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Crorkin P, Hao S, Ferreri NR. Responses to Ang II (Angiotensin II), Salt Intake, and Lipopolysaccharide Reveal the Diverse Actions of TNF-α (Tumor Necrosis Factor-α) on Blood Pressure and Renal Function. Hypertension 2022; 79:2656-2670. [PMID: 36129177 PMCID: PMC9649876 DOI: 10.1161/hypertensionaha.122.19464] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
TNF-α (tumor necrosis factor-alpha) is the best known as a proinflammatory cytokine; yet, this cytokine also has important immunomodulatory and regulatory functions. As the effects of TNF-α on immune system function were being revealed, the spectrum of its activities appeared in conflict with each other before investigators defined the settings and mechanisms by which TNF-α contributed to both host defense and chronic inflammation. These effects reflect self-protective mechanisms that may become harmful when dysregulated. The paradigm of physiological and pathophysiological effects of TNF-α has since been uncovered in the lung, colon, and kidney where its role has been identified in pulmonary edema, electrolyte reabsorption, and blood pressure regulation, respectively. Recent studies on the prohypertensive and inflammatory effects of TNF-α in the cardiovascular system juxtaposed to those related to NaCl and blood pressure homeostasis, the response of the kidney to lipopolysaccharide, and protection against bacterial infections are helping define the mechanisms by which TNF-α modulates distinct functions within the kidney. This review discusses how production of TNF-α by renal epithelial cells may contribute to regulatory mechanisms that not only govern electrolyte excretion and blood pressure homeostasis but also maintain the appropriate local hypersalinity environment needed for optimizing the innate immune response to bacterial infections in the kidney. It is possible that the wide range of effects mediated by TNF-α may be related to severity of disease, amount of inflammation and TNF-α levels, and the specific cell types that produce this cytokine, areas that remain to be investigated further.
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Affiliation(s)
- Patrick Crorkin
- Department of Pharmacology, New York Medical College, Valhalla, NY
| | - Shoujin Hao
- Department of Pharmacology, New York Medical College, Valhalla, NY
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2
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Veiras LC, Shen JZY, Bernstein EA, Regis GC, Cao D, Okwan-Duodu D, Khan Z, Gibb DR, Dominici FP, Bernstein KE, Giani JF. Renal Inflammation Induces Salt Sensitivity in Male db/db Mice through Dysregulation of ENaC. J Am Soc Nephrol 2021; 32:1131-1149. [PMID: 33731332 PMCID: PMC8259671 DOI: 10.1681/asn.2020081112] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 01/21/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Hypertension is considered a major risk factor for the progression of diabetic kidney disease. Type 2 diabetes is associated with increased renal sodium reabsorption and salt-sensitive hypertension. Clinical studies show that men have higher risk than premenopausal women for the development of diabetic kidney disease. However, the renal mechanisms that predispose to salt sensitivity during diabetes and whether sexual dimorphism is associated with these mechanisms remains unknown. METHODS Female and male db/db mice exposed to a high-salt diet were used to analyze the progression of diabetic kidney disease and the development of hypertension. RESULTS Male, 34-week-old, db/db mice display hypertension when exposed to a 4-week high-salt treatment, whereas equivalently treated female db/db mice remain normotensive. Salt-sensitive hypertension in male mice was associated with no suppression of the epithelial sodium channel (ENaC) in response to a high-salt diet, despite downregulation of several components of the intrarenal renin-angiotensin system. Male db/db mice show higher levels of proinflammatory cytokines and more immune-cell infiltration in the kidney than do female db/db mice. Blocking inflammation, with either mycophenolate mofetil or by reducing IL-6 levels with a neutralizing anti-IL-6 antibody, prevented the development of salt sensitivity in male db/db mice. CONCLUSIONS The inflammatory response observed in male, but not in female, db/db mice induces salt-sensitive hypertension by impairing ENaC downregulation in response to high salt. These data provide a mechanistic explanation for the sexual dimorphism associated with the development of diabetic kidney disease and salt sensitivity.
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Affiliation(s)
- Luciana C. Veiras
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California
| | - Justin Z. Y. Shen
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California
| | - Ellen A. Bernstein
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California
| | - Giovanna C. Regis
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California
| | - DuoYao Cao
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California
| | - Derick Okwan-Duodu
- Department of Pathology, Cedars-Sinai Medical Center, Los Angeles, California
| | - Zakir Khan
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California
| | - David R. Gibb
- Department of Pathology, Cedars-Sinai Medical Center, Los Angeles, California
| | - Fernando P. Dominici
- Department of Biological Chemistry, School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina
| | - Kenneth E. Bernstein
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California,Department of Pathology, Cedars-Sinai Medical Center, Los Angeles, California
| | - Jorge F. Giani
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California,Department of Pathology, Cedars-Sinai Medical Center, Los Angeles, California
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3
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Repetti R, Majumder N, De Oliveira KC, Meth J, Yangchen T, Sharma M, Srivastava T, Rohatgi R. Unilateral Nephrectomy Stimulates ERK and Is Associated With Enhanced Na Transport. Front Physiol 2021; 12:583453. [PMID: 33633581 PMCID: PMC7901926 DOI: 10.3389/fphys.2021.583453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 01/14/2021] [Indexed: 11/13/2022] Open
Abstract
Nephron loss initiates compensatory hemodynamic and cellular effects on the remaining nephrons. Increases in single nephron glomerular filtration rate and tubular flow rate exert higher fluid shear stress (FSS) on tubules. In principal cell (PC) culture models FSS induces ERK, and ERK is implicated in the regulation of transepithelial sodium (Na) transport, as well as, proliferation. Thus, we hypothesize that high tubular flow and FSS mediate ERK activation in the cortical collecting duct (CCD) of solitary kidney which regulates amiloride sensitive Na transport and affects CCD cell number. Immunoblotting of whole kidney protein lysate was performed to determine phospho-ERK (pERK) expression. Next, sham and unilateral nephrectomized mice were stained with anti-pERK antibodies, and dolichos biflorus agglutinin (DBA) to identify PCs with pERK. Murine PCs (mpkCCD) were grown on semi-permeable supports under static, FSS, and FSS with U0126 (a MEK1/2 inhibitor) conditions to measure the effects of FSS and ERK inhibition on amiloride sensitive Na short circuit current (Isc). pERK abundance was greater in kidney lysate of unilateral vs. sham nephrectomies. The total number of cells in CCD and pERK positive PCs increased in nephrectomized mice (9.3 ± 0.4 vs. 6.1 ± 0.2 and 5.1 ± 0.5 vs. 3.6 ± 0.3 cell per CCD nephrectomy vs. sham, respectively, n > 6 per group, p < 0.05). However, Ki67, a marker of proliferation, did not differ by immunoblot or immunohistochemistry in nephrectomy samples at 1 month compared to sham. Next, amiloride sensitive Isc in static mpkCCD cells was 25.3 ± 1.7 μA/cm2 (n = 21), but after exposure to 24 h of FSS the Isc increased to 41.4 ± 2.8 μA/cm2 (n = 22; p < 0.01) and returned to 19.1 ± 2.1 μA/cm2 (n = 18, p < 0.01) upon treatment with U0126. Though FSS did not alter α- or γ-ENaC expression in mpkCCD cells, γ-ENaC was reduced in U0126 treated cells. In conclusion, pERK increases in whole kidney and, specifically, CCD cells after nephrectomy, but pERK was not associated with active proliferation at 1-month post-nephrectomy. In vitro studies suggest high tubular flow induces ERK dependent ENaC Na absorption and may play a critical role in Na balance post-nephrectomy.
