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Wang L, Chen Y, Li J, Westenbroek R, Philyaw T, Zheng N, Scott JD, Liu Q, Catterall WA. Anchored PKA synchronizes adrenergic phosphoregulation of cardiac Ca v1.2 channels. J Biol Chem 2024; 300:107656. [PMID: 39128715 PMCID: PMC11408856 DOI: 10.1016/j.jbc.2024.107656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 07/10/2024] [Accepted: 07/31/2024] [Indexed: 08/13/2024] Open
Abstract
Adrenergic modulation of voltage gated Ca2+ currents is a context specific process. In the heart Cav1.2 channels initiate excitation-contraction coupling. This requires PKA phosphorylation of the small GTPase Rad (Ras associated with diabetes) and involves direct phosphorylation of the Cav1.2 α1 subunit at Ser1700. A contributing factor is the proximity of PKA to the channel through association with A-kinase anchoring proteins (AKAPs). Disruption of PKA anchoring by the disruptor peptide AKAP-IS prevents upregulation of Cav1.2 currents in tsA-201 cells. Biochemical analyses demonstrate that Rad does not function as an AKAP. Electrophysiological recording shows that channel mutants lacking phosphorylation sites (Cav1.2 STAA) lose responsivity to the second messenger cAMP. Measurements in cardiomyocytes isolated from Rad-/- mice show that adrenergic activation of Cav1.2 is attenuated but not completely abolished. Whole animal electrocardiography studies reveal that cardiac selective Rad KO mice exhibited higher baseline left ventricular ejection fraction, greater fractional shortening, and increased heart rate as compared to control animals. Yet, each parameter of cardiac function was slightly elevated when Rad-/- mice were treated with the adrenergic agonist isoproterenol. Thus, phosphorylation of Cav1.2 and dissociation of phospho-Rad from the channel are local cAMP responsive events that act in concert to enhance L-type calcium currents. This convergence of local PKA regulatory events at the cardiac L-type calcium channel may permit maximal β-adrenergic influence on the fight-or-flight response.
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Affiliation(s)
- Lipeng Wang
- Department of Pharmacology, University of Washington, School of Medicine, Seattle, Washington, USA
| | - Yi Chen
- Department of Neurobiology and Biophysics, University of Washington, School of Medicine, Seattle, Washington, USA
| | - Jin Li
- Department of Pharmacology, University of Washington, School of Medicine, Seattle, Washington, USA
| | - Ruth Westenbroek
- Department of Pharmacology, University of Washington, School of Medicine, Seattle, Washington, USA
| | - Travis Philyaw
- Department of Pharmacology, University of Washington, School of Medicine, Seattle, Washington, USA
| | - Ning Zheng
- Department of Pharmacology, University of Washington, School of Medicine, Seattle, Washington, USA; Howard Hughes Medical Institute, University of Washington, School of Medicine, Seattle, Washington, USA
| | - John D Scott
- Department of Pharmacology, University of Washington, School of Medicine, Seattle, Washington, USA.
| | - Qinghang Liu
- Department of Neurobiology and Biophysics, University of Washington, School of Medicine, Seattle, Washington, USA.
