Keeping forks in the loop: how chromatin architecture shields stalled replication forks

In a recent study published in Nature , Taneja et al. 1 find that replication stress triggers the formation of transient, CTCF-anchored, G9a/H3K9me3-coated chromatin loops that enclose stalled replication forks and protect nascent DNA from nucleolytic degradation. These findings define an architectural layer of fork protection that functions independently of the well-known BRCA2-dependent replication fork protection activity.