrane-associated iPLA2γ) and PNPLA9 (cytosol-associated iPLA2β) are the most widely studied and understood. The iPLA2s manifest a variety of activities in addition to phospholipase, are ubiquitously expressed, and participate in a multitude of biological processes, including fat catabolism, cell differentiation, maintenance of mitochondrial integrity, phospholipid remodeling, cell proliferation, signal transduction, and cell death. As might be expected, increased or decreased expression of iPLA2s can have profound effects on the metabolic state, CNS function, cardiovascular performance, and cell survival; therefore, dysregulation of iPLA2s can be a critical factor in the development of many diseases. This review is aimed at providing a general framework of the current understanding of the iPLA2s and discussion of the potential mechanisms of action of the iPLA2s and related involved lipid mediators.
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Affiliation(s)
- Sasanka Ramanadham
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Tomader Ali
- Undergraduate Research Office, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Jason W Ashley
- Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104
| | - Robert N Bone
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - William D Hancock
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Xiaoyong Lei
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
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Singh M, Shin YK, Yang X, Zehr B, Chakrabarti P, Kandror KV. 4E-BPs Control Fat Storage by Regulating the Expression of Egr1 and ATGL. J Biol Chem 2015; 290:17331-8. [PMID: 25814662 DOI: 10.1074/jbc.m114.631895] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Indexed: 01/04/2023] Open
Abstract
Early growth response transcription factor Egr1 controls multiple aspects of cell physiology and metabolism. In particular, Egr1 suppresses lipolysis and promotes fat accumulation in adipocytes by inhibiting the expression of adipose triglyceride lipase. According to current dogma, regulation of the Egr1 expression takes place primarily at the level of transcription. Correspondingly, treatment of cultured adipocytes with insulin stimulates expression of Egr1 mRNA and protein. Unexpectedly, the MEK inhibitor PD98059 completely blocks insulin-stimulated increase in the Egr1 mRNA but has only a moderate effect on the Egr1 protein. At the same time, mTORC1 inhibitors rapamycin and PP242 suppress expression of the Egr1 protein and have an opposite effect on the Egr1 mRNA. Mouse embryonic fibroblasts with genetic ablations of TSC2 or 4E-BP1/2 express less Egr1 mRNA but more Egr1 protein than wild type controls. (35)S-labeling has confirmed that translation of the Egr1 mRNA is much more effective in 4E-BP1/2-null cells than in control. A selective agonist of the CB1 receptors, ACEA, up-regulates Egr1 mRNA, but does not activate mTORC1 and does not increase Egr1 protein in adipocytes. These data suggest that although insulin activates both the Erk and the mTORC1 signaling pathways in adipocytes, regulation of the Egr1 expression takes place predominantly via the mTORC1/4E-BP-mediated axis. In confirmation of this model, we show that 4E-BP1/2-null MEFs express less ATGL and accumulate more fat than control cells, while knock down of Egr1 in 4E-BP1/2-null MEFs increases ATGL expression and decreases fat storage.
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Affiliation(s)
- Maneet Singh
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - Yu-Kyong Shin
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - Xiaoqing Yang
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - Brad Zehr
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - Partha Chakrabarti
- From the Boston University School of Medicine, Boston, Massachusetts 02118
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Buzelle SL, MacPherson REK, Peppler WT, Castellani L, Wright DC. The contribution of IL-6 to beta 3 adrenergic receptor mediated adipose tissue remodeling. Physiol Rep 2015; 3:3/2/e12312. [PMID: 25713332 PMCID: PMC4393216 DOI: 10.14814/phy2.12312] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The chronic activation of beta 3 adrenergic receptors results in marked alterations in adipose tissue morphology and metabolism, including increases in mitochondrial content and the expression of enzymes involved in lipogenesis and glyceroneogenesis. Acute treatment with CL 316,243, a beta 3 adrenergic agonist, induces the expression of interleukin 6. Interestingly, IL-6 has been shown to induce mitochondrial genes in cultured adipocytes. Therefore, the purpose of this paper was to examine the role of interleukin 6 in mediating the in vivo effects of CL 316,243 in white adipose tissue. Circulating IL-6, and markers of IL-6 signaling in white adipose tissue were increased 4 h following a single injection of CL 316,243 in C57BL6/J mice. Once daily injections of CL 316,243 for 5 days increased the protein content of a number of mitochondrial proteins including CORE1, Cytochrome C, PDH, MCAD, and Citrate Synthase to a similar extent in adipose tissue from WT and IL-6−/− mice. Conversely, CL 316,243-induced increases in COXIV and phosphorylated AMPK were attenuated in IL-6−/− mice. Likewise, the slight, but significant, CL 316,243-induced increases in ATGL, PEPCK, and PPARγ, were reduced or absent in adipose tissue IL-6−/− mice. The attenuated response to CL 316,243 in white adipose tissue in IL-6−/− mice was associated with reductions in whole-body oxygen consumption and energy expenditure in the light phase. Our findings suggest that IL-6 plays a limited role in CL 316,243-mediated adipose tissue remodeling.
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Affiliation(s)
- Samyra L Buzelle
- Department of Biochemistry, Ribeirao Preto Medical School, University of Sao Paulo, Riberao Preto, Brazil
| | - Rebecca E K MacPherson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Willem T Peppler
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Laura Castellani
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Xu X, Feng L, Liu Y, Zhou WX, Ma YC, Fei GJ, An N, Li Y, Wu X, Yao F, Cheng SJ, Lu XH. Differential gene expression profiling of gastric intraepithelial neoplasia and early-stage adenocarcinoma. World J Gastroenterol 2014; 20:17883-17893. [PMID: 25548486 PMCID: PMC4273138 DOI: 10.3748/wjg.v20.i47.17883] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 06/05/2014] [Accepted: 06/17/2014] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the differentiated whole genome expression profiling of gastric high- and low-grade intraepithelial neoplasia and early-stage adenocarcinoma.
METHODS: Gastric specimens from an upper magnifying chromoendoscopic targeted biopsy were collected from March 2010 to May 2013. Whole genome expression profiling was performed on 19 low-grade intraepithelial neoplasia (LGIN), 20 high-grade intraepithelial neoplasia (HGIN), 19 early-stage adenocarcinoma (EGC), and 19 chronic gastritis tissue samples using Agilent 4 × 44K Whole Human Genome microarrays. Differentially expressed genes between different types of lesions were identified using an unpaired t-test and corrected with the Benjamini and Hochberg false discovery rate algorithm. A gene ontology (GO) enrichment analysis was performed using the GeneSpring software GX 12.6. The differentially expressed gene was verified using a real-time TaqMan® PCR assay with independent tissue samples, including 26 LGIN, 15 HGIN, 14 EGC, and 20 chronic gastritis. The expression of G0S2 were further validated by immunohistochemical staining (IHC) in 24 LGIN, 40 HGIN, 30 EGC and 61 chronic gastritis specimens.
RESULTS: The gene expression patterns of LGIN and HGIN tissues were distinct. There were 2521 significantly differentially expressed transcripts in HGIN, with 951 upregulated and 1570 downregulated. A GO enrichment analysis demonstrated that the most striking overexpressed transcripts in HGIN compared with LGIN were in the category of metabolism, defense response, and nuclear factor κB (NF-κB) cascade. While the vast majority of transcripts had barely altered expression in HGIN and EGC tissues, only 38 transcripts were upregulated in EGC. A GO enrichment analysis revealed that the alterations of the immune response were most prominent in the progression from HGIN to EGC. It is worth noting that, compared with LGIN, 289 transcripts were expressed at higher levels both in HGIN and EGC. A characteristic gene, G0/G1 switch 2 (G0S2) was one of the 289 transcripts and related to metabolism, the immune response, and the NF-κB cascade, and its expression was validated in independent samples through real-time TaqMan® PCR and immunohistochemical staining. In real-time PCR analysis, the expression of G0S2 was elevated both in HGIN and EGC compared with that in LGIN (P < 0.01 and P < 0.001, respectively). In IHC analysis, G0S2 immunoreactivity was detected in the cytoplasmic of neoplastic cells, but was undetectable in chronic gastritis cells. The G0S2 expression in HGIN was higher than that of LGIN (P = 0.012, χ2 = 6.28) and EGC (P = 0.008, χ2 = 6.94).
CONCLUSION: A clear biological distinction between gastric high- and low-grade intraepithelial neoplasia was identified, and provides molecular evidence for clinical application.