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Affiliation(s)
- Robert Repetti
- Northport VA Medical Center, Northport, NY, United States.,School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Nomrota Majumder
- School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | | | - Jennifer Meth
- Northport VA Medical Center, Northport, NY, United States
| | - Tenzin Yangchen
- Program in Public Health, School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Mukut Sharma
- Kansas City VA Medical Center, Kansas City, MO, United States
| | | | - Rajeev Rohatgi
- Northport VA Medical Center, Northport, NY, United States.,School of Medicine, Stony Brook University, Stony Brook, NY, United States
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4
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Wang X, Antony V, Wang Y, Wu G, Liang G. Pattern recognition receptor‐mediated inflammation in diabetic vascular complications. Med Res Rev 2020; 40:2466-2484. [DOI: 10.1002/med.21711] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 06/23/2020] [Accepted: 06/29/2020] [Indexed: 12/13/2022]
Affiliation(s)
- Xu Wang
- Chemical Biology Research Center, School of Pharmaceutical Sciences Wenzhou Medical University Wenzhou Zhejiang China
| | - Victor Antony
- Chemical Biology Research Center, School of Pharmaceutical Sciences Wenzhou Medical University Wenzhou Zhejiang China
| | - Yi Wang
- Chemical Biology Research Center, School of Pharmaceutical Sciences Wenzhou Medical University Wenzhou Zhejiang China
- Zhuji Biomedical Institute, School of Pharmaceutical Sciences Wenzhou Medical University Zhuji Zhejiang China
| | - Gaojun Wu
- Department of Cardiology Wenzhou Medical University Wenzhou Zhejiang China
| | - Guang Liang
- Chemical Biology Research Center, School of Pharmaceutical Sciences Wenzhou Medical University Wenzhou Zhejiang China
- Zhuji Biomedical Institute, School of Pharmaceutical Sciences Wenzhou Medical University Zhuji Zhejiang China
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5
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Eriguchi M, Bernstein EA, Veiras LC, Khan Z, Cao DY, Fuchs S, McDonough AA, Toblli JE, Gonzalez-Villalobos RA, Bernstein KE, Giani JF. The Absence of the ACE N-Domain Decreases Renal Inflammation and Facilitates Sodium Excretion during Diabetic Kidney Disease. J Am Soc Nephrol 2018; 29:2546-2561. [PMID: 30185469 DOI: 10.1681/asn.2018030323] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 08/03/2018] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Recent evidence emphasizes the critical role of inflammation in the development of diabetic nephropathy. Angiotensin-converting enzyme (ACE) plays an active role in regulating the renal inflammatory response associated with diabetes. Studies have also shown that ACE has roles in inflammation and the immune response that are independent of angiotensin II. ACE's two catalytically independent domains, the N- and C-domains, can process a variety of substrates other than angiotensin I. METHODS To examine the relative contributions of each ACE domain to the sodium retentive state, renal inflammation, and renal injury associated with diabetic kidney disease, we used streptozotocin to induce diabetes in wild-type mice and in genetic mouse models lacking either a functional ACE N-domain (NKO mice) or C-domain (CKO mice). RESULTS In response to a saline challenge, diabetic NKO mice excreted 32% more urinary sodium compared with diabetic wild-type or CKO mice. Diabetic NKO mice also exhibited 55% less renal epithelial sodium channel cleavage (a marker of channel activity), 55% less renal IL-1β, 53% less renal TNF-α, and 53% less albuminuria than diabetic wild-type mice. This protective phenotype was not associated with changes in renal angiotensin II levels. Further, we present evidence that the anti-inflammatory tetrapeptide N-acetyl-seryl-asparyl-lysyl-proline (AcSDKP), an ACE N-domain-specific substrate that accumulates in the urine of NKO mice, mediates the beneficial effects observed in the NKO. CONCLUSIONS These data indicate that increasing AcSDKP by blocking the ACE N-domain facilitates sodium excretion and ameliorates diabetic kidney disease independent of intrarenal angiotensin II regulation.
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Affiliation(s)
| | | | | | | | | | - Sebastien Fuchs
- Department of Basic Medical Sciences, Western University of Health Sciences, Pomona, California
| | - Alicia A McDonough
- Department of Integrative Anatomical Sciences, Keck School of Medicine of University of Southern California, Los Angeles, California
| | - Jorge E Toblli
- Laboratory of Experimental Medicine, Hospital Alemán, University of Buenos Aires, National Scientific and Technical Research Council, Buenos Aires, Argentina; and
| | - Romer A Gonzalez-Villalobos
- Departments of Biomedical Sciences and.,Cardiovascular and Metabolism Discovery, Janssen Research and Development, Spring House, Pennsylvania
| | - Kenneth E Bernstein
- Departments of Biomedical Sciences and.,Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California
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Graham LA, Dominiczak AF, Ferreri NR. Role of renal transporters and novel regulatory interactions in the TAL that control blood pressure. Physiol Genomics 2017; 49:261-276. [PMID: 28389525 PMCID: PMC5451551 DOI: 10.1152/physiolgenomics.00017.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 03/27/2017] [Accepted: 04/05/2017] [Indexed: 12/31/2022] Open
Abstract
Hypertension (HTN), a major public health issue is currently the leading factor in the global burden of disease, where associated complications account for 9.4 million deaths worldwide every year. Excessive dietary salt intake is among the environmental factors that contribute to HTN, known as salt sensitivity. The heterogeneity of salt sensitivity and the multiple mechanisms that link high salt intake to increases in blood pressure are of upmost importance for therapeutic application. A continual increase in the kidney's reabsorption of sodium (Na+) relies on sequential actions at various segments along the nephron. When the distal segments of the nephron fail to regulate Na+, the effects on Na+ homeostasis are unfavorable. We propose that the specific nephron region where increased active uptake occurs as a result of variations in Na+ reabsorption is at the thick ascending limb of the loop of Henle (TAL). The purpose of this review is to urge the consideration of the TAL as contributing to the pathophysiology of salt-sensitive HTN. Further research in this area will enable development of a therapeutic application for targeted treatment.
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Affiliation(s)
- Lesley A Graham
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow Cardiovascular and Medical Sciences, Glasgow, United Kingdom; and
| | - Anna F Dominiczak
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow Cardiovascular and Medical Sciences, Glasgow, United Kingdom; and
| | - Nicholas R Ferreri
- Department of Pharmacology, New York Medical College, Valhalla, New York
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7
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An angiotensin II type 1 receptor binding molecule has a critical role in hypertension in a chronic kidney disease model. Kidney Int 2017; 91:1115-1125. [PMID: 28081856 DOI: 10.1016/j.kint.2016.10.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 09/28/2016] [Accepted: 10/27/2016] [Indexed: 01/13/2023]
Abstract
Angiotensin II type 1 receptor-associated protein (ATRAP) promotes AT1R internalization along with suppression of hyperactivation of tissue AT1R signaling. Here, we provide evidence that renal ATRAP plays a critical role in suppressing hypertension in a mouse remnant kidney model of chronic kidney disease. The effect of 5/6 nephrectomy on endogenous ATRAP expression was examined in the kidney of C57BL/6 and 129/Sv mice. While 129/Sv mice with a remnant kidney showed decreased renal ATRAP expression and developed hypertension, C57BL/6 mice exhibited increased renal ATRAP expression and resistance to progressive hypertension. Consequently, we hypothesized that downregulation of renal ATRAP expression is involved in pathogenesis of hypertension in the remnant kidney model of chronic kidney disease. Interestingly, 5/6 nephrectomy in ATRAP-knockout mice on the hypertension-resistant C57BL/6 background caused hypertension with increased plasma volume. Moreover, in knockout compared to wild-type C57BL/6 mice after 5/6 nephrectomy, renal expression of the epithelial sodium channel α-subunit and tumor necrosis factor-α was significantly enhanced, concomitant with increased plasma membrane angiotensin II type 1 receptor in the kidneys. Thus, renal ATRAP downregulation is involved in the onset and progression of blood pressure elevation caused by renal mass reduction, and implicates ATRAP as a therapeutic target for hypertension in chronic kidney disease.
