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Chirivi M, Cortes D, Rendon CJ, Contreras GA. Lipolysis inhibition as a treatment of clinical ketosis in dairy cows: Effects on adipose tissue metabolic and immune responses. J Dairy Sci 2024; 107:5104-5121. [PMID: 38278290 DOI: 10.3168/jds.2023-23998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 12/27/2023] [Indexed: 01/28/2024]
Abstract
Dairy cows with clinical ketosis (CK) exhibit excessive adipose tissue (AT) lipolysis and systemic inflammation. Lipolysis in cows can be induced by the canonical (hormonally induced) and inflammatory lipolytic pathways. Currently, the most common treatment for CK is oral propylene glycol (PG); however, PG does not reduce lipolysis or inflammation. Niacin (NIA) can reduce the activation of canonical lipolysis, whereas cyclooxygenase inhibitors such as flunixin meglumine (FM) can limit inflammation and inhibit the inflammatory lipolytic pathway. The objective of this study was to determine the effects of including NIA and FM in the standard PG treatment for postpartum CK on AT function. Multiparous Jersey cows (n = 18; 7.1 ± 3.8 DIM) were selected from a commercial dairy. Inclusion criteria were CK symptoms (lethargy, depressed appetite, and drop in milk yield) and high blood levels of BHB (≥1.2 mmol/L). Cows with CK were randomly assigned to one of 3 treatments: (1) PG: 310 g administered orally once per day for 5 d, (2) PG+NIA: 24 g administered orally once per day for 3 d, and (3) PG+NIA+FM: 1.1 mg/kg administered IV once per day for 3 d. Healthy control cows (HC; n = 6) matched by lactation and DIM (±2 d) were sampled. Subcutaneous AT explants were collected at d 0 and d 7 relative to enrollment. To assess AT insulin sensitivity, explants were treated with insulin (1 µL/L) during lipolysis stimulation with a β-adrenergic receptor agonist (isoproterenol, 1 µM). Lipolysis was quantified by glycerol release in the media. Lipid mobilization and inflammatory gene networks were evaluated using quantitative PCR. Protein biomarkers of lipolysis, insulin signaling, and AT inflammation, including hormone-sensitive lipase, protein kinase B (Akt), and ERK1/2, were quantified by capillary immunoassays. Flow cytometry of AT cellular components was used to characterize macrophage inflammatory phenotypes. Statistical significance was determined by a nonparametric t-test when 2 groups (HC vs. CK) were analyzed and an ANOVA test with Tukey adjustment when 3 treatment groups (PG vs. PG+NIA vs. PG+NIA+FM) were evaluated. At d 0, AT from CK cows showed higher mRNA expression of lipolytic enzymes ABHD5, LIPE, and LPL, as well as increased phosphorylation of hormone-sensitive lipase compared with HC. At d 0, insulin reduced lipolysis by 41% ± 8% in AT from HC, but CK cows were unresponsive (-2.9 ± 4%). Adipose tissue from CK cows exhibited reduced Akt phosphorylation compared with HC. Cows with CK had increased AT expression of inflammatory gene markers, including CCL2, IL8, IL10, TLR4, and TNF, along with ERK1/2 phosphorylation. Adipose tissue from CK cows showed increased macrophage infiltration compared with HC. By d 7, AT from PG+NIA+FM cows had a more robust response to insulin, as evidenced by reduced glycerol release (36.5% ± 8% compared with PG at 26.9% ± 7% and PG+NIA at 7.4% ± 8%) and enhanced phosphorylation of Akt. By d 7, PG+NIA+FM cows presented lower inflammatory markers, including ERK1/2 phosphorylation, and reduced macrophage infiltration, compared with PG and PG+NIA. These data suggest that including NIA and FM in CK treatment improves AT insulin sensitivity and reduces AT inflammation and macrophage infiltration.
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Affiliation(s)
- Miguel Chirivi
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI 48824
| | - Daniela Cortes
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI 48824
| | - C Javier Rendon
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI 48824
| | - G Andres Contreras
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI 48824.
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2
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Kang Q, Zhu X, Ren D, Ky A, MacDougald OA, O'Rourke RW, Rui L. Adipose METTL14-Elicited N 6 -Methyladenosine Promotes Obesity, Insulin Resistance, and NAFLD Through Suppressing β Adrenergic Signaling and Lipolysis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2301645. [PMID: 37526326 PMCID: PMC10558699 DOI: 10.1002/advs.202301645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 06/08/2023] [Indexed: 08/02/2023]
Abstract
White adipose tissue (WAT) lipolysis releases free fatty acids as a key energy substance to support metabolism in fasting, cold exposure, and exercise. Atgl, in concert with Cgi-58, catalyzes the first lipolytic reaction. The sympathetic nervous system (SNS) stimulates lipolysis via neurotransmitter norepinephrine that activates adipocyte β adrenergic receptors (Adrb1-3). In obesity, adipose Adrb signaling and lipolysis are impaired, contributing to pathogenic WAT expansion; however, the underling mechanism remains poorly understood. Recent studies highlight importance of N6 -methyladenosine (m6A)-based RNA modification in health and disease. METTL14 heterodimerizes with METTL3 to form an RNA methyltransferase complex that installs m6A in transcripts. Here, this work shows that adipose Mettl3 and Mettl14 are influenced by fasting, refeeding, and insulin, and are upregulated in high fat diet (HFD) induced obesity. Adipose Adrb2, Adrb3, Atgl, and Cgi-58 transcript m6A contents are elevated in obesity. Mettl14 ablation decreases these transcripts' m6A contents and increases their translations and protein levels in adipocytes, thereby increasing Adrb signaling and lipolysis. Mice with adipocyte-specific deletion of Mettl14 are resistant to HFD-induced obesity, insulin resistance, glucose intolerance, and nonalcoholic fatty liver disease (NAFLD). These results unravel a METTL14/m6A/translation pathway governing Adrb signaling and lipolysis. METTL14/m6A-based epitranscriptomic reprogramming impairs adipose Adrb signaling and lipolysis, promoting obesity, NAFLD, and metabolic disease.
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Affiliation(s)
- Qianqian Kang
- Department of Molecular and Integrative PhysiologyUniversity of Michigan Medical SchoolAnn ArborMI48109USA
- Elizabeth Weiser Caswell Diabetes InstituteUniversity of MichiganAnn ArborMI48109USA
| | - Xiaorong Zhu
- Department of Molecular and Integrative PhysiologyUniversity of Michigan Medical SchoolAnn ArborMI48109USA
- Department of EndocrinologyBeijing Tongren HospitalCapital Medical UniversityBeijing Diabetes InstituteBeijing100730China
| | - Decheng Ren
- Department of MedicineUniversity of ChicagoChicagoIL60637USA
| | - Alexander Ky
- Department of SurgeryUniversity of Michigan Medical SchoolAnn ArborMI48109USA
| | - Ormond A. MacDougald
- Department of Molecular and Integrative PhysiologyUniversity of Michigan Medical SchoolAnn ArborMI48109USA
- Elizabeth Weiser Caswell Diabetes InstituteUniversity of MichiganAnn ArborMI48109USA
- Department of Internal MedicineUniversity of Michigan Medical SchoolAnn ArborMI48109USA
| | - Robert W. O'Rourke
- Department of SurgeryUniversity of Michigan Medical SchoolAnn ArborMI48109USA
- Department of SurgeryVeterans Affairs Ann Arbor Healthcare SystemAn ArborMI48105USA
| | - Liangyou Rui
- Department of Molecular and Integrative PhysiologyUniversity of Michigan Medical SchoolAnn ArborMI48109USA
- Elizabeth Weiser Caswell Diabetes InstituteUniversity of MichiganAnn ArborMI48109USA
- Department of Internal MedicineUniversity of Michigan Medical SchoolAnn ArborMI48109USA
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3
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Romero AR, Mu A, Ayres JS. Adipose triglyceride lipase mediates lipolysis and lipid mobilization in response to iron-mediated negative energy balance. iScience 2022; 25:103941. [PMID: 35265813 PMCID: PMC8899412 DOI: 10.1016/j.isci.2022.103941] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 12/23/2021] [Accepted: 02/14/2022] [Indexed: 11/09/2022] Open
Abstract
Maintenance of energy balance is essential for overall organismal health. Mammals have evolved complex regulatory mechanisms that control energy intake and expenditure. Traditionally, studies have focused on understanding the role of macronutrient physiology in energy balance. In the present study, we examined the role of the essential micronutrient iron in regulating energy balance. We found that a short course of dietary iron caused a negative energy balance resulting in a severe whole body wasting phenotype. This disruption in energy balance was because of impaired intestinal nutrient absorption. In response to dietary iron-induced negative energy balance, adipose triglyceride lipase (ATGL) was necessary for wasting of subcutaneous white adipose tissue and lipid mobilization. Fat-specific ATGL deficiency protected mice from fat wasting, but caused a severe cachectic response in mice when fed iron. Our work reveals a mechanism for micronutrient control of lipolysis that is necessary for regulating mammalian energy balance.
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Affiliation(s)
- Alicia R. Romero
- Molecular and Systems Physiology Lab, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA,Gene Expression Lab, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA,Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA,Division of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Andre Mu
- Molecular and Systems Physiology Lab, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA,Gene Expression Lab, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA,Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Janelle S. Ayres
- Molecular and Systems Physiology Lab, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA,Gene Expression Lab, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA,Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA,Corresponding author
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4
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Chirivi M, Rendon CJ, Myers MN, Prom CM, Roy S, Sen A, Lock AL, Contreras GA. Lipopolysaccharide induces lipolysis and insulin resistance in adipose tissue from dairy cows. J Dairy Sci 2021; 105:842-855. [PMID: 34696909 DOI: 10.3168/jds.2021-20855] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 09/05/2021] [Indexed: 01/05/2023]
Abstract
Intense and protracted adipose tissue (AT) fat mobilization increases the risk of metabolic and inflammatory periparturient diseases in dairy cows. This vulnerability increases when cows have endotoxemia-common during periparturient diseases such as mastitis, metritis, and pneumonia-but the mechanisms are unknown. Fat mobilization intensity is determined by the balance between lipolysis and lipogenesis. Around parturition, the rate of lipolysis surpasses that of lipogenesis, leading to enhanced free fatty acid release into the circulation. We hypothesized that exposure to endotoxin (ET) increases AT lipolysis by activation of classic and inflammatory lipolytic pathways and reduction of insulin sensitivity. In experiment 1, subcutaneous AT (SCAT) explants were collected from periparturient (n = 12) Holstein cows at 11 ± 3.6 d (mean ± SE) before calving, and 6 ± 1 d and 13 ± 1.4 d after parturition. Explants were treated with the endotoxin lipopolysaccharide (LPS; 20 µg/mL; basal = 0 µg/mL) for 3 h. The effect of LPS on lipolysis was assessed in the presence of the β-adrenergic agonist and promoter of lipolysis isoproterenol (ISO; 1 µM; LPS+ISO). In experiment 2, SCAT explants were harvested from 24 nonlactating, nongestating multiparous Holstein dairy cows and exposed to the same treatments as in experiment 1 for 3 and 7 h. The effect of LPS on the antilipolytic responses induced by insulin (INS = 1 µL/L, LPS+INS) was established during ISO stimulation [ISO+INS, LPS+ISO+INS]. The characterization of lipolysis included the quantification of glycerol release and the assessment of markers of lipase activity [adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and phosphorylated HSL Ser563 (pHSL)], and insulin pathway activation (AKT, pAKT) using capillary electrophoresis. Inflammatory gene networks were evaluated by real-time quantitative PCR. In periparturient cows, LPS increased AT lipolysis by 67 ± 12% at 3 h across all time points compared with basal. In nonlactating cows, LPS was an effective lipolytic agent at 3 h and 7 h, increasing glycerol release by 115 ± 18% and 68.7 ± 16%, respectively, relative to basal. In experiment 2, LPS enhanced ATGL activity with minimal HSL activation at 3 h. In contrast, at 7 h, LPS increased HSL phosphorylation (i.e., HSL activity) by 123 ± 11%. The LPS-induced HSL lipolytic activity at 7 h coincided with the activation of the MEK/ERK inflammatory pathway. In experiment 2, INS reduced the lipolytic effect of ISO (ISO+INS: -63 ± 18%) and LPS (LPS+INS: -45.2 ± 18%) at 3 h. However, the antilipolytic effect of INS was lost in the presence of LPS at 7 h (LPS+INS: -16.3 ± 16%) and LPS+ISO+INS at 3 and 7 h (-3.84 ± 23.6% and -21.2 ± 14.6%). Accordingly, LPS reduced pAKT:AKT (0.11 ± 0.07) compared with basal (0.18 ± 0.05) at 7 h. Our results indicated that exposure to LPS activated the classic and inflammatory lipolytic pathways and reduced insulin sensitivity in SCAT. These data provide evidence that during endotoxemia, dairy cows may be more susceptible to lipolysis dysregulation and loss of adipocyte sensitivity to the antilipolytic action of insulin.
