cGMP decreases surface NKCC2 levels in the thick ascending limb: role of phosphodiesterase 2 (PDE2)

Ares, Gustavo; Caceres, Paulo; Álvarez-Leefmans, Francisco J.; Ortíz, Pablo

doi:10.1152/ajprenal.00449.2007

Cited by 43 publications

(97 citation statements)

References 40 publications

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“…Previous studies have reported that increases in cyclic guanosine monophosphate (cGMP) can decrease surface NKCC2 levels in the TALH acting through cGMP-stimulated phosphodiesterase 2. 23 Because HO-1 induction has been shown to increase cGMP levels through generation of CO, 24 it is possible that induction of HO-1 in TALH cells attenuates NKCC2 through CO-mediated increases in cGMP, resulting in increased degradation of the protein. However, measurement of NKCC2 protein in the apical membrane of the TALH in TALH-HHO1 mice by surface biotinylation was not determined and is needed to fully test this hypothesis.…”

Section: Discussionmentioning

confidence: 99%

Expression of Heme Oxygenase-1 in Thick Ascending Loop of Henle Attenuates Angiotensin II-Dependent Hypertension

Stec

Drummond

Gousette

et al. 2012

Journal of the American Society of Nephrology

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Kidney-specific induction of heme oxygenase-1 (HO-1) attenuates the development of angiotensin II (Ang II) -dependent hypertension, but the relative contribution of vascular versus tubular induction of HO-1 is unknown. To determine the specific contribution of thick ascending loop of Henle (TALH) -derived HO-1, we generated a transgenic mouse in which the uromodulin promoter controlled expression of human HO-1. Quantitative RT-PCR and confocal microscopy confirmed successful localization of the HO-1 transgene to TALH tubule segments. Medullary HO activity, but not cortical HO activity, was significantly higher in transgenic mice than control mice. Enhanced TALH HO-1 attenuated the hypertension induced by Ang II delivered by an osmotic minipump for 10 days (13963 versus 15362 mmHg in the transgenic and control mice, respectively; P,0.05). The lower blood pressure in transgenic mice associated with a 60% decrease in medullary NKCC2 transporter expression determined by Western blot. Transgenic mice also exhibited a 36% decrease in ouabain-sensitive sodium reabsorption and a significantly attenuated response to furosemide in isolated TALH segments,. In summary, these results show that increased levels of HO-1 in the TALH can lower blood pressure by a mechanism that may include alterations in NKCC2-dependent sodium reabsorption. Heme oxygenase (HO) is the rate-limiting enzyme in the catabolism of heme to biliverdin, during which both carbon monoxide (CO) gas and free iron are released. Biliverdin is then reduced to bilirubin by the ubiquitous enzyme biliverdin reductase. There are two major isoforms of HO that are responsible for the breakdown of heme, HO-1 and HO-2. HO-2 is the constitutively expressed isoform, whereas HO-1 is inducible by a wide variety of stimuli, including hypoxia, metals, ischemia, and oxidative stress. In the kidney, both isoforms of HO are present, with the highest level of expression of both isoforms in the renal medulla under basal conditions. 1,2 HO enzymes are not only expressed in the renal medulla, but their metabolites, CO and bilirubin, play an important role in the regulation of both renal vascular and tubular function. Renal medullary infusion of the general HO inhibitor, zinc deuteroporphyrin 2,4-bis glycol, results in a significant decrease in renal medullary blood flow. 1 In the renal tubules, increases in perfusion pressure increase CO levels, and inhibition of HO activity results in significant attenuation of pressure natriuresis and development of salt-sensitive hypertension. 3

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Section: Discussionmentioning

confidence: 99%

Expression of Heme Oxygenase-1 in Thick Ascending Loop of Henle Attenuates Angiotensin II-Dependent Hypertension

Stec

Drummond

Gousette

et al. 2012

Journal of the American Society of Nephrology

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“…THAL suspensions were also obtained from another group of HS and HS ϩ HCTZ-treated SS rats. Medullary THAL suspensions were prepared according to the method described previously (2,5,27). In brief, kidneys were perfused via the aorta with a perfusion solution (in mM: 130 NaCl, 2.5 NaH 2PO4, 4.0 KCl, 1.2 MgSO 4, 6 L-alanine, 1.0 disodium citrate, 5.5 glucose, 2.0 calcium lactate, and 10 HEPES, pH 7.4) containing 0.1% collagenase (Sigma, St. Louis, MO) and 100 U heparin.…”

Section: Methodsmentioning

confidence: 99%

“…Cell surface proteins were biotinylated as described in detail previously (2,5,27). THAL suspensions were equilibrated at 37°C for 20 min and oxygenated every 5 min with 100% O 2 with gentle mixing every 2 min.…”

Section: Methodsmentioning

confidence: 99%

“…Surface proteins were extracted from the beads by boiling in 50 l SDS-loading buffer containing 50 M DL-dithiothreitol and 5% ␤-mercaptoethanol as described in detail in our previous studies (2,5,27). For intracellular NKCC2 measurement, 10 g intracellular nonbiotinylated proteins were loaded on the same gels as the surface from each experiment.…”

Section: Methodsmentioning

confidence: 99%

“…However, to reabsorb Na and Cl from the tubule lumen, NKCC2 must be present at the apical surface. Recently, we showed that changes in the amount of NKCC2 at the apical membrane are necessary for the inhibition of NaCl absorption by cGMP [the second messenger of nitric oxide (NO)] and for stimulation by cAMP (the second messenger of arginine vasopressin) in normal rats (2,5,27). In addition, phosphorylation of NKCC2 at NH 2 -terminus threonines enhances cotransporter activity in heterologous expression systems (11,13,22,23,29) and arginine vasopressin enhances NH 2 -terminus phosphorylation and trafficking in mouse THALs (12).…”

