Telethonin protein expression in neuromuscular disorders

Telethonin is a 19-kDa sarcomeric protein, localized to the Z-disc of skeletal and cardiac muscles. Mutations in the telethonin gene cause limb-girdle muscular dystrophy type 2G (LGMD2G). We investigated the sarcomeric integrity of muscle fibers in LGMD2G patients, through double immunofluorescence analysis for telethonin with three sarcomeric proteins: titin, alpha-actinin-2, and myotilin and observed the typical cross striation pattern, suggesting that the Z-line of the sarcomere is apparently preserved, despite the absence of telethonin. Ultrastructural analysis confirmed the integrity of the sarcomeric architecture. the possible interaction of telethonin with other proteins responsible for several forms of neuromuscular disorders was also analyzed. Telethonin was clearly present in the rods in nemaline myopathy (NM) muscle fibers, confirming its localization to the Z-line of the sarcomere. Muscle from patients with absent telethonin showed normal expression for the proteins dystrophin, sarcoglycans, dysferlin, and calpain-3. Additionally, telethonin showed normal localization in muscle biopsies from patients with LGMD2A, LGMD2B, sarcoglycanopathies, and Duchenne muscular dystrophy (DMD). Therefore, the primary deficiency of calpain-3, dysferlin, sarcoglycans, and dystrophin do not seem to alter telethonin expression. (C) 2002 Elsevier Science B.V. All rights reserved.Univ São Paulo, Ctr Study Human Genome, Dept Biol, IBUSP, BR-05508900 São Paulo, BrazilInt Ctr Genet Engn & Biotechnol, Tieste, ItalyUniv Padua, CRIBI Biotechnol Ctr, I-35121 Padua, ItalyHarvard Univ, Childrens Hosp, Sch Med, Div Genet, Boston, MA 02115 USAUniv Helsinki, Helsinki, FinlandUNIFESP, Dept Neurol, São Paulo, BrazilFMUSP, Dept Neurol, São Paulo, BrazilFMUSP, Dept Pathol, São Paulo, BrazilUNIFESP, Dept Neurol, São Paulo, BrazilWeb of Scienc