Role of Renal DJ-1 in the Pathogenesis of Hypertension Associated With Increased Reactive Oxygen Species Production

Abstract

The D2 dopamine receptor (D2R) is important in the pathogenesis of essential hypertension. We have already reported that systemic deletion of the D2R gene in mice results in reactive oxygen species (ROS)-dependent hypertension, suggesting that the D2R has antioxidant effect. However, the mechanism of this effect is unknown. DJ-1 is a protein which has antioxidant properties. D2R and DJ-1 are expressed in the mouse kidney and colocalize and co-imunoprecipitate in mouse renal proximal tubule cells. We hypothesized that D2Rs regulate renal ROS production in the kidney through regulation of DJ-1 expression or function. Heterozygous D2+/− mice have increased blood pressure, urinary 8-isoprostanes, and renal Nox 4 expression, but decreased renal DJ-1 expression. Silencing D2R expression in mouse renal proximal tubule cells increases ROS production and decreases the expression of DJ-1. Conversely, treatment of these cells with a D2R agonist increases DJ-1 expression and decreases Nox 4 expression and NADPH oxidase activity, effects that are partially blocked by a D2R antagonist. Silencing DJ-1 expression in mouse renal proximal tubule cells increases ROS production and Nox 4 expression. Selective renal DJ-1 silencing by the subcapsular infusion of DJ-1 siRNA in mice increases blood pressure, and renal Nox 4 expression and NADPH oxidase activity. These results suggest that the inhibitory effects of D2R on renal ROS production are at least, in part, mediated by a positive regulation of DJ-1 expression/function and that DJ-1 may have a role in the prevention of hypertension associated with increased ROS production.

NADPH Oxidases, Reactive Oxygen Species, and the Kidney

“…In streptozotocin-treated mice, the Nox2 gene is upregulated in the kidneys. [42][43][44] Taken together, these data indicate that Nox2 may be involved in the development of renal oxidative stress during diabetes and, consequently, in the development of diabetic nephropathy.…”

Dopamine D2 receptor upregulates leptin and IL-6 in adipocytes

“…(selective D 2 R antagonist, Sigma-Aldrich), as previously described (14,15). Differentiated 3T3-L1 adipocytes were transfected with non-silencing siRNA (30 nM, Qiagen) or Drd2 siRNA (30 nM, Qiagen) using Hyperfect (Qiagen) and studied 72 h post-transfection.…”

“…Mouse kidney homogenates and cell lysates were subjected to immunoblotting, as previously described (14,15). The primary antibodies used were rabbit polyclonal anti-D 2 R (Millipore, #AB5084P), rabbit polyclonal antibodies against leptin (ABCAM, #ab9749), IL-6 (ABCAM, #ab6672), adiponectin (ABCAM, #ab22554), visfatin (BioVision, anti-mouse #5908-100), TNFα (ABCAM, #ab9739), OB receptor (Gene-Tex, Inc. GTX25593), and mouse monoclonal anti-GAPDH (glyceraldehyde-3-phosphate dehydrogenase) (Millipore,#MAB374).…”

The role of DJ-1/Nrf2 pathway in the pathogenesis of diabetic nephropathy in rats

“…3,4 Currently, evidence is emerging that DJ-1 is a multifunctional protein that has potent antioxidant properties and protects kidney against oxidative stress-induced cell injury. 5,6 Interestingly, the content of DJ-1 in glomerular mesangial cells induced by high glucose is relative to time nodes. 7 Studies demonstrated that DJ-1 protein is required for the stabilization of NF-E2-related factor-2 (Nrf2) and subsequent production of Nrf2-regulated enzymes.…”