1
|
Thekkedam CG, Dutka TL, Van der Poel C, Burgio G, Dulhunty AF. The RyR1 P3528S Substitution Alters Mouse Skeletal Muscle Contractile Properties and RyR1 Ion Channel Gating. Int J Mol Sci 2023; 25:434. [PMID: 38203604 PMCID: PMC10778724 DOI: 10.3390/ijms25010434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
The recessive Ryanodine Receptor Type 1 (RyR1) P3527S mutation causes mild muscle weakness in patients and increased resting cytoplasmic [Ca2+] in transformed lymphoblastoid cells. In the present study, we explored the cellular/molecular effects of this mutation in a mouse model of the mutation (RyR1 P3528S). The results were obtained from 73 wild type (WT/WT), 82 heterozygous (WT/MUT) and 66 homozygous (MUT/MUT) mice with different numbers of observations in individual data sets depending on the experimental protocol. The results showed that WT/MUT and MUT/MUT mouse strength was less than that of WT/WT mice, but there was no difference between genotypes in appearance, weight, mobility or longevity. The force frequency response of extensor digitorum longus (EDL) and soleus (SOL) muscles from WT/MUT and MUT/MUT mice was shifter to higher frequencies. The specific force of EDL muscles was reduced and Ca2+ activation of skinned fibres shifted to a lower [Ca2+], with an increase in type I fibres in EDL muscles and in mixed type I/II fibres in SOL muscles. The relative activity of RyR1 channels exposed to 1 µM cytoplasmic Ca2+ was greater in WT/MUT and MUT/MUT mice than in WT/WT mice. We suggest the altered RyR1 activity due to the P2328S substitution could increase resting [Ca2+] in muscle fibres, leading to changes in fibre type and contractile properties.
Collapse
Affiliation(s)
- Chris G. Thekkedam
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Acton, ACT 2601, Australia;
| | - Travis L. Dutka
- Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment (SABE), La Trobe University, Melbourne, VIC 3086, Australia;
| | - Chris Van der Poel
- Department of Microbiology, Anatomy, Physiology and Pharmacology, School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, VIC 3086, Australia;
| | - Gaetan Burgio
- Division of Genome Sciences and Cancer, John Curtin School of Medical Research, Australian National University, Acton, ACT 2601, Australia;
| | - Angela F. Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Acton, ACT 2601, Australia;
| |
Collapse
|
2
|
Dulhunty AF. Biophysical reviews top five: voltage-dependent charge movement in nerve and muscle. Biophys Rev 2023; 15:1903-1907. [PMID: 38192339 PMCID: PMC10771356 DOI: 10.1007/s12551-023-01165-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 11/02/2023] [Indexed: 01/10/2024] Open
Abstract
The discovery of gating currents and asymmetric charge movement in the early 1970s represented a remarkable leap forward in our understanding of the biophysical basis of voltage-dependent events that underlie electrical signalling that is vital for nerve and muscle function. Gating currents and charge movement reflect a fundamental process in which charged amino acid residues in an ion channel protein move in response to a change in the membrane electrical field and therefore activate the specific voltage-dependent response of that protein. The detection of gating currents and asymmetric charge movement over the past 50 years has been pivotal in unraveling the multiple molecular and intra-molecular processes which lead to action potentials in excitable tissues and excitation-contraction (EC) coupling in skeletal muscle. The recording of gating currents and asymmetric charge movement remains an essential component of investigations into the basic molecular mechanisms of neuronal conduction and muscle contraction.
Collapse
Affiliation(s)
- Angela F. Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, ACT, Canberra, 2601 Australia
| |
Collapse
|
3
|
Richardson SJ, Thekkedam CG, Casarotto MG, Beard NA, Dulhunty AF. FKBP12 binds to the cardiac ryanodine receptor with negative cooperativity: implications for heart muscle physiology in health and disease. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220169. [PMID: 37122219 PMCID: PMC10150220 DOI: 10.1098/rstb.2022.0169] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
Cardiac ryanodine receptors (RyR2) release the Ca2+ from intracellular stores that is essential for cardiac myocyte contraction. The ion channel opening is tightly regulated by intracellular factors, including the FK506 binding proteins, FKBP12 and FKBP12.6. The impact of these proteins on RyR2 activity and cardiac contraction is debated, with often apparently contradictory experimental results, particularly for FKBP12. The isoform that regulates RyR2 has generally been considered to be FKBP12.6, despite the fact that FKBP12 is the major isoform associated with RyR2 in some species and is bound in similar proportions to FKBP12.6 in others, including sheep and humans. Here, we show time- and concentration-dependent effects of adding FKBP12 to RyR2 channels that were partly depleted of FKBP12/12.6 during isolation. The added FKBP12 displaced most remaining endogenous FKBP12/12.6. The results suggest that FKBP12 activates RyR2 with high affinity and inhibits RyR2 with lower affinity, consistent with a model of negative cooperativity in FKBP12 binding to each of the four subunits in the RyR tetramer. The easy dissociation of some FKBP12/12.6 could dynamically alter RyR2 activity in response to changes in in vivo regulatory factors, indicating a significant role for FKBP12/12.6 in Ca2+ signalling and cardiac function in healthy and diseased hearts. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.
Collapse
Affiliation(s)
- S J Richardson
- John Curtin School of Medical Research, Australian National University, Canberra, Australia, Australian Capital Territory 2601, Australia
| | - C G Thekkedam
- John Curtin School of Medical Research, Australian National University, Canberra, Australia, Australian Capital Territory 2601, Australia
| | - M G Casarotto
- John Curtin School of Medical Research, Australian National University, Canberra, Australia, Australian Capital Territory 2601, Australia
| | - N A Beard
- John Curtin School of Medical Research, Australian National University, Canberra, Australia, Australian Capital Territory 2601, Australia
| | - A F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, Australia, Australian Capital Territory 2601, Australia
| |
Collapse
|
4
|
Salvage SC, Dulhunty AF, Jeevaratnam K, Jackson AP, Huang CLH. Feedback contributions to excitation-contraction coupling in native functioning striated muscle. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220162. [PMID: 37122213 PMCID: PMC10150225 DOI: 10.1098/rstb.2022.0162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
Skeletal and cardiac muscle excitation-contraction coupling commences with Nav1.4/Nav1.5-mediated, surface and transverse (T-) tubular, action potential generation. This initiates feedforward, allosteric or Ca2+-mediated, T-sarcoplasmic reticular (SR) junctional, voltage sensor-Cav1.1/Cav1.2 and ryanodine receptor-RyR1/RyR2 interaction. We review recent structural, physiological and translational studies on possible feedback actions of the resulting SR Ca2+ release on Nav1.4/Nav1.5 function in native muscle. Finite-element modelling predicted potentially regulatory T-SR junctional [Ca2+]TSR domains. Nav1.4/Nav1.5, III-IV linker and C-terminal domain structures included Ca2+ and/or calmodulin-binding sites whose mutations corresponded to specific clinical conditions. Loose-patch-clamped native murine skeletal muscle fibres and cardiomyocytes showed reduced Na+ currents (INa) following SR Ca2+ release induced by the Epac and direct RyR1/RyR2 activators, 8-(4-chlorophenylthio)adenosine-3',5'-cyclic monophosphate and caffeine, abrogated by the RyR inhibitor dantrolene. Conversely, dantrolene and the Ca2+-ATPase inhibitor cyclopiazonic acid increased INa. Experimental, catecholaminergic polymorphic ventricular tachycardic RyR2-P2328S and metabolically deficient Pgc1β-/- cardiomyocytes also showed reduced INa accompanying [Ca2+]i abnormalities rescued by dantrolene- and flecainide-mediated RyR block. Finally, hydroxychloroquine challenge implicated action potential (AP) prolongation in slowing AP conduction through modifying Ca2+ transients. The corresponding tissue/organ preparations each showed pro-arrhythmic, slowed AP upstrokes and conduction velocities. We finally extend discussion of possible Ca2+-mediated effects to further, Ca2+, K+ and Cl-, channel types. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.
Collapse
Affiliation(s)
- Samantha C Salvage
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Angela F Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Acton 2601, Australia
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Daphne Jackson Road, Guildford GU2 7XH, UK
| | - Antony P Jackson
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Christopher L-H Huang
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
- Faculty of Health and Medical Sciences, University of Surrey, Daphne Jackson Road, Guildford GU2 7XH, UK
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
| |
Collapse
|
5
|
Abstract
Flecainide, a cardiac class 1C blocker of the surface membrane sodium channel (NaV1.5), has also been reported to reduce cardiac ryanodine receptor (RyR2)-mediated sarcoplasmic reticulum (SR) Ca2+ release. It has been introduced as a clinical antiarrhythmic agent for catecholaminergic polymorphic ventricular tachycardia (CPVT), a condition most commonly associated with gain-of-function RyR2 mutations. Current debate concerns both cellular mechanisms of its antiarrhythmic action and molecular mechanisms of its RyR2 actions. At the cellular level, it targets NaV1.5, RyR2, Na+/Ca2+ exchange (NCX), and additional proteins involved in excitation-contraction (EC) coupling and potentially contribute to the CPVT phenotype. This Viewpoint primarily addresses the various direct molecular actions of flecainide on isolated RyR2 channels in artificial lipid bilayers. Such studies demonstrate different, multifarious, flecainide binding sites on RyR2, with voltage-dependent binding in the channel pore or voltage-independent binding at distant peripheral sites. In contrast to its single NaV1.5 pore binding site, flecainide may bind to at least four separate inhibitory sites on RyR2 and one activation site. None of these binding sites have been specifically located in the linear RyR2 sequence or high-resolution structure. Furthermore, it is not clear which of the inhibitory sites contribute to flecainide's reduction of spontaneous Ca2+ release in cellular studies. A confounding observation is that flecainide binding to voltage-dependent inhibition sites reduces cation fluxes in a direction opposite to physiological Ca2+ flow from SR lumen to cytosol. This may suggest that, rather than directly blocking Ca2+ efflux, flecainide can reduce Ca2+ efflux by blocking counter currents through the pore which otherwise limit SR membrane potential change during systolic Ca2+ efflux. In summary, the antiarrhythmic effects of flecainide in CPVT seem to involve multiple components of EC coupling and multiple actions on RyR2. Their clarification may identify novel specific drug targets and facilitate flecainide's clinical utilization in CPVT.
