GO:1990167 protein K27-linked deubiquitination: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1990167 describes the removal of K27-linked polyubiquitin chains from substrate proteins by deubiquitinating enzymes (DUBs).
• K27-linked ubiquitination is atypical and often serves non-degradative signaling roles in immunity, DNA damage response, and kinase activation.
• Key DUBs include USP8, OTUD6A, USP9X, OTUD4, UCHL3, JOSD2, and USP1, which act on substrates such as DDX3X, AKT, STAT1, CDK1, cGAS, and STING.
• Dysregulation of K27-linked deubiquitination contributes to cancer chemoresistance, glioblastoma progression, colitis, and type I interferonopathies.
• Studying this process requires integrated approaches: CRISPR knockout/knock-in models, ubiquitin chain-specific antibodies, mass spectrometry, and functional assays.
• EDITGENE provides CRISPR cell model services to dissect K27-linked deubiquitination mechanisms and identify therapeutic targets.
Description
Protein K27-linked deubiquitination (GO:1990167) is a biological process that removes ubiquitin chains linked through lysine 27 (K27) of ubiquitin from target proteins. Unlike the canonical K48-linked chains that target proteins for proteasomal degradation, K27-linked polyubiquitin often acts as a non-degradative signal that modulates protein-protein interactions, kinase activation, and immune signaling. This process is catalyzed by specialized deubiquitinating enzymes (DUBs) that cleave the isopeptide bond between K27 of one ubiquitin and the C-terminal glycine of the next, thereby reversing the modification. Researchers are increasingly interested in K27-linked deubiquitination because it sits at the crossroads of innate immunity, cell cycle control, and cancer chemoresistance. For example, the DUB OTUD6A removes K27-linked ubiquitin from AKT to modulate chemoresistance in cancer, while USP9X deubiquitinates STAT1 via K27 linkages to attenuate colitis. The specificity of these enzymes for K27 chains is critical for cellular homeostasis, and their dysregulation is linked to diseases ranging from glioblastoma to type I interferonopathies. Understanding GO:1990167 requires knowledge of the enzymes involved, the substrates they act on, and the downstream signaling consequences. This article synthesizes current evidence from QuickGO and PubMed to provide a research-grade overview of the mechanisms, key genes, disease relevance, and experimental models used to study K27-linked deubiquitination.
protein K27-linked deubiquitination At A Glance
| GO ID | GO:1990167 |
|---|---|
| GO term | protein K27-linked deubiquitination |
| Ontology | biological_process |
| Synonym | None |
| Major function | Removal of K27-linked polyubiquitin chains from substrate proteins by DUBs, modulating signaling and stability |
| Key enzymes | USP8, OTUD6A, USP9X, OTUD4, UCHL3, JOSD2, USP1 |
| Substrates | DDX3X, AKT, STAT1, CDK1, cGAS, STING, SAR1A |
| Associated diseases | Cancer chemoresistance, glioblastoma, colitis, type I interferonopathies |
| Research methods | CRISPR KO/KI, ubiquitin chain-specific antibodies, mass spectrometry, functional assays |
What Is GO:1990167?
GO:1990167, protein K27-linked deubiquitination, is defined as a protein deubiquitination process in which a K27-linked ubiquitin chain—a polymer of ubiquitin formed by linkages between lysine residues at position 27 of the ubiquitin monomers—is removed from a protein. This process is mediated by deubiquitinating enzymes (DUBs) that specifically recognize and cleave K27-linked polyubiquitin chains, reversing the post-translational modification and altering the substrate's function, localization, or stability.
Why Is protein K27-linked deubiquitination Important in Cell Biology?
Protein K27-linked deubiquitination is important because it provides a reversible switch for non-degradative ubiquitin signaling, influencing immune responses, cell proliferation, and stress adaptation. Dysregulation of this process can lead to uncontrolled inflammation, cancer progression, and chemoresistance, making the enzymes and substrates involved attractive therapeutic targets.
