Peroxisome Staining in Mammalian Cells Using Peroxisome-Specific Probes
December 19th, 2025
PeroxiSPY probes are used to detect peroxisomes in mammalian cells. Here we demonstrate how to use the probes to stain peroxisomes in live and fixed cells.
So our research focuses on understanding peroxisomes, which are essential organelles for lipid metabolism and cellular oxidative balance. We aim to uncover how their structure and function are regulated and how these processes change in disease. To achieve this, we develop fluorescent probes that allow us and the wider scientific community to visualize peroxisomes in a range of animal cells.
Here, we develop staining protocols that work in both live and fixed cells, providing powerful tools for studying paroxetine biology in health and pathology. One of the main experimental challenges is achieving non-invasive labeling of peroxisomes in animal cells. Whilst antibody staining helps overcome this, there is a lack of commercially available antibodies for paroxysmal proteins.
Another challenge is visualizing peroxisomes non-invasively in real time, which requires adaptable protocols. And finally, conventional staining doesn't provide a functional readout. While peroxidase-based staining can vary depending on paroxysmal function, which is both a challenge and an opportunity, because it allows us to distinguish paroxysmal functional states within the cell.
Begin with mammalian cells seeded the day before in a plate with cover slips that are now at a 30 to 70%confluency. Dilute the peroxisome probe with fresh media in a light-sensitive, micro-centrifuged tube to achieve a four micromolar final concentration. Select the desired well to stain and label the outside using a marker pen.
Aspirate 0.5 milliliters of media from the selected well and replace it with the prepared probe media drop by drop along the wall of the well. After dispensing, incubate the cells at 37 degrees Celsius for 10 to 15 minutes. From this point forward, shield the cells from light using aluminum foil.
Post-incubation, carefully remove the stained media and wash the cells twice with PBS. Then, place the plate under a chemical hood, add 4%paraformaldehyde in PBS to the cells, and incubate at room temperature for 20 minutes. After fixation, remove the paraformaldehyde into a designated waste container and wash the cells once with PBS.
Next, add 0.5%Triton X in PBS to permeabilize the cells and incubate for 2.5 minutes. After incubation, remove the Triton X and wash the cells twice with PBS for 10 minutes each. To block the cells, incubate them with 5%bovine serum albumin in PBS overnight at four degrees Celsius.
Perform the immunofluorescent staining procedure following standard protocol. Finally, perform microscopy to acquire images of both fixed and live cells. Live cell staining with Peroxi_SPY probes resulted in ATP-binding cassette subfamily D-dependent import into peroxisomes, producing a high peroxisome to cytoplasm fluorescence ratio in metabolically-active cells.
In wild type HEK-293T cells expressing GFP-SKL, Peroxi_SPY555 staining showed distinct colocalization with peroxisomes, whereas in PEX19 knockout cells that lack peroxisomes, the staining was absent. In human fibroblasts, Peroxi_SPY staining colocalized with the paroxysmal marker GFP-SKL, confirming peroxisome targeting. Peroxisome density quantification revealed significant variation among different cell types.
Optimized staining conditions in COS-7 cells using 250 nanomolar Peroxi_SPY for 20 minutes significantly increased the peroxisome to cytoplasm fluorescence ratio compared to the original one micromolar for 10 minutes protocol. Extended incubation of HEK-293T cells with Peroxi_SPY for 24 hours led to an improved peroxisome to cytoplasm fluorescence intensity ratio compared to 15 minutes, despite reduced peroxisome staining. A fixation protocol enabled successful antibody costaining demonstrated by preserved Peroxi_SPY labeling and Anti-PEX14 immunostaining in HuH-7 and HEK-293T cells.
Quantification showed that fixation and permeabilization procedures affected peroxisome-fluorescence intensity when compared to live cell staining. We have developed the Peroxi_SPY dye that can be used to visualize peroxisomes in both live and fixed animal cells. Our fluorescent probe can offer a simple and quick method to study peroxisome dynamics, heterogeneity, and dysfunction in ways that were previously limited.
This protocol will enable imaging-based peroxisome research in diverse cell types, including patient-derived cells with paroxysmal disorders.
Overview
This study focuses on the development and application of PeroxiSPY probes for the detection of peroxisomes in mammalian cells. The protocols established allow for effective staining of peroxisomes in both live and fixed cells, facilitating research into peroxisome biology.