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López-Yoldi M, Fernández-Galilea M, Laiglesia LM, Larequi E, Prieto J, Martínez JA, Bustos M, Moreno-Aliaga MJ. Cardiotrophin-1 stimulates lipolysis through the regulation of main adipose tissue lipases. J Lipid Res 2014; 55:2634-43. [PMID: 25351614 DOI: 10.1194/jlr.m055335] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cardiotrophin-1 (CT-1) is a cytokine with antiobesity properties and with a role in lipid metabolism regulation and adipose tissue function. The aim of this study was to analyze the molecular mechanisms involved in the lipolytic actions of CT-1 in adipocytes. Recombinant CT-1 (rCT-1) effects on the main proteins and signaling pathways involved in the regulation of lipolysis were evaluated in 3T3-L1 adipocytes and in mice. rCT-1 treatment stimulated basal glycerol release in a concentration- and time-dependent manner in 3T3-L1 adipocytes. rCT-1 (20 ng/ml for 24 h) raised cAMP levels, and in parallel increased protein kinase (PK)A-mediated phosphorylation of perilipin and hormone sensitive lipase (HSL) at Ser660. siRNA knock-down of HSL or PKA, as well as pretreatment with the PKA inhibitor H89, blunted the CT-1-induced lipolysis, suggesting that the lipolytic action of CT-1 in adipocytes is mainly mediated by activation of HSL through the PKA pathway. In ob/ob mice, acute rCT-1 treatment also promoted PKA-mediated phosphorylation of perilipin and HSL at Ser660 and Ser563, and increased adipose triglyceride lipase (desnutrin) content in adipose tissue. These results showed that the ability of CT-1 to regulate the activity of the main lipases underlies the lipolytic action of this cytokine in vitro and in vivo, and could contribute to CT-1 antiobesity effects.
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Affiliation(s)
- Miguel López-Yoldi
- Departments of Nutrition, Food Science, and Physiology University of Navarra, Pamplona, Navarra, Spain Centre for Nutrition Research, University of Navarra, Pamplona, Navarra, Spain
| | - Marta Fernández-Galilea
- Departments of Nutrition, Food Science, and Physiology University of Navarra, Pamplona, Navarra, Spain
| | - Laura M Laiglesia
- Departments of Nutrition, Food Science, and Physiology University of Navarra, Pamplona, Navarra, Spain Centre for Nutrition Research, University of Navarra, Pamplona, Navarra, Spain
| | - Eduardo Larequi
- Gene Therapy and Hepatology, CIMA, University of Navarra, Pamplona, Navarra, Spain
| | - Jesús Prieto
- Gene Therapy and Hepatology, CIMA, University of Navarra, Pamplona, Navarra, Spain CIBERehd Institute of Health Carlos III, Madrid, Spain
| | - J Alfredo Martínez
- Departments of Nutrition, Food Science, and Physiology University of Navarra, Pamplona, Navarra, Spain Centre for Nutrition Research, University of Navarra, Pamplona, Navarra, Spain CIBERobn, Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain
| | - Matilde Bustos
- Gene Therapy and Hepatology, CIMA, University of Navarra, Pamplona, Navarra, Spain
| | - Maria J Moreno-Aliaga
- Departments of Nutrition, Food Science, and Physiology University of Navarra, Pamplona, Navarra, Spain Centre for Nutrition Research, University of Navarra, Pamplona, Navarra, Spain CIBERobn, Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain
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Roles of chronic low-grade inflammation in the development of ectopic fat deposition. Mediators Inflamm 2014; 2014:418185. [PMID: 25143667 PMCID: PMC4131072 DOI: 10.1155/2014/418185] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Revised: 05/13/2014] [Accepted: 05/16/2014] [Indexed: 12/12/2022] Open
Abstract
Pattern of fat distribution is a major determinant for metabolic homeostasis. As a depot of energy, the storage of triglycerides in adipose tissue contributes to the normal fat distribution. Decreased capacity of fat storage in adipose tissue may result in ectopic fat deposition in nonadipose tissues such as liver, pancreas, and kidney. As a critical biomarker of metabolic complications, chronic low-grade inflammation may have the ability to affect the process of lipid accumulation and further lead to the disorder of fat distribution. In this review, we have collected the evidence linking inflammation with ectopic fat deposition to get a better understanding of the underlying mechanism, which may provide us with novel therapeutic strategies for metabolic disorders.
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Cardamone MD, Tanasa B, Chan M, Cederquist CT, Andricovich J, Rosenfeld MG, Perissi V. GPS2/KDM4A pioneering activity regulates promoter-specific recruitment of PPARγ. Cell Rep 2014; 8:163-76. [PMID: 24953653 DOI: 10.1016/j.celrep.2014.05.041] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 04/18/2014] [Accepted: 05/19/2014] [Indexed: 01/09/2023] Open
Abstract
Timely and selective recruitment of transcription factors to their appropriate DNA-binding sites represents a critical step in regulating gene activation; however, the regulatory strategies underlying each factor's effective recruitment to specific promoter and/or enhancer regions are not fully understood. Here, we identify an unexpected regulatory mechanism by which promoter-specific binding, and therefore function, of peroxisome proliferator-activator receptor γ (PPARγ) in adipocytes requires G protein suppressor 2 (GPS2) to prime the local chromatin environment via inhibition of the ubiquitin ligase RNF8 and stabilization of the H3K9 histone demethylase KDM4A/JMJD2. Integration of genome-wide profiling data indicates that the pioneering activity of GPS2/KDM4A is required for PPARγ-mediated regulation of a specific transcriptional program, including the lipolytic enzymes adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL). Hence, our findings reveal that GPS2 exerts a biologically important function in adipose tissue lipid mobilization by directly regulating ubiquitin signaling and indirectly modulating chromatin remodeling to prime selected genes for activation.
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Affiliation(s)
- M Dafne Cardamone
- Biochemistry Department, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA
| | - Bogdan Tanasa
- Department of Medicine, University of California, San Diego, School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Michelle Chan
- Biochemistry Department, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA
| | - Carly T Cederquist
- Biochemistry Department, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA
| | - Jaclyn Andricovich
- Biochemistry Department, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA
| | - Michael G Rosenfeld
- Department of Medicine, University of California, San Diego, School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093, USA; Howard Hughes Medical Institute, University of California, San Diego, School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Valentina Perissi
- Biochemistry Department, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA.
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68
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Nielsen TS, Jessen N, Jørgensen JOL, Møller N, Lund S. Dissecting adipose tissue lipolysis: molecular regulation and implications for metabolic disease. J Mol Endocrinol 2014; 52:R199-222. [PMID: 24577718 DOI: 10.1530/jme-13-0277] [Citation(s) in RCA: 263] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Lipolysis is the process by which triglycerides (TGs) are hydrolyzed to free fatty acids (FFAs) and glycerol. In adipocytes, this is achieved by sequential action of adipose TG lipase (ATGL), hormone-sensitive lipase (HSL), and monoglyceride lipase. The activity in the lipolytic pathway is tightly regulated by hormonal and nutritional factors. Under conditions of negative energy balance such as fasting and exercise, stimulation of lipolysis results in a profound increase in FFA release from adipose tissue (AT). This response is crucial in order to provide the organism with a sufficient supply of substrate for oxidative metabolism. However, failure to efficiently suppress lipolysis when FFA demands are low can have serious metabolic consequences and is believed to be a key mechanism in the development of type 2 diabetes in obesity. As the discovery of ATGL in 2004, substantial progress has been made in the delineation of the remarkable complexity of the regulatory network controlling adipocyte lipolysis. Notably, regulatory mechanisms have been identified on multiple levels of the lipolytic pathway, including gene transcription and translation, post-translational modifications, intracellular localization, protein-protein interactions, and protein stability/degradation. Here, we provide an overview of the recent advances in the field of AT lipolysis with particular focus on the molecular regulation of the two main lipases, ATGL and HSL, and the intracellular and extracellular signals affecting their activity.
