title: Active 5' splice sites regulate the biogenesis efficiency of Arabidopsis microRNAs derived from intron-containing genes.
abstract: Arabidopsis, miR402 that is encoded within the first intron of a protein-coding gene At1g77230, is induced by heat stress. Its upregulation correlates with splicing inhibition and intronic proximal polyA site selection. It suggests that miR402 is not processed from an intron, but rather from a shorter transcript after selection of the proximal polyA site within this intron. Recently, introns and active 5' splice sites (5'ss') have been shown to stimulate the accumulation of miRNAs encoded within the first exons of intron-containing MIR genes. In contrast, we have observed the opposite effect of splicing inhibition on intronic miR402 production. Transient expression experiments performed in tobacco leaves revealed a significant accumulation of the intronic mature miR402 when the 5'ss of the miR402-hosting intron was inactivated. In contrast, when the miR402 stem-loop structure was moved into the first exon, mutation of the first-intron 5'ss resulted in a decrease in the miRNA level. Thus, the 5'ss controls the efficiency of miRNA biogenesis. We also show that the SERRATE protein (a key component of the plant microprocessor) colocalizes and interacts with several U1 snRNP auxiliary proteins. We postulate that SERRATE-spliceosome connections have a direct effect on miRNA maturation.
authors.affiliation: Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznan 61-614, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Knop
authors.affiliation: Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznan 61-614, Poland.
authors.forename: Agata
authors.initials: A
authors.lastname: Stepien
authors.affiliation: Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznan 61-614, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Barciszewska-Pacak
authors.affiliation: Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznan 61-614, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Taube
authors.affiliation: Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznan 61-614, Poland.
authors.forename: Dawid
authors.initials: D
authors.lastname: Bielewicz
authors.affiliation: Department of Molecular and Cellular Biology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznan, 61-614, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Michalak
authors.affiliation: Laboratory of Biochemistry and Microspectroscopy Centre, Wageningen University, Stippeneng 4 Wageningen 6708, The Netherlands.
authors.forename: Jan W
authors.initials: JW
authors.lastname: Borst
authors.affiliation: Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznan 61-614, Poland artjarmo@amu.edu.pl.
authors.forename: Artur
authors.initials: A
authors.lastname: Jarmolowski
authors.affiliation: Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznan 61-614, Poland zofszwey@amu.edu.pl.
authors.forename: Zofia
authors.initials: Z
authors.lastname: Szweykowska-Kulinska