GO:0140798 histone H3R26 arginine deiminase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0140798 describes the enzymatic activity that converts histone H3 arginine 26 (H3R26) to citrulline, releasing ammonium [1,2].
• This activity is primarily catalyzed by peptidylarginine deiminase 2 (PADI2), which citrullinates H3R26 and facilitates estrogen receptor alpha target gene activation.
• H3R26 citrullination antagonizes arginine methylation at the same residue, creating a regulatory crosstalk that influences chromatin structure and transcription.
• Targeted H3R26 deimination modifies nucleosome structure to facilitate estrogen receptor binding.
• Dysregulated H3R26 citrullination has been implicated in cancer, including multiple myeloma and MGUS, where it drives IL-6 production.
• CRISPR/dCas9-based epigenetic editing systems now enable loci-targeted histone citrullination for precise transcription regulation.
Description
Histone H3R26 arginine deiminase activity (GO:0140798) is a molecular function that catalyzes the conversion of histone H3 arginine 26 to citrulline, a post-translational modification known as citrullination or deimination [1,2]. This activity is part of the broader family of peptidylarginine deiminase (PADI) enzymes, which convert positively charged arginine residues to neutral citrulline, thereby altering protein charge and function [2,3]. The reaction consumes water and releases ammonium, and it is calcium-dependent for PADI2. This specific modification at H3R26 has emerged as a critical regulator of gene expression, particularly in hormone-responsive cancers and developmental processes [2,5,6]. Researchers study GO:0140798 because it represents a direct link between enzymatic activity and epigenetic regulation. Citrullination of H3R26 can antagonize methylation at the same residue, influencing the recruitment of chromatin-modifying complexes and transcription factors. For example, H3R26 citrullination by PADI2 facilitates estrogen receptor alpha (ERα) target gene activation, highlighting its role in breast cancer biology. Additionally, targeted deimination of H3R26 alters nucleosome structure to enhance ER binding, providing a mechanistic basis for its function. Beyond cancer, PADI-mediated histone citrullination has been implicated in preimplantation development and inflammatory signaling in bone marrow mesenchymal stem cells [6,7]. The importance of GO:0140798 extends to the development of novel therapeutic strategies and research tools. Recent advances in CRISPR/dCas9-based epigenetic editing allow precise, loci-specific induction of histone citrullination, enabling researchers to dissect causal relationships between this modification and transcriptional outcomes. Understanding the regulation and downstream effects of H3R26 citrullination is therefore essential for both basic chromatin biology and translational applications in cancer and regenerative medicine.
histone H3R26 arginine deiminase activity At A Glance
| GO ID | GO:0140798 |
|---|---|
| GO term | histone H3R26 arginine deiminase activity |
| Ontology | molecular_function |
| Synonym | H3-R26 citrullination; histone-arginine deiminase activity (H3-R26 specific); histone H3-R26 arginine deiminase activity |
| Major function | Catalyzes the citrullination of histone H3 at arginine 26, converting it to citrulline and releasing ammonium |
| Reaction | H2O + histone H3 L-arginyl (position 26) = histone H3 L-citrullyl (position 26) + NH4+ |
| Primary enzyme | Peptidylarginine deiminase 2 (PADI2) |
| Cofactor requirement | Calcium-dependent for PADI2 nuclear localization and activity |
| Substrate specificity | Histone H3 arginine 26 residue |
What Is GO:0140798?
Histone H3R26 arginine deiminase activity is the enzymatic catalysis of a reaction in which a water molecule reacts with the arginine residue at position 26 of histone H3, converting it to a citrulline residue and releasing ammonium. This reaction results in histone H3 citrullination specifically at position 26, a post-translational modification that alters the charge and biochemical properties of the histone tail.
Why Is histone H3R26 arginine deiminase activity Important in Cell Biology?
GO:0140798 is important because it represents a key epigenetic regulatory mechanism that directly modifies chromatin at a specific histone residue, thereby influencing gene transcription, chromatin structure, and cellular signaling. This activity is critical for understanding how post-translational modifications of histones contribute to normal development and disease, particularly in hormone-dependent cancers and inflammatory conditions [1,2,5,7].
