Selective inhibition of initiator versus executioner caspases using small peptides containing unnatural amino acids

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Caspases are crucial enzymes regulating apoptosis, differentiation, and inflammation.
• Dysregulated caspase activity contributes to diseases including cancer, neurodegenerative disorders, and sepsis.
• Distinguishing specific caspase functions is challenging due to highly similar active sites and overlapping substrates among the 11 human isoforms.

Discussion:

• Existing peptide-based inhibitors often lack isoform specificity, binding promiscuously to multiple caspases.
• The tetrapeptide LETD, recognized for caspase-8, also binds to caspases-3, -6, and -9 with similar affinity.
• This lack of specificity hinders precise investigation of individual caspase roles in biological processes and disease.

Key Insights:

• A new series of compounds demonstrates >100-fold selectivity for inhibiting initiator caspases-8 and -9.
• These compounds effectively discriminate against executioner caspases-3, -6, and -7.
• This enhanced selectivity offers a valuable tool for dissecting specific caspase functions.

Outlook:

• The identified selective inhibitors can advance research into caspase-mediated diseases.
• These compounds may lead to more targeted therapeutic strategies for conditions involving aberrant caspase activity.
• Further studies will explore the therapeutic potential of these selective caspase inhibitors.