Acute effects of nutrient stimuli on pancreatic β-cell function are widely reported; however, the chronic effects of insulinotropic amino acids, such as L-alanine, on pancreatic β-cell function and integrity are unknown. In the present study, the effects of prolonged exposure (24 h) to the amino acid L-alanine on insulin secretory function, gene expression and pro-inflammatory cytokine-induced apoptosis were studied using clonal BRIN-BD11 cells. Expression profiling of BRIN-BD11 cells chronically exposed to L-alanine was performed using oligonucleotide microarray analysis. The effect of alanine, the iNOS (inducible nitric oxide synthase) inhibitor NMA (NG-methyl-L-arginine acetate) or the iNOS and NADPH oxidase inhibitor DPI (diphenylene iodonium) on apoptosis induced by a pro-inflammatory cytokine mix [IL-1β (interleukin-1β), TNF-α (tumour necrosis factor-α) and IFN-γ (interferon-γ)] was additionally assessed by flow cytometry. Culture for 24 h with 10 mM L-alanine resulted in desensitization to the subsequent acute insulin stimulatory effects of L-alanine. This was accompanied by substantial changes in gene expression of BRIN-BD11 cells. Sixty-six genes were up-regulated >1.8-fold, including many involved in cellular signalling, metabolism, gene regulation, protein synthesis, apoptosis and the cellular stress response. Subsequent functional experiments confirmed that L-alanine provided protection of BRIN-BD11 cells from pro-inflammatory cytokine-induced apoptosis. Protection from apoptosis was mimicked by NMA or DPI suggesting L-alanine enhances intracellular antioxidant generation. These observations indicate important long-term effects of L-alanine in regulating gene expression, secretory function and the integrity of insulin-secreting cells. Specific amino acids may therefore play a key role in β-cell function in vivo.
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November 2005
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Research Article|
October 24 2005
L-Alanine induces changes in metabolic and signal transduction gene expression in a clonal rat pancreatic β-cell line and protects from pro-inflammatory cytokine-induced apoptosis
Grainne A. Cunningham;
Grainne A. Cunningham
*Department of Biochemistry, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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Neville H. Mcclenaghan;
Neville H. Mcclenaghan
†School of Biomedical Sciences, University of Ulster, Coleraine, N. Ireland, U.K.
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Peter R. Flatt;
Peter R. Flatt
†School of Biomedical Sciences, University of Ulster, Coleraine, N. Ireland, U.K.
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Philip Newsholme
*Department of Biochemistry, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
Correspondence: Professor Philip Newsholme (email philip.newsholme@ucd.ie).
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Publisher: Portland Press Ltd
Received:
May 05 2005
Revision Received:
June 24 2005
Accepted:
July 27 2005
Accepted Manuscript online:
July 27 2005
Online ISSN: 1470-8736
Print ISSN: 0143-5221
The Biochemical Society
2005
Clin Sci (Lond) (2005) 109 (5): 447–455.
Article history
Received:
May 05 2005
Revision Received:
June 24 2005
Accepted:
July 27 2005
Accepted Manuscript online:
July 27 2005
Citation
Grainne A. Cunningham, Neville H. Mcclenaghan, Peter R. Flatt, Philip Newsholme; L-Alanine induces changes in metabolic and signal transduction gene expression in a clonal rat pancreatic β-cell line and protects from pro-inflammatory cytokine-induced apoptosis. Clin Sci (Lond) 1 November 2005; 109 (5): 447–455. doi: https://doi.org/10.1042/CS20050149
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