GO:0140950 histone H2A deubiquitinase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0140950 histone H2A deubiquitinase activity describes the enzymatic removal of ubiquitin from histone H2A, a key chromatin modification that regulates gene expression.
• The Polycomb repressive deubiquitinase complex PR-DUB, containing BAP1 and ASXL proteins, is the principal enzyme complex that catalyzes this reaction in metazoans.
• BAP1/ASXL1 specifically cleaves ubiquitin from histone H2A lysine 119 (H2AK119ub1), a mark deposited by Polycomb repressive complex 1 (PRC1).
• This activity is conserved across eukaryotes, with the Arabidopsis UBP5 enzyme performing an analogous function to counteract Polycomb-mediated repression.
• Dysregulation of histone H2A deubiquitinase activity is implicated in cancers such as mesothelioma and myeloma, and in immune regulation.
• Studying this activity requires integrated approaches including knockout models, structural biology, and genome-wide profiling of H2AK119ub1.
Description
Histone H2A deubiquitinase activity (GO:0140950) is a molecular function that removes ubiquitin from histone H2A, reversing a key epigenetic mark involved in gene silencing. This activity is essential for balancing ubiquitination and deubiquitination on chromatin, thereby influencing transcription, development, and genome stability. The Polycomb repressive deubiquitinase (PR-DUB) complex, containing BAP1 and ASXL proteins, was the first identified enzyme complex with this activity, and it specifically targets histone H2A lysine 119 ubiquitination (H2AK119ub1). Since its discovery, histone H2A deubiquitinases have been recognized as critical regulators of Polycomb-mediated repression and are linked to various human diseases, including cancer and immune disorders. Understanding the mechanism, regulation, and research methods for this activity is therefore of broad interest to biomedical researchers.
histone H2A deubiquitinase activity At A Glance
| GO ID | GO:0140950 |
|---|---|
| GO term | histone H2A deubiquitinase activity |
| Ontology | molecular_function |
| Synonym | histone H2A deubiquitination |
| Definition | A histone deubiquitinase that cleaves ubiquitin from a histone H2A protein to which it is conjugated. |
| Major function | Removal of ubiquitin from histone H2A, particularly H2AK119ub1, to regulate chromatin state and transcription. |
| Key enzyme complex | Polycomb repressive deubiquitinase (PR-DUB) complex containing BAP1 and ASXL proteins. |
| Substrate specificity | Histone H2A, with a preference for ubiquitinated lysine 119 (H2AK119ub1). |
| Conservation | Present in metazoans and plants, e.g., Arabidopsis UBP5. |
What Is GO:0140950?
Histone H2A deubiquitinase activity is defined by the Gene Ontology as a histone deubiquitinase that cleaves ubiquitin from a histone H2A protein to which it is conjugated. In other words, it is an enzymatic activity that removes ubiquitin molecules from histone H2A, reversing a post-translational modification that typically represses gene expression. This activity is specific to histone H2A and does not act on other histones or general ubiquitinated proteins.
Why Is histone H2A deubiquitinase activity Important in Cell Biology?
Histone H2A deubiquitinase activity is crucial for maintaining the dynamic balance of histone ubiquitination, a process that controls gene expression programs during development and differentiation. By counteracting Polycomb-mediated repression, it ensures proper expression of developmental genes and prevents aberrant silencing. Dysregulation of this activity has been directly linked to cancer, as BAP1 mutations are frequent in mesothelioma and other malignancies, and PSMD14, a proteasome component with this activity, drives myelomagenesis. Furthermore, BAP1-dependent H2A deubiquitination is required for B-cell intrinsic regulation of antibody responses, highlighting its role in immunity. Thus, understanding this activity offers insights into epigenetic regulation and provides potential therapeutic targets.
• Regulates gene expression by reversing H2AK119ub1, a repressive histone mark.
• Essential for proper development, as loss of BAP1 or ASXL proteins leads to developmental defects.
• Implicated in cancer: BAP1 mutations are common in mesothelioma, uveal melanoma, and renal cell carcinoma.
