Effect of AGTR1 A1166C genetic polymorphism on coronary artery lesions and mortality in patients with acute myocardial infarction.

The pathogenesis and prognosis of patients with acute myocardial infarction (AMI) may be influenced by both genetic and environmental factors. Findings on the relationship of polymorphisms in various genes encoding the renin-angiotensin-aldosterone system with coronary artery lesions and mortality in AMI patients are inconsistent. The aim of this study was to determine whether the AGTR1 A1166C genetic polymorphism affects coronary artery lesions and 1-year mortality in post-AMI patients. Patients with their first AMI admitted to Cho Ray Hospital, Vietnam, from January 2020 to August 2021 were enrolled in this prospective clinical study. All participants underwent invasive coronary angiography and were identified as having the genotypes of AGTR1 A1166C by way of a polymerase chain reaction method. All patients were followed up for all-cause mortality 12 months after AMI. The association of the AGTR1 A1166C polymorphism with coronary artery lesions and 1-year mortality was evaluated using logistic regression and Cox regression analysis, respectively. Five hundred and thirty-one AMI patients were recruited. The mean age was 63.9 ± 11.6 years, and 71.6% of the patients were male. There were no significant differences in the location and number of diseased coronary artery branches between the AA and AC+CC genotypes. The AC and CC genotypes were independently associated with ≥ 90% diameter stenosis of the left anterior descending (LAD) artery (odds ratio = 1.940; 95% confidence interval (CI): 1.059-3.552, p = 0.032). The 1-year all-cause mortality rate difference between patients with the AC and CC genotypes versus those with the AA genotype was not statistically significant (hazard ratio = 1.000, 95% CI: 0.429-2.328, p = 1.000). The AGTR1 A1166C genetic polymorphism is associated with very severe luminal stenosis of the LAD but not with mortality in AMI patients.

Genetic Variations of Angiotensinogen, Angiotensin Converting Enzyme, and Angiotensin Type 1 Receptor with the Risk of Pulmonary Tuberculosis.

There is little data regarding the impact of renin-angiotensin system (RAS) gene polymorphisms on tuberculosis. The current study designed to survey the possible association between RAS polymorphisms and the risk of pulmonary tuberculosis (PTB) in a sample of the southeast Iranian population. This case-control study was done on 170 PTB patients and 170 healthy subjects. The AGT rs699 C>T, ACE rs4341 C>G and AT1R rs5186 C>A variants were genotyped using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and ACE rs4646994 (287bp I/D) variant by PCR method. Regarding AT1R rs5186 A>C polymorphism, the findings revealed that AC genotype and C allele significantly decreased the risk of PTB (OR=0.39, 95% CI=0.22-0.67, p=0.001, and OR=0.53, 95% CI=0.25-0.72, p=0.002, C vs. A, respectively). The TC genotype and C allele of AGT rs699 T>C significantly associated with decreased the risk of PTB (OR=0.45, 95% CI=0.28-0.74, p=0.002, TC vs. TT and OR=0.51, 95% CI=0.32-0.80, p=0.005, C vs. T, respectively). The ID genotype of ACE 287bp I/D significantly increased the risk of PTB (OR=1.88, 95% CI=1.12-3.17, p=0.017). Our finding did not support an association between ACE rs4341 C>G variant and the risk of PTB. In summary, the findings revealed an association between AT1R rs5186 A>C, AGT rs699 T>C and ACE 287bp I/D polymorphisms and the risk of PTB in a sample of the southeast Iranian population. Further investigation with higher sample sizes and diverse ethnicities are required to confirm our findings.

The central renin-angiotensin system: A genetic pathway, functional decoding, and selective target engagement characterization in humans.

