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Publications

Journal Article Ppublish

PubMed: 40103231 DOI: 10.1093/nar/gkaf168

APE1 condensation in nucleoli of non-cancer cells depends on rRNA transcription and forming G-quadruplex RNA structures.

Nucleic Acids Res 53(5)

Authors: Giuseppe Dall'Agnese, Nancy M Hannett, Kalon J Overholt, Jesse M Platt, Jonathan E Henninger, Asier Marcos-Vidal, Zahraa Othman, Gilmar Salgado, Giulia Antoniali, Gianluca Tell

Affiliations

  • Laboratory of Molecular Biology and DNA Repair, Department of Medicine, University of Udine, 33100 Udine, Italy.
  • Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, United States.
  • Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
  • Division of Gastroenterology, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, United States.
  • W.M. Keck Imaging Facility, Whitehead Institute for Biomedical Research, Cambridge, MA 02142, United States.
  • ARNA Laboratory-Inserm U1212-CNRS UMR 5320, Bordeaux Biologie Santé-Université de Bordeaux, 146 Rue Léo Saignant, 33076 Bordeaux, France.

Abstract

APE1 [apurinic/apyrimidinic (AP) endodeoxyribonuclease 1] is the main endonuclease of the base excision repair pathway acting on abasic (AP) sites in DNA. APE1 is an abundant nuclear protein, and improper expression or localization of this factor could lead to the accumulation of toxic DNA intermediates. Altered APE1 subcellular distribution and expression are associated with cancer development, suggesting the importance of a fine-tuning mechanism for APE1 activities. Recent works highlighted the presence of APE1 within nucleoli of cancer cells and the ability of APE1 to form biomolecular condensate. However, whether secondary structures of ribosomal RNA (rRNA) influence the nucleolar localization of APE1 remains poorly understood. Since protein overexpression can result in artificial nucleolar accumulation, it is imperative to have appropriate cellular models to study APE1 trafficking under physiological conditions. To address this issue, we generated a murine embryonic stem cell line expressing endogenous fluorescent-tagged APE1. Live-cell imaging demonstrates that APE1 nucleolar accumulation requires active rRNA transcription and is modulated by different genotoxicants. In vitro experiments showed that APE1 condensate formation depends on RNA-forming G-quadruplex structures and relies on critical lysine residues. This study sheds light on the mechanisms underlying APE1 trafficking to the nucleolus and the formation of RNA-dependent APE1 nucleolar condensates.

MeSH

Cells, Genes, Rrna, Neoplasms, Nucleic Acids, Rna, Excision Repair