scholarly journals Long‐term interactions between the ACE/Ang II/AT1a receptor axis and the ACE2/Ang(1–7)/Mas receptor axis in wild‐type C57BL/6J and AT1a receptor‐knockout mice

2012 ◽  
Vol 26 (S1) ◽  
Author(s):  
Brianne Nicole Ellis ◽  
Xiao C Li ◽  
Elisa Miguel-Qin ◽  
Jia L Zhuo
Keyword(s):  
Knockout Mice ◽  
Ang Ii ◽  
Wild Type ◽  
Mas Receptor ◽  
At1a Receptor

Changes in angiotensin type 1 receptor binding and angiotensin-induced pressor responses in the rostral ventrolateral medulla of angiotensinogen knockout mice

2010 ◽  
Vol 298 (2) ◽  
pp. R411-R418 ◽  
Author(s):  
Daian Chen ◽  
Lisa Hazelwood ◽  
Lesley L. Walker ◽  
Brian J. Oldfield ◽  
Michael J. McKinley ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Receptor Binding ◽  
Knockout Mice ◽  
Pressor Response ◽  
Ventrolateral Medulla ◽  
Ang Ii ◽  
Wild Type ◽  
Intravenous Injections ◽  
Angiotensin Type

ANG II, the main circulating effector hormone of the renin-angiotensin system, is produced by enzymatic cleavage of angiotensinogen. The present study aimed to examine whether targeted deletion of the angiotensinogen gene ( Agt) altered brain ANG II receptor density or responsiveness to ANG II. In vitro autoradiography was used to examine the distribution and density of angiotensin type 1 (AT1) and type 2 receptors. In most brain regions, the distribution and density of angiotensin receptors were similar in brains of Agt knockout mice ( Agt −/− ) and wild-type mice. In Agt −/− mice, a small increase in AT1 receptor binding was observed in the rostral ventrolateral medulla (RVLM), a region that plays a critical role in blood pressure regulation. To examine whether Agt −/− mice showed altered responses to ANG II, blood pressure responses to intravenous injection (0.01–0.1 μg/kg) or RVLM microinjection (50 pmol in 50 nl) of ANG II were recorded in anesthetized Agt −/− and wild-type mice. Intravenous injections of phenylephrine (4 μg/kg and 2 μg/kg) were also made in both groups. The magnitude of the pressor response to intravenous injections of ANG II or phenylephrine was not different between Agt −/− and wild-type mice. Microinjection of ANG II into the RVLM induced a pressor response, which was significantly smaller in Agt −/− compared with wild-type mice (+10 ± 1 vs. +23 ± 4 mmHg, respectively, P = 0.004). Microinjection of glutamate into the RVLM (100 pmol in 10 nl) produced a robust pressor response, which was not different between Agt −/− and wild-type mice. A diminished response to ANG II microinjection in the RVLM of Agt −/− mice, despite an increased density of AT1 receptors suggests that signal transduction pathways may be altered in RVLM neurons of Agt −/− mice, resulting in attenuated cellular excitation.

scholarly journals Chemokine Receptor CXCR-2 Initiates Atrial Fibrillation by Triggering Monocyte Mobilization in Mice

Hypertension ◽  
2020 ◽  
Vol 76 (2) ◽  
pp. 381-392 ◽  
Author(s):  
Yun-Long Zhang ◽  
Hua-Jun Cao ◽  
Xiao Han ◽  
Fei Teng ◽  
Chen Chen ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Bone Marrow ◽  
Chemokine Receptor ◽  
Knockout Mice ◽  
Bone Marrow Cells ◽  
Atrial Remodeling ◽  
Dependent Manner ◽  
Ang Ii ◽  
Wild Type ◽  
Chemokine Ligands

