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Medina-Ortiz K, López-Alvarez D, Navia F, Hansen T, Fierro L, Castaño S. Identification of Na +/K +-ATPase α/β isoforms in Rhinella marina tissues by RNAseq and a molecular docking approach at the protein level to evaluate α isoform affinities for bufadienolides. Comp Biochem Physiol A Mol Integr Physiol 2021; 254:110906. [PMID: 33476762 DOI: 10.1016/j.cbpa.2021.110906] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/12/2021] [Accepted: 01/12/2021] [Indexed: 12/24/2022]
Abstract
Na+/K+-ATPase (NKA) function is inhibited by Bufadienolides (BD), a group of cardiotonic steroids (CTS) primarily produced by anurans of the Bufonidae family, such as Rhinella marina. This study characterized the presence of α and β NKA subunit isoforms in R. marina via RNAseq in four tissues: oocytes, skin, heart, and skeletal muscle. Transcripts encoding three α-like isoforms (α1, α2, α3) and three β-like isoforms (β1, β2, β4) were identified. The amino acid sequence of α1-like isoform shared 99.4% identity with the α1 isoform previously published for R. marina. Sequences for α2, α3, and β4 from R. marina were previously unavailable. The first extracellular loop in the α2-like isoform in R. marina showed similar substitutions to those found in their susceptible homologues in other taxa (L/Q111T and S119T); in contrast, this same loop in α3-like isoform showed similar substitutions (Q111L and G120R) to those reported for toad-eating animals such as snakes, which suggests relatively lower affinity for CTS. Docking results showed that all three α-like isoforms identified in R. marina transcriptomes have low affinity to CTS compared to the susceptible α1 isoform of Sus scrofa (pig), with α1-like isoform being the most resistant. The tissue-specific RNAseq results showed the following expression of NKA α-like and β-like subunit isoforms: Oocytes expressed α1 and β1; skin α1, β1, and low levels of β2; heart α1, α3, and β1; skeletal muscle α1, β4, with low levels of α2, α3, and β1. R. marina could be used as an important model for future structural, functional and pharmacological studies of NKA and its isoforms.
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Affiliation(s)
- Katherine Medina-Ortiz
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia.
| | - Diana López-Alvarez
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia
| | - Felipe Navia
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia
| | - Thomas Hansen
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia
| | - Leonardo Fierro
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia
| | - Santiago Castaño
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia.
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Pavlovic D. Endogenous cardiotonic steroids and cardiovascular disease, where to next? Cell Calcium 2019; 86:102156. [PMID: 31896530 PMCID: PMC7031694 DOI: 10.1016/j.ceca.2019.102156] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 12/24/2019] [Accepted: 12/24/2019] [Indexed: 11/18/2022]
Abstract
Ever since British Physician William Withering first described the use of foxglove extract for treatment of patients with congestive heart failure in 1785, cardiotonic steroids have been used clinically to treat heart failure and more recently atrial fibrillation. Due to their ability to bind and inhibit the ubiquitous transport enzyme sodium potassium pump, thus regulating intracellular Na+ concentration in every living cell, they are also an essential tool for research into the sodium potassium pump structure and function. Exogenous CTS have been clearly demonstrated to affect cardiovascular system through modulation of vagal tone, cardiac contraction (via ionic changes) and altered natriuresis. Reports of a number of endogenous CTS, since the 1980s, have intensified research into their physiologic and pathophysiologic roles and opened up novel therapeutic targets. Substantive evidence pointing to the role of endogenous ouabain and marinobufagenin, the two most prominent CTS, in development of cardiovascular disease has accumulated. Nevertheless, their presence, structure, biosynthesis pathways and even mechanism of action remain unclear or controversial. In this review the current state-of-the-art, the controversies and the remaining questions surrounding the role of endogenous cardiotonic steroids in health and disease are discussed.
