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Zhang C, Shao D, Zheng X, Hao L. The mechanism of LQTS related CaM mutation E141G interfering with Ca V1.2 channels function through its C-lobe. J Physiol Biochem 2024:10.1007/s13105-024-01064-5. [PMID: 39699847 DOI: 10.1007/s13105-024-01064-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 11/28/2024] [Indexed: 12/20/2024]
Abstract
Mutations in the CALM1-3 genes, which encode calmodulin (CaM), have been reported in clinical cases of long QT syndrome (LQTS). Specifically, the CaM mutant E141G (CaME141G) in the variant CALM1 gene has been identified as a causative factor in LQTS. This mutation disrupts the normal Ca2+-dependent inactivation (CDI) function of CaV1.2 channels. However, it is still unclear how CaME141G interferes with the regulatory role of wild-type (WT) CaM on CaV1.2 channels and leads to abnormal CDI. A CaM molecule contains two lobes with similar structure, the N-lobe and the C-lobe. In this study, a CaM-truncated C-lobe mutant E141G (C-lobeE141G) was engineered to exclude the impact of the unmutated N-lobe. Our findings revealed that at low Ca2+ concentration ([Ca2+]), the binding of C-lobeE141G to the preIQ, IQ and N-terminus (NT) of CaV1.2 channels has higher binding capacity (Bmax: 0.17, 0.22, 0.13) compared with those of WT C-lobe (Bmax: 0.04, 0.14, 0.11) in GST pull-down assay. With an increase in [Ca2+], the Ca2+-dependency for C-lobeE141G binding to CaV1.2 channels was impaired. Moreover, C-lobeE141G induced the relative channel activity to 240.58 ± 51.37% at resting [Ca2+], but it was unable to diminish the channel activity at high [Ca2+] even in the presence of WT N-lobe, which may be responsible for the abnormal CDI of CaV1.2 channels affected by the LQTS-related CaM mutation. Our research provides preliminary insights into the mechanism by which the CaM mutation interferes with CaV1.2 channels function through its C-lobe.
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Affiliation(s)
- Chenyang Zhang
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Dongxue Shao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Xi Zheng
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, 110122, China.
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2
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Kameyama M, Minobe E, Shao D, Xu J, Gao Q, Hao L. Regulation of Cardiac Cav1.2 Channels by Calmodulin. Int J Mol Sci 2023; 24:ijms24076409. [PMID: 37047381 PMCID: PMC10094977 DOI: 10.3390/ijms24076409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/19/2023] [Accepted: 03/23/2023] [Indexed: 03/31/2023] Open
Abstract
Cav1.2 Ca2+ channels, a type of voltage-gated L-type Ca2+ channel, are ubiquitously expressed, and the predominant Ca2+ channel type, in working cardiac myocytes. Cav1.2 channels are regulated by the direct interactions with calmodulin (CaM), a Ca2+-binding protein that causes Ca2+-dependent facilitation (CDF) and inactivation (CDI). Ca2+-free CaM (apoCaM) also contributes to the regulation of Cav1.2 channels. Furthermore, CaM indirectly affects channel activity by activating CaM-dependent enzymes, such as CaM-dependent protein kinase II and calcineurin (a CaM-dependent protein phosphatase). In this article, we review the recent progress in identifying the role of apoCaM in the channel ‘rundown’ phenomena and related repriming of channels, and CDF, as well as the role of Ca2+/CaM in CDI. In addition, the role of CaM in channel clustering is reviewed.
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Affiliation(s)
- Masaki Kameyama
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
- Correspondence:
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
| | - Dongxue Shao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
| | - Jianjun Xu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
| | - Qinghua Gao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
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3
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Montenarh M, Götz C. Protein kinase CK2 and ion channels (Review). Biomed Rep 2020; 13:55. [PMID: 33082952 PMCID: PMC7560519 DOI: 10.3892/br.2020.1362] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/28/2020] [Indexed: 12/18/2022] Open
Abstract
Protein kinase CK2 appears as a tetramer or higher molecular weight oligomer composed of catalytic CK2α, CK2α' subunits and non-catalytic regulatory CK2β subunits or as individual subunits. It is implicated in a variety of different regulatory processes, such as Akt signalling, splicing and DNA repair within eukaryotic cells. The present review evaluates the influence of CK2 on ion channels in the plasma membrane. CK2 phosphorylates platform proteins such as calmodulin and ankyrin G, which bind to channel proteins for a physiological transport to and positioning into the membrane. In addition, CK2 directly phosphorylates a variety of channel proteins directly to regulate opening and closing of the channels. Thus, modulation of CK2 activities by specific inhibitors, by siRNA technology or by CRISPR/Cas technology has an influence on intracellular ion concentrations and thereby on cellular signalling. The physiological regulation of the intracellular ion concentration is important for cell survival and correct intracellular signalling. Disturbance of this regulation results in a variety of different diseases including epilepsy, heart failure, cystic fibrosis and diabetes. Therefore, these effects should be considered when using CK2 inhibition as a treatment option for cancer.
