The human U5 snRNP assembly factor, AAR2, regulates gene expression dependent on the PRPF8 protein
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA758575 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:Small nuclear ribonucleoprotein complexes (snRNPs) represent the main subunits of the spliceosome. While the assembly of snRNP core particles has been well characterized, the incorporation of snRNP-specific proteins and the mechanisms of snRNP recycling after splicing are less well characterized. Furthermore, little is known about how targeted down-regulation of snRNP assembly factors impacts gene expression. U5 snRNP assembly in yeast requires the Aar2 protein, but the role of the human AAR2 homolog has not yet been investigated in detail. Here, we report a crystal structure of human AAR2 in complex with the RNase H-like domain of the U5-specific PRPF8 protein and in vitro interaction studies of AAR2 with U5 proteins, revealing similarities and differences in the interaction patterns compared to yeast Aar2p. Based on the structure, we probed the importance of interacting regions and residues, and designed AAR2 variants that failed to stably bind PRPF8 in vitro. SiRNA-mediated aar2 knock-down affected the expression levels of many genes. These effects were reversed by expressing siRNA-resistant PRPF8-binding AAR2 variants, but not by a phospho-mimetic AAR2 variant defective in PRPF8 binding. Our results reveal an unexpected role of an snRNP assembly factor in adjusting gene expression levels.
2025-08-16 | GSE182977 | GEO
Project description:U1 snRNP plays an essential role in initiating spliceosome assembly, yet the mechanism underlying its synergy with other splicing regulators for efficient spliceosome assembly remains elusive. Here we identify ZFP207 as a key regulator of U1 snRNP function that substantially promotes spliceosome assembly. Acute depletion of ZFP207 results in a series of molecular phenotypes indicative of U1 snRNP dysregulation. Mechanistically, the N-terminal zinc finger domains of ZFP207 directly bind to the stem-loop 3 (SL3) of U1 snRNA, while its C-terminal intrinsically disordered regions (IDRs) undergo phase separation to form biomolecular condensates with U1 snRNP. These condensates create a crowded molecular environment that increases the local concentration of splicing snRNPs and regulators, thereby accelerating the speed of spliceosome assembly by facilitating interactions between U1 snRNP and other snRNPs. Collectively, our study demonstrates the critical role of phase separation in ensuring effective U1 snRNP function and promoting efficient spliceosome assembly.
2024-12-30 | GSE249424 | GEO
Project description:Histone mRNAs are the only non-polyadenylated mRNAs in eukaryotic cells and require specialized processing in nuclear organelles known as histone locus bodies (HLBs), where essential processing factors are concentrated, including the U7 snRNP complex. Recent studies have revealed that misregulation of histone pre-mRNA processing can lead to polyadenylation of histone mRNAs and disruption of histone protein homeostasis. Despite the links to human disease, the factors contributing to polyadenylation of histone mRNAs and the mechanisms underlying HLB assembly and U7 snRNP biogenesis remain unclear. Here, we report novel functions of the small ubiquitin-related modifier 2 (SUMO2) in regulating histone pre-mRNA processing. Using a SUMO2 knockout osteosarcoma cell line, we identified a defect in 3’ end cleavage and a global increase in histone mRNA polyadenylation. Subsequent analysis of HLBs revealed increased dynamics and reduced levels of the U7 snRNP complex. By over-expressing U7 snRNP-specific components, Lsm11 and U7 snRNA, we partially rescued U7 snRNP levels and processing defects in SUMO2 knockout cells. Through analysis of Lsm11, we identified a SUMO-interacting motif in its N-terminus required for efficient incorporation into U7 snRNP complexes. Collectively, we demonstrate that SUMO2 promotes histone pre-mRNA 3’ end processing through stabilizing HLB interactions and facilitating U7 snRNP assembly
2025-03-29 | GSE292809 | GEO
Project description:Splicing is catalyzed by the spliceosome, a complex of five major small nuclear ribonucleoprotein particles (snRNPs). The pre-mRNA splicing factor PRPF8 is a crucial component of the U5 snRNP, and together with EFTUD2 and SNRNP200, it forms a central module of the spliceosome. Using quantitative proteomics, we identified assembly intermediates containing PRPF8, EFTUD2, and SNRNP200 in association with the HSP90/R2TP complex, its ZNHIT2 cofactor, and additional proteins. HSP90 and R2TP bind unassembled U5 proteins in the cytoplasm, stabilize them, and promote the formation of the U5 snRNP. We further found that PRPF8 mutants causing Retinitis pigmentosa assemble less efficiently with the U5 snRNP and bind more strongly to R2TP, with one mutant retained in the cytoplasm in an R2TP-dependent manner. We propose that the HSP90/R2TP chaperone system promotes the assembly of a key module of U5 snRNP while assuring the quality control of PRPF8. The proteomics data further reveal new interactions between R2TP and the tuberous sclerosis complex (TSC), pointing to a potential link between growth signals and the assembly of key cellular machines.
