title: Nonshivering thermogenesis protects against defective calcium handling in muscle.
abstract: When acutely exposed to a cold environment, mammals shiver to generate heat. During prolonged cold exposure, shivering is replaced by adaptive adrenergic nonshivering thermogenesis with increased heat production in brown adipose tissue due to activation of uncoupling protein-1 (UCP1). This cold acclimation is associated with chronically increased sympathetic stimulation of skeletal muscle, which may increase the sarcoplasmic reticulum (SR) Ca(2+) leak via destabilized ryanodine receptor 1 (RyR1) channel complexes. Here, we use genetically engineered UCP1-deficient (UCP1-KO) mice that rely completely on shivering in the cold. We examine soleus muscle, which participates in shivering, and flexor digitorum brevis (FDB) muscle, a distal and superficial muscle that does not shiver. Soleus muscles of cold-acclimated UCP1-KO mice exhibited severe RyR1 PKA hyperphosphorylation and calstabin1 depletion, as well as markedly decreased SR Ca(2+) release and force during contractions. In stark contrast, the RyR1 channel complexes were little affected, and Ca(2+) and force were not decreased in FDB muscles of cold-acclimated UCP1-KO mice. These results indicate that activation of UCP1-mediated heat production in brown adipose tissue during cold exposure reduces the necessity for shivering and thus prevents the development of severe dysfunction in shivering muscles.
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Aydin
authors.forename: Irina G
authors.initials: IG
authors.lastname: Shabalina
authors.forename: Nicolas
authors.initials: N
authors.lastname: Place
authors.forename: Steven
authors.initials: S
authors.lastname: Reiken
authors.forename: Shi-Jin
authors.initials: SJ
authors.lastname: Zhang
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Bellinger
authors.forename: Jan
authors.initials: J
authors.lastname: Nedergaard
authors.forename: Barbara
authors.initials: B
authors.lastname: Cannon
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Marks
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Bruton
authors.forename: Håkan
authors.initials: H
authors.lastname: Westerblad
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D002001:Adipose Tissue, Brown / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003080:Cold Temperature; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D010766:Phosphorylation; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism; D012768:Shivering / Q000502:physiology; D022722:Thermogenesis / Q000502:physiology*; D000071256:Uncoupling Protein 1
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; C000604372:Ucp1 protein, mouse; D000071256:Uncoupling Protein 1; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium