Increased expression and activation of c-Jun contributes to human amylin-induced apoptosis in pancreatic islet beta-cells

J Mol Biol. 2002 Nov 22;324(2):271-85. doi: 10.1016/s0022-2836(02)01044-6.


The role of c-Jun in apoptosis evoked by human amylin was investigated using human and rat insulinoma beta-cell lines. Two transient increases in the levels of c-jun mRNA were detected at 30 minutes and eight hours after treatment with human amylin. The level of c-Jun protein was also up-regulated in a time-dependent manner, reaching maximal levels after eight hours of exposure. However, no c-Jun induction was detected in cells treated with vehicle only or with rat amylin, indicating that the amyloidogenic feature of the human peptide may be important for c-Jun induction. We found that c-Jun was activated by phosphorylation specifically at Ser63 at four hours, but not at Ser73, after treatment with human amylin, preceding increased c-Jun protein. Furthermore, expression of an antisense c-jun (AS-c-jun), which suppressed protein levels of both c-Jun and phosphorylated-c-Jun, caused a marked reduction in apoptotic cell death, whereas the corresponding sense c-jun (S-c-jun) had no effect on changes of either c-Jun production or apoptosis. This indicated that increased expression and activation of c-Jun is required for human amylin-induced apoptosis. Immunocytochemical studies showed a significant increase in nuclear staining for c-Jun, phosphorylated-c-Jun (Ser63) and phosphorylated-JNK, suggesting that c-Jun may be activated through activation of JNK. In addition, electrophoretic mobility-shift assays showed that the increase in expression and phosphorylation of c-Jun was associated with increased AP-1 DNA binding activity. Supershift assays demonstrated that c-Jun, c-Fos and ATF-2 are part of the AP-1 complex, indicating that activated c-Jun is dimerized with c-Fos or ATF-2 for control of its target gene expression. Finally, we showed that human amylin triggers AP-1-mediated transcriptional activation. Our results suggest strongly that human amylin induces apoptosis through stimulation of expression and activation of c-Jun, and that co-expression and dimerization of c-Jun and c-fos or ATF-2 may be important for activation of the downstream apoptotic process.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid / pharmacology*
  • Animals
  • Apoptosis / drug effects*
  • Blotting, Northern
  • Blotting, Western
  • Cell Division / drug effects
  • DNA Primers / chemistry
  • DNA, Antisense / pharmacology
  • Electrophoretic Mobility Shift Assay
  • Humans
  • Immunoenzyme Techniques
  • Insulinoma / metabolism
  • Insulinoma / pathology
  • Insulinoma / physiopathology*
  • Islet Amyloid Polypeptide
  • Islets of Langerhans / drug effects*
  • Islets of Langerhans / metabolism
  • Luciferases / metabolism
  • Oligodeoxyribonucleotides, Antisense / pharmacology
  • Phosphorylation
  • Polymerase Chain Reaction
  • Proto-Oncogene Proteins c-jun / antagonists & inhibitors
  • Proto-Oncogene Proteins c-jun / metabolism*
  • Rats
  • Transcription Factor AP-1 / metabolism
  • Tumor Cells, Cultured / drug effects


  • Amyloid
  • DNA Primers
  • DNA, Antisense
  • Islet Amyloid Polypeptide
  • Oligodeoxyribonucleotides, Antisense
  • Proto-Oncogene Proteins c-jun
  • Transcription Factor AP-1
  • Luciferases