Luminal flow induces eNOS activation and translocation in the rat thick ascending limb. II. Role of PI3-kinase and Hsp90

Ortíz, Pablo; Hong, Nancy J.; Garvin, Jeffrey L.

doi:10.1152/ajprenal.00383.2003

Cited by 40 publications

(43 citation statements)

References 62 publications

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“…Previous reports from this group, as well as the present study, implicate NOS3 translocation and phosphorylation 9 at different regulatory sites as important regulators of THAL NOS3 activity. In a recent study, Ortiz et al 33 showed that NOS3 is activated when it localizes to the apical membrane of the THAL. Whether changes in NOS3 phosphorylation and enzyme expression are cytosolic intermediates necessary for the trafficking process is still unknown.…”

Section: Discussionmentioning

confidence: 99%

“…Some of the proteins that interact with NOS have been localized to the kidney; 34 however, its role in the regulation of THAL NOS3 has not been thoroughly investigated except for the interaction between NOS3 and heat shock protein 90. 33 Our laboratory is currently attempting to establish which other components of this mechanism are involved in regulation of THAL NOS3 activity.…”

Section: Discussionmentioning

confidence: 99%

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A High-Salt Diet Dissociates NO Synthase-3 Expression and NO Production by the Thick Ascending Limb

2006

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Abstract-NO produced by endothelial NO synthase (NOS3) decreases sodium transport by the thick ascending limb (THAL). We found previously that 7 days of high salt (HS) increased THAL-NOS3 expression but not NO production. NOS3 phosphorylation regulates enzyme activity. We hypothesized that HS acutely increases NOS3 expression and NO production, and, over time, changes in NOS3 phosphorylation dissociate NO production from expression. NOS3 expression increased by 71Ϯ13%, 127Ϯ24%, and 69Ϯ16% at days 1, 3, and 7 of HS, respectively. At days 14 and 28, expression was back to normal salt. After 1 day of HS, NO production in response to 250 mol/L L-arginine was elevated by 146% and, by day 3, returned to normal salt. Similar increases were found in response to endothelin-1. Inhibitors of NOS1/2 did not blunt the salt-induced increase in NO. Phosphorylation at Thr 495 , an inhibitory site, decreased by 39Ϯ8% at day 1 of HS and then increased by 116Ϯ18% at day 3. Phosphorylation at Ser 633 and Ser 1177(stimulatory sites) decreased by Ϸ25% at day 1 and remained depressed at day 3. Superoxide production increased by 71% at day 1, decreased by 57% at day 3, and decreased by 55% at day 7. The NOS inhibitor L-N G -nitroarginine methyl ester did not alter superoxide levels at any time point. The addition of reduced nicotinamide-adenine dinucleotide phosphate and tetrahydrobiopterin had no effect on NO release after 3 days of HS. We conclude the following: (1) HS transiently increases NO production and NOS3 expression; (2) NOS3 expression and NO production are dissociated by HS; and (3) changes in phosphorylation explain how THAL NOS3 activity and expression are dissociated by HS. Key Words: nitric oxide synthase Ⅲ kidney Ⅲ phosphorylation N itric oxide (NO) produced by endothelial NO synthase (NOS3) in the thick ascending limb (THAL) inhibits THAL sodium reabsorption by inhibiting Na/K/2Cl cotransporter activity. 1 Seven days of a high-salt (HS) diet increased NOS3 expression in the THAL, 2 suggesting that this enzyme may be important in chronic adaptation to HS intake. HS heightens NOS3 expression in the THAL by increasing medullary osmolality, enhancing release of endothelin-1, and activating endothelin B receptors. 2,3 However, NO production was not increased after 7 days of HS. 4 There are at least 3 possible reasons for the lack of correlation between enzyme expression and NO production: (1) NO bioavailability may be reduced; (2) availability of cofactors may be limited; or (3) NOS3 activity may be suppressed by allosteric modifications, which may or may not induce NOS3 uncoupling. Because superoxide (O 2 Ϫ ) levels in the THAL are decreased by 33.8% at day 7 of a HS diet, 5 it does not appear likely that NO bioavailability is reduced. Similarly, whereas NO production by NOS can be limited by cofactor availability under some circumstances, this occurs primarily during rapid bursts of NO production accompanied by robust NOS expression in macrophages, 6 making it unlikely that a 2-to 3-fold increase in NOS3 expression and a...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A High-Salt Diet Dissociates NO Synthase-3 Expression and NO Production by the Thick Ascending Limb

2006

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“…Recently, activation and translocation of NOS 3 in the thick ascending limb have been reported to require heat shock protein 90 ATPase activity. 54 Phosphorylation of NOS 3 by protein kinase A was first reported in 2001. 55 However, not until NOS 3 activation by shear stress was shown to be mediated by phosphorylation of serine 1179 in endothelial cells 56 were the potential consequences appreciated.…”

