Human HLTF participates in the lesion-bypass mechanism through the fork reversal structure, known as template switching of post-replication repair. However, the mechanism by which HLTF promotes the replication progression and fork stability of damaged forks remains unclear. Here, we identify a novel protein–protein interaction between HLTF and PARP1. The depletion of HLTF and PARP1 increases chromosome breaks, further reduces the length of replication tracks, and concomitantly increases the number of stalled forks after methyl methanesulfonate treatment according to a DNA fiber analysis. The progression of replication also depends on BARD1 in the presence of MMS treatment. By combining 5-ethynyl-2′-deoxyuridine with a proximity ligation assay, we revealed that the HLTF, PARP1, and BRCA1/BARD1/RAD51 proteins were initially recruited to damaged forks. However, prolonged stalling of damaged forks results in fork collapse. HLTF and PCNA dissociate from the collapsed forks, with increased accumulation of PARP1 and BRCA1/BARD1/RAD51 at the collapsed forks. Our results reveal that HLTF together with PARP1 and BARD1 participates in the stabilization of damaged forks, and the PARP1–BARD1 interaction is further involved in the repair of collapse forks.

人类HLTF通过前叉逆转结构参与了病变旁路机制，即复制后修复的模板切换。但是，HLTF促进受损叉的复制进程和叉稳定性的机制仍不清楚。在这里，我们确定了HLTF和PARP1之间新型的蛋白质相互作用。根据DNA纤维分析，HLTF和PARP1的消耗会增加染色体断裂，进一步缩短复制轨道的长度，并随之增加甲烷磺酸甲酯处理后停滞的叉子数量。在进行MMS治疗时，复制的进程还取决于BARD1。通过将5-乙炔基-2'-脱氧尿苷与邻近连接分析相结合，我们发现HLTF，PARP1，和BRCA1 / BARD1 / RAD51蛋白最初被募集到受损的叉子上。但是，损坏的货叉长时间失速会导致货叉倒塌。HLTF和PCNA与折叠叉分离，并且在折叠叉处PARP1和BRCA1 / BARD1 / RAD51的积累增加。我们的结果表明，HLTF与PARP1和BARD1一起参与了损坏叉的稳定工作，而PARP1–BARD1的相互作用进一步参与了折叠叉的修复。