Ratiometric transcriptional activation by protein degradation.

Ratiometric transcriptional activation converts protein degradation into highly sensitive gene expression signals in live cells, enabling detection of multiple protein downregulation events.

• Why it matters: Understanding and controlling cellular responses to protein abundance changes is crucial for biomedical research and therapeutic development. Synthetic circuits that translate protein degradation into transcriptional outputs could revolutionize how we monitor and manipulate cellular functions, especially for complex processes like oncogenic regulation.
• What they did: The authors designed and demonstrated principles for implementing ratiometric transcriptional activation, which involves controlling the ratio between a transcription factor and an inhibitor-fused protein of interest. They showed this approach works in single cells with orthogonal circuits and in multicellular pools, regardless of the protein downregulation mechanism, and can detect multiple events simultaneously through various outputs.
• The result: These circuits enable applications such as identifying oncogenic targets and discovering molecular glue degraders, providing a versatile platform for scalable, multiplexed detection of protein downregulation in live cells.