biostudies-literatureKhan ANCI NIH HHSU.S. Department of Health & Human Services | National Institutes of Health (NIH)NIGMS NIH HHS1683https://www.ebi.ac.uk/biostudies/studies/S-EPMC12647206biostudies-literatureUnknown8(1)ATM is an apical kinase that governs cellular responses to DNA replication-associated double strand breaks (DSBs) accumulated by the topoisomerase inhibitor anti-cancer therapy. Here we identify that TIPIN, a major constituent of the fork protection complex in the replisome, plays a key role in coordinating ATM signaling tied to DNA replication stress. We demonstrate that TIPIN amplifies ATM signaling to promote DNA end resection and homology-directed repair. TIPIN itself is phosphorylated by ATM, which is required for the recruitment of MDC1 to stalled forks to promote ATM-dependent NF-κB activation. Inhibition of the NF-κB pathway by MDC1 depletion impairs upregulation of anti-apoptotic regulator c-FLIP, thus potentiating caspase-8 activation and cytotoxicity of topoisomerase inhibition.Communications biologyTIPIN coordinates ATM-dependent checkpoint and NF-κB signaling to counteract DNA replication damage from topoisomerase inhibition.PMC12647206R01CA285515R01 CA285515R01GM144399R01 GM144399Patel JALo NKim HLim JFKhan AHaley JfalseTIPIN coordinates ATM-dependent checkpoint and NF-κB signaling to counteract DNA replication damage from topoisomerase inhibition.ATM is an apical kinase that governs cellular responses to DNA replication-associated double strand breaks (DSBs) accumulated by the topoisomerase inhibitor anti-cancer therapy. Here we identify that TIPIN, a major constituent of the fork protection complex in the replisome, plays a key role in coordinating ATM signaling tied to DNA replication stress. We demonstrate that TIPIN amplifies ATM signaling to promote DNA end resection and homology-directed repair. TIPIN itself is phosphorylated by ATM, which is required for the recruitment of MDC1 to stalled forks to promote ATM-dependent NF-κB activation. Inhibition of the NF-κB pathway by MDC1 depletion impairs upregulation of anti-apoptotic regulator c-FLIP, thus potentiating caspase-8 activation and cytotoxicity of topoisomerase inhibition.2025-01-01T00:00:00Z2025 Nov2026-06-05T16:43:11.387Z2026-05-18T03:13:08.25ZS-EPMC126472064129115110.1038/s42003-025-09084-7