Hsp90-dependent assembly of the DBC2/RhoBTB2-Cullin3 E3-ligase complex

PLoS One. 2014 Mar 7;9(3):e90054. doi: 10.1371/journal.pone.0090054. eCollection 2014.

Abstract

The expression of the wild-type tumor-suppressor gene DBC2 (Deleted-in-Breast Cancer 2, a.k.a RhoBTB2) is suppressed in many cancers, in addition to breast cancer. In a screen for Cdc37-associated proteins, DBC2 was identified to be a potential client protein of the 90 kDa heat shock protein (Hsp90) chaperone machine. Pull down assays of ectopically expressed DBC2 confirmed that DBC2 associated with Hsp90 and its co-chaperone components in reticulocyte lysate and MCF7 cells. Similar to other atypical Rho GTPases, DBC2 was found to have retained the capacity to bind GTP. The ability of DBC2 to bind GTP was modulated by the Hsp90 ATPase cycle, as demonstrated through the use of the Hsp90 chemical inhibitors, geldanamycin and molybdate. The binding of full length DBC2 to GTP was suppressed in the presence of geldanamycin, while it was enhanced in the presence of molybdate. Furthermore, assembly of DBC2-Cullin3-COP9 E3 ligase complexes was Hsp90-dependent. The data suggest a new paradigm for Hsp90-modulated assembly of a Cul3/DBC2 E3 ubiquitin ligase complex that may extend to other E3 ligase complexes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Cullin Proteins / genetics
  • Cullin Proteins / metabolism*
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism*
  • HSP90 Heat-Shock Proteins / genetics
  • HSP90 Heat-Shock Proteins / metabolism*
  • Humans
  • Immunoprecipitation
  • Mass Spectrometry
  • Protein Binding
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism*
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*

Substances

  • CUL3 protein, human
  • Cullin Proteins
  • HSP90 Heat-Shock Proteins
  • RHOBTB2 protein, human
  • Tumor Suppressor Proteins
  • Ubiquitin-Protein Ligases
  • GTP-Binding Proteins