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Birkedal R, Laasmaa M, Branovets J, Vendelin M. Ontogeny of cardiomyocytes: ultrastructure optimization to meet the demand for tight communication in excitation-contraction coupling and energy transfer. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210321. [PMID: 36189816 PMCID: PMC9527910 DOI: 10.1098/rstb.2021.0321] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The ontogeny of the heart describes its development from the fetal to the adult stage. In newborn mammals, blood pressure and thus cardiac performance are relatively low. The cardiomyocytes are thin, and with a central core of mitochondria surrounded by a ring of myofilaments, while the sarcoplasmic reticulum (SR) is sparse. During development, as blood pressure and performance increase, the cardiomyocytes become more packed with structures involved in excitation–contraction (e-c) coupling (SR and myofilaments) and the generation of ATP (mitochondria) to fuel the contraction. In parallel, the e-c coupling relies increasingly on calcium fluxes through the SR, while metabolism relies increasingly on fatty acid oxidation. The development of transverse tubules and SR brings channels and transporters interacting via calcium closer to each other and is crucial for e-c coupling. However, for energy transfer, it may seem counterintuitive that the increased structural density restricts the overall ATP/ADP diffusion. In this review, we discuss how this is because of the organization of all these structures forming modules. Although the overall diffusion across modules is more restricted, the energy transfer within modules is fast. A few studies suggest that in failing hearts this modular design is disrupted, and this may compromise intracellular energy transfer. This article is part of the theme issue ‘The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease’.
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Affiliation(s)
- Rikke Birkedal
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Akadeemia 15, room SCI-218, 12618 Tallinn, Estonia
| | - Martin Laasmaa
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Akadeemia 15, room SCI-218, 12618 Tallinn, Estonia
| | - Jelena Branovets
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Akadeemia 15, room SCI-218, 12618 Tallinn, Estonia
| | - Marko Vendelin
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Akadeemia 15, room SCI-218, 12618 Tallinn, Estonia
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2
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Lygate CA. The Pitfalls of in vivo Cardiac Physiology in Genetically Modified Mice - Lessons Learnt the Hard Way in the Creatine Kinase System. Front Physiol 2021; 12:685064. [PMID: 34054587 PMCID: PMC8160301 DOI: 10.3389/fphys.2021.685064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 04/22/2021] [Indexed: 12/30/2022] Open
Abstract
In order to fully understand gene function, at some point, it is necessary to study the effects in an intact organism. The creation of the first knockout mouse in the late 1980's gave rise to a revolution in the field of integrative physiology that continues to this day. There are many complex choices when selecting a strategy for genetic modification, some of which will be touched on in this review, but the principal focus is to highlight the potential problems and pitfalls arising from the interpretation of in vivo cardiac phenotypes. As an exemplar, we will scrutinize the field of cardiac energetics and the attempts to understand the role of the creatine kinase (CK) energy buffering and transport system in the intact organism. This story highlights the confounding effects of genetic background, sex, and age, as well as the difficulties in interpreting knockout models in light of promiscuous proteins and metabolic redundancy. It will consider the dose-dependent effects and unintended consequences of transgene overexpression, and the need for experimental rigour in the context of in vivo phenotyping techniques. It is intended that this review will not only bring clarity to the field of cardiac energetics, but also aid the non-expert in evaluating and critically assessing data arising from in vivo genetic modification.
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Affiliation(s)
- Craig A Lygate
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
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Telomere attrition and dysfunction: a potential trigger of the progeroid phenotype in nijmegen breakage syndrome. Aging (Albany NY) 2020; 12:12342-12375. [PMID: 32564008 PMCID: PMC7343506 DOI: 10.18632/aging.103453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 05/27/2020] [Indexed: 12/17/2022]
Abstract
Background: Nibrin, as part of the NBN/MRE11/RAD50 complex, is mutated in Nijmegen breakage syndrome (NBS), which leads to impaired DNA damage response and lymphoid malignancy. Results: Telomere length (TL) was markedly reduced in homozygous patients (and comparably so in all chromosomes) by ~40% (qPCR) and was slightly reduced in NBS heterozygotes older than 30 years (~25% in qPCR), in accordance with the respective cancer rates. Humanized cancer-free NBS mice had normal TL. Telomere elongation was inducible by telomerase and/or alternative telomere lengthening but was associated with abnormal expression of telomeric genes involved in aging and/or cell growth. Lymphoblastoid cells from NBS patients with long survival times (>12 years) displayed the shortest telomeres and low caspase 7 activity. Conclusions: NBS is a secondary telomeropathy. The two-edged sword of telomere attrition enhances the cancer-prone situation in NBS but can also lead to a relatively stable cellular phenotype in tumor survivors. Results suggest a modular model for progeroid syndromes with abnormal expression of telomeric genes as a molecular basis. Methods: We studied TL and function in 38 homozygous individuals, 27 heterozygotes, one homozygous fetus, six NBS lymphoblastoid cell lines, and humanized NBS mice, all with the same founder NBN mutation: c.657_661del5.
