A bistable circuit involving SCARECROW-RETINOBLASTOMA integrates cue to inform asymmetric stem cell division

L.A. Cruz Ramirez, S. Diaz-Trivino, I. Blilou, V Grieneisen, R. Sozzani, C Zamioudis, P. Miskolczi, J. Nieuwland, R. Benjamins, P.B. Dhonukshe, J. Caballero-Pérez, B.M. Horvath, Y. Long, A.P. Mähönen, H. Zhang, J. Xu, J.A.H. Murray, P.N. Benfey, L. Bako, A.F.M. MaréeB.J.G. Scheres

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

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 RETINOBLASTOMA-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.
Original languageEnglish
Pages (from-to)1002-1015
Number of pages14
JournalCell
Volume150
DOIs
Publication statusPublished - 2012

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