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Affiliation(s)
- Thomas Svava Nielsen
- The Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, DenmarkThe Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark
| | - Niels Jessen
- The Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, DenmarkThe Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark
| | - Jens Otto L Jørgensen
- The Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark
| | - Niels Møller
- The Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark
| | - Sten Lund
- The Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark
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69
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Faylon M, Koltes D, Spurlock D. Regulation of lipid droplet-associated proteins following growth hormone administration and feed restriction in lactating Holstein cows. J Dairy Sci 2014; 97:2847-55. [DOI: 10.3168/jds.2013-7565] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 02/05/2014] [Indexed: 11/19/2022]
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70
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Singh M, Kaur R, Lee MJ, Pickering RT, Sharma VM, Puri V, Kandror KV. Fat-specific protein 27 inhibits lipolysis by facilitating the inhibitory effect of transcription factor Egr1 on transcription of adipose triglyceride lipase. J Biol Chem 2014; 289:14481-7. [PMID: 24742676 DOI: 10.1074/jbc.c114.563080] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Lipolysis in fat tissue represents a major source of circulating fatty acids. Previously, we have found that lipolysis in adipocytes is controlled by early growth response transcription factor Egr1 that directly inhibits transcription of adipose triglyceride lipase, ATGL (Chakrabarti, P., Kim, J. Y., Singh, M., Shin, Y. K., Kim, J., Kumbrink, J., Wu, Y., Lee, M. J., Kirsch, K. H., Fried, S. K., and Kandror, K. V. (2013) Mol. Cell. Biol. 33, 3659-3666). Here we demonstrate that knockdown of the lipid droplet protein FSP27 (a.k.a. CIDEC) in human adipocytes increases expression of ATGL at the level of transcription, whereas overexpression of FSP27 has the opposite effect. FSP27 suppresses the activity of the ATGL promoter in vitro, and the proximal Egr1 binding site is responsible for this effect. FSP27 co-immunoprecipitates with Egr1 and increases its association with and inhibition of the ATGL promoter. Knockdown of Egr1 attenuates the inhibitory effect of FSP27. These results provide a new model of transcriptional regulation of ATGL.
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Affiliation(s)
- Maneet Singh
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - Rajween Kaur
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - Mi-Jeong Lee
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | - R Taylor Pickering
- From the Boston University School of Medicine, Boston, Massachusetts 02118
| | | | - Vishwajeet Puri
- From the Boston University School of Medicine, Boston, Massachusetts 02118
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Morris EM, Jackman MR, Meers GME, Johnson GC, Lopez JL, MacLean PS, Thyfault JP. Reduced hepatic mitochondrial respiration following acute high-fat diet is prevented by PGC-1α overexpression. Am J Physiol Gastrointest Liver Physiol 2013; 305:G868-80. [PMID: 24091599 PMCID: PMC3882433 DOI: 10.1152/ajpgi.00179.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Changes in substrate utilization and reduced mitochondrial respiratory capacity following exposure to energy-dense, high-fat diets (HFD) are putatively key components in the development of obesity-related metabolic disease. We examined the effect of a 3-day HFD on isolated liver mitochondrial respiration and whole body energy utilization in obesity-prone (OP) rats. We also examined if hepatic overexpression of peroxisomal proliferator-activated receptor-γ coactivator-1α (PGC-1α), a master regulator of mitochondrial respiratory capacity and biogenesis, would modify liver and whole body responses to the HFD. Acute, 3-day HFD (45% kcal) in OP rats resulted in increased daily energy intake, energy balance, weight gain, and adiposity, without an increase in liver triglyceride (triacylglycerol) accumulation. HFD-fed OP rats also displayed decreased whole body substrate switching from the dark to the light cycle, which was paired with reductions in hepatic mitochondrial respiration of multiple substrates in multiple respiratory states. Hepatic PGC-1α overexpression was observed to protect whole body substrate switching, as well as maintain mitochondrial respiration, following the acute HFD. Additionally, liver PGC-1α overexpression did not alter whole body dietary fatty acid oxidation but resulted in greater storage of dietary free fatty acids in liver lipid, primarily as triacylglycerol. Together, these data demonstrate that a short-term HFD can result in a decrease in metabolic flexibility and hepatic mitochondrial respiratory capacity in OP rats that is completely prevented by hepatic overexpression of PGC-1α.
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Affiliation(s)
- E. Matthew Morris
- 1Department of Internal Medicine-Gastroenterology, University of Missouri, Columbia, Missouri;
| | - Matthew R. Jackman
- 4Center for Human Nutrition, University of Colorado Denver, Denver, Colorado; ,6Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Colorado Denver, Denver, Colorado
| | - Grace M. E. Meers
- 1Department of Internal Medicine-Gastroenterology, University of Missouri, Columbia, Missouri;
| | - Ginger C. Johnson
- 4Center for Human Nutrition, University of Colorado Denver, Denver, Colorado; ,6Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Colorado Denver, Denver, Colorado
| | - Jordan L. Lopez
- 4Center for Human Nutrition, University of Colorado Denver, Denver, Colorado; ,6Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Colorado Denver, Denver, Colorado
| | - Paul S. MacLean
- 4Center for Human Nutrition, University of Colorado Denver, Denver, Colorado; ,5Department of Physiology and Biophysics, University of Colorado Denver, Denver, Colorado; and ,6Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Colorado Denver, Denver, Colorado
| | - John P. Thyfault
- 1Department of Internal Medicine-Gastroenterology, University of Missouri, Columbia, Missouri; ,2Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; ,3Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri;
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Differential Expressions of G0/G1 Switch Gene 2 and Comparative Gene Identification-58 are Associated with Fat Content in Bovine Muscle. Lipids 2013; 49:1-14. [DOI: 10.1007/s11745-013-3866-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 11/05/2013] [Indexed: 12/17/2022]
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73
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Yang M, Li S, Liu H, Yang G, Li L. Response to a long-term high-fat diet in the signature of genes involved in lipid metabolism in ApoE(-/-) mice. Am J Med Sci 2013; 346:211-5. [PMID: 23138120 DOI: 10.1097/maj.0b013e3182688026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
High-fat diet (HFD)-induced lipid metabolism disorders are a critical feature of diet-induced insulin resistance (IR); however, the mechanisms underlying the tissue-specific effects of HFDs on the signature of genes involved in lipid metabolism have not been fully investigated. Glucose homeostasis and insulin sensitivity were monitored in chow-fed and HFD-fed ApoE mice using the hyperinsulinemic-euglycemic clamp technique. The signatures of genes involved in lipid metabolism were measured in the liver and adipose tissues by quantitative real-time polymerase chain reaction and Western blot analysis. Long-term HFD (for 16 weeks) resulted in marked abnormalities in glucose and lipid metabolism and induced IR in ApoE mice. Long-term HFD also markedly upregulated the messenger RNA (mRNA) expression of insulin-induced gene-2, sterol regulatory element-binding protein cleavage-activating protein and sterol regulatory element-binding protein-1 in the liver and/or adipose tissues, in parallel with an elevated insulin-induced gene-2 protein in the liver. However, HFD markedly downregulated the mRNA expression of sterol regulatory element-binding protein-2, 3-hydroxy-3-methylglutaryl coenzyme A reductase and low-density lipoprotein receptor in the liver. Interestingly, long-term HFD markedly decreased adipose triglyceride lipase and peroxisome proliferator-activated receptor-γ mRNA, and adipose triglyceride lipase protein contents in the liver and/or adipose tissues. These findings provide a framework to understand the mechanisms by which long-term HFD regulates the gene signatures involved in lipid metabolism in the pathogenesis of diet-induced IR.
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Affiliation(s)
- Mengliu Yang
- The Key Laboratory of Laboratory Medical Diagnostics in the Ministry of Education and Department of Clinical Biochemistry, College of Laboratory Medicine, Chongqing Medical University, Chongqing, China
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Yogosawa S, Izumi T. Roles of activin receptor-like kinase 7 signaling and its target, peroxisome proliferator-activated receptor γ, in lean and obese adipocytes. Adipocyte 2013; 2:246-50. [PMID: 24052900 PMCID: PMC3774700 DOI: 10.4161/adip.24974] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/06/2013] [Accepted: 05/08/2013] [Indexed: 11/25/2022] Open
Abstract
We recently discovered a novel signaling pathway involving activin receptor-like kinase 7 (ALK7), one of the type I transforming growth factor-β receptors. ALK7 and activated Smads 2, 3, and 4 inhibit the master regulators of adipogenesis, CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ) specifically in differentiated adipocytes, but surprisingly increase both the adipocyte size and lipid content by suppressing lipolysis. Here, we show that, although both transcription factors are suppressed by ALK7 in either the obese or lean state, PPARγ, but not C/EBPα, is further suppressed under obesity through an ALK7-independent pathway. As a result, PPARγ and adipose lipolytic activities are severely downregulated in obesity. Reactivation of PPARγ by ALK7 inactivation leads to downregulation of inflammatory adipocytokines and upregulation of adiponectin. We propose that PPARγ promotes lipid turnover and remodeling by stimulating both triglyceride synthesis and breakdown in differentiated adipocytes. Finally, we discuss the physiological and evolutionary roles of the ALK7-signaling pathway and consider it as a potential target of therapy for obesity.