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Aksentijević D, Zervou S, Eykyn TR, McAndrew DJ, Wallis J, Schneider JE, Neubauer S, Lygate CA. Age-Dependent Decline in Cardiac Function in Guanidinoacetate- N-Methyltransferase Knockout Mice. Front Physiol 2020; 10:1535. [PMID: 32038270 PMCID: PMC6985570 DOI: 10.3389/fphys.2019.01535] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 12/05/2019] [Indexed: 01/15/2023] Open
Abstract
Aim Guanidinoacetate N-methyltransferase (GAMT) is the second essential enzyme in creatine (Cr) biosynthesis. Short-term Cr deficiency is metabolically well tolerated as GAMT–/– mice exhibit normal exercise capacity and response to ischemic heart failure. However, we hypothesized long-term consequences of Cr deficiency and/or accumulation of the Cr precursor guanidinoacetate (GA). Methods Cardiac function and metabolic profile were studied in GAMT–/– mice >1 year. Results In vivo LV catheterization revealed lower heart rate and developed pressure in aging GAMT–/– but normal lung weight and survival versus age-matched controls. Electron microscopy indicated reduced mitochondrial volume density in GAMT–/– hearts (P < 0.001), corroborated by lower mtDNA copy number (P < 0.004), and citrate synthase activity (P < 0.05), however, without impaired mitochondrial respiration. Furthermore, myocardial energy stores and key ATP homeostatic enzymes were barely altered, while pathology was unrelated to oxidative stress since superoxide production and protein carbonylation were unaffected. Gene expression of PGC-1α was 2.5-fold higher in GAMT–/– hearts while downstream genes were not activated, implicating a dysfunction in mitochondrial biogenesis signaling. This was normalized by 10 days of dietary Cr supplementation, as were all in vivo functional parameters, however, it was not possible to differentiate whether relief from Cr deficiency or GA toxicity was causative. Conclusion Long-term Cr deficiency in GAMT–/– mice reduces mitochondrial volume without affecting respiratory function, most likely due to impaired biogenesis. This is associated with hemodynamic changes without evidence of heart failure, which may represent an acceptable functional compromise in return for reduced energy demand in aging mice.
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Affiliation(s)
- Dunja Aksentijević
- Radcliffe Department of Medicine, Division of Cardiovascular Medicine and Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Sevasti Zervou
- Radcliffe Department of Medicine, Division of Cardiovascular Medicine and Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Thomas R Eykyn
- Department of Imaging Chemistry and Biology, School of Biomedical Engineering and Imaging Sciences, King's College London, St Thomas' Hospital, London, United Kingdom
| | - Debra J McAndrew
- Radcliffe Department of Medicine, Division of Cardiovascular Medicine and Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Julie Wallis
- Radcliffe Department of Medicine, Division of Cardiovascular Medicine and Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Jurgen E Schneider
- Experimental and Preclinical Imaging Centre, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Stefan Neubauer
- Radcliffe Department of Medicine, Division of Cardiovascular Medicine and Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Craig A Lygate
- Radcliffe Department of Medicine, Division of Cardiovascular Medicine and Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
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Jia D, Xiong L, Yu X, Chen X, Wang T, Chen AF, Chai Y, Zhu Z, Zhang C. Cardioprotective mechanism study of salvianic acid A sodium based on a proteome microarray approach and metabolomic profiling of rat serum after myocardial infarction. Mol Omics 2019; 15:271-279. [PMID: 31099812 DOI: 10.1039/c9mo00005d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Salvianic acid A sodium (SAAS), derived from a well-known herbal medicine Danshen (Salvia miltiorrhiza), is a new drug involved in phase I clinical trials in China for the treatment of coronary heart disease and stable angina pectoris. However, the direct binding protein(s) of SAAS are not understood and the broader cardioprotective effects as well as the underlying mechanisms remain to be further elucidated. In this study, Sprague-Dawley rats were subjected to left