Lipid signal transduction pathways in angiotensin II type 1 receptor-transfected fibroblasts

1995 ◽  
Vol 269 (2) ◽  
pp. C435-C442 ◽  
Author(s):  
Y. Wen ◽  
M. C. Cabot ◽  
E. Clauser ◽  
S. L. Bursten ◽  
J. L. Nadler
Keyword(s):  
Signal Transduction ◽  
Angiotensin Ii ◽  
Chinese Hamster ◽  
Receptor Activation ◽  
Signal Transduction Pathways ◽  
Ang Ii ◽  
Vascular Type ◽  
Lipid Signal ◽  
Fibroblast Line

A stable Chinese hamster ovary fibroblast line expressing the rat vascular type 1a angiotensin II (ANG II) receptor was used to study the lipid-derived signal transduction pathways elicited by type 1a ANG II receptor activation. ANG II caused a biphasic and dose-dependent increase in diacylglycerol (DAG) accumulation with an initial peak at 15 s (181 +/- 11% of control, P < 0.02) and a second sustained peak at 5-10 min (214 +/- 10% of control, P < 0.02). The late DAG peak was derived from phosphatidylcholine (PC), and the formation was blocked by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. ANG II also increased phosphatidic acid (PA) production nearly fourfold by 7.5 min. In the presence of ethanol, ANG II markedly increased phosphatidylethanol (PEt) formation, indicating activation of phospholipase D (PLD). ANG II was shown to increase the mass of three separate PA species, one of which apparently originated from DAG kinase action on PC-phospholipase C (PLC)-produced DAG, providing evidence for PC-PLC activity. ANG II also formed a third PA species, which originated neither from PLD nor from DAG kinase. These results demonstrate that multiple lipid signals propagated via collateral stimulation of PLC and PLD are generated by specific activation of the vascular type 1a ANG II receptor.

Cysteinyl leukotriene-dependent [Ca2+]iresponses to angiotensin II in cardiomyocytes

2003 ◽  
Vol 284 (4) ◽  
pp. H1269-H1276 ◽  
Author(s):  
Pinggang Liu ◽  
Derek A. Misurski ◽  
Venkat Gopalakrishnan
Keyword(s):  
Angiotensin Ii ◽  
Single Cells ◽  
Receptor Activation ◽  
Neonatal Rat ◽  
Ang Ii ◽  
Rat Cardiomyocytes ◽  
Endothelin 1 ◽  
Neonatal Rat Cardiomyocytes ◽  
Cysteinyl Leukotriene

With the use of fura 2 measurements in multiple and single cells, we examined whether cysteinyl leukotrienes (CysLT) mediate angiotensin II (ANG II)-evoked increases in cytosolic free Ca2+ concentration ([Ca2+]i) in neonatal rat cardiomyocytes. ANG II-evoked CysLT release peaked at 1 min. The angiotensin type 1 (AT1) antagonist losartan, but not the AT2antagonist PD-123319, attenuated the elevations in [Ca2+]i and CysLT levels evoked by ANG II. Vasopressin and endothelin-1 increased [Ca2+]i but not CysLT levels. The 5-lipoxygenase (5-LO) inhibitor AA-861 and the CysLT1-selective antagonist MK-571 reduced the maximal [Ca2+]i responses to ANG II but not to vasopressin and endothelin-1. While MK-571 reduced the responses to leukotriene D4 (LTD4), the dual CysLT antagonist BAY-u9773 completely blocked the [Ca2+]i elevation to both LTD4and LTC4. These data confirm that ANG II-evoked increases, but not vasopressin- and endothelin-1-evoked increases, in [Ca2+]i involve generation of the 5-lipoxygenase metabolite CysLT. The inositol (1,4,5)-trisphosphate [Ins(1,4,5)P3] antagonist 2-aminoethoxydiphenyl borate attenuated the [Ca2+]i responses to ANG II and LTD4. Thus AT1 receptor activation by ANG II is linked to CysLT-mediated Ca2+ release from Ins(1,4,5)P3-sensitive intracellular stores to augment direct ANG II-evoked Ca2+ mobilization in rat cardiomyocytes.

