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Influence of Endogenous Cardiac Glycosides, Digoxin, and Marinobufagenin in the Physiology of Epithelial Cells. Cardiol Res Pract 2019; 2019:8646787. [PMID: 32089875 PMCID: PMC7024086 DOI: 10.1155/2019/8646787] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/20/2019] [Accepted: 11/15/2019] [Indexed: 12/14/2022] Open
Abstract
Cardiac glycosides are a group of compounds widely known for their action in cardiac tissue, some of which have been found to be endogenously produced (ECG). We have previously studied the effect of ouabain, an endogenous cardiac glycoside, on the physiology of epithelial cells, and we have shown that in concentrations in the nanomolar range, it affects key properties of epithelial cells, such as tight junction, apical basolateral polarization, gap junctional intercellular communication (GJIC), and adherent junctions. In this work, we study the influence of digoxin and marinobufagenin, two other endogenously expressed cardiac glycosides, on GJIC as well as the degree of transepithelial tightness due to tight junction integrity (TJ). We evaluated GJIC by dye transfer assays and tight junction integrity by transepithelial electrical resistance (TER) measurements, as well as immunohistochemistry and western blot assays of expression of claudins 2 and 4. We found that both digoxin and marinobufagenin improve GJIC and significantly enhance the tightness of the tight junctions, as evaluated from TER measurements. Immunofluorescence assays show that both compounds promote enhanced basolateral localization of claudin-4 but not claudin 2, while densitometric analysis of western blot assays indicate a significantly increased expression of claudin 4. These changes, induced by digoxin and marinobufagenin on GJIC and TER, were not observed on MDCK-R, a modified MDCK cell line that has a genetically induced insensitive α1 subunit, indicating that Na-K-ATPase acts as a receptor mediating the actions of both ECG. Plus, the fact that the effect of both cardiac glycosides was suppressed by incubation with PP2, an inhibitor of c-Src kinase, PD98059, an inhibitor of mitogen extracellular kinase-1 and Y-27632, a selective inhibitor of ROCK, and a Rho-associated protein kinase, indicate altogether that the signaling pathways involved include c-Src and ERK1/2, as well as Rho-ROCK. These results widen and strengthen our general hypothesis that a very important physiological role of ECG is the control of the epithelial phenotype and the regulation of cell-cell contacts.
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Chang YM, Shih YL, Chen CP, Liu KL, Lee MH, Lee MZ, Hou HT, Huang HC, Lu HF, Peng SF, Chen KW, Yeh MY, Chung JG. Ouabain induces apoptotic cell death in human prostate DU 145 cancer cells through DNA damage and TRAIL pathways. ENVIRONMENTAL TOXICOLOGY 2019; 34:1329-1339. [PMID: 31436044 DOI: 10.1002/tox.22834] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 08/01/2019] [Accepted: 08/02/2019] [Indexed: 06/10/2023]
Abstract
Ouabain, a cardiotonic steroid and specific Na+ /K+ -ATPase inhibitor, has a potential to induce cancer cell apoptosis but the mechanisms of apoptosis induced by ouabain are not fully understand. The aim of this study was to investigate the cytotoxic effects of ouabain on human prostate cancer DU 145 cells in vitro. Cell morphological changes were examined by phase contrast microscopy. Cell viability, cell cycle distribution, cell apoptosis, DNA damage, the production of ROS and Ca2+ , and mitochondrial membrane potential (ΔΨm ) were measured by flow cytometry assay. Results indicated that ouabain induced cell morphological changes, decreased total cell viability, induced G0/G1 phase arrest, DNA damage, and cell apoptosis, increased ROS and Ca2+ production, but decreased the levels of ΔΨm in DU 145 cells. Ouabain also increased the activities of caspase-3, -8, and -9. Western blotting was used for measuring the alterations of apoptosis-associated protein expressions in DU 145 cells and results indicated that ouabain increased the expression of DNA damage associated proteins (pATMSer1981 , p-H2A.XSer139 , and p-p53Ser15 ) and ER-stress-associated proteins (Grp78, ATF6β, p-PERKThr981 , PERK, eIF2A, GADD153, CaMKIIβ, and caspase-4) in time-dependently. Furthermore, ouabain increased apoptosis-associated proteins (DR4, DR5, Fas, Fas Ligand, and FADD), TRAIL pathway, which related to extrinsic pathway, promoted the pro-apoptotic protein Bax, increased apoptotic-associated proteins, such as cytochrome c, AIF, Endo G, caspase-3, -8, and -9, but reduced anti-apoptotic protein Bcl-2 and Bcl-x in DU 145 cells. In conclusion, we may suggest that ouabain decreased cell viability and induced apoptotic cell death may via caspase-dependent and mitochondria-dependent pathways in human prostate cancer DU 145 cells.
