Abstract P279: Human Angiotensin Receptor Gene Variations, Hypertension & Reno-Vascular Complications

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Sudhir Jain ◽  
Natalie Sirianni ◽  
Nitin Puri ◽  
Ahmed A Khudhair ◽  
Ashok Kumar
Keyword(s):  
Blood Pressure ◽  
Transcriptional Regulation ◽  
Gene Expression Regulation ◽  
Vascular System ◽  
Receptor Gene ◽  
Vascular Complications ◽  
Renin Angiotensin System ◽  
Organ Damage ◽  
Angiotensin Receptor

Angiotensin receptor type 1 (AT1R), a G-protein coupled receptor mediates the effect of angiotensin-II and contributes to the pathophysiological consequences of reno-vascular system. AT1R-signaling promotes renal sodium retention, vascular remodeling, hypertension, and end organ damage. Genetic variations that increase AT1R can cause pathological outcomes associated with renin angiotensin system overactivity. However, genetically variable, transcriptional regulation of the human AT1R gene is poorly understood. In this regard, the human AT1R gene has a haplotype block of four SNPs: T/A at -810, T/G at -713, A/C at -214, and A/G at -153 in its promoter. Variants -810T, -713T, -214A, and -153A always occur together (named haplotype-I or Hap-I) and variants -810A, -713G, -214C, and -153G always occur together (haplotype-II or Hap-II). We have found that hap-I is associated with hypertension in Caucasians. Thus, we generated transgenic (TG) mice with hap-II and I of the hAT1R gene to study its transcriptional regulation in vivo . TG mice with hap-I have higher baseline expression of hAT1R (3.9 folds) in the kidney with increased blood pressure (Hap-I, 126±3 vs. Hap II, 115±4). Since, diet-induced obesity is accompanied by systemic inflammation and redox imbalance that, in turn, alter the cellular transcriptional milieu, we gave Western diet (WD) treatment to our TG mice. Preliminary studies show that transcription factors like USF1, GR and STAT3 binds strongly (2.1; 2.3; 1.7 folds respectively Vs Hap-II) to increase hAT1R expression (5.8 folds) and resulting blood pressure (136±2 vs. 120±3 in Hap II) in TG-mice with hap-I, as compared to hap-II. Complementary experiments show increased inflammatory and redox markers in renal tissues of Hap-I mice, when compared to Hap-II, after WD; including, IL6 (5.9 fold), NOX1 (5.2 fold), CRP (9.8 fold), and TNFα (6.3 fold). Also, histochemical analysis of kidneys show an elevated pathology in Hap-I TG mice. Thus, haplotype-dependent transcriptional regulation of the hAT1R gene causes increased hAT1R expression and blood pressure, in Hap-I TG mice. Importantly, WD exacerbates this differential gene- expression regulation, further increasing hAT1R and promoting a pro-oxidant/inflammatory milieu in mice with Hap-I.

Abstract 021: Haplotype-Dependent Differential Regulation Of The Human AT1R Gene Is Exacerbated By Age: Effects On Tissue Inflammatory And Redox Milieu

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Anita Rana ◽  
Sudhir Jain ◽  
Nitin Puri ◽  
Brahmaraju Mopidevi ◽  
Meenakshi Kaw ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Transcriptional Regulation ◽  
Gene Expression Regulation ◽  
Artificial Chromosome ◽  
Organ Damage ◽  
Antioxidant Defenses ◽  
Renal Diseases ◽  
R Gene ◽  
Nucleotide Polymorphisms ◽  
Inflammatory Milieu

