Phosphoregulation of MgcRacGAP in mitosis involves Aurora B and Cdk1 protein kinases and the PP2A phosphatase

Touré, Aminata and Mzali, Rym and Liot, Caroline and Seguin, Laetitia and Morin, Laurence and Crouin, Catherine and Chen-Yang, Ilin and Tsay, Yeou-Guang and Dorseuil, Olivier and Gacon, Gérard and Bertoglio, Jacques


MgcRacGAP, a Rho GAP essential to cytokinesis, works both as a Rho GTPase regulator and as a scaffolding protein. MgcRacGAP interacts with MKLP1 to form the centralspindlin complex and associates with the RhoGEF Ect2. The GAP activity of MgcRacGAP is regulated by Aurora B phosphorylation. We have isolated B56epsilon, a PP2A regulatory subunit, as a new MgcRacGAP partner. We report here that (i) MgcRacGAP is phosphorylated by Aurora B and Cdk1, (ii) PP2A dephosphorylates Aurora B and Cdk1 phosphorylated sites and (iii) inhibition of PP2A abrogates MgcRacGAP/Ect2 interaction. Therefore, PP2A may regulate cytokinesis by dephosphorylating MgcRacGAP and its interacting partners.