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Affiliation(s)
- Yi-Ming Chang
- Department of Pathology, Tri-service General Hospital and Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Yung-Luen Shih
- Department of Pathology and Laboratory Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
- School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei, Taiwan
- School of Medicine, College of Medicine, Fu-Jen Catholic University, New Taipei, Taiwan
| | - Chao-Ping Chen
- Department of Pathology and Laboratory Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Ko-Lin Liu
- Department of Pathology and Laboratory Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Mei-Hui Lee
- Department of Genetic Counseling Center, Changhua Christian Hospital, Changhua, Taiwan
| | - Ming-Zhe Lee
- Department of Clinical Pathology, Cheng-Hsin General Hospital, Taipei, Taiwan
| | - Hsin-Tu Hou
- Department of Clinical Pathology, Cheng-Hsin General Hospital, Taipei, Taiwan
| | - Hsieh-Chou Huang
- Department of Anesthesiology and Pain Medicine, Cheng-Hsin General Hospital, Taipei, Taiwan
- Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan
| | - Hsu-Feng Lu
- Department of Clinical Pathology, Cheng-Hsin General Hospital, Taipei, Taiwan
- Department of Restaurant, Hotel and Institutional Management, Fu-Jen Catholic University, New Taipei, Taiwan
| | - Shu-Fen Peng
- Department of Biological Science and Technology, China Medical University, Taichung, Taiwan
| | - Kuo-Wei Chen
- Division of Hematology and Oncology, Cheng-Hsin General Hospital, Taipei, Taiwan
| | - Ming-Yang Yeh
- Department of Education and Research, Cheng-Hsin General Hospital, Taipei, Taiwan
| | - Jing-Gung Chung
- Department of Biological Science and Technology, China Medical University, Taichung, Taiwan
- Department of Biotechnology, Asia University, Taichung, Taiwan
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Vilchis-Nestor CA, Roldán ML, Leonardi A, Navea JG, Padilla-Benavides T, Shoshani L. Ouabain Enhances Cell-Cell Adhesion Mediated by β 1 Subunits of the Na +,K +-ATPase in CHO Fibroblasts. Int J Mol Sci 2019; 20:E2111. [PMID: 31035668 PMCID: PMC6539428 DOI: 10.3390/ijms20092111] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 04/26/2019] [Accepted: 04/26/2019] [Indexed: 12/19/2022] Open
Abstract
Adhesion is a crucial characteristic of epithelial cells to form barriers to pathogens and toxic substances from the environment. Epithelial cells attach to each other using intercellular junctions on the lateral membrane, including tight and adherent junctions, as well as the Na+,K+-ATPase. Our group has shown that non-adherent chinese hamster ovary (CHO) cells transfected with the canine β1 subunit become adhesive, and those homotypic interactions amongst β1 subunits of the Na+,K+-ATPase occur between neighboring epithelial cells. Ouabain, a cardiotonic steroid, binds to the α subunit of the Na+,K+-ATPase, inhibits the pump activity and induces the detachment of epithelial cells when used at concentrations above 300 nM. At nanomolar non-inhibiting concentrations, ouabain affects the adhesive properties of epithelial cells by inducing the expression of cell adhesion molecules through the activation of signaling pathways associated with the α subunit. In this study, we investigated whether the adhesion between β1 subunits was also affected by ouabain. We used CHO fibroblasts stably expressing the β1 subunit of the Na+,K+-ATPase (CHO β1), and studied the effect of ouabain on cell adhesion. Aggregation assays showed that ouabain increased the adhesion between CHO β1 cells. Immunofluorescence and biotinylation assays showed that ouabain (50 nM) increases the expression of the β1 subunit of the Na+,K+-ATPase at the cell membrane. We also examined the effect of ouabain on the activation of signaling pathways in CHO β1 cells, and their subsequent effect on cell adhesion. We found that cSrc is activated by ouabain and, therefore, that it likely regulates the adhesive properties of CHO β1 cells. Collectively, our findings suggest that the β1 subunit adhesion is modulated by the expression levels of the Na+,K+-ATPase at the plasma membrane, which is regulated by ouabain.