• PSMD14, a proteasome-associated deubiquitinase, exhibits histone H2A deubiquitinase activity that promotes myeloma.
• Required for immune function, specifically B-cell antibody responses.
• Conserved in plants, where UBP5 regulates development by counteracting Polycomb repression.
• Provides a potential target for epigenetic therapies in cancers with BAP1 mutations.
• Structural insights into BAP1/ASXL1 catalysis inform drug design.
• Balances PRC1-mediated ubiquitination, preventing excessive chromatin condensation.
• Serves as a paradigm for understanding cross-talk between ubiquitin signaling and chromatin.
What Happens During histone H2A deubiquitinase activity?
Recognition of H2AK119ub1 substrate
In simple terms: The enzyme first finds and binds to the ubiquitin tag on histone H2A.
The deubiquitinase complex, such as PR-DUB, recognizes histone H2A monoubiquitinated at lysine 119 (H2AK119ub1), a mark deposited by Polycomb repressive complex 1 (PRC1). Structural studies of BAP1/ASXL1 reveal that the ASXL1 DEUBAD domain interacts with the BAP1 catalytic domain to form a composite active site that specifically engages the ubiquitinated H2A. This recognition is essential for targeting the enzyme to chromatin regions marked by H2AK119ub1.
Catalytic cleavage of ubiquitin
In simple terms: The enzyme cuts the ubiquitin molecule off the histone.
Once bound, the catalytic domain of BAP1 catalyzes the hydrolysis of the isopeptide bond between the C-terminal glycine of ubiquitin and lysine 119 of H2A. This reaction releases free ubiquitin and unmodified H2A, directly reversing the repressive mark. The catalytic mechanism involves a cysteine protease-like triad, and mutations in the catalytic cysteine abolish activity.
Chromatin remodeling and transcriptional effects
In simple terms: Removing ubiquitin changes how DNA is packaged, affecting gene activity.
Deubiquitination of H2A leads to a more open chromatin state and can either activate or repress transcription depending on context. In Drosophila, PR-DUB counteracts Polycomb silencing, while in mammals BAP1 enhances Polycomb repression by preventing excessive H2AK119ub1 accumulation and chromatin condensation. This dual role underscores the importance of precise regulation.
Coordination with other histone modifications
In simple terms: This activity works together with other chemical tags on histones.
H2A deubiquitination is coordinated with other histone modifications, such as H3K27 methylation, to establish specific chromatin states. For example, BAP1 recruitment to active enhancers via MLL4/ASXL interactions links H2A deubiquitination to transcriptional activation. Thus, histone H2A deubiquitinase activity is integrated into a broader network of epigenetic regulation.
Key Genes Involved in GO:0140950 histone H2A deubiquitinase activity
The following genes encode proteins that either possess histone H2A deubiquitinase activity or are essential components of the enzyme complexes that carry out this function.
| Gene | Major Role | Research Relevance |
|---|---|---|
| BAP1 | Catalytic subunit of the PR-DUB complex; removes ubiquitin from H2AK119ub1 | Frequently mutated in cancers; target for epigenetic therapy |
| ASXL1 | Scaffold subunit that binds BAP1 and stimulates its deubiquitinase activity | Mutations in ASXL1 are linked to myeloid malignancies and Bohring-Opitz syndrome |
| ASXL2 | Paralog of ASXL1; forms PR-DUB complexes with BAP1 | Implicated in development and cancer |
| ASXL3 | Paralog of ASXL1; interacts with BAP1 | Associated with Bainbridge-Ropers syndrome |
| PSMD14 | Proteasome component with histone H2A deubiquitinase activity | Drives myelomagenesis; potential therapeutic target in multiple myeloma |
| UBP5 | Arabidopsis histone H2A deubiquitinase that counteracts PRC-mediated repression | Model for plant development and Polycomb regulation |
| MLL4 | Recruits BAP1 to active enhancers via ASXL binding | Links H2A deubiquitination to enhancer regulation |
| PRC1 | Deposits H2AK119ub1, the substrate for deubiquitination | Context for understanding the balance of ubiquitination |
| PRC2 | Deposits H3K27me3, which cooperates with H2A deubiquitination | Epigenetic cross-talk |
| BAP1 (Drosophila) | Homolog of human BAP1; component of PR-DUB | Genetic model for Polycomb regulation |
| ASX (Drosophila) | Homolog of ASXL proteins; forms PR-DUB with BAP1 | First identified PR-DUB complex |
| CALYPSO (Drosophila) | Drosophila BAP1 homolog | Model for developmental studies |
| BAP1 (mouse) | Mouse BAP1; essential for development and immune function | Knockout models reveal roles in B-cell responses |
| ASXL1 (mouse) | Mouse ASXL1; interacts with BAP1 | Models for hematopoietic malignancies |
| PSMD14 (human) | Proteasome-associated deubiquitinase | Myeloma cell lines and xenografts |
| UBP5 (Arabidopsis) | Plant H2A deubiquitinase | Plant developmental genetics |
How Is histone H2A deubiquitinase activity Regulated?
