Dynamic interactions between SPX proteins, the ubiquitination machinery, and signalling molecules for stress adaptation at a whole-plant level.

The plant macronutrient phosphorus is a scarce resource and plant-available phosphate is limiting in most soil types. Generally, a gene regulatory module called the phosphate starvation response (PSR) enables efficient phosphate acquisition by roots and translocation to other organs. Plants growing on moderate to nutrient-rich soils need to co-ordinate availability of different nutrients and repress the highly efficient PSR to adjust phosphate acquisition to the availability of other macro- and micronutrients, and in particular nitrogen. PSR repression is mediated by a small family of single SYG1/Pho81/XPR1 (SPX) domain proteins. The SPX domain binds higher order inositol pyrophosphates that signal cellular phosphorus status and modulate SPX protein interaction with PHOSPHATE STARVATION RESPONSE1 (PHR1), the central transcriptional regulator of PSR. Sequestration by SPX repressors restricts PHR1 access to PSR gene promoters. Here we focus on SPX4 that primarily acts in shoots and sequesters many transcription factors other than PHR1 in the cytosol to control processes beyond the classical PSR, such as nitrate, auxin, and jasmonic acid signalling. Unlike SPX1 and SPX2, SPX4 is subject to proteasomal degradation not only by singular E3 ligases, but also by SCF-CRL complexes. Emerging models for these different layers of control and their consequences for plant acclimation to the environment will be discussed.

Catalysis of non-canonical protein ubiquitylation by the ARIH1 ubiquitin ligase.

Protein ubiquitylation typically involves isopeptide bond formation between the C-terminus of ubiquitin to the side-chain amino group on Lys residues. However, several ubiquitin ligases (E3s) have recently been identified that ubiquitylate proteins on non-Lys residues. For instance, HOIL-1 belongs to the RING-in-between RING (RBR) class of E3s and has an established role in Ser ubiquitylation. Given the homology between HOIL-1 and ARIH1, an RBR E3 that functions with the large superfamily of cullin-RING E3 ligases (CRLs), a biochemical investigation was undertaken, showing ARIH1 catalyzes Ser ubiquitylation to CRL-bound substrates. However, the efficiency of ubiquitylation was exquisitely dependent on the location and chemical environment of the Ser residue within the primary structure of the substrate. Comprehensive mutagenesis of the ARIH1 Rcat domain identified residues whose mutation severely impacted both oxyester and isopeptide bond formation at the preferred site for Ser ubiquitylation while only modestly affecting Lys ubiquitylation at the physiological site. The results reveal dual isopeptide and oxyester protein ubiquitylation activities of ARIH1 and set the stage for physiological investigations into this function of emerging importance.

Identification of ester-linked ubiquitylation sites during TLR7 signalling increases the number of inter-ubiquitin linkages from 8 to 12.

The E3 ligase HOIL-1 forms ester bonds in vitro between ubiquitin and serine/threonine residues in proteins. Here, we exploit UbiSite technology to identify serine and threonine residues undergoing HOIL-1 catalysed ubiquitylation in macrophages stimulated with R848, an activator of the TLR7/8 heterodimer. We identify Thr12, Thr14, Ser20 and Thr22 of ubiquitin as amino acid residues forming ester bonds with the C-terminal carboxylate of another ubiquitin molecule. This increases from 8 to 12 the number of ubiquitin linkage types that are formed in cells. We also identify Ser175 of IRAK4, Ser136, Thr163 and Ser168 of IRAK2 and Thr141 of MyD88 as further sites of HOIL-1-catalysed ubiquitylation together with lysine residues in these proteins that also undergo R848-dependent ubiquitylation. These findings establish that the ubiquitin chains attached to components of myddosomes are initiated by both ester and isopeptide bonds. Ester bond formation takes place within the proline, serine, threonine-rich (PST) domains of IRAK2 and IRAK4 and the intermediate domain of MyD88. The ubiquitin molecules attached to Lys162, Thr163 and Ser168 of IRAK2 are attached to different IRAK2 molecules.

Functional loss of ubiquitin-specific protease 14 may lead to a novel distal arthrogryposis phenotype.

