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ATM Engages Autodegradation of the E3 Ubiquitin Ligase COP1 After DNA Damage
David Dornan,1Harumi Shimizu,1Angie Mah,1Tanay Dudhela,1Michael Eby,2Karen O'Rourke,1Somasekar Seshagiri,2Vishva M. Dixit1*
The ataxia telangiectasia mutated (ATM) protein kinase is acritical component of a DNA-damage response network configuredto maintain genomic integrity. The abundance of an essentialdownstream effecter of this pathway, the tumor suppressor proteinp53, is tightly regulated by controlled degradation throughCOP1 and other E3 ubiquitin ligases, such as MDM2 and Pirh2;however, the signal transduction pathway that regulates theCOP1-p53 axis following DNA damage remains enigmatic. We observedthat in response to DNA damage, ATM phosphorylated COP1 on Ser387and stimulated a rapid autodegradation mechanism. Ionizing radiationtriggered an ATM-dependent movement of COP1 from the nucleusto the cytoplasm, and ATM-dependent phosphorylation of COP1on Ser387 was both necessary and sufficient to disrupt the COP1-p53complex and subsequently to abrogate the ubiquitination anddegradation of p53. Furthermore, phosphorylation of COP1 onSer387 was required to permit p53 to become stabilized and toexert its tumor suppressor properties in response to DNA damage.
1 Department of Physiological Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA. 2 Department of Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
* To whom correspondence should be addressed. E-mail: dixit{at}gene.com
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106, 17493-17498
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