NS and PML-IV promote telomeric recruitment of RAD51 under the telomere damage condition. (A) Telomeric recruitment of RAD51 was determined by confocal colocalization of TRF1-GFP and endogenous RAD51 foci. The number of telomere-associated RAD51 foci is increased by TRF2-DN transfection (from 0.7 to 2.7 per cell). Knockdown of NS or PML-IV significantly reduces the telomeric recruitment of RAD51 induced by TRF2-DN transfection (1.7 and 1.5 per cell, respectively). Both NS and PML-IV knockdown increase the number of nontelomeric RAD51 foci. Asterisks represent P values (see Fig. 1). (B) Overexpression of NS or PML-IV increases the number of telomere-associated RAD51 foci. Non-telomeric RAD51 foci are decreased by NS overexpression but unchanged by PML-IV overexpression. (C) CoIP confirms that PML-IV mediates the interaction between RAD51 and TRF1-So (lanes 1–4) and that this interaction is enhanced by TRF2-DN–induced telomere damage (lane 5). By comparison, PML-IV shows a much weaker effect in mediating the binding between RAD51 and TRF1 (lane 6). (D) PML-IV binds RAD51 directly and independently of telomere damage.