Effects of angiotensin II on the CO2 dependence of HCO3− reabsorption by the rabbit S2 renal proximal tubule

2006 ◽  
Vol 290 (3) ◽  
pp. F666-F673 ◽  
Author(s):  
Yuehan Zhou ◽  
Patrice Bouyer ◽  
Walter F. Boron
Keyword(s):  
Signal Transduction ◽  
Angiotensin Ii ◽  
Proximal Tubule ◽  
Renal Proximal Tubule ◽  
Signal Transduction Pathways ◽  
Low Doses ◽  
Ang Ii ◽  
Reabsorption Rate ◽  
Fractional Inhibition

Previous authors showed that, at low doses, both basolateral and luminal ANG II increase the proximal tubule's HCO3− reabsorption rate ( JHCO3). Using out-of-equilibrium CO2/HCO3− solutions, we demonstrated that basolateral CO2 increases JHCO3. Here, we examine interactions between ANG II and CO2 in isolated, perfused rabbit S2 segments. We first used equilibrated 5% CO2/22 mM HCO3−/pH 7.40 in bath and lumen. At 10−11 M, basolateral (BL) ANG II increased JHCO3 by 41%, and luminal ANG II increased JHCO3 by 35%. At 10−9 M, basolateral ANG II decreased JHCO3 by 43%, whereas luminal ANG II was without effect. Second, we varied [CO2]BL from 0 to 20% at fixed [HCO3−]BL and pHBL. Fractional stimulation produced by BL 10−11 M ANG II falls when [CO2]BL exceeds 5%. Fractional inhibition produced by BL 10−9 M ANG II tends to rise when [CO2]BL exceeds 5%. Regarding luminal ANG II, fractional stimulation produced by 10−11 M ANG II fell monotonically as [CO2]BL rose from 0 to 20%. Fractional inhibition produced by 10−9 M ANG II rose monotonically with increasing [CO2]BL. Viewed differently, ANG II at 10−11 M tended to reduce stimulation by CO2, and at 10−9 M, produced an even greater reduction. In conclusion, the mutual effects of 1) ANG II on the JHCO3 response to basolateral CO2 and 2) basolateral CO2 on the JHCO3 responses to ANG II suggest that the signal-transduction pathways for ANG II and basolateral CO2 intersect or merge.

scholarly journals Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology

2018 ◽  
Vol 98 (3) ◽  
pp. 1627-1738 ◽  
Author(s):  
Steven J. Forrester ◽  
George W. Booz ◽  
Curt D. Sigmund ◽  
Thomas M. Coffman ◽  
Tatsuo Kawai ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Angiotensin Ii ◽  
Signaling Pathways ◽  
Organ Damage ◽  
Metabolic Dysfunction ◽  
Ang Ii ◽  
Signaling Mechanisms ◽  
New Concepts ◽  
Large Animals

The renin-angiotensin-aldosterone system plays crucial roles in cardiovascular physiology and pathophysiology. However, many of the signaling mechanisms have been unclear. The angiotensin II (ANG II) type 1 receptor (AT1R) is believed to mediate most functions of ANG II in the system. AT1R utilizes various signal transduction cascades causing hypertension, cardiovascular remodeling, and end organ damage. Moreover, functional cross-talk between AT1R signaling pathways and other signaling pathways have been recognized. Accumulating evidence reveals the complexity of ANG II signal transduction in pathophysiology of the vasculature, heart, kidney, and brain, as well as several pathophysiological features, including inflammation, metabolic dysfunction, and aging. In this review, we provide a comprehensive update of the ANG II receptor signaling events and their functional significances for potential translation into therapeutic strategies. AT1R remains central to the system in mediating physiological and pathophysiological functions of ANG II, and participation of specific signaling pathways becomes much clearer. There are still certain limitations and many controversies, and several noteworthy new concepts require further support. However, it is expected that rigorous translational research of the ANG II signaling pathways including those in large animals and humans will contribute to establishing effective new therapies against various diseases.

