A new cell-permeable calpain inhibitor.

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Calpains, including mu- and m-calpain, are crucial enzymes involved in numerous physiological and pathological processes.
• Specific cell-permeable inhibitors are essential for studying calpain functions in cellular and animal models.
• A potent 27-mer peptide inhibitor derived from calpastatin exists but has limited cell permeability.

Purpose of the Study:

• To enhance the cell membrane permeability of a potent calpain inhibitor peptide.
• To evaluate the calpain inhibitory activity of the modified peptides.

Main Methods:

• N-terminal extension or disulfide linkage of the 27-mer calpain inhibitor peptide with the 7-mer penetratin fragment.
• Assessment of cell permeability of the modified peptides.
• Evaluation of calpain inhibitory potency of the constructs.

Main Results:

• Both N-terminally extended and disulfide-linked constructs demonstrated improved cell membrane permeability compared to the original peptide.
• The enhanced cell permeability was achieved without compromising the potent calpain inhibitory activity.
• The penetratin fragment facilitated cellular uptake of the inhibitor.

Conclusions:

• Modified calpain inhibitor peptides incorporating penetratin fragments show enhanced cell permeability.
• These novel constructs are promising tools for in vivo and in vitro calpain research.
• Further studies can explore the therapeutic potential of these cell-permeable calpain inhibitors.