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Lin S, Liu K, Zhang Y, Jiang M, Lu R, Folts CJ, Gao X, Noble MD, Zhao T, Zhou Z, Lan X, Que J. Pharmacological targeting of p38 MAP-Kinase 6 (MAP2K6) inhibits the growth of esophageal adenocarcinoma. Cell Signal 2018; 51:222-232. [PMID: 30102978 DOI: 10.1016/j.cellsig.2018.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Revised: 07/20/2018] [Accepted: 08/09/2018] [Indexed: 12/12/2022]
Abstract
Drug repurposing with a better understanding of the underlying mechanism has provided new avenues to find treatment for malignancies. Esophageal adenocarcinoma (EAC) is a rapidly increasing cancer with a dismal 5-year survival rate of <15%. Lack of efficient treatment options contributes to the high mortality rate of EAC. To find new therapy against EAC we performed unbiased drug screening of an FDA-approved drug library and identified that the cardiac glycosides including Ouabain, Digoxin and Digitoxin efficiently inhibit the proliferation of EAC cell lines (OE33 and OE19) both in vitro and in vivo. RNA-Sequencing analysis combined with RNAi screening revealed that Ouabain suppresses the proliferation of EAC cells through downregulation of p38 MAP-Kinase 6 (MAP2K6, also known as MKK6). Consistently, shRNA-mediated knockdown of MKK6 reduced the proliferation of EAC cells and tumor growth. Further analysis demonstrated that MKK6 inhibition leads to the reduced levels of the transcription factor SOX9. In line with this finding, deletion of SOX9 with CRISPR/Cas9 resulted in decreased proliferation of EACs in 3D organoid culture and reduced tumor growth. Together these findings establish a druggable axis that can be harnessed for therapeutic gain against EAC.
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Affiliation(s)
- Sijie Lin
- Division of Digestive and Liver Diseases and Center for Human Development, Department of Medicine, Columbia University, NY 10032, USA; Institute for Laboratory Medicine, Fuzhou General Hospital, PLA, Fuzhou, Fujian 350025, PR China
| | - Kuancan Liu
- Division of Digestive and Liver Diseases and Center for Human Development, Department of Medicine, Columbia University, NY 10032, USA; Institute for Laboratory Medicine, Fuzhou General Hospital, PLA, Fuzhou, Fujian 350025, PR China; Dong fang Hospital, Xiamen University, Fuzhou, Fujian 350025, PR China.
| | - Yongchun Zhang
- Division of Digestive and Liver Diseases and Center for Human Development, Department of Medicine, Columbia University, NY 10032, USA
| | - Ming Jiang
- Division of Digestive and Liver Diseases and Center for Human Development, Department of Medicine, Columbia University, NY 10032, USA
| | - Rong Lu
- Division of Digestive and Liver Diseases and Center for Human Development, Department of Medicine, Columbia University, NY 10032, USA
| | - Christopher J Folts
- Department of Biomedical Genetics, University of Rochester, Rochester NY14642, USA
| | - Xia Gao
- Division of Digestive and Liver Diseases and Center for Human Development, Department of Medicine, Columbia University, NY 10032, USA
| | - Mark D Noble
- Department of Biomedical Genetics, University of Rochester, Rochester NY14642, USA
| | - Tingting Zhao
- Dong fang Hospital, Xiamen University, Fuzhou, Fujian 350025, PR China
| | - Zhongren Zhou
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, MO63110, USA
| | - Xiaopeng Lan
- Institute for Laboratory Medicine, Fuzhou General Hospital, PLA, Fuzhou, Fujian 350025, PR China; Dong fang Hospital, Xiamen University, Fuzhou, Fujian 350025, PR China.
| | - Jianwen Que
- Division of Digestive and Liver Diseases and Center for Human Development, Department of Medicine, Columbia University, NY 10032, USA.
