Duration of Nuclear NF-κB Action Regulated by Reversible Acetylation

TLDR

NF‑κB nuclear activity requires IkappaB degradation, yet the mechanisms terminating its nuclear action are poorly defined, with new IkappaBα synthesis likely playing a key role. Acetylation of RelA weakens its binding to IkappaBα, and HDAC3‑mediated deacetylation restores this interaction, triggering CRM‑1‑dependent nuclear export and acting as an intranuclear switch that limits NF‑κB activity duration and replenishes cytoplasmic latent complexes.

Abstract

The nuclear expression and action of the nuclear factor kappa B (NF-kappaB) transcription factor requires signal-coupled phosphorylation and degradation of the IkappaB inhibitors, which normally bind and sequester this pleiotropically active factor in the cytoplasm. The subsequent molecular events that regulate the termination of nuclear NF-kappaB action remain poorly defined, although the activation of de novo IkappaBalpha gene expression by NF-kappaB likely plays a key role. Our studies now demonstrate that the RelA subunit of NF-kappaB is subject to inducible acetylation and that acetylated forms of RelA interact weakly, if at all, with IkappaBalpha. Acetylated RelA is subsequently deacetylated through a specific interaction with histone deacetylase 3 (HDAC3). This deacetylation reaction promotes effective binding to IkappaBalpha and leads in turn to IkappaBalpha-dependent nuclear export of the complex through a chromosomal region maintenance-1 (CRM-1)-dependent pathway. Deacetylation of RelA by HDAC3 thus acts as an intranuclear molecular switch that both controls the duration of the NF-kappaB transcriptional response and contributes to the replenishment of the depleted cytoplasmic pool of latent NF-kappaB-IkappaBalpha complexes.