US3 protein kinase of HSV-1 cycles between the cytoplasm and nucleus and interacts with programmed cell death protein 4 (PDCD4) to block apoptosis

Proc Natl Acad Sci U S A. 2011 Aug 30;108(35):14632-6. doi: 10.1073/pnas.1111942108. Epub 2011 Aug 15.


The U(S)3 protein kinase of herpes simplex virus 1 plays a key role in blocking apoptosis induced by viral gene products or exogenous agents. The U(S)3 protein kinase is similar to protein kinase A with respect to substrate range and specificity. We report that in the yeast two-hybrid system a domain of U(S)3 essential for antiapoptotic activity reacted with programmed cell death protein 4 (PDCD4). We report that U(S)3 interacts with PDCD4, that PDCD4 is posttranslationally modified in infected cells both in a U(S)3-dependent and -independent fashion, and that depletion of PDCD4 by siRNA blocked apoptosis induced by a Δα4 mutant virus. In infected cells, PDCD4 accumulates in the nucleus, whereas U(S)3 accumulates in the cytoplasm. Studies designed to elucidate the convergence of these proteins led to the discovery that U(S)3 protein kinase cycles between the nucleus and cytoplasm and that U(S)3 retains PDCD4 in infected cell nuclei.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Apoptosis Regulatory Proteins / physiology*
  • Apoptosis*
  • Cell Nucleus / metabolism*
  • Cytoplasm / metabolism*
  • HeLa Cells
  • Humans
  • Protein Processing, Post-Translational
  • Protein-Serine-Threonine Kinases / physiology*
  • RNA, Small Interfering / genetics
  • RNA-Binding Proteins / physiology*
  • Viral Proteins / physiology*


  • Apoptosis Regulatory Proteins
  • PDCD4 protein, human
  • RNA, Small Interfering
  • RNA-Binding Proteins
  • Viral Proteins
  • Protein-Serine-Threonine Kinases
  • US3 protein, Human herpesvirus 1