PRPF31 Antibody

What is PRPF31 and why is it important in research?

PRPF31 (PRP31 pre-mRNA processing factor 31 homolog) is a component of the spliceosome complex involved in pre-mRNA splicing. It is recruited to introns following the attachment of U4 and U6 RNAs and the 15.5K protein, making it crucial for the transition of the spliceosomal complex to the activated state . PRPF31's importance stems from its role as a component of the U4/U6.U5 tri-snRNP complex, which is essential for spliceosome assembly . Mutations in PRPF31 are associated with autosomal dominant retinitis pigmentosa type 11 (RP11), making it a significant target for retinal disease research .

What applications are compatible with PRPF31 antibodies?

PRPF31 antibodies have been validated for multiple applications including:

These applications have been tested with human and mouse samples . It's important to note that optimal antibody dilutions should be determined experimentally for each specific application and sample type.

How should PRPF31 antibodies be stored and handled?

PRPF31 antibodies should be stored at -20°C and remain stable for approximately one year after shipment. Aliquoting is generally unnecessary for -20°C storage. Most commercial PRPF31 antibodies are supplied in PBS with 0.02% sodium azide and 50% glycerol at pH 7.3 . Some smaller volume preparations (20μl) may contain 0.1% BSA as a stabilizer . Always follow manufacturer-specific storage instructions, as formulations may vary between suppliers.

How can I design experiments to study PRPF31 localization in retinal cells?

For effective localization studies of PRPF31 in retinal cells:

• Sample preparation: Prepare retinal sections or retinal cell cultures (primary or cell lines). For tissue sections, use antigen retrieval with TE buffer pH 9.0 or citrate buffer pH 6.0 .

• Antibody selection: Use antibodies targeting the N-terminus of PRPF31 to detect both wild-type and mutant proteins . This is particularly important for mutation studies.

• Co-staining approach: Include markers for nuclear speckles (e.g., SC35) and Cajal bodies (e.g., coilin) to assess PRPF31 localization within nuclear compartments .

• Controls: Include both positive controls (tissues known to express PRPF31) and negative controls (either no primary antibody or using tissues from knockout models).

• Analysis: Quantify the nuclear vs. cytoplasmic distribution of PRPF31 staining, as mutations can cause cytoplasmic mislocalization of PRPF31 .

Research has shown that in RP11 patient-derived cells, PRPF31 is predominantly localized in the cytoplasm, unlike control cells where it is mainly nuclear . This mislocalization pattern is critical for understanding disease mechanisms.

What are the best methods for quantifying PRPF31 protein expression?

Several validated approaches for PRPF31 protein quantification include:

• Western blotting: Most commonly used method. For accurate quantification, use:

  • Automated Western blotting systems (e.g., Jess system, ProteinSimple) for increased reproducibility

  • Image Studio Lite v5.2 (LI-COR Biosciences) for signal quantification

  • Loading controls such as β-actin or GAPDH for normalization

  • Recommended dilution of 1:10000 for PRPF31 antibodies such as EPR14587

• Immunofluorescence with quantitative imaging:

  • Fixed-cell imaging with consistent acquisition parameters

  • Z-stack imaging to capture the full cellular volume

  • Measurement of fluorescence intensity in defined cellular compartments

• Flow cytometry:

  • Particularly useful for comparing expression levels across cell populations

  • Requires permeabilization for intracellular PRPF31 detection

When comparing wild-type and mutant PRPF31 expression, Western blot analysis has revealed up to fivefold decrease in PRPF31 protein expression in mutation-carrying cells .

How can I optimize PRPF31 antibody for chromatin immunoprecipitation (ChIP) experiments?

While standard ChIP protocols work for PRPF31, optimization specific to this protein includes:

• Cross-linking optimization:

  • Use 1% paraformaldehyde for 30 minutes at room temperature

  • Perform crosslinking in the presence of protease inhibitors

• Nuclear extraction:

  • Lyse cells in buffer containing 20 mM HEPES, pH 7.4, 10 mM NaCl, 5 mM MgCl₂, and 0.1% NP-40

  • Incubate on ice for 10 minutes before collecting nuclei by centrifugation

• Sonication conditions:

  • Sonicate for 10 × 30 seconds to shear chromatin

  • Verify fragment size (200-500 bp) by gel electrophoresis

• Antibody selection and validation:

  • Use affinity-purified polyclonal antibodies against PRPF31

  • Include preimmune IgG preparations as negative controls

• Washing conditions:

  • Perform sequential washes with low salt buffer (0.1% SDS, 1% Triton X-100, 2 mM EDTA, 20 mM HEPES, pH 7.5, 150 mM NaCl) and high salt buffer (same composition but with 500 mM NaCl)

This optimized protocol has been successfully used to identify PRPF31-bound genomic regions in retinal tissues .