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Affiliation(s)
- Claudia Andrea Vilchis-Nestor
- Department of Physiology Biophysics and Neurosciences, Center for Research and Advanced Studies, Cinvestav-Ipn, CDMX 07360, Mexico.
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - María Luisa Roldán
- Department of Physiology Biophysics and Neurosciences, Center for Research and Advanced Studies, Cinvestav-Ipn, CDMX 07360, Mexico.
| | - Angelina Leonardi
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY 12866, USA.
| | - Juan G Navea
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY 12866, USA.
| | - Teresita Padilla-Benavides
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Liora Shoshani
- Department of Physiology Biophysics and Neurosciences, Center for Research and Advanced Studies, Cinvestav-Ipn, CDMX 07360, Mexico.
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Orellana AM, Leite JA, Kinoshita PF, Vasconcelos AR, Andreotti DZ, de Sá Lima L, Xavier GF, Kawamoto EM, Scavone C. Ouabain increases neuronal branching in hippocampus and improves spatial memory. Neuropharmacology 2018; 140:260-274. [PMID: 30099050 DOI: 10.1016/j.neuropharm.2018.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 07/05/2018] [Accepted: 08/06/2018] [Indexed: 12/20/2022]
Abstract
Previous research shows Ouabain (OUA) to bind Na, K-ATPase, thereby triggering a number of signaling pathways, including the transcription factors NFᴋB and CREB. These transcription factors play a key role in the regulation of BDNF and WNT-β-catenin signaling cascades, which are involved in neuroprotection and memory regulation. This study investigated the effects of OUA (10 nM) in the modulation of the principal signaling pathways involved in morphological plasticity and memory formation in the hippocampus of adult rats. The results show intrahippocampal injection of OUA 10 nM to activate the Wnt/β-Catenin signaling pathway and to increase CREB/BDNF and NFᴋB levels. These effects contribute to important changes in the cellular microenvironment, resulting in enhanced levels of dendritic branching in hippocampal neurons, in association with an improvement in spatial reference memory and the inhibition of long-term memory extinction.
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Affiliation(s)
- Ana Maria Orellana
- Department of Pharmacology, Institute of Biomedical Science I University of São Paulo, Room 338, Av. Prof. Lineu Prestes, 1524, ICB I, Cidade Universitária, 05508-900, São Paulo, SP. Brazil.
| | - Jacqueline Alves Leite
- Department of Pharmacology, Institute of Biomedical Science I University of São Paulo, Room 338, Av. Prof. Lineu Prestes, 1524, ICB I, Cidade Universitária, 05508-900, São Paulo, SP. Brazil.
| | - Paula Fernanda Kinoshita
- Department of Pharmacology, Institute of Biomedical Science I University of São Paulo, Room 338, Av. Prof. Lineu Prestes, 1524, ICB I, Cidade Universitária, 05508-900, São Paulo, SP. Brazil.
| | - Andrea Rodrigues Vasconcelos
- Department of Pharmacology, Institute of Biomedical Science I University of São Paulo, Room 338, Av. Prof. Lineu Prestes, 1524, ICB I, Cidade Universitária, 05508-900, São Paulo, SP. Brazil.
| | - Diana Zukas Andreotti
- Department of Pharmacology, Institute of Biomedical Science I University of São Paulo, Room 338, Av. Prof. Lineu Prestes, 1524, ICB I, Cidade Universitária, 05508-900, São Paulo, SP. Brazil.
| | - Larissa de Sá Lima
- Department of Pharmacology, Institute of Biomedical Science I University of São Paulo, Room 338, Av. Prof. Lineu Prestes, 1524, ICB I, Cidade Universitária, 05508-900, São Paulo, SP. Brazil.
| | - Gilberto Fernando Xavier
- Department of Physiology, Institute of Bioscience, University of São Paulo, Adress: Rua do Matão, Travessa 14, 101, São Paulo, 05508-090, Brazil.
| | - Elisa Mitiko Kawamoto
- Department of Pharmacology, Institute of Biomedical Science I University of São Paulo, Room 338, Av. Prof. Lineu Prestes, 1524, ICB I, Cidade Universitária, 05508-900, São Paulo, SP. Brazil.
| | - Cristoforo Scavone
- Department of Pharmacology, Institute of Biomedical Science I University of São Paulo, Room 338, Av. Prof. Lineu Prestes, 1524, ICB I, Cidade Universitária, 05508-900, São Paulo, SP. Brazil.
