title: Impaired Ca2+ store functions in skeletal and cardiac muscle cells from sarcalumenin-deficient mice.
abstract: Sarcalumenin (SAR), specifically expressed in striated muscle cells, is a Ca2+-binding protein localized in the sarcoplasmic reticulum (SR) of the intracellular Ca2+ store. By generating SAR-deficient mice, we herein examined its physiological role. The mutant mice were apparently normal in growth, health, and reproduction, indicating that SAR is not essential for fundamental muscle functions. SAR-deficient skeletal muscle carrying irregular SR ultrastructures retained normal force generation but showed slow relaxation phases after contractions. A weakened Ca2+ uptake activity was detected in the SR prepared from mutant muscle, indicating that SAR contributes to Ca2+ buffering in the SR lumen and also to the maintenance of Ca2+ pump proteins. Cardiac myocytes from SAR-deficient mice showed slow contraction and relaxation accompanied by impaired Ca2+ transients, and the mutant mice exhibited a number of impairments in cardiac performance as determined in electrocardiography, ventricular catheterization, and echocardiography. The results obtained demonstrate that SAR plays important roles in improving the Ca2+ handling functions of the SR in striated muscle.
authors.affiliation: Medical Chemistry and Molecular Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8575, Japan.
authors.forename: Morikatsu
authors.initials: M
authors.lastname: Yoshida
authors.forename: Susumu
authors.initials: S
authors.lastname: Minamisawa
authors.forename: Miei
authors.initials: M
authors.lastname: Shimura
authors.forename: Shinji
authors.initials: S
authors.lastname: Komazaki
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kume
authors.forename: Miao
authors.initials: M
authors.lastname: Zhang
authors.forename: Kiyoyuki
authors.initials: K
authors.lastname: Matsumura
authors.forename: Miyuki
authors.initials: M
authors.lastname: Nishi
authors.forename: Minori
authors.initials: M
authors.lastname: Saito
authors.forename: Yasutake
authors.initials: Y
authors.lastname: Saeki
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Yanagisawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takeshima
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006321:Heart / Q000503:physiopathology; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008854:Microscopy, Electron; D009119:Muscle Contraction; D018485:Muscle Fibers, Skeletal / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D051381:Rats
chemical_list: D008565:Membrane Proteins; C070323:sarcalumenin; D002118:Calcium