| S-EPMC5461031 | biostudies-literature
Project description:U1 snRNP plays an essential role in initiating spliceosome assembly, yet the mechanism underlying its synergy with other splicing regulators for efficient spliceosome assembly remains elusive. Here we identify ZFP207 as a key regulator of U1 snRNP function that substantially promotes spliceosome assembly. Acute depletion of ZFP207 largely recapitulates the molecular phenotypes observed with the depletion of SNRNP70, a core component of U1 snRNP. Mechanistically, the N-terminal zinc finger domains of ZFP207 directly bind to U1 snRNA, while its C-terminus undergoes phase separation via intrinsically disordered regions (IDRs) to forms biomolecular condensates with U1 snRNP. These condensates create a crowded molecular environment that increases the local concentration of splicing snRNPs and regulators, thereby accelerating the speed of spliceosome assembly by facilitating interactions between U1 snRNP and other snRNPs. Collectively, our study demonstrates the critical role of phase separation in ensuring proper U1 snRNP function and efficient spliceosome assembly.
2024-12-30 | GSE275020 | GEO
Project description:U1 snRNP plays an essential role in initiating spliceosome assembly, yet the mechanism underlying its synergy with other splicing regulators for efficient spliceosome assembly remains elusive. Here we identify ZFP207 as a key regulator of U1 snRNP function that substantially promotes spliceosome assembly. Acute depletion of ZFP207 largely recapitulates the molecular phenotypes observed with the depletion of SNRNP70, a core component of U1 snRNP. Mechanistically, the N-terminal zinc finger domains of ZFP207 directly bind to U1 snRNA, while its C-terminus undergoes phase separation via intrinsically disordered regions (IDRs) to forms biomolecular condensates with U1 snRNP. These condensates create a crowded molecular environment that increases the local concentration of splicing snRNPs and regulators, thereby accelerating the speed of spliceosome assembly by facilitating interactions between U1 snRNP and other snRNPs. Collectively, our study demonstrates the critical role of phase separation in ensuring proper U1 snRNP function and efficient spliceosome assembly.
2024-12-30 | GSE273461 | GEO
Project description:Transcription and splicing are intricately linked processes, with emerging evidence highlighting the involvement of splicing factors mediating their coupling. U1 small nuclear ribonucleoprotein particle (U1 snRNP), a key splicing factor, not only serves as the initial component of the spliceosome but also plays a crucial role in preventing premature cleavage and polyadenylation, facilitating long-distance transcription elongation. Here, we show that U1 snRNP regulates alternative promoter usage through inhibition of premature polyadenylation. Inhibiting U1 snRNP with antisense oligonucleotides or introducing a premature polyadenylation leads to a significant decrease in downstream promoter activity in genes with premature polyadenylation sites in between two promoters. Conversely, restoring U1 snRNP activity or inhibiting premature polyadenylation sites using a gene-specific U1 snRNP rescues downstream promoter activity. Mechanistically, U1 snRNP inhibition correlates with reduced chromatin accessibility and serine 5 phosphorylation levels of RNA polymerase II at downstream promoters. Our findings propose a model where U1 snRNP facilitates productive transcription from upstream promoters, triggering downstream promoter activation by destabilizing nucleosomes and promoting promoter escape.
