NDLI: STAT1-mediated down-regulation of Bcl-2 expression is involved in IFN-γ/TNF-α-induced apoptosis in NIT-1 cells.

Content Provider	Directory of Open Access Journals (DOAJ)
Author	Zhao-hui Cao Quan-you Zheng Gui-qing Li Xiao-bo Hu Shao-long Feng Gui-lian Xu Ke-qin Zhang
Abstract	Tumor necrosis factor (TNF)-α and interferon (IFN)-γ are the major pro-inflammatory cytokines involved in beta-cell destruction. The fate of islet beta-cells in the cytokine-induced intrinsic mitochondrial apoptotic pathway is determined by the interaction between members of the Bcl-2 family. However, the mechanism through which beta-cell apoptosis is regulated remains unclear. In this study, we treated the murine beta-cell line NIT-1 with TNF-α and IFN-γ and then investigated the regulation of signal transducer and activator of transcription-1 (STAT-1) and expression of the members of the Bcl-2 family in this apoptotic pathway. Results showed that TNF-α and IFN-γ synergistically reduced NIT-1 cell viability. In addition, the decrease in cell growth was due to apoptosis as shown by apoptotic body formation, detected by confocal laser microscope, and a significant increase in Annexin-Vup(+) cell percentage, detected by flow cytometry. Combination treatment with TNF-α and IFN-γ caused a remarkable increase in the release of cytochrome c, and in the activation of caspase-9 and caspase-3, as well as, an obvious enhancement in STAT-1 phosphorylation; the treatment, however, resulted in the down-regulation in Bcl-2 expression. The enhancement in STAT-1 activity and a down-regulation in Bcl-2 expression was also observed in MIN6 cells, another murine beta-cell derived line, after cells exposure to the combination of TNF-α and IFN-γ treatment. Knockdown of STAT-1 gene expression by siRNA or inhibition of STAT-1 activation with fludarabine reversed Bcl-2 down-expression and led to a significant decrease in apoptosis in TNF-α- and IFN-γ-treated NIT-1 cells. Taken together, our results suggest that STAT1-mediated down-regulation of Bcl-2 is involved in NIT-1 cell apoptosis induced by combination treatment with TNF-α and IFN-γ.
e-ISSN	19326203
DOI	10.1371/journal.pone.0120921
Journal	PLoS ONE
Issue Number	3
Volume Number	10
Language	English
Publisher	Public Library of Science (PLoS)
Publisher Date	2015-01-01
Publisher Place	United States
Access Restriction	Open
Subject Keyword	Medicine Science
Content Type	Text
Resource Type	Article

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