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Affiliation(s)
- Miguel Chirivi
- Department of Large Animal Clinical Science, Michigan State University, East Lansing 48824
| | - C Javier Rendon
- Department of Large Animal Clinical Science, Michigan State University, East Lansing 48824
| | - Madison N Myers
- Department of Large Animal Clinical Science, Michigan State University, East Lansing 48824
| | - Crystal M Prom
- Department of Animal Sciences, Michigan State University, East Lansing 48824
| | - Sambit Roy
- Department of Animal Sciences, Michigan State University, East Lansing 48824
| | - Aritro Sen
- Department of Animal Sciences, Michigan State University, East Lansing 48824
| | - Adam L Lock
- Department of Animal Sciences, Michigan State University, East Lansing 48824
| | - G Andres Contreras
- Department of Large Animal Clinical Science, Michigan State University, East Lansing 48824.
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5
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Genomic and Non-Genomic Actions of Glucocorticoids on Adipose Tissue Lipid Metabolism. Int J Mol Sci 2021; 22:ijms22168503. [PMID: 34445209 PMCID: PMC8395154 DOI: 10.3390/ijms22168503] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/01/2021] [Accepted: 08/04/2021] [Indexed: 12/15/2022] Open
Abstract
Glucocorticoids (GCs) are hormones that aid the body under stress by regulating glucose and free fatty acids. GCs maintain energy homeostasis in multiple tissues, including those in the liver and skeletal muscle, white adipose tissue (WAT), and brown adipose tissue (BAT). WAT stores energy as triglycerides, while BAT uses fatty acids for heat generation. The multiple genomic and non-genomic pathways in GC signaling vary with exposure duration, location (adipose tissue depot), and species. Genomic effects occur directly through the cytosolic GC receptor (GR), regulating the expression of proteins related to lipid metabolism, such as ATGL and HSL. Non-genomic effects act through mechanisms often independent of the cytosolic GR and happen shortly after GC exposure. Studying the effects of GCs on adipose tissue breakdown and generation (lipolysis and adipogenesis) leads to insights for treatment of adipose-related diseases, such as obesity, coronary disease, and cancer, but has led to controversy among researchers, largely due to the complexity of the process. This paper reviews the recent literature on the genomic and non-genomic effects of GCs on WAT and BAT lipolysis and proposes research to address the many gaps in knowledge related to GC activity and its effects on disease.
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6
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Barroso Oquendo M, Siegel-Axel D, Gerst F, Lorza-Gil E, Moller A, Wagner R, Machann J, Fend F, Königsrainer A, Heni M, Häring HU, Ullrich S, Birkenfeld AL. Pancreatic fat cells of humans with type 2 diabetes display reduced adipogenic and lipolytic activity. Am J Physiol Cell Physiol 2021; 320:C1000-C1012. [PMID: 33788629 DOI: 10.1152/ajpcell.00595.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Obesity, especially visceral fat accumulation, increases the risk of type 2 diabetes (T2D). The purpose of this study was to investigate the impact of T2D on the pancreatic fat depot. Pancreatic fat pads from 17 partial pancreatectomized patients (PPP) were collected, pancreatic preadipocytes isolated, and in vitro differentiated. Patients were grouped using HbA1c into normal glucose tolerant (NGT), prediabetic (PD), and T2D. Transcriptome profiles of preadipocytes and adipocytes were assessed by RNAseq. Insulin sensitivity was estimated by quantifying AKT phosphorylation on Western blots. Lipogenic capacity was assessed with oil red O staining, lipolytic activity via fatty acid release. Secreted factors were measured using ELISA. Comparative transcriptome analysis of preadipocytes and adipocytes indicates defective upregulation of genes governing adipogenesis (NR1H3), lipogenesis (FASN, SCD, ELOVL6, and FADS1), and lipolysis (LIPE) during differentiation of cells from T2D-PPP. In addition, the ratio of leptin/adiponectin mRNA was higher in T2D than in NGT-PPP. Preadipocytes and adipocytes of NGT-PPP were more insulin sensitive than T2D-PPP cells in regard to AKT phosphorylation. Triglyceride accumulation was similar in NGT and T2D adipocytes. Despite a high expression of the receptors NPR1 and NPR2 in NGT and T2D adipocytes, lipolysis was stimulated by ANP 1.74-fold in NGT cells only. This stimulation was further increased by the PDE5 inhibitor dipyridamole (3.09-fold). Dipyridamole and forskolin increased lipolysis receptor independently 1.88-fold and 1.48-fold, respectively, solely in NGT cells. In conclusion, the metabolic status persistently affects differentiation and lipolysis of pancreatic adipocytes. These alterations could aggravate the development of T2D.
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Affiliation(s)
- Morgana Barroso Oquendo
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine IV, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Dorothea Siegel-Axel
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine IV, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Felicia Gerst
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard-Karls-University of Tübingen, Neuherberg, Germany.,Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine IV, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Estela Lorza-Gil
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard-Karls-University of Tübingen, Neuherberg, Germany.,Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine IV, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Anja Moller
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard-Karls-University of Tübingen, Neuherberg, Germany.,Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine IV, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Robert Wagner
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard-Karls-University of Tübingen, Neuherberg, Germany.,Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine IV, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Jürgen Machann
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard-Karls-University of Tübingen, Neuherberg, Germany.,Section on Experimental Radiology, Department of Diagnostic and Interventional Radiology, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Falko Fend
- Institute of Pathology and Neuropathology, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Alfred Königsrainer
- Department of General, Visceral and Transplant Surgery, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Martin Heni
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard-Karls-University of Tübingen, Neuherberg, Germany.,Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine IV, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany.,Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Hans-Ulrich Häring
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard-Karls-University of Tübingen, Neuherberg, Germany.,Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine IV, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Susanne Ullrich
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard-Karls-University of Tübingen, Neuherberg, Germany.,Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine IV, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Andreas L Birkenfeld
- German Center for Diabetes Research (DZD e.V.), Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard-Karls-University of Tübingen, Neuherberg, Germany.,Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine IV, University Hospital of Eberhard-Karls-University Tübingen, Tübingen, Germany
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7
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The autocrine role of FGF21 in cultured adipocytes. Biochem J 2020; 477:2477-2487. [PMID: 32648929 DOI: 10.1042/bcj20200220] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 06/15/2020] [Accepted: 06/16/2020] [Indexed: 12/12/2022]
Abstract
Exposure to cold alters glucose and lipid metabolism of white and brown adipose tissue via activation of β-adrenergic receptor (ADRB). Fibroblast growth factor 21 (FGF21) has been shown to be locally released from adipose tissue upon activation of ADRBs and FGF21 increases glucose uptake in adipocytes. Therefore, FGF21 may play an autocrine role in inducing glucose uptake after β-adrenergic stimulation. To determine the putative autocrine role of FGF21, we stimulated three different types of adipocytes in vitro with Isoprenaline (Iso), an ADRB agonist, in the presence or absence of the FGF receptor (FGFR) inhibitor PD 173074. The three cell lines represent white (3T3-L1), beige (ME3) and brown (WT-1) adipocyte phenotypes, respectively. All three cells systems expressed β-klotho (KLB) and FGFR1 after differentiation and treatment with recombinant FGF21 increased glucose uptake in 3T3-L1 and WT-1 adipocytes, while no significant effect was observed in ME3. Oppositely, all three cell lines responded to Iso treatment and an increase in glucose uptake and lipolysis were observed. Interestingly, in response to the Iso treatment only the WT-1 adipocytes showed an increase in FGF21 in the medium. This was consistent with the observation that PD 173074 decreased Iso-induced glucose uptake in the WT-1 adipocytes. This suggests that FGF21 plays an autocrine role and increases glucose uptake after β-adrenergic stimulation of cultured brown WT-1 adipocytes.
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Høyer KL, Høgild ML, List EO, Lee KY, Kissinger E, Sharma R, Erik Magnusson N, Puri V, Kopchick JJ, Jørgensen JOL, Jessen N. The acute effects of growth hormone in adipose tissue is associated with suppression of antilipolytic signals. Physiol Rep 2020; 8:e14373. [PMID: 32073221 PMCID: PMC7029434 DOI: 10.14814/phy2.14373] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 01/19/2020] [Accepted: 01/21/2020] [Indexed: 02/07/2023] Open
Abstract
AIM Since GH stimulates lipolysis in vivo after a 2-hr lag phase, we studied whether this involves GH signaling and gene expression in adipose tissue (AT). METHODS Human subjects (n = 9) each underwent intravenous exposure to GH versus saline with measurement of serum FFA, and GH signaling, gene array, and protein in AT biopsies after 30-120 min. Human data were corroborated in adipose-specific GH receptor knockout (FaGHRKO) mice versus wild-type mice. Expression of candidate genes identified in the array were investigated in 3T3-L1 adipocytes. RESULTS GH increased serum FFA and AT phosphorylation of STAT5b in human subjects. This was replicated in wild-type mice, but not in FaGHRKO mice. The array identified 53 GH-regulated genes, and Ingenuity Pathway analysis showed downregulation of PDE3b, an insulin-dependent antilipolytic signal, upregulation of PTEN that inhibits insulin-dependent antilipolysis, and downregulation of G0S2 and RASD1, both encoding antilipolytic proteins. This was confirmed in 3T3-L1 adipocytes, except for PDE3B, including reciprocal effects of GH and insulin on mRNA expression of PTEN, RASD1, and G0S2. CONCLUSION (a) GH directly stimulates AT lipolysis in a GHR-dependent manner, (b) this involves suppression of antilipolytic signals at the level of gene expression, (c) the underlying GH signaling pathways remain to be defined.
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Affiliation(s)
- Katrine L. Høyer
- Medical Research LaboratoryDepartment of Clinical Medicine, HealthAarhus UniversityAarhusDenmark
- Department of EndocrinologyAarhus University HospitalAarhusDenmark
| | - Morten L. Høgild
- Medical Research LaboratoryDepartment of Clinical Medicine, HealthAarhus UniversityAarhusDenmark
- Department of EndocrinologyAarhus University HospitalAarhusDenmark
| | - Edward O. List
- The Edison Biotechnology InstituteAthensOHUSA
- Heritage College of Osteopathic MedicineOhio UniversityAthensOHUSA
| | - Kevin Y. Lee
- Heritage College of Osteopathic MedicineOhio UniversityAthensOHUSA
| | - Emily Kissinger
- Heritage College of Osteopathic MedicineOhio UniversityAthensOHUSA
| | - Rita Sharma
- Heritage College of Osteopathic MedicineOhio UniversityAthensOHUSA
| | - Nils Erik Magnusson
- Medical Research LaboratoryDepartment of Clinical Medicine, HealthAarhus UniversityAarhusDenmark
- Department of EndocrinologyAarhus University HospitalAarhusDenmark
| | - Vishwajeet Puri
- Heritage College of Osteopathic MedicineOhio UniversityAthensOHUSA
| | - John J. Kopchick
- The Edison Biotechnology InstituteAthensOHUSA
- Heritage College of Osteopathic MedicineOhio UniversityAthensOHUSA
| | - Jens O. L. Jørgensen
- Medical Research LaboratoryDepartment of Clinical Medicine, HealthAarhus UniversityAarhusDenmark
- Department of EndocrinologyAarhus University HospitalAarhusDenmark
| | - Niels Jessen
- Department of Clinical PharmacologyUniversity of AarhusAarhusDenmark
- Department of BiomedicineAarhus UniversityAarhusDenmark
- Steno Diabetes Center AarhusAarhus University HospitalAarhusDenmark
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9
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Rondini EA, Mladenovic-Lucas L, Roush WR, Halvorsen GT, Green AE, Granneman JG. Novel Pharmacological Probes Reveal ABHD5 as a Locus of Lipolysis Control in White and Brown Adipocytes. J Pharmacol Exp Ther 2017; 363:367-376. [PMID: 28928121 PMCID: PMC5698943 DOI: 10.1124/jpet.117.243253] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 09/09/2017] [Indexed: 12/30/2022] Open
Abstract
Current knowledge regarding acute regulation of adipocyte lipolysis is largely based on receptor-mediated activation or inhibition of pathways that influence intracellular levels of cAMP, thereby affecting protein kinase A (PKA) activity. We recently identified synthetic ligands of α-β-hydrolase domain containing 5 (ABHD5) that directly activate adipose triglyceride lipase (ATGL) by dissociating ABHD5 from its inhibitory regulator, perilipin-1 (PLIN1). In the current study, we used these novel ligands to determine the direct contribution of ABHD5 to various aspects of lipolysis control in white (3T3-L1) and brown adipocytes. ABHD5 ligands stimulated adipocyte lipolysis without affecting PKA-dependent phosphorylation on consensus sites of PLIN1 or hormone-sensitive lipase (HSL). Cotreatment of adipocytes with synthetic ABHD5 ligands did not alter the potency or maximal lipolysis efficacy of the β-adrenergic receptor (ADRB) agonist isoproterenol (ISO), indicating that both target a common pool of ABHD5. Reducing ADRB/PKA signaling with insulin or desensitizing ADRB suppressed lipolysis responses to a subsequent challenge with ISO, but not to ABHD5 ligands. Lastly, despite strong treatment differences in PKA-dependent phosphorylation of HSL, we found that ligand-mediated activation of ABHD5 led to complete triglyceride hydrolysis, which predominantly involved ATGL, but also HSL. These results indicate that the overall pattern of lipolysis controlled by ABHD5 ligands is similar to that of isoproterenol, and that ABHD5 plays a central role in the regulation of adipocyte lipolysis. As lipolysis is critical for adaptive thermogenesis and in catabolic tissue remodeling, ABHD5 ligands may provide a means of activating these processes under conditions where receptor signaling is compromised.
