DNA Demethylation in Retinal Neurocytes Contributes to the Up-Regulation of DNA Repair Protein, Ku80

Abstract

 

Purpose:

 

Ku80 plays a critical role in DNA repair. However, Ku80 is silencedin mature neurocytes. This study aimed to investigate the mechanismof Ku80 silencing and if Ku80 plays a role in DNA repair inretinal neurocytes.

 

Methods:

 

Ku80 expression was measured in the retina of fetus, neonataland adult mice via immunofluorescence. The primary retinal neurocyteswere treated with 5-azacytidine (5-Aza) and analysed by RT-PCRand Western Blot. Analysis of DNA methylation in Ku80 promoterwas performed. DSBs repair efficiency in primary retinal neurocytesafter treated by H₂O₂, was assayed by staining with γ-H2AX.

 

Results:

 

Ku80 is only expressed along the retinal ventricular surfaceof rapidly proliferating cells in the fetus. No expression ofKu80 and Ku70 is observed in the retina after birth. Demethylationby 5-Aza activates Ku80 expression in vitro, while methylationof -179bp in Ku80 promoter induces Ku80 silencing in retinalneurocytes. Ku80 reactivation in retinal neurocytes by 5-Azaenhances DNA integrity after treatment with H₂O₂.

 

Conclusions:

 

Ku80 might be a target for reactivation to increase retinalneuronal DNA repair.  

 

 

 

Keywords: retinal degenerations: cell biology • retina: neurochemistry • retinal development