A Novel Interaction of Ecdysoneless (ECD) Protein with R2TP Complex Component RUVBL1 Is Required for the Functional Role of ECD in Cell Cycle Progression

Mol Cell Biol. 2015 Dec 28;36(6):886-99. doi: 10.1128/MCB.00594-15.


Ecdysoneless (ECD) is an evolutionarily conserved protein whose germ line deletion is embryonic lethal. Deletion of Ecd in cells causes cell cycle arrest, which is rescued by exogenous ECD, demonstrating a requirement of ECD for normal mammalian cell cycle progression. However, the exact mechanism by which ECD regulates cell cycle is unknown. Here, we demonstrate that ECD protein levels and subcellular localization are invariant during cell cycle progression, suggesting a potential role of posttranslational modifications or protein-protein interactions. Since phosphorylated ECD was recently shown to interact with the PIH1D1 adaptor component of the R2TP cochaperone complex, we examined the requirement of ECD phosphorylation in cell cycle progression. Notably, phosphorylation-deficient ECD mutants that failed to bind to PIH1D1 in vitro fully retained the ability to interact with the R2TP complex and yet exhibited a reduced ability to rescue Ecd-deficient cells from cell cycle arrest. Biochemical analyses demonstrated an additional phosphorylation-independent interaction of ECD with the RUVBL1 component of the R2TP complex, and this interaction is essential for ECD's cell cycle progression function. These studies demonstrate that interaction of ECD with RUVBL1, and its CK2-mediated phosphorylation, independent of its interaction with PIH1D1, are important for its cell cycle regulatory function.

Publication types

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

MeSH terms

  • ATPases Associated with Diverse Cellular Activities
  • Apoptosis Regulatory Proteins / metabolism
  • Carrier Proteins / analysis
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Casein Kinase II / metabolism
  • Cell Cycle*
  • Cell Line, Tumor
  • DNA Helicases / metabolism*
  • Gene Deletion
  • HEK293 Cells
  • Humans
  • Mitosis
  • Mitotic Index
  • Mutation
  • Phosphorylation
  • Protein Interaction Maps*


  • Apoptosis Regulatory Proteins
  • Carrier Proteins
  • ECD protein, human
  • PIH1D1 protein, human
  • Casein Kinase II
  • ATPases Associated with Diverse Cellular Activities
  • DNA Helicases
  • RUVBL1 protein, human