AIM/HYPOTHESIS: The distinct metabolic properties of visceral and subcutaneous adipocytes may be due to inherent characteristics of the cells that are resident in each fat depot. To test this hypothesis, human adipocytes were differentiated in vitro from precursor stromal cells obtained from visceral and subcutaneous fat depots and analysed for genetic, biochemical and metabolic endpoints. METHODS: Stromal cells were isolated from adipose tissue depots of nondiabetic individuals. mRNA levels of adipocyte-specific proteins were determined by real-time RT-PCR. Insulin signalling was evaluated by immunoblotting with specific antibodies. Glucose transport was measured by a 2-deoxy-glucose uptake assay. Adiponectin secretion in the adipocyte-conditioned medium was determined by a specific RIA. RESULTS: With cell differentiation, mRNA levels of PPARG, C/EBPalpha (also known as CEBPA), AP2 (also known as GTF3A), GLUT4 (also known as SLC2A4) were markedly upregulated, whereas GLUT1 (also known as SLC2A1) mRNA did not change. However, expression of C/EBPalpha, AP2 and adiponectin was higher in subcutaneous than in visceral adipocytes. By contrast, adiponectin was secreted at threefold higher rates by visceral than by subcutaneous adipocytes while visceral adipocytes also showed two- to threefold higher insulin-stimulated glucose uptake. Insulin-induced phosphorylation of the insulin receptor, IRS proteins, Akt and extracellular signal-regulated kinase-1/2 was more rapid and tended to decrease at earlier time-points in visceral than in subcutaneous adipocytes. CONCLUSIONS/ INTERPRETATION: Subcutaneous and visceral adipocytes, also when differentiated in vitro from precursor stromal cells, retain differences in gene expression, adiponectin secretion, and insulin action and signalling. Thus, the precursor cells that reside in the visceral and subcutaneous fat depots may already possess inherent and specific metabolic characteristics that will be expressed upon completion of the differentiation programme.
AIM/HYPOTHESIS: The distinct metabolic properties of visceral and subcutaneous adipocytes may be due to inherent characteristics of the cells that are resident in each fat depot. To test this hypothesis, human adipocytes were differentiated in vitro from precursor stromal cells obtained from visceral and subcutaneous fat depots and analysed for genetic, biochemical and metabolic endpoints. METHODS: Stromal cells were isolated from adipose tissue depots of nondiabetic individuals. mRNA levels of adipocyte-specific proteins were determined by real-time RT-PCR. Insulin signalling was evaluated by immunoblotting with specific antibodies. Glucose transport was measured by a 2-deoxy-glucose uptake assay. Adiponectin secretion in the adipocyte-conditioned medium was determined by a specific RIA. RESULTS: With cell differentiation, mRNA levels of PPARG, C/EBPalpha (also known as CEBPA), AP2 (also known as GTF3A), GLUT4 (also known as SLC2A4) were markedly upregulated, whereas GLUT1 (also known as SLC2A1) mRNA did not change. However, expression of C/EBPalpha, AP2 and adiponectin was higher in subcutaneous than in visceral adipocytes. By contrast, adiponectin was secreted at threefold higher rates by visceral than by subcutaneous adipocytes while visceral adipocytes also showed two- to threefold higher insulin-stimulated glucose uptake. Insulin-induced phosphorylation of the insulin receptor, IRS proteins, Akt and extracellular signal-regulated kinase-1/2 was more rapid and tended to decrease at earlier time-points in visceral than in subcutaneous adipocytes. CONCLUSIONS/ INTERPRETATION: Subcutaneous and visceral adipocytes, also when differentiated in vitro from precursor stromal cells, retain differences in gene expression, adiponectin secretion, and insulin action and signalling. Thus, the precursor cells that reside in the visceral and subcutaneous fat depots may already possess inherent and specific metabolic characteristics that will be expressed upon completion of the differentiation programme.
Authors: Kirsi A Virtanen; Peter Lönnroth; Riitta Parkkola; Pauliina Peltoniemi; Markku Asola; Tapio Viljanen; Tuula Tolvanen; Juhani Knuuti; Tapani Rönnemaa; Risto Huupponen; Pirjo Nuutila Journal: J Clin Endocrinol Metab Date: 2002-08 Impact factor: 5.958
Authors: Susan A Phillips; Theodore P Ciaraldi; Deborah K Oh; Michelle K Savu; Robert R Henry Journal: Am J Physiol Endocrinol Metab Date: 2008-07-29 Impact factor: 4.310
Authors: Anna Leonardini; Luigi Laviola; Sebastio Perrini; Annalisa Natalicchio; Francesco Giorgino Journal: PPAR Res Date: 2010-02-23 Impact factor: 4.964
Authors: Shilpa H Jain; Joseph M Massaro; Udo Hoffmann; Guido A Rosito; Ramachandran S Vasan; Annaswamy Raji; Christopher J O'Donnell; James B Meigs; Caroline S Fox Journal: Diabetes Care Date: 2009-02-17 Impact factor: 19.112