Accumulating evidence suggests that the brain renin angiotensin system (RAS) plays a pivotal role in the regulation of cognition and behavior as well as in the neuropathology of neurological and mental disorders. The angiotensin II type 1 receptor (AT1R) mediates most functional and neuropathology-relevant actions associated with the central RAS. However, an overarching comprehension to guide translation and utilize the therapeutic potential of the central RAS in humans is currently lacking. We conducted a comprehensive characterization of the RAS using an innovative combination of transcriptomic gene expression mapping, image-based behavioral decoding, and pre-registered randomized controlled discovery-replication pharmacological resting-state functional magnetic resonance imaging (fMRI) trials (N = 132) with a selective AT1R antagonist. The AT1R exhibited a particular dense expression in a subcortical network encompassing the thalamus, striatum, and amygdalo-hippocampal formation. Behavioral decoding of the AT1R gene expression brain map showed an association with memory, stress, reward, and motivational processes. Transient pharmacological blockade of the AT1R further decreased neural activity in subcortical systems characterized by a high AT1R expression, while increasing functional connectivity in the cortico-basal ganglia-thalamo-cortical circuitry. Effects of AT1R blockade on the network level were specifically associated with the transcriptomic signatures of the dopaminergic, opioid, acetylcholine, and corticotropin-releasing hormone signaling systems. The robustness of the results was supported in an independent pharmacological fMRI trial. These findings present a biologically informed comprehensive characterization of the central AT1R pathways and their functional relevance on the neural and behavioral level in humans.

Impact of the gene polymorphisms in the renin-angiotensin system on cardiomyopathy risk: A meta-analysis.

Due to the inconsistent findings from various studies, the role of gene polymorphisms in the renin-angiotensin system in influencing the development of cardiomyopathy remains unclear. In this study, we conducted a systematic review and meta-analysis to summarize the findings regarding the impact of angiotensin converting enzyme (ACE) I/D, angiotensinogen (AGT) M235T, and angiotensin II Type 1 receptor (AGTR1) A1166C gene polymorphisms in patients with cardiomyopathy. We performed a comprehensive search of several electronic databases, including PubMed, Embase, the Cochrane Library, and Web of Science, covering articles published from the time of database creation to April 17, 2023. Studies on the assessment of genetic polymorphisms in genes related to the renin-angiotensin system in relation to cardiomyopathy were included. The primary outcome was cardiomyopathy. Risk of bias was assessed using the Newcastle-Ottawa Scale scale. The meta-analysis includes 19 studies with 4,052 cases and 5,592 controls. The ACE I/D polymorphisms were found to be associated with cardiomyopathy (allelic model D vs I: OR = 1.29, 95CI% = 1.08-1.52; dominant model DD+ID vs II: OR = 1.43, 95CI% = 1.01-2.02; recessive model DD vs ID+II: OR = 0.79, 95CI% = 0.64-0.98). AGT M235T polymorphism and cardiomyopathy were not significantly correlated (allelic model T vs M: OR = 1.26, 95CI% = 0.96-1.66; dominant model TT+MT vs MM: OR = 1.30, 95CI% = 0.98-1.73; recessive model TT vs MT+MM: OR = 0.63, 95CI% = 0.37-1.07). AGTR1 polymorphism and cardiomyopathy were not significantly associated under allelic model A vs C (OR = 0.69, 95CI% = 0.46-1.03) and recessive model AA vs CA+CC (OR = 0.89, 95CI% = 0.34-2.30), but under the dominant model AA+CA vs CC (OR = 0.51, 95CI% = 0.38-0.68). The current meta-analysis reveals that polymorphisms in ACE I/D may be a genetic risk factor for cardiomyopathy. There is an association between AGTR1 gene polymorphisms and risk of cardiomyopathy under the specific model.

Role of Angiotensin II Type 1a Receptor (AT1aR) of Renal Tubules in Regulating Inwardly Rectifying Potassium Channels 4.2 (Kir4.2), Kir4.1, and Epithelial Na+ Channel (ENaC).

