Increased Ca2+ storage capacity in the sarcoplasmic reticulum by overexpression of HRC (histidine-rich Ca2+ binding protein).
The histidine-rich Ca(2+) binding protein (HRC) is a high capacity Ca(2+) binding protein in the sarcoplasmic reticulum (SR). Because HRC appears to interact directly with triadin, HRC may play a role in the regulation of Ca(2+) release during excitation-contraction coupling. In this study, we examined the physiological effects of HRC overexpression in rat neonatal cardiomyocytes. Both caffeine-induced and depolarization-induced Ca(2+) release from the SR were increased significantly in the HRC overexpressing cardiomyocytes. Consistently, the Ca(2+) content, normally depleted from the SR in the presence of cyclopiazonic acid (CPA), remained elevated in these cells. In contrast, the density and the ryanodine-binding kinetics of the ryanodine receptor (RyR)/Ca(2+) release channel were slightly reduced or not significantly altered in the HRC overexpressing cardiomyocytes. We suggest that HRC is involved in the regulation of releasable Ca(2+) content into the SR.
Kim
Eunyoung
E
Department of Life Science and National Research Laboratory of Proteolysis, Kwangju Institute of Science and Technology (K-JIST), 1 Oryong-dong, Puk-gu, Kwangju 500-712, South Korea.
Shin
Dong Wook
DW
Hong
Chang Soo
CS
Jeong
Dongtak
D
Kim
Do Han
DH
Park
Woo Jin
WJ
D000818:Animals; D000831:Animals, Newborn; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D066298:In Vitro Techniques; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D051381:Rats; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D002110:Caffeine; D002118:Calcium