title: Evidence for alteration of calpain/calpastatin system in PBMC of cystic fibrosis patients.
abstract: We are here reporting that in peripheral blood mononuclear cells (PBMC) of patients homozygous for F508del-CFTR the calpain-calpastatin system undergoes a profound alteration. In fact, calpain basal activity, almost undetectable in control PBMC, becomes measurable at a significant extent in cells from cystic fibrosis (CF) patients, also due to a 40-60% decrease in both calpastatin protein and inhibitory activity. Constitutive protease activation in CF patients' cells induces a large accumulation of the mutated cystic fibrosis transmembrane conductance regulator (CFTR) in the 100kD+70kD split forms as well as a degradation of proteins associated to the CFTR complex. Specifically, the scaffolding protein Na(+)/H(+) exchanger 3 regulatory factor-1 (NHERF-1) is converted in two distinct fragments showing masses of 35kD and 20kD, being however the latter form the most represented one, thereby indicating that in CF-PBMC the CFTR complex undergoes a large disorganization. In conclusion, our observations are providing new information on the role of calpain in the regulation of plasma membrane ion conductance and provide additional evidence on the transition of this protease activity from a physiological to a pathological function.
authors: Department of Experimental Medicine, University of Genoa, Viale Benedetto XV, Genoa, Italy.
authors: Monica
authors: M
authors: Averna
authors: Roberto
authors: R
authors: Stifanese
authors: Roberta
authors: R
authors: De Tullio
authors: Laura
authors: L
authors: Minicucci
authors: Federico
authors: F
authors: Cresta
authors: Serena
authors: S
authors: Palena
authors: Franca
authors: F
authors: Salamino
authors: Sandro
authors: S
authors: Pontremoli
authors: Edon
authors: E
authors: Melloni
mesh_terms: D000293:Adolescent; D000328:Adult; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016022:Case-Control Studies; D002648:Child; D003550:Cystic Fibrosis / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004789:Enzyme Activation; D057075:Enzyme Assays; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D010750:Phosphoproteins / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D021381:Protein Transport; D059748:Proteolysis; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*; D055815:Young Adult; D000099149:Ezrin
chemical_list: D002135:Calcium-Binding Proteins; D002154:Calpain; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D003598:Cytoskeletal Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; D017923:Sodium-Hydrogen Exchangers; D000099149:Ezrin; C505032:CFTR protein, human; C093376:sodium-hydrogen exchanger regulatory factor; C033668:calpastatin