Biology subjects

Mayeda, A.

Publications and source records attributed to Mayeda, A..

6 recordsLinked to original sources

bioRxiv2026

Two closely related RNA helicases, UAP56 and URH49, couple mRNA splicing and export pathways with their distinct complexes

Transcription and mRNA processing are integrated into appropriate mRNA export pathway(s) enabling fine-tuned gene expression. The closely related RNA helicases, UAP56 and URH49, form distinct complexes known as the apo-TREX and the apo-AREX complexes, respectively, which remodel into the ATP-TREX complexes, thus forming multiple mRNA export pathways. However, the mechanisms by which helicases and their complexes shape these pathways remain unclear. Here, we showed that UAP56 and URH49 play general roles in mRNA splicing ahead of export. Further analyses revealed three patterns of splicing regulation and their association with mRNA export: Type I, in which both helicases redundantly or synergistically regulate splicing within the same transcripts, associated with cooperative mRNA export; Type II, in which either helicase preferentially regulates splicing in distinct transcripts; and Type III, in which the helicases exert opposing splicing effects within the same transcripts. Type II and III regulation was associated with selective mRNA export. Moreover, we demonstrated that the distinct complex formation influenced the splicing patterns regulated by the two helicases. Our findings reveal an additional layer of transcriptome regulation mediated by UAP56, URH49, and their complexes, extending beyond their canonical roles in mRNA export.

molecular biology↗

bioRxiv2023

RNPS1 in PSAP complex controls cyclical pre-mRNA splicing over the cell cycle

Cell cycle progression requires periodic gene expression through splicing control. However, the splicing factor that directly controls this cell cycle-dependent splicing remain unknown. Cell cycle-dependent expression of the AURKB (aurora kinase B) gene is essential for chromosome segregation and cytokinesis. We previously reported that RNPS1 is essential to maintain precise splicing in AURKB intron 5. Here we show that RNPS1 plays this role in PSAP complex with PNN and SAP18, but not ASAP complex with ACIN1 and SAP18. Whole-transcriptome sequencing of RNPS1- and PNN-deficient cells indicated that RNPS1, either alone or as PSAP complex, is an essential splicing factor for a subset of introns. Remarkably, protein expression of RNPS1, but not PNN, is coordinated with cyclical splicing in PSAP-controlled introns including AURKB intron 5. The ubiquitin-proteasome pathway is involved in the periodic decrease of RNPS1 protein level. RNPS1 is a key factor that controls periodic splicing during the cell cycle. O_FIG O_LINKSMALLFIG WIDTH=185 HEIGHT=200 SRC="FIGDIR/small/567984v3_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@84475dorg.highwire.dtl.DTLVardef@693637org.highwire.dtl.DTLVardef@16678feorg.highwire.dtl.DTLVardef@917ee0_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIThe AURKB gene encodes a protein kinase essential for cytokinesis and cell cycle C_LIO_LIPSAP complex (RNPS1, PNN, SAP18) is required for precise splicing in AURKB intron 5 C_LIO_LIRNPS1 protein in PSAP complex controls periodical splicing during the cell cycle C_LIO_LICyclical decrease of RNPS1 protein is mediated by the ubiquitin-proteasome pathway C_LI

molecular biology↗

bioRxiv2022

The RBM17/SPF45-SAP30BP interaction is essential for splicing in a subset of human short introns

