scholarly journals Angiotensin II-induced ERK1/ERK2 activation and protein synthesis are redox-dependent in glomerular mesangial cells

2004 ◽  
Vol 381 (1) ◽  
pp. 231-239 ◽  
Author(s):  
Yves GORIN ◽  
Jill M. RICONO ◽  
Brent WAGNER ◽  
Nam-Ho KIM ◽  
Basant BHANDARI ◽  
...  

Angiotensin II (Ang II) stimulates hypertrophy of glomerular mesangial cells. The signalling mechanism by which Ang II exerts this effect is not precisely known. Downstream potential targets of Ang II are the extracellular-signal-regulated kinases 1 and 2 (ERK1/ERK2). We demonstrate that Ang II activates ERK1/ERK2 via the AT1 receptor. Arachidonic acid (AA) mimics the action of Ang II on ERK1/ERK2 and phospholipase A2 inhibitors blocked Ang II-induced ERK1/ERK2 activation. The antioxidant N-acetylcysteine as well as the NAD(P)H oxidase inhibitors diphenylene iodonium and phenylarsine oxide abolished both Ang II- and AA-induced ERK1/ERK2 activation. Moreover, dominant-negative Rac1 (N17Rac1) blocks activation of ERK1/ERK2 in response to Ang II and AA, whereas constitutively active Rac1 resulted in an increase in ERK1/ERK2 activity. Antisense oligonucleotides for Nox4 NAD(P)H oxidase significantly reduce activation of ERK1/ERK2 by Ang II and AA. We also show that protein synthesis in response to Ang II and AA is inhibited by N17Rac1 or MEK (mitogen-activated protein kinase/ERK kinase) inhibitor. These results demonstrate that Ang II stimulates ERK1/ERK2 by AA and Nox4-derived reactive oxygen species, suggesting that these molecules act as downstream signal transducers of Ang II in the signalling pathway linking the Ang II receptor AT1 to ERK1/ERK2 activation. This pathway involving AA, Rac1, Nox4, reactive oxygen species and ERK1/ERK2 may play an important role in Ang II-induced mesangial cell hypertrophy.

Author(s):  
Yu-Te Lin ◽  
Yi-Chung Wu ◽  
Gwo-Ching Sun ◽  
Chiu-Yi Ho ◽  
Tzyy-Yue Wong ◽  
...  

Recent studies have indicated that several anti-hypertensive drugs may delay the development and progression of Alzheimer’s disease (AD). However, the relationships among AD, hypertension, and oxidative stress remain to be elucidated. In the present study, we aimed to determine whether treatment with resveratrol reduces reactive oxygen species (ROS) generation in the brain, thereby reducing cognitive impairment in rats with angiotensin II (Ang-II)-induced early AD. Male WKY rats with Ang-II-induced AD were treated with losartan or resveratrol for 2 weeks. Our results revealed that treatment with resveratrol (10 mg/kg/day) decreased blood pressure, increased levels of brain-derived neurotrophic factor (BDNF) in the hippocampus, and decreased ROS production in the nucleus tractus solitarius (NTS) in the Ang-II groups. In addition, inhibition of TauT231 phosphorylation in the hippocampus using resveratrol significantly abolished Ang-II-induced expression of Ab precursors, active caspase 3, and glycogen synthase kinase 3b (GSK-3b)Y216 while increasing AktS473 phosphorylation. Notably, resveratrol reversed impairments in hippocampal-dependent contextual memory induced by deleting NADPH oxidase and NOX2. Overall, our results suggest that resveratrol exerts neuroprotective effects against memory impairment and hippocampal damage in a rat model of early stage AD by reducing oxidative stress. These novel findings indicate that resveratrol may represent a pharmacological option for patients with hypertension at a risk of AD during old age.


2018 ◽  
Vol 7 (10) ◽  
pp. 329 ◽  
Author(s):  
Yu-Te Lin ◽  
Yi-Chung Wu ◽  
Gwo-Ching Sun ◽  
Chiu-Yi Ho ◽  
Tzyy-Yue Wong ◽  
...  

Recent studies have indicated that several anti-hypertensive drugs may delay the development and progression of Alzheimer’s disease (AD). However, the relationships among AD, hypertension, and oxidative stress remain to be elucidated. Here, we aimed to determine whether reactive oxygen species (ROS) reduction by resveratrol in the brain leads to cognitive impairment reduction in rats with angiotensin II (Ang-II)-induced early AD. Male Wistar Kyoto (WKY) rats with Ang-II-induced AD were treated with losartan or resveratrol for two weeks. Our results show decreased blood pressure, increased hippocampal brain-derived neurotrophic factor (BDNF) level, and decreased nucleus tractus solitarius (NTS) ROS production in the Ang-II groups with losartan (10 mg/kg), or resveratrol (10 mg/kg/day) treatment. Furthermore, losartan inhibition of hippocampal TauT231 phosphorylation activated AktS473 phosphorylation, and significantly abolished Ang-II-induced Aβ precursors, active caspase 3, and glycogen synthase kinase 3β (GSK-3β)Y216 expressions. Consistently, resveratrol showed similar effects compared to losartan. Both losartan and resveratrol restored hippocampal-dependent contextual memory by NADPH oxidase 2 (NOX2) deletion and superoxide dismutase 2 (SOD2) elevation. Our results suggest that both losartan and resveratrol exert neuroprotective effects against memory impairment and hippocampal damage by oxidative stress reduction in early stage AD rat model. These novel findings indicate that resveratrol may represent a pharmacological option similar to losartan for patients with hypertension at risk of AD during old age.


