Histone H4K16 acetylation (H4K16ac) is a key epigenetic mark essential for chromatin structure and DNA repair, which is substantially reduced in the accelerated aging disorder Hutchinson-Gilford progeria syndrome (HGPS). The specific enzymes governing H4K16ac homeostasis, particularly the deacetylase responsible for its loss in HGPS, remain poorly defined. Here, we sought to identify the enzymes regulating H4K16ac and determine if their inhibition could rescue HGPS-associated cellular defects. Using systematic siRNA screening in HeLa and U2OS cells, we confirmed that KAT8/MOF is the principal H4K16 acetyltransferase. Surprisingly, we identified HDAC2 as the dominant class I histone deacetylase for H4K16ac; knockdown of the highly homologous HDAC1 had no effect. While SIRT1 knockdown also increased H4K16ac, its contribution was minimal in HGPS vascular smooth muscle cells (VSMCs) compared to HDAC2. Crucially, selective pharmacological inhibition of HDAC2, but not SIRT1, robustly restored H4K16ac levels in HGPS VSMCs. This restoration led to a significant rescue of premature aging phenotypes, including improvements in nuclear morphology, preservation of proliferative capacity (Ki67) at late passages, and a significant reduction in cellular senescence. The effects of HDAC2 inhibition on cellular senescence and nuclear morphology suggests that HDAC2-mediated histone deacetylation contributes directly to the pathological features of HGPS, extending the functional impact of HDAC2 inhibition beyond DNA repair defects to fundamental aspects of cellular aging.
OptoLoop: An optogenetic tool to probe the functional role of genome organization
The genome folds inside the cell nucleus into hierarchical architectural features, such as chromatin loops and domains. If and how this genome organization influences the