Figure 2. Loss of senataxin severely impairs NHEJ-mediated RAG DSB repair in DNA-PKcs-inhibited abl pre-B cells during V(D)J recombination.

(A, B) The schematic of the retroviral V(D)J recombination substrates pMX-DEL^CJ (A) and pMX-DEL^SJ (B). The open and filled triangles represent the RSSs. The red bar indicates the probe (hCD4 cDNA) for Southern blot. The Es denote the EcoRV restriction sequences. The retroviral LTRs, CEs and SEs upon RAG cleavage as well as CJs and SJs after NHEJ-mediated repair are indicated. (C, D) Southern blot analysis of genomic DNA from WT and three clonal Setx^−/− abl pre-B cell lines with pMX-DEL^CJ (C) or pMX-DEL^SJ (D) treated with imatinib (imat.) in the presence or absence of the DNA-PKcs kinase inhibitor NU7441 for the indicated times. The genomic DNA samples were digested with EcoRV and hybridized to the hCD4 probe. The restriction fragments corresponding to unrearranged reporters (UR), repaired CJs or SJs and unrepaired CEs or SEs are indicated. R. CE and R. SE indicate resected CE and SE restriction fragments. (E) Southern blot analysis of EcoRV digested genomic DNA from cells described in (C) and (D) treated with imatinib in the presence or absence of the ATM kinase inhibitor KU55933 for the indicated times.