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Liu X, Oh S, Kirschner MW. The uniformity and stability of cellular mass density in mammalian cell culture. Front Cell Dev Biol 2022; 10:1017499. [PMID: 36313562 PMCID: PMC9597509 DOI: 10.3389/fcell.2022.1017499] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 09/23/2022] [Indexed: 12/04/2022] Open
Abstract
Cell dry mass is principally determined by the sum of biosynthesis and degradation. Measurable change in dry mass occurs on a time scale of hours. By contrast, cell volume can change in minutes by altering the osmotic conditions. How changes in dry mass and volume are coupled is a fundamental question in cell size control. If cell volume were proportional to cell dry mass during growth, the cell would always maintain the same cellular mass density, defined as cell dry mass dividing by cell volume. The accuracy and stability against perturbation of this proportionality has never been stringently tested. Normalized Raman Imaging (NoRI), can measure both protein and lipid dry mass density directly. Using this new technique, we have been able to investigate the stability of mass density in response to pharmaceutical and physiological perturbations in three cultured mammalian cell lines. We find a remarkably narrow mass density distribution within cells, that is, significantly tighter than the variability of mass or volume distribution. The measured mass density is independent of the cell cycle. We find that mass density can be modulated directly by extracellular osmolytes or by disruptions of the cytoskeleton. Yet, mass density is surprisingly resistant to pharmacological perturbations of protein synthesis or protein degradation, suggesting there must be some form of feedback control to maintain the homeostasis of mass density when mass is altered. By contrast, physiological perturbations such as starvation or senescence induce significant shifts in mass density. We have begun to shed light on how and why cell mass density remains fixed against some perturbations and yet is sensitive during transitions in physiological state.
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Lopina OD, Tverskoi AM, Klimanova EA, Sidorenko SV, Orlov SN. Ouabain-Induced Cell Death and Survival. Role of α1-Na,K-ATPase-Mediated Signaling and [Na +] i/[K +] i-Dependent Gene Expression. Front Physiol 2020; 11:1060. [PMID: 33013454 PMCID: PMC7498651 DOI: 10.3389/fphys.2020.01060] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/31/2020] [Indexed: 12/12/2022] Open
Abstract
Ouabain is of cardiotonic steroids (CTS) family that is plant-derived compounds and is known for many years as therapeutic and cytotoxic agents. They are specific inhibitors of Na,K-ATPase, the enzyme, which pumps Na+ and K+ across plasma membrane of animal cells. Treatment of cells by CTS affects various cellular functions connected with the maintenance of the transmembrane gradient of Na+ and K+. Numerous studies demonstrated that binding of CTS to Na,K-ATPase not only suppresses its activity but also induces some signal pathways. This review is focused on different mechanisms of two ouabain effects: their ability (1) to protect rodent cells from apoptosis through the expression of [Na+]i-sensitive genes and (2) to trigger death of non-rodents cells (so-called «oncosis»), possessing combined markers of «classic» necrosis and «classic» apoptosis. Detailed study of oncosis demonstrated that the elevation of the [Na+]i/[K+]i ratio is not a sufficient for its triggering. Non-rodent cell death is determined by the characteristic property of "sensitive" to ouabain α1-subunit of Na,K-ATPase. In this case, ouabain binding leads to enzyme conformational changes triggering the activation of p38 mitogen-activated protein kinases (MAPK) signaling. The survival of rodent cells with ouabain-«resistant» α1-subunit is connected with another conformational transition induced by ouabain binding that results in the activation of ERK 1/2 signaling pathway.