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8
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Jia G, Habibi J, Aroor AR, Martinez-Lemus LA, DeMarco VG, Ramirez-Perez FI, Sun Z, Hayden MR, Meininger GA, Mueller KB, Jaffe IZ, Sowers JR. Endothelial Mineralocorticoid Receptor Mediates Diet-Induced Aortic Stiffness in Females. Circ Res 2016; 118:935-943. [PMID: 26879229 DOI: 10.1161/circresaha.115.308269] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 02/12/2016] [Indexed: 12/13/2022]
Abstract
RATIONALE Enhanced activation of the mineralocorticoid receptors (MRs) in cardiovascular tissues increases oxidative stress, maladaptive immune responses, and inflammation with associated functional vascular abnormalities. We previously demonstrated that consumption of a Western diet (WD) for 16 weeks results in aortic stiffening, and that these abnormalities were prevented by systemic MR blockade in female mice. However, the cell-specific role of endothelial cell MR (ECMR) in these maladaptive vascular effects has not been explored. OBJECTIVE We hypothesized that specific deletion of the ECMR would prevent WD-induced increases in endothelial sodium channel activation, reductions in bioavailable nitric oxide, increased vascular remodeling, and associated increases in vascular stiffness in females. METHODS AND RESULTS Four-week-old female ECMR knockout and wild-type mice were fed either mouse chow or WD for 16 weeks. WD feeding resulted in aortic stiffness and endothelial dysfunction as determined in vivo by pulse wave velocity and ex vivo by atomic force microscopy, and wire and pressure myography. The WD-induced aortic stiffness was associated with enhanced endothelial sodium channel activation, attenuated endothelial nitric oxide synthase activation, increased oxidative stress, a proinflammatory immune response and fibrosis. Conversely, cell-specific ECMR deficiency prevented WD-induced aortic fibrosis and stiffness in conjunction with reductions in endothelial sodium channel activation, oxidative stress and macrophage proinflammatory polarization, restoration of endothelial nitric oxide synthase activation. CONCLUSIONS Increased ECMR signaling associated with consumption of a WD plays a key role in endothelial sodium channel activation, reduced nitric oxide production, oxidative stress, and inflammation that lead to aortic remodeling and stiffness in female mice.
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Affiliation(s)
- Guanghong Jia
- Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, MO, 65212, USA.,Research Service, Harry S Truman Memorial Veterans Hospital, Research Service, 800 Hospital Dr, Columbia, MO, 65201, USA
| | - Javad Habibi
- Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, MO, 65212, USA.,Research Service, Harry S Truman Memorial Veterans Hospital, Research Service, 800 Hospital Dr, Columbia, MO, 65201, USA
| | - Annayya R Aroor
- Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, MO, 65212, USA.,Research Service, Harry S Truman Memorial Veterans Hospital, Research Service, 800 Hospital Dr, Columbia, MO, 65201, USA
| | - Luis A Martinez-Lemus
- Research Service, Harry S Truman Memorial Veterans Hospital, Research Service, 800 Hospital Dr, Columbia, MO, 65201, USA.,Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65212, USA
| | - Vincent G DeMarco
- Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, MO, 65212, USA.,Research Service, Harry S Truman Memorial Veterans Hospital, Research Service, 800 Hospital Dr, Columbia, MO, 65201, USA.,Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA
| | | | - Zhe Sun
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65212, USA
| | - Melvin R Hayden
- Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, MO, 65212, USA.,Research Service, Harry S Truman Memorial Veterans Hospital, Research Service, 800 Hospital Dr, Columbia, MO, 65201, USA
| | - Gerald A Meininger
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65212, USA
| | | | - Iris Z Jaffe
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA 02111, USA
| | - James R Sowers
- Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, MO, 65212, USA.,Research Service, Harry S Truman Memorial Veterans Hospital, Research Service, 800 Hospital Dr, Columbia, MO, 65201, USA.,Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65212, USA
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9
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Awad AS, You H, Gao T, Cooper TK, Nedospasov SA, Vacher J, Wilkinson PF, Farrell FX, Brian Reeves W. Macrophage-derived tumor necrosis factor-α mediates diabetic renal injury. Kidney Int 2015; 88:722-33. [PMID: 26061548 PMCID: PMC4589442 DOI: 10.1038/ki.2015.162] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 03/24/2015] [Accepted: 04/09/2015] [Indexed: 01/15/2023]
Abstract
Monocyte/macrophage recruitment correlates strongly with the progression of diabetic nephropathy. Tumor necrosis factor-alpha (TNF-α) is produced by monocytes/macrophages but the direct role of TNF-α and/or macrophage-derived TNF-α in the progression of diabetic nephropathy remains unclear. Here we tested whether inhibition of TNF-α confers kidney protection in diabetic nephropathy via a macrophage-derived TNF-α dependent pathway. Compared to vehicle-treated mice, blockade of TNF-α with a murine anti-TNF-α antibody conferred kidney protection in Ins2Akita mice as indicated by reductions in albuminuria, plasma creatinine, histopathologic changes, kidney macrophage recruitment and plasma inflammatory cytokine levels at 18 weeks of age. To assess the direct role of macrophage-derived TNF-α in diabetic nephropathy, we generated macrophage specific TNF-α deficient mice (CD11bCre/TNF-αFlox/Flox). Conditional ablation of TNF-α in macrophages significantly reduced albuminuria, the increase in plasma creatinine and BUN, histopathologic changes and kidney macrophage recruitment compared to diabetic TNF-αFlox/Flox control mice after 12 weeks of streptozotocin-induced diabetes. Thus, production of TNF-α by macrophages plays a major role in diabetic renal injury. Hence, blocking TNF-α could be a novel therapeutic approach for treatment of diabetic nephropathy.
