PMC:4829102 / 7883-9322 JSONTXT

{"project":"2_test","denotations":[{"id":"26807646-12169690-73828172","span":{"begin":197,"end":199},"obj":"12169690"},{"id":"26807646-12169690-73828172","span":{"begin":197,"end":199},"obj":"12169690"},{"id":"26807646-12912992-73828173","span":{"begin":201,"end":203},"obj":"12912992"},{"id":"26807646-12912992-73828173","span":{"begin":201,"end":203},"obj":"12912992"},{"id":"26807646-7634335-73828174","span":{"begin":487,"end":489},"obj":"7634335"},{"id":"26807646-7634335-73828174","span":{"begin":487,"end":489},"obj":"7634335"},{"id":"26807646-8929543-73828174","span":{"begin":487,"end":489},"obj":"8929543"},{"id":"26807646-8929543-73828174","span":{"begin":487,"end":489},"obj":"8929543"},{"id":"26807646-18438770-73828174","span":{"begin":487,"end":489},"obj":"18438770"},{"id":"26807646-18438770-73828174","span":{"begin":487,"end":489},"obj":"18438770"},{"id":"26807646-11751629-73828175","span":{"begin":674,"end":676},"obj":"11751629"},{"id":"26807646-11751629-73828175","span":{"begin":674,"end":676},"obj":"11751629"},{"id":"26807646-16912188-73828176","span":{"begin":996,"end":998},"obj":"16912188"},{"id":"26807646-16912188-73828176","span":{"begin":996,"end":998},"obj":"16912188"}],"text":"EXD2 promotes homologous recombination and suppresses genome instability\nIn vivo, RPA is required for RAD51 focus formation and in vitro it has been shown to promote RAD51-mediated strand exchange 28, 29. Consistent with this, treatment of U2OS cells with IR generated large numbers of RAD51 foci (Fig. 3a and b). In contrast, EXD2 depletion significantly impaired RAD51 focus formation (Fig. 3a and b). RAD51-ssDNA nucleoprotein filament formation is a crucial step in DSB repair by HR 30-32. To examine if EXD2 is also required for efficient HR we used a U2OS cell line carrying an integrated homologous recombination reporter transgene and an I-SceI recognition sequence 33. Transient expression of I-SceI endonuclease generates a DSB that, when repaired by HR, restores the expression of a functional GFP protein. We found that depletion of EXD2 significantly decreased the frequency of homologous recombination (Fig. 3c). Cells defective in HR are intrinsically sensitive to PARP inhibitors 34. Accordingly, EXD2-depletion sensitised cells to the PARP inhibitor olaparib (Fig. 3d). Failure to efficiently repair damaged DNA is associated with chromosomal instability and in line with this, we found a significantly greater number of chromosomal aberrations in EXD2-depleted U2OS cells as compared to the WT control (Fig. 3e). Taken together this data supports a role of EXD2 in promoting homologous recombination and genome stability."}