Renin Receptor Research Articles

VACUOLAR H+-ATPASE AS A NOVEL TARGET TO LOWER LOW DENSITY LIPOPROTEIN CHOLESTEROL

Objective: Low density lipoprotein cholesterol (LDL-c) is cleared from the circulation through binding to the hepatic LDL receptor (LDLR). The (pro)renin receptor [(P)RR, also known as vacuolar H+-ATPase (V-ATPase) accessory protein 2 or ATP6AP2)] is a regulator of this process. Indeed, (P)RR silencing markedly reduced LDLR protein abundance and thereby LDL uptake. Since V-ATPase is a multi-subunit complex (consisting of 13 subunits), in this study we evaluated the role of subunits other than the (P)RR. Design and method: siRNAs were designed against all V-ATPase subunits, transfected into HepG2 cells, and evaluated for their capacity to affect cell surface LDLR. Given that silencing subunit ATP6V1B2 upregulated LDLR most, we next designed an adeno-associated virus expressing shAtp6v1b2 and injected this into C57BL/6 mice and then investigated the effects of Atp6v1b2 knocking-down on LDL metabolism in vivo. Results: Silencing subunit ATP6V1B2 in HepG2 cells increased surface LDLR and total LDLR protein abundance by 1.5- and 2.3-fold, respectively. This was accompanied by both LDLR mRNA upregulation, suggestive for de novo protein synthesis, and enhanced LDL uptake following exposure to excess LDL. Silencing ATP6V1B2 significantly increased the mRNA levels of sterol regulatory element-binding protein 2 (SREBP2)-targeted genes (SQLE, HMGCR, and NPC1) as well as the nuclear SREBP2 protein level. In vivo, knocking-down Atp6v1b2 decreased plasma total cholesterol by 23%, without affecting total triglycerides. This was accompanied by LDLR upregulation in the liver, both at the mRNA and protein levels. Conclusions: The V-ATPase subunit ATP6V1B2 is an important regulator of LDLR expression. This involves the transcription factor SREBP2, and allows substantial LDL-c lowering. V-ATPase might be a novel pharmacological target to lower cholesterol.

Endothelin-1 production via placental (pro)renin receptor in a mouse model of preeclampsia

IntroductionPreeclampsia (PE) pathogenesis is explained by the two-stage disorder theory. However, mechanisms underlying hypertension and proteinuria in PE remain unclear. The role of (pro)renin receptor (PRR) in PE pathology has received special attention. We examined endothelin-1 (ET-1) production via placental PRR in a PE mouse model. MethodsAt 14.5 day-post-coitum (DPC), we performed a reduced uterine perfusion pressure (RUPP) operation, ligating the uterine arteriovenous vessels in female mice. We also infused these mice with a PRR inhibitor, decoy peptide in the handle region of prorenin (HRP) for mice (NH2-RIPLKKMPSV-COOH). At 18.5 DPC, blood, urine, and placenta were collected; fetus and placenta were weighed. We evaluated placental hypoxia using quantitative polymerase chain reaction (PCR), with hypoxia-inducible factor-1α (HIF-1α) as index. We also evaluated PRR, transforming growth factor-β1 (TGF-β1), and ET-1 expression in the placenta using quantitative PCR and western blotting. ET-1 concentration in blood plasma was assessed using enzyme-linked immunosorbent assay. ResultsBlood pressure and proteinuria significantly increased, and fetal and placental weights decreased in RUPP mice. HIF-1α, PRR, TGF-β1, and ET-1 expressions considerably increased in RUPP mice placentas. ET-1 concentration in RUPP mice blood plasma was markedly increased. PRR inhibitor suppressed these changes. DiscussionIn PE model mice that underwent RUPP treatment, placental hypoxia increased PRR and ET-1 expression suggesting a causative relationship between ET-1 and intracellular PRR signaling. RUPP treatment, when combined with HRP, reversed the effect of elevated ET-1 levels in the model. This study may help to elucidate the pathogenesis of PE considering PRR and ET-1.

