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Pedersen SF, Counillon L. The SLC9A-C Mammalian Na +/H + Exchanger Family: Molecules, Mechanisms, and Physiology. Physiol Rev 2019; 99:2015-2113. [PMID: 31507243 DOI: 10.1152/physrev.00028.2018] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Na+/H+ exchangers play pivotal roles in the control of cell and tissue pH by mediating the electroneutral exchange of Na+ and H+ across cellular membranes. They belong to an ancient family of highly evolutionarily conserved proteins, and they play essential physiological roles in all phyla. In this review, we focus on the mammalian Na+/H+ exchangers (NHEs), the solute carrier (SLC) 9 family. This family of electroneutral transporters constitutes three branches: SLC9A, -B, and -C. Within these, each isoform exhibits distinct tissue expression profiles, regulation, and physiological roles. Some of these transporters are highly studied, with hundreds of original articles, and some are still only rudimentarily understood. In this review, we present and discuss the pioneering original work as well as the current state-of-the-art research on mammalian NHEs. We aim to provide the reader with a comprehensive view of core knowledge and recent insights into each family member, from gene organization over protein structure and regulation to physiological and pathophysiological roles. Particular attention is given to the integrated physiology of NHEs in the main organ systems. We provide several novel analyses and useful overviews, and we pinpoint main remaining enigmas, which we hope will inspire novel research on these highly versatile proteins.
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Affiliation(s)
- S F Pedersen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark; and Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, France, and Laboratories of Excellence Ion Channel Science and Therapeutics, Nice, France
| | - L Counillon
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark; and Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, France, and Laboratories of Excellence Ion Channel Science and Therapeutics, Nice, France
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Gan XT, Rajapurohitam V, Xue J, Huang C, Bairwa S, Tang X, Chow JTY, Liu MFW, Chiu F, Sakamoto K, Wagner KU, Karmazyn M. Myocardial Hypertrophic Remodeling and Impaired Left Ventricular Function in Mice with a Cardiac-Specific Deletion of Janus Kinase 2. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 185:3202-10. [PMID: 26475415 DOI: 10.1016/j.ajpath.2015.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 08/05/2015] [Accepted: 08/18/2015] [Indexed: 12/24/2022]
Abstract
The Janus kinase (JAK) system is involved in numerous cell signaling processes and is highly expressed in cardiac tissue. The JAK isoform JAK2 is activated by numerous factors known to influence cardiac function and pathologic conditions. However, although abundant, the role of JAK2 in the regulation or maintenance of cardiac homeostasis remains poorly understood. Using the Cre-loxP system, we generated a cardiac-specific deletion of Jak2 in the mouse to assess the effect on cardiac function with animals followed up for a 4-month period after birth. These animals had marked mortality during this period, although at 4 months mortality in male mice (47%) was substantially higher compared with female mice (30%). Both male and female cardiac Jak2-deleted mice had hypertrophy, dilated cardiomyopathy, and severe left ventricular dysfunction, including a marked reduction in ejection fractions as assessed by serial echocardiography, although the responses in females were somewhat less severe. Defective cardiac function was associated with altered protein levels of sarcoplasmic reticulum calcium-regulatory proteins particularly in hearts from male mice that had depressed levels of SERCA2 and phosphorylated phospholamban. In contrast, SERCA2 was unchanged in hearts of female mice, whereas phosphorylated phospholamban was increased. Our findings suggest that cardiac JAK2 is critical for maintaining normal heart function, and its ablation produces a severe pathologic phenotype composed of myocardial remodeling, heart failure, and pronounced mortality.
