CWC27 Antibody

What is CWC27 and what is its functional significance in cellular processes?

CWC27 (also known as SDCCAG10) is a spliceosome-associated protein that functions as a splicing factor in the Bact spliceosome complex. The protein consists of an N-terminal cyclophilin peptidyl-prolyl cis-trans isomerase (PPIase) domain and an unstructured C-terminus . Although the PPIase domain lacks cis-trans isomerase activity, it can still bind proline and is believed to participate in protein-protein interactions . The elongated C-terminal end of CWC27 interacts with CWC22 to form a landing platform for recruiting eIF4A3, a core component of the exon junction complex (EJC), to the spliceosome .

In vitro studies have demonstrated that CWC27 associates with the spliceosome during the Bact complex stage but is released prior to the conversion to the B* complex and assembly of the complete EJC . More importantly, recent in vivo evidence has confirmed its role in RNA splicing, with CWC27 dysfunction leading to alterations in splicing patterns including alternative splice site usage and intron retention .

What types of CWC27 antibodies are available for research applications?

Various CWC27 antibodies are available for research purposes, differing in their binding specificity, host organisms, clonality, conjugation, and applications. The following table summarizes key antibodies based on the search results:

This diversity allows researchers to select antibodies based on specific experimental requirements and target species .

What are the standard applications for CWC27 antibodies in research settings?

CWC27 antibodies are primarily used in the following applications:

• Western Blotting (WB): All available CWC27 antibodies can be used for Western blotting to detect the protein in cell or tissue lysates, allowing researchers to quantify expression levels and assess protein size .

• Immunofluorescence (IF): Many CWC27 antibodies are validated for both cultured cell immunofluorescence (IF (cc)) and paraffin-embedded section immunofluorescence (IF (p)), enabling visualization of CWC27's subcellular localization and co-localization with other spliceosomal components .

• Immunohistochemistry (IHC): Some antibodies can be used for IHC on frozen (IHC (fro)) or paraffin-embedded sections (IHC (p)), which is particularly valuable when studying CWC27 in tissues affected by mutations, such as retinal tissue .

• ELISA: Several CWC27 antibodies are suitable for enzyme-linked immunosorbent assays, allowing for quantitative analysis of CWC27 in solution .

The methodological approach should be selected based on the specific research question, with consideration of the antibody's validated applications and the target species relevance .

How does CWC27 participate in the splicing machinery at the molecular level?

CWC27 functions as a specialized component within the spliceosome complex, specifically during the Bact stage of spliceosome assembly. At the molecular level:

• CWC27 interacts directly with CWC22 through its elongated, solvent-exposed C-terminal end to form a critical landing platform .

• This CWC27-CWC22 complex then recruits eIF4A3, the core component of the exon junction complex (EJC) .

• CWC27 associates with the spliceosome during the Bact complex stage but is released from the spliceosome prior to conversion to the B* complex and assembly of the complete EJC .

The temporal regulation of CWC27's association and dissociation from the spliceosome is crucial for proper splicing progression. Although the PPIase domain of CWC27 lacks enzymatic cis-trans isomerase activity, it still possesses the ability to bind proline residues, suggesting that CWC27 may facilitate protein conformational changes or stabilize protein-protein interactions within the spliceosome without catalytic activity .

Recent in vivo evidence from the K338fs/K338fs Cwc27 mouse model has confirmed that disruption of CWC27 function leads to splicing defects including alternative splice site usage and intron retention, providing definitive evidence for its functional role in the splicing process .

What experimental evidence supports CWC27's role as a splicing factor in vivo?

While initial in vitro studies suggested CWC27's involvement in splicing, the K338fs/K338fs Cwc27 mouse model has provided compelling in vivo evidence for CWC27's function as a splicing factor:

• RNA-Seq Analysis: Bulk RNA sequencing of 3-month-old K338fs/K338fs Cwc27 mouse retinas revealed alterations in splicing patterns compared to wildtype mice, with significant differences in percent spliced in (PSI) values .

• Splicing Pattern Changes: The mouse model exhibited specific splicing defects including:

  • Alternative splice site usage

  • Intron retention

  • Changes in exon skipping patterns

• Cell-Type Specificity: Single-cell RNA sequencing (scRNA-seq) of 4-month-old mouse retinas demonstrated that splicing defects were particularly pronounced in rod photoreceptors, which constitute approximately 80% of cells in the retina .

• Endoplasmic Reticulum Stress: Positive staining for CHOP (a marker of ER stress) suggested that ER stress activation occurred in response to splicing pattern changes, potentially contributing to the disease mechanism .