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El-Mallakh RS, Payne RS, Schurr A, Gao Y, Lei Z, Kiss B, Gyertyán I, Adham N. Cariprazine delays ouabain-evoked epileptiform spikes and loss of activity in rat hippocampal slices. Psychiatry Res 2015; 229:370-3. [PMID: 26160196 DOI: 10.1016/j.psychres.2015.05.114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 03/24/2015] [Accepted: 05/24/2015] [Indexed: 11/30/2022]
Abstract
In the only bipolar cycling in vitro model, rat hippocampal slices are treated with the sodium pump inhibitor ouabain, which induces epileptiform activity, followed by refractory activity loss that recovers and cycles back to epileptiform activity. Thus, clinical cycling seen in patients with bipolar disorder is modeled on a cellular level as alternating hyperactivity and hypoactivity interspersed with normal activity. In this study, we tested the ability of cariprazine a new antipsychotic candidate to block ouabain-induced changes in rat hippocampal slices. Cycling of population spikes and epileptiform bursts was evoked using an extracellular stimulation electrode located in the Schaeffer collaterals of 400-µm-thick rat hippocampal slices treated with ouabain (3.3μM) alone or in combination with cariprazine (1, 5, 25, and 50µM). Responses were recorded using an extracellular electrode placed in the cell body layer of the CA1 region. Cariprazine 25 and 50µM delayed ouabain-induced epileptiform burst onset and subsequent activity loss. Lower cariprazine concentrations were ineffective. Cariprazine delays the onset of ouabain-induced epileptiform bursts and the loss of spiking activity similarly to that previously demonstrated with the mood stabilizer lithium. These results suggest that cariprazine may have therapeutic potential for treatment of bipolar disorder.
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Affiliation(s)
- Rif S El-Mallakh
- Mood Disorders Research Program, Department of Psychiatry and Behavioral Services, University of Louisville School of Medicine, Louisville, KY, USA.
| | - Ralphiel S Payne
- Department of Anesthesiology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Avital Schurr
- Department of Anesthesiology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Yonglin Gao
- Mood Disorders Research Program, Department of Psychiatry and Behavioral Services, University of Louisville School of Medicine, Louisville, KY, USA
| | - Zhemin Lei
- Department of Obstetrics and Gynecology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Béla Kiss
- Pharmacological and Safety Research, Gedeon Richter Plc., Budapest, Hungary
| | - István Gyertyán
- Pharmacological and Safety Research, Gedeon Richter Plc., Budapest, Hungary
| | - Nika Adham
- Forest Research Institute, Jersey City, NJ, USA
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Lee SY, Kim JH. Mechanisms underlying presynaptic Ca2+ transient and vesicular glutamate release at a CNS nerve terminal during in vitro ischaemia. J Physiol 2015; 593:2793-806. [PMID: 25833340 DOI: 10.1113/jp270060] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 03/30/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Here we demonstrate presynaptic responses and mechanisms of increased vesicular glutamate release during in vitro ischaemia in the calyx of Held terminal, an experimentally accessible presynaptic terminal in the CNS. The ischaemia-induced increase in presynaptic Ca(2+) was mediated by both Ca(2+) influx and Ca(2+) -induced Ca(2+) release from intracellular stores. The reverse operation of the plasma membrane Na(+) /Ca(2+) exchanger (NCX) plays a key role in Ca(2+) influx for triggering Ca(2+) release from intracellular stores at presynaptic terminals during in vitro ischaemia. Ca(2+) uptake via NCX underlies the ischaemia-induced Ca(2+) rise and the consequent increase in vesicular glutamate release from presynaptic terminals in the early phase of brain ischaemia. ABSTRACT An early consequence of brain ischaemia is an increase in vesicular glutamate release from presynaptic terminals. However, the mechanisms of this increased glutamate release are not fully understood. Here we studied presynaptic responses and mechanisms of increased glutamate release during in vitro ischaemia, using pre- and postsynaptic whole-cell recordings and presynaptic Ca(2+) imaging at the calyx of Held synapse in rat brainstem slices. Consistent with results from other brain regions, in vitro ischaemia significantly increased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) without affecting their amplitude, suggesting that ischaemia enhances vesicular glutamate release from presynaptic terminals. We found that ischaemia-induced vesicular glutamate release was dependent on a rise in basal Ca(2+) at presynaptic terminals, which resulted from extracellular Ca(2+) influx and Ca(2+) release from intracellular stores. During early ischaemia, increased Ca(2+) influx into presynaptic terminals was due to reverse operation of the plasma membrane Na(+) /Ca(2+) exchanger (NCX) rather than presynaptic depolarization or voltage-activated Ca(2+) currents. KB-R7943, an inhibitor of NCX, prevented the ischaemia-induced increases in presynaptic Ca(2+) and vesicular glutamate release. In addition, the removal of extracellular Na(+) completely inhibited the ischaemia-induced Ca(2+) rise. It therefore appears that a link between Na(+) accumulation and Ca(2+) uptake via NCX underlies the ischaemia-induced Ca(2+) rise and the consequent increase in vesicular glutamate release from presynaptic terminals in the early phase of brain ischaemia.
