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Bychkov R, Juhaszova M, Calvo-Rubio Barrera M, Donald LAH, Coletta C, Shumaker C, Moorman K, Tagirova S, Maltsev AV, Sollott SJ, Lakatta EG. Autonomic innervation, a peripheral glial cell web, and a novel S100B expressing interstitial cell type impart structural and functional complexity to the sinoatrial node. Biophys J 2023; 122:233a. [PMID: 36783144 DOI: 10.1016/j.bpj.2022.11.1372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Rostislav Bychkov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Magdalena Juhaszova
- National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Miguel Calvo-Rubio Barrera
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Lorenzo A H Donald
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Christopher Coletta
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Chad Shumaker
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Kayla Moorman
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Syevda Tagirova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Alexander V Maltsev
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
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Cortassa SC, Aon MA, Juhaszova M, Zorov DB, Sollott SJ. Consequential modulation of mitochondrial K +- and H +-driven ATP synthase activity under excess cytoplasmic NA + and oxidative stress mimicking heart failure: Modeling studies. Biophys J 2023; 122:96a-97a. [PMID: 36785106 DOI: 10.1016/j.bpj.2022.11.715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Sonia C Cortassa
- National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Magdalena Juhaszova
- National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Dmitry B Zorov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
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Winicki NM, Nanavati AP, Morrell CH, Moen JM, Axsom JE, Krawczyk M, Petrashevskaya NN, Beyman MG, Ramirez C, Alfaras I, Mitchell SJ, Juhaszova M, Riordon DR, Wang M, Zhang J, Cerami A, Brines M, Sollott SJ, de Cabo R, Lakatta EG. A small erythropoietin derived non-hematopoietic peptide reduces cardiac inflammation, attenuates age associated declines in heart function and prolongs healthspan. Front Cardiovasc Med 2023; 9:1096887. [PMID: 36741836 PMCID: PMC9889362 DOI: 10.3389/fcvm.2022.1096887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 12/28/2022] [Indexed: 01/20/2023] Open
Abstract
Background Aging is associated with increased levels of reactive oxygen species and inflammation that disrupt proteostasis and mitochondrial function and leads to organism-wide frailty later in life. ARA290 (cibinetide), an 11-aa non-hematopoietic peptide sequence within the cardioprotective domain of erythropoietin, mediates tissue protection by reducing inflammation and fibrosis. Age-associated cardiac inflammation is linked to structural and functional changes in the heart, including mitochondrial dysfunction, impaired proteostasis, hypertrophic cardiac remodeling, and contractile dysfunction. Can ARA290 ameliorate these age-associated cardiac changes and the severity of frailty in advanced age? Methods We conducted an integrated longitudinal (n = 48) and cross-sectional (n = 144) 15 months randomized controlled trial in which 18-month-old Fischer 344 x Brown Norway rats were randomly assigned to either receive chronic ARA290 treatment or saline. Serial echocardiography, tail blood pressure and body weight were evaluated repeatedly at 4-month intervals. A frailty index was calculated at the final timepoint (33 months of age). Tissues were harvested at 4-month intervals to define inflammatory markers and left ventricular tissue remodeling. Mitochondrial and myocardial cell health was assessed in isolated left ventricular myocytes. Kaplan-Meier survival curves were established. Mixed ANOVA tests and linear mixed regression analysis were employed to determine the effects of age, treatment, and age-treatment interactions. Results Chronic ARA290 treatment mitigated age-related increases in the cardiac non-myocyte to myocyte ratio, infiltrating leukocytes and monocytes, pro-inflammatory cytokines, total NF-κB, and p-NF-κB. Additionally, ARA290 treatment enhanced cardiomyocyte autophagy flux and reduced cellular accumulation of lipofuscin. The cardiomyocyte mitochondrial permeability transition pore response to oxidant stress was desensitized following chronic ARA290 treatment. Concurrently, ARA290 significantly blunted the age-associated elevation in blood pressure and preserved the LV ejection fraction. Finally, ARA290 preserved body weight and significantly reduced other markers of organism-wide frailty at the end of life. Conclusion Administration of ARA290 reduces cell and tissue inflammation, mitigates structural and functional changes within the cardiovascular system leading to amelioration of frailty and preserved healthspan.
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Affiliation(s)
- Nolan M. Winicki
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Alay P. Nanavati
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Christopher H. Morrell
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Jack M. Moen
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Jessie E. Axsom
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Melissa Krawczyk
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Natalia N. Petrashevskaya
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Max G. Beyman
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Christopher Ramirez
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Irene Alfaras
- Laboratory of Experimental Gerontology, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Sarah J. Mitchell
- Laboratory of Experimental Gerontology, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Daniel R. Riordon
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Mingyi Wang
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Jing Zhang
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Anthony Cerami
- Araim Pharmaceuticals, Inc., Tarrytown, NY, United States
| | - Michael Brines
- Feinstein Institutes for Medical Research, Northwell Health, Manhasset, NY, United States
| | - Steven J. Sollott
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Rafael de Cabo
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States
| | - Edward G. Lakatta
- Laboratory of Experimental Gerontology, Intramural Research Program, National Institute on Aging, Baltimore, MD, United States,*Correspondence: Edward G. Lakatta,
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Bychkov R, Juhaszova M, Calvo-Rubio Barrera M, Donald LAH, Coletta C, Shumaker C, Moorman K, Sirenko ST, Maltsev AV, Sollott SJ, Lakatta EG. The Heart's Pacemaker Mimics Brain Cytoarchitecture and Function: Novel Interstitial Cells Expose Complexity of the SAN. JACC Clin Electrophysiol 2022; 8:1191-1215. [PMID: 36182566 DOI: 10.1016/j.jacep.2022.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 05/27/2022] [Accepted: 07/01/2022] [Indexed: 10/14/2022]
Abstract
BACKGROUND The sinoatrial node (SAN) of the heart produces rhythmic action potentials, generated via calcium signaling within and among pacemaker cells. Our previous work has described the SAN as composed of a hyperpolarization-activated cyclic nucleotide-gated potassium channel 4 (HCN4)-expressing pacemaker cell meshwork, which merges with a network of connexin 43+/F-actin+ cells. It is also known that sympathetic and parasympathetic innervation create an autonomic plexus in the SAN that modulates heart rate and rhythm. However, the anatomical details of the interaction of this plexus with the pacemaker cell meshwork have yet to be described. OBJECTIVES This study sought to describe the 3-dimensional cytoarchitecture of the mouse SAN, including autonomic innervation, peripheral glial cells, and pacemaker cells. METHODS The cytoarchitecture of SAN whole-mount preparations was examined by three-dimensional confocal laser-scanning microscopy of triple immunolabeled with combinations of antibodies for HCN4, S100 calcium-binding protein B (S100B), glial fibrillary acidic protein (GFAP), choline acetyltransferase, or vesicular acetylcholine transporter, and tyrosine hydroxylase, and transmission electron microscopy. RESULTS The SAN exhibited heterogeneous autonomic innervation, which was accompanied by a web of peripheral glial cells and a novel S100B+/GFAP- interstitial cell population, with a unique morphology and a distinct distribution pattern, creating complex interactions with other cell types in the node, particularly with HCN4-expressing cells. Transmission electron microscopy identified a similar population of interstitial cells as telocytes, which appeared to secrete vesicles toward pacemaker cells. Application of S100B to SAN preparations desynchronized Ca2+ signaling in HCN4-expressing cells and increased variability in SAN impulse rate and rhythm. CONCLUSIONS The autonomic plexus, peripheral glial cell web, and a novel S100B+/GFAP- interstitial cell type embedded within the HCN4+ cell meshwork increase the structural and functional complexity of the SAN and provide a new regulatory pathway of rhythmogenesis.
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Affiliation(s)
- Rostislav Bychkov
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Miguel Calvo-Rubio Barrera
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Lorenzo A H Donald
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Christopher Coletta
- Laboratory of Genetics and Genomics, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Chad Shumaker
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Kayla Moorman
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Syevda Tagirova Sirenko
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Alexander V Maltsev
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA.
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Juhaszova M, Kobrinsky E, Zorov DB, Aon MA, Cortassa S, Sollott SJ. Setting the Record Straight: A New Twist on the Chemiosmotic Mechanism of Oxidative Phosphorylation. Function (Oxf) 2022; 3:zqac018. [PMID: 35601666 PMCID: PMC9112926 DOI: 10.1093/function/zqac018] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/08/2022] [Accepted: 04/10/2022] [Indexed: 01/07/2023]
Affiliation(s)
- Magdalena Juhaszova
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Evgeny Kobrinsky
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Dmitry B Zorov
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA,A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA,Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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Juhaszova M, Kobrinsky E, Zorov DB, Nuss HB, Yaniv Y, Fishbein KW, de Cabo R, Montoliu L, Gabelli SB, Aon MA, Cortassa S, Sollott SJ. ATP Synthase K +- and H +-fluxes Drive ATP Synthesis and Enable Mitochondrial K +-"Uniporter" Function: II. Ion and ATP Synthase Flux Regulation. Function (Oxf) 2022; 3:zqac001. [PMID: 35187492 PMCID: PMC8850977 DOI: 10.1093/function/zqac001] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 01/12/2022] [Accepted: 01/18/2022] [Indexed: 01/07/2023]
Abstract
We demonstrated that ATP synthase serves the functions of a primary mitochondrial K+ "uniporter," i.e., the primary way for K+ to enter mitochondria. This K+ entry is proportional to ATP synthesis, regulating matrix volume and energy supply-vs-demand matching. We show that ATP synthase can be upregulated by endogenous survival-related proteins via IF1. We identified a conserved BH3-like domain of IF1 which overlaps its "minimal inhibitory domain" that binds to the β-subunit of F1. Bcl-xL and Mcl-1 possess a BH3-binding-groove that can engage IF1 and exert effects, requiring this interaction, comparable to diazoxide to augment ATP synthase's H+ and K+ flux and ATP synthesis. Bcl-xL and Mcl-1, but not Bcl-2, serve as endogenous regulatory ligands of ATP synthase via interaction with IF1 at this BH3-like domain, to increase its chemo-mechanical efficiency, enabling its function as the recruitable mitochondrial KATP-channel that can limit ischemia-reperfusion injury. Using Bayesian phylogenetic analysis to examine potential bacterial IF1-progenitors, we found that IF1 is likely an ancient (∼2 Gya) Bcl-family member that evolved from primordial bacteria resident in eukaryotes, corresponding to their putative emergence as symbiotic mitochondria, and functioning to prevent their parasitic ATP consumption inside the host cell.