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Affiliation(s)
- Xiaohong T Gan
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Venkatesh Rajapurohitam
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Jenny Xue
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Cathy Huang
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Suresh Bairwa
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Xilan Tang
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Jeffrey T-Y Chow
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Melissa F W Liu
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Felix Chiu
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Kazuhito Sakamoto
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, Nebraska
| | - Kay-Uwe Wagner
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, Nebraska
| | - Morris Karmazyn
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
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Kramarenko II, Morinelli TA, Bunni MA, Raymond JR, Garnovskaya MN. The bradykinin B(2) receptor induces multiple cellular responses leading to the proliferation of human renal carcinoma cell lines. Cancer Manag Res 2012; 4:195-205. [PMID: 22904641 PMCID: PMC3421467 DOI: 10.2147/cmar.s31847] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background The vasoactive peptide bradykinin (BK) acts as a potent growth factor for normal kidney cells, but there have been few studies on the role of BK in renal cell carcinomas. Purpose In this study, we tested the hypothesis that BK also acts as a mitogen in kidney carcinomas, and explored the effects of BK in human renal carcinoma A498 cells. Methods The presence of mRNAs for BK B1 and BK B2 receptors in A498 cells was demonstrated by reverse transcription–polymerase chain reaction. To study BK signaling pathways, we employed fluorescent measurements of intracellular Ca2+, measured changes in extracellular pH as a reflection of Na+/H+ exchange (NHE) with a Cytosensor microphysiometer, and assessed extracellular signal-regulated kinase (ERK) activation by Western blotting. Results Exposure to 100 nM of BK resulted in the rapid elevation of intracellular Ca2+, caused a ≥30% increase in NHE activity, and a ≥300% increase in ERK phosphorylation. All BK signals were blocked by HOE140, a BK B2 receptor antagonist, but not by a B1 receptor antagonist. Inhibitor studies suggest that BK-induced ERK activation requires phospholipase C and protein kinase C activities, and is Ca2+/calmodulin-dependent. The amiloride analog 5-(N-methyl-N-isobutyl)-amiloride (MIA) blocked short-term NHE activation and inhibited ERK phosphorylation, suggesting that NHE is critical for ERK activation by BK. BK induced an approximately 40% increase in the proliferation of A498 cells as assessed by bromodeoxyuridine uptake. This effect was blocked by the ERK inhibitor PD98059, and was dependent on NHE activity. Conclusion We conclude that BK exerts mitogenic effects in A498 cells via the BK B2 receptor activation of growth-associated NHE and ERK.
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Affiliation(s)
- Inga I Kramarenko
- Department of Medicine (Nephrology Division), Medical University of South Carolina, Charleston, SC, USA
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Köster S, Pavkov-Keller T, Kühlbrandt W, Yildiz Ö. Structure of human Na+/H+ exchanger NHE1 regulatory region in complex with calmodulin and Ca2+. J Biol Chem 2011; 286:40954-61. [PMID: 21931166 PMCID: PMC3220496 DOI: 10.1074/jbc.m111.286906] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 09/06/2011] [Indexed: 11/06/2022] Open
Abstract
The ubiquitous mammalian Na(+)/H(+) exchanger NHE1 has critical functions in regulating intracellular pH, salt concentration, and cellular volume. The regulatory C-terminal domain of NHE1 is linked to the ion-translocating N-terminal membrane domain and acts as a scaffold for signaling complexes. A major interaction partner is calmodulin (CaM), which binds to two neighboring regions of NHE1 in a strongly Ca(2+)-dependent manner. Upon CaM binding, NHE1 is activated by a shift in sensitivity toward alkaline intracellular pH. Here we report the 2.23 Å crystal structure of the NHE1 CaM binding region (NHE1(CaMBR)) in complex with CaM and Ca(2+). The C- and N-lobes of CaM bind the first and second helix of NHE1(CaMBR), respectively. Both the NHE1 helices and the Ca(2+)-bound CaM are elongated, as confirmed by small angle x-ray scattering analysis. Our x-ray structure sheds new light on the molecular mechanisms of the phosphorylation-dependent regulation of NHE1 and enables us to propose a model of how Ca(2+) regulates NHE1 activity.
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Affiliation(s)
- Stefan Köster
- From the Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438 Frankfurt am Main, Germany and
| | - Tea Pavkov-Keller
- From the Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438 Frankfurt am Main, Germany and
- the Department of Structural Biology, Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/3, 8010 Graz, Austria
| | - Werner Kühlbrandt
- From the Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438 Frankfurt am Main, Germany and
| | - Özkan Yildiz
- From the Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438 Frankfurt am Main, Germany and
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Kurdi M, Booz GW. JAK redux: a second look at the regulation and role of JAKs in the heart. Am J Physiol Heart Circ Physiol 2009; 297:H1545-56. [PMID: 19717737 DOI: 10.1152/ajpheart.00032.2009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A number of type 1 receptor cytokine family members protect the heart from acute and chronic oxidative stress. This protection involves activation of two intracellular signaling cascades: the reperfusion injury salvage kinase (RISK) pathway, which entails activation of phosphatidylinositol 3-kinase (PI3-kinase) and ERK1/2, and JAK-STAT signaling, which involves activation of transcription factor signal transducer and activator of transcription 3 (STAT3). Obligatory for activation of both RISK and STAT3 by nearly all of these cytokines are the kinases JAK1 and JAK2. Yet surprisingly little is known about how JAK1 and JAK2 are regulated in the heart or how they couple to PI3-kinase activation. Although the JAKs are linked to antioxidative stress programs in the heart, we recently reported that these kinases are inhibited by oxidative stress in cardiac myocytes. In contrast, others have reported that cardiac JAK2 is activated by acute oxidative stress by an undefined process. Here we summarize recent insights into the regulation of JAK1 and JAK2. Besides oxidative stress, inhibitory regulation involves phosphorylation, nitration, and intramolecular restraints. Stimulatory regulation involves phosphorylation and adaptor proteins. The net effect of stress on JAK activity in the heart likely represents the sum of both inhibitory and stimulatory processes, along with their dynamic interaction. Thus the regulation of JAKs in the heart, once touted as the paragon of simplicity, is proving rather complicated indeed, requiring a second look. It is our contention that a better understanding of the regulation of this kinase family that is implicated in cardiac protection could translate into effective therapeutic strategies for preventing myocardial damage or repairing the injured heart.
