Comparative Proteomic Analysis of Histone Post-translational Modifications upon Ischemia/Reperfusion-Induced Retinal Injury

We present a detailed quantitative
map of single and coexisting
histone post-translational modifications (PTMs) in rat retinas affected
by ischemia and reperfusion (I/R) injury. Retinal I/R injury contributes
to serious ocular diseases, which can lead to vision loss and blindness.
We applied linear ion trap–orbitrap hybrid tandem mass spectrometry
(MS/MS) to quantify 131 single histone marks and 143 combinations
of multiple histone marks in noninjured and injured retinas. We observed
34 histone PTMs that exhibited significantly (p <
0.05) different abundance between healthy and I/R injured eyes, of
which we confirmed three H4 histone marks by Western blotting. H4K20me2
was up to 4-fold change up-regulated after the injury and is associated
with the response to DNA damage as demonstrated by an increase in
the phosphorylation of p53 and Chk1. This study demonstrates that
quantitative MS provides a sensitive and accurate way to dissect the
changes in the histone code after retinal injury. Specifically, DNA
damage associated histone PTMs may contribute to neurovascular degeneration
during the process of ischemia/reperfusion injury.