title: Skeletal muscle adaptation in response to voluntary running in Ca2+/calmodulin-dependent protein kinase IV-deficient mice.
abstract: Mammalian skeletal muscles undergo adaptation in response to alteration in functional demands by means of a variety of cellular signaling events. Previous experiments in transgenic mice showed that an active form of Ca2+/calmodulin-dependent protein kinase IV (CaMKIV) is capable of stimulating peroxisome proliferator-activated receptor gamma-coactivator 1alpha (PGC-1alpha) gene expression, promoting fast-to-slow fiber type switching and augmenting mitochondrial biogenesis in skeletal muscle. However, a role for endogenous CaMKIV in skeletal muscle has not been investigated rigorously. We report that genetically modified mice devoid of CaMKIV have normal fiber type composition and mitochondrial enzyme expression in fast-twitch skeletal muscles and responded to long-term (4 wk) voluntary running with increased expression of myosin heavy chain type IIa, myoglobin, PGC-1alpha, and cytochrome c oxidase IV proteins in plantaris muscle in a manner similar to that of wild-type mice. Short-term motor nerve stimulation (2 h at 10 Hz) likewise increased PGC-1alpha mRNA expression in tibialis anterior muscles in both Camk4(-/-) and wild-type mice. In addition, we have confirmed that no detectable CaMKIV protein is expressed in murine skeletal muscle. Thus CaMKIV is not required for the maintenance of slow-twitch muscle phenotype and endurance training-induced mitochondrial biogenesis and IIb-to-IIa fiber type switching in murine skeletal muscle. Other protein kinases sharing substrates with constitutively active CaMKIV may function as endogenous mediators of activity-dependent changes in myofiber phenotype.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, NC 27704, USA.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Akimoto
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Ribar
authors.forename: R Sanders
authors.initials: RS
authors.lastname: Williams
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yan
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D015153:Blotting, Western; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000172:deficiency*; D003576:Electron Transport Complex IV / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D006360:Heat-Shock Proteins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000502:physiology*; D009211:Myoglobin / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000378:metabolism; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010805:Physical Conditioning, Animal / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D006360:Heat-Shock Proteins; D009211:Myoglobin; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012333:RNA, Messenger; D014157:Transcription Factors; D003576:Electron Transport Complex IV; C517683:CAMK4 protein, human; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517685:Camk4 protein, mouse; D018995:Myosin Heavy Chains