RESUMEN
Mammalian (or mechanistic) target of rapamycin complex 2 (mTORC2) is a kinase complex that targets predominantly Akt family proteins, SGK1 and protein kinase C (PKC), and has well-characterized roles in mediating hormone and growth factor effects on a wide array of cellular processes. Recent evidence suggests that mTORC2 is also directly stimulated in renal tubule cells by increased extracellular K+ concentration, leading to activation of the Na+ channel, ENaC, and increasing the electrical driving force for K+ secretion. We identify here a signaling mechanism for this local effect of K+. We show that an increase in extracellular [K+] leads to a rise in intracellular chloride (Cl-), which stimulates a previously unknown scaffolding activity of the protein 'with no lysine-1' (WNK1) kinase. WNK1 interacts selectively with SGK1 and recruits it to mTORC2, resulting in enhanced SGK1 phosphorylation and SGK1-dependent activation of ENaC. This scaffolding effect of WNK1 is independent of its own kinase activity and does not cause a generalized stimulation of mTORC2 kinase activity. These findings establish a novel WNK1-dependent regulatory mechanism that harnesses mTORC2 kinase activity selectively toward SGK1 to control epithelial ion transport and electrolyte homeostasis.
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Proteínas Inmediatas-Precoces , Animales , Diana Mecanicista del Complejo 2 de la Rapamicina/metabolismo , Proteínas Inmediatas-Precoces/genética , Proteínas Inmediatas-Precoces/metabolismo , Cloruros/metabolismo , Canales Epiteliales de Sodio/genética , Canales Epiteliales de Sodio/metabolismo , Proteínas Serina-Treonina Quinasas , Serina-Treonina Quinasas TOR/metabolismo , Transporte Iónico , Antígenos de Histocompatibilidad Menor/genética , Antígenos de Histocompatibilidad Menor/metabolismo , Mamíferos/metabolismoRESUMEN
Background A beneficial role for prostanoids in hypertension is suggested by clinical studies showing nonsteroidal anti-inflammatory drugs, which block the production of all prostanoids, cause sodium retention and exacerbate hypertension. Among prostanoids, prostaglandin E2 and its E-prostanoid receptor 4 receptor (EP4R) have been implicated in blood pressure control. Our previous study found that conditional deletion of EP4R from all tissues in adult mice exacerbates angiotensin II-dependent hypertension, suggesting a powerful effect of EP4R to resist blood pressure elevation. We also found that elimination of EP4R from vascular smooth muscle cells did not affect the severity of hypertension, suggesting nonvascular targets of prostaglandin E mediate this antihypertensive effect. Methods and Results Here we generated mice with cell-specific deletion of EP4R from macrophage-specific EP4 receptor knockouts or kidney epithelial cells (KEKO) to assess the contributions of EP4R in these cells to hypertension pathogenesis. Macrophage-specific EP4 receptor knockouts showed similar blood pressure responses to alterations in dietary sodium or chronic angiotensin II infusion as Controls. By contrast, angiotensin II-dependent hypertension was significantly augmented in KEKOs (mean arterial pressure: 146±3 mm Hg) compared with Controls (137±4 mm Hg; P=0.02), which was accompanied by impaired natriuresis in KEKOs. Because EP4R expression in the kidney is enriched in the collecting duct, we compared responses to amiloride in angiotensin II-infused KEKOs and Controls. Blockade of the epithelial sodium channel with amiloride caused exaggerated natriuresis in KEKOs compared with Controls (0.21±0.01 versus 0.15±0.02 mmol/24 hour per 20 g; P=0.015). Conclusions Our data suggest EP4R in kidney epithelia attenuates hypertension. This antihypertension effect of EP4R may be mediated by reducing the activity of the epithelial sodium channel, thereby promoting natriuresis.