Atrial fibrillation (AF) is frequently associated with increased inflammatory response characterized by infiltration of monocytes/macrophages. The chemokine receptor CXCR-2 is a critical regulator of monocyte mobilization in hypertension and cardiac remodeling, but it is not known whether CXCR-2 is involved in the development of hypertensive AF. AF was induced by infusion of Ang II (angiotensin II; 2000 ng/kg per minute) for 3 weeks in male C57BL/6 wild-type mice, CXCR-2 knockout mice, bone marrow-reconstituted chimeric mice, and mice treated with the CXCR-2 inhibitor SB225002. Microarray analysis revealed that 4 chemokine ligands of CXCR-2 were significantly upregulated in the atria during 3 weeks of Ang II infusion. CXCR-2 expression and the number of CXCR2 + immune cells markedly increased in Ang II–infused atria in a time-dependent manner. Moreover, Ang II–infused wild-type mice had increased blood pressure, AF inducibility, atrial diameter, fibrosis, infiltration of macrophages, and superoxide production compared with saline-treated wild-type mice, whereas these effects were significantly attenuated in CXCR-2 knockout mice and wild-type mice transplanted with CXCR-2-deficient bone marrow cells or treated with SB225002. Moreover, circulating blood CXCL-1 levels and CXCR2 + monocyte counts were higher and associated with AF in human patients (n=31) compared with sinus rhythm controls (n=31). In summary, this study identified a novel role for CXCR-2 in driving monocyte infiltration of the atria, which accelerates atrial remodeling and AF after hypertension. Blocking CXCR-2 activation may serve as a new therapeutic strategy for AF.

scholarly journals Protease-independent action of tissue plasminogen activator in brain plasticity and neurological recovery after ischemic stroke

2019 ◽  
Vol 116 (18) ◽  
pp. 9115-9124 ◽  
Author(s):  
Hongjian Pu ◽  
Yejie Shi ◽  
Lili Zhang ◽  
Zhengyu Lu ◽  
Qing Ye ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Plasminogen Activator ◽  
Knockout Mice ◽  
Protease Activity ◽  
Brain Plasticity ◽  
Neurological Recovery ◽  
Egfr Signaling ◽  
Wild Type ◽  
Tissue Plasminogen

Emerging evidence suggests that tissue plasminogen activator (tPA), currently the only FDA-approved medication for ischemic stroke, exerts important biological actions on the CNS besides its well-known thrombolytic effect. In this study, we investigated the role of tPA on primary neurons in culture and on brain recovery and plasticity after ischemic stroke in mice. Treatment with recombinant tPA stimulated axonal growth in culture, an effect independent of its protease activity and achieved through epidermal growth factor receptor (EGFR) signaling. After permanent focal cerebral ischemia, tPA knockout mice developed more severe sensorimotor and cognitive deficits and greater axonal and myelin injury than wild-type mice, suggesting that endogenously expressed tPA promotes long-term neurological recovery after stroke. In tPA knockout mice, intranasal administration of recombinant tPA protein 6 hours poststroke and 7 more times at 2 d intervals mitigated white matter injury, improved axonal conduction, and enhanced neurological recovery. Consistent with the proaxonal growth effects observed in vitro, exogenous tPA delivery increased poststroke axonal sprouting of corticobulbar and corticospinal tracts, which might have contributed to restoration of neurological functions. Notably, recombinant mutant tPA-S478A lacking protease activity (but retaining the EGF-like domain) was as effective as wild-type tPA in rescuing neurological functions in tPA knockout stroke mice. These findings demonstrate that tPA improves long-term functional outcomes in a clinically relevant stroke model, likely by promoting brain plasticity through EGFR signaling. Therefore, treatment with the protease-dead recombinant tPA-S478A holds particular promise as a neurorestorative therapy, as the risk for triggering intracranial hemorrhage is eliminated and tPA-S478A can be delivered intranasally hours after stroke.

scholarly journals Angiotensin II stimulates superoxide production in the thick ascending limb by activating NOX4

2012 ◽  
Vol 303 (7) ◽  
pp. C781-C789 ◽  
Author(s):  
Katherine J. Massey ◽  
Nancy J. Hong ◽  
Jeffrey L. Garvin
Keyword(s):  
Angiotensin Ii ◽  
Nadph Oxidase ◽  
Knockout Mice ◽  
Thick Ascending Limb ◽  
Ang Ii ◽  
Wild Type ◽  
Outer Medulla ◽  
Catalytic Subunits ◽  
In The Wild

