title: BABY BOOM target genes provide diverse entry points into cell proliferation and cell growth pathways.
abstract: Ectopic expression of the Brassica napus BABY BOOM (BBM) AP2/ERF transcription factor is sufficient to induce spontaneous cell proliferation leading primarily to somatic embryogenesis, but also to organogenesis and callus formation. We used DNA microarray analysis in combination with a post-translationally regulated BBM:GR protein and cycloheximide to identify target genes that are directly activated by BBM expression in Arabidopsis seedlings. We show that BBM activated the expression of a largely uncharacterized set of genes encoding proteins with potential roles in transcription, cellular signaling, cell wall biosynthesis and targeted protein turnover. A number of the target genes have been shown to be expressed in meristems or to be involved in cell wall modifications associated with dividing/growing cells. One of the BBM target genes encodes an ADF/cofilin protein, ACTIN DEPOLYMERIZING FACTOR9 (ADF9). The consequences of BBM:GR activation on the actin cytoskeleton were followed using the GFP:FIMBRIN ACTIN BINDING DOMAIN2 (GFP:FABD) actin marker. Dexamethasone-mediated BBM:GR activation induced dramatic changes in actin organization resulting in the formation of dense actin networks with high turnover rates, a phenotype that is consistent with cells that are rapidly undergoing cytoplasmic reorganization. Together the data suggest that the BBM transcription factor activates a complex network of developmental pathways associated with cell proliferation and growth.
authors.affiliation: Plant Research International, P.O. Box 16, 6700 AA Wageningen, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Passarinho
authors.forename: Tijs
authors.initials: T
authors.lastname: Ketelaar
authors.forename: Meiqing
authors.initials: M
authors.lastname: Xing
authors.forename: Jeroen
authors.initials: J
authors.lastname: van Arkel
authors.forename: Chris
authors.initials: C
authors.lastname: Maliepaard
authors.forename: Mieke Weemen
authors.initials: MW
authors.lastname: Hendriks
authors.forename: Ronny
authors.initials: R
authors.lastname: Joosen
authors.forename: Michiel
authors.initials: M
authors.lastname: Lammers
authors.forename: Lydia
authors.initials: L
authors.lastname: Herdies
authors.forename: Bart
authors.initials: B
authors.lastname: den Boer
authors.forename: Lonneke
authors.initials: L
authors.lastname: van der Geest
authors.forename: Kim
authors.initials: K
authors.lastname: Boutilier
mesh_terms: D000199:Actins / Q000378:metabolism; D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029688:Brassica napus / Q000235:genetics*; D049108:Cell Enlargement; D049109:Cell Proliferation; D003599:Cytoskeleton / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D006360:Heat-Shock Proteins; D014157:Transcription Factors