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Hipertensión , Subtipo EP4 de Receptores de Prostaglandina E , Amilorida/uso terapéutico , Angiotensina II/metabolismo , Animales , Antiinflamatorios/uso terapéutico , Antihipertensivos/uso terapéutico , Dinoprostona/metabolismo , Células Epiteliales , Canales Epiteliales de Sodio/genética , Hipertensión/tratamiento farmacológico , Riñón , Macrófagos/metabolismo , Ratones , Prostaglandinas , Subtipo EP4 de Receptores de Prostaglandina E/genética , Subtipo EP4 de Receptores de Prostaglandina E/metabolismo , Sodio/metabolismo , Cloruro de Sodio Dietético/metabolismoRESUMEN
Tubular epithelial cells of the human kidney are considered as targets of Shiga toxins (Stxs) in the Stx-mediated pathogenesis of hemolytic-uremic syndrome (HUS) caused by Stx-releasing enterohemorrhagic Escherichia coli (EHEC). Analysis of Stx-binding glycosphingolipids (GSLs) of primary human renal proximal tubular epithelial cells (pHRPTEpiCs) yielded globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) with Cer (d18:1, C16:0), Cer (d18:1, C22:0), and Cer (d18:1, C24:1/C24:0) as the dominant lipoforms. Investigation of detergent-resistant membranes (DRMs) and nonDRMs, serving as equivalents for the liquid-ordered and liquid-disordered membrane phase, respectively, revealed the prevalence of Gb3Cer and Gb4Cer together with cholesterol and sphingomyelin in DRMs, suggesting lipid raft association. Stx1a and Stx2a exerted strong cellular damage with half-maximal cytotoxic doses (CD50) of 1.31 × 102 pg/mL and 1.66 × 103 pg/mL, respectively, indicating one order of magnitude higher cellular cytotoxicity of Stx1a. Surface acoustic wave (SAW) real-time interaction analysis using biosensor surfaces coated with DRM or nonDRM fractions gave stronger binding capability of Stx1a versus Stx2a that correlated with the lower cytotoxicity of Stx2a. Our study underlines the substantial role of proximal tubular epithelial cells of the human kidney being associated with the development of Stx-mediated HUS at least for Stx1a, while the impact of Stx2a remains somewhat ambiguous.
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Células Epiteliales/efectos de los fármacos , Túbulos Renales Proximales/citología , Toxinas Shiga/toxicidad , Animales , Membrana Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Chlorocebus aethiops , Células Epiteliales/metabolismo , Glicoesfingolípidos/metabolismo , Humanos , Trihexosilceramidas/metabolismoRESUMEN
Mechanical stress has been shown to induce the degradation of lipid droplets in kidney epithelial cells. Here, we illustrate the technical equipment and devices that are currently used in our laboratory to apply shear stress on cells. We provide a detailed protocol to monitor lipophagy in response to shear stress. The aim of this review is to guide and help people understand the challenges in studying acidic lipolysis in cells subjected to fluid flow.
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Autofagia , Metabolismo de los Lípidos , Células Epiteliales , Humanos , Riñón , Gotas Lipídicas/metabolismo , Estrés MecánicoRESUMEN
Fluoride (F) at micromolar (µM) concentrations induces apoptosis in several cell lines. Moreover, proteomic studies have shown major changes in the profile of proteins involved in signal transduction. These effects may negatively affect ion transport in the kidneys. The activity of epithelial sodium channels (ENaCs) is a limiting factor for sodium and water resorption in the kidneys, which is essential for the maintenance of the electrolyte balance and homeostasis of the body. Here we investigated the effects of F, at different concentrations (10, 40, 100, 200, and 400 µM), on the viability of renal epithelial cells (M-1), and ENaC expression. We showed that sodium fluoride (NaF) reduces cell viability in a concentration-dependent manner (p < 0.05) up to a 96-h time-point when compared to control. Sodium fluoride at moderate concentrations (100 and 200 µM), upregulated the ENaC subunit genes Scnn1a and Scnn1g, but not Scnn1b. Sodium fluoride downregulated all three ENaC subunit genes at a higher concentration of 400 µM (p < 0.05). Immunofluorescence analysis showed that Scnn1a and Scnn1g expression was decreased within 24 h of NaF treatment. After 48 h, NaF (400 µM) increased the expression of Scnn1a but not Scnn1g. However, NaF decreased the expression of Scnn1g at all studied concentrations. We conclude that F, at µM concentrations, modulates the expression of ENaC subunit genes, which is likely to significantly affect molecular signaling in kidney epithelial cells.