Collapse
Affiliation(s)
| | - Christopher L.-H. Huang
- Department of Biochemistry, University of Cambridge, Cambridge, UK
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - James A. Fraser
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Angela F. Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Acton, Australia
| |
Collapse
|
6
|
Dulhunty AF, Fraser JA, Huang CLH, Salvage SC. Gating of RYR2 channels from the arrhythmic RYR2-P2328S mouse heart and some unexpected actions of flecainide. J Gen Physiol 2022. [PMID: 34767014 DOI: 10.1085/jgp.2021ecc42] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The P2328S mutation in mice is associated with arrhythmia and spontaneous diastolic calcium release in atrial and ventricular myocytes and there is a corresponding leftward shift in the Ca2+-activation curve for mutant RYR2 channels from homozygous mouse hearts (Salvage et al. 2019. J Cell Sci. https://doi.org/10.1242/jcs.229039). P2328 is located in helical domain 1 (HD1) of RYR2. Local structural changes likely result when structurally active proline residues are replaced by structurally inert serine residues. We speculate that local structural changes in HD1 lead to sequential intradomain and interdomain stearic changes through the protein to the distant channel gate, which favor the open pore conformation. The drug flecainide prevents arrhythmia in humans and mouse models of CPVT by blocking NaV1.5 and RYR2 channels. Conventionally, flecainide blocks RYR2 channels in a voltage-dependent manner. We did not observe voltage-dependent pore block. This was possibly because, in contrast to previous studies, the only channel modulators that we used to produce end-diastolic control channel activity were 1 µM cytoplasmic Ca2+ and 1 mM luminal Ca2+. We observed previously unreported, voltage-independent increases in WT and P2328S channel activity at low flecainide concentrations, followed by a decline in activity at higher concentrations. The increase in activity dominated the effect of flecainide on P2328S channels. These effects suggested high-affinity flecainide binding to an activation site and lower-affinity binding to an inhibition site, both distant from the channel pore (Salvage et al. 2021. Cells. https://doi.org/10.3390/cells10082101). Unlike channel block by flecainide, the drug under our conditions stabilized intrinsic sub-conductance activity at +40 mV and -40 mV. Since flecainide effectively reduces CPVT arrythmia clinically and in animal models, we conclude that voltage-independent inhibition and voltage-dependent channel block prevail under cellular conditions. However, channel activation is important to note as it may be unmasked in other circumstances such as acquired cardiac disorders, mutations, or additional drug applications.
Collapse
Affiliation(s)
- Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Acton, Australia
| | - James A Fraser
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Cambridge, UK.,Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Samantha C Salvage
- Physiological Laboratory, University of Cambridge, Cambridge, UK.,Department of Biochemistry, University of Cambridge, Cambridge, UK
| |
Collapse
|
7
|
Shishmarev D, Rowland E, Aditya S, Sundararaj S, Oakley AJ, Dulhunty AF, Casarotto MG. Molecular interactions of
STAC
proteins with skeletal muscle dihydropyridine receptor and excitation‐contraction coupling. Protein Sci 2022; 31:e4311. [PMID: 35481653 PMCID: PMC9019556 DOI: 10.1002/pro.4311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 03/20/2022] [Accepted: 04/01/2022] [Indexed: 01/06/2023]
Abstract
Excitation‐contraction coupling (ECC) is the physiological process in which an electrical signal originating from the central nervous system is converted into muscle contraction. In skeletal muscle tissue, the key step in the molecular mechanism of ECC initiated by the muscle action potential is the cooperation between two Ca2+ channels, dihydropyridine receptor (DHPR; voltage‐dependent L‐type calcium channel) and ryanodine receptor 1 (RyR1). These two channels were originally postulated to communicate with each other via direct mechanical interactions; however, the molecular details of this cooperation have remained ambiguous. Recently, it has been proposed that one or more supporting proteins are in fact required for communication of DHPR with RyR1 during the ECC process. One such protein that is increasingly believed to play a role in this interaction is the SH3 and cysteine‐rich domain‐containing protein 3 (STAC3), which has been proposed to bind a cytosolic portion of the DHPR α1S subunit known as the II–III loop. In this work, we present direct evidence for an interaction between a small peptide sequence of the II–III loop and several residues within the SH3 domains of STAC3 as well as the neuronal isoform STAC2. Differences in this interaction between STAC3 and STAC2 suggest that STAC3 possesses distinct biophysical features that are potentially important for its physiological interactions with the II–III loop. Therefore, this work demonstrates an isoform‐specific interaction between STAC3 and the II–III loop of DHPR and provides novel insights into a putative molecular mechanism behind this association in the skeletal muscle ECC process.
Collapse
Affiliation(s)
- Dmitry Shishmarev
- John Curtin School of Medical Research Australian National University Canberra Australia
- Research School of Biology Australian National University Canberra Australia
| | - Emily Rowland
- John Curtin School of Medical Research Australian National University Canberra Australia
- Division of Structural Biology, Wellcome Centre for Human Genetics University of Oxford Oxford UK
| | - Shouvik Aditya
- John Curtin School of Medical Research Australian National University Canberra Australia
- Research School of Biology Australian National University Canberra Australia
| | - Srinivasan Sundararaj
- John Curtin School of Medical Research Australian National University Canberra Australia
| | - Aaron J. Oakley
- School of Chemistry & Molecular Bioscience and Molecular Horizons University of Wollongong Wollongong Australia
| | - Angela F. Dulhunty
- John Curtin School of Medical Research Australian National University Canberra Australia
| | - Marco G. Casarotto
- Research School of Biology Australian National University Canberra Australia
| |
Collapse
|
8
|
Dulhunty AF. Molecular Changes in the Cardiac RyR2 With Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT). Front Physiol 2022; 13:830367. [PMID: 35222090 PMCID: PMC8867003 DOI: 10.3389/fphys.2022.830367] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/07/2022] [Indexed: 11/13/2022] Open
Abstract
The cardiac ryanodine receptor Ca2+ release channel (RyR2) is inserted into the membrane of intracellular sarcoplasmic reticulum (SR) myocyte Ca2+ stores, where it releases the Ca2+ essential for contraction. Mutations in proteins involved in Ca2+ signaling can lead to catecholaminergic polymorphic ventricular tachycardia (CPVT). The most common cellular phenotype in CPVT is higher than normal cytoplasmic Ca2+ concentrations during diastole due to Ca2+ leak from the SR through mutant RyR2. Arrhythmias are triggered when the surface membrane sodium calcium exchanger (NCX) lowers cytoplasmic Ca2+ by importing 3 Na+ ions to extrude one Ca2+ ion. The Na+ influx leads to delayed after depolarizations (DADs) which trigger arrhythmia when reaching action potential threshold. Present therapies use drugs developed for different purposes that serendipitously reduce RyR2 Ca2+ leak, but can adversely effect systolic Ca2+ release and other target processes. Ideal drugs would specifically reverse the effect of individual mutations, without altering normal channel function. Such drugs will depend on the location of the mutation in the 4967-residue monomer and the effect of the mutation on local structure, and downstream effects on structures along the conformational pathway to the pore. Such atomic resolution information is only now becoming available. This perspective provides a summary of known or predicted structural changes associated with a handful of CPVT mutations. Known molecular changes associated with RyR opening are discussed, as well one study where minute molecular changes with a particular mutation have been tracked from the N-terminal mutation site to gating residues in the channel pore.
Collapse
|
9
|
Salvage SC, Gallant EM, Fraser JA, Huang CLH, Dulhunty AF. Flecainide Paradoxically Activates Cardiac Ryanodine Receptor Channels under Low Activity Conditions: A Potential Pro-Arrhythmic Action. Cells 2021; 10:cells10082101. [PMID: 34440870 PMCID: PMC8394964 DOI: 10.3390/cells10082101] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 08/07/2021] [Accepted: 08/10/2021] [Indexed: 12/02/2022] Open
Abstract
Cardiac ryanodine receptor (RyR2) mutations are implicated in the potentially fatal catecholaminergic polymorphic ventricular tachycardia (CPVT) and in atrial fibrillation. CPVT has been successfully treated with flecainide monotherapy, with occasional notable exceptions. Reported actions of flecainide on cardiac sodium currents from mice carrying the pro-arrhythmic homozygotic RyR2-P2328S mutation prompted our explorations of the effects of flecainide on their RyR2 channels. Lipid bilayer electrophysiology techniques demonstrated a novel, paradoxical increase in RyR2 activity. Preceding flecainide exposure, channels were mildly activated by 1 mM luminal Ca2+ and 1 µM cytoplasmic Ca2+, with open probabilities (Po) of 0.03 ± 0.01 (wild type, WT) or 0.096 ± 0.024 (P2328S). Open probability (Po) increased within 0.5 to 3 min of exposure to 0.5 to 5.0 µM cytoplasmic flecainide, then declined with higher concentrations of flecainide. There were no such increases in a subset of high Po channels with Po ≥ 0.08, although Po then declined with ≥5 µM (WT) or ≥50 µM flecainide (P2328S). On average, channels with Po < 0.08 were significantly activated by 0.5 to 10 µM of flecainide (WT) or 0.5 to 50 µM of flecainide (P2328S). These results suggest that flecainide can bind to separate activation and inhibition sites on RyR2, with activation dominating in lower activity channels and inhibition dominating in more active channels.
Collapse
Affiliation(s)
- Samantha C. Salvage
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK; (S.C.S.); (J.A.F.); (C.L.-H.H.)
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Esther M. Gallant
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Acton 2601, Australia;
| | - James A. Fraser
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK; (S.C.S.); (J.A.F.); (C.L.-H.H.)
| | - Christopher L.-H. Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK; (S.C.S.); (J.A.F.); (C.L.-H.H.)
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Angela F. Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Acton 2601, Australia;
- Correspondence:
| |
Collapse
|
10
|
Robinson K, Culley D, Waring S, Lamb GD, Easton C, Casarotto MG, Dulhunty AF. Peptide mimetic compounds can activate or inhibit cardiac and skeletal ryanodine receptors. Life Sci 2020; 260:118234. [PMID: 32791148 DOI: 10.1016/j.lfs.2020.118234] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/22/2020] [Accepted: 08/05/2020] [Indexed: 12/18/2022]
Abstract
AIMS Our aim was to characterise the actions of novel BIT compounds with structures based on peptides and toxins that bind to significant regulatory sites on ryanodine receptor (RyR) Ca2+ release channels. RyRs, located in sarcoplasmic reticulum (SR) Ca2+ store membranes of striated muscle, are essential for muscle contraction. Although severe sometimes-deadly myopathies occur when the channels become hyperactive following genetic or acquired changes, specific inhibitors of RyRs are rare. MAIN METHODS The effect of BIT compounds was determined by spectrophotometric analysis of Ca2+ release from isolated SR vesicles, analysis of single RyR channel activity in artificial lipid bilayers and contraction of intact and skinned skeletal muscle fibres. KEY FINDINGS The inhibitory compounds reduced: (a) Ca2+ release from SR vesicles with IC50s of 1.1-2.5 μM, competing with activation by parent peptides and toxins; (b) single RyR ion channel activity with IC50s of 0.5-1.5 μM; (c) skinned fibre contraction. In contrast, activating BIT compounds increased Ca2+ release with an IC50 of 5.0 μM and channel activity with AC50s of 2 to 12 nM and enhanced skinned fibre contraction. Sub-conductance activity dominated channel activity with both inhibitors and activators. Effects of all compounds on skeletal and cardiac RyRs were similar and reversible. Competition experiments suggest that the BIT compounds bind to the regulatory helical domains of the RyRs that impact on channel gating mechanisms through long-range allosteric interactions. SIGNIFICANCE The BIT compounds are strong modulators of RyR activity and provide structural templates for novel research tools and drugs to combat muscle disease.
