| 1992 |
Nopp140 is a nucleolar phosphoprotein that shuttles between the nucleolus and cytoplasm on tracks revealed by immunoelectron microscopy, extending from the dense fibrillar component of the nucleolus across the nucleoplasm to nuclear pore complexes. It was identified as a nuclear localization signal (NLS)-binding protein whose NLS binding is dependent on phosphorylation. It is phosphorylated to an unusually high degree, with a 10-fold repeated motif containing casein kinase II (CK2) consensus sites. |
Immunoelectron microscopy, subcellular fractionation, biochemical characterization, pulse-chase shuttling assay |
Cell |
High |
1623516
|
| 1996 |
Casein kinase II (CK2) phosphorylates Nopp140 to its unusually high degree in vertebrates; the yeast homolog SRP40 is also phosphorylated by CK2 but to a much lesser extent. SRP40 localizes to the yeast nucleolus and is required at a specific cellular concentration for optimal growth. |
In vitro kinase assay, immunological characterization, yeast growth assays (overexpression and deletion) |
The Journal of biological chemistry |
High |
8702624
|
| 1997 |
Nopp140 interacts directly with the CK2 regulatory beta subunit; the NH2-terminal 20 amino acids of CK2beta mediate binding to Nopp140. Co-immunoprecipitation confirmed in vivo association of Nopp140 with CK2. |
GST pulldown with immobilized CK2 fusion proteins, co-immunoprecipitation, overlay technique with radiolabeled CK2, deletion mutant mapping |
The Journal of biological chemistry |
High |
9013635
|
| 1997 |
Nopp140 functions as a transcriptional coactivator: it interacts with AGP/EBP (C/EBP beta) to synergistically activate the alpha-1 acid glycoprotein (AGP) gene, and independently interacts with TFIIB. Distinct regions of Nopp140 mediate interactions with AGP/EBP and TFIIB, and this physical interaction with TFIIB correlates with transcriptional activation ability. |
Immunoaffinity chromatography, co-immunoprecipitation, deletion mutant analysis, transcriptional reporter assays |
Molecular and cellular biology |
Medium |
8972203
|
| 1998 |
Nopp140 functions as a molecular link between the nucleolus and coiled bodies (Cajal bodies): its alternating positively and negatively charged repeat domain is required for targeting to both organelles. Nopp140 directly interacts with the coiled body-specific protein p80 coilin, as identified by yeast two-hybrid screening and confirmed by co-immunoprecipitation. Dominant-negative Nopp140 constructs chase endogenous Nopp140 and shared antigens out of the nucleolus. |
Yeast two-hybrid screen, co-immunoprecipitation, transient transfection with dominant-negative constructs, mutational analysis |
The Journal of cell biology |
High |
9679133
|
| 1999 |
Human Nopp140 (hNopp140) interacts with the largest subunit of RNA polymerase I (RPA194); this interaction is mediated through amino acids 204–382 of hNopp140. Expression of a dominant-negative hNopp140N382 (aa 1–382) mislocalizes endogenous RNA Pol I and shuts off rDNA transcription, establishing an essential role for Nopp140 in rDNA transcription. |
Co-immunoprecipitation, double immunofluorescence, in situ run-on transcription assay, dominant-negative transfection with deletion mapping |
Molecular and cellular biology |
High |
10567578
|
| 2000 |
Nopp140 interacts with both box H/ACA snoRNPs (containing NAP57/dyskerin) and box C/D snoRNPs (containing NAP65/Nop5/58p) via co-immunoprecipitation. Dominant-negative Nopp140 depletes snoRNP proteins from nucleoli in vivo, and this depletion arrests RNA Pol I transcription. In yeast, depletion of the Nopp140 homolog Srp40p causes loss of box H/ACA snoRNAs. |
