Inhibition of calpain-mediated cell death by a novel peptide inhibitor

• Published in: Experimental neurology 2006-12, Vol.202 (2), p.506-513
• Main Authors: McCollum, Adrian T., Jafarifar, Faegheh, Lynn, Bert C., Agu, Remigius U., Stinchcomb, Audra L., Wang, Susan, Chen, Qinghua, Guttmann, Rodney P.
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Analysis of Variance; Animals; Biological and medical sciences; Blotting, Western - methods; Calcium; Calpain; Calpain - chemistry; Calpain - pharmacology; Cell death; Cell Death - drug effects; Cells, Cultured; Cerebral Cortex - cytology; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Development. Senescence. Regeneration. Transplantation; Dose-Response Relationship, Drug; Drug Interactions; Embryo, Mammalian; Enzyme Activation; Enzyme Inhibitors - pharmacology; Fluoresceins - metabolism; Fundamental and applied biological sciences. Psychology; Ionomycin - pharmacology; Ionophores - metabolism; Isolated neuron and nerve. Neuroglia; Mass Spectrometry - methods; Medical sciences; Neural Inhibition - drug effects; Neurology; Neurons - drug effects; Neuropharmacology; Neuroprotective agent; Peptide; Peptides - antagonists & inhibitors; Peptides - pharmacology; Phage-display; Pharmacology. Drug treatments; Rats; Rats, Sprague-Dawley; Spectrin - metabolism; Vertebrates: nervous system and sense organs
• ISSN: 0014-4886; 1090-2430
• DOI: 10.1016/j.expneurol.2006.07.016

Calpains are calcium- and thiol-dependent proteases whose overactivation and degradation of various substrates have been implicated in a number of diseases and conditions such as cardiovascular dysfunction and ischemic stroke. With increasing evidence for calpain's role in cellular damage, the development of calpain inhibitors continues to be an important objective. Previously, we identified a highly specific calcium-dependent, calpain interacting peptide L-S-E-A-L, that showed homology to domains A and C of the only known endogenous inhibitor of calpains, calpastatin. This suggested that LSEAL had a calpain inhibitory function and synthetic LSEAL inhibited calpain I and II proteolysis of two calpain substrates, tau and alpha-synuclein . In the present study, we demonstrate that synthetic LSEAL is membrane permeable and is a potent inhibitor in two established models of calpain-mediated cell death using primary rat cortical neurons and SH-SY5Y neuroblastoma cells. In addition, we show that LSEAL inhibits calpain activity towards protein substrates as detected by an antibody to a calpain-specific breakdown product of spectrin. Taken together, these results suggest that LSEAL may represent a novel calpastatin mimetic with the potential for benefit in conditions of increased calpain activity such as stroke, traumatic brain injury or heart attack.