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O8G-Seq for Transcriptome-Wide RNA Oxidation Mapping
8-oxo-7,8-dihydroguanine (8-oxoG, or O8G) is one of the most abundant oxidative lesions in RNA, formed when reactive oxygen species (ROS) attack the C8 position of guanine. Unlike random chemical damage, 8-oxoG deposition is selective — it preferentially accumulates in guanine-rich regions, miRNA seed sequences, and specific transcript classes under oxidative stress. Once formed, 8-oxoG alters base-pairing specificity (G→T misreading), disrupts translation fidelity, and is recognized by dedicated RNA-binding proteins — including PNPase, AUF1/HNRNPD, PCBP1, and YB-1 — that route oxidized transcripts toward degradation or stabilization.
O8G-Seq maps these modifications transcriptome-wide. The method uses a highly specific anti-8-oxoG antibody to enrich oxidized RNA fragments via immunoprecipitation (IP), with a parallel input control sequenced for background normalization. By comparing IP to input, O8G-enriched transcripts and regions are identified — providing a comprehensive view of where RNA oxidation occurs, which transcripts are most affected, and how O8G landscapes shift between experimental conditions.
At CD Genomics, we offer a standardized O8G-Seq platform covering mRNA, lncRNA, circRNA, and total transcriptome workflows — each with paired IP and input library construction, sequencing, and full bioinformatics support.
Key Highlights:
- Anti-8-oxoG Antibody IP with Input Control — each sample is processed as paired IP and input libraries, enabling background-corrected enrichment calling and reducing false positives from non-specific antibody binding
- Four RNA-Type Coverage Options — O8G mRNA-seq, O8G lncRNA-seq, O8G circRNA-seq, and O8G total transcriptome for simultaneous profiling across RNA biotypes
- Anti-Oxidation Sample Handling — protocols designed to minimize artificial oxidation during RNA extraction, fragmentation, and IP steps
- End-to-End Bioinformatics — from peak calling and transcript annotation through differential O8G analysis and functional enrichment
Overview of Our O8G-Seq Services
8-oxo-7,8-dihydroguanine (8-oxoG, or O8G) is one of the most abundant oxidative lesions in RNA, formed when reactive oxygen species (ROS) attack the C8 position of guanine. Unlike random chemical damage, 8-oxoG deposition is selective — it preferentially accumulates in guanine-rich regions, miRNA seed sequences, and specific transcript classes under oxidative stress. Once formed, 8-oxoG alters base-pairing specificity (G→T misreading), disrupts translation fidelity, and is recognized by dedicated RNA-binding proteins — including PNPase, AUF1/HNRNPD, PCBP1, and YB-1 — that route oxidized transcripts toward degradation or stabilization.
O8G-Seq maps these modifications transcriptome-wide. The method uses a highly specific anti-8-oxoG antibody to enrich oxidized RNA fragments via immunoprecipitation (IP), with a parallel input control sequenced for background normalization. By comparing IP to input, O8G-enriched transcripts and regions are identified — providing a comprehensive view of where RNA oxidation occurs, which transcripts are most affected, and how O8G landscapes shift between experimental conditions.
At CD Genomics, we offer a standardized O8G-Seq platform covering mRNA, lncRNA, circRNA, and total transcriptome workflows — each with paired IP and input library construction, sequencing, and full bioinformatics support.
Core Technologies: O8G mRNA, lncRNA, circRNA, and Total Transcriptome Sequencing
O8G mRNA-Seq — Transcriptome-Wide mRNA Oxidation Profiling
O8G mRNA-seq focuses O8G profiling on the polyadenylated transcriptome — the most functionally annotated RNA fraction. mRNA is enriched via poly(A) selection, fragmented, and subjected to anti-8-oxoG IP alongside an input control. This is the standard entry point for most studies, as it directly links RNA oxidation to protein-coding gene expression.
