Affiliation:
1. Center for Comparative Oncology, University of California, Davis, California 95616
Abstract
ABSTRACT
DNA polymerase eta (PolH), a Y family translesion polymerase, is required for repairing UV-induced DNA damage, and loss of PolH is responsible for early onset of malignant skin cancers in patients with xeroderma pigmentosum variant (XPV), an autosomal recessive disorder. Here, we show that PolH, a target of the p53 tumor suppressor, is a short-half-life protein. We found that PolH is degraded by proteasome, which is enhanced upon UV irradiation. We also found that PolH interacts with Pirh2 E3 ligase, another target of the p53 tumor suppressor, via the polymerase-associated domain in PolH and the RING finger domain in Pirh2. In addition, we show that overexpression of Pirh2 decreases PolH protein stability, whereas knockdown of Pirh2 increases it. Interestingly, we found that PolH is recruited by Pirh2 and degraded by 20S proteasome in a ubiquitin-independent manner. Finally, we observed that Pirh2 knockdown leads to accumulation of PolH and, subsequently, enhances the survival of UV-irradiated cells. We postulate that UV irradiation promotes cancer formation in part by destabilizing PolH via Pirh2-mediated 20S proteasomal degradation.
Publisher
American Society for Microbiology
Subject
Cell Biology,Molecular Biology
Cited by
58 articles.
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