Multiple congenital contractures (MCC) comprise a number of rare, non-progressive conditions displaying marked phenotypic and etiologic heterogeneity. A genetic cause can be established in approximately half of the affected individuals, attributed to genetic defects in the formation and functioning of the central and peripheral nervous system, neuromuscular junctions, skeletal muscles, and connective tissue. Ubiquitin-specific protease 14 (USP14) encodes a major proteasome-associated deubiquitinating enzyme with an established dual role as an inhibitor and an activator of proteolysis, maintaining protein homeostasis. Usp14-deficient mice show a phenotype similar to lethal human MCC phenotypes, with callosal anomalies, muscle wasting, and early lethality, attributed to neuromuscular junction defects due to decreased monomeric ubiquitin pool. We describe a new, autosomal recessive MCC phenotype in three fetuses from two different branches of a consanguineous family, presenting with distal arthrogryposis, underdevelopment of the corpus callosum, and dysmorphic facial features. Exome sequencing identified a biallelic 4-bp deletion (c.233_236delTTCC; p.Leu78Glnfs*11, SCV002028347) in USP14, and sequencing of family members showed segregation with the phenotype. RT-qPCR experiment in an unaffected heterozygote revealed that mutant USP14 was expressed, indicating that abnormal transcript escapes nonsense-mediated mRNA decay. We propose that herein described fetuses represent the first human phenotype of USP14 loss, with callosal anomalies and/or cortical malformations, multiple contractures, and recognizable dysmorphic facial features.

The BRCA1/BARD1 ubiquitin ligase and its substrates.

Mutations in breast cancer type 1 susceptibility protein (BRCA1) and its heterodimeric binding partner BARD1 confer a high risk for the development of breast and ovarian cancers. The sole enzymatic function of the BRCA1/BARD1 complex is as a RING-type E3 ubiquitin (Ub) ligase, leading to the deposition of Ub signals onto a variety of substrate proteins. Distinct types of Ub signals deposited by BRCA1/BARD1 (i.e. degradative vs. non-degradative; mono-Ub vs. poly-Ub chains) on substrate proteins mediate aspects of its function in DNA double-stranded break repair, cell-cycle regulation, and transcriptional regulation. While cancer-predisposing mutations in both subunits lead to the inactivation of BRCA1/BARD1 ligase activity, controversy remains as to whether its Ub ligase activity directly inhibits tumorigenesis. Investigation of BRCA1/BARD1 substrates using rigorous, well-validated mutants and experimental systems will ultimately clarify the role of its ligase activity in cancer and possibly establish prognostic and diagnostic metrics for patients with mutations. In this review, we discuss the Ub ligase function of BRCA1/BARD1, highlighting experimental approaches, mechanistic considerations, and reagents that are useful in the study of substrate ubiquitylation. We also discuss the current understanding of two well-established BRCA1/BARD1 substrates (nucleosomal H2A and estrogen receptor α) and several recently discovered substrates (p50, NF2, Oct1, and LARP7). Lessons from the current body of work should provide a road map to researchers examining novel substrates and biological functions attributed to BRCA1/BARD1 Ub ligase activity.

Reconstitution of human CMG helicase ubiquitylation by CUL2LRR1 and multiple E2 enzymes.

Cullin ubiquitin ligases drive replisome disassembly during DNA replication termination. In worm, frog and mouse cells, CUL2LRR1 is required to ubiquitylate the MCM7 subunit of the CMG helicase. Here, we show that cullin ligases also drive CMG-MCM7 ubiquitylation in human cells, thereby making the helicase into a substrate for the p97 unfoldase. Using purified human proteins, including a panel of E2 ubiquitin-conjugating enzymes, we have reconstituted CMG helicase ubiquitylation, dependent upon neddylated CUL2LRR1. The reaction is highly specific to CMG-MCM7 and requires the LRR1 substrate targeting subunit, since replacement of LRR1 with the alternative CUL2 adaptor VHL switches ubiquitylation from CMG-MCM7 to HIF1. CUL2LRR1 firstly drives monoubiquitylation of CMG-MCM7 by the UBE2D class of E2 enzymes. Subsequently, CUL2LRR1 activates UBE2R1/R2 or UBE2G1/G2 to extend a single K48-linked ubiquitin chain on CMG-MCM7. Thereby, CUL2LRR1 converts CMG into a substrate for p97, which disassembles the ubiquitylated helicase during DNA replication termination.

Structural and Biochemical Basis for Higher-Order Assembly between A20-Binding Inhibitor of NF-κB 1 (ABIN1) and M1-Linked Ubiquitins.

