Modulation of Phosphoprotein Activity by Phosphorylation Targeting Chimeras (PhosTACs)

Area of Science:

• Biochemistry
• Molecular Biology
• Chemical Biology

Background:

• Protein phosphorylation is crucial for cell biology, regulated by kinases and phosphatases.
• Dysregulated phosphorylation, like retinoblastoma protein hyperphosphorylation in cancer, is linked to diseases.
• Existing kinase inhibitors face challenges like off-target effects and drug resistance.

Purpose of the Study:

• To introduce and evaluate the proof-of-concept for phosphorylation targeting chimeras (PhosTACs).
• To explore PhosTACs as a novel therapeutic strategy for diseases involving protein hyperphosphorylation.
• To demonstrate PhosTACs' ability to recruit phosphatases for targeted protein dephosphorylation.

Main Methods:

• Utilized a chemical biology approach to design and test PhosTACs.
• Recruited PP2A holoenzyme (scaffold and catalytic subunits) to protein substrates.
• Assessed PhosTAC efficacy on protein substrates like PDCD4 and FOXO3a.

Main Results:

• Successfully demonstrated targeted protein dephosphorylation using PhosTACs.
• PhosTACs recruited PP2A to PDCD4 and FOXO3a substrates.
• Dephosphorylation of FOXO3a by PhosTACs led to transcriptional activation of a reporter gene.

Conclusions:

• PhosTACs represent a viable new modality for targeted protein dephosphorylation.
• This technology offers potential gain-of-function opportunities by manipulating protein activity.
• PhosTACs provide a promising alternative to kinase inhibitors for treating diseases associated with aberrant phosphorylation.