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Affiliation(s)
- Davor Pavlovic
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
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Hu MY, Guh YJ, Shao YT, Kuan PL, Chen GL, Lee JR, Jeng MS, Tseng YC. Strong Ion Regulatory Abilities Enable the Crab Xenograpsus testudinatus to Inhabit Highly Acidified Marine Vent Systems. Front Physiol 2016; 7:14. [PMID: 26869933 PMCID: PMC4734175 DOI: 10.3389/fphys.2016.00014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 01/11/2016] [Indexed: 12/21/2022] Open
Abstract
Hydrothermal vent organisms have evolved physiological adaptations to cope with extreme abiotic conditions including temperature and pH. To date, acid-base regulatory abilities of vent organisms are poorly investigated, although this physiological feature is essential for survival in low pH environments. We report the acid-base regulatory mechanisms of a hydrothermal vent crab, Xenograpsus testudinatus, endemic to highly acidic shallow-water vent habitats with average environment pH-values ranging between 5.4 and 6.6. Within a few hours, X. testudinatus restores extracellular pH (pHe) in response to environmental acidification of pH 6.5 (1.78 kPa pCO2) accompanied by an increase in blood HCO3- levels from 8.8 ± 0.3 to 31 ± 6 mM. Branchial Na+/K+-ATPase (NKA) and V-type H+-ATPase (VHA), the major ion pumps involved in branchial acid-base regulation, showed dynamic increases in response to acidified conditions on the mRNA, protein and activity level. Immunohistochemical analyses demonstrate the presence of NKA in basolateral membranes, whereas the VHA is predominantly localized in cytoplasmic vesicles of branchial epithelial- and pillar-cells. X. testudinatus is closely related to other strong osmo-regulating brachyurans, which is also reflected in the phylogeny of the NKA. Accordingly, our results suggest that the evolution of strong ion regulatory abilities in brachyuran crabs that allowed the occupation of ecological niches in euryhaline, freshwater, and terrestrial habitats are probably also linked to substantial acid-base regulatory abilities. This physiological trait allowed X. testudinatus to successfully inhabit one of the world's most acidic marine environments.
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Affiliation(s)
- Marian Y Hu
- Institute of Cellular and Organismic Biology, Academia SinicaTaipei, Taiwan; Institute of Physiology, Christian-Albrechts University KielKiel, Germany
| | - Ying-Jey Guh
- Institute of Biological Chemistry, Academia Sinica Taipei, Taiwan
| | - Yi-Ta Shao
- Institute of Marine Biology, National Taiwan Ocean University Keelung, Taiwan
| | - Pou-Long Kuan
- Department of Life Science, National Taiwan Normal University Taipei, Taiwan
| | - Guan-Lin Chen
- Department of Life Science, National Taiwan Normal University Taipei, Taiwan
| | - Jay-Ron Lee
- Institute of Cellular and Organismic Biology, Academia Sinica Taipei, Taiwan
| | - Ming-Shiou Jeng
- Biodiversity Research Center, Academia Sinica Taipei, Taiwan
| | - Yung-Che Tseng
- Department of Life Science, National Taiwan Normal University Taipei, Taiwan
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Hu MY, Guh YJ, Stumpp M, Lee JR, Chen RD, Sung PH, Chen YC, Hwang PP, Tseng YC. Branchial NH4+-dependent acid–base transport mechanisms and energy metabolism of squid (Sepioteuthis lessoniana) affected by seawater acidification. Front Zool 2014. [DOI: 10.1186/s12983-014-0055-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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Lin NH, Chung TY, Li FY, Chen HA, Tzen JTC. Enhancing the potency of lithospermate B for inhibiting Na+/K+-ATPase activity by forming transition metal ion complexes. Acta Pharmacol Sin 2013; 34:893-900. [PMID: 23685954 DOI: 10.1038/aps.2013.32] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 03/11/2013] [Indexed: 02/03/2023] Open
Abstract
AIM To determine whether replacing Mg(2+) in magnesium lithospermate B (Mg-LSB) isolated from danshen (Salvia miltiorrhiza) with other metal ions could affect its potency in inhibition of Na(+)/K(+)-ATPase activity. METHODS Eight metal ions (Na(+), K(+), Mg(2+), Cr(3+), Mn(2+), Co(2+), Ni(2+), and Zn(2+)) were used to form complexes with LSB. The activity of Na(+)/K(+)-ATPase was determined by measuring the amount of inorganic phosphate (Pi) liberated from ATP. Human adrenergic neuroblastoma cell line SH-SY5Y was used to assess the intracellular Ca(2+) level fluctuation and cell viability. The metal binding site on LSB and the binding mode of the metal-LSB complexes were detected by NMR and visible spectroscopy, respectively. RESULTS The potencies of LSB complexed with Cr(3+), Mn(2+), Co(2+), or Ni(2+) increased by approximately 5 times compared to the naturally occurring LSB and Mg-LSB. The IC50 values of Cr-LSB, Mn-LSB, Co-LSB, Ni-LSB, LSB, and Mg-LSB in inhibition of Na(+)/K(+)-ATPase activity were 23, 17, 26, 25, 101, and 128 μmol/L, respectively. After treatment of SH-SY5Y cells with the transition metal-LSB complexes (25 μmol/L), the intracellular Ca(2+) level was substantially elevated, and the cells were viable for one day. The transition metals, as exemplified by Co(2+), appeared to be coordinated by two carboxylate groups and one carbonyl group of LSB. Titration of LSB against Co(2+) demonstrated that the Co-LSB complex was formed with a Co(2+):LSB molar ratio of 1:2 or 1:1, when [Co(2+)] was less than half of the [LSB] or higher than the [LSB], respectively. CONCLUSION LSB complexed with Cr(3+), Mn(2+), Co(2+), or Ni(2+) are stable, non-toxic and more potent in inhibition of Na(+)/K(+)-ATPase. The transition metal-LSB complexes have the potential to be superior substitutes for cardiac glycosides in the treatment of congestive heart failure.