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Affiliation(s)
| | | | | | | | | | - Kenneth W Fishbein
- Laboratory of Clinical Investigation, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Lluis Montoliu
- National Centre for Biotechnology (CNB-CSIC), Biomedical Research Networking Center on Rare Diseases (CIBERER-ISCIII), 28049 Madrid, Spain
| | - Sandra B Gabelli
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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Tarasov KV, Chakir K, Riordon DR, Lyashkov AE, Ahmet I, Perino MG, Silvester AJ, Zhang J, Wang M, Lukyanenko YO, Qu JH, Barrera MCR, Juhaszova M, Tarasova YS, Ziman B, Telljohann R, Kumar V, Ranek M, Lammons J, Bychkov R, de Cabo R, Jun S, Keceli G, Gupta A, Yang D, Aon MA, Adamo L, Morrell CH, Otu W, Carroll C, Chambers S, Paolocci N, Huynh T, Pacak K, Weiss R, Field L, Sollott SJ, Lakatta EG. A remarkable adaptive paradigm of heart performance and protection emerges in response to marked cardiac-specific overexpression of ADCY8. eLife 2022; 11:80949. [PMID: 36515265 PMCID: PMC9822292 DOI: 10.7554/elife.80949] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 12/08/2022] [Indexed: 12/15/2022] Open
Abstract
Adult (3 month) mice with cardiac-specific overexpression of adenylyl cyclase (AC) type VIII (TGAC8) adapt to an increased cAMP-induced cardiac workload (~30% increases in heart rate, ejection fraction and cardiac output) for up to a year without signs of heart failure or excessive mortality. Here, we show classical cardiac hypertrophy markers were absent in TGAC8, and that total left ventricular (LV) mass was not increased: a reduced LV cavity volume in TGAC8 was encased by thicker LV walls harboring an increased number of small cardiac myocytes, and a network of small interstitial proliferative non-cardiac myocytes compared to wild type (WT) littermates; Protein synthesis, proteosome activity, and autophagy were enhanced in TGAC8 vs WT, and Nrf-2, Hsp90α, and ACC2 protein levels were increased. Despite increased energy demands in vivo LV ATP and phosphocreatine levels in TGAC8 did not differ from WT. Unbiased omics analyses identified more than 2,000 transcripts and proteins, comprising a broad array of biological processes across multiple cellular compartments, which differed by genotype; compared to WT, in TGAC8 there was a shift from fatty acid oxidation to aerobic glycolysis in the context of increased utilization of the pentose phosphate shunt and nucleotide synthesis. Thus, marked overexpression of AC8 engages complex, coordinate adaptation "circuity" that has evolved in mammalian cells to defend against stress that threatens health or life (elements of which have already been shown to be central to cardiac ischemic pre-conditioning and exercise endurance cardiac conditioning) that may be of biological significance to allow for proper healing in disease states such as infarction or failure of the heart.
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Affiliation(s)
- Kirill V Tarasov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Khalid Chakir
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Daniel R Riordon
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Alexey E Lyashkov
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Ismayil Ahmet
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Maria Grazia Perino
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Allwin Jennifa Silvester
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Jing Zhang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Mingyi Wang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Yevgeniya O Lukyanenko
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Jia-Hua Qu
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Miguel Calvo-Rubio Barrera
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Yelena S Tarasova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Bruce Ziman
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Richard Telljohann
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Vikas Kumar
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Mark Ranek
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - John Lammons
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Rostislav Bychkov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Rafael de Cabo
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Seungho Jun
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Gizem Keceli
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Ashish Gupta
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Luigi Adamo
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Christopher H Morrell
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Walter Otu
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Cameron Carroll
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Shane Chambers
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Nazareno Paolocci
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Thanh Huynh
- Section on Medical Neuroendocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of HealthBethesdaUnited States
| | - Karel Pacak
- Section on Medical Neuroendocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of HealthBethesdaUnited States
| | - Robert Weiss
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Loren Field
- Kraennert Institute of Cardiology, Indiana University School of MedicineIdianapolisUnited States
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
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8
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Cortassa S, Aon MA, Juhaszova M, Kobrinsky E, Zorov DB, Sollott SJ. Computational modeling of mitochondrial K +- and H +-driven ATP synthesis. J Mol Cell Cardiol 2021; 165:9-18. [PMID: 34954465 DOI: 10.1016/j.yjmcc.2021.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 09/20/2021] [Accepted: 12/06/2021] [Indexed: 10/19/2022]
Abstract
ATP synthase (F1Fo) is a rotary molecular engine that harnesses energy from electrochemical-gradients across the inner mitochondrial membrane for ATP synthesis. Despite the accepted tenet that F1Fo transports exclusively H+, our laboratory has demonstrated that, in addition to H+, F1Fo ATP synthase transports a significant fraction of ΔΨm-driven charge as K+ to synthesize ATP. Herein, we utilize a computational modeling approach as a proof of principle of the feasibility of the core mechanism underlying the enhanced ATP synthesis, and to explore its bioenergetic consequences. A minimal model comprising the 'core' mechanism constituted by ATP synthase, driven by both proton (PMF) and potassium motive force (KMF), respiratory chain, adenine nucleotide translocator, Pi carrier, and K+/H+ exchanger (KHEmito) was able to simulate enhanced ATP synthesis and respiratory fluxes determined experimentally with isolated heart mitochondria. This capacity of F1Fo ATP synthase confers mitochondria with a significant energetic advantage compared to K+ transport through a channel not linked to oxidative phosphorylation (OxPhos). The K+-cycling mechanism requires a KHEmito that exchanges matrix K+ for intermembrane space H+, leaving PMF as the overall driving energy of OxPhos, in full agreement with the standard chemiosmotic mechanism. Experimental data of state 4➔3 energetic transitions, mimicking low to high energy demand, could be reproduced by an integrated computational model of mitochondrial function that incorporates the 'core' mechanism. Model simulations display similar behavior compared to the experimentally observed changes in ΔΨm, mitochondrial K+ uptake, matrix volume, respiration, and ATP synthesis during the energetic transitions at physiological pH and K+ concentration. The model also explores the role played by KHEmito in modulating the energetic performance of mitochondria. The results obtained support the available experimental evidence on ATP synthesis driven by K+ and H+ transport through the F1Fo ATP synthase.
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Affiliation(s)
- Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States of America.
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States of America.
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States of America.
| | - Evgeny Kobrinsky
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States of America.
| | - Dmitry B Zorov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States of America; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States of America.
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Juhaszova M, Kobrinsky E, Zorov DB, Nuss HB, Yaniv Y, Fishbein KW, de Cabo R, Montoliu L, Gabelli SB, Aon MA, Cortassa S, Sollott SJ. ATP Synthase K +- and H +-Fluxes Drive ATP Synthesis and Enable Mitochondrial K +-"Uniporter" Function: I. Characterization of Ion Fluxes. Function (Oxf) 2021; 3:zqab065. [PMID: 35229078 PMCID: PMC8867323 DOI: 10.1093/function/zqab065] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 01/07/2023]
Abstract
ATP synthase (F1Fo) synthesizes daily our body's weight in ATP, whose production-rate can be transiently increased several-fold to meet changes in energy utilization. Using purified mammalian F1Fo-reconstituted proteoliposomes and isolated mitochondria, we show F1Fo can utilize both ΔΨm-driven H+- and K+-transport to synthesize ATP under physiological pH = 7.2 and K+ = 140 mEq/L conditions. Purely K+-driven ATP synthesis from single F1Fo molecules measured by bioluminescence photon detection could be directly demonstrated along with simultaneous measurements of unitary K+ currents by voltage clamp, both blocked by specific Fo inhibitors. In the presence of K+, compared to osmotically-matched conditions in which this cation is absent, isolated mitochondria display 3.5-fold higher rates of ATP synthesis, at the expense of 2.6-fold higher rates of oxygen consumption, these fluxes being driven by a 2.7:1 K+: H+ stoichiometry. The excellent agreement between the functional data obtained from purified F1Fo single molecule experiments and ATP synthase studied in the intact mitochondrion under unaltered OxPhos coupling by K+ presence, is entirely consistent with K+ transport through the ATP synthase driving the observed increase in ATP synthesis. Thus, both K+ (harnessing ΔΨm) and H+ (harnessing its chemical potential energy, ΔμH) drive ATP generation during normal physiology.
