Autophosphorylation of ataxia-telangiectasia mutated (ATM) is regulated by protein phosphatase 2A in vivo

Goodarzi, Aaron, Jonnalagadda, Jyoti C, Douglas, Pauline, Young, David, Ruiqiong, Ye, Moorhead, Greg BG, Lees-Miller, Susan P and Khanna, Kum Kum (2004) Autophosphorylation of ataxia-telangiectasia mutated (ATM) is regulated by protein phosphatase 2A in vivo. EMBO Journal, 23. pp. 4451-4461. ISSN 0261-4189

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Abstract

Ionizing radiation induces autophosphorylation of the ataxia-telangiectasia mutated (ATM) protein kinase on serine 1981; however, the precise mechanisms that regulate ATM activation are not fully understood. Here, we show that the protein phosphatase inhibitor okadaic acid (OA) induces autophosphorylation of ATM on serine 1981 in unirradiated cells at concentrations that inhibit protein phosphatase 2A-like activity in vitro. OA did not induce -H2AX foci, suggesting that it induces ATM autophosphorylation by inactivation of a protein phosphatase rather than by inducing DNA double-strand breaks. In support of this, we show that ATM interacts with the scaffolding (A) subunit of protein phosphatase 2A (PP2A), that the scaffolding and catalytic (C) subunits of PP2A interact with ATM in undamaged cells and that immunoprecipitates of ATM from undamaged cells contain PP2A-like protein phosphatase activity. Moreover, we show that IR induces phosphorylation-dependent dissociation of PP2A from ATM and loss of the associated protein phosphatase activity. We propose that PP2A plays an important role in the regulation of ATM autophosphorylation and activity in vivo.

Item Type: Article
Schools and Departments: School of Life Sciences > Sussex Centre for Genome Damage and Stability
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Depositing User: Aaron Goodarzi
Date Deposited: 06 Feb 2012 19:26
Last Modified: 23 Jul 2012 12:08
URI: http://sro.sussex.ac.uk/id/eprint/20604
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