1
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Shen X, van den Brink J, Bergan-Dahl A, Kolstad TR, Norden ES, Hou Y, Laasmaa M, Aguilar-Sanchez Y, Quick AP, Espe EKS, Sjaastad I, Wehrens XHT, Edwards AG, Soeller C, Louch WE. Prolonged β-adrenergic stimulation disperses ryanodine receptor clusters in cardiomyocytes. eLife 2022; 11:77725. [PMID: 35913125 PMCID: PMC9410709 DOI: 10.7554/elife.77725] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 07/31/2022] [Indexed: 11/17/2022] Open
Abstract
Ryanodine receptors (RyRs) exhibit dynamic arrangements in cardiomyocytes, and we previously showed that ‘dispersion’ of RyR clusters disrupts Ca2+ homeostasis during heart failure (HF) (Kolstad et al., eLife, 2018). Here, we investigated whether prolonged β-adrenergic stimulation, a hallmark of HF, promotes RyR cluster dispersion and examined the underlying mechanisms. We observed that treatment of healthy rat cardiomyocytes with isoproterenol for 1 hr triggered progressive fragmentation of RyR clusters. Pharmacological inhibition of Ca2+/calmodulin-dependent protein kinase II (CaMKII) reversed these effects, while cluster dispersion was reproduced by specific activation of CaMKII, and in mice with constitutively active Ser2814-RyR. A similar role of protein kinase A (PKA) in promoting RyR cluster fragmentation was established by employing PKA activation or inhibition. Progressive cluster dispersion was linked to declining Ca2+ spark fidelity and magnitude, and slowed release kinetics from Ca2+ propagation between more numerous RyR clusters. In healthy cells, this served to dampen the stimulatory actions of β-adrenergic stimulation over the longer term and protect against pro-arrhythmic Ca2+ waves. However, during HF, RyR dispersion was linked to impaired Ca2+ release. Thus, RyR localization and function are intimately linked via channel phosphorylation by both CaMKII and PKA, which, while finely tuned in healthy cardiomyocytes, underlies impaired cardiac function during pathology.
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Affiliation(s)
- Xin Shen
- Institute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
| | | | - Anna Bergan-Dahl
- Institute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
| | - Terje R Kolstad
- Insitute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
| | | | - Yufeng Hou
- KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Martin Laasmaa
- Institute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
| | - Yuriana Aguilar-Sanchez
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, United States
| | - Ann Pepper Quick
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, United States
| | | | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
| | - Xander H T Wehrens
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, United States
| | | | | | - William Edward Louch
- Institute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
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2
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Molecular, Subcellular, and Arrhythmogenic Mechanisms in Genetic RyR2 Disease. Biomolecules 2022; 12:biom12081030. [PMID: 35892340 PMCID: PMC9394283 DOI: 10.3390/biom12081030] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/22/2022] [Accepted: 07/24/2022] [Indexed: 11/17/2022] Open
Abstract
The ryanodine receptor (RyR2) has a critical role in controlling Ca2+ release from the sarcoplasmic reticulum (SR) throughout the cardiac cycle. RyR2 protein has multiple functional domains with specific roles, and four of these RyR2 protomers are required to form the quaternary structure that comprises the functional channel. Numerous mutations in the gene encoding RyR2 protein have been identified and many are linked to a wide spectrum of arrhythmic heart disease. Gain of function mutations (GoF) result in a hyperactive channel that causes excessive spontaneous SR Ca2+ release. This is the predominant cause of the inherited syndrome catecholaminergic polymorphic ventricular tachycardia (CPVT). Recently, rare hypoactive loss of function (LoF) mutations have been identified that produce atypical effects on cardiac Ca2+ handling that has been termed calcium release deficiency syndrome (CRDS). Aberrant Ca2+ release resulting from both GoF and LoF mutations can result in arrhythmias through the Na+/Ca2+ exchange mechanism. This mini-review discusses recent findings regarding the role of RyR2 domains and endogenous regulators that influence RyR2 gating normally and with GoF/LoF mutations. The arrhythmogenic consequences of GoF/LoF mutations will then be discussed at the macromolecular and cellular level.
