Caspase selective reagents for diagnosing apoptotic mechanisms

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Apical caspases initiate apoptosis, but specific detection reagents are limited.
• Existing reagents for distinguishing apical caspases (caspase-8, -9, -10) lack specificity.
• Understanding apical caspase function is crucial for studying apoptotic cell death.

Purpose of the Study:

• To develop selective chemical probes for distinguishing apical caspases.
• To investigate the role of specific apical caspases in extrinsic and intrinsic apoptosis pathways.
• To establish a chemistry-based method for analyzing caspase activity during apoptosis.

Main Methods:

• Selected tetrapeptide sequences for optimal substrate selectivity.
• Converted substrates into activity-based probes (ABPs) with detectable tags.
• Utilized a panel strategy with multiple caspase-selective ABPs to interrogate apoptosis in Jurkat T lymphocytes and MDA-MB-231 breast cancer cells.

Main Results:

• Demonstrated a strong correlation between substrate and ABP kinetics.
• Reported the first highly selective substrate for quantifying caspase-8 activity during apoptosis.
• Developed a panel strategy using multiple ABPs to overcome limitations of single probes, revealing caspase-8's role in TRAIL-induced apoptosis.

Conclusions:

• A panel strategy using multiple caspase-selective activity-based probes (ABPs) offers a robust approach to study apoptosis.
• This method provides a chemistry-based approach to uncover specific caspase participation in apoptotic signaling.
• The developed probes and strategy offer a more faithful way to understand caspase-8 apoptotic signaling compared to nonspecific reagents.