Deficiency of XLF and PAXX prevents DNA double-strand break repair by non-homologous end joining in lymphocytes. Academic Article uri icon

Overview

abstract

  • Non-homologous end joining (NHEJ) is a major DNA double-strand break (DSB) repair pathway that functions in all phases of the cell cycle. NHEJ repairs genotoxic and physiological DSBs, such as those generated by ionizing radiation and during V(D)J recombination at antigen receptor loci, respectively. DNA end joining by NHEJ relies on the core factors Ku70, Ku80, XRCC4, and DNA Ligase IV. Additional proteins also play important roles in NHEJ. The XRCC4-like factor (XLF) participates in NHEJ through its interaction with XRCC4, and XLF deficiency in humans leads to immunodeficiency and increased sensitivity to ionizing radiation. However, XLF is dispensable for NHEJ-mediated DSB repair during V(D)J recombination in murine lymphocytes, where it may have redundant functions with other DSB repair factors. Paralog of XRCC4 and XLF (PAXX) is a recently identified NHEJ factor that has structural similarity to XRCC4 and XLF. Here we show that PAXX is also dispensable for NHEJ during V(D)J recombination and during the repair of genotoxic DSBs in lymphocytes. However, a combined deficiency of PAXX and XLF blocks NHEJ with a severity comparable to that observed in DNA Ligase IV-deficient cells. Similar to XLF, PAXX interacts with Ku through its C-terminal region, and mutations that disrupt Ku binding prevent PAXX from promoting NHEJ in XLF-deficient lymphocytes. Our findings suggest that the PAXX and XLF proteins may have redundant functions during NHEJ.

publication date

  • November 10, 2016

Research

keywords

  • B-Lymphocytes
  • DNA Breaks, Double-Stranded
  • DNA End-Joining Repair
  • DNA-Binding Proteins

Identity

PubMed Central ID

  • PMC5323033

Scopus Document Identifier

  • 85009960877

Digital Object Identifier (DOI)

  • 10.1080/15384101.2016.1253640

PubMed ID

  • 27830975

Additional Document Info

volume

  • 16

issue

  • 3