Loss of H3K9me3 Correlates with ATM Activation and Histone H2AX Phosphorylation Deficiencies in Hutchinson-Gilford Progeria Syndrome.

Haoyue Zhang,Celeste Witting,Kun Wang,Mason Trappio,Kan Cao,Linlin Sun,Di Wu,Michael Shing-Yan Huen

doi:10.1371/journal.pone.0167454

Haoyue Zhang, Celeste Witting + Show 6 more

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https://doi.org/10.1371/journal.pone.0167454

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Journal: PloS one	Publication Date: Dec 1, 2016
Citations: 24	License type: CC BY 4.0

Affiliation: University of Maryland, College Park

Abstract

Compelling evidence suggests that defective DNA damage response (DDR) plays a key role in the premature aging phenotypes in Hutchinson-Gilford progeria syndrome (HGPS). Studies document widespread alterations in histone modifications in HGPS cells, especially, the global loss of histone H3 trimethylated on lysine 9 (H3K9me3). In this study, we explore the potential connection(s) between H3K9me3 loss and the impaired DDR in HGPS. When cells are exposed to a DNA-damaging agent Doxorubicin (Dox), double strand breaks (DSBs) are generated that result in the phosphorylation of histone H2A variant H2AX (gammaH2AX) within an hour. We find that the intensities of gammaH2AX foci appear significantly weaker in the G0/G1 phase HGPS cells compared to control cells. This reduction is associated with a delay in the recruitment of essential DDR factors. We further demonstrate that ataxia-telangiectasia mutated (ATM) is responsible for the amplification of gammaH2AX signals at DSBs during G0/G1 phase, and its activation is inhibited in the HGPS cells that display significant loss of H3K9me3. Moreover, methylene (MB) blue treatment, which is known to save heterochromatin loss in HGPS, restores H3K9me3, stimulates ATM activity, increases gammaH2AX signals and rescues deficient DDR. In summary, this study demonstrates an early DDR defect of attenuated gammaH2AX signals in G0/G1 phase HGPS cells and provides a plausible connection between H3K9me3 loss and DDR deficiency.

Highlights

Hutchinson-Gilford progeria syndrome (HGPS) is a devastating premature aging disorder [1,2]
As shown in S1A and S1B Fig, HGPS fibroblasts showed a slight but significant increase in the number of gammaH2AX foci than the normal control, which is consistent with previous reports that HGPS cells accumulated more double strand breaks (DSBs) [34,35,36]
Our analysis showed that HGPS and normal control fibroblasts had comparable gammaH2AX foci counts, suggesting that similar numbers of DSBs were induced by Dox treatment in HGPS and normal cells

Summary

Introduction

Hutchinson-Gilford progeria syndrome (HGPS) is a devastating premature aging disorder [1,2]. The mutation activates a cryptic splice donor site and yields a 50 amino acid truncated lamin A mutant protein called “progerin” [3,4]. This internal deletion removes a cleavage site of Zmpste (a zinc metallopeptidase STE24 homolog) from lamin A and interferes with lamin A’s post-translational modifications, causing an abnormal retention of a farnesyl tail on the C-terminus of progerin [3,4]. The farnesylated progerin accumulates on the inner nuclear membrane and causes severe nuclear phenotypes including misshapen nuclear morphology, loss of peripheral heterochromatin, histone modification abnormalities, gene transcription alterations, compromised DDR and genome instability [5,6,7,8]

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