O8G mRNA-seq is well-suited for:
- Mapping oxidation across the coding transcriptome under defined stress conditions
- Identifying mRNAs with selective 8-oxoG enrichment for follow-up functional studies
- Comparing O8G landscapes between treatment and control, or between disease and normal tissue
- Integration with matched RNA-seq data to correlate oxidation with transcript abundance changes
A 2025 study in Frontiers in Cell and Developmental Biology applied O8G RIP-seq to mRNA from normal and senescent CaCO2 colon cancer cells, identifying distinct oxidation profiles that distinguish proliferating from senescent cancer cells (Huang et al., 2025).
O8G lncRNA-Seq — Long Non-Coding RNA Oxidation Detection
Long non-coding RNAs participate in diverse regulatory processes — chromatin remodeling, transcriptional control, post-transcriptional regulation — and their functions can be altered by oxidative modifications. O8G lncRNA-seq enriches for oxidized lncRNAs using an antibody-based approach compatible with rRNA-depleted or poly(A)-minus RNA fractions.
This workflow is suited for studies investigating how oxidative stress reshapes the lncRNA regulatory network, or whether specific lncRNAs acquire O8G modifications that alter their stability, structure, or protein-binding capacity.
O8G circRNA-Seq — Circular RNA Oxidation Profiling
Circular RNAs are covalently closed, typically more stable than linear transcripts, and enriched in the brain and other oxidative-metabolism-active tissues. Their extended half-life makes them particularly informative as cumulative records of oxidative exposure. circRNA-specific O8G-Seq requires RNase R treatment to deplete linear RNA before IP, enriching the circular fraction for oxidation profiling.
A 2025 Molecular Cancer study demonstrated that ROS-induced O8G modification of circPLCE1 recruits AUF1, destabilizes the circRNA, and relieves its tumor-suppressive activity in lung cancer — establishing circRNA oxidation as functionally relevant to cancer progression (Zhao et al., 2025).
O8G Total Transcriptome Sequencing
For studies requiring a complete picture — mRNA + lncRNA + circRNA simultaneously — O8G total transcriptome sequencing combines rRNA depletion with anti-8-oxoG IP to profile oxidation across all major RNA biotypes in a single experiment. This is the most comprehensive option, recommended when the full scope of RNA oxidation is unknown or when comparing global O8G landscapes between conditions.
Method Selection Guide: Choosing the Right O8G-Seq Approach
| Criterion | O8G mRNA-Seq | O8G lncRNA-Seq | O8G circRNA-Seq | O8G Total Transcriptome |
|---|---|---|---|---|
| RNA fraction | Poly(A)-selected mRNA | rRNA-depleted, poly(A)-minus | RNase R-treated circular RNA | rRNA-depleted total RNA |
| Transcripts profiled | Protein-coding mRNAs | Long non-coding RNAs | Circular RNAs | mRNA + lncRNA + circRNA |
| O8G detection | Anti-8-oxoG IP vs Input | Anti-8-oxoG IP vs Input | Anti-8-oxoG IP vs Input (+ RNase R) | Anti-8-oxoG IP vs Input |
| Resolution | Transcript/region-level (~100–200 nt) | Transcript/region-level | CircRNA-level | Transcript/region-level across biotypes |
| Functional annotation | Most complete — GO, KEGG, reactome | Moderate — lncRNA-specific databases | Limited — circRNA databases emerging | Full — across all annotated biotypes |
| RNA input | Moderate | Moderate to high | Higher (RNase R step + IP) | Highest (all biotypes) |
| Best for | mRNA-focused oxidation studies; stress response; translation fidelity; disease biomarker screening | lncRNA regulatory network oxidation; chromatin-associated lncRNA O8G profiling | Cumulative oxidative exposure; brain/neuron studies; circRNA functional oxidation | Global O8G landscape discovery; unknown oxidation targets; multi-RNA-type comparisons |
Selection Strategy:
- Start with your biological question. If you study how oxidation affects protein-coding gene expression, O8G mRNA-seq is the standard entry point. If your interest is in regulatory RNA oxidation, choose lncRNA-seq or circRNA-seq. If the scope is unknown — choose total transcriptome.
