title: Cathepsin S Contributes to the Pathogenesis of Muscular Dystrophy in Mice.
abstract: Duchenne muscular dystrophy (DMD) is an X-linked recessive disease caused by mutations in the gene encoding dystrophin. Loss of dystrophin protein compromises the stability of the sarcolemma membrane surrounding each muscle cell fiber, leading to membrane ruptures and leakiness that induces myofiber necrosis, a subsequent inflammatory response, and progressive tissue fibrosis with loss of functional capacity. Cathepsin S (Ctss) is a cysteine protease that is actively secreted in areas of tissue injury and ongoing inflammation, where it participates in extracellular matrix remodeling and healing. Here we show significant induction of Ctss expression and proteolytic activity following acute muscle injury or in muscle from mdx mice, a model of DMD. To examine the functional ramifications associated with greater Ctss expression, the Ctss gene was deleted in the mdx genetic background, resulting in protection from muscular dystrophy pathogenesis that included reduced myofiber turnover and histopathology, reduced fibrosis, and improved running capacity. Mechanistically, deletion of the Ctss gene in the mdx background significantly increased myofiber sarcolemmal membrane stability with greater expression and membrane localization of utrophin, integrins, and β-dystroglycan, which anchor the membrane to the basal lamina and underlying cytoskeletal proteins. Consistent with these results, skeletal muscle-specific transgenic mice overexpressing Ctss showed increased myofiber necrosis, muscle histopathology, and a functional deficit reminiscent of muscular dystrophy. Hence, Ctss induction during muscular dystrophy is a pathologic event that partially underlies disease pathogenesis, and its inhibition might serve as a new therapeutic strategy in DMD.
authors.affiliation: From the Department of Pediatrics and.
authors.forename: Andoria
authors.initials: A
authors.lastname: Tjondrokoesoemo
authors.affiliation: From the Department of Pediatrics and.
authors.forename: Tobias G
authors.initials: TG
authors.lastname: Schips
authors.affiliation: From the Department of Pediatrics and.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Sargent
authors.affiliation: From the Department of Pediatrics and.
authors.forename: Davy
authors.initials: D
authors.lastname: Vanhoutte
authors.affiliation: From the Department of Pediatrics and.
authors.forename: Onur
authors.initials: O
authors.lastname: Kanisicak
authors.affiliation: From the Department of Pediatrics and.
authors.forename: Vikram
authors.initials: V
authors.lastname: Prasad
authors.affiliation: From the Department of Pediatrics and.
authors.forename: Suh-Chin J
authors.initials: SC
authors.lastname: Lin
authors.affiliation: From the Department of Pediatrics and.
authors.forename: Marjorie
authors.initials: M
authors.lastname: Maillet
authors.affiliation: From the Department of Pediatrics and Howard Hughes Medical Institute, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229 jeff.molkentin@cchmc.org.
authors.forename: Jeffery D
authors.initials: JD
authors.lastname: Molkentin
mesh_terms: D000818:Animals; D002403:Cathepsins / Q000096:biosynthesis*; D003599:Cytoskeleton / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D018101:Mice, Inbred mdx; D018345:Mice, Knockout; D018485:Muscle Fibers, Skeletal / Q000201:enzymology* / Q000473:pathology; D009137:Muscular Dystrophy, Animal / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D020388:Muscular Dystrophy, Duchenne / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D009336:Necrosis; D059748:Proteolysis; D012508:Sarcolemma / Q000201:enzymology / Q000235:genetics / Q000473:pathology
chemical_list: D002403:Cathepsins; C028217:cathepsin S
keywords: cathepsin S; dystrophin; muscular dystrophy; protease; skeletal muscle; transgenic mice