| | - William A Catterall
- Department of Pharmacology, University of Washington, School of Medicine, Seattle, Washington, USA
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Wong YW, Haqqani H, Molenaar P. Roles of β-adrenoceptor Subtypes and Therapeutics in Human Cardiovascular Disease: Heart Failure, Tachyarrhythmias and Other Cardiovascular Disorders. Handb Exp Pharmacol 2024; 285:247-295. [PMID: 38844580 DOI: 10.1007/164_2024_720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
β-Adrenoceptors (β-ARs) provide an important therapeutic target for the treatment of cardiovascular disease. Three β-ARs, β1-AR, β2-AR, β3-AR are localized to the human heart. Activation of β1-AR and β2-ARs increases heart rate, force of contraction (inotropy) and consequently cardiac output to meet physiological demand. However, in disease, chronic over-activation of β1-AR is responsible for the progression of disease (e.g. heart failure) mediated by pathological hypertrophy, adverse remodelling and premature cell death. Furthermore, activation of β1-AR is critical in the pathogenesis of cardiac arrhythmias while activation of β2-AR directly influences blood pressure haemostasis. There is an increasing awareness of the contribution of β2-AR in cardiovascular disease, particularly arrhythmia generation. All β-blockers used therapeutically to treat cardiovascular disease block β1-AR with variable blockade of β2-AR depending on relative affinity for β1-AR vs β2-AR. Since the introduction of β-blockers into clinical practice in 1965, β-blockers with different properties have been trialled, used and evaluated, leading to better understanding of their therapeutic effects and tolerability in various cardiovascular conditions. β-Blockers with the property of intrinsic sympathomimetic activity (ISA), i.e. β-blockers that also activate the receptor, were used in the past for post-treatment of myocardial infarction and had limited use in heart failure. The β-blocker carvedilol continues to intrigue due to numerous properties that differentiate it from other β-blockers and is used successfully in the treatment of heart failure. The discovery of β3-AR in human heart created interest in the role of β3-AR in heart failure but has not resulted in therapeutics at this stage.
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Affiliation(s)
- Yee Weng Wong
- Cardiovascular Molecular & Therapeutics Translational Research Group, Northside Clinical School of Medicine, University of Queensland, The Prince Charles Hospital, Chermside, QLD, Australia
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Haris Haqqani
- Cardiovascular Molecular & Therapeutics Translational Research Group, Northside Clinical School of Medicine, University of Queensland, The Prince Charles Hospital, Chermside, QLD, Australia
- Department of Cardiology, The Prince Charles Hospital, Chermside, QLD, Australia
- Faculty of Medicine, University of Queensland, Brisbane, QLD, Australia
| | - Peter Molenaar
- Cardiovascular Molecular & Therapeutics Translational Research Group, Northside Clinical School of Medicine, University of Queensland, The Prince Charles Hospital, Chermside, QLD, Australia.
- Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia.
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Infield DT, Schene ME, Fazan FS, Galles GD, Galpin JD, Ahern CA. Real-time observation of functional specialization among phosphorylation sites in CFTR. J Gen Physiol 2023; 155:e202213216. [PMID: 36695813 PMCID: PMC9930130 DOI: 10.1085/jgp.202213216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 11/23/2022] [Accepted: 01/09/2023] [Indexed: 01/26/2023] Open
Abstract
Phosphoregulation is ubiquitous in biology. Defining the functional roles of individual phosphorylation sites within a multivalent system remains particularly challenging. We have therefore applied a chemical biology approach to light-control the state of single candidate phosphoserines in the canonical anion channel CFTR while simultaneously measuring channel activity. The data show striking non-equivalency among protein kinase A consensus sites, which vary from <10% to >1,000% changes in channel activity upon phosphorylation. Of note, slow phosphorylation of S813 suggests that this site is rate-limiting to the full activation of CFTR. Further, this approach reveals an unexpected coupling between the phosphorylation of S813 and a nearby site, S795. Overall, these data establish an experimental route to understanding roles of specific phosphoserines within complex phosphoregulatory domains. This strategy may be employed in the study of phosphoregulation of other eukaryotic proteins.
