DNA replication occurs at the nuclear matrix

Chromatin in eukaryotic cells is partitioned into loop-domains by binding of MARs to the nuclear matrix. It is increasingly accepted that the replication event is attached to the nuclear matrix. In this study, chicken myelomonocytic HD11 cells were synchronized at the G1/S phase boundary, and after release into the S phase, were immediately pulse-labelled with 5-bromodeoxyuridine (BrdU). The chromatin was then fractionated into the nuclear matrix and a solubilized fraction to determine the partitioning of BrdU in newly replicated DNA. Me found that in early S phase-synchronized cells newly replicated DNA was highly enriched in the nuclear matrix. This result indicates that origins of DNA replication in eukaryotic cells are attached at the nuclear matrix.