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3
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Colman MA, Alvarez-Lacalle E, Echebarria B, Sato D, Sutanto H, Heijman J. Multi-Scale Computational Modeling of Spatial Calcium Handling From Nanodomain to Whole-Heart: Overview and Perspectives. Front Physiol 2022; 13:836622. [PMID: 35370783 PMCID: PMC8964409 DOI: 10.3389/fphys.2022.836622] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 01/31/2022] [Indexed: 11/13/2022] Open
Abstract
Regulation of intracellular calcium is a critical component of cardiac electrophysiology and excitation-contraction coupling. The calcium spark, the fundamental element of the intracellular calcium transient, is initiated in specialized nanodomains which co-locate the ryanodine receptors and L-type calcium channels. However, calcium homeostasis is ultimately regulated at the cellular scale, by the interaction of spatially separated but diffusively coupled nanodomains with other sub-cellular and surface-membrane calcium transport channels with strong non-linear interactions; and cardiac electrophysiology and arrhythmia mechanisms are ultimately tissue-scale phenomena, regulated by the interaction of a heterogeneous population of coupled myocytes. Recent advances in imaging modalities and image-analysis are enabling the super-resolution reconstruction of the structures responsible for regulating calcium homeostasis, including the internal structure of nanodomains themselves. Extrapolating functional and imaging data from the nanodomain to the whole-heart is non-trivial, yet essential for translational insight into disease mechanisms. Computational modeling has important roles to play in relating structural and functional data at the sub-cellular scale and translating data across the scales. This review covers recent methodological advances that enable image-based modeling of the single nanodomain and whole cardiomyocyte, as well as the development of multi-scale simulation approaches to integrate data from nanometer to whole-heart. Firstly, methods to overcome the computational challenges of simulating spatial calcium dynamics in the nanodomain are discussed, including image-based modeling at this scale. Then, recent whole-cell models, capable of capturing a range of different structures (such as the T-system and mitochondria) and cellular heterogeneity/variability are discussed at two different levels of discretization. Novel methods to integrate the models and data across the scales and simulate stochastic dynamics in tissue-scale models are then discussed, enabling elucidation of the mechanisms by which nanodomain remodeling underlies arrhythmia and contractile dysfunction. Perspectives on model differences and future directions are provided throughout.
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Affiliation(s)
- Michael A. Colman
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | | | - Blas Echebarria
- Departament de Fisica, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain
| | - Daisuke Sato
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Henry Sutanto
- Department of Physiology and Pharmacology, State University of New York Downstate Health Sciences University, Brooklyn, NY, United States
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
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4
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Louch WE, Perdreau-Dahl H, Edwards AG. Image-Driven Modeling of Nanoscopic Cardiac Function: Where Have We Come From, and Where Are We Going? Front Physiol 2022; 13:834211. [PMID: 35356084 PMCID: PMC8959215 DOI: 10.3389/fphys.2022.834211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 01/31/2022] [Indexed: 11/24/2022] Open
Abstract
Complementary developments in microscopy and mathematical modeling have been critical to our understanding of cardiac excitation-contraction coupling. Historically, limitations imposed by the spatial or temporal resolution of imaging methods have been addressed through careful mathematical interrogation. Similarly, limitations imposed by computational power have been addressed by imaging macroscopic function in large subcellular domains or in whole myocytes. As both imaging resolution and computational tractability have improved, the two approaches have nearly merged in terms of the scales that they can each be used to interrogate. With this review we will provide an overview of these advances and their contribution to understanding ventricular myocyte function, including exciting developments over the last decade. We specifically focus on experimental methods that have pushed back limits of either spatial or temporal resolution of nanoscale imaging (e.g., DNA-PAINT), or have permitted high resolution imaging on large cellular volumes (e.g., serial scanning electron microscopy). We also review the progression of computational approaches used to integrate and interrogate these new experimental data sources, and comment on near-term advances that may unify understanding of the underlying biology. Finally, we comment on several outstanding questions in cardiac physiology that stand to benefit from a concerted and complementary application of these new experimental and computational methods.
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Affiliation(s)
- William E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Harmonie Perdreau-Dahl
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
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5
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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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6
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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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7
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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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8
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Munro ML, van Hout I, Aitken-Buck HM, Sugunesegran R, Bhagwat K, Davis PJ, Lamberts RR, Coffey S, Soeller C, Jones PP. Human Atrial Fibrillation Is Not Associated With Remodeling of Ryanodine Receptor Clusters. Front Cell Dev Biol 2021; 9:633704. [PMID: 33718369 PMCID: PMC7947344 DOI: 10.3389/fcell.2021.633704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 02/08/2021] [Indexed: 12/02/2022] Open
Abstract
The release of Ca2+ by ryanodine receptor (RyR2) channels is critical for cardiac function. However, abnormal RyR2 activity has been linked to the development of arrhythmias, including increased spontaneous Ca2+ release in human atrial fibrillation (AF). Clustering properties of RyR2 have been suggested to alter the activity of the channel, with remodeling of RyR2 clusters identified in pre-clinical models of AF and heart failure. Whether such remodeling occurs in human cardiac disease remains unclear. This study aimed to investigate the nanoscale organization of RyR2 clusters in AF patients – the first known study to examine this potential remodeling in diseased human cardiomyocytes. Right atrial appendage from cardiac surgery patients with paroxysmal or persistent AF, or without AF (non-AF) were examined using super-resolution (dSTORM) imaging. Significant atrial dilation and cardiomyocyte hypertrophy was observed in persistent AF patients compared to non-AF, with these two parameters significantly correlated. Interestingly, the clustering properties of RyR2 were remarkably unaltered in the AF patients. No significant differences were identified in cluster size (mean ∼18 RyR2 channels), density or channel packing within clusters between patient groups. The spatial organization of clusters throughout the cardiomyocyte was also unchanged across the groups. RyR2 clustering properties did not significantly correlate with patient characteristics. In this first study to examine nanoscale RyR2 organization in human cardiac disease, these findings indicate that RyR2 cluster remodeling is not an underlying mechanism contributing to altered channel function and subsequent arrhythmogenesis in human AF.
