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Blaustein MP, Hamlyn JM. Sensational site: the sodium pump ouabain-binding site and its ligands. Am J Physiol Cell Physiol 2024; 326:C1120-C1177. [PMID: 38223926 PMCID: PMC11193536 DOI: 10.1152/ajpcell.00273.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 12/22/2023] [Accepted: 01/10/2024] [Indexed: 01/16/2024]
Abstract
Cardiotonic steroids (CTS), used by certain insects, toads, and rats for protection from predators, became, thanks to Withering's trailblazing 1785 monograph, the mainstay of heart failure (HF) therapy. In the 1950s and 1960s, we learned that the CTS receptor was part of the sodium pump (NKA) and that the Na+/Ca2+ exchanger was critical for the acute cardiotonic effect of digoxin- and ouabain-related CTS. This "settled" view was upended by seven revolutionary observations. First, subnanomolar ouabain sometimes stimulates NKA while higher concentrations are invariably inhibitory. Second, endogenous ouabain (EO) was discovered in the human circulation. Third, in the DIG clinical trial, digoxin only marginally improved outcomes in patients with HF. Fourth, cloning of NKA in 1985 revealed multiple NKA α and β subunit isoforms that, in the rodent, differ in their sensitivities to CTS. Fifth, the NKA is a cation pump and a hormone receptor/signal transducer. EO binding to NKA activates, in a ligand- and cell-specific manner, several protein kinase and Ca2+-dependent signaling cascades that have widespread physiological effects and can contribute to hypertension and HF pathogenesis. Sixth, all CTS are not equivalent, e.g., ouabain induces hypertension in rodents while digoxin is antihypertensinogenic ("biased signaling"). Seventh, most common rodent hypertension models require a highly ouabain-sensitive α2 NKA and the elevated blood pressure is alleviated by EO immunoneutralization. These numerous phenomena are enabled by NKA's intricate structure. We have just begun to understand the endocrine role of the endogenous ligands and the broad impact of the ouabain-binding site on physiology and pathophysiology.
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Affiliation(s)
- Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - John M Hamlyn
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States
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Tang Z, Chen S, Ni Y, Zhao R, Zhu X, Yang X, Zhang X. Role of Na +, K +-ATPase ion pump in osteoinduction. Acta Biomater 2021; 129:293-308. [PMID: 34087440 DOI: 10.1016/j.actbio.2021.05.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 05/24/2021] [Accepted: 05/26/2021] [Indexed: 12/14/2022]
Abstract
Porous biphasic calcium phosphate bioceramic (BCP) possesses osteoinductivity to induce the osteoblastic commitment of mesenchymal stem cells (MSCs) and ectopic bone formation. However, the underlying mechanism remains enigmatic. We performed a gene array analysis of MSCs cocultured with BCP to screen for candidate osteoinductive modulators. Na+, K+-ATPase (NKA), an ion transporter, therefore was identified as a crucial ion transporter in regulating the osteogenesis of the cells. NKA activator, a polyclonal antibody, enriched the cytomembrane abundance of NKA and lead to an enhanced osteogenic effect of BCP. As indicated in gene array analysis and suggested by co-immunoprecipitation assay, protein phosphatase 2A (PP2A) was elevated by BCP to dephosphorylate NKA and prevent its endocytosis. The inhibition of NKA by ouabain resulted in an adverse effect on osteoinductivity of BCP. We further altered NKA activity in mice implanted with BCP and found that the intensity and incidence of osteoinduction was increased by the NKA activator. We went one step further by investigating the potential of targeting NKA in osteoporotic bone regeneration. Activating NKA upregulated osteogenic gene expression and calcium deposition ability of osteoporotic osteoblasts. Furthermore, activation of NKA in mice ameliorated estrogen-deficiency induced bone loss, in terms of increased bone mass and improved bending strength. With this osteoinductive bioceramic derived ion transporter target, we demonstrate that the activation of NKA has significant potential to revolutionize the regeneration of bone. STATEMENT OF SIGNIFICANCE: In this study, we identified an important role of Na+, K+-ATPase (NKA) have played in osteoinductivity of biphasic calcium phosphate bioceramic (BCP). Furthermore, we demonstrated the therapeutic potential of targeting NKA in osteoporotic bone regeneration. Numerous gene and protein targets to treat osteoporosis were discovered every year, mainly obtained by genomic and proteomic screenings of a large population. In contrast, our study identified an unrevealed bone regenerating target from the upregulated genes induced by an osteoinductive biomaterial. The approach was cost-saving since it did not require a large sample pool. Furthermore, the target derived from this approach was proven to be anabolic. Identification of an anabolic agent holds significant value since most of the current anti-osteoporotic therapies are antiresorptive.