Histone H2A deubiquitinase activity is regulated at multiple levels. The formation of the PR-DUB complex is essential, as ASXL proteins bind to and activate BAP1. Recruitment to specific chromatin regions is mediated by interactions with transcription factors and chromatin modifiers, such as MLL4 at active enhancers. Additionally, the activity can be modulated by post-translational modifications and by the availability of substrate H2AK119ub1, which is deposited by PRC1. In Arabidopsis, UBP5 activity is likely regulated during development to counteract Polycomb repression. Overall, this activity is tightly controlled to maintain appropriate gene expression patterns.
histone H2A deubiquitinase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| BAP1 | Mesothelioma, uveal melanoma, renal cell carcinoma | BAP1 knockout cell lines and mouse models |
| PSMD14 | Multiple myeloma | PSMD14 knockdown in myeloma cell lines and xenografts |
| ASXL1 | Myeloid malignancies, Bohring-Opitz syndrome | ASXL1 mutant knock-in mice and patient-derived cells |
| ASXL3 | Bainbridge-Ropers syndrome | ASXL3 knockout zebrafish or mouse models |
| UBP5 | Plant development | Arabidopsis ubp5 mutants |
Cancer
Mutations in BAP1, a histone H2A deubiquitinase, are frequent in mesothelioma, uveal melanoma, clear cell renal cell carcinoma, and other cancers. Loss of BAP1 activity leads to accumulation of H2AK119ub1 and altered chromatin states that promote tumorigenesis. In multiple myeloma, the proteasome component PSMD14 exhibits histone H2A deubiquitinase activity that drives myelomagenesis, suggesting a non-proteolytic role for PSMD14 in cancer. These findings highlight histone H2A deubiquitinase activity as a potential therapeutic target.
Developmental disorders
Germline mutations in ASXL1, ASXL2, and ASXL3, which encode subunits of PR-DUB, cause developmental syndromes such as Bohring-Opitz syndrome and Bainbridge-Ropers syndrome. These mutations impair BAP1 recruitment and H2A deubiquitination, leading to aberrant gene silencing during development. In plants, loss of UBP5 results in developmental defects due to misregulation of Polycomb target genes.
Immune dysfunction
BAP1-mediated histone H2A deubiquitination is required for B-cell intrinsic regulation of antibody responses. Conditional knockout of BAP1 in mouse B cells impairs germinal center formation and antibody production, indicating a critical role in humoral immunity. This links histone H2A deubiquitinase activity to immune disorders and vaccine responses.
