Regulation of Nuclear Translocation of HDAC3 by IκBα Is Required for Tumor Necrosis Factor Inhibition of Peroxisome Proliferator-activated Receptor γ Function*

Inhibition of peroxisome proliferator-activated receptor γ (PPARγ) function by TNF-α contributes to glucose and fatty acid metabolic disorders in inflammation and cancer, although the molecular mechanism is not fully understood. In this study, we demonstrate that nuclear translocation of HDAC3 is regulated by TNF-α, and this event is required for inhibition of transcriptional activity of PPARγ by TNF-α. HDAC3 is associated with IκBα in the cytoplasm. After IκBα degradation in response to TNF-α, HDAC3 is subject to nuclear translocation, leading to an increase in HDAC3 activity in the nucleus. This event leads to subcellular redistribution of HDAC3. Knock-out of IκBα, but not p65 or p50, leads to disappearance of HDAC3 in the cytoplasm, which is associated with HDAC3 enrichment in the nucleus. These data suggest that inhibition of PPARγ by TNF-α is not associated with a reduction in the DNA binding activity of PPARγ. Rather, these results suggest that IκBα-dependent nuclear translocation of HDAC3 is responsible for PPARγ inhibition by TNF-α.