• Regulates innate immune signaling by reversing K27-linked ubiquitination on adaptors like DDX3X and cGAS.
• Modulates kinase activation, including AKT and CDK1, affecting cancer cell survival and chemoresistance.
• Controls inflammatory responses through deubiquitination of STAT1 in macrophages.
• Influences DNA damage response and genome stability via K27-linked chains on repair proteins.
• Affects type I interferon production and antitumor immunity through STING trafficking.
• Provides a mechanism for fine-tuning protein function without degradation, distinct from K48-linked pathways.
• Dysregulation is linked to glioblastoma, colitis, and interferonopathies.
• Enzymes like OTUD6A and USP9X are potential drug targets for cancer and inflammatory diseases.
• K27-linked chains can act as kinetic traps for some DUBs, adding regulatory complexity.
• CRISPR-based models are essential to dissect causal roles of DUBs in disease.
What Happens During protein K27-linked deubiquitination?
Recognition of K27-linked ubiquitin chains
In simple terms: The deubiquitinating enzyme finds and binds to the specific K27-linked ubiquitin chain on a target protein.
DUBs such as OTUD6A and USP9X contain domains that selectively recognize K27-linked polyubiquitin chains. For example, OTUD6A binds to K27-linked chains on AKT, while USP9X recognizes K27-linked chains on STAT1. This recognition is crucial for specificity, as different ubiquitin linkages encode distinct signals.
Cleavage of the isopeptide bond
In simple terms: The enzyme cuts the bond between ubiquitin molecules, removing the chain from the substrate.
Once bound, the catalytic domain of the DUB cleaves the isopeptide bond between the C-terminal glycine of one ubiquitin and lysine 27 of the next ubiquitin in the chain. This reaction releases the ubiquitin chain and free substrate. For instance, USP8 deubiquitinates DDX3X by cleaving K27-linked chains, thereby modulating its function in stress granules.
Substrate fate after deubiquitination
In simple terms: After the chain is removed, the target protein changes its behavior, such as becoming active or changing location.
Removal of K27-linked chains can alter substrate stability, localization, or interaction partners. For example, deubiquitination of AKT by OTUD6A promotes its activation and downstream signaling, contributing to chemoresistance. Similarly, USP9X-mediated deubiquitination of STAT1 restricts its activity and attenuates colitis.
Downstream signaling consequences
In simple terms: The removal of K27 chains triggers a cascade of cellular responses, like immune activation or cell survival.
K27-linked deubiquitination impacts pathways such as type I interferon production, MAPK signaling, and DNA damage response. For example, JOSD2 deubiquitinates cGAS to facilitate immune evasion in colorectal cancer, while USP1 inhibition enhances STING trafficking and antitumor immunity via SAR1A deubiquitination.
Key Genes Involved in GO:1990167 protein K27-linked deubiquitination
The following genes encode deubiquitinating enzymes or substrates that are directly implicated in K27-linked deubiquitination, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| USP8 | Deubiquitinates DDX3X via K27-linked chains | Type I interferonopathies, stress granule regulation |
| OTUD6A | Removes K27-linked ubiquitin from AKT | Cancer chemoresistance, AKT signaling |
| USP9X | Deubiquitinates STAT1 via K27 linkages | Colitis, macrophage inflammation |
| OTUD4 | Deubiquitinates CDK1, activates MAPK pathway | Glioblastoma progression |
| UCHL3 | Hydrolyzes K27-linked diubiquitin | Enzyme kinetics, ubiquitin chain recognition |
| JOSD2 | Deubiquitinates cGAS | Colorectal cancer immune evasion |
| USP1 | Regulates SAR1A ubiquitination and STING trafficking | Radiation-induced antitumor immunity |
| DDX3X | Substrate of USP8 | Stress granule formation, innate immunity |
| AKT | Substrate of OTUD6A | Cell survival, chemoresistance |
| STAT1 | Substrate of USP9X | Inflammatory signaling, colitis |
| CDK1 | Substrate of OTUD4 | Cell cycle, glioblastoma |
| cGAS | Substrate of JOSD2 | DNA sensing, immune evasion |
| STING | Indirectly regulated by USP1 via SAR1A | Type I interferon, antitumor immunity |
| TRIF | Regulated by K27-linked polyubiquitination and deubiquitination | Innate immune response |
| SAR1A | Substrate of USP1-mediated deubiquitination | STING trafficking |
How Is protein K27-linked deubiquitination Regulated?