Sex differences in soluble (pro)renin receptor regulation of blood pressure

Background: Cleavage of the extra-cellular domain of the (pro)renin receptor (PRR) yields a soluble fragment (sPRR), that has been implicated in the pathogenesis of hypertension. We recently developed a novel mouse model with mutation in the cleavage site of the PRR using CRISPR/Cas9 such that sPRR is not generated. Since the gene encoding PRR is on the X-chromosome, male mutant mice have markedly lower plasma sPRR levels (control: 21.5 ± 2.5 vs mutant: 0.2 ± 0.03 ng/ml, p<0.001) while female mutant mice (being heterozygous) have roughly 40% reduction in plasma sPRR levels (control: 11.6 ± 1.6 vs mutant: 6.2 ± 1.0 ng/ml, p<0.01). In this study, we examined sex differences in the mechanisms regulating blood pressure (BP) between male and female mutant sPRR mice and their littermate controls following angiotensin-II induced hypertension and DOCA-salt hypertension. Methods: Male and female control and mutant sPRR mice aged 3-4 months of age were treated with angiotensin-II (Ang-II, 400 ng/kg/min, n= 6-8/group)) for 2 weeks or DOCA (50 mg/kg, n=5-6/group) and saline for 3 weeks. BP was monitored by radio-telemetry. Metabolic balance studies were performed during course of Ang-II infusion or at the end of DOCA-salt treatment. Results: Compared to controls, male mutant sPRR mice had lower baseline blood pressure (systolic - 118 ± 4 vs control: 125 ± 3 mm of Hg) as well as attenuated hypertensive response to Ang-II infusion (systolic day 7: 122 ± 5 vs control: 150 ± 6; day 14: 128 ± 7 vs control: 158 ± 4 mm Hg) and DOCA-salt treatment (systolic day 17: 132 ± 5 vs control: 141 ± 2 mm Hg). In contrast, female control and mutant sPRR mice had similar BP at baseline (systolic 112 ± 4 vs control: 113 ± 6 mm Hg) and following DOCA-salt treatment (systolic day 17: 141 ± 9 vs control: 139 ± 11 mmHg). However, female mutant sPRR mice had an attenuated hypertensive response to Ang-II infusion compared to female controls (systolic day 7: 116 ± 17 vs controls:134 ± 16; day 14:126 ± 20 vs control:149 ± 20 mm Hg). Male control and mutant sPRR mice had no differences in urinary Na+ or K+ excretion with Ang-II infusion while female mutant sPRR mice had enhanced urinary Na and K excretion compared to controls on day 2 and day 7 of Ang-II infusion. Both male and female mutant sPRR mice had attenuated vasoconstrictor response to Ang-II in isolated mesenteric arteries despite similar Ang-II receptor expression. We are currently examining differences in renin angiotensin aldosterone system markers between male and female control and mutant sPRR mice following Ang-II/DOCA-salt hypertension. Conclusion: These results suggest that sPRR plays a role in Ang-II induced hypertension in male and female mice through modulation of urinary Na+/K+ excretion and vascular reactivity. sPRR is also involved in regulating BP with DOCA-salt treatment in male but not female mice. NHLBI This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

(Pro)Renin Receptor Decoy Peptide PRO20 Protects against Oxidative Renal Damage Induced by Advanced Oxidation Protein Products

Chronic kidney disease (CKD) is associated with advanced oxidation protein products (AOPPs). A recent study has shown that AOPP-induced renal tubular injury is mediated by the (pro)renin receptor (PRR). However, it is unclear whether the PRR decoy inhibitor PRO20 can protect against renal damage related to AOPPs in vivo. In this study, we examined the role of the PRR in rats with AOPP-induced renal oxidative damage. Male SD rats were subjected to unilateral nephrectomy, and after a four-day recuperation period, they were randomly divided into four groups (n = 6/group) for four weeks: control (CTR), unmodified rat serum albumin (RSA, 50 mg/kg/day via tail-vein injection), AOPPs-RSA (50 mg/kg/day via tail-vein injection), and AOPPs-RSA + PRO20 (50 mg/kg/day via tail-vein injection + 500 μg/kg/day via subcutaneous injection) groups. PRO20 was administered 3 days before AOPPs-RSA injection. Renal histopathology evaluation was performed by periodic acid-Schiff (PAS) staining, and biochemical parameters related to renal injury and oxidative stress biomarkers were evaluated. The expression of related indicators was quantified by RT-qPCR and immunoblotting analysis. In the results, rats in the AOPPs-RSA group exhibited higher levels of albuminuria, inflammatory cell infiltration, and tubular dilation, along with upregulation of oxidative stress, profibrotic and proinflammatory factors, and elevation of AOPP levels. Meanwhile, in the PRO20 group, these were significantly reduced. Moreover, the levels of almost all components of the renin-angiotensin system (RAS) and Nox4-dependent H2O2 production in urine and the kidneys were elevated by AOPPs-RSA, while they were suppressed by PRO20. Furthermore, AOPPs-RSA rats showed elevated kidney expression of the PRR and soluble PRR (sPRR) and increased renal excretion of sPRR. In summary, these findings suggest that PRR inhibition may serve as a protective mechanism against AOPP-induced nephropathy by inhibiting the intrarenal RAS and Nox4-derived H2O2 mechanisms.

