GO:1900045 negative regulation of protein K63-linked ubiquitination: Immune Signaling Brake, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1900045 describes any process that stops, prevents, or reduces the frequency, rate, or extent of K63-linked ubiquitination of a protein, a non-degradative ubiquitin chain type central to immune signaling and protein quality control.
• Key negative regulators include deubiquitinases such as OTUD4, OTUD1, and PSMD14, and E3 ligases such as TRIM35 and STUB1 that can redirect or limit K63 chain formation on specific substrates.
• Dysregulation of K63-linked ubiquitination brakes is linked to cancer progression, immune evasion, autoinflammatory signaling, and impaired antigen presentation.
• The process is substrate-specific and often phospho-regulated; for example, OTUD4 is activated by phosphorylation to remove K63 chains from MyD88.
• CRISPR knockout, point-mutation, knock-in, and overexpression models are essential to dissect which enzyme directly controls a given substrate's K63 ubiquitination state.
• EDITGENE provides end-to-end CRISPR cell model generation and CRISPR library screening/bioinformatics to map negative regulators of K63-linked ubiquitination.
Description
GO:1900045, negative regulation of protein K63-linked ubiquitination, is a biological process term that captures the cellular mechanisms which reduce or prevent the addition of K63-linked ubiquitin chains to target proteins. K63-linked polyubiquitin is a non-degradative signal that scaffolds protein-protein interactions, and its reversal or inhibition is a critical layer of control in immune signaling, DNA damage responses, and protein quality control. Because K63 chains often act as activating platforms, the enzymes that remove or block them function as molecular brakes that prevent excessive or prolonged signaling. Researchers study this term to understand how cells terminate inflammatory and antiviral signals, how tumors evade immune detection, and how deubiquitinases and E3 ligases shape substrate-specific outcomes. The process is not a single reaction but a collection of regulatory events, including deubiquitination, competitive chain editing, and sequestration of ubiquitin chain donors. Consequently, GO:1900045 is a hub for both mechanistic cell biology and therapeutic target discovery.
negative regulation of protein K63-linked ubiquitination At A Glance
| GO ID | GO:1900045 |
|---|---|
| GO term | negative regulation of protein K63-linked ubiquitination |
| Ontology | biological_process |
| Synonym | inhibition of protein K63-linked ubiquitination; downregulation of protein K63-linked polyubiquitination; negative regulation of protein K63-linked polyubiquitination |
| Major function | Reduces or prevents K63-linked ubiquitin chain attachment on target proteins, thereby limiting non-degradative signaling platforms. |
| Biological context | Immune signaling, DNA damage response, protein quality control, and cancer progression. |
| Key enzyme classes | Deubiquitinases (e.g., OTUD4, OTUD1, PSMD14) and E3 ligases/adaptors (e.g., TRIM35, STUB1). |
| Substrate examples | MyD88, STING, cGAS, UHRF1. |
| Regulation mode | Phospho-activation, substrate recruitment, and competitive chain editing. |
What Is GO:1900045?
In plain terms, GO:1900045 refers to any cellular process that stops, prevents, or reduces the frequency, rate, or extent of attaching K63-linked ubiquitin chains to a protein. This includes the action of deubiquitinases that cleave K63 chains, E3 ligases or adaptors that block chain elongation, and signaling events that downregulate the enzymes responsible for K63-linked ubiquitination. It is a negative regulatory biological process, meaning it opposes the positive process of protein K63-linked ubiquitination.
Why Is negative regulation of protein K63-linked ubiquitination Important in Cell Biology?
Negative regulation of K63-linked ubiquitination is important because K63 chains serve as non-degradative scaffolds that amplify immune and stress signals, and unchecked K63 ubiquitination can drive chronic inflammation, autoimmunity, and tumor immune evasion. Understanding this process reveals how cells terminate signaling at the right time and how pathogens or tumors hijack these brakes. It also identifies druggable nodes, such as deubiquitinases and E3 ligases, that can be targeted to modulate immune responses or overcome therapy resistance.
• Controls termination of MyD88-dependent inflammatory signaling through OTUD4.
• Limits cGAS-STING-mediated antiviral and autoinflammatory responses via TRIM35 and Listerin.