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Tang G, Shen Y, Gao P, Song SS, Si LY. Klotho attenuates isoproterenol-induced hypertrophic response in H9C2 cells by activating Na+/K+-ATPase and inhibiting the reverse mode of Na+/Ca2+-exchanger. In Vitro Cell Dev Biol Anim 2018; 54:250-256. [DOI: 10.1007/s11626-017-0215-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 11/09/2017] [Indexed: 12/20/2022]
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Yan X, Xun M, Dou X, Wu L, Zhang F, Zheng J. Activation of Na+-K+-ATPase with DRm217 attenuates oxidative stress-induced myocardial cell injury via closing Na+-K+-ATPase/Src/Ros amplifier. Apoptosis 2017; 22:531-543. [DOI: 10.1007/s10495-016-1342-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Yan X, Xun M, Li J, Wu L, Dou X, Zheng J. Activation of Na+/K+-ATPase attenuates high glucose-induced H9c2 cell apoptosis via suppressing ROS accumulation and MAPKs activities by DRm217. Acta Biochim Biophys Sin (Shanghai) 2016; 48:883-893. [PMID: 27563007 DOI: 10.1093/abbs/gmw079] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/23/2016] [Indexed: 01/08/2023] Open
Abstract
Hyperglycemia is one of the major factors responsible for the myocardial apoptosis and dysfunction in diabetes. Many studies have proved that there is a close relationship between decreased Na+/K+-ATPase activity and diabetic cardiomyopathy. However, the effect of directly activated Na+/K+-ATPase on high glucose-induced myocardial injury is still unknown. Here we found that DRm217, a Na+/K+-ATPase's DR-region specific monoclonal antibody and direct activator, could prevent high glucose-induced H9c2 cell injury, reactive oxygen species (ROS) release, and mitochondrial dysfunction. High glucose-treatment decreased Na+/K+-ATPase activity and increased intracellular Ca2+ level, whereas DRm217 increased Na+/K+-ATPase activity and alleviated Ca2+ overload. Inhibition of Ca2+ overload or closing sodium calcium exchanger (NCX channel) could reverse high glucose-induced ROS increasing and cell injury. In addition, DRm217 could significantly attenuate high glucose-induced p38, JNK and ERK1/2 phosphorylation, which were involved in high glucose-induced cell injury and ROS accumulation. Our findings suggest that DRm217 may protect against the deleterious effects of high glucose in the heart. Prevention of high glucose-induced myocardial cell injury by specific Na+/K+-ATPase activator may be an attractive therapeutic option.
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Affiliation(s)
- Xiaofei Yan
- Department of Biochemistry and Molecular Biology, Medical College of Xi'an Jiaotong University, Xi'an 710061, China
| | - Meng Xun
- Department of Immunology and Microbiology, Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Jing Li
- Department of Biochemistry and Molecular Biology, Medical College of Xi'an Jiaotong University, Xi'an 710061, China
| | - Litao Wu
- Department of Biochemistry and Molecular Biology, Medical College of Xi'an Jiaotong University, Xi'an 710061, China
| | - Xiaojuan Dou
- Department of Biochemistry and Molecular Biology, Medical College of Xi'an Jiaotong University, Xi'an 710061, China
| | - Jin Zheng
- Hospital of Nephrology, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an 710061, China
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Nasri HR, Shahouzehi B, Masoumi-Ardakani Y, Iranpour M. Effects of digoxin on cardiac iron content in rat model of iron overload. ARYA ATHEROSCLEROSIS 2016; 12:180-184. [PMID: 28149313 PMCID: PMC5266134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Plasma iron excess can lead to iron accumulation in heart, kidney and liver. Heart failure is a clinical widespread syndrome. In thalassemia, iron overload cardiomyopathy is caused by iron accumulation in the heart that leads to cardiac damage and heart failure. Digoxin increases the intracellular sodium concentration by inhibition of Na+/K+-ATPase that affects Na+/Ca2+ exchanger (NCX), which raises intracellular calcium and thus attenuates heart failure. The mechanism of iron uptake into cardiomyocytes is not exactly understood. METHODS We assessed the effect of different concentrations of digoxin on cardiac iron content in rat model of iron overload. Digoxin had been administrated intraperitoneally (IP) for one week before main study began to assure increased digoxin levels. Group 1 received four IP injections of iron-dextran (12.5mg/100g body weight) every 5 days evenly distributed over 20 days. Groups 2-4 received 0.5, 1 and 5 mg/kg/day IP digoxin, respectively. Last three groups 5-7 received iron-dextran as group 1 and digoxin concentrations 0.5, 1 and 5 mg/kg/day, respectively. RESULTS Cardiac iron contents were significantly higher in iron overload groups that received different concentrations (0.5, 1 and 5 mg/kg/day) of digoxin than their counterparts in control groups and this pattern was also observed in pathology assessment. CONCLUSION It seems that digoxin plays an important role in iron transport into heart in iron overload state but exact mechanism of this phenomenon is not clear. L-type Ca2+ channels are good candidates that probably could be involved in iron accumulation in cardiomyocytes. Thus it would be better to reconsider digoxin administration in thalassemia and iron overload conditions.
