Paraoxonase 2 decreases renal reactive oxygen species production, lowers blood pressure, and mediates dopamine D2 receptor-induced inhibition of NADPH oxidase

Abstract

The dopamine D2 receptor (D2R) regulates renal reactive oxygen species (ROS) production and impaired D2R function results in ROS-dependent hypertension. Paraoxonase 2 (PON2), which belongs to the paraoxonase gene family, is expressed in various tissues, acting to protect against cellular oxidative stress. We hypothesized that PON2 may be involved in preventing excessive renal ROS production and thus may contribute to maintenance of normal blood pressure. Moreover, the D2R may decrease ROS production, in part, through regulation of PON2. D2R co-localized with PON2 in the brush border of mouse renal proximal tubules. Renal PON2 protein was decreased (-33%±6%) in D2-/- relative to D2+/+ mice. The renal subcapsular infusion of PON2 siRNA decreased PON2 protein expression (-55%), increased renal oxidative stress (2.2-fold), associated with increased renal NADPH oxidase expression (Nox1: 1.9-fold; Nox2: 2.9-fold; and Nox4: 1.6-fold) and activity (1.9-fold), and elevated arterial blood pressure (systolic: 134±5 vs. 93±6 mmHg; diastolic: 97±4 vs. 65±7 mmHg; mean: 113±4 vs. 75±7 mmHg). To determine the relevance of the PON2 and D2R interaction in humans, we studied human renal proximal tubule cells. Both D2R and PON2 were found in non-lipid and lipid rafts and physically interacted with each other. Treatment of these cells with the D2R/D3R agonist quinpirole (1μM, 24h) decreased ROS production (-35%±6%), associated with decreased NADPH oxidase activity (-32%±3%) and expression of Nox2 (-41%±7%) and Nox4 (-47%±8%) protein, and increased expression of PON2 mRNA (2.1-fold) and protein (1.6-fold) at 24h. Silencing PON2 (siRNA, 10nM, 48 h) not only partially prevented the quinpiroleinduced decrease in ROS production by 36%, but also increased basal ROS production (1.3-fold) which was associated with an increase in NADPH oxidase activity (1.4-fold) and expression of Nox2 (2.1-fold) and Nox4 (1.8-fold) protein. Inhibition of NADPH oxidase with diphenylene iodonium (10 μM/30 min) inhibited the increase in ROS production caused by PON2 silencing. Our results suggest that renal PON2 is involved in the inhibition of renal NADPH oxidase activity and ROS production and contributes to the maintenance of normal blood pressure. PON2 is positively regulated by D2R and may, in part, mediate the inhibitory effect of renal D2R on NADPH oxidase activity and ROS production.

Sestrin2 Decreases Renal Oxidative Stress, Lowers Blood Pressure, and Mediates Dopamine D 2 Receptor–Induced Inhibition of Reactive Oxygen Species Production

“…Previous studies from our laboratory have shown that disruption of Drd2 (D 2 R −/− ) increases systolic and diastolic blood pressures that are associated with increased ROS production and oxidative stress in the kidney [12, 15, 26, 27]. To determine if sestrin2 is involved in these alterations, we first measured the renal protein expression of sestrin2 in D 2 R −/− and D 2 R +/+ mice.…”

“…The D 2 R decreases cellular oxidative stress in human RPTCs [15]. To determine whether or not sestrin2 is involved in the anti-oxidant effect of D 2 R, we treated human RPTCs with the D 2 R agonist quinpirole in the presence of siRNA targeting human sestrin2.…”

“…The method of the renal cortical silencing of the gene of interest was developed in our laboratory [15, 26–28]. C57BL/6 mice were purchased from the Jackson Laboratory (Bar Harbor, ME).…”

“…The renal activity of NADPH oxidase and the expression of Nox-1, Nox-2, and Nox-4 are increased in D 2 R −/− [12]. We have recently shown that renal PON2, a protein that possesses antioxidant properties [13–15] and is positively regulated by D 2 R, mediates, in part, the inhibitory effect of renal D 2 R on NADPH oxidase activity and ROS production [15], and contributes to the maintenance of normal blood pressure.…”

PON2 and ATP2B2 gene polymorphisms with noise-induced hearing loss

“…PON gene family consisting of at least 3 genes (PON1, PON2 and PON3) located in the long arm of human chromosome 7 (q21.3-22.1) coding for esterases (19). PON2 expressing in tissues throughout the body may develop its antioxidant effect at a cellular level (20), and its deficiency can increase ROS production, which led to the damage of cochlear hair cell (21). Some researchers have found that PON2 polymorphisms may be associated with diseases, such as ischemic stroke, diabetes, and Alzheimer's dementia (22)(23)(24).…”