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Affiliation(s)
- Alaa S Awad
- Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Hanning You
- Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Ting Gao
- Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Timothy K Cooper
- Department of Comparative Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
| | - Sergei A Nedospasov
- Engelhardt Institute of Molecular Biology and Lomonosov Moscow State University, Moscow, Russia
| | - Jean Vacher
- Clinical Research Institute of Montreal, Départment de Médecine, Université de Montréal, Montreal, Quebec, Canada
| | - Patrick F Wilkinson
- Department of Immunology Research, Janssen R&D, Spring House, Pennsylvania, USA
| | - Francis X Farrell
- Department of Immunology Research, Janssen R&D, Spring House, Pennsylvania, USA
| | - W Brian Reeves
- Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania, USA
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10
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Ito K, Hirooka Y, Sunagawa K. Cardiac sympathetic afferent stimulation induces salt-sensitive sympathoexcitation through hypothalamic epithelial Na+ channel activation. Am J Physiol Heart Circ Physiol 2014; 308:H530-9. [PMID: 25527778 DOI: 10.1152/ajpheart.00586.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cardiac sympathetic afferent (CSA), which plays an important role in heart-brain communication for sympathoexcitation, is stimulated in heart failure. Additionally, high salt intake leads to further sympathoexcitation due to activation of hypothalamic epithelial Na(+) channels (ENaCs) in heart failure. In the present study, we stimulated the CSA in adult male mice by epicardial application of capsaicin and using ethanol as a control to determine whether CSA stimulation led to activation of hypothalamic ENaCs, resulting in salt-induced sympathoexcitation. Three days after capsaicin treatment, an upregulation of hypothalamic α-ENaCs, without activation of mineralocorticoid receptors, was observed. We also examined expression levels of the known ENaC activator TNF-α. Hypothalamic TNF-α increased in capsaicin-treated mice, whereas intracerebroventricular infusion of the TNF-α blocker etanercept prevented capsaicin-induced upregulation of α-ENaCs. To examine brain arterial pressure (AP) sensitivity toward Na(+), we performed an intracerebroventricular infusion of high Na(+)-containing (0.2 M) artificial cerebrospinal fluid. AP and heart rate were significantly increased in capsaicin-treated mice compared with control mice. CSA stimulation also caused excitatory responses with high salt intake. Compared with a regular salt diet, the high-salt diet augmented AP, heart rate, and 24-h urinary norepinephrine excretion, which is an indirect marker of sympathetic activity with mineralocorticoid receptor activation, in capsaicin-treated mice but not in ethanol-treated mice. Treatment with etanercept or the ENaC blocker benzamil prevented these salt-induced excitatory responses. In summary, we show that CSA stimulation leads to an upregulation of hypothalamic α-ENaCs mediated via an increase in TNF-α and results in increased salt sensitivity.
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Affiliation(s)
- Koji Ito
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan; and
| | - Yoshitaka Hirooka
- Department of Advanced Cardiovascular Regulation and Therapeutics, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Kenji Sunagawa
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan; and
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11
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Ndisang JF, Jadhav A. Hemin therapy improves kidney function in male streptozotocin-induced diabetic rats: role of the heme oxygenase/atrial natriuretic peptide/adiponectin axis. Endocrinology 2014; 155:215-29. [PMID: 24140713 DOI: 10.1210/en.2013-1050] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Diabetic nephropathy is characterized by elevated macrophage infiltration and inflammation. Although heme-oxygenase (HO) is cytoprotective, its role in macrophage infiltration and nephropathy in type 1 diabetes is not completely elucidated. Administering the HO inducer, hemin, to streptozotocin-diabetic rats suppressed renal proinflammatory macrophage-M1 phenotype alongside several proinflammatory agents, chemokines, and cytokines including macrophage inflammatory protein 1α (MIP-1α), macrophage-chemoattractant protein-1 (MCP-1), TNF-α, IL-1β, IL-6, nuclear factor-κB (NF-κB), and aldosterone, a stimulator of the inflammatory/oxidative transcription factor, NF-κB. Similarly, hemin therapy attenuated extracellular matrix/profibrotic proteins implicated in renal injury including fibronectin, collagen-IV, and TGF-β1 and reduced several renal histopathological lesions such as glomerulosclerosis, tubular necrosis, tubular vacuolization, and interstitial macrophage infiltration. Furthermore, hemin reduced markers of kidney dysfunction like proteinuria and albuminuria but increased creatinine clearance, suggesting improved kidney function. Correspondingly, hemin significantly enhanced the antiinflammatory macrophage-M2 phenotype, IL-10, adiponectin, HO-1, HO activity, and atrial natriuretic-peptide (ANP), a substance that abates TNF-α, IL-6, and IL-1β, with parallel increase of urinary cGMP, a surrogate marker of ANP. Contrarily, coadministering the HO inhibitor, chromium-mesoporphyrin with the HO-inducer, hemin nullified the antidiabetic and renoprotective effects, whereas administering chromium-mesoporphyrin alone abrogated basal HO activity, reduced basal adiponectin and ANP levels, aggravated hyperglycemia, and further increased MCP-1, MIP-1α, aldosterone, NF-κB, TNF-α, IL-6, IL-1β, proteinuria/albuminuria, and aggravated creatinine clearance, thus exacerbating renal dysfunction, suggesting the importance of the basal HO-adiponectin-ANP axis in renoprotection and kidney function. Collectively, these data suggest that hemin ameliorates diabetic nephropathy by selectively enhancing the antiinflammatory macrophage-M2 phenotype and IL-10 while concomitantly abating the proinflammatory macrophage-M1 phenotype and suppressing extracellular matrix/profibrotic factors with reduction of renal lesions including interstitial macrophage infiltration. Because aldosterone stimulate NF-κB, which activates cytokines like TNF-α, IL-6, IL-1β that in turn stimulate chemokines such as MCP-1 and MIP-1α to promote macrophage-M1 infiltration, the hemin-dependent potentiation of the HO-adiponectin-ANP axis may account for reduced macrophage infiltration and inflammatory insults in streptozotocin-diabetic rats.
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Affiliation(s)
- Joseph Fomusi Ndisang
- Department of Physiology, University of Saskatchewan College of Medicine, Saskatoon, Saskatchewan, Canada S7N 5E5
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12
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Attenuation of hyperlipidemia- and diabetes-induced early-stage apoptosis and late-stage renal dysfunction via administration of fibroblast growth factor-21 is associated with suppression of renal inflammation. PLoS One 2013; 8:e82275. [PMID: 24349242 PMCID: PMC3857822 DOI: 10.1371/journal.pone.0082275] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/01/2013] [Indexed: 12/21/2022] Open
Abstract
Background Lipotoxicity is a key feature of the pathogenesis of diabetic kidney disease, and is attributed to excessive lipid accumulation (hyperlipidemia). Increasing evidence suggests that fibroblast growth factor (FGF)21 has a crucial role in lipid metabolism under diabetic conditions. Objective The present study investigated whether FGF21 can prevent hyperlipidemia- or diabetes-induced renal damage, and if so, the possible mechanism. Methods Mice were injected with free fatty acids (FFAs, 10 mg/10 g body weight) or streptozotocin (150 mg/kg) to establish a lipotoxic model or type 1 diabetic model, respectively. Simultaneously the mice were treated with FGF21 (100 µg/kg) for 10 or 80 days. The kidney weight-to-tibia length ratio and renal function were assessed. Systematic and renal lipid levels were detected by ELISA and Oil Red O staining. Renal apoptosis was examined by TUNEL assay. Inflammation, oxidative stress, and fibrosis were assessed by Western blot. Results Acute FFA administration and chronic diabetes were associated with lower kidney-to-tibia length ratio, higher lipid levels, severe renal apoptosis and renal dysfunction. Obvious inflammation, oxidative stress and fibrosis also observed in the kidney of both mice models. Deletion of the fgf21 gene further enhanced the above pathological changes, which were significantly prevented by administration of exogenous FGF21. Conclusion These results suggest that FFA administration and diabetes induced renal damage, which was further enhanced in FGF21 knock-out mice. Administration of FGF21 significantly prevented both FFA- and diabetes-induced renal damage partially by decreasing renal lipid accumulation and suppressing inflammation, oxidative stress, and fibrosis.