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Affiliation(s)
- Mazen Kurdi
- Department of Chemistry and Biochemistry, Faculty of Sciences, Lebanese University, Rafic Hariri Educational Campus, Hadath, Lebanon
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Kramarenko II, Bunni MA, Morinelli TA, Raymond JR, Garnovskaya MN. Identification of functional bradykinin B(2) receptors endogenously expressed in HEK293 cells. Biochem Pharmacol 2008; 77:269-76. [PMID: 18938142 DOI: 10.1016/j.bcp.2008.09.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 09/19/2008] [Accepted: 09/22/2008] [Indexed: 11/29/2022]
Abstract
The human embryonic kidney (HEK) 293 cell line is widely used in cell biology research. Although HEK293 cells have been meticulously studied, our knowledge about endogenous G protein-coupled receptors (GPCR) in these cells is incomplete. While studying the effects of bradykinin (BK), a potent growth factor for renal cells, we unexpectedly discovered that BK activates extracellular signal-regulated protein kinase 1 and 2 (ERK) in HEK293 cells. Thus, we hypothesized that HEK293 cells possess endogenous BK receptors. RT-PCR demonstrated the presence of mRNAs for BK B(1) and BK B(2) receptors in HEK293 cells. Western blotting with BK B(1) and BK B(2) receptor antibodies confirmed this result at the protein level. To establish that BK receptors are functional, we employed fluorescent measurements of intracellular Ca(2+), measured changes in extracellular acidification rate (ECAR) as a reflection of the Na(+)/H(+) exchange (NHE) with a Cytosensortrade microphysiometer, and assessed ERK activation by Western blotting with a phospho-specific ERK antibody. Exposure of HEK293 cells to BK produced a concentration-dependent rise in intracellular Ca(2+) (EC(50)=36.5+/-8.0 x 10(-9)M), a rapid increase in tyrosine phosphorylation of ERK (EC(50)=9.8+/-0.4 x 10(-9)M), and elevation in ECAR by approximately 20%. All of these signals were blocked by HOE-140 (B(2) receptor antagonist) but not by des-Arg(10)-HOE-140 (B(1) receptor antagonist). We conclude that HEK293 cells express endogenous functional BK B(2) receptors, which couple to the mobilization of intracellular Ca(2+), increases in ECAR and increases in ERK phosphorylation.
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Affiliation(s)
- Inga I Kramarenko
- Medical and Research Services of the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC 29401, USA
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Whitney JA. Reference Systems for Kinase Drug Discovery: Chemical Genetic Approaches to Cell-Based Assays. Assay Drug Dev Technol 2004; 2:417-29. [PMID: 15357923 DOI: 10.1089/adt.2004.2.417] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Protein kinases play key roles in a number of diseases, including cancer, inflammation, and diabetes. Disregulation of kinase-based signal transduction networks results in aberrant cell differentiation, activation, proliferation, and invasion. The growing importance of kinases as a major class of drug targets across multiple large clinical indications, together with the large number of kinases in the genome (~518), has generated a critical need for technologies that enable the identification of potent and selective kinase inhibitors with good drug-like properties. In this review, we describe methods used for developing cell-based assays for kinase inhibitors, discuss advantages and disadvantages of each approach, and describe new chemical genetic methods as reference systems for establishing cell-based assays and their use for functional selectivity profiling of kinase inhibitors.
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Affiliation(s)
- J Andrew Whitney
- Department of Research Informatics, Cellular Genomics, Inc., Branford, CT, USA.
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