Regulation of oxidative DNA damage repair by DNA polymerase λ and MutYH by cross-talk of phosphorylation and ubiquitination.
It is of pivotal importance for genome stability that repair DNA polymerases (Pols), such as Pols λ and β, which all exhibit considerably reduced fidelity when replicating undamaged DNA, are tightly regulated, because their misregulation could lead to mutagenesis. Recently, we found that the correct repair of the abundant and highly miscoding oxidative DNA lesion 7,8-dihydro-8-oxo-2'-deoxyguanine (8-oxo-G) is performed by an accurate repair pathway that is coordinated by the MutY glycosylase homologue (MutYH) and Pol λ in vitro and in vivo. Pol λ is phosphorylated by Cdk2/cyclinA in late S and G2 phases of the cell cycle, promoting Pol λ stability by preventing it from being targeted for proteasomal degradation by ubiquitination. However, it has remained a mystery how the levels of Pol λ are controlled, how phosphorylation promotes its stability, and how the engagement of Pol λ in active repair complexes is coordinated. Here, we show that the E3 ligase Mule mediates the degradation of Pol λ and that the control of Pol λ levels by Mule has functional consequences for the ability of mammalian cells to deal with 8-oxo-G lesions. Furthermore, we demonstrate that phosphorylation of Pol λ by Cdk2/cyclinA counteracts its Mule-mediated degradation by promoting recruitment of Pol λ to chromatin into active 8-oxo-G repair complexes through an increase in Pol λ's affinity to chromatin-bound MutYH. Finally, MutYH appears to promote the stability of Pol λ by binding it to chromatin. In contrast, Pol λ not engaged in active repair on chromatin is subject for proteasomal degradation.
Institute for Veterinary Biochemistry and Molecular Biology, University of Zürich-Irchel, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
Enni
E
Markkanen
Barbara
B
van Loon
Elena
E
Ferrari
Jason L
JL
Parsons
Grigory L
GL
Dianov
Ulrich
U
Hübscher
D000080242:8-Hydroxy-2'-Deoxyguanosine; D015153:Blotting, Western; D004249:DNA Damage / Q000502:physiology*; D045647:DNA Glycosylases / Q000378:metabolism*; D019951:DNA Polymerase beta / Q000378:metabolism*; D004260:DNA Repair / Q000502:physiology*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D006861:Hydrogen Peroxide; D009841:Oligonucleotides / Q000235:genetics; D010084:Oxidation-Reduction; D010766:Phosphorylation; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
D009841:Oligonucleotides; D025521:Tumor Suppressor Proteins; D000080242:8-Hydroxy-2'-Deoxyguanosine; D006861:Hydrogen Peroxide; C502830:HUWE1 protein, human; D044767:Ubiquitin-Protein Ligases; C415367:DNA polymerase beta2; D019951:DNA Polymerase beta; D045647:DNA Glycosylases; C061738:mutY adenine glycosylase; D003849:Deoxyguanosine