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Active ingredients in Chinese medicines promoting blood circulation as Na+/K+ -ATPase inhibitors. Acta Pharmacol Sin 2011; 32:141-51. [PMID: 21293466 DOI: 10.1038/aps.2010.197] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The positive inotropic effect of cardiac glycosides lies in their reversible inhibition on the membrane-bound Na(+)/K(+)-ATPase in human myocardium. Steroid-like compounds containing a core structure similar to cardiac glycosides are found in many Chinese medicines conventionally used for promoting blood circulation. Some of them are demonstrated to be Na(+)/K(+)-ATPase inhibitors and thus putatively responsible for their therapeutic effects via the same molecular mechanism as cardiac glycosides. On the other hand, magnesium lithospermate B of danshen is also proposed to exert its cardiac therapeutic effect by effectively inhibiting Na(+)/K(+)-ATPase. Theoretical modeling suggests that the number of hydrogen bonds and the strength of hydrophobic interaction between the effective ingredients of various medicines and residues around the binding pocket of Na(+)/K(+)-ATPase are crucial for the inhibitory potency of these active ingredients. Ginsenosides, the active ingredients in ginseng and sanqi, substantially inhibit Na(+)/K(+)-ATPase when sugar moieties are attached only to the C-3 position of their steroid-like structure, equivalent to the sugar position in cardiac glycosides. Their inhibitory potency is abolished, however, when sugar moieties are linked to C-6 or C-20 position of the steroid nucleus; presumably, these sugar attachments lead to steric hindrance for the entrance of ginsenosides into the binding pocket of Na(+)/K(+)-ATPase. Neuroprotective effects of cardiac glycosides, several steroid-like compounds, and magnesium lithospermate B against ischemic stroke have been accordingly observed in a cortical brain slice-based assay model, and cumulative data support that effective inhibitors of Na(+)/K(+)-ATPase in the brain could be potential drugs for the treatment of ischemic stroke.
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Lingrel JB. The physiological significance of the cardiotonic steroid/ouabain-binding site of the Na,K-ATPase. Annu Rev Physiol 2010; 72:395-412. [PMID: 20148682 DOI: 10.1146/annurev-physiol-021909-135725] [Citation(s) in RCA: 226] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Na,K-ATPase is the membrane "pump" that generates the Na(+) and K(+) gradients across the plasma membrane that drives many physiological processes. This enzyme is highly sensitive to inhibition by cardiotonic steroids, most notably the digitalis/ouabain class of compounds, which have been used for centuries to treat congestive heart failure and arrhythmias. The amino acids that constitute the ouabain-binding site are highly conserved across the evolutionary spectrum. This could be fortuitous or could result from this site being conserved because it has an important biological function. New physiological approaches using genetically engineered mice are being used to define the biological significance of the "receptor function" of the Na,K-ATPase and its regulation by potential endogenous cardiotonic steroid-like compounds. These studies extend the reach of earlier studies involving the biochemical purification of endogenous regulatory ligands.
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Affiliation(s)
- Jerry B Lingrel
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0524, USA.
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Cane toad toxicity: an assessment of extracts from early developmental stages and adult tissues using MDCK cell culture. Toxicon 2009; 53:385-91. [PMID: 18948131 DOI: 10.1016/j.toxicon.2008.10.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 09/19/2008] [Accepted: 10/07/2008] [Indexed: 11/21/2022]
Abstract
Extracts of the cane toad (Bufo [Chaunus] marinus) adversely affected the growth of Mardin-Darby canine kidney (MDCK) cells during culture. In a similar manner to ouabain treatment, application of toad extracts over a 24 h period resulted in high levels of cytotoxicity, as indicated by cell detachment, increased membrane permeability and loss of mitochondrial function. Cell viability and growth were unchanged for controls (PBS) and increased with the application of Limnodynastes peronii tadpole and adult frog extracts. We investigated the general cytotoxicity of cane toad developmental stages (e.g., eggs, embryonic hatchlings, tadpoles and post-metamorphic toadlets) as well as selected adult tissues (e.g. skin, gut, liver). Our results showed that pre-metamorphic cane toad aqueous extracts used at 1 mg/ml on MDCK cells generated cytotoxicity levels comparable to ouabain treatment (3 microM). After normalisation, extracts from 2-3-month-old toadlets appeared less toxic than pre- and early metamorphic stages. Adult tissues revealed a gradient of cytotoxicity levels ranging from non-toxic brain to highly toxic dorsal skin extracts.