anterior descending artery ligation to investigate the cardioprotective effect of SAAS against myocardial infarction (MI). Moreover, a human proteome microarray was used to identify the direct binding proteins of SAAS, which was further verified by metabolomic profiling of rat serum after MI using an ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) based approach. Our results demonstrated that SAAS significantly improved cardiac function and protected against MI-induced injury. In total, 370 proteins were identified to specifically bind SAAS and strikingly enriched in metabolic pathways. Rat serum metabolomic profiling identified 26 potential biomarkers including various glycerophospholipids (GPLs) and an array of fatty acids. Metabolic pathway analysis found increased phospholipid catabolism, sphingolipid metabolism and linoleic acid metabolism, decreased tryptophan metabolism, and impaired glycerophospholipid metabolism and primary bile acid biosynthesis in MI animals, while SAAS remarkably reversed these metabolic changes. SAAS may protect against myocardial infarction in rats by reversing multiple metabolic changes-induced by MI injury. Our findings will shed light on the cardioprotective mechanism of SAAS and aid its clinical use. Moreover, the SAAS-binding proteins identified by the proteome microarray are expected to be a valuable resource for its greater development.
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Affiliation(s)
- Dan Jia
- School of Pharmacy, Second Military Medical University, No. 325 Guohe Road, Shanghai 200433, China.
| | - Liyan Xiong
- School of Pharmacy, Second Military Medical University, No. 325 Guohe Road, Shanghai 200433, China. and School of Medicine, Shanghai University, Shanghai 200444, China
| | - Xuhong Yu
- Department of Pharmacy, The PLA 305 Hospital, Beijing 100017, China
| | - Xiaofei Chen
- School of Pharmacy, Second Military Medical University, No. 325 Guohe Road, Shanghai 200433, China.
| | - Tingfang Wang
- School of Pharmacy, Second Military Medical University, No. 325 Guohe Road, Shanghai 200433, China. and School of Medicine, Shanghai University, Shanghai 200444, China
| | - Alex F Chen
- School of Pharmacy, Second Military Medical University, No. 325 Guohe Road, Shanghai 200433, China. and Third Xiangya Hospital and the Institute of Vascular Disease and Translational Medicine, Central South University, Changsha 410008, China
| | - Yifeng Chai
- School of Pharmacy, Second Military Medical University, No. 325 Guohe Road, Shanghai 200433, China.
| | - Zhenyu Zhu
- School of Pharmacy, Second Military Medical University, No. 325 Guohe Road, Shanghai 200433, China.
| | - Chuan Zhang
- School of Pharmacy, Second Military Medical University, No. 325 Guohe Road, Shanghai 200433, China. and School of Medicine, Shanghai University, Shanghai 200444, China
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The creatine kinase system as a therapeutic target for myocardial ischaemia-reperfusion injury. Biochem Soc Trans 2018; 46:1119-1127. [PMID: 30242115 PMCID: PMC6195634 DOI: 10.1042/bst20170504] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 08/18/2018] [Accepted: 08/22/2018] [Indexed: 12/13/2022]
Abstract
Restoring blood flow following an acute myocardial infarction saves lives, but results in tissue damage due to ischaemia–reperfusion injury (I/R). Ameliorating this damage is a major research goal to improve recovery and reduce subsequent morbidity due to heart failure. Both the ischaemic and reperfusion phases represent crises of cellular energy provision in which the mitochondria play a central role. This mini-review will explore the rationale and therapeutic potential of augmenting the creatine kinase (CK) energy shuttle, which constitutes the primary short-term energy buffer and transport system in the cardiomyocyte. Proof-of-principle data from several transgenic mouse models have demonstrated robust cardioprotection by either raising myocardial creatine levels or by overexpressing specific CK isoforms. The effect on cardiac function, high-energy phosphates and myocardial injury will be discussed and possible directions for future research highlighted. We conclude that the CK system represents a viable target for therapeutic intervention in I/R injury; however, much needed translational studies will require the development of new pharmacological tools.
