title: Sarcalumenin plays a critical role in age-related cardiac dysfunction due to decreases in SERCA2a expression and activity.
abstract: Impaired Ca(2+) reuptake into the sarcoplasmic reticulum (SR) underlies a primary pathogenesis of heart failure in the aging heart. Sarcalumenin (SAR), a Ca(2+)-binding glycoprotein located in the longitudinal SR, regulates Ca(2+) reuptake by interacting with SR Ca(2+)-ATPase (SERCA). Here we found that the expression levels of both SAR and SERCA2 proteins were significantly downregulated in senescent wild-type mice (18-month old) and that downregulation of SAR protein preceded downregulation of SERCA2 protein. The downregulation of SERCA2 protein was greater in senescent SARKO mice than in age-matched senescent wild-type mice, which was at least in part due to progressive degradation of SERCA2 protein in SARKO mice. Senescent SARKO mice exhibited typical findings of heart failure such as increased sympathetic activity, impaired exercise tolerance, and upregulation of biomarkers of cardiac stress. Consequently, cardiac function was progressively decreased in senescent SARKO. We also found that the expression levels of endoplasmic reticulum (ER) stress-related genes such as x-box binding protein 1 (XBP1) were significantly increased in senescent SARKO mice, indicating that senescent SARKO mice exhibited ER stress. Thus we uncovered the important role of SAR in maintaining Ca(2+) transport activity of SERCA2a and cardiac function in the senescent population.
authors: Department of Life Science and Medical Bioscience, Waseda University, Wakamatsu-cho, Shinjuku-ku, Tokyo, Japan.
authors: Qibin
authors: Q
authors: Jiao
authors: Hiroshi
authors: H
authors: Takeshima
authors: Yoshihiro
authors: Y
authors: Ishikawa
authors: Susumu
authors: S
authors: Minamisawa
mesh_terms: D000375:Aging / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D015536:Down-Regulation / Q000235:genetics; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D006321:Heart / Q000187:drug effects / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009206:Myocardium / Q000201:enzymology / Q000473:pathology; D020097:Natriuretic Peptide, Brain / Q000235:genetics / Q000378:metabolism; D010805:Physical Conditioning, Animal; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism*; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000378:metabolism
chemical_list: D015415:Biomarkers; D008565:Membrane Proteins; D012333:RNA, Messenger; D020097:Natriuretic Peptide, Brain; C070323:sarcalumenin; D009320:Atrial Natriuretic Factor; D003513:Cycloheximide; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium