Lighting Up the Pathways to Caspase Activation Using Bimolecular Fluorescence Complementation

Area of Science:

• Molecular biology
• Cellular biology
• Immunology

Background:

• Initiator caspases are crucial proteases in apoptosis and innate immunity.
• These caspases (e.g., caspase-1, -2, -8, -9) activate via dimerization on specific protein complexes.
• Understanding early activation steps is key to studying these vital cellular processes.

Purpose of the Study:

• To introduce and validate Caspase Bimolecular Fluorescence Complementation (BiFC) as a method.
• To visualize and quantify the recruitment of initiator caspases to their activation platforms.
• To provide a sensitive readout of early caspase activation events.

Main Methods:

• Utilizing split fluorescent proteins fused to initiator caspases.
• Employing microscopy-based approaches to detect fluorescence complementation.
• Analyzing fluorescence to assess caspase recruitment and complex formation.

Main Results:

• Caspase BiFC successfully visualizes initiator caspase recruitment and induced proximity.
• The technique provides quantitative data on activation efficiency at the population level.
• Microscopy allows for per-cell analysis of kinetics, complex size, and number.

Conclusions:

• Caspase BiFC is a powerful imaging tool for studying initiator caspase activation.
• This method offers detailed insights into the early molecular events of apoptosis and immunity.
• BiFC enables quantitative analysis of caspase activation dynamics in living cells.