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Longitudinal imaging of the ageing mouse. Mech Ageing Dev 2016; 160:93-116. [PMID: 27530773 DOI: 10.1016/j.mad.2016.08.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 07/30/2016] [Accepted: 08/04/2016] [Indexed: 12/13/2022]
Abstract
Several non-invasive imaging techniques are used to investigate the effect of pathologies and treatments over time in mouse models. Each preclinical in vivo technique provides longitudinal and quantitative measurements of changes in tissues and organs, which are fundamental for the evaluation of alterations in phenotype due to pathologies, interventions and treatments. However, it is still unclear how these imaging modalities can be used to study ageing with mice models. Almost all age related pathologies in mice such as osteoporosis, arthritis, diabetes, cancer, thrombi, dementia, to name a few, can be imaged in vivo by at least one longitudinal imaging modality. These measurements are the basis for quantification of treatment effects in the development phase of a novel treatment prior to its clinical testing. Furthermore, the non-invasive nature of such investigations allows the assessment of different tissue and organ phenotypes in the same animal and over time, providing the opportunity to study the dysfunction of multiple tissues associated with the ageing process. This review paper aims to provide an overview of the applications of the most commonly used in vivo imaging modalities used in mouse studies: micro-computed-tomography, preclinical magnetic-resonance-imaging, preclinical positron-emission-tomography, preclinical single photon emission computed tomography, ultrasound, intravital microscopy, and whole body optical imaging.
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Simson P, Jepihhina N, Laasmaa M, Peterson P, Birkedal R, Vendelin M. Restricted ADP movement in cardiomyocytes: Cytosolic diffusion obstacles are complemented with a small number of open mitochondrial voltage-dependent anion channels. J Mol Cell Cardiol 2016; 97:197-203. [PMID: 27261153 DOI: 10.1016/j.yjmcc.2016.04.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 04/19/2016] [Indexed: 12/17/2022]
Abstract
Adequate intracellular energy transfer is crucial for proper cardiac function. In energy starved failing hearts, partial restoration of energy transfer can rescue mechanical performance. There are two types of diffusion obstacles that interfere with energy transfer from mitochondria to ATPases: mitochondrial outer membrane (MOM) with voltage-dependent anion channel (VDAC) permeable to small hydrophilic molecules and cytoplasmatic diffusion barriers grouping ATP-producers and -consumers. So far, there is no method developed to clearly distinguish the contributions of cytoplasmatic barriers and MOM to the overall diffusion restriction. Furthermore, the number of open VDACs in vivo remains unknown. The aim of this work was to establish the partitioning of intracellular diffusion obstacles in cardiomyocytes. We studied the response of mitochondrial oxidative phosphorylation of permeabilized rat cardiomyocytes to changes in extracellular ADP by recording 3D image stacks of NADH autofluorescence. Using cell-specific mathematical models, we determined the permeability of MOM and cytoplasmatic barriers. We found that only ~2% of VDACs are accessible to cytosolic ADP and cytoplasmatic diffusion barriers reduce the apparent diffusion coefficient by 6-10×. In cardiomyocytes, diffusion barriers in the cytoplasm and by the MOM restrict ADP/ATP diffusion to similar extents suggesting a major role of both barriers in energy transfer and other intracellular processes.
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Affiliation(s)
- Päivo Simson
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia
| | - Natalja Jepihhina
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia
| | - Martin Laasmaa
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia
| | - Pearu Peterson
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia
| | - Rikke Birkedal
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia
| | - Marko Vendelin
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia.
