title: S6K1 and E2FB are in mutually antagonistic regulatory links controlling cell growth and proliferation in Arabidopsis.
abstract: Plant development is dependent on the coordination between growth and cell proliferation. The nutrient sensing TOR kinase and its downstream target, the 40S ribosomal S6 Kinase, are central controllers of cell growth that were also shown to determine cell size by inhibiting the onset of mitosis in yeast and animal cells. We have shown that the Arabidopsis S6 Kinase1 inhibits cell proliferation through the RBR-E2FB complex. S6K1 interacts with RBR via its N-terminal RBR binding motif, promotes its nuclear localization and consequent RBR-dependent repression of cell cycle genes through E2FB. Here we show that S6K1 and E2FB are in a mutually antagonistic relationship both in their protein abundance and in their activity. We propose that this double inhibitory regulatory connection between S6K1 and E2FB forms a regulatory switch that might be important to determine whether cells divide or grow.
authors.affiliation: Royal Holloway; University of London; School of Biological Sciences; Egham, UK.
authors.forename: Rossana
authors.initials: R
authors.lastname: Henriques
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Magyar
authors.forename: László
authors.initials: L
authors.lastname: Bögre
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D049108:Cell Enlargement; D049109:Cell Proliferation; D050684:E2F Transcription Factors / Q000378:metabolism*; D063245:Plant Development; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D050684:E2F Transcription Factors; C506682:E2Fb protein, Arabidopsis; C487568:RBR1 protein, Arabidopsis; D019893:Ribosomal Protein S6 Kinases
keywords: Arabidopsis; E2FB; RBR; S6K1; cell growth; cell proliferation; protein stability