angiotensinogen and diphenyleneiodonium

Reactive oxygen species (ROS) are produced during the interaction between oxalate/calcium oxalate monohydrate (COM) crystals and renal epithelial cells and are responsible for the various cellular responses through the activation of NADPH oxidase (Nox). Ox and COM also activate the renin-angiotensin-aldosterone system (RAAS). Aldosterone stimulates ROS production through activation of Nox with the involvement of mineralocorticoid receptor (MR), Rac1 and mitogen-activated protein kinases (MAPK). We investigated RAAS pathways in vivo in an animal model of hyperoxaluria and in vitro by exposing renal epithelial cells to COM crystals.. Hyperoxaluria was induced in male SD rats by administering ethylene glycol. One group of rats was additionally given spironolactone. Total RNA was extracted and subjected to genomic microarrays to obtain global transcriptome data. Normal rat kidney cell line (NRK-52E) was incubated with aldosterone(10(-7) M) and COM(67 μg/cm(2)) with or without spironolactone(10(-5) M), a selective inhibitor of SRC family of kinases; protein phosphatase 2(pp2) (10(-5) M) and Nox inhibitor; diphenylene iodonium (DPI) (10(-5) M).. Relative expression of genes encoding for AGT, angiotensin receptors 1b and 2, Renin 1, Cyp11b, HSD11B2, Nr3c2, NOx4 and Rac1 was upregulated in the kidneys of rats with hyperoxaluria. Treatment with spironolactone reversed the effect of hyperoxaluria. Both aldosterone and COM crystals activated Nox and Rac1 expression in NRK52E, while spironolactone inhibited Nox and Rac1 expression. Increased Rac1 expression was significantly attenuated by treatment with PP2 and spironolactone.. Results indicate that hyperoxaluria-induced production of ROS, injury and inflammation are in part associated with the activation of Nox through renin-angiotensin-aldosterone pathway.

Topics: 11-beta-Hydroxysteroid Dehydrogenase Type 2; Angiotensinogen; Animals; Calcium Oxalate; Cell Line; Cytochrome P-450 CYP11B2; Disease Models, Animal; Enzyme Inhibitors; Ethylene Glycol; Gene Expression Profiling; Hyperoxaluria; Male; Mineralocorticoid Receptor Antagonists; NADPH Oxidase 4; NADPH Oxidases; Onium Compounds; Protein Phosphatase 2; rac1 GTP-Binding Protein; Rats; Rats, Sprague-Dawley; Receptors, Angiotensin; Receptors, Mineralocorticoid; Renin; Renin-Angiotensin System; RNA, Messenger; Spironolactone; Steroid 11-beta-Hydroxylase

Decrease in endogenous hydrogen sulfide (H2S) was reported to participate in the pathogenesis of diabetic nephropathy (DN). This study is aimed at exploring the relationship between the abnormalities in H2S metabolism, hyperglycemia-induced oxidative stress and the activation of intrarenal renin-angiotensin system (RAS). Cultured renal mesangial cells (MCs) and streptozotocin (STZ) induced diabetic rats were used for the studies. The expressions of angiotensinogen (AGT), angiotensin converting enzyme (ACE), angiotensin II (Ang II) type I receptor (AT1), transforming growth factor-β1 (TGF-β1) and collagen IV were measured by real time PCR and Western blot. Reactive oxygen species (ROS) production was assessed by fluorescent probe assays. Cell proliferation was analyzed by 5'-bromo-2'-deoxyuridine incorporation assay. Ang II concentration was measured by an enzyme immunoassay. AGT, ACE and AT1 receptor mRNA levels and Ang II concentration were increased in high glucose (HG) -treated MCs, the cell proliferation rate and the production of TGF-β1 and of collagen IV productions were also increased. The NADPH oxidase inhibitor diphenylenechloride iodonium (DPI) was able to reverse the HG-induced RAS activation and the changes in cell proliferation and collagen synthesis. Supplementation of H2S attenuated HG-induced elevations in ROS and RAS activation. Blockade on H2S biosynthesis from cystathione-γ-lyase (CSE) by DL-propargylglycine (PPG) resulted in effects similar to that of HG treatment. In STZ-induced diabetic rats, the changes in RAS were also reversed by H2S supplementation without affecting blood glucose concentration. These data suggested that the decrease in H2S under hyperglycemic condition leads to an imbalance between oxidative and reductive species. The increased oxidative species results in intrarenal RAS activation, which, in turn, contributes to the pathogenesis of renal dysfunction.

Topics: Acetophenones; Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Blood Glucose; Cell Proliferation; Cells, Cultured; Collagen Type IV; Cystathionine beta-Synthase; Cystathionine gamma-Lyase; Diabetes Mellitus, Experimental; Glucose; Hydrogen Sulfide; Hyperglycemia; Kidney; Losartan; Mesangial Cells; NADPH Oxidases; Onium Compounds; Peptidyl-Dipeptidase A; Rats; Reactive Oxygen Species; Receptor, Angiotensin, Type 1; Renin-Angiotensin System; RNA, Messenger; Transforming Growth Factor beta1