Collapse
Affiliation(s)
- Ken Robinson
- Research School of Chemistry, Australian National University, Canberra, Australia
| | - Dane Culley
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Sam Waring
- Research School of Chemistry, Australian National University, Canberra, Australia
| | - Graham D Lamb
- Physiology, Anatomy and Microbiology, Biochemistry and Microbiology, La Trobe University, Melbourne, VIC, Australia
| | - Christopher Easton
- Research School of Chemistry, Australian National University, Canberra, Australia
| | - Marco G Casarotto
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, Australia.
| |
Collapse
|
11
|
Salvage SC, Gallant EM, Beard NA, Ahmad S, Valli H, Fraser JA, Huang CLH, Dulhunty AF. Ion channel gating in cardiac ryanodine receptors from the arrhythmic RyR2-P2328S mouse. J Cell Sci 2019; 132:jcs.229039. [PMID: 31028179 PMCID: PMC6550012 DOI: 10.1242/jcs.229039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 04/16/2019] [Indexed: 12/20/2022] Open
Abstract
Mutations in the cardiac ryanodine receptor Ca2+ release channel (RyR2) can cause deadly ventricular arrhythmias and atrial fibrillation (AF). The RyR2-P2328S mutation produces catecholaminergic polymorphic ventricular tachycardia (CPVT) and AF in hearts from homozygous RyR2P2328S/P2328S (denoted RyR2S/S) mice. We have now examined P2328S RyR2 channels from RyR2S/S hearts. The activity of wild-type (WT) and P2328S RyR2 channels was similar at a cytoplasmic [Ca2+] of 1 mM, but P2328S RyR2 was significantly more active than WT at a cytoplasmic [Ca2+] of 1 µM. This was associated with a >10-fold shift in the half maximal activation concentration (AC50) for Ca2+ activation, from ∼3.5 µM Ca2+ in WT RyR2 to ∼320 nM in P2328S channels and an unexpected >1000-fold shift in the half maximal inhibitory concentration (IC50) for inactivation from ∼50 mM in WT channels to ≤7 μM in P2328S channels, which is into systolic [Ca2+] levels. Unexpectedly, the shift in Ca2+ activation was not associated with changes in sub-conductance activity, S2806 or S2814 phosphorylation or the level of FKBP12 (also known as FKBP1A) bound to the channels. The changes in channel activity seen with the P2328S mutation correlate with altered Ca2+ homeostasis in myocytes from RyR2S/S mice and the CPVT and AF phenotypes.This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
- Samantha C Salvage
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK.,Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Esther M Gallant
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Acton ACT 2601, Australia
| | - Nicole A Beard
- Centre for Research in Therapeutic Solutions, Faculty of Science and Technology, University of Canberra, Bruce, ACT 2617, Australia
| | - Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Haseeb Valli
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - James A Fraser
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK.,Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Angela F Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Acton ACT 2601, Australia
| |
Collapse
|
12
|
Chakraborty AD, Gonano LA, Munro ML, Smith LJ, Thekkedam C, Staudacher V, Gamble AB, Macquaide N, Dulhunty AF, Jones PP. Activation of RyR2 by class I kinase inhibitors. Br J Pharmacol 2019; 176:773-786. [PMID: 30588601 DOI: 10.1111/bph.14562] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 11/26/2018] [Accepted: 12/09/2018] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Kinase inhibitors are a common treatment for cancer. Class I kinase inhibitors that target the ATP-binding pocket are particularly prevalent. Many of these compounds are cardiotoxic and can cause arrhythmias. Spontaneous release of Ca2+ via cardiac ryanodine receptors (RyR2), through a process termed store overload-induced Ca2+ release (SOICR), is a common mechanism underlying arrhythmia. We explored whether class I kinase inhibitors could modify the activity of RyR2 and trigger SOICR to determine if this contributes to the cardiotoxic nature of these compounds. EXPERIMENTAL APPROACH The impact of class I and II kinase inhibitors on SOICR was studied in HEK293 cells and ventricular myocytes using single-cell Ca2+ imaging. A specific effect on RyR2 was confirmed using single channel recordings. Ventricular myocytes were also used to determine if drug-induced changes in SOICR could be reversed using anti-SOICR agents. KEY RESULTS Class I kinase inhibitors increased the propensity of SOICR. Single channel recording showed that this was due to a specific effect on RyR2. Class II kinase inhibitors decreased the activity of RyR2 at the single channel level but had little effect on SOICR. The promotion of SOICR mediated by class I kinase inhibitors could be reversed using the anti-SOICR agent VK-II-86. CONCLUSIONS AND IMPLICATIONS Part of the cardiotoxicity of class I kinase inhibitors can be assigned to their effect on RyR2 and increase in SOICR. Compounds with anti-SOICR activity may represent an improved treatment option for patients.
Collapse
Affiliation(s)
- A D Chakraborty
- Department of Physiology, School of Biomedical Sciences, and HeartOtago, University of Otago, Dunedin, New Zealand
| | - L A Gonano
- Department of Physiology, School of Biomedical Sciences, and HeartOtago, University of Otago, Dunedin, New Zealand.,Centro de Investigaciones Cardiovasculares, CONICET La Plata, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - M L Munro
- Department of Physiology, School of Biomedical Sciences, and HeartOtago, University of Otago, Dunedin, New Zealand
| | - L J Smith
- Department of Physiology, School of Biomedical Sciences, and HeartOtago, University of Otago, Dunedin, New Zealand
| | - C Thekkedam
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - V Staudacher
- School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - A B Gamble
- School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - N Macquaide
- Institute of Cardiovascular and Medical Sciences and School of Life Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, UK
| | - A F Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - P P Jones
- Department of Physiology, School of Biomedical Sciences, and HeartOtago, University of Otago, Dunedin, New Zealand
| |
Collapse
|
13
|
Abstract
The ryanodine receptor calcium release channel is central to cytoplasmic Ca
2+ signalling in skeletal muscle, the heart, and many other tissues, including the central nervous system, lymphocytes, stomach, kidney, adrenal glands, ovaries, testes, thymus, and lungs. The ion channel protein is massive (more than 2.2 MDa) and has a structure that has defied detailed determination until recent developments in cryo-electron microscopy revealed much of its structure at near-atomic resolution. The availability of this high-resolution structure has provided the most significant advances in understanding the function of the ion channel in the past 30 years. We can now visualise the molecular environment of individual amino acid residues that form binding sites for essential modulators of ion channel function and determine its role in Ca
2+ signalling. Importantly, the structure has revealed the structural environment of the many deletions and point mutations that disrupt Ca
2+ signalling in skeletal and cardiac myopathies and neuropathies. The implications are of vital importance to our understanding of the molecular basis of the ion channel’s function and for the design of therapies to counteract the effects of ryanodine receptor-associated disorders.
Collapse
Affiliation(s)
- Angela F Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, 131 Garran Road, The Australian National University, Acton, ACT, 2601, Australia
| | - Nicole A Beard
- Centre for Research in Therapeutic Solutions, Faculty of Science and Technology, University of Canberra, Bruce, ACT, 2617, Australia
| | - Marco G Casarotto
- Department of Cancer Biology and Therapeutics, John Curtin School of Medical Research, 131 Garran Road, The Australian National University, Acton, ACT, 2601, Australia
| |
Collapse
|
14
|
Robinson K, Easton CJ, Dulhunty AF, Casarotto MG. Exploiting Peptidomimetics to Synthesize Compounds That Activate Ryanodine Receptor Calcium Release Channels. ChemMedChem 2018; 13:1957-1971. [DOI: 10.1002/cmdc.201800366] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 07/24/2018] [Indexed: 11/11/2022]
Affiliation(s)
- Ken Robinson
- Research School of Chemistry Australian National University Canberra Australia
| | | | - Angela F. Dulhunty
- John Curtin School of Medical Research Australian National University Canberra Australia
| | - Marco G. Casarotto
- John Curtin School of Medical Research Australian National University Canberra Australia
| |
Collapse
|
15
|
Denniss A, Dulhunty AF, Beard NA. Ryanodine receptor Ca 2+ release channel post-translational modification: Central player in cardiac and skeletal muscle disease. Int J Biochem Cell Biol 2018; 101:49-53. [PMID: 29775742 DOI: 10.1016/j.biocel.2018.05.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 05/10/2018] [Accepted: 05/13/2018] [Indexed: 12/21/2022]
Abstract
Calcium release from internal stores is a quintessential event in excitation-contraction coupling in cardiac and skeletal muscle. The ryanodine receptor Ca2+ release channel is embedded in the internal sarcoplasmic reticulum Ca2+ store, which releases Ca2+ into the cytoplasm, enabling contraction. Ryanodine receptors form the hub of a macromolecular complex extending from the extracellular space to the sarcoplasmic reticulum lumen. Ryanodine receptor activity is influenced by the integrated effects of associated co-proteins, ions, and post-translational phosphor and redox modifications. In healthy muscle, ryanodine receptors are phosphorylated and redox modified to basal levels, to support cellular function. A pathological increase in the degree of both post-translational modifications disturbs intracellular Ca2+ signalling, and is implicated in various cardiac and skeletal disorders. This review summarises our current understanding of the mechanisms linking ryanodine receptor post-translational modification to heart failure and skeletal myopathy and highlights the challenges and controversies within the field.