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Joncquel-Chevalier Curt M, Voicu PM, Fontaine M, Dessein AF, Porchet N, Mention-Mulliez K, Dobbelaere D, Soto-Ares G, Cheillan D, Vamecq J. Creatine biosynthesis and transport in health and disease. Biochimie 2015; 119:146-65. [DOI: 10.1016/j.biochi.2015.10.022] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 10/27/2015] [Indexed: 12/31/2022]
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Branovets J, Sepp M, Kotlyarova S, Jepihhina N, Sokolova N, Aksentijevic D, Lygate CA, Neubauer S, Vendelin M, Birkedal R. Unchanged mitochondrial organization and compartmentation of high-energy phosphates in creatine-deficient GAMT-/- mouse hearts. Am J Physiol Heart Circ Physiol 2013; 305:H506-20. [PMID: 23792673 DOI: 10.1152/ajpheart.00919.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Disruption of the creatine kinase (CK) system in hearts of CK-deficient mice leads to changes in the ultrastructure and regulation of mitochondrial respiration. We expected to see similar changes in creatine-deficient mice, which lack the enzyme guanidinoacetate methyltransferase (GAMT) to produce creatine. The aim of this study was to characterize the changes in cardiomyocyte mitochondrial organization, regulation of respiration, and intracellular compartmentation associated with GAMT deficiency. Three-dimensional mitochondrial organization was assessed by confocal microscopy. On populations of permeabilized cardiomyocytes, we recorded ADP and ATP kinetics of respiration, competition between mitochondria and pyruvate kinase for ADP produced by ATPases, ADP kinetics of endogenous pyruvate kinase, and ATP kinetics of ATPases. These data were analyzed by mathematical models to estimate intracellular compartmentation. Quantitative analysis of morphological and kinetic data as well as derived model fits showed no difference between GAMT-deficient and wild-type mice. We conclude that inactivation of the CK system by GAMT deficiency does not alter mitochondrial organization and intracellular compartmentation in relaxed cardiomyocytes. Thus, our results suggest that the healthy heart is able to preserve cardiac function at a basal level in the absence of CK-facilitated energy transfer without compromising intracellular organization and the regulation of mitochondrial energy homeostasis. This raises questions on the importance of the CK system as a spatial energy buffer in unstressed cardiomyocytes.
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Affiliation(s)
- Jelena Branovets
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Tallinn, Estonia; and
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11
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Lygate CA, Aksentijevic D, Dawson D, ten Hove M, Phillips D, de Bono JP, Medway DJ, Sebag-Montefiore L, Hunyor I, Channon KM, Clarke K, Zervou S, Watkins H, Balaban RS, Neubauer S. Living without creatine: unchanged exercise capacity and response to chronic myocardial infarction in creatine-deficient mice. Circ Res 2013; 112:945-55. [PMID: 23325497 DOI: 10.1161/circresaha.112.300725] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Creatine is thought to be involved in the spatial and temporal buffering of ATP in energetic organs such as heart and skeletal muscle. Creatine depletion affects force generation during maximal stimulation, while reduced levels of myocardial creatine are a hallmark of the failing heart, leading to the widely held view that creatine is important at high workloads and under conditions of pathological stress. OBJECTIVE We therefore hypothesised that the consequences of creatine-deficiency in mice would be impaired running capacity, and exacerbation of heart failure following myocardial infarction. METHODS AND RESULTS Surprisingly, mice with whole-body creatine deficiency due to knockout of the biosynthetic enzyme (guanidinoacetate N-methyltransferase [GAMT]) voluntarily ran just as fast and as far as controls (>10 km/night) and performed the same level of work when tested to exhaustion on a treadmill. Furthermore, survival following myocardial infarction was not altered, nor was subsequent left ventricular (LV) remodelling and development of chronic heart failure exacerbated, as measured by 3D-echocardiography and invasive hemodynamics. These findings could not be accounted for by compensatory adaptations, with no differences detected between WT and GAMT(-/-) proteomes. Alternative phosphotransfer mechanisms were explored; adenylate kinase activity was unaltered, and although GAMT(-/-) hearts accumulated the creatine precursor guanidinoacetate, this had negligible energy-transfer activity, while mitochondria retained near normal function. CONCLUSIONS Creatine-deficient mice show unaltered maximal exercise capacity and response to chronic myocardial infarction, and no obvious metabolic adaptations. Our results question the paradigm that creatine is essential for high workload and chronic stress responses in heart and skeletal muscle.
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Affiliation(s)
- Craig A Lygate
- Department of Cardiovascular Medicine, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford, UK.
