O-GlcNAcylation of myosin phosphatase targeting subunit 1 (MYPT1) dictates timely disjunction of centrosomes

J Biol Chem. 2020 May 22;295(21):7341-7349. doi: 10.1074/jbc.RA119.012401. Epub 2020 Apr 15.


The role of O-linked N-acetylglucosamine (O-GlcNAc) modification in the cell cycle has been enigmatic. Previously, both O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) disruptions have been shown to derail the mitotic centrosome numbers, suggesting that mitotic O-GlcNAc oscillation needs to be in concert with mitotic progression to account for centrosome integrity. Here, using both chemical approaches and biological assays with HeLa cells, we attempted to address the underlying molecular mechanism and observed that incubation of the cells with the OGA inhibitor Thiamet-G strikingly elevates centrosomal distances, suggestive of premature centrosome disjunction. These aberrations could be overcome by inhibiting Polo-like kinase 1 (PLK1), a mitotic master kinase. PLK1 inactivation is modulated by the myosin phosphatase targeting subunit 1 (MYPT1)-protein phosphatase 1cβ (PP1cβ) complex. Interestingly, MYPT1 has been shown to be abundantly O-GlcNAcylated, and the modified residues have been detected in a recent O-GlcNAc-profiling screen utilizing chemoenzymatic labeling and bioorthogonal conjugation. We demonstrate here that MYPT1 is O-GlcNAcylated at Thr-577, Ser-585, Ser-589, and Ser-601, which antagonizes CDK1-dependent phosphorylation at Ser-473 and attenuates the association between MYPT1 and PLK1, thereby promoting PLK1 activity. We conclude that under high O-GlcNAc levels, PLK1 is untimely activated, conducive to inopportune centrosome separation and disruption of the cell cycle. We propose that too much O-GlcNAc is equally deleterious as too little O-GlcNAc, and a fine balance between the OGT/OGA duo is indispensable for successful mitotic divisions.

Keywords: CDK1; MYPT1; O-GlcNAcylation; O-linked N-acetylglucosamine (O-GlcNAc); PLK1; cell cycle; centrosome; mitosis; protein phosphorylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CDC2 Protein Kinase / genetics
  • CDC2 Protein Kinase / metabolism
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cell Line
  • Centrosome / metabolism*
  • Glycosylation
  • Humans
  • Mitosis*
  • Myosin-Light-Chain Phosphatase / genetics
  • Myosin-Light-Chain Phosphatase / metabolism*
  • Polo-Like Kinase 1
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism


  • Cell Cycle Proteins
  • Proto-Oncogene Proteins
  • Protein Serine-Threonine Kinases
  • CDC2 Protein Kinase
  • CDK1 protein, human
  • Myosin-Light-Chain Phosphatase
  • PPP1R12A protein, human