Collapse
Affiliation(s)
- Amanda Denniss
- Health Research Institute, Faculty of Science and Technology, University of Canberra, Bruce, ACT, Australia
| | - Angela F Dulhunty
- John Curtin School of Medical Research, The Australian National University, Acton, ACT, Australia
| | - Nicole A Beard
- Health Research Institute, Faculty of Science and Technology, University of Canberra, Bruce, ACT, Australia.
| |
Collapse
|
16
|
Salvage SC, Chandrasekharan KH, Jeevaratnam K, Dulhunty AF, Thompson AJ, Jackson AP, Huang CL. Multiple targets for flecainide action: implications for cardiac arrhythmogenesis. Br J Pharmacol 2018; 175:1260-1278. [PMID: 28369767 PMCID: PMC5866987 DOI: 10.1111/bph.13807] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 03/27/2017] [Accepted: 03/29/2017] [Indexed: 12/19/2022] Open
Abstract
Flecainide suppresses cardiac tachyarrhythmias including paroxysmal atrial fibrillation, supraventricular tachycardia and arrhythmic long QT syndromes (LQTS), as well as the Ca2+ -mediated, catecholaminergic polymorphic ventricular tachycardia (CPVT). However, flecainide can also exert pro-arrhythmic effects most notably following myocardial infarction and when used to diagnose Brugada syndrome (BrS). These divergent actions result from its physiological and pharmacological actions at multiple, interacting levels of cellular organization. These were studied in murine genetic models with modified Nav channel or intracellular ryanodine receptor (RyR2)-Ca2+ channel function. Flecainide accesses its transmembrane Nav 1.5 channel binding site during activated, open, states producing a use-dependent antagonism. Closing either activation or inactivation gates traps flecainide within the pore. An early peak INa related to activation of Nav channels followed by rapid de-activation, drives action potential (AP) upstrokes and their propagation. This is diminished in pro-arrhythmic conditions reflecting loss of function of Nav 1.5 channels, such as BrS, accordingly exacerbated by flecainide challenge. Contrastingly, pro-arrhythmic effects attributed to prolonged AP recovery by abnormal late INaL following gain-of-function modifications of Nav 1.5 channels in LQTS3 are reduced by flecainide. Anti-arrhythmic effects of flecainide that reduce triggering in CPVT models mediated by sarcoplasmic reticular Ca2+ release could arise from its primary actions on Nav channels indirectly decreasing [Ca2+ ]i through a reduced [Na+ ]i and/or direct open-state RyR2-Ca2+ channel antagonism. The consequent [Ca2+ ]i alterations could also modify AP propagation velocity and therefore arrhythmic substrate through its actions on Nav 1.5 channel function. This is consistent with the paradoxical differences between flecainide actions upon Na+ currents, AP conduction and arrhythmogenesis under circumstances of normal and increased RyR2 function. LINKED ARTICLES This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.
Collapse
Affiliation(s)
- Samantha C Salvage
- Department of BiochemistryUniversity of CambridgeCambridgeUK
- Physiological LaboratoryUniversity of CambridgeCambridgeUK
| | | | - Kamalan Jeevaratnam
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordUK
- School of MedicinePerdana University – Royal College of Surgeons IrelandSerdangSelangor Darul EhsanMalaysia
| | - Angela F Dulhunty
- Muscle Research Group, Eccles Institute of Neuroscience, John Curtin School of Medical ResearchAustralian National UniversityActonAustralia
| | | | | | - Christopher L‐H Huang
- Department of BiochemistryUniversity of CambridgeCambridgeUK
- Physiological LaboratoryUniversity of CambridgeCambridgeUK
| |
Collapse
|
17
|
Perez CF, Eltit JM, Lopez JR, Bodnár D, Dulhunty AF, Aditya S, Casarotto MG. Functional and structural characterization of a novel malignant hyperthermia-susceptible variant of DHPR-β 1a subunit (CACNB1). Am J Physiol Cell Physiol 2017; 314:C323-C333. [PMID: 29212769 DOI: 10.1152/ajpcell.00187.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Malignant hyperthermia (MH) susceptibility has been recently linked to a novel variant of β1a subunit of the dihydropyridine receptor (DHPR), a channel essential for Ca2+ regulation in skeletal muscle. Here we evaluate the effect of the mutant variant V156A on the structure/function of DHPR β1a subunit and assess its role on Ca2+ metabolism of cultured myotubes. Using differential scanning fluorimetry, we show that mutation V156A causes a significant reduction in thermal stability of the Src homology 3/guanylate kinase core domain of β1a subunit. Expression of the variant subunit in β1-null mouse myotubes resulted in increased sensitivity to caffeine stimulation. Whole cell patch-clamp analysis of β1a-V156A-expressing myotubes revealed a -2 mV shift in voltage dependence of channel activation, but no changes in Ca2+ conductance, current kinetics, or sarcoplasmic reticulum Ca2+ load were observed. Measurement of resting free Ca2+ and Na+ concentrations shows that both cations were significantly elevated in β1a-V156A-expressing myotubes and that these changes were linked to increased rates of plasmalemmal Ca2+ entry through Na+/Ca2+ exchanger and/or transient receptor potential canonical channels. Overall, our data show that mutant variant V156A results in instability of protein subdomains of β1a subunit leading to a phenotype of Ca2+ dysregulation that partly resembles that of other MH-linked mutations of DHPR α1S subunit. These data prove that homozygous expression of variant β1a-V156A has the potential to be a pathological variant, although it may require other gene defects to cause a full MH phenotype.
Collapse
Affiliation(s)
- Claudio F Perez
- Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Jose M Eltit
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University , Richmond, Virginia
| | - Jose R Lopez
- Department of Molecular Biosciences, University of California , Davis, California
| | - Dóra Bodnár
- Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University , Canberra , Australia
| | - Shouvik Aditya
- John Curtin School of Medical Research, Australian National University , Canberra , Australia
| | - Marco G Casarotto
- John Curtin School of Medical Research, Australian National University , Canberra , Australia
| |
Collapse
|
18
|
Richardson SJ, Steele GA, Gallant EM, Lam A, Schwartz CE, Board PG, Casarotto MG, Beard NA, Dulhunty AF. Publisher's Note: Association of FK506 binding proteins with RyR channels - effect of CLIC2 binding on sub-conductance opening and FKBP binding. J. Cell Sci. doi: 10.1242/jcs.204461. J Cell Sci 2017:jcs.211243. [PMID: 28982713 DOI: 10.1242/jcs.211243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
19
|
Hanna AD, Lam A, Thekkedam C, Willemse H, Dulhunty AF, Beard NA. The Anthracycline Metabolite Doxorubicinol Abolishes RyR2 Sensitivity to Physiological Changes in Luminal Ca2+ through an Interaction with Calsequestrin. Mol Pharmacol 2017; 92:576-587. [DOI: 10.1124/mol.117.108183] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 09/07/2017] [Indexed: 12/31/2022] Open
|
20
|
Dulhunty AF, Wei-LaPierre L, Casarotto MG, Beard NA. Core skeletal muscle ryanodine receptor calcium release complex. Clin Exp Pharmacol Physiol 2017; 44:3-12. [PMID: 27696487 DOI: 10.1111/1440-1681.12676] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Revised: 09/27/2016] [Accepted: 09/27/2016] [Indexed: 12/15/2022]
Abstract
The core skeletal muscle ryanodine receptor (RyR1) calcium release complex extends through three compartments of the muscle fibre, linking the extracellular environment through the cytoplasmic junctional gap to the lumen of the internal sarcoplasmic reticulum (SR) calcium store. The protein complex is essential for skeletal excitation-contraction (EC)-coupling and skeletal muscle function. Its importance is highlighted by perinatal death if any one of the EC-coupling components are missing and by myopathies associated with mutation of any of the proteins. The proteins essential for EC-coupling include the DHPR α1S subunit in the transverse tubule membrane, the DHPR β1a subunit in the cytosol and the RyR1 ion channel in the SR membrane. The other core proteins are triadin and junctin and calsequestrin, associated mainly with SR. These SR proteins are not essential for survival but exert structural and functional influences that modify the gain of EC-coupling and maintain normal muscle function. This review summarises our current knowledge of the individual protein/protein interactions within the core complex and their overall contribution to EC-coupling. We highlight significant areas that provide a continuing challenge for the field. Additional important components of the Ca2+ release complex, such as FKBP12, calmodulin, S100A1 and Stac3 are identified and reviewed elsewhere.
Collapse
Affiliation(s)
- Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Lan Wei-LaPierre
- Department of Physiology and Pharmacology, University of Rochester Medical Center, Rochester, NY, USA
| | - Marco G Casarotto
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Nicole A Beard
- Health Research Institute, University of Canberra, Canberra, ACT, Australia
| |
Collapse
|
21
|
Richardson SJ, Steele GA, Gallant EM, Lam A, Schwartz CE, Board PG, Casarotto MG, Beard NA, Dulhunty AF. Association of FK506 binding proteins with RyR channels - effect of CLIC2 binding on sub-conductance opening and FKBP binding. J Cell Sci 2017; 130:3588-3600. [PMID: 28851804 DOI: 10.1242/jcs.204461] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/31/2017] [Indexed: 12/22/2022] Open
Abstract
Ryanodine receptor (RyR) Ca2+ channels are central to striated muscle function and influence signalling in neurons and other cell types. Beneficially low RyR activity and maximum conductance opening may be stabilised when RyRs bind to FK506 binding proteins (FKBPs) and destabilised by FKBP dissociation, with submaximal opening during RyR hyperactivity associated with myopathies and neurological disorders. However, the correlation with submaximal opening is debated and quantitative evidence is lacking. Here, we have measured altered FKBP binding to RyRs and submaximal activity with addition of wild-type (WT) CLIC2, an inhibitory RyR ligand, or its H101Q mutant that hyperactivates RyRs, which probably causes cardiac and intellectual abnormalities. The proportion of sub-conductance opening increases with WT and H101Q CLIC2 and is correlated with reduced FKBP-RyR association. The sub-conductance opening reduces RyR currents in the presence of WT CLIC2. In contrast, sub-conductance openings contribute to excess RyR 'leak' with H101Q CLIC2. There are significant FKBP and RyR isoform-specific actions of CLIC2, rapamycin and FK506 on FKBP-RyR association. The results show that FKBPs do influence RyR gating and would contribute to excess Ca2+ release in this CLIC2 RyR channelopathy.