These findings provide the first direct evidence that CWC27 functions as a splicing factor in an in vivo context, confirming what was previously only demonstrated in vitro .

How do CWC27 mutations affect gene expression and splicing patterns in affected tissues?

Research on the K338fs/K338fs Cwc27 mouse model has revealed several significant impacts of CWC27 mutations on gene expression and splicing:

• Cell-Type Specific Gene Expression Changes: Single-cell RNA sequencing of 4-month-old mouse retinas showed distinct transcriptional changes in different cell types:

  • Rod photoreceptors: Downregulation of mitochondrial-encoded transcripts related to oxidative phosphorylation enzymes

  • Müller glial (MG) cells: Upregulation of genes related to inflammation, consistent with glial activation in response to photoreceptor degeneration

  • Cone photoreceptors: Limited changes (only three upregulated and one downregulated genes)

  • Other retinal cell types (bipolar, ganglion, and amacrine cells): Minimal gene expression changes

• Splicing Alterations: Analysis of splicing patterns revealed:

  • Changes in alternative splice site usage

  • Increased intron retention

  • Alterations in exon inclusion/exclusion patterns

• Cellular Stress Response: The splicing defects appear to trigger endoplasmic reticulum stress, as evidenced by positive CHOP staining, which likely contributes to the observed retinal degeneration .

These findings suggest that CWC27 mutations exert their pathogenic effects through disruption of normal splicing mechanisms, with particularly pronounced effects in specific cell types such as rod photoreceptors that are especially sensitive to splicing defects .

What is the relationship between CWC27 dysfunction and retinal degeneration?

The relationship between CWC27 dysfunction and retinal degeneration involves several interconnected mechanisms:

• Clinical Evidence: Biallelic deleterious variants in CWC27 lead to a spectrum of overlapping phenotypes including retinal degeneration, which can occur in both syndromic and non-syndromic forms .

• Mouse Model Findings: The K338fs/K338fs Cwc27 mouse model exhibits:

  • Significant retinal dysfunction (50% reduction in retinal function by electroretinography)

  • Progressive retinal degeneration (50% decrease in retinal thickness)

  • Cell-type specific vulnerability (predominantly affecting photoreceptors)

• Molecular Mechanisms: Several pathways appear to contribute to retinal degeneration:

  • Disrupted splicing patterns in photoreceptors

  • Downregulation of mitochondrial-encoded transcripts in rod photoreceptors

  • Activation of endoplasmic reticulum stress response

  • Secondary inflammatory response in Müller glial cells

• Temporal Progression: By 6 months of age, the K338fs/K338fs Cwc27 mouse model shows significant retinal dysfunction and degeneration, with approximately 85% of photoreceptor cells remaining at 4 months, indicating progressive degeneration .

The cell-type specificity of the pathology, particularly affecting rod photoreceptors, may explain why retinal degeneration is a prominent feature of CWC27-related disorders, as photoreceptors have high metabolic demands and specialized gene expression patterns that may be particularly sensitive to splicing defects .

How can researchers validate CWC27 antibody specificity for their experimental systems?

Validating CWC27 antibody specificity is crucial for reliable experimental results. Researchers should implement the following methodological approaches:

• Positive Controls:

  • Use tissues or cell lines with known high CWC27 expression

  • Include recombinant CWC27 protein as a positive control in Western blots

  • Test against transfected lysates expressing full-length human SDCCAG10 protein

• Negative Controls:

  • CWC27 knockout or knockdown cells/tissues

  • Secondary antibody-only controls to assess background signal

  • Pre-absorption with immunizing peptide to confirm specificity

• Cross-reactivity Assessment:

  • Test the antibody against related cyclophilin family proteins

  • Verify reactivity across species when working with non-human models (checking predicted reactivity information)

• Multiple Antibody Validation:

  • Compare results using antibodies targeting different epitopes of CWC27 (e.g., N-terminal vs. C-terminal regions)

  • Use both tagged and untagged versions of CWC27 in overexpression systems

• Technique-specific Validation:

  • For Western blotting: Confirm band size matches the predicted molecular weight of CWC27

  • For immunofluorescence: Verify subcellular localization consistent with known CWC27 distribution

  • For immunoprecipitation: Confirm by mass spectrometry

These validation steps should be performed in the specific experimental system being studied to ensure antibody performance in that particular context.

What are the optimal conditions for using CWC27 antibodies in Western blotting?

