Calpain activity in fast, slow, transforming, and regenerating skeletal muscles of rat
| Autor: | Bernd T. Dittrich, Karim R. Sultan, Dirk Pette |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Male
Gene isoform medicine.medical_specialty Physiology chemistry.chemical_element Stimulation Hindlimb Biology Calcium Myofibrils Microsomes Internal medicine medicine Animals Protein Isoforms Regeneration Rats Wistar Muscle Skeletal Calpastatin Calpain musculoskeletal neural and ocular physiology Calcium-Binding Proteins Skeletal muscle Cell Biology musculoskeletal system Electric Stimulation Rats Muscle Fibers Slow-Twitch Endocrinology medicine.anatomical_structure chemistry Muscle Fibers Fast-Twitch biology.protein Myofibril |
| Zdroj: | American Journal of Physiology-Cell Physiology. 279:C639-C647 |
| ISSN: | 1522-1563 0363-6143 |
| DOI: | 10.1152/ajpcell.2000.279.3.c639 |
| Popis: | Fiber-type transitions in adult skeletal muscle induced by chronic low-frequency stimulation (CLFS) encompass coordinated exchanges of myofibrillar protein isoforms. CLFS-induced elevations in cytosolic Ca2+could activate proteases, especially calpains, the major Ca2+-regulated cytosolic proteases. Calpain activity determined by a fluorogenic substrate in the presence of unaltered endogenous calpastatin activities increased twofold in low-frequency-stimulated extensor digitorum longus (EDL) muscle, reaching a level intermediate between normal fast- and slow-twitch muscles. μ- and m-calpains were delineated by a calpain-specific zymographical assay that assessed total activities independent of calpastatin and distinguished between native and processed calpains. Contrary to normal EDL, structure-bound, namely myofibrillar and microsomal calpains, were abundant in soleus muscle. However, the fast-to-slow conversion of EDL was accompanied by an early translocation of cytosolic μ-calpain, suggesting that myofibrillar and microsomal μ-calpain was responsible for the twofold increase in activity and thus involved in controlled proteolysis during fiber transformation. This is in contrast to muscle regeneration where m-calpain translocation predominated. Taken together, we suggest that translocation is an important step in the control of calpain activity in skeletal muscle in vivo. |
| Databáze: | OpenAIRE |
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