• Regulates estrogen receptor alpha target gene activation in breast cancer cells.
• Antagonizes arginine methylation at H3R26, creating a regulatory crosstalk that affects chromatin state.
• Facilitates estrogen receptor binding by modifying nucleosome structure.
• Plays a potential role in preimplantation development through PADI-mediated histone citrullination.
• Drives IL-6 production by bone marrow mesenchymal stem cells in MGUS and multiple myeloma.
• Is calcium-dependent, linking cellular calcium signaling to nuclear epigenetic regulation.
• Can be targeted using CRISPR/dCas9-based epigenetic editing for precise transcription regulation.
• Represents a potential therapeutic target for cancers and inflammatory diseases [2,7].
• Provides a mechanism for rapid, enzyme-mediated changes in chromatin charge and structure [1,5].
• Enables researchers to study causal relationships between histone citrullination and gene expression.
What Happens During histone H3R26 arginine deiminase activity?
Substrate Recognition and Binding
In simple terms: The enzyme finds and binds to the histone H3 tail near arginine 26.
The enzyme, primarily PADI2, recognizes histone H3 and positions the arginine 26 residue within its active site. This binding is influenced by the surrounding chromatin context and the presence of other histone modifications. Calcium binding to PADI2 induces conformational changes that are required for its nuclear localization and activity. The specificity for H3R26 is determined by the enzyme's active site architecture and the local sequence context of the histone tail.
Catalytic Deimination Reaction
In simple terms: The enzyme converts arginine 26 into citrulline by removing an imine group and adding water.
The catalytic mechanism involves the hydrolysis of the guanidinium group of arginine, resulting in the formation of a citrulline residue and the release of ammonium. This reaction consumes a water molecule and is calcium-dependent for PADI2. The conversion of arginine to citrulline reduces the positive charge of the histone tail, which can alter electrostatic interactions with DNA and other proteins [1,2].
Chromatin Structural Changes
In simple terms: The modification changes how tightly DNA is wrapped around histones, making it easier for other proteins to bind.
Citrullination of H3R26 modifies nucleosome structure, facilitating the binding of transcription factors such as estrogen receptor alpha. Targeted H3R26 deimination specifically facilitates estrogen receptor binding by altering nucleosome structure. This structural change can increase chromatin accessibility and promote the assembly of transcriptional complexes at target gene promoters [2,5].
Crosstalk with Other Histone Modifications
In simple terms: Citrullination at H3R26 competes with methylation at the same site, affecting gene expression.
H3R26 citrullination antagonizes arginine methylation at the same residue, creating a regulatory crosstalk that influences ER-target gene transcription. This competition between citrullination and methylation can determine the recruitment of specific chromatin readers and writers, thereby shaping the transcriptional outcome. The balance between these modifications is dynamically regulated and can be altered in disease states [1,2].
Downstream Transcriptional Activation
In simple terms: The modification helps turn on specific genes, especially those controlled by estrogen receptor.
H3R26 citrullination by PADI2 facilitates estrogen receptor alpha target gene activation, leading to increased transcription of genes involved in cell proliferation and survival. This activity is part of a feed-forward loop where ER signaling can also influence PADI2 expression or activity. The resulting transcriptional changes can promote cancer cell growth and contribute to endocrine resistance [2,7].
