ROS-mediated EB1 phosphorylation through Akt/GSK3β pathway: implication in cancer cell response to microtubule-targeting agents
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Marion Le Grand1,2, Amandine Rovini1,3, Veronique Bourgarel-Rey1,2, Stephane Honore1,2, Sonia Bastonero1, Diane Braguer1 and Manon Carre1
1 Aix Marseille Université, Inserm, CRO2 UMR_S 911, Marseille, France
2 APHM, Hopital Timone, Marseille, France
3 Department of Neurology, Mayo Clinic, Rochester, MN, USA.
Manon Carré, email:
Keywords: EB1 phosphorylation, microtubule dynamics, mitochondrial ROS, chemotherapy, Akt/GSK3β pathway
Received: March 6, 2014 Accepted: May 16, 2014 Published: May 18, 2014
Microtubule-targeting agents (MTAs) are largely administered in adults and children cancers. Better deciphering their mechanism of action is of prime importance to develop more convenient therapy strategies. Here, we addressed the question of how reactive oxygen species (ROS) generation by mitochondria can be necessary for MTA efficacy. We showed for the first time that EB1 associates with microtubules in a phosphorylation-dependent manner, under control of ROS. By using phospho-defective mutants, we further characterized the Serine 155 residue as critical for EB1 accumulation at microtubule plus-ends, and both cancer cell migration and proliferation. Phosphorylation of EB1 on the Threonine 166 residue triggered opposite effects, and was identified as a requisite molecular switch in MTA activities. We then showed that GSK3β activation was responsible for MTA-triggered EB1 phosphorylation, resulting from ROS-mediated inhibition of upstream Akt. We thus disclosed here a novel pathway by which generation of mitochondrial ROS modulates microtubule dynamics through phosphorylation of EB1, improving our fundamental knowledge about this oncogenic protein, and pointing out the need to re-examine the current dogma of microtubule targeting by MTAs. The present work also provides a strong mechanistic rational to the promising therapeutic strategies that currently combine MTAs with anti-Akt targeted therapies.
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