Co-immunoprecipitation, dominant-negative transfection, yeast conditional lethal depletion strain, northern blotting |
Molecular biology of the cell |
High |
10679015
|
| 2001 |
Exogenous expression of the repeat domain of Nopp140 induces formation of intranuclear endoplasmic reticulum stacks (R-rings) derived from the inner nuclear membrane; Nopp140 localizes directly to the electron-dense matrix in which these membrane stacks are embedded, demonstrating a direct role for Nopp140 in generating this intranuclear membrane structure. |
Transmission electron microscopy, immunofluorescence, subcellular fractionation, exogenous expression of Nopp140 constructs |
Journal of cell science |
Medium |
11739657
|
| 2002 |
Immunopurified box H/ACA snoRNP core particles (NAP57, GAR1, NHP2, NOP10) are sufficient for rRNA pseudouridylation in vitro. Although snoRNPs associate quantitatively and reversibly with Nopp140, pseudouridylation activity is independent of Nopp140 association, consistent with a chaperoning rather than catalytic role for Nopp140. |
In vitro pseudouridylation assay with immunopurified snoRNPs, thin-layer chromatography, 32P-labeled rRNA substrates |
Molecular and cellular biology |
High |
12446766
|
| 2002 |
Nopp140 mediates protein kinase A (PKA) signaling to activate the AGP gene: PKA-dependent phosphorylation of Nopp140, together with C/EBPbeta, synergistically induces agp gene expression. Nopp140 mutants defective in PKA phosphorylation sites lose this transcriptional activation ability, and maximum activation also requires CREB and C/EBPbeta. |
Transcriptional reporter assays, PKA inhibitor (PKI) experiments, site-directed mutagenesis of PKA phosphorylation sites, co-transfection assays |
The Journal of biological chemistry |
Medium |
12167624
|
| 2008 |
Nopp140 specifically binds to the catalytic subunit of CK2 (CK2alpha) with a dissociation constant of ~4 nM and inhibits CK2 catalytic activity. The C-terminal region of Nopp140 contains the CK2alpha-binding region. IP6 (inositol hexakisphosphate) specifically binds to CK2alpha and disrupts the Nopp140-CK2alpha interaction (IC50 ~25 µM), thereby relieving Nopp140-mediated inhibition of CK2. |
Surface plasmon resonance (quantitative binding assay), yeast two-hybrid, CK2 activity assays, deletion mutant mapping |
Biochemical and biophysical research communications |
High |
18790693
|
| 2009 |
SMN (survival motor neuron protein) is required for accumulation of Nopp140 in Cajal bodies: SMN knockdown decreases Nopp140 in CBs, while SMN overexpression in SMA cells restores CB localization of Nopp140. SMA patient-derived SMN mutants fail to promote Nopp140 association with CBs. |
RNA interference knockdown of SMN, overexpression of wild-type and mutant SMN in SMA patient fibroblasts, immunofluorescence microscopy |
Human molecular genetics |
Medium |
19129172
|
| 2009 |
NOLC1 is required for TP53-mediated activation of the MDM2 promoter: co-transfection and chromatin immunoprecipitation experiments showed that TP53-regulated expression of MDM2 requires co-activation by NOLC1. NOLC1 knockdown in NPC xenografts reduces tumor growth and induces apoptosis with downregulation of MDM2. |
Co-transfection reporter assays, chromatin immunoprecipitation (ChIP), shRNA knockdown, xenograft tumor model |
The American journal of pathology |
Medium |
19541936
|
| 2013 |
Crystal structure of CK2 complexed with IP6 reveals that a lysine-rich cluster of CK2 is critical for IP6 binding. Biochemical experiments show that a Nopp140 fragment (residues 568–596) and IP6 competitively bind to CK2alpha at the substrate recognition site; phospho-Ser574 of Nopp140 significantly enhances its interaction with CK2alpha. Mutations K74E, K76E, K77E in CK2alpha reduce interactions with both IP6 and the Nopp140-derived peptide. |