2021 ◽  
Vol 12 ◽  
Author(s):  
Hawa Nordin Siti ◽  
Juriyati Jalil ◽  
Ahmad Yusof Asmadi ◽  
Yusof Kamisah

Cardiac hypertrophy is characteristic of heart failure in patients who have experienced cardiac remodeling. Many medicinal plants, including Parkia speciosa Hassk., have documented cardioprotective effects against such pathologies. This study investigated the activity of P. speciosa empty pod extract against cardiomyocyte hypertrophy in H9c2 cardiomyocytes exposed to angiotensin II (Ang II). In particular, its role in modulating the Ang II/reactive oxygen species/nitric oxide (Ang II/ROS/NO) axis and mitogen-activated protein kinase (MAPK) pathway was examined. Treatment with the extract (12.5, 25, and 50 μg/ml) prevented Ang II-induced increases in cell size, NADPH oxidase activity, B-type natriuretic peptide levels, and reactive oxygen species and reductions in superoxide dismutase activity. These were comparable to the effects of the valsartan positive control. However, the extract did not significantly ameliorate the effects of Ang II on inducible nitric oxide synthase activity and nitric oxide levels, while valsartan did confer such protection. Although the extract decreased the levels of phosphorylated extracellular signal-related kinase, p38, and c-Jun N-terminal kinase, valsartan only decreased phosphorylated c-Jun N-terminal kinase expression. Phytochemical screening identified the flavonoids rutin (1) and quercetin (2) in the extract. These findings suggest that P. speciosa empty pod extract protects against Ang II-induced cardiomyocyte hypertrophy, possibly by modulating the Ang II/ROS/NO axis and MAPK signaling pathway via a mechanism distinct from valsartan.


2013 ◽  
Vol 305 (10) ◽  
pp. H1451-H1461 ◽  
Author(s):  
Gang Wang ◽  
Pallabi Sarkar ◽  
Jeffrey R. Peterson ◽  
Josef Anrather ◽  
Joseph P. Pierce ◽  
...  

Regulation of blood pressure by angiotensin II (ANG II) is a process that involves the reactive oxygen species (ROS) and calcium. We have shown that ANG-II type 1 receptor (AT1R) and prostaglandin E2 (PGE2) type 1 receptors (EP1R) are required in the subfornical organ (SFO) for ROS-mediated hypertension induced by slow-pressor ANG-II infusion. However, the signaling pathway associated with this process remains unclear. We sought to determine mechanisms underlying the ANG II-induced ROS and calcium influx in mouse SFO cells. Ultrastructural studies showed that cyclooxygenase 1 (COX-1) codistributes with AT1R in the SFO, indicating spatial proximity. Functional studies using SFO cells revealed that ANG II potentiated PGE2 release, an effect dependent on AT1R, phospholipase A2 (PLA2) and COX-1. Furthermore, both ANG II and PGE2 increased ROS formation. While the increase in ROS initiated by ANG II, but not PGE2, required the activation of the AT1R/PLA2/COX-1 pathway, both ANG II and PGE2 were dependent on EP1R and Nox2 as downstream effectors. Finally, ANG II potentiated voltage-gated L-type Ca2+ currents in SFO neurons via the same signaling pathway required for PGE2 production. Blockade of EP1R and Nox2-derived ROS inhibited ANG II and PGE2-mediated Ca2+ currents. We propose a mechanism whereby ANG II increases COX-1-derived PGE2 through the AT1R/PLA2 pathway, which promotes ROS production by EP1R/Nox2 signaling in the SFO. ANG II-induced ROS are coupled with Ca2+ influx in SFO neurons, which may influence SFO-mediated sympathoexcitation. Our findings provide the first evidence of a spatial and functional framework that underlies ANG-II signaling in the SFO and reveal novel targets for antihypertensive therapies.


2006 ◽  
Vol 290 (1) ◽  
pp. H96-H106 ◽  
Author(s):  
Julieta Palomeque ◽  
Luciana Sapia ◽  
Roger J. Hajjar ◽  
Alicia Mattiazzi ◽  
Martín Vila Petroff