Section: Regulation Of Nos Activitymentioning

confidence: 99%

Recent Advances in the Regulation of Nitric Oxide in the Kidney

Herrera

Garvin

2005

Hypertension

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Abstract-Nitric oxide (NO) plays important roles in the regulation of renal function and the long-term control of blood pressure. New roles of NO have been proposed recently in diabetes, nephrotoxicity, and pregnancy. NO derived from all 3 NOS isoforms contributes to the overall regulation of kidney function, and recent advances in our understanding of their regulation have been made lately. In this regard, substrate and cofactor availability play important roles in regulating nitric oxide synthase (NOS) activity not only by limiting enzyme activity but also by influencing the coupling of NOS with its cofactors, tetrahydrobiopterin and NADPH. Protein-protein interactions are now recognized to be important negative and positive regulators of NOS. Phosphorylation is another component of the mechanism whereby NOS is activated or deactivated. Increased NOS expression can also influence enzyme activity; however, the degree of expression does not always correlate with enzyme activity because increased NO levels can result in inhibition of NOS. Finally, other potential regulators of NOS such as endogenous L-arginine analogs may also be important. In this article, we summarize recent advances in the regulation of activity and expression of the NOS isoforms within the kidney. renal function and long-term regulation of blood pressure. [1][2][3][4] This is best evidenced by the fact that inhibiting intrarenal NO production increased blood pressure. 5 In addition, reduced NO has been identified as a common denominator of many hypertensive models. 6 -9 The effects of NO on blood pressure via actions in the kidney occur through multiple mechanisms. These include increasing renal blood flow caused by vasodilatation, 10 increasing glomerular filtration, 11 inhibiting sodium transport along the nephron, 12-14 and regulating release of renin. 15 NO produced by each of the 3 nitric oxide synthases (NOS), NOS 1, NOS 2, and NOS 3, reportedly contributes to the regulation of renal function. Inhibition of NOS activity within the kidney is known to lead to sodium retention and hypertension. This review addresses recent advances in our understanding of the role played by renal NO in various physiological and pathophysiological conditions, as well as how NO production is regulated. Roles for Renal NOHistorically, NO produced by the kidney has been thought of primarily as a factor that regulates urinary volume and sodium excretion. The physiological effects of NO can be mediated via changes in renal hemodynamics and/or salt and water absorption by the nephron. NO reduces renal vascular tone in part by dilating the afferent arteriole. 16 It also increases glomerular filtration rate. 11 NO modulates renin secretion by the juxtaglomerular apparatus 15 and tubuloglomerular feedback. 3 Finally, NO regulates transport in various nephron segments as reviewed recently by Ortiz and Garvin. 12 More recently it has been recognized that in a number of pathophysiological conditions, the actions of NO on renal hemodynamics and/or nephron transport are ...

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“…Thus, in the absence of exogenously added L-arginine, thick ascending limbs do not generate NO (25). Several factors stimulate NO production in this nephron segment, including angiotensin (5,35), ␣-2 adrenergic agonists (31,45), endothelin (13,32), and luminal flow (28,29). Once generated, NO activates soluble guanylate cyclase and forms cGMP (21).…”

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confidence: 99%

Nitric oxide reduces flow-induced superoxide production via cGMP-dependent protein kinase in thick ascending limbs

Hong

Garvin

2009

American Journal of Physiology-Renal Physiology

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Hong NJ, Garvin JL. Nitric oxide reduces flow-induced superoxide production via cGMP-dependent protein kinase in thick ascending limbs. Am J Physiol Renal Physiol 296: F1061-F1066, 2009. First published February 25, 2009 doi:10.1152/ajprenal.90707.2008.-We have shown that increased luminal flow induces O 2 Ϫ and nitric oxide (NO) production in thick ascending limbs (TALs). However, the interaction of flow-stimulated NO and O 2 Ϫ in TALs is unclear. We hypothesized that NO inhibits flow-induced O 2 Ϫ production in TALs via cGMPdependent protein kinase (PKG). We measured flow-stimulated O 2 Ϫ production in rat TALs using dihydroethidium in the absence and presence of L-arginine (0.3 mM), the substrate for NO synthase. The addition of L-arginine reduced flow-induced net O 2 Ϫ production from 68 Ϯ 9 to 17 Ϯ 4 AU/s (P Ͻ 0.002). The addition of the NO synthase inhibitor Ϫ from 39 Ϯ 9 to 7 Ϯ 3 AU/s (P Ͻ 0.03). The PKG inhibitor KT-5823 (5 M) partially restored flow-induced net O 2 Ϫ in the presence of L-arginine (L-arginine: 4 Ϯ 4 AU/s vs. L-arginine ϩ KT-5823: 32 Ϯ 9 AU/s; P Ͻ 0.03) and db-cGMP (db-cGMP: 9 Ϯ 7 AU/s vs. db-cGMP ϩ KT-5823: 54 Ϯ 5 AU/s; P Ͻ 0.01). Phosphodiesterase II inhibition had no effect on arginine-inhibited O 2 Ϫ production. We conclude that 1) NO reduces flow-stimulated O 2 Ϫ production, 2) this occurs primarily via the cGMP/PKG pathway, and 3) O 2 Ϫ scavenging by NO plays a minor role.reactive oxygen species; soluble guanylate cyclase; phosphodiesterase; scavenging NITRIC OXIDE (NO) and superoxide (O 2 Ϫ ) regulate kidney function, and consequently blood pressure. NO promotes natriuresis and diuresis, and therefore reductions in blood pressure. O 2

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Luminal flow induces eNOS activation and translocation in the rat thick ascending limb. II. Role of PI3-kinase and Hsp90

Cited by 40 publications

References 62 publications

A High-Salt Diet Dissociates NO Synthase-3 Expression and NO Production by the Thick Ascending Limb

A High-Salt Diet Dissociates NO Synthase-3 Expression and NO Production by the Thick Ascending Limb

Recent Advances in the Regulation of Nitric Oxide in the Kidney

Nitric oxide reduces flow-induced superoxide production via cGMP-dependent protein kinase in thick ascending limbs

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