HDAC inhibitor-mediated beta-cell protection against cytokine-induced toxicity is STAT1 Tyr701 phosphorylation independent.

ABSTRACT

Histone deacetylase (HDAC) inhibition protects pancreatic beta-cells against apoptosis induced by the combination of the proinflammatory cytokines interleukin (IL)-1ß and interferon (IFN)-γ. Decreased expression of cell damage-related genes is observed on the transcriptional level upon HDAC inhibition using either IL-1ß or IFN-γ alone. Whereas HDAC inhibition has been shown to regulate NFκB-activity, related primarily to IL-1ß signaling, it is unknown whether the inhibition of HDACs affect IFN-γ signaling in beta-cells. Further, in non-beta-cells, there is a dispute whether HDAC inhibition regulates IFN-γ signaling at the level of STAT1 Tyr701 phosphorylation. Using different small molecule HDAC inhibitors with varying class selectivity, INS-1E wild type and stable HDAC1-3 knockdown pancreatic INS-1 cell lines, we show that IFN-γ-induced Cxcl9 and iNos expression as well as Cxcl9 and GAS reporter activity were decreased by HDAC inhibition in a STAT1 Tyr701 phosphorylation-independent fashion. In fact, knockdown of HDAC1 increased IFN-γ-induced STAT1 phosphorylation.