Disruption of cyclooxygenase-2 prevents downregulation of cortical AQP2 and AQP3 in response to bilateral ureteral obstruction in the mouse

Self Cite

Bilateral ureteral obstruction (BUO) is associated with renal damage and impaired ability to concentrate urine and is known to induce alterations in an array of kidney proteins. The aim of this study was to identify acute proteomic alterations induced by BUO. Rats were subjected to BUO for 2, 6, or 24 h. Mass spectrometry-based proteomics was performed on the renal inner medulla, and protein changes in the obstructed group were identified. Significant changes were successfully identified for 109 proteins belonging to different biological classes. Interestingly, proteins belonging to the cytoskeleton and proteins related to cytoskeletal regulation were found to be biologically enriched in BUO using online-accessible tools. Western blots confirmed the selected results, demonstrating acute downregulation of proteins belonging to all three cytoskeletal components. The microfilament protein β-actin and the intermediate filament proteins pankeratin and vimentin were all downregulated. β-Tubulin, an important microtubular protein, was found to be significantly downregulated after 24 h. Also, there was significant upregulation of cofilin, an actin-binding protein known to be upregulated in other nephropathy models. Furthermore, both upregulation and downregulation of cytoskeletal motor and regulatory proteins were observed. These findings were confirmed by immunohistochemistry, which clearly showed alterations in labeling in the inner medulla. Interestingly, we were able to confirm selected results in mpkCCD cells exposed to mechanical stretch. Our findings add to the knowledge of BUO-induced acute changes in the renal cytoskeleton and suggest that these molecular changes are partly mediated by increased stretch of the cells during obstruction.

Section: Discussionsupporting

confidence: 47%

Proteomic identification of early changes in the renal cytoskeleton in obstructive uropathy

Stødkilde

Palmfeldt

Nilsson

et al. 2014

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“…The mechanisms underlying the concentrating defects and polyuria in these pathological conditions are incompletely understood, but may involve effects on tubular solute and water transporters, as well as hemodynamic effects. A COX-2-dependent downregulation of AQP-2 in the collecting duct and suppression of NKCC2 in the thick ascending limb have been implicated in postobstructive polyuria (33,34). Interestingly, lithium-induced nephrogenic diabetes insipidus is also associated with COX-2-mediated dysregulation of AQP-2 in the collecting duct (12), but whether IL-1␤ levels are increased in this condition appears to be unknown.…”

Section: Discussionmentioning

confidence: 99%

Chronic elevation of IL-1β induces diuresis via a cyclooxygenase 2-mediated mechanism

Boesen

2013

Chronic renal inflammation is an increasingly recognized phenomenon in multiple disease states, but the impact of specific cytokines on renal function is unclear. Previously, we found that 14-day interleukin-1β (IL-1β) infusion increased urine flow in mice. To determine the mechanism by which this occurs, the current study tested the possible involvement of three classical prodiuretic pathways. Chronic IL-1β infusion significantly increased urine flow (6.5 ± 1 ml/day at day 14 vs. 2.3 ± 0.3 ml/day in vehicle group; P < 0.05) and expression of cyclooxygenase (COX)-2, all three nitric oxide synthase (NOS) isoforms, and endothelin (ET)-1 in the kidney (P < 0.05 in all cases). Urinary prostaglandin E metabolite (PGEM) excretion was also significantly increased at day 14 of IL-1β infusion (1.21 ± 0.26 vs. 0.29 ± 0.06 ng/day in vehicle-infused mice; P = 0.001). The selective COX-2 inhibitor celecoxib markedly attenuated urinary PGEM excretion and abolished the diuretic response to chronic IL-1β infusion. In contrast, deletion of NOS3, or inhibition of NOS1 with L-VNIO, did not blunt the diuretic effect of IL-1β, nor did pharmacological blockade of endothelin ETA and ETB receptors with A-182086. Consistent with a primary effect on water transport, IL-1β infusion markedly reduced inner medullary aquaporin-2 expression (P < 0.05) and did not alter urinary Na⁺ or K⁺ excretion. These data indicate a critical role for COX-2 in mediating the effects of chronic IL-1β elevation on the kidney.

“…Fixed kidneys were then dehydrated, embedded in paraffin, and cut into 2-m slices on a rotary microtome. Labeling and antigen exposure were performed as previously described by Nilsson et al (25) using COX-2 antibodies.…”

Section: Methodsmentioning

confidence: 99%

Quercetin attenuates cyclooxygenase-2 expression in response to acute ureteral obstruction

Carlsen

Frøkiær

Nørregaard

2015

Self Cite

Unilateral ureteral obstruction (UUO) is associated with increased hydrostatic pressure, inflammation, and oxidative stress in the renal parenchyma. Previous studies have demonstrated marked cyclooxygenase (COX)-2 induction in renal medullary interstitial cells (RMICs) in response to UUO. The aim of the present study was to evaluate the effect of quercetin, a naturally occurring antioxidant, on COX-2 induction in vivo and in vitro. Rats subjected to 24 h of UUO were treated intraperitoneally with quercetin (50 mg·kg(-1)·day(-1)). Quercetin partly prevented COX-2 induction in the renal inner medulla in response to UUO. Moreover, RMICs exposed to conditions associated with obstruction, inflammation (produced by IL-1β), oxidative stress (produced by H2O2), and mechanical stress (produced by stretch) showed increased COX-2 expression. Interestingly, quercetin reduced COX-2 induction in RMICs subjected to stretched. Similarly, PGE2 production was markedly increased in RMICs exposed to stretch and was reversed to control levels by quercetin treatment. Furthermore, stretch-induced phosphorylation of ERK1/2 was blocked by quercetin, and inhibition of ERK1/2 attenuated stretch-induced COX-2 induction in RMICs. These results indicate that quercetin attenuated the induction of COX-2 expression and activity in RMICs exposed to mechanical stress as a consequence of acute UUO and that the MAPK ERK1/2 pathway might be involved in this quercetin-mediated reduction in COX-2.