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Mouse phenotyping with MRI. Methods Mol Biol 2011. [PMID: 21874500 DOI: 10.1007/978-1-61779-219-9_31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The field of mouse phenotyping with magnetic resonance imaging (MRI) is rapidly growing, motivated by the need for improved tools for characterizing and evaluating mouse models of human disease. Image results can provide important comparisons of human conditions with mouse disease models, evaluations of treatment, development or disease progression, as well as direction for histological or other investigations. Effective mouse MRI studies require attention to many aspects of experiment design. In this chapter, we provide details and discussion of important practical considerations: hardware requirements, mouse handling for in vivo imaging, specimen preparation for ex vivo imaging, sequence and contrast agent selection, study size, and quantitative image analysis. We focus particularly on anatomical phenotyping, an important and accessible application that has shown a high potential for impact in many mouse models at our imaging center.
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Schneider JE, Lanz T, Barnes H, Stork LA, Bohl S, Lygate CA, Ordidge RJ, Neubauer S. Accelerated cardiac magnetic resonance imaging in the mouse using an eight-channel array at 9.4 Tesla. Magn Reson Med 2011; 65:60-70. [PMID: 20740650 PMCID: PMC3021721 DOI: 10.1002/mrm.22605] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
MRI has become an important tool to noninvasively assess global and regional cardiac function, infarct size, or myocardial blood flow in surgically or genetically modified mouse models of human heart disease. Constraints on scan time due to sensitivity to general anesthesia in hemodynamically compromised mice frequently limit the number of parameters available in one imaging session. Parallel imaging techniques to reduce acquisition times require coil arrays, which are technically challenging to design at ultrahigh magnetic field strengths. This work validates the use of an eight-channel volume phased-array coil for cardiac MRI in mice at 9.4 T. Two- and three-dimensional sequences were combined with parallel imaging techniques and used to quantify global cardiac function, T(1)-relaxation times and infarct sizes. Furthermore, the rapid acquisition of functional cine-data allowed for the first time in mice measurement of left-ventricular peak filling and ejection rates under intravenous infusion of dobutamine. The results demonstrate that a threefold accelerated data acquisition is generally feasible without compromising the accuracy of the results. This strategy may eventually pave the way for routine, multiparametric phenotyping of mouse hearts in vivo within one imaging session of tolerable duration.
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Affiliation(s)
- Jürgen E Schneider
- British Heart Foundation Experimental MR Unit (BMRU), Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 7BN, United Kingdom.
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[Transcriptome atlas of serine family amino acid metabolism-related genes in eight rat regenerating liver cell types.]. YI CHUAN = HEREDITAS 2010; 32:829-38. [PMID: 20709681 DOI: 10.3724/sp.j.1005.2010.00829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
To explore the transcription profiles of serine family amino acid metabolism-related genes in eight liver cell types during rat liver regeneration (LR), eight types of rat regenerating liver cells were isolated using the combination of percoll density gradient centrifugation and immunomagnetic bead methods. Then, the expression profiles of the genes associated with metabolism of serine family amino acid in rat liver regeneration were detected by Rat Genome 230 2.0 Array. The expression patterns of these genes were analyzed through the software of Cluster and Treeview. The activities of serine family amino acid metabolism were analyzed by the methods of bioinformatics and systems biology. The results showed that 27 genes were significantly expressed. Among them, the numbers of genes showing significant expression changes in hepatocytes, biliary epithelial cells, oval cells, hepatic stellate cells, sinusoidal endothelial cells, Kupffer cells, pit cells and dendritic cells were 13, 16, 11, 14, 13, 11, 12, and 14, respectively. The numbers of up-, down-, and up-/down-regulated genes in corresponding cells were 7, 6, and 0; 2, 10, and 4; 2, 8, and 1; 8, 3, and 3; 6, 5, and 2; 4, 6, and 1; 2, 10, and 0; and 6, 6, and 2. Overall, the genes in the eight types of cells were mostly down-regulated during liver regeneration, but most LR-related genes in hepatic stellate cells and sinusoidal endothelial cells were up-regulated in priming phase. It is suggested that biosynthesis of serine family amino acid was enhanced in hepatocytes, hepatic stellate cells, sinusoidal endothelial cells and Kupffer cells in the priming phase. The catabolism of them was enhanced in hepatocytes, biliary epithelial cells, pit cells and dendritic cells in progressive phase.