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Affiliation(s)
- Elizabeth A Rondini
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan (E.A.R., L.M.-L., J.G.G.); Department of Chemistry, Scripps Research Institute, Jupiter, Florida (W.R.R., G.T.H.); and Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada (A.E.G.)
| | - Ljiljana Mladenovic-Lucas
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan (E.A.R., L.M.-L., J.G.G.); Department of Chemistry, Scripps Research Institute, Jupiter, Florida (W.R.R., G.T.H.); and Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada (A.E.G.)
| | - William R Roush
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan (E.A.R., L.M.-L., J.G.G.); Department of Chemistry, Scripps Research Institute, Jupiter, Florida (W.R.R., G.T.H.); and Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada (A.E.G.)
| | - Geoff T Halvorsen
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan (E.A.R., L.M.-L., J.G.G.); Department of Chemistry, Scripps Research Institute, Jupiter, Florida (W.R.R., G.T.H.); and Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada (A.E.G.)
| | - Alex E Green
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan (E.A.R., L.M.-L., J.G.G.); Department of Chemistry, Scripps Research Institute, Jupiter, Florida (W.R.R., G.T.H.); and Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada (A.E.G.)
| | - James G Granneman
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan (E.A.R., L.M.-L., J.G.G.); Department of Chemistry, Scripps Research Institute, Jupiter, Florida (W.R.R., G.T.H.); and Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada (A.E.G.)
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10
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Insulin action and resistance in obesity and type 2 diabetes. Nat Med 2017; 23:804-814. [PMID: 28697184 DOI: 10.1038/nm.4350] [Citation(s) in RCA: 757] [Impact Index Per Article: 108.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 05/11/2017] [Indexed: 12/12/2022]
Abstract
Nutritional excess is a major forerunner of type 2 diabetes. It enhances the secretion of insulin, but attenuates insulin's metabolic actions in the liver, skeletal muscle and adipose tissue. However, conflicting evidence indicates a lack of knowledge of the timing of these events during the development of obesity and diabetes, pointing to a key gap in our understanding of metabolic disease. This Perspective reviews alternate viewpoints and recent results on the temporal and mechanistic connections between hyperinsulinemia, obesity and insulin resistance. Although much attention has addressed early steps in the insulin signaling cascade, insulin resistance in obesity seems to be largely elicited downstream of these steps. New findings also connect insulin resistance to extensive metabolic cross-talk between the liver, adipose tissue, pancreas and skeletal muscle. These and other advances over the past 5 years offer exciting opportunities and daunting challenges for the development of new therapeutic strategies for the treatment of type 2 diabetes.
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11
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Kuo T, Chen TC, Lee RA, Nguyen NHT, Broughton AE, Zhang D, Wang JC. Pik3r1 Is Required for Glucocorticoid-Induced Perilipin 1 Phosphorylation in Lipid Droplet for Adipocyte Lipolysis. Diabetes 2017; 66:1601-1610. [PMID: 28292967 PMCID: PMC5440017 DOI: 10.2337/db16-0831] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 03/09/2017] [Indexed: 12/26/2022]
Abstract
Glucocorticoids promote lipolysis in white adipose tissue (WAT) to adapt to energy demands under stress, whereas superfluous lipolysis causes metabolic disorders, including dyslipidemia and hepatic steatosis. Glucocorticoid-induced lipolysis requires the phosphorylation of cytosolic hormone-sensitive lipase (HSL) and perilipin 1 (Plin1) in the lipid droplet by protein kinase A (PKA). We previously identified Pik3r1 (also called p85α) as a glucocorticoid receptor target gene. Here, we found that glucocorticoids increased HSL phosphorylation, but not Plin1 phosphorylation, in adipose tissue-specific Pik3r1-null (AKO) mice. Furthermore, in lipid droplets, the phosphorylation of HSL and Plin1 and the levels of catalytic and regulatory subunits of PKA were increased by glucocorticoids in wild-type mice. However, these effects were attenuated in AKO mice. In agreement with reduced WAT lipolysis, glucocorticoid- initiated hepatic steatosis and hypertriglyceridemia were improved in AKO mice. Our data demonstrated a novel role of Pik3r1 that was independent of the regulatory function of phosphoinositide 3-kinase in mediating the metabolic action of glucocorticoids. Thus, the inhibition of Pik3r1 in adipocytes could alleviate lipid disorders caused by excess glucocorticoid exposure.
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Affiliation(s)
- Taiyi Kuo
- Endocrinology Graduate Program, University of California, Berkeley, Berkeley, CA
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA
| | - Tzu-Chieh Chen
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA
- Metabolic Biology Graduate Program, University of California, Berkeley, Berkeley, CA
| | - Rebecca A Lee
- Endocrinology Graduate Program, University of California, Berkeley, Berkeley, CA
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA
| | - Nguyen Huynh Thao Nguyen
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA
| | - Augusta E Broughton
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA
| | - Danyun Zhang
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA
| | - Jen-Chywan Wang
- Endocrinology Graduate Program, University of California, Berkeley, Berkeley, CA
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA
- Metabolic Biology Graduate Program, University of California, Berkeley, Berkeley, CA
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12
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Liu Y, Sheng L, Xiong Y, Shen H, Liu Y, Rui L. Liver NF-κB-Inducing Kinase Promotes Liver Steatosis and Glucose Counterregulation in Male Mice With Obesity. Endocrinology 2017; 158:1207-1216. [PMID: 28379340 PMCID: PMC5460833 DOI: 10.1210/en.2016-1582] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 02/10/2017] [Indexed: 12/20/2022]
Abstract
Obesity is associated with chronic inflammation and liver steatoses. Numerous proinflammatory cytokines have been reported to regulate liver glucose and lipid metabolism, thus contributing to the pathogenesis of liver steatosis and/or metabolic dysfunction. Nuclear factor-κB-inducing kinase (NIK) is stimulated by many cytokines and mediates activation of the noncanonical nuclear factor-κB pathway. We previously reported that liver NIK is aberrantly activated in obesity; inactivation of NIK by overexpressing dominant negative NIK(KA) suppresses hepatic glucose production. In the present study, we generated conditional NIK knockout mice using the Cre/loxp system. Mice with hepatocyte-specific or hematopoietic lineage-specific deletion of NIK were normal with either normal chow diet or high-fat diet (HFD) conditions. In contrast, deletion of NIK in the liver, including both hepatocytes and immune cells, protected against HFD-induced liver steatosis and attenuated hepatic glucose production. Mechanistically, deletion of liver NIK suppressed liver inflammation and lipogenic programs, thus contributing to protection against liver steatosis. Liver NIK also downregulated cyclic nucleotide phosphodiesterases, thereby augmenting the cyclic adenosine monophosphate/protein kinase A pathway and glucagon-stimulated hepatic glucose production. Together, our data suggest that NIK pathways in both hepatocytes and immune cells act in concert to promote liver steatosis and glucose production in the setting of obesity.
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Affiliation(s)
- Yan Liu
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Liang Sheng
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Yi Xiong
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Hong Shen
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Yong Liu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, The Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Liangyou Rui
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109
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13
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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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14
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Morgan A, Mooney K, Mc Auley M. Obesity and the dysregulation of fatty acid metabolism: implications for healthy aging. Expert Rev Endocrinol Metab 2016; 11:501-510. [PMID: 30058918 DOI: 10.1080/17446651.2016.1245141] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The population of the world is aging. In 2010, an estimated 524 million people were aged 65 years or older representing eight percent of the global population. By 2050, this number is expected to nearly triple to approximately 1.5 billion, 16 percent of the world's population. Although people are living longer, the quality of their lives are often compromised due to ill-health. Areas covered: Of the conditions which compromise health as we age, obesity is at the forefront. Over half of the global older population were overweight or obese in 2010, significantly increasing the risk of a range of metabolic diseases. Although, it is well recognised excessive calorie intake is a fundamental driver of adipose tissue dysfunction, the relationship between obesity; intrinsic aging; and fat metabolism is less understood. In this review we discuss the intersection between obesity, aging and the factors which contribute to the dysregulation of whole-body fat metabolism. Expert commentary: Being obese disrupts an array of physiological systems and there is significant crosstalk among these. Moreover it is imperative to acknowledge the contribution intrinsic aging makes to the dysregulation of these systems and the onset of disease.
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Affiliation(s)
- Amy Morgan
- a Department of Chemical Engineering , University of Chester, Thornton Science Park , Chester , UK
| | - Kathleen Mooney
- b Faculty of Health and Social Care , Edge Hill University , Lancashire , UK
| | - Mark Mc Auley
- a Department of Chemical Engineering , University of Chester, Thornton Science Park , Chester , UK
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15
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Kapoor S, Waldmann H, Ziegler S. Novel approaches to map small molecule–target interactions. Bioorg Med Chem 2016; 24:3232-45. [DOI: 10.1016/j.bmc.2016.05.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 05/10/2016] [Accepted: 05/12/2016] [Indexed: 10/24/2022]
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16
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Richards L, Li M, van Esch B, Garssen J, Folkerts G. The effects of short-chain fatty acids on the cardiovascular system. PHARMANUTRITION 2016. [DOI: 10.1016/j.phanu.2016.02.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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17
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Mulumba M, Granata R, Marleau S, Ong H. QRFP-43 inhibits lipolysis by preventing ligand-induced complex formation between perilipin A, caveolin-1, the catalytic subunit of protein kinase and hormone-sensitive lipase in 3T3-L1 adipocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:657-66. [PMID: 25677823 DOI: 10.1016/j.bbalip.2015.02.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 01/21/2015] [Accepted: 02/02/2015] [Indexed: 11/30/2022]
Abstract
QRFP (RFamide) peptides are neuropeptides involved in food intake and adiposity regulation in rodents. We have previously shown that QRFP-43 (43RFa) and QRFP-26 (26RFa) inhibited isoproterenol (ISO)-induced lipolysis in adipocytes. However, the antilipolytic signaling pathways activated by QRFP peptides have not been investigated. In the present study, 3T3-L1 adipocytes were used to identify the main pathways involved in QRFP-43 decreasing ISO-induced lipolysis. Our results show that QRFP-43 reduced ISO-induced phosphorylation of perilipin A (PLIN) and hormone-sensitive lipase (HSL) on Ser660 by 43 and 25%, respectively, but increased Akt phosphorylation by 44%. However, the inhibition of phosphodiesterase 3B (PDE3B), a regulator of lipolysis activated by Akt, did not reverse the antilipolytic effect of QRFP-43. PDE3B inhibition reversed the decrease of Ser660 HSL phosphorylation associated with QRFP-43 antilipolytic effect. QRFP-43 also prevented PKC activation and ISO-induced Src kinases activation leading to the inhibition of the caveolin-1 (CAV-1) translocation on lipid droplets. Indeed, QRFP-43 attenuated phorbol 12-myristate 13-acetate-induced lipolysis and ISO-induced extracellular signal-regulated and Src kinases by 28, 37 and 48%, respectively. The attenuation of ISO-induced lipolysis by QRFP-43 was associated with a decrease of phosphorylated Ser660 HSL, PKA-catalytic (PKA-c) subunit and CAV-1 translocation on lipid droplets by 37, 50 and 46%, respectively. The decrease in ISO-induced CAV-1 and PKA-c translocation was associated with a reduction of PLIN phosphorylation by 44% in QRFP-43-treated adipocytes. These results suggest that QRFP-43 attenuated ISO-induced lipolysis by preventing the formation of an active complex on lipid droplets and the activation of Src kinases and PKC.