• Supports antigen presentation and anti-tumor immunity; its disruption can impair immune recognition in pancreatic cancer.
• Contributes to cancer progression through STUB1-mediated regulation of UHRF1 in cholangiocarcinoma.
• Modulates synthetic lethality and therapy response in triple-negative breast cancer via PSMD14.
• Regulates neutrophil polarization and immunopathology in periodontitis through OTUD1.
• Maintains ribosome quality control by editing polyubiquitin architecture on collided ribosomes.
• Provides a mechanistic basis for targeting deubiquitinases and E3 ligases in precision oncology.
What Happens During negative regulation of protein K63-linked ubiquitination?
Recognition of K63-linked ubiquitin chains on substrate proteins
In simple terms: First, the cell must find the protein that carries K63-linked ubiquitin chains.
Negative regulation begins with the recognition of K63-linked ubiquitin chains on specific substrate proteins. Deubiquitinases such as OTUD4 and OTUD1 contain ubiquitin-binding domains that selectively engage K63 linkages, allowing them to distinguish K63 chains from other linkage types. In the ribosome quality control pathway, polyubiquitin architecture editing on collided ribosomes requires recognition of specific chain conformations to maintain persistent RQC activity. This step ensures that negative regulation is substrate-specific and linkage-selective.
Deubiquitination and chain cleavage
In simple terms: Enzymes cut the K63 ubiquitin chains off the target protein.
The central event is the cleavage of K63-linked ubiquitin chains by deubiquitinases. OTUD4 is a phospho-activated K63 deubiquitinase that removes K63 chains from MyD88, thereby dampening MyD88-dependent signaling. OTUD1 suppresses secretory neutrophil polarization by deubiquitinating K63-linked substrates, which ameliorates immunopathology in periodontitis. PSMD14, a component of the 19S proteasome, also removes K63 chains and its targeting combined with arachidonic acid induces synthetic lethality in triple-negative breast cancer. These examples show that deubiquitination is a primary mechanism for negative regulation of K63-linked ubiquitination.
E3 ligase-mediated inhibition or redirection of K63 chain formation
In simple terms: Some enzymes block the addition of K63 chains by competing with or redirecting the ubiquitination machinery.
Negative regulation can also occur at the level of chain formation. TRIM35 negatively regulates cGAS-STING signaling by attenuating K63-linked ubiquitination of STING, likely through competitive or inhibitory interactions that prevent chain elongation. STUB1 mediates K63-linked ubiquitination of UHRF1 in cholangiocarcinoma, and its regulation illustrates how E3 ligases can either promote or oppose K63 chain assembly depending on context. Listerin promotes cGAS degradation through the ESCRT pathway, indirectly reducing K63-linked signaling events. Thus, E3 ligases and adaptors can act as brakes by redirecting substrates away from K63 chain assembly.
Downstream consequences for signaling and protein fate
In simple terms: Once K63 chains are removed or blocked, the signal they carried is shut down.
The removal or prevention of K63-linked ubiquitination has diverse downstream effects. In immune signaling, it terminates NF-kB and interferon responses by destabilizing signaling scaffolds. In antigen presentation, IFN-gamma-driven UBE2D3 upregulation impairs antigen presentation pathways, and negative regulation of K63 chains may counter this effect. In cancer, loss of K63 chain brakes can promote DNA hypermethylation and tumor progression, as seen with UHRF1 in cholangiocarcinoma. In ribosome quality control, polyubiquitin architecture editing maintains RQC activity on collided ribosomes. These outcomes highlight the broad physiological impact of this process.
Key Genes Involved in GO:1900045 negative regulation of protein K63-linked ubiquitination
The following genes and proteins are experimentally implicated in negative regulation of protein K63-linked ubiquitination or in the K63-linked ubiquitination pathways they control.