X-ray crystallography, competitive binding assays, site-directed mutagenesis of CK2alpha, in vitro kinase activity assays, peptide-based interaction studies |
Proceedings of the National Academy of Sciences of the United States of America |
High |
24218616
|
| 2014 |
Drosophila Nopp140 deletion causes redistribution of the C/D snoRNP methyltransferase fibrillarin to the nucleoplasm, reduced 2'-O-methylation of rRNA at select sites, loss of cytoplasmic ribosomes (replaced by abnormal electron-dense granules), loss of RpL34, and a significant drop in protein translation. Pre-rRNA cleavage pathways are generally unaffected. R2 retrotransposons within rDNA are selectively expressed upon Nopp140 loss. |
FLP-FRT gene deletion, immunofluorescence, RT-PCR, northern blot, metabolic labeling, immunoblot, ultrastructural analysis (TEM) |
Chromosoma |
High |
25384888
|
| 2017 |
NOLC1 interacts with TRF2 and mediates nucleolar retention of TRF2 in a cell cycle-dependent manner. NOLC1 ablation increases nuclear TRF2 foci and decreases nucleolar TRF2 levels; conversely, NOLC1 overexpression promotes nucleolar accumulation of TRF2. NOLC1 overexpression also increases 53BP1 foci and induces DNA damage response; co-expression of TRF2 rescues NOLC1 overexpression-induced cell cycle arrest and apoptosis. |
Co-immunoprecipitation, siRNA knockdown, overexpression, immunofluorescence microscopy in 293T and HepG2 cells |
Cell death discovery |
Medium |
28875039
|
| 2018 |
Nopp140 is an intrinsically disordered protein; its C-terminal region (residues 568–596, specifically residues 574–589) binds CK2alpha, and this interaction induces conformational rigidity in the otherwise disordered Nopp140 C-terminal region. |
Single-molecule FRET (smFRET), electron paramagnetic resonance (EPR) with site-specific spin labeling, surface plasmon resonance |
International journal of molecular sciences |
Medium |
29382046
|
| 2019 |
Nopp140 is required to recruit and retain all scaRNPs (small Cajal body-specific RNPs) in Cajal bodies. Knockdown of Nopp140 releases all scaRNPs, causing an unprecedented reduction in size of CB granules. Mislocalization of telomerase by Nopp140 KD (as opposed to WDR79/TCAB1 mutation) leads to gradual extension of telomeres, identifying Nopp140 as a player in telomere length maintenance through dynamic distribution of telomerase between CBs and nucleoplasm. |
siRNA knockdown of Nopp140, electron microscopy (CB granule ultrastructure), telomere length assays, immunofluorescence |
Molecular biology of the cell |
High |
31664887
|
| 2021 |
CB localization of Nopp140 is essential for scaRNP concentration in Cajal bodies, and phosphorylation by CK2 at ~80 serines targets Nopp140 to CBs. Nopp140 knockdown-mediated release of scaRNPs from CBs severely compromises 2'-O-methylation of spliceosomal snRNAs (U1, U2, U5, U12), identifying CBs as the site of scaRNP catalysis and establishing that these snRNA modifications safeguard splicing fidelity. |
Nopp140 knockdown, 2'-O-methylation profiling of snRNAs, alternative splicing analysis, CK2 phosphorylation site characterization |
Genes & development |
High |
34301768
|
| 2022 |
Coilin's N-terminal domain (NTD) forms multivalent interactions with Nopp140 to achieve biomolecular condensation and CB assembly in the nucleus. Nopp140 has condensation capacity and is required for CB assembly; coilin NTD-NTD assemblies make multivalent contacts with Nopp140 to form nuclear puncta. Single amino acid mutations reveal distinct molecular interactions for fibril formation vs. Nopp140-dependent nuclear puncta formation. |