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Affiliation(s)
- Olga Dmitrievna Lopina
- Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Artem Mikhaylovich Tverskoi
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences (RAS), Moscow, Russia
- Laboratory of Biological Membranes, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | | | | | - Sergei Nikolaevich Orlov
- Laboratory of Biological Membranes, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
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Na⁺ i,K⁺ i-Dependent and -Independent Signaling Triggered by Cardiotonic Steroids: Facts and Artifacts. Molecules 2017; 22:molecules22040635. [PMID: 28420099 PMCID: PMC6153942 DOI: 10.3390/molecules22040635] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 03/31/2017] [Accepted: 04/11/2017] [Indexed: 11/17/2022] Open
Abstract
Na⁺,K⁺-ATPase is the only known receptor of cardiotonic steroids (CTS) whose interaction with catalytic α-subunits leads to inhibition of this enzyme. As predicted, CTS affect numerous cellular functions related to the maintenance of the transmembrane gradient of monovalent cations, such as electrical membrane potential, cell volume, transepithelial movement of salt and osmotically-obliged water, symport of Na⁺ with inorganic phosphate, glucose, amino acids, nucleotides, etc. During the last two decades, it was shown that side-by-side with these canonical Na⁺i/K⁺i-dependent cellular responses, long-term exposure to CTS affects transcription, translation, tight junction, cell adhesion and exhibits tissue-specific impact on cell survival and death. It was also shown that CTS trigger diverse signaling cascades via conformational transitions of the Na⁺,K⁺-ATPase α-subunit that, in turn, results in the activation of membrane-associated non-receptor tyrosine kinase Src, phosphatidylinositol 3-kinase and the inositol 1,4,5-triphosphate receptor. These findings allowed researchers to propose that endogenous CTS might be considered as a novel class of steroid hormones. We focus our review on the analysis of the relative impact Na⁺i,K⁺i-mediated and -independent pathways in cellular responses evoked by CTS.
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Venugopal J, Blanco G. Ouabain Enhances ADPKD Cell Apoptosis via the Intrinsic Pathway. Front Physiol 2016; 7:107. [PMID: 27047392 PMCID: PMC4805603 DOI: 10.3389/fphys.2016.00107] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 03/07/2016] [Indexed: 11/13/2022] Open
Abstract
Progression of autosomal dominant polycystic kidney disease (ADPKD) is highly influenced by factors circulating in blood. We have shown that the hormone ouabain enhances several characteristics of the ADPKD cystic phenotype, including the rate of cell proliferation, fluid secretion and the capacity of the cells to form cysts. In this work, we found that physiological levels of ouabain (3 nM) also promote programmed cell death of renal epithelial cells obtained from kidney cysts of patients with ADPKD (ADPKD cells). This was determined by Alexa Fluor 488 labeled-Annexin-V staining and TUNEL assay, both biochemical markers of apoptosis. Ouabain-induced apoptosis also takes place when ADPKD cell growth is blocked; suggesting that the effect is not secondary to the stimulatory actions of ouabain on cell proliferation. Ouabain alters the expression of BCL family of proteins, reducing BCL-2 and increasing BAX expression levels, anti- and pro-apoptotic mediators respectively. In addition, ouabain caused the release of cytochrome c from mitochondria. Moreover, ouabain activates caspase-3, a key “executioner” caspase in the cell apoptotic pathway, but did not affect caspase-8. This suggests that ouabain triggers ADPKD cell apoptosis by stimulating the intrinsic, but not the extrinsic pathway of programmed cell death. The apoptotic effects of ouabain are specific for ADPKD cells and do not occur in normal human kidney cells (NHK cells). Taken together with our previous observations, these results show that ouabain causes an imbalance in cell growth/death, to favor growth of the cystic cells. This event, characteristic of ADPKD, further suggests the importance of ouabain as a circulating factor that promotes ADPKD progression.
