title: Inhibition of calpain-mediated cell death by a novel peptide inhibitor.
abstract: 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.
authors.affiliation: Department of Biology, Florida A and M University, Tallahassee, FL, USA.
authors.forename: Adrian T
authors.initials: AT
authors.lastname: McCollum
authors.forename: Faegheh
authors.initials: F
authors.lastname: Jafarifar
authors.forename: Bert C
authors.initials: BC
authors.lastname: Lynn
authors.forename: Remigius U
authors.initials: RU
authors.lastname: Agu
authors.forename: Audra L
authors.initials: AL
authors.lastname: Stinchcomb
authors.forename: Susan
authors.initials: S
authors.lastname: Wang
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Chen
authors.forename: Rodney P
authors.initials: RP
authors.lastname: Guttmann
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002154:Calpain / Q000737:chemistry / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004622:Embryo, Mammalian; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005452:Fluoresceins / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D009433:Neural Inhibition / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects*; D010455:Peptides / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013049:Spectrin / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D005452:Fluoresceins; D007476:Ionophores; D010455:Peptides; D013049:Spectrin; C085925:calcein AM; D015759:Ionomycin; D000255:Adenosine Triphosphate; D002154:Calpain