title: Differential regulation of the fiber type-specific gene expression of the sarcoplasmic reticulum calcium-ATPase isoforms induced by exercise training.
abstract: The regulatory role of adenosine monophosphate-activated protein kinase (AMPK)-α2 on sarcoplasmic reticulum calcium-ATPase (SERCA) 1a and SERCA2a in different skeletal muscle fiber types has yet to be elucidated. Sedentary (Sed) or exercise-trained (Ex) wild-type (WT) and AMPKα2-kinase dead (KD) transgenic mice, which overexpress a mutated and inactivated AMPKα2 subunit, were utilized to characterize how genotype or exercise training influenced the regulation of SERCA isoforms in gastrocnemius. As expected, both Sed and Ex KD mice had >40% lower AMPK phosphorylation and 30% lower SERCA1a protein than WT mice (P < 0.05). In contrast, SERCA2a protein was not different among KD and WT mice. Exercise increased SERCA1a and SERCA2a protein content among WT and KD mice, compared with their Sed counterparts. Maximal SERCA activity was lower in KD mice, compared with WT. Total phospholamban protein was higher in KD mice than in WT and lower in Ex compared with Sed mice. Exercise training increased phospholamban Ser(16) phosphorylation in WT mice. Laser capture microdissection and quantitative PCR indicated that SERCA1a mRNA expression among type I fibers was not altered by genotype or exercise, but SERCA2a mRNA was increased 30-fold in WT+Ex, compared with WT+Sed. In contrast, the exercise-stimulated increase for SERCA2a mRNA was blunted in KD mice. Exercise upregulated SERCA1a and SERCA2a mRNA among type II fibers, but was not altered by genotype. Collectively, these data suggest that exercise differentially influences SERCA isoform expression in type I and type II fibers. Additionally, AMPKα2 influences the regulation of SERCA2a mRNA in type I skeletal muscle fibers following exercise training.
authors.affiliation: Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Manitoba, Canada; Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada;
authors.forename: Marc P
authors.initials: MP
authors.lastname: Morissette
authors.affiliation: Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Manitoba, Canada; Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada; Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada; and.
authors.forename: Shanel E
authors.initials: SE
authors.lastname: Susser
authors.affiliation: Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Manitoba, Canada; Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada;
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Stammers
authors.affiliation: Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Manitoba, Canada; Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada;
authors.forename: Kimberley A
authors.initials: KA
authors.lastname: O'Hara
authors.affiliation: Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Manitoba, Canada; Spinal Cord Research Institute, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Phillip F
authors.initials: PF
authors.lastname: Gardiner
authors.affiliation: Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Manitoba, Canada; Spinal Cord Research Institute, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Patricia
authors.initials: P
authors.lastname: Sheppard
authors.affiliation: Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Manitoba, Canada; Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada;
authors.forename: Teri L
authors.initials: TL
authors.lastname: Moffatt
authors.affiliation: Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, Manitoba, Canada; Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada; Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada; and tduhamel@sbrc.ca.
authors.forename: Todd A
authors.initials: TA
authors.lastname: Duhamel
mesh_terms: D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism / Q000502:physiology; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018656:Muscle Fibers, Fast-Twitch / Q000201:enzymology; D018657:Muscle Fibers, Slow-Twitch / Q000201:enzymology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000096:biosynthesis* / Q000235:genetics*
chemical_list: D007527:Isoenzymes; D012313:RNA; D017868:Cyclic AMP-Dependent Protein Kinases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases
keywords: AMPK; MHC; SERCA; exercise training; fiber type; myosin heavy chain