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Berchtold MW, Villalobo A. Ca 2+/calmodulin signaling in organismal aging and cellular senescence: Impact on human diseases. Biochim Biophys Acta Mol Basis Dis 2025; 1871:167583. [PMID: 39579800 DOI: 10.1016/j.bbadis.2024.167583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2024] [Revised: 11/18/2024] [Accepted: 11/18/2024] [Indexed: 11/25/2024]
Abstract
Molecular mechanisms of aging processes at the level of organisms and cells are in the focus of a large number of research laboratories. This research culminated in recent breakthroughs, which contributed to the better understanding of the natural aging process and aging associated malfunctions leading to age-related diseases. Ca2+ in connection with its master intracellular sensor protein calmodulin (CaM) regulates a plethora of crucial cellular processes orchestrating a wide range of signaling processes. This review focuses on the involvement of Ca2+/CaM in cellular mechanisms, which are associated with normal aging, as well as playing a role in the development of diseases connected with signaling processes during aging. We specifically highlight processes that involve inactivation of proteins, which take part in Ca2+/CaM regulatory systems by oxygen or nitrogen free radical species, during organismal aging and cellular senescence. As examples of organs where aging processes have recently been investigated, we chose to review the literature on molecular aging processes with involvement of Ca2+/CaM in heart and neuronal diseases, as well as in cancer and metabolic diseases, all deeply affected by aging. In addition, this article focuses on cellular senescence, a mechanism that may contribute to aging processes and therefore has been proposed as a target to interfere with the progression of age-associated diseases.
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Affiliation(s)
- Martin W Berchtold
- Department of Biology, University of Copenhagen, 13 Universitetsparken, DK-2100 Copenhagen Ø, Denmark.
| | - Antonio Villalobo
- Cancer and Human Molecular Genetics Area, Oto-Neurosurgery Research Group, University Hospital La Paz Research Institute (IdiPAZ), Paseo de la Castellana 261, E-28046 Madrid, Spain.
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2
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Charest A, Nasta N, Siddiqui S, Menkes S, Thomas A, Saad D, Forman J, Huang X, Sison CP, Gerdes AM, Stout RF, Ojamaa K. Nanoscale organization of cardiac calcium channels is dependent on thyroid hormone status. Am J Physiol Heart Circ Physiol 2024; 327:H1309-H1326. [PMID: 39365674 PMCID: PMC11559645 DOI: 10.1152/ajpheart.00272.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 09/12/2024] [Accepted: 09/27/2024] [Indexed: 10/06/2024]
Abstract
Thyroid hormone dysfunction is frequently observed in patients with chronic illnesses including heart failure, which increases the risk of adverse events. This study examined the effects of thyroid hormones (THs) on cardiac transverse-tubule (TT) integrity, Ca2+ sparks, and nanoscale organization of ion channels in excitation-contraction (EC) coupling, including L-type calcium channel (CaV1.2), ryanodine receptor type 2 (RyR2), and junctophilin-2 (Jph2). TH deficiency was established in adult female rats by propyl-thiouracil (PTU) ingestion for 8 wk; followed by randomization to continued PTU without or with oral triiodo-l-thyronine (T3; 10 µg/kg/day) for an additional 2 wk (PTU + T3). Confocal microscopy of isolated cardiomyocytes (CMs) showed significant misalignment of TTs and increased Ca2+ sparks in thyroid-deficient CMs. Density-based spatial clustering of applications with noise (DBSCAN) analysis of stochastic optical reconstruction microscopy (STORM) images showed decreased (P < 0.0001) RyR2 cluster number per cell area in PTU CMs compared with euthyroid (EU) control myocytes, and this was normalized by T3 treatment. CaV1.2 channels and Jph2 localized within a 210 nm radius of the RyR2 clusters were significantly reduced in PTU myocytes, and these values were increased with T3 treatment. A significant percentage of the RyR2 clusters in the PTU myocytes had neither CaV1.2 nor Jph2, suggesting fewer functional clusters in EC coupling. Nearest neighbor distances between RyR2 clusters were greater (P < 0.001) in PTU cells compared with EU- and T3-treated CMs that correspond to disarray of TTs at the sarcomere z-discs. These results support a regulatory role of T3 in the nanoscale organization of RyR2 clusters and colocalization of CaV1.2 and Jph2 in optimizing EC coupling.NEW & NOTEWORTHY Thyroid hormone (TH) dysfunction exacerbates preexisting heart conditions leading to an increased risk of premature morbidity/mortality. Triiodo-l-thyronine (T3) optimizes cardiac excitation-contraction (EC) coupling by maintaining myocardial T-tubule (TT) structures and organization of calcium ion channels. Single-molecule localization microscopy shows T3 effects on the clustering of ryanodine receptors (RyR2) with colocalization of L-type calcium channels (CaV1.2) and junctophilin-2 (Jph2) at TT-SR structures. Heart disease with subclinical hypothyroidism/low T3 syndrome may benefit from TH treatment.
