Leptin decreases apoptosis and alters BCL-2 : Bax ratio in clonal rodent pancreatic beta-cells

• Published in: Diabetes/metabolism research and reviews 2007-09, Vol.23 (6), p.497-502
• Main Authors: Brown, James E. P., Dunmore, Simon J.
• Format: Article
• Language: English
• Subjects: Animals; apoptosis; Apoptosis - drug effects; Bax; BCL-2; bcl-2-Associated X Protein - genetics; bcl-2-Associated X Protein - metabolism; beta-cell; Biological and medical sciences; Cell Line; Culture Media, Serum-Free; Endocrinopathies; Fundamental and applied biological sciences. Psychology; Insulin-Secreting Cells - drug effects; Insulin-Secreting Cells - metabolism; Insulin-Secreting Cells - physiology; leptin; Leptin - pharmacology; Medical sciences; Proto-Oncogene Proteins c-bcl-2 - metabolism; Rats; RNA, Messenger - metabolism; Vertebrates: endocrinology
• ISSN: 1520-7552; 1520-7560
• DOI: 10.1002/dmrr.726

Aims/Hypothesis The adipocyte derived peptide hormone leptin is known to regulate apoptosis and cell viability in several cells and tissues, as well as having several pancreatic islet beta‐cell specific effects such as inhibition of glucose‐stimulated insulin secretion. This study investigated the effects of leptin upon apoptosis induced by serum depletion and on expression of the apoptotic regulators B‐cell leukaemia 2 gene product (BCL‐2) and BCL2‐associated X protein (Bax) in the glucose‐responsive BRIN‐BD11 beta‐cell line. Methods BRIN‐BD11 cells were cultured in RPMI 1640 and subsequently serum depleted ± leptin (10 and 50 ng/mL) for 24 h. Cell viability and apoptosis were measured using a modified MTS assay and TUNEL/YO‐PRO‐1 assays, respectively. BCL‐2 and Bax expression were measured by real‐time PCR and Western blotting. Results Leptin caused a reduction in serum‐depleted apoptosis, although it failed to have any effect on the overall cell viability, causing a 68% shift from apoptosis to necrosis. Leptin significantly increased the level of BCL‐2 mRNA expression (150% compared to serum depletion alone), without altering Bax mRNA expression. At the protein level, leptin increased BCL‐2 and decreased Bax, altering the BCL‐2 : Bax ratio. Conclusions We conclude that leptin reduces apoptosis in beta‐cells at physiological concentrations, possibly via its ability to up‐regulate BCL‐2 and Bax expression. Copyright © 2007 John Wiley & Sons, Ltd.