Age-associated inflammation and redox imbalance underlie etiopathogenesis of cardiovascular-renal diseases, including hypertension and end organ damage. Angiotensin II (Ang II), via activation of the AT1R, contributes to the development and progression of these pathophysiologies. We have identified two haplotype blocks of single nucleotide polymorphisms (SNPs) in the hAT 1 R gene: haplotype II (Hap II: -810A, -713G, -214C, -153G) and I (Hap I: -810T, -713T, -214A, -153A). In clinical studies, Hap I is linked to human hypertension. This study examines haplotype-dependent and age-associated transcriptional regulation of the hAT1R gene. In this regard, we have engineered transgenic (TG) mice with either haplotype of the hAT1R gene using a 166-kb bacterial artificial chromosome. ChIP assay shows increased RNA-Pol II binding (~1.6 fold higher) to the chromatin extracts from renal tissues of adult (4-6 months) male Hap I-TG mice with increased hAT1R expression (~6 fold higher). This was accompanied by higher baseline blood pressure in Hap I-TG mice (Hap I- 129±3 vs. Hap II- 116±4, p<0.05). Next, we examined the effects of age on this haplotype-dependent regulation of the hAT1R. Aged (>18 months), male mice were used for this part of the study. hAT1R expression increases with age in both haplotypes; however, this increase is significantly higher in Hap I-TG mice (3.17±0.5 to 5.5±0.75 fold) as opposed to mice with Hap II (1.1±0.2 to 1.8±0.1 fold). Age-associated change (Δ) in inflammatory and redox markers was significantly (p<0.05) greater in TG mice with Hap I including, IL1 (4.6±0.8 vs. 2.1±0.49 fold), IL6 (4.0±0.69 vs. 2.1±0.2 fold) and NOX1 (8.3±0.4 vs. 2.5±0.6 fold). This is accompanied by age-associated reduction in levels of antioxidant defenses (SOD1: 0.97±0.0 vs. 1.4±0.1 fold; HO1: 0.77±0.1 vs. 1.3±0.2 fold) and pro-survival genes including, NAMPTS (2.1 folds lower in Hap I vs. Hap II) and SIRT1 (1.8 fold lower in Hap I vs. Hap II). Thus, haplotype-dependent transcriptional regulation of the hAT 1 R gene causes increased hAT1R expression and blood pressure, in Hap I TG mice. Importantly, aging exacerbates this differential gene-expression regulation, further increasing hAT1R and promoting a prooxidant/inflammatory milieu in mice with Hap I.

scholarly journals Apparently normal kidney development in mice with conditional disruption of ANG II-AT1 receptor genes in FoxD1-positive stroma cell precursors

2019 ◽  
Vol 316 (6) ◽  
pp. F1191-F1200 ◽  
Author(s):  
Julia Schrankl ◽  
Bjoern Neubauer ◽  
Michaela Fuchs ◽  
Katharina Gerl ◽  
Charlotte Wagner ◽  
...  
Keyword(s):  
Kidney Development ◽  
Receptor Gene ◽  
Cell Lineage ◽  
Renin Angiotensin System ◽  
Plasma Renin ◽  
Cell Types ◽  
Ang Ii ◽  
Normal Kidney ◽  
And Function

An intact renin-angiotensin system involving ANG II type 1 (AT1) receptors is crucial for normal kidney development. It is still unclear in which cell types AT1 receptor signaling is required for normal kidney development, maturation, and function. Because all kidney cells deriving from stroma progenitor cells express AT1 receptors and because stromal cells fundamentally influence nephrogenesis and tubular maturation, we investigated the relevance of AT1 receptors in stromal progenitors and their descendants for renal development and function. For this aim, we generated and analyzed mice with conditional deletion of AT1A receptor in the FoxD1 cell lineage in combination with global disruption of the AT1B receptor gene. These FoxD1-AT1ko mice developed normally. Their kidneys showed neither structural nor functional abnormalities compared with wild-type mice, whereas in isolated perfused FoxD1-AT1ko kidneys, the vasoconstrictor and renin inhibitory effects of ANG II were absent. In vivo, however, plasma renin concentration and renal renin expression were normal in FoxD1-AT1ko mice, as were blood pressure and glomerular filtration rate. These findings suggest that a strong reduction of AT1 receptors in renal stromal progenitors and their descendants does not disturb normal kidney development.

