| 2007 |
N4BP1 binds the WW2 domain of the E3 ubiquitin ligase Itch, competing with Itch substrates (p73α, c-Jun, p63) for the same binding site, thereby inhibiting Itch-mediated ubiquitylation of these substrates and Itch autoubiquitylation activity both in vitro and in vivo. |
Co-immunoprecipitation, in vitro and in vivo ubiquitylation assays, RNAi knockdown, N4BP1 knockout cells |
Proceedings of the National Academy of Sciences of the United States of America |
High |
17592138
|
| 2010 |
N4BP1 is a substrate for Nedd4-mediated polyubiquitylation and proteasomal degradation. SUMOylation of N4BP1 by SUMO1 abrogates its ubiquitylation, stabilizing it. Endogenous N4BP1 localizes predominantly to the nucleolus in primary cells, with a fraction at PML nuclear bodies; loss of the desumoylase SENP1 or proteasome inhibition causes accumulation of N4BP1 at PML nuclear bodies. |
Ubiquitylation assays, SUMOylation assays, immunofluorescence localization, subcellular fractionation, SENP1-mutant primary embryonic fibroblasts, proteasome inhibitor (MG132) treatment |
Journal of cell science |
High |
20233849
|
| 2019 |
N4BP1 harbors a PilT N-terminus (NYN)-like RNase domain and inhibits HIV-1 replication by binding to and degrading viral mRNA species. N4BP1 is cleaved at Arg509 by the paracaspase MALT1 following T cell activation, and this cleavage inactivates its HIV-1 restriction activity and facilitates reactivation of latent HIV-1 proviruses. |
RNA-binding and mRNA degradation assays, mutational analysis (Arg509), MALT1 knockout studies, primary T cell and macrophage infection models |
Nature microbiology |
High |
31133753
|
| 2019 |
N4BP1 contains a novel ubiquitin-binding domain (CoCUN) in its C-terminal ~50 residues that recognizes the canonical hydrophobic patch of ubiquitin (Ile44) through a Phe-Pro motif, resembling CUE domain recognition but evolutionarily distinct. CoCUN does not bind NEDD8 (unlike the related CUBAN domain). Both CoCUN and CUBAN are polyubiquitinated in cells. |
NMR spectroscopy (15N chemical shift perturbation), mutagenesis, circular dichroism, protein sequence analysis |
Biomolecules |
High |
31319543
|
| 2020 |
N4BP1 is a suppressor of TLR1/2-, TLR7-, and TLR9-driven cytokine production (MyD88-dependent TLRs), but not TLR3 or TLR4 responses in wild-type macrophages. N4BP1 is cleaved and inactivated by caspase-8 downstream of TRIF signaling (TLR3, TLR4) or TNF/death receptor engagement, thereby licensing those pathways to produce higher cytokine levels. Caspase-8-deficient macrophages retain intact N4BP1, explaining their impaired cytokine responses to TLR3/4; co-deletion of N4BP1 in caspase-8-deficient macrophages largely rescues this defect. |
N4BP1 knockout mice, caspase-8-deficient macrophages, N4BP1/caspase-8 double-knockout genetic rescue, cytokine production assays, cleavage assays |
Nature |
High |
32971525
|
| 2021 |
N4BP1 inhibits TLR-dependent NF-κB activation by directly interacting with the NEMO (IKKγ) COZI domain through its UBA-like and CUE-like domains, attenuating NEMO dimerization/oligomerization. Caspase-8, activated downstream of TRIF (TLR3/TLR4), cleaves N4BP1 distal to residues D424 and D490, abolishing its inhibitory effect on NF-κB. |
Co-immunoprecipitation, in vitro binding assays, domain deletion mapping, N4bp1-deficient mice, caspase-8 cleavage site mutagenesis |
Nature communications |
High |
33654074
|
| 2021 |
In keratinocytes, N4BP1 binds JunB and FosB mRNAs and reduces their stability, thereby suppressing keratinocyte proliferation. In neutrophils, N4BP1 limits survival and tissue infiltration by targeting CXCL1, CCL20, and S100A8 mRNAs. N4BP1-deficient mice develop severe IMQ-induced psoriasis-like disease. |
RNA immunoprecipitation, transcriptome profiling, N4BP1 KO mice, primary keratinocyte proliferation assays, IMQ psoriasis model |
Cell death & disease |
Medium |
33990547
|
| 2023 |
N4BP1 negatively regulates Notch signaling by binding NICD (specifically via the NICD RAM domain) and promoting its ubiquitin-mediated proteasomal degradation after Notch1 S3 cleavage. The CoCUN domain Phe-Pro motif (residues 862/863) in N4BP1 is essential for NICD degradation. The E3 ligase Trim21 is required for N4BP1-regulated NICD degradation. In cortical neural progenitors, N4BP1 overexpression promotes differentiation while N4BP1 loss maintains stem-like properties. |
Protein binding assays, domain mutagenesis (Phe-Pro motif), Trim21 KO, overexpression and KO in neural progenitor cells, cortical development assays |