High-plasma soluble prorenin receptor is associated with vascular damage in male, but not female, mice fed a high-fat diet.

Plasma soluble prorenin receptor (sPRR) displays sexual dimorphism and is higher in women with type 2 diabetes mellitus (T2DM). However, the contribution of plasma sPRR to the development of vascular complications in T2DM remains unclear. We investigated if plasma sPRR contributes to sex differences in the activation of the systemic renin-angiotensin-aldosterone system (RAAS) and vascular damage in a model of high-fat diet (HFD)-induced T2DM. Male and female C57BL/6J mice were fed either a normal fat diet (NFD) or an HFD for 28 wk to assess changes in blood pressure, cardiometabolic phenotype, plasma prorenin/renin, sPRR, and ANG II. After completing dietary protocols, tissues were collected from males to assess vascular reactivity and aortic reactive oxygen species (ROS). A cohort of male mice was used to determine the direct contribution of increased systemic sPRR by infusion. To investigate the role of ovarian hormones, ovariectomy (OVX) was performed at 32 wk in females fed either an NFD or HFD. Significant sex differences were found after 28 wk of HFD, where only males developed T2DM and increased plasma prorenin/renin, sPRR, and ANG II. T2DM in males was accompanied by nondipping hypertension, carotid artery stiffening, and aortic ROS. sPRR infusion in males induced vascular thickening instead of material stiffening caused by HFD-induced T2DM. While intact females were less prone to T2DM, OVX increased plasma prorenin/renin, sPRR, and systolic blood pressure. These data suggest that sPRR is a novel indicator of systemic RAAS activation and reflects the onset of vascular complications during T2DM regulated by sex.NEW & NOTEWORTHY High-fat diet (HFD) for 28 wk leads to type 2 diabetes mellitus (T2DM) phenotype, concomitant with increased plasma soluble prorenin receptor (sPRR), nondipping blood pressure, and vascular stiffness in male mice. HFD-fed female mice exhibiting a preserved cardiometabolic phenotype until ovariectomy revealed increased plasma sPRR and blood pressure. Plasma sPRR may indicate the status of systemic renin-angiotensin-aldosterone system (RAAS) activation and the onset of vascular complications during T2DM in a sex-dependent manner.

The role of (pro)renin receptor and its soluble form in cardiovascular diseases.

The renin-angiotensin system (RAS) is a major classic therapeutic target for cardiovascular diseases. In addition to the circulating RAS, local tissue RAS has been identified in various tissues and plays roles in tissue inflammation and tissue fibrosis. (Pro)renin receptor (PRR) was identified as a new member of RAS in 2002. Studies have demonstrated the effects of PRR and its soluble form in local tissue RAS. Moreover, as an important part of vacuolar H+-ATPase, it also contributes to normal lysosome function and cell survival. Evidently, PRR participates in the pathogenesis of cardiovascular diseases and may be a potential therapeutic target of cardiovascular diseases. This review focuses on the effects of PRR and its soluble form on the physiological state, hypertension, myocardial ischemia reperfusion injury, heart failure, metabolic cardiomyopathy, and atherosclerosis. We aimed to investigate the possibilities and challenges of PRR and its soluble form as a new therapeutic target in cardiovascular diseases.

Dietary Resveratrol Butyrate Monoester Supplement Improves Hypertension and Kidney Dysfunction in a Young Rat Chronic Kidney Disease Model.

Chronic kidney disease (CKD) remains a public health problem. Certain dietary supplements can assist in the prevention of CKD progression. In this regard, resveratrol is a polyphenol and has a potential therapeutic role in alleviating CKD. We previously utilized butyrate in order to improve the bioavailability of resveratrol via esterification and generated a resveratrol butyrate monoester (RBM). In this study, the hypothesis that RBM supplementation is able to protect against kidney dysfunction and hypertension was tested by using an adenine-induced CKD model. For this purpose, three-week-old male Sprague Dawley rats (n = 40) were equally categorized into: group 1-CN (sham control); group 2-CKD (adenine-fed rats); group 3-REV (CKD rats treated with 50 mg/L resveratrol); group 4-MEL (CKD rats treated with 25 mg/L RBM); and group 5-MEH (CKD rats treated with 50 mg/L RBM). At the end of a 12-week period, the rats were then euthanized. The adenine-fed rats displayed hypertension and kidney dysfunction, which were attenuated by dietary supplementation with RBM. The CKD-induced hypertension coincided with: decreased nitric oxide (NO) bioavailability; augmented renal protein expression of a (pro)renin receptor and angiotensin II type 1 receptor; and increased oxidative stress damage. Additionally, RBM and resveratrol supplementation shaped distinct gut microbiota profiles in the adenine-treated CKD rats. The positive effect of high-dose RBM was shown together with an increased abundance of the genera Duncaniella, Ligilactobacillus, and Monoglobus, as well as a decrease in Eubacterium and Schaedierella. Importantly, the mechanism of action of the RBM supplementation may be related to the restoration of NO, rebalancing of the RAS, a reduction in oxidative stress, and alterations to the gut microbiota. Moreover, RBM supplementation shows promise for the purposes of improving CKD outcomes and hypertension. As such, further translation to human studies is warranted.

