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Li Z, Langhans SA. Transcriptional regulators of Na,K-ATPase subunits. Front Cell Dev Biol 2015; 3:66. [PMID: 26579519 PMCID: PMC4620432 DOI: 10.3389/fcell.2015.00066] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 10/05/2015] [Indexed: 12/20/2022] Open
Abstract
The Na,K-ATPase classically serves as an ion pump creating an electrochemical gradient across the plasma membrane that is essential for transepithelial transport, nutrient uptake and membrane potential. In addition, Na,K-ATPase also functions as a receptor, a signal transducer and a cell adhesion molecule. With such diverse roles, it is understandable that the Na,K-ATPase subunits, the catalytic α-subunit, the β-subunit and the FXYD proteins, are controlled extensively during development and to accommodate physiological needs. The spatial and temporal expression of Na,K-ATPase is partially regulated at the transcriptional level. Numerous transcription factors, hormones, growth factors, lipids, and extracellular stimuli modulate the transcription of the Na,K-ATPase subunits. Moreover, epigenetic mechanisms also contribute to the regulation of Na,K-ATPase expression. With the ever growing knowledge about diseases associated with the malfunction of Na,K-ATPase, this review aims at summarizing the best-characterized transcription regulators that modulate Na,K-ATPase subunit levels. As abnormal expression of Na,K-ATPase subunits has been observed in many carcinoma, we will also discuss transcription factors that are associated with epithelial-mesenchymal transition, a crucial step in the progression of many tumors to malignant disease.
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Affiliation(s)
- Zhiqin Li
- Nemours Center for Childhood Cancer Research, Nemours/Alfred I. duPont Hospital for Children Wilmington, DE, USA
| | - Sigrid A Langhans
- Nemours Center for Childhood Cancer Research, Nemours/Alfred I. duPont Hospital for Children Wilmington, DE, USA
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Huynh TP, Barwe SP, Lee SJ, McSpadden R, Franco OE, Hayward SW, Damoiseaux R, Grubbs SS, Petrelli NJ, Rajasekaran AK. Glucocorticoids suppress renal cell carcinoma progression by enhancing Na,K-ATPase beta-1 subunit expression. PLoS One 2015; 10:e0122442. [PMID: 25836370 PMCID: PMC4383530 DOI: 10.1371/journal.pone.0122442] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 02/21/2015] [Indexed: 11/28/2022] Open
Abstract
Glucocorticoids are commonly used as palliative or chemotherapeutic clinical agents for treatment of a variety of cancers. Although steroid treatment is beneficial, the mechanisms by which steroids improve outcome in cancer patients are not well understood. Na,K-ATPase beta-subunit isoform 1 (NaK-β1) is a cell-cell adhesion molecule, and its expression is down-regulated in cancer cells undergoing epithelial-to mesenchymal-transition (EMT), a key event associated with cancer progression to metastatic disease. In this study, we performed high-throughput screening to identify small molecules that could up-regulate NaK-β1 expression in cancer cells. Compounds related to the glucocorticoids were identified as drug candidates enhancing NaK-β1 expression. Of these compounds, triamcinolone, dexamethasone, and fluorometholone were validated to increase NaK-β1 expression at the cell surface, enhance cell-cell adhesion, attenuate motility and invasiveness and induce mesenchymal to epithelial like transition of renal cell carcinoma (RCC) cells in vitro. Treatment of NaK-β1 knockdown cells with these drug candidates confirmed that these compounds mediate their effects through up-regulating NaK-β1. Furthermore, we demonstrated that these compounds attenuate tumor growth in subcutaneous RCC xenografts and reduce local invasiveness in orthotopically-implanted tumors. Our results strongly indicate that the addition of glucocorticoids in the treatment of RCC may improve outcome for RCC patients by augmenting NaK-β1 cell-cell adhesion function.
