The FHA domain determinesDrosophilaChk2/Mnk localization to key mitotic structures and is essential for early embryonic DNA damage responses
In: Molecular Biology of the Cell, Jg. 26 (2015-05-15), S. 1811-1828
Online
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Zugriff:
DNA damage induces Chk2/Mnk-dependent mitotic and developmental blocks in early Drosophila embryos. The Mnk-FHA domain and its phosphopeptide-binding ability play essential dual functions in mediating the embryonic DNA damage response: activating Mnk upon DNA damage and recruiting Mnk to multiple cellular structures independently of DNA damage.
DNA damage responses, including mitotic centrosome inactivation, cell-cycle delay in mitosis, and nuclear dropping from embryo cortex, maintain genome integrity in syncytial Drosophila embryos. A conserved signaling kinase, Chk2, known as Mnk/Loki, is essential for the responses. Here we demonstrate that functional EGFP-Mnk expressed from a transgene localizes to the nucleus, centrosomes, interkinetochore/centromere region, midbody, and pseudocleavage furrows without DNA damage and in addition forms numerous foci/aggregates on mitotic chromosomes upon DNA damage. We expressed EGFP-tagged Mnk deletion or point mutation variants and investigated domain functions of Mnk in vivo. A triple mutation in the phosphopeptide-binding site of the forkhead-associated (FHA) domain disrupted normal Mnk localization except to the nucleus. The mutation also disrupted Mnk foci formation on chromosomes upon DNA damage. FHA mutations and deletion of the SQ/TQ-cluster domain (SCD) abolished Mnk transphosphorylations and autophosphorylations, indicative of kinase activation after DNA damage. A potent NLS was found at the C-terminus, which is required for normal Mnk function. We propose that the FHA domain in Mnk plays essential dual functions in mediating embryonic DNA damage responses by means of its phosphopeptide-binding ability: activating Mnk in the nucleus upon DNA damage and recruiting Mnk to multiple subcellular structures independently of DNA damage.
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The FHA domain determinesDrosophilaChk2/Mnk localization to key mitotic structures and is essential for early embryonic DNA damage responses
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Autor/in / Beteiligte Person: | Takada, Saeko ; Collins, Eric R. ; Kurahashi, Kayo |
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Zeitschrift: | Molecular Biology of the Cell, Jg. 26 (2015-05-15), S. 1811-1828 |
Veröffentlichung: | American Society for Cell Biology (ASCB), 2015 |
Medientyp: | unknown |
ISSN: | 1939-4586 (print) ; 1059-1524 (print) |
DOI: | 10.1091/mbc.e14-07-1238 |
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