When DNA becomes its own enemy: How DNA impacts replication dynamics, fidelity, and integrity

Every dividing cell in our body copies three billion DNA letters with near-perfect accuracy, but certain repetitive sequences cause the copying machinery to stall and make mistakes. This matters because these problematic sequences—which can fold into unusual shapes like hairpins or four-stranded structures—are known hotspots for mutations and chromosome rearrangements in many cancers. Yet the same sequences also serve essential regulatory roles in healthy cells, meaning cells must have ways to preserve them. The fundamental gap is that no one understands exactly how the copying machinery responds to these challenging templates, or why it sometimes fails. The researchers will use purified human replication proteins and novel cellular models to watch, in real time, what happens when the copying machinery encounters these structures. They will measure how the DNA template itself alters copying speed, accuracy, and whether the genome remains intact. This is fundamental science. It will not produce a diagnostic test or drug tomorrow. But understanding how replication stress arises from the DNA itself—rather than from external damage—could eventually explain why certain genomic regions are fragile in cancer, and why some repetitive sequences are preserved while others are not. Past work on replication machinery has already underpinned cancer therapies that exploit replication vulnerabilities.