title: Characterization of AtNUC-L1 reveals a central role of nucleolin in nucleolus organization and silencing of AtNUC-L2 gene in Arabidopsis.
abstract: Nucleolin is one of the most abundant protein in the nucleolus and is a multifunctional protein involved in different steps of ribosome biogenesis. In contrast to animals and yeast, the genome of the model plant Arabidopsis thaliana encodes two nucleolin-like proteins, AtNUC-L1 and AtNUC-L2. However, only the AtNUC-L1 gene is ubiquitously expressed in normal growth conditions. Disruption of this AtNUC-L1 gene leads to severe plant growth and development defects. AtNUC-L1 is localized in the nucleolus, mainly in the dense fibrillar component. Absence of this protein in Atnuc-L1 plants induces nucleolar disorganization, nucleolus organizer region decondensation, and affects the accumulation levels of pre-rRNA precursors. Remarkably, in Atnuc-L1 plants the AtNUC-L2 gene is activated, suggesting that AtNUC-L2 might rescue, at least partially, the loss of AtNUC-L1. This work is the first description of a higher eukaryotic organism with a disrupted nucleolin-like gene and defines a new role for nucleolin in nucleolus structure and rDNA chromatin organization.
authors.affiliation: Unité Mixte de Recherche Centre National de la Recherche Scientifique 5096, Université de Perpignan, Perpignan, 66860 Perpignan, France.
authors.forename: Frederic
authors.initials: F
authors.lastname: Pontvianne
authors.forename: Isabel
authors.initials: I
authors.lastname: Matía
authors.forename: Julien
authors.initials: J
authors.lastname: Douet
authors.forename: Sylvette
authors.initials: S
authors.lastname: Tourmente
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Medina
authors.forename: Manuel
authors.initials: M
authors.lastname: Echeverria
authors.forename: Julio
authors.initials: J
authors.lastname: Sáez-Vásquez
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000032:analysis / Q000235:genetics* / Q000502:physiology*; D002466:Cell Nucleolus / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D002467:Cell Nucleus / Q000737:chemistry; D004275:DNA, Ribosomal / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D018745:Genome, Plant / Q000235:genetics; D006570:Heterochromatin / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics; D010750:Phosphoproteins / Q000235:genetics / Q000502:physiology*; D012335:RNA, Ribosomal / Q000096:biosynthesis; D016601:RNA-Binding Proteins / Q000032:analysis / Q000235:genetics* / Q000502:physiology*; D000097796:Nucleolin
chemical_list: D029681:Arabidopsis Proteins; D004275:DNA, Ribosomal; D006570:Heterochromatin; D009687:Nuclear Proteins; D010750:Phosphoproteins; D012335:RNA, Ribosomal; D016601:RNA-Binding Proteins; D000097796:Nucleolin; C519187:NUC-L1 protein, Arabidopsis; C519188:NUC-L2 protein, Arabidopsis