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MESH Headings
- Animals
- Carcinoma, Renal Cell/drug therapy
- Carcinoma, Renal Cell/enzymology
- Carcinoma, Renal Cell/pathology
- Cell Adhesion/drug effects
- Cell Line, Tumor
- Dexamethasone/pharmacology
- Disease Progression
- Fluorometholone/pharmacology
- Glucocorticoids/pharmacology
- HeLa Cells
- High-Throughput Screening Assays
- Humans
- Kidney Neoplasms/drug therapy
- Kidney Neoplasms/enzymology
- Kidney Neoplasms/pathology
- Male
- Mice
- Mice, Hairless
- Mice, SCID
- Neoplasm Invasiveness/prevention & control
- Promoter Regions, Genetic/drug effects
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Neoplasm/genetics
- RNA, Neoplasm/metabolism
- Sodium-Potassium-Exchanging ATPase/genetics
- Sodium-Potassium-Exchanging ATPase/metabolism
- Triamcinolone/pharmacology
- Up-Regulation/drug effects
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Thu P. Huynh
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America
- Nemours Center for Childhood Cancer Research, A. I. DuPont Hospital for Children, Wilmington, Delaware, United States of America
| | - Sonali P. Barwe
- Nemours Center for Childhood Cancer Research, A. I. DuPont Hospital for Children, Wilmington, Delaware, United States of America
| | - Seung J. Lee
- Nemours Center for Childhood Cancer Research, A. I. DuPont Hospital for Children, Wilmington, Delaware, United States of America
| | - Ryan McSpadden
- Nemours Center for Childhood Cancer Research, A. I. DuPont Hospital for Children, Wilmington, Delaware, United States of America
| | - Omar E. Franco
- Department of Urologic Surgery, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Simon W. Hayward
- Department of Urologic Surgery, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Robert Damoiseaux
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Stephen S. Grubbs
- Helen F. Graham Cancer Center, Christiana Care Health System, Newark, Delaware, United States of America
| | - Nicholas J. Petrelli
- Helen F. Graham Cancer Center, Christiana Care Health System, Newark, Delaware, United States of America
| | - Ayyappan K. Rajasekaran
- Helen F. Graham Cancer Center, Christiana Care Health System, Newark, Delaware, United States of America
- Department of Biological Sciences, University of Delaware, Newark, Delaware, United States of America
- Therapy Architects, 2700 Silverside Road, Wilmington, Delaware, United States of America
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Chen XY, Wang SM, Li N, Hu Y, Zhang Y, Xu JF, Li X, Ren J, Su B, Yuan WZ, Teng XR, Zhang RX, Jiang DH, Mulet X, Li HP. Creation of lung-targeted dexamethasone immunoliposome and its therapeutic effect on bleomycin-induced lung injury in rats. PLoS One 2013; 8:e58275. [PMID: 23516459 PMCID: PMC3597622 DOI: 10.1371/journal.pone.0058275] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 02/01/2013] [Indexed: 12/28/2022] Open
Abstract
OBJECTIVE Acute lung injury (ALI), is a major cause of morbidity and mortality, which is routinely treated with the administration of systemic glucocorticoids. The current study investigated the distribution and therapeutic effect of a dexamethasone(DXM)-loaded immunoliposome (NLP) functionalized with pulmonary surfactant protein A (SP-A) antibody (SPA-DXM-NLP) in an animal model. METHODS DXM-NLP was prepared using film dispersion combined with extrusion techniques. SP-A antibody was used as the lung targeting agent. Tissue distribution of SPA-DXM-NLP was investigated in liver, spleen, kidney and lung tissue. The efficacy of SPA-DXM-NLP against lung injury was assessed in a rat model of bleomycin-induced acute lung injury. RESULTS The SPA-DXM-NLP complex was successfully synthesized and the particles were stable at 4°C. Pulmonary dexamethasone levels were 40 times higher with SPA-DXM-NLP than conventional dexamethasone injection. Administration of SPA-DXM-NLP significantly attenuated lung injury and inflammation, decreased incidence of infection, and increased survival in animal models. CONCLUSIONS The administration of SPA-DXM-NLP to animal models resulted in increased levels of DXM in the lungs, indicating active targeting. The efficacy against ALI of the immunoliposomes was shown to be superior to conventional dexamethasone administration. These results demonstrate the potential of actively targeted glucocorticoid therapy in the treatment of lung disease in clinical practice.
