Thyroid hormone is required for the phenotype transitions induced by the pharmacological inhibition of calcineurin in adult soleus muscle of rats.
The present experiment was designed to examine the effects of hypothyroidism and calcineurin inhibition induced by cyclosporin A (CsA) administration on both contractile and metabolic soleus muscle phenotypes, with a novel approach to the signaling pathway controlling mitochondrial biogenesis. Twenty-eight rats were randomly assigned to four groups, normothyroid, hypothyroid, and orally treated with either CsA (25 mg/kg, N-CsA and H-CsA) or vehicle (N-Vh and H-Vh), for 3 wk. Muscle phenotype was estimated by the MHC profile and activities of oxidative and glycolytic enzymes. We measured mRNA levels of the peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1 alpha), the major regulator of mitochondrial content. We also studied the expression of the catalytic A-subunit of calcineurin (CnA) both at protein and transcript levels and mRNA levels of modulatory calcineurin inhibitor proteins (MCIP)-1 and -2, which are differentially regulated by calcineurin activity and thyroid hormone, respectively. CsA-administration induced a slow-to-fast MHC transition limited to the type IIA isoform, which is associated with increased oxidative capacities. Hypothyroidism strongly decreased both the expression of fast MHC isoforms and oxidative capacities. Effects of CsA administration on muscle phenotype were blocked in conditions of thyroid hormone deficiency. Changes in the oxidative profile were strongly related to PGC-1 alpha changes and associated with phosphorylation of p38 MAPK. Calcineurin and MCIPs mRNA levels were decreased by both hypothyroidism and CsA without additive effects. Taken together, these results suggest that adult muscle phenotype is primarily under the control of thyroid state. Physiological levels of thyroid hormone are required for the effects of calcineurin inhibition on slow oxidative muscle phenotype.
Koulmann
Nathalie
N
Département des facteurs humains, Centre de recherches du service de santé des armées, BP 87-38702 La Tronche Cedex, France. nkoulmann@crssa.net
Bahi
Lahoucine
L
Ribera
Florence
F
Sanchez
Hervé
H
Serrurier
Bernard
B
Chapot
Rachel
R
Peinnequin
André
A
Ventura-Clapier
Renée
R
Bigard
Xavier
X
D000367:Age Factors; D000818:Animals; D019703:Calcineurin / Q000235:genetics / Q000378:metabolism*; D065095:Calcineurin Inhibitors; D020134:Catalytic Domain; D016572:Cyclosporine / Q000097:blood / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000097:blood / Q000494:pharmacology; D007037:Hypothyroidism / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010641:Phenotype; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013963:Thyroid Hormones / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D065095:Calcineurin Inhibitors; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D009124:Muscle Proteins; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C501429:Ppargc1a protein, rat; C548050:RCAN1 protein, rat; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D013963:Thyroid Hormones; D014157:Transcription Factors; D016572:Cyclosporine; D048051:p38 Mitogen-Activated Protein Kinases; D019703:Calcineurin; D018995:Myosin Heavy Chains