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Affiliation(s)
- Daniel T. Infield
- Department of Molecular Physiology and Biophysics and Iowa Neuroscience Institute, University of Iowa, Carver College of Medicine, Iowa, IA, USA
| | - Miranda E. Schene
- Department of Molecular Physiology and Biophysics and Iowa Neuroscience Institute, University of Iowa, Carver College of Medicine, Iowa, IA, USA
| | - Frederico S. Fazan
- Department of Molecular Physiology and Biophysics and Iowa Neuroscience Institute, University of Iowa, Carver College of Medicine, Iowa, IA, USA
| | - Grace D. Galles
- Department of Molecular Physiology and Biophysics and Iowa Neuroscience Institute, University of Iowa, Carver College of Medicine, Iowa, IA, USA
| | - Jason D. Galpin
- Department of Molecular Physiology and Biophysics and Iowa Neuroscience Institute, University of Iowa, Carver College of Medicine, Iowa, IA, USA
| | - Christopher A. Ahern
- Department of Molecular Physiology and Biophysics and Iowa Neuroscience Institute, University of Iowa, Carver College of Medicine, Iowa, IA, USA
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Convergent regulation of Ca V1.2 channels by direct phosphorylation and by the small GTPase RAD in the cardiac fight-or-flight response. Proc Natl Acad Sci U S A 2022; 119:e2208533119. [PMID: 36215501 PMCID: PMC9586275 DOI: 10.1073/pnas.2208533119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The L-type calcium currents conducted by the cardiac CaV1.2 calcium channel initiate excitation-contraction coupling and serve as a key regulator of heart rate, rhythm, and force of contraction. CaV1.2 is regulated by β-adrenergic/protein kinase A (PKA)-mediated protein phosphorylation, proteolytic processing, and autoinhibition by its carboxyl-terminal domain (CT). The small guanosine triphosphatase (GTPase) RAD (Ras associated with diabetes) has emerged as a potent inhibitor of CaV1.2, and accumulating evidence suggests a key role for RAD in mediating β-adrenergic/PKA upregulation of channel activity. However, the relative roles of direct phosphorylation of CaV1.2 channels and phosphorylation of RAD in channel regulation remain uncertain. Here, we investigated the hypothesis that these two mechanisms converge to regulate CaV1.2 channels. Both RAD and the proteolytically processed distal CT (dCT) strongly reduced CaV1.2 activity. PKA phosphorylation of RAD and phosphorylation of Ser-1700 in the proximal CT (pCT) synergistically reversed this inhibition and increased CaV1.2 currents. Our findings reveal that the proteolytically processed form of CaV1.2 undergoes convergent regulation by direct phosphorylation of the CT and by phosphorylation of RAD. These parallel regulatory pathways provide a flexible mechanism for upregulation of the activity of CaV1.2 channels in the fight-or-flight response.
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Vascular Ca V1.2 channels in diabetes. CURRENT TOPICS IN MEMBRANES 2022; 90:65-93. [PMID: 36368875 DOI: 10.1016/bs.ctm.2022.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Diabetic vasculopathy is a significant cause of morbidity and mortality in the diabetic population. Hyperglycemia, one of the central metabolic abnormalities in diabetes, has been associated with vascular dysfunction due to endothelial cell damage. However, studies also point toward vascular smooth muscle as a locus for hyperglycemia-induced vascular dysfunction. Emerging evidence implicates hyperglycemia-induced regulation of vascular L-type Ca2+ channels CaV1.2 as a potential mechanism for vascular dysfunction during diabetes. This chapter summarizes our current understanding of vascular CaV1.2 channels and their regulation during physiological and hyperglycemia/diabetes conditions. We will emphasize the role of CaV1.2 in vascular smooth muscle, the effects of elevated glucose on CaV1.2 function, and the mechanisms underlying its dysregulation in hyperglycemia and diabetes. We conclude by examining future directions and gaps in knowledge regarding CaV1.2 regulation in health and during diabetes.
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Yuasa M, Kojima A, Mi X, Ding WG, Omatsu-Kanbe M, Kitagawa H, Matsuura H. Characterization and functional role of rapid- and slow-activating delayed rectifier K + currents in atrioventricular node cells of guinea pigs. Pflugers Arch 2021; 473:1885-1898. [PMID: 34704178 DOI: 10.1007/s00424-021-02617-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 08/05/2021] [Accepted: 08/19/2021] [Indexed: 01/28/2023]
Abstract
The atrioventricular (AV) node is the only conduction pathway where electrical impulse can pass from atria to ventricles and exhibits spontaneous automaticity. This study examined the function of the rapid- and slow-activating delayed rectifier K+ currents (IKr and IKs) in the regulation of AV node automaticity. Isolated AV node cells from guinea pigs were current- and voltage-clamped to record the action potentials and the IKr and IKs current. The expression of IKr or IKs was confirmed in the AV node cells by immunocytochemistry, and the positive signals of both channels were localized mainly on the cell membrane. The basal spontaneous automaticity was equally reduced by E4031 and HMR-1556, selective blockers of IKr and IKs, respectively. The nonselective β-adrenoceptor agonist isoproterenol markedly increased the firing rate of action potentials. In the presence of isoproterenol, the firing rate of action potentials was more effectively reduced by the IKs inhibitor HMR-1556 than by the IKr inhibitor E4031. Both E4031 and HMR-1556 prolonged the action potential duration and depolarized the maximum diastolic potential under basal and β-adrenoceptor-stimulated conditions. IKr was not significantly influenced by β-adrenoceptor stimulation, but IKs was concentration-dependently enhanced by isoproterenol (EC50: 15 nM), with a significant negative voltage shift in the channel activation. These findings suggest that both the IKr and IKs channels might exert similar effects on regulating the repolarization process of AV node action potentials under basal conditions; however, when the β-adrenoceptor is activated, IKs modulation may become more important.