Single amino acid mutational analysis, live-cell imaging of coilin NTD behaviors (fibril vs. puncta formation), knockdown of Nopp140, in vivo condensation assays |
Nature communications |
High |
36224177
|
| 2022 |
FGF12 is a nucleolar protein that interacts with both NOLC1 and TCOF1, and is required to bridge the NOLC1-TCOF1 interaction (NOLC1 and TCOF1 cannot interact with each other in the absence of FGF12). The FGF12-NOLC1-TCOF1 complex formation is phosphorylation-dependent and requires the C-terminal region of FGF12. |
Co-immunoprecipitation, nucleolar localization assays, deletion/domain analysis, phosphorylation-dependence experiments |
Cell communication and signaling : CCS |
Medium |
36411431
|
| 2022 |
ACKR3 activation induces nuclear translocation of beta-arrestin-1 (beta-arr1), which interacts with NOLC1. Phosphorylated NOLC1 then interacts with fibrillarin (a nucleolar methyltransferase), increasing histone H2A methylation and promoting rRNA transcription in ribosome biogenesis. |
Co-immunoprecipitation, nuclear fractionation, CXCL12/AMD3100 pharmacological activation of ACKR3, transgenic mouse model, rRNA transcription assays |
Acta pharmacologica Sinica |
Medium |
35365782
|
| 2025 |
SPOP (E3 ubiquitin ligase adaptor) mediates ubiquitination and proteasomal degradation of NOLC1 to maintain normal protein levels. ECa-associated SPOP mutants abrogate binding and ubiquitination of NOLC1, causing NOLC1 accumulation. NOLC1 acts as a transcriptional factor to activate transcription of B4GALT1, leading to abnormal glycosylation. |
Co-immunoprecipitation, ubiquitination assays, SPOP mutant expression, transcriptional reporter assays for B4GALT1, knockdown/overexpression experiments |
Oncogene |
Medium |
40097806
|
| 2025 |
NOLC1 binds to the p53 DNA-binding domain (DBD), decreasing p53 nuclear accumulation stimulated by cisplatin and suppressing p53 transcriptional functions, thereby suppressing p53-mediated ferroptosis. |
Co-immunoprecipitation with domain mapping, NOLC1 knockdown, p53 nuclear accumulation assays, ferroptosis assays, p53 target gene expression analysis |
eLife |
Medium |
40864495
|
| 2025 |
FTO (m6A eraser) destabilizes NOLC1 mRNA by removing m6A modifications; FTO knockdown increases m6A modifications on NOLC1 mRNA, increasing its stability and thus NOLC1 protein levels. Elevated NOLC1 inhibits pre-rRNA transcription, causing nucleolar stress and p53 accumulation, thereby promoting cellular senescence. |
m6A modification profiling, RNA stability assays, FTO knockdown/overexpression, NOLC1 knockdown rescue experiments, p53 accumulation assays, pre-rRNA transcription assays |
Biomolecules |
Medium |
41301545
|
| 2025 |
Nopp140 concentrates intrinsically disordered, NLS-rich protein regions (IDRs) in the dense fibrillar component (DFC) of the nucleolus, including the CTD of RNA Pol I-associated factor PAF49. This network forms the DFC as a liquid-liquid phase separated condensate that fosters rRNA modification with near-100% efficiency. |
Live-cell imaging, phase separation assays, knockdown experiments, rRNA modification analysis |
bioRxivpreprint |
Medium |
|
| 2025 |
NOLC1 functions as a key transcriptional regulator of NPR1 (encoding NPRA) in endothelial cells: reverse ChIP of the NPR1 promoter identified NOLC1 as a binding protein, and NOLC1 knockdown decreases both NPRA mRNA and protein expression. Loss of NOLC1 also triggers cellular senescence (elevated p53/p21, SA-β-gal, ROS, G0/G1 arrest), which is rescued by NPRA overexpression. |
Reverse chromatin immunoprecipitation (R-ChIP), siRNA knockdown, NPRA overexpression rescue experiments, senescence assays |
Genesis (New York, N.Y. : 2000) |
Medium |
41195691
|