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Cheng Y, Chen G, Wang L, Kong J, Pan J, Xi Y, Shen F, Huang Z. Triptolide-induced mitochondrial damage dysregulates fatty acid metabolism in mouse sertoli cells. Toxicol Lett 2018; 292:136-150. [PMID: 29723566 DOI: 10.1016/j.toxlet.2018.04.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 04/09/2018] [Accepted: 04/30/2018] [Indexed: 10/17/2022]
Abstract
Triptolide is a major active ingredient of tripterygium glycosides, used for the therapy of immune and inflammatory diseases. However, its clinical applications are limited by severe male fertility toxicity associated with decreased sperm count, mobility and testicular injures. In this study, we determined that triptoide-induced mitochondrial dysfunction triggered reduction of lactate and dysregulation of fatty acid metabolism in mouse Sertoli cells. First, triptolide induced mitochondrial damage through the suppressing of proliferator-activated receptor coactivator-1 alpha (PGC-1α) activity and protein. Second, mitochondrial damage decreased lactate production and dysregulated fatty acid metabolism. Finally, mitochondrial dysfunction was initiated by the inhibition of sirtuin 1 (SIRT1) with the regulation of AMP-activated protein kinase (AMPK) in Sertoli cells after triptolide treatment. Meanwhile, triptolide induced mitochondrial fatty acid oxidation dysregulation by increasing AMPK phosphorylation. Taken together, we provide evidence that the mechanism of triptolide-induced testicular toxicity under mitochondrial injury may involve a metabolic change.
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Affiliation(s)
- Yisen Cheng
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China
| | - Gaojian Chen
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China.
| | - Li Wang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China.
| | - Jiamin Kong
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China.
| | - Ji Pan
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China.
| | - Yue Xi
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China.
| | - Feihai Shen
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China.
| | - Zhiying Huang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China.
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Hu YJ, Wang YD, Tan FQ, Yang WX. Regulation of paracellular permeability: factors and mechanisms. Mol Biol Rep 2013; 40:6123-42. [PMID: 24062072 DOI: 10.1007/s11033-013-2724-y] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Accepted: 09/14/2013] [Indexed: 12/20/2022]
Abstract
Epithelial permeability is composed of transcellular permeability and paracellular permeability. Paracellular permeability is controlled by tight junctions (TJs). Claudins and occludin are two major transmembrane proteins in TJs, which directly determine the paracellular permeability to different ions or large molecules. Intracellular signaling pathways including Rho/Rho-associated protein kinase, protein kinase Cs, and mitogen-activated protein kinase, modulate the TJ proteins to affect paracellular permeability in response for diverse stimuli. Cytokines, growth factors and hormones in organism can regulate the paracellular permeability via signaling pathway. The transcellular transporters such as Na-K-ATPase, Na(+)-coupled transporters and chloride channels, can interact with paracellular transport and regulate the TJs. In this review, we summarized the factors affecting paracellular permeability and new progressions of the related mechanism in recent studies, and pointed out further research areas.
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Affiliation(s)
- Yan-Jun Hu
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310006, People's Republic of China
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Thundathil JC, Rajamanickam GD, Kastelic JP, Newton LD. The Effects of Increased Testicular Temperature on Testis-Specific Isoform of Na+/K+-ATPase in Sperm and its Role in Spermatogenesis and Sperm Function. Reprod Domest Anim 2012; 47 Suppl 4:170-7. [DOI: 10.1111/j.1439-0531.2012.02072.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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New Insights into the Regulation of Na+,K+-ATPase by Ouabain. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 294:99-132. [DOI: 10.1016/b978-0-12-394305-7.00002-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Abstract
The exchange of substances between higher organisms and the environment occurs across transporting epithelia whose basic features are tight junctions (TJs) that seal the intercellular space, and polarity, which enables cells to transport substances vectorially. In a previous study, we demonstrated that 10 nM ouabain modulates TJs, and we now show that it controls polarity as well. We gauge polarity through the development of a cilium at the apical domain of Madin-Darby canine kidney cells (MDCK, epithelial dog kidney). Ouabain accelerates ciliogenesis in an ERK1/2-dependent manner. Claudin-2, a molecule responsible for the Na(+) and H(2)O permeability of the TJs, is also present at the cilium, as it colocalizes and coprecipitates with acetylated α-tubulin. Ouabain modulates claudin-2 localization at the cilium through ERK1/2. Comparing wild-type and ouabain-resistant MDCK cells, we show that ouabain acts through Na(+),K(+)-ATPase. Taken together, our previous and present results support the possibility that ouabain constitutes a hormone that modulates the transporting epithelial phenotype, thereby playing a crucial role in metazoan life.