BACKGROUND: Kir4.2 and Kir4.1 play a role in regulating membrane transport in the proximal tubule (PT) and in the distal-convoluted-tubule (DCT), respectively. METHODS: We generated kidney-tubule-specific-AT1aR-knockout (Ks-AT1aR-KO) mice to examine whether renal AT1aR regulates Kir4.2 and Kir4.1. RESULTS: Ks-AT1aR-KO mice had a lower systolic blood pressure than Agtr1aflox/flox (control) mice. Ks-AT1aR-KO mice had a lower expression of NHE3 (Na+/H+-exchanger 3) and Kir4.2, a major Kir-channel in PT, than Agtr1aflox/flox mice. Whole-cell recording also demonstrated that the membrane potential in PT of Ks-AT1aR-KO mice was lesser negative than Agtr1aflox/flox mice. The expression of Kir4.1 and Kir5.1, Kir4.1/Kir5.1-mediated K+ currents of DCT and DCT membrane potential in Ks-AT1aR-KO mice, were similar to Agtr1aflox/flox mice. However, angiotensin II perfusion for 7 days hyperpolarized the membrane potential in PT and DCT of the control mice but not in Ks-AT1aR-KO mice, while angiotensin II perfusion did not change the expression of Kir4.1, Kir4.2, and Kir5.1. Deletion of AT1aR did not significantly affect the expression of αENaC (epithelial Na+ channel) and ßENaC but increased cleaved γENaC expression. Patch-clamp experiments demonstrated that deletion of AT1aR increased amiloride-sensitive Na+-currents in the cortical-collecting duct but not in late-DCT. However, tertiapin-Q sensitive renal outer medullary potassium channel currents were similar in both genotypes. CONCLUSIONS: AT1aR determines the baseline membrane potential of PT by controlling Kir4.2 expression/activity but AT1aR is not required for determining the baseline membrane potential of the DCT and Kir4.1/Kir5.1 activity/expression. However, AT1aR is required for angiotensin II-induced hyperpolarization of basolateral membrane of PT and DCT. Deletion of AT1aR had no effect on baseline renal outer medullary potassium channel activity but increased ENaC activity in the CCD.

Angiotensin II type 1 receptor-associated protein deletion combined with angiotensin II stimulation accelerates the development of diabetic kidney disease in mice on a C57BL/6 strain.

The progress in the research field of diabetic kidney disease (DKD) has been disturbed by the lack of reliable animal models. Angiotensin II (Ang II) type 1 receptor (AT1R)-associated protein (ATRAP) promotes internalization of AT1R and selectively inhibits pathological AT1R signaling. In this study, we investigated whether overactivation of the renin-angiotensin system (RAS) through a combination of ATRAP deletion with Ang II stimulation developed a progressive DKD model in C57BL/6 mice, which are resistant to the development of kidney injury. Eight-week-old male systemic ATRAP-knockout mice on the C57BL/6 strain (KO) and their littermate wild-type mice (Ctrl) were divided into five groups: 1) Ctrl, 2) Ctrl-streptozotocin (STZ), 3) KO-STZ, 4) Ctrl-STZ-Ang II, and 5) KO-STZ-Ang II. Ang II was administered for 6 weeks from 4 weeks after STZ administration. At 10 weeks after STZ administration, mice were euthanized to evaluate kidney injuries. Neither ATRAP deletion alone nor Ang II stimulation alone developed a progressive DKD model in STZ-induced diabetic C57BL/6 mice. However, a combination of ATRAP deletion with Ang II stimulation accelerated the development of DKD as manifested by overt albuminuria, glomerular hypertrophy, podocyte loss, mesangial expansion, kidney interstitial fibrosis and functional insufficiency, concomitant with increased angiotensinogen and AT1R expression in the kidneys. In STZ-induced diabetic C57BL/6 mice that are resistant to the development of kidney injury, the combination of ATRAP deletion and Ang II stimulation accelerates the development of DKD, which may be associated with intrarenal RAS overactivation.

AT1R autoantibody promotes phenotypic transition of smooth muscle cells by activating AT1R-OAS2.

Phenotypic transition of vascular smooth muscle cells (VSMCs) is an early event in the onset and progression of several cardiovascular diseases. As an important mediator of the renin-angiotensin system (RAS), activation of the angiotensin II type 1 receptor (AT1R) induces phenotypic transition of VSMCs. AT1R autoantibodies (AT1-AAs), which are agonistic autoantibodies of AT1R, have been detected in the sera of patients with a variety of cardiovascular diseases associated with phenotypic transition. However, the effect of AT1-AA on phenotypic transition is currently unknown. In this study, AT1-AA-positive rat model was established by active immunization to detect markers of VSMCs phenotypic transition. The results showed that AT1-AA-positive rats showed phenotypic transition of VSMCs, which was evidenced by the decrease of contractile markers, while the increase of synthetic markers in the thoracic aorta. However, in AT1-AA-positive AT1R knockout rats, the phenotypic transition-related proteins were not altered. In vitro, after stimulating human aortic smooth muscle cells with AT1-AA for 48 h, 2'-5' oligoadenylate synthase 2 (OAS2) was identified as the key differentially expressed gene by RNA sequencing and bioinformatics analysis. Furthermore, high expression of OAS2 was found in aorta of AT1-AA-positive rats; knockdown of OAS2 by siRNA can reverse the phenotypic transition of VSMCs induced by AT1-AA. In summary, this study suggests that AT1-AA can promote phenotypic transition of VSMCs through AT1R-OAS2 pathway, and OAS2 might serve as a potential therapeutic target to prevent pathological phenotypic transition of smooth muscle cells.