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Affiliation(s)
- Mukandila Mulumba
- Faculty of Pharmacy, Université de Montréal C.P. 6128, Succursale Centre-Ville, Montréal, Québec H3C 3J7, Canada
| | - Riccarda Granata
- Laboratory of Molecular and Cellular Endocrinology, Department of Medical Sciences, University of Turin, Corso Dogliotti 14, Turin 10126, Italy
| | - Sylvie Marleau
- Faculty of Pharmacy, Université de Montréal C.P. 6128, Succursale Centre-Ville, Montréal, Québec H3C 3J7, Canada
| | - Huy Ong
- Faculty of Pharmacy, Université de Montréal C.P. 6128, Succursale Centre-Ville, Montréal, Québec H3C 3J7, Canada.
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18
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Rodrigues T, Lin YC, Hartenfeller M, Renner S, Lim YF, Schneider G. Repurposing de novo designed entities reveals phosphodiesterase 3B and cathepsin L modulators. Chem Commun (Camb) 2015; 51:7478-81. [DOI: 10.1039/c5cc01376c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Scaffold hopping: a computational algorithm correctly predicted the macromolecular target ofde novogenerated small molecular entities.
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Affiliation(s)
- Tiago Rodrigues
- Swiss Federal Institute of Technology (ETH)
- Department of Chemistry and Applied Biosciences
- 8093 Zürich
- Switzerland
| | - Yen-Chu Lin
- Swiss Federal Institute of Technology (ETH)
- Department of Chemistry and Applied Biosciences
- 8093 Zürich
- Switzerland
| | - Markus Hartenfeller
- Swiss Federal Institute of Technology (ETH)
- Department of Chemistry and Applied Biosciences
- 8093 Zürich
- Switzerland
- Novartis Pharma AG
| | | | - Yi Fan Lim
- Swiss Federal Institute of Technology (ETH)
- Department of Chemistry and Applied Biosciences
- 8093 Zürich
- Switzerland
| | - Gisbert Schneider
- Swiss Federal Institute of Technology (ETH)
- Department of Chemistry and Applied Biosciences
- 8093 Zürich
- Switzerland
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19
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Mathieu P, Boulanger MC, Després JP. Ectopic visceral fat: a clinical and molecular perspective on the cardiometabolic risk. Rev Endocr Metab Disord 2014; 15:289-98. [PMID: 25326657 DOI: 10.1007/s11154-014-9299-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Worldwide, cardiovascular diseases (CVDs) are a leading cause of mortality. While in many westernized societies there has been a decrease prevalence of smoking and that a special emphasis has been put on the urgency to control the, so called, classical risk factors, it is more and more recognized that there remains a residual risk, which contributes to the development of CVDs. Imaging studies conducted over two decades have highlighted that the accumulation of ectopic visceral fat is associated with a plethora of metabolic dysfunctions, which have complex and intertwined interactions and participate to the development/progression/events of many cardiovascular disorders. The contribution of visceral ectopic fat to the development of coronary artery disease (CAD) is now well established, while in the last several years emerging evidence has pointed out that accumulation of harmful ectopic fat is associated with other cardiovascular disorders such as calcific aortic valve disease (CAVD), atrial fibrillation and left ventricular dysfunction. We review herein the key molecular processes linking the accumulation of ectopic fat to the development of CVDs. We have attempted, whenever possible, to use a translational approach whereby the pathobiology processes are linked to clinical observations.
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Affiliation(s)
- Patrick Mathieu
- Institut de Cardiologie et de Pneumologie de Québec/Quebec Heart and Lung Institute, 2725 Chemin Ste-Foy, Québec, QC, G1V-4G5, Canada,
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20
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Makinen MW, Salehitazangi M. The Structural Basis of Action of Vanadyl (VO 2+) Chelates in Cells. Coord Chem Rev 2014; 279:1-22. [PMID: 25237207 DOI: 10.1016/j.ccr.2014.07.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Much emphasis has been given to vanadium compounds as potential therapeutic reagents for the treatment of diabetes mellitus. Thus far, no vanadium compound has proven efficacious for long-term treatment of this disease in humans. Therefore, in review of the research literature, our goal has been to identify properties of vanadium compounds that are likely to favor physiological and biochemical compatibility for further development as therapeutic reagents. We have, therefore, limited our review to those vanadium compounds that have been used in both in vivo experiments with small, laboratory animals and in in vitro studies with primary or cultured cell systems and for which pharmacokinetic and pharmacodynamics results have been reported, including vanadium tissue content, vanadium and ligand lifetime in the bloodstream, structure in solution, and interaction with serum transport proteins. Only vanadyl (VO2+) chelates fulfill these requirements despite the large variety of vanadium compounds of different oxidation states, ligand structure, and coordination geometry synthesized as potential therapeutic agents. Extensive review of research results obtained with use of organic VO2+-chelates shows that the vanadyl chelate bis(acetylacetonato)oxidovanadium(IV) [hereafter abbreviated as VO(acac)2], exhibits the greatest capacity to enhance insulin receptor kinase activity in cells compared to other organic VO2+-chelates, is associated with a dose-dependent capacity to lower plasma glucose in diabetic laboratory animals, and exhibits a sufficiently long lifetime in the blood stream to allow correlation of its dose-dependent action with blood vanadium content. The properties underlying this behavior appear to be its high stability and capacity to remain intact upon binding to serum albumin. We relate the capacity to remain intact upon binding to serum albumin to the requirement to undergo transcytosis through the vascular endothelium to gain access to target tissues in the extravascular space. Serum albumin, as the most abundant transport protein in the blood stream, serves commonly as the carrier protein for small molecules, and transcytosis of albumin through capillary endothelium is regulated by a Src protein tyrosine kinase system. In this respect it is of interest to note that inorganic VO2+ has the capacity to enhance insulin receptor kinase activity of intact 3T3-L1 adipocytes in the presence of albumin, albeit weak; however, in the presence of transferrin no activation is observed. In addition to facilitating glucose uptake, the capacity of VO2+- chelates for insulin-like, antilipolytic action in primary adipocytes has also been reviewed. We conclude that measurement of inhibition of release of only free fatty acids from adipocytes stimulated by epinephrine is not a sufficient basis to ascribe the observations to purely insulin-mimetic, antilipolytic action. Adipocytes are known to contain both phosphodiesterase-3 and phosphodiesterase-4 (PDE3 and PDE4) isozymes, of which insulin antagonizes lipolysis only through PDE3B. It is not known whether the other isozyme in adipocytes is influenced directly by VO2+- chelates. In efforts to promote improved development of VO2+- chelates for therapeutic purposes, we propose synergism of a reagent with insulin as a criterion for evaluating physiological and biochemical specificity of action. We highlight two organic compounds that exhibit synergism with insulin in cellular assays. Interestingly, the only VO2+- chelate for which this property has been demonstrated, thus far, is VO(acac)2.
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Affiliation(s)
- Marvin W Makinen
- Department of Biochemistry & Molecular Biology, Gordon Center for Integrative Science, The University of Chicago, 929 East 57 Street, Chicago, Illinois 60637 USA
| | - Marzieh Salehitazangi
- Department of Biochemistry & Molecular Biology, Gordon Center for Integrative Science, The University of Chicago, 929 East 57 Street, Chicago, Illinois 60637 USA
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21
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Abstract
There has been an upsurge of interest in the adipocyte coincident with the onset of the obesity epidemic and the realization that adipose tissue plays a major role in the regulation of metabolic function. The past few years, in particular, have seen significant changes in the way that we classify adipocytes and how we view adipose development and differentiation. We have new perspective on the roles played by adipocytes in a variety of homeostatic processes and on the mechanisms used by adipocytes to communicate with other tissues. Finally, there has been significant progress in understanding how these relationships are altered during metabolic disease and how they might be manipulated to restore metabolic health.
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Affiliation(s)
- Evan D Rosen
- Division of Endocrinology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA; Departments of Genetics and Cell Biology, Harvard Medical School, Boston, MA 02215, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.
| | - Bruce M Spiegelman
- Departments of Genetics and Cell Biology, Harvard Medical School, Boston, MA 02215, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
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22
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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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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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Ovadia H, Haim Y, Nov O, Almog O, Kovsan J, Bashan N, Benhar M, Rudich A. Increased adipocyte S-nitrosylation targets anti-lipolytic action of insulin: relevance to adipose tissue dysfunction in obesity. J Biol Chem 2011; 286:30433-30443. [PMID: 21724851 DOI: 10.1074/jbc.m111.235945] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Protein S-nitrosylation is a reversible protein modification implicated in both physiological and pathophysiological regulation of protein function. In obesity, skeletal muscle insulin resistance is associated with increased S-nitrosylation of insulin-signaling proteins. However, whether adipose tissue is similarly affected in obesity and, if so, what are the causes and functional consequences of increased S-nitrosylation in this tissue are unknown. Total protein S-nitrosylation was increased in intra-abdominal adipose tissue of obese humans and in high fat-fed or leptin-deficient ob/ob mice. Both the insulin receptor β-subunit and Akt were S-nitrosylated, correlating with body weight. Elevated protein and mRNA expression of inducible NO synthase and decreased protein levels of thioredoxin reductase were associated with increased adipose tissue S-nitrosylation. Cultured differentiated pre-adipocyte cell lines exposed to the NO donors S-nitrosoglutathione (GSNO) or S-nitroso-N-acetylpenicillamine exhibited diminished insulin-stimulated phosphorylation of Akt but not of GSK3 nor of insulin-stimulated glucose uptake. Yet the anti-lipolytic action of insulin was markedly impaired in both cultured adipocytes and in mice injected with GSNO prior to administration of insulin. In cells, impaired ability of insulin to diminish phosphorylated PKA substrates in response to isoproterenol suggested impaired insulin-induced activation of PDE3B. Consistently, increased S-nitrosylation of PDE3B was detected in adipose tissue of high fat-fed obese mice. Site-directed mutagenesis revealed that Cys-768 and Cys-1040, two putative sites for S-nitrosylation adjacent to the substrate-binding site of PDE3B, accounted for ∼50% of its GSNO-induced S-nitrosylation. Collectively, PDE3B and the anti-lipolytic action of insulin may constitute novel targets for increased S-nitrosylation of adipose tissue in obesity.
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Affiliation(s)
- Hilla Ovadia
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84103
| | - Yulia Haim
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84103
| | - Ori Nov
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84103
| | - Orna Almog
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84103
| | - Julia Kovsan
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84103
| | - Nava Bashan
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84103
| | - Moran Benhar
- Department of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096
| | - Assaf Rudich
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84103; National Institute of Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84103, Israel.
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25
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Perino A, Ghigo A, Ferrero E, Morello F, Santulli G, Baillie GS, Damilano F, Dunlop AJ, Pawson C, Walser R, Levi R, Altruda F, Silengo L, Langeberg LK, Neubauer G, Heymans S, Lembo G, Wymann MP, Wetzker R, Houslay MD, Iaccarino G, Scott JD, Hirsch E. Integrating cardiac PIP3 and cAMP signaling through a PKA anchoring function of p110γ. Mol Cell 2011; 42:84-95. [PMID: 21474070 DOI: 10.1016/j.molcel.2011.01.030] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 12/20/2010] [Accepted: 01/24/2011] [Indexed: 01/08/2023]
Abstract
Adrenergic stimulation of the heart engages cAMP and phosphoinositide second messenger signaling cascades. Cardiac phosphoinositide 3-kinase p110γ participates in these processes by sustaining β-adrenergic receptor internalization through its catalytic function and by controlling phosphodiesterase 3B (PDE3B) activity via an unknown kinase-independent mechanism. We have discovered that p110γ anchors protein kinase A (PKA) through a site in its N-terminal region. Anchored PKA activates PDE3B to enhance cAMP degradation and phosphorylates p110γ to inhibit PIP(3) production. This provides local feedback control of PIP(3) and cAMP signaling events. In congestive heart failure, p110γ is upregulated and escapes PKA-mediated inhibition, contributing to a reduction in β-adrenergic receptor density. Pharmacological inhibition of p110γ normalizes β-adrenergic receptor density and improves contractility in failing hearts.