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Affiliation(s)
| | | | | | | | | | - Kenneth W Fishbein
- Laboratory of Clinical Investigation, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Lluis Montoliu
- National Centre for Biotechnology (CNB-CSIC), Biomedical Research Networking Center on Rare Diseases (CIBERER-ISCIII), 28049, Madrid, Spain
| | - Sandra B Gabelli
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA,Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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Cortassa SC, Aon MA, Juhaszova M, Kobrinsky E, Zorov DB, Sollott SJ. Computational Modeling of Mitochondrial K+ and H+-Driven ATP Synthesis and Volume Regulation. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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11
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Cortassa S, Juhaszova M, Aon MA, Zorov DB, Sollott SJ. Mitochondrial Ca 2+, redox environment and ROS emission in heart failure: Two sides of the same coin? J Mol Cell Cardiol 2021; 151:113-125. [PMID: 33301801 PMCID: PMC7880885 DOI: 10.1016/j.yjmcc.2020.11.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 11/05/2020] [Accepted: 11/28/2020] [Indexed: 12/11/2022]
Abstract
Heart failure (HF) is a progressive, debilitating condition characterized, in part, by altered ionic equilibria, increased ROS production and impaired cellular energy metabolism, contributing to variable profiles of systolic and diastolic dysfunction with significant functional limitations and risk of premature death. We summarize current knowledge concerning changes of intracellular Na+ and Ca2+ control mechanisms during the disease progression and their consequences on mitochondrial Ca2+ homeostasis and the shift in redox balance. Absent existing biological data, our computational modeling studies advance a new 'in silico' analysis to reconcile existing opposing views, based on different experimental HF models, regarding variations in mitochondrial Ca2+ concentration that participate in triggering and perpetuating oxidative stress in the failing heart and their impact on cardiac energetics. In agreement with our hypothesis and the literature, model simulations demonstrate the possibility that the heart's redox status together with cytoplasmic Na+ concentrations act as regulators of mitochondrial Ca2+ levels in HF and of the bioenergetics response that will ultimately drive ATP supply and oxidative stress. The resulting model predictions propose future directions to study the evolution of HF as well as other types of heart disease, and to develop novel testable mechanistic hypotheses that may lead to improved therapeutics.
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Affiliation(s)
- Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, United States.
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, United States.
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, United States; Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD, United States.
| | - Dmitry B Zorov
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, United States; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, United States.
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Kobrinsky E, Zorov DB, Juhaszova M, Aon MA, Cortassa S, Sollott SJ. Mitochondrial ATP Synthase Utilizes Both K+ and H+ Conductances to Drive ATP Synthesis. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2472] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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13
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Maltsev AV, Ajay Warrier P, Monfredi O, Juhaszova M, Lakatta EG, Maltsev VA, Stern MD. Machine Learning and Super-Resolution Microscopy Reveal Detailed Hierarchy of Ryanodine Receptor Distribution in Cardiac Pacemaker Cells. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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14
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Nanavati A, Moen J, Axsom J, Krawczyk M, Petrashevskaya N, Beyman M, Ramirez C, Alfaras I, Mitchell S, Bernier M, Morrell C, Sollott S, Juhaszova M, deCabo R, Lakatta E. ARA290, a small non-hematopoietic peptide derived from erythropoietin, prolongs healthspan and attenuates age-associated declines in cardiac function. J Mol Cell Cardiol 2018. [DOI: 10.1016/j.yjmcc.2018.07.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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15
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Zorova LD, Popkov VA, Plotnikov EY, Silachev DN, Pevzner IB, Jankauskas SS, Babenko VA, Zorov SD, Balakireva AV, Juhaszova M, Sollott SJ, Zorov DB. Mitochondrial membrane potential. Anal Biochem 2018; 552:50-59. [PMID: 28711444 PMCID: PMC5792320 DOI: 10.1016/j.ab.2017.07.009] [Citation(s) in RCA: 1000] [Impact Index Per Article: 166.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/06/2017] [Accepted: 07/07/2017] [Indexed: 01/13/2023]
Abstract
The mitochondrial membrane potential (ΔΨm) generated by proton pumps (Complexes I, III and IV) is an essential component in the process of energy storage during oxidative phosphorylation. Together with the proton gradient (ΔpH), ΔΨm forms the transmembrane potential of hydrogen ions which is harnessed to make ATP. The levels of ΔΨm and ATP in the cell are kept relatively stable although there are limited fluctuations of both these factors that can occur reflecting normal physiological activity. However, sustained changes in both factors may be deleterious. A long-lasting drop or rise of ΔΨm vs normal levels may induce unwanted loss of cell viability and be a cause of various pathologies. Among other factors, ΔΨm plays a key role in mitochondrial homeostasis through selective elimination of dysfunctional mitochondria. It is also a driving force for transport of ions (other than H+) and proteins which are necessary for healthy mitochondrial functioning. We propose additional potential mechanisms for which ΔΨm is essential for maintenance of cellular health and viability and provide recommendations how to accurately measure ΔΨm in a cell and discuss potential sources of artifacts.
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Affiliation(s)
- Ljubava D Zorova
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; International Laser Center, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Vasily A Popkov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Egor Y Plotnikov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Denis N Silachev
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Irina B Pevzner
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Stanislovas S Jankauskas
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Valentina A Babenko
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Savva D Zorov
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Anastasia V Balakireva
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russian Federation
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Dmitry B Zorov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
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Nanavati A, Moen J, Axsom J, Krawczyk M, Petrashevskaya N, Beyman M, Ramirez C, Alfaras I, Mitchell S, Bernier M, Morrell C, Sollott S, Juhaszova M, deCabo R, Lakatta E. ARA290, A Small Non‐Hematopoietic Peptide Derived From Erythropoietin, Prolongs Healthspan And Attenuates Age‐Associated Declines In The Heart's Structure And Function. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.lb288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Jack Moen
- National Institute on AgingBaltimoreMD
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Juhaszova M, Cortassa S, Aon MA, González-Reyes JA, Calvo-Rubio M, Villalba JM, Zorov DB, Kobrinsky E, Ziman BD, Koch LG, Britton SL, Lakatta EG, Sollott SJ. High Intrinsic Aerobic Endurance Capacity Preserves Cardiomyocyte Quality Control, Mitochondrial Fitness and Lifespan. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.3572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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18
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Bychkov R, Tsutsui K, Juhaszova M, Sollott S, Stern MD, Maltsev VA, Lakatta EG. Microstructural and Functional Imaging of the Intact Sinoatrial Node Detects Heterogenous Ca2+-Driven Intra and Intercellular Communications that Lead to Pacing Perfection. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.1193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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19
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Cortassa S, Aon MA, Juhaszova M, Gonzalez-Reyes JA, Calvo-Rubio M, Villalba JM, Ziman B, Mitchell SJ, Alfaras I, Chakir K, Axsom JE, Bullock K, Lakatta E, Sollott SJ. Enhanced Respiratory Reserve Sustained by Lipid Oxidation and Autophagy Underlie Extended Lifespan in High- Compared to Low-Running Capacity Rats. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.3568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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20
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Lukyanenko YO, Younes A, Lyashkov AE, Tarasov KV, Riordon DR, Lee J, Sirenko SG, Kobrinsky E, Ziman B, Tarasova YS, Juhaszova M, Sollott SJ, Graham DR, Lakatta EG. Ca(2+)/calmodulin-activated phosphodiesterase 1A is highly expressed in rabbit cardiac sinoatrial nodal cells and regulates pacemaker function. J Mol Cell Cardiol 2016; 98:73-82. [PMID: 27363295 DOI: 10.1016/j.yjmcc.2016.06.064] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 05/23/2016] [Accepted: 06/23/2016] [Indexed: 11/29/2022]
Abstract
Constitutive Ca(2+)/calmodulin (CaM)-activation of adenylyl cyclases (ACs) types 1 and 8 in sinoatrial nodal cells (SANC) generates cAMP within lipid-raft-rich microdomains to initiate cAMP-protein kinase A (PKA) signaling, that regulates basal state rhythmic action potential firing of these cells. Mounting evidence in other cell types points to a balance between Ca(2+)-activated counteracting enzymes, ACs and phosphodiesterases (PDEs) within these cells. We hypothesized that the expression and activity of Ca(2+)/CaM-activated PDE Type 1A is higher in SANC than in other cardiac cell types. We found that PDE1A protein expression was 5-fold higher in sinoatrial nodal tissue than in left ventricle, and its mRNA expression was 12-fold greater in the corresponding isolated cells. PDE1 activity (nimodipine-sensitive) accounted for 39% of the total PDE activity in SANC lysates, compared to only 4% in left ventricular cardiomyocytes (LVC). Additionally, total PDE activity in SANC lysates was lowest (10%) in lipid-raft-rich and highest (76%) in lipid-raft-poor fractions (equilibrium sedimentation on a sucrose density gradient). In intact cells PDE1A immunolabeling was not localized to the cell surface membrane (structured illumination microscopy imaging), but located approximately within about 150nm inside of immunolabeling of hyperpolarization-activated cyclic nucleotide-gated potassium channels (HCN4), which reside within lipid-raft-rich microenvironments. In permeabilized SANC, in which surface membrane ion channels are not functional, nimodipine increased spontaneous SR Ca(2+) cycling. PDE1A mRNA silencing in HL-1 cells increased the spontaneous beating rate, reduced the cAMP, and increased cGMP levels in response to IBMX, a broad spectrum PDE inhibitor (detected via fluorescence resonance energy transfer microscopy). We conclude that signaling via cAMP generated by Ca(2+)/CaM-activated AC in SANC lipid raft domains is limited by cAMP degradation by Ca(2+)/CaM-activated PDE1A in non-lipid raft domains. This suggests that local gradients of [Ca(2+)]-CaM or different AC and PDE1A affinity regulate both cAMP production and its degradation, and this balance determines the intensity of Ca(2+)-AC-cAMP-PKA signaling that drives SANC pacemaker function.