Collapse
Affiliation(s)
- Spencer J Richardson
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, PO Box 334, ACT 2601, Australia
| | - Gregory A Steele
- Capital Pathology Laboratory, 70 Kent St, Deakin, ACT 2600, Australia
| | - Esther M Gallant
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, PO Box 334, ACT 2601, Australia
| | - Alexander Lam
- Neurosurgery, Royal Perth Hospital, 197 Wellington St, Perth, WA 6000, Australia
| | - Charles E Schwartz
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Philip G Board
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, PO Box 334, ACT 2601, Australia
| | - Marco G Casarotto
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, PO Box 334, ACT 2601, Australia
| | - Nicole A Beard
- Cardiac Physiology Department, Health Research Institute, Faculty of Education Science and Mathematics, University of Canberra, Bruce, ACT 2617, Australia
| | - Angela F Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, PO Box 334, ACT 2601, Australia
| |
Collapse
|
22
|
Norris NC, Joseph S, Aditya S, Karunasekara Y, Board PG, Dulhunty AF, Oakley AJ, Casarotto MG. Structural and biophysical analyses of the skeletal dihydropyridine receptor β subunit β 1a reveal critical roles of domain interactions for stability. J Biol Chem 2017; 292:8401-8411. [PMID: 28351836 DOI: 10.1074/jbc.m116.763896] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 03/16/2017] [Indexed: 01/02/2023] Open
Abstract
Excitation-contraction (EC) coupling in skeletal muscle requires a physical interaction between the voltage-gated calcium channel dihydropyridine receptor (DHPR) and the ryanodine receptor Ca2+ release channel. Although the exact molecular mechanism that initiates skeletal EC coupling is unresolved, it is clear that both the α1 and β subunits of DHPR are essential for this process. Here, we employed a series of techniques, including size-exclusion chromatography-multi-angle light scattering, differential scanning fluorimetry, and isothermal calorimetry, to characterize various biophysical properties of the skeletal DHPR β subunit β1a Removal of the intrinsically disordered N and C termini and the hook region of β1a prevented oligomerization, allowing for its structural determination by X-ray crystallography. The structure had a topology similar to that of previously determined β isoforms, which consist of SH3 and guanylate kinase domains. However, transition melting temperatures derived from the differential scanning fluorimetry experiments indicated a significant difference in stability of ∼2-3 °C between the β1a and β2a constructs, and the addition of the DHPR α1s I-II loop (α-interaction domain) peptide stabilized both β isoforms by ∼6-8 °C. Similar to other β isoforms, β1a bound with nanomolar affinity to the α-interaction domain, but binding affinities were influenced by amino acid substitutions in the adjacent SH3 domain. These results suggest that intramolecular interactions between the SH3 and guanylate kinase domains play a role in the stability of β1a while also providing a conduit for allosteric signaling events.
Collapse
Affiliation(s)
- Nicole C Norris
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Soumya Joseph
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Shouvik Aditya
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Yamuna Karunasekara
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Philip G Board
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Aaron J Oakley
- Department of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Marco G Casarotto
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory 2601, Australia.
| |
Collapse
|
23
|
Walweel K, Molenaar P, Imtiaz MS, Denniss A, Dos Remedios C, van Helden DF, Dulhunty AF, Laver DR, Beard NA. Ryanodine receptor modification and regulation by intracellular Ca 2+ and Mg 2+ in healthy and failing human hearts. J Mol Cell Cardiol 2017; 104:53-62. [PMID: 28131631 DOI: 10.1016/j.yjmcc.2017.01.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 01/01/2017] [Accepted: 01/24/2017] [Indexed: 11/30/2022]
Abstract
RATIONALE Heart failure is a multimodal disorder, of which disrupted Ca2+ homeostasis is a hallmark. Central to Ca2+ homeostasis is the major cardiac Ca2+ release channel - the ryanodine receptor (RyR2) - whose activity is influenced by associated proteins, covalent modification and by Ca2+ and Mg2+. That RyR2 is remodelled and its function disturbed in heart failure is well recognized, but poorly understood. OBJECTIVE To assess Ca2+ and Mg2+ regulation of RyR2 from left ventricles of healthy, cystic fibrosis and failing hearts, and to correlate these functional changes with RyR2 modifications and remodelling. METHODS AND RESULTS The function of RyR2 from left ventricular samples was assessed using lipid bilayer single-channel measurements, whilst RyR2 modification and protein:protein interactions were determined using Western Blots and co-immunoprecipitation. In all failing hearts there was an increase in RyR2 activity at end-diastolic cytoplasmic Ca2+ (100nM), a decreased cytoplasmic [Ca2+] required for half maximal activation (Ka) and a decrease in inhibition by cytoplasmic Mg2+. This was accompanied by significant hyperphosphorylation of RyR2 S2808 and S2814, reduced free thiol content and a reduced interaction with FKBP12.0 and FKBP12.6. Either dephosphorylation of RyR2 using PP1 or thiol reduction using DTT eliminated any significant difference in the activity of RyR2 from healthy and failing hearts. We also report a subgroup of RyR2 in failing hearts that were not responsive to regulation by intracellular Ca2+ or Mg2+. CONCLUSION Despite different aetiologies, disrupted RyR2 Ca2+ sensitivity and biochemical modification of the channel are common constituents of failing heart RyR2 and may underlie the pathological disturbances in intracellular Ca2+ signalling.
Collapse
Affiliation(s)
- K Walweel
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia
| | - P Molenaar
- Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, 4000, Northside Clinical School, School of Clinical Medicine, University of Queensland and Critical Care Research Group, The Prince Charles Hospital, Chermside, QLD, 4032, Australia
| | - M S Imtiaz
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
| | - A Denniss
- Health Research Institute, Faculty of Education Science and Mathematics, University of Canberra, Bruce, ACT 2617, Australia
| | - C Dos Remedios
- Bosch Institute, Discipline of Anatomy, University of Sydney, Sydney, New South Wales 2006, Australia
| | - D F van Helden
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia
| | - A F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, 0200, Australia
| | - D R Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia
| | - N A Beard
- Health Research Institute, Faculty of Education Science and Mathematics, University of Canberra, Bruce, ACT 2617, Australia; John Curtin School of Medical Research, Australian National University, Canberra, ACT, 0200, Australia.
| |
Collapse
|
24
|
Dulhunty AF, Board PG, Beard NA, Casarotto MG. Physiology and Pharmacology of Ryanodine Receptor Calcium Release Channels. Advances in Pharmacology 2017; 79:287-324. [DOI: 10.1016/bs.apha.2016.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
25
|
Hanna AD, Lam A, Thekkedam C, Gallant EM, Beard NA, Dulhunty AF. Correction: Cardiac ryanodine receptor activation by a high Ca2+ store load is reversed in a reducing cytoplasmic redox environment. J Cell Sci 2016; 129:4317. [PMID: 27852829 PMCID: PMC5117203 DOI: 10.1242/jcs.198705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
26
|
Hewawasam RP, Liu D, Casarotto MG, Board PG, Dulhunty AF. The GSTM2 C-Terminal Domain Depresses Contractility and Ca2+ Transients in Neonatal Rat Ventricular Cardiomyocytes. PLoS One 2016; 11:e0162415. [PMID: 27612301 PMCID: PMC5017731 DOI: 10.1371/journal.pone.0162415] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 08/22/2016] [Indexed: 11/25/2022] Open
Abstract
The cardiac ryanodine receptor (RyR2) is an intracellular ion channel that regulates Ca2+ release from the sarcoplasmic reticulum (SR) during excitation–contraction coupling in the heart. The glutathione transferases (GSTs) are a family of phase II detoxification enzymes with additional functions including the selective inhibition of RyR2, with therapeutic implications. The C-terminal half of GSTM2 (GSTM2C) is essential for RyR2 inhibition, and mutations F157A and Y160A within GSTM2C prevent the inhibitory action. Our objective in this investigation was to determine whether GSTM2C can enter cultured rat neonatal ventricular cardiomyocytes and influence contractility. We show that oregon green-tagged GSTM2C (at 1 μM) is internalized into the myocytes and it reduces spontaneous contraction frequency and myocyte shortening. Field stimulation of myocytes evoked contraction in the same percentage of myocytes treated either with media alone or media plus 15 μM GSTM2C. Myocyte shortening during contraction was significantly reduced by exposure to 15 μM GSTM2C, but not 5 and 10 μM GSTM2C and was unaffected by exposure to 15 μM of the mutants Y160A or F157A. The amplitude of the Ca2+ transient in the 15 μM GSTM2C - treated myocytes was significantly decreased, the rise time was significantly longer and the decay time was significantly shorter than in control myocytes. The Ca2+ transient was not altered by exposure to Y160A or F157A. The results are consistent with GSTM2C entering the myocytes and inhibiting RyR2, in a manner that indicates a possible therapeutic potential for treatment of arrhythmia in the neonatal heart.
Collapse
Affiliation(s)
- Ruwani P. Hewawasam
- John Curtin School of Medical Research, The Australian National University, GPO Box 334, Canberra City, ACT 2600, Australia
| | - Dan Liu
- John Curtin School of Medical Research, The Australian National University, GPO Box 334, Canberra City, ACT 2600, Australia
| | - Marco G. Casarotto
- John Curtin School of Medical Research, The Australian National University, GPO Box 334, Canberra City, ACT 2600, Australia
| | - Philip G. Board
- John Curtin School of Medical Research, The Australian National University, GPO Box 334, Canberra City, ACT 2600, Australia
| | - Angela F. Dulhunty
- John Curtin School of Medical Research, The Australian National University, GPO Box 334, Canberra City, ACT 2600, Australia
- * E-mail:
| |
Collapse
|
27
|
Willemse H, Theodoratos A, Smith PN, Dulhunty AF. Unexpected dependence of RyR1 splice variant expression in human lower limb muscles on fiber-type composition. Pflugers Arch 2015; 468:269-78. [PMID: 26438192 DOI: 10.1007/s00424-015-1738-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 09/14/2015] [Accepted: 09/29/2015] [Indexed: 10/23/2022]
Abstract
The skeletal muscle ryanodine receptor Ca(2+) release channel (RyR1), essential for excitation-contraction (EC) coupling, demonstrates a known developmentally regulated alternative splicing in the ASI region. We now find unexpectedly that the expression of the splice variants is closely related to fiber type in adult human lower limb muscles. We examined the distribution of myosin heavy chain isoforms and ASI splice variants in gluteus minimus, gluteus medius and vastus medialis from patients aged 45 to 85 years. There was a strong positive correlation between ASI(+)RyR1 and the percentage of type 2 fibers in the muscles (r = 0.725), and a correspondingly strong negative correlation between the percentages of ASI(+)RyR1 and percentage of type 1 fibers. When the type 2 fiber data were separated into type 2X and type 2A, the correlation with ASI(+)RyR1 was stronger in type 2X fibers (r = 0.781) than in type 2A fibers (r = 0.461). There was no significant correlation between age and either fiber-type composition or ASI(+)RyR1/ASI(-)RyR1 ratio. The results suggest that the reduced expression of ASI(-)RyR1 during development may reflect a reduction in type 1 fibers during development. Preferential expression of ASI(-) RyR1, having a higher gain of in Ca(2+) release during EC coupling than ASI(+)RyR1, may compensate for the reduced terminal cisternae volume, fewer junctional contacts and reduced charge movement in type 1 fibers.