Key Genes Involved in GO:0140798 histone H3R26 arginine deiminase activity
The following genes and proteins are directly involved in or regulate histone H3R26 arginine deiminase activity and its downstream effects.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PADI2 | Catalyzes citrullination of H3R26 | Primary enzyme for GO:0140798; target for cancer and inflammatory studies [2,3] |
| PADI4 | Catalyzes histone citrullination, including H3R26 | Potential redundant or compensatory activity; studied in preimplantation development |
| ESR1 | Estrogen receptor alpha; binds chromatin and activates target genes | H3R26 citrullination facilitates ER binding and target gene activation [2,5] |
| H3-3A | Histone H3 variant; substrate for citrullination | Provides the H3R26 residue for modification [1,2] |
| H3-3B | Histone H3 variant; substrate for citrullination | Alternative H3 variant that can be citrullinated at R26 |
| H3C1 | Histone H3 family member; substrate | Contributes to the pool of H3 for citrullination |
| H3C2 | Histone H3 family member; substrate | Potential substrate for PADI2-mediated citrullination |
| H3C3 | Histone H3 family member; substrate | May be citrullinated at R26 in specific contexts |
| H3C4 | Histone H3 family member; substrate | Contributes to H3R26 citrullination dynamics |
| H3C6 | Histone H3 family member; substrate | Potential target for deimination |
| H3C7 | Histone H3 family member; substrate | May influence chromatin structure upon citrullination |
| H3C8 | Histone H3 family member; substrate | Substrate for PADI2 in vitro and in vivo |
| H3C10 | Histone H3 family member; substrate | Potential involvement in H3R26 modification |
| H3C11 | Histone H3 family member; substrate | Contributes to histone H3 pool |
| H3C12 | Histone H3 family member; substrate | May be citrullinated at R26 |
| H3C13 | Histone H3 family member; substrate | Potential substrate for PADI-mediated citrullination |
| H3C14 | Histone H3 family member; substrate | Involved in chromatin regulation |
| H3C15 | Histone H3 family member; substrate | Potential target for H3R26 citrullination |
How Is histone H3R26 arginine deiminase activity Regulated?
Histone H3R26 arginine deiminase activity is regulated by calcium signaling, which controls the nuclear localization and enzymatic activity of PADI2. Additionally, the activity can be influenced by crosstalk with other histone modifications, such as methylation at H3R26, which competes with citrullination and affects ER-target gene transcription. The expression levels of PADI2 and its interacting partners also modulate the overall activity. Recent advances in CRISPR/dCas9-based epigenetic editing allow for precise, loci-specific regulation of histone citrullination, providing a tool to study its dynamic regulation.
histone H3R26 arginine deiminase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PADI2 | Breast cancer, ER-positive tumors | PADI2 knockout or overexpression in MCF-7 cells |
| PADI2 | Multiple myeloma, MGUS | PADI2 inhibition in bone marrow mesenchymal stem cells |
| ESR1 | Breast cancer, endocrine resistance | ESR1 mutant knock-in in breast cancer cell lines [2,5] |
| PADI4 | Preimplantation development | Padi4 knockout mouse embryos |
| H3-3A | Chromatin regulation in cancer | H3R26 point mutation (R26K) knock-in [1,5] |
Breast Cancer and Estrogen Receptor Signaling
H3R26 citrullination by PADI2 facilitates estrogen receptor alpha target gene activation, promoting the transcription of genes that drive cell proliferation and survival in breast cancer. This modification is part of a regulatory loop that can contribute to endocrine resistance and tumor progression. The crosstalk between citrullination and methylation at H3R26 further fine-tunes ER-dependent transcription, making it a potential therapeutic target [1,2].
Multiple Myeloma and MGUS
Citrullination of histone H3 drives IL-6 production by bone marrow mesenchymal stem cells in monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma. This inflammatory cytokine supports the growth and survival of malignant plasma cells, highlighting a role for H3R26 citrullination in the tumor microenvironment. Targeting PADI2 activity could therefore reduce IL-6-mediated support of myeloma cells.
Preimplantation Development
PADI-mediated histone citrullination, including at H3R26, has been implicated in preimplantation development, suggesting a role in early embryonic gene regulation and chromatin remodeling. Disruption of this activity could affect developmental processes, although further studies are needed to fully elucidate the mechanisms.
Inflammatory and Autoimmune Conditions
Histone citrullination is a hallmark of inflammatory responses and is implicated in autoimmune diseases such as rheumatoid arthritis. The specific role of H3R26 citrullination in these conditions is an active area of research, with potential links to cytokine production and immune cell activation.