Effects of a monoclonal antibody against (pro)renin receptor on gliomagenesis

Glioblastoma is characterized by a strong self-renewal potential and poor differentiated state. We have reported previously that the (pro)renin receptor [(P)RR] is a potential target for glioma therapy by silencing the (P)RR gene. Here, we have examined the effects of a monoclonal antibody against (P)RR on gliomagenesis. Human glioma cell lines (U251MG and U87MG) and a glioma stem cell line (MGG23) were used for the in vitro study. The expressions of the Wnt/β-catenin signaling pathway (Wnt signaling pathway) components and stemness markers were measured by Western blotting. The effects of the (P)RR antibody on cell proliferation, sphere formation, apoptosis and migration were also examined. Subcutaneous xenografts were also examined in nude mice. Treatment with the (P)RR antibody reduced expression of Wnt signaling pathway components and stemness markers. Furthermore, the (P)RR antibody reduced cell proliferation and decreased sphere formation significantly. The treatment also suppressed migration and induced apoptosis. In a subcutaneous xenograft model, systemic administration of the (P)RR antibody reduced tumor volume significantly. These data show that treatment with the (P)RR antibody is a potential therapeutic strategy for treating glioblastoma.

(Pro)Renin Receptor Antagonism Attenuates High-Fat-Diet-Induced Hepatic Steatosis.

Non-alcoholic fatty liver disease (NAFLD) comprises a spectrum of liver damage directly related to diabetes, obesity, and metabolic syndrome. The (pro)renin receptor (PRR) has recently been demonstrated to play a role in glucose and lipid metabolism. Here, we test the hypothesis that the PRR regulates the development of diet-induced hepatic steatosis and fibrosis. C57Bl/6J mice were fed a high-fat diet (HFD) or normal-fat diet (NFD) with matching calories for 6 weeks. An 8-week methionine choline-deficient (MCD) diet was used to induce fibrosis. Two weeks following diet treatment, mice were implanted with a subcutaneous osmotic pump delivering either the peptide PRR antagonist, PRO20, or scrambled peptide for 4 or 6 weeks. Mice fed a 6-week HFD exhibited increased liver lipid accumulation and liver triglyceride content compared with NFD-fed mice. Importantly, PRO20 treatment reduced hepatic lipid accumulation in HFD-fed mice without affecting body weight or blood glucose. Furthermore, PRR antagonism attenuated HFD-induced steatosis, particularly microvesicular steatosis. In the MCD diet model, the percentage of collagen area was reduced in PRO20-treated compared with control mice. PRO20 treatment also significantly decreased levels of liver alanine aminotransferase, an indicator of liver damage, in MCD-fed mice compared with controls. Mechanistically, we found that PRR antagonism prevented HFD-induced increases in PPARγ and glycerol-3-phosphate acyltransferase 3 expression in the liver. Taken together, our findings establish the involvement of the PRR in liver triglyceride synthesis and suggest the therapeutic potential of PRR antagonism for the treatment of liver steatosis and fibrosis in NAFLD.

(Pro)renin receptor promotes colorectal cancer progression through inhibiting the NEDD4L-mediated Wnt3 ubiquitination and modulating gut microbiota

BackgroundWe previously found that (pro)renin receptor ((P)RR) augments Wnt3 protein without affecting Wnt3 gene transcription in colorectal cancer (CRC) cells, thus contributes to CRC initiation. The present study aims to investigate whether (P)RR further promotes CRC progression following oncogenesis and the related mechanisms. Notably, we deeply elaborate how (P)RR affects Wnt3 protein level and the key enzyme that mediates this process.MethodsImmunohistochemistry, western blotting and immunofluorescence were performed to detect protein expression status. A kind of gastrointestinal epithelium-specific ATP6AP2 ((P)RR encoding gene) knock-in mice were generated using Crispr/Cas9 system.ResultsWe found that increased (P)RR expression in primary CRC lesions is positively associated with higher Wnt3 protein level and disease progression. Progressive CRC presents less colocalization of Wnt3 and an E3 ubiquitin ligase NEDD4L in primary lesions than non-progressive CRC. In colon cancer cells, (P)RR dramatically inhibits the NEDD4L-mediated Wnt3 protein ubiquitination. ATP6AP2 knock-in mice show more diminished Wnt3-NEDD4L colocalization in their gut epithelium in comparison to wildtype mice. They also have abnormal gut bacterial flora distribution. Especially, Lachnospiraceae_NK4A136 and Bacteroides genus, which are generally protective against CRC, are suppressed in guts of ATP6AP2 knock-in mice.ConclusionsCollectively, (P)RR promotes CRC progression through inhibiting the NEDD4L-mediated Wnt3 ubiquitination and modulating gut microbiota.5Fh7m3ebJHKpa3LjUnmMxGVideo