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Affiliation(s)
- Mayumi Yuasa
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan
| | - Akiko Kojima
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan
| | - Xinya Mi
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan
| | - Wei-Guang Ding
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan.
| | - Mariko Omatsu-Kanbe
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan
| | - Hirotoshi Kitagawa
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan
| | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan
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Miranda DR, Voss AA, Bannister RA. Into the spotlight: RGK proteins in skeletal muscle. Cell Calcium 2021; 98:102439. [PMID: 34261001 DOI: 10.1016/j.ceca.2021.102439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/24/2021] [Accepted: 06/26/2021] [Indexed: 10/20/2022]
Abstract
The RGK (Rad, Rem, Rem2 and Gem/Kir) family of small GTPases are potent endogenous inhibitors of voltage-gated Ca2+ channels (VGCCs). While the impact of RGK proteins on cardiac physiology has been investigated extensively, much less is known regarding their influence on skeletal muscle biology. Thus, the purpose of this article is to establish a basis for future investigation into the role of RGK proteins in regulating the skeletal muscle excitation-contraction (EC) coupling complex via modulation of the L-type CaV1.1 VGCC. The pathological consequences of elevated muscle RGK protein expression in Type II Diabetes, Amyotrophic Lateral Sclerosis (ALS), Duchenne's Muscular Dystrophy and traumatic nerve injury are also discussed.
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Affiliation(s)
- Daniel R Miranda
- Department of Biological Sciences, College of Science and Mathematics, Wright State University, 235A Biological Sciences, 3640 Colonel Glenn Highway, Dayton, OH 45435, USA
| | - Andrew A Voss
- Department of Biological Sciences, College of Science and Mathematics, Wright State University, 235A Biological Sciences, 3640 Colonel Glenn Highway, Dayton, OH 45435, USA.
| | - Roger A Bannister
- Departments of Pathology and Biochemistry & Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD 21201, USA.
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Reconstitution of β-adrenergic regulation of Ca V1.2: Rad-dependent and Rad-independent protein kinase A mechanisms. Proc Natl Acad Sci U S A 2021; 118:2100021118. [PMID: 34001616 DOI: 10.1073/pnas.2100021118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
L-type voltage-gated CaV1.2 channels crucially regulate cardiac muscle contraction. Activation of β-adrenergic receptors (β-AR) augments contraction via protein kinase A (PKA)-induced increase of calcium influx through CaV1.2 channels. To date, the full β-AR cascade has never been heterologously reconstituted. A recent study identified Rad, a CaV1.2 inhibitory protein, as essential for PKA regulation of CaV1.2. We corroborated this finding and reconstituted the complete pathway with agonist activation of β1-AR or β2-AR in Xenopus oocytes. We found, and distinguished between, two distinct pathways of PKA modulation of CaV1.2: Rad dependent (∼80% of total) and Rad independent. The reconstituted system reproduces the known features of β-AR regulation in cardiomyocytes and reveals several aspects: the differential regulation of posttranslationally modified CaV1.2 variants and the distinct features of β1-AR versus β2-AR activity. This system allows for the addressing of central unresolved issues in the β-AR-CaV1.2 cascade and will facilitate the development of therapies for catecholamine-induced cardiac pathologies.
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