Time-lapse imaging reveals dynamic relocalization of PP1gamma throughout the mammalian cell cycle

Mol Biol Cell. 2003 Jan;14(1):107-17. doi: 10.1091/mbc.e02-07-0376.

Abstract

Protein phosphatase 1 (PP1) is a ubiquitous serine/threonine phosphatase that regulates many cellular processes, including cell division. When transiently expressed as fluorescent protein (FP) fusions, the three PP1 isoforms, alpha, beta/delta, and gamma1, are active phosphatases with distinct localization patterns. We report here the establishment and characterization of HeLa cell lines stably expressing either FP-PP1gamma or FP alone. Time-lapse imaging reveals dynamic targeting of FP-PP1gamma to specific sites throughout the cell cycle, contrasting with the diffuse pattern observed for FP alone. FP-PP1gamma shows a nucleolar accumulation during interphase. On entry into mitosis, it localizes initially at kinetochores, where it exchanges rapidly with the diffuse cytoplasmic pool. A dramatic relocalization of PP1 to the chromosome-containing regions occurs at the transition from early to late anaphase, and by telophase FP-PP1gamma also accumulates at the cleavage furrow and midbody. The changing spatio-temporal distribution of PP1gamma revealed using the stable PP1 cell lines implicates it in multiple processes, including nucleolar function, the regulation of chromosome segregation and cytokinesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle / physiology*
  • Cell Division / physiology
  • Cell Nucleolus / metabolism
  • HeLa Cells
  • Humans
  • Phosphoprotein Phosphatases / genetics
  • Phosphoprotein Phosphatases / metabolism*
  • Protein Phosphatase 1
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism

Substances

  • Recombinant Fusion Proteins
  • Phosphoprotein Phosphatases
  • Protein Phosphatase 1