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Affiliation(s)
- Jessica Venugopal
- Department of Molecular and Integrative Physiology and The Kidney Institute, University of Kansas Medical Center Kansas City, KS, USA
| | - Gustavo Blanco
- Department of Molecular and Integrative Physiology and The Kidney Institute, University of Kansas Medical Center Kansas City, KS, USA
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Rocha SC, Pessoa MTC, Neves LDR, Alves SLG, Silva LM, Santos HL, Oliveira SMF, Taranto AG, Comar M, Gomes IV, Santos FV, Paixão N, Quintas LEM, Noël F, Pereira AF, Tessis ACSC, Gomes NLS, Moreira OC, Rincon-Heredia R, Varotti FP, Blanco G, Villar JAFP, Contreras RG, Barbosa LA. 21-Benzylidene digoxin: a proapoptotic cardenolide of cancer cells that up-regulates Na,K-ATPase and epithelial tight junctions. PLoS One 2014; 9:e108776. [PMID: 25290152 PMCID: PMC4188576 DOI: 10.1371/journal.pone.0108776] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 08/25/2014] [Indexed: 02/07/2023] Open
Abstract
Cardiotonic steroids are used to treat heart failure and arrhythmia and have promising anticancer effects. The prototypic cardiotonic steroid ouabain may also be a hormone that modulates epithelial cell adhesion. Cardiotonic steroids consist of a steroid nucleus and a lactone ring, and their biological effects depend on the binding to their receptor, Na,K-ATPase, through which, they inhibit Na+ and K+ ion transport and activate of several intracellular signaling pathways. In this study, we added a styrene group to the lactone ring of the cardiotonic steroid digoxin, to obtain 21-benzylidene digoxin (21-BD), and investigated the effects of this synthetic cardiotonic steroid in different cell models. Molecular modeling indicates that 21-BD binds to its target Na,K-ATPase with low affinity, adopting a different pharmacophoric conformation when bound to its receptor than digoxin. Accordingly, 21-DB, at relatively high µM amounts inhibits the activity of Na,K-ATPase α1, but not α2 and α3 isoforms. In addition, 21-BD targets other proteins outside the Na,K-ATPase, inhibiting the multidrug exporter Pdr5p. When used on whole cells at low µM concentrations, 21-BD produces several effects, including: 1) up-regulation of Na,K-ATPase expression and activity in HeLa and RKO cancer cells, which is not found for digoxin, 2) cell specific changes in cell viability, reducing it in HeLa and RKO cancer cells, but increasing it in normal epithelial MDCK cells, which is different from the response to digoxin, and 3) changes in cell-cell interaction, altering the molecular composition of tight junctions and elevating transepithelial electrical resistance of MDCK monolayers, an effect previously found for ouabain. These results indicate that modification of the lactone ring of digoxin provides new properties to the compound, and shows that the structural change introduced could be used for the design of cardiotonic steroid with novel functions.
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Affiliation(s)
- Sayonarah C. Rocha
- Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Marco T. C. Pessoa
- Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Luiza D. R. Neves
- Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Silmara L. G. Alves
- Laboratório de Síntese Orgânica, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Luciana M. Silva
- Laboratório de Biologia Celular e Inovação Biotecnológica, Fundação Ezequiel Dias, Belo Horizonte, MG, Brazil
| | - Herica L. Santos
- Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Soraya M. F. Oliveira
- Laboratório de Bioinformática, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Alex G. Taranto
- Laboratório de Bioinformática, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Moacyr Comar
- Laboratório de Bioinformática, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Isabella V. Gomes
- Laboratório de Biologia Celular e Mutagenicidade, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Fabio V. Santos
- Laboratório de Biologia Celular e Mutagenicidade, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Natasha Paixão
- Laboratório de Farmacologia Bioquímica e Molecular, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Luis E. M. Quintas
- Laboratório de Farmacologia Bioquímica e Molecular, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - François Noël
- Laboratório de Farmacologia Bioquímica e Molecular, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Antonio F. Pereira
- Laboratório de Bioquímica Microbiana, Instituto de Microbiologia Paulo Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Ana C. S. C. Tessis
- Laboratório de Bioquímica Microbiana, Instituto de Microbiologia Paulo Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro (IFRJ), Rio de Janeiro, RJ, Brazil
