Js. Mymryk et St. Bayley, INDUCTION OF GENE-EXPRESSION BY EXON-2 OF THE MAJOR E1A PROTEINS OF ADENOVIRUS TYPE-5, Journal of virology, 67(12), 1993, pp. 6922-6928
We have constructed an adenovirus type 5 (Ad5) E1A mutant, dl1119/520,
that produces essentially only exon 2 of the major E1A proteins. In i
nfected primary baby rat kidney cells, this mutant induced expression
of the E1B 55-kDa protein, and in infected human KB cells, it induced
expression of this protein, the E2A 72-kDa protein, and hexon. In KB c
ells, this mutant grew substantially better than Ad5 dl312, which lack
s EIA, and as well as Ad5 dl520, an E1A mutant producing only the 243-
residue protein. These results suggest that exon 2 of E1A proteins on
its own was able to activate gene expression. We also constructed muta
nts of dl1119/520, containing small deletions in regions of exon 2 tha
t others found to be associated with effects on the properties of E1A
transformants. None of these deletions destroyed gene activation compl
etely, indicating that there may be some redundancy among sequences in
exon 2 for inducing gene expression. The two deletions that decreased
induction the most, residues 224 to 238 and 255 to 270, were in regio
ns reported to be associated with the expression of a metalloprotease
and with enhanced transformation, suggesting that exon 2 may regulate
expression of genes governing cell growth. It is remarkable that all s
ections of E1A proteins, exon 1, the unique region, and exon 2, have n
ow been found to affect gene expression.