title: A genetic link between epigenetic repressor AS1-AS2 and a putative small subunit processome in leaf polarity establishment of Arabidopsis.
abstract: Although the DEAD-box RNA helicase family is ubiquitous in eukaryotes, its developmental role remains unelucidated. Here, we report that cooperative action between the Arabidopsis nucleolar protein RH10, an ortholog of human DEAD-box RNA helicase DDX47, and the epigenetic repressor complex of ASYMMETRIC-LEAVES1 (AS1) and AS2 (AS1-AS2) is critical to repress abaxial (ventral) genes ETT/ARF3 and ARF4, which leads to adaxial (dorsal) development in leaf primordia at shoot apices. Double mutations of rh10-1 and as2 (or as1) synergistically up-regulated the abaxial genes, which generated abaxialized filamentous leaves with loss of the adaxial domain. DDX47 is part of the small subunit processome (SSUP) that mediates rRNA biogenesis. In rh10-1 we found various defects in SSUP-related events, such as: accumulation of 35S/33S rRNA precursors; reduction in the 18S/25S ratio; and nucleolar hypertrophy. Double mutants of as2 with mutations of genes that encode other candidate SSUP-related components such as nucleolin and putative rRNA methyltransferase exhibited similar synergistic defects caused by up-regulation of ETT/ARF3 and ARF4 These results suggest a tight link between putative SSUP and AS1-AS2 in repression of the abaxial-determining genes for cell fate decisions for adaxial development.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Matsumura
authors.affiliation: Botanical Gardens, Graduate School of Science, The University of Tokyo, Hakusan 3-7-1, Bunkyo-ku, Tokyo 112-0001, Japan.
authors.forename: Iwai
authors.initials: I
authors.lastname: Ohbayashi
authors.affiliation: Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo-shi, Chiba 271-8510, Japan.
authors.forename: Hiro
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Graduate School of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Kojima
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
authors.forename: Nanako
authors.initials: N
authors.lastname: Ishibashi
authors.affiliation: Graduate School of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan.
authors.forename: Sumie
authors.initials: S
authors.lastname: Keta
authors.affiliation: Graduate School of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan.
authors.forename: Ayami
authors.initials: A
authors.lastname: Nakagawa
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
authors.forename: Rika
authors.initials: R
authors.lastname: Hayashi
authors.affiliation: CNRS, Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan 66860, France Université de Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan F-66860, France.
authors.forename: Julio
authors.initials: J
authors.lastname: Saéz-Vásquez
authors.affiliation: CNRS, Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan 66860, France Université de Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan F-66860, France.
authors.forename: Manuel
authors.initials: M
authors.lastname: Echeverria
authors.affiliation: Botanical Gardens, Graduate School of Science, The University of Tokyo, Hakusan 3-7-1, Bunkyo-ku, Tokyo 112-0001, Japan.
authors.forename: Munetaka
authors.initials: M
authors.lastname: Sugiyama
authors.affiliation: Graduate School of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan.
authors.forename: Kenzo
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Graduate School of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan yas@bio.nagoya-u.ac.jp cmachida@isc.chubu.ac.jp.
authors.forename: Chiyoko
authors.initials: C
authors.lastname: Machida
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan yas@bio.nagoya-u.ac.jp cmachida@isc.chubu.ac.jp.
authors.forename: Yasunori
authors.identifier: http://orcid.org/0000-0002-2764-918X
authors.initials: Y
authors.lastname: Machida
keywords: AS1-AS2; Arabidopsis thaliana; Epigenetic repression; Leaf polarity; Nucleolus factors; SSU processome