title: Sense transgene-induced post-transcriptional gene silencing in tobacco compromises the splicing of endogenous counterpart genes.
abstract: Sense transgene-induced post-transcriptional gene silencing (S-PTGS) is thought to be a type of RNA silencing in which ARGONAUTE1 directs the small interfering RNA (siRNA)-mediated cleavage of a target mRNA in the cytoplasm. Here, we report that the altered splicing of endogenous counterpart genes is a main cause for the reduction of their mature mRNA levels. After the S-PTGS of a tobacco endoplasmic reticulum ω-3 fatty acid desaturase (NtFAD3) gene, 3'-truncated, polyadenylated endo-NtFAD3 transcripts and 5'-truncated, intron-containing endo-NtFAD3 transcripts were detected in the total RNA fraction. Although transcription proceeded until the last exon of the endogenous NtFAD3 gene, intron-containing NtFAD3 transcripts accumulated in the nucleus of the S-PTGS plants. Several intron-containing NtFAD3 transcripts harboring most of the exon sequences were generated when an endogenous silencing suppressor gene, rgs-CaM, was overexpressed in the S-PTGS plants. These intron-containing NtFAD3 splice variants were generated in the presence of NtFAD3 siRNAs that are homologous to the nucleotide sequences of these splice variants. The results of this study indicate that the inhibition of endo-NtFAD3 gene expression is primarily directed via the alteration of splicing and not by cytoplasmic slicer activity. Our results suggest that the transgene and intron-containing endogenous counterpart genes are differentially suppressed in S-PTGS plants.
authors.affiliation: Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba, Japan.
authors.forename: Mi-Rae
authors.initials: MR
authors.lastname: Shin
authors.affiliation: Graduate School of Horticulture, Chiba University, Chiba, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Natsuume
authors.affiliation: Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Setagaya-ku, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Graduate School of Horticulture, Chiba University, Chiba, Japan.
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Hanaoka
authors.affiliation: Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Setagaya-ku, Tokyo, Japan.
authors.forename: Misaki
authors.initials: M
authors.lastname: Imai
authors.affiliation: Department of Applied Biology and Chemistry, Tokyo University of Agriculture, Setagaya-ku, Tokyo, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Iijima
authors.affiliation: Graduate School of Horticulture, Chiba University, Chiba, Japan.
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Oka
authors.affiliation: Graduate School of Science and Technology, Chiba University, Inage-ku, Chiba, Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Adachi
authors.affiliation: Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kodama
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D001483:Base Sequence; D047369:Chromatin Immunoprecipitation; D017931:DNA Primers / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D059014:High-Throughput Nucleotide Sequencing; D008969:Molecular Sequence Data; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014026:Nicotiana / Q000235:genetics*; D019076:Transgenes / Q000235:genetics*
chemical_list: D017931:DNA Primers; D034741:RNA, Small Interfering; D044943:Fatty Acid Desaturases; C078565:omega-3 fatty acid desaturase