scholarly journals Angiotensin II Upregulates Sodium-Glucose Co-Transporter2 (SGLT2) Expression and SGLT2 Inhibitor Attenuates Ang II-Induced Hypertensive Renal Injury in Mice

2020 ◽  
Author(s):  
Kana N Miyata ◽  
Chao-Sheng Lo ◽  
Shuiling Zhao ◽  
Min-Chun Liao ◽  
Yuchao Pang ◽  
...  

Clinical trials indicate that sodium-glucose co-transporter 2 inhibitors (SGLT2i) improve kidney function, yet, the molecular regulation of SGLT2 expression is incompletely understood. Here, we investigated the role of the intrarenal renin-angiotensin-system (RAS) on SGLT2 expression. In adult non-diabetic participants in the Nephrotic Syndrome Study Network (NEPTUNE, N=163), multivariable linear regression analysis showed SGLT2 mRNA was significantly associated with angiotensinogen (AGT), renin, and angiotensin converting enzyme (ACE) mRNA levels (p<0.001). In vitro, angiotensin II (Ang II) dose-dependently stimulated SGLT2 expression in HK-2, human immortalized renal proximal tubular cells (RPTCs); losartan and antioxidants inhibited it. Sglt2 expression was increased in transgenic mice specifically overexpressing Agt in their RPTCs, as well as in WT mice with a single subcutaneous injection of Ang II (1.44 mg/kg). Moreover, Ang II (1000 ng/kg/min) infusion via osmotic mini-pump in WT mice for 4 weeks increased systolic blood pressure (SBP), glomerulosclerosis, tubulointerstitial fibrosis, and albuminuria; canaglifozin (Cana, 15 mg/kg/day) reversed these changes, with the exception of SBP. Fractional glucose excretion was higher in Ang II+Cana than WT+Cana, whereas Sglt2 expression was similar. Our data demonstrate a link between intrarenal RAS and SGLT2 expression and that SGLT2i ameliorates Ang II-induced renal injury independent of SBP.

2013 ◽  
Vol 25 (3) ◽  
pp. 539 ◽  
Author(s):  
Lucas C. Siqueira ◽  
Joabel T. dos Santos ◽  
Rogério Ferreira ◽  
Robson Souza dos Santos ◽  
Adelina M. dos Reis ◽  
...  

The present study evaluated whether the gonadotrophin surge modulates components of the renin–angiotensin system and whether angiotensin II (Ang II) plays a role in the production of hormones by follicular cells during the ovulatory process. In Experiment 1, cows were ovariectomised at various times (0, 3, 6, 12 and 24h) after GnRH injection to obtain preovulatory follicles. The concentration of Ang II in follicular fluid increased after GnRH and reached a peak at 24h, concomitant with the peak of angiotensinogen (AGT) mRNA expression in granulosa cells. AGT mRNA was not expressed in theca cells. Ang II receptor type 2 and angiotensin-converting enzyme mRNA levels were transiently upregulated in theca cells. In Experiment 2, an in vitro culture was used to determine whether Ang II could modulate hormone production by healthy dominant follicles. In the absence of LH, Ang II did not alter hormonal production by either theca or granulosa cells. Ang II plus LH increased progesterone and prostaglandin secretion by granulosa cells. In summary, the renin–angiotensin system is actively controlled during the preovulatory period and Ang II amplifies the stimulatory effects of LH on the secretion of progesterone and prostaglandins by granulosa cells.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yongjun Zhu ◽  
Hongwang Cui ◽  
Jie Lv ◽  
Haiqin Liang ◽  
Yanping Zheng ◽  
...  