| Gene | Major Role | Research Relevance |
|---|---|---|
| OTUD4 | Phospho-activated K63 deubiquitinase that removes K63 chains from MyD88 | Regulates MyD88-dependent inflammatory signaling |
| OTUD1 | Deubiquitinase that suppresses secretory neutrophil polarization | Ameliorates immunopathology of periodontitis |
| PSMD14 | Proteasome-associated deubiquitinase that removes K63 chains | Targeting induces synthetic lethality in triple-negative breast cancer |
| TRIM35 | E3 ligase that attenuates K63-linked ubiquitination of STING | Negatively regulates cGAS-STING signaling |
| STUB1 | E3 ligase mediating K63-linked ubiquitination of UHRF1 | Promotes cholangiocarcinoma progression via DNA hypermethylation |
| UHRF1 | Substrate of STUB1-mediated K63 ubiquitination | Maintains DNA hypermethylation of PLA2G2A in cholangiocarcinoma |
| MyD88 | Substrate of OTUD4-mediated K63 deubiquitination | Central adaptor in inflammatory signaling |
| STING | Substrate of TRIM35-mediated attenuation of K63 ubiquitination | Key adaptor in cGAS-STING antiviral signaling |
| cGAS | Substrate regulated by Listerin-mediated degradation | Negatively regulates cGAS-mediated immune response |
| Listerin | E3 ligase promoting cGAS degradation via ESCRT | Negatively regulates cGAS-mediated immune response |
| UBE2D3 | E2 conjugating enzyme upregulated by IFN-gamma | Impairs antigen presentation in pancreatic cancer |
| FADS1 | Target of m6A modification in TNBC | Linked to PSMD14 targeting and synthetic lethality |
| PLA2G2A | Downstream target of UHRF1-mediated hypermethylation | Tumor suppressor-like role in cholangiocarcinoma |
| RQC components | Edit polyubiquitin architecture on collided ribosomes | Maintain persistent RQC activity |
| ESCRT pathway | Mediates cGAS degradation | Negatively regulates cGAS-mediated immune response |
| NF-kB signaling | Downstream pathway affected by K63 chain removal | Inflammatory and immune regulation |
| Interferon signaling | Downstream pathway affected by K63 chain removal | Antiviral and anti-tumor immunity |
How Is negative regulation of protein K63-linked ubiquitination Regulated?
The process of negative regulation of protein K63-linked ubiquitination is itself regulated at multiple levels. OTUD4 is phospho-activated, meaning its deubiquitinase activity toward K63 chains on MyD88 requires phosphorylation, providing a switch that couples upstream kinases to signal termination. OTUD1 activity is linked to neutrophil polarization states, suggesting that cellular differentiation cues regulate its function. PSMD14 is a proteasome-associated deubiquitinase whose targeting can be exploited by metabolic interventions such as arachidonic acid, indicating that cellular metabolism influences K63 chain removal. In ribosome quality control, polyubiquitin architecture editing on collided ribosomes is dynamically regulated to maintain persistent RQC activity, showing that chain editing is tuned to translation stress. These examples demonstrate that negative regulation of K63-linked ubiquitination is not constitutive but responsive to phosphorylation, metabolism, and stress signals.
negative regulation of protein K63-linked ubiquitination and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| STUB1/UHRF1 | Cholangiocarcinoma progression via DNA hypermethylation | Knockout of STUB1 in cholangiocarcinoma cell lines; UHRF1 point-mutation |
| PSMD14/FADS1 | Triple-negative breast cancer synthetic lethality | PSMD14 knockout combined with arachidonic acid treatment; FADS1 m6A knock-in |
| OTUD4/MyD88 | Inflammatory signaling and autoimmunity | OTUD4 phospho-mutant knock-in; MyD88 K63 ubiquitination reporter |
| TRIM35/STING | cGAS-STING-mediated autoinflammation | TRIM35 knockout and STING K63 mutant knock-in |
| OTUD1 | Periodontitis immunopathology | OTUD1 knockout in neutrophil models; overexpression in inflammatory cells |
Cancer progression and therapy resistance
Dysregulation of K63-linked ubiquitination brakes contributes to cancer. STUB1-mediated K63-linked ubiquitination of UHRF1 promotes cholangiocarcinoma progression by maintaining DNA hypermethylation of PLA2G2A, suggesting that targeting this axis could reverse epigenetic silencing. In triple-negative breast cancer, targeting PSMD14 combined with arachidonic acid induces synthetic lethality via FADS1 m6A modification, highlighting a metabolic vulnerability linked to K63 deubiquitination. IFN-gamma-driven UBE2D3 upregulation impairs antigen presentation pathways and anti-tumor immunity in pancreatic cancer, indicating that K63-linked ubiquitination events shape immune evasion. These findings position negative regulators of K63 chains as potential therapeutic targets.