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Urinary prostasin excretion is associated with adiposity in nonhypertensive African-American adolescents. Pediatr Res 2013; 74:206-10. [PMID: 23863785 PMCID: PMC4332551 DOI: 10.1038/pr.2013.81] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 02/05/2013] [Indexed: 01/07/2023]
Abstract
BACKGROUND Metabolic abnormalities in obesity can overstimulate the renal epithelial sodium channel (ENaC) and subsequently lead to blood pressure (BP) elevation. Prostasin, a membrane-bound/secretive serine protease, is thought to activate ENaC via the proteolytic cleavage of the channel. Our specific aim was to explore whether there is a relationship between adiposity and urinary prostasin excretion at the population level. METHODS In 271 African-American adolescents, urinary prostasin concentrations were determined by enzyme-linked immunosorbent assay and normalized by urinary creatinine. RESULTS Urinary prostasin excretion increased in the overweight/obese group (n = 110, 38.2 ± 4.0 ng/mg) vs. the normal-weight group (n = 161, 20.7 ± 1.2 ng/mg, P = 0.03). Urinary prostasin excretion was significantly correlated with BMI percentiles (r = 0.14, P = 0.02), waist circumference (r = 0.13, P = 0.05), total body fat mass (r = 0.20, P < 0.01), and percentage body fat (r = 0.23, P < 0.01). Urinary prostasin excretion was also correlated with plasma aldosterone (r = 0.11, P = 0.05) and systolic BP (SBP; r = 0.15, P = 0.02), but the significances disappeared after adjustment of any of the adiposity variables. CONCLUSION Our data for the first time suggest that adiposity plays a role in urinary prostasin excretion, and its associations with aldosterone and BP appear to be modulated by adiposity. Whether urinary prostasin excretion is a biomarker/mechanism underlying obesity-related hypertension deserves further investigations.
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Shrestha K, Shao Z, Singh D, Dupont M, Tang WHW. Relation of systemic and urinary neutrophil gelatinase-associated lipocalin levels to different aspects of impaired renal function in patients with acute decompensated heart failure. Am J Cardiol 2012; 110:1329-35. [PMID: 22835414 DOI: 10.1016/j.amjcard.2012.06.035] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 06/08/2012] [Accepted: 06/08/2012] [Indexed: 12/17/2022]
Abstract
Both urine and serum neutrophil gelatinase-associated lipocalin (NGAL) reflect active chronic kidney disease and predict acute kidney injury. However, a direct comparison of these markers in acute decompensated heart failure has not been performed. We prospectively evaluated 93 patients admitted with acute decompensated heart failure and treated with intravenous furosemide and measured both systemic (serum) and urine NGAL levels and their corresponding markers of estimated glomerular filtration rate, natriuresis (urine sodium), and diuretic response (net output, urine sodium/furosemide ratio). In our study cohort, the median urine and serum NGAL level was 34 ng/ml (interquartile range 24 to 86) and 252 ng/ml (interquartile range 175 to 350), respectively. The urine and serum NGAL levels correlated modestly (r = 0.37, p <0.001). Higher urine (but not systemic) NGAL correlated with the markers of impaired natriuresis and reduced diuresis (p <0.005 for all). In contrast, higher serum NGAL demonstrated a stronger relation with reduced glomerular filtration function (p <0.0001). Both markers predicted acute kidney injury (urine NGAL, odds ratio 1.7, p = 0.035; serum NGAL, odds ratio 1.9, p = 0.009). In conclusion, in patients with acute decompensated heart failure, urine NGAL levels reflect renal distal tubular injury with impaired natriuresis and diuresis, and systemic NGAL levels demonstrate a stronger association with glomerular filtration function. Both systemic and urine NGAL predict worsening renal function.
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Affiliation(s)
- Kevin Shrestha
- Heart and Vascular Institute, Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio, USA
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15
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Yang J, Pollock JS, Carmines PK. NADPH oxidase and PKC contribute to increased Na transport by the thick ascending limb during type 1 diabetes. Hypertension 2011; 59:431-6. [PMID: 22203737 DOI: 10.1161/hypertensionaha.111.184796] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Type 1 diabetes triggers protein kinase C (PKC)-dependent NADPH oxidase activation in the renal medullary thick ascending limb (mTAL), resulting in accelerated superoxide production. As acute exposure to superoxide stimulates NaCl transport by the mTAL, we hypothesized that diabetes increases mTAL Na(+) transport through PKC-dependent and NADPH oxidase-dependent mechanisms. An O(2)-sensitive fluoroprobe was used to measure O(2) consumption by mTALs from rats with streptozotocin-induced diabetes and sham rats. In sham mTALs, total O(2) consumption was evident as a 0.34±0.03 U change in normalized relative fluorescence (ΔNRF)/min per mg protein. Ouabain (2 mmol/L) reduced O(2) consumption by 69±4% and 500 μmol/L furosemide reduced O(2) consumption by 58±8%. Total O(2) consumption was accelerated in mTAL from diabetic rats (0.74±0.07 ΔNRF/min/mg protein; P<0.05 versus sham), reflecting increases in ouabain- and furosemide-sensitive O(2) consumption. NADPH oxidase inhibition (100 μmol/L apocynin) reduced furosemide-sensitive O(2) consumption by mTAL from diabetic rats to values not different from sham. The PKC inhibitor calphostin C (1 μmol/L) or the PKCα/β inhibitor Gö6976 (1 μmol/L) decreased furosemide-sensitive O(2) consumption in both groups, achieving values that did not differ between sham and diabetic. PKCβ inhibition had no effect in either group. Similar inhibitory patterns were evident with regard to ouabain-sensitive O(2) consumption. We conclude that NADPH oxidase and PKC (primarily PKCα) contribute to an increase in O(2) consumption by the mTAL during type 1 diabetes through effects on the ouabain-sensitive Na(+)-K(+)-ATPase and furosemide-sensitive Na(+)-K(+)-2Cl(-) cotransporter that are primarily responsible for active transport Na(+) reabsorption by this nephron segment.
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Affiliation(s)
- Jing Yang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
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Horita S, Seki G, Yamada H, Suzuki M, Koike K, Fujita T. Insulin resistance, obesity, hypertension, and renal sodium transport. Int J Hypertens 2011; 2011:391762. [PMID: 21629870 PMCID: PMC3095959 DOI: 10.4061/2011/391762] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 02/16/2011] [Indexed: 12/12/2022] Open
Abstract
Sodium transport through various nephron segments is quite important in regulating sodium reabsorption and blood pressure. Among several regulators of this process, insulin acts on almost all the nephron segments and is a strong enhancer of sodium reabsorption. Sodium-proton exchanger type 3 (NHE3) is a main regulator of sodium reabsorption in the luminal side of proximal tubule. In the basolateral side of the proximal tubule, sodium-bicarbonate cotransporter (NBCe1) mediates sodium and bicarbonate exit from tubular cells. In the distal nephron and the connecting tubule, epithelial sodium channel (ENaC) is of great importance to sodium reabsorption. NHE3, NBCe1, and ENaC are all regulated by insulin. Recently with-no-lysine (WNK) kinases, responsible for familial hypertension, stimulating sodium reabsorption in the distal nephron, have been found to be also regulated by insulin. We will discuss the regulation of renal sodium transport by insulin and its roles in the pathogenesis of hypertension in insulin resistance.