How do I generate and validate PRPF31 knockout models for retinal degeneration studies?

PRPF31 knockout models can be generated using these validated approaches:

• AAV-CRISPR/Cas9 system:

  • For SpCas9, gRNA targeting exon 6 of PRPF31 has shown 92.3 ± 0.58% editing efficiency in GFP-positive HEK293 cells

  • For SaCas9 (which allows packaging of Cas9 and gRNA in a single AAV vector), combinations of gRNAs targeting exons 2 and 3 of mouse Prpf31 showed highest knockout efficiency

  • Deliver via subretinal injection for localized retinal effects

• Validation of knockout:

  • Genomic DNA analysis: Use deep sequencing to quantify editing efficiency (typically 24-38% of Prpf31 is modified following AAV delivery)

  • Protein analysis: Western blotting with antibodies against PRPF31 to confirm reduced protein levels

  • Functional analysis: Assessment of retinal structure (OCT) and function (ERG)

• Important considerations:

  • Complete Prpf31 knockout is embryonically lethal and systemic knockout in neonatal mice results in stunted development and early death within 4 weeks

  • Consider temporal control systems (inducible Cre-loxP) for tissue-specific knockout

  • Heterozygous knockouts may better represent the autosomal dominant nature of PRPF31-RP

Keep in mind that subretinal injection of Prpf31-KO vectors results in severe and rapid structural and functional degeneration in photoreceptors and RPE, providing a useful model for testing therapeutic approaches .

What cellular phenotypes can be assessed using PRPF31 antibodies in retinitis pigmentosa models?

Key cellular phenotypes that can be assessed include:

• PRPF31 protein localization:

  • Nuclear vs. cytoplasmic distribution (mutations cause cytoplasmic mislocalization)

  • Co-localization with nuclear speckles and Cajal bodies

• Protein aggregation:

  • Detection of insoluble aggregates containing mutant PRPF31 and ubiquitin-conjugated proteins

  • Assessment of co-aggregation with other splicing factors (PRPF8, SNRNP200, PRPF4, PRPF6)

  • Quantification of heat shock proteins (e.g., Hsp70) co-localized with PRPF31 aggregates

• Splicing defects:

  • Altered assembly of tri-snRNP complexes with reduced U4/U6 snRNPs and accumulation of U5

  • Changes in nuclear speckle morphology

  • Reduced formation of active spliceosomes

• RPE-specific phenotypes:

  • Disruption of tight junctions (visualized with ZO1 staining)

  • Defects in phagocytosis of photoreceptor outer segments (showing a twofold decrease in PRPF31-mutated cells)

  • Drusen-like deposits in the retina

Proteomic analysis of insoluble fractions from patient-derived RPE cells has identified 934 differentially expressed proteins in these aggregates, including visual cycle proteins (RLBP1, DHRS3), protein folding components (HSPB1), and splicing factors .

How can I distinguish between haploinsufficiency and dominant-negative effects in PRPF31 mutation models?

To distinguish between these two mechanisms:

• Protein expression analysis:

  • Compare PRPF31 protein levels in patient vs. control cells using calibrated Western blotting

  • In haploinsufficiency, expect ~50% reduction in total PRPF31 protein

  • In dominant-negative effects, expression levels may vary, but functional impairment exceeds what would be expected from reduced levels alone

• Subcellular localization studies:

  • In haploinsufficiency models, wild-type PRPF31 maintains normal nuclear localization

  • In dominant-negative models, mutant PRPF31 may sequester wild-type protein in cytoplasmic aggregates (as observed in Prpf31 A216P mutant mice)

• Complementation experiments:

  • Overexpress wild-type PRPF31 in mutation-carrying cells:

    • If haploinsufficiency is the mechanism, this should rescue cellular phenotypes

    • If dominant-negative effects predominate, rescue will be incomplete

• Mutant protein interactions:

  • Perform co-immunoprecipitation with wild-type and mutant-specific antibodies

  • Assess whether mutant PRPF31 is incorporated into splicing complexes

  • Research has shown that mutant PRPF31 variants are not incorporated into splicing complexes, supporting a haploinsufficiency model in some cases

How can I use PRPF31 antibodies to investigate the molecular pathogenesis of retinitis pigmentosa?