- Consider the functional annotation depth. mRNA oxidation profiles map directly to known pathways (GO, KEGG). lncRNA and circRNA oxidation profiles provide positional and quantitative information but functional interpretation relies on more limited annotation databases.
- RNase R efficiency matters for circRNA. circRNA-Seq requires efficient linear RNA removal. We verify RNase R digestion efficiency by qPCR of linear control transcripts before proceeding to IP.
- Combine for completeness. An efficient strategy is total transcriptome for discovery, followed by targeted validation using individual RNA-type workflows on key samples.
End-to-End Workflow and Quality Control
Our O8G-Seq service follows a standardized workflow with QC checkpoints at each stage. The defining feature is the paired IP and input library design — two parallel sequencing libraries from the same RNA sample, enabling background-corrected O8G enrichment calling.
- Sample Receipt and Quality Assessment — QC Checkpoint: RNA integrity (RIN) by Bioanalyzer/TapeStation; concentration and purity (OD260/280, OD260/230); degradation assessment. Anti-oxidation precautions: samples handled in O₂-minimized buffers during QC.
- RNA Preparation and Fragmentation — QC Checkpoint: poly(A) selection / rRNA depletion / RNase R treatment efficiency verified; RNA fragmentation size distribution confirmed (Bioanalyzer); RNA yield post-enrichment. Fragmentation is performed in O₂-depleted buffer with antioxidants to prevent artifactual oxidation during processing.
- Anti-8-oxoG Immunoprecipitation — QC Checkpoint: anti-8-oxoG antibody specificity validated against m6A, 8-oxoA, 5-hydroxycytosine, and unmodified RNA; IP enrichment efficiency monitored by qPCR of known oxidized and non-oxidized control transcripts; input aliquot retained for parallel library construction.
- Library Construction and Sequencing — QC Checkpoint: library yield and fragment size; Q30 scores; duplication rate. Both IP and input libraries sequenced on the same flow cell to minimize batch effects.
- Data QC and Bioinformatics — QC Checkpoint: IP vs input read distribution; peak enrichment signal-to-noise (FRiP); replicate correlation; peak reproducibility between biological replicates; deliverable completeness.
Sample Requirements and Anti-Oxidation Preparation Guidelines
RNA is chemically more susceptible to oxidation than DNA — guanine bases in single-stranded RNA are particularly exposed. Preventing artifactual oxidation during sample preparation, storage, and shipping is essential for O8G-Seq data quality.
| Service Tier | Recommended RNA Type | Input Guideline | Key QC Metrics | Notes |
|---|---|---|---|---|
| O8G mRNA-Seq | Poly(A)-selected or total RNA | ≥ 30 μg total RNA recommended; ≥ 10 μg minimum; ≥ 20 ng/μL | RIN ≥ 7; OD260/280: 1.8–2.1; OD260/230 ≥ 1.5 | Standard entry option; total RNA submitted, poly(A) selection performed in-house under anti-oxidation conditions |
| O8G lncRNA-Seq | Total RNA (rRNA-depleted) | ≥ 30 μg total RNA recommended; ≥ 10 μg minimum; ≥ 20 ng/μL | RIN ≥ 7; OD260/280: 1.8–2.1 | Requires rRNA depletion before IP; higher total input than mRNA-seq |
| O8G circRNA-Seq | Total RNA (RNase R-treated) | ≥ 40 μg total RNA recommended; ≥ 15 μg minimum; ≥ 20 ng/μL | RIN ≥ 7; OD260/280: 1.8–2.1 | RNase R digestion reduces linear RNA; input validated by qPCR before IP |
| O8G Total Transcriptome | Total RNA (rRNA-depleted) | ≥ 40 μg total RNA recommended; ≥ 15 μg minimum; ≥ 20 ng/μL | RIN ≥ 7; OD260/280: 1.8–2.1; OD260/230 ≥ 1.5 | Highest input requirement; single experiment covers mRNA, lncRNA, and circRNA O8G profiles |
Anti-Oxidation Preparation Notes:
- Isolate RNA in the presence of antioxidants (e.g., deferoxamine mesylate) and under O₂-minimized conditions where feasible
- Avoid RNA fragmentation before shipping — intact RNA is less susceptible to oxidation than fragmented RNA
- Use nuclease-free water or TE buffer (pH 7.0) pre-treated to remove trace metals that catalyze oxidation
- Ship on dry ice; store at -80°C; avoid repeated freeze-thaw cycles
- Include a small aliquot of control RNA (e.g., untreated reference sample) shipped in parallel to help distinguish biological oxidation from handling-related background
Bioinformatics Analysis and Deliverables
O8G-Seq generates paired IP and input datasets per sample. Our pipeline integrates peak calling with input-normalized enrichment quantification, transcript annotation, and differential analysis.