Abstract P159: Scavengers of Isolevuglandins as Novel Therapeutic Approaches for Treating Hypertension & Associated Inflammation

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Wei Chen ◽  
Liang Xiao ◽  
Annet Kirabo ◽  
Danielle L Michell ◽  
Sean S Davies ◽  
...  
Keyword(s):  
Blood Pressure ◽  
T Lymphocytes ◽  
Antihypertensive Drugs ◽  
Study Drug ◽  
Organ Damage ◽  
Blue Staining ◽  
Ang Ii ◽  
Subsequent Activation ◽  
Oxidatively Modified

Adaptive immunity and especially T lymphocytes play a crucial role in the development of hypertension. Proteins that are oxidatively modified by highly reactive isolevuglandins (isoLGs) accumulate in dendritic cells & lead to subsequent activation of T lymphocytes. This process can be prevented by compounds known to scavenge isoLGs, such as 2-hydroxybenzylamine (2-HOBA). The overall goal of current study is to develop novel antihypertensive drugs based on this isoLG scavenging strategy, that will not only prevent but will also reverse hypertension and its associated inflammatory end-organ damage. Initially, the preventative effects of 10 putative isoLG scavengers were tested. C57Bl/6 mice received angiotensin (Ang) II (490 ng/kg/min) infusion for 14 days. Each compound was administered in the drinking water (1mg/ml) at the onset of Ang II infusion for 7 days to a half of the mice & for entire 14 day period to another half of the animals. Blood pressure was measured by tail cuff method. Among 10 compounds, we found that 2-HOBA, methyl 2HOBA (Me2HOBA) & 3-methoxy2-HOBA (3-Mo2HOBA) were most effective in lowering blood pressure. Interestingly, the pyridoxamine analogs were not effectively lowered blood pressure. We further examined the efficacy of our 3 most effective compounds in reversing established hypertension. Mice received Ang II infusion for 6 weeks and received each study drug (2 mg/ml) during the last 4 weeks. We employed radiotelemetry to monitor blood pressure. Compared with untreated mice, Me2-HOBA, 3-Mo2-HOBA & 2-HOBA were equally effective in lowering blood pressure by 20 mmHg (all p < 0.05 vs no drug). Six weeks of Ang II infusion caused 2- to 4-fold increases in renal T cell (CD3 + ) & monocyte/macrophage (F4/80 + ) infiltration as measured by immunohistochemistry & all three compounds markedly reduced these by 50%. These treatments also reduced aortic fibrosis as measured by Masson’s Trichrome blue staining. We conclude that these isoLG scavengers can be potentially used as new effective therapy for lowering blood pressure & attenuating hypertensive renal & vascular damage. Variability of in vivo effectiveness for the different scavengers likely reflects differences in bioavailability due to structure & lypophilicity.

Abstract 443: Androgen-Sensitive Hypertension in Adult mRen2.Lewis Rats

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Emma H Trimmer ◽  
Sarah H Lindsey
Keyword(s):  
Blood Pressure ◽  
Body Weight ◽  
Critical Role ◽  
Renin Angiotensin System ◽  
Organ Damage ◽  
Heart Weight ◽  
Adult Males ◽  
Adult Rats ◽  
End Organ Damage ◽  
The Impact

The mRen2.Lewis (mRen2) rat is an angiotensin II-dependent model of hypertension that displays marked sex differences in systolic blood pressure (SBP). Gonadectomy (GDX) of young female mRen2 rats significantly increases SBP; however, the role of androgens has not been assessed. In addition, the impact of GDX in adult rats with well-established hypertension is not known. Therefore, the current study assessed the impact of adult gonadectomy (GDX; 17 weeks of age) on established hypertension and associated end organ damage in mRen2 rats. Baseline SBP at 16 weeks of age was not different between male groups (214 ± 13 mmHg, n=5 vs. 224 ± 3 mmHg, n=3, P>0.05) but was significantly lower in females (143 ± 9 mmHg, n=3, P<0.01). GDX significantly lowered SBP in males after one week (159 ± 13 mmHg, P<0.001), and SBP remained lower until 25 weeks of age (169 ± 9 mmHg, P<0.05). The lower SBP in GDX males was associated with a significant reduction in kidney weight (3.1 ± 0.02 vs. 2.9 ± 0.06 mg/g body weight, P<0.05), heart weight (4.1 ± 0.10 vs. 3.4 ± 0.12 mg/g body weight, P<0.01), and proteinuria (53 ± 7 vs. 20 ± mg/kg/day, P<0.01) at 25 weeks of age. Proteinuria in GDX males remained significantly higher in comparison to GDX females (3.9 ± 0.6 mg/kg/day, P<0.01). In summary, GDX of adult male but not female mRen2 rats had a significant and rapid impact on blood pressure and was associated with a reduction in end organ damage. When combined with our previous work in the female mRen2 rat, we conclude that estrogens may play a critical role in the development of hypertension in younger females, while androgens apparently contribute to the maintenance of blood pressure in adult males. This animal model may be relevant to discern the complex relationships between sex hormones, hypertension, and tissue damage. Future studies will establish the molecular pathways by which each of these steroid hormones interacts with the renin-angiotensin system to modulate blood pressure in the mRen2 strain.

