Microarray analysis of cytokine activation of apoptosis pathways in the thyroid.
It has been suggested that Fas-mediated apoptosis plays an important role in the pathogenesis of autoimmune thyroid diseases. Our previous studies have demonstrated that normal primary thyroid epithelial cells are resistant to Fas-mediated apoptosis, but the resistance can be overcome by pretreatment with a combination of interferon-gamma (IFN-gamma) and IL-1beta. To understand the molecular mechanism responsible for the IFN-gamma/IL-1beta effects, we profiled changes in the transcription induced by these two cytokines in normal human thyroid cells, using cDNA microarrays. We found that IFN-gamma/IL-1beta showed a significant increase in apoptosis-related genes such as inducible nitric oxide synthase (iNOS), receptor-interacting protein 2 (RIP2), and caspases 10. These increases were confirmed by other methods, including real-time PCR and Western blot. Furthermore, the sensitization of primary thyroid epithelial cells to Fas-mediated apoptosis by IFN-gamma/IL-1beta was significantly blocked by a general caspase inhibitor, z-VAD, or by the combination of two specific individual caspase inhibitors. In addition, our results showed that IFN-gamma/IL-1beta enhance p38 MAPK phosphorylation and that SB 203580, a p38 MAPK inhibitor, can inhibit IFN-gamma/IL-1beta-induced p38 MAPK phosphorylation. SB 203580 also significantly prevented cytokine-induced iNOS expression and caspase activation and thus blocked Fas-mediated apoptosis of thyroid cells sensitized by IFN-gamma/IL-1beta. In conclusion, our data suggest that both p38 MAPK and iNOS are involved in IFN-gamma/IL-1beta-induced sensitization of the thyroid cells to Fas-mediated apoptosis via the activation of caspases 3, 7, and 10 and that this pathway may be further activated by BID. This hints that inflammatory cytokines regulate death-receptor-mediated apoptosis at multiple points in the process.
Wang
Su He
SH
Department of Medicine, University of Michigan Medical School, Ann Arbor, MI 48109-0648, USA.
Van Antwerp
Mary
M
Kuick
Rork
R
Gauger
Paul G
PG
Doherty
Gerard M
GM
Fan
Yang Yi
YY
Baker
James R
JR
D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D051023:BH3 Interacting Domain Death Agonist Protein / Q000502:physiology; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000502:physiology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000494:pharmacology*; D052247:Nitric Oxide Synthase Type II / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis; D015398:Signal Transduction / Q000502:physiology; D013961:Thyroid Gland / Q000166:cytology / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects; D019014:fas Receptor / Q000378:metabolism / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology
D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D053583:Interleukin-1beta; D019014:fas Receptor; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II; D048051:p38 Mitogen-Activated Protein Kinases; D020169:Caspases