K27-linked deubiquitination is regulated at multiple levels. The expression and activity of DUBs can be controlled by transcription, post-translational modifications, and interacting partners. For example, OTUD6A and TRIM21 orchestrate AKT K27-linked ubiquitination in a dynamic balance that modulates chemoresistance. Similarly, USP9X activity towards STAT1 is regulated by upstream signals in macrophages. The specificity of DUBs for K27 chains can also be influenced by the presence of other ubiquitin linkages and the conformation of the substrate. Additionally, K27-linked chains themselves can act as kinetic traps for certain DUBs, adding another layer of regulation.
protein K27-linked deubiquitination and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| OTUD6A | Cancer chemoresistance | CRISPR knockout in cancer cell lines, xenograft models |
| USP9X | Colitis | Macrophage-specific knockout mice, DSS-induced colitis |
| OTUD4 | Glioblastoma | Patient-derived glioblastoma cells, orthotopic xenografts |
| JOSD2 | Colorectal cancer immune evasion | CRISPR knockout in colorectal cancer cells, syngeneic models |
| USP1 | Radiation-induced antitumor immunity | Knockout cells, radiation therapy models |
Cancer chemoresistance and glioblastoma
Dysregulated K27-linked deubiquitination promotes cancer progression and resistance to therapy. OTUD6A removes K27-linked ubiquitin from AKT, enhancing AKT activation and chemoresistance in cancer cells. OTUD4 deubiquitinates CDK1 and activates MAPK signaling, driving glioblastoma progression. Targeting these DUBs could sensitize tumors to chemotherapy.
Inflammatory and autoimmune diseases
K27-linked deubiquitination controls inflammatory signaling. USP9X deubiquitinates STAT1 via K27 linkages, attenuating colitis by restricting oncostatin M production. In type I interferonopathies, USP8 deubiquitinates DDX3X in stress granules, potentiating cGAS-mediated interferon responses. These findings highlight the role of K27-linked deubiquitination in balancing immune activation and tolerance.
Immune evasion in colorectal cancer
JOSD2 deubiquitinates cGAS, facilitating immune evasion in colorectal cancer. Similarly, USP1 inhibition enhances oligo-ubiquitinated SAR1A-mediated STING trafficking and activation, boosting radiation-induced antitumor immunity. These studies demonstrate that K27-linked deubiquitination is a key regulator of antitumor immune responses.
From protein K27-linked deubiquitination-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of OTUD6A reverse chemoresistance? | OTUD6A knockout cancer cell lines and xenografts |
| How does USP9X K27-deubiquitination of STAT1 affect colitis? | USP9X conditional knockout mice, DSS colitis model |
| What is the role of OTUD4 in glioblastoma progression? | OTUD4 knockout glioblastoma cells, orthotopic xenografts |
| Can JOSD2 inhibition enhance antitumor immunity? | JOSD2 knockout colorectal cancer cells, syngeneic mouse models |
| Does USP1 inhibition potentiate radiation therapy? | USP1 knockout cells, radiation treatment, STING reporter assays |
| How does K27-linked chain recognition occur structurally? | Point mutations in DUB catalytic domains, ubiquitin chain binding assays |
How to Study the protein K27-linked deubiquitination Process
| Method | What It Measures | Typical Application |
|---|---|---|
| K27-linkage-specific antibodies | Presence of K27-linked ubiquitin chains | Western blot, immunoprecipitation |
| Mass spectrometry | Ubiquitin chain topology and substrate identification | Proteomic profiling of DUB substrates |
| CRISPR knockout | Loss-of-function effects on deubiquitination | Functional studies of DUBs |
| CRISPR knock-in | Tagged or mutant DUB expression | Localization and interaction studies |
| Luciferase reporter assays | Interferon or NF-kB pathway activation | Immune signaling downstream of deubiquitination |
| In vitro deubiquitination assays | Enzymatic activity of DUBs on K27 chains | Kinetic and specificity studies |
| Co-immunoprecipitation | Protein-protein interactions | DUB-substrate binding |
Ubiquitin chain-specific detection
To study K27-linked deubiquitination, researchers use linkage-specific antibodies or mass spectrometry to detect K27-linked ubiquitin chains on substrates. For example, K27-linked polyubiquitination of TRIF was characterized using such methods. These tools allow monitoring of chain removal after DUB manipulation.