Polyubiquitination is important in controlling NF-κB signaling. Excessive NF-κB activity has been linked to inflammatory disorders and autoimmune diseases, while ABIN1 could attenuate NF-κB activation to maintain immune homeostasis by utilizing UBAN to recognize linear (M1)-linked polyubiquitinated NF-κB activation mediators, including NEMO, IRAK1 and RIP1. PolyUb-mediated UBAN recruitment remains undetermined, since the recognition studies focused mostly on di-ubiquitin (diUb). Here we report three crystal structures of human ABIN1 UBAN (hABIN1UBAN) in complex with M1-linked diUb, triUb, and tetraUb, respectively. Notably, the hABIN1UBAN:diUb structure reveals that a diUb randomly binds one of the Ub-binding sites of the hABIN1UBAN dimer and leaves the other site vacant. Together with the ITC and gel-filtration analyses, we found that M1-triUb and M1-tetraUb adopt two unique conformations, instead of an elongated one, and they preferentially use the N-terminal two-Ub unit to bind the primary Ub-binding site of a hABIN1UBAN dimer and the C-terminal two-Ub unit to bind the secondary Ub-binding site of another hABIN1UBAN dimer. Especially, our results suggest that two ABIN1UBAN dimers cooperatively bind two UBAN-binding units of a tetraUb or vice versa. Since the UBAN family members share a conserved diUb-binding mode, our results suggest that M1-polyUb modification allows multiple copies of the two-tandem Ub unit to simultaneously coordinate multiple and/or different binding partners to increase their local concentrations and to facilitate the formation of a large signaling complex. Our study provides a structural-functional glimpse of M1-polyUb as a multiple-molecule binding platform to exert its intrinsic structural plasticity in mediating cellular signaling.

Proteasome in action: substrate degradation by the 26S proteasome.

Ubiquitination is the major criteria for the recognition of a substrate-protein by the 26S proteasome. Additionally, a disordered segment on the substrate - either intrinsic or induced - is critical for proteasome engagement. The proteasome is geared to interact with both of these substrate features and prepare it for degradation. To facilitate substrate accessibility, resting proteasomes are characterised by a peripheral distribution of ubiquitin receptors on the 19S regulatory particle (RP) and a wide-open lateral surface on the ATPase ring. In this substrate accepting state, the internal channel through the ATPase ring is discontinuous, thereby obstructing translocation of potential substrates. The binding of the conjugated ubiquitin to the ubiquitin receptors leads to contraction of the 19S RP. Next, the ATPases engage the substrate at a disordered segment, energetically unravel the polypeptide and translocate it towards the 20S catalytic core (CP). In this substrate engaged state, Rpn11 is repositioned at the pore of the ATPase channel to remove remaining ubiquitin modifications and accelerate translocation. C-termini of five of the six ATPases insert into corresponding lysine-pockets on the 20S α-ring to complete 20S CP gate opening. In the resulting substrate processing state, the ATPase channel is fully contiguous with the translocation channel into the 20S CP, where the substrate is proteolyzed. Complete degradation of a typical ubiquitin-conjugate takes place over a few tens of seconds while hydrolysing tens of ATP molecules in the process (50 kDa/∼50 s/∼80ATP). This article reviews recent insight into biochemical and structural features that underlie substrate recognition and processing by the 26S proteasome.

Herpes simplex virus 1 infection induces ubiquitination of UBE1a.

Herpes simplex virus 1 (HSV-1) is a human DNA virus that causes cold sores, keratitis, meningitis, and encephalitis. Ubiquitination is a post-translational protein modification essential for regulation of cellular events, such as proteasomal degradation, signal transduction, and protein trafficking. The process is also involved in events for establishing viral infection and replication. The first step in ubiquitination involves ubiquitin (Ub) binding with Ub-activating enzyme (E1, also termed UBE1) via a thioester linkage. Our results show that HSV-1 infection alters protein ubiquitination pattern in host cells, as evidenced by MS spectra and co-immunoprecipitation assays. HSV-1 induced ubiquitination of UBE1a isoform via an isopeptide bond with Lys604. Moreover, we show that ubiquitination of K604 in UBE1a enhances UBE1a activity; that is, the activity of ubiquitin-transfer to E2 enzyme. Subsequently, we investigated the functional role of UBE1a and ubiquitination of K604 in UBE1a. We found that UBE1-knockdown increased HSV-1 DNA replication and viral production. Furthermore, overexpression of UBE1a, but not a UBE1a K604A mutant, suppressed viral replication. Furthermore, we found that UBE1a and ubiquitination at K604 in UBE1a retarded expression of HSV-1 major capsid protein, ICP5. Our findings show that UBE1a functions as an antiviral factor that becomes activated upon ubiquitination at Lys604.

