2. Academic Validation
  3. DNA and RNA Cleavage Complexes and Repair Pathway for TOP3B RNA- and DNA-Protein Crosslinks

DNA and RNA Cleavage Complexes and Repair Pathway for TOP3B RNA- and DNA-Protein Crosslinks

  • Cell Rep. 2020 Dec 29;33(13):108569. doi: 10.1016/j.celrep.2020.108569.
Sourav Saha 1,  Yilun Sun 1,  Shar-Yin Naomi Huang 1,  Simone Andrea Baechler 1,  Lorinc Sandor Pongor 1,  Keli Agama 1,  Ukhyun Jo 1,  Hongliang Zhang 1,  Yuk-Ching Tse-Dinh 2,  Yves Pommier 3
Affiliations

Affiliations

  • 1 Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
  • 2 Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA; Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
  • 3 Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA. Electronic address: pommier@nih.gov.
PMID: 33378676 DOI: 10.1016/j.celrep.2020.108569
Abstract

The present study demonstrates that Topoisomerase 3B (TOP3B) forms both RNA and DNA cleavage complexes (TOP3Bccs) in vivo and reveals a pathway for repairing TOP3Bccs. For inducing and detecting cellular TOP3Bccs, we engineer a "self-trapping" mutant of TOP3B (R338W-TOP3B). Transfection with R338W-TOP3B induces R-loops, genomic damage, and growth defect, which highlights the importance of TOP3Bcc repair mechanisms. To determine how cells repair TOP3Bccs, we deplete tyrosyl-DNA phosphodiesterases (TDP1 and TDP2). TDP2-deficient cells show elevated TOP3Bccs both in DNA and RNA. Conversely, overexpression of TDP2 lowers cellular TOP3Bccs. Using recombinant human TDP2, we demonstrate that TDP2 can process both denatured and proteolyzed TOP3Bccs. We also show that cellular TOP3Bccs are ubiquitinated by the E3 Ligase TRIM41 before undergoing proteasomal processing and excision by TDP2.

Keywords

DNA repair; TDP2; TRIM41; topoisomerase; ubiquitin-proteasome.

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