Unlocking the protective potential of the angiotensin type 2 receptor (AT2R) in acute lung injury and age-related pulmonary dysfunction.

Despite its known importance in the cardiovascular system, the specific role and impact of the angiotensin type 2 receptor (AT2R) in lung physiology and pathophysiology remain largely elusive. In this study, we highlight the distinct and specialized lung-specific roles of AT2R, primarily localized to an alveolar fibroblast subpopulation, in contrast to the angiotensin type 1 receptor (AT1R), which is almost exclusively expressed in lung pericytes. Evidence from our research demonstrates that the disruption of AT2R (AT2R-/y), is associated with a surge in oxidative stress and impaired lung permeability, which were further intensified by Hyperoxic Acute Lung Injury (HALI). With aging, AT2R-/y mice show an increase in oxidative stress, premature enlargement of airspaces, as well as increased mortality when exposed to hyperoxia as compared to age-matched WT mice. Our investigation into Losartan, an AT1R blocker, suggests that its primary HALI lung-protective effects are channeled through AT2R, as its protective benefits are absent in AT2R-/y mice. Importantly, a non-peptide AT2R agonist, Compound 21 (C21), successfully reverses lung oxidative stress and TGFß activation in wild-type (WT) mice exposed to HALI. These findings suggest a possible paradigm shift in the therapeutic approach for lung injury and age-associated pulmonary dysfunction, from targeting AT1R with angiotensin receptor blockers (ARBs) towards boosting the protective function of AT2R.

Interactions between AT1R and GRKs: the determinants for activation of signaling pathways involved in blood pressure regulation.

The success of Angiotensin II receptor blockers, specifically Angiotensin II type 1 receptor (AT1R) antagonists as antihypertensive drug emphasizes the involvement of AT1R in Essential hypertension. The structural insights and mutational studies of Ang II-AT1R have brought about the vision to design Ang II analogs that selectively activate the pathways with beneficial and cardioprotective effects such as cell survival and hinder the deleterious effects such as hypertrophy and cell death. AT1R belongs to G-protein coupled receptors and is regulated by G-protein coupled receptor kinases (GRKs) that either uncouples Gq protein for receptor desensitization or phosphorylate C-terminus to recruit ß-arrestin for internalization of the receptor. The interaction of GRKs with ligand activated AT1R induces conformational changes and signal either Gq dependent or Gq independent pathways. These interactions might explain the complex regulatory mechanisms and offer promising ideas for hypertension therapeutics. This article reviews the functional role of AT1R, organization of GRK genes and regulation of AT1R by GRKs that play significant role in desensitization and internalization of the receptors.

miR-125a-5p/miR-125b-5p contributes to pathological activation of angiotensin II-AT1R in mouse distal convoluted tubule cells by the suppression of Atrap.

The renin-angiotensin system plays a crucial role in the regulation of blood pressure. Activation of the angiotensin II (Ang II)-Ang II type 1 receptor (AT1R) signaling pathway contributes to the pathogenesis of hypertension and subsequent organ damage. AT1R-associated protein (ATRAP) has been identified as an endogenous inhibitory protein of the AT1R pathological activation. We have shown that mouse Atrap (Atrap) represses various Ang II-AT1R-mediated pathologies, including hypertension in mice. The expression of human ATRAP (ATRAP)/Atrap can be altered in various pathological states in humans and mice, such as Ang II stimulation and serum starvation. However, the regulatory mechanisms of ATRAP/Atrap are not yet fully elucidated. miRNAs are 21 to 23 nucleotides of small RNAs that post-transcriptionally repress gene expression. Single miRNA can act on hundreds of target mRNAs, and numerous miRNAs have been identified as the Ang II-AT1R signaling-associated disease phenotype modulator, but nothing is known about the regulation of ATRAP/Atrap. In the present study, we identified miR-125a-5p/miR-125b-5p as the evolutionarily conserved miRNAs that potentially act on ATRAP/Atrap mRNA. Further analysis revealed that miR-125a-5p/miR-125b-5p can directly repress both ATRAP and Atrap. In addition, the inhibition of miR-125a-5p/miR-125b-5p resulted in the suppression of the Ang II-AT1R signaling in mouse distal convoluted tubule cells. Taken together, miR-125a-5p/miR-125b-5p activates Ang II-AT1R signaling by the suppression of ATRAP/Atrap. Our results provide new insights into the potential approaches for achieving the organ-protective effects by the repression of the miR-125 family associated with the enhancement of ATRAP/Atrap expression.

