The ORC ubiquitin ligase OBI1 promotes DNA replication origin firing.

DNA replication initiation is a two-step process. During the G1-phase of the cell cycle, the ORC complex, CDC6, CDT1, and MCM2-7 assemble at replication origins, forming pre-replicative complexes (pre-RCs). In S-phase, kinase activities allow fork establishment through (CDC45/MCM2-7/GINS) CMG-complex formation.

Author Correction: RNAs coordinate nuclear envelope assembly and DNA replication through ELYS recruitment to chromatin.

In the original version of this Article, the affiliation details for Antoine Aze, Michalis Fragkos, Stéphane Bocquet, Julien Cau and Marcel Méchali incorrectly omitted 'CNRS and the University of Montpellier'. This has now been corrected in both the PDF and HTML versions of the Article.

RNAs coordinate nuclear envelope assembly and DNA replication through ELYS recruitment to chromatin.

Upon fertilisation, the sperm pronucleus acquires the competence to replicate the genome through a cascade of events that link chromatin remodelling to nuclear envelope formation. The factors involved have been partially identified and are poorly characterised. Here, using Xenopus laevis egg extracts we show that RNAs are required for proper nuclear envelope assembly following sperm DNA decondensation.

Synergic reprogramming of mammalian cells by combined exposure to mitotic Xenopus egg extracts and transcription factors.

Transfer of somatic cell nuclei to enucleated eggs and ectopic expression of specific transcription factors are two different reprogramming strategies used to generate pluripotent cells from differentiated cells. However, these methods are poorly efficient, and other unknown factors might be required to increase their success rate. Here we show that Xenopus egg extracts at the metaphase stage (M phase) have a strong reprogramming activity on mouse embryonic fibroblasts (MEFs).

The regulation of competence to replicate in meiosis by Cdc6 is conserved during evolution.

DNA replication licensing is an important step in the cell cycle at which cells become competent for DNA replication. When the cell cycle is arrested for long periods of time, this competence is lost. This is the case for somatic cells arrested in G0 or vertebrate oocytes arrested in G2.

Expression of ISWI and its binding to chromatin during the cell cycle and early development.

We have characterized Xenopus ISWI, a catalytic subunit of a family of chromatin-remodeling complexes. We show that ISWI is expressed constitutively during development but poorly expressed in adult tissues except oocytes which contain a large store of maternal protein. We further analyzed its localization both in vivo and in vitro in Xenopus cell cycle extracts and identified that ISWI binds to chromatin at the G1-S period.

Competence to replicate in the unfertilized egg is conferred by Cdc6 during meiotic maturation.

Meiotic maturation, the final step of oogenesis, is a crucial stage of development in which an immature oocyte becomes a fertilizable egg. In Xenopus, the ability to replicate DNA is acquired during maturation at breakdown of the nuclear envelope by translation of a DNA synthesis inducer that is not present in the oocyte. Here we identify Cdc6, which is essential for recruiting the minichromosome maintenance (MCM) helicase to the pre-replication complex, as this inducer of DNA synthesis.