Note: HRP-conjugated versions are typically generated using amine-reactive crosslinkers, with protocols optimized for signal-to-noise ratios .
Western Blot: Detects RBM47 at ~64 kDa in human cell lines (A549, 293T) and tissues .
Immunohistochemistry: Localizes RBM47 in paraffin-embedded tissues (e.g., cancer biopsies) .
Flow Cytometry: Quantifies intracellular RBM47 in permeabilized cells .
Hepatocellular Carcinoma (HCC): RBM47 overexpression suppresses tumor progression by upregulating UPF1, reducing proliferation, and inducing apoptosis .
Breast Cancer: Loss of RBM47 correlates with metastasis by destabilizing tumor-suppressive mRNAs (e.g., DKK1, IL8) .
Papillary Thyroid Cancer: RBM47 stabilizes lncRNA SNHG5, inhibiting proliferation and activating autophagy .
RBM47 enhances IFNAR1 mRNA stability, amplifying antiviral ISG responses against DENV, ZIKV, and HSV-1 .
RBM47 (RNA Binding Motif Protein 47) is a multifunctional RNA-binding protein that plays crucial roles in regulating RNA stability, alternative splicing, and C-to-U RNA editing. RBM47 contains three RNA recognition motifs (RRMs) that are essential for its function in binding target mRNAs . The protein has dual significance in research: it demonstrates potent antiviral activity by stabilizing IFNAR1 mRNA to enhance interferon signaling, while also functioning as a tumor suppressor in several cancers . RBM47 is an interferon-stimulated gene (ISG) that can be induced by viral infection or interferon stimulation, making it an important component of the innate immune response .
For optimal Western blotting results with HRP-conjugated RBM47 antibodies:
Sample preparation: Extract proteins using RIPA buffer with protease inhibitors
Loading: Use 20-40 μg of total protein per lane
Transfer: Transfer to PVDF membrane at 100V for 90 minutes
Blocking: Block with 5% non-fat milk in TBST for 1 hour at room temperature
Primary antibody: Dilute RBM47 antibody 1:100 to 1:1000 (optimize for specific antibody) and incubate overnight at 4°C
Washing: Wash 3-5 times with TBST, 5 minutes each
Secondary antibody: If using non-conjugated primary antibody, incubate with HRP-conjugated secondary antibody (1:5000) for 1 hour at room temperature; if using direct HRP-conjugated RBM47 antibody, this step is skipped
Detection: Use enhanced chemiluminescence (ECL) substrate for visualization
Expected band size: Human RBM47 appears at approximately 64 kDa
Studies have successfully used this method to detect RBM47 expression in various cell lines, including 293T, HFF, HUVEC, and THP-1 cells, particularly following IFN-α stimulation .
Proper validation of RBM47 antibodies should include:
Western blot analysis using:
Immunoprecipitation followed by mass spectrometry:
Verify pull-down of RBM47 and check for expected interacting partners
Immunofluorescence/immunohistochemistry validation:
Compare staining patterns to mRNA expression data
Include RBM47 knockout or knockdown controls
Cross-validate with multiple antibodies targeting different epitopes
ELISA or dot blot with recombinant protein:
Establish detection limits and linear range of quantification
Research has shown that validation is particularly important for RBM47 antibodies as expression levels can vary significantly between tissues and following interferon stimulation .
For optimizing RIP assays with RBM47 antibodies:
Cross-linking protocol:
Use 1% formaldehyde for protein-RNA cross-linking (10 minutes at room temperature)
Quench with 0.125 M glycine for 5 minutes
Lysis conditions:
Lyse cells in buffer containing 25 mM Tris-HCl (pH 7.5), 150 mM NaCl, 1 mM EDTA, 1% NP-40, 5% glycerol with RNase inhibitors and protease inhibitors
Sonicate briefly to disrupt nuclear membranes without fragmenting RNA
Immunoprecipitation:
Pre-clear lysate with protein A/G beads for 1 hour
Incubate with RBM47 antibody (5-10 μg) overnight at 4°C
Add protein A/G beads for 2-4 hours at 4°C
Wash extensively with increasing stringency
RNA extraction and analysis:
Reverse cross-links with proteinase K treatment
Extract RNA using TRIzol reagent
Analyze by RT-qPCR or RNA sequencing
Published research has used this approach to demonstrate that RBM47 specifically binds to IFNAR1 mRNA at the 3'UTR region, with three distinct binding sites identified through RIP followed by qRT-PCR analysis . These studies showed significant enrichment of IFNAR1 mRNA, but not IFNAR2 mRNA, in RBM47-Flag immunoprecipitates, confirming the specificity of RBM47-RNA interactions .