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Cereijido M, Contreras RG, Shoshani L, Larre I. The Na+-K+-ATPase as self-adhesion molecule and hormone receptor. Am J Physiol Cell Physiol 2011; 302:C473-81. [PMID: 22049208 DOI: 10.1152/ajpcell.00083.2011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Thanks to the homeostasis of the internal milieu, metazoan cells can enormously simplify their housekeeping efforts and engage instead in differentiation and multiple forms of organization (tissues, organs, systems) that enable them to produce an astonishing diversity of mammals. The stability of the internal milieu despite drastic variations of the external environment (air, fresh or seawater, gastrointestinal fluids, glomerular filtrate, bile) is due to transporting epithelia that can adjust their specific permeability to H(2)O, H(+), Na(+), K(+), Ca(2+), and Cl(-) over several orders of magnitude and exchange substances with the outer milieu with exquisite precision. This exchange is due to the polarized expression of membrane proteins, among them Na(+)-K(+)-ATPase, an oligomeric enzyme that uses chemical energy from ATP molecules to translocate ions across the plasma membrane of epithelial cells. Na(+)-K(+)-ATPase presents two types of asymmetries: the arrangement of its subunits, and its expression in one pole of the epithelial cell ("polarity"). In most epithelia, polarity consists of the expression of Na(+)-K(+)-ATPase towards the intercellular space and arises in part from the interaction of the extracellular segment of the β-subunit with another β-subunit present in a Na(+)-K(+)-ATPase molecule expressed by a neighboring cell. In addition to enabling the Na(+)-K(+)-ATPase to transport ions and water vectorially, this position exposes its receptors to ouabain and analogous cardiotonic steroids, which are present in the internal milieu because these were secreted by endocrine cells.
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Affiliation(s)
- M Cereijido
- CINVESTAV, Col. San Pedro Zacatenco, Del. Gustavo A. Madero, México, D.F., México.
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Dvela M, Rosen H, Ben-Ami HC, Lichtstein D. Endogenous ouabain regulates cell viability. Am J Physiol Cell Physiol 2011; 302:C442-52. [PMID: 22031604 DOI: 10.1152/ajpcell.00336.2011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The endogenous cardiac steroid-like compounds, endogenous ouabain (EO) in particular, are present in the human circulation and are considered putative ligands of the inhibitory binding site of the plasma membrane Na(+)-K(+)-ATPase. A vast amount of data shows that, when added to cell cultures, these steroids promote the growth of cardiac, vascular, and epithelial cells. However, the involvement of the endogenous compounds in the regulation of cell viability and proliferation has never been addressed experimentally. In this study, we show that EO is present in mammalian sera and cerebral spinal fluid, as well as in commercial bovine and horse sera. The lowering of serum EO concentration by the addition of specific anti-ouabain antibodies caused a decrease in the viability of several cultured cell lines. Among these, neuronal NT2 cells were mostly affected, whereas no reduction in viability was seen in rat neuroendocrine PC12 and monkey kidney COS-7 cells. The anti-ouabain antibody-induced reduction in NT2 cell viability was significantly attenuated by the addition of ouabain and was not observed in cells growing in serum-free media. Furthermore, the addition to the medium of low concentrations (nM) of the cardenolide ouabain, but not of the bufadienolide bufalin, increased NT2 and PC12 cell viability and proliferation. In addition, at these concentrations both ouabain and bufalin caused the activation of ERK1/2 in the NT2 cells. The specific ERK1/2 inhibitor U0126 inhibited both the ouabain-induced activation of the enzyme and the increase in cell viability. Furthermore, anti-ouabain antibodies attenuated serum-stimulated ERK1/2 activity in NT2 but not in PC12 cells. Cumulatively, our results suggest that EO plays a significant role in the regulation of cell viability. In addition, our findings support the notion that activation of the ERK1/2 signaling pathway is obligatory but not sufficient for the induction of cell viability by EO.
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Affiliation(s)
- Moran Dvela
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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