Delayed activation of the DNA replication licensing system in Lgr5(+) intestinal stem cells


7 During late mitosis and early G1, replication origins are licensed for replication by binding to 8 MCM2-7 double hexamers. This signals proliferative fate commitment. Here, we investigate 9 how licensing and proliferative commitment are coupled in the small-intestinal epithelium. 10 We developed a method for identifying cells in intestinal crypts that contain DNA-bound 11 MCM2-7 and are licensed for replication. Interphase cells at the top of the transit amplifying 12 zone did not contain DNA-bound MCM2-7, but still expressed MCM2-7 protein. This 13 suggests licensing is inhibited immediately at terminal differentiation, after a final mitosis. 14 Strikingly, we found that at the crypt base the majority of Lgr5(+) intestinal stem cells reside 15 in an unlicensed state, despite expressing MCM2-7 protein and the Ki67 proliferation 16 marker. This state, which we call ‘shallow-G0’, might allow stem cells to be easily activated 17 to re-enter the cell cycle. We demonstrate that the dynamics of the licensing system 18 provides a novel means to assess the unique cell-cycle of intestinal epithelial cells. 19 20 not peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission. The copyright holder for this preprint (which was . doi: bioRxiv preprint first posted online Aug. 17, 2017;

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@inproceedings{Carroll2017DelayedAO, title={Delayed activation of the DNA replication licensing system in Lgr5(+) intestinal stem cells}, author={Thomas D. Carroll and Ian P. Newton and J Julian Blow and Inke S. N{\"a}thke}, year={2017} }