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J. Virol., 09 1996, 6207-6215, Vol 70, No. 9
RC Marcellus, JG Teodoro, T Wu, DE Brough, G Ketner, GC Shore and PE Branton
In the absence of E1B, the 289- and 243-residue E1A products of human
adenovirus type 5 induce p53-dependent apoptosis. However, our group has
shown recently that the 289-residue E1A protein is also able to induce
apoptosis by a p53-independent mechanism (J. G. Teodoro, G. C. Shore, and
P. E. Branton, Oncogene 11:467-474, 1995). Preliminary results suggested
that p53-independent cell death required expression of one or more
additional adenovirus early gene products. Here we show that both the E1B
19-kDa protein and cellular Bcl-2 inhibit or significantly delay
p53-independent apoptosis. Neither early region E2 or E3 appeared to be
necessary for such cell death. Analysis of a series of E1A mutants
indicated that mutations in the transactivation domain and other regions of
E1A correlated with E1A-mediated transactivation of E4 gene expression.
Furthermore, p53-deficient human SAOS-2 cells infected with a mutant which
expresses E1B but none of the E4 gene products remained viable for
considerably longer times than those infected with wild-type adenovirus
type 5. In addition, an adenovirus vector lacking both E1 and E4 was unable
to induce DNA degradation and cell killing in E1A-expressing cell lines.
These data showed that an E4 product is essential for E1A-induced
p53-independent apoptosis.
Copyright © 1996, American Society for Microbiology
Adenovirus type 5 early region 4 is responsible for E1A-induced p53- independent apoptosis
Department of Biochemistry McGill University, Montreal, Quebec, Canada.
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