When performing IHC with RBM47 antibodies across various tissue types:
Tissue-specific considerations:
Pancreatic tissue: Requires extended antigen retrieval (20 minutes in citrate buffer, pH 6.0) due to dense stroma
Breast tissue: May need lower antibody concentration (1:200) to avoid background staining
Lung tissue: Often requires shorter antigen retrieval time (10 minutes)
Optimal protocol:
Fixation: 10% neutral buffered formalin, 24 hours
Antigen retrieval: Heat-induced epitope retrieval in citrate buffer (pH 6.0)
Blocking: 1% bovine serum albumin (BSA) solution
Primary antibody: RBM47 antibody (1:100 dilution) overnight at 4°C
Secondary detection: HRP-conjugated Goat Anti-rabbit IgG (1:100) for 45 minutes
Visualization: 3,3'-diaminobenzidine (DAB) staining for 10 minutes with hematoxylin counterstain
Controls and validation:
Positive control: Include tissues with known RBM47 expression (e.g., interferon-stimulated tissues)
Negative control: Omit primary antibody or use tissues from RBM47 knockout/knockdown models
Expression pattern verification: RBM47 shows predominantly cytoplasmic localization
Research has successfully used this approach for evaluating RBM47 expression in pancreatic cancer tissues, revealing correlations between RBM47 expression and natural killer cell infiltration patterns .
Since RBM47 is an interferon-stimulated gene, interferon treatment can enhance detection:
Interferon stimulation protocol:
Treat cells with recombinant IFN-α (1000 U/ml) for 12-24 hours
For optimal time course analysis: Collect samples at 0, 3, 6, 12, and 24 hours
Use JAK inhibitors (e.g., Ruxolitinib) as negative control to confirm specificity
Cell-type specific considerations:
| Cell Type | Optimal IFN-α Concentration | Peak RBM47 Expression | Notes |
|---|---|---|---|
| 293T | 1000 U/ml | 12-16 hours | Strong induction |
| HFF | 500 U/ml | 8-12 hours | Moderate induction |
| HUVEC | 1000 U/ml | 12-24 hours | Sustained expression |
| THP-1 | 500-1000 U/ml | 6-12 hours | Rapid response |
Detection methods optimization:
Western blot: Increase sample loading to 40 μg for untreated samples
qRT-PCR: Design primers spanning exon junctions to avoid genomic DNA amplification
Immunofluorescence: Increase primary antibody incubation to overnight at 4°C
Research has demonstrated that IFN-α stimulation significantly upregulates both mRNA and protein levels of RBM47 in various cell types, with the promoter region of RBM47 containing three putative STAT1 binding motifs critical for IFN induction .
Common detection issues and solutions include:
Weak or no signal in Western blots:
Increase protein loading (40-60 μg)
Extend primary antibody incubation to overnight at 4°C
Use more sensitive detection systems (e.g., SuperSignal West Femto)
Consider pre-treating samples with IFN-α to upregulate RBM47 expression
Use RBM47-overexpressing cells as positive controls
Non-specific bands:
Increase blocking time (2 hours with 5% milk)
Use more stringent washing conditions (6 × 10 minutes with 0.1% TBST)
Validate with RBM47 knockout controls to identify the specific band
Use monoclonal antibodies for higher specificity
Inconsistent results between experiments:
Standardize cell culture conditions (density, passage number)
Control for interferon status of cells (endogenous interferon can vary)
Use internal loading controls (e.g., tubulin) for normalization
Prepare fresh lysates as RBM47 may degrade during storage
Tissue-specific detection challenges:
For tissues with low expression, consider using amplification systems
For highly autofluorescent tissues, use Sudan Black B to reduce background
Research has shown that knockout validation is particularly important for RBM47 antibodies, as demonstrated in studies where RBM47 knockout cell lines were used to confirm antibody specificity in Western blot and immunofluorescence assays .