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Feldmann T, Glukmann V, Medvenev E, Shpolansky U, Galili D, Lichtstein D, Rosen H. Role of endosomal Na+-K+-ATPase and cardiac steroids in the regulation of endocytosis. Am J Physiol Cell Physiol 2007; 293:C885-96. [PMID: 17553933 DOI: 10.1152/ajpcell.00602.2006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Plasma membrane Na(+)-K(+)-ATPase, which drives potassium into and sodium out of the cell, has important roles in numerous physiological processes. Cardiac steroids (CS), such as ouabain and bufalin, specifically interact with the pump and affect ionic homeostasis, signal transduction, and endocytosed membrane traffic. CS-like compounds are present in mammalian tissues, synthesized in the adrenal gland, and considered to be new family of steroid hormones. In this study, the mechanism of Na(+)-K(+)-ATPase involvement in the regulation of endocytosis is explored. We show that the effects of various CS on changes in endosomal pH are mediated by the pump and correspond to their effects on endosomal membrane traffic. In addition, it was found that CS-induced changes in endocytosed membrane traffic were dependent on alterations in [Na(+)] and [H(+)] in the endosome. Furthermore, we show that various CS differentially regulate endosomal pH and membrane traffic. The results suggest that these differences are due to specific binding characteristics. Based on our observations, we propose that Na(+)-K(+)-ATPase is a key player in the regulation of endosomal pH and endocytosed membrane traffic. Furthermore, our results raise the possibility that CS-like hormones regulate differentially intracellular membrane traffic.
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Affiliation(s)
- Tomer Feldmann
- The Kuvin Center for the Study of Infectious and Tropical Diseases, Institute of Microbiology, The Hebrew Univ.-Hadassah Medical School, Jerusalem 91120, Israel.
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Nesher M, Shpolansky U, Rosen H, Lichtstein D. The digitalis-like steroid hormones: new mechanisms of action and biological significance. Life Sci 2007; 80:2093-2107. [PMID: 17499813 DOI: 10.1016/j.lfs.2007.03.013] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 03/08/2007] [Accepted: 03/14/2007] [Indexed: 12/25/2022]
Abstract
Digitalis-like compounds (DLC) are a family of steroid hormones synthesized in and released from the adrenal gland. DLC, the structure of which resembles that of plant cardiac glycosides, bind to and inhibit the activity of the ubiquitous cell surface enzyme Na(+), K(+)-ATPase. However, there is a large body of evidence suggesting that the regulation of ion transport by Na(+), K(+)-ATPase is not the only physiological role of DLC. The binding of DLC to Na(+), K(+)-ATPase induces the activation of various signal transduction cascades that activate changes in intracellular Ca(++) homeostasis, and in specific gene expression. These, in turn, stimulate endocytosis and affect cell growth and proliferation. At the systemic level, DLC were shown to be involved in the regulation of major physiological parameters including water and salt homeostasis, cardiac contractility and rhythm, systemic blood pressure and behavior. Furthermore, the DLC system has been implicated in several pathological conditions, including cardiac arrhythmias, hypertension, cancer and depressive disorders. This review evaluates the evidence for the different aspects of DLC action and delineates open questions in the field.
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Affiliation(s)
- Maoz Nesher
- Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Uri Shpolansky
- Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Haim Rosen
- The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - David Lichtstein
- Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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Matsukawa M, Mukai T, Akizawa T, Miyatake S, Yoshioka M, Morris JF, Butler VP. Isolation and characterization of novel endogenous digitalis-like factors in the ovary of the giant toad, Bufo marinus. JOURNAL OF NATURAL PRODUCTS 1998; 61:1476-1481. [PMID: 9868147 DOI: 10.1021/np980189g] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We have previously described the structures of four novel unconjugated bufadienolides in the ovary of the toad, Bufo marinus. In this study, we report the separation and characterization of three novel bufadienolide conjugates. These compounds were purified by HPLC, and their structures were determined to be 11alpha, 19-dihydroxytelocinobufagin-3-(12-hydroxydodecanoic acid) ester, 11alpha,19-dihydroxytelocinobufagin-3-(14-hydroxy-7-tetra decenoic acid) ester, and 11alpha, 19-dihydroxytelocinobufagin-3-(14-hydroxytetradecanoic acid) ester on the basis of NMR and MS data. Numerous dicarboxylic acid esters of bufadienolides have previously been described, but the three bufadienolide conjugates described in this report differ from previously described esters in that they contain hydroxylated monocarboxylic acids. The function of these three conjugates is not known but they are, like bufotoxins, potent inhibitors of Na+, K+-ATPase and may play a developmental role in the differentiation of toad oocytes.
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Affiliation(s)
- M Matsukawa
- Department of Analytical Chemistry, Pharmaceutical Sciences, Setsunan University, 45-1, Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan.
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