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Getty-Kaushik L, Viereck JC, Goodman JM, Guo Z, LeBrasseur NK, Richard AMT, Flanagan JN, Yaney GC, Hamilton JA, Tornheim K. Mice deficient in phosphofructokinase-M have greatly decreased fat stores. Obesity (Silver Spring) 2010; 18:434-40. [PMID: 19779479 PMCID: PMC2871150 DOI: 10.1038/oby.2009.295] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Synthesis of triacylglycerol requires the glucose-derived glycerol component, and glucose uptake has been viewed as the rate-limiting step in glucose metabolism in adipocytes. Furthermore, adipose tissue contains all three isoforms of the glycolytic enzyme phosphofructokinase (PFK). We here report that mice deficient in the muscle isoform PFK-M have greatly reduced fat stores. Mice with disrupted activity of the PFK-M distal promoter were obtained from Lexicon Pharmaceuticals, developed from OmniBank OST#56064. Intra-abdominal fat was measured by magnetic resonance imaging of the methylene proton signal. Lipogenesis from labeled glucose was measured in isolated adipocytes. Lipolysis (glycerol and free fatty acid release) was measured in perifused adipocytes. Intra-abdominal fat in PFK-M-deficient female mice (5-10 months old) was 17 +/- 3% of that of wild-type littermates (n = 4; P < 0.02). Epididymal fat weight in 15 animals (7-9.5 months) was 34 +/- 4% of control littermate (P < 0.002), with 10-30% lower body weight. Basal and insulin-stimulated lipogenesis in PFK-M-deficient epididymal adipocytes was 40% of the rates in cells from heterozygous littermates (n = 3; P < 0.05). The rate of isoproterenol-stimulated lipolysis in wild-type adipocytes declined approximately 10% after 1 h and 50% after 2 h; in PFK-M-deficient cells it declined much more rapidly, 50% in 1 h and 90% in 2 h, and lipolytic oscillations appeared to be damped (n = 4). These results indicate an important role for PFK-M in adipose metabolism. This may be related to the ability of this isoform to generate glycolytic oscillations, because such oscillations may enhance the production of the triacylglycerol precursor alpha-glycerophosphate.
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Affiliation(s)
- Lisa Getty-Kaushik
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jason C. Viereck
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jessie M. Goodman
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Zifang Guo
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Nathan K. LeBrasseur
- Section of Endocrinology, Diabetes and Nutrition, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
| | - Ann-Marie T. Richard
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA
| | - John N. Flanagan
- Section of Endocrinology, Diabetes and Nutrition, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
| | - Gordon C. Yaney
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - James A. Hamilton
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Keith Tornheim
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA
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Getty-Kaushik L, Richard AMT, Deeney JT, Krawczyk S, Shirihai O, Corkey BE. The CB1 antagonist rimonabant decreases insulin hypersecretion in rat pancreatic islets. Obesity (Silver Spring) 2009; 17:1856-60. [PMID: 19644453 PMCID: PMC3808997 DOI: 10.1038/oby.2009.234] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Type 2 diabetes and obesity are characterized by elevated nocturnal circulating free fatty acids, elevated basal insulin secretion, and blunted glucose-stimulated insulin secretion (GSIS). The CB1 receptor antagonist, Rimonabant, has been shown to improve glucose tolerance and insulin sensitivity in vivo but its direct effect on islets has been unclear. Islets from lean littermates and obese Zucker (ZF) and Zucker Diabetic Fatty (ZDF) rats were incubated for 24 h in vitro and exposed to 11 mmol/l glucose and 0.3 mmol/l palmitate (GL) with or without Rimonabant. Insulin secretion was determined at basal (3 mmol/l) or stimulatory (15 mmol/l) glucose concentrations. As expected, basal secretion was significantly elevated in islets from obese or GL-treated lean rats whereas the fold increase in GSIS was diminished. Rimonabant decreased basal hypersecretion in islets from obese rats and GL-treated lean rats without decreasing the fold increase in GSIS. However, it decreased GSIS in islets from lean rats without affecting basal secretion. These findings indicate that Rimonabant has direct effects on islets to reduce insulin secretion when secretion is elevated above normal levels by diet or in obesity. In contrast, it appears to decrease stimulated secretion in islets from lean animals but not in obese or GL-exposed islets.
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Affiliation(s)
- Lisa Getty-Kaushik
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Ann-Marie T. Richard
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jude T. Deeney
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Sarah Krawczyk
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Orian Shirihai
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Barbara E. Corkey
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
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