To distinguish between RBM47 isoforms functionally:
Isoform-specific expression strategies:
Generate expression constructs for full-length RBM47, 3RRM variant (containing only the RNA recognition motifs), and ΔRRM variant (lacking RNA recognition motifs)
Use lentiviral systems for stable expression with tetracycline-inducible promoters
Validate expression by Western blot with antibodies recognizing different epitopes
Functional assays to differentiate isoforms:
Reporter assays: Test each isoform's ability to enhance ISRE (IFN-stimulated response element) promoter activity
Antiviral assays: Compare virus inhibition (e.g., VSV-GFP replication) between isoforms
mRNA stability assays: Measure IFNAR1 mRNA half-life in cells expressing different isoforms
RNA binding specificity assessment:
Perform RNA immunoprecipitation with each isoform
Use EMSA (electrophoretic mobility shift assay) to compare binding to IFNAR1 mRNA fragments
Conduct luciferase reporter assays with target 3'UTR sequences
Research has demonstrated that the RNA recognition domain of RBM47 is essential for its antiviral function, as the full-length RBM47 and 3RRM variant enhanced ISRE promoter activity and inhibited VSV-GFP replication, while the ΔRRM mutant did not .
To study RBM47-RNA complexes in situ:
Proximity ligation assay (PLA) for RNA-protein interaction:
Fix cells with 4% paraformaldehyde
Perform reverse transcription with BrdU-labeled nucleotides
Incubate with anti-RBM47 antibody and anti-BrdU antibody
Use PLA probes against the primary antibodies
Amplify signal according to PLA protocol
Visualize interactions as fluorescent dots
Fluorescence-based RNA-protein co-localization:
Perform RNA FISH for target mRNAs (e.g., IFNAR1) using fluorescent probes
Follow with immunofluorescence for RBM47 using specific antibodies
Analyze co-localization using confocal microscopy
Quantify using Pearson's or Mander's correlation coefficients
CLIP-seq (cross-linking immunoprecipitation-sequencing) optimization:
Cross-link cells with UV irradiation (254 nm, 400 mJ/cm²)
Immunoprecipitate with RBM47 antibodies
Perform RNA library preparation and high-throughput sequencing
Analyze binding motifs and RNA targets using bioinformatics tools
Biochemical fractionation with immunoblotting:
Separate cytoplasmic, nuclear, and polysome fractions
Perform Western blotting for RBM47 in each fraction
Compare distribution with target mRNAs detected by RT-qPCR
Research using these approaches has identified that RBM47 predominantly interacts with mRNAs in cytoplasmic compartments, consistent with its role in stabilizing IFNAR1 mRNA through binding to specific regions in the 3'UTR .
For optimal pulse-chase experiments to study RBM47's effect on mRNA stability:
Experimental design:
Cell models: Use matched pairs of RBM47-overexpressing, knockdown, and control cells
For primary cells: Consider using cells from RBM47 heterozygous mice compared to wild-type
Transcription inhibition approach:
Treat cells with actinomycin D (5 μg/ml)
Collect RNA at 0, 2, 4, 6, and 8 hours post-treatment
Extract total RNA using TRIzol reagent
Quantify target mRNAs (e.g., IFNAR1) by RT-qPCR
Calculate half-life using exponential decay model
Metabolic labeling approach:
Pulse cells with 4-thiouridine (4sU) for 1 hour
Chase with uridine for various time periods
Isolate labeled RNA using biotinylation and streptavidin pull-down
Analyze by RT-qPCR or RNA-seq
Controls and validation:
Include known stable (e.g., GAPDH) and unstable (e.g., c-Myc) mRNAs as controls
Verify RBM47 expression/knockdown by Western blot at each timepoint
Confirm binding to target mRNA by RIP-qPCR in parallel samples
Research has shown that RBM47 specifically stabilizes IFNAR1 mRNA but not IFNAR2 or STAT1 mRNAs in IFN-α-stimulated cells, with RT-PCR assays demonstrating reduced IFNAR1 mRNA content in RBM47 knockout cells compared to wild-type cells .