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Affiliation(s)
- Yevgeniya O Lukyanenko
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - Antoine Younes
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - Alexey E Lyashkov
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA; Department of Molecular and Comparative Pathobiology, Johns Hopkins School of Medicine, 733 N. Broadway, MRB 835, Baltimore, MD 21205, USA.
| | - Kirill V Tarasov
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - Daniel R Riordon
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - Joonho Lee
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - Syevda G Sirenko
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - Evgeny Kobrinsky
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - Bruce Ziman
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - Yelena S Tarasova
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
| | - David R Graham
- Department of Molecular and Comparative Pathobiology, Johns Hopkins School of Medicine, 733 N. Broadway, MRB 835, Baltimore, MD 21205, USA.
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, 251 Bayview Blvd., Baltimore, MD 21224, USA.
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Maltsev VA, Maltsev AV, Juhaszova M, Sirenko S, Monfredi O, Shroff H, York A, Sollott SJ, Lakatta EG, Stern MD. Cardiac Pacemaker Cell Function at a Super-Resolution Scale of SIM: Distribution of RyRs, Calcium Dynamics, and Numerical Modeling. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1455] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Abstract
Byproducts of normal mitochondrial metabolism and homeostasis include the buildup of potentially damaging levels of reactive oxygen species (ROS), Ca(2+), etc., which must be normalized. Evidence suggests that brief mitochondrial permeability transition pore (mPTP) openings play an important physiological role maintaining healthy mitochondria homeostasis. Adaptive and maladaptive responses to redox stress may involve mitochondrial channels such as mPTP and inner membrane anion channel (IMAC). Their activation causes intra- and intermitochondrial redox-environment changes leading to ROS release. This regenerative cycle of mitochondrial ROS formation and release was named ROS-induced ROS release (RIRR). Brief, reversible mPTP opening-associated ROS release apparently constitutes an adaptive housekeeping function by the timely release from mitochondria of accumulated potentially toxic levels of ROS (and Ca(2+)). At higher ROS levels, longer mPTP openings may release a ROS burst leading to destruction of mitochondria, and if propagated from mitochondrion to mitochondrion, of the cell itself. The destructive function of RIRR may serve a physiological role by removal of unwanted cells or damaged mitochondria, or cause the pathological elimination of vital and essential mitochondria and cells. The adaptive release of sufficient ROS into the vicinity of mitochondria may also activate local pools of redox-sensitive enzymes involved in protective signaling pathways that limit ischemic damage to mitochondria and cells in that area. Maladaptive mPTP- or IMAC-related RIRR may also be playing a role in aging. Because the mechanism of mitochondrial RIRR highlights the central role of mitochondria-formed ROS, we discuss all of the known ROS-producing sites (shown in vitro) and their relevance to the mitochondrial ROS production in vivo.
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Affiliation(s)
- Dmitry B Zorov
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Magdalena Juhaszova
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Steven J Sollott
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
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Stern MD, Maltseva LA, Juhaszova M, Sollott SJ, Lakatta EG, Maltsev VA. Hierarchical clustering of ryanodine receptors enables emergence of a calcium clock in sinoatrial node cells. J Gen Physiol 2014; 143:577-604. [PMID: 24778430 PMCID: PMC4003189 DOI: 10.1085/jgp.201311123] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 04/07/2014] [Indexed: 12/12/2022] Open
Abstract
The sinoatrial node, whose cells (sinoatrial node cells [SANCs]) generate rhythmic action potentials, is the primary pacemaker of the heart. During diastole, calcium released from the sarcoplasmic reticulum (SR) via ryanodine receptors (RyRs) interacts with membrane currents to control the rate of the heartbeat. This "calcium clock" takes the form of stochastic, partially periodic, localized calcium release (LCR) events that propagate, wave-like, for limited distances. The detailed mechanisms controlling the calcium clock are not understood. We constructed a computational model of SANCs, including three-dimensional diffusion and buffering of calcium in the cytosol and SR; explicit, stochastic gating of individual RyRs and L-type calcium channels; and a full complement of voltage- and calcium-dependent membrane currents. We did not include an anatomical submembrane space or inactivation of RyRs, the two heuristic components that have been used in prior models but are not observed experimentally. When RyRs were distributed in discrete clusters separated by >1 µm, only isolated sparks were produced in this model and LCR events did not form. However, immunofluorescent staining of SANCs for RyR revealed the presence of bridging RyR groups between large clusters, forming an irregular network. Incorporation of this architecture into the model led to the generation of propagating LCR events. Partial periodicity emerged from the interaction of LCR events, as observed experimentally. This calcium clock becomes entrained with membrane currents to accelerate the beating rate, which therefore was controlled by the activity of the SERCA pump, RyR sensitivity, and L-type current amplitude, all of which are targets of β-adrenergic-mediated phosphorylation. Unexpectedly, simulations revealed the existence of a pathological mode at high RyR sensitivity to calcium, in which the calcium clock loses synchronization with the membrane, resulting in a paradoxical decrease in beating rate in response to β-adrenergic stimulation. The model indicates that the hierarchical clustering of surface RyRs in SANCs may be a crucial adaptive mechanism. Pathological desynchronization of the clocks may explain sinus node dysfunction in heart failure and RyR mutations.
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Affiliation(s)
- Michael D Stern
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
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Liu J, Sirenko S, Juhaszova M, Sollott SJ, Shukla S, Yaniv Y, Lakatta EG. Age-associated abnormalities of intrinsic automaticity of sinoatrial nodal cells are linked to deficient cAMP-PKA-Ca(2+) signaling. Am J Physiol Heart Circ Physiol 2014; 306:H1385-97. [PMID: 24633551 DOI: 10.1152/ajpheart.00088.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A reduced sinoatrial node (SAN) functional reserve underlies the age-associated decline in heart rate acceleration in response to stress. SAN cell function involves an oscillatory coupled-clock system: the sarcoplasmic reticulum (SR), a Ca(2+) clock, and the electrogenic-sarcolemmal membrane clock. Ca(2+)-activated-calmodulin-adenylyl cyclase/CaMKII-cAMP/PKA-Ca(2+) signaling regulated by phosphodiesterase activity drives SAN cells automaticity. SR-generated local calcium releases (LCRs) activate Na(+)/Ca(2+) exchanger in the membrane clock, which initiates the action potential (AP). We hypothesize that SAN cell dysfunctions accumulate with age. We found a reduction in single SAN cell AP firing in aged (20-24 mo) vs. adult (3-4 mo) mice. The sensitivity of the SAN beating rate responses to both muscarinic and adrenergic receptor activation becomes decreased in advanced age. Additionally, age-associated coincident dysfunctions occur stemming from compromised clock functions, including a reduced SR Ca(2+) load and a reduced size, number, and duration of spontaneous LCRs. Moreover, the sensitivity of SAN beating rate to a cAMP stress induced by phosphodiesterase inhibitor is reduced, as are the LCR size, amplitude, and number in SAN cells from aged vs. adult mice. These functional changes coincide with decreased expression of crucial SR Ca(2+)-cycling proteins, including SR Ca(2+)-ATPase pump, ryanodine receptors, and Na(+)/Ca(2+) exchanger. Thus a deterioration in intrinsic Ca(2+) clock kinetics in aged SAN cells, due to deficits in intrinsic SR Ca(2+) cycling and its response to a cAMP-dependent pathway activation, is involved in the age-associated reduction in intrinsic resting AP firing rate, and in the reduction in the acceleration of heart rate during exercise.
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Affiliation(s)
- Jie Liu
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and Department of Physiology, University of Sydney, Sydney, New South Wales, Australia
| | - Syevda Sirenko
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| | - Shweta Shukla
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| | - Yael Yaniv
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
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Younes A, Lukyanenko Y, Lyashkov A, Tarasov K, Sirenko S, Ziman B, Juhaszova M, Graham DR, Lakatta EG. Phosphodiesterase Expression Pattern and Activity Partitioning in Lipid Raft and in Non-Lipid-Raft Microenvironment in Cardiac Sinoatrial Nodal Cells. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Stern M, Maltseva LA, Juhaszova M, Sollott SJ, Lakatta EG, Maltsev VA. Emergence and Synchronization of the “Calcium Clock” in a 3-Dimensional Model of a Sino-Atrial Node Cell with Explicit Channel Gating. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.1838] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Yaniv Y, Juhaszova M, Sollott SJ. Age-related changes of myocardial ATP supply and demand mechanisms. Trends Endocrinol Metab 2013; 24:495-505. [PMID: 23845538 PMCID: PMC3783621 DOI: 10.1016/j.tem.2013.06.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 05/30/2013] [Accepted: 06/03/2013] [Indexed: 01/03/2023]
Abstract
In advanced age, the resting myocardial oxygen consumption rate (MVO2) and cardiac work (CW) in the rat remain intact. However, MVO2, CW and cardiac efficiency achieved at high demand are decreased with age, compared to maximal values in the young. Whether this deterioration is due to decrease in myocardial ATP demand, ATP supply, or the control mechanisms that match them remains controversial. Here we discuss evolving perspectives of age-related changes of myocardial ATP supply and demand mechanisms, and critique experimental models used to investigate aging. Specifically, we evaluate experimental data collected at the level of isolated mitochondria, tissue, or organism, and discuss how mitochondrial energetic mechanisms change in advanced age, both at basal and high energy-demand levels.
