Generation of Cancer Cell Clones to Visualize Telomeric Repeat-containing RNA TERRA Expressed from a Single Telomere in Living Cells
January 17th, 2019
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Here, we present a protocol to generate cancer cell clones containing a MS2 sequence tag at a single subtelomere. This approach, relying on the MS2-GFP system, enables visualization of the endogenous transcripts of telomeric repeat-containing RNA (TERRA) expressed from a single telomere in living cells.
Overview
This protocol describes a method for generating cancer cell clones with a MS2 sequence tag at a single subtelomere, allowing for the visualization of TERRA transcripts in living cells.
Key Study Components
Area of Science
- Cell Biology
- Cancer Research
- Genetics
Background
- Telomeres play a crucial role in chromosome stability.
- TERRA is a noncoding RNA associated with telomeres.
- Understanding TERRA localization can provide insights into telomere function.
- Current methods lack the ability to visualize TERRA from a single telomere.
Purpose of Study
- To develop a technique for visualizing TERRA from a specific telomere.
- To investigate the localization of TERRA in living cells.
- To enhance understanding of telomere biology.
Methods Used
- Culture AGS cells to 50-60% confluence.
- Transfect cells with sgRNA Cas9 vector and MS2 cassette.
- Replace medium with Neomycin-containing medium.
- Use Tripsyn for cell detachment in a 96-well plate.
Main Results
- The method successfully visualizes TERRA transcripts in living cells.
- Demonstrated the localization of TERRA to a single telomere.
- Provided a new tool for studying telomere dynamics.
- Enabled further exploration of telomere-related questions.
Conclusions
- This protocol offers a novel approach to study TERRA.
- It enhances the understanding of telomere function in cancer biology.
- Future studies can leverage this method for deeper insights.
Frequently Asked Questions
What is TERRA?
TERRA is a noncoding RNA associated with telomeres, playing a role in telomere regulation.
How does this method improve visualization of TERRA?
This method allows for the visualization of TERRA transcripts from a single telomere in living cells.
What cell line is used in this protocol?
AGS cells are used for this protocol.
What is the significance of studying TERRA?
Studying TERRA can provide insights into telomere function and its implications in cancer.
Who are the contributors to this study?
Claudio Oss Pegorar and Nicole Bettin are graduate students contributing to this study.
What are the main steps in the protocol?
The main steps include cell culture, transfection, medium replacement, and cell detachment.
Executive Industry Relevance
Visualizing TERRA dynamics from a single telomere in living cancer cells addresses a critical gap in telomere biology, enabling mechanistic de-risking of telomere-targeted therapeutic hypotheses. This approach supports target validation by providing direct evidence of TERRA localization and function, which is relevant for oncology drug discovery programs focused on telomere maintenance mechanisms. The method enhances predictive confidence in preclinical models by linking telomeric RNA behavior to chromosomal stability and gene regulation in disease-relevant systems.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of TERRA's role in telomere heterochromatin formation and length homeostasis in cancer cells.
- Operational Value: Provides a reproducible system to test telomere-targeting compounds by monitoring TERRA dynamics as a functional readout.
Screening & Assay Development
- Scientific Value: Generates validated clonal cell lines with MS2-tagged telomeres for consistent TERRA detection in live-cell imaging assays.
- Operational Value: Standardizes TERRA visualization across experiments, reducing variability in RNA localization studies.
Translational & Preclinical Research
- Scientific Value: Supports disease-relevant modeling of TERRA function in human cancer cells, aligning with translational biomarker discovery efforts.
- Operational Value: Facilitates longitudinal tracking of TERRA dynamics to inform risk-adjusted advancement decisions in telomere-modulating therapies.
Pipeline & Workflow Integration
The method integrates into early discovery workflows by establishing clonal models that bridge target validation and assay development for telomere-focused oncology programs.
- Discovery Biology: Supports hypothesis testing of TERRA's involvement in telomere crosstalk with internal chromosomal regions and gene expression regulation.
- Screening: Enables assay readiness through stable, fluorescently detectable TERRA transcripts for compound screening in live-cell formats.
- Analytics: Provides quantitative spatial and temporal readouts of TERRA localization, facilitating comparison across experimental conditions.
- Translational Research: Connects single-telomere TERRA behavior to preclinical continuity by modeling telomere biology in human cancer contexts.
- Enterprise Reuse: Establishes a reusable clonal platform applicable to multiple telomere biology studies and cancer types.
Operational & Enterprise Impact
- Scientific Value: Reduces mechanistic ambiguity in TERRA function by enabling direct visualization from a defined genomic locus.
- Operational Value: Ensures standardization and reproducibility through clonal selection and MS2-GFP labeling.
- Strategic Value: Improves go/no-go decisions in telomere-targeted drug development by providing mechanistic insights into target engagement.
- Portfolio Impact: Supports risk-adjusted prioritization of telomere-modulating agents based on validated TERRA dynamics.
Implementation Considerations
- Requires expertise in genome editing, clonal selection, and live-cell fluorescence microscopy.
- Dependent on retroviral transduction systems and confocal imaging infrastructure.
- Necessitates cross-team standardization for clone validation and TERRA detection protocols.
- Adaptation to other cell lines may require optimization of transfection and selection conditions.
- Practical limitations include the need for single-clone isolation to avoid mixed populations, as noted in the protocol.
Biopharma FAQs
Why does single-telomere TERRA visualization matter for target validation?
Visualizing TERRA from a single telomere enables direct assessment of its role in telomere heterochromatin formation and length homeostasis, which are key mechanisms in cancer cell immortality. This approach reduces mechanistic ambiguity by linking TERRA expression to a defined genomic locus, supporting target validation in telomere-focused oncology programs.
How does clonal isolation with MS2 cassette integration support independent variable isolation in discovery pipelines?
Generating stable clones with MS2 sequences integrated at a single subtelomere isolates the telomere of origin as the independent variable, enabling precise tracking of TERRA transcription and localization. This approach minimizes confounding signals from other telomeres, supporting rigorous hypothesis testing in target validation workflows.
What quantitative dependent variable measurements does live-cell TERRA imaging enable?
Live-cell imaging of MS2-tagged TERRA transcripts enables quantitative measurement of RNA accumulation, dynamics, and subcellular localization over time. These measurements provide functional readouts for assessing TERRA behavior in response to genetic or pharmacological perturbations in cancer cells.
Why are replication requirements important for cross-functional collaboration in TERRA studies?
Replication through clonal selection and PCR/Southern blot validation ensures that TERRA observations are consistent and not due to clonal variability or off-target effects. This rigor supports reliable data sharing across discovery, preclinical, and translational teams studying telomere biology.
What statistical analysis capabilities are needed before implementing TERRA-MS2 cloning in screening workflows?
Implementing this method requires statistical analysis of TERRA signal intensity, localization frequency, and co-localization with telomeric markers across multiple cells and conditions. These capabilities enable objective comparison of TERRA dynamics in screening assays for telomere-modulating compounds.
Chapters in this video
0:04
Title
0:37
Selection of Neomycin Resistant Clones
3:41
Screening of Neomycin Resistant Clones
5:34
Elimination of the Neomycin Resistance Gene from the MS2 Cassette Integrated at Subtelomere 15q
6:06
Visualization of TERRA-MS2 Transcripts in Living Cells
6:49
Results: Cancer Cell Clones with MS2 Sequence Tag Created and Imaged
8:17
Conclusion