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Puntmann VO, Mayr M. Phenotyping transgenic animals—An integrated readout of pathophysiology by combining proteomics and metabolomics with cardiovascular imaging. J Mol Cell Cardiol 2010; 48:571-3. [DOI: 10.1016/j.yjmcc.2009.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 12/03/2009] [Accepted: 12/03/2009] [Indexed: 10/20/2022]
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Mice over-expressing the myocardial creatine transporter develop progressive heart failure and show decreased glycolytic capacity. J Mol Cell Cardiol 2009; 48:582-90. [PMID: 19913546 DOI: 10.1016/j.yjmcc.2009.10.033] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 10/26/2009] [Accepted: 10/26/2009] [Indexed: 11/22/2022]
Abstract
The metabolic phenotype of the failing heart includes a decrease in phosphocreatine and total creatine concentration [Cr], potentially contributing to contractile dysfunction. Surprisingly, in 32- week-old mice over-expressing the myocardial creatine transporter (CrT-OE), we previously demonstrated that elevated [Cr] correlates with left ventricular (LV) hypertrophy and failure. The aim of this study was to determine the temporal relationship between elevated [Cr] and the onset of cardiac dysfunction and to screen for potential molecular mechanisms. CrT-OE mice were compared with wild-type (WT) littermate controls longitudinally using cine-MRI to measure cardiac function and single-voxel (1)H-MRS to measure [Cr] in vivo at 6, 16, 32, and 52 weeks of age. CrT-OE mice had elevated [Cr] at 6 weeks (mean 1.9-fold), which remained constant throughout life. Despite this increased [Cr], LV dysfunction was not apparent until 16 weeks and became more pronounced with age. Additionally, LV tissue from 12 to 14 week old CrT-OE mice was compared to WT using 2D difference in-gel electrophoresis (DIGE). These analyses detected a majority of the heart's metabolic enzymes and identified seven proteins that were differentially expressed between groups. The most pronounced protein changes were related to energy metabolism: alpha- and beta-enolase were selectively decreased (p<0.05), while the remaining enzymes of glycolysis were unchanged. Consistent with a decrease in enolase content, its activity was significantly lower in CrT-OE hearts (in WT, 0.59+/-0.02 micromol ATP produced/microg protein/min; CrT-OE, 0.31+/-0.06; p<0.01). Additionally, anaerobic lactate production was decreased in CrT-OE mice (in WT, 102+/-3 micromol/g wet myocardium; CrT-OE, 78+/-13; p=0.02), consistent with decreased glycolytic capacity. Finally, we found that enolase may be regulated by increased expression of the beta-enolase repressor transcription factor, which was significantly increased in CrT-OE hearts. This study demonstrates that chronically increased myocardial [Cr] in the CrT-OE model leads to the development of progressive hypertrophy and heart failure, which may be mediated by a compromise in glycolytic capacity at the level of enolase.
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Nieman BJ, Szulc KU, Turnbull DH. Three-dimensional, in vivo MRI with self-gating and image coregistration in the mouse. Magn Reson Med 2009; 61:1148-57. [PMID: 19253389 DOI: 10.1002/mrm.21945] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Motion during magnetic resonance imaging (MRI) scans routinely results in undesirable image artifact or blurring. Since high-resolution, three-dimensional (3D) imaging of the mouse requires long scan times for satisfactory signal-to-noise ratio (SNR) and image quality, motion-related artifacts are likely over much of the body and limit applications of mouse MRI. In this investigation, we explored the use of self-gated imaging methods and image coregistration for improving image quality in the presence of motion. Self-gated signal results from a modified 3D gradient-echo sequence showed detection of periodic respiratory and cardiac motion in the adult mouse-with excellent comparison to traditional measurements, sensitivity to respiration-induced tissue changes in the brain, and even detection of embryonic cardiac motion in utero. Serial image coregistration with rapidly-acquired, low-SNR volumes further enabled detection and correction of bulk changes in embryo location during in utero imaging sessions and subsequent reconstruction of high-quality images. These methods, in combination, are shown to expand the range of applications for 3D mouse MRI, enabling late-stage embryonic heart imaging and introducing the possibility of longitudinal developmental studies from embryonic stages through adulthood.
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Affiliation(s)
- Brian J Nieman
- Kimmel Center for Biological and Medicine at the Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
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