Project description:UBL5 is an atypical ubiquitin-like protein, whose function in metazoans remains largely unexplored. We show that UBL5 is required for sister chromatid cohesion maintenance in human cells. UBL5 primarily associates with spliceosomal proteins, and UBL5 depletion decreases pre-mRNA splicing efficiency, leading to globally enhanced intron retention. Defective sister chromatid cohesion is a general consequence of dysfunctional pre-mRNA splicing, resulting from the selective downregulation of the cohesion protection factor Sororin. As the UBL5 yeast orthologue, Hub1, also promotes spliceosome functions, our results show that UBL5 plays an evolutionary conserved role in pre-mRNA splicing, the integrity of which is essential for the fidelity of chromosome segregation.
Project description:UBL5 is an atypical ubiquitin-like protein, whose function in metazoans remains largely unexplored. We show that UBL5 is required for sister chromatid cohesion maintenance in human cells. UBL5 primarily associates with spliceosomal proteins, and UBL5 depletion decreases pre-mRNA splicing efficiency, leading to globally enhanced intron retention. Defective sister chromatid cohesion is a general consequence of dysfunctional pre-mRNA splicing, resulting from the selective downregulation of the cohesion protection factor Sororin. As the UBL5 yeast orthologue, Hub1, also promotes spliceosome functions, our results show that UBL5 plays an evolutionary conserved role in pre-mRNA splicing, the integrity of which is essential for the fidelity of chromosome segregation. Total RNA was extracted from HeLa cells treated with control (CTRL), UBL5 (#57, #58, or #82), or SART1 siRNAs for 48 h and processed for RNA-Seq analysis
Project description:Although splicing is essential for the expression of most eukaryotic genes, inactivation of splicing factors causes specific defects in mitosis. The molecular cause of this defect is unknown. Here we show that the spliceosome subunits SNW1 and PRPF8 are essential for sister chromatid cohesion in human cells. A transcriptome-wide analysis revealed that SNW1 or PRPF8 depletion affects the splicing of specific introns in a subset of pre-mRNAs, including pre-mRNAs encoding the cohesion protein sororin and the APC/C subunit APC2. SNW1 depletion causes cohesion defects predominantly by reducing sororin levels, which causes destabilisation of cohesin on DNA. SNW1 depletion also reduces APC/C activity and contributes to cohesion defects indirectly by delaying mitosis and causing ‘cohesion fatigue’. Simultaneous expression of sororin and APC2 from intron-less cDNAs restores cohesion in SNW1 depleted cells. These results indicate that the spliceosome is required for mitosis because it enables expression of genes essential for cohesion. Our transcriptome-wide identification of retained introns in SNW1 and PRPF8 depleted cells may help to understand the aetiology of diseases associated with splicing defects, such as retinosa pigmentosum and cancer.
Project description:Although splicing is essential for the expression of most eukaryotic genes, inactivation of splicing factors causes specific defects in mitosis. The molecular cause of this defect is unknown. Here we show that the spliceosome subunits SNW1 and PRPF8 are essential for sister chromatid cohesion in human cells. A transcriptome-wide analysis revealed that SNW1 or PRPF8 depletion affects the splicing of specific introns in a subset of pre-mRNAs, including pre-mRNAs encoding the cohesion protein sororin and the APC/C subunit APC2. SNW1 depletion causes cohesion defects predominantly by reducing sororin levels, which causes destabilisation of cohesin on DNA. SNW1 depletion also reduces APC/C activity and contributes to cohesion defects indirectly by delaying mitosis and causing ‘cohesion fatigue’. Simultaneous expression of sororin and APC2 from intron-less cDNAs restores cohesion in SNW1 depleted cells. These results indicate that the spliceosome is required for mitosis because it enables expression of genes essential for cohesion. Our transcriptome-wide identification of retained introns in SNW1 and PRPF8 depleted cells may help to understand the aetiology of diseases associated with splicing defects, such as retinosa pigmentosum and cancer.
