Suppressor mechanism of serum thymic factor on tumor necrosis factor-alpha-induced apoptosis in the mouse pancreatic beta-cell line.
Tumor necrosis factor-alpha (TNF-alpha) is a cytokine considered to play a key role in beta-cell destruction in insulin-dependent diabetes mellitus (IDDM). Serum thymic factor (Facteur thymique serique; FTS) is a nonapeptide thymus hormone known to inhibit IDDM in a mouse model. In this study, the effect of TNF-alpha on the murine pancreatic beta-cell line MIN6 was examined. Cell shrinkage and detachment were seen in cells treated with 0-50 ng/ml TNF-alpha for 12h. Oligonucleosomal DNA fragmentation was determined from non-adherent cells, indicating that the TNF-alpha-induced cell destruction was attributed to apoptosis. Fragmented DNA was quantified by enzyme-linked immunosorbent assay to measure the amount of histone-bound oligonucleosomes. FTS was treated with TNF-alpha and the percentage of fragmented DNA was analyzed. The data indicate a distinct reduction of fragmented DNA at a concentration of 1 ng/ml FTS. Expression of TNF receptor I, inducible form of nitric oxide synthase (iNOS), interleukin-1 beta-converting enzyme (ICE), Bcl-2, and nuclear factor kappa B (NF-kappa B) was analyzed by reverse transcriptase-polymerase chain reaction to investigate the suppressor mechanism of FTS on TNF-alpha-induced apoptosis. FTS treatment suppressed the expression of iNOS and Bcl-2 mRNA in TNF-alpha-treated cells. The expression of NF-kappa B mRNA in TNF-alpha-treated cells was enhanced after FTS treatment, while that of ICE mRNA did not change in TNF-alpha-treated cells with or without FTS treatment. These results suggest that the inhibition of MIN6 cell death by FTS on TNF-alpha-induced apoptosis is caused by a negative feedback mechanism involving the inhibition of iNOS induction.
Department of Molecular Immunology, School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
Junko
J
Yasuda
Wakako
W
Nishioka
Akikazu
A
Sakudo
Sachiko
S
Yama
Ruka
R
Setoguchi
Keiichi
K
Saeki
Yoshitsugu
Y
Matsumoto
Akira
A
Awaya
Takashi
T
Onodera
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002460:Cell Line; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D013935:Thymic Factor, Circulating / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D014409:Tumor Necrosis Factor-alpha; D013935:Thymic Factor, Circulating