For developing and validating in vivo models to study RBM47:
Generation of genetic models:
Complete knockout models: Note that RBM47⁻/⁻ homozygous mice may not be viable
Heterozygous models: RBM47⁺/⁻ mice show significantly lower RBM47 protein levels in multiple tissues
Conditional knockout models: Use tissue-specific Cre recombinase expression
Knock-in models: Consider epitope-tagged RBM47 for antibody validation
Validation of antibody specificity in tissue samples:
Compare staining patterns between wild-type and RBM47⁺/⁻ tissues
Perform peptide competition assays to confirm specificity
Use multiple antibodies targeting different epitopes
Correlate protein detection with mRNA expression by in situ hybridization
Functional assessment in viral challenge models:
Challenge mice with various viruses (e.g., VSV, HSV-1)
Measure viral loads in blood, lung, spleen, and brain
Assess tissue injury through histological analysis
Quantify ISG expression in various tissues
Experimental considerations for tissue analysis:
| Tissue Type | Protein Extraction Method | Special Considerations |
|---|---|---|
| Blood | RBC lysis buffer, followed by RIPA | Monitor inflammatory status |
| Lung | Mechanical homogenization in RIPA | Higher protease inhibitor concentration |
| Spleen | Gentle homogenization in NP-40 buffer | Preserve immune cell populations |
| Brain | Regional dissection, specialized extraction buffer | Lipid interference with extraction |
Research has shown that in RBM47 heterozygous mice, both RBM47 and IFNAR1 protein levels were significantly reduced across multiple tissues compared to wild-type mice. These mice exhibited increased viral loads and more severe tissue injury upon viral challenge, with decreased expression of ISGs like IFIT1 and Cig5, despite normal IFN-β production .
When interpreting contradictory roles of RBM47:
Context-dependent function analysis:
Cell type specificity: Compare RBM47 function in epithelial cells versus immune cells
Pathway interaction: Assess how RBM47 interacts with IFN signaling versus cancer pathways
Target mRNA repertoire: Determine if RBM47 binds different mRNAs in different contexts
Integrated experimental approach:
Examine RBM47 expression across cancer and normal tissues with paired antibody and mRNA detection
Perform RNA-seq and RIP-seq in both cancer and immune contexts
Use gene ontology analysis to categorize RBM47-regulated genes by function
Mechanistic resolution of paradoxical findings:
Reconciliation framework:
Timing: Early versus late roles in disease progression
Dosage: Expression level dependent effects
Interaction partners: Different protein complexes in different contexts
For quantitative analysis of RBM47 expression:
Western blot quantification:
Normalization method: Express RBM47 relative to loading controls (e.g., tubulin, GAPDH)
Technical replicates: Perform at least three independent experiments
Statistical analysis: Apply paired t-tests for comparing treatments in the same cell line
Presentation: Include both representative blots and quantification graphs with error bars
Immunohistochemistry scoring systems:
H-score method: Intensity (0-3) × percentage of positive cells (0-100%), resulting in score of 0-300
Allred score: Sum of proportion score (0-5) and intensity score (0-3), resulting in score of 0-8
Digital analysis: Use image analysis software with validated algorithms for objective quantification
Correlation with clinical parameters:
Kaplan-Meier survival analysis based on RBM47 expression levels
Cox regression for multivariate analysis with other prognostic factors
Correlation with immune cell infiltration using Spearman's rank correlation
Multi-parameter analysis:
Combine RBM47 expression with target mRNA levels (e.g., IFNAR1)
Correlate with ISG expression or viral load in infection models
In cancer studies, correlate with known markers of progression
Research approaches have employed statistical methods such as Student's t-test for comparing RBM47 expression between groups, with error bars representing 95% confidence intervals obtained from multiple PCR reactions . When examining RBM47's relationship to other factors like NK cell infiltration in pancreatic cancer, correlation analysis has been valuable for establishing potential mechanistic relationships .
