title: Mathematical modelling of WOX5- and CLE40-mediated columella stem cell homeostasis in Arabidopsis.
abstract: The root meristem of Arabidopsis thaliana harbours a pool of stem cells, which divide to give rise to the differentiated cells of the various root tissues. Regulatory networks of inter-cellular signalling molecules control the homeostasis of stem cell number and position so that both stem and differentiated cells are consistently available. This work focuses on the transcription factor WUSCHEL-RELATED HOMEOBOX 5 (WOX5), the signalling peptide CLAVATA3/EMBRYO-SURROUNDING REGION 40 (CLE40) and the feedback loops involving them, which maintain the columella stem cells (CSCs). WOX5 signals from the quiescent centre (QC) to promote stem cell fate, while CLE40 is secreted from the differentiated columella cells (CCs) to promote differentiation. Our analyses of mathematical models of this network show that, when cell fate is controlled primarily by antagonistic factors, homeostasis requires a spatial component and inter-cellular signalling. We have also found that WOX5 contributes to, but is not absolutely necessary for, CSC maintenance. Furthermore, our modelling led us to postulate an additional signalling molecule that promotes CSC maintenance. We propose that this WOX5-independent signal originates in the QC, is targeted by CLE40 signalling and is capable of maintaining CSCs.
authors.affiliation: Institute of Developmental Genetics, Heinrich Heine University, 40225 Düsseldorf, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Richards
authors.affiliation: Institute of Developmental Genetics, Heinrich Heine University, 40225 Düsseldorf, Germany.
authors.forename: Rene H
authors.initials: RH
authors.lastname: Wink
authors.affiliation: Institute of Developmental Genetics, Heinrich Heine University, 40225 Düsseldorf, Germany ruediger.simon@uni-duesseldorf.de.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Simon
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006706:Homeostasis; D018519:Meristem / Q000502:physiology; D008957:Models, Genetic; D018517:Plant Roots / Q000502:physiology; D013234:Stem Cells / Q000166:cytology / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; C506683:CLE40 protein, Arabidopsis; D018398:Homeodomain Proteins; C116421:WUSCHEL protein, Arabidopsis
keywords: CLE40; Columella cells; WOX5.; gene regulatory networks; peptide signalling; root development; stem cell homeostasis