A non-transcriptional function of Yap orchestrates the DNA replication program

In multicellular eukaryotic organisms, the initiation of DNA replication occurs asynchronously throughout S-phase according to a regulated replication timing program. Here, using Xenopus egg extracts, we showed that Yap (Yes-associated protein 1), a downstream effector of the Hippo signaling pathway, is required for the control of DNA replication dynamics. We found that Yap is recruited to chromatin at the start of DNA replication and that Yap depletion accelerates DNA replication dynamics by increasing the number of activated replication origins. Furthermore, we identified Rif1, a major regulator of the DNA replication timing program, as a novel Yap binding protein. In Xenopus embryos, using a Trim-Away approach during cleavage stages devoid of transcription, we found that both Yap and Rif1 depletion trigger an acceleration of cell divisions, suggesting a shorter S-phase by alterations of the replication program. Finally, our data show that Rif1 knockdown leads to defects in the partitioning of early versus late replication foci in retinal stem cells, as we previously showed for Yap. Altogether, our findings unveil a non-transcriptional role for Yap in regulating replication dynamics. We propose that Yap and Rif1 function as breaks to control the DNA replication program in early embryos and post-embryonic stem cells. HighlightsO_LIYap is recruited to chromatin during DNA replication dependent on pre-replicative complex assembly. C_LIO_LIYap controls DNA replication dynamics by limiting origin firing. C_LIO_LIThe replication timing regulatory factor 1, Rif1, is a novel Yap binding-partner. C_LIO_LIBoth Yap and Rif1 regulate the length of the first embryonic cell cycles. C_LIO_LILike Yap, Rif1 controls retinal stem cell DNA replication timing. C_LI