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Affiliation(s)
- Alessia Perino
- Department of Genetics, Biology and Biochemistry, Molecular Biotechnology Center, University of Torino, Torino 10126, Italy
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Francis SH, Blount MA, Corbin JD. Mammalian Cyclic Nucleotide Phosphodiesterases: Molecular Mechanisms and Physiological Functions. Physiol Rev 2011; 91:651-90. [DOI: 10.1152/physrev.00030.2010] [Citation(s) in RCA: 451] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The superfamily of cyclic nucleotide (cN) phosphodiesterases (PDEs) is comprised of 11 families of enzymes. PDEs break down cAMP and/or cGMP and are major determinants of cellular cN levels and, consequently, the actions of cN-signaling pathways. PDEs exhibit a range of catalytic efficiencies for breakdown of cAMP and/or cGMP and are regulated by myriad processes including phosphorylation, cN binding to allosteric GAF domains, changes in expression levels, interaction with regulatory or anchoring proteins, and reversible translocation among subcellular compartments. Selective PDE inhibitors are currently in clinical use for treatment of erectile dysfunction, pulmonary hypertension, intermittent claudication, and chronic pulmonary obstructive disease; many new inhibitors are being developed for treatment of these and other maladies. Recently reported x-ray crystallographic structures have defined features that provide for specificity for cAMP or cGMP in PDE catalytic sites or their GAF domains, as well as mechanisms involved in catalysis, oligomerization, autoinhibition, and interactions with inhibitors. In addition, major advances have been made in understanding the physiological impact and the biochemical basis for selective localization and/or recruitment of specific PDE isoenzymes to particular subcellular compartments. The many recent advances in understanding PDE structures, functions, and physiological actions are discussed in this review.
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Affiliation(s)
- Sharron H. Francis
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and Department of Medicine-Renal Division, Emory University School of Medicine, Atlanta, Georgia
| | - Mitsi A. Blount
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and Department of Medicine-Renal Division, Emory University School of Medicine, Atlanta, Georgia
| | - Jackie D. Corbin
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and Department of Medicine-Renal Division, Emory University School of Medicine, Atlanta, Georgia
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Aboulaich N, Chui PC, Asara JM, Flier JS, Maratos-Flier E. Polymerase I and transcript release factor regulates lipolysis via a phosphorylation-dependent mechanism. Diabetes 2011; 60:757-65. [PMID: 21282370 PMCID: PMC3046836 DOI: 10.2337/db10-0744] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
OBJECTIVE Polymerase I and transcript release factor (PTRF) is a protein highly expressed in adipose tissue and is an integral structural component of caveolae. Here, we report on a novel role of PTRF in lipid mobilization. RESEARCH DESIGN AND METHODS PTRF expression was examined in different adipose depots of mice during fasting, refeeding, and after administration of catecholamines and insulin. Involvement of PTRF during lipolysis was studied upon PTRF knockdown and overexpression and mutation of PTRF phosphorylation sites in 3T3-L1 adipocytes. RESULTS PTRF expression in mouse white adipose tissue (WAT) is regulated by nutritional status, increasing during fasting and decreasing to baseline after refeeding. Expression of PTRF also is hormonally regulated because treatment of mice with insulin leads to a decrease in expression, whereas isoproterenol increases expression in WAT. Manipulation of PTRF levels revealed a role of PTRF in lipolysis. Lentiviral-mediated knockdown of PTRF resulted in a marked attenuation of glycerol release in response to isoproterenol. Conversely, overexpressing PTRF enhanced isoproterenol-stimulated glycerol release. Mass-spectrometric analysis revealed that PTRF is phosphorylated at multiple sites in WAT. Mutation of serine 42, threonine 304, or serine 368 to alanine reduced isoproterenol-stimulated glycerol release in 3T3-L1 adipocytes. CONCLUSIONS Our study is the first direct demonstration for a novel adipose tissue-specific function of PTRF as a mediator of lipolysis and also shows that phosphorylation of PTRF is required for efficient fat mobilization.
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Affiliation(s)
- Nabila Aboulaich
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Patricia C. Chui
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - John M. Asara
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
- Department of Signal Transduction, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Jeffrey S. Flier
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Eleftheria Maratos-Flier
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
- Corresponding author: Eleftheria Maratos-Flier,
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Jensen J, Ruge T, Lai YC, Svensson MK, Eriksson JW. Effects of adrenaline on whole-body glucose metabolism and insulin-mediated regulation of glycogen synthase and PKB phosphorylation in human skeletal muscle. Metabolism 2011; 60:215-26. [PMID: 20153492 DOI: 10.1016/j.metabol.2009.12.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 12/23/2009] [Accepted: 12/28/2009] [Indexed: 11/20/2022]
Abstract
In the present study, we investigated the effect of adrenaline on insulin-mediated regulation of glucose and fat metabolism with focus on regulation of skeletal muscle PKB, GSK-3, and glycogen synthase (GS) phosphorylation. Ten healthy subjects (5 men and 5 women) received a 240-minute intravenous infusion of adrenaline (0.05 μg/[kg min]) or saline; after 120 minutes, a hyperinsulinemic-euglycemic clamp was added. Adrenaline infusion increased blood glucose concentration by approximately 50%, but the hyperinsulinemic clamp normalized blood glucose within 30 minutes. Glucose infusion rate during the last hour was approximately 60% lower during adrenaline infusion compared with saline (4.3 ± 0.5 vs 11.2 ± 0.6 mg/kg lean body mass per minute). Insulin increased PKB Ser⁴⁷³, PKB Thr³⁰⁸, and GSK-3β Ser⁹ phosphorylation in skeletal muscles; coinfusion of adrenaline did not influence insulin-stimulated PKB and GSK-3 phosphorylation. Adrenaline alone did not influence phosphorylation of PKB and GSK-3β. Insulin increased GS fractional activity and decreased GS Ser⁶⁴¹ and Ser⁶⁴⁵,⁶⁴⁹,⁶⁵³,⁶⁵⁷ phosphorylation. In the presence of adrenaline, insulin did neither activate GS nor dephosphorylate GS Ser⁶⁴¹. Surprisingly, GS Ser⁷ phosphorylation was not influenced by adrenaline. Adrenaline increased plasma lactate concentration; and muscle glycogen content was reduced in skeletal muscle the day after adrenaline infusion, supporting that insulin does not stimulate glycogen synthesis in skeletal muscles when adrenaline is present. In conclusion, adrenaline did not influence basal or insulin-stimulated PKB and GSK-3β phosphorylation in muscles, but completely blocked insulin-mediated GS activation and Ser⁶⁴¹ dephosphorylation. Still, insulin normalized adrenaline-mediated hyperglycemia.
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Affiliation(s)
- Jørgen Jensen
- Department of Physiology, National Institute of Occupational Health, P.O. Box 8149 Dep, N-0033 Oslo, Norway.
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29
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Age-related changes in the epithelial and stromal compartments of the mammary gland in normocalcemic mice lacking the vitamin D3 receptor. PLoS One 2011; 6:e16479. [PMID: 21298063 PMCID: PMC3027678 DOI: 10.1371/journal.pone.0016479] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 12/29/2010] [Indexed: 12/31/2022] Open
Abstract
The vitamin D3 receptor (VDR) serves as a negative growth regulator during mammary gland development via suppression of branching morphogenesis during puberty and modulation of differentiation and apoptosis during pregnancy, lactation and involution. To assess the role of the VDR in the aging mammary gland, we utilized 12, 14, and 16 month old VDR knockout (KO) and wild type (WT) mice for assessment of integrity of the epithelial and stromal compartments, steroid hormone levels and signaling pathways. Our data indicate that VDR ablation is associated with ductal ectasia of the primary mammary ducts, loss of secondary and tertiary ductal branches and atrophy of the mammary fat pad. In association with loss of the white adipose tissue compartment, smooth muscle actin staining is increased in glands from VDR KO mice, suggesting a change in the stromal microenviroment. Activation of caspase-3 and increased Bax expression in mammary tissue of VDR KO mice suggests that enhanced apoptosis may contribute to loss of ductal branching. These morphological changes in the glands of VDR KO mice are associated with ovarian failure and reduced serum 17β-estradiol. VDR KO mice also exhibit progressive loss of adipose tissue stores, hypoleptinemia and increased metabolic rate with age. These developmental studies indicate that, under normocalcemic conditions, loss of VDR signaling is associated with age-related estrogen deficiency, disruption of epithelial ductal branching, abnormal energy expenditure and atrophy of the mammary adipose compartment.
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30
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Tsukahara T, Hanazawa S, Murakami-Murofushi K. Cyclic phosphatidic acid influences the expression and regulation of cyclic nucleotide phosphodiesterase 3B and lipolysis in 3T3-L1 cells. Biochem Biophys Res Commun 2010; 404:109-14. [PMID: 21095182 DOI: 10.1016/j.bbrc.2010.11.076] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 11/17/2010] [Indexed: 01/30/2023]
Abstract
Cyclic phosphatidic acid (cPA) is found in cells from slime mold to humans and has a largely unknown function. We previously reported that cPA significantly inhibited the lipid accumulation in 3T3-L1 adipocytes through inhibition of PPARγ activation. We find here that cPA reduced intracellular triglyceride levels and inhibited the phosphodiesterase 3B (PDE3B) expression in 3T3-L1 adipocytes. PPARγ activation in adipogenesis that can be blocked by treatment with cPA then participates in adipocyte function through inhibition of PDE3B expression. We also found the intracellular cAMP levels in 3T3-L1 adipocytes increased after exposure to cPA. These findings contribute to the participation of cPA on the lipolytic activity in 3T3-L1 adipocytes. Our studies imply that cPA might be a therapeutic compound in the treatment of obesity and obesity-related diseases.
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Affiliation(s)
- Tamotsu Tsukahara
- Department of Integrative Physiology and Bio-System Control, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
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31
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Insulin regulates adipocyte lipolysis via an Akt-independent signaling pathway. Mol Cell Biol 2010; 30:5009-20. [PMID: 20733001 DOI: 10.1128/mcb.00797-10] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
After a meal, insulin suppresses lipolysis through the activation of its downstream kinase, Akt, resulting in the inhibition of protein kinase A (PKA), the main positive effector of lipolysis. During insulin resistance, this process is ineffective, leading to a characteristic dyslipidemia and the worsening of impaired insulin action and obesity. Here, we describe a noncanonical Akt-independent, phosphoinositide-3 kinase (PI3K)-dependent pathway that regulates adipocyte lipolysis using restricted subcellular signaling. This pathway selectively alters the PKA phosphorylation of its major lipid droplet-associated substrate, perilipin. In contrast, the phosphorylation of another PKA substrate, hormone-sensitive lipase (HSL), remains Akt dependent. Furthermore, insulin regulates total PKA activity in an Akt-dependent manner. These findings indicate that localized changes in insulin action are responsible for the differential phosphorylation of PKA substrates. Thus, we identify a pathway by which insulin regulates lipolysis through the spatially compartmentalized modulation of PKA.
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32
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Ahmed K, Tunaru S, Tang C, Müller M, Gille A, Sassmann A, Hanson J, Offermanns S. An autocrine lactate loop mediates insulin-dependent inhibition of lipolysis through GPR81. Cell Metab 2010; 11:311-9. [PMID: 20374963 DOI: 10.1016/j.cmet.2010.02.012] [Citation(s) in RCA: 268] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 12/29/2009] [Accepted: 02/17/2010] [Indexed: 02/07/2023]
Abstract
Lactate is an important metabolic intermediate released by skeletal muscle and other organs including the adipose tissue, which converts glucose into lactate under the influence of insulin. Here we show that lactate activates the G protein-coupled receptor GPR81, which is expressed in adipocytes and mediates antilipolytic effects through G(i)-dependent inhibition of adenylyl cyclase. Using GPR81-deficient mice, we demonstrate that the receptor is not involved in the regulation of lipolysis during intensive exercise. However, insulin-induced inhibition of lipolysis and insulin-induced decrease in adipocyte cAMP levels were strongly reduced in mice lacking GPR81, although insulin-dependent release of lactate by adipocytes was comparable between wild-type and GPR81-deficient mice. Thus, lactate and its receptor GPR81 unexpectedly function in an autocrine and paracrine loop to mediate insulin-induced antilipolytic effects. These data show that lactate can directly modulate metabolic processes in a hormone-like manner, and they reveal a new mechanism underlying the antilipolytic effects of insulin.
