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J Biol Chem. 2014 Aug 15;289(33):22739-48. doi: 10.1074/jbc.M114.550459. Epub 2014 Jun 12.

Ubiquitin-specific peptidase 20 regulates Rad17 stability, checkpoint kinase 1 phosphorylation and DNA repair by homologous recombination.

Author information

1
From the Division of Hematology-Oncology, Dept of Internal Medicine, and the Cancer Center, University Of New Mexico, Albuquerque, New Mexico 87131.
2
the Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02215.
3
the Department of Medicine, University of Florida, Gainesville, Florida 32610, and.
4
From the Division of Hematology-Oncology, Dept of Internal Medicine, and the Cancer Center, University Of New Mexico, Albuquerque, New Mexico 87131, moshaheen@salud.unm.edu.

Abstract

Rad17 is a subunit of the Rad9-Hus1-Rad1 clamp loader complex, which is required for Chk1 activation after DNA damage. Rad17 has been shown to be regulated by the ubiquitin-proteasome system. We have identified a deubiquitylase, USP20 that is required for Rad17 protein stability in the steady-state and post DNA damage. We demonstrate that USP20 and Rad17 interact, and that this interaction is enhanced by UV exposure. We show that USP20 regulation of Rad17 is at the protein level in a proteasome-dependent manner. USP20 depletion results in poor activation of Chk1 protein by phosphorylation, consistent with Rad17 role in ATR-mediated phosphorylation of Chk1. Similar to other DNA repair proteins, USP20 is phosphorylated post DNA damage, and its depletion sensitizes cancer cells to damaging agents that form blocks ahead of the replication forks. Similar to Chk1 and Rad17, which enhance recombinational repair of collapsed replication forks, we demonstrate that USP20 depletion impairs DNA double strand break repair by homologous recombination. Together, our data establish a new function of USP20 in genome maintenance and DNA repair.

KEYWORDS:

Checkpoint Control; Cisplatin; DNA Damage Response; DNA Repair; Deubiquitylation (Deubiquitination); Homologous Recombination; USP20; chk1; rad17

PMID:
24923443
PMCID:
PMC4132780
DOI:
10.1074/jbc.M114.550459
[Indexed for MEDLINE]
Free PMC Article

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