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75
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Identification of human patatin-like phospholipase domain-containing protein 1 and a mutant in human cervical cancer HeLa cells. Mol Biol Rep 2013; 40:5597-605. [PMID: 24057234 DOI: 10.1007/s11033-013-2661-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Accepted: 09/14/2013] [Indexed: 01/04/2023]
Abstract
Recently members of mammalian patatin-like phospholipase domain containing (PNPLA) protein family have attracted attention for their critical roles in diverse aspects of lipid metabolism and signal pathway. Until now little has been known about the characteristics of PNPLA1. Here, the full length coding cDNA sequence of human PNPLA1 (hPNPLA1) was cloned for the first time, which encoded a polypeptide with 532 amino acids containing the whole patatin domain. Tissue expression profiles analysis showed that low mRNA levels of hPNPLA1 existed in various tissues, except high expression in the digestive system, bone marrow and spleen. Subcellular distribution of hPNPLA1 tagged with green fluorescence protein mainly localized to lipid droplets. Furthermore, a nonsense mutation of PNPLA1 in human cervical cancer HeLa cells was identified. The hPNPLA1 mutant encoded a protein of 412 amino acids without the C-terminal domain and did not colocalize to lipid droplets, which suggested that the C-terminal region of hPNPLA1 affected lipid droplet binding. These results identified hPNPLA1 and a mutant in HeLa cells, and provided insights into the structure and function of PNPLA1.
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76
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Serr J, Li X, Lee K. The Regulation of Lipolysis in Adipose Tissue. JOURNAL OF ANIMAL SCIENCE AND TECHNOLOGY 2013. [DOI: 10.5187/jast.2013.55.4.303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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77
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Insulin inhibits lipolysis in adipocytes via the evolutionarily conserved mTORC1-Egr1-ATGL-mediated pathway. Mol Cell Biol 2013; 33:3659-66. [PMID: 23858058 DOI: 10.1128/mcb.01584-12] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
One of the basic functions of insulin in the body is to inhibit lipolysis in adipocytes. Recently, we have found that insulin inhibits lipolysis and promotes triglyceride storage by decreasing transcription of adipose triglyceride lipase via the mTORC1-mediated pathway (P. Chakrabarti et al., Diabetes 59:775-781, 2010), although the mechanism of this effect remained unknown. Here, we used a genetic screen in Saccharomyces cerevisiae in order to identify a transcription factor that mediates the effect of Tor1 on the expression of the ATGL ortholog in yeast. This factor, Msn4p, has homologues in mammalian cells that form a family of early growth response transcription factors. One member of the family, Egr1, is induced by insulin and nutrients and directly inhibits activity of the ATGL promoter in vitro and expression of ATGL in cultured adipocytes. Feeding animals a high-fat diet increases the activity of mTORC1 and the expression of Egr1 while decreasing ATGL levels in epididymal fat. We suggest that the evolutionarily conserved mTORC1-Egr1-ATGL regulatory pathway represents an important component of the antilipolytic effect of insulin in the mammalian organism.
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78
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Ren G, Beech C, Smas CM. The immunoglobulin superfamily protein differentiation of embryonic stem cells 1 (dies1) has a regulatory role in preadipocyte to adipocyte conversion. PLoS One 2013; 8:e65531. [PMID: 23799023 PMCID: PMC3684596 DOI: 10.1371/journal.pone.0065531] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 05/01/2013] [Indexed: 11/19/2022] Open
Abstract
Differentiation of Embryonic Stem Cells 1 (Dies1) was recently identified as a novel type I immunoglobulin (IgG) domain-containing plasma membrane protein important for effective differentiation of a murine pluripotent embryonic stem cell line. In this setting, Dies1 enhances bone morphogenetic protein 4 (BMP4) signaling. Here we show Dies1 transcript expression is induced ∼225-fold during in vitro adipogenesis of 3T3-L1 murine preadipocytes. Immunocytochemical imaging using ectopic expression of Flag-tagged Dies1 in 3T3-L1 adipocytes revealed localization to the adipocyte plasma membrane. Modulation of adipocyte phenotype with with tumor necrosis factor-α (TNFα) treatment or by siRNA knockdown of the master pro-adipogenic transcription factor peroxisome proliferator activated receptor gamma (PPARγ) resulted in a 90% and 60% reduction of Dies1 transcript levels, respectively. Moreover, siRNA-mediated Dies1 knockdown in 3T3-L1 preadipocytes inhibited adipogenic conversion. Such cultures had a 35% decrease in lipid content and a 45%–65% reduction in expression of key adipocyte transcripts, including that for PPARγ. The standard protocol for full in vitro adipogenic conversion of committed preadipocytes, such as 3T3-L1, does not include BMP4 treatment. Thus we posit the positive role of Dies1 in adipogenesis, unlike that for Dies1 in differentiation of embryonic stem cells, does not include its pro-BMP4 effects. In support of this idea, 3T3-L1 adipocytes knocked down for Dies1 did not evidence decreased phospho-Smad1 levels upon BMP4 exposure. qPCR analysis of Dies1 transcript in multiple murine and human tissues reveals high enrichment in white adipose tissue (WAT). Interestingly, we observed a 10-fold induction of Dies1 transcript in WAT of fasted vs. fed mice, suggesting a role for Dies1 in nutritional response of mature fat cells in vivo. Together our data identify Dies1 as a new differentiation-dependent adipocyte plasma membrane protein whose expression is required for effective adipogenesis and that may also play a role in regard to nutritional status in WAT.
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Affiliation(s)
- Gang Ren
- Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine, Toledo, Ohio, United States of America
| | - Cameron Beech
- Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine, Toledo, Ohio, United States of America
| | - Cynthia M. Smas
- Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine, Toledo, Ohio, United States of America
- Center for Diabetes and Endocrine Research, University of Toledo College of Medicine, Toledo, Ohio, United States of America
- * E-mail:
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79
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Wang X, Wang Y, Li Y. Adipose triglyceride lipase (ATGL) clone, expression pattern, and regulation by different lipid sources and lipid levels in large yellow croaker (Pseudosciaena crocea R.). MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2013; 15:197-205. [PMID: 22836232 DOI: 10.1007/s10126-012-9477-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 07/14/2012] [Indexed: 06/01/2023]
Abstract
Adipose triglyceride lipase (ATGL) was recently identified as a triglyceride (TG)-specific lipase. In this study, we first obtained from large yellow croaker fish a 1,820-bp (GenBank ID: HQ916211) ATGL cDNA fragment with a 141-bp 5'UTR, a 1,485-bp open reading frame, and a 194-bp 3'UTR. The predicted fish ATGL had 494 amino acids (GenBank ID: ADY89608) and a calculated molecular weight of 55.1 kDa. ATGL was highly expressed in liver and, to a lesser degree, in heart, muscle, and abdominal fat. ATGL gene expression was high at 4.5 g and then decreased at 157.9 g and increased again at 474.2 g. The effects of lipid levels and lipid sources on ATGL expression in vivo were also investigated. A high-lipid diet decreased ATGL expression in fish significantly (P < 0.01). Fish in soybean oil group exhibited significantly lower ATGL expression than fish in the fish oil and beef tallow groups (P < 0.01). These data enhance our understanding of ATGL in fish lipid metabolism.
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Affiliation(s)
- Xinxia Wang
- Institute of Feed Science, Zhejiang University, No. 388 Yuhangtang Road, Hangzhou, People's Republic of China
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80
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The role of triglyceride lipases in cancer associated cachexia. Trends Mol Med 2013; 19:292-301. [PMID: 23499576 PMCID: PMC3655383 DOI: 10.1016/j.molmed.2013.02.006] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Revised: 02/15/2013] [Accepted: 02/18/2013] [Indexed: 12/18/2022]
Abstract
Cancer associated cachexia (CAC) is a complex multiorgan syndrome frequently associated with various forms of cancer. Affected patients suffer from a dramatic loss of skeletal muscle and adipose tissue. Most cases are accompanied by anorexia, and nutritional supplements are not sufficient to stop or reverse its course. CAC impairs many forms of therapeutic interventions and accounts for 15-20% of all deaths of cancer patients. Recently, several studies have recognized the importance of lipid metabolism and triglyceride hydrolysis as a major metabolic pathway involved in the initiation and/or progression of CAC. In this review, we explore the contributions of the triglyceride lipases to CAC and discuss various factors modulating lipase activity.