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Affiliation(s)
- Kashan Ahmed
- Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, Ludwigstrasse 43, 61231 Bad Nauheim, Germany
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Meex RCR, Schrauwen P, Hesselink MKC. Modulation of myocellular fat stores: lipid droplet dynamics in health and disease. Am J Physiol Regul Integr Comp Physiol 2009; 297:R913-24. [DOI: 10.1152/ajpregu.91053.2008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Storage of fatty acids as triacylglycerol (TAG) occurs in almost all mammalian tissues. Whereas adipose tissue is by far the largest storage site of fatty acids as TAG, subcellular TAG-containing structures—referred to as lipid droplets (LD)—are also present in other tissues. Until recently, LD were considered inert storage sites of energy dense fats. Nowadays, however, LD are increasingly considered dynamic functional organelles involved in many intracellular processes like lipid metabolism, vesicle trafficking, and cell signaling. Next to TAG, LD also contain other neutral lipids such as diacylglycerol. Furthermore, LD are coated by a monolayer of phospholipids decorated with a variety of proteins regulating the delicate balance between LD synthesis, growth, and degradation. Disturbances in LD-coating proteins may result in disequilibrium of TAG synthesis and degradation, giving rise to insulin-desensitizing lipid intermediates, especially in insulin-responsive tissues like skeletal muscle. For a proper and detailed understanding, more information on processes and players involved in LD synthesis and degradation is necessary. This, however, is hampered by the fact that research on LD dynamics in (human) muscle is still in its infancy. A rapidly expanding body of knowledge on LD dynamics originates from studies in other tissues and other species. Here, we aim to review the involvement of LD-coating proteins in LD formation and degradation (LD dynamics) and to extrapolate this knowledge to human skeletal muscle and to explore the role of LD dynamics in myocellular insulin sensitivity.
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Affiliation(s)
- Ruth C. R. Meex
- NUTRIM School for Nutrition, Toxicology and Metabolism, Departments of 1Human Movement Sciences and
| | - Patrick Schrauwen
- Human Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Matthijs K. C. Hesselink
- NUTRIM School for Nutrition, Toxicology and Metabolism, Departments of 1Human Movement Sciences and
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Allosteric-site and catalytic-site ligand effects on PDE5 functions are associated with distinct changes in physical form of the enzyme. Cell Signal 2009; 21:1768-74. [PMID: 19665054 DOI: 10.1016/j.cellsig.2009.07.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 07/27/2009] [Accepted: 07/28/2009] [Indexed: 11/23/2022]
Abstract
Native phosphodiesterase-5 (PDE5) homodimer contains distinct non-catalytic cGMP allosteric sites and catalytic sites for cGMP hydrolysis. Purified recombinant PDE5 was activated by pre-incubation with cGMP. Relatively low concentrations of cGMP produced a Native PAGE gel shift of PDE5 from a single band position (lower band) to a band with decreased mobility (upper band); higher concentrations of cGMP produced a band of intermediate mobility (middle band) in addition to the upper band. Two point mutations (G659A and G659P) near the catalytic site that reduced affinity for cGMP substrate retained allosteric cGMP-binding affinity like that of WT PDE5 but displayed cGMP-induced gel shift only to the middle-band position. The upper band could represent a form produced by cGMP binding to the catalytic site, while the middle band could represent a form produced by cGMP binding to the allosteric site. Millimolar cGMP was required for gel shift of PDE5 when added to the pre-incubation before Native PAGE, presumably due to removal of most of the cGMP during electrophoresis, but micromolar cGMP was sufficient for this effect if cGMP was included in the native gel buffer. cGMP-induced gel shift was associated with stimulation of PDE5 catalytic activity, and the rates of onset and reversibility of this effect suggested that it was due to cGMP binding to the allosteric site. Incubation of PDE5 with non-hydrolyzable, catalytic site-specific, substrate analogs such as the inhibitors sildenafil and tadalafil, followed by dilution, did not produce activation of catalytic activity like that obtained with cGMP, although both inhibitors produced a similar gel shift to the upper band as that obtained with cGMP. This implied that occupation of the catalytic site alone can produce a gel shift to the upper band. PDE5 activation or gel shift was reversed by lowering cGMP with dilution followed by at least 1h of incubation. Such slow reversibility could prolong effects of cGMP on PDE5 in cells after decline of this nucleotide. Reversal was also achieved by Mg(++) addition to the pre-incubation mixture to promote cGMP degradation, but Mg(++) addition did not reverse the gel shift caused by sildenafil, which is not hydrolyzed by PDE5. Upon extensive dilution, the effect of tadalafil, a potent PDE5 inhibitor, to enhance catalytic-site affinity for this inhibitor was rapidly reversed. Thus, kinetic effect of binding of a high-affinity PDE5 inhibitor to the catalytic site is more readily reversible than that obtained by cGMP binding to the allosteric site. It is concluded that cGMP or PDE5 inhibitor binding to the catalytic site, or ligand binding to both the catalytic site and allosteric site simultaneously, changes PDE5 to a similar physical form; this form is distinct from that produced by cGMP binding to the allosteric site, which activates the enzyme and reverses more slowly.
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Muraoka M, Fukushima A, Viengchareun S, Lombès M, Kishi F, Miyauchi A, Kanematsu M, Doi J, Kajimura J, Nakai R, Uebi T, Okamoto M, Takemori H. Involvement of SIK2/TORC2 signaling cascade in the regulation of insulin-induced PGC-1alpha and UCP-1 gene expression in brown adipocytes. Am J Physiol Endocrinol Metab 2009; 296:E1430-9. [PMID: 19351809 DOI: 10.1152/ajpendo.00024.2009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Salt-inducible kinase 2 (SIK2) is expressed abundantly in adipose tissues and represses cAMP-response element-binding protein (CREB)-mediated gene expression by phosphorylating the coactivator transducer of regulated CREB activity (TORC2). Phosphorylation at Ser(587) of SIK2 diminishes its TORC2 phosphorylation activity. In 3T3-L1 white adipocytes, SIK2 downregulates lipogenic gene in response to nutritional stresses. To investigate the impact of SIK2 on the function of brown adipose tissue (BAT), we used T37i brown adipocytes, mice with diet-induced obesity, and SIK2 mutant (S587A) transgenic mice. When T37i adipocytes were treated with insulin, the levels of peroxisome proliferator-activated receptor-coactivator-1alpha (PGC-1alpha) and uncoupling protein-1 (UCP-1) mRNA were increased, and the induction was inhibited by overexpression of SIK2 (S587A) mutant or dominant-negative CREB. Insulin enhanced SIK2 phosphorylation at Ser(587), which was accompanied by decrease in phospho-TORC2. Similarly, the decrease in the level of SIK2 phosphorylation at Ser(587) was observed in the BAT of mice with diet-induced obesity, which was negatively correlated with TORC2 phosphorylation. To confirm the negative correlation between SIK2 phosphorylation at Ser(587) and TORC2 phosphorylation in BAT, SIK2 mutant (S587A) was overexpressed in adipose tissues by using the adipocyte fatty acid-binding protein 2 promoter. The expression of recombinant SIK2 (S587A) was restricted to BAT, and the levels of phospho-TORC2 were elevated in BAT of transgenic mice. Male transgenic mice developed high-fat diet-induced obesity, and their BAT expressed low levels of PGC-1alpha and UCP-1 mRNA, suggesting that SIK2-TORC2 cascade may be important for the regulation of PGC-1alpha and UCP-1 gene expression in insulin signaling in BAT.
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Affiliation(s)
- Masaaki Muraoka
- Laboratory of Cell Signaling and Metabolism, National Institute of Biomedical Innovation, 7-6-8, Asagi, Saito, Ibaraki, Osaka 567-0085, Japan
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Zechner R, Kienesberger PC, Haemmerle G, Zimmermann R, Lass A. Adipose triglyceride lipase and the lipolytic catabolism of cellular fat stores. J Lipid Res 2008; 50:3-21. [PMID: 18952573 DOI: 10.1194/jlr.r800031-jlr200] [Citation(s) in RCA: 394] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Fatty acids (FAs) are essential components of all lipid classes and pivotal substrates for energy production in all vertebrates. Additionally, they act directly or indirectly as signaling molecules and, when bonded to amino acid side chains of peptides, anchor proteins in biological membranes. In vertebrates, FAs are predominantly stored in the form of triacylglycerol (TG) within lipid droplets of white adipose tissue. Lipid droplet-associated TGs are also found in most nonadipose tissues, including liver, cardiac muscle, and skeletal muscle. The mobilization of FAs from all fat depots depends on the activity of TG hydrolases. Currently, three enzymes are known to hydrolyze TG, the well-studied hormone-sensitive lipase (HSL) and monoglyceride lipase (MGL), discovered more than 40 years ago, as well as the relatively recently identified adipose triglyceride lipase (ATGL). The phenotype of HSL- and ATGL-deficient mice, as well as the disease pattern of patients with defective ATGL activity (due to mutation in ATGL or in the enzyme's activator, CGI-58), suggest that the consecutive action of ATGL, HSL, and MGL is responsible for the complete hydrolysis of a TG molecule. The complex regulation of these enzymes by numerous, partially uncharacterized effectors creates the "lipolysome," a complex metabolic network that contributes to the control of lipid and energy homeostasis. This review focuses on the structure, function, and regulation of lipolytic enzymes with a special emphasis on ATGL.
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Affiliation(s)
- Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Austria.
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Müller G, Wied S, Over S, Frick W. Inhibition of lipolysis by palmitate, H2O2 and the sulfonylurea drug, glimepiride, in rat adipocytes depends on cAMP degradation by lipid droplets. Biochemistry 2008; 47:1259-73. [PMID: 18186616 DOI: 10.1021/bi701413t] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The release of fatty acids and glycerol from lipid droplets (LD) of mammalian adipose cells is tightly regulated by a number of counterregulatory signals and negative feedback mechanisms. In humans unrestrained lipolysis contributes to the pathogenesis of obesity and type II diabetes. In order to identify novel targets for the pharmacological interference with lipolysis, the molecular mechanisms of four antilipolytic agents were compared in isolated rat adipocytes. Incubation of the adipocytes with insulin, palmitate, glucose oxidase (for the generation of H2O2) and the antidiabetic sulfonylurea drug, glimepiride, reduced adenylyl cyclase-dependent, but not dibutyryl-cAMP-induced lipolysis as well as the translocation of hormone-sensitive lipase and the LD-associated protein, perilipin-A, to and from LD, respectively. The antilipolytic activity of palmitate, H2O2 and glimepiride rather than that of insulin was dependent on rolipram-sensitive but cilostamide-insensitive phosphodiesterase (PDE) but was not associated with detectable downregulation of total cytosolic cAMP and insulin signaling via phosphatidylinositol-3 kinase and protein kinase B. LD from adipocytes treated with palmitate, H2O2 and glimepiride were capable of converting cAMP to adenosine in vitro, which was hardly observed with those from basal cells. Conversion of cAMP to adenosine was blocked by rolipram and the 5'-nucleotidase inhibitor, AMPCP. Immunoblotting analysis revealed a limited salt-sensitive association with LD of some of the PDE isoforms currently known to be expressed in rat adipocytes. In contrast, the cAMP-to-adenosine converting activity was stripped off the LD by bacterial phosphatidylinositol-specific phospholipase C. These findings emphasize the importance of the compartmentalization of cAMP signaling for the regulation of lipolysis in adipocytes, in general, and of the involvement of LD-associated proteins for cAMP degradation, in particular.
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Affiliation(s)
- Günter Müller
- Sanofi-Aventis Pharma, Therapeutic Department Metabolism, 65926 Frankfurt am Main, Germany.
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Cong L, Chen K, Li J, Gao P, Li Q, Mi S, Wu X, Zhao A. Regulation of adiponectin and leptin secretion and expression by insulin through a PI3K-PDE3B dependent mechanism in rat primary adipocytes. Biochem J 2007; 403:519-25. [PMID: 17286556 PMCID: PMC1876381 DOI: 10.1042/bj20061478] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Adiponectin is intimately involved in the regulation of insulin sensitivity, carbohydrate and lipid metabolism, and cardiovascular functions. The circulating concentration of adiponectin is decreased in obesity and Type 2 diabetes. The present study attempts to elucidate the mechanisms underlying the regulation of adiponectin secretion and expression in rat primary adipocytes. The beta-agonist, isoprenaline, decreased adiponectin secretion and expression in a dose-dependent manner in primary adipocytes. Importantly, such an inhibitory effect could be blocked by insulin. The opposing effects of isoprenaline and insulin could be explained by differential regulation of intracellular cAMP levels, since cAMP analogues suppressed adiponectin secretion and expression in a fashion similar to isoprenaline, and insulin blocked the inhibitory effects of the cAMP analogue hydrolysable by PDE (phosphodiesterase). A specific PDE3 inhibitor, milrinone, and PI3K (phosphoinositide 3-kinase) inhibitors abolished the effects of insulin on adiponectin secretion and expression. In the same studies, leptin secretion and expression displayed a similar pattern of regulation to adiponectin. We conclude that insulin and beta-agonists act directly at the adipocytes in opposing fashions to regulate the production of adiponectin and leptin, and that a PI3K-PDE3B-cAMP pathway mediates the effects of insulin to restore beta-agonist/cAMP-suppressed secretion and expression of these two adipokines.
