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Mio depletion links mTOR regulation to Aurora A and Plk1 activation at mitotic centrosomes.

Platani M, Trinkle-Mulcahy L, Porter M, Jeyaprakash AA, Earnshaw WC - J. Cell Biol. (2015)

Bottom Line: In this study, we report that Mio, a highly conserved member of the SEACAT/GATOR2 complex necessary for the activation of mTORC1 kinase, plays a critical role in mitotic spindle formation and subsequent chromosome segregation by regulating the proper concentration of active key mitotic kinases Plk1 and Aurora A at centrosomes and spindle poles.Mio-depleted cells showed reduced activation of Plk1 and Aurora A kinase at spindle poles and an impaired localization of MCAK and HURP, two key regulators of mitotic spindle formation and known substrates of Aurora A kinase, resulting in spindle assembly and cytokinesis defects.Our results indicate that a major function of Mio in mitosis is to regulate the activation/deactivation of Plk1 and Aurora A, possibly by linking them to mTOR signaling in a pathway to promote faithful mitotic progression.

View Article: PubMed Central - HTML - PubMed

Affiliation: Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK m.platani@ed.ac.uk Bill.Earnshaw@ed.ac.uk.

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Spindle assembly factors HURP and MCAK are misregulated after Mio depletion. (A) Control and Mio-depleted cells were fixed and immunostained with α-HURP (green), α-tubulin (red), and DNA (blue). (B) Control and Mio-depleted cells transfected with GFP-MCAK (green) were fixed and immunostained with α-pericentrin (red) and DNA (blue). (C) Control and Mio-depleted cells were fixed and immunostained with α-MPM2 (red), α-tubulin (green), and DNA (blue). Bars, 10 µm.
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fig7: Spindle assembly factors HURP and MCAK are misregulated after Mio depletion. (A) Control and Mio-depleted cells were fixed and immunostained with α-HURP (green), α-tubulin (red), and DNA (blue). (B) Control and Mio-depleted cells transfected with GFP-MCAK (green) were fixed and immunostained with α-pericentrin (red) and DNA (blue). (C) Control and Mio-depleted cells were fixed and immunostained with α-MPM2 (red), α-tubulin (green), and DNA (blue). Bars, 10 µm.

Mentions: The distribution of HURP on the spindle was dramatically altered upon Mio depletion. The protein was then evenly distributed throughout the spindle, and the chromosome-proximal characteristic band was lost (Fig. 7 A). A similar mislocalization of HURP was previously seen in cells treated with selective Aurora A inhibitors or depleted of the Aurora A–activating partner TPX2 (Kesisova et al., 2013).


Mio depletion links mTOR regulation to Aurora A and Plk1 activation at mitotic centrosomes.

Platani M, Trinkle-Mulcahy L, Porter M, Jeyaprakash AA, Earnshaw WC - J. Cell Biol. (2015)

Spindle assembly factors HURP and MCAK are misregulated after Mio depletion. (A) Control and Mio-depleted cells were fixed and immunostained with α-HURP (green), α-tubulin (red), and DNA (blue). (B) Control and Mio-depleted cells transfected with GFP-MCAK (green) were fixed and immunostained with α-pericentrin (red) and DNA (blue). (C) Control and Mio-depleted cells were fixed and immunostained with α-MPM2 (red), α-tubulin (green), and DNA (blue). Bars, 10 µm.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4494011&req=5

fig7: Spindle assembly factors HURP and MCAK are misregulated after Mio depletion. (A) Control and Mio-depleted cells were fixed and immunostained with α-HURP (green), α-tubulin (red), and DNA (blue). (B) Control and Mio-depleted cells transfected with GFP-MCAK (green) were fixed and immunostained with α-pericentrin (red) and DNA (blue). (C) Control and Mio-depleted cells were fixed and immunostained with α-MPM2 (red), α-tubulin (green), and DNA (blue). Bars, 10 µm.
Mentions: The distribution of HURP on the spindle was dramatically altered upon Mio depletion. The protein was then evenly distributed throughout the spindle, and the chromosome-proximal characteristic band was lost (Fig. 7 A). A similar mislocalization of HURP was previously seen in cells treated with selective Aurora A inhibitors or depleted of the Aurora A–activating partner TPX2 (Kesisova et al., 2013).

Bottom Line: In this study, we report that Mio, a highly conserved member of the SEACAT/GATOR2 complex necessary for the activation of mTORC1 kinase, plays a critical role in mitotic spindle formation and subsequent chromosome segregation by regulating the proper concentration of active key mitotic kinases Plk1 and Aurora A at centrosomes and spindle poles.Mio-depleted cells showed reduced activation of Plk1 and Aurora A kinase at spindle poles and an impaired localization of MCAK and HURP, two key regulators of mitotic spindle formation and known substrates of Aurora A kinase, resulting in spindle assembly and cytokinesis defects.Our results indicate that a major function of Mio in mitosis is to regulate the activation/deactivation of Plk1 and Aurora A, possibly by linking them to mTOR signaling in a pathway to promote faithful mitotic progression.

View Article: PubMed Central - HTML - PubMed

Affiliation: Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK m.platani@ed.ac.uk Bill.Earnshaw@ed.ac.uk.

Show MeSH
Related in: MedlinePlus