Mitochondrial Dysfunction Is Involved in Apoptosis Induced by Serum Withdrawal and Fatty Acids in the Beta-Cell Line INS-1

Endocrinology. 2003 Jan;144(1):335-45. doi: 10.1210/en.2001-211282.

Abstract

The potential toxic effects of high extracellular concentrations of fatty acids were tested in beta(INS-1)-cells cultured in the absence of serum, a condition known to alter cell survival in various systems. This may in part mimic the situation in type 1 or 2 diabetes where beta-cells are already insulted by various stressful conditions, such as cytokines and oxidative stress. Serum removal caused, over a 36-h period, oxidative stress and an early impairment of mitochondrial function, as revealed by increased superoxide production and markedly reduced mitochondrial membrane potential, but a lack of cytochrome c and apoptosis-inducing factor release in the cytosol. The fatty acids palmitate and oleate considerably accelerated the apoptosis process in serum-starved cells, as revealed by fluorescence-activated cell sorting analysis, morphological changes, chromatin condensation, DNA laddering, poly(ADP-ribose) polymerase cleavage, cytochrome c and apoptosis-inducing factor release, and increased levels of Bax and cytosolic caspase-2. The fatty acids also increased nitric oxide production, apparently independently of inducible nitric oxide synthase induction. Under the same experimental conditions, elevated glucose alone had only a marginal effect on beta-cell apoptosis. Together the results indicate that elevated concentrations of fatty acids are particularly efficient in accelerating the rate of apoptosis of already stressed beta(INS-1)-cells displaying altered mitochondrial function, and that the mitochondrial arm of the apoptosis process is involved in beta-cell lipotoxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects*
  • Apoptosis Inducing Factor
  • Blood*
  • Caspase 2
  • Caspases / metabolism
  • Cell Line
  • Cell Survival
  • Chromatin / ultrastructure
  • Culture Media, Serum-Free*
  • Cytochrome c Group / metabolism
  • Cytosol / metabolism
  • DNA Fragmentation
  • Fatty Acids / pharmacology*
  • Flavoproteins / metabolism
  • Flow Cytometry
  • Glucose / pharmacology
  • Islets of Langerhans / drug effects
  • Islets of Langerhans / ultrastructure*
  • Membrane Potentials
  • Membrane Proteins / metabolism
  • Mitochondria / physiology*
  • Mitochondria / ultrastructure
  • Nitric Oxide / metabolism
  • Oleic Acid / pharmacology
  • Oxidative Stress
  • Palmitic Acid / pharmacology
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-bcl-2*
  • Superoxides / metabolism
  • bcl-2-Associated X Protein

Substances

  • Apoptosis Inducing Factor
  • Chromatin
  • Culture Media, Serum-Free
  • Cytochrome c Group
  • Fatty Acids
  • Flavoproteins
  • Membrane Proteins
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-2-Associated X Protein
  • Superoxides
  • Oleic Acid
  • Palmitic Acid
  • Nitric Oxide
  • Caspase 2
  • Caspases
  • Glucose