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Fluoruros , Proteómica , Supervivencia Celular , Células Epiteliales , Fluoruros/toxicidad , RiñónRESUMEN
HIV-associated nephropathy (HIVAN) predominantly affects people of African ancestry living with HIV who do not receive appropriate antiretroviral therapy (ART). Childhood HIVAN is characterized by heavy proteinuria and decreased kidney function. Kidney histology shows mesangial expansion, classic or collapsing glomerulosclerosis, and microcystic renal tubular dilatation leading to kidney enlargement. The pathogenesis of HIVAN involves the kidney recruitment of inflammatory cells and the infection of kidney epithelial cells. In addition, both viral and genetic factors play key roles in this disease. Modern ART has improved the outcome and decreased the prevalence of childhood HIVAN. However, physicians have had modest success providing chronic ART to children and adolescents, and we continue to see children with HIVAN all over the world. This article discusses the progress made during the last decade in our understanding of the pathogenesis and treatment of childhood HIVAN, placing particular emphasis on the mechanisms that mediate the infection of kidney epithelial cells, and the roles of cytokines, the HIV-Tat gene, and the Apolipoprotein-1 (APOL1) gene risk variants in this disease. In view of the large number of children living with HIV at risk of developing HIVAN, better prevention and treatment programs are needed to eradicate this disease.
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Nefropatía Asociada a SIDA , Infecciones por VIH , VIH-1 , Nefropatía Asociada a SIDA/diagnóstico , Nefropatía Asociada a SIDA/epidemiología , Nefropatía Asociada a SIDA/genética , Adolescente , Apolipoproteína L1 , Infecciones por VIH/complicaciones , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/epidemiología , Humanos , RiñónRESUMEN
Oxidative stress is associated with many renal disorders, both acute and chronic, and has also been described to contribute to the disease progression. Therefore, oxidative stress is a potential therapeutic target. The human antioxidant α1-microglobulin (A1M) is a plasma and tissue protein with heme-binding, radical-scavenging and reductase activities. A1M can be internalized by cells, localized to the mitochondria and protect mitochondrial function. Due to its small size, A1M is filtered from the blood into the glomeruli, and taken up by the renal tubular epithelial cells. A1M has previously been described to reduce renal damage in animal models of preeclampsia, radiotherapy and rhabdomyolysis, and is proposed as a pharmacological agent for the treatment of kidney damage. In this paper, we examined the in vitro protective effects of recombinant human A1M (rA1M) in human proximal tubule epithelial cells. Moreover, rA1M was found to protect against heme-induced cell-death both in primary cells (RPTEC) and in a cell-line (HK-2). Expression of stress-related genes was upregulated in both cell cultures in response to heme exposure, as measured by qPCR and confirmed with in situ hybridization in HK-2 cells, whereas co-treatment with rA1M counteracted the upregulation. Mitochondrial respiration, analyzed with the Seahorse extracellular flux analyzer, was compromised following exposure to heme, but preserved by co-treatment with rA1M. Finally, heme addition to RPTE cells induced an upregulation of the endogenous cellular expression of A1M, via activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)-pathway. Overall, data suggest that A1M/rA1M protects against stress-induced damage to tubule epithelial cells that, at least partly, can be attributed to maintaining mitochondrial function.
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alfa-Globulinas/farmacología , Células Epiteliales/patología , Hemo/toxicidad , Túbulos Renales Proximales/patología , Sustancias Protectoras/farmacología , Apoptosis/efectos de los fármacos , Línea Celular , Citoprotección/efectos de los fármacos , Proteínas HSP70 de Choque Térmico/metabolismo , Hemo-Oxigenasa 1/genética , Hemo-Oxigenasa 1/metabolismo , Humanos , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteínas Recombinantes/farmacología , Estrés Fisiológico/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Acute kidney injury (AKI) due to cisplatin is a significant problem that limits its use as an effective chemotherapeutic agent. T cell receptor+CD4-CD8- double negative (DN) T cells constitute the major T cell population in the human and mouse kidney, express programmed cell death protein (PD)-1, and protect from ischemic AKI. However, the pathophysiological roles of DN T cells in cisplatin-induced AKI is unknown. In this study, wild-type mice were treated with cisplatin (30 mg/kg) or vehicle, and the effects on kidney DN T cell numbers and function were measured. In vitro experiments evaluated effects of kidney DN T cells on cisplatin-induced apoptosis and PD ligand 1 (PD-L1) in renal epithelial cells. Adoptive transfer experiments assessed the therapeutic potential of DN T cells during cisplatin-induced AKI. Our results show that kidney DN T cell population increased at 24 h and declined by 72 h after cisplatin treatment. Cisplatin treatment increased kidney DN T cell proliferation, apoptosis, CD69, and IL-10 expression, whereas CD62L, CD44, IL-17A, interferon-γ, and TNF-α were downregulated. Cisplatin treatment decreased both PD-1 and natural killer 1.1 subsets of kidney DN T cells with a pronounced effect on the PD-1 subset. In vitro kidney DN T cell coculture decreased cisplatin-induced apoptosis in kidney proximal tubular epithelial cells, increased Bcl-2, and decreased cleaved caspase 3 expression. Cisplatin-induced expression of PD ligand 1 was reduced in proximal tubular epithelial cells cocultured with DN T cells. Adoptive transfer of DN T cells attenuated kidney dysfunction and structural damage from cisplatin-induced AKI. These results demonstrate that kidney DN T cells respond rapidly and play a protective role during cisplatin-induced AKI.