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Affiliation(s)
- Yael Yaniv
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, Maryland, USA
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Liu J, Sirenko S, Juhaszova M, Ziman B, Shetty V, Rain S, Shukla S, Spurgeon HA, Vinogradova TM, Maltsev VA, Lakatta EG. A full range of mouse sinoatrial node AP firing rates requires protein kinase A-dependent calcium signaling. J Mol Cell Cardiol 2011; 51:730-9. [PMID: 21840316 DOI: 10.1016/j.yjmcc.2011.07.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 06/24/2011] [Accepted: 07/26/2011] [Indexed: 11/24/2022]
Abstract
Recent perspectives on sinoatrial nodal cell (SANC)(*) function indicate that spontaneous sarcoplasmic reticulum (SR) Ca(2+) cycling, i.e. an intracellular "Ca(2+) clock," driven by cAMP-mediated, PKA-dependent phosphorylation, interacts with an ensemble of surface membrane electrogenic molecules ("surface membrane clock") to drive SANC normal automaticity. The role of AC-cAMP-PKA-Ca(2+) signaling cascade in mouse, the species most often utilized for genetic manipulations, however, has not been systematically tested. Here we show that Ca(2+) cycling proteins (e.g. RyR2, NCX1, and SERCA2) are abundantly expressed in mouse SAN and that spontaneous, rhythmic SR generated local Ca(2+) releases (LCRs) occur in skinned mouse SANC, clamped at constant physiologic [Ca(2+)]. Mouse SANC also exhibits a high basal level of phospholamban (PLB) phosphorylation at the PKA-dependent site, Serine16. Inhibition of intrinsic PKA activity or inhibition of PDE in SANC, respectively: reduces or increases PLB phosphorylation, and markedly prolongs or reduces the LCR period; and markedly reduces or accelerates SAN spontaneous firing rate. Additionally, the increase in AP firing rate by PKA-dependent phosphorylation by β-adrenergic receptor (β-AR) stimulation requires normal intracellular Ca(2+) cycling, because the β-AR chronotropic effect is markedly blunted when SR Ca(2+) cycling is disrupted. Thus, AC-cAMP-PKA-Ca(2+) signaling cascade is a major mechanism of normal automaticity in mouse SANC.
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Affiliation(s)
- Jie Liu
- Laboratory of Cardiovascular Science, Intramural Research Program, Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore MD 21224, USA
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Yaniv Y, Juhaszova M, Lyashkov AE, Spurgeon HA, Sollott SJ, Lakatta EG. Ca2+-regulated-cAMP/PKA signaling in cardiac pacemaker cells links ATP supply to demand. J Mol Cell Cardiol 2011; 51:740-8. [PMID: 21835182 DOI: 10.1016/j.yjmcc.2011.07.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 07/12/2011] [Accepted: 07/21/2011] [Indexed: 10/17/2022]
Abstract
RATIONALE In sinoatrial node cells (SANC), Ca(2+) activates adenylate cyclase (AC) to generate a high basal level of cAMP-mediated/protein kinase A (PKA)-dependent phosphorylation of Ca(2+) cycling proteins. These result in spontaneous sarcoplasmic-reticulum (SR) generated rhythmic Ca(2+) oscillations during diastolic depolarization, that not only trigger the surface membrane to generate rhythmic action potentials (APs), but, in a feed-forward manner, also activate AC/PKA signaling. ATP is consumed to pump Ca(2+) to the SR, to produce cAMP, to support contraction and to maintain cell ionic homeostasis. OBJECTIVE Since feedback mechanisms link ATP-demand to ATP production, we hypothesized that (1) both basal ATP supply and demand in SANC would be Ca(2+)-cAMP/PKA dependent; and (2) due to its feed-forward nature, a decrease in flux through the Ca(2+)-cAMP/PKA signaling axis will reduce the basal ATP production rate. METHODS AND RESULTS O(2) consumption in spontaneous beating SANC was comparable to ventricular myocytes (VM) stimulated at 3 Hz. Graded reduction of basal Ca(2+)-cAMP/PKA signaling to reduce ATP demand in rabbit SANC produced graded ATP depletion (r(2)=0.96), and reduced O(2) consumption and flavoprotein fluorescence. Neither inhibition of glycolysis, selectively blocking contraction nor specific inhibition of mitochondrial Ca(2+) flux reduced the ATP level. CONCLUSIONS Feed-forward basal Ca(2+)-cAMP/PKA signaling both consumes ATP to drive spontaneous APs in SANC and is tightly linked to mitochondrial ATP production. Interfering with Ca(2+)-cAMP/PKA signaling not only slows the firing rate and reduces ATP consumption, but also appears to reduce ATP production so that ATP levels fall. This distinctly differs from VM, which lack this feed-forward basal cAMP/PKA signaling, and in which ATP level remains constant when the demand changes.
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Affiliation(s)
- Yael Yaniv
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, Maryland 21224-6825, USA
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31
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Yaniv Y, Juhaszova M, Wang S, Fishbein KW, Zorov DB, Sollott SJ. Analysis of mitochondrial 3D-deformation in cardiomyocytes during active contraction reveals passive structural anisotropy of orthogonal short axes. PLoS One 2011; 6:e21985. [PMID: 21779362 PMCID: PMC3136939 DOI: 10.1371/journal.pone.0021985] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 06/13/2011] [Indexed: 11/19/2022] Open
Abstract
The cardiomyocyte cytoskeleton, composed of rigid and elastic elements, maintains the isolated cell in an elongated cylindrical shape with an elliptical cross-section, even during contraction-relaxation cycles. Cardiomyocyte mitochondria are micron-sized, fluid-filled passive spheres distributed throughout the cell in a crystal-like lattice, arranged in pairs sandwiched between the sarcomere contractile machinery, both longitudinally and radially. Their shape represents the extant 3-dimensional (3D) force-balance. We developed a novel method to examine mitochondrial 3D-deformation in response to contraction and relaxation to understand how dynamic forces are balanced inside cardiomyocytes. The variation in transmitted light intensity induced by the periodic lattice of myofilaments alternating with mitochondrial rows can be analyzed by Fourier transformation along a given cardiomyocyte axis to measure mitochondrial deformation along that axis. This technique enables precise detection of changes in dimension of ∼1% in ∼1 µm (long-axis) structures with 8 ms time-resolution. During active contraction (1 Hz stimulation), mitochondria deform along the length- and width-axes of the cell with similar deformation kinetics in both sarcomere and mitochondrial structures. However, significant deformation anisotropy (without hysteresis) was observed between the orthogonal short-axes (i.e., width and depth) of mitochondria during electrical stimulation. The same degree of deformation anisotropy was also found between the myocyte orthogonal short-axes during electrical stimulation. Therefore, the deformation of the mitochondria reflects the overall deformation of the cell, and the apparent stiffness and stress/strain characteristics of the cytoskeleton differ appreciably between the two cardiomyocyte orthogonal short-axes. This method may be applied to obtaining a better understanding of the dynamic force-balance inside cardiomyocytes and of changes in the spatial stiffness characteristics of the cytoskeleton that may accompany aging or pathological conditions.
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Affiliation(s)
- Yael Yaniv
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Su Wang
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Kenneth W. Fishbein
- Laboratory of Clinical Investigation, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Dmitry B. Zorov
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Steven J. Sollott
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- * E-mail:
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Yaniv Y, Juhaszova M, Lyashkov AE, Spurgeon HA, Sollott SJ, Lakatta EG. Ca2+-Regulated-cAMP/PKA Signaling in Cardiac Pacemaker Cells Links ATP Supply to Demand. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.2579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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33
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Ahmet I, Tae HJ, Juhaszova M, Riordon DR, Boheler KR, Sollott SJ, Brines M, Cerami A, Lakatta EG, Talan MI. A small nonerythropoietic helix B surface peptide based upon erythropoietin structure is cardioprotective against ischemic myocardial damage. Mol Med 2010; 17:194-200. [PMID: 21170473 DOI: 10.2119/molmed.2010.00235] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 12/15/2010] [Indexed: 01/23/2023] Open
Abstract
Strong cardioprotective properties of erythropoietin (EPO) reported over the last 10 years have been difficult to translate to clinical applications for ischemic cardioprotection owing to undesirable parallel activation of erythropoiesis and thrombogenesis. A pyroglutamate helix B surface peptide (pHBP), recently engineered to include only a part of the EPO molecule that does not bind to EPO receptor and thus, is not erythropoietic, retains tissue protective properties of EPO. Here we compared the ability of pHBP and EPO to protect cardiac myocytes from oxidative stress in vitro and cardiac tissue from ischemic damage in vivo. HBP, similar to EPO, increased the reactive oxygen species (ROS) threshold for induction of the mitochondrial permeability transition by 40%. In an experimental model of myocardial infarction induced by permanent ligation of a coronary artery in rats, a single bolus injection of 60 μg/kg of pHBP immediately after coronary ligation, similar to EPO, reduced apoptosis in the myocardial area at risk, examined 24 h later, by 80% and inflammation by 34%. Myocardial infarction (MI) measured 24 h after coronary ligation was similarly reduced by 50% in both pHBP- and EPO-treated rats. Two wks after surgery, left ventricular remodeling (ventricular dilation) and functional decline (fall in ejection fraction) assessed by echocardiography were significantly and similarly attenuated in pHBP- and EPO-treated rats, and MI size was reduced by 25%. The effect was retained during the 6-wk follow-up. A single bolus injection of pHBP immediately after coronary ligation was effective in reduction of MI size in a dose as low as 1 μg/kg, but was ineffective at a 60 μg/kg dose if administered 24 h after MI induction. We conclude that pHBP is equally cardioprotective with EPO and deserves further consideration as a safer alternative to rhEPO in the search for therapeutic options to reduce myocardial damage following blockade of the coronary circulation.
