Figure 1From: Histone H4 deacetylation plays a critical role in early gene silencing during neuronal apoptosisNuclear histone deacetylase (HDAC) activity in the retina is increased following optic nerve crush (ONC). The data shown was adjusted for protein input and normalized to day 0 control samples. The mean (± SE) HDAC activity is shown (n = 3-5 retinas per data point). (A) No increase in HDAC activity was observed in control eyes (OD) post ONC. There was a significant increase in nuclear HDAC activity in the crush samples (OS) at both 5 and 7 days post ONC (*P = 0.0014 for day 5 vs. day 0 and **P = 0.0006 for day 7 vs. day 0). HDAC activity in this assay was completely inhibited by 500 nM of trichostatin A (TSA). (B) HDAC activity in nuclear extracts from retinas of mice 5 days post ONC was titrated with TSA (n = 3 samples at each concentration). Both control and experimental samples displayed similar inhibition kinetics with an IC50 value ranging from 15 -- 22 nM TSA, comparable to the reported IC50 values of 1 -- 10 nM for class I HDACs [61]. (C) HDAC activity in the same samples as (B) was titrated with the HDAC2 and HDAC3 selective inhibitor apicidin [62]. Apicidin results in an 80% reduction in nuclear HDAC activity, yielding an IC50 ranging from 1.88 to 2.55 nM, consistent with the reported HDAC3 IC50 for apicidin [26]. These data suggest that the majority of nuclear HDAC activity in the retina is provided by class I HDACs, principally HDAC2 and HDAC3. AFU, arbitrary fluorescence units.Back to article page