Optimizing Western blotting conditions for CWC27 antibodies requires attention to several methodological details:

• Sample Preparation:

  • Use fresh tissue/cell lysates prepared with protease inhibitors

  • For nuclear proteins like CWC27, include nuclear extraction protocols

  • Denature samples at 95°C for 5 minutes in sample buffer containing SDS and a reducing agent

• Gel Selection and Transfer:

  • Use 10-12% polyacrylamide gels for optimal resolution of CWC27 (approximately 33-38 kDa)

  • Perform wet transfer to nitrocellulose or PVDF membranes at 30V overnight at 4°C for efficient transfer of nuclear proteins

• Blocking and Antibody Incubation:

  • Block membranes with 5% non-fat dry milk or 5% BSA in TBST for 1 hour at room temperature

  • For primary CWC27 antibody incubation:

    • Mouse polyclonal antibodies (e.g., ABIN523691): Use 1:500-1:1000 dilution, incubate overnight at 4°C

    • Rabbit polyclonal antibodies: Use 1:500-1:2000 dilution, incubate overnight at 4°C

  • For secondary antibody incubation: Use 1:5000-1:10000 dilution of appropriate HRP-conjugated secondary antibody for 1 hour at room temperature

• Detection and Troubleshooting:

  • Use enhanced chemiluminescence (ECL) for detection

  • If signal is weak, consider longer exposure times or signal amplification systems

  • If background is high, increase washing steps and optimize blocking conditions

• Controls:

  • Include lysate from cells overexpressing CWC27 as a positive control

  • Use GAPDH or β-actin as loading controls

  • Include a molecular weight marker to confirm correct band size

These conditions should be optimized for each specific CWC27 antibody, as binding characteristics may vary between antibodies targeting different epitopes .

How should researchers design experiments to study CWC27's role in splicing?

Designing robust experiments to study CWC27's role in splicing requires a multi-faceted approach:

• Model Systems Selection:

  • Cell lines: Human retinal cell lines or RPE1 cells (previously used in CWC27 knockdown studies)

  • Animal models: Consider the K338fs/K338fs Cwc27 mouse model, which shows clear splicing defects and retinal phenotypes

  • Patient-derived cells: If available, cells from patients with CWC27 mutations provide clinically relevant models

• Experimental Approaches:

  • Loss-of-function studies:

    • CRISPR-Cas9 knockout of CWC27

    • siRNA/shRNA knockdown of CWC27

    • Use of the K338fs/K338fs Cwc27 mouse model

  • Rescue experiments:

    • Re-expression of wildtype CWC27 in knockout/knockdown systems

    • Expression of mutant variants to identify critical domains

  • Protein interaction studies:

    • Co-immunoprecipitation to confirm CWC27 interaction with CWC22 and eIF4A3

    • Proximity ligation assays to visualize interactions in situ

• Splicing Analysis Methods:

  • Transcriptome-wide approaches:

    • Bulk RNA-seq to identify global splicing changes

    • Single-cell RNA-seq to detect cell-type specific effects

    • Direct RNA sequencing to avoid PCR biases

  • Targeted approaches:

    • RT-PCR with primers spanning exon-exon junctions

    • Minigene splicing assays for specific transcripts

    • Quantitative analysis of intron retention

• Functional Consequences Assessment:

  • Analysis of downstream pathways affected by splicing changes

  • Evaluation of endoplasmic reticulum stress (e.g., CHOP staining)

  • Assessment of cell viability and function in affected cell types

• Temporal Considerations:

  • Acute vs. chronic depletion of CWC27

  • Time-course analyses to distinguish primary from secondary effects

  • Developmental stage-specific effects, particularly in retinal cells

This experimental framework allows for comprehensive characterization of CWC27's role in splicing and the consequences of its dysfunction .

What controls should be included when using CWC27 antibodies in immunofluorescence?

Proper controls are essential for reliable immunofluorescence experiments with CWC27 antibodies:

• Primary Antibody Controls:

  • Positive Control: Tissues/cells known to express CWC27 (e.g., retinal tissue sections for studies related to retinal degeneration)

  • Negative Control: CWC27 knockout/knockdown cells or tissues

  • Peptide Competition: Pre-incubation of antibody with immunizing peptide should abolish specific staining

  • Isotype Control: Non-specific IgG from the same species as the primary antibody at the same concentration

• Secondary Antibody Controls:

  • Secondary-only Control: Omit primary antibody but include secondary antibody to assess non-specific binding

  • Cross-reactivity Control: Test secondary antibody on samples lacking primary antibody host species proteins

• Fixation and Permeabilization Optimization:

  • Compare different fixatives (PFA, methanol, acetone) as they may affect epitope accessibility

  • Optimize permeabilization conditions for nuclear proteins like CWC27

• Multiple Antibody Validation:

  • Use multiple antibodies targeting different epitopes of CWC27 (e.g., N-terminal vs. C-terminal)