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81
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Park Y, Kim Y, Kim J, Yoon KS, Clark J, Lee J, Park Y. Imidacloprid, a neonicotinoid insecticide, potentiates adipogenesis in 3T3-L1 adipocytes. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:255-9. [PMID: 23215241 DOI: 10.1021/jf3039814] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
There is emerging evidence that organochlorine and organophosphorus insecticide exposure may be linked to excessive weight gain and symptoms of diabetes. However, there is a lack of knowledge for other types of insecticides with potential influence on obesity and diabetes. Thus, the purpose of this investigation was to determine the role of imidacloprid, a neonicotinoid insecticide, in lipid metabolism by use of 3T3-L1 adipocytes. Imidacloprid treatment potentiated lipid accumulation in 3T3-L1 adipocytes and significantly increased expression of a key regulator of adipocyte differentiation and key regulators of lipogenesis. These results imply the involvement of imidacloprid in altered adipogenesis, resulting in increased fat accumulation. This finding is the first report of a potential link between neonicotinoid insecticide exposure and lipid accumulation in adipocytes. Further in vivo as well as epidemiological studies will be required before we can extrapolate these findings to a potential contribution of imidacloprid in human obesity.
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Affiliation(s)
- Yooheon Park
- Department of Food Science, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States.
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82
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Yasmeen R, Reichert B, Deiuliis J, Yang F, Lynch A, Meyers J, Sharlach M, Shin S, Volz KS, Green KB, Lee K, Alder H, Duester G, Zechner R, Rajagopalan S, Ziouzenkova O. Autocrine function of aldehyde dehydrogenase 1 as a determinant of diet- and sex-specific differences in visceral adiposity. Diabetes 2013; 62:124-36. [PMID: 22933113 PMCID: PMC3526050 DOI: 10.2337/db11-1779] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mechanisms for sex- and depot-specific fat formation are unclear. We investigated the role of retinoic acid (RA) production by aldehyde dehydrogenase 1 (Aldh1a1, -a2, and -a3), the major RA-producing enzymes, on sex-specific fat depot formation. Female Aldh1a1(-/-) mice, but not males, were resistant to high-fat (HF) diet-induced visceral adipose formation, whereas subcutaneous fat was reduced similarly in both groups. Sexual dimorphism in visceral fat (VF) was attributable to elevated adipose triglyceride lipase (Atgl) protein expression localized in clusters of multilocular uncoupling protein 1 (Ucp1)-positive cells in female Aldh1a1(-/-) mice compared with males. Estrogen decreased Aldh1a3 expression, limiting conversion of retinaldehyde (Rald) to RA. Rald effectively induced Atgl levels via nongenomic mechanisms, demonstrating indirect regulation by estrogen. Experiments in transgenic mice expressing an RA receptor response element (RARE-lacZ) revealed HF diet-induced RARE activation in VF of females but not males. In humans, stromal cells isolated from VF of obese subjects also expressed higher levels of Aldh1 enzymes compared with lean subjects. Our data suggest that an HF diet mediates VF formation through a sex-specific autocrine Aldh1 switch, in which Rald-mediated lipolysis in Ucp1-positive visceral adipocytes is replaced by RA-mediated lipid accumulation. Our data suggest that Aldh1 is a potential target for sex-specific antiobesity therapy.
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Affiliation(s)
- Rumana Yasmeen
- Department of Human Nutrition, The Ohio State University, Columbus, Ohio
| | - Barbara Reichert
- Department of Human Nutrition, The Ohio State University, Columbus, Ohio
| | - Jeffrey Deiuliis
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Fangping Yang
- Department of Human Nutrition, The Ohio State University, Columbus, Ohio
| | - Alisha Lynch
- Department of Human Nutrition, The Ohio State University, Columbus, Ohio
| | - Joseph Meyers
- Department of Human Nutrition, The Ohio State University, Columbus, Ohio
| | - Molly Sharlach
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California
| | - Sangsu Shin
- Department of Animal Sciences, The Ohio State University, Columbus, Ohio
| | - Katharina S. Volz
- Department of Human Nutrition, The Ohio State University, Columbus, Ohio
| | - Kari B. Green
- Mass Spectrometry and Proteomics Facility, The Ohio State University, Columbus, Ohio
| | - Kichoon Lee
- Department of Animal Sciences, The Ohio State University, Columbus, Ohio
| | - Hansjuerg Alder
- Nucleic Acid Shared Resource, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
| | - Gregg Duester
- Development and Aging Program, Sanford-Burnham Medical Research Institute, La Jolla, California
| | - Rudolf Zechner
- Institute of Molecular Biosciences, Karl Franzens University, Graz, Austria
| | - Sanjay Rajagopalan
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Ouliana Ziouzenkova
- Department of Human Nutrition, The Ohio State University, Columbus, Ohio
- Corresponding author: Ouliana Ziouzenkova,
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83
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Yogosawa S, Mizutani S, Ogawa Y, Izumi T. Activin receptor-like kinase 7 suppresses lipolysis to accumulate fat in obesity through downregulation of peroxisome proliferator-activated receptor γ and C/EBPα. Diabetes 2013; 62:115-23. [PMID: 22933117 PMCID: PMC3526038 DOI: 10.2337/db12-0295] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We previously identified a quantitative trait locus for adiposity, non-insulin-dependent diabetes 5 (Nidd5), on mouse chromosome 2. In the current study, we identified the actual genetic alteration at Nidd5 as a nonsense mutation of the Acvr1c gene encoding activin receptor-like kinase 7 (ALK7), one of the type I transforming growth factor-β receptors, which results in a COOH-terminal deletion of the kinase domain. We further showed that the ALK7 dysfunction causes increased lipolysis in adipocytes and leads to decreased fat accumulation. Conversely, ALK7 activation inhibits lipolysis by suppressing the expression of adipose lipases. ALK7 and activated Smads repress those lipases by downregulating peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein (C/EBP) α. Although PPARγ and C/EBPα act as adipogenic transcription factors during adipocyte differentiation, they are lipolytic in sum in differentiated adipocytes and are downregulated by ALK7 in obesity to accumulate fat. Under the obese state, ALK7 deficiency improves glucose tolerance and insulin sensitivity by preferentially increasing fat combustion in mice. These findings have uncovered a net lipolytic function of PPARγ and C/EBPα in differentiated adipocytes and point to the ALK7-signaling pathway that is activated in obesity as a potential target of medical intervention.
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Affiliation(s)
- Satomi Yogosawa
- Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Shin Mizutani
- Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Yoshihiro Ogawa
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Tetsuro Izumi
- Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
- Corresponding author: Tetsuro Izumi,
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84
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Yamashita-Sugahara Y, Tokuzawa Y, Nakachi Y, Kanesaki-Yatsuka Y, Matsumoto M, Mizuno Y, Okazaki Y. Fam57b (family with sequence similarity 57, member B), a novel peroxisome proliferator-activated receptor γ target gene that regulates adipogenesis through ceramide synthesis. J Biol Chem 2012; 288:4522-37. [PMID: 23275342 DOI: 10.1074/jbc.m112.440792] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
This report identifies a novel gene encoding Fam57b (family with sequence similarity 57, member B) as a novel peroxisome proliferator-activated receptor γ (PPARγ)-responsive transmembrane gene that is related to obesity. The gene was identified based on an integrated bioinformatics analysis of the following three expression profiling data sets: adipocyte differentiation of mouse stromal cells (ST2 cells), adipose tissues from obesity mice, and siRNA-mediated knockdown of Pparγ using ST2 cells. Fam57b consists of three variants expressed from different promoters and contains a Tram-Lag1-CLN8 domain that is related to ceramide synthase. Reporter and ChIP assays showed that Fam57b variant 2 is a bona fide PPARγ target gene in ST2 cells. Fam57b was up-regulated during adipocyte differentiation, suggesting that FAM57B is involved in this process. Surprisingly, FAM57B overexpression inhibited adipogenesis, and siRNA-mediated knockdown promoted adipocyte differentiation. Analysis of the ceramide content by lipid assay found that ceramides were in fact augmented in FAM57B-overexpressing ST2 cells. We also confirmed that ceramide inhibits adipogenesis. Therefore, the aforementioned results of FAM57B overexpression and siRNA experiments are reconciled by ceramide synthesis. In summary, we present in vitro evidence showing that PPARγ regulates Fam57b transcription during the adipogenesis of ST2 cells. In addition, our results suggest that PPARγ activation contributes to the regulation of ceramide metabolism during adipogenesis via FAM57B.
