Calcium signalling in the regulation of PGC-1alpha, PDK4 and HKII mRNA expression.
The role of calcium signalling and specific intracellular calcium signalling pathways in regulating skeletal muscle tissue peroxisome proliferator-activated receptor gamma co-activator (PGC)-1alpha, hexokinase (HK)II and pyruvate dehydrogenase kinase (PDK)4 mRNA was examined. Cultured primary rat skeletal muscle cells were incubated for 6 h in caffeine or ionomycin. Because PGC-1alpha mRNA clearly showed greater induction with ionomycin, the latter was chosen for the main experiments, whereby cells were incubated for 6 h with either ionomycin alone or in combination with either cyclosporin A or KN-62. The PGC-1alpha mRNA level was increased (p<0.05) approximately six-fold and HKII mRNA content approximately two-fold by ionomycin relative to the corresponding controls, whereas the PDK4 mRNA content remained unaffected. Cyclosporin A abolished (p<0.05) and KN-62 reduced (p<0.1) the ionomycin-induced increase in PGC-1alpha mRNA. Electrical stimulation of in vitro incubated rat EDL muscle increased (p<0.05) PGC-1alpha mRNA by 2.2-fold after 4 h of recovery relative to a resting control, and this increase was absent when muscles were incubated with KN-62 or cyclosporin A. The present data strongly suggest that calcium signalling is involved in regulating the PGC-1alpha and HKII genes, but not PDK4. Both calcineurin and CaMK signalling seem to be involved in the calcium- and contraction-mediated PGC-1alpha up-regulation in skeletal muscle.
Kusuhara
Keiko
K
Copenhagen Muscle Research Centre and Centre of Inflammation and Metabolism, The August Krogh Building, Department of Molecular Biology, University of Copenhagen, Copenhagen Ø, Denmark.
Madsen
Klavs
K
Jensen
Lotte
L
Hellsten
Ylva
Y
Pilegaard
Henriette
H
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D020013:Calcium Signaling; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology; D004558:Electric Stimulation; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics*; D006593:Hexokinase / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015759:Ionomycin / Q000494:pharmacology; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C501429:Ppargc1a protein, rat; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D002110:Caffeine; D015759:Ionomycin; C063302:KN 62; D016572:Cyclosporine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011494:Protein Kinases; C403287:pyruvate dehydrogenase kinase 4; D006593:Hexokinase