Human cytomegalovirus IE1-72 activates ataxia telangiectasia mutated kinase and a p53/p21-mediated growth arrest response

J Virol. 2005 Sep;79(17):11467-75. doi: 10.1128/JVI.79.17.11467-11475.2005.


Human cytomegalovirus (HCMV) encodes several proteins that can modulate components of the cell cycle machinery. The UL123 gene product, IE1-72, binds the Rb-related, p107 protein and relieves its repression of E2F-responsive promoters; however, it is unable to induce quiescent cells to enter S phase in wild-type (p53(+/+)) cells. IE1-72 also induces p53 accumulation through an unknown mechanism. We present here evidence suggesting that IE1-72 may activate the p53 pathway by increasing the levels of p19(Arf) and by inducing the phosphorylation of p53 at Ser15. Phosphorylation of this residue by IE1-72 expression alone or HCMV infection is found to be dependent on the ataxia-telangiectasia mutated kinase. IE2-86 expression leads to p53 phosphorylation and may contribute to this phenotype in HCMV-infected cells. We also found that IE1-72 promotes p53 nuclear accumulation by abrogating p53 nuclear shuttling. These events result in the stimulation of p53 activity, leading to a p53- and p21-dependent inhibition of cell cycle progression from G(1) to S phase in cells transiently expressing IE1-72. Thus, like many of the small DNA tumor viruses, the first protein expressed upon HCMV infection activates a p53 response by the host cell.

Publication types

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

MeSH terms

  • Animals
  • Ataxia Telangiectasia Mutated Proteins
  • Cell Cycle
  • Cell Cycle Proteins / metabolism*
  • Cell Line
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cytomegalovirus / metabolism
  • Cytomegalovirus / physiology*
  • DNA-Binding Proteins / metabolism*
  • Fibroblasts / cytology
  • Fibroblasts / virology
  • G1 Phase
  • Immediate-Early Proteins / metabolism*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Protein-Serine-Threonine Kinases / metabolism*
  • Tumor Suppressor Protein p53 / metabolism*
  • Tumor Suppressor Proteins / metabolism*
  • Viral Proteins / metabolism*


  • Cell Cycle Proteins
  • Cyclin-Dependent Kinase Inhibitor p21
  • DNA-Binding Proteins
  • IE1 protein, cytomegalovirus
  • Immediate-Early Proteins
  • Tumor Suppressor Protein p53
  • Tumor Suppressor Proteins
  • Viral Proteins
  • Phosphatidylinositol 3-Kinases
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Protein-Serine-Threonine Kinases