Angiotensin II (ANG II) stimulates production of superoxide (O2−) by NADPH oxidase (NOX) in medullary thick ascending limbs (TALs). There are three isoforms of the catalytic subunit (NOX1, 2, and 4) known to be expressed in the kidney. We hypothesized that NOX2 mediates ANG II-induced O2− production by TALs. To test this, we measured NOX1, 2, and 4 mRNA and protein by RT-PCR and Western blot in TAL suspensions from rats and found three catalytic subunits expressed in the TAL. We measured O2− production using a lucigenin-based assay. To assess the contribution of NOX2, we measured ANG II-induced O2− production in wild-type and NOX2 knockout mice (KO). ANG II increased O2− production by 346 relative light units (RLU)/mg protein in the wild-type mice ( n = 9; P < 0.0007 vs. control). In the knockout mice, ANG II increased O2− production by 290 RLU/mg protein ( n = 9; P < 0.007 vs. control). This suggests that NOX2 does not contribute to ANG II-induced O2− production ( P < 0.6 WT vs. KO). To test whether NOX4 mediates the effect of ANG II, we selectively decreased NOX4 expression in rats using an adenovirus that expresses NOX4 short hairpin (sh)RNA. Six to seven days after in vivo transduction of the kidney outer medulla, NOX4 mRNA was reduced by 77%, while NOX1 and NOX2 mRNA was unaffected. In control TALs, ANG II stimulated O2− production by 96%. In TALs transduced with NOX4 shRNA, ANG II-stimulated O2− production was not significantly different from the baseline. We concluded that NOX4 is the main catalytic isoform of NADPH oxidase that contributes to ANG II-stimulated O2− production by TALs.

scholarly journals Angiotensin II-dependent phosphorylation at Ser11/Ser18 and Ser938 shifts the E2 conformations of rat kidney Na+/K+-ATPase

2012 ◽  
Vol 443 (1) ◽  
pp. 249-258 ◽  
Author(s):  
Katherine J. Massey ◽  
Quanwen Li ◽  
Noreen F. Rossi ◽  
Raymond R. Mattingly ◽  
Douglas R. Yingst
Keyword(s):  
Angiotensin Ii ◽  
Plasma Membranes ◽  
Rat Kidney ◽  
Second Phase ◽  
Ang Ii ◽  
Wild Type ◽  
Opossum Kidney ◽  
Opossum Kidney Cells ◽  
Two Phases ◽  
At1a Receptor

Kidney plasma membranes, which contain a single α-1 isoform of Na+/K+-ATPase, simultaneously contain two sub-conformations of E2P, differing in their rate of digoxin release in response to Na+ and ATP. Treating cells with Ang II (angiotensin II) somehow changes the conformation of both, because it differentially inhibits the rate of digoxin release. In the present study we tested whether Ang II regulates release by increasing phosphorylation at Ser11/Ser18 and Ser938. Opossum kidney cells co-expressing the AT1a receptor and either α-1.wild-type, α-1.S11A/S18A or α-1.S938A were treated with or without 10 nM Ang II for 5 min, increasing phosphorylation at the three sites. Na+/K+-ATPase was bound to digoxin-affinity columns in the presence of Na+, ATP and Mg2+. A solution containing 30 mM NaCl and 3 mM ATP eluted ~20% of bound untreated Na+/K+-ATPase (Population #1). Pre-treating cells with Ang II slowed the elution of Population #1 in α-1.wild-type and α-1.S938A, but not α-1.S11A/S18A cells. Another 50% of bound Na+/K+-ATPase (Population #2) was subsequently eluted in two phases by a solution containing 150 mM NaCl and 3 mM ATP. Ang II increased the initial rate and slowed the second phase in α-1.wild-type, but not α-1.S938A, cells. Thus Ang II changes the conformation of two forms of EP2 via differential phosphorylation.

Genomics of cardiac remodeling in angiotensin II-treated wild-type and LOX-1-deficient mice

2010 ◽  
Vol 42 (1) ◽  
pp. 42-54 ◽  
Author(s):  
Bum-Yong Kang ◽  
Changping Hu ◽  
Sunhyo Ryu ◽  
Junaid A. Khan ◽  
Michela Biancolella ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Expression Profile ◽  
Expression Profile ◽  
Knockout Mice ◽  
Cardiac Remodeling ◽  
Oxidant Stress ◽  
Reactive Oxygen Species Generation ◽  
Cardiac Response ◽  
Ang Ii ◽  
Wild Type