Intracellular angiotensin II induces cell proliferation independent of AT1 receptor

2006 ◽  
Vol 291 (5) ◽  
pp. C995-C1001 ◽  
Author(s):  
Kenneth M. Baker ◽  
Rajesh Kumar
Keyword(s):  
Cell Proliferation ◽  
Angiotensin Ii ◽  
Cho Cells ◽  
Cardiac Myocyte ◽  
Chinese Hamster ◽  
Cell Types ◽  
Growth Effect ◽  
Ang Ii

We recently reported intracrine effects of angiotensin II (ANG II) on cardiac myocyte growth and hypertrophy that were not inhibited by the ANG II type 1 receptor (AT1) antagonist, losartan. To further determine the role of AT1 in intracrine effects, we studied the effect of intracellular ANG II (iANG II) on cell proliferation in native Chinese hamster ovary (CHO) cells and those stably transfected with AT1 receptor (CHO-AT1). CHO-AT1, but not CHO cells, showed enhanced proliferation following exposure to extracellular ANG II (eANG II). However, when transiently transfected with an iANG II expression vector, both cell types showed significantly enhanced proliferation, compared with those transfected with a scrambled peptide. Losartan blocked eANG II-induced cell proliferation, but not that induced by iANG II. To further confirm these findings, CHO and CHO-AT1 cells were stably transfected for iANG II expression (CHO-iA and CHO-AT1-iA, respectively). Cells grown in serum-free medium were counted every 24 h, up to 72 h. CHO-iA and CHO-AT1-iA cells showed a steeper growth curve compared with CHO and CHO-AT1, respectively. These observations were confirmed by Wst-1 assay. The AT1 receptor antagonists losartan, valsartan, telmisartan, and candesartan did not attenuate the faster growth rate of CHO-iA and CHO-AT1-iA cells. eANG II showed an additional growth effect in CHO-AT1-iA cells, which could be selectively blocked by losartan. These data demonstrate that intracrine ANG II can act independent of AT1 receptors and suggest novel intracellular mechanisms of action for ANG II.

scholarly journals Angiotensin II-Induced Cardiac Effects Are Modulated by Endocannabinoid-Mediated CB1 Receptor Activation

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 724
Author(s):  
Zsuzsanna Miklós ◽  
Dina Wafa ◽  
György L. Nádasy ◽  
Zsuzsanna E. Tóth ◽  
Balázs Besztercei ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Coronary Flow ◽  
Cannabinoid Receptors ◽  
Cardiac Tissue ◽  
Receptor Activation ◽  
Ang Ii ◽  
Metabolic Demand ◽  
Cardiac Effects ◽  
Rat Hearts

Angiotensin II (Ang II) has various cardiac effects and causes vasoconstriction. Ang II activates the type-1 angiotensin receptor—Gq/11 signaling pathway resulting in the release of 2-arachidonoylglycerol (2-AG). We aimed to investigate whether cardiac Ang II effects are modulated by 2-AG-release and to identify the role of type-1 cannabinoid receptors (CB1R) in these effects. Expression of CB1R in rat cardiac tissue was confirmed by immunohistochemistry. To characterize short-term Ang II effects, increasing concentrations of Ang II (10−9–10−7 M); whereas to assess tachyphylaxis, repeated infusions of Ang II (10−7 M) were administered to isolated Langendorff-perfused rat hearts. Ang II infusions caused a decrease in coronary flow and ventricular inotropy, which was more pronounced during the first administration. CB agonist 2-AG and WIN55,212-2 administration to the perfusate enhanced coronary flow. The flow-reducing effect of Ang II was moderated in the presence of CB1R blocker O2050 and diacylglycerol-lipase inhibitor Orlistat. Our findings indicate that Ang II-induced cardiac effects are modulated by simultaneous CB1R-activation, most likely due to 2-AG-release during Ang II signalling. In this combined effect, the response to 2-AG via cardiac CB1R may counteract the positive inotropic effect of Ang II, which may decrease metabolic demand and augment Ang II-induced coronary vasoconstriction.

