title: Aberrant mRNA transcripts and the nonsense-mediated decay proteins UPF2 and UPF3 are enriched in the Arabidopsis nucleolus.
abstract: The eukaryotic nucleolus is multifunctional and involved in the metabolism and assembly of many different RNAs and ribonucleoprotein particles as well as in cellular functions, such as cell division and transcriptional silencing in plants. We previously showed that Arabidopsis thaliana exon junction complex proteins associate with the nucleolus, suggesting a role for the nucleolus in mRNA production. Here, we report that the plant nucleolus contains mRNAs, including fully spliced, aberrantly spliced, and single exon gene transcripts. Aberrant mRNAs are much more abundant in nucleolar fractions, while fully spliced products are more abundant in nucleoplasmic fractions. The majority of the aberrant transcripts contain premature termination codons and have characteristics of nonsense-mediated decay (NMD) substrates. A direct link between NMD and the nucleolus is shown by increased levels of the same aberrant transcripts in both the nucleolus and in Up-frameshift (upf) mutants impaired in NMD. In addition, the NMD factors UPF3 and UPF2 localize to the nucleolus, suggesting that the Arabidopsis nucleolus is therefore involved in identifying aberrant mRNAs and NMD.
authors: Genetics Programme, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, Scotland, United Kingdom.
authors: Sang Hyon
authors: SH
authors: Kim
authors: Olga A
authors: OA
authors: Koroleva
authors: Dominika
authors: D
authors: Lewandowska
authors: Ali F
authors: AF
authors: Pendle
authors: Gillian P
authors: GP
authors: Clark
authors: Craig G
authors: CG
authors: Simpson
authors: Peter J
authors: PJ
authors: Shaw
authors: John W S
authors: JW
authors: Brown
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002466:Cell Nucleolus / Q000378:metabolism*; D046169:Dermoscopy; D012333:RNA, Messenger / Q000235:genetics*
chemical_list: D029681:Arabidopsis Proteins; D012333:RNA, Messenger; C504799:UPF3 protein, Arabidopsis