Association of the rs5186 polymorphism of the AGTR1 gene with decreased eGFR in patients with type 2 diabetes from Mexico City.

BACKGROUND: Early biomarkers search for Diabetic Kidney Disease (DKD) in patients with Type 2 Diabetes Mellitus (T2DM), as genetic markers to identify vulnerable carriers of the disease even before Glomerular Filtration Rate (GFR) decline or microalbuminuria development, has been relevant during the last few years. The rs5186 (A116C) polymorphism of the Angiotensin II Receptor Type I gene (AGTR1), has been associated to multiple effects of renal injury risk, commonly detected in patients with Diabetes Mellitus (DM). It has been described that rs5186 could have an effect in stability proteins that assemble Angiotensin II Receptor Type I (AT1), modifying its action, which is why it should be considered as a risk factor for Chronic Kidney Disease (CKD), characterized by a GFR progressive reduction. Even though, the association between rs5186 AGTR1 gene polymorphism and DKD in patients with T2DM has been controversial, inconclusive, and even absent. This disputable issue might be as a result of association studies in which many and varied clinical phenotypes included are contemplated as CKD inductors and enhancers. Although, the sample sizes studied in patients with T2DM are undersized and did not have a strict inclusion criteria, lacking of biochemical markers or KDOQI classification, which have hindered its examination. OBJECTIVE: The aim of our study was to establish an association between rs5186 AGTR1 gene polymorphism and GFR depletion, assessed as a risk factor to DKD development in patients with T2DM. METHODS: We analyzed 297 not related patients with T2DM, divided into 221 controls (KDOQI 1) and 76 cases (KDOQI 2). Arterial pressure, anthropometric and biochemical parameters were measured. rs5186 of AGTR1 genotyping was performed by TaqMan assay real-time PCR method. Allele and genotype frequencies, and Hardy-Weinberg equilibrium were measured. Normality test for data distribution was analyzed by Shapiro-Wilk test, variable comparison by Student's t-test for continuous variables, and Chi-squared test for categorical variables; ANOVA test was used for mean comparison of more than two groups. Effect of rs5186 to DKD was estimated by multiple heritability adjustment models for risk variables of DKD. Statistical significance was indicated by p<0.05. Data was analyzed using Statistical Package STATA v11 software. RESULTS: Dominant and Over-dominant models showed a likelihood ratio to GFR depletion of 1.89 (1.05-3.39, p=0.031) and 2.01 (1.08-3.73, p=0.023) in patients with T2DM. Risk factor increased to 2.54 (1.10-5.89) in women in Over-dominant model. CONCLUSION: In clinical practice, most of nephropathies progress at a slow pace into a total breakdown of renal function, even asymptomatic. This is the first study, reporting that rs5186 polymorphism of AGTR1 gene contribution to GFR depletion, and this could be evaluated as a predisposing factor for DKD in patients with T2DM.

MicroRNA-206 Contributes to the Progression of Preeclampsia by Suppressing the Viability and Mobility of Trophocytes via the Inhibition of AGTR1.

The development of preeclampsia (PE) is associated with the impaired trophoblast motility. MicroRNAs (miRs) contribute to the modulation of trophoblast invasion. In the current study, the role of miR-206/AGTR1 in the TNF-alpha-induced invasion defect of trophoblasts was explored. The levels of miR-206 and ATGR1 in clinical placenta tissues were investigated. Trophoblasts were treated with TNF-alpha, and the levels of miR-206 and ATGR1 were modulated. Changes in cell viability, invasion, and inflammation in trophoblasts were detected. The level of miR-206 was induced, while the level of AGTR1 was suppressed in placenta tissues. In in vitro assays, TNF-alpha suppressed viability, induced inflammatory response, inhibited invasion, upregulated miR-206, and down-regulated AGTR1. The inhibited expression of miR-206 or the overexpression of AGTR1 counteracted the effects of TNF-alpha, indicating the key role of the miR-206/AGTR1 in progression of PE. Collectively, miR-206 suppressed viability, induced inflammatory response, and decreased invasion of trophoblasts by inhibiting AGTR1.