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Affiliation(s)
- Mathias Montenarh
- Medical Biochemistry and Molecular Biology, Saarland University, D-66424 Homburg, Saarland, Germany
| | - Claudia Götz
- Medical Biochemistry and Molecular Biology, Saarland University, D-66424 Homburg, Saarland, Germany
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4
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Neumaier F, Alpdogan S, Hescheler J, Schneider T. Protein phosphorylation maintains the normal function of cloned human Ca v2.3 channels. J Gen Physiol 2018; 150:491-510. [PMID: 29453293 PMCID: PMC5839719 DOI: 10.1085/jgp.201711880] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 12/22/2017] [Accepted: 01/24/2018] [Indexed: 11/30/2022] Open
Abstract
Cav2.3 Ca2+ channels are subject to cytosolic regulation, which has been difficult to characterize in native cells. Neumaier et al. demonstrate the role of phosphorylation in the function of these channels and suggest a close relationship between voltage dependence and the phosphorylation state. R-type currents mediated by native and recombinant Cav2.3 voltage-gated Ca2+ channels (VGCCs) exhibit facilitation (run-up) and subsequent decline (run-down) in whole-cell patch-clamp recordings. A better understanding of the two processes could provide insight into constitutive modulation of the channels in intact cells, but low expression levels and the need for pharmacological isolation have prevented investigations in native systems. Here, to circumvent these limitations, we use conventional and perforated-patch-clamp recordings in a recombinant expression system, which allows us to study the effects of cell dialysis in a reproducible manner. We show that the decline of currents carried by human Cav2.3+β3 channel subunits during run-down is related to adenosine triphosphate (ATP) depletion, which reduces the number of functional channels and leads to a progressive shift of voltage-dependent gating to more negative potentials. Both effects can be counteracted by hydrolysable ATP, whose protective action is almost completely prevented by inhibition of serine/threonine but not tyrosine or lipid kinases. Protein kinase inhibition also mimics the effects of run-down in intact cells, reduces the peak current density, and hyperpolarizes the voltage dependence of gating. Together, our findings indicate that ATP promotes phosphorylation of either the channel or an associated protein, whereas dephosphorylation during cell dialysis results in run-down. These data also distinguish the effects of ATP on Cav2.3 channels from those on other VGCCs because neither direct nucleotide binding nor PIP2 synthesis is required for protection from run-down. We conclude that protein phosphorylation is required for Cav2.3 channel function and could directly influence the normal features of current carried by these channels. Curiously, some of our findings also point to a role for leupeptin-sensitive proteases in run-up and possibly ATP protection from run-down. As such, the present study provides a reliable baseline for further studies on Cav2.3 channel regulation by protein kinases, phosphatases, and possibly proteases.