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Affiliation(s)
| | - Jun Hee Kim
- Department of Physiology.,Centre for Biomedical Neuroscience, University of Texas Health Science Centre, San Antonio, Texas, 78229, USA
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Gonçalves-de-Albuquerque CF, Burth P, Silva AR, de Moraes IMM, Oliveira FMDJ, Santelli RE, Freire AS, de Lima GS, da Silva ED, da Silva CI, Morandi V, Bozza PT, Younes-Ibrahim M, de Castro Faria Neto HC, de Castro Faria MV. Murine lung injury caused by Leptospira interrogans glycolipoprotein, a specific Na/K-ATPase inhibitor. Respir Res 2014; 15:93. [PMID: 25265888 PMCID: PMC4151191 DOI: 10.1186/s12931-014-0093-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 07/31/2014] [Indexed: 12/15/2022] Open
Abstract
Background Leptospiral glycolipoprotein (GLP) is a potent and specific Na/K-ATPase inhibitor. Severe pulmonary form of leptospirosis is characterized by edema, inflammation and intra-alveolar hemorrhage having a dismal prognosis. Resolution of edema and inflammation determines the outcome of lung injury. Na/K-ATPase activity is responsible for edema clearance. This enzyme works as a cell receptor that triggers activation of mitogen-activated protein kinase (MAPK) intracellular signaling pathway. Therefore, injection of GLP into lungs induces injury by triggering inflammation. Methods We injected GLP and ouabain, into mice lungs and compared their effects. Bronchoalveolar lavage fluid (BALF) was collected for cell and lipid body counting and measurement of protein and lipid mediators (PGE2 and LTB4). The levels of the IL-6, TNFα, IL-1B and MIP-1α were also quantified. Lung images illustrate the injury and whole-body plethysmography was performed to assay lung function. We used Toll-like receptor 4 (TLR4) knockout mice to evaluate leptospiral GLP-induced lung injury. Na/K-ATPase activity was determined in lung cells by nonradioactive rubidium incorporation. We analyzed MAPK p38 activation in lung and in epithelial and endothelial cells. Results Leptospiral GLP and ouabain induced lung edema, cell migration and activation, production of lipid mediators and cytokines and hemorrhage. They induced lung function alterations and inhibited rubidium incorporation. Using TLR4 knockout mice, we showed that the GLP action was not dependent on TLR4 activation. GLP activated of p38 and enhanced cytokine production in cell cultures which was reversed by a selective p38 inhibitor. Conclusions GLP and ouabain induced lung injury, as evidenced by increased lung inflammation and hemorrhage. To our knowledge, this is the first report showing GLP induces lung injury. GLP and ouabain are Na/K-ATPase targets, triggering intracellular signaling pathways. We showed p38 activation by GLP-induced lung injury, which was may be linked to Na/K-ATPase inhibition. Lung inflammation induced by GLP was not dependent on TLR4 activation.
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Pouokam E, Bell A, Diener M. Actions of Angeli's salt, a nitroxyl (HNO) donor, on ion transport across mucosa—submucosa preparations from rat distal colon. Eur J Pharmacol 2013; 715:133-41. [DOI: 10.1016/j.ejphar.2013.05.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/03/2013] [Accepted: 05/20/2013] [Indexed: 10/26/2022]
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Gonçalves-de-Albuquerque CF, Silva AR, Burth P, de Moraes IMM, Oliveira FMDJ, Younes-Ibrahim M, dos Santos MDCB, D'Ávila H, Bozza PT, Faria Neto HCDC, Faria MVDC. Oleic acid induces lung injury in mice through activation of the ERK pathway. Mediators Inflamm 2012; 2012:956509. [PMID: 23209347 PMCID: PMC3504460 DOI: 10.1155/2012/956509] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 10/18/2012] [Indexed: 01/06/2023] Open
Abstract
Oleic acid (OA) can induce acute lung injury in experimental models. In the present work, we used intratracheal OA injection to show augmented oedema formation, cell migration and activation, lipid mediator, and cytokine productions in the bronchoalveolar fluids of Swiss Webster mice. We also demonstrated that OA-induced pulmonary injury is dependent on ERK1/2 activation, since U0126, an inhibitor of ERK1/2 phosphorylation, blocked neutrophil migration, oedema, and lipid body formation as well as IL-6, but not IL-1β production. Using a mice strain carrying a null mutation for the TLR4 receptor, we proved that increased inflammatory parameters after OA challenges were not due to the activation of the TLR4 receptor. With OA being a Na/K-ATPase inhibitor, we suggest the possible involvement of this enzyme as an OA target triggering lung inflammation.