DNA-damage tolerance through PCNA ubiquitination and sumoylation.

DNA-damage tolerance (DDT) is employed by eukaryotic cells to bypass replication-blocking lesions induced by DNA-damaging agents. In budding yeast Saccharomyces cerevisiae, DDT is mediated by RAD6 epistatic group genes and the central event for DDT is sequential ubiquitination of proliferating cell nuclear antigen (PCNA), a DNA clamp required for replication and DNA repair. DDT consists of two parallel pathways: error-prone DDT is mediated by PCNA monoubiquitination, which recruits translesion synthesis DNA polymerases to bypass lesions with decreased fidelity; and error-free DDT is mediated by K63-linked polyubiquitination of PCNA at the same residue of monoubiquitination, which facilitates homologous recombination-mediated template switch. Interestingly, the same PCNA residue is also subjected to sumoylation, which leads to inhibition of unwanted recombination at replication forks. All three types of PCNA posttranslational modifications require dedicated conjugating and ligation enzymes, and these enzymes are highly conserved in eukaryotes, from yeast to human.

A novel polyubiquitin chain linkage formed by viral Ubiquitin is resistant to host deubiquitinating enzymes.

The Baculoviridae family of viruses encode a viral Ubiquitin (vUb) gene. Though the vUb is homologous to the host eukaryotic Ubiquitin (Ub), its preservation in the viral genome indicates unique functions that are not compensated by the host Ub. We report the structural, biophysical, and biochemical properties of the vUb from Autographa californica multiple nucleo-polyhedrosis virus (AcMNPV). The packing of central helix α1 to the beta-sheet ß1-ß5 is different between vUb and Ub. Consequently, its stability is lower compared with Ub. However, the surface properties, ubiquitination activity, and the interaction with Ubiquitin-binding domains are similar between vUb and Ub. Interestingly, vUb forms atypical polyubiquitin chain linked by lysine at the 54th position (K54), and the deubiquitinating enzymes are ineffective against the K54-linked polyubiquitin chains. We propose that the modification of host/viral proteins with the K54-linked chains is an effective way selected by the virus to protect the vUb signal from host DeUbiquitinases.

Association of DEAR1 Tagging Single Nucleotide Polymorphisms With Breast Cancer in a Sample of Colombian Population: A Case Control Study.

PURPOSE: Ubiquitin ligase genes can act as oncogenes or tumor suppressor genes. They play a role in various diseases, including development and progression of breast cancer; the objective of this study was to evaluate the association of common variants in the ductal-epithelium-associated RING chromosome 1 (DEAR1) gene with breast cancer risk in a sample of Colombian population. METHODS: We carried out a case-control study to investigate associations of variants in DEAR1 with breast cancer in women from Colombia. Single nucleotide polymorphisms (SNPs) rs584298, rs2927970, rs59983645, and rs599167 were genotyped in 1022 breast cancer cases and 1023 healthy controls using the iPLEX® and Kompetitive Allele Specific PCR (polymerase chain reaction) (KASP) method. The associations between SNPs and breast cancer were examined by conditional logistic regression. The associations between SNPs and epidemiological/histopathological variables were examined by multinomial logistic regression. RESULTS: Associations were found between tag SNPs and breast cancer adjusted for the epidemiological risk factors rs584298 genotypes AG and GG (P = .048 and P = .004, respectively). The analysis of the disease characteristics showed that SNP rs584298 (genotype AG) (P = .015) shows association with progesterone receptor (PR) status and (genotype AA) (P = .048) shows association with human epidermal growth factor receptor 2 (HER2) status. CONCLUSIONS: The SNP rs584298 in DEAR1 showed associations with breast cancer and the expression of HER2 receptor; when this receptor is amplified, the result is aggressive tumoral subtype and expression of PR receptor that is associated with high-proliferative tumor grade. Validation of this SNP is important to establish whether this variant or the tagged variant is the cause for the risk association showed.

