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Nucleic Acids Res. 2018 Sep 6;46(15):7747-7756. doi: 10.1093/nar/gky579.

The transcription-coupled DNA repair-initiating protein CSB promotes XRCC1 recruitment to oxidative DNA damage.

Author information

1
Department of Molecular Genetics, Oncode Institute, Cancer Genomics Netherlands, Erasmus MC, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands.
2
Laboratoire de Biologie et Modélisation de la Cellule (LBMC) CNRS, ENSL, UCBL UMR 5239, Université de Lyon, Ecole Normale Supérieure de Lyon, 69007 Lyon.
3
CEA, Institute of Cellular and Molecular Radiobiology, F-96265 Fontenay aux Roses, France.
4
UMR967 CEA, INSERM, Universités Paris-Diderot et Paris-Sud, F-92265 Fontenay aux Roses, France.

Abstract

Transcription-coupled nucleotide excision repair factor Cockayne syndrome protein B (CSB) was suggested to function in the repair of oxidative DNA damage. However thus far, no clear role for CSB in base excision repair (BER), the dedicated pathway to remove abundant oxidative DNA damage, could be established. Using live cell imaging with a laser-assisted procedure to locally induce 8-oxo-7,8-dihydroguanine (8-oxoG) lesions, we previously showed that CSB is recruited to these lesions in a transcription-dependent but NER-independent fashion. Here we showed that recruitment of the preferred 8-oxoG-glycosylase 1 (OGG1) is independent of CSB or active transcription. In contrast, recruitment of the BER-scaffolding protein, X-ray repair cross-complementing protein 1 (XRCC1), to 8-oxoG lesions is stimulated by CSB and transcription. Remarkably, recruitment of XRCC1 to BER-unrelated single strand breaks (SSBs) does not require CSB or transcription. Together, our results suggest a specific transcription-dependent role for CSB in recruiting XRCC1 to BER-generated SSBs, whereas XRCC1 recruitment to SSBs generated independently of BER relies predominantly on PARP activation. Based on our results, we propose a model in which CSB plays a role in facilitating BER progression at transcribed genes, probably to allow XRCC1 recruitment to BER-intermediates masked by RNA polymerase II complexes stalled at these intermediates.

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