L-Alanine induces changes in metabolic and signal transduction gene expression in a clonal rat pancreatic beta-cell line and protects from pro-inflammatory cytokine-induced apoptosis.

Abstract

Acute effects of nutrient stimuli on pancreatic beta-cell function are widely reported; however, the chronic effects of insulinotropic amino acids, such as L-alanine, on pancreatic beta-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 (N(G)-methyl-L-arginine acetate) or the iNOS and NADPH oxidase inhibitor DPI (diphenylene iodonium) on apoptosis induced by a pro-inflammatory cytokine mix [IL-1beta (interleukin-1beta), TNF-alpha (tumour necrosis factor-alpha) and IFN-gamma (interferon-gamma)] 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 beta-cell function in vivo.

• Authors: Grainne A Cunningham, Neville H McClenaghan, Peter R Flatt, Philip Newsholme
• Journal: Clinical science (London, England : 1979) (Clin Sci (Lond)) Vol. 109 Issue 5 Pg. 447-55 (Nov 2005) ISSN: 0143-5221 [Print] England
• PMID: 16045439 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cytokines
• Insulin
• Nitrites
• Reactive Nitrogen Species
• Reactive Oxygen Species
• Nitric Oxide
• Alanine

Topics

• Alanine (pharmacology)
• Animals
• Apoptosis (drug effects)
• Cell Line
• Clone Cells (drug effects, metabolism)
• Cytokines (pharmacology)
• Gene Expression Regulation (drug effects)
• Insulin (metabolism)
• Insulin Secretion
• Insulin-Secreting Cells (drug effects, metabolism, pathology)
• Nitric Oxide (biosynthesis)
• Nitrites (metabolism)
• Oligonucleotide Array Sequence Analysis
• Polymerase Chain Reaction (methods)
• Rats
• Reactive Nitrogen Species (antagonists & inhibitors, physiology)
• Reactive Oxygen Species (antagonists & inhibitors, metabolism)
• Signal Transduction (drug effects, genetics)