Modulation of Phosphoprotein Activity by Phosphorylation Targeting Chimeras (PhosTACs)

ACS Chem Biol. 2021 Dec 17;16(12):2808-2815. doi: 10.1021/acschembio.1c00693. Epub 2021 Nov 15.

Abstract

Protein phosphorylation, which regulates many critical aspects of cell biology, is dynamically governed by kinases and phosphatases. Many diseases are associated with dysregulated hyperphosphorylation of critical proteins, such as retinoblastoma protein in cancer. Although kinase inhibitors have been widely applied in the clinic, growing evidence of off-target effects and increasing drug resistance prompts the need to develop a new generation of drugs. Here, we propose a proof-of-concept study of phosphorylation targeting chimeras (PhosTACs). Similar to PROTACs in their ability to induce ternary complexes, PhosTACs focus on recruiting a Ser/Thr phosphatase to a phosphosubstrate to mediate its dephosphorylation. However, distinct from PROTACs, PhosTACs can uniquely provide target gain-of-function opportunities to manipulate protein activity. In this study, we applied a chemical biology approach to evaluate the feasibility of PhosTACs by recruiting the scaffold and catalytic subunits of the PP2A holoenzyme to protein substrates such as PDCD4 and FOXO3a for targeted protein dephosphorylation. For FOXO3a, this dephosphorylation resulted in the transcriptional activation of a FOXO3a-responsive reporter gene.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Apoptosis Regulatory Proteins
  • Catalytic Domain
  • Chimera / metabolism*
  • Enzyme Activation
  • Forkhead Box Protein O3
  • HeLa Cells
  • Holoenzymes / chemistry
  • Humans
  • Phosphoproteins / chemistry*
  • Phosphorylation
  • Protein Tyrosine Phosphatases / metabolism*
  • RNA-Binding Proteins
  • Structure-Activity Relationship

Substances

  • Apoptosis Regulatory Proteins
  • Forkhead Box Protein O3
  • Holoenzymes
  • PDCD4 protein, human
  • Phosphoproteins
  • RNA-Binding Proteins
  • Protein Tyrosine Phosphatases