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Affiliation(s)
- Felix Neumaier
- Institute for Neurophysiology, University of Cologne, Cologne, Germany
| | - Serdar Alpdogan
- Institute for Neurophysiology, University of Cologne, Cologne, Germany
| | - Jürgen Hescheler
- Institute for Neurophysiology, University of Cologne, Cologne, Germany
| | - Toni Schneider
- Institute for Neurophysiology, University of Cologne, Cologne, Germany
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Wölkart G, Schrammel A, Koyani CN, Scherübel S, Zorn‐Pauly K, Malle E, Pelzmann B, Andrä M, Ortner A, Mayer B. Cardioprotective effects of 5-hydroxymethylfurfural mediated by inhibition of L-type Ca 2+ currents. Br J Pharmacol 2017; 174:3640-3653. [PMID: 28768052 PMCID: PMC5610158 DOI: 10.1111/bph.13967] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 07/11/2017] [Accepted: 07/14/2017] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE The antioxidant 5-hydroxymethylfurfural (5-HMF) exerts documented beneficial effects in several experimental pathologies and is currently tested as an antisickling drug in clinical trials. In the present study, we examined the cardiovascular effects of 5-HMF and elucidated the mode of action of the drug. EXPERIMENTAL APPROACH The cardiovascular effects of 5-HMF were studied with pre-contracted porcine coronary arteries and rat isolated normoxic-perfused hearts. Isolated hearts subjected to ischaemia/reperfusion (I/R) injury were used to test for potential cardioprotective effects of the drug. The effects of 5-HMF on action potential and L-type Ca2+ current (ICa,L ) were studied by patch-clamping guinea pig isolated ventricular cardiomyocytes. KEY RESULTS 5-HMF relaxed coronary arteries in a concentration-dependent manner and exerted negative inotropic, lusitropic and chronotropic effects in rat isolated perfused hearts. On the other hand, 5-HMF improved recovery of inotropic and lusitropic parameters in isolated hearts subjected to I/R. Patch clamp experiments revealed that 5-HMF inhibits L-type Ca2+ channels. Reduced ICa,L density, shift of ICa,L steady-state inactivation curves toward negative membrane potentials and slower recovery of ICa,L from inactivation in response to 5-HMF accounted for the observed cardiovascular effects. CONCLUSIONS AND IMPLICATIONS Our data revealed a cardioprotective effect of 5-HMF in I/R that is mediated by inhibition of L-type Ca2+ channels. Thus, 5-HMF is suggested as a beneficial additive to cardioplegic solutions, but adverse effects and contraindications of Ca2+ channel blockers have to be considered in therapeutic application of the drug.
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Affiliation(s)
- G Wölkart
- Institute of Pharmaceutical Sciences, Department of Pharmacology and ToxicologyUniversity of GrazGrazAustria
| | - A Schrammel
- Institute of Pharmaceutical Sciences, Department of Pharmacology and ToxicologyUniversity of GrazGrazAustria
| | - C N Koyani
- Institute of Molecular Biology and BiochemistryMedical University of GrazGrazAustria
| | - S Scherübel
- Institute of BiophysicsMedical University of GrazGrazAustria
| | - K Zorn‐Pauly
- Institute of BiophysicsMedical University of GrazGrazAustria
| | - E Malle
- Institute of Molecular Biology and BiochemistryMedical University of GrazGrazAustria
| | - B Pelzmann
- Institute of BiophysicsMedical University of GrazGrazAustria
| | - M Andrä
- Department of Thoracic and Cardiovascular SurgeryKlinikum KlagenfurtKlagenfurtAustria
| | - A Ortner
- Institute of Pharmaceutical Sciences, Department of Pharmaceutical ChemistryUniversity of GrazGrazAustria
| | - B Mayer
- Institute of Pharmaceutical Sciences, Department of Pharmacology and ToxicologyUniversity of GrazGrazAustria
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Minobe E, Mori MX, Kameyama M. Calmodulin and ATP support activity of the Cav1.2 channel through dynamic interactions with the channel. J Physiol 2017; 595:2465-2477. [PMID: 28130847 PMCID: PMC5390892 DOI: 10.1113/jp273736] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 01/06/2017] [Indexed: 11/08/2022] Open
Abstract
Key points Cav1.2 channels maintain activity through interactions with calmodulin (CaM). In this study, activities of the Cav1.2 channel (α1C) and of mutant‐derivatives, C‐terminal deleted (α1CΔ) and α1CΔ linked with CaM (α1CΔCaM), were compared in the inside‐out mode. α1CΔ with CaM, but not without CaM, and α1CΔCaM were active, suggesting that CaM induced channel activity through a dynamic interaction with the channel, even without the distal C‐tail. ATP induced α1C activity with CaM and enhanced activity of the mutant channels. Okadaic acid mimicked the effect of ATP on the wildtype but not mutant channels. These results supported the hypothesis that CaM and ATP maintain activity of Cav1.2 channels through their dynamic interactions. ATP effects involve mechanisms both related and unrelated to channel phosphorylation. CaM‐linked channels are useful tools for investigating Cav1.2 channels in the inside‐out mode; the fast run‐down is prevented by only ATP and the slow run‐down is nearly absent.