To investigate RBM47's splicing regulatory function:
High-throughput splicing analysis:
RNA-seq in RBM47 knockdown/knockout versus control cells
Analysis using specialized tools (e.g., rMATS, MISO, VAST-TOOLS)
Validation of alternative exon usage by RT-PCR
Minigene splicing reporter assays for candidate events
Direct binding assessment:
CLIP-seq to map RBM47 binding sites near alternative exons
Motif analysis to identify binding preferences
In vitro binding assays with synthetic RNA containing splicing regulatory elements
Mutagenesis of predicted binding sites in minigene constructs
Functional splicing complex analysis:
Co-immunoprecipitation with splicing factors
Mass spectrometry to identify RBM47 interactors
Immunofluorescence co-localization with splicing speckle markers
In vitro splicing assays with recombinant RBM47
Isoform-specific functional analysis:
Generate isoform-specific antibodies or tagged constructs
Compare full-length versus RRM-only constructs in splicing assays
Assess domain requirements for interaction with splicing machinery
Previous research has identified RBM47 as an alternative splicing factor, with studies demonstrating its role in regulating splicing events in various contexts . The three RNA recognition motifs (RRMs) in RBM47 are likely critical for this function, as suggested by functional studies with the 3RRM variant form versus the ΔRRM variant .
Integration of emerging technologies with RBM47 antibodies:
Single-molecule imaging approaches:
Single-molecule FISH combined with immunofluorescence
Live-cell imaging with fluorescently tagged RBM47
Single-molecule tracking to monitor RBM47-mRNA complex formation and dynamics
Super-resolution microscopy (STORM, PALM) for nanoscale localization
Mass spectrometry-based interaction mapping:
BioID or APEX2 proximity labeling with RBM47 fusion proteins
Quantitative proteomics of RBM47 interactome under different conditions
Crosslinking mass spectrometry to identify protein-protein interfaces
Targeted proteomics for monitoring RBM47 complex formation
Spatial transcriptomics integration:
Visium spatial gene expression with RBM47 immunofluorescence
Multiplex imaging of RBM47 with target mRNAs and cell type markers
3D reconstruction of RBM47-RNA interactions in tissue context
Correlation of spatial RBM47 patterns with local ISG expression
CRISPR-based technologies:
CRISPRi for targeted RBM47 silencing in specific cell populations
CRISPR activation to enhance RBM47 expression
CRISPR RNA tracking combined with RBM47 imaging
Domain-specific CRISPR editing to generate functional variants
These approaches can provide insights into how RBM47 dynamically interacts with target mRNAs like IFNAR1 in different cellular compartments, potentially revealing mechanisms underlying its context-dependent roles in cancer and antiviral immunity .
For investigating RBM47's RNA editing cofactor function:
Research has identified RBM47 as an essential cofactor of APOBEC1-mediated C-to-U RNA editing , suggesting it plays a critical role in determining target specificity or enhancing catalytic efficiency of the editing complex.
