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The Effect of Replication Protein A Inhibition and Post-Translational Modification on ATR Kinase Signaling

Matthew R Jordan1, Greg G Oakley2, Lindsey D Mayo1

  • 1Indiana University School of Medicine.

Research Square
|August 7, 2024
PubMed

Insights

New chemical inhibitors targeting replication protein A (RPA) block ATR kinase signaling, crucial for cancer cell survival. These RPA inhibitors offer a promising strategy for developing novel anti-cancer therapeutics by disrupting DNA damage response pathways.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Cancer Therapeutics

Background:

  • The ATR kinase pathway is vital for maintaining genome integrity by responding to DNA damage.
  • Replication protein A (RPA) is essential for sensing single-stranded DNA and activating ATR signaling.
  • ATR pathway dysregulation is a hallmark of cancer, making it a therapeutic target.

Purpose of the Study:

  • To elucidate the mechanism of action of novel chemical RPA inhibitors (RPAi).
  • To investigate the role of RPA post-translational modifications (PTMs) in ATR kinase activation and RPAi sensitivity.
  • To provide insights into the anti-cancer potential of RPAi targeting the ATR pathway.

Main Methods:

  • Biochemically reconstituted ATR kinase signaling pathway.
  • Development and application of RPA-DNA binding inhibitors (RPA-DBi) and RPA protein-protein interaction inhibitors (RPA-PPIi).
  • Analysis of RPA and TopBP1 post-translational modifications (PTMs) including phosphorylation and acetylation.

Main Results:

  • Both RPA-DBi and RPA-PPIi effectively abrogate ATR-dependent phosphorylation of downstream targets.
  • RPA32 phosphorylation and TopBP1 phosphorylation stimulate ATR kinase activation.
  • RPA70 acetylation does not affect ATR kinase activation.
  • RPA PTMs impact ATR signaling but do not alter sensitivity to RPA inhibitors.

Conclusions:

  • Chemical RPA inhibitors effectively block ATR signaling by interfering with RPA function.
  • RPA PTMs modulate ATR kinase activation, offering a layer of regulation.
  • Understanding RPAi mechanisms and RPA PTMs is crucial for developing effective ATR-targeted cancer therapies.

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