Active Role for Nibrin in the Kinetics of Atm Activation
- 1 March 2006
- journal article
- research article
- Published by Informa UK Limited in Molecular and Cellular Biology
- Vol. 26 (5), 1691-1699
- https://doi.org/10.1128/mcb.26.5.1691-1699.2006
Abstract
The Atm protein kinase is central to the DNA double-strand break response in mammalian cells. After irradiation, dimeric Atm undergoes autophosphorylation at Ser 1981 and dissociates into active monomers. Atm activation is stimulated by expression of the Mre11/Rad50/nibrin complex. Previously, we showed that a C-terminal fragment of nibrin, containing binding sites for both Mre11 and Atm, was sufficient to provide this stimulatory effect in Nijmegen breakage syndrome (NBS) cells. To discriminate whether nibrin's role in Atm activation is to bind and translocate Mre11/Rad50 to the nucleus or to interact directly with Atm, we expressed an Mre11 transgene with a C-terminal NLS sequence in NBS fibroblasts. The Mre11-NLS protein complexed with Rad50, localized to the nucleus in NBS fibroblasts, and associated with chromatin. However, Atm autophosphorylation was not stimulated in cells expressing Mre11-NLS, nor were downstream Atm targets phosphorylated. To determine whether nibrin-Atm interaction is necessary to stimulate Atm activation, we expressed nibrin transgenes lacking the Atm binding domain in NBS fibroblasts. The nibrin ΔAtm protein interacted with Mre11/Rad50; however, Atm autophosphorylation was dramatically reduced after irradiation in NBS cells expressing the nibrin ΔAtm transgenes relative to wild-type nibrin. These results indicate that nibrin plays an active role in Atm activation beyond translocating Mre11/Rad50 to the nucleus and that this function requires nibrin-Atm interaction.Keywords
This publication has 46 references indexed in Scilit:
- Tumor Suppressor P53 Binding Protein 1 (53bp1) Is Involved in DNA Damage–Signaling PathwaysThe Journal of cell biology, 2001
- An alternative mode of translation permits production of a variant NBS1 protein from the common Nijmegen breakage syndrome alleleNature Genetics, 2001
- Distinct Functional Domains of Nibrin Mediate Mre11 Binding, Focus Formation, and Nuclear LocalizationMolecular and Cellular Biology, 2001
- The Forkhead-associated Domain of NBS1 Is Essential for Nuclear Foci Formation after Irradiation but Not Essential for hRAD50·hMRE11·NBS1 Complex DNA Repair ActivityJournal of Biological Chemistry, 2001
- Chromatin Association of Human Origin Recognition Complex, Cdc6, and Minichromosome Maintenance Proteins during the Cell Cycle: Assembly of Prereplication Complexes in Late MitosisMolecular and Cellular Biology, 2000
- Ataxia telangiectasia-mutated phosphorylates Chk2 in vivo and in vitroProceedings of the National Academy of Sciences, 2000
- Functional link between ataxia-telangiectasia and Nijmegen breakage syndrome gene productsNature, 2000
- ATM phosphorylation of Nijmegen breakage syndrome protein is required in a DNA damage responseNature, 2000
- Requirement of ATM-Dependent Phosphorylation of Brca1 in the DNA Damage Response to Double-Strand BreaksScience, 1999
- A Single Ataxia Telangiectasia Gene with a Product Similar to PI-3 KinaseScience, 1995