AbstractAbnormal renin-angiotensin system (RAS) activation plays a critical role in the initiation and progression of chronic kidney disease (CKD) by directly mediating renal tubular cell apoptosis. Our previous study showed that necroptosis may play a more important role than apoptosis in mediating renal tubular cell loss in chronic renal injury rats, but the mechanism involved remains unknown. Here, we investigate whether blocking the angiotensin II type 1 receptor (AT1R) and/or angiotensin II type 2 receptor (AT2R) beneficially alleviates renal tubular cell necroptosis and chronic kidney injury. In an angiotensin II (Ang II)-induced renal injury mouse model, we found that blocking AT1R and AT2R effectively mitigates Ang II-induced increases in necroptotic tubular epithelial cell percentages, necroptosis-related RIP3 and MLKL protein expression, serum creatinine and blood urea nitrogen levels, and tubular damage scores. Furthermore, inhibition of AT1R and AT2R diminishes Ang II-induced necroptosis in HK-2 cells and the AT2 agonist CGP42112A increases the percentage of necroptotic HK-2 cells. In addition, the current study also demonstrates that Losartan and PD123319 effectively mitigated the Ang II-induced increases in Fas and FasL signaling molecule expression. Importantly, disruption of FasL significantly suppressed Ang II-induced increases in necroptotic HK-2 cell percentages, and necroptosis-related proteins. These results suggest that Fas and FasL, as subsequent signaling molecules of AT1R and AT2R, might involve in Ang II-induced necroptosis. Taken together, our results suggest that Ang II-induced necroptosis of renal tubular cell might be involved both AT1R and AT2R and the subsequent expression of Fas, FasL signaling. Thus, AT1R and AT2R might function as critical mediators.


2017 ◽  
Vol 312 (5) ◽  
pp. H968-H979 ◽  
Author(s):  
Neeru M. Sharma ◽  
Shyam S. Nandi ◽  
Hong Zheng ◽  
Paras K. Mishra ◽  
Kaushik P. Patel

An activated renin-angiotensin system (RAS) within the central nervous system has been implicated in sympathoexcitation during various disease conditions including congestive heart failure (CHF). In particular, activation of the RAS in the paraventricular nucleus (PVN) of the hypothalamus has been recognized to augment sympathoexcitation in CHF. We observed a 2.6-fold increase in angiotensinogen (AGT) in the PVN of CHF. To elucidate the molecular mechanism for increased expression of AGT, we performed in silico analysis of the 3′-untranslated region (3′-UTR) of AGT and found a potential binding site for microRNA (miR)-133a. We hypothesized that decreased miR-133a might contribute to increased AGT in the PVN of CHF rats. Overexpression of miR-133a in NG108 cells resulted in 1.4- and 1.5-fold decreases in AGT and angiotensin type II (ANG II) type 1 receptor (AT1R) mRNA levels, respectively. A luciferase reporter assay performed on NG108 cells confirmed miR-133a binding to the 3′-UTR of AGT. Consistent with these in vitro data, we observed a 1.9-fold decrease in miR-133a expression with a concomitant increase in AGT and AT1R expression within the PVN of CHF rats. Furthermore, restoring the levels of miR-133a within the PVN of CHF rats with viral transduction resulted in a significant reduction of AGT (1.4-fold) and AT1R (1.5-fold) levels with a concomitant decrease in basal renal sympathetic nerve activity (RSNA). Restoration of miR-133a also abrogated the enhanced RSNA responses to microinjected ANG II within the PVN of CHF rats. These results reveal a novel and potentially unique role for miR-133a in the regulation of ANG II within the PVN of CHF rats, which may potentially contribute to the commonly observed sympathoexcitation in CHF. NEW & NOTEWORTHY Angiotensinogen (AGT) expression is upregulated in the paraventricular nucleus of the hypothalamus through posttranscriptional mechanism interceded by microRNA-133a in heart failure. Understanding the mechanism of increased expression of AGT in pathological conditions leading to increased sympathoexcitation may provide the basis for the possible development of new therapeutic agents with enhanced specificity.


1995 ◽  
Vol 268 (2) ◽  
pp. F266-F272 ◽  
Author(s):  
B. A. Atiyeh ◽  
B. S. Arant ◽  
W. L. Henrich ◽  
M. G. Seikaly

The glomerulus has several components of the renin-angiotensin system (RAS). The purpose of this study was to evaluate the ability of glomeruli isolated from adult Wistar-Kyoto rats to produce angiotensin II (ANG II). When isolated glomeruli were incubated in Krebs buffer, the peak concentration of immunoreactive angiotensin (ANG) in the incubation medium, representing simultaneous production and degradation, occurred after 15 min of incubation (3.98 +/- 0.34 pg.mg protein-1.15 min-1, of which 18% was ANG II. When 125I-labeled ANG II was incubated with isolated glomeruli, the half-life of ANG II was 6.06 min. Hence, we estimated ANG II production at 3.77 +/- 0.21 pg.mg protein-1.15 min-1. When angiotensinogen-rich serum was added to the incubation medium, ANG concentration at 15 min increased by 500-fold (1,978 +/- 44 pg.mg protein-1.15 min-1, P < 0.001). ANG concentration in the glomerular incubate responded to perturbations known to alter systemic RAS. Enalaprilat, chymostatin, propranolol, and renin antiserum decreased ANG concentration in glomerular incubate, whereas salt depletion increased this (P < 0.05). We conclude that the rat glomerulus can generate ANG II independent of neural, hormonal, or vascular control.


Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Peter P Sayeski ◽  
Sung O Park ◽  
Annet Kirabo ◽  
Rebekah Baskin ◽  
Dale M Seth ◽  
...  

We previously found that Jak2 kinase, expressed within vascular smooth muscle cells (VSMC), plays a critical role in angiotensin II (Ang II)-mediated hypertension. Given that Jak2 mediates both pressor-dependent and pressor-independent events, we sought to determine the role of blood pressure (BP), per se, on the deleterious effects of Jak2 within the kidney. To investigate this, three groups of mice were examined; i) wild type mice (Controls) that received Ang II infusion, ii) mice lacking Jak2 expression within the VSMC (VSMC Jak2 Null) that also received Ang II, and iii) Control mice that received Ang II plus an anti-hypertensive triple therapy (3Rx). After baseline BP recordings, Ang II was infused (1000 ng/kg/min, SC) to all groups and the 3Rx regimen (80 mg/L hydralazine, 5 mg/L reserpine, 30 mg/L hydrochlorothiazide in the drinking water) was initiated two days later to the 3Rx group, in order to maintain BP at similar levels to the VSMC Jak2 Null group. After 28 days of Ang II, mice were euthanized and the kidneys were assessed via histological, molecular, and functional approaches. Chronic Ang II infusion significantly increased the levels of intrarenal Ang II in all three groups; Control = 1,262±283 fmol/g, VSMC Jak2 Null = 1,655±666 fmol/g, and 3Rx = 2,174±588. While Ang II infusion significantly increased the mean BP in the Control group (152 ± 2 mm Hg), it was significantly, and similarly, lower in both the VSMC Jak2 Null and 3Rx groups (125 ± 5 mm Hg and 131 ± 5 mm Hg, respectively). Glomerular sclerosis was absent and interstitial fibrosis ranged from absent- mild- moderate, and was similar in all groups. The increases in i) perivascular infiltration of CD3+ lymphocytes, ii) CTGF gene expression, iii) tubule casts and iv) albuminuria that were observed in the Control mice, were significantly reduced in both the VSMC Jak2 Null and 3Rx groups. [CTGF mRNA Levels: Control = 100%±17, VSMC Jak2 Null = 70%±12*, 3Rx= 56%±17*. Urine Albumin (ng/day): Control = 414 ± 262, VSMC Jak2 Null = 138 ± 172*, 3Rx= 101 ± 89* (*, p<0.05 vs. Control)]. Thus, the early renal injury due to chronic Ang II infusion correlates with increased BP and not with the expression of VSMC-derived Jak2, suggesting that Jak2 contributes to early Ang II-mediated renal injury via its pressor-dependent actions.


2008 ◽  
Vol 295 (2) ◽  
pp. H835-H841 ◽  
Author(s):  
Zsolt Bagi ◽  
Nora Erdei ◽  
Akos Koller

Previously, we found that high intraluminal pressure leads to production of reactive oxygen species (ROS) and also upregulates several components of the renin-angiotensin system in the wall of small arteries. We hypothesized that acute exposure of arterioles to high intraluminal pressure in vitro via increasing ROS production enhances the functional availability of type 1 angiotensin II (Ang II) receptors (AT1 receptors), resulting in sustained constrictions. In arterioles (∼180 μm) isolated from rat skeletal muscle, Ang II elicited dose-dependent constrictions, which decreased significantly by the second application [maximum (max.): from 59% ± 4% to 26% ± 5% at 10−8 M; P < 0.05] in the presence of 80 mmHg of intraluminal pressure. In contrast, if the arterioles were exposed to high intraluminal pressure (160 mmHg for 30 min), Ang II-induced constrictions remained substantial on the second application (max.: 51% ± 3% at 10−8 M). In the presence of Tiron and polyethylene glycol (PEG)-catalase, known to reduce the level of superoxide anion and hydrogen peroxide (H2O2), second applications of Ang II evoked similarly reduced constrictions, even after high-pressure exposure (29% ± 4% at 10−8 M). Furthermore, when arterioles were exposed to H2O2 (for 30 min, 10−7 M, at normal 80 mmHg pressure), Ang II-induced constrictions remained substantial on second applications (59% ± 5% at 10−8 M). These findings suggest that high pressure, likely via inducing H2O2 production, increases the functional availability of AT1 receptors and thus enhances Ang II-induced arteriolar constrictions. We propose that in hypertension–regardless of etiology–high intraluminal pressure, via oxidative stress, enhances the functional availability of AT1 receptors augmenting Ang II-induced constrictions.