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Affiliation(s)
- Xue-Yuan Chen
- Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Shan-Mei Wang
- Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Nan Li
- Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yang Hu
- Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yuan Zhang
- Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Jin-Fu Xu
- Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Xia Li
- Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Jie Ren
- Institute of Nano and Bio-polymeric materials, Tongji University, Shanghai, China
| | - Bo Su
- Centrol Laboratory of Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Wei-Zhong Yuan
- Institute of Nano and Bio-polymeric materials, Tongji University, Shanghai, China
| | - Xin-Rong Teng
- Institute of Nano and Bio-polymeric materials, Tongji University, Shanghai, China
| | - Rong-Xuan Zhang
- Department of Pathology, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Dian-hua Jiang
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Xavier Mulet
- CSIRO Materials Science and Engineering, Clayton, Victoria, Australia
| | - Hui-Ping Li
- Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
- * E-mail:
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Tokhtaeva E, Sachs G, Sun H, Dada LA, Sznajder JI, Vagin O. Identification of the amino acid region involved in the intercellular interaction between the β1 subunits of Na+/K+ -ATPase. J Cell Sci 2012; 125:1605-16. [PMID: 22328500 DOI: 10.1242/jcs.100149] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Epithelial junctions depend on intercellular interactions between β(1) subunits of the Na(+)/K(+)-ATPase molecules of neighboring cells. The interaction between dog and rat subunits is less effective than the interaction between two dog β(1) subunits, indicating the importance of species-specific regions for β(1)-β(1) binding. To identify these regions, the species-specific amino acid residues were mapped on a high-resolution structure of the Na(+)/K(+)-ATPase β(1) subunit to select those exposed towards the β(1) subunit of the neighboring cell. These exposed residues were mutated in both dog and rat YFP-linked β(1) subunits (YFP-β(1)) and also in the secreted extracellular domain of the dog β(1) subunit. Five rat-like mutations in the amino acid region spanning residues 198-207 of the dog YFP-β(1) expressed in Madin-Darby canine kidney (MDCK) cells decreased co-precipitation of the endogenous dog β(1) subunit with YFP-β(1) to the level observed between dog β(1) and rat YFP-β(1). In parallel, these mutations impaired the recognition of YFP-β(1) by the dog-specific antibody that inhibits cell adhesion between MDCK cells. Accordingly, dog-like mutations in rat YFP-β(1) increased both the (YFP-β(1))-β(1) interaction in MDCK cells and recognition by the antibody. Conversely, rat-like mutations in the secreted extracellular domain of the dog β(1) subunit increased its interaction with rat YFP-β(1) in vitro. In addition, these mutations resulted in a reduction of intercellular adhesion between rat lung epithelial cells following addition of the secreted extracellular domain of the dog β(1) subunit to a cell suspension. Therefore, the amino acid region 198-207 is crucial for both trans-dimerization of the Na(+)/K(+)-ATPase β(1) subunits and cell-cell adhesion.
