Bcl-2 and adenovirus E1B 19 kDA protein prevent E1A-induced processing of CPP32 and cleavage of poly(ADP-ribose) polymerase

Oncogene. 1996 Feb 1;12(3):529-35.


The E1A oncoproteins of adenovirus type 5 are potent inducers of apoptotic cell death. To manifest growth promoting and transforming properties, therefore, E1A requires the co-expression of a suppressor of apoptosis. During normal viral infection, this function is provided by the E1B 19 kDa protein. However, the cellular suppressor Bcl-2 can substitute for 19K during infection, and both proteins can effectively cooperate with E1A to facilitate transformation of primary cells in culture. How E1A induces apoptosis and at what point(s) on this pathway Bcl-2 and E1B 19K act are not presently known. Here, we demonstrate that E1A-induced apoptosis is accompanied by specific endo-proteolytic cleavage of poly(ADP-ribose) polymerase (PARP), an event that is linked to the Ced-3/ICE apoptotic pathway in other systems. PARP cleavage was also observed in p53-null cells infected with 19K- virus expressing 13S E1A. In addition to PARP cleavage, expression of E1A caused processing of the zymogen form of CPP32, a Ced-3/ICE protease that cleaves PARP and is required for apoptosis in mammalian cells. These events were prevented when E1A was co-expressed with E1B 19K or BCL-2, which places these suppressors of apoptosis either at or upstream of processing of pro-CPP32.

MeSH terms

  • Adenovirus E1A Proteins / metabolism*
  • Adenovirus E1B Proteins / metabolism*
  • Adenoviruses, Human / metabolism*
  • Animals
  • Apoptosis
  • CHO Cells
  • Caspase 3
  • Caspases*
  • Cell Division
  • Cell Survival
  • Cricetinae
  • Cysteine Endopeptidases / metabolism*
  • Enzyme Precursors / metabolism*
  • Humans
  • KB Cells
  • Kinetics
  • Poly(ADP-ribose) Polymerases / metabolism*
  • Protein Processing, Post-Translational
  • Protein-Tyrosine Kinases / metabolism
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-bcl-2
  • Recombinant Proteins / metabolism
  • Time Factors
  • Transfection


  • Adenovirus E1A Proteins
  • Adenovirus E1B Proteins
  • Enzyme Precursors
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Recombinant Proteins
  • Poly(ADP-ribose) Polymerases
  • Protein-Tyrosine Kinases
  • CASP3 protein, human
  • Caspase 3
  • Caspases
  • Cysteine Endopeptidases