SUMOylation of RepoMan during late telophase regulates dephosphorylation of lamin A

Dephosphorylation of lamin A, which triggers nuclear lamina reconstitution, is crucial for the completion of mitosis. However, the specific phosphatase and regulatory mechanism that allow timely lamin A dephosphorylation remain unclear. Here, we report that RepoMan, a regulatory subunit of protein phosphatase 1γ (PP1γ) is transiently modified with SUMO-2 at K762 during late telophase. SUMOylation of RepoMan markedly enhanced its binding affinity with lamin A. Moreover, the SUMOylated RepoMan/PP1γ contributes to lamin A recruitment to telophase chromosomes and dephosphorylation of the mitotic lamin A phosphorylation. Expression of a SUMO-2 mutant defective in interaction with SUMO interacting motif (SIM) resulted in failure of the lamin A and RepoMan association, along with abrogation of lamin A dephosphorylation and subsequent nuclear lamina formation. These findings strongly suggested that RepoMan/PP1γ recruits lamin A through SUMO-SIM interaction. Thus, transient SUMOylation of RepoMan plays an important role in the spatio-temporal regulation of lamin A dephosphorylation and the subsequent nuclear lamina formation at the end of mitosis.