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Affiliation(s)
- Elmira Tokhtaeva
- Department of Physiology, School of Medicine, UCLA and Veterans Administration Greater Los Angeles Health Care System, Los Angeles, VAGLAHS/West LA, Building 113, Room 324, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA
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Xie GL, Yan H, Lu ZF. Inhibition of glucocorticoid-induced changes of Na(+), K(+)-ATPase in rat lens by a glucocorticoid receptor antagonist RU486. Exp Eye Res 2010; 91:544-9. [PMID: 20637751 DOI: 10.1016/j.exer.2010.07.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2010] [Revised: 07/06/2010] [Accepted: 07/08/2010] [Indexed: 01/24/2023]
Abstract
Cataract formation can be induced by prolonged use of glucocorticoids. The underlying mechanism is not fully understood yet. The presence of the functional glucocorticoid receptor (GR) in human and rat lens epithelial cells suggests that glucocorticoids target lens epithelial cells directly and specifically. Na(+), K(+)-ATPase has long been recognized for its role in regulating electrolyte concentration in the lens, contributing to lens transparency. We previously reported that the inactivation of Na(+), K(+)-ATPase induced by a glucocorticoid in rat lens. Therefore, the question is whether the changes of Na(+), K(+)-ATPase can be induced through the specific GR activation in glucocorticoid-induced cataract formation. Clear rat lenses were cultured in vitro and were treated with or without dexamethasone (Dex) or RU486 (a GR antagonist). The lenses were cultured for 7 days and photographed daily to record the development of opacity. The activity of Na(+), K(+)-ATPase was determined by using spectrophotometric analysis. The mRNA and protein level expressions of Na(+), K(+)-ATPase α1 were examined by reverse transcription polymerase chain reaction (RT-PCR), Western blot and immunohistochemistry analysis, respectively. Our findings are presented in this study and show that mist-like opacity of the lens was observed as early as 5 days after incubation with dexamethasone. The opacity was more obvious at day 7 in the Dex group. The lenses of the untreated group and the RU486+Dex group remained transparent throughout the incubation. The activity of Na(+), K(+)-ATPase in the Dex-treated group decreased in a time-dependent manner. There was no significant loss of enzyme activity in either the control or the RU486+Dex group throughout the incubation period. Both the protein and mRNA expression levels of Na(+), K(+)-ATPase α1 in the capsule-epithelium of lenses decreased in the Dex-treated group. The GR antagonist RU486 inhibited the decrease of the expression of Na(+), K(+)-ATPase α1 induced by Dex. All of the above results suggested that the GR-mediated reduction of Na(+), K(+)-ATPase may contribute to the formation of steroid-induced cataract. Intervention in this pathway maybe helpful to avoid glucocorticoids-cataract formation.
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Chen WL, Lin CT, Yao CC, Huang YH, Chou YB, Yin HS, Hu FR. In-Vitro Effects of Dexamethasone on Cellular Proliferation, Apoptosis, and Na+-K+-ATPase Activity of Bovine Corneal Endothelial Cells. Ocul Immunol Inflamm 2009; 14:215-23. [PMID: 16911983 DOI: 10.1080/09273940600732380] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE To assess the in-vitro effects of dexamethasone (DEX) on the proliferation, apoptosis, and Na+-K+-ATPase activity of bovine corneal endothelial cells. METHODS Bovine corneal endothelial cells were cultured with DEX ranging from 10-10 to 10-3 M. The effect of DEX on the proliferation was analyzed by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay. Apoptosis and necrosis were detected by staining with fluorescein-conjugated annexin V and propidium iodide, followed by flow cytometry. The effect of DEX on Na+-K+-ATPase activity was evaluated using non-isotopic methods. RESULTS DEX did not affect cellular proliferation or induce apoptosis/necrosis from 10-10 to 10-5 M. At 10-4 and 10-3 M, DEX significantly decreased proliferation and increased apoptosis and/or necrosis. DEX significantly increased the Na+-K+-ATPase activity from 10-8 to 10-6 M, with the maximal effect at 10-6 M (p < 0.01); this effect was inhibited by RU38486, an antiglucocorticoid molecule. CONCLUSIONS Bovine corneal endothelial cells express glucocorticoid receptor (GR) mRNA and protein. DEX decreases cell proliferation and induces cellular apoptosis and/or necrosis at high concentrations. DEX also increases the Na+-K+-ATPase activity at certain concentrations.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Blotting, Western