1992 ◽  
Vol 263 (5) ◽  
pp. F900-F906 ◽  
Author(s):  
K. Ohishi ◽  
P. K. Carmines ◽  
E. W. Inscho ◽  
L. G. Navar

The in vitro blood-perfused juxtamedullary nephron technique was utilized to determine the contribution of endothelium-derived relaxing factor (EDRF) to resting renal arteriolar caliber and to evaluate the interaction between EDRF and angiotensin II (ANG II) in renal microvascular control. Video microscopy was employed to visualize rat afferent and efferent arterioles and to measure their responses to blockade of nitric oxide (NO), which has been shown to account for much of the biological action of EDRF. The NO synthesis inhibitor, N omega-nitro-L-arginine (L-NNA), elicited vasoconstriction in a concentration-dependent manner, with 1,000 microM L-NNA significantly reducing both afferent (16 +/- 3%) and efferent (13 +/- 1%) diameters. This concentration of L-NNA also blocked the vasodilator response to 10 microM acetylcholine, while responsiveness to sodium nitroprusside was maintained. Vasoconstrictor responses to 1,000 microM L-NNA were attenuated in kidneys from rats pretreated with enalaprilat or losartan, reducing afferent diameter by 7 +/- 1 (n = 8) and 3 +/- 1% (n = 10) of control, respectively. Efferent arteriolar responses to L-NNA were similarly attenuated by losartan. The constrictor response to 10 nM ANG II was not exaggerated by L-NNA, suggesting that ANG II does not stimulate EDRF synthesis. These observations indicate that EDRF is continuously released in a quantity sufficient to affect both afferent and efferent arterioles of juxtamedullary nephrons in vitro. Furthermore, ANG II blockade attenuates the vasoconstriction elicited by L-NNA, suggesting that EDRF interacts with the renin-angiotensin system to control juxtamedullary afferent and efferent arteriolar resistance.


2013 ◽  
Vol 304 (5) ◽  
pp. F505-F514 ◽  
Author(s):  
Weijian Shao ◽  
Dale M. Seth ◽  
Minolfa C. Prieto ◽  
Hiroyuki Kobori ◽  
L. Gabriel Navar

In angiotensin II (ANG II) infusion hypertension, there is an augmentation of intratubular angiotensinogen (AGT) and ANG II leading to increased urinary AGT and ANG II excretion rates associated with tissue injury. However, the changes in urinary AGT and ANG II excretion rates and markers of renal injury during physiologically induced stimulation of the renin-angiotensin system (RAS) by a low-salt diet remain unclear. Male Sprague-Dawley rats received a low-salt diet (0.03% NaCl; n = 6) and normal-salt diet (0.3% NaCl, n = 6) for 13 days. Low-salt diet rats had markedly higher plasma renin activity and plasma ANG II levels. Kidney cortex renin mRNA, kidney AGT mRNA, and AGT immunoreactivity were not different; however, medullary renin mRNA, kidney renin content, and kidney ANG II levels were significantly elevated by the low-salt diet. Kidney renin immunoreactivity was also markedly increased in juxtaglomerular apparati and in cortical and medullary collecting ducts. Urinary AGT excretion rates and urinary ANG II excretion rates were not augmented by the low-salt diet. The low-salt diet caused mild renal fibrosis in glomeruli and the tubulointerstitium, but no other signs of kidney injury were evident. These results indicate that, in contrast to the response in ANG II infusion hypertension, the elevated plasma and intrarenal ANG II levels caused by physiological stimulation of RAS are not reflected by increased urinary AGT or ANG II excretion rates or the development of renal injury.