Angiotensin II type 1 receptor-mediated stimulation of c-fos gene expression in astroglial cultures

1993 ◽  
Vol 265 (4) ◽  
pp. C1046-C1049 ◽  
Author(s):  
M. K. Raizada ◽  
B. Rydzewski ◽  
D. Lu ◽  
C. Sumners
Keyword(s):  
Gene Expression ◽  
Angiotensin Ii ◽  
Receptor Activation ◽  
At1 Receptor ◽  
Mrna Levels ◽  
Ang Ii ◽  
Astroglial Cells ◽  
Pai 1 ◽  
Stimulation Of

Angiotensin II (ANG II) stimulates plasminogen activator inhibitor 1 (PAI-1) gene expression in astroglial cells prepared from rat brains. In this study, we investigated whether c-fos gene expression may be involved in this cellular action of ANG II. Incubation of astroglial cultures with ANG II caused a time- and dose-dependent transient stimulation of the steady-state levels of c-fos mRNA, with a maximal stimulation of 50-fold observed with 100 nM ANG II within 30-45 min. This stimulation was completely abolished by the presence of the type 1 ANG II (AT1) receptor antagonist losartan but not by the type 2 ANG II receptor blocker PD-123177. Depolarization of brain cell cultures with 50 mM K+ also caused a 100-fold increase in c-fos mRNA levels, an effect partially blocked by losartan. These observations show that AT1 receptor activation stimulates expression of the c-fos gene, which may act as a third messenger in the regulation of cellular actions of ANG II, including PAI-1 gene expression in astroglial cells.

Hepatocyte Growth Factor and Macrophage-stimulating Protein “Hinge” Analogs to Treat Pancreatic Cancer

2019 ◽  
Vol 19 (10) ◽  
pp. 782-795
Author(s):  
John W. Wright ◽  
Kevin J. Church ◽  
Joseph W. Harding
Keyword(s):  
Pancreatic Cancer ◽  
Signal Transduction ◽  
Growth Factor ◽  
Hepatocyte Growth Factor ◽  
Tumor Growth ◽  
Receptor Activation ◽  
Signal Transduction Pathways ◽  
Met Receptor ◽  
Macrophage Stimulating Protein ◽  
Hepatocyte Growth

Pancreatic cancer (PC) ranks twelfth in frequency of diagnosis but is the fourth leading cause of cancer related deaths with a 5 year survival rate of less than 7 percent. This poor prognosis occurs because the early stages of PC are often asymptomatic. Over-expression of several growth factors, most notably vascular endothelial growth factor (VEGF), has been implicated in PC resulting in dysfunctional signal transduction pathways and the facilitation of tumor growth, invasion and metastasis. Hepatocyte growth factor (HGF) acts via the Met receptor and has also received research attention with ongoing efforts to develop treatments to block the Met receptor and its signal transduction pathways. Macrophage-stimulating protein (MSP), and its receptor Ron, is also recognized as important in the etiology of PC but is less well studied. Although the angiotensin II (AngII)/AT1 receptor system is best known for mediating blood pressure and body water/electrolyte balance, it also facilitates tumor vascularization and growth by stimulating the expression of VEGF. A metabolite of AngII, angiotensin IV (AngIV) has sequence homology with the “hinge regions” of HGF and MSP, key structures in the growth factor dimerization processes necessary for Met and Ron receptor activation. We have developed AngIV-based analogs designed to block dimerization of HGF and MSP and thus receptor activation. Norleual has shown promise as tested utilizing PC cell cultures. Results indicate that cell migration, invasion, and pro-survival functions were suppressed by this analog and tumor growth was significantly inhibited in an orthotopic PC mouse model.

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