To differentiate between RBM47's diverse RNA processing functions:
Comprehensive target identification approach:
Perform parallel RIP-seq and CLIP-seq experiments
Compare binding patterns at 3'UTRs (stability) versus exon-intron boundaries (splicing)
Analyze binding at known editing sites versus stability regulatory elements
Develop computational pipelines to categorize binding patterns
Function-specific rescue experiments:
Generate domain-specific RBM47 mutants:
| Domain | Expected Function | Mutation Strategy |
|---|---|---|
| RRM1 | RNA binding | Point mutations in RNA-contact residues |
| RRM2-3 | Protein interaction | Surface mutations on non-RNA-binding face |
| C-terminal | Recruitment of effectors | Truncation or deletion |
Test each mutant for rescue of specific functions in RBM47-deficient cells
Temporal analysis of RNA processing:
Nascent RNA sequencing to capture co-transcriptional events
Pulse-chase RNA labeling to track newly synthesized transcripts
Subcellular fractionation to separate nuclear versus cytoplasmic functions
Time-course analysis following RBM47 induction or depletion
Mechanistic dissection:
For stability: Measure half-life of target mRNAs like IFNAR1
For splicing: Quantify inclusion/exclusion ratios of alternative exons
For editing: Measure C-to-U conversion efficiency at known sites
For translation: Analyze polysome association of target mRNAs
Research has demonstrated that RBM47 has multiple functions, including mRNA stabilization (e.g., IFNAR1, IL-10), alternative splicing regulation, and acting as a cofactor for C-to-U RNA editing . The RNA recognition motifs of RBM47 are essential for these functions, as demonstrated by experimental comparisons between full-length RBM47, the 3RRM variant, and the ΔRRM variant .
For translational research targeting RBM47:
Target validation methodology:
Genetic approach: Compare phenotypes of RBM47 knockout/knockdown versus overexpression
Pharmacological approach: Develop and test small molecule modulators of RBM47 function
Patient-derived models: Analyze RBM47 expression and function in primary cells
Correlation with clinical outcomes: Associate RBM47 levels with disease progression
Context-dependent function assessment:
For cancer applications: Evaluate effects in both primary tumors and metastatic settings
For antiviral applications: Test across multiple virus families and in different tissue types
For inflammatory conditions: Assess impact on both protective and pathological inflammation
For combined settings: Study RBM47 modulation in virus-associated cancers
Delivery and targeting strategies:
For enhancement strategies: mRNA delivery, CRISPR activation, or small molecule stabilizers
For inhibition strategies: siRNA/ASO approaches, protein degraders, or inhibitory peptides
Tissue-specific targeting: Employ tissue-tropic delivery vehicles
Temporal control: Use inducible systems for precise timing of modulation
Safety assessment:
Monitor interferon signaling and inflammatory responses
Evaluate impact on RNA processing globally
Assess compensatory mechanisms in long-term studies
Check for unexpected off-target effects on other RNA-binding proteins
Research has revealed potentially contradictory roles for RBM47 in different contexts, with tumor suppressor activity in several cancers but potential promotion of cell proliferation and immune evasion in pancreatic cancer . Additionally, since RBM47 stabilizes IFNAR1, it may contribute to both antiviral protection and inflammation, depending on context . These complex roles suggest that therapeutic targeting would require careful consideration of disease context and potential side effects.
For validating RBM47 antibodies in diagnostic applications:
Analytical validation protocol:
Specificity testing against recombinant RBM47 and closely related proteins
Sensitivity determination using serial dilutions of recombinant protein
Reproducibility assessment across multiple lots and operators
Stability testing under various storage and handling conditions
Clinical sample validation:
Test across diverse sample types (tissue sections, blood, liquid biopsies)
Compare with gold standard methods (e.g., mass spectrometry, RNA-seq)
Establish reference ranges in healthy versus disease populations
Perform blinded testing on well-characterized clinical cohorts
Diagnostic performance metrics:
Determine sensitivity, specificity, PPV, and NPV for specific clinical applications
Generate ROC curves and calculate area under curve (AUC)
Compare performance against existing diagnostic markers
Assess correlation with disease severity or prognosis
Implementation considerations:
Standardize protocols for sample collection and processing
Establish quantitative cutoff values for positive/negative results
Develop quality control materials and procedures
Design appropriate confirmation testing strategies
Research has shown variable RBM47 expression across different tissues and disease states, with reduced expression in certain cancers acting as a tumor suppressor , while showing increased expression in others like pancreatic cancer . Additionally, RBM47 expression is upregulated by interferon stimulation , suggesting potential utility as a biomarker for viral infections or interferon treatment response.