Abstract
Proliferating cell nuclear antigen (PCNA), known as processive protein factor during DNA synthesis, has been shown to be involved in all types of DNA repair mechanisms including nucleotide excision repair (NER) and base excision repair (BER). Our previous study has found that when NER is encountered with BER, BER appears to be dominant over NER, but NER is delayed to allow BER. As an effort to characterize the BER dominancy, we assessed how the levels of PCNA might affect BER. The results were showed that the repair of hydrogen peroxide induced DNA lesions was greatly delayed in serum-deprived cells. Knockdown of PCNA produced similar inhibitory effect, while the overexpression of PCNA abolished the serum deprivation effect. However, the overexpression of PCNA were unfavorable BER in DNA replication inhibition. The results demostrated that PCNA appears to be tightly coupled with DNA replication as the presence of oxidative damages.