Project description:To study pre-mRNA splicing function of the ubiquitin-like protein Hub1/UBL-5 in Caenorhabditis elegans. We have employed splicing-sensitive microarray expression profiling to examine the changes in pre-mRNA splicing. We collected wild-type and ubl-5 knock out worms at L3 stage and isolated total RNA. Which was reverse transcribed to double-stranded cDNA and cRNA was generated by in vitro transcription. The labeled cRNA samples were fragmented at 60°C and hybridized on to an Agilent Gene Expression Microarray. The data showed accumulation of intron- and outron containing transcripts in ubl-5 knockout worms in comparison to wild-type worms
Project description:The conserved ubiquitin-like protein Hub1/UBL-5 associates with proteins non-covalently. In yeast and human cells, Hub1 promotes splicing of precursor mRNAs with weak introns and alternative splicing, however, its splicing function has remained elusive in multicellular organisms. We demonstrate the splicing function of Hub1/UBL-5 in the free-living nematode Caenorhabditis elegans. UBL-5 binds to the HIND-containing splicing factors Snu66/SART-1 and PRP-38 and associates with other spliceosomal proteins. Caenorhabditis elegans hub1/ubl-5 mutants die at the larval L3 stage, and show accumulation of intron- and outron-containing transcripts. The latter observation adds to UBL-5’s splicing function in trans-RNA splicing. UBL-5 complements splicing defects of hub1-knockout Schizosaccharomyces pombe, confirming its functional conservation. Thus, UBL-5 is important for C. elegans development and cis- and trans-RNA splicing.
Project description:RNA splicing, the process of intron removal from pre-mRNA, is essential for the regulation of gene expression. It is controlled by the spliceosome, a megadalton RNA-protein complex that assembles de novo on each pre-mRNA intron via an ordered assembly of intermediate complexes. Spliceosome activation is a major control step requiring dramatic protein and RNA rearrangements leading to a catalytically active complex. Splicing factor 3B subunit 1 (SF3B1) protein, a subunit of the U2 snRNP, is phosphorylated during spliceosome activation, but the responsible kinase has not been identified. Here we show that cyclin-dependent kinase 11 (CDK11) associates with SF3B1 and phosphorylates threonine residues at its N-terminus during spliceosome activation. The phosphorylation is important for association of SF3B1 with U5 and U6 snRNAs in spliceosome activated Bact complex and it can be blocked by OTS964, a potent and selective inhibitor of CDK11. CDK11 inhibition prevents spliceosomal transition from the precatalytic complex B to the activated complex Bact and leads to widespread intron retention and accumulation of non-functional spliceosomes on pre-mRNAs and chromatin. We characterize OTS964 as a quality chemical biology probe for CDK11 and demonstrate a central role of CDK11 in spliceosome assembly and splicing regulation.
Project description:In this study, we identified many new potential interactors of the Aurora-A kinase using a proteomic approach. A significant portion of Aurora-A interaction network is composed of proteins involved in pre-mRNA splicing, implying that Aurora-A signaling extends beyond its canonical function. Aurora-A directly interacts with many of the RRM domain-containing splicing factors such as SR proteins and hnRNP proteins and phosphorylates them in vitro. Aurora-A shows a subcellar distribution to nuclear speckles, the storehouse of splicing factors, consistent with its potential function in pre-mRNA splicing. Moreover, RNA-seq analysis of pharmacologically inhibited Aurora-A cells identified 261 genes whose RNA splicing is dependent on Aurora-A activity. These splicing affected genes are involved in various biological processes such as transcription, GTPase activity, ciliogenesis, DNA repair, RNA splicing and G2/M transition. Here, for the first time, we uncovered a relationship between Aurora-A activity and mRNA processing through a complex network of factors involved in RNA maturation.
Project description:Here we examine the role of mRNA splicing in Caenorhabditis elegans RNAi. We find that viable null mutations in U1 and U2-snRNP-specific splicing factor genes cause defects in RNAi. The U1A orthologue rnp-2 is required for normal ERGO-1 Argonaute-class 26G siRNA biogenesis, trans-splicing of the eri-6/7 transcript and targeting of poorly conserved gene transcripts by WAGO Argonaute-class 22G siRNAs. We find that poorly spliced gene transcripts engaged by the siRNA generating machinery are poorly conserved, possess few introns, and often have introns that are divergent from introns found in highly conserved genes.
Project description:Dysregulation of pre-mRNA alternative splicing (AS) is closely associated with cancers. However, the relationships between the AS and classic oncogenes/tumor suppressors are largely unknown. Here we show that the deletion of tumor suppressor PTEN alters pre-mRNA splicing in its phosphatase-independent manner, and identify262 PTEN-regulated AS events in 293T cells by RNA sequencing, which are associated with significant worse outcome of cancer patients. Based on these findings, we report that nuclear PTEN interacts with the splicing machinery, spliceosome, to regulate its assembly and pre-mRNA splicing. Especially, the exon-2b exclusion of GOLGA2 contributes to PTEN knockdown-induced tumorigenesis by promoting dramatic Golgi extension and secretion, and PTEN depletion significantly sensitizes cancer cells to secretion inhibitors, Brefeldin A and Golgicide A. Given that many cancers lack PTEN expression, our results suggest that Golgi secretion inhibitors alone or in combination with PI3K/Akt kinase inhibitors may be therapeutically useful for PTEN-deficient cancers.
Project description:Cyclin-dependent kinase 11 (CDK11) is essential for the regulation of pre-mRNA splicing by phosphorylating SF3B1, a core spliceosome component. This phosphorylation is a marker of the catalytically active spliceosome, so it is important to identify the mechanisms that regulate CDK11. Herein, we report that a small subset of CDK11 is phosphorylated on the activation T-loop threonine 595 (Thr595) and is associated with the activated spliceosome on chromatin in gene bodies. Mutational analyses revealed that Thr595 is essential for the formation of the active CDK11 complex with cyclin L and SAP30BP. CDK11 transiently associates with CDK7, a transcriptional kinase that also promotes the activation of other CDKs. The time course of the inhibition of CDK7 initially decreases transcription, but later produces unspliced pre-mRNAs. The dynamics of onset of the CDK7-mediated splicing defect correlates with the sequential dephosphorylation of CDK11 Thr595 and SF3B1. SILAC-based phospho-proteomics upon brief CDK11 inhibition identified SF3B1, CDC5L and ESS2 as CDK11 substrates, an overlap with the previously identified CDK7 substrates in the spliceosome. In summary, our study suggests that CDK7 likely acts via CDK11 Thr595 phosphorylation to regulate pre-mRNA splicing in cells. The identification of additional CDK11 substrates indicates its more complex role in spliceosome regulation.