A bistable circuit involving SCARECROW-RETINOBLASTOMA integrates cues to inform asymmetic stem cell division

A. Cruz-Ramirez, S. Diaz-Trivino, I. Blilou, R. Benjamins, Y. Long, B.J.G. Scheres

Research output: Contribution to journalArticleAcademicpeer-review

180 Citations (Scopus)

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
JournalCell
Volume150
Issue number5
DOIs
Publication statusPublished - 2012

Keywords

  • protein-protein interactions
  • arabidopsis root-meristem
  • tumor-suppressor
  • split luciferase
  • auxin transport
  • cycle
  • gene
  • differentiation
  • plants
  • growth

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