Inflammatory and autoimmune signaling
K63-linked ubiquitination is a key activating signal in innate immunity, and its negative regulation prevents excessive inflammation. OTUD4 removes K63 chains from MyD88 to dampen MyD88-dependent signaling, and its phospho-activation provides a checkpoint against uncontrolled inflammation. OTUD1 suppresses secretory neutrophil polarization and ameliorates immunopathology of periodontitis, linking K63 deubiquitination to tissue-protective anti-inflammatory effects. TRIM35 negatively regulates cGAS-STING signaling by attenuating K63-linked ubiquitination of STING, which is critical for preventing autoinflammatory responses to self-DNA. Listerin promotes cGAS degradation through the ESCRT pathway to negatively regulate cGAS-mediated immune response, further illustrating how K63 chain brakes prevent autoimmunity.
Protein quality control and ribosome stress
K63-linked ubiquitination is not only an immune signal but also a quality control signal on damaged proteins and collided ribosomes. Polyubiquitin architecture editing on collided ribosomes maintains persistent RQC activity, and negative regulation of K63 chains may help reset or terminate quality control cycles. This connection links GO:1900045 to ribosomopathies and neurodegenerative diseases where protein quality control is impaired. Although direct disease associations for this specific term are still emerging, the mechanistic overlap with RQC and ESCRT pathways suggests broad relevance.
From negative regulation of protein K63-linked ubiquitination-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is a candidate deubiquitinase required for removing K63 chains from a substrate? | CRISPR knockout of the deubiquitinase followed by K63 ubiquitination assays |
| Does a specific phosphorylation site control deubiquitinase activity? | Point-mutation knock-in of phospho-dead or phospho-mimetic residues |
| Does an E3 ligase attenuate K63 chain formation on an immune adaptor? | Knockout and tagged knock-in of the E3 ligase with STING or cGAS reporters |
| Can overexpression of a negative regulator suppress inflammatory signaling? | Overexpression cell models with NF-kB or interferon reporters |
| Which genes modulate K63-linked ubiquitination at a systems level? | CRISPR library screening with K63 ubiquitination readouts |
| Does a disease-associated mutation alter K63 chain editing? | Knock-in of patient-derived mutations in deubiquitinases or substrates |
How to Study the negative regulation of protein K63-linked ubiquitination Process
| Method | What It Measures | Typical Application |
|---|---|---|
| K63 linkage-specific immunoblot | Abundance of K63-linked ubiquitin chains on a substrate | Validation of deubiquitinase or E3 ligase effects |
| In vitro deubiquitination assay | Direct cleavage of K63 chains by a purified enzyme | Confirming catalytic activity of OTUD4 or OTUD1 |
| DiGly proteomics | Global K63 ubiquitination site changes | Mapping substrate repertoires upon knockout |
| Co-immunoprecipitation | Physical interaction between regulator and substrate | Identifying adaptors and complexes |
| CRISPR knockout library screen | Genes whose loss alters K63 ubiquitination or signaling | Unbiased discovery of negative regulators |
| Reporter cell assays | NF-kB or interferon activation status | Functional readout of K63 chain brakes |
| Live-cell imaging | Spatiotemporal dynamics of K63 chains | Visualizing STING or MyD88 trafficking |
| Bioinformatics pathway enrichment | Overrepresentation of K63-related genes in screen hits | Prioritizing candidates for validation |
Ubiquitination assays and chain-specific detection
Detecting K63-linked ubiquitination requires linkage-specific reagents such as K63-specific antibodies or TUBE probes. Co-immunoprecipitation of substrate proteins followed by immunoblotting with K63 linkage-specific antibodies can reveal changes in chain abundance. In vitro deubiquitination assays using recombinant enzymes and K63-linked ubiquitin chains can confirm direct catalytic activity. These methods are foundational for validating negative regulators identified by screening.
