PLK1 and β-TrCP-dependent ubiquitination and degradation of Rap1GAP controls cell proliferation

PLoS One. 2014 Oct 17;9(10):e110296. doi: 10.1371/journal.pone.0110296. eCollection 2014.

Abstract

Rap1GAP is a GTPase-activating protein (GAP) that specifically stimulates the GTP hydrolysis of Rap1 GTPase. Although Rap1GAP is recognized as a tumor suppressor gene and downregulated in various cancers, little is known regarding the regulation of Rap1GAP ubiquitination and degradation under physiological conditions. Here, we demonstrated that Rap1GAP is ubiquitinated and degraded through proteasome pathway in mitosis. Proteolysis of Rap1GAP requires the PLK1 kinase and β-TrCP ubiquitin ligase complex. We revealed that PLK1 interacts with Rap1GAP in vivo through recognition of an SSP motif within Rap1GAP. PLK1 phosphorylates Ser525 in conserved 524DSGHVS529 degron of Rap1GAP and promotes its interaction with β-TrCP. We also showed that Rap1GAP was a cell cycle regulator and that tight regulation of the Rap1GAP degradation in mitosis is required for cell proliferation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Proliferation*
  • GTPase-Activating Proteins / chemistry
  • GTPase-Activating Proteins / genetics
  • GTPase-Activating Proteins / metabolism*
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Mitosis
  • Polo-Like Kinase 1
  • Protein Binding
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • Proteolysis*
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Ubiquitination*
  • beta-Transducin Repeat-Containing Proteins / genetics
  • beta-Transducin Repeat-Containing Proteins / metabolism*

Substances

  • Cell Cycle Proteins
  • GTPase-Activating Proteins
  • Proto-Oncogene Proteins
  • RAP1GAP protein, human
  • beta-Transducin Repeat-Containing Proteins
  • Protein Serine-Threonine Kinases

Grants and funding

This work was supported by the National Natural Science Foundation of China (30872947, 31071193, and 81171964). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.