title: Control of plant stem cell function by conserved interacting transcriptional regulators.
abstract: Plant stem cells in the shoot apical meristem (SAM) and root apical meristem are necessary for postembryonic development of aboveground tissues and roots, respectively, while secondary vascular stem cells sustain vascular development. WUSCHEL (WUS), a homeodomain transcription factor expressed in the rib meristem of the Arabidopsis SAM, is a key regulatory factor controlling SAM stem cell populations, and is thought to establish the shoot stem cell niche through a feedback circuit involving the CLAVATA3 (CLV3) peptide signalling pathway. WUSCHEL-RELATED HOMEOBOX 5 (WOX5), which is specifically expressed in the root quiescent centre, defines quiescent centre identity and functions interchangeably with WUS in the control of shoot and root stem cell niches. WOX4, expressed in Arabidopsis procambial cells, defines the vascular stem cell niche. WUS/WOX family proteins are evolutionarily and functionally conserved throughout the plant kingdom and emerge as key actors in the specification and maintenance of stem cells within all meristems. However, the nature of the genetic regime in stem cell niches that centre on WOX gene function has been elusive, and molecular links underlying conserved WUS/WOX function in stem cell niches remain unknown. Here we demonstrate that the Arabidopsis HAIRY MERISTEM (HAM) family of transcription regulators act as conserved interacting cofactors with WUS/WOX proteins. HAM and WUS share common targets in vivo and their physical interaction is important in driving downstream transcriptional programs and in promoting shoot stem cell proliferation. Differences in the overlapping expression patterns of WOX and HAM family members underlie the formation of diverse stem cell niche locations, and the HAM family is essential for all of these stem cell niches. These findings establish a new framework for the control of stem cell production during plant development.
authors.affiliation: Division of Biology, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Division of Biology, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
authors.forename: Xing
authors.initials: X
authors.lastname: Liu
authors.affiliation: Biology Department, College of William and Mary, Williamsburg, Virginia 23187-8795, USA.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Engstrom
authors.affiliation: 1] Division of Biology, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA [2] Howard Hughes Medical Institute, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
authors.forename: Zachary L
authors.initials: ZL
authors.lastname: Nimchuk
authors.affiliation: Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, California 92093, USA.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Pruneda-Paz
authors.affiliation: Division of Biology, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
authors.forename: Paul T
authors.initials: PT
authors.lastname: Tarr
authors.affiliation: Division of Biology, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
authors.forename: An
authors.initials: A
authors.lastname: Yan
authors.affiliation: University of Southern California, Molecular and Computational Biology, Department of Biological Sciences, Dana and David Dornsife College of Letters, Arts and Sciences, Los Angeles, California 90089, USA.
authors.forename: Steve A
authors.initials: SA
authors.lastname: Kay
authors.affiliation: 1] Division of Biology, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA [2] Howard Hughes Medical Institute, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
authors.forename: Elliot M
authors.initials: EM
authors.lastname: Meyerowitz
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D049109:Cell Proliferation; D018506:Gene Expression Regulation, Plant; D051548:Histone Acetyltransferases / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D018520:Plant Shoots / Q000166:cytology / Q000235:genetics; D011485:Protein Binding; D055153:Stem Cell Niche; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; C116421:WUSCHEL protein, Arabidopsis; C582654:HAM1 protein, Arabidopsis; D051548:Histone Acetyltransferases