In this study, Affo et al. determine origin and functions of cancer-associated fibroblasts in the liver and uncover distinct subsets that promote the growth of intrahepatic cholangiocarcinoma via different therapeutically targetable mediators. Upon publication of the original article, we realized that we had inadvertently omitted Dr.

The prime function of nucleoli is ribogenesis, however, several other, non-canonical functions have recently been identified, including a role in genotoxic stress response. Upon DNA damage, numerous proteins shuttle dynamically between the nucleolus and the nucleoplasm, yet the underlying molecular mechanisms are incompletely understood. Here, we demonstrate that PARP1 and PARylation contribute to genotoxic stress-induced nucleolar-nucleoplasmic shuttling of key genome maintenance factors in HeLa cells. Our work revealed that the RECQ helicase, WRN, translocates from nucleoli to the nucleoplasm upon treatment with the oxidizing agent H 2 O 2 , the alkylating agent 2-chloroethyl ethyl sulfide (CEES), and the topoisomerase inhibitor camptothecin (CPT). We show that after treatment with H 2 O 2 and CEES, but not CPT, WRN translocation was dependent on PARP1 protein, yet independent of its enzymatic activity. In contrast, nucleolar-nucleoplasmic translocation of the base excision repair protein, XRCC1, was dependent on both PARP1 protein and its enzymatic activity. Furthermore, gossypol, which inhibits PARP1 activity by disruption of PARP1-protein interactions, abolishes nucleolar-nucleoplasmic shuttling of WRN, XRCC1 and PARP1, indicating the involvement of further upstream factors. In conclusion, this study highlights a prominent role of PARP1 in the DNA damage-induced nucleolar-nucleoplasmic shuttling of genome maintenance factors in HeLa cells in a toxicant and protein-specific manner.

ods for risk assessment and classification of chemicals. When establishing new test methods, it is imperative to implement the 3R principle where possible. Ideally such tests should be animal-free and should rely on human-relevant biological systems (Beken et al., 2016;Knudsen et al., 2019).The comet assay is the gold standard in many laboratories for genotoxicity measurements. With its high sensitivity and broad scope of application, it is an attractive technique for analyzing DNA damage induction and repair in a broad variety of cells. Nevertheless, a problematic issue is the lack of inter-laboratory comparability (Ersson et al., 2013). Work on standardization of the comet assay protocol has decreased the inter-experimental and inter-laboratory variability of the assay (Cassano et al., 2020), but also shown its drawbacks (Brunborg et al., 2018;Enciso et al., 2018). The CometChip ® platform provides a high-throughput DNA damage analysis in a 96-well format, but no automated version has been described so far (Sykora et al., 2018). Additionally,

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