- Cattle
- Cell Proliferation/drug effects
- Cells, Cultured
- Dexamethasone/pharmacology
- Electrophoresis, Polyacrylamide Gel
- Endothelium, Corneal/drug effects
- Endothelium, Corneal/metabolism
- Endothelium, Corneal/pathology
- Flow Cytometry
- Fluorescent Antibody Technique, Indirect
- Glucocorticoids/pharmacology
- Hormone Antagonists/pharmacology
- Microscopy, Fluorescence
- Mifepristone/pharmacology
- RNA, Messenger/metabolism
- Receptors, Glucocorticoid/genetics
- Receptors, Glucocorticoid/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sodium-Potassium-Exchanging ATPase/metabolism
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Affiliation(s)
- Wei-Li Chen
- Department of Ophthalmology and Graduate Institute of Clinical Medicine, National Taipei University Hospital, Taipei, Taiwan
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Kim SH, Kim KX, Raveendran NN, Wu T, Pondugula SR, Marcus DC. Regulation of ENaC-mediated sodium transport by glucocorticoids in Reissner's membrane epithelium. Am J Physiol Cell Physiol 2009; 296:C544-57. [PMID: 19144862 DOI: 10.1152/ajpcell.00338.2008] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Reissner's membrane epithelium forms much of the barrier that produces and sustains the large ionic differences between cochlear endolymph and perilymph. We have reported that Reissner's membrane contributes to normal cochlear function by absorbing Na(+) from endolymph via amiloride-sensitive channels in gerbil inner ear. We used mouse Reissner's membrane to 1) identify candidate genes involved in the Na(+) transport pathway, 2) determine whether their level of expression was regulated by the synthetic glucocorticoid dexamethasone, and 3) obtain functional evidence for the physiological importance of these genes. Transcripts were present for alpha-, beta-, and gamma-subunits of epithelial Na(+) channel (ENaC); corticosteroid receptors GR (glucocorticoid receptor) and MR (mineralocorticoid receptor); GR agonist regulator 11beta-hydroxysteroid dehydrogenase (HSD) type 1 (11beta-HSD1); Na(+) transport control components SGK1, Nedd4-2, and WNKs; and K(+) channels and Na(+)-K(+)-ATPase. Expression of the MR agonist regulator 11beta-HSD2 was not detected. Dexamethasone upregulated transcripts for alpha- and beta-subunits of ENaC ( approximately 6- and approximately 3-fold), KCNK1 ( approximately 3-fold), 11beta-HSD1 ( approximately 2-fold), SGK1 ( approximately 2-fold), and WNK4 ( approximately 3-fold). Transepithelial currents from the apical to the basolateral side of Reissner's membrane were sensitive to amiloride (IC(50) approximately 0.7 muM) and benzamil (IC(50) approximately 0.1 muM), but not EIPA (IC(50) approximately 34 muM); amiloride-blocked transepithelial current was not immediately changed by forskolin/IBMX. Currents were reduced by ouabain, lowered bath Na(+) concentration (from 150 to 120 mM), and K(+) channel blockers (XE-991, Ba(2+), and acidification from pH 7.4 to 6.5). Dexamethasone-stimulated current and gene expression were reduced by mifepristone, but not spironolactone. These molecular, pharmacological, and functional observations are consistent with Na(+) absorption by mouse Reissner's membrane, which is mediated by apical ENaC and/or other amiloride-sensitive channels, basolateral Na(+)-K(+)-ATPase, and K(+)-permeable channels and is under the control of glucocorticoids. These results provide an understanding and a molecular definition of an important transport function of Reissner's membrane epithelium in the homeostasis of cochlear endolymph.