Association between AGTR1 (c.1166 A>C) Polymorphisms and Kidney Injury in Hypertension.

BACKGROUND: High blood pressure is the main cause of cardiovascular diseases. Kidney damage is one of the most common organ secondary damage to hypertension. The study of hypertension gene polymorphisms is an important means of precision treatment of primary hypertension. OBJECTIVES: The objective of this study was to explore the relationship between AGTR1 (c.1166 A>C) gene polymorphisms and hypertension combined with kidney damage, while exploring the relationship between codominant, dominant and recessive gene model and hypertension with kidney injury and the susceptibility of different genotypes to hypertension with kidney injury. METHODS: The distribution of AGTR1 polymorphism in the AGTR1 in hypertensive patients (hypertension group, 292 patients) and hypertension with kidney injury patients (44 patients) were detected and compared by PCR-melting curve method. RESULTS: The genotype distribution of hypertension and combined groups met Hardy-Weinberg equilibrium (p > 0.05); the distribution difference between the three genotypes was statistically significant (p < 0.05), the codominant, dominant and recessive distribution frequency of genotypes (p < 0.05), and no difference between A allele and C allele (p > 0.05). CONCLUSIONS: Our study identified the relationship of AGTRA (c.1166 A>C) with hypertension combined with renal injury, and compared the susceptibility of different genetic models, which may provide novel targets for precision gene therapy of hypertension. CLINICAL TRIAL REGISTRATION: URL: https://www.chictr.org.cn/indexEN.html; Unique identifier: ChiCTR2100051472.

ACE2 inhibits proliferation of smooth muscle cell through AT1R and its downstream signaling pathway.

To investigate the effect of the angiotensin converting enzyme 2 (ACE2) on AT1R expression, ERK1/2 and STAT3 protein phosphorylation in rat vascular smooth muscle cells (VSMCs) was studied. VSMCs were transfected with a lentiviral vector including the ACE2 gene and with siRNA to regulate the level of ACE2 in VSMCs. The levels of mRNA and proteins of ACE2, AT1R, ERK1/2, p-ERK1/2, STAT3, and p-STAT3 in VSMCs were examined using real-time PCR and western blot. The proliferation of VSMCs was observed by CCK-8 assay and BrdU measurement. Upregulation of ACE2 inhibited the growth of cells elicited by angiotensin II (Ang II). ACE2 significantly suppressed the level of the AT1 receptor (AT1R) protein induced by Ang II and phosphorylated the ERK1/2 and STAT3 proteins in the downstream signaling pathway. The transcriptional and translational levels of ACE2 were significantly lower in the si-ACE2 group than in the control group. The level of AT1R mRNA and protein, both with the phosphorylation expression of ERK1/2 and STAT3 protein in the siACE2 group and the Ang II group, were significantly enhanced than those in the control group. ACE2 significantly inhibited the growth of VSMCs. ACE2 inhibited the proliferation of VSMCs by suppressing AT1R and the downstream ERK1/2 and STAT3 signaling axes. Also, Ang II enhanced the level of AT1R and phosphorylated ERK1/2 and STAT3 by inhibiting the level of the ACE2 mRNA and protein.

Unraveling allostery within the angiotensin II type 1 receptor for Gαq and ß-arrestin coupling.

G protein-coupled receptors engage both G proteins and ß-arrestins, and their coupling can be biased by ligands and mutations. Here, to resolve structural elements and mechanisms underlying effector coupling to the angiotensin II (AngII) type 1 receptor (AT1R), we combined alanine scanning mutagenesis of the entire sequence of the receptor with pharmacological profiling of Gαq and ß-arrestin engagement to mutant receptors and molecular dynamics simulations. We showed that Gαq coupling to AT1R involved a large number of residues spread across the receptor, whereas fewer structural regions of the receptor contributed to ß-arrestin coupling regulation. Residue stretches in transmembrane domain 4 conferred ß-arrestin bias and represented an important structural element in AT1R for functional selectivity. Furthermore, we identified allosteric small-molecule binding sites that were enclosed by communities of residues that produced biased signaling when mutated. Last, we showed that allosteric communication within AT1R emanating from the Gαq coupling site spread beyond the orthosteric AngII-binding site and across different regions of the receptor, including currently unresolved structural regions. Our findings reveal structural elements and mechanisms within AT1R that bias Gαq and ß-arrestin coupling and that could be harnessed to design biased receptors for research purposes and to develop allosteric modulators.

