Calcineurin regulates slow myosin, but not fast myosin or metabolic enzymes, during fast‐to‐slow transformation in rabbit skeletal muscle cell culture

• DOI: 10.1111/j.1469-7793.2001.0215b.x
• Publication Date: 2004-08-05T10:17:37Z
• Authors: Joachim D. Meißner; Gerolf Gros; Renate J. Scheibe; Michael Scholz; Hans‐Peter Kubis
• Keywords: Glyceraldehyde 3-phosphate dehydrogenase

The addition of cyclosporin A (500 ng ml(-1)) - an inhibitor the Ca2+-calmodulin-regulated serine/threonine phosphatase calcineurin to primary cultures rabbit skeletal muscle cells had no influence on expression fast myosin heavy chain (MHC) isoforms MHCIIa and MHCIId at level protein mRNA, but reduced slow MHCI mRNA. In addition, citrate synthase (CS) glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA was found. enzyme activity CS also not affected. When Ca2+ ionophore A23187 (4 x 10(-7) M) added medium, a partial fast-to-slow transformation occurred. increased, decreased. Cotreatment with able prevent upregulation as well protein, did reverse decrease in expression. influenced by A. Cyclosporin under treatment failed reduce increased CS. GAPDH altered cotreatment myotubes culture were electrostimulated 1 Hz for 15 min periods followed pauses 30 min, induced. Again, prevented without affecting nuclear translocation calcineurin-regulated transcription factor activated thymocytes (NFATc1) during ionophore, prevention presence A, demonstrated immunocytochemically culture. effects demonstrate involvement calcineurin-dependent signalling pathways controlling MHCI, MHCIIa, MHCIId, GAPDH, ionophore- electrostimulation-induced transformations. data indicate differential regulation MHCII metabolism. Calcineurin alone is sufficient mediate complete transformation.