title: A bistable circuit involving SCARECROW-RETINOBLASTOMA integrates cues to inform asymmetric stem cell division.
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.
authors.affiliation: Molecular Genetics, Department of Biology, University of Utrecht, 3584 CH Utrecht, The Netherlands.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Cruz-Ramírez
authors.forename: Sara
authors.initials: S
authors.lastname: Díaz-Triviño
authors.forename: Ikram
authors.initials: I
authors.lastname: Blilou
authors.forename: Verônica A
authors.initials: VA
authors.lastname: Grieneisen
authors.forename: Rosangela
authors.initials: R
authors.lastname: Sozzani
authors.forename: Christos
authors.initials: C
authors.lastname: Zamioudis
authors.forename: Pál
authors.initials: P
authors.lastname: Miskolczi
authors.forename: Jeroen
authors.initials: J
authors.lastname: Nieuwland
authors.forename: René
authors.initials: R
authors.lastname: Benjamins
authors.forename: Pankaj
authors.initials: P
authors.lastname: Dhonukshe
authors.forename: Juan
authors.initials: J
authors.lastname: Caballero-Pérez
authors.forename: Beatrix
authors.initials: B
authors.lastname: Horvath
authors.forename: Yuchen
authors.initials: Y
authors.lastname: Long
authors.forename: Ari Pekka
authors.initials: AP
authors.lastname: Mähönen
authors.forename: Hongtao
authors.initials: H
authors.lastname: Zhang
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.forename: James A H
authors.initials: JA
authors.lastname: Murray
authors.forename: Philip N
authors.initials: PN
authors.lastname: Benfey
authors.forename: Laszlo
authors.initials: L
authors.lastname: Bako
authors.forename: Athanasius F M
authors.initials: AF
authors.lastname: Marée
authors.forename: Ben
authors.initials: B
authors.lastname: Scheres
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D060049:Asymmetric Cell Division; D056741:Cyclin D / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D058503:Mesophyll Cells / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D018517:Plant Roots / Q000166:cytology* / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D056741:Cyclin D; D007210:Indoleacetic Acids; C487568:RBR1 protein, Arabidopsis; C100978:SCR protein, Arabidopsis; D018844:Cyclin-Dependent Kinases