The octapeptide angiotensin II (ANG II) can modulate cardiac contractility and is increased in heart failure, where contractile function is impaired. In rat cardiac myocytes, 1 μM of ANG II produces a negative inotropic effect (NIE) (24.6 ± 5% reduction). However, the subcellular signaling involved in this effect remains elusive. We examined the mechanisms and signaling events involved in the reduction in contractile function induced by the peptide in indo-1-loaded rat cardiomyocytes. The results showed that the NIE of ANG II was not associated with a parallel decrease in the intracellular Ca2+ transient, indicating that a decrease in myofilament responsiveness to Ca2+ underlies the reduction in contractility. We assessed the role of PKC, tyrosine kinases, reactive oxygen species (ROS), and mitogen-activated protein kinases (MAPKs) in the NIE of the peptide. Pretreatment of cells with the NAD(P)H oxidase inhibitor diphenyleneiodonium chloride or with the superoxide scavenger 4,5-dihydroxy-1,3-benzene-disulfonic acid did not affect the ANG II-induced NIE. Moreover, ANG II-induced ROS production, after 20 min of incubation with the peptide, could not be detected with the use of either the fluorophore 5-(6)-chloromethyl-2′, 7′-dichlorodihydrofluorecein diacetate or lucigenin-enhanced chemiluminescence. In contrast, the ANG II-induced NIE was abrogated by the inhibitors of PKC (calphostin C), tyrosine kinase (genistein), and p38 MAPK (SB-202190). Furthermore, the NIE was significantly exacerbated (60 ± 10% reduction) by p38 MAPK overexpression. These results exclude the participation of ROS in the NIE of the peptide and point to PKC and tyrosine kinase as upstream mediators. Furthermore, they reveal p38 MAPK as the putative effector of the reduction in myofilament responsiveness to Ca2+ and the decrease in contractility induced by the peptide.


1983 ◽  
Vol 158 (6) ◽  
pp. 1836-1852 ◽  
Author(s):  
L Baud ◽  
J Hagege ◽  
J Sraer ◽  
E Rondeau ◽  
J Perez ◽  
...  

To investigate the phagocytic capability of glomerular mesangial cells and the biochemical events associated with phagocytosis, rat cultured mesangial cells were incubated in the presence of opsonized zymosan (STZ) and production of reactive-oxygen species and lipoxygenase products were determined. Mesangial cells were identified on the basis of morphologic (presence of microfilaments and pattern of staining by an anti-myosin antiserum) and physiologic (contractile activity in response to angiotensin II) characteristics. No contamination by esterase-positive cells was observed. Electron microscopy revealed that the phagocytic process started after 5 min of incubation, and affected approximately 50% of the cells. Superoxide anion (.O2-) and hydrogen peroxide (H2O2) generation by mesangial cells exposed to STZ increased with time and STZ concentration. Cells incubated with zymosan particles treated with heated serum produced undetectable amounts of .O2- and 6 times less H2O2 than cells exposed to STZ. Pretreatment by cytochalasin B produced a marked decrease in STZ-stimulated production of reactive oxygen species. [3H]Arachidonic acid was incorporated into mesangial cell phospholipids and its release and conversion into monohydroxyeicosatetraenoic acids (HETE) was measured by radiometric high performance liquid chromatography (HPLC). Incubation with STZ markedly stimulated the release of arachidonic acid from its phospholipid stores and its transformation into 11-, 12-, and 15-HETE. Lipoxygenase inhibitors inhibited STZ-stimulated H2O2 production, whereas they did not modify the phagocytic process as shown by the absence of any effect on the uptake of 125I-STZ by the mesangial cells. This study demonstrates that a high percentage of rat cultured mesangial cells phagocytose opsonized particles. The phagocytic process results in an oxidative burst that appears to be dependent on stimulation of the lipoxygenase pathway.


2012 ◽  
Vol 302 (4) ◽  
pp. H901-H909 ◽  
Author(s):  
Rukhsana Gul ◽  
Asif Iqbal Shawl ◽  
Suhn-Hee Kim ◽  
Uh-Hyun Kim

Reactive oxygen species (ROS) and Ca2+ signals are closely associated with the pathogenesis of cardiac hypertrophy. However, the cause and effect of the two signals in cardiac hypertrophy remain to be clarified. We extend our recent report by investigating a potential interaction between ROS and Ca2+ signals utilizing in vitro and in vivo angiotensin II (ANG II)-induced cardiac hypertrophy models. ANG II-induced initial Ca2+ transients mediated by inositol trisphosphate (IP3) triggered initial ROS production in adult rat cardiomyocytes. The ROS generated by activation of the NAD(P)H oxidase complex via Rac1 in concert with Ca2+ activates ADP-ribosyl cyclase to generate cyclic ADP-ribose (cADPR). This messenger-mediated Ca2+ signal further augments ROS production, since 2,2′-dihydroxyazobenzene, an ADP-ribosyl cyclase inhibitor, or 8-Br-cADPR, an antagonistic analog of cADPR, abolished further ROS production. Data from short hairpin RNA (shRNA)-mediated knockdown of Akt1 and p47phox demonstrated that Akt1 is the upstream key molecule responsible for the initiation of Ca2+ signal that activates p47phox to generate ROS in cardiomyocytes. Nuclear translocation of nuclear factor of activated T-cell in cardiomyocytes was significantly suppressed by treatment with NAD(P)H oxidase inhibitors as well as by shRNA against Akt1 and p47phox. Our results suggest that in cardiomyocytes Ca2+ and ROS messengers generated by ANG II amplify the initial signals in a cooperative manner, thereby leading to cardiac hypertrophy.


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