PS-B12-4: SOLUBLE (PRO)RENIN RECEPTOR LEVEL INCREASED IN A RAT MODEL OF REDUCED UTERINE PERFUSION PRESSURE

Objective: The (pro)renin receptor [(P)RR)] is a multifunctional protein with roles in angiotensin II-dependent and -independent intracellular cell signaling and as an adaptor protein between the Wnt receptor complex and vacuolar proton-translocating adenosine triphosphatase. The (P)RR is cleaved from the full length (P)RR to generate soluble (P)RR [s(P)RR], reflecting the status of the tissue activity of the (P)RR. We have shown that maternal blood s(P)RR concentrations in early pregnancy are associated with increased blood pressure in late pregnancy, while higher levels of s(P)RR in cord blood in babies are at lower risk of low birth weight. We have also reported that intracellular s(P)RR is increased by hypoxia and interacts with pyruvate dehydrogenase β; subunit (PDHB) to stabilize PDHB protein and pyruvate dehydrogenase (PDH) activity in trophoblast cells, leading to our hypothesis that (P)RR may help maintain oxidative metabolism and efficient energy production during placental ischemia. In this in vivo study, we investigated effects of reduced uterine perfusion pressure (RUPP) on PDH activity and s(P)RR levels in rats. Design and method: RUPP was induced by placing sliver clips around the aorta above the iliac bifurcation and the bilateral uterine arcades in pregnant Sprague Dawley rats on gestational day 14 (RUPP rats). Weights of placentas and infants were measured on gestational day 21. mRNA expressions of (P)RR, hypoxia-inducible factor 1-alpha (HIF1a), and PDHB, and protein levels of HIF1a, (P)RR, s(P)RR, PDHB, lactate, and pyruvate, and activity of PDH in placentas were measured on gestational day 21. Result: Weight of placentas and infants were significantly decreased in RUPP rats when compared with those of sham rats. mRNA and protein levels of HIF1a were significantly higher in RUPP rats than in control sham rats, indicating that ischemia was actually induced by RUPP. mRNA levels of (P)RR and PDHB were not significantly different between the groups. The protein level of (P)RR was not significantly different between the groups while s(P)RR protein level was significantly higher in RUPP rats than in controls. Concentrations of lactate or pyruvate and PDH activity were not significantly different between the groups. Conclusion: PDH activity was not decreased even under the condition of placental ischemia. s(P)RR but not full length (P)RR was increased by placental ischemia. These data suggested that s(P)RR might be increased by placental ischemia to maintain mitochondrial oxidative metabolism in rats.

PS-C22-10: SERUM SOLUBLE (PRO)RENIN RECEPTOR CONCENTRATION AS A PROGNOSTIC FACTOR IN PATIENTS UNDERGOING MAINTENANCE HEMODIALYSIS

Objective: The (pro)renin receptor [(P)RR)] is a multifunctional protein with roles in angiotensin II-dependent and -independent intracellular cell signaling and as an adaptor protein between the Wnt receptor complex and vacuolar proton-translocating adenosine triphosphatase. The (P)RR is cleaved to generate soluble (P)RR [s(P)RR], reflecting the status of the tissue renin-angiotensin system and/or activity of the (P)RR. Patients undergoing hemodialysis (HD) have poor prognosis because of the increased prevalence of cardiovascular and malignant diseases. This study was conducted to investigate whether the s(P)RR level is associated with new onset of cardiovascular events or malignant diseases and prognosis in patients undergoing HD. Design and method: A total of 258 patients undergoing maintenance HD who were enrolled in our cohort study investigating the relationships between serum s(P)RR levels and background factors were prospectively followed up for 60 months. We investigated the relationships between s(P)RR levels and new onset of cardiovascular events or malignant diseases and mortality during the follow-up period. Results: The cumulative incidence of new onset of cardiovascular events (P = 0.009) and cardiovascular deaths (P < 0.001), but not of malignant diseases, was significantly greater in patients with higher serum s(P)RR level (≧ 29.8 ng/ml) than in those with lower s(P)RR level (< 29.8 ng/ml). A high serum s(P)RR level was independently correlated with cardiovascular mortality (95% CI 1.001 - 1.083, P = 0.046). Conclusions: These data showed that the serum s(P)RR level is associated with cardiovascular events and mortality, suggesting that the serum s(P)RR level could be used as a biomarker for selecting patients requiring intensive care.