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Affiliation(s)
- Amanda Charest
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States
| | - Nicholas Nasta
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States
| | - Sumaiyah Siddiqui
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States
| | - Silvia Menkes
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States
| | - Anvin Thomas
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States
| | - Dana Saad
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States
| | - Jake Forman
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States
| | - Xueqi Huang
- Biostatistics Unit, Office of Academic Affairs, Northwell Health, New Hyde Park, New York, United States
| | - Cristina P Sison
- Biostatistics Unit, Office of Academic Affairs, Northwell Health, New Hyde Park, New York, United States
| | - A Martin Gerdes
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States
| | - Randy F Stout
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States
| | - Kaie Ojamaa
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States
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3
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Alvarez JAE, Jafri MS, Ullah A. Using a Failing Human Ventricular Cardiomyocyte Model to Re-Evaluate Ca 2+ Cycling, Voltage Dependence, and Spark Characteristics. Biomolecules 2024; 14:1371. [PMID: 39595549 PMCID: PMC11591732 DOI: 10.3390/biom14111371] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2024] [Revised: 10/13/2024] [Accepted: 10/23/2024] [Indexed: 11/28/2024] Open
Abstract
Previous studies have observed alterations in excitation-contraction (EC) coupling during end-stage heart failure that include action potential and calcium (Ca2+) transient prolongation and a reduction of the Ca2+ transient amplitude. Underlying these phenomena are the downregulation of potassium (K+) currents, downregulation of the sarcoplasmic reticulum Ca2+ ATPase (SERCA), increase Ca2+ sensitivity of the ryanodine receptor, and the upregulation of the sodium-calcium (Na=-Ca2+) exchanger. However, in human heart failure (HF), debate continues about the relative contributions of the changes in calcium handling vs. the changes in the membrane currents. To understand the consequences of the above changes, they are incorporated into a computational human ventricular myocyte HF model that can explore the contributions of the spontaneous Ca2+ release from the sarcoplasmic reticulum (SR). The reduction of transient outward K+ current (Ito) is the main membrane current contributor to the decrease in RyR2 open probability and L-type calcium channel (LCC) density which emphasizes its importance to phase 1 of the action potential (AP) shape and duration (APD). During current-clamp conditions, RyR2 hyperphosphorylation exhibits the least amount of Ca2+ release from the SR into the cytosol and SR Ca2+ fractional release during a dynamic slow-rapid-slow (0.5-2.5-0.5 Hz) pacing, but it displays the most abundant and more lasting Ca2+ sparks two-fold longer than a normal cell. On the other hand, under voltage-clamp conditions, HF by decreased SERCA and upregulated INCX show the least SR Ca2+ uptake and EC coupling gain, as compared to HF by hyperphosphorylated RyR2s. Overall, this study demonstrates that the (a) combined effect of SERCA and NCX, and the (b) RyR2 dysfunction, along with the downregulation of the cardiomyocyte's potassium currents, could substantially contribute to Ca2+ mishandling at the spark level that leads to heart failure.