Human pre-mRNA splicing requires the removal of introns with highly variable lengths, from tens to over a million nucleotides. Therefore, mechanisms of intron recognition and splicing are likely not universal. Recently, we reported that splicing in a subset of human short introns with truncated polypyrimidine tracts depends on RBM17 (SPF45), instead of the canonical splicing factor U2AF heterodimer. Here, we demonstrate that SAP30BP, a factor previously implicated in transcriptional control, is an essential splicing cofactor for RBM17. In vitro binding and NMR analyses demonstrate that a U2AF-homology motif (UHM) in RBM17 binds directly to a newly identified UHM-ligand motif (ULM) in SAP30BP. We show that this RBM17-SAP30BP interaction is required to specifically recruit RBM17 to phosphorylated SF3B1 (SF3b155), a U2 snRNP component in active spliceosomes. We propose a unique mechanism for splicing in a subset of short introns, in which SAP30BP guides RBM17 in the assembly of active spliceosomes. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=193 SRC="FIGDIR/small/522300v4_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@12da1c3org.highwire.dtl.DTLVardef@d71e53org.highwire.dtl.DTLVardef@108160corg.highwire.dtl.DTLVardef@1df7275_HPS_FORMAT_FIGEXP M_FIG C_FIG In briefFukumura et al. discover a general splicing mechanism in a subset of human short introns with truncated polypyrimidine tracts. This splicing reaction is mediated by intermediary RBM17-SAP30BP complex, instead of the known U2AF heterodimer. SAP30BP binding to RBM17 may support RBM17 association with active phosphorylated SF3B1 in U2 snRNP. HighlightsO_LIRBM17 (SPF45) is a splicing factor required for a subset of human short introns C_LIO_LISAP30BP is an essential cofactor, which interacts with RBM17 via UHM-ULM binding C_LIO_LIRBM17 forms a weak complex with SAP30BP before its binding with SF3B1 in U2 snRNP C_LIO_LIRBM17-SAP30BP complex supports RBM17 to be recruited to active phosphorylated SF3B1 C_LI

molecular biology↗

bioRxiv2021

The Exon Junction Complex Core Represses Caner-specific Mature mRNA Re-splicing: A Potential Key Role in Terminating Splicing

Using the TSG101 pre-mRNA, we previously discovered cancer-specific resplicing of mature mRNA that generates aberrant transcripts/proteins. The fact that mRNA is aberrantly re-spliced in various cancer cells implies there must be an important mechanism to prevent deleterious re-splicing on the spliced mRNA in normal cells. We thus postulated that the mRNA re-splicing is controlled by specific repressors, and we searched for repressor candidates by siRNA-based screening for mRNA re-splicing activity. We found that knockdown of EIF4A3, which is a core component of the exon junction complex (EJC), significantly promoted mRNA re-splicing. Remarkably, we could recapitulate cancer-specific mRNA resplicing in normal cells by knock-down of any of the core EJC proteins, EIF4A3, MAGOH or RBM8A (Y14), implicating the EJC core as the repressor of mRNA re-splicing often observed in cancer cells. We propose that the EJC core is a critical mRNA quality control factor to prevent over-splicing of mature mRNA.

molecular biology↗

bioRxiv2019

A Distinct Subset of Human Short Introns: U2AF Heterodimer Is Replaced by SPF45 (RBM17) as General Splicing Factor

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 identified a known alternative splicing regulator SPF45 (RBM17) as a constitutive splicing factor that is required to splice out this 56-nt intron. Whole-transcriptome sequencing of SPF45-deficient cells revealed that SPF45 is essential in the efficient splicing of many short introns. To initiate the spliceosome assembly on a short intron with the truncated poly-pyrimidine tract, the U2AF-homology motif (UHM) of SPF45 competes out that of U2AF65 for binding to the UHM-ligand motif (ULM) of the U2 snRNP protein SF3b155 (SF3B1). We propose that splicing in a distinct subset of human short introns depends on SPF45 but not U2AF heterodimer.

molecular biology↗

bioRxiv2018

The functional circular RNA, ciRS-7 (CDR1as), is biosynthesized using back-splicing promoted by inverted mammalian-wide MIRs but not primate-specific Alus

Circular RNAs (circRNAs) are stable noncoding RNAs with a closed circular structure. One of the first and best studied circRNAs is ciRS-7 (CDR1as) that acts as a regulator of the microRNA miR-7, however, the biosynthesis pathway has remained an enigma. Here we delineate the biosynthesis pathway of ciRS-7. The back-splicing events that form circRNAs are often facilitated by flanking inverted repeats of the primate-specific Alu elements. ciRS-7 gene lacks these elements but, instead, we identified a set of flanking inverted elements belonging to the mammalian-wide interspersed repeat (MIR) family. Splicing reporter assays in HEK293 cells demonstrated that these inverted MIRs are required to generate ciRS-7 through a back-splicing and CRISPR/Cas9-mediated deletions confirmed the requirement of the endogenous MIR elements in SH-SY5Y cells. Using bioinformatics searches, we identified several other MIR-dependent circRNAs that we confirmed experimentally. We propose that MIR-mediated RNA circularization constitutes a new widespread biosynthesis principle for mammalian circRNAs.

molecular biology↗