Transcription Block Survival (TBS) is a high-throughput, intracellular peptide screening platform to derive functional transcription factor antagonists. It has been utilised to target the transcriptional regulator exemplar cJun which interacts with TRE site on DNA and is upregulated or overexpressed in a range of diseases. PPI-DNA interactions are compelling yet underexplored targets and harbour significant promise in drug development.
During TBS, TRE sites are introduced into the coding region of the essential gene dihydrofolate reductase (TRE-DHFR). Introduction of cJun into cells containing TRE-DHFR causes RNA polymerase to be sterically hindered producing a transcriptional block, leading to cell death. In vivo library screening of ~130,000 peptides identified a sequence that both binds cJun and antagonises function as demonstrated by restored cell growth due to TRE-DHFR transcription and subsequent in vitro hit validation. TBS is an entirely tag-free genotype-to-phenotype approach, selecting desirable attributes such as high solubility, target specificity and low toxicity within a complex cellular environment. It facilitates rapid library screening to accelerate the identification of therapeutically valuable sequences.
Brennan, A., Leech J., Kad N.M., and Mason J.M. An Approach to Derive Functional Peptide Inhibitors of Transcription Factor Activity JACS Au. 2, 4, 996-1006 (2022).
Brennan A., Leech J.T., Kad N.M., and Mason J.M. The Effect of Helix-Inducing Constraints and Downsizing Upon a Transcription Block Survival Derived Functional cJun Antagonist. Cell Rep Phys Sci (In Press).