Chromatin remodeling and initiation of DNA replication

While much has been learned in recent years about the process of chromatin remodeling and its role in activation of transcription, relatively little h as been reported on the role of chromatin remodeling in DNA replication. Ho wever, it is well established that transcription factors and chromatin stru cture play an important role in replication origin usage. Recent work has b egun to indicate that chromatin remodeling factors are likely to play an im portant role in the regulation of replication origin usage. The results to date are most consistent with the role for chromatin remodeling factors in DNA replication as being indirect, and very similar to their role in transc ription. The current evidence suggests that transcription factors bind to a uxiliary sequences adjacent to replication origins and recruit chromatin re modeling factors to create either nucleosome-free regions or regions of spe cifically spaced nucleosomes. This results in activation of the nearby orig in, presumably by making the origin region more accessible to replication f actors. Until recently, there has been very little evidence of direct interactions between chromatin remodeling factors and the DNA replication machinery. Rec ent studies have provided data indicating that direct interactions may exis t between chromatin remodeling factors and two cellular replication factors , the Origin Recognition Complex and Proliferating Cell Nuclear Antigen. Ho wever, since these replication factors are also involved in other nuclear p rocesses, such as transcriptional silencing and DNA repair, respectively, f urther study is necessary to establish whether these direct interactions ar e also important for DNA replication.