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Affiliation(s)
- Shoko Horita
- Department of Internal Medicine, Faculty of Medicine, The University of Tokyo 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan
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Li K, Guo D, Zhu H, Hering-Smith KS, Hamm LL, Ouyang J, Dong Y. Interleukin-6 stimulates epithelial sodium channels in mouse cortical collecting duct cells. Am J Physiol Regul Integr Comp Physiol 2010; 299:R590-5. [PMID: 20504903 DOI: 10.1152/ajpregu.00207.2009] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The aim of this study is to elucidate the effects of interleukin-6 (IL-6) on the expression and activity of the epithelial sodium channel (ENaC), which is one of the key mechanisms underlying tubular sodium reabsorption. M-1 cortical collecting duct cells were treated with IL-6 (100 ng/ml) for 12 h. Real-time polymerase chain reaction and immunoblotting were employed to examine the mRNA and protein abundance. Transepithelial voltage (V(te)) and resistance (R(te)) were measured with an ohm/voltmeter (EVOM, WPI). The equivalent current was calculated as the ratio of V(te) to R(te.) Treatment with IL-6 (n = 5) increased the mRNA abundance of alpha-ENaC by 11 +/- 7% (P = not significant), beta-ENaC by 78 +/- 14% (P = 0.01), gamma-ENaC by 185 +/- 38% (P = 0.02), and prostasin by 29 +/- 5% (P = 0.01), all normalized by beta-actin. Treatment with IL-6 increased the protein expression of alpha-ENaC by 19 +/- 3% (P = 0.001), beta-ENaC by 89 +/- 21% (P = 0.01), gamma-ENaC by 36 +/- 12% (P = 0.02), and prostasin by 33 +/- 6% (P = 0.02). The amiloride-sensitive sodium current increased by 37 +/- 5%, from 6.0 +/- 0.4 to 8.2 +/- 0.3 muA/cm(2) (P < 0.01), in the cells treated with IL-6 compared with controls (P = 0.01). Aprotinin (28 microg/ml), a prostasin inhibitor, reduced the amiloride-sensitive sodium current by 61 +/- 5%, from 6.1 +/- 0.3 to 3.7 +/- 0.2 muA/cm(2) (P = 0.01). The magnitude of the IL-6-induced amiloride-sensitive sodium current in the presence of aprotinin dropped by 57 +/- 2%, from 8.6 +/- 0.2 to 4.9 +/- 0.2 muA/cm(2) (P < 0.01). This study has identified a novel function of IL-6, namely, IL-6 may activate ENaC. Therefore, renal inflammation mediated by IL-6 likely contributes to impaired pressure natriuresis.
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Affiliation(s)
- Ke Li
- Georgia Prevention Institute, Dept. of Pediatrics, Medical College of Georgia, Augusta, GA 30912-3715, USA
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TNF-α reduces the Na+/K+ATPase activity in LLC-PK1cells by activating caspases and JNK and inhibiting NF-κB. Cell Biol Int 2010; 34:607-13. [DOI: 10.1042/cbi20090093] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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19
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Zhang C, Tan Y, Guo W, Li C, Ji S, Li X, Cai L. Attenuation of diabetes-induced renal dysfunction by multiple exposures to low-dose radiation is associated with the suppression of systemic and renal inflammation. Am J Physiol Endocrinol Metab 2009; 297:E1366-77. [PMID: 19789291 DOI: 10.1152/ajpendo.00478.2009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Renal protection against diabetes-induced pathogenic injuries by multiple exposures to low-dose radiation (LDR) was investigated to develop a novel approach to the prevention of renal disease for diabetic subjects. C57BL/6J mice were given multiple low-dose streptozotocin (STZ; 6 x 60 [corrected] mg/kg) to produce a type 1 diabetes. Two weeks after diabetes onset, some of diabetic mice and age-matched nondiabetic mice were exposed whole body to 25 mGy X-rays every other day for 2, 4, 8, 12, and 16 wk. Diabetes caused a significant renal dysfunction, shown by time-dependent increase in urinary microalbumin (Malb) and decrease in urinary creatinine (Cre), and pathological changes, shown by significant increases in renal structural changes and PAS-positive staining. However, diabetes-induced renal dysfunction and pathological changes were significantly, albeit partially, attenuated by multiple exposures to LDR. Furthermore, LDR protection against diabetes-induced renal dysfunction and pathological changes was associated with a significant suppression of diabetes-increased systemic and renal inflammation, shown by significant increases in serum and renal TNFalpha, ICAM-1, IL-18, MCP-1, and PAI-1 contents. To further explore the mechanism by which LDR prevents diabetes-induced renal pathological changes, renal oxidative damage was examined by Western blotting and immunohistochemical staining for 3-nitrotyrosine and 4-hydroxynonenal. Significant increase in oxidative damage was observed in diabetic mice, but not diabetic mice, with LDR. Renal fibrosis, examined by Western blotting of connective tissue growth factor and Masson's trichrome staining, was also evident in the kidneys of diabetic mice but not diabetic mice with LDR. These results suggest that multiple exposures to LDR significantly suppress diabetes-induced systemic and renal inflammatory response and renal oxidative damage, resulting in a prevention of the renal dysfunction and fibrosis.
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Affiliation(s)
- Chi Zhang
- School of Public Health of Jilin University, Changchun, China
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20
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Ramia NF, Kreydiyyeh SI. TNF-alpha modulates the Na+/ K+ ATPase and the Na+K+2Cl- symporter in LLC-PK cells. Eur J Clin Invest 2009; 39:280-8. [PMID: 19292883 DOI: 10.1111/j.1365-2362.2009.02098.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Tumour necrosis factor alpha (TNF-alpha) has been implicated in the development of diabetic nephropathy and the accompanying increase in sodium retention. Inhibition of renal Na(+)/K(+) ATPase was reported to accompany cell death. As TNF is known to induce both apoptosis and cell survival, this work investigated the effect and mechanism of action of TNF-alpha on the Na(+)/K(+) ATPase and the Na(+)K(+)2Cl(-) symporter using LLC-PK(1) cells, a porcine renal proximal tubules cell line. MATERIALS AND METHODS Cells were incubated for 2 h with TNF-alpha in presence and absence of pyrrolidinedithiocarbamate, SP600125 and FK009, respective inhibitors of the transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB), c-Jun N-terminal kinase (JNK) and caspases. The activity of the pump was assayed by measuring the ouabain-inhibitable release of inorganic phosphate. Changes in its expression and the expression of the symporter were monitored by western blot analysis. RESULTS TNF-alpha up-regulated both transporters. NF-kappaB, JNK and the caspases were all mediators of the cytokine action. TNF up-regulated the Na(+)/K(+) pump by stimulating JNK which in turn, activated NF-kappaB and inhibited the caspases. TNF effect on the cotransporter was also mediated via activation of JNK which however inhibited NF-kappaB and by so doing prevented activation of caspases. As caspases were demonstrated to down-regulate the two transporters, their inhibition by TNF is responsible for the observed up-regulatory effect. CONCLUSIONS It was concluded that the Na(+)/K(+) ATPase and Na(+)K(+)2Cl(-) are both targets of TNF-alpha and the effect of the cytokine favours cell survival over cell death.
