Chromatin loops protect replication forks during stress

Replication stress triggers the formation of protective chromatin loops around stalled replication forks. These loops shield the forks from degradation, preserving genome integrity. The loops are stabilized by CTCF and heterochromatin, forming a protective scaffold. Loss of this structure leads to nascent-strand degradation. This mechanism is crucial even in BRCA2-deficient cells, where it safeguards replication initiation zones and prevents mutations.