  • Compare conjugated (e.g., AbBy Fluor® 555, AbBy Fluor® 350) and unconjugated antibodies with appropriate secondary antibodies

• Biological Validation:

  • Co-staining with other spliceosome markers to confirm expected co-localization

  • Comparison of staining patterns in wildtype vs. mutant tissues (e.g., K338fs/K338fs Cwc27 mouse model)

  • Correlation with functional data (e.g., areas with splicing defects)

• Technical Replication:

  • Include multiple technical and biological replicates

  • Blind scoring/quantification to prevent observer bias

These controls are particularly important when working with conjugated antibodies like the AbBy Fluor® 555-conjugated anti-CWC27 antibody, which is validated for immunofluorescence on both cultured cells and paraffin-embedded sections .

How can researchers integrate CWC27 antibody data with transcriptomic analysis?

Integrating CWC27 antibody data with transcriptomic analysis creates a powerful approach to understand CWC27's role in splicing:

• Experimental Design Integration:

  • Parallel Sample Processing: Process matched samples for antibody-based detection and RNA extraction

  • Time-Course Alignment: Align protein expression/localization data with transcriptomic changes over time

  • Cell-Type Resolution: Use techniques like single-cell RNA-seq alongside immunofluorescence to correlate cell-type specific expression patterns

• Multi-Modal Data Analysis:

  • Co-expression Networks: Identify genes whose expression or splicing correlates with CWC27 protein levels

  • Structure-Function Analysis: Correlate CWC27 protein domains (detected by domain-specific antibodies) with specific splicing events

  • Subcellular Localization: Correlate nuclear vs. cytoplasmic CWC27 distribution with splicing efficiency

• Validation Strategies:

  • Knockdown/Knockout Confirmation: Verify antibody specificity by confirming reduced signal in RNA-seq validated knockdown/knockout samples

  • Splicing-Specific Validation: For identified alternatively spliced transcripts, design isoform-specific antibodies to confirm protein-level changes

  • Functional Validation: Correlate splicing changes with downstream protein function using antibodies against affected targets

• Specific Methodological Approaches:

  • CLIP-seq with CWC27 Antibodies: Identify direct RNA targets of CWC27

  • Proximity Labeling: Use CWC27 antibodies for proximity labeling followed by mass spectrometry to identify protein interaction partners

  • Spatial Transcriptomics: Correlate spatial CWC27 protein distribution with regional transcriptomic profiles

• Data Visualization and Integration:

  • Create integrated visualizations showing both protein-level and RNA-level changes

  • Develop computational pipelines that incorporate both data types for predictive modeling

This integrated approach has been successful in studying the K338fs/K338fs Cwc27 mouse model, where protein-level analysis (including CHOP staining for ER stress) was combined with both bulk RNA-seq and scRNA-seq to provide a comprehensive understanding of CWC27's role in retinal biology and disease .

How should contradictory results from different CWC27 antibodies be resolved?

When faced with contradictory results from different CWC27 antibodies, researchers should implement a systematic troubleshooting approach:

• Epitope Mapping Analysis:

  • Determine Antibody Epitopes: Compare the binding regions of the contradictory antibodies (e.g., AA 1-291 vs. AA 201-300)

  • Post-translational Modifications: Consider whether PTMs might mask specific epitopes

  • Protein Isoforms: Check if antibodies might detect different CWC27 isoforms or splice variants

• Validation with Orthogonal Techniques:

  • mRNA Expression: Correlate protein detection with RT-qPCR measurement of CWC27 mRNA

  • Mass Spectrometry: Use targeted proteomics to independently quantify CWC27

  • Genetic Models: Test antibodies in CWC27 knockout/knockdown models or the K338fs/K338fs mouse

• Technical Optimization:

  • Fixation Conditions: Test multiple fixation protocols as they can affect epitope accessibility

  • Antigen Retrieval: Optimize antigen retrieval methods for each antibody

  • Blocking Conditions: Test different blocking agents to reduce non-specific binding

  • Antibody Concentration: Titrate each antibody to optimal working concentration

• Expert Consultation:

  • Contact antibody manufacturers for technical support

  • Consult with laboratories experienced in CWC27 research

  • Consider sending samples for independent validation

• Consensus-Based Approach:

  • Use multiple antibodies targeting different epitopes

  • Consider results reliable only when confirmed by at least two independent antibodies

  • Weight evidence based on antibody validation quality and experimental rigor

• Reporting Transparency:

  • Document all optimization attempts and contradictory results

  • Report antibody catalog numbers, lot numbers, and detailed methods

  • Consider publishing negative or contradictory results to inform the field

This methodical approach ensures that contradictions become opportunities for deeper understanding rather than obstacles to research progress.