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Affiliation(s)
- Michelle L Munro
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Isabelle van Hout
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Hamish M Aitken-Buck
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | | | - Krishna Bhagwat
- Department of Cardiothoracic Surgery, Dunedin Hospital, Dunedin, New Zealand
| | - Philip J Davis
- Department of Cardiothoracic Surgery, Dunedin Hospital, Dunedin, New Zealand
| | - Regis R Lamberts
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Sean Coffey
- Department of Medicine and HeartOtago, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Christian Soeller
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | - Peter P Jones
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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9
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Götz R, Kunz TC, Fink J, Solger F, Schlegel J, Seibel J, Kozjak-Pavlovic V, Rudel T, Sauer M. Nanoscale imaging of bacterial infections by sphingolipid expansion microscopy. Nat Commun 2020; 11:6173. [PMID: 33268771 PMCID: PMC7710728 DOI: 10.1038/s41467-020-19897-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 11/05/2020] [Indexed: 12/20/2022] Open
Abstract
Expansion microscopy (ExM) enables super-resolution imaging of proteins and nucleic acids on conventional microscopes. However, imaging of details of the organization of lipid bilayers by light microscopy remains challenging. We introduce an unnatural short-chain azide- and amino-modified sphingolipid ceramide, which upon incorporation into membranes can be labeled by click chemistry and linked into hydrogels, followed by 4× to 10× expansion. Confocal and structured illumination microscopy (SIM) enable imaging of sphingolipids and their interactions with proteins in the plasma membrane and membrane of intracellular organelles with a spatial resolution of 10–20 nm. As our functionalized sphingolipids accumulate efficiently in pathogens, we use sphingolipid ExM to investigate bacterial infections of human HeLa229 cells by Neisseria gonorrhoeae, Chlamydia trachomatis and Simkania negevensis with a resolution so far only provided by electron microscopy. In particular, sphingolipid ExM allows us to visualize the inner and outer membrane of intracellular bacteria and determine their distance to 27.6 ± 7.7 nm. Imaging of lipid bilayers using light microscopy is challenging. Here the authors label cells using a short chain click-compatible ceramide to visualize mammalian and bacterial membranes with expansion microscopy.
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Affiliation(s)
- Ralph Götz
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Tobias C Kunz
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Julian Fink
- Institute for Organic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Franziska Solger
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Jan Schlegel
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Jürgen Seibel
- Institute for Organic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Vera Kozjak-Pavlovic
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Thomas Rudel
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
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10
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Klimas A, Zhao Y. Expansion Microscopy: Toward Nanoscale Imaging of a Diverse Range of Biomolecules. ACS NANO 2020; 14:7689-7695. [PMID: 32628828 PMCID: PMC7456618 DOI: 10.1021/acsnano.0c04374] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Expansion microscopy (ExM) has become a powerful imaging tool for visualizing the nanoscale organization of protein and nucleic acid targets in cells and tissues using only a conventional microscope. Until recently, current ExM approaches have had limited applicability to imaging other biomolecules, such as lipids and small molecules. With the new TRITON probes reported by Wen et al. in this issue of ACS Nano, ExM can now be used to perform nanoscale imaging of the cytoskeleton and lipid membranes. In this Perspective, we offer a brief overview of recent developments in ExM, with a focus on biomolecule anchoring and labeling strategies that target a wide range of biomolecules to the water-swellable polymer formed in situ, a key step that ensures biomolecules or labels of interest are separated in space and can be resolved on a conventional microscope. In addition to these new advancements, we discuss challenges and future directions in this exciting field.
