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TDP1 phosphorylation by CDK1 in mitosis promotes MUS81-dependent repair of trapped Top1-DNA covalent complexes

Srijita Paul Chowdhuri1, Benu Brata Das2

  • 1Laboratory of Molecular Biology, School of Biological Sciences, Indian Association for the Cultivation of Science, 2A & B, Raja S. C. Mullick Road, Jadavpur, Kolkata, West Bengal, 700032, India.

The EMBO Journal
|July 16, 2024
PubMed

Insights

Researchers discovered that CDK1-dependent phosphorylation of Tyrosyl-DNA phosphodiesterase 1 (TDP1) at S61 is crucial for its function during mitosis. This phosphorylation prevents DNA damage and mitotic defects by ensuring proper repair of Topoisomerase 1-DNA covalent complexes.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • Topoisomerase 1 (Top1) regulates DNA topology and is essential for cell division.
  • Tyrosyl-DNA phosphodiesterase 1 (TDP1) removes Top1-DNA covalent complexes (Top1cc), which can impede DNA replication and transcription.
  • Understanding the cell cycle regulation of DNA repair mechanisms is critical for preventing genomic instability.

Purpose of the Study:

  • To investigate the role of TDP1 phosphorylation in mitosis.
  • To elucidate the mechanism of Top1cc repair during cell division.
  • To understand how replication stress impacts DNA repair and genomic integrity.

Main Methods:

  • Identification of CDK1-dependent phosphorylation sites on TDP1 using biochemical assays.
  • Generation and analysis of a TDP1 variant (TDP1-S61A) defective for S61 phosphorylation.
  • Assessment of DNA damage, mitotic progression, and genomic instability markers in response to replication stress.

Main Results:

  • CDK1 phosphorylates TDP1 at serine 61 (S61) during mitosis.
  • TDP1-S61A variant accumulates on mitotic chromosomes, causing DNA damage and mitotic defects.
  • MUS81-dependent repair pathway is involved in resolving Top1cc during mitosis.
  • Replication stress with TDP1-S61A leads to increased chromatid breaks, anaphase bridges, and micronuclei formation.

Conclusions:

  • Mitotic phosphorylation of TDP1 at S61 by CDK1 is essential for efficient repair of Top1cc.
  • Dysregulation of TDP1 phosphorylation contributes to genomic instability under replication stress.
  • This study reveals a novel cell cycle-dependent mechanism for maintaining genome integrity.
Keywords:
CDK1MUS81MiDASTDP1Topoisomerase 1

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