1994 ◽  
Vol 266 (3) ◽  
pp. F384-F393 ◽  
Author(s):  
D. Chansel ◽  
T. Bizet ◽  
S. Vandermeersch ◽  
P. Pham ◽  
B. Levy ◽  
...  

The aim of the present report was to examine the effect of several agents on angiotensin II (ANG II) and losartan receptors using 125I-[Sar1,Ala8]ANG II and [3H]losartan as radiolabeled ligand, respectively. ANG II receptors were downregulated in glomeruli from rats infused with ANG II during 3 wk or rats receiving losartan orally during 1 wk. The number of sites (Bmax) was reduced, but the dissociation constant (Kd) value was unchanged. Losartan receptors were downregulated in glomeruli from rats receiving losartan, but remained unchanged in glomeruli from rats infused with ANG II. Since in vivo administration of losartan results in increase of plasma ANG II and formation of metabolites, in vitro studies using human mesangial cells were performed to better analyze the present findings. Treatment of mesangial cells during 4 days by ANG II, losartan, or its metabolite, EXP-3174, also produced downregulation of 125I-[Sar1,Ala8]ANG II binding sites with a decreased Bmax and unchanged Kd value. Only treatment of mesangial cells by ANG II or EXP-3174 produced downregulation of [3H]losartan binding sites. In contrast, exposure of these cells to losartan resulted in upregulation of [3H]losartan binding sites. Under all conditions, only Bmax was modified. Whereas internalization of [3H]losartan in mesangial cells was negligible under all experimental conditions, there was an increase of the percentage of internalized 125I-[Sar1,Ala8]ANG II after exposure of the cells to ANG II or AT1 antagonists. No change was observed in mesangial cell AT1 receptor mRNA levels. This study demonstrates that 1) AT1 mRNA is expressed in human mesangial cells; 2) the characteristics of 125I-[Sar1,Ala8]ANG II and [3H]losartan binding sites in rat glomeruli and human mesangial cells are different, with Kd and Bmax values greater in both preparations when [3H]losartan was utilized; 3) both types of binding sites obey different regulations, and the effects of losartan in vivo are due in part to the associated increase in plasma ANG II levels and the transformation of the drug into its metabolite, EXP-3174; 4) downregulation of AT1 receptors does not depend on changes in mRNA expression but is associated with increased relative internalization.


1994 ◽  
Vol 266 (6) ◽  
pp. F911-F918 ◽  
Author(s):  
A. Tufro-McReddie ◽  
D. W. Johns ◽  
K. M. Geary ◽  
H. Dagli ◽  
A. D. Everett ◽  
...  

To determine whether angiotensin II (ANG II) modulates renal growth and renin and angiotensin type 1 (AT1) gene expression via AT1 during development, weanling rats were given ANG II antagonist losartan (DuP 753) for 3 wk. Body weight (g), kidney weight (g), and kidney weight-to-body weight ratio were lower in losartan-treated rats (162 +/- 7, 1.6 +/- 0.06, and 9.5 +/- 0.1 x 10(-3)) than in control rats (184 +/- 5, 1.8 +/- 0.07, and 10.1 +/- 0.1 x 10(-3); P < 0.05). Renal DNA content (mg/kidney) was lower in losartan-treated (2.4 +/- 0.17) than in control rats (3.3 +/- 0.31; P < 0.05), whereas protein-to-DNA and RNA-to-DNA ratios were similar in losartan-treated and control rats. Renin mRNA levels were sevenfold higher in losartan-treated than in control rats, as determined by quantitative standardized dot blot analysis. In addition, blockade of AT1 with losartan induced recruitment of renin-synthesizing and renin-containing cells in the renal vasculature, as determined by immunocytochemistry and in situ hybridization. To establish whether AT1 blockade has a direct effect on renin gene expression, freshly isolated renin-producing cells were exposed in vitro to losartan (10(-6) M) or culture media (control). Losartan induced a twofold increase in steady-state renin mRNA levels above control (P < 0.05). Intrarenal AT1 mRNA levels were not altered by losartan given either in vivo or in vitro to freshly dispersed cells. To define whether immature renin-secreting cells are responsive to ANG II, renin release was determined by reverse hemolytic plaque assay.(ABSTRACT TRUNCATED AT 250 WORDS)


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