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Gao Y, Payne RS, Schurr A, Hougland T, Lord J, Herman L, Lei Z, Banerjee P, El-Mallakh RS. Memantine reduces mania-like symptoms in animal models. Psychiatry Res 2011; 188:366-71. [PMID: 21269711 DOI: 10.1016/j.psychres.2010.12.030] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 12/18/2010] [Accepted: 12/20/2010] [Indexed: 01/04/2023]
Abstract
Memantine, a selective antagonist of the N-methyl-D-aspartate receptor, is approved for the treatment of moderate to severe Alzheimer's disease. Ion dysregulation is thought to be involved in the pathophysiology of bipolar illness, suggesting that memantine may be effective in treating bipolar manic and/or depressive episodes. We utilized two preclinical models of mania that mimic pathophysiologic changes seen in bipolar illness to examine the potential efficacy of memantine in the treatment of this disorder. Locomotor hyperactivity of male Sprague-Dawley rats in an open field was induced with intracerebroventricular (ICV) administration of 10(-3) M ouabain. Memantine (2.5, 5 or 7.5mg/kg), lithium (6.75 mEq/kg), or vehicle were administered acutely via intraperitoneal injection immediately prior to ouabain, then chronically for 7 days (oral memantine 20, 30, and 40 mg/kg/day in water; lithium 2.4 g/kg food). In a second model of bipolar disorder, cycling between population spikes and epileptiform bursts was investigated in rat hippocampal slices treated with ouabain (3.3 μM) alone or in combination with memantine (0.5, 1.0, and 5.0 μM). Ouabain-induced hyperlocomotion was normalized with acute and chronic lithium and chronic use of memantine. Memantine delayed the onset of ouabain-induced-cycling in hippocampal slices. Memantine may have antimanic properties.
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Affiliation(s)
- Yonglin Gao
- Mood Disorders Research Program, Department of Psychiatry and Behavioral Sciences, University of Louisville School of Medicine, Louisville, KY 40202, United States
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Kapela A, Tsoukias NM. Multiscale FEM modeling of vascular tone: from membrane currents to vessel mechanics. IEEE Trans Biomed Eng 2011; 58:3456-9. [PMID: 21788180 DOI: 10.1109/tbme.2011.2162513] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Regulation of vascular tone is a complex process that remains poorly understood. Here, we present our recent efforts for the development of physiologically realistic models of arterial segments for the analysis of vasoreactivity in health and disease. Multiscale modeling integrates intracellular and cell membrane components into whole-cell models of calcium and membrane potential dynamics. Single-cell models of vascular cells are combined into a multicellular model of the vascular wall, and vessel wall biomechanics are integrated with calcium dynamics in the smooth muscle layer. At each scale, continuum models using finite element method can account for spatial heterogeneity in calcium signaling and for nonuniform deformations of a vessel segment. The outlined approach can be used to investigate cellular mechanisms underlying altered vasoreactivity in hypertension.
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Affiliation(s)
- Adam Kapela
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA.