Soluble (Pro)Renin Receptor Level in Patients with Severe Obesity Is Associated with Visceral Adiposity and Is Involved with Insulin Resistance and Renal Injury

Introduction: High soluble (pro)renin receptor (s[P]RR) level in circulation is reported in obese patients; however, it is unclear which body composition components are responsible for it. In this study, the authors examined blood s(P)RR levels and ATP6AP2 gene expression levels in visceral and subcutaneous adipose tissue (VAT, SAT) in severely obese patients who underwent laparoscopic sleeve gastrectomy (LSG), with the aim of clarifying the relationship with body composition and metabolic factors. Methods: Seventy five cases who underwent LSG between 2011 and 2015 and were postoperatively followed-up for 12 months at the Toho University Sakura Medical Center were included in the analysis of the cross-sectional survey at baseline, and 33 cases were included in the analysis of the longitudinal survey during the 12 months after LSG. We evaluated body composition, glycolipid parameters, liver/renal function, as well as serum s(P)RR level and ATP6AP2 mRNA expression level in VAT and SAT. Results: The mean serum s(P)RR level at baseline was 26.1 ng/mL, this value was considered higher than values in healthy subjects. There was no significant difference in the expression level of ATP6AP2 mRNA between VAT and SAT. At baseline, multiple regression analysis for the association between s(P)RR and variables identified that visceral fat area, HOMA2-IR, and UACR showed the independent relationships with s(P)RR. During the 12 months after LSG, body weight, serum s(P)RR level showed a significant decrease (from 30.0 ± 7.0 to 21.9 ± 4.3). Multiple regression analysis for the association between the change in s(P)RR and variables showed that changes in visceral fat area, and alanine transaminase were independently related to the change in s(P)RR. Conclusion: This study showed that blood s(P)RR level was high in severely obese patients, decreased with weight loss by LSG, and was associated with visceral fat area in both pre- and postoperative changes. The results suggest that blood s(P)RR levels in obese patients may reflect the involvement of visceral adipose (P)RR in insulin resistance and renal damage mechanisms associated with obesity.

PS-B12-11: FUNCTIONAL VERSATILITY OF (PRO) RENIN RECEPTOR CLARIFIED BY STRUCTURAL AND EVOLUTIONARY ANALYSES

Objective: (Pro)renin receptor [(P)RR] is a single-span membrane protein originally identified as a regulator of the renin-angiotensin-aldosterone system. (P)RR reportedly exerts various functions, including an accessory protein of vacuolar ATPase complex and a component of Wnt receptor complex. The soluble form of (P)RR [s(P)RR] which comprises of most of extracellular domain (ECD) exerts an antidiuretic action. although the versatile functions should be mediated through the interactions between (p)rr ecd and its respective binding partners, the one-to-many bindings has not been fully explained. Here we investigated the binding mode of this receptor by structural and evolutionary analyses using three-dimensional structural models of (P)RR, which were predicted by the AlphaFold2 (AF2) program, a machine learning-based algorithm capable of predicting protein structure to near experimental accuracy. Design and method: Monoclonal antibodies against (P)RR reduce the Wnt/beta-catenin-dependent development of pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic cancer. Antibodies against two (P)RR regions (residues 47–60 and 200–213) located in ECD reduce the proliferation of human PDAC cells in vitro. The spatial distribution of the two regions was examined using human (P)RR AF2 structural models (monomer and dimer). The evolutionary conservation profile and hydrophobicity were mapped on the models. Results: The dimer structure predicted by AF2 shows that (P)RR homodimerizes via ECD, which explains the experimentally proven dimer formation. The 47–60 and 200–213 regions of (P)RR formed a continuous surface patch on the structural model, which comprised evolutionarily conserved hydrophobic residues. The dimer model revealed the presence of two hand-like grooves, with 47–60 and 200–213 regions as its palm and 270–296 region (intrinsically disordered region, IDR) as its fingers. Conclusions: Considering conformational flexibility of IDR allowing for multiple protein interactions, we propose that the grooves may act as a binding interface with Wnt signaling molecules and antibodies against the grooves probably interfere with the formation of Wnt receptor complex due to steric hindrance and direct competition with the binding interface residues. The hydrophobic nature of the grooves may explain why (P)RR shows one-to-many bindings underpinning its functional versatility. This study provides new insights into the binding mode of (P)RR for the first time. s(P)RR is considered a useful biomarker for diseases, including essential hypertension and cancer. Our findings may help explore a new treatment and biomarker testing of human diseases, and contribute to quality of life in a longevity society.