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Affiliation(s)
- Jerome Anthony E. Alvarez
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA;
- US Naval Research Laboratory, Center for Bio/Molecular Science and Engineering, Washington, DC 20375, USA
| | - Mohsin Saleet Jafri
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA;
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 20201, USA
| | - Aman Ullah
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA;
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4
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Cooke JP, Youker KA, Lai L. Myocardial Recovery versus Myocardial Regeneration: Mechanisms and Therapeutic Modulation. Methodist Debakey Cardiovasc J 2024; 20:31-41. [PMID: 39184159 PMCID: PMC11342844 DOI: 10.14797/mdcvj.1400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Accepted: 06/12/2024] [Indexed: 08/27/2024] Open
Abstract
Myocardial recovery is characterized by a return toward normal structure and function of the heart after an injury. Mechanisms of myocardial recovery include restoration and/or adaptation of myocyte structure and function, mitochondrial activity and number, metabolic homeostasis, electrophysiological stability, extracellular matrix remodeling, and myocardial perfusion. Myocardial regeneration is an element of myocardial recovery that involves the generation of new myocardial tissue, a process which is limited in adult humans but may be therapeutically augmented. Understanding the mechanisms of myocardial recovery and myocardial regeneration will lead to novel therapies for heart failure.
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Affiliation(s)
- John P. Cooke
- Houston Methodist Academic Institute, Houston, Texas, US
| | | | - Li Lai
- Houston Methodist Academic Institute, Houston, Texas, US
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Alibhai FJ, Li RK. Rejuvenation of the Aging Heart: Molecular Determinants and Applications. Can J Cardiol 2024; 40:1394-1411. [PMID: 38460612 DOI: 10.1016/j.cjca.2024.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 02/20/2024] [Accepted: 03/04/2024] [Indexed: 03/11/2024] Open
Abstract
In Canada and worldwide, the elderly population (ie, individuals > 65 years of age) is increasing disproportionately relative to the total population. This is expected to have a substantial impact on the health care system, as increased aged is associated with a greater incidence of chronic noncommunicable diseases. Within the elderly population, cardiovascular disease is a leading cause of death, therefore developing therapies that can prevent or slow disease progression in this group is highly desirable. Historically, aging research has focused on the development of anti-aging therapies that are implemented early in life and slow the age-dependent decline in cell and organ function. However, accumulating evidence supports that late-in-life therapies can also benefit the aged cardiovascular system by limiting age-dependent functional decline. Moreover, recent studies have demonstrated that rejuvenation (ie, reverting cellular function to that of a younger phenotype) of the already aged cardiovascular system is possible, opening new avenues to develop therapies for older individuals. In this review, we first provide an overview of the functional changes that occur in the cardiomyocyte with aging and how this contributes to the age-dependent decline in heart function. We then discuss the various anti-aging and rejuvenation strategies that have been pursued to improve the function of the aged cardiomyocyte, with a focus on therapies implemented late in life. These strategies include 1) established systemic approaches (caloric restriction, exercise), 2) pharmacologic approaches (mTOR, AMPK, SIRT1, and autophagy-targeting molecules), and 3) emerging rejuvenation approaches (partial reprogramming, parabiosis/modulation of circulating factors, targeting endogenous stem cell populations, and senotherapeutics). Collectively, these studies demonstrate the exciting potential and limitations of current rejuvenation strategies and highlight future areas of investigation that will contribute to the development of rejuvenation therapies for the aged heart.
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Affiliation(s)
- Faisal J Alibhai
- Toronto General Research Hospital Institute, University Health Network, Toronto, Ontario, Canada
| | - Ren-Ke Li
- Toronto General Research Hospital Institute, University Health Network, Toronto, Ontario, Canada; Department of Surgery, Division of Cardiovascular Surgery, University of Toronto, Toronto, Ontario, Canada.