Proteomics and interactome mapping
Mass spectrometry-based proteomics can map K63 ubiquitination sites and identify interactors of deubiquitinases and E3 ligases. DiGly remnant profiling after trypsin digestion enriches K63-linked peptides and quantifies changes upon knockout or overexpression of candidate regulators. Affinity purification of tagged enzymes followed by mass spectrometry reveals substrate repertoires and adaptor proteins. These approaches provide systems-level views of the K63 ubiquitination landscape.
CRISPR screening and functional genomics
CRISPR knockout libraries coupled with K63 ubiquitination or signaling readouts enable unbiased discovery of negative regulators. For example, targeting PSMD14 was identified as a synthetic lethal interaction in triple-negative breast cancer, and IFN-gamma-driven UBE2D3 upregulation was linked to antigen presentation defects. Pooled screens with reporters for NF-kB or interferon activation can identify genes whose loss increases K63 chain abundance. Bioinformatics integration of screen hits with pathway databases refines candidate lists.
Imaging and cellular assays
Fluorescence microscopy with tagged ubiquitin or substrate reporters can visualize K63 chain dynamics in live cells. Co-localization of deubiquitinases with substrate puncta, such as STING at the Golgi, provides spatial information. Neutrophil polarization assays can measure functional consequences of OTUD1 modulation. These cellular assays complement biochemical and proteomic methods.
How CRISPR Can Be Used to Study GO:1900045 negative regulation of protein K63-linked ubiquitination
Knockout
CRISPR knockout is the primary approach to test whether a candidate gene is required for negative regulation of K63-linked ubiquitination. Knocking out a deubiquitinase such as OTUD4 or OTUD1 is expected to increase K63 chain abundance on substrates and enhance downstream signaling. Knockout of TRIM35 would be predicted to elevate K63-linked ubiquitination of STING and amplify cGAS-STING signaling. These models provide loss-of-function evidence for causal roles.
Point Mutation
Point-mutation knock-in allows precise interrogation of catalytic residues or regulatory phosphorylation sites. For example, mutating the catalytic cysteine of OTUD4 or the phospho-acceptor site required for its activation can distinguish enzyme activity from scaffolding functions. Similarly, point mutations in STING at K63 ubiquitination acceptor lysines can test whether TRIM35-mediated attenuation depends on those sites. These models are essential for mechanistic dissection.
Knock-in
Tagged knock-in of endogenous genes with epitope tags or fluorescent proteins enables physiological tracking of K63 chain regulators. Knocking in a tag on OTUD4 or TRIM35 allows endogenous expression-level analysis and interactome capture without overexpression artifacts. Knock-in of K63 ubiquitination site mutants in substrates such as MyD88 or STING provides definitive evidence for site-specific regulation. These models bridge in vitro biochemistry and in vivo physiology.
Overexpression
Overexpression models are useful for gain-of-function studies and for testing whether a candidate regulator is sufficient to suppress K63-linked ubiquitination. Overexpressing OTUD1 or TRIM35 can reduce K63 chain abundance and dampen inflammatory or interferon responses. Overexpression of STUB1 or UHRF1 can drive K63-dependent oncogenic phenotypes in cholangiocarcinoma models. These systems complement knockout studies by establishing sufficiency.
How EDITGENE Supports negative regulation of protein K63-linked ubiquitination Research
Researchers studying negative regulation of protein K63-linked ubiquitination-related genes often need to determine whether a candidate gene is causally involved in chain removal, chain attenuation, or downstream signaling. This requires precisely engineered cell models that can isolate enzyme activity, substrate specificity, and signaling outcomes.
Contact EDITGENE today to design your custom CRISPR model for negative regulation of protein K63-linked ubiquitination research.
Frequently Asked Questions About negative regulation of protein K63-linked ubiquitination
What is GO:1900045?
GO:1900045 is the Gene Ontology biological process term for negative regulation of protein K63-linked ubiquitination, meaning any process that stops, prevents, or reduces the frequency, rate, or extent of attaching K63-linked ubiquitin chains to a protein.
What genes are involved in negative regulation of protein K63-linked ubiquitination?
Key genes include deubiquitinases such as OTUD4, OTUD1, and PSMD14, and E3 ligases such as TRIM35 and STUB1, along with substrates like MyD88, STING, cGAS, and UHRF1.