| | - Natalia L. S. Gomes
- Laboratório de Biologia Molecular e Doenças Endêmicas, Instituto Oswaldo Cruz/Fiocruz, Rio de Janeiro, RJ, Brazil
| | - Otacilio C. Moreira
- Laboratório de Biologia Molecular e Doenças Endêmicas, Instituto Oswaldo Cruz/Fiocruz, Rio de Janeiro, RJ, Brazil
| | - Ruth Rincon-Heredia
- Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - Fernando P. Varotti
- Laboratório de Bioquímica de Parasitos, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Gustavo Blanco
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Jose A. F. P. Villar
- Laboratório de Síntese Orgânica, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
| | - Rubén G. Contreras
- Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - Leandro A. Barbosa
- Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil
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Live fluorescence and transmission-through-dye microscopic study of actinomycin D-induced apoptosis and apoptotic volume decrease. Apoptosis 2014; 18:521-32. [PMID: 23325449 DOI: 10.1007/s10495-013-0804-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The effect of actinomycin D on HeLa cells was studied by live fluorescence and transmission-through-dye microscopy-a recently developed technique that permits volume measurements in live cells. In particular, it is well suited for the observation and quantification of the apoptotic volume decrease (AVD), which is widely viewed as an essential feature of apoptosis. The main results from our study are as follows. (1) Apoptosis caused in HeLa cells by actinomycin D proceeds in two morphologically distinct stages: the early stage is characterized by extensive blebbing, and the late stage by a more compact shape. The loss of mitochondrial membrane potential occurs at about the same time as blebbing, and chromatin condensation follows 30-90 min later. Caspase-3 and 7 become activated during the late stage. (2) Because blebbing occurs before activation of caspase-3, it has to be initiated by a different mechanism. Although blebbing is one of the earliest observable changes, it can be selectively inhibited without affecting other apoptotic reactions. (3) The majority of cells experience a temporary volume increase after the appearance of blebs. Eventually, AVD takes over and the cells shrink by approximately 40 % of their initial volume; the volume loss becomes noticeable at the end of the blebbing phase and continues through the late stage. Sometimes, at the end of long incubations, shrinkage gives way to swelling, possibly indicating secondary necrosis. (4) Both early and late apoptosis are accompanied by intracellular accumulation of Na(+), while low-sodium medium prevents apoptosis. Except for a partial protective effect of quinine, all of the tested blockers of Na(+), K(+) and Cl(-) channels failed to prevent apoptosis or AVD.
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Orlov SN, Platonova AA, Hamet P, Grygorczyk R. Cell volume and monovalent ion transporters: their role in cell death machinery triggering and progression. Am J Physiol Cell Physiol 2013; 305:C361-72. [PMID: 23615964 DOI: 10.1152/ajpcell.00040.2013] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cell death is accompanied by the dissipation of electrochemical gradients of monovalent ions across the plasma membrane that, in turn, affects cell volume via modulation of intracellular osmolyte content. In numerous cell types, apoptotic and necrotic stimuli caused cell shrinkage and swelling, respectively. Thermodynamics predicts a cell type-specific rather than an ubiquitous impact of monovalent ion transporters on volume perturbations in dying cells, suggesting their diverse roles in the cell death machinery. Indeed, recent data showed that apoptotic collapse may occur in the absence of cell volume changes and even follow cell swelling rather than shrinkage. Moreover, side-by-side with cell volume adjustment, monovalent ion transporters contribute to cell death machinery engagement independently of volume regulation via cell type-specific signaling pathways. Thus, inhibition of Na(+)-K(+)-ATPase by cardiotonic steroids (CTS) rescues rat vascular smooth muscle cells from apoptosis via a novel Na(+)i-K(+)i-mediated, Ca(2+)i-independent mechanism of excitation-transcription coupling. In contrast, CTS kill renal epithelial cells independently of Na(+)-K(+)-ATPase inhibition and increased [Na(+)]i/[K(+)]i ratio. The molecular origin of [Na(+)]i/[K(+)]i sensors involved in the inhibition of apoptosis as well as upstream intermediates of Na(+)i/K(+)i-independent death signaling triggered by CTS remain unknown.
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Affiliation(s)
- Sergei N Orlov
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada.
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