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Updated: Jun 24, 2026

Assessment of Global DNA Double-Strand End Resection using BrdU-DNA Labeling coupled with Cell Cycle Discrimination Imaging
Published on: April 28, 2021
hnRNP-U is a specific DNA-dependent protein kinase substrate phosphorylated in response to DNA double-strand breaks
Fredrik M Berglund1, Paul R Clarke
1Biomedical Research Institute, College of Medicine, Dentistry and Nursing, University of Dundee, Level 5, Ninewells Hospital and Medical School, Dundee DD1 9SY, Scotland, UK.
Abstract:
Cellular responses to DNA damage are orchestrated by the large phosphoinositol-3-kinase related kinases ATM, ATR and DNA-PK. We have developed a cell-free system to dissect the biochemical mechanisms of these kinases. Using this system, we identify heterogeneous nuclear ribonucleoprotein U (hnRNP-U), also termed scaffold attachment factor A (SAF-A), as a specific substrate for DNA-PK. We show that hnRNP-U is phosphorylated at Ser59 by DNA-PK in vitro and in cells in response to DNA double-strand breaks. Phosphorylation of hnRNP-U suggests novel functions for DNA-PK in the response to DNA damage.
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