Advances in Organelle Visualization

Researchers recently developed a groundbreaking tool called RELAY lysosomal labeling to overcome the limitations of traditional cellular imaging. Specifically, visualizing lysosomes in living cells remains essential for understanding various physiological functions. However, most existing probes often disrupt the delicate chemistry of the lysosomal lumen or suffer from rapid signal leakage. These drawbacks typically prevent scientists from conducting long-term observations of organelle behavior. Consequently, the development of RELAY (Relocation of Endocytic Leaflet tAg to modifY organelles) represents a significant leap forward in biotechnology.

How the RELAY Strategy Works

The RELAY method employs a unique topology-preserving strategy. First, researchers use liposome-cell membrane fusion to anchor fluorescent DNA probes onto the inner leaflet of the plasma membrane. These probes utilize phosphorothioate (PS) backbones, which naturally resist degradation by nucleases. Subsequently, normal endocytic trafficking moves these probes from the cell surface to the lysosomes. Notably, the probes remain on the cytosol-facing outer leaflet rather than entering the acidic interior. Therefore, the probes avoid the harsh degradation typical of the lysosomal lumen, ensuring high stability.

Discoveries Using RELAY Lysosomal Labeling

This stable, asymmetric labeling supports high-fidelity imaging for up to one week. During experiments, the team utilized this extended timeframe to monitor lysosomal dynamics during cellular senescence. Interestingly, they discovered a random and unidirectional intercellular transfer of lysosomes. This process occurs via tunneling nanotubes, which act as thin bridges for cell-cell communication. Furthermore, the ability to track these organelles for seven days allows researchers to observe complex biological functions that were previously invisible. Indeed, this high-fidelity approach facilitates a deeper exploration of how cells manage waste and communicate under stress.

Frequently Asked Questions

Why is long-term lysosomal imaging difficult with traditional probes?

Traditional probes usually target the lysosomal interior, where high acidity and digestive enzymes quickly degrade the fluorescent signal or disrupt the organelle's natural chemistry.

How does the RELAY method protect the fluorescent DNA probes?

The RELAY method anchors the probes to the outer surface of the lysosome. Because the probes face the cytosol rather than the acidic lumen, they remain protected from internal degradation.

What did the study reveal about cell-to-cell communication?

The study found that cells can transfer lysosomes to one another through tunneling nanotubes. This transfer is random and unidirectional, suggesting a new pathway for intercellular organelle exchange.

Disclaimer: This content is for informational and educational purposes only. It does not constitute medical advice or a substitute for professional healthcare. Refer to the latest local and national guidelines for clinical practice.

References

Yan A et al. Relocation of Endocytic Leaflet DNA Probes for Asymmetric and Week-Long Lysosomal Labeling. J Am Chem Soc. 2026 Feb 10. doi: 10.1021/jacs.5c21974. PMID: 41664987.

Ruan Z et al. DNA Nanomachines for Mapping Organelle Dynamics. Nature Biotechnology. 2024;42(3):450-458.

Zhang X et al. Tunneling Nanotubes: Highways for Intercellular Organelle Transport. Frontiers in Cell and Developmental Biology. 2023;11:112045.