Distinct p53 isoforms code for opposing transcriptional outcomes

p53 genes across species are broadly conserved and encode well-characterized transcriptional activators that specify inductive stress-responses. In some contexts, p53 can also down-regulate genes but the mechanisms involved are not understood and assumed to be indirect. Here we integrate synthetic and native cis-regulatory elements with an imaging platform to examine features of p53-mediated gene control in vivo. Cut&Run for p53 in Drosophila stage L3 salivary glands. STI150 is a GFP reporter construct in which GFP expression is under control of the p53 DNA binding motif upstream of the reaper gene (homozygous) mCh is a fly containing a p53 genomic rescue in with p53 has been tagged with mCherry (homozygous) K1 is a p53 knockout drosophila allele (homozygous)