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Affiliation(s)
- Ismayil Ahmet
- Laboratory of Cardiovascular Sciences, National Institute on Aging, NIH, Baltimore, Maryland 21224-6825, United States of America
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Zhang Z, Hancock B, Leen S, Ramaswamy S, Sollott SJ, Boheler KR, Juhaszova M, Lakatta EG, Spencer RG, Fishbein KW. Compatibility of superparamagnetic iron oxide nanoparticle labeling for ¹H MRI cell tracking with ³¹P MRS for bioenergetic measurements. NMR Biomed 2010; 23:1166-72. [PMID: 20853523 PMCID: PMC3161830 DOI: 10.1002/nbm.1545] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Revised: 03/01/2010] [Accepted: 03/12/2010] [Indexed: 05/04/2023]
Abstract
Labeling of cells with superparamagnetic iron oxide nanoparticles permits cell tracking by (1)H MRI while (31)P MRS allows non-invasive evaluation of cellular bioenergetics. We evaluated the compatibility of these two techniques by obtaining (31)P NMR spectra of iron-labeled and unlabeled immobilized C2C12 myoblast cells in vitro. Broadened but usable (31)P spectra were obtained and peak area ratios of resonances corresponding to intracellular metabolites showed no significant differences between labeled and unlabeled cell populations. We conclude that (31)P NMR spectra can be obtained from cells labeled with sufficient iron to permit visualization by (1)H imaging protocols and that these spectra have sufficient quality to be used to assess metabolic status. This result introduces the possibility of using localized (31)P MRS to evaluate the viability of iron-labeled therapeutic cells as well as surrounding host tissue in vivo.
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Affiliation(s)
- Zhuoli Zhang
- Laboratory of Cardiovascular Science, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
- Laboratory of Clinical Investigation, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
| | - Brynne Hancock
- Laboratory of Clinical Investigation, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
| | - Stephanie Leen
- Laboratory of Clinical Investigation, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
| | - Sharan Ramaswamy
- Laboratory of Clinical Investigation, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
| | - Steven J. Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
| | - Kenneth R. Boheler
- Laboratory of Cardiovascular Science, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
| | - Edward G. Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
| | - Richard G. Spencer
- Laboratory of Clinical Investigation, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
| | - Kenneth W. Fishbein
- Laboratory of Clinical Investigation, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD
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35
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Yaniv Y, Juhaszova M, Nuss HB, Wang S, Zorov DB, Lakatta EG, Sollott SJ. Matching ATP supply and demand in mammalian heart: in vivo, in vitro, and in silico perspectives. Ann N Y Acad Sci 2010; 1188:133-42. [PMID: 20201896 PMCID: PMC2943203 DOI: 10.1111/j.1749-6632.2009.05093.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although the heart rapidly adapts cardiac output to match the body's circulatory demands, the regulatory mechanisms ensuring that sufficient ATP is available to perform the required cardiac work are not completely understood. Two mechanisms have been suggested to serve as key regulators: (1) ADP and Pi concentrations--ATP utilization/hydrolysis in the cytosol increases ADP and Pi fluxes to mitochondria and hence the amount of available substrates for ATP production increases; and (2) Ca2+ concentration--ATP utilization/hydrolysis is coupled to changes in free cytosolic calcium and mitochondrial calcium, the latter controlling Ca2+-dependent activation of mitochondrial enzymes taking part in ATP production. Here we discuss the evolving perspectives of each of the putative regulatory mechanisms and the precise molecular targets (dehydrogenase enzymes, ATP synthase) based on existing experimental and theoretical evidence. The data synthesis can generate novel hypotheses and experimental designs to solve the ongoing enigma of energy supply-demand matching in the heart.
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Affiliation(s)
- Yael Yaniv
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, Maryland 21224-6825, USA
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Zorov DB, Juhaszova M, Yaniv Y, Nuss HB, Wang S, Sollott SJ. Regulation and pharmacology of the mitochondrial permeability transition pore. Cardiovasc Res 2009; 83:213-25. [PMID: 19447775 PMCID: PMC2701724 DOI: 10.1093/cvr/cvp151] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 05/04/2009] [Accepted: 05/10/2009] [Indexed: 12/18/2022] Open
Abstract
The 'mitochondrial permeability transition', characterized by a sudden induced change of the inner mitochondrial membrane permeability for water as well as for small substances (=1.5 kDa), has been known for three decades. Research interest in the entity responsible for this phenomenon, the 'mitochondrial permeability transition pore' (mPTP), has dramatically increased after demonstration that it plays a key role in the life and death decision in cells. Therefore, a better understanding of this phenomenon and its regulation by environmental stresses, kinase signalling, and pharmacological intervention is vital. The characterization of the molecular identity of the mPTP will allow identification of possible pharmacological targets and assist in drug design for its precise regulation. However, despite extensive research efforts, at this point the pore-forming core component(s) of the mPTP remain unidentified. Pivotal new genetic evidence has shown that components once believed to be core elements of the mPTP (namely mitochondrial adenine nucleotide translocator and cyclophilin D) are instead only mPTP regulators (or in the case of voltage-dependent anion channels, probably entirely dispensable). This review provides an update on the current state of knowledge regarding the regulation of the mPTP.
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Affiliation(s)
| | | | | | | | | | - Steven J. Sollott
- Laboratory of Cardiovascular Science, Gerontology Research Center, Box 13, Intramural Research Program, National Institute on Aging, NIH, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825, USA
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37
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Abstract
Limitation of infarct size by ischemic/pharmacological pre- and postconditioning involves activation of a complex set of cell-signaling pathways. Multiple lines of evidence implicate the mitochondrial permeability transition pore (mPTP) as a key end effector of ischemic/pharmacological pre- and postconditioning. Increasing the ROS threshold for mPTP induction enhances the resistance of cardiomyocytes to oxidant stress and results in infarct size reduction. Here, we survey and synthesize the present knowledge about the role of glycogen synthase kinase (GSK)-3beta in cardioprotection, including pre- and postconditioning. Activation of a wide spectrum of cardioprotective signaling pathways is associated with phosphorylation and inhibition of a discrete pool of GSK-3beta relevant to mitochondrial signaling. Therefore, GSK-3beta has emerged as the integration point of many of these pathways and plays a central role in transferring protective signals downstream to target(s) that act at or in proximity to the mPTP. Bcl-2 family proteins and mPTP-regulatory elements, such as adenine nucleotide translocator and cyclophilin D (possibly voltage-dependent anion channel), may be the functional downstream target(s) of GSK-3beta. Gaining a better understanding of these interactions to control and prevent mPTP induction when appropriate will enable us to decrease the negative impact of the reperfusion-induced ROS burst on the fate of mitochondria and perhaps allow us to limit propagation of damage throughout and between cells and consequently, to better limit infarct size.
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Affiliation(s)
- Magdalena Juhaszova
- Laboratory of Cardiovascular Science, Gerontology Research Center, Box 13, National Institute on Aging, NIH, Baltimore, Maryland 21224-6825, USA
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Chiara F, Castellaro D, Marin O, Petronilli V, Brusilow WS, Juhaszova M, Sollott SJ, Forte M, Bernardi P, Rasola A. Hexokinase II detachment from mitochondria triggers apoptosis through the permeability transition pore independent of voltage-dependent anion channels. PLoS One 2008; 3:e1852. [PMID: 18350175 PMCID: PMC2267038 DOI: 10.1371/journal.pone.0001852] [Citation(s) in RCA: 226] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Accepted: 02/21/2008] [Indexed: 11/17/2022] Open
Abstract
Type II hexokinase is overexpressed in most neoplastic cells, and it mainly localizes on the outer mitochondrial membrane. Hexokinase II dissociation from mitochondria triggers apoptosis. The prevailing model postulates that hexokinase II release from its mitochondrial interactor, the voltage-dependent anion channel, prompts outer mitochondrial membrane permeabilization and the ensuing release of apoptogenic proteins, and that these events are inhibited by growth factor signalling. Here we show that a hexokinase II N-terminal peptide selectively detaches hexokinase II from mitochondria and activates apoptosis. These events are abrogated by inhibiting two established permeability transition pore modulators, the adenine nucleotide translocator or cyclophilin D, or in cyclophilin D knock-out cells. Conversely, insulin stimulation or genetic ablation of the voltage-dependent anion channel do not affect cell death induction by the hexokinase II peptide. Therefore, hexokinase II detachment from mitochondria transduces a permeability transition pore opening signal that results in cell death and does not require the voltage-dependent anion channel. These findings have profound implications for our understanding of the pathways of outer mitochondrial membrane permeabilization and their inactivation in tumors.
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Affiliation(s)
- Federica Chiara
- CNR Institute of Neuroscience and Department of Biomedical Sciences, University of Padova, Padova, Italy
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Juhaszova M, Wang S, Zorov DB, Nuss HB, Gleichmann M, Mattson MP, Sollott SJ. The identity and regulation of the mitochondrial permeability transition pore: where the known meets the unknown. Ann N Y Acad Sci 2008; 1123:197-212. [PMID: 18375592 DOI: 10.1196/annals.1420.023] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The mitochondrial permeability transition (MPT) pore complex is a key participant in the machinery that controls mitochondrial fate and, consequently, cell fate. The quest for the pore identity has been ongoing for several decades and yet the main structure remains unknown. Established "dogma" proposes that the core of the MPT pore is composed of an association of voltage-dependent anion channel (VDAC) and adenine nucleotide translocase (ANT). Recent genetic knockout experiments contradict this commonly accepted interpretation and provide a basis for substantial revision of the MPT pore identity. There is now sufficient evidence to exclude VDAC and ANT as the main pore structural components. Regarding MPT pore regulation, the role of cyclophilin D is confirmed and ANT may still serve some regulatory function, although the involvement of hexokinase II and creatine kinase remains unresolved. When cell protection signaling pathways are activated, we have found that the Bcl-2 family members relay the signal from glycogen synthase kinase-3 beta onto a target at or in close proximity to the pore. Our experimental findings in intact cardiac myocytes and neurons indicate that the current "dogma" related to the role of Ca2+ in MPT induction requires reevaluation. Emerging evidence suggests that after injury-producing stresses, reactive oxygen species (but not Ca2+) are largely responsible for the pore induction. In this article we discuss the current state of knowledge and provide new data related to the MPT pore structure and regulation.
