Enhanced Renal Afferent Arteriolar Reactive Oxygen Species and Contractility to Endothelin-1 Are Associated with Canonical Wnt Signaling in Diabetic Mice

Abstract

Background/Aims: Canonical Wnt signaling is involved in oxidative stress, vasculopathy and diabetes mellitus but its role in diabetic renal microvascular dysfunction is unclear. We tested the hypothesis that enhanced canonical Wnt signaling in renal afferent arterioles from diabetic mice increases reactive oxygen species (ROS) and contractions to endothelin-1 (ET-1). Methods: Streptozotocin-induced diabetes or control C57Bl/6 mice received vehicle or sulindac (40 mg·kg^-1·day^-1) to block Wnt signaling for 4 weeks. ET-1 contractions were measured by changes of afferent arteriolar diameter. Arteriolar H₂O₂, O₂ ^-, protein expression and enzymatic activity were assessed using sensitive fluorescence probes, immunoblotting and colorimetric assay separately. Results: Compared to control, diabetic mouse afferent arteriole had increased O₂^- (+ 84%) and H₂O₂ (+ 91%) and enhanced responses to ET-1 at 10^-8 mol·l^-1 (-72±4% of versus -43±4%, P< 0.05) accompanied by reduced protein expressions and activities for catalase and superoxide dismutase 2 (SOD2). Arteriolar O₂ ^- was increased further by ET-1 and contractions to ET-1 reduced by PEG-SOD in both groups whereas H₂O₂ unchanged by ET-1 and contractions were reduced by PEG-catalase selectively in diabetic mice. The Wnt signaling protein β-catenin was upregulated (3.3-fold decrease in p-β-catenin/β-catenin) while the glycogen synthase kinase-3β (GSK-3β) was downregulated (2.6-fold increase in p-GSK-3β/ GSK-3β) in preglomerular vessels of diabetic mice. Sulindac normalized the Wnt signaling proteins, arteriolar O₂ ^-, H₂O₂ and ET-1 contractions while doubling microvascular catalase and SOD2 expression in diabetic mice. Conclusion: Increased ROS, notably H₂O₂ contributes to enhanced afferent arteriolar responses to ET-1 in diabetes, which is closely associated with Wnt signaling. Antioxidant pharmacological strategies targeting Wnt signaling may improve vascular function in diabetic nephropathy.

microRNA-378a Regulates the Reactive Oxygen Species (ROS)/Phosphatidylinositol 3-Kinases (PI3K)/AKT Signaling Pathway in Human Lens Epithelial Cells and Cataract

“…An increase in ROS can influence cell signaling proteins and their functional consequences. In a previous study, signaling pathways were shown to be targeted by ROS, including NF-κB, MAPKs, PI3K/AKT, Wnt/β-catenin, and ion channel signaling [13,15,16]. To determine the role of PI3K/AKT signaling in cell proliferation and apoptosis of HLECs, we used the PI3K inhibitor, LY294002, to determine the effects on cell growth and apoptosis.…”

“…Changes in the ethidium to dihydroethidium (E: DHE) fluorescence ratio and 6-carboxy-2′,7′-dichlorodihydrofluorescein diacetate (C-H 2 DCFDA) (Sigma, St. Louis, MO, USA) were used for detection of superoxide (O 2 − ) and hydrogen peroxide (H 2 O 2 ), respectively, which were analyzed using standard assay kits, according to the manufacturer’s instructions [13,20]. The O 2 − and H 2 O 2 levels were presented as units or μmol per milligram of protein.…”

“…Aerobic metabolism requires oxygen, which can be associated with the generation of free radicals and reactive oxygen species (ROS) [12]. Superoxide (O 2 − ) and hydrogen peroxide (H 2 O 2 ) are major ROS that can impair cellular components [13]. An increase in oxidative stress is believed to be the underlying cause for many human diseases, including cataract, and antioxidants may be potential therapeutic strategies for cataract [14].…”

Oxidative Stress, Reductive Stress and Antioxidants in Vascular Pathogenesis and Aging

“…In afferent arterioles, NOX2-dependent superoxide formation contributes to the development of vasoconstriction elicited by angiotensin II [66]. Also, the endothelin-1-induced vasoconstriction in the renal microcirculation depends on superoxide, whose source is not yet determined [67,68]. Furthermore, sphingosine 1-phosphate-induced vasoconstrictions of afferent arterioles could be inhibited by the NOX inhibitor apocynin, suggesting that NOX-dependent superoxide formation contributes to this vasoconstriction [69].…”

Neuroprotection of Rodent and Human Retinal Ganglion Cells In Vitro/Ex Vivo by the Hybrid Small Molecule SA-2

“…and exogenous (vitamin C, vitamin E, carotenoids, etc.) antioxidants [ 10 , 11 , 12 ]. Oxidative damage also increases the release of cytochrome c from the mitochondria into the cytosol, which acts as the major initiator of the apoptotic signaling cascade [ 7 , 13 ].…”