Quintuple labeling in the electron microscope with genetically encoded enhanced horseradish peroxidase

Area of Science:

• Cell Biology
• Microscopy
• Molecular Biology

Background:

• Genetic multilabeling is crucial for modern cell biology.
• Fluorescence microscopy has numerous genetic labeling tools (e.g., green fluorescent protein variants).
• Electron microscopy (EM) currently lacks true genetic encoded multilabeling capabilities.

Purpose of the Study:

• To develop a novel strategy for genetic multilabeling in electron microscopy.
• To create a reliable and highly sensitive label for EM applications.
• To enable multiplexed organelle labeling for advanced cell biology studies.

Main Methods:

• Engineered an enhanced horseradish peroxidase (eHRP) enzyme for high sensitivity and reliability.
• Constructed fusion proteins to target eHRP to specific organelles: endoplasmic reticulum, synaptic vesicles, and plasma membrane.
• Utilized combinatorial expression of organelle-specific constructs for multiplexed labeling.

Main Results:

• Achieved reliable triple labeling of endoplasmic reticulum, synaptic vesicles, and plasma membrane using eHRP.
• Demonstrated that combinatorial expression of three constructs increased distinguishable labels to seven.
• Established a novel multilabeling strategy for electron microscopy.

Conclusions:

• The developed combinatorial organelle-specific labeling strategy effectively enables genetic multilabeling in EM.
• This approach significantly expands the toolkit for cell biology research, addressing a critical gap.
• The technique offers broad applicability for visualizing complex cellular structures and processes.