Asunto(s)
Lesión Renal Aguda/prevención & control , Traslado Adoptivo , Apoptosis , Cisplatino , Células Epiteliales/inmunología , Túbulos Renales Proximales/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/trasplante , Lesión Renal Aguda/inducido químicamente , Lesión Renal Aguda/inmunología , Lesión Renal Aguda/patología , Animales , Antígeno B7-H1/inmunología , Proliferación Celular , Células Cultivadas , Técnicas de Cocultivo , Modelos Animales de Enfermedad , Células Epiteliales/patología , Túbulos Renales Proximales/patología , Masculino , Ratones Endogámicos C57BL , Fenotipo , Subgrupos de Linfocitos T/inmunologíaRESUMEN
BACKGROUND: Dyslipidemia causes renal damage; however, the detailed molecular mechanism has not been clarified. It is known that carnitine palmitoyl transferase 1-a (CPT1a) gene encodes an enzyme involved in fatty acid oxidation and, therefore, lipid content. In the present study, we investigated whether the accumulation of lipids induced by 7-ketocholesterol (7-KC) in tubular epithelial cells produce a fibrotic and inflammatory response through CPT1a. METHODS: Using an epithelial cell line, NRK-52E, we determine if intracellular accumulation of 7-KC modulates profibrotic and inflammatory events through CPT1a gene expression. In addition, the direct effects of CPT1a genetic modification has been studied. RESULTS: Our results revealed that high levels of 7-KC induce increased expression of CPT1a, TGF-ß1, α- SMA and NLRP3 that was correlated with lipid content. GW3965 treatment, which have shown to facilitate the efflux of cholesterol, eliminated the intracellular lipid droplets of 7-KC laden cells and decreased the expression of CPT1a, TGF-ß1, α- SMA and NLRP3. Furthermore, CPT1a Knockdown and C75 pre-treatment increased lipid content but decreased TGF-ß1, α- SMA and NLRP3. CONCLUSIONS: Our findings reveal that the profibrotic effect of 7-KC on renal epithelial cells are mediated by CPT1a overexpression, which acts on TGF-ß1, α-SMA and NLRP3. Thus, CPT1a downregulation protects against 7-KC-induced fibrosis in tubular epithelial cells by downregulating TGF-ß1, α- SMA and NLRP3.
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Carnitina O-Palmitoiltransferasa/metabolismo , Regulación hacia Abajo , Células Epiteliales/patología , Inflamasomas/metabolismo , Túbulos Renales Proximales/patología , Factor de Crecimiento Transformador beta1/metabolismo , Animales , Benzoatos/farmacología , Bencilaminas/farmacología , Línea Celular , Regulación hacia Abajo/efectos de los fármacos , Células Epiteliales/efectos de los fármacos , Fibrosis , Furanos/farmacología , Cetocolesteroles , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , RatasRESUMEN
Uropathogenic Escherichia coli (UPEC) are the primary cause of urinary tract infections (UTIs) in humans. P-fimbriae are key players for bacterial adherence to the uroepithelium through the Galα1-4Gal-binding PapG adhesin. The three identified classes I, II and III of PapG are supposed to adhere differently to host cell glycosphingolipids (GSLs) of the uroepithelial tract harboring a distal or internal Galα1-4Gal sequence. In this study, GSL binding characteristics were obtained in a nonradioactive adhesion assay using biotinylated E. coli UTI and urine isolates combined with enzyme-linked NeutrAvidin for detection. Initial experiments with reference globotriaosylceramide (Gb3Cer, Galα1-4Galß1-4Glcß1-1Cer), globotetraosylceramide (Gb4Cer, GalNAcß1-3Galα1-4Galß1-4Glcß1-1Cer) and Forssman GSL (GalNAcα1-3GalNAcß1-3Galα1-4Galß1-4Glcß1-1Cer) revealed balanced adhesion toward the three GSLs for PapG I-mediated attachment. In contrast, E. coli carrying PapG II or PapG III increasingly adhered to growing oligosaccharide chain lengths of Gb3Cer, Gb4Cer and Forssman GSL. Binding studies with GSLs from human A498 kidney and human T24 bladder epithelial cells, both being negative for the Forssman GSL, revealed the less abundant Gb4Cer vs. Gb3Cer as the prevalent receptor in A498 cells of E. coli expressing PapG II or PapG III. On the other hand, T24 cells exhibited a higher relative content of Gb4Cer vs. Gb3Cer alongside dominant binding of PapG II- or PapG III-harboring E. coli toward Gb4Cer and vastly lowered attachment to minor Gb3Cer. Further studies on PapG-mediated interaction with cell surface-exposed GSLs will improve our knowledge on the molecular mechanisms of P-fimbriae-mediated adhesion and may contribute to the development of antiadhesion therapeutics to combat UTIs.