PAQR9 Modulates BAG6-mediated protein quality control of mislocalized membrane proteins.

Protein quality control is crucial for maintaining cellular homeostasis and its dysfunction is closely linked to human diseases. The post-translational protein quality control machinery mainly composed of BCL-2-associated athanogene 6 (BAG6) is responsible for triage of mislocalized membrane proteins (MLPs). However, it is unknown how the BAG6-mediated degradation of MLPs is regulated. We report here that PAQR9, a member of the Progesterone and AdipoQ receptor (PAQR) family, is able to modulate BAG6-mediated triage of MLPs. Analysis with mass spectrometry identified that BAG6 is one of the major proteins interacting with PAQR9 and such interaction is confirmed by co-immunoprecipitation and co-localization assays. The protein degradation rate of representative MLPs is accelerated by PAQR9 knockdown. Consistently, the polyubiquitination of MLPs is enhanced by PAQR9 knockdown. PAQR9 binds to the DUF3538 domain within the proline-rich stretch of BAG6. PAQR9 reduces the binding of MLPs to BAG6 in a DUF3538 domain-dependent manner. Taken together, our results indicate that PAQR9 plays a role in the regulation of protein quality control of MLPs via affecting the interaction of BAG6 with membrane proteins.

Bacterial DUBs: deubiquitination beyond the seven classes.

Protein ubiquitination is a posttranslational modification that regulates many aspects of cellular life, including proteostasis, vesicular trafficking, DNA repair and NF-κB activation. By directly targeting intracellular bacteria or bacteria-containing vacuoles to the lysosome, ubiquitination is also an important component of cell-autonomous immunity. Not surprisingly, several pathogenic bacteria encode deubiquitinases (DUBs) and use them as secreted effectors that prevent ubiquitination of bacterial components. A systematic overview of known bacterial DUBs, including their cleavage specificities and biological roles, suggests multiple independent acquisition events from host-encoded DUBs and other proteases. The widely used classification of DUBs into seven well-defined families should only be applied to eukaryotic DUBs, since several bacterial DUBs do not follow this classification.

The 'dark matter' of ubiquitin-mediated processes: opportunities and challenges in the identification of ubiquitin-binding domains.

Ubiquitin modifications of target proteins act to localise, direct and specify a diverse range of cellular processes, many of which are biomedically relevant. To allow this diversity, ubiquitin modifications exhibit remarkable complexity, determined by a combination of polyubiquitin chain length, linkage type, numbers of ubiquitin chains per target, and decoration of ubiquitin with other small modifiers. However, many questions remain about how different ubiquitin signals are specifically recognised and transduced by the decoding ubiquitin-binding domains (UBDs) within ubiquitin-binding proteins. This review briefly outlines our current knowledge surrounding the diversity of UBDs, identifies key challenges in their discovery and considers recent structural studies with implications for the increasing complexity of UBD function and identification. Given the comparatively low numbers of functionally characterised polyubiquitin-selective UBDs relative to the ever-expanding variety of polyubiquitin modifications, it is possible that many UBDs have been overlooked, in part due to limitations of current approaches used to predict their presence within the proteome. Potential experimental approaches for UBD discovery are considered; web-based informatic analyses, Next-Generation Phage Display, deubiquitinase-resistant diubiquitin, proximity-dependent biotinylation and Ubiquitin-Phototrap, including possible advantages and limitations. The concepts discussed here work towards identifying new UBDs which may represent the 'dark matter' of the ubiquitin system.

Integrative genomic analysis identifies associations of molecular alterations to APOBEC and BRCA1/2 mutational signatures in breast cancer.

BACKGROUND: The observed mutations in cancer are the result of ~30 mutational processes, which stamp particular mutational signatures (MS). Nevertheless, it is still not clear which genomic alterations correlate to several MS. Here, a method to analyze associations of genomic data with MS is presented and applied to The Cancer Genome Atlas breast cancer data revealing promising associations. METHODS: The MS were discretized into clusters whose extremes were statistically associated with mutations, copy number, and gene expression data. RESULTS: Known associations for apolipoprotein B editing complex (APOBEC) and for BRCA1 and BRCA2 support the proposal. For BRCA1/2, mutations in ARAP3, three focal deletions, and one amplification were detected. Around 50 mutated genes for the two APOBEC signatures were identified including three kinesins (KIF13A, KIF1B, KIF4A), three ubiquitins (USP45, UBR4, UBR1), and two demethylases (KDM5B, KDM5C) among other genes also connected to DNA damage pathways. The results suggest novel roles for other genes currently not involved in DNA repair. The altered expression program was very high for the BRCA1/2 signature, high for APOBEC signature 13 clearly associated to immune response, and low for APOBEC signature 2. The remaining signatures show scarce associations. CONCLUSION: Specific genetic alterations can be associated with particular MS.

