Histone Lysine Methyltransferase SETD8 Promotes Carcinogenesis by Deregulating PCNA Expression

Masashi Takawa,Takaaki Kobayashi,Helen I Field,Tatsuhiko Tsunoda,Yukiko Iwai,Kazuhiro Maejima,Shinya Hayami,Bruce A.J Ponder,Masanori Sugiyama,Koji Ueda,Ryuji Hamamoto,Naoshi Dohmae,Yusuke Nakamura,Yutaka Atomi,Gouji Toyokawa,Yuka Yamane,Shin-Ichi Ohnuma,Masaharu Kogure,Hyun Soo Cho ,Akira Masuda ,Takayuki Aoki

doi:10.1158/0008-5472.can-11-3701

Masashi Takawa, Takaaki Kobayashi + Show 19 more

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https://doi.org/10.1158/0008-5472.can-11-3701

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Abstract

Although the physiologic significance of lysine methylation of histones is well known, whether lysine methylation plays a role in the regulation of nonhistone proteins has not yet been examined. The histone lysine methyltransferase SETD8 is overexpressed in various types of cancer and seems to play a crucial role in S-phase progression. Here, we show that SETD8 regulates the function of proliferating cell nuclear antigen (PCNA) protein through lysine methylation. We found that SETD8 methylated PCNA on lysine 248, and either depletion of SETD8 or substitution of lysine 248 destabilized PCNA expression. Mechanistically, lysine methylation significantly enhanced the interaction between PCNA and the flap endonuclease FEN1. Loss of PCNA methylation retarded the maturation of Okazaki fragments, slowed DNA replication, and induced DNA damage, and cells expressing a methylation-inactive PCNA mutant were more susceptible to DNA damage. An increase of methylated PCNA was found in cancer cells, and the expression levels of SETD8 and PCNA were correlated in cancer tissue samples. Together, our findings reveal a function for lysine methylation on a nonhistone protein and suggest that aberrant lysine methylation of PCNA may play a role in human carcinogenesis.

Highlights

Protein methylation is recently considered an important posttranslational modification and is predominantly found on lysine and arginine residues
RERF-LC-AI and SBC5 cells were from Japanese Collection of Research Bioresources (JCRB) in 2001, and tested and authenticated by DNA profiling for polymorphic short tandem repeat (STR) markers. 253J and 253J-BV cells were from Korean Cell Line Bank (KCLB) in 2001, and tested and authenticated by DNA profiling for polymorphic STR markers
We found overexpression of SETD8 in both non–small cell lung carcinoma (NSCLC) and small cell lung carcinoma (SCLC; Fig. 1A)

Summary

Introduction

Protein methylation is recently considered an important posttranslational modification and is predominantly found on lysine and arginine residues. Lysine methylation involves the addition of 1 to 3 methyl groups on the amino acid's e-amine group, to form mono-, di-, or tri-methyllysine. Its function is best understood in histones [1]. With the exception of Dot1/ DOT1L, all histone lysine methyltransferases (HKMT) contain a SET domain of about 130 amino acids, and so far nearly 40 SET domain–containing HKMTs or potential HKMTs have. Authors' Affiliations: 1Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, The University of Tokyo; 2Laboratory for Biomarker Development, RIKEN, Minato-ku; 3Department of Surgery, Kyorin University School of Medicine, Mitaka; 4Division of Colorectal Surgery, National Cancer Center Hospital, Chuo-ku, Tokyo; 5Biomolecular Characterization Team, RIKEN, Wako, Saitama; 6Laboratory for Medical Informatics, RIKEN, Yokohama, Kanagawa, Japan; Departments of 7Genetics and 8Oncology, Cancer Research UK, Cambridge Research Institute, University of Cambridge, Cambridge; 9Institute of Ophthalmology, University College London, London, United Kingdom; and 10Section of Hematology/Oncology, The University of Chicago, Chicago, Illinois.

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