Project description:Cohesion between sister chromatids depends on the chromosomal cohesin complex and allows the spindle apparatus in mitosis to recognize replicated chromosomes for segregation into daughter cells. Sister chromatid cohesion is established concomitant with DNA replication, and requires the essential Eco1 protein, a replication fork-associated acetyl transferase. The mechanism by which Eco1 establishes sister chromatid cohesion is not known. Here, we show that the cohesin subunit Smc3 is acetylated in an Eco1-dependent manner during S phase to establish sister chromatid cohesion. We isolated spontaneous suppressors of the thermosensitive eco1-1 allele in budding yeast, and identified the suppressor mutations from the hybridization pattern of genomic DNA on oligonucleotide tiling arrays. An acetylation mimicking mutation of a conserved lysine in Smc3 to asparagine (K113N) makes Eco1 dispensable for cell growth, indicating that Smc3 acetylation is Eco1’s only essential function. We identified a second set of eco1-1 suppressor mutations in the budding yeast ortholog of the cohesin regulator Wapl (Wpl1/Rad61). Wapl destabilizes cohesin on chromosomes, and Eco1-dependent Smc3 acetylation during S-phase might render cohesin resistant to Wapl. Our results clarify the role of Eco1 in the establishment of sister chromatid cohesion, and suggest that Eco1 modifies cohesin to stabilize an Eco1-independent cohesion establishment reaction.
Project description:Long noncoding RNAs (lncRNAs) have appeared to be involved in the most diverse cellular processes through multiple mechanisms. Here we describe a previously uncharacterized human lncRNA, CONCR (cohesion regulator noncoding RNA), transcriptionally activated by MYC, which is upregulated in multiple cancer types. The expression of CONCR is cell cycle-regulated, and it is required for cell cycle progression and DNA replication. Moreover, cells depleted of CONCR show severe defects in sister chromatid cohesion, suggesting an essential role for CONCR in cohesion establishment during cell division. CONCR interacts with and regulates the activity of DDX11, a DNA-dependent ATPase and helicase involved in DNA replication. These findings suggest a novel mechanism of action for CONCR in the modulation of DDX11 enzymatic activity, unveiling the direct involvement of a lncRNA in the establishment of sister chromatid cohesion. Characterization of the function of the long noncoding RNA CONCR. HCT116 p53-/- cells were left untreated (0h) or treated with the DNA damaging drug 5-FU for 4h and 12h.
Project description:Long noncoding RNAs (lncRNAs) have appeared to be involved in the most diverse cellular processes through multiple mechanisms. Here we describe a previously uncharacterized human lncRNA, CONCR (cohesion regulator noncoding RNA), transcriptionally activated by MYC, which is upregulated in multiple cancer types. The expression of CONCR is cell cycle-regulated, and it is required for cell cycle progression and DNA replication. Moreover, cells depleted of CONCR show severe defects in sister chromatid cohesion, suggesting an essential role for CONCR in cohesion establishment during cell division. CONCR interacts with and regulates the activity of DDX11, a DNA-dependent ATPase and helicase involved in DNA replication. These findings suggest a novel mechanism of action for CONCR in the modulation of DDX11 enzymatic activity, unveiling the direct involvement of a lncRNA in the establishment of sister chromatid cohesion. Characterization of the function of the long noncoding RNA CONCR. Analysis of DDX11 chromatin binding by ChIP-seq in the presence or absence of CONCR.
Project description:Sister chromatid cohesion, established during replication by the protein complex Cohesin, is essential for both chromosome segregation and double-strand break (DSB) repair. Normally cohesion formation is strictly limited to the S-phase of the cell cycle, but DSBs can trigger cohesion also after DNA replication has been completed. The function of this damage-induced cohesion remains unknown. In this investigation we show that it is essential for repair in post-replicative cells in yeast. Furthermore, it is established genome-wide after induction of a single DSB, and controlled by the DNA damage response and Cohesin regulating factors. We thus define a cohesion establishment pathway that is independent of DNA duplication and acts together with cohesion formed during replication in sister chromatid-based DSB repair. Keywords: ChIP-chip analysis
Project description:Long noncoding RNAs (lncRNAs) have appeared to be involved in the most diverse cellular processes through multiple mechanisms. Here we describe a previously uncharacterized human lncRNA, CONCR (cohesion regulator noncoding RNA), transcriptionally activated by MYC, which is upregulated in multiple cancer types. The expression of CONCR is cell cycle-regulated, and it is required for cell cycle progression and DNA replication. Moreover, cells depleted of CONCR show severe defects in sister chromatid cohesion, suggesting an essential role for CONCR in cohesion establishment during cell division. CONCR interacts with and regulates the activity of DDX11, a DNA-dependent ATPase and helicase involved in DNA replication. These findings suggest a novel mechanism of action for CONCR in the modulation of DDX11 enzymatic activity, unveiling the direct involvement of a lncRNA in the establishment of sister chromatid cohesion.