Abstract Calmodulin (CaM) plays a critical role in regulation of Cav1.2 Ca2+ channels. CaM binds to the channel directly, maintaining channel activity and regulating it in a Ca2+‐dependent manner. To explore the molecular mechanisms involved, we compared the activity of the wildtype channel (α1C) and mutant derivatives, C‐terminal deleted (α1C∆) and α1C∆ linked to CaM (α1C∆CaM). These were co‐expressed with β2a and α2δ subunits in HEK293 cells. In the inside‐out mode, α1C and α1C∆ showed minimal open‐probabilities in a basic internal solution (run‐down), whereas α1C∆ with CaM and α1C∆CaM maintained detectable channel activity, confirming that CaM was necessary, but not sufficient, for channel activity. Previously, we reported that ATP was required to maintain channel activity of α1C. Unlike α1C, the mutant channels did not require ATP for activation in the early phase (3–5 min). However, α1C∆ with CaM + ATP and α1C∆CaM with ATP maintained activity, even in the late phase (after 7–9 min). These results suggested that CaM and ATP interacted dynamically with the proximal C‐terminal tail of the channel and, thereby, produced channel activity. In addition, okadaic acid, a protein phosphatase inhibitor, could substitute for the effects of ATP on α1C but not on the mutant channels. These results supported the hypothesis that CaM and ATP maintain activity of Cav1.2 channels, further indicating that ATP has dual effects. One maintains phosphorylation of the channel and the other becomes apparent when the distal carboxyl‐terminal tail is removed. Cav1.2 channels maintain activity through interactions with calmodulin (CaM). In this study, activities of the Cav1.2 channel (α1C) and of mutant‐derivatives, C‐terminal deleted (α1CΔ) and α1CΔ linked with CaM (α1CΔCaM), were compared in the inside‐out mode. α1CΔ with CaM, but not without CaM, and α1CΔCaM were active, suggesting that CaM induced channel activity through a dynamic interaction with the channel, even without the distal C‐tail. ATP induced α1C activity with CaM and enhanced activity of the mutant channels. Okadaic acid mimicked the effect of ATP on the wildtype but not mutant channels. These results supported the hypothesis that CaM and ATP maintain activity of Cav1.2 channels through their dynamic interactions. ATP effects involve mechanisms both related and unrelated to channel phosphorylation. CaM‐linked channels are useful tools for investigating Cav1.2 channels in the inside‐out mode; the fast run‐down is prevented by only ATP and the slow run‐down is nearly absent.
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Affiliation(s)
- Etsuko Minobe
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Masayuki X Mori
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan
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7
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Yu L, Xu J, Minobe E, Kameyama A, Yang L, Feng R, Hao L, Kameyama M. Role of protein phosphatases in the run down of guinea pig cardiac Cav1.2 Ca2+ channels. Am J Physiol Cell Physiol 2016; 310:C773-9. [DOI: 10.1152/ajpcell.00199.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 01/05/2016] [Indexed: 12/26/2022]
Abstract
This study aimed to investigate protein phosphatases involved in the run down of Cav1.2 Ca2+ channels. Single ventricular myocytes obtained from adult guinea pig hearts were used to record Ca2+ channel currents with the patch-clamp technique. Calmodulin (CaM) and ATP were used to restore channel activity in inside-out patches. Inhibitors of protein phosphatases were applied to investigate the role of phosphatases. The specific protein phosphatase type 1 (PP1) inhibitor (PP1 inhibitor-2) and protein phosphatase type 2A (PP2A) inhibitor (fostriecin) abolished the slow run down of Cav1.2 Ca2+ channels, which was evident as the time-dependent attenuation of the reversing effect of CaM/ATP on the run down. However, protein phosphatase type 2B (PP2B, calcineurin) inhibitor cyclosporine A together with cyclophilin A had no effect on the channel run down. Furthermore, PP1 inhibitor-2 mainly prolonged the open time constants of the channel, specifically, the slow open time. Fostriecin primarily shortened the slow close time constants. Our data suggest that PP1 and PP2A were involved in the slow phase of Cav1.2 Ca2+ channel run down. In addition, they exerted different effects on the open-close kinetics of the channel. All above support the view that PP1 and PP2A may dephosphorylate distinct phosphorylation sites on the Cav1.2 Ca2+ channel.