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9
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Pouokam E, Diener M. Mechanisms of actions of hydrogen sulphide on rat distal colonic epithelium. Br J Pharmacol 2011; 162:392-404. [PMID: 20840536 DOI: 10.1111/j.1476-5381.2010.01026.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND AND PURPOSE The aim of this study was to clarify the mechanisms by which hydrogen sulphide (H₂S) affects ion secretion across rat distal colonic epithelium. EXPERIMENTAL APPROACH Changes in short-circuit current induced by the H₂S-donor, sodium hydrosulphide (NaHS; 10 mmol·L⁻¹), were measured in Ussing chambers after permeabilization of the apical membrane with nystatin. Cytosolic Ca²(+) concentration ([Ca²(+)](i)) and Ca²(+) in intracellular stores were measured with fluorescent dyes. Changes in mitochondrial membrane potential were estimated with rhodamine 123. KEY RESULTS NaHS had a biphasic effect on overall currents across the basolateral membrane: an initial inhibition followed by a secondary stimulation. Both a scilliroside-sensitive action on the Na(+) -K(+)-ATPase and modulation of glibenclamide-sensitive and tetrapentylammonium-sensitive (i.e. ATP-sensitive and Ca²(+)-dependent) basolateral K(+) channels were involved in this action. Experiments with rhodamine 123 revealed that NaHS induced a hyperpolarization of the mitochondrial membrane. NaHS evoked a biphasic change in [Ca²(+)](i) , an initial decrease followed by a secondary increase, known to be mediated by the release of stored Ca²(+). Initial falls in [Ca²(+)](i) were not mediated by a sequestration of Ca²(+) in intracellular Ca²(+) storing organelles, as the Mag-Fura-2 signal was unaffected by NaHS. Falls in [Ca²(+)](i) were inhibited by 2',4'-dichlorobenzamil, an inhibitor of the Na(+)-Ca²(+)-exchanger, and attenuated in Na(+)-free buffer, suggesting a transient stimulation of Ca²(+) outflow by this transporter, directly demonstrated by Mn²(+) quenching experiments. CONCLUSIONS AND IMPLICATIONS ATP-sensitive and Ca²(+)-dependent basolateral K(+) conductances, the basolateral Na(+)-K(+)-pump as well as Ca²(+) transporters were involved in the action of H₂S in regulating colonic ion secretion.
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Affiliation(s)
- E Pouokam
- Institute for Veterinary Physiology, Justus-Liebig-University Giessen, Germany
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10
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Tsoukias NM. Calcium dynamics and signaling in vascular regulation: computational models. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 3:93-106. [PMID: 21061306 DOI: 10.1002/wsbm.97] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Calcium is a universal signaling molecule with a central role in a number of vascular functions including in the regulation of tone and blood flow. Experimentation has provided insights into signaling pathways that lead to or affected by Ca(2+) mobilization in the vasculature. Mathematical modeling offers a systematic approach to the analysis of these mechanisms and can serve as a tool for data interpretation and for guiding new experimental studies. Comprehensive models of calcium dynamics are well advanced for some systems such as the heart. This review summarizes the progress that has been made in modeling Ca(2+) dynamics and signaling in vascular cells. Model simulations show how Ca(2+) signaling emerges as a result of complex, nonlinear interactions that cannot be properly analyzed using only a reductionist's approach. A strategy of integrative modeling in the vasculature is outlined that will allow linking macroscale pathophysiological responses to the underlying cellular mechanisms.
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11
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Li Y, Yang KJ, Park J. Multiple implications of 3-phosphoinositide-dependent protein kinase 1 in human cancer. World J Biol Chem 2010; 1:239-47. [PMID: 21537480 PMCID: PMC3083972 DOI: 10.4331/wjbc.v1.i8.239] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 07/13/2010] [Accepted: 07/20/2010] [Indexed: 02/05/2023] Open
Abstract
3-phosphoinositide-dependent protein kinase-1 (PDK1) is a central mediator of cellular signaling between phosphoinositide-3 kinase and various intracellular serine/threonine kinases, including protein kinase B, p70 ribosomal S6 kinase, serum and glucocorticoid-inducible kinase, and protein kinase C. PDK1 activates members of the AGC family of protein kinases by phosphorylating serine/threonine residues in the activation loop. Here, we review the regulatory mechanisms of PDK1 and its roles in cancer. PDK1 is activated by autophosphorylation in the activation loop and other serine residues, as well as by phosphorylation of Tyr-9 and Tyr-373/376. Src appears to recognize PDK1 following tyrosine phosphorylation. The role of heat shock protein 90 in regulating PDK1 stability and PDK1-Src complex formation are also discussed. Furthermore, we summarize the subcellular distribution of PDK1. Finally, an important role for PDK1 in cancer chemotherapy is proposed. In conclusion, a better understanding of its molecular regulatory mechanisms in various signaling pathways will help to explain how PDK1 acts as an oncogenic kinase in various cancers, and will contribute to the development of novel cancer chemotherapies.
