title: Calpain inhibition promotes the rescue of F(508)del-CFTR in PBMC from cystic fibrosis patients.
abstract: A basal calpain activity promotes the limited proteolysis of wild type (WT) cystic fibrosis conductance regulator (CFTR), inducing the internalization of the split channel. This process contributes to the regulation in the level of the active CFTR at the plasma membranes. In peripheral blood mononuclear cells (PBMC) from 16 healthy donors, the inhibition of calpain activity induces a 3-fold increase in the amount of active WT CFTR at the plasma membranes. Instead, in PBMC from cystic fibrosis (CF) patients, calpain activity is expressed at aberrant levels causing the massive removal of F(508)del-CFTR from the cell surface. In these patients, the inhibition of such abnormal proteolysis rescues physiological amounts of active mutated CFTR in 90% of the patients (25 over 28). The recovery of functional F(508)del-CFTR at the physiological location, in cells treated with a synthetic calpain inhibitor, indicates that F(508)del-CFTR folding, maturation, and trafficking operate in CF-PBMC at significant rate. Thus, an increase in the basal calpain activity seems primarily involved in the CFTR defect observed in various CF cells. Furthermore, in CF-PBMC the recovery of the scaffolding protein Na(+)/H(+) exchanger regulatory factor 1 (NHERF-1), occurring following inhibition of the aberrant calpain activity, can contribute to rescue CFTR-functional clusters.
authors.affiliation: Department of Experimental Medicine (DIMES) - Biochemistry Section, and Center of Excellence for Biomedical Research (CEBR), University of Genoa, Genoa, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Averna
authors.forename: Marco
authors.initials: M
authors.lastname: Pedrazzi
authors.forename: Laura
authors.initials: L
authors.lastname: Minicucci
authors.forename: Roberta
authors.initials: R
authors.lastname: De Tullio
authors.forename: Federico
authors.initials: F
authors.lastname: Cresta
authors.forename: Franca
authors.initials: F
authors.lastname: Salamino
authors.forename: Sandro
authors.initials: S
authors.lastname: Pontremoli
authors.forename: Edon
authors.initials: E
authors.lastname: Melloni
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002154:Calpain / Q000037:antagonists & inhibitors*; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002648:Child; D003550:Cystic Fibrosis / Q000235:genetics* / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D006023:Glycoproteins / Q000494:pharmacology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D055815:Young Adult
chemical_list: D002352:Carrier Proteins; D006023:Glycoproteins; D009842:Oligopeptides; D010750:Phosphoproteins; D017923:Sodium-Hydrogen Exchangers; C039304:calpain inhibitors; C093376:sodium-hydrogen exchanger regulatory factor; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C047473:N-(3-N-(benzyloxycarbonyl)amino-1-carboxypropyl)leucyl-O-methyltyrosine N-methylamide; D002154:Calpain