Transcriptional regulation of breathless FGF receptor gene by binding of TRACHEALESS/dARNT heterodimers to three central midline elements in Drosophila developing trachea

Development ◽  
1997 ◽  
Vol 124 (20) ◽  
pp. 3975-3986 ◽  
Author(s):  
T. Ohshiro ◽  
K. Saigo
Keyword(s):  
Transcriptional Regulation ◽  
Protein Complexes ◽  
Receptor Gene ◽  
Fgf Receptor ◽  
Enhancer Region ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Target Sites ◽  
Drosophila Trachea

The development of Drosophila trachea is under the control of spatially and/or quantitatively regulated activity of BREATHLESS FGF receptor, which is also essential for midline glial migration. Here, we identified the minimum enhancer region of breathless, cloned the Drosophila ARNT gene (dARNT), and showed biochemical and genetic evidence that breathless expression in developing trachea is regulated by direct interactions between TRACHEALESS/dARNT heterodimers and three central midline elements (TACGTGs) situated in the minimum enhancer region. Our results also showed that SINGLE-MINDED/dARNT heterodimers, which are essential for breathless expression in midline precursor cells, share DNA targets in common with TRACHEALESS/dARNT, indicating that two different basic helix-loop-helix-PAS protein complexes act through the same target sites in vivo.

Abstract P192: AT1R Blockade Increases the Depressor Effect of Alamandine in Normotensive SD Rats

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Giovanni Canta ◽  
Roberto Lautner ◽  
Robson Santos
Keyword(s):  
Blood Pressure ◽  
Biological Effects ◽  
Femoral Vein ◽  
Blood Pressure Measurement ◽  
Critical Role ◽  
Renin Angiotensin System ◽  
Dependent Manner ◽  
Sd Rats ◽  
Depressor Effect

The renin–angiotensin system (RAS) plays a critical role in blood pressure control and electrolyte homeostasis. It has been established that Ang II is not the only active peptide of the RAS. Recently, new active fragments formed through metabolism of the classical axis peptides have been identified and their biological effects characterized. One of these peptides, is Alamandine, which was described by our group. Here we investigate the effect of Alamandine on blood pressure in non-anesthetized SD rats. To study the in vivo effects of this peptide, we used 12 weeks old SD rats (300-400 g). Administration of drugs and the blood pressure measurement were performed with a cannula inserted through the femoral vein and artery, respectively. We administered Alamandine with bolus injections (0.02, 0.2 ,1 ,5, 20 and 80 ng). A biphasic effect of alamandine was observed. The greatest depressor effect of Alamandine was observed at a lower dose, 1 ng. (Δ MAP: - 10.33±0.85 mmHg p <0.05). On the other hand, the highest dose, 80 ng, did not change significantly the blood pressure. Interestingly, when Losartan (5mg/kg) was administered 30min before the injection of alamandine, the depressor effect of this peptide was increased, mainly at 0.2 ng (Δ MAP: - 6±1.05 mmHg Alamandine vs. Δ MAP: - 20.33 ± 2,34 mmHg Alamandine after Losartan p <0.05). In losartan treated rats only depressor response were observed with all doses. In conclusion, our data show that Alamandine has a biphasic effects on blood pressure and seems to interact whith AT1 receptor in a dose - dependent manner.