What methodologies can help distinguish direct vs. indirect effects of CWC27 dysfunction?

Distinguishing direct from indirect effects of CWC27 dysfunction requires sophisticated experimental design and analysis:

• Temporal Resolution Studies:

  • Acute vs. Chronic Depletion: Compare immediate effects of CWC27 depletion (e.g., using inducible systems) with long-term consequences

  • Time-Course Analysis: Track molecular changes over time to establish causal relationships

  • Early Timepoint Analysis: Focus on 3-month timepoint in mouse models before significant degeneration occurs

• Molecular Interaction Mapping:

  • Direct Binding Assays: Use purified components to test direct RNA or protein interactions

  • CLIP-seq/eCLIP: Identify direct RNA targets of CWC27 protein

  • Proximity Labeling: Use BioID or APEX2 fused to CWC27 to identify proximal proteins in living cells

• Rescue Experiments:

  • Domain-Specific Rescue: Express specific CWC27 domains to rescue discrete functions

  • Tethering Assays: Artificially tether CWC27 to specific RNAs to test direct functional effects

  • Bypass Experiments: Express downstream components to bypass CWC27 requirement

• Computational Analysis:

  • Network Analysis: Construct protein-protein and protein-RNA interaction networks

  • Motif Analysis: Identify common sequence or structural motifs in affected RNAs

  • Kinetic Modeling: Model temporal changes to predict direct vs. cascade effects

• Cell-Type Specific Analysis:

  • Use scRNA-seq to distinguish primary affected cell types (e.g., rod photoreceptors) from secondarily affected cells (e.g., Müller glia)

  • Compare splicing changes across cell types to identify common direct targets

  • Employ cell-type specific CWC27 knockout/knockdown to isolate direct effects

• Comparative Studies:

  • Compare effects of CWC27 dysfunction with other splicing factors

  • Analyze conserved vs. species-specific effects across model organisms

  • Examine similarities/differences between in vitro and in vivo findings

This multi-faceted approach has revealed, for example, that downregulation of mitochondrial-encoded transcripts in rod photoreceptors is likely a direct effect of CWC27 dysfunction, while inflammatory gene upregulation in Müller glial cells appears to be a secondary response to photoreceptor degeneration .

How can researchers interpret splicing changes observed in CWC27 mutant models?

Interpreting splicing changes in CWC27 mutant models requires sophisticated analysis methods and careful consideration of biological context:

• Categorization of Splicing Events:

  • Classify Event Types: Distinguish between alternative splice site usage, intron retention, exon skipping, and other splicing variations

  • Quantify Event Magnitude: Measure percent spliced in (PSI) values and Δ-PSI between mutant and wildtype samples

  • Identify Cell-Type Specificity: Determine which splicing changes occur in which cell populations using scRNA-seq data

• Functional Impact Assessment:

  • Predict Coding Consequences: Analyze whether splicing changes affect protein coding potential (e.g., frameshift, premature termination)

  • Pathway Enrichment: Determine if affected transcripts cluster in specific biological pathways

  • Structure-Function Analysis: Predict how protein domain architecture might be altered by splicing changes

• Direct vs. Indirect Effects Discrimination:

  • Motif Analysis: Identify sequence motifs enriched near affected splice sites

  • Compare with Known CWC27 Functions: Assess whether changes align with CWC27's known role in the Bact spliceosome complex

  • Cross-Reference with Other Splicing Factors: Compare with splicing patterns in other spliceosomopathies

• Biological Consequence Correlation:

  • Correlate with Phenotypes: Link specific splicing events to observed cellular or organismal phenotypes

  • Time-Course Analysis: Track how splicing changes precede or follow other molecular events

  • Connect to Stress Responses: Evaluate whether splicing changes trigger cellular stress responses such as ER stress (CHOP activation)

• Validation Strategies:

  • Minigene Assays: Test specific splicing events in isolation

  • RT-PCR Validation: Confirm key splicing changes with isoform-specific primers

  • Protein-Level Confirmation: Verify that splicing changes result in altered protein production

• Therapeutic Implications:

  • Identify Targetable Events: Determine which splicing changes might be amenable to correction

  • Prioritize Critical Events: Focus on splicing changes most likely to drive pathology

  • Consider Compensatory Approaches: Identify pathways that might be targeted to compensate for splicing defects

This comprehensive interpretation framework has been applied to the K338fs/K338fs Cwc27 mouse model, revealing that splicing defects likely trigger ER stress, which contributes to retinal degeneration, thus providing insight into potential therapeutic strategies .