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Affiliation(s)
- N F Ramia
- Department of Biology, American University of Beirut, Beirut, Lebanon
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21
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Navarro-González JF, Jarque A, Muros M, Mora C, García J. Tumor necrosis factor-alpha as a therapeutic target for diabetic nephropathy. Cytokine Growth Factor Rev 2009; 20:165-73. [PMID: 19251467 DOI: 10.1016/j.cytogfr.2009.02.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Activation of innate immunity with the subsequent development of a chronic low-grade inflammatory response is now recognized as a critical factor in the pathogenesis of diabetes mellitus and diabetic complications, including diabetic nephropathy. In the setting of diabetic nephropathy, there is now evidence of the relevant contribution of pro-inflammatory cytokines, with special participation of tumor necrosis factor-alpha (TNF-alpha). This new pathogenic perspective leads to new therapeutic implications derived from modulation of inflammation and inflammatory cytokines. Experimental studies have shown the beneficial renal actions derived from TNF-alpha inhibition with the use of soluble TNF-alpha receptor fusion proteins, chimeric monoclonal antibodies and pentoxifylline (PTF). Clinical application of this strategy is nowadays limited to PTF administration, which has demonstrated significant beneficial effects in patients with diabetic nephropathy. Overall, these studies indicate that inhibition of TNF-alpha might be an efficacious treatment for renal disease secondary to diabetes mellitus.
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Affiliation(s)
- Juan F Navarro-González
- Nephrology Service, Univeristy Hospital Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain.
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Edinger RS, Lebowitz J, Li H, Alzamora R, Wang H, Johnson JP, Hallows KR. Functional regulation of the epithelial Na+ channel by IkappaB kinase-beta occurs via phosphorylation of the ubiquitin ligase Nedd4-2. J Biol Chem 2009; 284:150-157. [PMID: 18981174 PMCID: PMC2610498 DOI: 10.1074/jbc.m807358200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 10/28/2008] [Indexed: 12/31/2022] Open
Abstract
We have previously shown that IkappaB kinase-beta (IKKbeta) interacts with the epithelial Na+ channel (ENaC) beta-subunit and enhances ENaC activity by increasing its surface expression in Xenopus oocytes. Here, we show that the IKKbeta-ENaC interaction is physiologically relevant in mouse polarized kidney cortical collecting duct (mpkCCDc14) cells, as RNA interference-mediated knockdown of endogenous IKKbeta in these cells by approximately 50% resulted in a similar reduction in transepithelial ENaC-dependent equivalent short circuit current. Although IKKbeta binds to ENaC, there was no detectable phosphorylation of ENaC subunits by IKKbeta in vitro. Because IKKbeta stimulation of ENaC activity occurs through enhanced channel surface expression and the ubiquitin-protein ligase Nedd4-2 has emerged as a central locus for ENaC regulation at the plasma membrane, we tested the role of Nedd4-2 in this regulation. IKKbeta-dependent phosphorylation of Xenopus Nedd4-2 expressed in HEK-293 cells occurred both in vitro and in vivo, suggesting a potential mechanism for regulation of Nedd4-2 and thus ENaC activity. 32P labeling studies utilizing wild-type or mutant forms of Xenopus Nedd4-2 demonstrated that Ser-444, a key SGK1 and protein kinase A-phosphorylated residue, is also an important IKKbeta phosphorylation target. ENaC stimulation by IKKbeta was preserved in oocytes expressing wild-type Nedd4-2 but blocked in oocytes expressing either a dominant-negative (C938S) or phospho-deficient (S444A) Nedd4-2 mutant, suggesting that Nedd4-2 function and phosphorylation by IKKbeta are required for IKKbeta regulation of ENaC. In summary, these results suggest a novel mode of ENaC regulation that occurs through IKKbeta-dependent Nedd4-2 phosphorylation at a recognized SGK1 and protein kinase A target site.
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Affiliation(s)
- Robert S Edinger
- Renal-Electrolyte Division, Departments of Medicine and Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Jonathan Lebowitz
- Renal-Electrolyte Division, Departments of Medicine and Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Hui Li
- Renal-Electrolyte Division, Departments of Medicine and Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Rodrigo Alzamora
- Renal-Electrolyte Division, Departments of Medicine and Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Huamin Wang
- Renal-Electrolyte Division, Departments of Medicine and Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - John P Johnson
- Renal-Electrolyte Division, Departments of Medicine and Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261; Renal-Electrolyte Division, Departments of Medicine and Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Kenneth R Hallows
- Renal-Electrolyte Division, Departments of Medicine and Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261; Renal-Electrolyte Division, Departments of Medicine and Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261.
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Cordovado SK, Zhao Y, Warram JH, Gong H, Anderson KL, Hendrix MM, Hancock LN, Cleary PA, Mueller PW. Nephropathy in type 1 diabetes is diminished in carriers of HLA-DRB1*04: the genetics of kidneys in diabetes (GoKinD) study. Diabetes 2008; 57:518-22. [PMID: 18039812 PMCID: PMC2679388 DOI: 10.2337/db07-0826] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE The purpose of this study was to examine whether known genetic risk factors for type 1 diabetes (HLA-DRB1, -DQA1, and -DQB1 and insulin locus) play a role in the etiology of diabetic nephropathy. RESEARCH DESIGN AND METHODS; Genetic analysis of HLA-DRB1, -DQA1, -DQB1 and the insulin gene (INS) was performed in the Genetics of Kidneys in Diabetes (GoKinD) collection of DNA (European ancestry subset), which includes case patients with type 1 diabetes and nephropathy (n = 829) and control patients with type 1 diabetes but not nephropathy (n = 904). The availability of phenotypic and genotypic data on GoKinD participants allowed a detailed analysis of the association of these genes with diabetic nephropathy. RESULTS Diabetic probands who were homozygous for HLA-DRB1*04 were 50% less likely to have nephropathy than probands without any DRB1*04 alleles. In heterozygous carriers, a protective effect of this allele was not as clearly evident; the mode of inheritance therefore remains unclear. This association was seen in probands with both short (<28 years, P = 0.02) and long (>/=28 years, P = 0.0001) duration of diabetes. A1C, a marker of sustained hyperglycemia, was increased in control probands with normoalbuminuira, despite long-duration diabetes, from 7.2 to 7.3 to 7.7% with 0, 1, and 2 copies of the DRB1*04 allele, respectively. This result is consistent with a protective effect of DRB1*04 that may allow individuals to tolerate higher levels of hyperglycemia, as measured by A1C, without developing nephropathy. CONCLUSIONS These data suggest that carriers of DRB1*04 are protected from some of the injurious hyperglycemic effects related to nephropathy. Interestingly, DRB1*04 appears to be both a risk allele for type 1 diabetes and a protective allele for nephropathy.
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Affiliation(s)
- Suzanne K Cordovado
- Centers for Disease Control and Prevention, 4770 Buford Hwy, MS F-24, Atlanta, GA 30341, USA.
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Bao HF, Zhang ZR, Liang YY, Ma JJ, Eaton DC, Ma HP. Ceramide mediates inhibition of the renal epithelial sodium channel by tumor necrosis factor-alpha through protein kinase C. Am J Physiol Renal Physiol 2007; 293:F1178-86. [PMID: 17634398 DOI: 10.1152/ajprenal.00153.2007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
To determine whether ceramide mediates regulation of the renal epithelial sodium channel (ENaC) by tumor necrosis factor-alpha (TNF-alpha), confocal microscopy and patch-clamp experiments were performed in A6 distal nephron cells. We found that TNF-alpha (100 ng/ml) had no effect on ENaC activity and ceramide level when the cells were grown in the presence of aldosterone, but significantly inhibited ENaC and induced ceramide production after the cells were pretreated with LY 294002, an inhibitor of phosphatidylinositol 3-kinase, for 24 h. The inhibition of ENaC induced by TNF-alpha was mimicked by exogenous sphingomyelinase (0.1 U/ml) and C(2)-ceramide (50 microM), but neither C(2)-dihydroceramide, a membrane-impermeable analog of C(2)-ceramide, nor choline, and abolished by pretreatment with GF109203X, a protein kinase C (PKC) inhibitor. C(2)-ceramide failed to affect ENaC in the cells pretreated with GF109203X, but not in the cells pretreated with PD-98059, a mitogen-activated protein kinase kinase inhibitor. C(2)-ceramide induced the externalization of phosphatidylserine (PS) in control A6 cells, but not in the cells pretreated with GF109203X. Together with our previous finding that cytosolic PS maintains ENaC activity in A6 cells, these data suggest that ceramide mediates TNF-alpha inhibition of the renal ENaC via a pathway associated with PKC-dependent externalization of PS.