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High salt differentially regulates surface NKCC2 expression in thick ascending limbs of Dahl salt-sensitive and salt-resistant rats

Haque

Ares

Caceres

et al. 2011

American Journal of Physiology-Renal Physiology

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Haque MZ, Ares GR, Caceres PS, Ortiz PA. High salt differentially regulates surface NKCC2 expression in thick ascending limbs of Dahl salt-sensitive and salt-resistant rats. Am J Physiol Renal Physiol 300: F1096 -F1104, 2011. First published February 9, 2011 doi:10.1152/ajprenal.00600.2010.-NaCl reabsorption by the thick ascending limb of the loop of Henle (THAL) occurs via the apical Na-K-2Cl cotransporter, NKCC2. Overall, NKCC2 activity and NaCl reabsorption are regulated by the amount of NKCC2 at the apical surface, and also by phosphorylation. Dahl salt-sensitive rats (SS) exhibit higher NaCl reabsorption by the THAL compared with Dahl salt-resistant rats (SR), and they become hypertensive during high-salt (HS) intake. However, the effect of HS on THAL transport, surface NKCC2 expression, and NKCC2 NH2-terminus phosphorylation has not been studied. We hypothesized that HS enhances surface NKCC2 and its phosphorylation in THALs from Dahl SS. THAL suspensions were obtained from a group of SS and SR rats on normal-salt (NS) or HS intake. In SR rats THAL NaCl transport measured as furosemide-sensitive oxygen consumption was decreased by HS (Ϫ34%, P Ͻ 0.05). In contrast, HS did not affect THAL transport in SS rats. As expected, HS increased systolic blood pressure only in SS rats (⌬ 23 Ϯ 2 mmHg, P Ͻ 0.002) but not in SR rats (⌬ 5 Ϯ 3 mmHg). We next tested the effect of HS intake on apical surface NKCC2 and its NH2-terminus threonine phosphorylation (P-NKCC2) in SS and SR rats. HS intake decreased surface NKCC2 by 15 Ϯ 2% (P Ͻ 0.03) in THALs from SR without affecting total NKCC2 or NH2-terminus P-NKCC2. In contrast, in SS rats HS intake increased surface NKCC2 by 54 Ϯ 6% (P Ͻ 0.01) without affecting total NKCC2 expression or P-NKCC2. We conclude that HS intake causes different effects on surface NKCC2 in SS and SR rats. Our data suggest that enhanced surface NKCC2 in SS rats might contribute to enhanced NaCl reabsorption in SS rats during HS intake. Na-K-2Cl cotransporter; nephron; salt-sensitive hypertension; trafficking ENHANCED BLOOD PRESSURE in Dahl salt-sensitive (SS) rats is in part related to a renal defect that prevents the kidney from appropriately excreting a salt load (18,19,21,30). However, little is known about the molecular mechanisms by which the various nephron segments decrease NaCl reabsorption during a heightened salt load in normal or hypertensive animals. Enhanced NaCl reabsorption by the thick ascending limb of the loop of Henle (THAL) may be involved in the development of hypertension in the SS rat (19,20,30,36). In vivo micropuncture experiments showed enhanced NaCl reabsorption along the loop of Henle of SS rats before and during high-salt (HS) intake (19,20,30,36). In addition, others showed enhanced Cl absorption in isolated, perfused THALs of SS rats (10,18,20,30,36). Despite data showing enhanced NaCl transport in the THAL, the regulation of individual transporters in this nephron segment has been poorly studied in SS rats.The THAL reabsorbs Ϸ30% of the filtered NaCl in a process medi...

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In VivoandEx VivoAnalysis of Tubule Function

Stockand

Vallon²,

Ortíz

2012

Comprehensive Physiology

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Analysis of tubule function with in vivo and ex vivo approaches has been instrumental in revealing renal physiology. This work allows assignment of functional significance to known gene products expressed along the nephron, primary of which are proteins involved in electrolyte transport and regulation of these transporters. Not only we have learned much about the key roles played by these transport proteins and their proper regulation in normal physiology but also the combination of contemporary molecular biology and molecular genetics with in vivo and ex vivo analysis opened a new era of discovery informative about the root causes of many renal diseases. The power of in vivo and ex vivo analysis of tubule function is that it preserves the native setting and control of the tubule and proteins within tubule cells enabling them to be investigated in a "real-life" environment with a high degree of precision. In vivo and ex vivo analysis of tubule function continues to provide a powerful experimental outlet for testing, evaluating, and understanding physiology in the context of the novel information provided by sequencing of the human genome and contemporary genetic screening. These tools will continue to be a mainstay in renal laboratories as this discovery process continues and as we continue to identify new gene products functionally compromised in renal disease.

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cGMP decreases surface NKCC2 levels in the thick ascending limb: role of phosphodiesterase 2 (PDE2)

Cited by 43 publications

References 40 publications

Expression of Heme Oxygenase-1 in Thick Ascending Loop of Henle Attenuates Angiotensin II-Dependent Hypertension

Expression of Heme Oxygenase-1 in Thick Ascending Loop of Henle Attenuates Angiotensin II-Dependent Hypertension

High salt differentially regulates surface NKCC2 expression in thick ascending limbs of Dahl salt-sensitive and salt-resistant rats

In VivoandEx VivoAnalysis of Tubule Function

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