We studied the gene expression profile during cardiac hypertrophy induced by angiotensin (ANG) II in wild-type mice and the influence of LOX-1 deletion on the gene expression profile. Wild-type and LOX-1 knockout mice were given saline or ANG II infusion for 4 wk. The saline-treated LOX-1 knockout mice showed upregulation of several genes including Ddx3y and Eif2s3y. ANG II infusion enhanced expression of genes known to be associated with cardiac remodeling, such as Agt, Ace, Timp4, Fstl, and Tnfrst12a, as well as oxidant stress-related genes Gnaq, Sos1, and Rac1. Some other strongly upregulated genes identified in this study have not been previously associated with LOX-1 deletion and/or hypertension. To confirm these observations with ANG II infusion and LOX-1 deletion, cultured HL-1 mouse cardiomyocytes were exposed to ANG II or transfected with pCI-neo/LOX-1, which resulted in severalfold increase in reactive oxygen species generation, upregulation of ANG II type 1 (AT1) receptor, and cardiomyocyte growth. Quantitative PCR analysis of these treated cardiomyocytes confirmed upregulation of many of the genes identified in the in vivo study. This study provides the first set of data on the gene expression profiling of cardiac tissue treated with ANG II and expands on the important role of LOX-1 in cardiac response to ANG II.

Abstract 639: Angiotensin 1-7 Contributes To Cardioprotective Effects Of Cardiac Overexpression Of Angiotensin II Type 2 Receptor In Mice Post-MI

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Jiang Xu ◽  
Oscar A Carretero ◽  
Liping Zhu ◽  
Pamela Harding ◽  
Nour-Eddine Rhaleb ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Capillary Density ◽  
Left Ventricular ◽  
Ang Ii ◽  
Wild Type ◽  
Cross Sectional ◽  
Mas Receptor ◽  
Cardioprotective Effects ◽  
Mini Pump

Angiotensin II (Ang II) acting on AT1 receptor plays a pivotal role in the pathophysiology of cardiovascular disease, whereas AT2 has been considered cardioprotective, although the mechanisms are not fully understood. Recently studies suggest AT2 interacts with ACE2, an enzyme known to release Ang 1-7 from Ang II. Thus we hypothesize that Ang 1-7 contributes to cardioprotective effects of AT2, possibly via AT2/ACE2/Ang 1-7 cascade. Transgenic mice with AT2 specifically overexpressed in the heart (Tg-AT2) and their wild-type littermates (WT) were subjected to myocardial infarction (MI) or sham MI and divided into 1) sham MI; 2) MI + vehicle; and 3) MI + Mas receptor antagonist ([D-Ala7-Ang 1-7], A779, 0.5 mg/kg/day via osmotic mini pump). Treatments were started on the same day of MI and continued for 8 weeks. Our data show that AT2 and ACE2 protein expression in the heart was significantly increased in Tg-AT2 mice, whereas AT1 protein remained unchanged. Systolic blood pressure (SBP) and cardiac phenotypes did not differ between strains under basal conditions. MI increased myocyte cross-sectional area (MCSA), interstitial collagen fraction (ICF), left ventricular diastolic dimension (LVDd) and capillary density, and decreased LV ejection fraction (EF) in both strains; however, these pathological responses were diminished in Tg-AT2. Blockade of Mas receptor with A779 attenuated the cardioprotective effects observed in Tg-AT2 mice (Table). Infarct size (IS) did not differ among groups. Our findings suggest that overexpression/activation of AT2 protects against cardiac remodeling and dysfunction post MI, which is mediated in part through Ang 1-7 acting on the Mas receptor.

scholarly journals In vivo regulation of AT1a receptor-mediated intracellular uptake of [125I]Val5-ANG II in the kidneys and adrenals of AT1a receptor-deficient mice

2008 ◽  
Vol 294 (2) ◽  
pp. F293-F302 ◽  
Author(s):  
Xiao C. Li ◽  
Jia L. Zhuo
Keyword(s):  
Adrenal Glands ◽  
Physiological Role ◽  
Intracellular Uptake ◽  
Ang Ii ◽  
Angiotensin Receptor ◽  
Wild Type ◽  
In Vivo Autoradiography ◽  
At1a Receptor ◽  
Deficient Mice

