Tumor necrosis factor alpha signaling pathway and apoptosis in pancreatic beta cells

Metabolism. 1999 Dec;48(12):1485-92. doi: 10.1016/s0026-0495(99)90234-2.


Cytokines induce apoptosis in pancreatic beta cells, but the exact mechanisms and sequence of events are not clear. Here, we investigate a role for tumor necrosis factor alpha (TNF-alpha) in the apoptosis of beta cells. Using the ribonuclease (RNase) protection assay and the reverse transcriptase-polymerase chain reaction (RT-PCR) method, we confirmed that TNF receptor 1 (TNFR1), TNFR1-associated death domain protein (TRADD), Fas receptor-associated intracellular protein with death domain (FADD), and FADD-like interleukin-1beta-converting enzyme (FLICE) were expressed in the pancreatic beta cell line, MIN6 cells. Fluorescent microscopic examination using Hoechst 33342 dye (Sigma, St Louis, MO) demonstrated that TNF-alpha induced time- and dose-dependent apoptotic nuclear changes in these beta cells. In situ end-labeling (ISEL) DNA analysis revealed that 10 nmol/L TNF-alpha generated new 3'-OH DNA strand breaks. Moreover, qualitative assessment of the induced DNA damage on agarose gels showed that 10 nmol/L TNF-alpha produced characteristic apoptotic patterns of DNA fragments formed by internucleosomal hydrolysis of static chromatin. In addition, C2-ceramides and natural ceramides dispersed in a solvent mixture of ethanol and dodecane induced characteristic features of apoptosis in MIN6 cells, mimicking TNF-induced DNA damage. We also determined endosomal ceramide production after TNF-alpha (10 nmol/L) treatment in MIN6 cells using the diacylglycerol kinase assay. These results suggest that TNF-alpha can cause apoptosis in pancreatic beta cells through TNFR1-linked apoptotic factors, TRADD, FADD, and FLICE, and TNF-induced ceramide production may be involved in the pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing*
  • Animals
  • Antigens, CD / metabolism
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Carrier Proteins / metabolism
  • Ceramides / biosynthesis
  • Ceramides / pharmacology
  • DNA Fragmentation
  • Fas-Associated Death Domain Protein
  • Humans
  • Islets of Langerhans / metabolism
  • Islets of Langerhans / physiology*
  • Mice
  • Proteins / metabolism
  • Receptors, Tumor Necrosis Factor / metabolism
  • Receptors, Tumor Necrosis Factor, Type I
  • Signal Transduction / physiology*
  • TNF Receptor-Associated Death Domain Protein
  • TNF Receptor-Associated Factor 1
  • Tumor Cells, Cultured
  • Tumor Necrosis Factor Receptor-Associated Peptides and Proteins*
  • Tumor Necrosis Factor-alpha / pharmacology
  • Tumor Necrosis Factor-alpha / physiology*


  • Adaptor Proteins, Signal Transducing
  • Antigens, CD
  • Carrier Proteins
  • Ceramides
  • FADD protein, human
  • Fadd protein, mouse
  • Fas-Associated Death Domain Protein
  • Proteins
  • Receptors, Tumor Necrosis Factor
  • Receptors, Tumor Necrosis Factor, Type I
  • TNF Receptor-Associated Death Domain Protein
  • TNF Receptor-Associated Factor 1
  • Tradd protein, mouse
  • Tumor Necrosis Factor Receptor-Associated Peptides and Proteins
  • Tumor Necrosis Factor-alpha