Modification of PCNA by ISG15 Plays a Crucial Role in Termination of Error-Prone Translesion DNA Synthesis

• DOI: 10.1016/j.molcel.2014.03.031
• Publication Date: 2014-04-24T16:00:59Z
• Authors: Jung Mi Park; Seung Wook Yang; Kyung Ryun Yu; Seung Hyun Ka; Seong Won Lee; Jae Hong Seol; Young Joo Jeon; Chin Ha Chung
• Keywords: DNA Replication; 0301 basic medicine; 0303 health sciences; Binding Sites; DNA Repair; Lysine; Ubiquitin-Protein Ligases; Ubiquitination; Cell Biology; DNA Polymerase II; Arginine; Tripartite Motif Proteins; 03 medical and health sciences; Gene Expression Regulation; Mutation Rate; Mutagenesis; Gene Knockdown Techniques; Proliferating Cell Nuclear Antigen; Cytokines; Humans; Molecular Biology; Ubiquitin Thiolesterase; DNA Damage; HeLa Cells; Transcription Factors

In response to DNA damage, PCNA is mono-ubiquitinated and triggers translesion DNA synthesis (TLS) by recruiting polymerase-η. However, it remained unknown how error-prone TLS is turned off after DNA lesion bypass to prevent mutagenesis. Here we showed that ISG15 modification (ISGylation) of PCNA plays a key role in TLS termination. Upon UV irradiation, EFP, an ISG15 E3 ligase, bound to mono-ubiquitinated PCNA and promoted its ISGylation. ISGylated PCNA then tethered USP10 for deubiquitination and in turn the release of polymerase-η from PCNA. Eventually, PCNA was deISGylated by UBP43 for reloading of replicative DNA polymerases and resuming normal DNA replication. However, ISGylation-defective Lys-to-Arg mutations in PCNA or knockdown of any of ISG15, EFP, or USP10 led to persistent recruitment of mono-ubiquitinated PCNA and polymerase-η to nuclear foci, causing an increase in mutation frequency. These findings establish a crucial role of PCNA ISGylation in termination of error-prone TLS for preventing excessive mutagenesis.