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Affiliation(s)
- Yzumi Yamashita-Sugahara
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka City, Saitama 350-1241, Japan
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85
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Karbowska J, Kochan Z. Fat-reducing effects of dehydroepiandrosterone involve upregulation of ATGL and HSL expression, and stimulation of lipolysis in adipose tissue. Steroids 2012; 77:1359-65. [PMID: 22951290 DOI: 10.1016/j.steroids.2012.08.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 08/07/2012] [Indexed: 12/31/2022]
Abstract
Dehydroepiandrosterone (DHEA) reduces body fat in rodents and humans, and increases glycerol release from isolated rat epididymal adipocytes and human visceral adipose tissue explants. It suggests that DHEA stimulates triglyceride hydrolysis in adipose tissue; however, the mechanisms underlying this action are still unclear. We examined the effects of DHEA on the expression of adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL), the key enzymes of lipolysis, in rat epididymal white adipose tissue (eWAT). Male Wistar rats were fed a diet containing 0.6% DHEA for 2 weeks and eWAT was analyzed for mRNA and protein expression of ATGL and HSL, as well as mRNA expression of peroxisome proliferator-activated receptor γ 2 (PPARγ2) and its downstream target fatty acid translocase (FAT). Glycerol release from eWAT explants and serum free fatty acids (FFA) were also measured. Rats that received DHEA gained less weight, had 23% lower eWAT mass and 31% higher serum FFA levels than controls. Cultured explants of eWAT from DHEA-treated rats released 81% more glycerol than those from control rats. DHEA administration upregulated ATGL mRNA (1.62-fold, P<0.05) and protein (1.78-fold, P<0.05) expression as well as augmented HSL mRNA levels (1.36-fold, P<0.05) and Ser660 phosphorylation of HSL (2.49-fold, P<0.05). PPARγ2 and FAT mRNA levels were also increased in DHEA-treated rats (1.61-fold, P<0.05 and 2.16-fold, P<0.05; respectively). Moreover, ATGL, HSL, and FAT mRNA levels were positively correlated with PPARγ2 expression. This study demonstrates that DHEA promotes lipid mobilization in adipose tissue by increasing the expression and activity of ATGL and HSL. The effects of DHEA appear to be mediated, at least in part, via PPARγ2 activation, which in turn upregulates ATGL and HSL gene expression.
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Affiliation(s)
- Joanna Karbowska
- Department of Biochemistry, Medical University of Gdansk, Debinki 1, 80-211 Gdansk, Poland.
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86
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Fernández-Galilea M, Pérez-Matute P, Prieto-Hontoria PL, Martinez JA, Moreno-Aliaga MJ. Effects of lipoic acid on lipolysis in 3T3-L1 adipocytes. J Lipid Res 2012; 53:2296-306. [PMID: 22941773 PMCID: PMC3465999 DOI: 10.1194/jlr.m027086] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 08/31/2012] [Indexed: 12/22/2022] Open
Abstract
Lipoic acid (LA) is a naturally occurring compound with beneficial effects on obesity. The aim of this study was to evaluate its effects on lipolysis in 3T3-L1 adipocytes and the mechanisms involved. Our results revealed that LA induced a dose- and time-dependent lipolytic action, which was reversed by pretreatment with the c-Jun N-terminal kinase inhibitor SP600125, the PKA inhibitor H89, and the AMP-activated protein kinase activator AICAR. In contrast, the PI3K/Akt inhibitor LY294002 and the PDE3B antagonist cilostamide enhanced LA-induced lipolysis. LA treatment for 1 h did not modify total protein content of hormone-sensitive lipase (HSL) but significantly increased the phosphorylation of HSL at Ser(563) and at Ser(660), which was reversed by H89. LA treatment also induced a marked increase in PKA-mediated perilipin phosphorylation. LA did not significantly modify the protein levels of adipose triglyceride lipase or its activator comparative gene identification 58 (CGI-58) and inhibitor G(0)/G(1) switch gene 2 (G0S2). Furthermore, LA caused a significant inhibition of adipose-specific phospholipase A2 (AdPLA) protein and mRNA levels in parallel with a decrease in the amount of prostaglandin E(2) released and an increase in cAMP content. Together, these data suggest that the lipolytic actions of LA are mainly mediated by phosphorylation of HSL through cAMP-mediated activation of protein kinase A probably through the inhibition of AdPLA and prostaglandin E(2).
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Affiliation(s)
- Marta Fernández-Galilea
- Department of Nutrition, Food Science, Physiology and Toxicology, University of Navarra, Pamplona, Spain; and
| | - Patricia Pérez-Matute
- Department of Nutrition, Food Science, Physiology and Toxicology, University of Navarra, Pamplona, Spain; and
- HIV and Associated Metabolic Alterations Unit, Infectious Diseases Area, Center for Biomedical Research of La Rioja (CIBIR), Logroño, Spain
| | - Pedro L Prieto-Hontoria
- Department of Nutrition, Food Science, Physiology and Toxicology, University of Navarra, Pamplona, Spain; and
| | - J Alfredo Martinez
- Department of Nutrition, Food Science, Physiology and Toxicology, University of Navarra, Pamplona, Spain; and
| | - Maria J Moreno-Aliaga
- Department of Nutrition, Food Science, Physiology and Toxicology, University of Navarra, Pamplona, Spain; and
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87
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Wang X, Huang M, Wang Y. The effect of insulin, TNFα and DHA on the proliferation, differentiation and lipolysis of preadipocytes isolated from large yellow croaker (Pseudosciaena Crocea R.). PLoS One 2012; 7:e48069. [PMID: 23110176 PMCID: PMC3482209 DOI: 10.1371/journal.pone.0048069] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2012] [Accepted: 09/20/2012] [Indexed: 01/19/2023] Open
Abstract
Fish final product can be affected by excessive lipid accumulation. Therefore, it is important to develop strategies to control obesity in cultivated fish to strengthen the sustainability of the aquaculture industry. As in mammals, the development of adiposity in fish depends on hormonal, cytokine and dietary factors. In this study, we investigated the proliferation and differentiation of preadipocytes isolated from the large yellow croaker and examined the effects of critical factors such as insulin, TNFα and DHA on the proliferation, differentiation and lipolysis of adipocytes. Preadipocytes were isolated by collagenase digestion, after which their proliferation was evaluated. The differentiation process was optimized by assaying glycerol-3-phosphate dehydrogenase (GPDH) activity. Oil red O staining and electron microscopy were performed to visualize the accumulated triacylglycerol. Gene transcript levels were measured using SYBR green quantitative real-time PCR. Insulin promoted preadipocytes proliferation, stimulated cell differentiation and decreased lipolysis of mature adipocytes. TNFα and DHA inhibited cell proliferation and differentiation. While TNFα stimulated mature adipocyte lipolysis, DHA showed no lipolytic effect on adipocytes. The expressions of adipose triglyceride lipase (ATGL), fatty acid synthase (FAS), lipoprotein lipase (LPL) and peroxisome proliferator-activated receptor α, γ (PPARα, PPARγ) were quantified during preadipocytes differentiation and adipocytes lipolysis to partly explain the regulation mechanisms. In summary, the results of this study indicated that although preadipocytes proliferation and the differentiation process in large yellow croaker are similar to these processes in mammals, the effects of critical factors such as insulin, TNFα and DHA on fish adipocytes development are not exactly the same. Our findings fill in the gaps in the basic data regarding the effects of critical factors on adiposity development in fish and will facilitate the further study of molecular mechanism by which these factors act in fish and the application of this knowledge to eventually control obesity in cultured species.
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Affiliation(s)
- Xinxia Wang
- Institute of Feed Science, Zhejiang University, Hangzhou, Zhejiang Province, People’s Republic of China
| | - Ming Huang
- Institute of Feed Science, Zhejiang University, Hangzhou, Zhejiang Province, People’s Republic of China
| | - Yizhen Wang
- Institute of Feed Science, Zhejiang University, Hangzhou, Zhejiang Province, People’s Republic of China
- * E-mail:
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88
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Koslowski R, Kasper M, Schaal K, Knels L, Lange M, Bernhard W. Surfactant metabolism and anti-oxidative capacity in hyperoxic neonatal rat lungs: effects of keratinocyte growth factor on gene expression in vivo. Histochem Cell Biol 2012; 139:461-72. [DOI: 10.1007/s00418-012-1038-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2012] [Indexed: 01/10/2023]
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89
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90
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Ren G, Kim JY, Smas CM. Identification of RIFL, a novel adipocyte-enriched insulin target gene with a role in lipid metabolism. Am J Physiol Endocrinol Metab 2012; 303:E334-51. [PMID: 22569073 PMCID: PMC3423120 DOI: 10.1152/ajpendo.00084.2012] [Citation(s) in RCA: 224] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
To identify new genes that are important in fat metabolism, we utilized the Lexicon-Genentech knockout database of genes encoding transmembrane and secreted factors and whole murine genome transcriptional profiling data that we generated for 3T3-L1 in vitro adipogenesis. Cross-referencing null models evidencing metabolic phenotypes with genes induced in adipogenesis led to identification of a new gene, which we named RIFL (refeeding induced fat and liver). RIFL-null mice have serum triglyceride levels approximately one-third of wild type. RIFL transcript is induced >100-fold during 3T3-L1 adipogenesis and is also increased markedly during adipogenesis of murine and human primary preadipocytes. siRNA-mediated knockdown of RIFL during 3T3-L1 adipogenesis results in an ~35% decrease in adipocyte triglyceride content. Murine RIFL transcript is highly enriched in white and brown adipose tissue and liver. Fractionation of WAT reveals that RIFL transcript is exclusive to adipocytes with a lack of expression in stromal-vascular cells. Nutritional and hormonal studies are consistent with a prolipogenic function for RIFL. There is evidence of an approximately eightfold increase in RIFL transcript level in WAT in ob/ob mice compared with wild-type mice. RIFL transcript level in WAT and liver is increased ~80- and 12-fold, respectively, following refeeding of fasted mice. Treatment of 3T3-L1 adipocytes with insulin increases RIFL transcript ≤35-fold, whereas agents that stimulate lipolysis downregulate RIFL. Interestingly, the 198-amino acid RIFL protein is predicted to be secreted and shows ~30% overall conservation with the NH(2)-terminal half of angiopoietin-like 3, a liver-secreted protein that impacts lipid metabolism. In summary, our data suggest that RIFL is an important new regulator of lipid metabolism.