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Affiliation(s)
- Hui-Fang Bao
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
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Abstract
The post-macula densa segments of the renal tubule--that is, the distal convoluted tubule, connecting tubule, and collecting duct--play a central role in determining final urine sodium excretion. The major regulated sodium transporters and channels in these cell types include the thiazide-sensitive (Na-Cl) cotransporter (NCC), the epithelial sodium channel (ENaC), and Na-K-ATPase. Furthermore, although not involved in sodium reabsorption, the anion exchanger, pendrin, and the basolateral bumetanide-sensitive Na-K-2Cl cotransporter (NKCC1 or BSC2) have roles in blood-volume maintenance. Mutations in several of these major sodium transporters, channel subunits, and their regulatory proteins have been linked to human diseases such as Liddle's syndrome, Gitelman's syndrome, and Gordon's syndrome, emphasizing the need for appropriate regulation of sodium at these sites for maintenance of sodium balance and normotension.
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Affiliation(s)
- Carolyn A Ecelbarger
- Department of Medicine, Georgetown University, Box 571412, Washington, DC 20057-1412, USA.
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Abstract
Vascular smooth muscle cell (VSMC) migration plays a key role in tissue repair after arterial wall injury. VSMC migration requires integration of chemical and mechanical signaling mechanisms. Recently, we showed that epithelial Na(+) channel (ENaC) proteins are expressed in VSMCs and that ENaC inhibition abolishes pressure-induced constriction in isolated artery segments. However, whether ENaC proteins play a role in VSMC migration is unknown. The goal of this study was to determine whether ENaC molecules are required for VSMC migration. Using RT-PCR, immunoblotting, and immunolabeling, we detected expression of alpha-, beta-, and gammaENaC transcripts and proteins in cultured VSMCs (SV40-LT and A10 cells). Of the three proteins, betaENaC was the most readily detected in both cell lines by immunolocalization and Western blotting. Inhibition of ENaC activity with 1 microM benzamil blunted VSMC migration associated with wound healing (40.3% at 8 h and 26.2% at 24 h) and in response to the chemotactic stimulant platelet-derived growth factor-BB (38.1%). Furthermore, silencing ENaC gene expression with small interfering RNA blunted VSMC migration. These data indicate that expression of ENaC proteins is required for normal VSMC migration and suggest a potential new role for ENaC proteins in vascular tissue repair.
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Affiliation(s)
- Samira C Grifoni
- Dept. of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216, USA
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Abdullah HI, Pedraza PL, Hao S, Rodland KD, McGiff JC, Ferreri NR. NFAT regulates calcium-sensing receptor-mediated TNF production. Am J Physiol Renal Physiol 2005; 290:F1110-7. [PMID: 16380462 DOI: 10.1152/ajprenal.00223.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Because nuclear factor of activated T cells (NFAT) has been implicated in TNF production as well as osmoregulation and salt and water homeostasis, we addressed whether calcium-sensing receptor (CaR)-mediated TNF production in medullary thick ascending limb (mTAL) cells was NFAT dependent. TNF production in response to addition of extracellular Ca(2+) (1.2 mM) was abolished in mTAL cells transiently transfected with a dominant-negative CaR construct (R796W) or pretreated with the phosphatidylinositol phospholipase C (PI-PLC) inhibitor U-73122. Cyclosporine A (CsA), an inhibitor of the serine/threonine phosphatase calcineurin, and a peptide ligand, VIVIT, that selectively inhibits calcineurin-NFAT signaling, also prevented CaR-mediated TNF production. Increases in calcineurin activity in cells challenged with Ca(2+) were inhibited after pretreatment with U-73122 and CsA, suggesting that CaR activation increases calcineurin activity in a PI-PLC-dependent manner. Moreover, U-73122, CsA, and VIVIT inhibited CaR-dependent activity of an NFAT construct that drives expression of firefly luciferase in transiently transfected mTAL cells. Collectively, these data verify the role of calcineurin and NFAT in CaR-mediated TNF production by mTAL cells. Activation of the CaR also increased the binding of NFAT to a consensus oligonucleotide, an effect that was blocked by U-73122 and CsA, suggesting that a calcineurin- and NFAT-dependent pathway increases TNF production in mTAL cells. This mechanism likely regulates TNF gene transcription as U-73122, CsA, and VIVIT blocked CaR-dependent activity of a TNF promoter construct. Elucidating CaR-mediated signaling pathways that regulate TNF production in the mTAL will be crucial to understanding mechanisms that regulate extracellular fluid volume and salt balance.
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Lebowitz J, Edinger RS, An B, Perry CJ, Onate S, Kleyman TR, Johnson JP. IκB Kinase-β (IKKβ) Modulation of Epithelial Sodium Channel Activity. J Biol Chem 2004; 279:41985-90. [PMID: 15292220 DOI: 10.1074/jbc.m403923200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Using the yeast two-hybrid system, we identified a number of proteins that interacted with the carboxyl termini of murine epithelial sodium channel (ENaC) subunits. Initial screens indicated an interaction between the carboxyl terminus of beta-ENaC and IkappaB kinase-beta (IKKbeta), the kinase that phosphorylates Ikappabeta and results in nuclear targeting of NF-kappaB. A true two-hybrid reaction employing full-length IKKbeta and the carboxyl termini of all three subunits confirmed a strong interaction with beta-ENaC, a weak interaction with gamma-ENaC, and no interaction with alpha-ENaC. Co-immunoprecipitation studies for IKKbeta were performed in a murine cortical collecting duct cell line that endogenously expresses ENaC. Immunoprecipitation with beta-ENaC, but not gamma-ENaC, resulted in co-immunoprecipitation of IKKbeta. To examine the direct effects of IKKbeta on ENaC activity, co-expression studies were performed using the two-electrode voltage clamp technique in Xenopus oocytes. Oocytes were injected with cRNAs for alphabetagamma-ENaC with or without cRNA for IKKbeta. Co-injection of IKKbeta significantly increased the amiloride-sensitive current above controls. Using cell surface ENaC labeling, we determined that an increase of ENaC in the plasma membrane accounted for the increase in current. The injection of kinase-dead IKKbeta (K44A) in ENaC-expressing oocytes resulted in a significant decrease in current. Treatment of mpkCCD(c14) cells with aldosterone increased whole cell amounts of IKKbeta. Because this result suggested that aldosterone might activate NF-kappaB, mpkCCD(c14) cells were transiently transfected with a luciferase reporter gene responsive to NF-kappaB activation. Both aldosterone and tumor necrosis factor-alpha (TNFalpha) stimulation caused a similar and significant increase in luciferase activity as compared with controls. We conclude that IKKbeta interacts with ENaC by up-regulating ENaC at the plasma membrane and that the presence of IKKbeta is at very least permissive to ENaC function. These studies also suggest a previously unexpected interaction between the NF-kappaB transcription pathway and steroid regulatory pathways in epithelial cells.
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Affiliation(s)
- Jonathan Lebowitz
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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