The Experts below are selected from a list of 1587 Experts worldwide ranked by ideXlab platform
A Jan H Danser - One of the best experts on this subject based on the ideXlab platform.
-
Prorenin periconceptionally and in pregnancy does it have a physiological role
Molecular and Cellular Endocrinology, 2021Co-Authors: Rosalieke E Wiegel, Frauke Von Versenhoynck, Regine P M Steegerstheunissen, Eric A P Steegers, A Jan H DanserAbstract:Pregnancy demands major cardiovascular, renal and endocrine changes to provide an adequate blood supply for the growing fetus. The renin-angiotensin-aldosterone system plays a key role in this adaptation process. One of its components, Prorenin, is released in significant amounts from the ovary and uteroplacental unit. This review describes the sources of Prorenin in the periconception period and in pregnancy, including its modulation by in-vitro fertilization protocols, and discusses its potential effects, among others focusing on preeclampsia. It ends with discussing the long-term consequences, even in later life, of inappropriate renin-angiotensin-aldosterone system activity in pregnancy and offers directions for future research. Ultimately, a full understanding of the role of Prorenin periconceptionally and during pregnancy will help to develop tools to diagnose and/or prevent reproductive complications.
-
megalin a novel endocytic receptor for Prorenin and renin
Hypertension, 2020Co-Authors: Ingrid M Garrelds, Yuan Sun, Alexandre Goes Martini, Manoe J Janssen, Rosalinde Masereeuw, A Jan H DanserAbstract:Megalin is an endocytic receptor contributing to protein reabsorption. Impaired expression or trafficking of megalin increases urinary renin and allowed the detection of Prorenin, which normally is absent in urine. Here, we investigated (pro)renin uptake by megalin, using both conditionally immortalized proximal tubule epithelial cells and Brown Norway Rat yolk sac cells (BN16). To distinguish binding and internalization, cells were incubated with recombinant human (pro)renin at 4°C and 37°C, respectively. (Pro)renin levels were assessed by immunoradiometric assay. At 4°C, BN16 cells bound 3× more Prorenin than renin, suggestive for a higher affinity of Prorenin. Similarly, at 37°C, Prorenin accumulated at 3- to 4-fold higher levels than renin in BN16 cells. Consequently, depletion of medium Prorenin (but not renin) content occurred after 24 hours. No such differences were observed in conditionally immortalized proximal tubule epithelial cells, and M6P (mannose-6-phosphate) greatly reduced conditionally immortalized proximal tubule epithelial cells (pro)renin uptake, suggesting that these cells accumulate (pro)renin largely via M6P receptors. M6P did not affect (pro)renin uptake in BN16 cells. Yet, inhibiting megalin expression with siRNA greatly reduced (pro)renin binding and internalization by BN16 cells. Furthermore, treating BN16 cells with albumin, an endogenous ligand of megalin, also decreased binding and internalization of (pro)renin, while deleting the (pro)renin receptor affected the latter only. Exposing Prorenin's prosegment with the renin inhibitor aliskiren dramatically increased Prorenin binding, while after prosegment cleavage with trypsin Prorenin binding was identical to that of renin. In conclusion, megalin might function as an endocytic receptor for (pro)renin and displays a preference for Prorenin. Megalin-mediated endocytosis requires the (pro)renin receptor.
-
Renin and Prorenin Renin- and Prorenin-Induced Effects in Rat Vascular Smooth Muscle Cells Overexpressing the Human (Pro)Renin Receptor Does (Pro)Renin-(Pro)Renin Receptor Interaction Actually Occur?
2016Co-Authors: Wendy W Batenburg, Ulrike Maschke, Frank Leijten, Dominik N. Müller, A Jan H DanserAbstract:Abstract—Renin/Prorenin binding to the (pro)renin receptor ([P]RR) results in direct (angiotensin-independent) second-messenger activation in vitro, whereas in vivo studies in rodents overexpressing Prorenin (400-fold) or the (P)RR do not support such activation. To solve this discrepancy, DNA synthesis, extracellular signal–regulated kinase 1/2 phosphorylation, and plasminogen-activator inhibitor 1 release were evaluated in wild-type and human (P)RR-overexpressing vascular smooth muscle cells after their incubation with 1 to 80 nmol/L of (pro)renin. Human Prorenin (4 nmol/L, ie, 800-fold above normal) angiotensinogen increased DNA synthesis in human (P)RR cells only in an angiotensin II type 1 receptor–dependent manner. Prorenin at this concentration also increased plasminogen-activator inhibitor 1 release via angiotensin. Prorenin alone at 4 nmol/L was without effect, but at 20 nmol/L (4000-fold above normal) it activated extracellular signal–regulated kinase 1/2 directly (ie, independent of angiotensin). Renin at concentrations of 1 nmol/L (2000-fold above normal) and higher directly stimulated DNA synthesis, extracellular signal–regulated kinase 1/2 phosphorylation, and plasminogen-activator inhibitor 1 release in wild-type and human (P)RR cells, and similar effects were seen for rat renin, indicating that they were mediated via the rat (P)RR. In conclusion, angiotensin generation depending on Prorenin-(P)RR interaction may occur in transgenic rodents overexpressing Prorenin several 100-fold. Direct (pro)renin-induced effects via the (P)RR require agonist concentrations that are far above the levels in wild-type and transgenic rats. Therefore, only Prorenin (and not [P]RR) overexpressio