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Affiliation(s)
- Gang Ren
- Department of Biochemistry and Cancer Biology and Center for Diabetes and Endocrine Research, University of Toledo College of Medicine, Toledo, OH 43614, USA
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91
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Tanigawa K, Degang Y, Kawashima A, Akama T, Yoshihara A, Ishido Y, Makino M, Ishii N, Suzuki K. Essential role of hormone-sensitive lipase (HSL) in the maintenance of lipid storage in Mycobacterium leprae-infected macrophages. Microb Pathog 2012; 52:285-91. [PMID: 22553833 DOI: 10.1016/j.micpath.2012.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Mycobacterium leprae (M. leprae), the causative agent of leprosy, parasitizes within the foamy or enlarged phagosome of macrophages where rich lipids accumulate. Although the mechanisms for lipid accumulation in the phagosome have been clarified, it is still unclear how such large amounts of lipids escape degradation. To further explore underlying mechanisms involved in lipid catabolism in M. leprae-infected host cells, we examined the expression of hormone-sensitive lipase (HSL), a key enzyme in fatty acid mobilization and lipolysis, in human macrophage THP-1 cells. We found that infection by live M. leprae significantly suppressed HSL expression levels. This suppression was not observed with dead M. leprae or latex beads. Macrophage activation by peptidoglycan (PGN), the ligand for toll-like receptor 2 (TLR2), increased HSL expression; however, live M. leprae suppressed this increase. HSL expression was abolished in the slit-skin smear specimens from patients with lepromatous and borderline leprosy. In addition, the recovery of HSL expression was observed in patients who experienced a lepra reaction, which is a cell-mediated, delayed-type hypersensitivity immune response, or in patients who were successfully treated with multi-drug therapy. These results suggest that M. leprae suppresses lipid degradation through inhibition of HSL expression, and that the monitoring of HSL mRNA levels in slit-skin smear specimens may be a useful indicator of patient prognosis.
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Affiliation(s)
- Kazunari Tanigawa
- Leprosy Research Center, National Institute of Infectious Diseases, 4-2-1 Aoba-cho, Higashimurayama, Tokyo 189-0002, Japan
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92
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Ogasawara J, Sakurai T, Kizaki T, Ishibashi Y, Izawa T, Sumitani Y, Ishida H, Radak Z, Haga S, Ohno H. Higher levels of ATGL are associated with exercise-induced enhancement of lipolysis in rat epididymal adipocytes. PLoS One 2012; 7:e40876. [PMID: 22815850 PMCID: PMC3397928 DOI: 10.1371/journal.pone.0040876] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 06/18/2012] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND In adipose cells, adipose triglyceride lipase (ATGL) catalyzes the first step in adipocyte triacylglyceride hydrolysis, thereby regulating both basal and hormone-stimulated lipolysis. However, little is known about the molecular mechanism(s) underlying habitual exercise-induced adaptive modulation of ATGL in white adipocytes via alteration in transcription regulator and lipolytic cofactors. METHODOLOGY/PRINCIPAL RESULTS Male Wistar rats were randomly divided into 2 groups a sedentary control group (CG) and a habitual exercise group (EG). The EG was subjected to running on a treadmill set at 5 days per week for 9 weeks. The CG was not subjected to running on a treadmill. In the EG, levels of ATGL mRNA and protein were elevated with a significant increase in lipolysis compared with the CG, accompanied by a significant increase in associations of CGI-58 with ATGL protein. Under these conditions, an upregulation of peroxisome proliferation-activated receptorg-2 (PPARg-2) was observed. In the EG, the addition of rosiglitazone further significantly increased the levels of ATGL protein compared with the CG. However, attenuated levels of the ATGL protein in adipocytes were obtained by the addition of insulin, which is known to inhibit the expression of ATGL, in both types of groups. Actually, levels of plasma insulin were significantly reduced in the EG compared with the CG. CONCLUSIONS These data suggest that elevated levels of ATGL are involved in the exercise-induced enhancement of lipolysis in primary adipocytes. The exact mechanism(s) underlying this phenomenon is associated, at least in part, with upregulated transcriptional activation of PPARg-2. In addition, exercise-induced lower circulation levels of insulin also correlate with habitual exercise-induced higher levels of ATGL in primary adipocytes.
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Affiliation(s)
- Junetsu Ogasawara
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Tokyo, Japan.
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93
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Rodriguez-Cuenca S, Carobbio S, Vidal-Puig A. Ablation of Pparg2 impairs lipolysis and reveals murine strain differences in lipolytic responses. FASEB J 2012; 26:1835-44. [PMID: 22319009 DOI: 10.1096/fj.11-193631] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
We investigate the role of PPARg2 as a regulator of lipolysis and its interaction with specific genetic backgrounds as determinants of the severity of the metabolic phenotype. This question was prompted by our previous characterization of Pparg2-knockout (KO) mice that revealed striking genetic background differences in the severity of their adipose tissue development impairment and dysfunction. Analysis is done of pharmacological lipolytic responses combined with protein and mRNA expression analysis in isolated adipocytes from the gonadal pad of Pparg2-KO mice in 2 different backgrounds (129S6/SvEv and C57BL/6). We provide evidence of the prolipolytic role of PPARg2 and how these effects are modulated by genetic background, leading to differential severity of metabolic syndrome. Specifically, ablation of Pparg2 reduced both basal and stimulated lipolysis as a result of impaired β(3)-AR signaling, a general defect at downstream lipases, and increased insulin-mediated antilipolytic action. Of note, the C57BL/6 Pparg2-KO mice exhibited more active lipolytic response to catecholamines than 129S6/SvEv Pparg2-KO mice with respect to their wild-type controls. Pparg2-KO mice exhibit metabolic inflexibility resulting from the combined effects of impaired lipid deposition coupled with impaired lipolytic lipid mobilization. The genetic background-dependent differences in lipolysis may account for Pparg2-KO background-specific differences in the severity of their metabolic disturbances. Our findings identify the isoform Pparg2 as an integrator of the adipose lipid metabolism coordinating both anabolic and catabolic processes.
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Affiliation(s)
- Sergio Rodriguez-Cuenca
- Department of Clinical Biochemistry, Metabolic Research Laboratories, Institute of Metabolic Science, NIHR Cambridge Biomedical Research Centre, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
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94
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Samuel VT, Shulman GI. Mechanisms for insulin resistance: common threads and missing links. Cell 2012; 148:852-71. [PMID: 22385956 DOI: 10.1016/j.cell.2012.02.017] [Citation(s) in RCA: 1469] [Impact Index Per Article: 122.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Indexed: 02/07/2023]
Abstract
Insulin resistance is a complex metabolic disorder that defies explanation by a single etiological pathway. Accumulation of ectopic lipid metabolites, activation of the unfolded protein response (UPR) pathway, and innate immune pathways have all been implicated in the pathogenesis of insulin resistance. However, these pathways are also closely linked to changes in fatty acid uptake, lipogenesis, and energy expenditure that can impact ectopic lipid deposition. Ultimately, these cellular changes may converge to promote the accumulation of specific lipid metabolites (diacylglycerols and/or ceramides) in liver and skeletal muscle, a common final pathway leading to impaired insulin signaling and insulin resistance.