CRISPR-based functional screens
CRISPR knockout or knock-in models are used to dissect the roles of DUBs and substrates. For instance, OTUD6A knockout revealed its role in AKT deubiquitination and chemoresistance. Similarly, USP9X knockout in macrophages demonstrated its anti-inflammatory function.
Proteomics and interactomics
Mass spectrometry-based proteomics can identify DUB substrates and interacting partners. For example, OTUD4 was shown to deubiquitinate CDK1 using proteomic approaches. These methods help map the K27-linked deubiquitination network.
Functional assays for immune signaling
Reporter assays for type I interferon and NF-kB activation are used to measure downstream effects of K27-linked deubiquitination. For example, USP8-mediated deubiquitination of DDX3X was linked to enhanced cGAS-mediated interferon production using such assays. Similarly, JOSD2 and USP1 effects on cGAS-STING were assessed.
How CRISPR Can Be Used to Study GO:1990167 protein K27-linked deubiquitination
Knockout
CRISPR knockout of DUBs such as OTUD6A, USP9X, OTUD4, JOSD2, and USP1 has been used to demonstrate their roles in K27-linked deubiquitination and downstream phenotypes. For example, OTUD6A knockout reversed chemoresistance in cancer cells, and USP9X knockout exacerbated colitis in mice.
Point Mutation
Point mutations in the catalytic domain of DUBs or in the K27 residue of ubiquitin can be introduced using CRISPR to study specificity. For instance, mutating the catalytic cysteine of UCHL3 affects its ability to hydrolyze K27-linked diubiquitin. Such models help dissect enzyme mechanism and substrate recognition.
Knock-in
Knock-in of tagged ubiquitin or DUBs (e.g., HA-ubiquitin, GFP-USP8) allows tracking of K27-linked chains and enzyme localization. For example, tagged DDX3X was used to study its deubiquitination by USP8 in stress granules. Knock-in models are valuable for real-time imaging and biochemical isolation.
Overexpression
Overexpression of DUBs or substrates via CRISPR activation or lentiviral delivery can amplify K27-linked deubiquitination signals. For example, overexpression of OTUD6A enhanced AKT activation and chemoresistance, while USP9X overexpression suppressed STAT1 activity. These models are useful for gain-of-function studies.
How EDITGENE Supports protein K27-linked deubiquitination Research
Researchers studying protein K27-linked deubiquitination-related genes often need to determine whether a candidate gene is causally involved in a specific signaling pathway or disease phenotype. This requires precise genetic models that can knockout, mutate, tag, or overexpress the gene of interest in relevant cell types.
Contact EDITGENE today to design your custom CRISPR model for protein K27-linked deubiquitination research.
Frequently Asked Questions About protein K27-linked deubiquitination
What is protein K27-linked deubiquitination?
It is the removal of K27-linked polyubiquitin chains from proteins by deubiquitinating enzymes, reversing a non-degradative ubiquitin signal.
What genes are involved in protein K27-linked deubiquitination?