From histone H3R26 arginine deiminase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does PADI2 knockout reduce H3R26 citrullination and ER target gene expression? | PADI2 knockout cell line (e.g., MCF-7) |
| Does H3R26 citrullination directly facilitate ER binding? | H3R26 point mutation (R26K) knock-in cell line |
| Can loci-specific H3R26 citrullination activate a target gene? | CRISPR/dCas9-PADI2 epigenetic editing system |
| What is the role of calcium in PADI2 nuclear localization? | Calcium-binding mutant PADI2 knock-in |
| Does PADI2 overexpression drive IL-6 production in myeloma? | PADI2 overexpression in bone marrow mesenchymal stem cells |
| Is H3R26 citrullination required for preimplantation development? | Padi4 knockout mouse embryos |
How to Study the histone H3R26 arginine deiminase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Western blot | Protein levels and modification status | Detection of H3R26 citrullination with site-specific antibodies |
| ChIP-seq | Genome-wide localization of modified histones | Mapping H3R26 citrullination across the genome |
| RNA-seq | Gene expression changes | Identifying target genes upon PADI2 modulation [2,7] |
| ATAC-seq | Chromatin accessibility | Assessing nucleosome structural changes |
| Mass spectrometry | Identification of citrullination sites | Unbiased discovery of histone modifications |
| Immunofluorescence | Subcellular localization | Visualizing H3R26 citrullination in cells |
| CRISPR/dCas9 epigenetic editing | Loci-specific modification | Targeted induction of H3R26 citrullination |
| qRT-PCR | Quantification of specific transcripts | Validating RNA-seq results |
Detection of H3R26 Citrullination
Site-specific antibodies against citrullinated H3R26 are used in Western blot, immunofluorescence, and chromatin immunoprecipitation (ChIP) to detect and quantify the modification. Mass spectrometry-based proteomics can also identify citrullination sites on histones with high confidence [1,2].
Transcriptional Profiling
RNA sequencing (RNA-seq) is used to measure changes in gene expression upon modulation of H3R26 citrullination, such as PADI2 knockout or overexpression. This allows researchers to identify target genes and pathways affected by the modification [2,7].
Chromatin Accessibility and Structure
ATAC-seq and MNase-seq can assess changes in chromatin accessibility and nucleosome positioning following H3R26 citrullination. These methods help elucidate how the modification alters chromatin structure to facilitate transcription factor binding.
Epigenetic Editing
CRISPR/dCas9-based epigenetic editing systems fused to PADI2 or its catalytic domain enable loci-specific induction of H3R26 citrullination. This technology allows precise dissection of causal relationships between the modification and transcriptional outcomes.
How CRISPR Can Be Used to Study GO:0140798 histone H3R26 arginine deiminase activity
Knockout
CRISPR knockout of PADI2 or PADI4 can eliminate H3R26 arginine deiminase activity, allowing researchers to study the loss-of-function effects on gene expression, chromatin structure, and cellular phenotypes. Knockout cell lines are valuable for validating the specificity of the enzymatic activity and for identifying downstream targets [2,6].
Point Mutation
Introducing point mutations at the H3R26 residue (e.g., R26K) using CRISPR knock-in can prevent citrullination while preserving other histone functions. This approach helps distinguish the specific effects of H3R26 citrullination from other modifications and can be used to test the causal role of the modification in transcription.
Knock-in
Knock-in of tagged PADI2 or H3 variants allows for affinity purification, imaging, and chromatin immunoprecipitation studies. Tagged knock-in models enable the study of protein interactions and localization dynamics in a physiological context [3,4].
Overexpression
Overexpression of PADI2 or its catalytic domain using CRISPR activation or lentiviral vectors can increase H3R26 citrullination levels, facilitating the study of gain-of-function effects on transcription and cellular behavior. Overexpression models are useful for identifying downstream pathways and potential therapeutic targets [2,7].
How EDITGENE Supports histone H3R26 arginine deiminase activity Research
Researchers studying histone H3R26 arginine deiminase activity-related genes often need to determine whether a candidate gene is causally involved in the modification, chromatin regulation, or disease phenotypes. EDITGENE provides a comprehensive suite of CRISPR-based services to enable precise genetic and epigenetic manipulations, from knockout to knock-in and overexpression, tailored to your experimental needs.