Collapse
Affiliation(s)
- Hermia Willemse
- John Curtin School of Medical Research, Australian National University, Acton, ACT, 2600, Australia.
| | - Angelo Theodoratos
- John Curtin School of Medical Research, Australian National University, Acton, ACT, 2600, Australia.
| | - Paul N Smith
- Trauma and Orthopaedic Research Unit, Canberra Hospital, Building 6, Level 1, P.O. Box 11, Woden, ACT, 2606, Australia.
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Acton, ACT, 2600, Australia.
| |
Collapse
|
28
|
Samarasinghe K, Liu D, Tummala P, Cappello J, Pace SM, Arnolda L, Casarotto MG, Dulhunty AF, Board PG. Glutathione transferase M2 variants inhibit ryanodine receptor function in adult mouse cardiomyocytes. Biochem Pharmacol 2015; 97:269-80. [DOI: 10.1016/j.bcp.2015.08.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 08/03/2015] [Indexed: 11/16/2022]
|
29
|
Rebbeck RT, Willemse H, Groom L, Casarotto MG, Board PG, Beard NA, Dirksen RT, Dulhunty AF. Regions of ryanodine receptors that influence activation by the dihydropyridine receptor β1a subunit. Skelet Muscle 2015. [PMID: 26203350 PMCID: PMC4510890 DOI: 10.1186/s13395-015-0049-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Background Although excitation-contraction (EC) coupling in skeletal muscle relies on physical activation of the skeletal ryanodine receptor (RyR1) Ca2+ release channel by dihydropyridine receptors (DHPRs), the activation pathway between the DHPR and RyR1 remains unknown. However, the pathway includes the DHPR β1a subunit which is integral to EC coupling and activates RyR1. In this manuscript, we explore the isoform specificity of β1a activation of RyRs and the β1a binding site on RyR1. Methods We used lipid bilayers to measure single channel currents and whole cell patch clamp to measure L-type Ca2+ currents and Ca2+ transients in myotubes. Results We demonstrate that both skeletal RyR1 and cardiac RyR2 channels in phospholipid bilayers are activated by 10–100 nM of the β1a subunit. Activation of RyR2 by 10 nM β1a was less than that of RyR1, suggesting a reduced affinity of RyR2 for β1a. A reduction in activation was also observed when 10 nM β1a was added to the alternatively spliced (ASI(−)) isoform of RyR1, which lacks ASI residues (A3481-Q3485). It is notable that the equivalent region of RyR2 also lacks four of five ASI residues, suggesting that the absence of these residues may contribute to the reduced 10 nM β1a activation observed for both RyR2 and ASI(−)RyR1 compared to ASI(+)RyR1. We also investigated the influence of a polybasic motif (PBM) of RyR1 (K3495KKRRDGR3502) that is located immediately downstream from the ASI residues and has been implicated in EC coupling. We confirmed that neutralizing the basic residues in the PBM (RyR1 K-Q) results in an ~50 % reduction in Ca2+ transient amplitude following expression in RyR1-null (dyspedic) myotubes and that the PBM is also required for β1a subunit activation of RyR1 channels in lipid bilayers. These results suggest that the removal of β1a subunit interaction with the PBM in RyR1 could contribute directly to ~50 % of the Ca2+ release generated during skeletal EC coupling. Conclusions We conclude that the β1a subunit likely binds to a region that is largely conserved in RyR1 and RyR2 and that this region is influenced by the presence of the ASI residues and the PBM in RyR1. Electronic supplementary material The online version of this article (doi:10.1186/s13395-015-0049-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN USA
| | - Hermia Willemse
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital, PO Box 334, Canberra, ACT 2601 Australia
| | - Linda Groom
- Department of Physiology and Pharmacology, University of Rochester Medical Center, Rochester, NY USA
| | - Marco G Casarotto
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital, PO Box 334, Canberra, ACT 2601 Australia
| | - Philip G Board
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital, PO Box 334, Canberra, ACT 2601 Australia
| | - Nicole A Beard
- Discipline of Biomedical Sciences, Centre for Research in Therapeutic Solutions, University of Canberra, Canberra, ACT 2601 Australia
| | - Robert T Dirksen
- Department of Physiology and Pharmacology, University of Rochester Medical Center, Rochester, NY USA
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital, PO Box 334, Canberra, ACT 2601 Australia
| |
Collapse
|
30
|
Walweel K, Li J, Molenaar P, Imtiaz MS, Quail A, dos Remedios CG, Beard NA, Dulhunty AF, van Helden DF, Laver DR. Differences in the regulation of RyR2 from human, sheep, and rat by Ca²⁺ and Mg²⁺ in the cytoplasm and in the lumen of the sarcoplasmic reticulum. ACTA ACUST UNITED AC 2015; 144:263-71. [PMID: 25156119 PMCID: PMC4144672 DOI: 10.1085/jgp.201311157] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cardiac ryanodine receptors (RyR2) from humans, rats, and sheep show differential sensitivity to calcium and magnesium, with regulation of human RyR2 resembling that of sheep more than that of rat. Regulation of the cardiac ryanodine receptor (RyR2) by intracellular Ca2+ and Mg2+ plays a key role in determining cardiac contraction and rhythmicity, but their role in regulating the human RyR2 remains poorly defined. The Ca2+- and Mg2+-dependent regulation of human RyR2 was recorded in artificial lipid bilayers in the presence of 2 mM ATP and compared with that in two commonly used animal models for RyR2 function (rat and sheep). Human RyR2 displayed cytoplasmic Ca2+ activation (Ka = 4 µM) and inhibition by cytoplasmic Mg2+ (Ki = 10 µM at 100 nM Ca2+) that was similar to RyR2 from rat and sheep obtained under the same experimental conditions. However, in the presence of 0.1 mM Ca2+, RyR2s from human were 3.5-fold less sensitive to cytoplasmic Mg2+ inhibition than those from sheep and rat. The Ka values for luminal Ca2+ activation were similar in the three species (35 µM for human, 12 µM for sheep, and 10 µM for rat). From the relationship between open probability and luminal [Ca2+], the peak open probability for the human RyR2 was approximately the same as that for sheep, and both were ∼10-fold greater than that for rat RyR2. Human RyR2 also showed the same sensitivity to luminal Mg2+ as that from sheep, whereas rat RyR2 was 10-fold more sensitive. In all species, modulation of RyR2 gating by luminal Ca2+ and Mg2+ only occurred when cytoplasmic [Ca2+] was <3 µM. The activation response of RyR2 to luminal and cytoplasmic Ca2+ was strongly dependent on the Mg2+ concentration. Addition of physiological levels (1 mM) of Mg2+ raised the Ka for cytoplasmic Ca2+ to 30 µM (human and sheep) or 90 µM (rat) and raised the Ka for luminal Ca2+ to ∼1 mM in all species. This is the first report of the regulation by Ca2+ and Mg2+ of native RyR2 receptor activity from healthy human hearts.
Collapse
Affiliation(s)
- Kafa Walweel
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales 2308, Australia
| | - Jiao Li
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales 2308, Australia
| | - Peter Molenaar
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland 4001, Australia School of Medicine, University of Queensland, Brisbane, Queensland 4006, Australia Critical Care Research Group, The Prince Charles Hospital Foundation, Chermside, Queensland 4032, Australia
| | - Mohammad S Imtiaz
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales 2308, Australia
| | - Anthony Quail
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales 2308, Australia
| | - Cris G dos Remedios
- Bosch Institute, Discipline of Anatomy, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Nicole A Beard
- Faculty of Education, Science, Technology, and Mathematics, University of Canberra, Canberra, Australian Capital Territory 2601, Australia
| | - Angela F Dulhunty
- The John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory 2600, Australia
| | - Dirk F van Helden
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales 2308, Australia
| | - Derek R Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales 2308, Australia
| |
Collapse
|
31
|
Beard NA, Dulhunty AF. C-terminal residues of skeletal muscle calsequestrin are essential for calcium binding and for skeletal ryanodine receptor inhibition. Skelet Muscle 2015; 5:6. [PMID: 25861445 PMCID: PMC4389316 DOI: 10.1186/s13395-015-0029-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 01/14/2015] [Indexed: 02/05/2023] Open
Abstract
Background Skeletal muscle function depends on calcium signaling proteins in the sarcoplasmic reticulum (SR), including the calcium-binding protein calsequestrin (CSQ), the ryanodine receptor (RyR) calcium release channel, and skeletal triadin 95 kDa (trisk95) and junctin, proteins that bind to calsequestrin type 1 (CSQ1) and ryanodine receptor type 1 (RyR1). CSQ1 inhibits RyR1 and communicates store calcium load to RyR1 channels via trisk95 and/or junctin. Methods In this manuscript, we test predictions that CSQ1’s acidic C-terminus contains binding sites for trisk95 and junctin, the major calcium binding domain, and that it determines CSQ1’s ability to regulate RyR1 activity. Results Progressive alanine substitution of C-terminal acidic residues of CSQ1 caused a parallel reduction in the calcium binding capacity but did not significantly alter CSQ1’s association with trisk95/junctin or influence its inhibition of RyR1 activity. Deletion of the final seven residues in the C-terminus significantly hampered calcium binding, significantly reduced CSQ’s association with trisk95/junctin and decreased its inhibition of RyR1. Deletion of the full C-terminus further reduced calcium binding to CSQ1 altered its association with trisk95 and junctin and abolished its inhibition of RyR1. Conclusions The correlation between the number of residues mutated/deleted and binding of calcium, trisk95, and junctin suggests that binding of each depends on diffuse ionic interactions with several C-terminal residues and that these interactions may be required for CSQ1 to maintain normal muscle function.
