title: Regulation of the Cav1.2 cardiac channel by redox via modulation of CaM interaction with the channel.
abstract: Although it has been well documented that redox can modulate Cav1.2 channel activity, the underlying mechanisms are not fully understood. In our study, we examined the effects of redox on Cav1.2 channel activity and on CaM interaction with the Cav1.2 α1 subunit. Dithiothreitol (DTT, 1 mM) in the cell-attached mode decreased, while hydrogen peroxide (H2O2, 1 mM) increased channel activity to 72 and 303%, respectively. The effects of redox were maintained in the inside-out mode where channel activity was induced by CaM + ATP: DTT (1 mM) decreased, while H2O2 (1 mM) increased the channel activity. These results were mimicked by the thioredoxin and oxidized glutathione system. To test whether the redox state might determine channel activity by affecting the CaM interaction with the channel, we examined the effects of DTT and H2O2 on CaM binding to the N- and C-terminal fragments of the channel. We found that DTT concentration-dependently inhibited CaM binding to the C-terminus (IC50 37 μM), but H2O2 had no effect. Neither DTT nor H2O2 had an effect on CaM interaction with the N-terminus. These results suggest that redox-mediated regulation of the Cav1.2 channel is governed, at least partially, by modulation of the CaM interaction with the channel.
authors.affiliation: Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110122, China; Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
authors.forename: Etsuko
authors.initials: E
authors.lastname: Minobe
authors.affiliation: Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
authors.forename: Shoken
authors.initials: S
authors.lastname: Shimoara
authors.affiliation: Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110122, China. Electronic address: lyhao@mail.cmu.edu.cn.
authors.forename: Liying
authors.initials: L
authors.lastname: Hao
authors.affiliation: Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan. Electronic address: kame@m.kufm.kagoshima-u.ac.jp.
authors.forename: Masaki
authors.initials: M
authors.lastname: Kameyama
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism / Q000502:physiology*; D002147:Calmodulin / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D004229:Dithiothreitol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000166:cytology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010084:Oxidation-Reduction
chemical_list: D020746:Calcium Channels, L-Type; D002147:Calmodulin; C419385:L-type calcium channel alpha(1C); D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D004229:Dithiothreitol
keywords: Calmodulin; Cardiac myocyte; Cav1.2 channel; Ion channel regulation; Redox