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Expression of the poly(ADP-ribose) polymerase gene following natural and induced DNA strand breakage and effect of hyperexpression on DNA repair.

Abstract：

:The catalytic activity of the nuclear enzyme poly(ADP-ribose) polymerase (NAD+ ADP-ribosyl transferase, EC 2,4,2,30) is totally dependent upon the presence of DNA strand breaks. Having isolated a full-length cDNA for the polymerase, we have now evaluated the effect of endogenously and exogenously induced DNA strand breaks on the transcriptional control of this enzyme. During retinoic acid or dimethyl-sulfoxide-induced differentiation of HL-60 human leukemia cells, which may involve DNA breaks as well as other changes in chromatin, mRNA levels for the polymerase increased very early and remained high for up to 48 h after which it decreased to pre-induced levels. Polymerase transcript levels did not change, however, during the induction of DNA strand breaks by dimethylsulfate, a variety of other alkylating agents, X-irradiation, or UV-irradiation in several mammalian cell lines. It appears that in sharp contrast to the catalytic requirement of the polymerase, the induction of transcription of the polymerase gene may not be a strand-break-dependent process. The noninducibility of the polymerase gene following DNA damage suggested that there may be adequate levels of the polymerase in the cells to cope with DNA damage. To test this hypothesis we examined the efficacy of DNA repair in Cos cells engineered to overexpress the polymerase. Although there was a slight augmentation of the repair rate, this increase was apparent only after very high levels of DNA damage and only at early repair times. After a longer repair period, the extent of repair in control cell was similar to that in the cell overexpressing the polymerase. We thus conclude that the basal levels of the polymerase are adequate for significant amounts of DNA damage.

journal_name

Carcinogenesis

journal_title

Carcinogenesis

authors

Bhatia K,Pommier Y,Giri C,Fornace AJ,Imaizumi M,Breitman TR,Cherney BW,Smulson ME

doi

10.1093/carcin/11.1.123

subject

Has Abstract

pub_date

1990-01-01 00:00:00

pages

123-8

issue

eissn

0143-3334

issn

1460-2180

journal_volume

pub_type

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Expression of the poly(ADP-ribose) polymerase gene following natural and induced DNA strand breakage and effect of hyperexpression on DNA repair.