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Affiliation(s)
- Lifeng Yu
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China; and
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Jianjun Xu
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Asako Kameyama
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Lei Yang
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Rui Feng
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China; and
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China; and
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
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Xu J, Yu L, Minobe E, Lu L, Lei M, Kameyama M. PKA and phosphatases attached to the Ca(V)1.2 channel regulate channel activity in cell-free patches. Am J Physiol Cell Physiol 2015; 310:C136-41. [PMID: 26561637 DOI: 10.1152/ajpcell.00157.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 11/02/2015] [Indexed: 11/22/2022]
Abstract
Calmodulin (CaM) + ATP can reprime voltage-gated L-type Ca(2+) channels (Ca(V)1.2) in inside-out patches for activation, but this effect decreases time dependently. This suggests that the Ca(V)1.2 channel activity is regulated by additional cytoplasmic factors. To test this hypothesis, we examined the role of cAMP-dependent protein kinase A (PKA) and protein phosphatases in the regulation of Ca(V)1.2 channel activity in the inside-out mode in guinea pig ventricular myocytes. Ca(V)1.2 channel activity quickly disappeared after the patch was excised from the cell and recovered to only 9% of that in the cell-attached mode on application of CaM + ATP at 10 min after the inside out. However, immediate exposure of the excised patch to the catalytic subunit of PKA + ATP or the nonspecific phosphatase inhibitor okadaic acid significantly increased the Ca(V)1.2 channel activity recovery by CaM + ATP (114 and 96%, respectively) at 10 min. Interestingly, incubation of the excised patches with cAMP + ATP also increased CaM/ATP-induced Ca(V)1.2 channel activity recovery (108%), and this effect was blocked by the nonspecific protein kinase inhibitor K252a. The channel activity in the inside-out mode was not maintained by either catalytic subunit of PKA or cAMP + ATP in the absence of CaM, but was stably maintained in the presence of CaM for more than 40 min. These results suggest that PKA and phosphatase(s) attached on or near the Ca(V)1.2 channel regulate the basal channel activity, presumably through modulation of the dynamic CaM interaction with the channel.
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Affiliation(s)
- Jianjun Xu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Lifeng Yu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China; Department of Ethnopharmacology, School of Pharmacy, China Medical University, Shenyang, China; and
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Liting Lu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Laboratory of Environmental Biology, Northeastern University, Shenyang, China
| | - Ming Lei
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan;
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9
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Sun Y, Xu J, Minobe E, Shimoara S, Hao L, Kameyama M. Regulation of the Cav1.2 cardiac channel by redox via modulation of CaM interaction with the channel. J Pharmacol Sci 2015; 128:137-43. [PMID: 26169579 DOI: 10.1016/j.jphs.2015.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 06/02/2015] [Accepted: 06/16/2015] [Indexed: 02/07/2023] Open
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.
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Affiliation(s)
- Yu Sun
- 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
| | - Jianjun Xu
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan
| | - Shoken Shimoara
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110122, China.
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
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10
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FENG RUI, LIU YAN, SUN XUEFEI, WANG YAN, HU HUIYUAN, GUO FENG, ZHAO JINSHENG, HAO LIYING. Molecular cloning and expression of the calmodulin gene from guinea pig hearts. Exp Ther Med 2015; 9:2311-2318. [DOI: 10.3892/etm.2015.2411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 03/19/2015] [Indexed: 11/06/2022] Open
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11
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Liu SY, Xu JJ, Minobe E, Gao QH, Feng R, Zhao MM, Guo F, Yang L, Hao LY, Kameyama M. Nucleotides maintain the activity of Cav1.2 channels in guinea-pig ventricular myocytes. Biochem Biophys Res Commun 2015; 460:813-8. [PMID: 25824040 DOI: 10.1016/j.bbrc.2015.03.111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 03/20/2015] [Indexed: 11/15/2022]
Abstract
The activity of Cav1.2 Ca(2+) channels is maintained in the presence of calmodulin and ATP, even in cell-free patches, and thus a channel ATP-binding site has been suggested. In this study, we examined whether other nucleotides, such as GTP, UTP, CTP, ADP and AMP, could be substituted for ATP in guinea-pig ventricular myocytes. We found that all the nucleotides tested could re-prime the Ca(2+) channels in the presence of 1 μM calmodulin in the inside-out mode. The order of efficacy was ATP > GTP > UTP > ADP > CTP ≈ AMP. Thus, the presumed nucleotide-binding site in the channel seemed to favor a purine rather than pyrimidine base and a triphosphate rather than a di- or mono-phosphate group. Furthermore, a high concentration (10 mM) of GTP, UTP, CTP, ADP and AMP had inhibitory effects on the channel activity. These results provide information on the putative nucleotide-binding site(s) in Cav1.2 Ca(2+) channels.
