Damaged DNA-binding protein 2 accelerates UV-damaged DNA repair in human corneal endothelium.
OBJECTIVE
To determine damaged DNA-binding protein 2-gene expression levels in vitro and ex vivo, and the degree of DNA repair in damaged DNA-binding protein 2-overexpressing cultured human corneal endothelium after ultraviolet irradiation.


METHODS
Constitutive damaged DNA-binding protein 2-gene expression levels in various human tissues were determined by semi-quantitative reverse transcription-polymerase chain reactions. The dynamics of nucleotide excision repair-related gene expression in cultured human corneal endothelium were investigated in a ribonuclease protection assay after ultraviolet-irradiation. The effect of damaged DNA-binding protein 2 on DNA repair was studied after ultraviolet-irradiation in cultured human corneal endothelium infected with adenovirus carrying damaged DNA-binding protein 2.


RESULTS
Human corneal endothelium and epithelium in the donor cornea had the highest constitutive damaged DNA-binding protein 2-gene expression of the various human tissues studied. Gene expression level dynamics associated with nucleotide excision repair factors after ultraviolet-irradiation showed that the increase in the rate of damaged DNA-binding protein 2-gene expression in cultured human corneal endothelium was highest of the nucleotide excision repair-related genes studied. An in vivo DNA repair assay showed that DNA repair efficiency in damaged DNA-binding protein 2-overexpressing cultured human corneal endothelium after ultraviolet-irradiation was significantly improved as compared with that in the control human corneal endothelium.


CONCLUSIONS
The human corneal endothelium abundantly expresses the damaged DNA-binding protein 2-gene that is produced efficiently on ultraviolet exposure. This overexpressed damaged DNA-binding protein 2 in the human corneal endothelium contributes to the protection system against DNA damage after ultraviolet-irradiation. Our findings show a critical role for damaged DNA-binding protein 2 in DNA repair to maintain the human corneal endothelium function.
Inoki
Taeko
T
Department of Ophthalmology, Jichi Medical School, Tochigi, Japan.
Endo
Hitoshi
H
Inoki
Yutaka
Y
Hamamoto
Toshiro
T
Tsuru
Tadahiko
T
Mori
Toshio
T
Miyata
Kazunori
K
Amano
Shiro
S
Yamagami
Satoru
S
D000328:Adult; D000368:Aged; D002478:Cells, Cultured; D004249:DNA Damage / Q000235:genetics; D004260:DNA Repair / Q000235:genetics*; D004270:DNA, Circular / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D004728:Endothelium, Corneal / Q000528:radiation effects*; D005136:Eye Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014466:Ultraviolet Rays
D004270:DNA, Circular; D004268:DNA-Binding Proteins; D005136:Eye Proteins; C115368:MBD2 protein