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  • An ATR-PrimPol pathway confers tolerance to oncogenic KRAS-induced and heterochromatin-associated replication stress.

An ATR-PrimPol pathway confers tolerance to oncogenic KRAS-induced and heterochromatin-associated replication stress.

Nature communications (2023-08-18)
Taichi Igarashi, Marianne Mazevet, Takaaki Yasuhara, Kimiyoshi Yano, Akifumi Mochizuki, Makoto Nishino, Tatsuya Yoshida, Yukihiro Yoshida, Nobuhiko Takamatsu, Akihide Yoshimi, Kouya Shiraishi, Hidehito Horinouchi, Takashi Kohno, Ryuji Hamamoto, Jun Adachi, Lee Zou, Bunsyo Shiotani
ABSTRACT

Activation of the KRAS oncogene is a source of replication stress, but how this stress is generated and how it is tolerated by cancer cells remain poorly understood. Here we show that induction of KRASG12V expression in untransformed cells triggers H3K27me3 and HP1-associated chromatin compaction in an RNA transcription dependent manner, resulting in replication fork slowing and cell death. Furthermore, elevated ATR expression is necessary and sufficient for tolerance of KRASG12V-induced replication stress to expand replication stress-tolerant cells (RSTCs). PrimPol is phosphorylated at Ser255, a potential Chk1 substrate site, under KRASG12V-induced replication stress and promotes repriming to maintain fork progression and cell survival in an ATR/Chk1-dependent manner. However, ssDNA gaps are generated at heterochromatin by PrimPol-dependent repriming, leading to genomic instability. These results reveal a role of ATR-PrimPol in enabling precancerous cells to survive KRAS-induced replication stress and expand clonally with accumulation of genomic instability.

MATERIALS
Product Number
Brand
Product Description

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Anti-DNA-RNA Hybrid Antibody, clone S9.6, clone S9.6, from mouse
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Anti-HP1α Antibody, clone15.19s2, clone 15.19s2, Upstate®, from mouse
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Roscovitine, A potent, reversible, and selective inhibitor of Cdks that exhibits about 10-fold greater efficacy towards p34-cdk1 and p33-cdk2 and 20-fold greater efficacy towards p33-cdk5 relative to Olomoucine.
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Anti-phospho-Histone H3 (Ser10) Antibody, Mitosis Marker, Upstate®, from rabbit