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Affiliation(s)
- Li Cong
- Department of Cell Biology and Physiology, University of Pittsburgh, S-326, 3500 Terrace Street, Pittsburgh, PA 15261, U.S.A
| | - Ke Chen
- Department of Cell Biology and Physiology, University of Pittsburgh, S-326, 3500 Terrace Street, Pittsburgh, PA 15261, U.S.A
| | - Ji Li
- Department of Cell Biology and Physiology, University of Pittsburgh, S-326, 3500 Terrace Street, Pittsburgh, PA 15261, U.S.A
| | - Ping Gao
- Department of Cell Biology and Physiology, University of Pittsburgh, S-326, 3500 Terrace Street, Pittsburgh, PA 15261, U.S.A
| | - Qiang Li
- Department of Cell Biology and Physiology, University of Pittsburgh, S-326, 3500 Terrace Street, Pittsburgh, PA 15261, U.S.A
| | - Shuhua Mi
- Department of Cell Biology and Physiology, University of Pittsburgh, S-326, 3500 Terrace Street, Pittsburgh, PA 15261, U.S.A
| | - Xin Wu
- Department of Cell Biology and Physiology, University of Pittsburgh, S-326, 3500 Terrace Street, Pittsburgh, PA 15261, U.S.A
| | - Allan Z. Zhao
- Department of Cell Biology and Physiology, University of Pittsburgh, S-326, 3500 Terrace Street, Pittsburgh, PA 15261, U.S.A
- To whom correspondence should be addressed (email )
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Sasseville M, Côté N, Guillemette C, Richard FJ. New insight into the role of phosphodiesterase 3A in porcine oocyte maturation. BMC DEVELOPMENTAL BIOLOGY 2006; 6:47. [PMID: 17038172 PMCID: PMC1617088 DOI: 10.1186/1471-213x-6-47] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Accepted: 10/12/2006] [Indexed: 11/10/2022]
Abstract
Background The ovulatory surge of gonadotropins triggers oocyte maturation and rupture of the ovarian follicle. The resumption of nuclear maturation in the oocyte from the prophase stage is characterized by germinal vesicle breakdown (GVBD). It has previously been shown that specific inhibition of cAMP degradation by PDE3 prevents the resumption of oocyte meiosis. However, no report has characterized the activity of PDE3 in the porcine oocyte, or the implication of the cAMP-PDE3 pathway in the entire nuclear maturation process. In this study, PDE3 activity in the oocyte was assessed during in vitro maturation (IVM) and the possible roles of the cAMP-PDE3 pathway in the resumption and progression of meiosis were investigated in terms of different models of oocyte maturation. Results Cyclic AMP-degrading PDE activity was detected in the cumulus-oocyte complex (COC) and was partially inhibited by a specific PDE3 inhibitor, cilostamide. When measured only in the denuded oocyte, PDE activity was almost completely inhibited by cilostamide, suggesting that cAMP-PDE3 activity is the major cAMP-PDE in porcine oocytes. PDE3A mRNA was detected by RT-PCR. PDE3 activity did not vary significantly during the early hours of IVM, but a maximum was observed at 13 hours. In cumulus-oocyte complexes, meiosis resumed after 20.81 hours of culture. PDE3 inhibition no longer maintained meiotic arrest if sustained beyond 17.65 hours of IVM, 3 hours prior to resumption of meiosis. Thereafter, PDE3 inhibition progressively lost its efficacy in GVBD. When the protein phosphatase 1 and 2A inhibitor okadaic acid was continuously or transiently (3 hours) present during IVM, meiosis resumed prematurely; PDE3 inhibition was unable to prevent GVBD. However, PDE3 inhibition in COC treated with OA for 3 hours significantly delayed meiosis at the intermediate stage. Conclusion The present investigation has demonstrated that PDE3A is the major cAMP-degrading PDE in the oocyte. It regulates the resumption of meiosis until 3 hours prior to GVBD and transiently affects meiotic progression.
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Affiliation(s)
- Maxime Sasseville
- Centre de Recherche en Biologie de la Reproduction, Département des Sciences Animales, Université Laval, Québec, Canada
| | - Nancy Côté
- Centre de Recherche en Biologie de la Reproduction, Département des Sciences Animales, Université Laval, Québec, Canada
| | - Christine Guillemette
- Centre de Recherche en Biologie de la Reproduction, Département des Sciences Animales, Université Laval, Québec, Canada
| | - François J Richard
- Centre de Recherche en Biologie de la Reproduction, Département des Sciences Animales, Université Laval, Québec, Canada
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Langin D. Control of fatty acid and glycerol release in adipose tissue lipolysis. C R Biol 2006; 329:598-607; discussion 653-5. [PMID: 16860278 DOI: 10.1016/j.crvi.2005.10.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Accepted: 10/18/2005] [Indexed: 11/25/2022]
Abstract
Adipose tissue lipolysis is the catabolic process leading to the breakdown of triglycerides stored in fat cells and the release of fatty acids and glycerol. Recent work has revealed that lipolysis is not a simple metabolic pathway stimulated by catecholamines and inhibited by insulin. New discoveries on the regulation of lipolysis by endocrine and paracrine factors and on the proteins involved in triglyceride hydrolysis have led to a reappraisal of the complexity of the various signal transduction pathways. The steps involved in the dysregulation of lipolysis observed in obesity have partly been identified.
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Affiliation(s)
- Dominique Langin
- Unité de recherches sur les obésités, INSERM UPS U586, institut Louis-Bugnard, université Paul-Sabatier, CHU Rangueil, BP 84225, 31432 Toulouse cedex 4, France.
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Langin D. Adipose tissue lipolysis as a metabolic pathway to define pharmacological strategies against obesity and the metabolic syndrome. Pharmacol Res 2006; 53:482-91. [PMID: 16644234 DOI: 10.1016/j.phrs.2006.03.009] [Citation(s) in RCA: 229] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Accepted: 03/17/2006] [Indexed: 02/08/2023]
Abstract
Adipose tissue lipolysis is the catabolic process leading to the breakdown of triglycerides stored in fat cells and release of fatty acids and glycerol. Recent work has revealed that lipolysis is not a simple metabolic pathway stimulated by catecholamines and inhibited by insulin. There have been new discoveries on the endocrine and paracrine regulation of lipolysis and on the molecular mechanisms of triglyceride hydrolysis. Catecholamines modulate lipolysis through lipolytic beta-adrenoceptor and antilipolytic alpha2-adrenoceptor. Recent studies have allowed a better understanding of the relative contribution of the two types of receptors and provided evidence for the in vivo involvement of alpha2-adrenoceptors in the physiological control of subcutaneous adipose tissue lipolysis. A puzzling observation is the characterization of a residual catecholamine-induced lipolysis in mice deficient in beta-adrenoceptors. A novel lipolytic system has been characterized in human fat cells. Natriuretic peptides stimulate lipolysis through a cGMP-dependent pathway. There are other lipolytic pathways active in human fat cells which importance is not fully understood. Forty years after the description of the antilipolytic effect of nicotinic acid, the receptors have been identified. Adrenomedullin which is produced by adipocytes exert an antilipolytic effect through an indirect mechanism involving nitric oxide. The molecular details of the lipolytic reaction are not fully understood. The role of the lipases has been re-evaluated with the cloning of adipose triglyceride lipase. Hormone-sensitive lipase appears as the major lipase for catecholamine and natriuretic peptide-stimulated lipolysis whereas adipose triglyceride lipase mediates the hydrolysis of triglycerides during basal lipolysis. Translocation of hormone-sensitive lipase bound to the adipocyte lipid binding protein to the lipid droplet seems to be an important step during lipolytic activation. Re-organization of the lipid droplet coating by perilipins facilitates the access of the enzyme. The role of other lipid-interacting proteins in lipolysis is still unclear. The proteins involved in the lipolytic process constitute drug targets for the treatment of obesity and the metabolic syndrome. The oldest example is nicotinic acid (niacin) used as a hypolipidaemic drug. A first approach consists in molecules stimulating lipolysis and oxidation of the released fatty acids to decrease fat stores. A second approach is a chronic inhibition of lipolysis to diminish plasma fatty acid level which is a central feature of the metabolic syndrome.
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Affiliation(s)
- Dominique Langin
- Obesity Research Unit Inserm UPS U586, Institut Louis Bugnard, Université Paul Sabatier, CHU Rangueil, Toulouse, France.
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Wang H, Reaves LA, Edens NK. Ginseng extract inhibits lipolysis in rat adipocytes in vitro by activating phosphodiesterase 4. J Nutr 2006; 136:337-42. [PMID: 16424109 DOI: 10.1093/jn/136.2.337] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Elevated concentrations of plasma free fatty acids (FFA) may cause insulin resistance. Inhibition of lipolysis reduces FFA availability and improves insulin sensitivity. Ginseng extract (Panax spp., GE) was shown to improve glycemia in Type 2 diabetes. In the present study, the antilipolytic effect of GE in rat adipocytes and the signaling pathway for GE antilipolysis were investigated. Adipocytes were isolated from rat fat tissue by collagenase digestion. The ability of GE to inhibit lipolysis was assessed by measuring glycerol and FFA release into the incubation medium. Phosphatidylinositol 3-kinase (PI3-K) inhibitor and various phosphodiesterase (PDE) inhibitors were applied to investigate the signaling pathway for GE antilipolysis. The present study showed that insulin and GE inhibited lipolysis by 42.4 and 49% compared with basal, respectively (P < 0.05). Unlike insulin, the PI3-K inhibitor wortmannin did not reverse GE antilipolysis, and GE did not affect phosphorylation of protein kinase B (PKB). The nonselective PDE inhibitor enprofylline reversed both insulin and GE antilipolysis. The specific phosphodiesterase 3 (PDE3) inhibitor cilostamide reversed insulin antilipolysis completely, but did not significantly affect GE antilipolysis. The specific phosphodiesterase 4 (PDE4) inhibitor rolipram did not significantly affect insulin antilipolysis, but almost completely reversed GE antilipolysis. Moreover, the combination of PDE3 and PDE4 inhibitors completely reversed GE antilipolysis. None of the ginsenosides (Rb1, Re, Rg1, Rc, Rb2, and Rd) were responsible for GE antilipolysis. The results suggest that ginseng exerts its antilipolytic effect through a signaling pathway different from that of insulin. GE antilipolysis is mediated in part by activating PDE4 in rat adipocytes.
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Affiliation(s)
- Hong Wang
- The Ohio State University, Columbus, OH 43210, USA
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43
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Morito S, Yaguchi K, Imada M, Tachikawa C, Nomura M, Moritani S, Igarashi M, Yokogawa K, Miyamoto KI. Insulin signaling in adipocytes differentiated from mouse stromal MC3T3-G2/PA6 cells. Biol Pharm Bull 2005; 28:2040-5. [PMID: 16272686 DOI: 10.1248/bpb.28.2040] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The stromal MC3T3-G2/PA6 (PA6) cells from mouse clavaria did not require insulin for differentiation into mature adipose cells, although insulin is well known to play a key role in adipocyte differentiation. Large lipid droplets were observed in the cytoplasm of PA6 cells, and mRNA expression of the adipose specific proteins (aP2, PPARgamma, C/EBPalpha, FAS, GLUT4, leptin, and adiponectin) as differentiation markers appeared or increased clearly in the cells at 8 d after stimulation without insulin. In addition, the glycerol released from the cells (lipolysis) was increased in a concentration-dependent manner by isoproterenol. However, the isoproterenol-induced lipolysis in the cells was not influenced by treatment with insulin, although that was observed in extramedullary adipocytes, 3T3-L1 cells. On the other hand, the 2-deoxy-D-[1-3H]glucose uptake in differentiated PA6 cells also increased by insulin, as shown in other adipose cells. In the cells, insulin induced the phosphorylation of extracellular signal-regulated kinases (Erks), Akt at Ser 473 and ribosomal p70 S6 protein kinase (p70 S6K) at Thr 389, and the insulin-induced 2-deoxy-D-[1-3H]glucose uptake was inhibited by pre-treatment with wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K), or ML-9, an Akt inhibitor. These results suggest that the insulin signal for adipogenesis (lipogenesis) and lipolysis in bone marrow stroma PA6 cells differs from extramedullary adipocytes, such as 3T3-L1 cells.
