A Bistable Circuit Involving SCARECROW-RETINOBLASTOMA Integrates Cues to Inform Asymmetric Stem Cell Division
2012 (English)In: Cell, ISSN 0092-8674, E-ISSN 1097-4172, Vol. 150, no 5, 1002-1015 p.Article in journal (Refereed) Published
In plants, where cells cannot migrate, asymmetric cell divisions (ACDs) must be confined to the appropriate spatial context. We investigate tissue-generating asymmetric divisions in a stem cell daughter within the Arabidopsis root. Spatial restriction of these divisions requires physical binding of the stem cell regulator SCARECROW (SCR) by the RETINOBLASTOM-RELATED (RBR) protein. In the stem cell niche, SCR activity is counteracted by phosphorylation of RBR through a cyclinD6;1-CDK complex. This cyclin is itself under transcriptional control of SCR and its partner SHORT ROOT (SHR), creating a robust bistable circuit with either high or low SHR-SCR complex activity. Auxin biases this circuit by promoting CYCD6;1 transcription. Mathematical modeling shows that ACDs are only switched on after integration of radial and longitudinal information, determined by SHR and auxin distribution, respectively. Coupling of cell-cycle progression to protein degradation resets the circuit, resulting in a "flip flop" that constrains asymmetric cell division to the stem cell region.
Place, publisher, year, edition, pages
Elsevier, 2012. Vol. 150, no 5, 1002-1015 p.
Biochemistry and Molecular Biology Cell Biology
IdentifiersURN: urn:nbn:se:umu:diva-104253DOI: 10.1016/j.cell.2012.07.017ISI: 000308500200014PubMedID: 22921914OAI: oai:DiVA.org:umu-104253DiVA: diva2:819242