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Affiliation(s)
- Hamid Reza Nasri
- Associate Professor, Cardiovascular Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Sciences, Kerman, Iran
| | - Beydolah Shahouzehi
- Endocrinology and Metabolism Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Sciences, Kerman, Iran
| | - Yaser Masoumi-Ardakani
- Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran,Correspondence to: Yaser Masoumi-Ardakani,
| | - Maryam Iranpour
- Associate Professor, Department of Pathology, Kerman University of Medical Sciences, Kerman, Iran
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Yan X, Liang F, Li D, Zheng J. Ouabain elicits human glioblastoma cells apoptosis by generating reactive oxygen species in ERK-p66SHC-dependent pathway. Mol Cell Biochem 2014; 398:95-104. [PMID: 25217205 DOI: 10.1007/s11010-014-2208-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 08/30/2014] [Indexed: 01/26/2023]
Abstract
Excessive reactive oxygen species (ROS) generation has been implicated as one of main agents in ouabain-induced anticancer effect. Unfortunately, the signaling pathways under it are not very clarified. In the present study, we investigated the molecular mechanism involved in ouabain-induced ROS generation and cell apoptosis on human U373MG and U87MG glioma cells. Ouabain-induced glioblastoma cells apoptosis and increased ROS generation. Clearance ROS by three different ROS scavenger partly, but not totally, reversed ouabain's effect on cell apoptosis. Ouabain-induced ROS generation was not regulated by calcium overload, reduced nicotinamide adenine dinucleotide phosphate oxidation, but by p66Shc phosphorylation. Ouabain treatment increased p66Shc Ser36 phosphorylation. Knockdown of p66Shc by siRNA significantly inhibited ROS generations in response to ouabain. Ouabain-induced p66Shc phosphorylation through Src/Ras/extracellular signal-regulated kinase signal pathway. Our results uncovered a novel signaling pathway with p66Shc, ouabain-induced ROS generation, and glioblastoma cell apoptosis.
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Affiliation(s)
- Xiaofei Yan
- Department of Biochemistry and Molecular Biology, Medical School, Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, People's Republic of China,
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Almagro JC, Gilliland GL, Breden F, Scott JK, Sok D, Pauthner M, Reichert JM, Helguera G, Andrabi R, Mabry R, Bléry M, Voss JE, Laurén J, Abuqayyas L, Barghorn S, Ben-Jacob E, Crowe JE, Huston JS, Johnston SA, Krauland E, Lund-Johansen F, Marasco WA, Parren PWHI, Xu KY. Antibody engineering and therapeutics, The Annual Meeting of the Antibody Society: December 8-12, 2013, Huntington Beach, CA. MAbs 2014; 6:577-618. [PMID: 24589717 PMCID: PMC4011904 DOI: 10.4161/mabs.28421] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The 24th Antibody Engineering & Therapeutics meeting brought together a broad range of participants who were updated on the latest advances in antibody research and development. Organized by IBC Life Sciences, the gathering is the annual meeting of The Antibody Society, which serves as the scientific sponsor. Preconference workshops on 3D modeling and delineation of clonal lineages were featured, and the conference included sessions on a wide variety of topics relevant to researchers, including systems biology; antibody deep sequencing and repertoires; the effects of antibody gene variation and usage on antibody response; directed evolution; knowledge-based design; antibodies in a complex environment; polyreactive antibodies and polyspecificity; the interface between antibody therapy and cellular immunity in cancer; antibodies in cardiometabolic medicine; antibody pharmacokinetics, distribution and off-target toxicity; optimizing antibody formats for immunotherapy; polyclonals, oligoclonals and bispecifics; antibody discovery platforms; and antibody-drug conjugates.
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Affiliation(s)
| | | | | | | | - Devin Sok
- The Scripps Research Institute; La Jolla, CA USA
| | | | | | - Gustavo Helguera
- CONICET; Laboratorio Biotecnología Farmacéutica; Instituto de Biología y Medicina Experimental, IBYME; Ciudad Autónoma de Buenos Aires, Argentina
| | | | | | | | - James E Voss
- The Scripps Research Institute; La Jolla, CA USA
| | - Juha Laurén
- Regeneron Pharmaceuticals, Inc.; Tarrytown, NY USA
| | | | | | | | - James E Crowe
- Vanderbilt University Medical Center, Nashville, TN, USA
| | | | | | | | | | | | | | - Kai Y Xu
- University of Maryland; Baltimore, MD USA
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