Standard Deliverables:
| Deliverable | Description |
|---|---|
| Raw sequencing data | Demultiplexed read files for IP and input libraries with quality scores |
| Aligned reads | Reads aligned to reference genome/transcriptome for IP and input |
| O8G enrichment peaks | Statistically significant O8G-enriched regions called from IP vs input comparison |
| Normalized signal tracks | Input-normalized IP enrichment tracks for genome browser visualization |
| Peak annotation | Peaks annotated to transcripts, genomic features (CDS, 5'UTR, 3'UTR), and RNA biotype |
| QC report | IP enrichment efficiency, FRiP, read distribution, library complexity, replicate correlation |
| Differential O8G analysis | Statistically significant differentially oxidized regions between user-defined condition groups |
| Motif analysis | Sequence motifs enriched around O8G peak summits |
| GO/KEGG enrichment | Functional enrichment of O8G-modified transcripts (mRNA and total transcriptome workflows) |
Optional Advanced Analysis:
- O8G stoichiometry estimation — relative oxidation level per transcript, accounting for transcript abundance and IP efficiency
- Multi-omics integration — combined O8G data with matched RNA-seq, m6A-seq, or proteomics to link RNA oxidation to expression and translation changes
- G-rich region oxidation bias analysis — assessment of whether observed oxidation correlates with predicted susceptibility based on G-content and sequence context
- circRNA-specific O8G analysis — specialized annotation and differential analysis for circRNA oxidation profiles
- Custom visualization — publication-ready figures including genome browser tracks, heatmaps, volcano plots, and circos plots
- Epigenomic data analysis — see our dedicated Epigenomic Data Analysis service
Representative Data and Demo Results
The composite image below illustrates the data types delivered with each O8G-Seq project. All panels reflect standard bioinformatics output formats from our pipeline.
O8G Enrichment and Genomic Distribution:
- IP vs Input enrichment track (Panel A) — IGV-style genome browser view showing three parallel tracks: IP coverage, input coverage, and normalized enrichment ratio across a representative genomic locus. Peaks called above the significance threshold are highlighted, revealing O8G-enriched regions at single-transcript resolution.
- O8G peak distribution across RNA biotypes (Panel B) — horizontal stacked bar chart or pie chart showing the distribution of called O8G peaks across mRNA CDS, 5'UTR, 3'UTR, lncRNA, and circRNA — providing a global view of where oxidation occurs in the transcriptome.
- Metagene profile of O8G enrichment (Panel C) — average O8G IP/input enrichment signal plotted across the gene body from 5'UTR through CDS to 3'UTR. Reveals whether oxidation preferentially accumulates in specific transcript regions.
Differential Analysis and Functional Interpretation:
- Differential O8G volcano plot (Panel D) — each point represents an O8G-enriched transcript or region; x-axis shows log2 fold change of IP/input ratio between conditions; y-axis shows -log10 adjusted p-value. Hyper-oxidized transcripts in red, hypo-oxidized in blue.
- Sequence motif logo (Panel E) — consensus sequence motif enriched around O8G peak summits, identifying preferred nucleotide contexts for 8-oxoG deposition. G-rich motifs are characteristic of genuine oxidation signal.