Asunto(s)
Adhesinas de Escherichia coli/metabolismo , Células Epiteliales/metabolismo , Escherichia coli/metabolismo , Proteínas Fimbrias/metabolismo , Glicoesfingolípidos/metabolismo , Riñón/metabolismo , Vejiga Urinaria/metabolismo , Adhesinas de Escherichia coli/química , Sitios de Unión , Células Cultivadas , Células Epiteliales/química , Escherichia coli/química , Proteínas Fimbrias/química , Glicoesfingolípidos/química , Humanos , Riñón/microbiología , Vejiga Urinaria/microbiologíaRESUMEN
BACKGROUND & AIMS: The organic solute transporter α-ß (OSTα-OSTß) mainly facilitates transport of bile acids across the basolateral membrane of ileal enterocytes. Therefore, inhibition of OSTα-OSTß might have similar beneficial metabolic effects as intestine-specific agonists of the major nuclear receptor for bile acids, the farnesoid X receptor (FXR). However, no OSTα-OSTß inhibitors have yet been identified. METHODS: Here, we developed a screen to identify specific inhibitors of OSTα-OSTß using a genetically encoded Förster Resonance Energy Transfer (FRET)-bile acid sensor that enables rapid visualization of bile acid efflux in living cells. RESULTS: As proof of concept, we screened 1280 Food and Drug Administration-approved drugs of the Prestwick chemical library. Clofazimine was the most specific hit for OSTα-OSTß and reduced transcellular transport of taurocholate across Madin-Darby canine kidney epithelial cell monolayers expressing apical sodium bile acid transporter and OSTα-OSTß in a dose-dependent manner. Moreover, pharmacologic inhibition of OSTα-OSTß also moderately increased intracellular taurocholate levels and increased activation of intestinal FXR target genes. Oral administration of clofazimine in mice (transiently) increased intestinal FXR target gene expression, confirming OSTα-OSTß inhibition in vivo. CONCLUSIONS: This study identifies clofazimine as an inhibitor of OSTα-OSTß in vitro and in vivo, validates OSTα-OSTß as a drug target to enhance intestinal bile acid signaling, and confirmed the applicability of the Förster Resonance Energy Transfer-bile acid sensor to screen for inhibitors of bile acid efflux pathways.
RESUMEN
Isochoric (constant volume) freezing has been recently suggested as a new method for cell and organ preservation. As a first step in studying the effect of isochoric freezing on mammalian cells, Madin-Darby canine kidney epithelial cells (MDCK), were frozen in an isochoric system, in a simple extracellular phosphate buffered solution to -10 °C (96.5â¯MPa), - 15 °C (162â¯MPa) and -20 °C (205â¯MPa) for 60 and 120â¯min. Cell membrane integrity and cell metabolism were studied with a Live/Dead cell vitality assay and flow cytometry. We found that cell survival decreases with an increase in pressure (lower temperatures) and time of exposure. For example, 60% of cells survived 60â¯min at - 10 °C and only 18% survived 120â¯min at this temperature. Negligible survival was measured at - 20 °C. This study may serve as the baseline towards further research on techniques to optimize the effects of isochoric freezing on living biological matter.