Angiotensin II type 1a receptor knockout ameliorates high-fat diet-induced cardiac dysfunction by regulating glucose and lipid metabolism.

Obesity-related cardiovascular diseases are associated with overactivation of the renin-angiotensin system (RAS). However, the underlying mechanisms remain elusive. In this study, we investigate the role of angiotensin II (Ang II) in high-fat diet (HFD)-induced cardiac dysfunction by focusing on cardiac glucose and lipid metabolism and energy supply. Ang II plays a role in cardiovascular regulation mainly by stimulating angiotensin II type 1 receptor (AT1R), among which AT1aR is the most important subtype in regulating the function of the cardiovascular system. AT1aR gene knockout (AT1aR ‒/‒) rats and wild-type (WT) rats are randomly divided into four groups and fed with either a normal diet (ND) or a HFD for 12 weeks. The myocardial lipid content, Ang II level and cardiac function are then evaluated. The expressions of a number of genes involved in glucose and fatty acid oxidation and mitochondrial dynamics are measured by quantitative polymerase chain reaction and western blot analysis. Our results demonstrate that AT1aR knockout improves HFD-induced insulin resistance and dyslipidemia as well as lipid deposition and left ventricular dysfunction compared with WT rats fed a HFD. In addition, after feeding with HFD, AT1aR ‒/‒ rats not only show further improvement in glucose and fatty acid oxidation but also have a reverse effect on increased mitochondrial fission proteins. In conclusion, AT1aR deficiency ameliorates HFD-induced cardiac dysfunction by enhancing glucose and fatty acid oxidation, regulating mitochondrial dynamics-related protein changes, and further promoting cardiac energy supply.

Unveiling Angiotensin II and Losartan-Induced Gene Regulatory Networks Using Human Urine-Derived Podocytes.

Podocytes are highly specialized cells that play a pivotal role in the blood filtration process in the glomeruli of the kidney, and their dysfunction leads to renal diseases. For this reason, the study and application of this cell type is of great importance in the field of regenerative medicine. Hypertension is mainly regulated by the renin-angiotensin-aldosterone system (RAAS), with its main mediator being angiotensin II (ANG II). Elevated ANG II levels lead to a pro-fibrotic, inflammatory, and hypertrophic milieu that induces apoptosis in podocytes. The activation of RAAS is critical for the pathogenesis of podocyte injury; as such, to prevent podocyte damage, patients with hypertension are administered drugs that modulate RAAS signaling. A prime example is the orally active, non-peptide, selective angiotensin-II-type I receptor (AGTR1) blocker losartan. Here, we demonstrate that SIX2-positive urine-derived renal progenitor cells (UdRPCs) and their immortalized counterpart (UM51-hTERT) can be directly differentiated into mature podocytes. These podocytes show activation of RAAS after stimulation with ANG II, resulting in ANG II-dependent upregulation of the expression of the angiotensin-II-type I receptor, AGTR1, and the downregulated expression of the angiotensin-II-type II receptor 2 (AGTR2). The stimulation of podocytes with losartan counteracts ANG II-dependent changes, resulting in a dependent favoring of the specific receptor from AGTR1 to AGTR2. Transcriptome analysis revealed 94 losartan-induced genes associated with diverse biological processes and pathways such as vascular smooth muscle contraction, the oxytocin signaling pathway, renin secretion, and ECM-receptor interaction. Co-stimulation with losartan and ANG II induced the exclusive expression of 106 genes associated with DNA methylation or demethylation, cell differentiation, the developmental process, response to muscle stretch, and calcium ion transmembrane transport. These findings highlight the usefulness of UdRPC-derived podocytes in studying the RAAS pathway and nephrotoxicity in various kidney diseases.

AT1R gene rs389566 polymorphism contributes to MACCEs in hypertension patients.

