title: Expression patterns of initiator and effector caspases in denervated human skeletal muscle.
abstract: There is evidence that apoptotic cell death contributes to the loss of denervated muscle fibers. In 17 patients with neurogenic muscular atrophy, we studied the expression of the apoptosis mediators APAF-1/caspase-9 and degrading caspases-2, -3, and -7 by immunohistochemical and western blot analyses. Muscle with neurogenic atrophy showed distinct upregulation of caspase-9 and -7 and no expression for APAF-1 (apoptosis protease-activating factor-1) and caspase-2 and -3. Expression of caspase-7 was restricted to atrophic fibers, but caspase-9 was also found in normal-sized muscle fibers where its expression was often confined to single fiber segments. These findings indicate that upregulated expression of caspase-9 can initiate the proteolytic cascade involving the downstream executioner caspase-7, which mediates degradation of denervated muscle fibers. However, apoptotic events may be restricted to single muscle-fiber segments, where apoptotic cell degradation contributes to the long-term process of atrophy. Pharmacological inhibition of caspases may be a therapeutic strategy in diminishing muscle atrophy.
authors.affiliation: Neurological (Edinger) Institute, Johann Wolfgang Goethe University Hospital, Deutschordenstrasse 46, D-60528 Frankfurt am Main, Germany. dominique-suzanne.tews@kgu.edu
authors.forename: Dominique S
authors.initials: DS
authors.lastname: Tews
authors.forename: Wera
authors.initials: W
authors.lastname: Behrhof
authors.forename: Susanne
authors.initials: S
authors.lastname: Schindler
mesh_terms: D000328:Adult; D000368:Aged; D020169:Caspases / Q000032:analysis / Q000096:biosynthesis*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009121:Muscle Denervation; D018482:Muscle, Skeletal / Q000737:chemistry / Q000201:enzymology* / Q000294:innervation*; D009133:Muscular Atrophy / Q000201:enzymology; D010523:Peripheral Nervous System Diseases / Q000201:enzymology
chemical_list: D020169:Caspases