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Affiliation(s)
- Yuwen Li
- Yuwen Li, Keum-Jin Yang, Jongsun Park, Department of Pharmacology, Metabolic Diseases and Cell Signaling Laboratory, Cancer Research Institute, Research Institute for Medical Sciences, College of Medicine, Chungnam National University, Daejeon 301-131, South Korea
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Edwards A. Modeling transport in the kidney: investigating function and dysfunction. Am J Physiol Renal Physiol 2009; 298:F475-84. [PMID: 19889951 DOI: 10.1152/ajprenal.00501.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Mathematical models of water and solute transport in the kidney have significantly expanded our understanding of renal function in both health and disease. This review describes recent theoretical developments and emphasizes the relevance of model findings to major unresolved questions and controversies. These include the fundamental processes by which urine is concentrated in the inner medulla, the ultrastructural basis of proteinuria, irregular flow oscillation patterns in spontaneously hypertensive rats, and the mechanisms underlying the hypotensive effects of thiazides. Macroscopic models of water, NaCl, and urea transport in populations of nephrons have served to test, confirm, or refute a number of hypotheses related to the urine concentrating mechanism. Other macroscopic models focus on the mechanisms, role, and irregularities of renal hemodynamic control and on the regulation of renal oxygenation. At the mesoscale, models of glomerular filtration have yielded significant insight into the ultrastructural basis underlying a number of disorders. At the cellular scale, models of epithelial solute transport and pericyte Ca2+ signaling are being used to elucidate transport pathways and the effects of hormones and drugs. Areas where further theoretical progress is conditional on experimental advances are also identified.
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Affiliation(s)
- Aurélie Edwards
- Department of Chemical and Biological Engineering, Tufts University, Medford, Massachusetts 02155, USA.
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Wang Q, Rajshankar D, Branch DR, Siminovitch KA, Herrera Abreu MT, Downey GP, McCulloch CA. Protein-tyrosine phosphatase-alpha and Src functionally link focal adhesions to the endoplasmic reticulum to mediate interleukin-1-induced Ca2+ signaling. J Biol Chem 2009; 284:20763-72. [PMID: 19497848 DOI: 10.1074/jbc.m808828200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Calcium (Ca2+) signaling by the pro-inflammatory cytokine interleukin-1 (IL-1) is dependent on focal adhesions, which contain diverse structural and signaling proteins including protein phosphatases. We examined here the role of protein-tyrosine phosphatase (PTP) alpha in regulating IL-1-induced Ca2+ signaling in fibroblasts. IL-1 promoted recruitment of PTPalpha to focal adhesions and endoplasmic reticulum (ER) fractions, as well as tyrosine phosphorylation of the ER Ca2+ release channel IP3R. In response to IL-1, catalytically active PTPalpha was required for Ca2+ release from the ER, Src-dependent phosphorylation of IP3R1 and accumulation of IP3R1 in focal adhesions. In pulldown assays and immunoprecipitations PTPalpha was required for the association of PTPalpha with IP3R1 and c-Src, and this association was increased by IL-1. Collectively, these data indicate that PTPalpha acts as an adaptor to mediate functional links between focal adhesions and the ER that enable IL-1-induced Ca2+ signaling.
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Affiliation(s)
- Qin Wang
- Canadian Institutes of Health Research Group in Matrix Dynamics, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5S 3E2, Canada
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Cao C, Payne K, Lee-Kwon W, Zhang Z, Lim SW, Hamlyn J, Blaustein MP, Kwon HM, Pallone TL. Chronic ouabain treatment induces vasa recta endothelial dysfunction in the rat. Am J Physiol Renal Physiol 2008; 296:F98-F106. [PMID: 18945826 DOI: 10.1152/ajprenal.90429.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Descending vasa recta (DVR) are 15-microm vessels that perfuse the renal medulla. Ouabain has been shown to augment DVR endothelial cytoplasmic Ca(2+) ([Ca(2+)](CYT)) signaling. In this study, we examined the expression of the ouabain-sensitive Na-K-ATPase alpha2 subunit in the rat renal vasculature and tested effects of acute ouabain exposure and chronic ouabain treatment on DVR. Immunostaining with antibodies directed against the alpha2 subunit verified its expression in both DVR pericytes and endothelium. Acute application of ouabain (100 or 500 nM) augmented the DVR nitric oxide generation stimulated by acetylcholine (ACh; 10 microM). At a concentration of 1 mM, ouabain constricted microperfused DVR, whereas at 100 nM, it was without effect. Acute ouabain (100 nM) did not augment constriction by angiotensin II (0.5 or 10 nM), whereas l-nitroarginine methyl ester-induced contraction of DVR was slightly enhanced. Ouabain-hypertensive (OH) rats were generated by chronic ouabain treatment (30 microg.kg(-1).day(-1), 5 wk). The acute endothelial [Ca(2+)](CYT) elevation by ouabain (100 nM) was absent in DVR endothelia of OH rats. The [Ca(2+)](CYT) response to 10 nM ACh was also eliminated, whereas the response to 10 microM ACh was not. The endothelial [Ca(2+)](CYT) response to bradykinin (100 nM) was significantly attenuated. We conclude that endothelial responses may offset the ability of acute ouabain exposure to enhance DVR vasoconstriction. Chronic exposure to ouabain, in vivo, leads to hypertension and DVR endothelial dysfunction, manifested as reduced [Ca(2+)](CYT) responses to both ouabain- and endothelium-dependent vasodilators.