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Affiliation(s)
- Varman T Samuel
- Department of Medicine, Yale University School of Medicine, New Haven, CT 06510, USA.
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95
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Sun X, Tang Y, Tan X, Li Q, Zhong W, Sun X, Jia W, McClain CJ, Zhou Z. Activation of peroxisome proliferator-activated receptor-γ by rosiglitazone improves lipid homeostasis at the adipose tissue-liver axis in ethanol-fed mice. Am J Physiol Gastrointest Liver Physiol 2012; 302:G548-57. [PMID: 22173916 PMCID: PMC3311430 DOI: 10.1152/ajpgi.00342.2011] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 12/14/2011] [Indexed: 02/06/2023]
Abstract
The development of alcohol-induced fatty liver is associated with a reduction of white adipose tissue (WAT). Peroxisome proliferator-activated receptor (PPAR)-γ prominently distributes in the WAT and plays a crucial role in maintaining adiposity. The present study investigated the effects of PPAR-γ activation by rosiglitazone on lipid homeostasis at the adipose tissue-liver axis. Adult C57BL/6 male mice were pair fed liquid diet containing ethanol or isocaloric maltose dextrin for 8 wk with or without rosiglitazone supplementation to ethanol-fed mice for the last 3 wk. Ethanol exposure downregulated adipose PPAR-γ gene and reduced the WAT mass in association with induction of inflammation, which was attenuated by rosiglitazone. Ethanol exposure stimulated lipolysis but reduced fatty acid uptake capacity in association with dysregulation of lipid metabolism genes. Rosiglitazone normalized adipose gene expression and corrected ethanol-induced lipid dyshomeostasis. Ethanol exposure induced steatosis and upregulated inflammatory genes in the liver, which were attenuated by rosiglitazone. Hepatic peroxisomal fatty acid β-oxidation was suppressed by ethanol in associated with inhibition of acyl-coenzyme A oxidase 1. Rosiglitazone elevated plasma adiponectin level and normalized peroxisomal fatty acid β-oxidation rate. However, rosiglitazone did not affect ethanol-reduced very low-density lipoprotein secretion from the liver. These results demonstrated that activation of PPAR-γ by rosiglitazone reverses ethanol-induced adipose dysfunction and lipid dyshomeostasis at the WAT-liver axis, thereby abrogating alcoholic fatty liver.
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Affiliation(s)
- Xiuhua Sun
- Department of Nutrition, University of North Carolina at Greensboro, USA
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96
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Lorente-Cebrián S, Bustos M, Marti A, Fernández-Galilea M, Martinez JA, Moreno-Aliaga MJ. Eicosapentaenoic acid inhibits tumour necrosis factor-α-induced lipolysis in murine cultured adipocytes. J Nutr Biochem 2012; 23:218-27. [DOI: 10.1016/j.jnutbio.2010.11.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2010] [Revised: 10/29/2010] [Accepted: 11/22/2010] [Indexed: 12/11/2022]
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97
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A low-protein, high-carbohydrate diet increases fatty acid uptake and reduces norepinephrine-induced lipolysis in rat retroperitoneal white adipose tissue. Lipids 2012; 47:279-89. [PMID: 22228227 DOI: 10.1007/s11745-011-3648-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2011] [Accepted: 12/08/2011] [Indexed: 10/14/2022]
Abstract
A low-protein, high-carbohydrate (LPHC) diet for 15 days increased the lipid content in the carcass and adipose tissues of rats. The aim of this work was to investigate the mechanisms of this lipid increase in the retroperitoneal white adipose tissue (RWAT) of these animals. The LPHC diet induced an approximately two- and tenfold increase in serum corticosterone and TNF-α, respectively. The rate of de novo fatty acid (FA) synthesis in vivo was reduced (50%) in LPHC rats, and the lipoprotein lipase activity increased (100%). In addition, glycerokinase activity increased (60%), and the phosphoenolpyruvate carboxykinase content decreased (27%). Basal [U-¹⁴C]-glucose incorporation into glycerol-triacylglycerol did not differ between the groups; however, in the presence of insulin, [U-¹⁴C]-glucose incorporation increased by 124% in adipocytes from only control rats. The reductions in IRS1 and AKT content as well as AKT phosphorylation in the RWAT from LPHC rats and the absence of an insulin response suggest that these adipocytes have reduced insulin sensitivity. The increase in NE turnover by 45% and the lack of a lipolytic response to NE in adipocytes from LPHC rats imply catecholamine resistance. The data reveal that the increase in fat storage in the RWAT of LPHC rats results from an increase in FA uptake from circulating lipoproteins and glycerol phosphorylation, which is accompanied by an impaired lipolysis that is activated by NE.
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98
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Etschmaier K, Becker T, Eichmann TO, Schweinzer C, Scholler M, Tam-Amersdorfer C, Poeckl M, Schuligoi R, Kober A, Chirackal Manavalan AP, Rechberger GN, Streith IE, Zechner R, Zimmermann R, Panzenboeck U. Adipose triglyceride lipase affects triacylglycerol metabolism at brain barriers. J Neurochem 2011; 119:1016-28. [PMID: 21951135 DOI: 10.1111/j.1471-4159.2011.07498.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Currently, little is known about the role of intracellular triacylglycerol (TAG) lipases in the brain. Adipose triglyceride lipase (ATGL) is encoded by the PNPLA2 gene and catalyzes the rate-limiting step of lipolysis. In this study, we investigated the effects of ATGL deficiency on brain lipid metabolism in vivo using an established knock-out mouse model (ATGL-ko). A moderate decrease in TAG hydrolase activity detected in ATGL-ko versus wild-type brain tissue was accompanied by a 14-fold increase in TAG levels and an altered composition of TAG-associated fatty acids in ATGL-ko brains. Oil Red O staining revealed a severe accumulation of neutral lipids associated to cerebrovascular cells and in distinct brain regions namely the ependymal cell layer and the choroid plexus along the ventricular system. In situ hybridization histochemistry identified ATGL mRNA expression in ependymal cells, the choroid plexus, pyramidal cells of the hippocampus, and the dentate gyrus. Our findings imply that ATGL is involved in brain fatty acid metabolism, particularly in regions mediating transport and exchange processes: the brain-CSF interface, the blood-CSF barrier, and the blood-brain barrier.
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Affiliation(s)
- Karoline Etschmaier
- Institute of Pathophysiology and Immunology, Medical University of Graz, Graz, Austria
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99
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Liu LR, Lin SP, Chen CC, Chen YJ, Tai CC, Chang SC, Juang RH, Tseng YW, Liu BH, Mersmann HJ, Shen TL, Ding ST. Serum amyloid A induces lipolysis by downregulating perilipin through ERK1/2 and PKA signaling pathways. Obesity (Silver Spring) 2011; 19:2301-9. [PMID: 21701568 DOI: 10.1038/oby.2011.176] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Serum amyloid A (SAA) is not only an apolipoprotein, but also a member of the adipokine family with potential to enhance lipolysis. The purpose of this study was to explore how SAA facilitates lipolysis in porcine adipocytes. We found that SAA increased the phosphorylation of perilipin and hormone-sensitive lipase (HSL) after 12-h treatment and decreased perilipin expression after 24-h treatment, and these effects were prevented by extracellular signal-regulated kinase (ERK) or protein kinase A (PKA) inhibitors in primary adipocyte cell culture. SAA treatment decreased HSL and adipose triglyceride lipase (ATGL) expression. SAA treatment also activated ERK and PKA by increasing the phosphorylation of these kinases. Moreover, SAA significantly increased porcine adipocyte glycerol release and lipase activity, which was inhibited by either ERK (PD98059) or PKA (H89) inhibitors, suggesting that ERK and PKA were involved in mediating SAA enhanced lipolysis. SAA downregulated the expression of peroxisome proliferator-activated receptor γ (PPARγ) mRNA, which was reversed by the ERK inhibitor. We performed a porcine perilipin promoter assay in differentiated 3T3-L1 adipocytes and found that SAA reduced the porcine perilipin promoter specifically through the function of its PPAR response element (PPRE), and this effect was reversed by the ERK inhibitor. These findings demonstrate that SAA-induced lipolysis is a result of downregulation of perilipin and activation of HSL via ERK/PPARγ and PKA signaling pathways. The finding could lead to developing new strategies for reducing human obesity.
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Affiliation(s)
- Lih R Liu
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan
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100
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Elevated Adipose Triglyceride Lipase in Newly Diagnosed Type 2 Diabetes Mellitus With Hypertension. Am J Med Sci 2011; 342:452-5. [DOI: 10.1097/maj.0b013e318218482f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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