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6
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Starnes L, Hall A, Etal D, Cavallo AL, Grabowski P, Gallon J, Kha M, Hicks R, Pointon A. RYR2 deficient human model identifies calcium handling and metabolic dysfunction impacting pharmacological responses. Front Cardiovasc Med 2024; 11:1357315. [PMID: 39041002 PMCID: PMC11260679 DOI: 10.3389/fcvm.2024.1357315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Accepted: 06/18/2024] [Indexed: 07/24/2024] Open
Abstract
Creation of disease models utilizing hiPSCs in combination with CRISPR/Cas9 gene editing enable mechanistic insights into differential pharmacological responses. This allows translation of efficacy and safety findings from a healthy to a diseased state and provides a means to predict clinical outcome sooner during drug discovery. Calcium handling disturbances including reduced expression levels of the type 2 ryanodine receptor (RYR2) are linked to cardiac dysfunction; here we have created a RYR2 deficient human cardiomyocyte model that mimics some aspects of heart failure. RYR2 deficient cardiomyocytes show differential pharmacological responses to L-type channel calcium inhibitors. Phenotypic and proteomic characterization reveal novel molecular insights with altered expression of structural proteins including CSRP3, SLMAP, and metabolic changes including upregulation of the pentose phosphate pathway and increased sensitivity to redox alterations. This genetically engineered in vitro cardiovascular model of RYR2 deficiency supports the study of pharmacological responses in the context of calcium handling and metabolic dysfunction enabling translation of drug responses from healthy to perturbed cellular states.
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Affiliation(s)
- Linda Starnes
- Safety Sciences, Clinical Pharmacology & Safety Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Andrew Hall
- Safety Sciences, Clinical Pharmacology & Safety Sciences, R&D, AstraZeneca, Cambridge, United Kingdom
| | - Damla Etal
- Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | | | - Piotr Grabowski
- Imaging and Data Analytics, Clinical Pharmacology & Safety Sciences, R&D, AstraZeneca, Cambridge, United Kingdom
| | - John Gallon
- Imaging and Data Analytics, Clinical Pharmacology & Safety Sciences, R&D, AstraZeneca, Cambridge, United Kingdom
| | - Michelle Kha
- Safety Sciences, Clinical Pharmacology & Safety Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Ryan Hicks
- BioPharmaceuticals R&D Cell Therapy Department, Research and Early Development, Cardiovascular, Renal, and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
- School of Cardiovascular and Metabolic Medicine & Sciences, King’s College London, London, United Kingdom
| | - Amy Pointon
- Safety Sciences, Clinical Pharmacology & Safety Sciences, R&D, AstraZeneca, Cambridge, United Kingdom
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7
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Liu L, Zhou K, Liu X, Hua Y, Wang H, Li Y. The interplay between cardiac dyads and mitochondria regulated the calcium handling in cardiomyocytes. Front Physiol 2022; 13:1013817. [PMID: 36531185 PMCID: PMC9755166 DOI: 10.3389/fphys.2022.1013817] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 11/24/2022] [Indexed: 11/15/2023] Open
Abstract
Calcium mishandling and mitochondrial dysfunction have been increasingly recognized as significant factors involved in the progression procedure of cardiomyopathy. Ca2+ mishandling could cause calcium-triggered arrhythmias, which could enhance force development and ATP consumption. Mitochondrial disorganization and dysfunction in cardiomyopathy could disturb the balance of energy catabolic and anabolic procedure. Close spatial localization and arrangement of structural among T-tubule, sarcoplasmic reticulum, mitochondria are important for Ca2+ handling. So that, we illustrate the regulating network between calcium handling and mitochondrial homeostasis, as well as its intracellular mechanisms in this review, which would be worthy to develop novel therapeutic strategy and restore the function of injured cardiomyocytes.