Advanced applications for investigating pathogenesis mechanisms include:

• Proteomics of insoluble fractions:

  • Isolate insoluble protein fractions from patient-derived cells

  • Use PRPF31 antibodies to confirm presence of PRPF31 in aggregates

  • Perform mass spectrometry to identify co-aggregating proteins

  • This approach has identified 934 differentially expressed proteins in RP11-RPE cell insoluble fractions, revealing affected pathways including mRNA splicing, protein folding, and UPR

• RNA-protein interaction studies:

  • RNA immunoprecipitation (RIP) to identify RNAs bound by PRPF31

  • Individual nucleotide resolution UV crosslinking and immunoprecipitation (iCLIP)

  • These techniques can reveal alterations in RNA processing in disease states

• Splicing analysis pipeline:

  • RNA-seq of patient-derived cells followed by differential splicing analysis

  • Validation of splicing changes using RT-PCR

  • Studies have shown that 11% of genes in RPEs of Prpf31 mutant mice were differentially spliced, including genes related to inflammation, oxidative stress, retinol metabolism, and cilia formation

• Cellular stress response:

  • Assessment of unfolded protein response (UPR) activation

  • Investigation of autophagy and lysosomal pathways

  • Quantification of ubiquitinated proteins in PRPF31 mutant cells

  • Targeting these pathways with compounds like Rapamycin has been shown to reduce cytoplasmic aggregates and improve cell survival

Using these approaches, research has demonstrated that progressive protein aggregate accumulation, rather than direct PRPF31-initiated mis-splicing, overburdens waste disposal machinery in RPE cells .

What are the recommended controls when using PRPF31 antibodies in experimental studies?

Rigorous experimental design requires these controls:

• Antibody validation controls:

  • PRPF31 knockout or knockdown cells/tissues as negative controls

  • Overexpression systems for positive controls

  • Isotype controls (e.g., rabbit IgG) to assess non-specific binding

  • Testing multiple antibodies targeting different epitopes of PRPF31

• Sample-specific controls:

  • CRISPR/Cas9-corrected isogenic controls from patient-derived cells

  • Age-matched and tissue-matched controls for in vivo studies

  • For retinal studies, non-retinal tissues as specificity controls

• Technical controls for specific applications:

  • For Western blotting: Loading controls (β-actin, GAPDH); molecular weight markers to confirm band specificity

  • For immunoprecipitation: Pre-immune serum or IgG controls

  • For immunofluorescence: Secondary antibody-only controls; peptide competition assays

  • For ChIP: Input samples and IgG precipitation controls

• Functional rescue controls:

  • Expression of wild-type PRPF31 in mutant cells

  • Gene therapy controls such as KO-Rescue vs. KO-PBS eyes in animal models

In PRPF31 retinitis pigmentosa studies, CRISPR/Cas9-corrected isogenic controls have been particularly valuable for distinguishing disease-specific effects from individual genetic variation .

How can I investigate PRPF31's role in tri-snRNP assembly and splicing using immunofluorescence?

To study PRPF31's role in splicing complexes:

• Co-localization analysis approach:

  • Perform dual or triple immunofluorescence with antibodies against:

    • PRPF31

    • Other tri-snRNP components (PRPF8, SNRNP200, PRPF4, PRPF6)

    • Nuclear speckle markers (SC35, SRSF2)

    • Cajal body markers (coilin)

  • Use high-resolution confocal or super-resolution microscopy

  • Quantify co-localization using Pearson's correlation coefficient or Manders' overlap coefficient

• Functional assessments:

  • Fluorescence recovery after photobleaching (FRAP) to assess dynamics of PRPF31 in nuclear compartments

  • Live-cell imaging with fluorescently tagged PRPF31 and other splicing factors

  • Pre-mRNA processing analysis using splicing reporter constructs

• Analysis metrics:

  • Measure the size and number of nuclear speckles (reduced in PRPF31 mutant cells)

  • Quantify the intensity of PRPF31 staining in Cajal bodies vs. speckles

  • Assess the ratio of mature tri-snRNPs vs. individual snRNPs

Research has shown that mutations in PRPF31 lead to tri-snRNP assembly defects in Cajal bodies with reduced U4/U6 snRNPs and accumulation of U5, resulting in smaller nuclear speckles and reduced formation of active spliceosomes . These changes correlate with global splicing dysregulation in patient-derived retinal cells.

How should I interpret discrepancies in PRPF31 antibody staining patterns between different studies?