Collapse
Affiliation(s)
- Nicole A Beard
- John Curtin School of Medical Research, Australian National University, Garran Road, Canberra, ACT 2601 Australia ; Discipline of Biomedical Sciences, Centre for Research in Therapeutic Solutions, Faculty of Education Science, Technology and Maths, University of Canberra, Kirinari Street, Bruce, ACT 2601 Australia
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Garran Road, Canberra, ACT 2601 Australia
| |
Collapse
|
32
|
Li L, Mirza S, Richardson SJ, Gallant EM, Thekkedam C, Pace SM, Zorzato F, Liu D, Beard NA, Dulhunty AF. A new cytoplasmic interaction between junctin and ryanodine receptor Ca2+ release channels. J Cell Sci 2015; 128:951-63. [PMID: 25609705 PMCID: PMC4342579 DOI: 10.1242/jcs.160689] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Junctin, a non-catalytic splice variant encoded by the aspartate-β-hydroxylase (Asph) gene, is inserted into the membrane of the sarcoplasmic reticulum (SR) Ca2+ store where it modifies Ca2+ signalling in the heart and skeletal muscle through its regulation of ryanodine receptor (RyR) Ca2+ release channels. Junctin is required for normal muscle function as its knockout leads to abnormal Ca2+ signalling, muscle dysfunction and cardiac arrhythmia. However, the nature of the molecular interaction between junctin and RyRs is largely unknown and was assumed to occur only in the SR lumen. We find that there is substantial binding of RyRs to full junctin, and the junctin luminal and, unexpectedly, cytoplasmic domains. Binding of these different junctin domains had distinct effects on RyR1 and RyR2 activity: full junctin in the luminal solution increased RyR channel activity by ∼threefold, the C-terminal luminal interaction inhibited RyR channel activity by ∼50%, and the N-terminal cytoplasmic binding produced an ∼fivefold increase in RyR activity. The cytoplasmic interaction between junctin and RyR is required for luminal binding to replicate the influence of full junctin on RyR1 and RyR2 activity. The C-terminal domain of junctin binds to residues including the S1–S2 linker of RyR1 and N-terminal domain of junctin binds between RyR1 residues 1078 and 2156.
Collapse
Affiliation(s)
- Linwei Li
- John Curtin School of Medical Research, ACT 0200, Australia
| | - Shamaruh Mirza
- John Curtin School of Medical Research, ACT 0200, Australia
| | | | | | | | - Suzy M Pace
- John Curtin School of Medical Research, ACT 0200, Australia
| | | | - Dan Liu
- John Curtin School of Medical Research, ACT 0200, Australia
| | - Nicole A Beard
- John Curtin School of Medical Research, ACT 0200, Australia
| | | |
Collapse
|
33
|
Hanna AD, Lam A, Tham S, Dulhunty AF, Beard NA. Adverse effects of doxorubicin and its metabolic product on cardiac RyR2 and SERCA2A. Mol Pharmacol 2014; 86:438-49. [PMID: 25106424 PMCID: PMC4164980 DOI: 10.1124/mol.114.093849] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 08/08/2014] [Indexed: 11/22/2022] Open
Abstract
The use of anthracycline chemotherapeutic drugs is restricted owing to potentially fatal cardiotoxic side effects. It has been hypothesized that anthracycline metabolites have a primary role in this cardiac dysfunction; however, information on the molecular interactions of these compounds in the heart is scarce. Here we provide novel evidence that doxorubicin and its metabolite, doxorubicinol, bind to the cardiac ryanodine receptor (RyR2) and to the sarco/endoplasmic reticulum Ca(2+) ATPase (SERCA2A) and deleteriously alter their activity. Both drugs (0.01 μM-2.5 μM) activated single RyR2 channels, and this was reversed by drug washout. Both drugs caused a secondary inhibition of RyR2 activity that was not reversed by drug washout. Preincubation with the reducing agent dithiothreitol (DTT, 1 mM) prevented drug-induced inhibition of channel activity. Doxorubicin and doxorubicinol reduced the abundance of thiol groups on RyR2, further indicating that oxidation reactions may be involved in the actions of the compounds. Ca(2+) uptake into sarcoplasmic reticulum vesicles by SERCA2A was inhibited by doxorubicinol, but not doxorubicin. Unexpectedly, in the presence of DTT, doxorubicinol enhanced the rate of Ca(2+) uptake by SERCA2A. Together the evidence provided here shows that doxorubicin and doxorubicinol interact with RyR2 and SERCA2A in similar ways, but that the metabolite acts with greater efficacy than the parent compound. Both compounds modify RyR2 and SERCA2A activity by binding to the proteins and also act via thiol oxidation to disrupt SR Ca(2+) handling. These actions would have severe consequences on cardiomyocyte function and contribute to clinical symptoms of acute anthracycline cardiotoxicity.
Collapse
Affiliation(s)
- Amy D Hanna
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Alex Lam
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Steffi Tham
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Nicole A Beard
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| |
Collapse
|
34
|
Hernández-Ochoa EO, Olojo RO, Rebbeck RT, Dulhunty AF, Schneider MF. β1a490-508, a 19-residue peptide from C-terminal tail of Cav1.1 β1a subunit, potentiates voltage-dependent calcium release in adult skeletal muscle fibers. Biophys J 2014; 106:535-47. [PMID: 24507594 DOI: 10.1016/j.bpj.2013.11.4503] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 11/11/2013] [Accepted: 11/13/2013] [Indexed: 10/25/2022] Open
Abstract
The α1 and β1a subunits of the skeletal muscle calcium channel, Cav1.1, as well as the Ca(2+) release channel, ryanodine receptor (RyR1), are essential for excitation-contraction coupling. RyR1 channel activity is modulated by the β1a subunit and this effect can be mimicked by a peptide (β1a490-524) corresponding to the 35-residue C-terminal tail of the β1a subunit. Protein-protein interaction assays confirmed a high-affinity interaction between the C-terminal tail of the β1a and RyR1. Based on previous results using overlapping peptides tested on isolated RyR1, we hypothesized that a 19-amino-acid residue peptide (β1a490-508) is sufficient to reproduce activating effects of β1a490-524. Here we examined the effects of β1a490-508 on Ca(2+) release and Ca(2+) currents in adult skeletal muscle fibers subjected to voltage-clamp and on RyR1 channel activity after incorporating sarcoplasmic reticulum vesicles into lipid bilayers. β1a490-508 (25 nM) increased the peak Ca(2+) release flux by 49% in muscle fibers. Considerably fewer activating effects were observed using 6.25, 100, and 400 nM of β1a490-508 in fibers. β1a490-508 also increased RyR1 channel activity in bilayers and Cav1.1 currents in fibers. A scrambled form of β1a490-508 peptide was used as negative control and produced negligible effects on Ca(2+) release flux and RyR1 activity. Our results show that the β1a490-508 peptide contains molecular components sufficient to modulate excitation-contraction coupling in adult muscle fibers.
Collapse
Affiliation(s)
- Erick O Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Rotimi O Olojo
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Robyn T Rebbeck
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Martin F Schneider
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland.
| |
Collapse
|
35
|
Hanna AD, Lam A, Thekkedam C, Gallant EM, Beard NA, Dulhunty AF. Cardiac ryanodine receptor activation by a high Ca²⁺ store load is reversed in a reducing cytoplasmic redox environment. J Cell Sci 2014; 127:4531-41. [PMID: 25146393 PMCID: PMC4197090 DOI: 10.1242/jcs.156760] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Here, we report the impact of redox potential on isolated cardiac ryanodine receptor (RyR2) channel activity and its response to physiological changes in luminal [Ca2+]. Basal leak from the sarcoplasmic reticulum is required for normal Ca2+ handling, but excess diastolic Ca2+ leak attributed to oxidative stress is thought to lower the threshold of RyR2 for spontaneous sarcoplasmic reticulum Ca2+ release, thus inducing arrhythmia in pathological situations. Therefore, we examined the RyR2 response to luminal [Ca2+] under reducing or oxidising cytoplasmic redox conditions. Unexpectedly, as luminal [Ca2+] increased from 0.1 to 1.5 mM, RyR2 activity declined when pretreated with cytoplasmic 1 mM DTT or buffered with GSH∶GSSG to a normal reduced cytoplasmic redox potential (−220 mV). Conversely, with 20 µM cytoplasmic 4,4′-DTDP or buffering of the redox potential to an oxidising value (−180 mV), RyR2 activity increased with increasing luminal [Ca2+]. The luminal redox potential was constant at −180 mV in each case. These responses to luminal [Ca2+] were maintained with cytoplasmic 2 mM Na2ATP or 5 mM MgATP (1 mM free Mg2+). Overall, the results suggest that the redox potential in the RyR2 junctional microdomain is normally more oxidised than that of the bulk cytoplasm.
Collapse
Affiliation(s)
- Amy D Hanna
- John Curtin School of Medical Research, Australian National University, Canberra, ACT 6200, Australia
| | - Alex Lam
- John Curtin School of Medical Research, Australian National University, Canberra, ACT 6200, Australia
| | - Chris Thekkedam
- John Curtin School of Medical Research, Australian National University, Canberra, ACT 6200, Australia
| | - Esther M Gallant
- John Curtin School of Medical Research, Australian National University, Canberra, ACT 6200, Australia
| | - Nicole A Beard
- Centre for Research in Therapeutic Solutions, University of Canberra, Bruce, ACT 2617, Australia
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, ACT 6200, Australia
| |
Collapse
|
36
|
Rebbeck RT, Karunasekara Y, Board PG, Beard NA, Casarotto MG, Dulhunty AF. Skeletal muscle excitation–contraction coupling: Who are the dancing partners? Int J Biochem Cell Biol 2014; 48:28-38. [DOI: 10.1016/j.biocel.2013.12.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 11/29/2013] [Accepted: 12/04/2013] [Indexed: 01/15/2023]
|
37
|
Steele GA, Beard NA, Board PG, Dulhunty AF. CLIC-2 Determines FKBP12 and FKBP12.6 Association with Ryanodine Receptor Calcium Release Channels. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
38
|
Casarotto MG, Karunasekara Y, Aditya S, Cappello J, Dulhunty AF, Board PG, Oakley AJ, Norris NC. Structural and Binding Studies of the Cav1.1 β1A Subunit. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.2531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
39
|
Hanna AD, Lam A, Dulhunty AF, Beard NA. Mechanisms of Anthracycline-Induced Dysfunction of Calcium Handling Proteins in the Heart. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
|
40
|
Li J, Imtiaz MS, Beard NA, Dulhunty AF, Thorne R, vanHelden DF, Laver DR. ß-Adrenergic stimulation increases RyR2 activity via intracellular Ca2+ and Mg2+ regulation. PLoS One 2013; 8:e58334. [PMID: 23533585 PMCID: PMC3606165 DOI: 10.1371/journal.pone.0058334] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 02/02/2013] [Indexed: 01/19/2023] Open
Abstract
Here we investigate how ß-adrenergic stimulation of the heart alters regulation of ryanodine receptors (RyRs) by intracellular Ca2+ and Mg2+ and the role of these changes in SR Ca2+ release. RyRs were isolated from rat hearts, perfused in a Langendorff apparatus for 5 min and subject to 1 min perfusion with 1 µM isoproterenol or without (control) and snap frozen in liquid N2 to capture their phosphorylation state. Western Blots show that RyR2 phosphorylation was increased by isoproterenol, confirming that RyR2 were subject to normal ß-adrenergic signaling. Under basal conditions, S2808 and S2814 had phosphorylation levels of 69% and 15%, respectively. These levels were increased to 83% and 60%, respectively, after 60 s of ß-adrenergic stimulation consistent with other reports that ß-adrenergic stimulation of the heart can phosphorylate RyRs at specific residues including S2808 and S2814 causing an increase in RyR activity. At cytoplasmic [Ca2+] <1 µM, ß-adrenergic stimulation increased luminal Ca2+ activation of single RyR channels, decreased luminal Mg2+ inhibition and decreased inhibition of RyRs by mM cytoplasmic Mg2+. At cytoplasmic [Ca2+] >1 µM, ß-adrenergic stimulation only decreased cytoplasmic Mg2+ and Ca2+ inhibition of RyRs. The Ka and maximum levels of cytoplasmic Ca2+ activation site were not affected by ß-adrenergic stimulation. Our RyR2 gating model was fitted to the single channel data. It predicted that in diastole, ß-adrenergic stimulation is mediated by 1) increasing the activating potency of Ca2+ binding to the luminal Ca2+ site and decreasing its affinity for luminal Mg2+ and 2) decreasing affinity of the low-affinity Ca2+/Mg2+ cytoplasmic inhibition site. However in systole, ß-adrenergic stimulation is mediated mainly by the latter.
