Abstract：
Persistent DNA-protein crosslinks formed by human topoisomerase IIIα (TOP3A-DPCs) interfere with DNA metabolism and lead to genome damage and cell death. Recently, we demonstrated that such abortive TOP3A-DPCs are ubiquitylated and proteolyzed by Spartan (SPRTN). Here, we identify transient poly(ADP-ribosylation) (PARylation) in addition to ubiquitylation as a signaling mechanism for TOP3A-DPC repair and provide evidence that poly(ADP-ribose) polymerase 1 (PARP1) drives the repair of TOP3A-DPCs by recruiting flap endonuclease 1 (FEN1) to the TOP3A-DPCs. We find that blocking PARylation attenuates the interaction of FEN1 and TOP3A and that TOP3A-DPCs accumulate in cells with compromised PARP1 activity and in FEN1-deficient cells. We also show that PARP1 suppresses TOP3A-DPC ubiquitylation and that inhibiting the ubiquitin-activating enzyme E1 (UBE1) increases TOP3A-DPCs, consistent with ubiquitylation serving as a signaling mechanism for TOP3A-DPC repair mediated by SPRTN and TDP2. We propose that two concerted pathways repair TOP3A-DPCs: PARylation-driven FEN1 excision and ubiquitylation-driven SPRTN-TDP2 excision.
摘要：
由人拓扑异构酶IIIα（TOP3A-DPC）形成的持续DNA-蛋白质交联干扰DNA代谢并导致基因组损伤和细胞死亡。最近,我们证明了这种失败的TOP3A-DPC被Spartan（SPRTN）泛素化和蛋白水解。这里,我们确定了除泛素化之外的瞬时聚(ADP-核糖基化)(PAR化)作为TOP3A-DPC修复的信号机制,并提供了聚(ADP-核糖)聚合酶1(PARP1)通过向TOP3A-DPC募集皮瓣核酸内切酶1(FEN1)来驱动TOP3A-DPC修复的证据.我们发现阻断PARylation减弱了FEN1和TOP3A的相互作用，并且TOP3A-DPC在PARP1活性受损的细胞和FEN1缺陷细胞中积累。我们还显示PARP1抑制TOP3A-DPC泛素化，抑制泛素激活酶E1（UBE1）增加TOP3A-DPC，与泛素化作为SPRTN和TDP2介导的TOP3A-DPC修复的信号机制一致。我们建议两种协同途径修复TOP3A-DPC：PARylation驱动的FEN1切除和泛素化驱动的SPRTN-TDP2切除。