When encountering discrepancies:

• Antibody-specific factors:

  • Different epitopes: Antibodies targeting N-terminal vs. C-terminal epitopes may show different patterns, especially with truncated mutants

  • Clonality: Monoclonal antibodies are more specific but may miss some isoforms; polyclonal antibodies detect more variants but can show cross-reactivity

  • Host species and isotype can affect background and sensitivity

  • Validation status: Not all antibodies undergo rigorous validation across applications

• Technical variables:

  • Fixation methods significantly impact nuclear protein detection (paraformaldehyde vs. methanol)

  • Antigen retrieval methods (TE buffer pH 9.0 vs. citrate buffer pH 6.0)

  • Blocking reagents and incubation times

  • Detection systems (direct fluorescence, amplification methods)

• Biological variables:

  • Cell/tissue type differences: PRPF31 expression is enriched in photoreceptor cells and inner nuclear layer of the retina

  • Disease state: Mutations cause mislocalization to cytoplasm in patient cells

  • Development stage and cell cycle phase

• Resolution of discrepancies:

  • Use multiple antibodies targeting different epitopes

  • Employ complementary techniques (immunofluorescence, Western blotting, in situ hybridization)

  • Include appropriate positive and negative controls

  • Report detailed methodology to facilitate comparison between studies

In situ hybridization studies show that PRPF31 mRNA is strongly expressed in the outer nuclear layer (photoreceptor nuclei) and inner nuclear layer of the retina , which should be considered when interpreting immunostaining results.

What are common technical challenges when using PRPF31 antibodies and how can they be addressed?

Common challenges and solutions include:

• High background in immunofluorescence:

  • Increase blocking time (2-3 hours with 5-10% normal serum)

  • Optimize antibody concentration (test dilutions from 1:50-1:500 for IF-P)

  • Use alternative blocking agents (BSA, fish gelatin, commercial blockers)

  • Increase washing duration and detergent concentration

  • Consider using monoclonal antibodies for higher specificity

• Weak or absent Western blot signal:

  • Optimize protein extraction methods (for nuclear proteins like PRPF31)

  • Adjust antibody concentration (1:2000-1:16000 range recommended)

  • Increase exposure time or use more sensitive detection systems

  • Use fresh antibody preparations and verify storage conditions

  • Consider antigen retrieval techniques for Western blots

• Inconsistent immunoprecipitation:

  • Increase antibody amount or lysate incubation time

  • Use antibodies specifically validated for IP applications

  • Test different lysis buffers to preserve protein interactions

  • Consider crosslinking antibodies to beads to reduce background

  • Available agarose-conjugated formats may improve results

• Detection of aggregated species:

  • Use non-reducing conditions for aggregate preservation

  • Include protease inhibitors during sample preparation

  • Consider native gel electrophoresis for intact complexes

  • For insoluble aggregates, use specialized fractionation protocols that have been successful in isolating PRPF31-containing aggregates

For PRPF31 research specifically, it is recommended to test antibody reactivity in both nuclear and cytoplasmic fractions, as mutation-related mislocalization can shift protein distribution significantly .

How can I reconcile contradictory findings about PRPF31 function in different experimental systems?

To address contradictory findings:

• Systematic analysis of model systems:

  • Different species: Mouse models show milder phenotypes than human patients

  • Cell types: PRPF31 effects are more pronounced in photoreceptors and RPE cells than other cell types

  • Mutation types: Different mutations (truncation vs. missense) may operate through different mechanisms

  • Developmental timing: Embryonic vs. adult phenotypes may differ significantly

• Mechanism-focused investigations:

  • Haploinsufficiency: Dominant in many PRPF31 mutations

  • Dominant-negative effects: Observed with specific mutations like A216P

  • Aggregate toxicity: Progressive accumulation of protein aggregates

  • Splicing defects: Global vs. retina-specific alternative splicing

• Methodological reconciliation:

  • Compare acute (CRISPR/Cas9) vs. chronic (germline) models

  • Evaluate protein level reduction vs. complete knockout effects

  • Consider gene dosage effects and complementation studies

  • Assess temporal aspects of degeneration progression

• Integration of findings:

  • PRPF31 mutations may initially cause haploinsufficiency effects on splicing

  • Progressive accumulation of mutant proteins leads to aggregation

  • Aggregates sequester wild-type PRPF31 and other proteins

  • Waste disposal machinery becomes overburdened, exacerbating cellular stress

  • Retinal cells are particularly vulnerable due to high metabolic demands

Research suggests that the retina has a relatively higher demand for PRPF31 function, resulting in increased sensitivity to PRPF31 reduction . This helps explain why PRPF31 mutant carriers develop retina-specific disease, as the remaining PRPF31 levels from the wild-type allele are sufficient for normal function in other tissues but inadequate for retinal cells.