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Affiliation(s)
- Sung Huhn Kim
- Kansas State Univ., Anatomy & Physiology, 228 Coles Hall, Manhattan, KS 66506-5802, USA
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Unfried K, Sydlik U, Bierhals K, Weissenberg A, Abel J. Carbon nanoparticle-induced lung epithelial cell proliferation is mediated by receptor-dependent Akt activation. Am J Physiol Lung Cell Mol Physiol 2008; 294:L358-67. [DOI: 10.1152/ajplung.00323.2007] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Treatment of lung epithelial cells with different kinds of nano-sized particles leads to cell proliferation. Because bigger particles fail to induce this reaction, it is suggested that the special surface properties, due to the extremely small size of these kinds of materials, is the common principle responsible for this specific cell reaction. Here the activation of the protein kinase B (Akt) signaling cascade by carbon nanoparticles was investigated with regard to its relevance for proliferation. Kinetics and dose-response experiments demonstrated that Akt is specifically activated by nanoparticulate carbon particles in rat alveolar type II epithelial cells as well as in human bronchial epithelial cells. This pathway appeared to be dependent on epidermal growth factor receptor and β1-integrins. The activation of Akt by these receptors is known to be a feature of adhesion-dependent signaling. However, intracellular proteins described in this context (focal adhesion kinase pp125FAK and integrin-linked kinase) were not activated, indicating a specific signaling mechanism. Inhibitor studies demonstrate that nanoparticle-induced proliferation is mediated by phosphoinositide 3-kinases and Akt. Moreover, overexpression of mutant Akt, as well as pretreatment with an Akt inhibitor, reduced nanoparticle-specific ERK1/2 phosphorylation, which is decisive for nanoparticle-induced proliferation. With this report, we describe the activation of a pathway by carbon nanoparticles that was so far known to be triggered by ligand receptor binding or on cell adhesion to extracellular matrix proteins.
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Liu Z, Braverman LE, Malabanan A. Thyrotoxic Periodic Paralysis in A Hispanic Man after the Administration Of Prednisone. Endocr Pract 2006; 12:427-31. [PMID: 16901800 DOI: 10.4158/ep.12.4.427] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To present a case of thyrotoxic periodic paralysis (TPP) in a Hispanic man and to discuss the potential precipitating mechanisms. METHODS We review the clinical and laboratory findings relative to the occurrence of TPP in a 34-year-old Hispanic man, who had been diagnosed as having Graves' disease. RESULTS TPP is a rare complication of thyrotoxicosis. The two known triggers of TPP are high carbohydrate intake and rest after strenuous physical activity. Other precipitating factors include ingestion of alcohol, infection, trauma, emotional stress, and exposure to cold. Nonselective beta-adrenergic blocking agents are used as prophylaxis for the paralytic attacks. Glucocorticoids have been used to treat nonresponsive and recurrent episodes. Nevertheless, our patient, a 34-year-old Hispanic man, had received propranolol for 7 days and one single dose of prednisone 2 hours before the onset of the paralysis. In patients with TPP, the Na+/K+-adenosinetriphosphatase (ATPase) pump activity is considerably increased by excess thyroid hormones, resulting in an increased intracellular potassium shift. Insulin activates the Na+/K+-ATPase pump as well; thus, the precipitating effect of a high carbohydrate diet is explained. Glucocorticoids have been shown to increase the number of Na+/K+-ATPase molecules in skeletal muscle. They also increase insulin secretion in the basal state and the first-phase insulin release after a glucose load. CONCLUSION In our patient with TPP, the onset of the attack was not prevented by the use of propranolol and was likely triggered by the administration of prednisone.