Mapping the protein binding site of the (pro)renin receptor using in silico 3D structural analysis

We have previously reported that monoclonal antibodies against the (pro)renin receptor [(P)RR] can reduce the Wnt/β-catenin-dependent development of pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic cancer. Antibodies against two (P)RR regions (residues 47–60 and 200–213) located in the extracellular domain (ECD) reduced the proliferation of human PDAC cells in vitro. Although these regions probably participate in the activation of Wnt/β-catenin signaling, their functional significance remains unclear. Moreover, the (P)RR ECD is predicted to possess an intrinsically disordered region (IDR), which allows multiple protein interactions because of its conformational flexibility. In this study, we investigated the significance of the two regions and the IDR by in silico 3D structural analysis using the AlphaFold2 program and evolutionary sequence conservation profile. The model showed that ECD adopted a folded domain (residues 17–269) and had an IDR (residues 270–296). The two regions mapped onto the structural model formed a continuous surface patch comprising evolutionarily conserved hydrophobic residues. The homodimeric structure predicted by AlphaFold2 showed that full-length (P)RR comprising the ECD, single-span transmembrane, and cytoplasmic domains formed a twofold symmetric dimer via the ECD, which explains the experimentally proven homodimerization. The dimer model possessed two hand-shaped grooves with residues 47–60 and 200–213 in their palms and the IDR as their fingers. Based on these findings, we propose that the IDR-containing hydrophobic grooves act as a binding site for (P)RR and perform multiple functions, including Wnt signaling activation.Antibodies against the (pro)renin receptor residues 47–60 and 200–213 can inhibit pancreatic ductal adenocarcinoma (PDAC) cell proliferation by suppressing Wnt signaling. This study provides 3D structural insights into receptor binding and one-to-many interactions, which underpin the functional versatility of this receptor.

Abstract 11064: Role of Renin-Angiotensin System Axis in Human Abdominal Aortic Aneurysm

Introduction: Renin-Angiotensin System (RAS) regulates the cardiovascular system and has been implicated in the development of abdominal aortic aneurysm (AAA). RAS modulates function via balancing the ACE/Chymase/AngII-AT1 receptor and ACE-2/Ang(1-7)-Mas receptor axis. Preferential activation of the ACE/Chymase/AngII-AT1 receptor pathway of the RAS contributes to dysregulation of cardiovascular system and disease while the Ang(1-7)-MasR axis contributes to anti-inflammatory pathways. Therefore, identifying the RAS axis mechanism involved in growth, progression, or the risk of rupture in AAA humans could bring a novel treatment perspective. Hypothesis: We hypothesize that in the AAA, the local RAS is altered such as it favours the ACE/AngII/AT1R axis while decreasing the ACE-2/Ang(1-7)/MasR pathway, with consequent AAA development. Objective: We sought to investigate the expression of RAS components in the AAA human aorta. Methods: Aorta tissue from AAA patients (n=21) was collected during the AAA conventional repair surgery, and aorta control aortas were obtained from organ donors (Control, n=11). Protein expression of renin, chymase, ACE, ACE-2 AT1, AT2, and MAS receptors was analyzed by Western Blotting. Results: Our AAA cohort consisted mostly males (76.6% AAA vs. 63.6% Control, p=0.68), smokers or ex-smokers (90.4% AAA vs. 36.3% Control, p=0.002) and most of them had hypertension(71.4% AAA vs. 36.3% Control, p=0.07). Analysis of protein expression in the AAA group showed that ACE and AT1 receptors were upregulated compared with Control (p=0.05; p=0.02, respectively,), while chymase expression was decreased in AAA compared to the control (p=0.03). Additionally, the AAA group showed downregulation in ACE-2 and AT2 compared with Control (respectively, p=0.01, p=0.03). There was no significant difference in the expression of renin and MAS receptors between groups (p=0.52, p=0.41, respectively,). Conclusions: Our data show that the ACE/AT1R axis was upregulated while ACE-2 and AT2 receptors were downregulated in the AAA aorta. Our results implicate local RAS in AAA development and warrant further studies.