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Affiliation(s)
- Magdalena Juhaszova
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD 21224-6825, USA
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Moaddel R, Oliveira R, Kimura T, Hyppolite P, Juhaszova M, Bernier M, Wainer I. Initial synthesis and characterization of an alpha7 nicotinic receptor cellular membrane affinity chromatography column: Effect of receptor subtype and cell type. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1127.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Regina Oliveira
- Departamento de QuimicaUniversidade Federal de Sao CarlosSao CarlosBrazil
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Moaddel R, Oliveira RV, Kimura T, Hyppolite P, Juhaszova M, Xiao Y, Kellar KJ, Bernier M, Wainer IW. Initial synthesis and characterization of an alpha7 nicotinic receptor cellular membrane affinity chromatography column: effect of receptor subtype and cell type. Anal Chem 2007; 80:48-54. [PMID: 18062706 DOI: 10.1021/ac701943b] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, cellular membrane fragments from SH-EP1-pCEP4-halpha7 and alpha7 HEK-293 cell lines were used to synthesize cellular membrane affinity chromatography (CMAC) columns containing functional alpha7 nicotinic acetylcholine receptors, CMAC(alpha7 nAChR) columns. The synthesis of stable columns required the addition of cholesterol to the 2% cholate solubilization/immobilization (s/i) buffer and to the mobile phase. In addition, when membranes from the SH-EP1 cell line were used, l-alpha-phosphatidylserine and l-alpha-phosphatidylethanolamine also had to be added to the s/i buffer. A CMAC(alpha4beta2 nAChR) column was prepared using membrane fragments from a SH-EP1-pCEP4-halpha4beta2 cell line, and this process required the addition of l-alpha-phosphatidylserine and l-alpha-phosphatidylethanolamine to the s/i buffer, but not cholesterol. The s/i buffers from the three columns were compared with the s/i buffer utilized in the preparation of a CMAC(alpha4beta2 nAChR) column prepared using an alpha4beta2 HEK-293 cell line, which required no additions to the 2% cholate s/i buffer. The data demonstrate that both cell type and receptor type affect the protocol required to produce a stable CMAC column and that, at the current time, the development of an optimum immobilization protocol is an empirical process. The results are also consistent with the observation that the alpha7 nAChR is localized in lipid rafts in both of these cell lines and that the cholate detergent removed cholesterol from these microdomains.
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Affiliation(s)
- Ruin Moaddel
- Gerontology Research Center, National Institutes on Aging, National Institutes of Health, Baltimore, Maryland 21224-6825, USA.
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Jang HJ, Kokrashvili Z, Theodorakis MJ, Carlson OD, Kim BJ, Zhou J, Kim HH, Xu X, Chan SL, Juhaszova M, Bernier M, Mosinger B, Margolskee RF, Egan JM. Gut-expressed gustducin and taste receptors regulate secretion of glucagon-like peptide-1. Proc Natl Acad Sci U S A 2007; 104:15069-74. [PMID: 17724330 PMCID: PMC1986614 DOI: 10.1073/pnas.0706890104] [Citation(s) in RCA: 739] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1), released from gut endocrine L cells in response to glucose, regulates appetite, insulin secretion, and gut motility. How glucose given orally, but not systemically, induces GLP-1 secretion is unknown. We show that human duodenal L cells express sweet taste receptors, the taste G protein gustducin, and several other taste transduction elements. Mouse intestinal L cells also express alpha-gustducin. Ingestion of glucose by alpha-gustducin null mice revealed deficiencies in secretion of GLP-1 and the regulation of plasma insulin and glucose. Isolated small bowel and intestinal villi from alpha-gustducin null mice showed markedly defective GLP-1 secretion in response to glucose. The human L cell line NCI-H716 expresses alpha-gustducin, taste receptors, and several other taste signaling elements. GLP-1 release from NCI-H716 cells was promoted by sugars and the noncaloric sweetener sucralose, and blocked by the sweet receptor antagonist lactisole or siRNA for alpha-gustducin. We conclude that L cells of the gut "taste" glucose through the same mechanisms used by taste cells of the tongue. Modulating GLP-1 secretion in gut "taste cells" may provide an important treatment for obesity, diabetes and abnormal gut motility.
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Affiliation(s)
- Hyeung-Jin Jang
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
| | - Zaza Kokrashvili
- Department of Neuroscience, Mount Sinai School of Medicine, 1425 Madison Avenue, Box 1065, New York, NY 10029
| | - Michael J. Theodorakis
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
| | - Olga D. Carlson
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
| | - Byung-Joon Kim
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
| | - Jie Zhou
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
| | - Hyeon Ho Kim
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
| | - Xiangru Xu
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
| | - Sic L. Chan
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
| | - Magdalena Juhaszova
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
| | - Michel Bernier
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
| | - Bedrich Mosinger
- Department of Neuroscience, Mount Sinai School of Medicine, 1425 Madison Avenue, Box 1065, New York, NY 10029
| | - Robert F. Margolskee
- Department of Neuroscience, Mount Sinai School of Medicine, 1425 Madison Avenue, Box 1065, New York, NY 10029
- To whom correspondence should be addressed. E-mail:
| | - Josephine M. Egan
- *National Institute on Aging/National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224; and
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Lyashkov AE, Juhaszova M, Dobrzynski H, Vinogradova TM, Maltsev VA, Juhasz O, Spurgeon HA, Sollott SJ, Lakatta EG. Calcium cycling protein density and functional importance to automaticity of isolated sinoatrial nodal cells are independent of cell size. Circ Res 2007; 100:1723-31. [PMID: 17525366 DOI: 10.1161/circresaha.107.153676] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Spontaneous, localized, rhythmic ryanodine receptor (RyRs) Ca(2+) releases occur beneath the cell membrane during late diastolic depolarization in cardiac sinoatrial nodal cells (SANCs). These activate the Na(+)/Ca(2+) exchanger (NCX1) to generate inward current and membrane excitation that drives normal spontaneous beating. The morphological background for the proposed functional of RyR and NCX crosstalk, however, has not been demonstrated. Here we show that the average isolated SANC whole cell labeling density of RyRs and SERCA2 is similar to atrial and ventricle myocytes, and is similar among SANCs of all sizes. Labeling of NCX1 is also similar among SANCs of all sizes and exceeds that in atrial and ventricle myocytes. Submembrane colocalization of NCX1 and cardiac RyR (cRyR) in all SANCs exceeds that in the other cell types. Further, the Cx43 negative primary pacemaker area of the intact rabbit sinoatrial node (SAN) exhibits robust positive labeling for cRyR, NCX1, and SERCA2. Functional studies in isolated SANCs show that neither the average action potential (AP) characteristics, nor those of intracellular Ca(2+) releases, nor the spontaneous cycle length vary with cell size. Chelation of intracellular [Ca(2+)], or disabling RyRs or NCX1, markedly attenuates or abolishes spontaneous SANC beating in all SANCs. Thus, there is dense labeling of SERCA2, RyRs, and NCX1 in small-sized SANCs, thought to reside within the SAN center, the site of impulse initiation. Because normal automaticity of these cells requires intact Ca(2+) cycling, interactions of SERCA, RyR2 and NCX molecules are implicated in the initiation of the SAN impulse.
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Affiliation(s)
- Alexey E Lyashkov
- Laboratory of Cardiovascular Science, Gerontology Research Center, NIA, NIH, Baltimore, Maryland 21224-6825, USA
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Zorov DB, Juhaszova M, Sollott SJ. Mitochondrial ROS-induced ROS release: an update and review. Biochim Biophys Acta 2006; 1757:509-17. [PMID: 16829228 DOI: 10.1016/j.bbabio.2006.04.029] [Citation(s) in RCA: 1018] [Impact Index Per Article: 56.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2006] [Revised: 03/24/2006] [Accepted: 04/28/2006] [Indexed: 11/26/2022]
Abstract
Unstable mitochondrial membrane potential and redox transitions can occur following insults including ischemia/reperfusion injury and toxin exposure, with negative consequences for mitochondrial integrity and cellular survival. These transitions can involve mechanisms such as the recently described process, "Reactive Oxygen Species (ROS)-induced ROS-release" (RIRR), and be generated by circuits where the mitochondrial permeability transition (MPT) pore and the inner membrane anion channel (IMAC) are involved. The exposure to excessive oxidative stress results in an increase in ROS reaching a threshold level that triggers the opening of one of the requisite mitochondrial channels. In turn, this leads to the simultaneous collapse of the mitochondrial membrane potential and a transient increased ROS generation by the electron transfer chain. Generated ROS can be released into cytosol and trigger RIRR in neighboring mitochondria. This mitochondrion-to-mitochondrion ROS-signaling constitutes a positive feedback mechanism for enhanced ROS production leading to potentially significant mitochondrial and cellular injury. This review and update considers a variety of RIRR mechanisms (involving MPT, IMAC and episodes of mitochondrial transient hyperpolarization). RIRR could be a general cell biology phenomenon relevant to the processes of programmed mitochondrial destruction and cell death, and may contribute to other mechanisms of post-ischemic pathologies, including arrhythmias.