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Affiliation(s)
- Shu-yuan Liu
- 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, Kagoshima 890-8544, Japan
| | - Jian-jun Xu
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan
| | - Qing-hua Gao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110122, China
| | - Rui Feng
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110122, China; Cardiovascular Institute of China Medical University, Shenyang 110001, China
| | - Mei-mi Zhao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110122, China; Cardiovascular Institute of China Medical University, Shenyang 110001, China
| | - Feng Guo
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110122, China; Cardiovascular Institute of China Medical University, Shenyang 110001, China
| | - Lei Yang
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan
| | - Li-ying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110122, China; Cardiovascular Institute of China Medical University, Shenyang 110001, China.
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan.
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Guo F, Zhou PD, Gao QH, Gong J, Feng R, Xu XX, Liu SY, Hu HY, Zhao MM, Adam HC, Cai JQ, Hao LY. Low-Mg(2+) treatment increases sensitivity of voltage-gated Na(+) channels to Ca(2+)/calmodulin-mediated modulation in cultured hippocampal neurons. Am J Physiol Cell Physiol 2015; 308:C594-605. [PMID: 25652447 DOI: 10.1152/ajpcell.00174.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 01/30/2015] [Indexed: 02/06/2023]
Abstract
Culture of hippocampal neurons in low-Mg(2+) medium (low-Mg(2+) neurons) results in induction of continuous seizure activity. However, the underlying mechanism of the contribution of low Mg(2+) to hyperexcitability of neurons has not been clarified. Our data, obtained using the patch-clamp technique, show that voltage-gated Na(+) channel (VGSC) activity, which is associated with a persistent, noninactivating Na(+) current (INa,P), was modulated by calmodulin (CaM) in a concentration-dependent manner in normal and low-Mg(2+) neurons, but the channel activity was more sensitive to Ca(2+)/CaM regulation in low-Mg(2+) than normal neurons. The increased sensitivity of VGSCs in low-Mg(2+) neurons was partially retained when CaM12 and CaM34, CaM mutants with disabled binding sites in the N or C lobe, were used but was diminished when CaM1234, a CaM mutant in which all four Ca(2+) sites are disabled, was used, indicating that functional Ca(2+)-binding sites from either lobe of CaM are required for modulation of VGSCs in low-Mg(2+) neurons. Furthermore, the number of neurons exhibiting colocalization of CaM with the VGSC subtypes NaV1.1, NaV1.2, and NaV1.3 was significantly higher in low- Mg(2+) than normal neurons, as shown by immunofluorescence. Our main finding is that low-Mg(2+) treatment increases sensitivity of VGSCs to Ca(2+)/CaM-mediated regulation. Our data reveal that CaM, as a core regulating factor, connects the functional roles of the three main intracellular ions, Na(+), Ca(2+), and Mg(2+), by modulating VGSCs and provides a possible explanation for the seizure discharge observed in low-Mg(2+) neurons.
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Affiliation(s)
- Feng Guo
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Pei-Dong Zhou
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Qing-Hua Gao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Jian Gong
- Department of Clinical Pharmacy, School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical University, Shenyang, China
| | - Rui Feng
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Xiao-Xue Xu
- Department of Neurology, The First Hospital of China Medical University, Shenyang, China; and
| | - Shu-Yuan Liu
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Hui-Yuan Hu
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Mei-Mi Zhao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Hogan-Cann Adam
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Ji-Qun Cai
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Li-Ying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
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Kameyama M, Minobe E, Xu JJ, Han DY, Hadhimulya A, Kameyama A, Feng R, Liu S, Hao LY. [Regulation of L-type (CaV1.2) Ca(2+) channels by calmodulin and ATP]. Nihon Yakurigaku Zasshi 2014; 144:222-226. [PMID: 25381891 DOI: 10.1254/fpj.144.222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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