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Glucose-induced de novo synthesis of fatty acyls causes proportional increases in INS-1E cellular lipids
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
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2008 (English)In: NMR in Biomedicine, ISSN 0952-3480, E-ISSN 1099-1492, Vol. 21, no 4, 357-365 p.Article in journal (Refereed) Published
Abstract [en]

Raised concentrations of glucose for extended periods of time have detrimental effects on the insulin-producing P-cell. As de novo synthesis of lipids has been observed under such conditions, it was hypothesized that newly formed lipids may preferentially contain saturated fatty acids, which in particular have been associated with impaired beta-cell function. Glucose-induced de novo synthesis of fatty acids in INS-1E cells cultured in 5.5, 11, 20 or 27 mM glucose for 5 days was assessed by high-resolution magic-angle-spinning (HR-MAS) NMR spectroscopy and gas chromatography-mass spectrometry (GC-MS). The glucose origin of the increase in fatty acyls was verified by replacing glucose with [1-C-13]glucose during culture followed by analysis with two-dimensional H-1-C-13 NMR spectroscopy. The composition of the fatty acyls was determined by GC-MS. Fatty acyls determined by HR-MAS H-1 NMR spectroscopy were increased fivefold in INS-1E cells cultured in 20 or 27mM glucose compared with cells cultured in 5.5mM glucose. The five most abundant fatty acids with their relative percentages in INS-1E cells cultured in 5.5 mM glucose were oleate (33%), palmitate (25%), stearate (19%), octadecenoate (13%) and palmitoleate (4.4%). These proportions were not affected by glucose-induced de novo synthesis in INS-1E cells cultured in 11, 20 or 27 mM glucose. It is concluded that glucose-induced de novo lipid synthesis results in accumulation of both saturated and unsaturated fatty acids in specific proportions that are identical with those present under control conditions.

Place, publisher, year, edition, pages
2008. Vol. 21, no 4, 357-365 p.
Keyword [en]
diabetes, fatty acyls, gas chromatography-mass spectrometry, glucose, high-resolution magic-angle-spinning NMR, INS-1E cells, lipids, metabolomics
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-96440DOI: 10.1002/nbm.1197ISI: 000256460300005PubMedID: 17691080OAI: oai:DiVA.org:uu-96440DiVA: diva2:171013
Available from: 2007-11-14 Created: 2007-11-14 Last updated: 2011-03-18Bibliographically approved
In thesis
1. Glucotoxicity in Insulin-Producing β-Cells
Open this publication in new window or tab >>Glucotoxicity in Insulin-Producing β-Cells
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background and aims: Type 2 diabetes mellitus is connected with elevated glucose levels, which cause impaired glucose-stimulated insulin secretion (GSIS) and degeneration of β-cells. Mechanisms for such glucotoxic effects were explored in the present study.

Materials and methods: INS-1E cells were cultured for 5 days in 5.5, 11, 20 or 27 mM glucose in the presence or absence of AMPK-agonist AICAR. GSIS was determined from INS-1E cells and islets obtained from type 2 diabetes and control donors. Human islets and INS-1E cells were functionally characterized (GSIS) and protein profiled (SELDI-TOF MS). Glucose-induced de novo synthesis of fatty acyls (HR-MAS NMR spectroscopy), fatty acid composition (GC-MS), triglyceride content and specific proteins (Western blotting) were determined in INS-1E cells.

Results: Impaired GSIS was observed from INS-1E cells exposed to chronic hyperglycaemia and islets isolated from type 2 diabetics compared to INS-1E cells cultured at normal glucose levels and control islets, respectively. Several glucose-regulated proteins were found when type 2 diabetes and control islets or mitochondria from INS-1E cells cultured at different glucose concentrations were protein profiled. Glucose induced lipid de novo synthesis of both saturated and unsaturated fatty acids in specific proportions. Glucose-induced impairment of function and mass was reverted by inclusion of AICAR, which lowered levels of pro-apoptotic protein CHOP but left triglyceride content unaffected.

Conclusions: Impaired GSIS and increased apoptosis observed in β-cells after prolonged exposure to elevated glucose concentrations involved accumulation of lipid species in specific proportions, AMPK-inactivation, ER-stress activation and complex, coordinated changes in expression patterns of mitochondrial and human islet proteins.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 45 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 291
Cell biology, type 2 diabetes, SELDI-TOF MS, glucotoxicity, proteomics, insulin secretion, mitochondria, lipids, INS-1E cells, GC-MS, HR-MAS NMR, metabolomics, human islet, AMPK, AICAR, ER stress, apoptosis, Cellbiologi
urn:nbn:se:uu:diva-8309 (URN)978-91-554-7022-7 (ISBN)
Public defence
2007-12-08, B21, BMC, Husargatan 3, Uppsala, 09:15
Available from: 2007-11-14 Created: 2007-11-14Bibliographically approved

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