The EMBO journal |
Medium |
37807845
|
| 2024 |
N4BP1 acts as a dimerization-dependent linear ubiquitin reader through a novel ubiquitin-binding module named LUBIN, which positions two non-selective ubiquitin-binding domains to preferentially recognize linear (M1) ubiquitin chains. N4BP1 is recruited to the nascent TNFR1 signaling complex and limits NF-κB signaling duration in a LUBIN-dependent manner. N4BP1 deficiency accelerates TNFα-induced cell death by increasing complex II assembly. Under apoptotic conditions, caspase-8 cleaves N4BP1, leading to its rapid 26S proteasomal degradation. |
Structural modeling, mutagenesis, TNFR1 signaling complex immunoprecipitation, N4BP1 KO functional assays, ubiquitin-chain binding assays, caspase-8 cleavage assays |
Cell death discovery |
Medium |
38643192
|
| 2024 |
N4BP1 acts in concert with non-canonical IκB kinases (TBK1 and IKKε) and their adaptor TANK to limit the duration of canonical IKKα/β signaling after MyD88-dependent TLR activation. Deletion of TBK1/IKKε or TANK phenocopies N4BP1 deficiency. Optimal suppression requires N4BP1's ability to bind polyubiquitin chains, as inactivating mutations in the ubiquitin-binding motif of N4BP1 increase TLR-induced cytokine production. |
N4BP1 KO and ubiquitin-binding mutant knock-in mice, TBK1/IKKε/TANK KO macrophages, cytokine production assays, genetic epistasis |
Immunity |
High |
38697117
|
| 2024 |
N4BP1 degrades its mRNA targets via their coding sequences (CDS) rather than the 3'-UTR. A critical 33-nt sequence (nt 289–322) near the 5' end of FosC CDS, containing a polyC motif, is required for N4BP1-mediated degradation. Both the KH domain and the NYN (YacP-like nuclease) domain are essential for N4BP1's mRNA-degrading activity. N4BP1-mediated mRNA turnover is independent of nonsense-mediated decay (NMD), as it is preserved in UPF1/UPF3A/UPF3B-deficient cells. |
Domain deletion mutagenesis, point mutations, reporter assays, CDS/3'UTR swap experiments, NMD-deficient cell lines (UPF1/UPF3A/UPF3B KO), RNA immunoprecipitation |
The Journal of biological chemistry |
High |
39491646
|
| 2024 |
Enteroviral 3C protease (3Cpro) from multiple human enteroviruses cleaves N4BP1 at residue Q816, destroying its ability to regulate TNFα-induced NF-κB signaling. Mouse N4BP1, which has a threonine at the P1' site, is resistant to human enteroviral 3Cpro, but rodent EMCV 3Cpro cleaves both human and mouse N4BP1 at species-specific sites. |
FIMO motif search, biochemical cleavage assays, cell biology experiments with 3Cpro expression, site mutagenesis (Q816), NF-κB signaling readouts |
Journal of virology |
Medium |
39655957
|
| 2025 |
N4BP1 is a nucleocytoplasmic shuttling protein. Nuclear accumulation is induced by leptomycin B (blocking CRM1-mediated export). A nuclear localization signal (NLS) spanning residues 279–299 is required for nuclear import; its deletion abolishes nuclear import and fusion to GFP drives GFP into the nucleus. N4BP1 forms liquid-liquid phase separation aggregates in both cytoplasm and nucleus that colocalize with NEDD8-modified proteins (including cullin-1 and cullin-2), dependent on the CoCUN domain. Heat shock promotes N4BP1 aggregation, which confers cellular protection under stress. |
Leptomycin B treatment, NLS deletion and GFP fusion constructs, live imaging, 1,6-hexanediol phase separation assay, co-localization with neddylated proteins, heat shock experiments |
The Journal of biological chemistry |
Medium |
40701250
|
| 2026 |
N4BP1 suppresses IL-17 signaling by blocking translation of Act1 (TRAF3IP2) mRNA rather than affecting its stability. In N4BP1-deficient cells, Act1 mRNA is enriched in the translationally active polysome fraction, leading to elevated Act1 protein, hyperactivation of p38 MAPK, and increased downstream cytokines (CXCL1, CCL20, MMP9). |
Polysome profiling, mRNA stability assays, N4BP1 KO cells and mice, Act1 shRNA rescue experiments, p38 pharmacological inhibition, IMQ-induced skin model |
Inflammation research |
Medium |
41504891
|
| 2025 |
N4BP1 is identified as a negative regulator of NF-κB that is targeted by poxvirus effector myxoma virus M3.1; N4BP1 inactivation by M3.1 unleashes an NF-κB ETI response, placing N4BP1 functionally alongside ZC3H12A and TBK1 as anti-viral NF-κB suppressors that can serve as pathogen sensors. |
Virulence factor expression screen in human monocytes, RNA-seq transcriptional response assays |
bioRxiv (preprint)preprint |
Low |
bio_10.1101_2025.03.04.641538
|