Key Study Components
Area of Science
- Cell Biology
- Fluorescent Imaging
- Organelle Dynamics
Background
- Peroxisomes are crucial for lipid metabolism and oxidative balance in cells.
- Understanding their structure and function is vital for insights into various diseases.
- Existing challenges include non-invasive labeling and visualization of peroxisomes.
- Commercially available antibodies for peroxisomal proteins are limited.
Purpose of Study
- To develop fluorescent probes for visualizing peroxisomes in animal cells.
- To establish staining protocols for both live and fixed cells.
- To enhance understanding of peroxisome dynamics and dysfunction.
Methods Used
- Preparation of PeroxiSPY probes and staining protocols.
- Incubation of cells with probes and fixation with paraformaldehyde.
- Immunofluorescent staining and microscopy for imaging.
- Quantification of peroxisome density and fluorescence intensity.
Main Results
- PeroxiSPY probes effectively stain peroxisomes in various cell types.
- Optimized conditions significantly improved fluorescence ratios.
- Distinct colocalization of PeroxiSPY with peroxisomal markers was observed.
- Fixation and permeabilization protocols influenced staining outcomes.
Conclusions
- PeroxiSPY probes provide a simple method for studying peroxisome dynamics.
- The developed protocols enable imaging-based research in diverse cell types.
- This work enhances the understanding of peroxisomal function in health and disease.
Frequently Asked Questions
Executive Industry Relevance
Quantitative visualization of peroxisomes in live mammalian cells addresses a critical gap in early discovery and disease modeling, enabling direct assessment of organelle function and dysfunction. The PeroxiSPY probe platform supports mechanistic de-risking and target validation for peroxisome-related pathways, with implications for rare disease research and translational biomarker development. This capability enhances predictive confidence at key inflection points in the discovery pipeline.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables direct interrogation of peroxisome biology and pathway function in live cells.
- Supports mechanistic de-risking by distinguishing functional states of peroxisomes in disease-relevant models.
- Facilitates target validation for peroxisome-associated genetic disorders and metabolic pathways.
Screening & Assay Development
- Provides a standardized, quantitative readout for peroxisome abundance and dynamics in high-content imaging workflows.
- Improves assay reproducibility and scalability by enabling non-toxic, live-cell staining across diverse cell types.
- Supports screening readiness for compound evaluation targeting peroxisomal function or rescue.
Translational & Preclinical Research
- Enables assessment of peroxisome dysfunction in patient-derived cells, supporting translational biomarker alignment.
- Facilitates continuity from discovery through preclinical validation by quantifying organelle-level phenotypes.
- Provides predictive value for disease modeling and therapeutic hypothesis testing in rare genetic disorders.
Pipeline & Workflow Integration
The PeroxiSPY staining protocol integrates into the discovery continuum from early mechanistic studies to preclinical disease modeling, supporting both hypothesis-driven research and quantitative screening.
- Discovery Biology: Supports hypothesis testing and pathway clarification by enabling real-time visualization of peroxisome dynamics.
- Screening: Delivers reproducible, quantitative fluorescence outputs for comparative analysis across conditions and cell types.
- Analytics: Provides robust measurements of peroxisome density and function, facilitating statistical comparison and decision-making.
- Translational Research: Aligns with biomarker development by enabling detection of pathological phenotypes in patient-derived cells.
- Enterprise Reuse: Offers a broadly applicable, reusable platform for peroxisome research across multiple disease areas and cell models.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in peroxisome-targeted research.
- Operational Value: Standardizes live-cell and fixed-cell imaging workflows for cross-lab reproducibility.
- Strategic Value: Improves go/no-go decisions and capital efficiency by enabling early detection of functional phenotypes.
- Portfolio Impact: Supports risk-adjusted prioritization of peroxisome-related targets and disease models.
Implementation Considerations
- Requires expertise in live-cell imaging and quantitative fluorescence analysis.
- Needs access to fluorescence microscopy and compatible analytical infrastructure.
- Demands cross-team standardization of staining and imaging protocols for reproducibility.
- Adaptable to a range of mammalian cell types, including patient-derived models.
- Fluorescence intensity may be affected by fixation and permeabilization steps, requiring protocol optimization.