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Frío/efectos adversos , Criopreservación/métodos , Crioprotectores/farmacología , Congelación/efectos adversos , Preservación de Órganos/métodos , Animales , Tampones (Química) , Línea Celular , Membrana Celular/fisiología , Supervivencia Celular/fisiología , Perros , Células de Riñón Canino Madin Darby , Fosfatos/químicaRESUMEN
Increasing incidence of renal pathology in the western world calls for innovative research for the development of cell-based therapies such as a bioartificial kidney (BAK) device. To fulfil the multitude of kidney functions, the core component of the BAK is a living membrane consisting of a tight kidney cell monolayer with preserved functional organic ion transporters cultured on a polymeric membrane surface. This membrane, on one side, is in contact with blood and therefore should have excellent blood compatibility, whereas the other side should facilitate functional monolayer formation. This work investigated the effect of membrane chemistry and surface topography on kidney epithelial cells to improve the formation of a functional monolayer. To achieve this, microtopographies were fabricated with high resolution and reproducibility on polystyrene films and on polyethersulfone-polyvinyl pyrrolidone (PES-PVP) porous membranes. A conditionally immortalized proximal tubule epithelial cell line (ciPTEC) was cultured on both, and subsequently, the cell morphology and monolayer formation were assessed. Our results showed that L-dopamine coating of the PES-PVP was sufficient to support ciPTEC monolayer formation. The polystyrene topographies with large features were able to align the cells in various patterns without significantly disruption of monolayer formation; however, the PES-PVP topographies with large features disrupted the monolayer. In contrast, the PES-PVP membranes with small features and with large spacing supported well the ciPTEC monolayer formation. In addition, the topographical PES-PVP membranes were compatible as a substrate membrane to measure organic cation transporter activity in Transwell® systems. Copyright © 2016 John Wiley & Sons, Ltd.
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Materiales Biocompatibles/farmacología , Células Epiteliales/citología , Riñón/citología , Animales , Transporte Biológico/efectos de los fármacos , Línea Celular , Creatinina/metabolismo , Células Epiteliales/efectos de los fármacos , Células Epiteliales/ultraestructura , Humanos , Membranas Artificiales , Polímeros/farmacología , Porosidad , Povidona/farmacología , Sulfonas/farmacologíaRESUMEN
Tumor suppressor genes and their effector pathways have been identified for many dominantly heritable cancers, enabling efforts to intervene early in the course of disease. Our approach on the subject of early intervention was to investigate gene expression patterns of morphologically normal "one-hit" cells before they become hemizygous or homozygous for the inherited mutant gene which is usually required for tumor formation. Here, we studied histologically non-transformed renal epithelial cells from patients with inherited disorders that predispose to renal tumors, including von Hippel-Lindau (VHL) disease and Tuberous Sclerosis (TSC). As controls, we studied histologically normal cells from non-cancerous renal epithelium of patients with sporadic clear cell renal cell carcinoma (ccRCC). Gene expression analyses of VHLmut/wt or TSC1/2mut/wt versus wild-type (WT) cells revealed transcriptomic alterations previously implicated in the transition to precancerous renal lesions. For example, the gene expression changes in VHLmut/wt cells were consistent with activation of the hypoxia response, associated, in part, with the "Warburg effect". Knockdown of any remaining VHL mRNA using shRNA induced secondary expression changes, such as activation of NFκB and interferon pathways, that are fundamentally important in the development of RCC. We posit that this is a general pattern of hereditary cancer predisposition, wherein haploinsufficiency for VHL or TSC1/2, or potentially other tumor susceptibility genes, is sufficient to promote development of early lesions, while cancer results from inactivation of the remaining normal allele. The gene expression changes identified here are related to the metabolic basis of renal cancer and may constitute suitable targets for early intervention.
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Proteínas de Unión al Calcio/genética , Predisposición Genética a la Enfermedad/genética , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/genética , Carcinoma de Células Renales/genética , Línea Celular Tumoral , Perfilación de la Expresión Génica , Técnicas de Silenciamiento del Gen , Haploinsuficiencia , Heterocigoto , Humanos , Immunoblotting , Neoplasias Renales/genética , Mutación , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena en Tiempo Real de la Polimerasa , TranscriptomaRESUMEN
A prerequisite for tissue electrolyte homeostasis is highly regulated ion and water transport through kidney or intestinal epithelia. In the present work, we monitored changes in the cell and luminal volumes of type II Madin-Darby canine kidney (MDCK) cells grown in a 3D environment in response to drugs, or to changes in the composition of the basal extracellular fluid. Using fluorescent markers and high-resolution spinning disc confocal microscopy, we could show that lack of sodium and potassium ions in the basal fluid (tetramethylammonium chloride (TMACl) buffer) induces a rapid increase in the cell and luminal volumes. This transepithelial water flow could be regulated by inhibitors and agonists of chloride channels. Hence, the driving force for the transepithelial water flow is chloride secretion, stimulated by hyperpolarization. Chloride ion depletion of the basal fluid (using sodium gluconate buffer) induces a strong reduction in the lumen size, indicating reabsorption of water from the lumen to the basal side. Lumen size also decreased following depolarization of the cell interior by rendering the membrane permeable to potassium. Hence, MDCK cells are capable of both absorption and secretion of chloride ions and water; negative potential within the lumen supports secretion, while depolarizing conditions promote reabsorption.
