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PP1/Repo-Man Dephosphorylates Mitotic Histone H3 at T3 and Regulates Chromosomal Aurora B Targeting

2011; Elsevier BV; Volume: 21; Issue: 9 Linguagem: Inglês

10.1016/j.cub.2011.03.047

1879-0445

Junbin Qian, Bart Lesage, Monique Beullens, Aleyde Van Eynde, Mathieu Bollen,

Photosynthetic Processes and Mechanisms

The transient mitotic histone H3 phosphorylation by various protein kinases regulates chromosome condensation and segregation, but the counteracting phosphatases have been poorly characterized [1-8]. We show here that PP1γ is the major histone H3 phosphatase acting on the mitotically phosphorylated (ph) residues H3T3ph, H3S10ph, H3T11ph, and H3S28ph. In addition, we identify Repo-Man, a chromosome-bound interactor of PP1γ [9], as a selective regulator of H3T3ph and H3T11ph dephosphorylation. Repo-Man promotes H3T11ph dephosphorylation by an indirect mechanism but directly and specifically targets H3T3ph for dephosphorylation by associated PP1γ. The PP1γ/Repo-Man complex opposes the protein kinase Haspin-mediated spreading of H3T3ph to the chromosome arms until metaphase and catalyzes the net dephosphorylation of H3T3ph at the end of mitosis. Consistent with these findings, Repo-Man modulates in a PP1-dependent manner the H3T3ph-regulated chromosomal targeting of Aurora kinase B and its substrate MCAK. Our study defines a novel mechanism by which PP1 counteracts Aurora B.