NBS1 facilitates pre-ribosomal RNA biogenesis
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo Sapiens
SUBMITTER: 
Xiaochun Yu
PROVIDER: PXD061157 | iProX | Mon Feb 24 00:00:00 GMT 2025
REPOSITORIES: iProX
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Project description:Nucleolar ribosomal DNA (rDNA) repeats control ribosome manufacturing. rDNA harbors a ribosomal RNA (rRNA) gene and an intergenic spacer (IGS). RNA polymerase (Pol) I transcribes rRNA genes yielding the rRNA components of ribosomes. Pol II at the IGS induces rRNA production by preventing Pol I from excessively synthesizing IGS non-coding RNAs (ncRNAs) that can disrupt nucleoli. At the IGS, Pol II regulatory processes and whether Pol I function can be beneficial remain unknown. Here, we identify IGS Pol II regulators, uncovering nucleolar optimization via IGS Pol I. Compartment-enriched proximity-dependent biotin identification (compBioID) showed enrichment of the TATA-less promoter-binding TBPL1 and transcription regulator PAF1 with IGS Pol II. TBPL1 localizes to TCT motifs, driving Pol II and Pol I and maintaining its baseline ncRNA levels. PAF1 promotes Pol II elongation, preventing unscheduled R-loops that hyper-restrain IGS Pol I and its ncRNAs. PAF1 or TBPL1 deficiency disrupts nucleolar organization and rRNA biogenesis. In PAF1-deficient cells, repressing unscheduled IGS R-loops rescues nucleolar organization and rRNA production. Depleting IGS Pol I-dependent ncRNAs is sufficient to compromise nucleoli. We present the interactome of nucleolar Pol II and show its control by TBPL1 and PAF1 ensures IGS Pol I ncRNAs maintaining nucleolar structure and operation.
2024-10-09 | GSE261857 | GEO
Project description:Ribosome biogenesis is a highly regulated multistep process that controls cell growth and proliferation. The first and key regulatory step of ribosome biogenesis is represented by the transcription of ribosomal RNA (rRNA) genes by RNA polymerase (pol) I in the nucleolus. Activity of RNA pol I is tightly regulated by interactions with many auxiliary factors that mediate promoter recognition and contribute to transcription initiation, elongation and termination. In this study we were able to identify by mass spectrometry some of the known components of the RNA pol I transcribing machinery, and at the same time we identify some novel interactors.
2020-05-06 | PXD018143 | Pride
Project description:Ribosome biogenesis is a fundamental process required for all cellular activities. Histone deacetylases play critical roles in many biological processes including transcriptional repression and rDNA silencing. However, their function in pre-rRNA processing remains poorly understood. Here, we discovered a previously uncharacterized role of Arabidopsis histone deacetylase HD2C in pre-rRNA processing via both canonical and non-canonical manners. HD2C interacts with HD2B and forms homo- and/or hetero-oligomers in the nucleolus. Depletion of HD2C and HD2B induces a ribosome biogenesis deficiency morphological phenotype and aberrant accumulation of 18S pre-rRNA intermediates. Our genome-wide analysis revealed that HD2C binds and represses the expression of key genes involved in ribosome biogenesis. Using RNA immunoprecipitation and sequencing, we further uncovered a non-canonical mechanism of HD2C directly associating with pre-rRNA and small nucleolar RNAs to regulate rRNA methylation. Together, this study reveals a multifaceted role of HD2C in ribosome biogenesis and provides mechanistic insights into how histone deacetylases modulate rRNA maturation at both transcriptional and post-transcriptional levels.
2018-03-01 | GSE107883 | GEO
Project description:The RNA exosome is an essential 3’ to 5’ processing exoribonuclease complex that mediates degradation, processing, and quality control of virtually all eukaryotic RNAs. The nucleolar RNA exosome, consisting of a 9-subunit core and a distributive 3ʹ to 5ʹ exonuclease EXOSC10, plays a critical role in processing and degrading nucleolar RNAs, including pre-ribosomal RNA (pre-rRNA). However, how the RNA exosome is regulated in the nucleolus is poorly understood. Here, we report that the nucleolar ubiquitin-specific protease USP36 is a novel regulator of the nucleolar RNA exosome. USP36 binds to the RNA exosome through direct interaction with EXOSC10. Interestingly, USP36 does not significantly regulate the levels of EXOSC10 and other exosome subunits. Instead, it mediates EXOSC10 SUMOylation at Lys (K) 583. Mutating K583 impaired the binding of EXOSC10 to pre-rRNAs and the K583R mutant failed to rescue the defects in rRNA processing and cell growth inhibition caused by knockdown of endogenous EXOSC10, indicating that EXOSC10 SUMOylation is critical for the exosome function in rRNA processing. Furthermore, USP36 itself is a rRNA-binding protein that associates pre-rRNA. These results suggest that USP36 acts as a novel SUMO ligase to mediate EXOSC10 SUMOylation critical for the RNA exosome function in rRNA processing and ribosome biogenesis.