OBJECTIVE: To investigate the possible association between AT1R gene polymorphisms and major adverse cardiovascular and cerebrovascular events (MACCEs) in hypertension patients combined with or without coronary artery disease (CAD) in Xinjiang. METHODS: 374 CAD patients and 341 non-CAD individuals were enrolled as study participants and all of them have a hypertension diagnosis. AT1R gene polymorphisms were genotyped by SNPscan™ typing assays. During the follow-up in the clinic or by telephone interview, MACCEs were recorded. Kaplan-Meier curves and Cox survival analyses were used to explore the association between AT1R gene polymorphisms and the occurrence of MACCEs. RESULTS: AT1R gene rs389566 was associated with MACCEs. The TT genotype of the AT1R gene rs389566 had a significantly higher probability of MACCEs than the AA + AT genotype (75.2% vs. 24.8%, P = 0.033). Older age (OR = 1.028, 95% CI: 1.009-1.0047, P = 0.003) and TT genotype of rs389566 (OR = 1.770, 95% CI: 1.148-2.729, P = 0.01) were risk factors of MACCEs. AT1R gene rs389566 TT genotype may be a predisposing factor for the occurrence of MACCEs in hypertensive patients. CONCLUSION: We should also pay more attention to the prevent of MACCEs in hypertension patients combined with CAD. Especially those elderly hypertensive patients carrying AT1R rs389566 TT genotype requires avoidance of unhealthy lifestyle, better management of blood pressure control and reduce the occurrence of MACCEs.

Inhibition of angiotensin II type 1 receptor reduces oxidative stress damage to the intestinal barrier in severe acute pancreatitis.

Intestinal barrier injury is a common complication of severe acute pancreatitis (SAP), which is often accompanied by intestinal mucosal barrier injury and results in serious consequences. However, the exact mechanism remains unclear. We aimed to investigate whether angiotensin II type 1 receptor (AT1)-mediated oxidative stress is involved in SAP intestinal barrier injury and assessed the effects of inhibiting this pathway. The SAP model was established by retrograde bile duct injection of sodium taurocholate (5%). The rats were divided into three groups: the control group (SO), the SAP group (SAP), and the azilsartan intervention group (SAP + AZL). Serum amylase, lipase, and other indexes were measured to evaluate SAP severity in each group. Histopathological changes in the pancreas and intestine were evaluated by HE staining. The oxidative stress of intestinal epithelial cells was detected by superoxide dismutase and glutathione. We also detected the expression and distribution of intestinal barrier-related proteins. The results showed that the serum indexes, the severity of tissue damage, and the level of oxidative stress in the SAP + AZL group were significantly lower than in the SAP group. Our study provided hitherto undocumented evidence of AT1 expression in the intestinal mucosa, confirming that AT1-mediated oxidative stress is involved in SAP intestinal mucosal injury, and inhibiting this pathway could effectively reduce intestinal mucosal oxidative stress injury, providing a new and effective target for the treatment of SAP intestinal barrier injury.

Angiotensin receptor blockers retard the progression and fibrosis via inhibiting the viability of AGTR1+ CAFs in intrahepatic cholangiocarcinoma.

BACKGROUND: Intrahepatic cholangiocarcinoma (iCCA) is a highly lethal malignancy characterized by massive fibrosis and has ineffective adjuvant therapies. Here, we demonstrate the potential of angiotensin receptor blockers (ARBs) in targeting iCCA. METHODS: Masson's trichrome staining was used to assess the effect of ARBs in iCCA specimens, CCK8 and gel contraction assays in vitro and in xenograft models in vivo. RNA-seq and ATAC-seq were used for mechanistic investigations. RESULTS: Patients with iCCA who were administered ARBs had a better prognosis and a lower proportion of tumour stroma, indicating alleviated fibrosis. The presence of AGTR1, the ARBs receptor, is associated with a poor prognosis of iCCA and is highly expressed in tumour tissues and cancer-associated fibroblasts (CAFs). The ARBs strongly attenuated the viability of AGTR1+ CAFs in vitro and retarded tumour progression and fibrosis in xenograft models of co-cultured CAFs and iCCA cells. Still, they did not have a significant effect on AGTR1- CAFs. Moreover, ARBs decreased the secretion of AGTR1+ CAF-derived MFAP5 via the Hippo pathway, weakened the interaction between CAFs and iCCA cells, and impaired the aggressiveness of iCCA cells by attenuating the activation of the Notch1 pathway in iCCA cells. CONCLUSIONS: ARBs exhibit anti-fibrotic function by inhibiting the viability of AGTR1+ CAFs. These findings support using ARBs as a novel therapeutic option for targeting iCCA.