From histone H2A deubiquitinase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of BAP1 affect H2AK119ub1 levels and gene expression? | BAP1 knockout cell lines (e.g., HeLa, HEK293T) |
| How does a specific point mutation in BAP1 affect its catalytic activity? | Point-mutant knock-in via CRISPR (e.g., C91S) |
| What is the role of BAP1 in B-cell antibody responses? | B-cell-specific BAP1 knockout mice |
| Can ASXL1 mutations found in patients disrupt PR-DUB complex formation? | Knock-in of patient mutations in cell lines |
| Does overexpression of PSMD14 increase H2A deubiquitination and promote myeloma? | PSMD14 overexpression in myeloma cell lines |
| How does UBP5 regulate plant development? | Arabidopsis UBP5 knockout and overexpression lines |
How to Study the histone H2A deubiquitinase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Western blot | H2AK119ub1 levels | Assessing deubiquitinase activity in cell lysates |
| In vitro deubiquitination assay | Enzymatic cleavage of ubiquitin from H2A | Testing recombinant BAP1/ASXL1 activity and mutants |
| ChIP-seq | Genome-wide distribution of H2AK119ub1 | Mapping changes upon BAP1 knockout or overexpression |
| Mass spectrometry | Quantification of ubiquitination sites | Identifying global changes in histone ubiquitination |
| X-ray crystallography | Three-dimensional structure of enzyme-substrate complex | Understanding catalytic mechanism |
| RNA-seq | Transcriptional changes | Linking H2A deubiquitination to gene expression |
| Immunofluorescence | Nuclear localization and chromatin condensation | Visualizing effects of BAP1 loss |
| CRISPR screening | Identification of genes affecting H2AK119ub1 | Functional genomics of deubiquitination |
Detection of H2AK119ub1 levels
Western blotting with antibodies specific to H2AK119ub1 is a standard method to assess histone H2A deubiquitinase activity. This approach can be used in cells with knockout or overexpression of candidate genes to determine changes in substrate levels. Additionally, mass spectrometry-based proteomics can quantify ubiquitination sites on histones.
In vitro deubiquitinase assays
Recombinant BAP1/ASXL1 complexes can be incubated with ubiquitinated H2A substrates, and the release of ubiquitin can be measured by gel electrophoresis or fluorescence. Such assays are used to determine catalytic parameters and the effects of mutations.
Chromatin immunoprecipitation (ChIP)
ChIP followed by quantitative PCR or sequencing (ChIP-seq) can map the genomic distribution of H2AK119ub1 and other histone marks upon modulation of deubiquitinase activity. This reveals how the enzyme affects chromatin state and transcription.
Structural biology
X-ray crystallography and cryo-electron microscopy have provided detailed insights into how BAP1/ASXL1 recognizes and cleaves H2AK119ub1. These methods are essential for understanding the catalytic mechanism and for designing inhibitors.
How CRISPR Can Be Used to Study GO:0140950 histone H2A deubiquitinase activity
Knockout
CRISPR-Cas9 knockout of BAP1 or ASXL genes is widely used to study loss of histone H2A deubiquitinase activity. Knockout cell lines exhibit increased H2AK119ub1 levels and altered gene expression, providing insights into the role of this activity in cancer and development. In mice, conditional knockout of BAP1 in B cells has revealed its importance in antibody responses.
Point Mutation
Introducing point mutations in the catalytic domain of BAP1 (e.g., C91S) via CRISPR knock-in allows researchers to separate catalytic activity from scaffolding functions. Such models are valuable for understanding how specific mutations found in patients affect enzyme function.
Knock-in
Knock-in of tagged BAP1 (e.g., GFP or HA) enables endogenous localization and interaction studies. Additionally, knock-in of disease-associated ASXL1 mutations can model their effects on PR-DUB complex formation and activity.
Overexpression
Overexpression of wild-type or mutant BAP1, PSMD14, or UBP5 in cell lines can be used to assess gain-of-function effects on H2A deubiquitination and downstream phenotypes. This approach is particularly useful for studying oncogenic roles of PSMD14 in myeloma.
How EDITGENE Supports histone H2A deubiquitinase activity Research
Researchers studying histone H2A deubiquitinase activity-related genes often need to determine whether a candidate gene is causally involved in chromatin regulation, disease, or development. Generating precise genetic models is essential to dissect the function of enzymes like BAP1, ASXL proteins, and PSMD14. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate such research.
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Frequently Asked Questions About histone H2A deubiquitinase activity
What is histone H2A deubiquitinase activity?