Collapse
Affiliation(s)
- Jiao Li
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Mohammad S. Imtiaz
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Nicole A. Beard
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Angela F. Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Rick Thorne
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Dirk F. vanHelden
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Derek R. Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
- * E-mail:
| |
Collapse
|
41
|
Dulhunty AF, Wium E, Li L, Hanna AD, Mirza S, Talukder S, Ghazali NA, Beard NA. Proteins within the intracellular calcium store determine cardiac RyR channel activity and cardiac output. Clin Exp Pharmacol Physiol 2013; 39:477-84. [PMID: 22524859 DOI: 10.1111/j.1440-1681.2012.05704.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
SUMMARY The contractile function of the heart requires the release of Ca(2+) from intracellular Ca(2+) stores in the sarcoplasmic reticulum (SR) of cardiac muscle cells. The efficacy of Ca(2+) release depends on the amount of Ca(2+) loaded into the Ca(2+) store and the way in which this 'Ca(2+) load' influences the activity of the cardiac ryanodine receptor Ca(2+) release channel (RyR2). The effects of the Ca(2+) load on Ca(2+) release through RyR2 are facilitated by: (i) the sensitivity of RyR2 itself to luminal Ca(2+) concentrations; and (ii) interactions between the cardiac Ca(2+) -binding protein calsequestrin (CSQ) 2 and RyR2, transmitted through the 'anchoring' proteins junctin and/or triadin. Mutations in RyR2 are linked to catecholaminergic polymorphic ventricular tachycardia (CPVT) and sudden cardiac death. The tachycardia is associated with changes in the sensitivity of RyR2 to luminal Ca(2+) . Triadin-, junctin- or CSQ-null animals survive, but their longevity and ability to tolerate stress is compromised. These studies reveal the importance of the proteins in normal muscle function, but do not reveal the molecular nature of their functional interactions, which must be defined before changes in the proteins leading to CPVT and heart disease can be understood. Herein, we discuss known interactions between the RyR, triadin, junctin and CSQ with emphasis on the cardiac isoforms of the proteins. Where there is little known about the cardiac isoforms, we discuss evidence from skeletal isoforms.
Collapse
Affiliation(s)
- Angela F Dulhunty
- Department of Translational Biosciences, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia.
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Hanna AD, Lam A, Dulhunty AF, Beard NA. Anthracycline-Induced Dysfunction of Cardiac SR Ca2+ Handling - The Role of Thiol Oxidation. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
43
|
Willemse H, Smith PN, Board PG, Casarotto MG, Dulhunty AF. Human Aging and Expression of Proteins Interacting with the Ryanodine Receptor in Skeletal Muscle. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
|
44
|
Li L, Mirza S, Beard NA, Dulhunty AF. A Cytoplasmic Interaction between Junctin and RyRs with Major Consequences for RyR1 and RyR2 Activity In Vitro. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
|
45
|
Rebbeck RT, Willemse H, Groom L, Dirksen RT, Dulhunty AF. Interactions between Dihydropyridine β1A Subunit and Ryanodine Receptor Isoforms. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
|
46
|
Dulhunty AF, Beard NA, Hanna AD. Regulation and dysregulation of cardiac ryanodine receptor (RyR2) open probability during diastole in health and disease. ACTA ACUST UNITED AC 2012; 140:87-92. [PMID: 22851673 PMCID: PMC3409097 DOI: 10.1085/jgp.201210862] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
47
|
Karunasekara Y, Rebbeck RT, Weaver LM, Board PG, Dulhunty AF, Casarotto MG. An α-helical C-terminal tail segment of the skeletal L-type Ca2+ channel β1a subunit activates ryanodine receptor type 1 via a hydrophobic surface. FASEB J 2012; 26:5049-59. [PMID: 22962299 DOI: 10.1096/fj.12-211334] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Excitation-contraction (EC) coupling in skeletal muscle depends on protein interactions between the transverse tubule dihydropyridine receptor (DHPR) voltage sensor and intracellular ryanodine receptor (RyR1) calcium release channel. We present novel data showing that the C-terminal 35 residues of the β(1a) subunit adopt a nascent α-helix in which 3 hydrophobic residues align to form a hydrophobic surface that binds to RyR1 isolated from rabbit skeletal muscle. Mutation of the hydrophobic residues (L496, L500, W503) in peptide β(1a)V490-M524, corresponding to the C-terminal 35 residues of β(1a), reduced peptide binding to RyR1 to 15.2 ± 7.1% and prevented the 2.9 ± 0.2-fold activation of RyR1 by 10 nM wild-type peptide. An upstream hydrophobic heptad repeat implicated in β(1a) binding to RyR1 does not contribute to RyR1 activation. Wild-type β(1a)A474-A508 peptide (10 nM), containing heptad repeat and hydrophobic surface residues, increased RyR1 activity by 2.3 ± 0.2- and 2.2 ± 0.3-fold after mutation of the heptad repeat residues. We conclude that specific hydrophobic surface residues in the 35 residue β(1a) C-terminus bind to RyR1 and increase channel activity in lipid bilayers and thus may support skeletal EC coupling.
Collapse
Affiliation(s)
- Yamuna Karunasekara
- Department of Translational Bioscience, John Curtin School of Medical Research, Australian National University, P.O. Box 334, Canberra, ACT 2601, Australia
| | | | | | | | | | | |
Collapse
|
48
|
Takano K, Liu D, Tarpey P, Gallant E, Lam A, Witham S, Alexov E, Chaubey A, Stevenson RE, Schwartz CE, Board PG, Dulhunty AF. An X-linked channelopathy with cardiomegaly due to a CLIC2 mutation enhancing ryanodine receptor channel activity. Hum Mol Genet 2012; 21:4497-507. [PMID: 22814392 DOI: 10.1093/hmg/dds292] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Chloride intracellular channel 2 (CLIC2) protein is a member of the glutathione transferase class of proteins. Its' only known function is the regulation of ryanodine receptor (RyR) intracellular Ca(2+) release channels. These RyR proteins play a major role in the regulation of Ca(2+) signaling in many cells. Utilizing exome capture and deep sequencing of genes on the X-chromosome, we have identified a mutation in CLIC2 (c.303C>G, p.H101Q) which is associated with X-linked intellectual disability (ID), atrial fibrillation, cardiomegaly, congestive heart failure (CHF), some somatic features and seizures. Functional studies of the H101Q variant indicated that it stimulated rather than inhibited the action of RyR channels, with channels remaining open for longer times and potentially amplifying Ca(2+) signals dependent on RyR channel activity. The overly active RyRs in cardiac and skeletal muscle cells and neuronal cells would result in abnormal cardiac function and trigger post-synaptic pathways and neurotransmitter release. The presence of both cardiomegaly and CHF in the two affected males and atrial fibrillation in one are consistent with abnormal RyR2 channel function. Since the dysfunction of RyR2 channels in the brain via 'leaky mutations' can result in mild developmental delay and seizures, our data also suggest a vital role for the CLIC2 protein in maintaining normal cognitive function via its interaction with RyRs in the brain. Therefore, our patients appear to suffer from a new channelopathy comprised of ID, seizures and cardiac problems because of enhanced Ca(2+) release through RyRs in neuronal cells and cardiac muscle cells.
Collapse
Affiliation(s)
- Kyoko Takano
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Liu D, Hewawasam R, Karunasekara Y, Casarotto MG, Dulhunty AF, Board PG. The inhibitory glutathione transferase M2-2 binding site is located in divergent region 3 of the cardiac ryanodine receptor. Biochem Pharmacol 2012; 83:1523-9. [PMID: 22406107 DOI: 10.1016/j.bcp.2012.02.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 02/19/2012] [Accepted: 02/21/2012] [Indexed: 10/28/2022]
Abstract
The muscle-specific glutathione transferase GSTM2-2 modulates the activity of ryanodine receptor (RyR) calcium release channels: it inhibits the activity of cardiac RyR (RyR2) channels with high affinity and activates skeletal RyR (RyR1) channels with low affinity. The C terminal domain of GSTM2-2 (GSTM2C) alone physically binds to RyR2 and inhibits its activity, but it does not bind to RyR1. We have now used yeast two-hybrid analysis, chemical cross-linking, intrinsic tryptophan fluorescence and Ca(2+) release studies to determine that the binding site for GSTM2C is in divergent region 3 (D3) of RyR2. The D3 region encompasses residues 1855-1890 in RyR2. Specific mutagenesis shows the binding primarily involves electrostatic interactions with residues K1875, K1886, R1887 and K1889, all residues that are present in RyR2, but not in RyR1. The significant sequence differences between the D3 regions of RyR2 and RyR1 explain why GSTM2-2 specifically inhibits RyR2. This specific inhibition of RyR2 could modulate Ca cycling and be useful for the treatment of heart failure. RyR2 inhibition during diastole may improve filling of the SR with Ca(2+) and improve contractility.
Collapse
Affiliation(s)
- Dan Liu
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | | | | | | | | | | |
Collapse
|
50
|
Janczura M, Blackburn A, Dulhunty AF, Beard NA. Acute Chemotherapeutic Treatment Induces Chronic Phosphorylation of the Cardiac Ryanodine Receptor. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.3018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|