Son Maintains Accurate Splicing of Pre-mRNAs Encoding Chromatin Modifiers
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE28672 | GEO | 2011/12/22
SECONDARY ACCESSION(S): PRJNA138951
REPOSITORIES: GEO
Similar Datasets
Project description:Exon and expression analysis of HeLa cells after knockdown of SON Serine-arginine-rich (SR) proteins play a key role in alternative pre-mRNA splicing in eukaryotes. Our laboratory recently showed that a large SR protein called Son has unique repeat motifs that are essential for maintaining the subnuclear organization of pre-mRNA processing factors in nuclear speckles. Motif analysis of Son highlights putative RNA interaction domains that suggest a direct role for Son in pre-mRNA splicing. A genome-wide screen was performed to identify putative human transcription and splicing targets of Son. HeLa cells were transfected with siRNA against SON or a control siRNA (siLuciferase) for 48 hours. Five biological replicates were used for each condition.
2011-12-22 | E-GEOD-28672 | biostudies-arrayexpress
Project description:SON is a large Ser/Arg (SR)-related protein localized in nuclear speckles. SON siRNA causes defects in mitotic progression and genome instability. We used microarrays to detail the pattern of gene expression after SON knockdown.
2011-04-01 | GSE26888 | GEO
Project description:SON is a large Ser/Arg (SR)-related protein localized in nuclear speckles. SON siRNA causes defects in mitotic progression and genome instability. We used microarrays to detail the pattern of gene expression after SON knockdown. HeLa cells were grown in 100 mm dishes and transfected with negative control siRNA or SON siRNA (400 pmol). Then, cells were harvested after 66 hours and RNAs were isolated. Microarrays were performed using GeneChip Human Genome U133A 2.0 (Affymetrix).
2011-04-01 | E-GEOD-26888 | biostudies-arrayexpress
Project description:The nucleus of higher eukaryotes is a highly compartmentalized and dynamic organelle consisting of several biological condensates that regulate gene expression at multiple levels. First reported more than 100 years ago by Ramón y Cajal, nuclear speckles (NS) are among the most prominent of such condensates, which were independently rediscovered multiple times and are also known as interchromatin granule clusters (ICGs), splicing speckles, or SC35 domains. Despite their prevalence, research on the function of NS is virtually restricted to colocalization analyses, since an organizing core, without which NS cannot form, remains unidentified. The monoclonal antibody SC35, which was raised against a spliceosomal extract, is a frequently used reagent to mark NS since its debut in 1990. Despite its prolific use, and the consensus regarding its primary target as SRSF2, clear inconsistencies between observations made with mAb SC35, and transgenic SRSF2 constructs in the same experiment are noted. Intrigued by these disparities, we carried out a systematic re-characterization of this monoclonal antibody and its cellular targets. Unexpectedly, we found no evidence for SC35 mAb recognizing SRSF2 in human cells. In contrast, our results show that the 35 kDa namesake protein recognized by SC35 mAb is SRSF7, a related but distinct SR protein. More importantly, using mass-spectrometry, CRISPR-mediated knock-ins, immunoblotting and fluorescence microscopy, we show that the main target of SC35 mAb is SRRM2, a large (300 kDa), spliceosome-associated protein with prominent intrinsically disordered regions (IDRs) that sharply localizes to NS. Analysis of protein length evolution among metazoa revealed a peculiar IDR extension specifically for SRRM2 and SON in vertebrates, a hallmark of condensate formation. Combining these results, we tested a long-standing question in the study of NS: whether NS are formed around a specific core, or various SR-proteins self-assemble into a phase-separated compartment without the need for a defined core. Here we show that, the elusive core of NS is formed by SON and SRRM2, since depletion of SON leads only to a partial disassembly of NS, while combined depletion of SON together with SRRM2, but not other NS associated factors, or depletion of SON in a cell line where IDRs of SRRM2 are genetically deleted, leads to a near-complete dissolution of NS. This work, therefore, paves the way to study the role of NS under diverse physiological and stress conditions.
2020-10-26 | PXD021814 | Pride
Project description:Splicing is catalyzed by the spliceosome, a compositionally dynamic complex assembled stepwise on pre-mRNA. We reveal links between splicing machinery components and the intrinsically disordered ciliopathy protein SANS. Pathogenic mutations in SANS/USH1G lead to Usher syndrome––the most common cause of deaf-blindness. Previously, SANS was shown to function only in the cytosol and primary cilia. Here, we have uncovered molecular links between SANS and pre-mRNA splicing catalyzed by the spliceosome in the nucleus. We show that SANS is found in Cajal bodies and nuclear speckles, where it interacts with components of spliceosomal subcomplexes such as SF3B1 and the large splicing cofactor SON but also with PRPFs and snRNAs related to the tri-snRNP complex. SANS is required for the transfer of tri-snRNPs between Cajal bodies and nuclear speckles for spliceosome assembly and may also participate in snRNP recycling back to Cajal bodies. SANS depletion alters the kinetics of spliceosome assembly, leading to accumulation of complex A. SANS deficiency and USH1G pathogenic mutations affects splicing of genes related to cell proliferation and USH. Thus, we provide the first evidence that splicing dysregulation may participate in the pathophysiology of Usher syndrome.