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Affiliation(s)
- Aleksandra Klimas
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Yongxin Zhao
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
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11
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Wen G, Vanheusden M, Acke A, Valli D, Neely RK, Leen V, Hofkens J. Evaluation of Direct Grafting Strategies via Trivalent Anchoring for Enabling Lipid Membrane and Cytoskeleton Staining in Expansion Microscopy. ACS NANO 2020; 14:7860-7867. [PMID: 32176475 DOI: 10.1021/acsnano.9b09259] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Super-resolution fluorescence microscopy is a key tool in the elucidation of biological fine structures, providing insights into the distribution and interactions of biomolecular complexes down to the nanometer scale. Expansion microscopy is a recently developed approach for achieving nanoscale resolution on a conventional microscope. Here, biological samples are embedded in an isotropically swollen hydrogel. This physical expansion of the sample allows imaging with resolutions down to the tens-of-nanometers. However, because of the requirement that fluorescent labels are covalently bound to the hydrogel, standard, small-molecule targeting of fluorophores has proven incompatible with expansion microscopy. Here, we show a chemical linking approach that enables direct, covalent grafting of a targeting molecule and fluorophore to the hydrogel in expansion microscopy. We show application of this series of molecules in the antibody-free targeting of the cell cytoskeleton and in an example of lipid membrane staining for expansion microscopy. Furthermore, using this trivalent linker strategy, we demonstrate the benefit of introducing fluorescent labels post-expansion by visualizing an immunostaining through fluorescent oligonucleotide hybridization after expanding the polymer. Our probes allow different labeling approaches that are compatible with expansion microscopy.
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Affiliation(s)
- Gang Wen
- Department of Chemistry, KU Leuven, Leuven, 3001, Belgium
| | | | - Aline Acke
- Department of Chemistry, KU Leuven, Leuven, 3001, Belgium
| | - Donato Valli
- Department of Chemistry, KU Leuven, Leuven, 3001, Belgium
| | - Robert K Neely
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Volker Leen
- Department of Chemistry, KU Leuven, Leuven, 3001, Belgium
| | - Johan Hofkens
- Department of Chemistry, KU Leuven, Leuven, 3001, Belgium
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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12
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Faried M, Suga K, Okamoto Y, Shameli K, Miyake M, Umakoshi H. Membrane Surface-Enhanced Raman Spectroscopy for Cholesterol-Modified Lipid Systems: Effect of Gold Nanoparticle Size. ACS OMEGA 2019; 4:13687-13695. [PMID: 31497686 PMCID: PMC6714513 DOI: 10.1021/acsomega.9b01073] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 08/05/2019] [Indexed: 05/19/2023]
Abstract
A gold nanoparticle (AuNP) has a localized surface plasmon resonance peak depending on its size, which is often utilized for surface-enhanced Raman scattering (SERS). To obtain information on the cholesterol (Chol)-incorporated lipid membranes by SERS, AuNPs (5, 100 nm) were first functionalized by 1-octanethiol and then modified by lipids (AuNP@lipid). In membrane surface-enhanced Raman spectroscopy (MSERS), both signals from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and Chol molecules were enhanced, depending on preparation conditions (size of AuNPs and lipid/AuNP ratio). The enhancement factors (EFs) were calculated to estimate the efficiency of AuNPs on Raman enhancement. The size of AuNP100nm@lipid was 152.0 ± 12.8 nm, which showed an surface enhancement Raman spectrum with an EF2850 value of 111 ± 9. The size of AuNP5nm@lipid prepared with a lipid/AuNP ratio of 1.38 × 104 (lipid molecule/particle) was 275.3 ± 20.2 nm, which showed the highest enhancement with an EF2850 value of 131 ± 21. On the basis of fluorescent probe analyses, the membrane fluidity and polarity of AuNP@lipid were almost similar to DOPC/Chol liposome, indicating an intact membrane of DOPC/Chol after modification with AuNPs. Finally, the membrane properties of AuNP@lipid systems were also discussed on the basis of the obtained MSERS signals.
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Affiliation(s)
- Miftah Faried
- Division of Chemical
Engineering, Graduate School of Engineering Science, Osaka University, 1-3
Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan
| | - Keishi Suga
- Division of Chemical
Engineering, Graduate School of Engineering Science, Osaka University, 1-3
Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan
- E-mail: . Phone: +81-6-6850-6286. Fax: +81-6-6850-6286 (K.S.)
| | - Yukihiro Okamoto
- Division of Chemical
Engineering, Graduate School of Engineering Science, Osaka University, 1-3
Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan
| | - Kamyar Shameli
- Department of Environment and Green Technology, Malaysia−Japan
International Institute of Technology, Universiti
Teknologi Malaysia, Jalan Sultan Yahya Petra, Kuala Lumpur 54100, Malaysia
| | - Mikio Miyake
- Department of Environment and Green Technology, Malaysia−Japan
International Institute of Technology, Universiti
Teknologi Malaysia, Jalan Sultan Yahya Petra, Kuala Lumpur 54100, Malaysia
- School
of Materials Science, Japan Advanced Institute
of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Hiroshi Umakoshi
- Division of Chemical
Engineering, Graduate School of Engineering Science, Osaka University, 1-3
Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan
- E-mail: . Phone: +81-6-6850-6287. Fax: +81-6-6850-6286 (H.U.)
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