The HDAs (a subfamily of histone deacetylases), a class of Zn²⁺-dependent histone deacetylases, are highly homologous to the reduced potassium dependency 3 (RPD3) in yeast. HDAs extensively regulate chromosome stability, gene transcription, and protein activity by catalyzing the removal of acetyl group from histone and non-histone lysine residues. HDA-mediated deacetylation is essential for plant growth, development, and responses to abiotic stress. We review the research progress in HDAs regarding the discovery, structures, classification, deacetylation process, and roles in regulating plant responses to abiotic stress. Furthermore, this paper prospects the future research on HDAs, aiming to provide theoretical support for the research on epigenetic regulation mediated by HDAs.
Histone Deacetylases/classification* ; Zinc/metabolism* ; Stress, Physiological/physiology* ; Plants/genetics*

Histone deacetylase (HDAC) has been highlighted as one of key players in tumorigenesis and angiogenesis. Recently, several derivatives of psammaplin (Psams) from a marine sponge have been known to inhibit the HDAC activity, but the molecular mechanism for the inhibition has not fully understood. Here, we explored the mode of action of Psams for the inhibition of HDAC activity in the molecular and cellular level. Among the derivatives, psammaplin A (Psam A) showed the potent inhibitory activity in enzyme assay and anti-proliferation assay with IC50 value of 0.003 and 1 microM, respectively. Psam A selectively induced hyperacetylation of histones in the cells, resulting in the upregulation of gelsolin, a well-known HDAC target gene, in a transcriptional level. In addition, reduced Psam A showed a stronger inhibitory activity than that of non-reduced one. Notably, glutathione-depleted cells were not sensitive to Psam A, implying that cellular reduction of the compound is responsible for the HDAC inhibition of Psam A after uptake into the cells. Together, these data demonstrate that Psam A could exhibit its activity under the reduced condition in the cells and be a new natural prodrug targeting HDAC.
Tyrosine/*analogs & derivatives/chemistry/pharmacology ; Prodrugs/chemistry/*pharmacology ; Oxidation-Reduction ; Molecular Structure ; Humans ; Histones/metabolism ; Histone Deacetylases/*antagonists & inhibitors/*classification/genetics/metabolism ; Hela Cells ; Enzyme Inhibitors/chemistry/*pharmacology ; Disulfides/chemistry/*pharmacology ; Cell Proliferation ; Biological Products/chemistry/*pharmacology ; Acetylation