A Method to Regulate Protein Function in Living Cells Using Small Molecules

Stanford researchers have developed a general system to regulate the activities of specific proteins in mammalian cells using cell-permeable, synthetic molecules. By manipulating protein activity (rather than using traditional perturbations of DNA and its expression), this method allows the study of essential genes as well as processes that occur on a fast time scale.

The technique relies on an engineered binding domain that degrades quickly in the absence of its small-molecule ligand. When this unstable domain is linked to proteins of interest, the resulting fusion proteins are also degraded without the protection of the ligand. This feature allows the activity of the fused protein to be specifically regulated with precise temporal control and excellent dose-dependent tunability of protein levels. The rapid, reversible, tunable system could be used analyze proteins for drug discovery and basic research or as a protein activation switch in cell therapy.

Stage of Development

• In vitro validation of system in multiple mammalian cell types
• Ligand response demonstrated in dozens of diverse target proteins
• Ligand-dependent stability shown to function in vivo when expressed in mice
• The inventors have developed:
  • new domains that are optimized for membrane-bound proteins such as GPCRs
  • the current system in living mice; testing underway in humans
  • several versions of this system to allow simultaneous ligand-mediated regulation of two different proteins.