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Affiliation(s)
- Satoshi Morito
- Department of Clinical Pharmacy, Graduate School of Natural Science and Technology, Kanazawa University, Japan
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Carmen GY, Víctor SM. Signalling mechanisms regulating lipolysis. Cell Signal 2005; 18:401-8. [PMID: 16182514 DOI: 10.1016/j.cellsig.2005.08.009] [Citation(s) in RCA: 315] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Accepted: 08/19/2005] [Indexed: 02/06/2023]
Abstract
Adipose tissue plays an important role providing energy to other tissues and functioning as an energy reserve organ. The energy supply is produced by triglycerides stored in a large vacuole representing approximately 95% of adipocyte volume. In the fasting period, triglyceride hydrolysis produces glycerol and free fatty acids which are important oxidative fuels for other tissues such as liver, skeletal muscle, kidney and myocardium. Hormone-sensitive lipase (HSL) is the enzyme that hydrolyzes intracellular triacylglycerol and diacylglycerol, and is one of the key molecules controlling lipolysis. Hormones and physiological factors such as dieting, physical exercise and ageing regulate intensively the release of glycerol and free fatty acids from adipocytes. One of the best known mechanisms that activate lipolysis in the adipocyte is the cAMP dependent pathway. cAMP production is modulated by hormone receptors coupled to Gs/Gi family of GTP binding proteins, such as beta-adrenergic receptors, whereas cAMP degradation is controlled by modulation of phosphodiesterase activity, increased by insulin receptor signalling. cAMP activates PKA which activates HSL by promoting its phosphorylation. Hormonal control of lipolysis can also be achieved by receptors coupled G proteins of the Gq family, through molecular mechanisms that involve PKC and MAPK, which are currently under investigation. cGMP and PKG have also been found to activate lipolysis in adipocytes. In this review we have compiled data from literature reporting both the classical and the alternative mechanisms of lipolysis.
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Affiliation(s)
- González-Yanes Carmen
- Department of Medical Biochemistry and Molecular Biology, School of Medicine. Investigation Unit, Virgen Macarena University Hospital, Av. Sanchez Pizjuan 4, Seville 41009, Spain
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Abstract
The presence of the extracellular calcium-sensing receptor (CaSR) has been demonstrated in numerous cells that are key in the control of serum calcium concentrations, underscoring its relevance in systemic calcium homeostasis. The more recent evidence of its presence in tissues not involved in this function has broadened the spectrum of interest in this protein, now known to regulate diverse cell functions such as proliferation, differentiation, and apoptosis. This study shows the expression of CaSR in human omental adipose tissue, isolated adipocytes, and adipocyte progenitor cells as assessed by RT-PCR and immunoblotting. This is the first report of CaSR being expressed in human adipocytes and adipocyte progenitor cells, opening the possibility to investigate the physiological implications and thus contributing a novel component for adipose tissue biology research.
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Affiliation(s)
- Mariana Cifuentes
- Institute of Nutrition and Food Technology, University of Chile, Macul, Casilla, Santiago, Chile.
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46
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Zhang X, Carey GB. Plasma membrane-bound cyclic AMP phosphodiesterase activity in 3T3-L1 adipocytes. Comp Biochem Physiol B Biochem Mol Biol 2005; 137:309-16. [PMID: 15050518 DOI: 10.1016/j.cbpc.2003.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Revised: 12/02/2003] [Accepted: 12/07/2003] [Indexed: 11/22/2022]
Abstract
Plasma membranes were isolated from 3T3-L1 adipocytes. Plasma membrane phosphodiesterase (PM-PDE) was measured in the presence of 5 microM cilostamide. Time course and cAMP dose response ranging from 0 to 2 microM were measured. PM-PDE remained linear up to 20 min. Non-linear curve fitting analysis showed that the low Km cAMP dose data fit a two component curve significantly better than a one component curve, indicating that there are two iso-forms of PDE in the plasma membrane of 3T3-L1 adipocytes, similar to swine adipocytes. The Km and Vmax values for this two component curve were Km1=0.12 microM, Vmax1=3.08 pmol min(-1) mg(-1) protein, and Km2=3.67 microM, Vmax2=83.8 pmol min(-1) mg(-1) protein. Inhibitors of PDE1, PDE2 and PDE5 failed to inhibit PM-PDE, as observed in swine adipocyte plasma membranes. However, PDE4 inhibitors were three-fold more effective at inhibiting PDE in 3T3-L1 PM compared to swine adipocyte PM. One mM 1, 3-dipropyl-8-p-sulfophenylxanthine (DPSPX) inhibited PM-PDE by approximately 75% in both preparations. These data demonstrate that PM-PDE is distinct from microsomal membrane PDE and may be responsible for extracellular cAMP metabolism to AMP in 3T3-L1 adipocytes.
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Affiliation(s)
- Xiujun Zhang
- Department of Animal and Nutritional Sciences, University of New Hampshire, 403 Kendall Hall, Durham, NH 03824, USA
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Watanabe T, Satoo H, Kohara K, Takami R, Motoyashiki T, Morita T, Ueki H. Orthovanadate stimulates cAMP phosphodiesterase 3 activity in isolated rat hepatocytes through mitogen-activated protein kinase activation dependent on cAMP-dependent protein kinase. Biol Pharm Bull 2005; 27:789-96. [PMID: 15187419 DOI: 10.1248/bpb.27.789] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Orthovanadate (vanadate) as well as insulin stimulated phosphodiesterase 3 (PDE3) in the particulate fraction of rat hepatocytes. The vanadate-induced activations of PDE3 and mitogen-activated protein kinase (MAPK) were inhibited by H-89 and PD98059, suggesting that the MAPK activation via cAMP-dependent protein kinase (PKA) and MAPK kinase is involved in the vanadate action. On the other hand, the insulin-induced activations of PDE3 and Akt were inhibited by wortmannin, suggesting involvement of the Akt activation via phosphatidylinositol 3-kinase (PI3K) in the insulin action. The vanadate-induced activations of PKA and PDE3 were inhibited in part by propranolol or genistein, suggesting that vanadate may exert its actions via dual signaling pathways of beta-adrenergic receptors and receptor tyrosine kinases of growth factors. Vanadate, in contrast to insulin, did not promote the phosphorylation of insulin receptor substrate-1. The vanadate-induced increase in the phosphorylation of a main isoform of MAPKs, p44 protein, was detected by immunoblotting migration patterns of SDS-PAGE. A partially purified PDE3 activity was increased by addition of MAPK or Akt to the reaction mixture, suggesting that MAPK as well as Akt acts upstream of PDE3. The activation of PDE3 by insulin was independent of a transient increase in the MAPK activity, probably due to the dephosphorylated inactivation mediated by the induced activation of MAPK phosphatases (MKPs). Vanadate did not affect the MKP activity. These results indicate that vanadate stimulates the particulate PDE3 activity by activating mainly p44 MAPK via a PKA-dependent process, and that it differs from insulin with regard to a phosphorylation cascade of PDE3 activation.
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Affiliation(s)
- Tomoyasu Watanabe
- Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan
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48
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Petry S, Ben Ali Y, Chahinian H, Jordan H, Kleine H, Müller G, Carrière F, Abousalham A. Sensitive assay for hormone-sensitive lipase using NBD-labeled monoacylglycerol to detect low activities in rat adipocytes. J Lipid Res 2005; 46:603-14. [PMID: 15627655 DOI: 10.1194/jlr.d400021-jlr200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The recent finding that p-nitrobenzofurazan (NBD)-FA is incorporated into and released from the acylglycerols of isolated rat adipocytes in an insulin-sensitive manner [G. Muller, H. Jordan, C. Jung, H. Kleine, and S. Petry. 2003. Biochimie. 85: 1245-1246] suggests that NBD-FA-labeled acylglycerols are cleaved by rat adipocyte hormone-sensitive lipase (HSL) in vivo. In the present study, we developed a continuous, sensitive in vitro lipase assay using a monoacylglycerol (MAG) containing NBD (NBD-MAG). NBD-MAG was found to provide an efficient substrate for rat adipocyte and human recombinant HSL. Ultrasonic treatment applied in the presence of phospholipids leads to the incorporation of NBD-MAG into the phospholipid liposomes and to a concomitant change of its spectrophotometric properties. The enzymatic release of NBD-FA and its dissociation from the carrier liposomes is accompanied by the recovery of the original spectrophotometric characteristics. The rate of lipolysis was monitored by measuring the increase in optical density at 481 nm, which was found to be linear with time and linearly proportional to the amount of lipase added. To assess the specific activity of recombinant HSL, we determined the molar extinction coefficient of NBD-FA under the assay conditions. This convenient assay procedure based on NBD-MAG should facilitate the search for small molecule HSL inhibitors.
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Affiliation(s)
- Stefan Petry
- Aventis Pharma Germany, 65926 Frankfurt am Main, Germany.
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Ben Ali Y, Chahinian H, Petry S, Muller G, Carrière F, Verger R, Abousalham A. Might the kinetic behavior of hormone-sensitive lipase reflect the absence of the lid domain? Biochemistry 2004; 43:9298-306. [PMID: 15260473 DOI: 10.1021/bi049479o] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hormone-sensitive lipase (HSL) is thought to contribute importantly to the mobilization of fatty acids from the triacylglycerols (TAGs) stored in adipocytes, providing the main source of energy in mammals. To investigate the HSL substrate specificity more closely, we systematically assessed the lipolytic activity of recombinant human HSL on solutions and emulsions of various vinyl esters and TAG substrates, using the pH-stat assay technique. Recombinant human HSL activity on solutions of partly soluble vinyl esters or TAG was found to range from 35 to 90% of the maximum activity measured with the same substrates in the emulsified state. The possible existence of a lipid-water interface due to the formation of small aggregates of vinyl esters or TAG in solution may account for the HSL activity observed below the solubility limit of the substrate. Recombinant human HSL also hydrolyzes insoluble medium- and long-chain acylglycerols such as trioctanoylglycerol, dioleoylglycerol, and olive oil, and can therefore be classified as a true lipase. Preincubation of the recombinant HSL with a serine esterase inhibitor such as diethyl p-nitrophenyl phosphate in 1:100 molar excess leads to complete HSL inhibition within 15 min. This result indicates that the catalytic serine of HSL is highly reactive and that it is readily accessible. Similar behavior was also observed with lipases with no lid domain covering their active site, or with a deletion in the lid domain. The 3-D structure of HSL, which still remains to be determined, may therefore lack the lid domain known to exist in various other lipases.
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Affiliation(s)
- Yassine Ben Ali
- Enzymology at Interfaces and Physiology of Lipolysis, UPR 9025-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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Rydén M, Dicker A, Götherström C, Aström G, Tammik C, Arner P, Le Blanc K. Functional characterization of human mesenchymal stem cell-derived adipocytes. Biochem Biophys Res Commun 2004; 311:391-7. [PMID: 14592427 DOI: 10.1016/j.bbrc.2003.10.010] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The function of adipocytes derived from human mesenchymal stem cells (hMSC) was investigated for the first time in hMSC from fetal liver (FL) and adult bone marrow (BM) and compared with preadipocytes from human subcutaneous adipose tissue differentiated according to adipocyte-specific protocols. FL- and BM-derived adipocytes displayed both morphological and functional characteristics of mature adipocytes including specific intracellular signaling pathways for tumor necrosis factor-alpha, catecholamine-regulated lipolysis as well as secretion of adiponectin and leptin. Similar to differentiated preadipocytes, hMSC adipocytes displayed lipolytic effects mediated by beta-adrenoceptors and antilipolytic effects mediated by the alpha 2A-adrenoceptor (alpha 2A-AR) and expressed proteins with a pivotal role in human lipolysis, including beta 2-AR, alpha 2A-AR, and hormone-sensitive lipase. We conclude that hMSC-derived adipocytes are morphologically and functionally similar to preadipocytes and display an intact lipolytic signaling pathway and endocrine function. These systems could be of great value in adipocyte research as a renewable source of adipocytes.
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Affiliation(s)
- Mikael Rydén
- Department of Medicine, Center of Metabolism and Endocrinology, Karolinska Institute, Huddinge University Hospital, 141 86, Stockholm, Sweden.
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