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Affiliation(s)
- Chunhua Cao
- Department of Medicine, UMMS, Baltimore, MD 21201, USA
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Abstract
The Na-K-ATPase is an energy-transducing ion pump that converts the free energy of ATP into transmembrane ion gradients. It also serves as a functional receptor for cardiotonic steroids such as ouabain and digoxin. Binding of ouabain to the Na-K-ATPase can activate calcium signaling in a cell-specific manner. The exquisite calcium modulation via the Na-K-ATPase is achieved by the ability of the pump to integrate signals from numerous protein and non-protein molecules, including ion transporters, channels, protein kinases/phosphatases, as well as cellular Na+. This review focuses on the unique properties of the Na-K-ATPase and its role in the formation of different calcium-signaling microdomains.
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Affiliation(s)
- Jiang Tian
- Department of Physiology and Pharmacology, University of Toledo Health Science Campus, Toledo, Ohio, USA
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Cai T, Wang H, Chen Y, Liu L, Gunning WT, Quintas LEM, Xie ZJ. Regulation of caveolin-1 membrane trafficking by the Na/K-ATPase. ACTA ACUST UNITED AC 2008; 182:1153-69. [PMID: 18794328 PMCID: PMC2542476 DOI: 10.1083/jcb.200712022] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Here, we show that the Na/K-ATPase interacts with caveolin-1 (Cav1) and regulates Cav1 trafficking. Graded knockdown of Na/K-ATPase decreases the plasma membrane pool of Cav1, which results in a significant reduction in the number of caveolae on the cell surface. These effects are independent of the pumping function of Na/K-ATPase, and instead depend on interaction between Na/K-ATPase and Cav1 mediated by an N-terminal caveolin-binding motif within the ATPase α1 subunit. Moreover, knockdown of the Na/K-ATPase increases basal levels of active Src and stimulates endocytosis of Cav1 from the plasma membrane. Microtubule-dependent long-range directional trafficking in Na/K-ATPase–depleted cells results in perinuclear accumulation of Cav1-positive vesicles. Finally, Na/K-ATPase knockdown has no effect on processing or exit of Cav1 from the Golgi. Thus, the Na/K-ATPase regulates Cav1 endocytic trafficking and stabilizes the Cav1 plasma membrane pool.
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Affiliation(s)
- Ting Cai
- Department of Physiology and Pharmacology, University of Toledo College of Medicine, Health Science Campus, Toledo, OH 43614, USA
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Edwards A, Pallone TL. Mechanisms underlying angiotensin II-induced calcium oscillations. Am J Physiol Renal Physiol 2008; 295:F568-84. [PMID: 18562632 DOI: 10.1152/ajprenal.00107.2008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To gain insight into the mechanisms that underlie angiotensin II (ANG II)-induced cytoplasmic Ca2+ concentration ([Ca]cyt) oscillations in medullary pericytes, we expanded a prior model of ion fluxes. ANG II stimulation was simulated by doubling maximal inositol trisphosphate (IP3) production and imposing a 90% blockade of K+ channels. We investigated two configurations, one in which ryanodine receptors (RyR) and IP3 receptors (IP3R) occupy a common store and a second in which they reside on separate stores. Our results suggest that Ca2+ release from stores and import from the extracellular space are key determinants of oscillations because both raise [Ca] in subplasmalemmal spaces near RyR. When the Ca2+-induced Ca2+ release (CICR) threshold of RyR is exceeded, the ensuing Ca2+ release is limited by Ca2+ reuptake into stores and export across the plasmalemma. If sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) pumps do not remain saturated and sarcoplasmic reticulum Ca2+ stores are replenished, that phase is followed by a resumption of leak from internal stores that leads either to [Ca]cyt elevation below the CICR threshold (no oscillations) or to elevation above it (oscillations). Our model predicts that oscillations are more prone to occur when IP3R and RyR stores are separate because, in that case, Ca2+ released by RyR during CICR can enhance filling of adjacent IP3 stores to favor a high subsequent leak that generates further CICR events. Moreover, the existence or absence of oscillations depends on the set points of several parameters, so that biological variation might well explain the presence or absence of oscillations in individual pericytes.
