Regulation of human DNA polymerase delta in the cellular responses to DNA damage

Abstract

The p12 subunit of polymerase delta (Pol d) is degraded in response to DNA damage induced by UV, alkylating agents, oxidative, and replication stresses. This leads to the conversion of the Pol d4 holoenzyme to the heterotrimer, Pol d3. We review studies that establish that Pol d3 formation is an event that could have a major impact on cellular processes in genomic surveillance, DNA replication, and DNA repair. p12 degradation is dependent on the apical ataxia telangiectasia and Rad3 related (ATR) kinase and is mediated by the ubiquitin-proteasome system. Pol d3 exhibits properties of an ''antimutator'' polymerase, suggesting that it could contribute to an increased surveillance against mutagenesis, for example, when Pol d carries out bypass synthesis past small base lesions that engage in spurious base pairing. Chromatin immunoprecipitation analysis and examination of the spatiotemporal recruitment of Pol d to sites of DNA damage show that Pol d3 is the primary form of Pol d associated with cyclobutane pyrimidine dimer lesions and therefore should be considered as the operative form of Pol d engaged in DNA repair. We propose a model for the switching of Pol d with translesion polymerases, incorporating the salient features of the recently determined structure of monoubiquitinated proliferating cell nuclear antigen and emphasizing the role of Pol d3. Because of the critical role of Pol d activity in DNA replication and repair, the formation of Pol d3 in response to DNA damage opens the prospect that pleiotropic effects may ensue. This opens the horizons for future exploration of how this novel response to DNA damage contributes to genomic stability. Environ. Mol. Mutagen. 53:683-698, 2012. V V C 2012 Wiley Periodicals, Inc.

A Novel Function of CRL4Cdt2

“…2 plays a key role in eukaryotic DNA replication and is also involved in gap filling during DNA repair (1,2). Human Pol ␦ is a heterotetramer (Pol ␦4) composed of the p125 (catalytic), p50, p68, and p12 subunits (2)(3)(4)(5).…”

“…Human Pol ␦ is a heterotetramer (Pol ␦4) composed of the p125 (catalytic), p50, p68, and p12 subunits (2)(3)(4)(5). Evidence in yeast supports a model for a division of labor between Pol ␦ and Pol ⑀ in which Pol ␦ is largely responsible for the synthesis of the lagging strand, and Pol ⑀ is largely responsible for the synthesis of the leading strand (6 -9).…”

“…Human Pol ␦4 is regulated in response to DNA damage (2,22). The p12 subunit of Pol ␦ is degraded in response to UV radiation, alkylating agents, and replication stress under the control of ATR, resulting in the conversion of Pol ␦4 to Pol ␦3, the heterotrimer lacking p12 (22).…”

“…Presteady state kinetic analyses have shown that Pol ␦3 has an increased rate constant (k Pol-exo ) for transfer of primer ends from the polymerase to the 3Ј-to 5Ј-exonuclease (exo) catalytic sites and a decrease in k Pol , the rate constant for polymerization. These changes define Pol ␦3 as having a greater proofreading ability than Pol ␦4, providing a rationale for its formation in response to DNA damage (2,24,25).…”

Comparative proteomics analysis of global cellular stress responses to hydroxyurea-induced DNA damage in HeLa cells

“…In the previous studies, we had observed that Pol d is also regulated in the DDR as reviewed by Lee et al (2012). The Pol d smallest subunit p12 is degraded in response to DNA damage that is induced by UV irradiation, alkylating agents, or replication stresses Meng et al 2009;Zhang et al 2007Zhang et al , 2013.…”