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Adenovirus e4orf4 protein reduces phosphorylation of c-fos and e1a proteins while simultaneously reducing the level of ap-1

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Overview

authors

  • Mueller, Ulrich
  • Kleinberger, T.
  • Shenk, T.

publication date

  • October 1992

journal

  • Journal of Virology  Journal

abstract

  • Adenovirus E1A protein and cyclic AMP cooperate to induce transcription factor AP-1 and viral gene expression in mouse S49 cells. We report that a protein encoded within the viral E4 gene region acts to counterbalance the induction of AP-1 DNA-binding activity by E1A and cyclic AMP. Studies with mutant adenoviruses demonstrated that in the absence of E4orf4 protein, AP-1 DNA-binding activity is induced to substantially higher levels than in wild-type virus-infected cells. The induction is the result of increased production of JunB and c-Fos proteins. Hyperphosphorylated forms of c-Fos and E1A proteins accumulate in the absence of functional E4orf4 protein. We propose that the E4orf4 protein acts to inhibit the activity of a cellular kinase that phosphorylates both the E1A and c-Fos proteins. Phosphorylation-dependent alterations in the activity of c-Fos, E1A, or some unidentified protein might, then, lead to decreased synthesis of AP-1 components. This E4 function likely plays an important role in natural infections, since a mutant virus unable to express the E4orf4 protein is considerably more cytotoxic than the wild-type virus.

subject areas

  • Adenovirus Early Proteins
  • Animals
  • Blotting, Western
  • Cell Survival
  • Cells, Cultured
  • Cyclic AMP
  • Mice
  • Oncogene Proteins, Viral
  • Phosphorylation
  • Precipitin Tests
  • Proto-Oncogene Proteins c-fos
  • Proto-Oncogene Proteins c-jun
  • RNA, Messenger
  • Transcription, Genetic
  • Viral Proteins
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Identity

PubMed Central ID

  • PMC241463

International Standard Serial Number (ISSN)

  • 0022-538X

PubMed ID

  • 1326648
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Additional Document Info

start page

  • 5867

end page

  • 5878

volume

  • 66

issue

  • 10

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