The Brn-3a transcription factor stimulates the expression of the anti-apopt
otic Bcl-2 and Bcl-x proteins and protects neuronal cells from apoptosis. H
ere we show that a minimal Bcl-x promoter is activated by Brn-3a and that t
his stimulation is prevented by the pro-apoptotic p53 protein. Both these e
ffects are mediated via Bcl-x promoter sequences, which are indistinguishab
le from those required for minimal basal promoter activity. A newly describ
ed upstream Bcl-x promoter is also activated by Brn-3a with this activation
being prevented by p53. Hence, Brn-3a-mediated activation of two distinct
Bcl-x promoters and of the Bcl-2 promoter is blocked by p53 whereas this is
not observed for Brn-3a activated promoters derived from genes not involve
d in inhibiting apoptosis. p53 therefore appears to specifically target the
activation by Brn-3a of promoters derived from genes with an anti-apoptoti
c effect and this may be involved in the pro-apoptotic activity of p53.