title: RyR2 modulates a Ca2+-activated K+ current in mouse cardiac myocytes.
abstract: In cardiomyocytes, Ca2+ entry through voltage-dependent Ca2+ channels (VDCCs) binds to and activates RyR2 channels, resulting in subsequent Ca2+ release from the sarcoplasmic reticulum (SR) and cardiac contraction. Previous research has documented the molecular coupling of small-conductance Ca2+-activated K+ channels (SK channels) to VDCCs in mouse cardiac muscle. Little is known regarding the role of RyRs-sensitive Ca2+ release in the SK channels in cardiac muscle. In this study, using whole-cell patch clamp techniques, we observed that a Ca2+-activated K+ current (IK,Ca) recorded from isolated adult C57B/L mouse atrial myocytes was significantly decreased by ryanodine, an inhibitor of ryanodine receptor type 2 (RyR2), or by the co-application of ryanodine and thapsigargin, an inhibitor of the sarcoplasmic reticulum calcium ATPase (SERCA) (p<0.05, p<0.01, respectively). The activation of RyR2 by caffeine increased the IK,Ca in the cardiac cells (p<0.05, p<0.01, respectively). We further analyzed the effect of RyR2 knockdown on IK,Ca and Ca2+ in isolated adult mouse cardiomyocytes using a whole-cell patch clamp technique and confocal imaging. RyR2 knockdown in mouse atrial cells transduced with lentivirus-mediated small hairpin interference RNA (shRNA) exhibited a significant decrease in IK,Ca (p<0.05) and [Ca2+]i fluorescence intensity (p<0.01). An immunoprecipitated complex of SK2 and RyR2 was identified in native cardiac tissue by co-immunoprecipitation assays. Our findings indicate that RyR2-mediated Ca2+ release is responsible for the activation and modulation of SK channels in cardiac myocytes.
authors.affiliation: Department of Physiology, School of Medicine, Zhengzhou University, Zhengzhou, Henan, China; Department of Pathophysiology, School of Basic Medical Science, Xinxiang Medical College, Xinxiang, Henan, China.
authors.forename: Yong-Hui
authors.initials: YH
authors.lastname: Mu
authors.affiliation: Department of Physiology, School of Medicine, Zhengzhou University, Zhengzhou, Henan, China.
authors.forename: Wen-Chao
authors.initials: WC
authors.lastname: Zhao
authors.affiliation: Department of Physiology, School of Medicine, Zhengzhou University, Zhengzhou, Henan, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Duan
authors.affiliation: Department of Physiology, School of Medicine, Zhengzhou University, Zhengzhou, Henan, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Biological Engineering, University of Henan, Kaifeng, Henan, China.
authors.forename: Wei-da
authors.initials: WD
authors.lastname: Zhao
authors.affiliation: Department of Physiology, School of Medicine, Zhengzhou University, Zhengzhou, Henan, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Hui-Yin
authors.initials: HY
authors.lastname: Tu
authors.affiliation: Department of Physiology, School of Medicine, Zhengzhou University, Zhengzhou, Henan, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D055724:Electrophysiological Phenomena; D055785:Gene Knockdown Techniques; D051379:Mice; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism
chemical_list: C496898:Kcnn2 protein, mouse; D012333:RNA, Messenger; D019837:Ryanodine Receptor Calcium Release Channel; D051640:Small-Conductance Calcium-Activated Potassium Channels; C000592748:ryanodine receptor 2. mouse; D011188:Potassium; D002118:Calcium
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