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Affiliation(s)
- Zhao Liu
- Section of Endocrinology, Diabetes and Nutrition, Boston Medical Center, Boston, Massachusetts 02118, USA
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Pondugula SR, Raveendran NN, Ergonul Z, Deng Y, Chen J, Sanneman JD, Palmer LG, Marcus DC. Glucocorticoid regulation of genes in the amiloride-sensitive sodium transport pathway by semicircular canal duct epithelium of neonatal rat. Physiol Genomics 2006; 24:114-23. [PMID: 16263802 DOI: 10.1152/physiolgenomics.00006.2005] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The lumen of the inner ear has an unusually low concentration of endolymphatic Na+, which is important for transduction processes. We have recently shown that glucocorticoid receptors (GR) stimulate absorption of Na+by semicircular canal duct (SCCD) epithelia. In the present study, we sought to determine the presence of genes involved in the control of the amiloride-sensitive Na+transport pathway in rat SCCD epithelia and whether their level of expression was regulated by glucocorticoids using quantitative real-time RT-PCR. Transcripts were present for α-, β-, and γ-subunits of the epithelial sodium channel (ENaC); the α1-, α3-, β1-, and β3-isoforms of Na+-K+-ATPase; inwardly rectifying potassium channels [IC50of short circuit current ( Isc) for Ba2+: 210 μM] Kir2.1, Kir2.2, Kir2.3, Kir2.4, Kir3.1, Kir3.3, Kir4.1, Kir4.2, Kir5.1, and Kir7.1; sulfonyl urea receptor 1 (SUR1); GR; mineralocorticoid receptor (MR); 11β-hydroxysteroid dehydrogenase (11β-HSD) types 1 and 2; serum- and glucocorticoid-regulated kinase 1 (Sgk1); and neural precursor cell-expressed developmentally downregulated 4-2 (Nedd4-2). On the other hand, transcripts for the α4-subunit of Na+-K+-ATPase, Kir1.1, Kir3.2, Kir3.4, Kir6.1, Kir6.2, and SUR2 were found to be absent, and Iscwas not inhibited by glibenclamide. Dexamethasone (100 nM for 24 h) not only upregulated the transcript expression of α-ENaC (∼4-fold), β2-subunit (∼2-fold) and β3-subunit (∼8-fold) of Na+-K+-ATPase, Kir2.1 (∼5-fold), Kir2.2 (∼9-fold), Kir2.4 (∼3-fold), Kir3.1 (∼ 3- fold), Kir3.3 (∼2-fold), Kir4.2 (∼3-fold ), Kir7.1 (∼2-fold), Sgk1 (∼4-fold), and Nedd4-2 (∼2-fold) but also downregulated GR (∼3-fold) and 11β-HSD1 (∼2-fold). Expression of GR and 11β-HSD1 was higher than MR and 11β-HSD2 in the absence of dexamethasone. Dexamethasone altered transcript expression levels (α-ENaC and Sgk1) by activation of GR but not MR. Proteins were present for the α-, β-, and γ-subunits of ENaC and Sgk1, and expression of α- and γ-ENaC was upregulated by dexamethasone. These findings are consistent with the genomic stimulation by glucocorticoids of Na+absorption by SCCD and provide an understanding of the therapeutic action of glucocorticoids in the treatment of Meniere's disease.
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Hao H, Rhodes R, Ingbar DH, Wendt CH. Dexamethasone responsive element in the rat Na, K-ATPase beta1 gene coding region. ACTA ACUST UNITED AC 2004; 1630:55-63. [PMID: 14654235 DOI: 10.1016/j.bbaexp.2003.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Na, K-ATPase plays an essential role in active alveolar epithelial fluid resorption. In fetal and adult alveolar epithelial cells, glucocorticoids (GC) increase Na, K-ATPase activity, mRNA levels, and transcription rate of the beta(1) subunit. In this study, we describe a glucocorticoid responsive element (GRE) in the coding region of the rat Na, K-ATPase beta(1) gene in a rat lung epithelial cell line. Transient transfection experiments with the beta(1) subunit coding region with or without the 5' and 3' untranslated regions demonstrated responsiveness to dexamethasone induction and also identified a GRE at +434 in exon IV. The +434 GRE conferred dexamethasone responsiveness in a heterologous thymidine kinase promoter irrespective of its orientation to the beta(1) promoter. Transcriptional upregulation by dexamethasone was abolished in +434 mutants. Electrophoretic mobility shift assays (EMSA) demonstrated specific binding of nuclear proteins to the +434 GRE and the presence of the GC receptor. This specific binding was inhibited by a GRE previously described in the rat Na, K-ATPase beta(1) gene at -631. In conclusion, we identified a GRE at +434 in the exon IV of the rat Na, K-ATPase beta(1) gene.
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Affiliation(s)
- Hong Hao
- Pulmonary and Critical Care Division, Department of Medicine, MMC 276, University of Minnesota, Minneapolis 55455, USA
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