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Affiliation(s)
| | | | | | | | - Hua Wang
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Yifei Li
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
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8
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Rossi D, Pierantozzi E, Amadsun DO, Buonocore S, Rubino EM, Sorrentino V. The Sarcoplasmic Reticulum of Skeletal Muscle Cells: A Labyrinth of Membrane Contact Sites. Biomolecules 2022; 12:488. [PMID: 35454077 PMCID: PMC9026860 DOI: 10.3390/biom12040488] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/14/2022] [Accepted: 03/18/2022] [Indexed: 12/17/2022] Open
Abstract
The sarcoplasmic reticulum of skeletal muscle cells is a highly ordered structure consisting of an intricate network of tubules and cisternae specialized for regulating Ca2+ homeostasis in the context of muscle contraction. The sarcoplasmic reticulum contains several proteins, some of which support Ca2+ storage and release, while others regulate the formation and maintenance of this highly convoluted organelle and mediate the interaction with other components of the muscle fiber. In this review, some of the main issues concerning the biology of the sarcoplasmic reticulum will be described and discussed; particular attention will be addressed to the structure and function of the two domains of the sarcoplasmic reticulum supporting the excitation-contraction coupling and Ca2+-uptake mechanisms.
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Affiliation(s)
- Daniela Rossi
- Department of Molecular and Developmental Medicine, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy; (E.P.); (D.O.A.); (S.B.); (E.M.R.); (V.S.)
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9
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Dixon RE. Nanoscale Organization, Regulation, and Dynamic Reorganization of Cardiac Calcium Channels. Front Physiol 2022; 12:810408. [PMID: 35069264 PMCID: PMC8769284 DOI: 10.3389/fphys.2021.810408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 11/30/2021] [Indexed: 12/19/2022] Open
Abstract
The architectural specializations and targeted delivery pathways of cardiomyocytes ensure that L-type Ca2+ channels (CaV1.2) are concentrated on the t-tubule sarcolemma within nanometers of their intracellular partners the type 2 ryanodine receptors (RyR2) which cluster on the junctional sarcoplasmic reticulum (jSR). The organization and distribution of these two groups of cardiac calcium channel clusters critically underlies the uniform contraction of the myocardium. Ca2+ signaling between these two sets of adjacent clusters produces Ca2+ sparks that in health, cannot escalate into Ca2+ waves because there is sufficient separation of adjacent clusters so that the release of Ca2+ from one RyR2 cluster or supercluster, cannot activate and sustain the release of Ca2+ from neighboring clusters. Instead, thousands of these Ca2+ release units (CRUs) generate near simultaneous Ca2+ sparks across every cardiomyocyte during the action potential when calcium induced calcium release from RyR2 is stimulated by depolarization induced Ca2+ influx through voltage dependent CaV1.2 channel clusters. These sparks summate to generate a global Ca2+ transient that activates the myofilaments and thus the electrical signal of the action potential is transduced into a functional output, myocardial contraction. To generate more, or less contractile force to match the hemodynamic and metabolic demands of the body, the heart responds to β-adrenergic signaling by altering activity of calcium channels to tune excitation-contraction coupling accordingly. Recent accumulating evidence suggests that this tuning process also involves altered expression, and dynamic reorganization of CaV1.2 and RyR2 channels on their respective membranes to control the amplitude of Ca2+ entry, SR Ca2+ release and myocardial function. In heart failure and aging, altered distribution and reorganization of these key Ca2+ signaling proteins occurs alongside architectural remodeling and is thought to contribute to impaired contractile function. In the present review we discuss these latest developments, their implications, and future questions to be addressed.
