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A Bistable Circuit Involving SCARECROW-RETINOBLASTOMA Integrates Cues to Inform Asymmetric Stem Cell Division

  • Alfredo Cruz-Ramirez
  • , Sara Diaz-Trivino
  • , Ikram Blilou
  • , Veronica A. Grieneisen
  • , Rosangela Sozzani
  • , Christos Zamioudis
  • , Pal Miskolczi
  • , Jeroen Nieuwland
  • , Rene Benjamins
  • , Pankaj Dhonukshe
  • , Juan Caballero-Perez
  • , Beatrix Horvath
  • , Yuchen Long
  • , Ari Pekka Mahonen
  • , Hongtao Zhang
  • , Jian Xu
  • , James A. H. Murray
  • , Philip N. Benfey
  • , Laszlo Bako
  • , Athanasius F. M. Maree
  • Ben Scheres

Publication: Contribution to journalJournal articlepeer-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 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.
Original languageEnglish
Pages (from-to)1002-1015
Number of pages14
JournalCell
Volume150
Issue number5
DOIs
Publication statusPublished - 2012

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