Calcium influx-mediated translocation of m-calpain induces Ku80 cleavage and enhances the Ku80-related DNA repair pathway

Kyung Hye Baek, Han Vit Yu, Eosu Kim, Younghwa Na, Youngjoo Kwon

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Proteomic analysis of ionomycin-treated and untreated mammary epithelial MCF10A cells elucidated differences in Ku80 cleavage. Ku80, a subunit of the Ku protein complex, is an initiator of the non-homologous, end-joining (NHEJ), double-strand breaks (DSBs) repair pathway. The nuclear Ku80 was cleaved in a calcium concentration-dependent manner by m-calpain but not by m-calpain. The cleavage of nuclear Ku80 at its β/χ domain was validated by Western blotting analysis using flag-tagged expression vectors of truncated versions of Ku80 and a flag antibody and was confirmed in m-calpain knock-down cells and in vitro cell-free evaluation with recombinant proteins of calpains, Ku70, and Ku80. In addition, the cleaved Ku80 still formed a Ku heterodimer and promoted DNA DSB repair activity. Taken together, these findings indicate that translocated m-calpain enhances the NHEJ pathway through the cleavage of Ku80. Based on the present study, m-calpain in DNA repair pathways might be a novel anticancer drug target, or its mechanism might be a possible route for resistance acquisition of DNA damage-inducing chemotherapeutics.

Original languageEnglish
Pages (from-to)30831-30844
Number of pages14
JournalOncotarget
Volume7
Issue number21
DOIs
StatePublished - 24 May 2016

Keywords

  • Adriamycin
  • DNA damage
  • Ku80-related DNA repair
  • m-calpain

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