Key genes include USP8, OTUD6A, USP9X, OTUD4, UCHL3, JOSD2, and USP1, which encode DUBs acting on substrates like DDX3X, AKT, STAT1, CDK1, cGAS, and STING.
How does K27-linked deubiquitination differ from K48-linked deubiquitination?
K48-linked chains typically target proteins for degradation, while K27-linked chains often modulate signaling without degradation, and are removed by specific DUBs.
What diseases are associated with K27-linked deubiquitination?
It is linked to cancer chemoresistance, glioblastoma, colitis, type I interferonopathies, and immune evasion in colorectal cancer.
Which DUBs specifically remove K27-linked ubiquitin?
OTUD6A, USP9X, USP8, OTUD4, JOSD2, and USP1 have been shown to remove K27-linked chains from specific substrates.
How can I study K27-linked deubiquitination in the lab?
Use K27-linkage-specific antibodies, mass spectrometry, CRISPR knockout/knock-in models, and functional reporter assays.
What is the role of OTUD6A in cancer?
OTUD6A deubiquitinates AKT via K27 linkages, promoting AKT activation and chemoresistance in cancer cells.
How does USP9X affect inflammation?
USP9X deubiquitinates STAT1 via K27 linkages, restricting oncostatin M production and attenuating colitis.
Can CRISPR be used to study K27-linked deubiquitination?
Yes, CRISPR knockout, knock-in, point mutation, and overexpression models are widely used to dissect DUB functions and substrate interactions.
What services does EDITGENE offer for K27-linked deubiquitination research?
EDITGENE provides CRISPR knockout, point mutation, knock-in, overexpression cell models, library screening, and bioinformatics services.
Conclusion
Protein K27-linked deubiquitination (GO:1990167) is a critical regulatory process that reverses non-degradative ubiquitin signaling on key substrates involved in immunity, cancer, and inflammation. The growing list of DUBs and substrates underscores its importance in human disease, from chemoresistance to interferonopathies. Continued research using advanced CRISPR models and proteomic tools will further illuminate this pathway and reveal new therapeutic opportunities.
References
- 1. Zhang X et al.. 2024. Stress granule-localized USP8 potentiates cGAS-mediated type I interferonopathies through deubiquitination of DDX3X.. Cell Rep 43(6):114248 PMID: 38795350
- 2. Jiang Q et al.. 2026. TRIM21 and OTUD6A orchestrate AKT K27-linked atypical ubiquitination to modulate cancer chemoresistance.. Nat Struct Mol Biol 33(1):84-99 PMID: 41188598
- 3. Zhang T et al.. 2026. Macrophage USP9X attenuates colitis by restricting oncostatin M production via K27-linked deubiquitination of STAT1.. Cell Mol Immunol 23(7):806-822 PMID: 42209766
- 4. Wu X et al.. 2019. Regulation of TRIF-mediated innate immune response by K27-linked polyubiquitination and deubiquitination.. Nat Commun 10(1):4115 PMID: 31511519
- 5. Ci M et al.. 2024. OTUD4 promotes the progression of glioblastoma by deubiquitinating CDK1 and activating MAPK signaling pathway.. Cell Death Dis 15(3):179 PMID: 38429268
- 6. van Tilburg GBA et al.. 2021. K27-Linked Diubiquitin Inhibits UCHL3 via an Unusual Kinetic Trap.. Cell Chem Biol 28(2):191-201.e8 PMID: 33238157
- 7. Du J et al.. 2025. Deubiquitinating enzyme JOSD2 modulates cGAS to facilitate immune evasion in colorectal cancer.. Oncoimmunology 14(1):2590245 PMID: 41351298
- 8. Zhou W et al.. 2025. Targeting USP1 Potentiates Radiation-Induced Type I IFN-Dependent Antitumor Immunity by Enhancing Oligo-Ubiquitinated SAR1A-Mediated STING Trafficking and Activation.. Adv Sci (Weinh) 12(15):e2412687 PMID: 39976106