2025-05-19 | GSE284680 | GEO
Project description:Small nuclear ribonucleoprotein complexes (snRNPs) represent the main subunits of the spliceosome. While the assembly of the snRNP core particles has been well characterized, comparably little is known of the incorporation of snRNP-specific proteins and the mechanisms of snRNP recycling. U5 snRNP assembly in yeast requires binding of the the Aar2 protein to Prp8p as a placeholder to preclude premature assembly of the SNRNP200 helicase, but the role of the human AAR2 homolog has not yet been investigated in detail. Here, a crystal structure of human AAR2 in complex with the RNase H-like domain of the U5-specific PRPF8 (PRP8F RH) is reported, revealing a significantly different interaction between the two proteins compared with that in yeast. Based on the structure of the AAR2-PRPF8 RH complex, the importance of the interacting regions and residues was probed and AAR2 variants were designed that failed to stably bind PRPF8 in vitro. Protein-interaction studies of AAR2 with U5 proteins using size-exclusion chromatography reveal similarities and marked differences in the interaction patterns compared with yeast Aar2p and imply phosphorylation-dependent regulation of AAR2 reminiscent of that in yeast. It is found that in vitro AAR2 seems to lock PRPF8 RH in a conformation that is only compatible with the first transesterification step of the splicing reaction and blocks a conformational switch to the step 2-like, Mg2+-coordinated conformation that is likely during U5 snRNP biogenesis. These findings extend the picture of AAR2 PRP8 interaction from yeast to humans and indicate a function for AAR2 in the spliceosomal assembly process beyond its role as an SNRNP200 placeholder in yeast.
| S-EPMC9629490 | biostudies-literature
Project description:We compared the transcriptome of cerebellar tissues gained from 4 weeks old mice that carry either the Prpf8Y2334N or Prpf8Δ17 mutant variant of splicing factor Prpf8. In both RNA-Seq runs, homozygous animals were analysed along with wt controls (both genders).
2023-03-31 | E-MTAB-10753 | biostudies-arrayexpress
Project description:Transcription and splicing are inherently intertwined. Accumulating evidence support a role of splicing factors in mediating this coupling. U1 small nuclear ribonucleoprotein particle (U1 snRNP), a key splicing factor, acts as the initial building block of the spliceosome, interacting with nascent pre-mRNA at 5' splice sites. In addition to its role in splicing, U1 snRNP is crucial for preventing premature cleavage and polyadenylation, enabling long-distance transcription elongation. Here, we show that U1 snRNP can regulate the usage of alternative promoters through its role in inhibiting premature polyadenylation. Using antisense oligonucleotides to inhibit U1 snRNP, we first observed a markedly decrease in downstream promoter activity at the newly synthesized RNA level. Interestingly, U1 snRNP inhibition selectively impacts downstream promoters of genes featuring premature polyadenylation sites located between two promoters. Overexpressing a wild-type U1 snRNP or a gene-specific U1 snRNP designed to inhibit premature polyadenylation sites restores downstream promoter activity. Conversely, introducing a premature polyadenylation site between two promoters reduces downstream promoter activity. Exploring the underlying molecular mechanisms, we identified a substantial decrease in serine 5 phosphorylation levels in newly recruited RNA polymerase II at downstream promoters following U1 snRNP inhibition, and reduced chromatin accessibility in the vicinity of downstream promoters. Overall, our model is consistent with productive transcription from upstream promoters triggering downstream promoter activation in the presence of U1 snRNP by destabilizing nucleosomes and promoting promoter escape at downstream promoters.
2025-05-19 | GSE252389 | GEO