- GO/KEGG enrichment bar chart (Panel F) — top enriched biological process terms among O8G-modified transcripts, linking oxidation patterns to specific pathways and providing functional context for differential analysis results.
All demo results are generated from representative datasets and reflect the standard analysis depth delivered with each project. Actual figures are customized to your experimental design and research question.
Applications Across Research Areas
8-oxoG deposition is linked to cancer through multiple mechanisms. In miRNA seeds, position-specific 8-oxoG redirects target recognition — 4o8G-miR-124 suppresses glioma while 3o8G-miR-122 promotes hepatocellular carcinoma (Eom et al., Nature Cell Biology, 2023). In circRNAs, ROS-induced O8G modification of circPLCE1 relieves tumor suppression by recruiting AUF1 for degradation (Zhao et al., Molecular Cancer, 2025). O8G-Seq enables transcriptome-wide mapping of these functionally significant oxidation events across cancer types, stages, and treatment conditions.
RNA oxidation accumulates with age, and senescent cells exhibit distinct O8G landscapes from their proliferating counterparts. Huang et al. (2025) applied O8G RIP-seq to compare mRNA oxidation profiles in normal versus senescent CaCO2 colon cancer cells, identifying transcripts and pathways selectively oxidized during senescence — including focal adhesion and RNA binding pathways. O8G-Seq provides a direct readout of the RNA oxidation component of the aging process.
Air pollution exposure induces transcriptome-wide RNA oxidation. Gonzalez-Rivera et al. (Communications Biology, 2020) identified 707 oxidized transcripts after low-level pollution exposure and 555 after high-level exposure in human bronchial epithelial cells, with oxidized transcripts enriched in cholesterol biosynthesis, fatty acid elongation, and cancer pathways. O8G-Seq is the direct approach for mapping how environmental exposures leave chemical marks on the transcriptome.
The brain is a high-oxidative-metabolism tissue with abundant RNA oxidation. 8-oxoG accumulation in neuronal transcripts is implicated in Alzheimer's disease, Parkinson's disease, and ALS — where oxidative stress and mitochondrial dysfunction converge on RNA as a target. O8G-Seq can map which transcripts are most vulnerable in specific brain regions, cell types, or disease models.
RNA guanine is more readily oxidized than DNA under the oxidative conditions prevalent in cardiovascular disease. A 2024 review in Pharmacological Research highlighted 8-oxoG in both DNA and RNA as contributors to atherosclerosis, ischemia-reperfusion injury, and cardiac hypertrophy (Li et al., 2024). O8G-Seq enables transcript-specific mapping of RNA oxidation in cardiac and vascular tissues under disease-relevant conditions.
Viral RNA genomes and host transcripts both undergo oxidation during infection-associated oxidative stress. In respiratory syncytial virus (RSV), the DNA/RNA repair enzyme OGG1 binds 8-oxoG in viral RNA, concealing oxidized guanine to maintain genetic fidelity — and inhibiting this interaction reduces viral progeny production (Pan et al., PLOS Pathogens, 2024). O8G-Seq can simultaneously profile oxidation on host and pathogen RNA during infection time courses.