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Transporte Biológico/fisiología , Cloruros/fisiología , Potasio/fisiología , Reabsorción Renal/fisiología , Sodio/fisiología , Agua/fisiología , Animales , Benzoatos/farmacología , Transporte Biológico/efectos de los fármacos , Células Cultivadas , Agonistas de los Canales de Cloruro/farmacología , Canales de Cloruro/antagonistas & inhibidores , Canales de Cloruro/fisiología , Colforsina/farmacología , Perros , Lubiprostona/farmacología , Células de Riñón Canino Madin Darby , Potenciales de la Membrana/fisiología , Microscopía Confocal , Nigericina/farmacología , Tiazolidinas/farmacología , Fijación del TejidoRESUMEN
BACKGROUND: Transcription factor Nrf2 protects from experimental acute kidney injury (AKI) and is promising to limit progression in human chronic kidney disease (CKD) by upregulating multiple antioxidant genes. We recently demonstrated that deletion of Keap1, the endogenous inhibitor of Nrf2, in T lymphocytes significantly protects from AKI. In this study, we investigated the effect of Keap1 deletion on Nrf2 mediated antioxidant response in the renal tubular epithelial cells. METHODS: We deleted Keap1 exon 2 and 3 in the renal tubular epithelial cells by crossing Ksp-Cre mice with Keap1 floxed (Keap1 (f/f)) mice. Deletion of Keap1 gene in the kidney epithelial cells of Ksp-Keap1 (-/-) mice and its effect on Nrf2 target gene expression was performed using PCR and real-time PCR respectively. Histological evaluation was performed on H&E stained sections. Complete blood count, serum and urine analysis were performed to assess systemic effects of defective kidney development. Student's T test was used to determine statistical difference between the groups. RESULTS: Ksp-Cre resulted in the deletion of Keap1 exon 2 and 3 and subsequent upregulation of Nrf2 target genes, Nqo1, Gclm and Gclc in the kidney epithelial cells of Ksp-Keap1 (-/-) mice at baseline. Renal epithelial cell specific deletion of Keap1 in Ksp-Keap1 (-/-) mice caused marked renal pelvic expansion and significant compression of medullary parenchyma consistent with hydronephrosis in both (3 month-old) males and females. Kidneys from 6 month-old Ksp-Keap1 (-/-) mice showed progressive hydronephrosis. Hematological, biochemical and urinary analysis showed significantly higher red blood cell count (p = 0.04), hemoglobin (p = 0.01), hematocrit (p = 0.02), mean cell volume (p = 0.02) and mean cell hemoglobin concentration (p = 0.003) in Ksp-Keap1 (-/-) mice in comparison to Keap1 (f/f) mice. CONCLUSIONS: These unexpected findings demonstrate that Keap1 deletion in renal tubular epithelial cells results in an abnormal kidney development consistent with hydronephrosis and reveals a novel Keap1 mediated signaling pathway in renal development.
Asunto(s)
Epitelio/metabolismo , Hidronefrosis/genética , Hidronefrosis/metabolismo , Proteína 1 Asociada A ECH Tipo Kelch/deficiencia , Proteína 1 Asociada A ECH Tipo Kelch/genética , Riñón/metabolismo , Animales , Eliminación de Gen , Hidronefrosis/patología , Riñón/crecimiento & desarrollo , Riñón/patología , Masculino , Ratones , Ratones Noqueados , Ratones TransgénicosRESUMEN
The threat posed by the 2009 pandemic H1N1 virus emphasized the need for new influenza A virus vaccines inducing a broad cross-protective immune response for use in both humans and pigs. An effective and broad influenza vaccine for pigs would greatly benefit the pork industry and contribute to public health by diminishing the risk of emerging highly pathogenic reassortants. Current inactivated protein vaccines against swine influenza produce only short-lived immunity and have no efficacy against heterologous strains. DNA vaccines are a potential alternative with advantages such as the induction of cellular and humoral immunity, inherent safety and rapid production time. We have previously developed a DNA vaccine encoding selected influenza proteins of pandemic origin and demonstrated broad protective immune responses in ferrets and pigs. In this study, we evaluated our DNA vaccine expressed by next-generation vectors. These new vectors can improve gene expression, but they are also efficiently produced on large scales and comply with regulatory guidelines by avoiding antibiotic resistance genes. In addition, a new needle-free delivery of the vaccine, convenient for mass vaccinations, was compared with intradermal needle injection followed by electroporation. We report that when our DNA vaccine is expressed by the new vectors and delivered to the skin with the needle-free device in the rabbit model, it can elicit an antibody response with the same titers as a conventional vector with intradermal electroporation. The needle-free delivery is already in use for traditional protein vaccines in pigs but should be considered as a practical alternative for the mass administration of broadly protective influenza DNA vaccines.