How can PRPF31 antibodies be used to evaluate therapeutic approaches for retinitis pigmentosa?

PRPF31 antibodies serve as essential tools for evaluating therapeutics:

• Gene therapy assessment:

  • Measuring PRPF31 protein restoration following AAV-mediated gene augmentation

  • In successful gene therapy trials, Western blotting confirmed restoration of PRPF31 protein levels in treated eyes

  • Immunofluorescence to assess proper nuclear localization of expressed PRPF31

• Protein aggregate reduction strategies:

  • Quantifying changes in cytoplasmic PRPF31 aggregates following treatment

  • Monitoring co-aggregating proteins (e.g., visual cycle proteins)

  • Assessing autophagy activation through LC3 and p62 markers alongside PRPF31

  • Rapamycin treatment has been shown to reduce PRPF31-containing cytoplasmic aggregates and improve cell survival

• Combinatorial therapy monitoring:

  • Using PRPF31 antibodies alongside markers of retinal health

  • Evaluating sequential therapy effects (e.g., aggregate clearance followed by gene therapy)

  • Assessing retinal structure preservation in treated areas

• Diseased cell identification for cell replacement strategies:

  • Identifying cells with cytoplasmic PRPF31 mislocalization as targets for replacement

  • Monitoring integration of transplanted healthy cells

Therapeutic targeting of waste disposal mechanisms, particularly activation of the autophagy pathway, has shown promise in reducing cytoplasmic aggregates and could potentially be combined with gene therapy approaches for PRPF31-adRP patients .

What are the experimental considerations when using PRPF31 antibodies to monitor disease progression in animal models?

Key considerations include:

• Temporal profiling approach:

  • Establish baseline PRPF31 expression and localization in healthy controls

  • Create a timeline of sampling points matching disease progression stages

  • In rapidly progressing CRISPR-induced models, evaluate at 1-10 weeks post-injection

  • In slower progressing models (e.g., A216P mice), assess changes over months

• Multi-parameter assessment:

  • Combine PRPF31 antibody staining with:

    • Photoreceptor markers (rhodopsin, recoverin)

    • RPE markers (RPE65, ZO-1)

    • Cell death markers (TUNEL, cleaved caspase-3)

    • Stress markers (BiP/GRP78, CHOP)

• Sample collection and processing:

  • For retinal sections: Use consistent fixation methods across timepoints

  • For protein analysis: Separate nuclear and cytoplasmic fractions

  • For insoluble aggregates: Use specialized fractionation protocols

• Quantitative measures:

  • Measure PRPF31 protein levels by Western blot

  • Quantify nuclear vs. cytoplasmic PRPF31 distribution

  • Assess co-localization with aggregate markers

  • Track the percentage of cells with PRPF31 mislocalization

In CRISPR-based models, genomic DNA analysis revealed that 38.02 ± 12.66% of mouse Prpf31 was modified in treated-rescue eyes, while 24.08 ± 3.37% was modified in knockout-PBS eyes at 10 weeks post-injection . This higher percentage of edited cells in rescue conditions indicates preservation of cells that would otherwise be lost to degeneration.

How can we distinguish between primary molecular effects of PRPF31 mutations and secondary cellular responses?

To differentiate primary from secondary effects:

• Temporal analysis framework:

  • Conduct time-course studies beginning at earliest detectable stages

  • In patient-derived models, use isogenic controls to isolate mutation effects

  • Identify the sequence of molecular changes following PRPF31 mutation

• Direct splicing effects vs. downstream consequences:

  • Primary effects: Pre-mRNA splicing defects, tri-snRNP assembly alterations

  • Secondary effects: Protein aggregation, UPR activation, autophagy impairment

  • Tertiary effects: Cell death pathways, inflammatory responses

• Mechanistic intervention studies:

  • Use splicing modulators to determine if correcting splicing defects reverses other phenotypes

  • Target protein aggregation (e.g., with Rapamycin) to determine if splicing defects remain

  • Inhibit specific stress pathways to assess their contribution to disease progression

• Multi-omics integration:

  • Compare transcriptomic (splicing changes) and proteomic (aggregation, expression changes) data

  • Identify earliest molecular alterations before morphological changes

  • Research has identified 1333 differentially expressed genes in RPE cells of Prpf31 mutant mice, with particular impact on inflammation, oxidative stress, and retinol metabolism pathways

Current evidence suggests a model where initial splicing defects lead to protein misfolding and aggregation, which progressively overburdens cellular waste disposal mechanisms, creating a cycle of increasing cellular stress that ultimately leads to retinal cell death .