Histone H2A deubiquitinase activity (GO:0140950) is an enzymatic function that removes ubiquitin from histone H2A, reversing a repressive chromatin mark.
What genes are involved in histone H2A deubiquitinase activity?
Key genes include BAP1, ASXL1, ASXL2, ASXL3, PSMD14, and UBP5, which encode subunits or enzymes with this activity.
Which enzyme complex has histone H2A deubiquitinase activity?
The Polycomb repressive deubiquitinase (PR-DUB) complex, containing BAP1 and ASXL proteins, is the primary enzyme complex with this activity.
What is the role of BAP1 in histone H2A deubiquitination?
BAP1 is the catalytic subunit of PR-DUB that cleaves ubiquitin from H2AK119ub1, thereby regulating gene expression and suppressing tumors.
How is histone H2A deubiquitinase activity linked to cancer?
Mutations in BAP1 cause mesothelioma and other cancers, while PSMD14 activity drives myeloma, highlighting the importance of this activity in tumorigenesis.
What methods are used to study histone H2A deubiquitinase activity?
Common methods include Western blot for H2AK119ub1, in vitro deubiquitination assays, ChIP-seq, and structural biology.
Is histone H2A deubiquitinase activity conserved in plants?
Yes, the Arabidopsis UBP5 enzyme has this activity and counteracts Polycomb-mediated repression during development.
What is H2AK119ub1?
H2AK119ub1 is the monoubiquitination of histone H2A at lysine 119, a repressive mark deposited by PRC1 and removed by histone H2A deubiquitinases.
How does PSMD14 exhibit histone H2A deubiquitinase activity?
PSMD14, a proteasome component, can cleave ubiquitin from H2A independently of its proteolytic role, promoting myelomagenesis.
Can CRISPR be used to study histone H2A deubiquitinase activity?
Yes, CRISPR knockout, point mutation knock-in, and overexpression models are powerful tools to dissect the function of genes like BAP1 and ASXL1.
Conclusion
Histone H2A deubiquitinase activity (GO:0140950) is a fundamental epigenetic function that reverses H2AK119ub1, thereby influencing gene expression, development, and disease. The PR-DUB complex, with BAP1 and ASXL proteins, is the best-characterized enzyme carrying out this activity, and its dysregulation is linked to cancers, developmental disorders, and immune defects. Continued research using CRISPR models, structural biology, and genomics will further illuminate the mechanisms and therapeutic potential of targeting this activity.
References
- 1. He L et al.. 2023. The proteasome component PSMD14 drives myelomagenesis through a histone deubiquitinase activity.. Mol Cell 83(22):4000-4016.e6 PMID: 37935198
- 2. Zhang Y et al.. 2024. ASXLs binding to the PHD2/3 fingers of MLL4 provides a mechanism for the recruitment of BAP1 to active enhancers.. Nat Commun 15(1):4883 PMID: 38849395
- 3. Thomas JF et al.. 2023. Structural basis of histone H2A lysine 119 deubiquitination by Polycomb repressive deubiquitinase BAP1/ASXL1.. Sci Adv 9(32):eadg9832 PMID: 37556531
- 4. Godwin J et al.. 2024. The UBP5 histone H2A deubiquitinase counteracts PRCs-mediated repression to regulate Arabidopsis development.. Nat Commun 15(1):667 PMID: 38253560
- 5. Scheuermann JC et al.. 2010. Histone H2A deubiquitinase activity of the Polycomb repressive complex PR-DUB.. Nature 465(7295):243-7 PMID: 20436459
- 6. Verrijzer CP. 2022. Goldilocks meets Polycomb.. Genes Dev 36(19-20):1043-1045 PMID: 36460465
- 7. Conway E et al.. 2021. BAP1 enhances Polycomb repression by counteracting widespread H2AK119ub1 deposition and chromatin condensation.. Mol Cell 81(17):3526-3541.e8 PMID: 34186021
- 8. Liang Y et al.. 2024. B-cell intrinsic regulation of antibody mediated immunity by histone H2A deubiquitinase BAP1.. Front Immunol 15:1353138 PMID: 38529289