2023-07-20 | PXD031592 | Pride
Project description:Circular RNAs (circRNAs) are broadly expressed in eukaryotic cells, but their role in human health and disease remains obscure. Here, we show that circular antisense non-coding RNA in the INK4 locus (circANRIL), which is transcribed at a locus of atherosclerotic cardiovascular disease on chromosome 9p21, confers athero-protection by controlling ribosomal RNA (rRNA) maturation and modulating pathways of atherogenesis. At the molecular level, circANRIL competes with precursor rRNA (pre-rRNA) for binding to pescadillo homolog 1 (PES1), an essential 60S-preribosomal assembly factor, thereby impairing exonuclease-mediated pre-rRNA processing and ribosome biogenesis. As a consequence, circANRIL induces nucleolar stress and p53 activation, resulting in the induction of apoptosis and inhibition of proliferation, which are key athero-protective cell functions within the arterial wall. Collectively, these findings identify circANRIL as a prototype of a circRNA regulating ribosome biogenesis and conferring athero-protection, thereby unveiling a therapeutic potential of certain circRNAs in human disease.
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Project description:The nucleolus composes hundreds of proteins that play distinct roles in ribosomal RNA (rRNA) processing within Fibrillar Center/Dense Fibrillar Component (FC/DFC) units and ribosome assembly in Granular Component (GC). The sub-nucleolar localization of most proteins and how their unique localization facilitates rRNA processing have remained elusive. By screening 200 nucleolar candidate proteins with high-resolution, live-cell microscopy, we identified a previously undescribed sub-nucleolar compartment, named the periphery of DFC (PDFC). Among the 12 proteins identified in PDFC, URB1 (unhealthy ribosome biogenesis 1) is required for PDFC organization and proper 3' end processing of 47S pre-rRNA. URB1 binds between the 28S rRNA and the 3' external transcribed spacer (3' ETS) to ensure 3' ETS removal, which occurs at the DFC/PDFC boundary. Loss of URB1 leads to accumulation of aberrant 3' ETS-retained 32S pre-rRNA variants, which activates exosome-dependent nucleolar surveillance. This causes decreased 28S rRNA production, reduced cell proliferation and retarded mouse embryonic pre-implementation development. Furthermore, urb1 depletion results in developmental craniofacial disorder in zebrafish, which can be at least partially rescued by further depleting exosome components. Together, this study provides new insights into functional sub-nucleolar organizations, identifies a physiologically essential step in rRNA maturation and emphasizes the exosome-dependent pre-rRNA surveillance pathway.
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Project description:The nucleolus composes hundreds of proteins that play distinct roles in ribosomal RNA (rRNA) processing within Fibrillar Center/Dense Fibrillar Component (FC/DFC) units and ribosome assembly in Granular Component (GC). The sub-nucleolar localization of most proteins and how their unique localization facilitates rRNA processing have remained elusive. By screening 200 nucleolar candidate proteins with high-resolution, live-cell microscopy, we identified a previously undescribed sub-nucleolar compartment, named the periphery of DFC (PDFC). Among the 12 proteins identified in PDFC, URB1 (unhealthy ribosome biogenesis 1) is required for PDFC organization and proper 3' end processing of 47S pre-rRNA. URB1 binds between the 28S rRNA and the 3' external transcribed spacer (3' ETS) to ensure 3' ETS removal, which occurs at the DFC/PDFC boundary. Loss of URB1 leads to accumulation of aberrant 3' ETS-retained 32S pre-rRNA variants, which activates exosome-dependent nucleolar surveillance. This causes decreased 28S rRNA production, reduced cell proliferation and retarded mouse embryonic pre-implementation development. Furthermore, urb1 depletion results in developmental craniofacial disorder in zebrafish, which can be at least partially rescued by further depleting exosome components. Together, this study provides new insights into functional sub-nucleolar organizations, identifies a physiologically essential step in rRNA maturation and emphasizes the exosome-dependent pre-rRNA surveillance pathway.
