Rei Yoshimoto

Setsunan University · Faculty of Pharmaceutical Sciences

Pre-mRNA splicing occurs in a large complex spliceosome. The steps of both spliceosome assembly and splicing reaction have been extensively analyzed, and many of the factors involved have been identified. However, the post-splicing intron turnover process, especially in vertebrates, remains to be examined. In this paper, we developed a two-tag affi...

Spliceostatin A (SSA) is a methyl ketal derivative of FR901464, a potent antitumor compound isolated from a culture broth of Pseudomonas sp. no. 2663. These compounds selectively bind to the essential spliceosome component SF3b, a subcomplex of the U2 snRNP, to inhibit pre-mRNA splicing. However, the mechanism of SSA's antitumor activity is unknown...

Circular RNAs (circRNAs) are stable non-coding RNAs with a closed circular structure. One of the best studied circRNAs is ciRS-7 (CDR1as) that acts as a regulator of the microRNA miR-7; however, its biosynthesis pathway has remained an enigma. Here we delineate the biosynthesis pathway of ciRS-7. The back-splicing events that form circRNAs are ofte...

RNA splicing, a highly conserved process in eukaryotic gene expression, is seen as a promising target for anticancer agents. Splicing is associated with other RNA processing steps, such as transcription and nuclear export; however, our understanding of the interaction between splicing and other RNA regulatory mecha- nisms remains incomplete. Moreov...

Histidine (His) residues are methylated in various proteins, but their roles and regulation mechanisms remain unknown. Here, we show that carnosine N-methyltransferase 1 (CARNMT1), a known His methyltransferase of dipeptide carnosine (βAla-His), is a major His N1-position-specific methyltransferase. We found that 52 His sites in 20 proteins underwe...

Short Interspersed Elements (SINEs) comprise a significant portion of the genomes of higher eukaryotes, including humans and mice. This review focuses on SINE- derived noncoding RNAs (ncRNAs), particularly BC1, BC200, and 4.5SH RNA, which are expressed abundantly and in a species-specific manner. These ncRNAs seem to have independently evolved thei...

We recently demonstrated that splicing in a subset of human short introns with a truncated polypyrimidine tract (PPT) depends on RBM17 (SPF45) instead of the known essential splicing factor, U2AF2-U2AF1 (U2AF65-U2AF35). On a truncated PPT, the UHM (U2AF-homology motif) of RBM17 can interact with the ULM (UHM-ligand motif) of SF3B1 (SF3b155) in the...

Pre-mRNA splicing is an indispensable mechanism for eukaryotic gene expression. Splicing inhibition causes cell cycle arrest at the G1 and G2/M phases, and this is thought to be one of the reasons for the potent antitumor activity of splicing inhibitors. However, the molecular mechanisms underlying the cell cycle arrest have many unknown aspects. I...

A huge number of noncoding RNAs are transcribed from the genomes of higher eukaryotes, many of which are species-specific and localize in the nucleus with unknown function. 4.5SH RNA is a highly abundant, small rodent-specific noncoding RNA that localizes to nuclear speckles enriched in pre-mRNA splicing regulators. Here we show that mutant mice la...

The biogenesis of small non-coding RNAs is a molecular event that contributes to cellular functions. The basidiomycete fungus Ustilago maydis is a biotrophic pathogen parasitizing maize. A hallmark of its genome structure is an absence of RNAi machinery including Dicer and Argonaute proteins, which are responsible for the production of small RNAs i...

Pre-mRNA splicing is indispensable for eukaryotic gene expression. Splicing inhibition causes cell cycle arrest and cell death, which are the reasons of potent anti-tumor activity of splicing inhibitors. Here, we found that truncated proteins are involved in cell cycle arrest and cell death upon splicing inhibition. We analyzed pre-mRNAs accumulate...

Human pre-mRNA introns vary in size from under fifty to over a million nucleotides. We searched for essential factors involved in the splicing of human short introns by screening siRNAs against 154 human nuclear proteins. The splicing activity was assayed with a model HNRNPH1 pre-mRNA containing short 56-nucleotide intron. We identify a known alter...

Human pre-mRNA introns vary in size from under fifty to over a million nucleotides. We searched for essential factors specifically involved in the splicing of human short introns by screening siRNAs against 154 human nuclear proteins for activity on a model short 56-nucleotide intron-containing HNRNPH1 pre-mRNA. We identified a known alternative sp...

Human pre-mRNA introns vary in size from under fifty to over a million nucleotides. We searched for specific splicing factors involved in human short introns by screening siRNAs against 154 human nuclear proteins for activity on a model short 56-nucleotide intron-containing HNRNPH1 pre-mRNA. We identified a known alternative splicing regulator SPF4...

Significance p180/ RRBP1 is an essential factor for high-rate protein synthesis on the endoplasmic reticulum (ER) in terminally differentiated secretory cells. A unique system for selectively enhanced translation has been proposed for p180-associated polyribosomes. Here we provide evidence that SF3b4, an RNA-binding protein in the splicing factor,...

CircRNAs are abundant stable noncoding RNAs with covalently closed circular structure. The first characterized circRNA, ciRS-7 (CDR1as), acts as a 'sponge', or decoy, that regulates the stability and activity of miR-7 micro RNA. Here we demonstrate the definitive biosynthesis pathway of this important ciRS-7. By anti-sense oligoribonucleotide targe...

In eukaryotes, pre-mRNA splicing is an essential step for gene expression. We have been analyzing post-splicing intron turnover steps in higher eukaryotes. Here, we report protein interaction between human Debranching enzyme 1 (hDbr1) and several factors found in the Intron Large (IL) complex, which is an intermediate complex of the intron degradat...

Splicing, a process for mRNA maturation, is essential for correct gene expression after transcription. However, recent studies also suggest that splicing affects transcription, but its mechanism remains elusive. We previously reported that treatment with spliceostatin A (SSA), a specific splicing inhibitor targeting the splicing factor SF3b, leads...

To identify the novel factors involved in the postsplicing intron turnover pathway, we carried out immunoprecipitation with known postsplicing factors, hPrp43 and TFIP11. As an interacting factor, we identified C2ORF3 protein by mass spectrometry. We found that C2ORF3 protein is present in the previously characterized Intron Large (IL) complex with...

RNA splicing is an important target for basic research of disease mechanisms and for drug discovery. Here, we report a new method for analysis of the in vitro RNA splicing process that produces fluorescence using a reduction-triggered fluorescence (RETF) probe. The fluorescence signal is produced only when the two probes bind side-by-side with a sp...

The Far UpStream Element (FUSE)-binding protein-interacting repressor (FIR), a c-myc transcriptional suppressor, is alternatively spliced removing the transcriptional repression domain within exon 2 (FIRΔexon2) in colorectal cancers. SAP155 is a subunit of the essential splicing factor 3b (SF3b) subcomplex in the spliceosome. This study aims to stu...

Fluorescence through proximity: Reduction-triggered fluorescent probes bearing either a fluorescein derivative or triphenylphosphine bind sequence-specifically at the branch site of lariat RNA. The chemical reaction between the two substrates leads to the formation of unquenched fluorescein and the emission of a fluorescence signal (see picture). P...

Gomafu (also referred to as RNCR2/MIAT) was originally identified as a noncoding RNA expressed in a particular set of neurons. Unlike protein-coding mRNAs, the Gomafu RNA escapes nuclear export and stably accumulates in the nucleus, making a unique nuclear compartment. Although recent studies have revealed the functional relevance of Gomafu in a se...