Organizer-Derived WOX5 Signal Maintains Root Columella Stem Cells through Chromatin-Mediated Repression of CDF4 Expression

• Published in: Developmental cell Vol. 33; no. 5; pp. 576 - 588
• Main Authors: Pi, Limin, Aichinger, Ernst, van der Graaff, Eric, Llavata-Peris, Cristina I., Weijers, Dolf, Hennig, Lars, Groot, Edwin, Laux, Thomas
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 08.06.2015
• Subjects: Acetylation; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; arabidopsis-thaliana; Cell Differentiation; Chromatin - genetics; Chromatin Immunoprecipitation; Co-Repressor Proteins - genetics; Co-Repressor Proteins - metabolism; Developmental Biology; Electrophoretic Mobility Shift Assay; fate; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; gene-expression; histone deacetylase; Histone Deacetylases - genetics; Histone Deacetylases - metabolism; Histones - metabolism; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; In Situ Hybridization; meristem; Meristem - cytology; Meristem - metabolism; Microarray Analysis; Microscopy, Confocal; Nuclear Pore Complex Proteins - genetics; Nuclear Pore Complex Proteins - metabolism; Plant Roots - cytology; Plant Roots - metabolism; Promoter Regions, Genetic - genetics; protein; shoot; Signal Transduction; Stem Cell Niche; Stem Cells - cytology; Stem Cells - metabolism; topless; transcriptional repression; Utvecklingsbiologi; wuschel
• ISSN: 1534-5807; 1878-1551; 1878-1551
• DOI: 10.1016/j.devcel.2015.04.024

Stem cells in plants and animals are maintained pluripotent by signals from adjacent niche cells. In plants, WUSCHEL HOMEOBOX (WOX) transcription factors are central regulators of stem cell maintenance in different meristem types, yet their molecular mode of action has remained elusive. Here we show that in the Arabidopsis root meristem, the WOX5 protein moves from the root niche organizer, the quiescent center, into the columella stem cells, where it directly represses the transcription factor gene CDF4. This creates a gradient of CDF4 transcription, which promotes differentiation opposite to the WOX5 gradient, allowing stem cell daughter cells to exit the stem cell state. We further show that WOX5 represses CDF4 transcription by recruiting TPL/TPR co-repressors and the histone deacetylase HDA19, which consequently induces histone deacetylation at the CDF4 regulatory region. Our results show that chromatin-mediated repression of differentiation programs is a common strategy in plant and animal stem cell niches. [Display omitted] •WOX5 can reprogram differentiated columella cells into stem cells•Intercellular WOX5 movement maintains stem cell pluripotency•WOX5 represses the differentiation factor CDF4 via histone deacetylation•Opposing transcription factor gradients regulate stem cell balance Pi et al. provide evidence for transcription factor WOX5 functioning as a mobile organizer signal that represses differentiation in neighboring columella stem cells in the Arabidopsis root. WOX5 recruits TPL/TPR co-repressors and the histone deacetylase HDA19 to silence the differentiation factor CDF4 in the regulation of stem cell maintenance.