Asunto(s)
Virus de la Influenza A/inmunología , Gripe Humana/prevención & control , Infecciones por Orthomyxoviridae/veterinaria , Enfermedades de los Porcinos/prevención & control , Vacunas de ADN/inmunología , Administración Cutánea , Animales , Anticuerpos Antivirales/sangre , Humanos , Virus de la Influenza A/genética , Infecciones por Orthomyxoviridae/prevención & control , Conejos , Porcinos , Vacunas de ADN/administración & dosificación , Vacunas de ADN/genéticaRESUMEN
BACKGROUND: Nephrotoxicity is one of the known side effects of methotrexate (MTX) therapy despite the use of conventional protective measures. Our objectives were to evaluate the effects of N-acetylcysteine (NAC) on MTX-induced toxicity in renal tubular cells and to evaluate whether adjunctive use of NAC interferes with MTX antitumor activity in the B-cell lymphoma. METHODS: Kidney Epithelial (Madin-Darby canine kidney [MDCK]) cells were exposed to MTX (10 µM or 100 µM) alone and with NAC (0.2 mM or 0.4 mM). Reactive oxygen species (ROS) generation at 1, 2, 4, and 24 h was measured by flow cytometer. Quantification of total glutathione (GSH) was performed by using GSH assay kit. To measure the impact of NAC on the antitumor activity of MTX, B lymphoma cells were exposed to MTX alone and with NAC. A percentage of apoptosis was measured using fluorescein isothiocyanate in both cell lines. Quantitative data was presented as a means ± standard deviation, and P values were analyzed using the Student's t-test. RESULTS: Apoptosis in MDCK cells were observed after 24 h of incubation with both 10 µM and 100 µM MTX. Maximum ROS generation was observed at 4 h and corresponded to GSH production. Treatment with 0.2 and 0.4 mM of NAC led to decrease percentages of apoptotic MDCK cells. NAC did not change either proliferation or apoptosis of B-cell lymphoma. CONCLUSION: Using NAC for kidney protection may not interfere with the antitumor activity of MTX. Further in vivo studies are warranted to confirm noninterference between MTX and NAC and assess synergistic antitumor effects.
RESUMEN
In addition to its role in regulation of salt transport in the kidney, the mineralocorticoid hormone aldosterone plays an independent role as a mediator of kidney injury and progression of chronic kidney disease. Studies in both animal models and patients have shown that aldosterone enhances the accumulation of extracellular matrix and progression of fibrosis in the kidney. However, the cellular mechanisms that lead to aldosterone-dependent fibrogenesis are poorly understood. In this study we find that aldosterone stimulates fibronectin synthesis through mineralocorticoid receptor (MCR) dependent activation of the c-Jun NH2-terminal protein kinase (JNK) and subsequent phosphorylation of the AP1 transcription factor c-jun, which forms a nuclear complex with the mineralocorticoid receptor in a kidney fibroblast cell line (NRK 49f). Furthermore, MCR-independent phosphorylation of Src family kinase induces IgF1 receptor phosphorylation, which leads to stimulation of the extracellular signal-regulated kinase (ERK1/2) to enhanced fibronectin synthesis. We further find that the IgF1-R-dependent signaling pathway activates fibronectin expression faster than the MCR-dependent pathway. We propose that the mechanisms described in this study are important to aldosterone-dependent progression of interstitial fibrosis in the kidney. Due to the duality of aldosterone-dependent activation of fibronectin synthesis in kidney fibroblasts, MCR-specific inhibitors may not entirely prevent the progression of fibrosis by aldosterone in the kidney.