title: Calcineurin is a potent regulator for skeletal muscle regeneration by association with NFATc1 and GATA-2.
abstract: The molecular signaling pathways involved in regeneration after muscle damage have not been identified. In the present study, we tested the hypothesis that calcineurin, a calcium-regulated phosphatase recently implicated in the signaling of fiber-type conversion and muscle hypertrophy, is required to induce skeletal muscle remodeling. The amount of calcineurin and dephosphorylated nuclear factor of activated T cells c1 (NFATc1) proteins was markedly increased in the regenerating muscle of rats. The amount of calcineurin co-precipitating with NFATc1 and GATA-2, and NFATc1 co-precipitating with GATA-2 gradually increased in the tibialis anterior muscle after bupivacaine injection. Calcineurin protein was present in the proliferating satellite cells labeled with BrdU in the damaged muscle after 4 days. In contrast, calcineurin was not detected in the quiescent nonactivating satellite cells expressing Myf-5. At 4 days post injection, many macrophages detected in the damaged and regenerating area did not possess calcineurin protein. Calcineurin protein was abundant in many myoblasts and myotubes that expressed MyoD and myogenin at 4 and 6 days post injection. In the intact muscle, no immunoreactivity of calcineurin or BrdU was detected in the cell membrane, cytosol or the extracellular connective tissue. In mice, intraperitoneal injection of cyclosporin A, a potent inhibitor of calcineurin, induced extensive inflammation, marked fiber atrophy, the appearance of immature myotubes, and calcification in the regenerating muscle compared with phosphate-buffered saline-administered mice. Thus, calcineurin may have an important role in muscle regeneration in association with NFATc1 and GATA-2.
authors.affiliation: Department of Legal Medicine, Kyoto Prefectural University of Medicine, 456 Kajii-cho, Kawaramachi-hirokoji, Kamigyo-ku, Japan. ksakuma@basic.kpu-m.ac.jp
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Sakuma
authors.forename: Junji
authors.initials: J
authors.lastname: Nishikawa
authors.forename: Ryuta
authors.initials: R
authors.lastname: Nakao
authors.forename: Kimi
authors.initials: K
authors.lastname: Watanabe
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Totsuka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakano
authors.forename: Mamoru
authors.initials: M
authors.lastname: Sano
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yasuhara
mesh_terms: D000779:Anesthetics, Local / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002045:Bupivacaine / Q000008:administration & dosage / Q000494:pharmacology; D019703:Calcineurin / Q000187:drug effects / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D050989:GATA2 Transcription Factor; D007150:Immunohistochemistry; D007273:Injections, Intramuscular; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D017570:MyoD Protein / Q000187:drug effects / Q000378:metabolism; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011233:Precipitin Tests; D051381:Rats; D012038:Regeneration / Q000187:drug effects / Q000502:physiology*; D032496:Satellite Cells, Skeletal Muscle / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D014157:Transcription Factors / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000779:Anesthetics, Local; D004268:DNA-Binding Proteins; D050989:GATA2 Transcription Factor; C494712:Gata2 protein, mouse; C494713:Gata2 protein, rat; D017570:MyoD Protein; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D009687:Nuclear Proteins; D014157:Transcription Factors; D019703:Calcineurin; D002045:Bupivacaine