2023-01-04 | GSE196625 | GEO
Project description:During ribosome biogenesis a plethora of assembly factors and essential enzymes drive the unidirectional maturation of nascent pre-ribosomal subunits. The DEAD-box RNA helicase Dbp10 is suggested to restructure pre-ribosomal rRNA of the evolving peptidyl-transferase center (PTC) on nucleolar ribosomal 60S assembly intermediates. Here, we show that point mutations within conserved catalytic helicase-core motifs of Dbp10 yield a dominant-lethal growth phenotype. Such dbp10 mutants, which stably associate with pre-60S intermediates, impair pre-60S biogenesis at a nucleolar stage prior to the release of assembly factor Rrp14 and stable integration of late nucleolar factors such as Noc3. Furthermore, the binding of the GTPase Nug1 to particles isolated directly via mutant Dbp10 bait proteins is specifically inhibited. The N-terminal domain of Nug1 interacts with Dbp10 and the methyltransferase Spb1, whose pre-60S incorporation is also reduced in absence of functional Dbp10. Our data suggest that Dbp10’s helicase activity generates a crucial framework for assembly factor docking thereby permitting the progression of pre-60S maturation
2024-05-22 | PXD046068 | Pride
Project description:Circular RNAs (circRNAs) are broadly expressed in eukaryotic cells, but their role in human health and disease remains obscure. Here, we show that circular antisense non-coding RNA in the INK4 locus (circANRIL), which is transcribed at a locus of atherosclerotic cardiovascular disease on chromosome 9p21, confers athero-protection by controlling ribosomal RNA (rRNA) maturation and modulating pathways of atherogenesis. At the molecular level, circANRIL competes with precursor rRNA (pre-rRNA) for binding to pescadillo homolog 1 (PES1), an essential 60S-preribosomal assembly factor, thereby impairing exonuclease-mediated pre-rRNA processing and ribosome biogenesis. As a consequence, circANRIL induces nucleolar stress and p53 activation, resulting in the induction of apoptosis and inhibition of proliferation, which are key athero-protective cell functions within the arterial wall. Collectively, these findings identify circANRIL as a prototype of a circRNA regulating ribosome biogenesis and conferring athero-protection, thereby unveiling a therapeutic potential of certain circRNAs in human disease. Analysis of transcriptome-wide expression level in HEK293 cells with stable overexpression of circular ANRIL (n=3) compared to a vector control (n=3).
2016-08-22 | E-GEOD-65392 | biostudies-arrayexpress
Project description:Myriad of craniofacial disorders are caused by heterozygous mutations in general regulators of housekeeping cellular functions such as ribosome biogenesis. While it is understood that many of these highly tissue-specific malformations are a consequence of defects in cranial neural crest cells (cNCCs), an embryonic cell group that gives rise to most of the facial structures during embryogenesis, the mechanism underlying cell type-selectivity of these effects remains largely unknown. Here we show that DDX21, a DEAD-box RNA helicase involved in control of both RNA polymerase (Pol) I and Pol II dependent transcriptional arms of ribosome biogenesis, is a key mediator of the nucleolar stress response. Using an in vitro model of Treacher Collins Syndrome (TCS), a craniofacial disorder caused by heterozygous mutations in components of the Pol I transcriptional machinery, we demonstrate that perturbations in ribosomal RNA (rRNA) transcription induce DDX21-mediated surveillance mechanism in cNCCs, leading to DDX21 relocalization from the nucleolus to the nucleoplasm, its eviction from Pol I and Pol II chromatin targets and inhibition of rRNA processing. Importantly, these effects are cell type-selective, cell-autonomous and involve activation of the p53 pathway. We further show that cNCCs are characterized by the inherently high reservoir of p53 mRNA and sensitivity to p53-mediated apoptosis. Remarkably, preventing the loss of DDX21 from nucleolus and chromatin can rescue both the sensitivity to apoptosis and TCS-associated craniofacial phenotypes in vivo. This mechanism is not restricted to TCS, as gene function perturbations linked to other ribosomopathies with craniofacial manifestations also lead to the activation of DDX21 surveillance. Lastly, we provide evidence that inhibition of rRNA synthesis leads to rDNA damage, and furthermore, that rDNA damage is sufficient to activate DDX21 surveillance and elicits tissue-selective and dosage-dependent effects on craniofacial development in vivo.
2018-02-01 | GSE89420 | GEO