Contact EDITGENE today to design your custom CRISPR model for histone H3R26 arginine deiminase activity research.
Frequently Asked Questions About histone H3R26 arginine deiminase activity
What is histone H3R26 arginine deiminase activity?
It is the enzymatic activity that converts arginine 26 of histone H3 to citrulline, releasing ammonium, as defined by GO:0140798 [1,2].
What genes are involved in histone H3R26 arginine deiminase activity?
The primary gene is PADI2, which encodes the enzyme peptidylarginine deiminase 2. Other PADI family members and histone H3 variants may also contribute [2,6].
Which enzyme catalyzes H3R26 citrullination?
PADI2 is the main enzyme known to catalyze H3R26 citrullination, although PADI4 may also have activity [2,6].
What is the role of H3R26 citrullination in cancer?
It facilitates estrogen receptor alpha target gene activation in breast cancer and drives IL-6 production in multiple myeloma, promoting tumor growth [2,7].
How is H3R26 citrullination detected?
It is commonly detected using site-specific antibodies in Western blot, immunofluorescence, or ChIP, as well as by mass spectrometry [1,2].
Is H3R26 citrullination reversible?
The reaction is catalyzed by PADI enzymes and is generally considered irreversible, but the modification can be removed by histone turnover or other mechanisms.
What is the relationship between H3R26 citrullination and methylation?
Citrullination and methylation compete for the same arginine residue, creating a regulatory crosstalk that influences gene transcription.
Can CRISPR be used to study H3R26 citrullination?
Yes, CRISPR knockout of PADI2, point mutation of H3R26, and CRISPR/dCas9-based epigenetic editing are powerful approaches to study this modification [4,5].
What diseases are associated with H3R26 citrullination?
Breast cancer, multiple myeloma, MGUS, and potentially preimplantation developmental defects and inflammatory conditions [2,6,7].
How does calcium affect H3R26 arginine deiminase activity?
Calcium is required for PADI2 nuclear localization and enzymatic activity, linking calcium signaling to histone citrullination.
Conclusion
Histone H3R26 arginine deiminase activity (GO:0140798) is a specialized enzymatic function that plays a pivotal role in epigenetic regulation by converting H3R26 to citrulline. This modification influences chromatin structure, transcription factor binding, and gene expression, with significant implications for cancer, development, and inflammation. Understanding its mechanism and regulation provides opportunities for therapeutic intervention and advances in epigenetic research.
References
- 1. Clancy KW et al.. 2017. Citrullination/Methylation Crosstalk on Histone H3 Regulates ER-Target Gene Transcription.. ACS Chem Biol 12(6):1691-1702 PMID: 28485572
- 2. Zhang X et al.. 2012. Peptidylarginine deiminase 2-catalyzed histone H3 arginine 26 citrullination facilitates estrogen receptor α target gene activation.. Proc Natl Acad Sci U S A 109(33):13331-6 PMID: 22853951
- 3. Zheng L et al.. 2019. Calcium Regulates the Nuclear Localization of Protein Arginine Deiminase 2.. Biochemistry 58(27):3042-3056 PMID: 31243954
- 4. Zhang X et al.. 2024. A programmable CRISPR/dCas9-based epigenetic editing system enabling loci-targeted histone citrullination and precise transcription regulation.. J Genet Genomics 51(12):1485-1493 PMID: 38849111
- 5. Guertin MJ et al.. 2014. Targeted H3R26 deimination specifically facilitates estrogen receptor binding by modifying nucleosome structure.. PLoS Genet 10(9):e1004613 PMID: 25211228
- 6. Kan R et al.. 2012. Potential role for PADI-mediated histone citrullination in preimplantation development.. BMC Dev Biol 12:19 PMID: 22712504
- 7. McNee G et al.. 2017. Citrullination of histone H3 drives IL-6 production by bone marrow mesenchymal stem cells in MGUS and multiple myeloma.. Leukemia 31(2):373-381 PMID: 27400413
