BABY BOOM target genes provide diverse entry points into cell proliferation and cell growth pathways

Plant Mol Biol. 2008 Oct;68(3):225-37. doi: 10.1007/s11103-008-9364-y. Epub 2008 Jul 29.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Arabidopsis / cytology*
  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism
  • Brassica napus / genetics*
  • Cell Enlargement*
  • Cell Proliferation
  • Cytoskeleton / metabolism
  • Gene Expression Regulation, Plant
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism
  • Oligonucleotide Array Sequence Analysis
  • Seedlings / genetics
  • Seedlings / growth & development
  • Seedlings / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Actins
  • Heat-Shock Proteins
  • Transcription Factors