How does K63-linked ubiquitination differ from K48-linked ubiquitination?
K63-linked ubiquitination is non-degradative and serves as a signaling scaffold, whereas K48-linked chains typically target proteins for proteasomal degradation; negative regulation of K63 chains therefore modulates signaling rather than protein stability.
Which enzymes remove K63-linked ubiquitin chains?
Deubiquitinases such as OTUD4, OTUD1, and PSMD14 can cleave K63-linked chains, and their activity is often regulated by phosphorylation or cellular context.
Why is negative regulation of K63-linked ubiquitination important in cancer?
It can suppress oncogenic signaling or immune evasion; for example, STUB1-mediated K63 ubiquitination of UHRF1 promotes cholangiocarcinoma, while PSMD14 targeting induces synthetic lethality in triple-negative breast cancer.
How is OTUD4 regulated?
OTUD4 is a phospho-activated K63 deubiquitinase, meaning phosphorylation is required for its activity toward substrates such as MyD88.
What role does TRIM35 play in cGAS-STING signaling?
TRIM35 negatively regulates cGAS-STING signaling by attenuating K63-linked ubiquitination of STING.
Can CRISPR screens identify negative regulators of K63-linked ubiquitination?
Yes, pooled CRISPR knockout or activation screens with K63 ubiquitination or signaling readouts can uncover novel regulators, as demonstrated by studies linking PSMD14 and UBE2D3 to these pathways.
What experimental models are used to study this process?
Common models include CRISPR knockout, point-mutation knock-in, tagged knock-in, and overexpression cell lines, combined with K63 linkage-specific immunoblotting, proteomics, and reporter assays.
Is negative regulation of K63-linked ubiquitination linked to inflammation?
Yes, it dampens inflammatory signaling; OTUD4 removes K63 chains from MyD88, and OTUD1 suppresses neutrophil polarization to ameliorate periodontitis immunopathology.
Conclusion
GO:1900045, negative regulation of protein K63-linked ubiquitination, is a critical biological process that controls the duration and intensity of non-degradative ubiquitin signaling. Through deubiquitinases such as OTUD4, OTUD1, and PSMD14, and E3 ligases such as TRIM35 and STUB1, cells prevent excessive K63 chain accumulation on substrates like MyD88, STING, cGAS, and UHRF1. This process is essential for immune homeostasis, cancer suppression, and protein quality control, and its dysregulation contributes to inflammatory disease and tumor progression. Continued research using CRISPR-engineered cell models and functional genomics will clarify how these brakes are wired and how they can be therapeutically targeted.
References
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- 2. Yu Y et al.. 2025. Targeting PSMD14 combined with arachidonic acid induces synthetic lethality via FADS1 m(6)A modification in triple-negative breast cancer.. Sci Adv 11(19):eadr3173 PMID: 40344056
- 3. Zhao Y et al.. 2018. OTUD4 Is a Phospho-Activated K63 Deubiquitinase that Regulates MyD88-Dependent Signaling.. Mol Cell 69(3):505-516.e5 PMID: 29395066
- 4. Wang S et al.. 2025. IFN-γ-driven UBE2D3 upregulation impairs antigen presentation pathways and anti-tumor immunity in pancreatic cancer.. Nat Commun 16(1):10733 PMID: 41315272
- 5. Tomomatsu S et al.. 2025. Polyubiquitin architecture editing on collided ribosomes maintains persistent RQC activity.. EMBO J 44(21):6051-6077 PMID: 40957981
- 6. Qin F et al.. 2023. Listerin promotes cGAS protein degradation through the ESCRT pathway to negatively regulate cGAS-mediated immune response.. Proc Natl Acad Sci U S A 120(52):e2308853120 PMID: 38109536
- 7. Song J et al.. 2023. The Deubiquitinase OTUD1 Suppresses Secretory Neutrophil Polarization And Ameliorates Immunopathology of Periodontitis.. Adv Sci (Weinh) 10(30):e2303207 PMID: 37639212
- 8. Zhang J et al.. 2025. TRIM35 Negatively Regulates the cGAS-STING-Mediated Signaling Pathway by Attenuating K63-Linked Ubiquitination of STING.. Inflammation 48(2):855-869 PMID: 39088122
