Inhibition of histone deacetylase activity suppresses IFN-γ induction of tripartite motif 22 via CHIP-mediated proteasomal degradation of IRF-1.

Tripartite motif (TRIM)22 plays an important role in IFN-mediated antiviral activity. We previously demonstrated that IFN regulatory factor (IRF)-1 was crucial for basal and IFN-induced TRIM22 transcription via binding to a novel cis-element named 5' extended IFN-stimulating response element. In this study, we investigated the role of histone deacetylase (HDAC) activity in TRIM22 induction by IFN-γ and its underlying mechanism. We found that the HDAC activity, especially that conferred by HDAC6, was required for IFN-γ-induced TRIM22 transcription. Importantly, inhibition of HDAC activity by trichostatin A (TSA) enhanced the hyperacetylation of heat shock protein (HSP)90 and suppressed its chaperone activity for IRF-1. Further study showed that TSA treatment promoted the proteasomal degradation of IRF-1 protein via enhancing the association of IRF-1 with the ubiquitin E3 ligase carboxyl terminus of Hsc70-interacting protein. Moreover, carboxyl terminus of Hsc70-interacting protein was found to be involved in the TSA-mediated inhibitory effect on IFN-γ induction of TRIM22 as well as other IRF-1-dependent IFN-stimulated genes. This study may provide novel insight into the role of HDAC activity in the transcriptional control of IFN-stimulated gene induction.