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Affiliation(s)
- Dmitry B Zorov
- Laboratory of Cardiovascular Science, Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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Theodorakis MJ, Carlson O, Michopoulos S, Doyle ME, Juhaszova M, Petraki K, Egan JM. Human duodenal enteroendocrine cells: source of both incretin peptides, GLP-1 and GIP. Am J Physiol Endocrinol Metab 2006; 290:E550-9. [PMID: 16219666 DOI: 10.1152/ajpendo.00326.2004] [Citation(s) in RCA: 263] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Among the products of enteroendocrine cells are the incretins glucagon-like peptide-1 (GLP-1, secreted by L cells) and glucose-dependent insulinotropic peptide (GIP, secreted by K cells). These are key modulators of insulin secretion, glucose homeostasis, and gastric emptying. Because of the rapid early rise of GLP-1 in plasma after oral glucose, we wished to definitively establish the absence or presence of L cells, as well as the relative distribution of the incretin cell types in human duodenum. We confirmed the presence of proglucagon and pro-GIP genes, their products, and glucosensory molecules by tissue immunohistochemistry and RT-PCR of laser-captured, single duodenal cells. We also assayed plasma glucose, incretin, and insulin levels in subjects with normal glucose tolerance and type 2 diabetes for 120 min after they ingested 75 g of glucose. Subjects with normal glucose tolerance (n=14) had as many L cells (15+/-1), expressed per 1,000 gut epithelial cells, as K cells (13+/-1), with some containing both hormones (L/K cells, 5+/-1). In type 2 diabetes, the number of L and L/K cells was increased (26+/-2; P<0.001 and 9+/-1; P < 0.001, respectively). Both L and K cells contained glucokinase and glucose transporter-1, -2, and -3. Newly diagnosed type 2 diabetic subjects had increased plasma GLP-1 levels between 20 and 80 min, concurrently with rising plasma insulin levels. Significant coexpression of the main incretin peptides occurs in human duodenum. L and K cells are present in equal numbers. New onset type 2 diabetes is associated with a shift to the L phenotype.
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Affiliation(s)
- Michael J Theodorakis
- Diabetes Section, Laboratory of Clinical Investigation, National Institute of Health, Baltimore, MD 21224, USA
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Moon C, Krawczyk M, Paik D, Coleman T, Brines M, Juhaszova M, Sollott SJ, Lakatta EG, Talan MI. Erythropoietin, Modified to Not Stimulate Red Blood Cell Production, Retains Its Cardioprotective Properties. J Pharmacol Exp Ther 2005; 316:999-1005. [PMID: 16306273 DOI: 10.1124/jpet.105.094854] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Erythropoietin (EPO), a hematopoietic cytokine, possesses strong antiapoptotic, tissue-protective properties. For clinical applications, it is desirable to separate the hematopoietic and tissue-protective properties. Recently introduced carbamylated erythropoietin (CEPO) does not stimulate the erythropoiesis but retains the antiapoptotic and neuroprotective effects. We tested the ability of CEPO to protect cardiac tissue from toxin-induced and oxidative stress in vitro and ischemic damage in vivo and compared these effects with the effects of EPO. CEPO reduced by 50% the extent of staurosporine-induced apoptosis in isolated rats' cardiomyocytes and increased by 25% the reactive oxygen species threshold for induction of the mitochondrial permeability transition. In an experimental model of myocardial infarction induced by permanent ligation of a coronary artery in rats, similarly to EPO, a single bolus injection of 30 mug/kg b.wt. of CEPO immediately after coronary ligation reduced apoptosis in the myocardial area at risk, examined 24 h later, by 50%. Left ventricular remodeling (ventricular dilation) and functional decline (fall in ejection fraction) assessed by repeated echocardiography were significantly and similarly attenuated in CEPO- and EPO-treated rats. Four weeks after coronary ligation, the myocardial infarction (MI) size in CEPO- and EPO-treated rats was half of that in untreated coronary-ligated animals. Unlike EPO, CEPO had no effect on hematocrit. The antiapoptotic cardioprotective effects of CEPO, shown by its ability to limit both post-MI left ventricular remodeling and the extent of the myocardial scar in the model of permanent coronary artery ligation in rats, demonstrate comparable potency to that of native (nonmodified) EPO.
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Affiliation(s)
- Chanil Moon
- Laboratory of Cardiovascular Sciences, Gerontology Research Center, National Institute on Aging, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825, USA
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Pullmann R, Juhaszova M, López de Silanes I, Kawai T, Mazan-Mamczarz K, Halushka MK, Gorospe M. Enhanced proliferation of cultured human vascular smooth muscle cells linked to increased function of RNA-binding protein HuR. J Biol Chem 2005; 280:22819-26. [PMID: 15824116 PMCID: PMC1350862 DOI: 10.1074/jbc.m501106200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In dividing cells, the RNA-binding protein HuR associates with and stabilizes labile mRNAs encoding proliferative proteins, events that are linked to the increased cytoplasmic presence of HuR. Here, assessment of HuR levels in various vascular pathologies (intimal hyperplasia, atherosclerosis and neointimal proliferation, sclerosis of arterialized saphenous venous graft, and fibromuscular dysplasia) revealed a distinct increase in HuR expression and cytoplasmic abundance within the intima and neointima layers. On the basis of these observations, we postulated a role for HuR in promoting the proliferation of vascular smooth muscle cells. To test this hypothesis directly, we investigated the expression, subcellular localization, and proliferative influence of HuR in human vascular smooth muscle cells (hVSMCs). Treatment of hVSMCs with platelet-derived growth factor increased HuR levels in the cytoplasm, thereby influencing the expression of metabolic, proliferative, and structural genes. Importantly, knockdown of HuR expression by using RNA interference caused a reduction of hVSMC proliferation, both basally and following platelet-derived growth factor treatment. We propose that HuR contributes to regulating hVSMC growth and homeostasis in pathologies associated with vascular smooth muscle proliferation.
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Affiliation(s)
- Rudolf Pullmann
- Laboratory of Cellular and Molecular Biology and Laboratory of Cardiovascular Sciences, NIA-Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA
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Juhaszova M, Rabuel C, Zorov DB, Lakatta EG, Sollott SJ. Protection in the aged heart: preventing the heart-break of old age? Cardiovasc Res 2005; 66:233-44. [PMID: 15820192 DOI: 10.1016/j.cardiores.2004.12.020] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2004] [Revised: 12/10/2004] [Accepted: 12/27/2004] [Indexed: 11/30/2022] Open
Abstract
The aged heart has a diminished functional and adaptive reserve capacity, an increased susceptibility to incur damage (e.g., as a result of ischemia), and a limited practical ability for repair/regeneration. Thus, there has been considerable interest to harness the heart's endogenous capacity to resist such damage, known as ischemic preconditioning (IPC), as well as other cardioprotective mechanisms. However, the translation of basic research findings into clinical practice has largely been inadequate because there have been few if any successful implementations in terms of viable therapies activating cardioprotection mechanisms to limit infarct size. Here, we provide an overview of the general mechanisms of cardioprotection, changes in the structure and function of the aged heart, and the current knowledge regarding cardioprotection in aged heart. The problems and opportunities for successful bench-to-bedside translation of cardioprotection in the elderly are discussed.
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Affiliation(s)
- Magdalena Juhaszova
- Laboratory of Cardiovascular Sciences, Gerontology Research Center, Box 13 Intramural Research Program, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Dr., Baltimore, MD 21224-6825, USA
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Abstract
Fluorescence microscopy imaging has become one of the most useful techniques to assess the activity of individual cells, subcellular trafficking of signals to and between organelles, and to appreciate how organelle function is regulated. The past 2 decades have seen a tremendous advance in the rational design and development in the nature and selectivity of probes to serve as reporters of the intracellular environment in live cells. These probes range from small organic fluorescent molecules to fluorescent biomolecules and photoproteins ingeniously engineered to follow signaling traffic, sense ionic and nonionic second messengers, and report various kinase activities. These probes, together with recent advances in imaging technology, have enabled significantly enhanced spatial and temporal resolution. This review summarizes some of these developments and their applications to assess intracellular organelle function.
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Affiliation(s)
- Dmitry B Zorov
- Laboratories of Cardiovascular Sciences, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Md 21224-6825, USA
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50
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Juhaszova M, Zorov DB, Kim SH, Pepe S, Fu Q, Fishbein KW, Ziman BD, Wang S, Ytrehus K, Antos CL, Olson EN, Sollott SJ. Glycogen synthase kinase-3beta mediates convergence of protection signaling to inhibit the mitochondrial permeability transition pore. J Clin Invest 2004; 113:1535-49. [PMID: 15173880 PMCID: PMC419483 DOI: 10.1172/jci19906] [Citation(s) in RCA: 722] [Impact Index Per Article: 36.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2003] [Accepted: 03/30/2004] [Indexed: 01/09/2023] Open
Abstract
Environmental stresses converge on the mitochondria that can trigger or inhibit cell death. Excitable, postmitotic cells, in response to sublethal noxious stress, engage mechanisms that afford protection from subsequent insults. We show that reoxygenation after prolonged hypoxia reduces the reactive oxygen species (ROS) threshold for the mitochondrial permeability transition (MPT) in cardiomyocytes and that cell survival is steeply negatively correlated with the fraction of depolarized mitochondria. Cell protection that exhibits a memory (preconditioning) results from triggered mitochondrial swelling that causes enhanced substrate oxidation and ROS production, leading to redox activation of PKC, which inhibits glycogen synthase kinase-3beta (GSK-3beta). Alternatively, receptor tyrosine kinase or certain G protein-coupled receptor activation elicits cell protection (without mitochondrial swelling or durable memory) by inhibiting GSK-3beta, via protein kinase B/Akt and mTOR/p70(s6k) pathways, PKC pathways, or protein kinase A pathways. The convergence of these pathways via inhibition of GSK-3beta on the end effector, the permeability transition pore complex, to limit MPT induction is the general mechanism of cardiomyocyte protection.
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Affiliation(s)
- Magdalena Juhaszova
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, Maryland 21224-6825, USA
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