Loss of Soluble (Pro) Renin Receptor Attenuates Adenine Induced Kidney Disease

Loss of Soluble (Pro) Renin Receptor Attenuates Adenine Induced Kidney Disease

ODP139 Association between serum soluble (pro)renin receptor level and worsening of cardiac function in hemodialysis patients: A prospective observational study

Abstract A total of 258 maintenance HD patients were recruited and serum s(P)RR concentration was measured. Background factors in patients who survived (S group) and patients who died (D group) during the 12-month follow-up period and relationships between serum s(P)RR level and changes in cardiac function during the follow-up period in the S group were investigated. The median serum s(P)RR value at baseline was29.8 ng/ml. Twenty-four patients died during the follow-up period. Cardiothoracic ratio, human atrial natriuretic peptide (hANP), brain natriuretic peptide (BNP), and E over e-prime were significantly higher in the D group. In the S group, changes in hANP or BNP were significantly greater in the higher serum s(P)RR group than in the lower serum s(P)RR group. High serum s(P)RR level was significantly correlated with changes in BNP, independent of other factors. High serum s(P)RR level was associated with increases in BNP, independent of other risk factors, suggesting that an increased expression of (P)RR may be associated with a progression of heart failure in HD patients and that serum s(P)RR concentration could be used as a biomarker for selecting patients requiring intensive care. Presentation: No date and time listed

Mutagenesis of the cleavage site of (pro)renin receptor abrogates aldosterone-salt-induced hypertension and renal injury in mice.

Soluble (pro)renin receptor (sPRR), the extracellular domain of (pro)renin receptor (PRR), is primarily generated by site-1 protease and furin. It has been reported that sPRR functions as an important regulator of intrarenal renin contributing to angiotensin II (ANG II)-induced hypertension. Relatively, less is known for the function of sPRR in ANG II-independent hypertension such as mineralocorticoid excess. In the present study, we used a novel mouse model with mutagenesis of the cleavage site in PRR (termed as PRRR279V/L282V or mutant) to examine the phenotype during aldosterone (Aldo)-salt treatment. The hypertensive response of mutant mice to Aldo-salt treatment was blunted in parallel with the attenuated response of plasma volume expansion and renal medullary α-epithelial Na+ channel expression. Moreover, Aldo-salt-induced hypertrophy in the heart and kidney as well as proteinuria were improved, accompanied by blunted polydipsia and polyuria. Together, these results represent strong evidence favoring endogenous sPRR as a mediator of Aldo-salt-induced hypertension and renal injury.NEW & NOTEWORTHY We used a novel mouse model with mutagenesis of the cleavage site of PRR to support soluble PRR as an essential mediator of aldosterone-salt-induced hypertension and also as a potential therapeutic target for patients with mineralocorticoid excess. We firstly report that soluble PRR-dependent pathway medicates the Na+-retaining action of aldosterone in the distal nephron, which opens up a new area for a better understanding of the molecular basis of renal handling of Na+ balance and blood pressure.

PGE2 stimulates aldosterone release via cAMP/sPRR/β-catenin pathway in mouse inner medullary collecting duct cells

Increasing evidence showed the generation of aldosterone in the collecting duct (CD), a major site for the synthesis and action of prostaglandin E2 (PGE2). Both aldosterone and PGE2 are stimulated by Na+ depletion or K+ loading or angiotensin II. However, what happens first and the correlation between PGE2 and aldosterone in the CD remains obscure. PGE2 stimulates aldosterone release in the adrenal zona glomerulosa cells via E-prostanoid (EP) receptors by activating the cAMP/cAMP-responsive element-binding pathway. Here, we further tested the hypothesis that the synthesis of aldosterone is stimulated by PGE2 in CD cells and the underlying mechanism. In primary mouse inner medullary CD cells, PGE2 incubation significantly stimulated aldosterone release in parallel with an increase of CYP11B2 (cytochrome P-450, family 11, subfamily B, polypeptide 2), (pro)renin receptor (PRR), and prorenin protein expression and upregulation of medium soluble PRR (sPRR), prorenin/renin, and cAMP levels, both of which were attenuated by the EP1 antagonist SC-19220 and the protein kinase C (PKC) inhibitor calphostin C. PGE2-induced release of aldosterone, prorenin/renin, and sPRR was also abolished by the protein kinase A inhibitor H89. Both a PRR antagonist PRO20 and β-catenin inhibitor ICG001 blunted PGE2 or sPRR-induced aldosterone and prorenin/renin secretion. Exogenous sPRR protein incubation not only stimulated the release of aldosterone and prorenin/renin but also reversed PF429242 (an inhibitor of subtilisin kexin isozyme-1, which can block endogenous sPRR generation)-attenuated aldosterone and prorenin/renin secretion. Therefore, we conclude that PGE2 increases CD aldosterone synthesis through the EP1 receptor via the PKC/cAMP/sPRR/β-catenin pathway.