Case Study: O8G-Seq Reveals mRNA Oxidation Profiles Distinguishing Normal from Senescent Cancer Cells
Method Comparison: O8G-Seq vs Alternative RNA Oxidation Detection Approaches
| Feature | O8G-Seq (Antibody IP) | ChLoRox-Seq | G>T Mutation Signature | OAbSeq |
|---|---|---|---|---|
| Principle | Anti-8-oxoG antibody enriches modified RNA fragments | Chemical labeling (K₂IrBr₆ + biotin) of 8-oxoG, streptavidin enrichment | 8-oxoG→T misincorporation during reverse transcription detected as G>T variants | Aniline-induced strand scission at abasic sites (8-oxoG oxidation products) |
| Antibody-free | No — requires anti-8-oxoG antibody | Yes | Yes | Yes |
| Resolution | Transcript/region (~100–200 nt) | Exon-level | Single-base (site of G>T substitution) | Single-base (site of strand scission) |
| Detects | Stable 8-oxoG in RNA | Stable 8-oxoG in RNA | 8-oxoG + other G oxidation products that cause G>T misreading | Abasic sites (terminal oxidation products); indirect 8-oxoG inference |
| Specificity | Antibody-dependent; validated against m6A, 8-oxoA | 94-fold over unmodified RNA (Burroughs et al., 2024) | Cannot distinguish 8-oxoG from other G→T-causing lesions | Detects abasic sites — 8-oxoG is a precursor, not directly detected |
| Input requirement | Moderate | Moderate | High (requires deep coverage for variant calling) | Low to moderate |
| Maturity | Established — published since 2020, multiple independent studies | Emerging — published 2024 | Conceptually straightforward but limited adoption | Emerging — published 2025 |
| IP/Input paired design | Yes — background correction via input control | Yes — streptavidin vs input comparison | No — relies on sequencing depth and variant caller sensitivity | No — relies on unique ligation-competent fragment formation |
| Best for | Transcriptome-wide O8G discovery; multi-sample comparison; established workflows with validated QC | Antibody-free labs; exon-level resolution; lower cost per sample | Site-level O8G mapping; miRNA seed oxidation studies with sufficient depth | Mapping terminal oxidation damage products; nucleotide-resolution abasic site detection |
O8G-Seq using antibody-based IP remains the most established method for transcriptome-wide 8-oxoG profiling, with paired input controls that directly correct for non-specific background — an advantage for multi-sample comparative studies where consistent normalization is critical. Newer antibody-free methods (ChLoRox-Seq, OAbSeq) offer higher resolution and are important developments, but their adoption is still emerging and each detects a different subset of the oxidation landscape (stable 8-oxoG vs abasic sites).
Frequently Asked Questions
References
- Gonzalez-Rivera JC, Baldridge KC, Wang Y, Patel A, Contreras LM, et al. Post-transcriptional air pollution oxidation to the cholesterol biosynthesis pathway promotes pulmonary stress phenotypes. Communications Biology, 2020, 3:480. https://doi.org/10.1038/s42003-020-01118-6
- Eom S, et al. Widespread 8-oxoguanine modifications of miRNA seeds differentially regulate redox-dependent cancer development. Nature Cell Biology, 2023, 25:1369-1383. https://doi.org/10.1038/s41556-023-01209-6
- Huang J, Lin Y, Zhao Y, Wei L. Overview of distinct 8-oxoguanine profiles of messenger RNA in normal and senescent cancer cells. Frontiers in Cell and Developmental Biology, 2025, 13:1443888. https://doi.org/10.3389/fcell.2025.1443888
- Zhao Q, Cai D, Xu H, et al. O8G-modified circPLCE1 inhibits lung cancer progression via chaperone-mediated autophagy. Molecular Cancer, 2025, 24:82. https://doi.org/10.1186/s12943-025-02283-0
- Pan L, Wang K, Hao W, et al. 8-Oxoguanine DNA Glycosylase 1 conceals oxidized guanine in nucleoprotein-associated RNA of respiratory syncytial virus. PLOS Pathogens, 2024, 20(10):e1012616. https://doi.org/10.1371/journal.ppat.1012616
- Burroughs MR, Sweet PJ, Contreras LM. Optimized chemical labeling method for isolation of 8-oxoG-modified RNA, ChLoRox-Seq, identifies mRNAs enriched in oxidation and transcriptome-wide distribution biases of oxidation events post environmental stress. RNA Biology, 2024, 21:1209-1225. https://doi.org/10.1080/15476286.2024.2427903
- Li Y, et al. The role of DNA and RNA guanosine oxidation in cardiovascular diseases. Pharmacological Research, 2024, 204:107187. https://doi.org/10.1016/j.phrs.2024.107187