Using type 1a angiotensin receptor (AT1a) receptor-deficient (Agtr1a−/−) mice and in vivo autoradiography, we tested the hypothesis that intracellular uptake of ANG II in the kidney and adrenal glands is primarily mediated by AT1a receptors and that the response is regulated by prevailing endogenous ANG II. After pretreatment of wild-type (Agtr1a+/+) and Agtr1a−/− mice ( n = 6–9 each group) with or without captopril (25 mg·kg−1·day−1) or losartan (10 mg·kg−1·day−1) for 2 wk, [125I]Val5-ANG II was infused for 60 min. Intracellular uptake of [125I]Val5-ANG II was determined by quantitative in vivo autoradiography after washout of circulating [125I]Val5-ANG II. Basal intracellular ANG II levels were 65% lower in the kidney ( P < 0.001), but plasma ANG II levels were threefold higher, in Agtr1a−/− than wild-type mice ( P < 0.01). Although plasma [125I]Val5-ANG II levels were similar, urinary excretion of [125I]Val5-ANG II was fourfold higher in Agtr1a−/− mice ( P < 0.001). By contrast, intracellular [125I]Val5-ANG II levels were ∼80% lower in the kidney and adrenal glands of Agtr1a−/− mice ( P < 0.01). Captopril decreased endogenous plasma and renal ANG II levels ( P < 0.01) but increased intracellular uptake of [125I]Val5-ANG II in the kidney and adrenal glands of wild-type and Agtr1a−/− mice ( P < 0.01). Losartan largely blocked renal and adrenal uptake of [125I]Val5-ANG II in wild-type and Agtr1a−/− mice. Thus 80% of intracellular ANG II uptake in the kidney and adrenal glands is mediated by AT1a receptors, whereas AT1b receptor- and other non-receptor-mediated mechanisms account for 20% of the response. Our results suggest that AT1a receptor-mediated uptake of extracellular ANG II may play a physiological role in the kidney and adrenal glands.

scholarly journals Role of TNFR1 and TNFR2 receptors in tubulointerstitial fibrosis of obstructive nephropathy

1999 ◽  
Vol 277 (5) ◽  
pp. F766-F772 ◽  
Author(s):  
Guangjie Guo ◽  
Jeremiah Morrissey ◽  
Ruth McCracken ◽  
Timothy Tolley ◽  
Saulo Klahr
Keyword(s):  
Knockout Mice ◽  
Ureteral Obstruction ◽  
Collagen Iv ◽  
Tubulointerstitial Fibrosis ◽  
Kidney Cortex ◽  
Mrna Levels ◽  
Ang Ii ◽  
Wild Type ◽  
Interstitial Volume ◽  
Tnf Α

Unilateral ureteral obstruction (UUO) results in tubulointerstitial fibrosis of the obstructed kidney. In this study, we report the contribution of tumor necrosis factor-α (TNF-α) to the fibrosis that develops after ureteral obstruction. Mice in which individual TNF-α receptors TNFR1 or TNFR2 had been genetically knocked out were used, and results were compared with mice of C57Bl/6 background after 5 days UUO. Both kidneys were removed and examined histologically for changes in interstitial volume (Vvint), collagen IV deposition, α-smooth muscle actin (α-SMA) matrix score, nuclear factor-κB (NF-κB) activity, and TNF-α mRNA levels. We found that the Vvint of contralateral unobstructed kidneys averaged ∼7% and was indistinguishable among the three genotypes of mice. Vvintof ureteral obstructed kidney of C57Bl/6 mice averaged 33 ± 3.9% after 5 days of UUO. Vvint of obstructed kidneys of TNFR1 mice was significantly reduced to 19.4 ± 3.1%, whereas that of TNFR2 mice was significantly decreased to 25.4% ± 4.8%. There was a modest but significant difference between Vvint of TNFR1 and TNFR2 ( P < 0.047). Both collagen IV and α-SMA matrix scores were decreased significantly in obstructed kidney of TNFR1 mouse compared with that of C57Bl/6 and TNFR2 mice. Nuclear extracts prepared from kidney cortex were found to have a significant increase in NF-κB binding activity in obstructed kidney compared with contralateral kidney. Individual knockout of the TNFR1 or TNFR2 genes resulted in significantly less NF-κB activation compared with the wild type, with TNFR1 being less than TNFR2 knockout. There was a significant increase in TNF-α mRNA in the kidney with ureteral obstruction in all three genotypes. TNFR1 knockout displayed a significant reduction in amount of TNF-α mRNA induced compared with wild-type or TNFR2 knockout mice. Treatment of TNFR1 knockout mice with an angiotensin converting enzyme inhibitor further decreased Vvint and TNF-α mRNA induction, suggesting an interaction of ANG II and TNF-α systems. These results suggest that TNF-α contributes, in part, to changes in interstitial volume, myofibroblast differentiation, and NF-κB activation in the kidney during ureteral obstruction. These changes appear to be mediated through both TNFR1 and TNFR2 gene products with effects through the TNFR1 receptor predominating. Furthermore, ANG II appears to stimulate TNF-α pathophysiological events leading to renal fibrosis.

Sign in / Sign up

Export Citation Format

Share Document