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Affiliation(s)
- Aurélie Edwards
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA 02155, USA.
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Oloizia B, Paul RJ. Ca2+ clearance and contractility in vascular smooth muscle: evidence from gene-altered murine models. J Mol Cell Cardiol 2008; 45:347-62. [PMID: 18598701 DOI: 10.1016/j.yjmcc.2008.05.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 05/17/2008] [Accepted: 05/29/2008] [Indexed: 01/15/2023]
Abstract
The central importance of calcium clearance proteins, and their regulators, in the modulation of myocardial contractility and intracellular Ca(2+) concentration ([Ca(2+)](i)) has long been established. Key players identified include the Na(+)-Ca(2+) exchanger, the Na(+)-K(+) ATPase, the sarco(endo)plasmic reticulum Ca(2+)-ATPase and associated phospholamban. Gene-targeted and transgenic murine models have been critical in the elucidation of their function. The study of these proteins in the regulation of contractile parameters in vascular smooth muscle, on the other hand, is less well studied. More recently, gene-targeted and transgenic models have expanded our knowledge of Ca(2+) clearance proteins and their role in both tonic and phasic smooth muscle contractility. In this review, we will briefly treat the mechanisms which underlie Ca(2+) clearance in smooth muscle. These will be addressed in light of studies using gene-modified mouse models, the results of which will be compared and contrasted with those in the cardiomyocyte. The recently identified human mutations in phospholamban, which lead to dilated cardiomyopathy, are also present in vascular and other smooth muscle. Given the importance of these Ca(2+) clearance systems to modulation of smooth muscle, it is likely that mutations will also lead to smooth muscle pathology.
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Affiliation(s)
- Brian Oloizia
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0576, USA
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Zhang Q, Cao C, Zhang Z, Wier WG, Edwards A, Pallone TL. Membrane current oscillations in descending vasa recta pericytes. Am J Physiol Renal Physiol 2008; 294:F656-66. [PMID: 18184740 DOI: 10.1152/ajprenal.00493.2007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the origin of spontaneous transient inward current (STIC) oscillations in descending vasa recta (DVR) pericytes. In cells clamped at -80 mV, angiotensin II (ANG II; 10 nmol/l) induced oscillations with mean amplitude and frequency of -65.5 pA and 1.2 Hz. Simultaneous recording of cytoplasmic calcium ([Ca(2+)](CYT)) and membrane current oscillations verified their synchrony and the correlation of their amplitudes. Confocal recording in fluo-4-loaded DVR showed that ANG II can induce either stable pericyte [Ca(2+)](CYT) elevation or oscillations, while decreasing adjacent endothelial [Ca(2+)](CYT). Oscillating currents reversed sign at -30.2 mV and were blocked by niflumic acid, implicating charge transfer via Cl(-) ion. Removal of extracellular Ca(2+), blockade of Ca(2+) influx with SKF96365 (30 micromol/l), ryanodine (30 micromol/l), or caffeine (10 mmol/l) inhibited oscillations. In contrast, they were insensitive to removal of extracellular Na(+) and exposure to either nifedipine (1 micromol/l) or 2-aminoethoxydiphenyl borate (10 micromol/l). Ouabain (100 nmol/l) increased basal pericyte [Ca(2+)](CYT) and the frequency of resting STICs but did not affect the larger oscillations that followed ANG II stimulation. We conclude that [Ca(2+)](CYT) oscillations stimulate Cl(-) currents. The former are most likely maintained by repetitive cycles of ryanodine-sensitive SR Ca(2+) release and SKF96365-sensitive store refilling.
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Affiliation(s)
- Qingli Zhang
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
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