Designing active RNF4 monomers by introducing a tryptophan: avidity towards E2∼Ub conjugates dictates the activity of ubiquitin RING E3 ligases.

Ubiquitin RING E3 ligases (E3s) catalyze ubiquitin (Ub) transfer to their substrates by engaging E2∼Ub intermediates with the help of their RING domains. Different E3s have been found to contain a conserved tryptophan residue in their RING that plays an essential role in E2 binding and, hence, enzymatic activity. Many active E3s, however, lack this specific residue. We mined through the existing data to observe that the conservation of the tryptophan and quaternary organization of the RING domains are remarkably correlated. Monomeric RINGs possess the tryptophan while all well-characterized dimeric RINGs, except RNF8, contain other amino acid residues. Biochemical analyses on representative E3s and their mutants reveal that the tryptophan is essential for optimal enzymatic activity of monomeric RINGs whereas dimeric E3s with tryptophan display hyperactivity. Most critically, the introduction of the tryptophan restores the activity of inactive monomeric RNF4 mutants, an obligatory dimeric E3. Binding studies indicate that monomeric RINGs retained the tryptophan for their optimal functionality to compensate for weak Ub binding. On the other hand, tryptophan was omitted from dimeric RINGs during the course of evolution to prevent unwanted modifications and allow regulation of their activity through oligomerization.

TGF-ß prevents the denervation-induced reduction of bone formation and promotes the bone regeneration through inhibiting ubiquitin-proteasome pathway.

Background: Transforming growth factor beta (TGF-ß) can stimulate osteogenesis as a multifunctional protein. The present study was to explore if TGF-ß can prevent denervation-induced reduction of bone formation.Materials & methods: The 6-week-old male mice were treated with recombinant human TGF-ß1 (rhTGF-ß1). Bone formation, endochondral bone growth rates, and gene expression of osteoblast markers were measured in the skeletal tissue by real-time PCR.Results: RhTGF-ß1 treatment prevented the denervation-induced decrease in bone formation rates, endochondral growth, and expression of Cbfa1/Runx2 (runt-related transcription factor 2), Ostecalcin (OC), and ColIA1. TGF-ß1 partially inhibited the denervation-induced ubiquitination of Cbfa1/Runx2 in mouse cancellous bones via ubiquitin-proteasome pathway.Conclusion: TGF-ß prevents denervation-induced reduction of bone formation and promotes the bone regeneration through inhibiting ubiquitin-proteasome pathway at least partially.

Role of RNF20 in cancer development and progression - a comprehensive review.

Evolving strategies to counter cancer initiation and progression rely on the identification of novel therapeutic targets that exploit the aberrant genetic changes driving oncogenesis. Several chromatin associated enzymes have been shown to influence post-translational modification (PTM) in DNA, histones, and non-histone proteins. Any deregulation of this core group of enzymes often leads to cancer development. Ubiquitylation of histone H2B in mammalian cells was identified over three decades ago. An exciting really interesting new gene (RING) family of E3 ubiquitin ligases, known as RNF20 and RNF40, monoubiquitinates histone H2A at K119 or H2B at K120, is known to function in transcriptional elongation, DNA double-strand break (DSB) repair processes, maintenance of chromatin differentiation, and exerting tumor suppressor activity. RNF20 is somatically altered in breast, lung, prostate cancer, clear cell renal cell carcinoma (ccRCC), and mixed lineage leukemia, and its reduced expression is a key factor in initiating genome instability; and it also functions as one of the significant driving factors of oncogenesis. Loss of RNF20/40 and H2B monoubiquitination (H2Bub1) is found in several cancers and is linked to an aggressive phenotype, and is also an indicator of poor prognosis. In this review, we summarized the current knowledge of RNF20 in chronic inflammation-driven cancers, DNA DSBs, and apoptosis, and its impact on chromatin structure beyond the single nucleosome level.