Activation of the protein kinases ATM and ATR following chromosomal breakage prevents initiation of DNA replication and entry into mitosis. However, the effects of ATM and ATR activation in cells already progressing through mitosis are poorly understood. Here we report that ATM and ATR activation induced by DNA double-strand breaks (DSBs) inhibits centrosome-driven spindle assembly in Xenopus laevis mitotic egg extract and somatic cells, delaying mitotic progression. Using a cDNA expression library to screen for ATM and ATR substrates, we identified centrosomal protein CEP63 as an ATM and ATR target required for normal spindle assembly. ATM and ATR phosphorylate Xenopus CEP63 (XCEP63) on Ser 560 and promote its delocalization from the centrosome. Suppression of ATM and ATR activity or mutation of XCEP63 Ser 560 to Ala prevented spindle assembly defects. Consistently, inactivation of the CEP63 gene in avian DT40 cells impaired spindle assembly and prevented ATM- and ATR-dependent effects on mitosis. These data indicate that ATM and ATR control mitotic events in vertebrate cells by targeting CEP63 and centrosome dependent spindle assembly.

An ATM- and ATR-dependent checkpoint inactivates spindle assembly by targeting CEP63 / E. Smith, D. Dejsuphong, A. Balestrini, M. Hampel, C. Lenz, S. Takeda, A. Vindigni, V. Costanzo. - In: NATURE CELL BIOLOGY. - ISSN 1465-7392. - 11:3(2009), pp. 278-285. [10.1038/ncb1835]

An ATM- and ATR-dependent checkpoint inactivates spindle assembly by targeting CEP63

V. Costanzo
2009

Abstract

Activation of the protein kinases ATM and ATR following chromosomal breakage prevents initiation of DNA replication and entry into mitosis. However, the effects of ATM and ATR activation in cells already progressing through mitosis are poorly understood. Here we report that ATM and ATR activation induced by DNA double-strand breaks (DSBs) inhibits centrosome-driven spindle assembly in Xenopus laevis mitotic egg extract and somatic cells, delaying mitotic progression. Using a cDNA expression library to screen for ATM and ATR substrates, we identified centrosomal protein CEP63 as an ATM and ATR target required for normal spindle assembly. ATM and ATR phosphorylate Xenopus CEP63 (XCEP63) on Ser 560 and promote its delocalization from the centrosome. Suppression of ATM and ATR activity or mutation of XCEP63 Ser 560 to Ala prevented spindle assembly defects. Consistently, inactivation of the CEP63 gene in avian DT40 cells impaired spindle assembly and prevented ATM- and ATR-dependent effects on mitosis. These data indicate that ATM and ATR control mitotic events in vertebrate cells by targeting CEP63 and centrosome dependent spindle assembly.
Xenopus egg extracts; double-strand breaks; DNA-damage; mitotic spindle; cell-cycle; centrosome amplification; protein-phosphorylation; self-organization; vertebrate cells; identification
Settore MED/04 - Patologia Generale
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/798644
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