Development of BromoTag: A "Bump-and-Hole"-PROTAC System to Induce Potent, Rapid, and Selective Degradation of Tagged Target Proteins

J Med Chem. 2021 Oct 28;64(20):15477-15502. doi: 10.1021/acs.jmedchem.1c01532. Epub 2021 Oct 15.

Abstract

Small-molecule-induced protein depletion technologies, also called inducible degrons, allow degradation of genetically engineered target proteins within cells and animals. Here, we design and develop the BromoTag, a new inducible degron system comprising a Brd4 bromodomain L387A variant as a degron tag that allows direct recruitment by heterobifunctional bumped proteolysis targeting chimeras (PROTACs) to hijack the VHL E3 ligase. We describe extensive optimization and structure-activity relationships of our bump-and-hole-PROTACs using a CRISPR knock-in cell line expressing model target BromoTag-Brd2 at endogenous levels. Collectively, our cellular and mechanistic data qualifies bumped PROTAC AGB1 as a potent, fast, and selective degrader of BromoTagged proteins, with a favorable pharmacokinetic profile in mice. The BromoTag adds to the arsenal of chemical genetic degradation tools allowing us to manipulate protein levels to interrogate the biological function and therapeutic potential in cells and in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / antagonists & inhibitors*
  • Cell Cycle Proteins / metabolism
  • Dose-Response Relationship, Drug
  • Drug Development*
  • HEK293 Cells
  • Humans
  • Molecular Structure
  • Proteolysis / drug effects*
  • Structure-Activity Relationship
  • Transcription Factors / antagonists & inhibitors*
  • Transcription Factors / metabolism

Substances

  • BRD4 protein, human
  • Cell Cycle Proteins
  • Transcription Factors