Over-Expression of the Mas Receptor Decreases Arterial Thrombosis Risk in B2R KO Mice by Elevating NO and Prostacyclin and Reducing GPVI Activation

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 700-700
Author(s):  
Chao Fang ◽  
Evi Stavrou ◽  
Alec A Schmaier ◽  
Gregory N Adams ◽  
Marvin T. Nieman ◽  
...  
Keyword(s):  
Renin Angiotensin System ◽  
Angiotensin Receptor ◽  
Angiotensin System ◽  
Over Expression ◽  
Mas Receptor ◽  
Artery Thrombosis ◽  
Thrombosis Risk ◽  
Function Defect ◽  
Losartan Treatment

Abstract Abstract 700 Background: Bradykinin B2 receptor KO mice (B2R KO) were recognized to have delayed rose bengal and ferric chloride carotid artery thrombosis times and long tail bleeding times. In B2R KO, elevated serum angiotensin II (AngII) binds to an over-expressed angiotensin receptor 2 (AT2R) to increase plasma NO and prostacyclin (Blood 108:192, 2006). It was proposed that the combined presence of elevated AngII and AT2R are essential for the thrombosis protection phenotype. However, after losartan treatment, an angiotensin receptor 1 antagonist, thrombosis remains delayed in B2R KO despite reduction in AngII levels from 258±64 to 40±15 pg/ml. An additional pathway for thrombosis protection in B2R KO mice was sought. Methods and Results: Losartan treatment lowers ACE mRNA in mice along with lowering AngII levels. However, even in the presence of low AngII levels, plasma Ang1-7 levels, the breakdown product of AngII, in losartan-treated B2R KO are increased [21±2.2 pg/ml vs 14.4±0.7 pg/ml in wild type mice (WT)]. Upon examination, B2R KO also have elevated Mas mRNA, the receptor for angiotensin1-7, with over-expressed renal Mas protein. Treatment of B2R KO with A-779, a Mas antagonist, shortens carotid artery thrombosis time (58±4 to 38±4 min) and tail bleeding time (170±13 to 88±8 sec) and lowers plasma concentrations of nitrate (from 21.5±3.6 micromolar in untreated B2R KO to 15±5 micromolar in A-779-treated mice) and 6-keto-PGF1alpha (259±103 pg/ml in untreated B2R KO to 132±58 pg/ml). ADP- or thrombin-induced platelet (plt) activation are not abnormal in B2R KO, either by aggregation studies or by flow cytometric studies examining for fibrinogen binding or JON/A integrin epitope binding and P-Selectin expression, respectively. Although static and flow adherence to collagen was normal, B2R KO plts have defective spreading on collagen (20±0.6 microns in B2R KO versus 27±0.4 microns in WT, p<0.0001) under static conditions. Resting B2R KO plts constitutively also have increased DAF-FM fluorescence (649±41 AFU versus 405±36 AFU, p=0.0012), suggesting increased plt NO without stimulation. GSNO, an NO donor, or carbaprostacyclin, a stable derivative of prostacyclin, inhibits murine plt spreading on collagen in a concentration-dependent manner. B2R KO plts have reduced GPVI activation using CRP or convulxin even though GPVI expression on B2R KO and WT plts are similar. Further, B2R KO plts have reduced Syk phosphorylation after convulxin stimulation and reduced phosphorylation of Src family kinases when spreading on collagen. Treatment of B2R KO plts in vivo with A-779 corrects the spreading and Src family kinase phosphorylation defects upon collagen exposure, suggesting an in vivo role of the Mas receptor in the plt function defect and thrombosis delay. Conclusion: B2R KO are protected from thrombosis by over-expression of two receptors (AT2R and Mas) from the renin-angiotensin system resulting in increased NO and prostacyclin and an acquired platelet function defect. The receptors AT2R and MAS compensate for the absence of the B2R. These studies show novel mechanism(s) whereby receptors in the renin-angiotensin system influence platelet function and arterial thrombosis risk in vivo. Disclosures: No relevant conflicts of interest to declare.

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