Quantitative Analysis of Alternative Pre-mRNA Splicing in Mouse Brain Sections Using RNA In Situ Hybridization Assay
August 26th, 2018
8.4K views
An in situ hybridization (ISH) protocol that uses short antisense oligonucleotides to detect alternative pre-mRNA splicing patterns in mouse brain sections is described.
Overview
This article describes an in situ hybridization (ISH) protocol utilizing short antisense oligonucleotides to detect alternative pre-mRNA splicing patterns in mouse brain sections. This method allows for the simultaneous analysis of splicing patterns in various subtypes within complex biological structures.
Key Study Components
Area of Science
- Neuroscience
- Genetics
- Molecular Biology
Background
- Alternative pre-mRNA splicing is crucial for generating protein diversity.
- Understanding splicing patterns can provide insights into brain function and disorders.
- In situ hybridization techniques are essential for studying splicing in tissue contexts.
- This study focuses on mouse brain sections to explore splicing variations.
Purpose of Study
- To develop a sensitive assay for detecting alternative splicing in situ.
- To analyze splicing patterns across different brain regions.
- To enhance the understanding of splicing mechanisms in the brain.
Methods Used
- In situ hybridization using short antisense oligonucleotides.
- Shock anti-static exon junction probes for isoform-specific signals.
- Signal amplification technology to increase detection sensitivity.
- Analysis of exon inclusion and splicing percentages in various anatomical areas.
Main Results
- Robust hybridization signals were achieved using the developed method.
- Alternative splicing patterns were successfully detected in mouse brain sections.
- The technique allows for simultaneous analysis of multiple splicing events.
- Results contribute to understanding the complexity of splicing in neural tissues.
Conclusions
- The ISH protocol provides a valuable tool for studying alternative splicing.
- Findings enhance knowledge of splicing mechanisms in the brain.
- This method can facilitate further research into splicing-related neurological conditions.
Frequently Asked Questions
What is in situ hybridization?
In situ hybridization is a technique used to detect specific nucleic acid sequences within fixed tissues or cells.
Why is alternative splicing important?
Alternative splicing allows a single gene to produce multiple protein isoforms, contributing to protein diversity and function.
How does this method improve sensitivity?
The method employs signal amplification technology and specific probes to enhance detection sensitivity of splicing events.
What are exon junction probes?
Exon junction probes are designed to bind to specific regions of mRNA, allowing for the detection of splicing events.
Can this method be applied to other tissues?
While this study focuses on mouse brain sections, the method can potentially be adapted for other tissues.
What are the implications of this research?
The research provides insights into splicing mechanisms that could inform studies on neurological disorders.
Executive Industry Relevance
This method enables spatially resolved quantification of alternative splicing events in complex tissues, addressing a critical gap in target validation where bulk RNA approaches mask cellular heterogeneity. By providing isoform-specific signals at single-cell resolution in anatomically defined brain regions, it supports mechanistic de-risking of splicing-dependent targets in neuroscience drug discovery. The ability to calculate percent spliced in (PSI) values from exon inclusion and skipping signals offers a quantitative, reproducible metric for assessing target engagement and pathway modulation in preclinical models.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of therapeutic hypotheses by linking specific splice isoforms to cell-type-specific expression patterns in disease-relevant brain regions.
- Operational Value: Provides a robust, sensitive assay system for examining alternative splicing patterns in situ within tissue slices, reducing reliance on dissociated cell models that lose spatial context.
Screening & Assay Development
- Scientific Value: Uses shock anti-static exon junction probes to generate isoform-specific hybridization signals, enabling simultaneous analysis of multiple subtypes within complex biological structures.
- Operational Value: Signal amplification technology increases detection sensitivity, producing robust signals suitable for quantitative imaging and automated analysis workflows.
Translational & Preclinical Research
- Scientific Value: Facilitates disease-relevant system analysis by mapping splicing patterns across anatomical areas such as cortex and hippocampus, supporting biomarker discovery for neuropsychiatric indications.
- Operational Value: Enables parallel processing of adjacently cut tissue sections under identical conditions, ensuring data accuracy for cross-sectional comparisons in preclinical studies.
Pipeline & Workflow Integration
The method fits within the discovery biology phase, where spatially resolved splicing data informs target selection and mechanistic understanding before assay development for high-throughput screening.
- Discovery Biology: Supports hypothesis testing by revealing cell-type-specific alternative splicing patterns that may be obscured in bulk tissue analyses.
- Screening: Generates quantitative, spatially resolved readouts (e.g., PSI values) that can inform assay design for splicing-modulating compounds.
- Analytics: Enables calculation of percent spliced in from exon inclusion and skipping signal counts, providing a normalized metric for comparing conditions across brain regions.
- Translational Research: Connects discovery findings to preclinical continuity by validating splicing changes in anatomically defined regions relevant to disease models.
- Enterprise Reuse: The probe-based approach is adaptable to multiple alternative exons, positioning it as a reusable platform for splicing analysis across diverse targets and disease areas.
Operational & Enterprise Impact
- Scientific Value: Reduces mechanistic ambiguity by linking specific splice isoforms to defined anatomical locations, increasing confidence in target-disease relationships.
- Operational Value: Standardized protocol with built-in controls (e.g., adjacently cut slides, identical processing) enhances reproducibility across sites and users.
- Strategic Value: Supports better go/no-go decisions by providing spatially resolved efficacy and mechanism data early in the discovery pipeline.
- Portfolio Impact: Enables risk-adjusted prioritization of targets based on validated splicing expression in disease-relevant neural circuits.
Implementation Considerations
- Requires expertise in RNA in situ hybridization, tissue sectioning, and quantitative image analysis for punctate dot counting.
- Dependent on hybridization ovens, humidity control trays, and reagent systems for probe hybridization, signal amplification, and detection (e.g., Fast Red).
- Necessitates standardization across teams for slide preparation, probe incubation, and washing steps to ensure comparability of PSI calculations.
- Adaptation to new exons requires design and validation of exon junction-specific probes, with sensitivity to target sequence accessibility.
- Practical limitation: Multi-color labeling is not currently available, requiring sequential analysis on separate slides, which increases tissue sectioning and processing demands.
Biopharma FAQs
Why does counting exon inclusion and skipping signals matter for target validation?
Counting signals from exon inclusion- and skipping-specific probes enables calculation of percent spliced in (PSI) values, providing a quantitative measure of isoform expression in specific brain regions. This supports target validation by linking splice variant abundance to anatomical context and disease relevance.
How does isolating the independent variable (probe specificity) fit the discovery pipeline?
Using exon junction probes that distinguish between inclusion and skipping isoforms isolates the splicing event as the independent variable, enabling clear attribution of signal changes to specific molecular alterations. This fits early discovery by clarifying mechanism-of-action for splicing-modulating compounds.
What quantitative dependent variable measurements enable PSI calculation?
The number of red punctate dots from inclusion-specific and skipping-specific probes, along with total signal, serves as the dependent variable for PSI calculation. These counts are normalized to determine the percentage of transcripts containing the exon across cell populations in defined brain regions.
Why do replication requirements matter for cross-functional collaboration?
Replicating the assay on adjacently cut tissue sections processed identically ensures that signal differences reflect true biological variation rather than technical artifacts. This supports reliable data sharing between discovery, preclinical, and translational teams for consistent target assessment.
What statistical analysis capabilities are required before implementation?
Implementation requires the ability to quantify and compare signal counts across biological replicates and anatomical regions, using methods such as mean PSI with standard deviation or confidence intervals. Basic statistical comparison of PSI values between conditions (e.g., wild type vs. mutant) is necessary to assess significant splicing changes.