2021-05-25 | PXD023942 | Pride
Project description:Control of the number of centrosomes is critical for cell division, trafficking and cilia. Regulation of centrosome number occurs through the precise duplication of centrioles that reside in the center of centrosomes. Here we explored transcriptional control of centriole assembly by focusing on alternative splicing factors in isolation from other cell cycle processes. Of five splicing factors originally identified as required for centriole assembly, only SON is specifically required. Procentriole assembly is severely disrupted when SON is reduced but early centriole assembly events still occur. Whole genome mRNA sequencing identified thousands of genes whose splicing and expression are affected by the reduction of SON, with an enrichment of genes involved in the microtubule cytoskeleton. SON is required for the proper splicing and expression of the centriolar satellite protein, CEP131. Fluorescence microscopy and electron tomography establish key differences to the trafficking and microtubule network around the centrosomes that contribute to the centriole assembly defects. This establishes SON as required for centriole assembly, partially through its activity in splicing CEP131 and through control of microtubules organized by the centrosome.
2021-12-22 | GSE164278 | GEO
Project description:Human embryonic stem cells (hESCs) harbor the ability to undergo lineage-specific differentiation into clinically relevant cell types. Transcription factors and epigenetic modifiers are known to play important roles in the maintenance of pluripotency of hESCs. However, little is known about regulation of pluripotency through splicing. In this study, we identify the spliceosome-associated factor SON as a novel factor essential for the maintenance of hESCs. Depletion of SON in hESCs results in the loss of pluripotency and cell death. Using genome-wide RNA profiling, we identified transcripts that are regulated by SON. Importantly, we confirmed that SON regulates the proper splicing of transcripts encoding for pluripotency regulators such as PRDM14, OCT4, E4F1 and MED24. Furthermore, we show that SON is bound to these transcripts in vivo. In summary, we connect a splicing-regulatory network for accurate transcription production to the maintenance of pluripotency and self-renewal of hESCs.
2013-08-29 | E-MTAB-1687 | biostudies-arrayexpress
Project description:The nucleus is highly organized such that factors involved in transcription and processing of distinct classes of RNA are organized within specific nuclear bodies. One example is the nuclear speckle, which is defined by high concentrations of protein and non-coding RNA regulators of pre-mRNA splicing. What functional role, if any, speckles might play in the process of mRNA splicing remains unknown. Here we show that genes localized near nuclear speckles display higher spliceosome concentrations, increased spliceosome binding to their pre-mRNAs, and higher co-transcriptional splicing levels relative to genes that are located farther from nuclear speckles. We show that directed recruitment of a pre-mRNA to nuclear speckles is sufficient to increase mRNA splicing levels. Finally, we show that gene organization around nuclear speckles is highly dynamic with differential localization between cell types corresponding to differences in splicing efficiency. Together, our results integrate the longstanding observations of nuclear speckles with the biochemistry of mRNA splicing and demonstrate a critical role for dynamic 3D spatial organization of genomic DNA in driving spliceosome concentrations and controlling the efficiency of mRNA splicing.
2024-03-22 | GSE247833 | GEO
Project description:Dysregulation of MLL complex-mediated histone methylation plays a pivotal role in gene expression associated with diseases, but little is known about cellular factors modulating MLL complex activity. Here, we report that SON, previously known as an RNA splicing factor, controls MLL complex-mediated transcriptional initiation. SON binds to DNA near transcription start sites, interacts with menin, and inhibits MLL complex assembly, resulting in decreased H3K4me3 and transcriptional repression. Importantly, alternatively spliced short isoforms of SON are markedly upregulated in acute myeloid leukemia. The short isoforms compete with full-length SON for chromatin occupancy, but lack the menin-binding ability, thereby antagonizing full-length SON function in transcriptional repression while not impairing full-length SON-mediated RNA splicing. Furthermore, overexpression of a short isoform of SON enhances replating potential of hematopoietic progenitors. Our findings define SON as a fine-tuner of the MLL-menin interaction and reveal short SON overexpression as a marker indicating aberrant transcriptional initiation in leukemia.
2016-03-24 | GSE76910 | GEO
Project description:We recently reported that serine-arginine-rich (SR) protein-mediated pre-mRNA structural remodeling generates a pre-mRNA 3D structural scaffold that is stably recognized by the early spliceosomal components. However, the intermediate steps between the free pre-mRNA and the assembled early spliceosome are not yet characterized. By probing the early spliceosomal complexes in vitro and RNA-protein interactions in vivo, we show that the SR proteins bind the pre-mRNAs cooperatively generating a substrate that recruits U1 snRNP and U2AF65 in a splice signal-independent manner. Excess U1 snRNP selectively displaces some of the SR protein molecules from the pre-mRNA generating the substrate for splice signal-specific, sequential recognition by U1 snRNP, U2AF65, and U2AF35. Our work thus identifies a novel function of U1 snRNP in mammalian splicing substrate definition, explains the need for excess U1 snRNP compared to other U snRNPs in vivo, demonstrates how excess SR proteins could inhibit splicing, and provides a conceptual basis to examine if this mechanism of splicing substrate definition is employed by other splicing regulatory proteins.
2022-07-05 | GSE188652 | GEO