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Affiliation(s)
- Rose E Dixon
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA, United States
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10
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Hou Y, Bai J, Shen X, de Langen O, Li A, Lal S, Dos Remedios CG, Baddeley D, Ruygrok PN, Soeller C, Crossman DJ. Nanoscale Organisation of Ryanodine Receptors and Junctophilin-2 in the Failing Human Heart. Front Physiol 2021; 12:724372. [PMID: 34690801 PMCID: PMC8531480 DOI: 10.3389/fphys.2021.724372] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 09/03/2021] [Indexed: 11/16/2022] Open
Abstract
The disrupted organisation of the ryanodine receptors (RyR) and junctophilin (JPH) is thought to underpin the transverse tubule (t-tubule) remodelling in a failing heart. Here, we assessed the nanoscale organisation of these two key proteins in the failing human heart. Recently, an advanced feature of the t-tubule remodelling identified large flattened t-tubules called t-sheets, that were several microns wide. Previously, we reported that in the failing heart, the dilated t-tubules up to ~1 μm wide had increased collagen, and we hypothesised that the t-sheets would also be associated with collagen deposits. Direct stochastic optical reconstruction microscopy (dSTORM), confocal microscopy, and western blotting were used to evaluate the cellular distribution of excitation-contraction structures in the cardiac myocytes from patients with idiopathic dilated cardiomyopathy (IDCM) compared to myocytes from the non-failing (NF) human heart. The dSTORM imaging of RyR and JPH found no difference in the colocalisation between IDCM and NF myocytes, but there was a higher colocalisation at the t-tubule and sarcolemma compared to the corbular regions. Western blots revealed no change in the JPH expression but did identify a ~50% downregulation of RyR (p = 0.02). The dSTORM imaging revealed a trend for the smaller t-tubular RyR clusters (~24%) and reduced the t-tubular RyR cluster density (~35%) that resulted in a 50% reduction of t-tubular RyR tetramers in the IDCM myocytes (p < 0.01). Confocal microscopy identified the t-sheets in all the IDCM hearts examined and found that they are associated with the reticular collagen fibres within the lumen. However, the size and density of the RyR clusters were similar in the myocyte regions associated with t-sheets and t-tubules. T-tubule remodelling is associated with a reduced RyR expression that may contribute to the reduced excitation-contraction coupling in the failing human heart.
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Affiliation(s)
- Yufeng Hou
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Jizhong Bai
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Xin Shen
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Oscar de Langen
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Amy Li
- Department of Pharmacy and Biomedical Science, Health and Engineering, La Trobe University, Bendigo, VIC, Australia
| | - Sean Lal
- Faculty of Medicine and Science, University of Sydney, Sydney, NSW, Australia
| | | | - David Baddeley
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Peter N Ruygrok
- Department of Cardiology, Auckland City Hospital, Auckland, New Zealand
| | | | - David J Crossman
- Department of Physiology, University of Auckland, Auckland, New Zealand
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11
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Setterberg IE, Le C, Frisk M, Li J, Louch WE. The Physiology and Pathophysiology of T-Tubules in the Heart. Front Physiol 2021; 12:718404. [PMID: 34566684 PMCID: PMC8458775 DOI: 10.3389/fphys.2021.718404] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/07/2021] [Indexed: 12/18/2022] Open
Abstract
In cardiomyocytes, invaginations of the sarcolemmal membrane called t-tubules are critically important for triggering contraction by excitation-contraction (EC) coupling. These structures form functional junctions with the sarcoplasmic reticulum (SR), and thereby enable close contact between L-type Ca2+ channels (LTCCs) and Ryanodine Receptors (RyRs). This arrangement in turn ensures efficient triggering of Ca2+ release, and contraction. While new data indicate that t-tubules are capable of exhibiting compensatory remodeling, they are also widely reported to be structurally and functionally compromised during disease, resulting in disrupted Ca2+ homeostasis, impaired systolic and/or diastolic function, and arrhythmogenesis. This review summarizes these findings, while highlighting an emerging appreciation of the distinct roles of t-tubules in the pathophysiology of heart failure with reduced and preserved ejection fraction (HFrEF and HFpEF). In this context, we review current understanding of the processes underlying t-tubule growth, maintenance, and degradation, underscoring the involvement of a variety of regulatory proteins, including junctophilin-2 (JPH2), amphiphysin-2 (BIN1), caveolin-3 (Cav3), and newer candidate proteins. Upstream regulation of t-tubule structure/function by cardiac workload and specifically ventricular wall stress is also discussed, alongside perspectives for novel strategies which may therapeutically target these mechanisms.
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Affiliation(s)
- Ingunn E Setterberg
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Christopher Le
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Michael Frisk
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Jia Li
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
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