-
Combined Renin Inhibition/(Pro)Renin Receptor Blockade in Diabetic Retinopathy- A Study in Transgenic (mREN2)27 Rats
2016Co-Authors: Wendy W Batenburg, Mieke Van Den Heuvel, Amrisha Verma, Yunyang Wang, Ping Zhu, Richard Van Veghel, A Jan H DanserAbstract:Dysfunction of renin-angiotensin system (RAS) contributes to the pathogenesis of diabetic retinopathy (DR). Prorenin, the precursor of renin is highly elevated in ocular fluid of diabetic patients with proliferative retinopathy. Prorenin may exert local effects in the eye by binding to the so-called (pro)renin receptor ((P)RR). Here we investigated the combined effects of the renin inhibitor aliskiren and the putative (P)RR blocker handle-region peptide (HRP) on diabetic retinopathy in streptozotocin (STZ)-induced diabetic transgenic (mRen2)27 rats (a model with high plasma Prorenin levels) as well as Prorenin stimulated cytokine expression in cultured Müller cells. Adult (mRen2)27 rats were randomly divided into the following groups: (1) non-diabetic; (2) diabetic treated with vehicle; (3) diabetic treated with aliskiren (10 mg/kg per day); and (4) diabetic treated with aliskiren+HRP (1 mg/kg per day). Age-matched non-diabetic wildtype Sprague-Dawley rats were used as control. Drugs were administered by osmotic minipumps for three weeks. Transgenic (mRen2)27 rat retinas showed increased apoptotic cell death of both inner retinal neurons and photoreceptors, increased loss of capillaries, as well as increased expression of inflammatory cytokines. These pathological changes were further exacerbated by diabetes. Aliskiren treatment of diabetic (mRen2)27 rats prevented retinal gliosis, and reduced retinal apoptotic cell death, acellular capillaries and the expression of inflammatory cytokines. HRP on top of aliskiren did not provide additional protection. In cultured Müller cells, Prorenin significantly increased the expression levels of IL-1a and TNF-a, and this was completel
-
pro renin receptor is required for Prorenin dependent and independent regulation of vacuolar h atpase activity in mdck c11 collecting duct cells
American Journal of Physiology-renal Physiology, 2013Co-Authors: Ingrid M Garrelds, A Jan H Danser, Carsten A Wagner, Marcel E MeimaAbstract:Prorenin binding to the Prorenin receptor [(P)RR] results in nonproteolytic activation of Prorenin but also directly (i.e., independent of angiotensin generation) activates signal transduction cascades that can lead to the upregulation of profibrotic factors. The (P)RR is an accessory protein of vacuolar-type H⁺-ATPase (V-ATPase) and is required for V-ATPase integrity. In addition, in collecting duct cells, Prorenin-induced activation of Erk depends on V-ATPase activity. However, whether Prorenin binding to the (P)RR directly regulates V-ATPase activity is as yet unknown. Here, we studied the effect of Prorenin on plasma membrane V-ATPase activity in Madin-Darby canine kidney clone 11 (MDCK.C11) cells, which resemble intercalated cells of the collecting duct. Prorenin increased V-ATPase activity at low nanomolar concentrations, and the V-ATPase inhibitor bafilomycin A1, but not the angiotensin II type 1 and 2 receptor blockers irbesartan and PD-123319, prevented this. Increased, but not basal, V-ATPase activity was abolished by small interfering RNA depletion of the (P)RR. Unexpectedly, the putative peptidic (P)RR blocker handle region peptide also increased V-ATPase activity in a (P)RR-dependent manner. Finally, [Arg⁸]-vasopressin-stimulated V-ATPase activity and cAMP production were also abolished by (P)RR depletion. Our results show that in MDCK.C11 cells, the (P)RR is required for Prorenin-dependent and -independent regulation of V-ATPase activity.
Maarten A D H Schalekamp - One of the best experts on this subject based on the ideXlab platform.
-
Asynchronous Changes in Prorenin and Renin Secretion after Captopril in Patients with Renal Artery Stenosis
2016Co-Authors: Maarten A D H SchalekampAbstract:SUMMARY An assay of plasma Prorenin was developed in which the conversion to renin occurred under apparently optimal conditions. Some characteristics of the assay were 1) Prorenin was activated by Sepharose-bound trypsin at 4°C; 2) the concentration of activator was not critical provided that incubation was prolonged until renin activity had reached a plateau; and 3) this plateau was stable and had the same height as after maximal activation with acid, pepsin, plasmin or urokinase. Maximal activity with Sepharose-bound trypsin at 4°C was higher than with cryoactivation, and optimal conditions were more readily reproduced than with trypsin at 37°C or with acid-activation. The assay was used for measurements in peripheral and renal vein plasma after captopril in hypertensive patients with unilateral renal artery stenosis. Peripheral renin rose within 30 minutes after a first dose of captopril, 50 mg orally, and it remained high with chronic treatment. In contrast, peripheral Prorenin fell initially and rose after 4 hours. These changes in peripheral plasma were related to changes in the secretion rates of the two forms of renin from the affected kidney. Thus chronic, but not acute, stimulation of renin release was associated with an increased secretion rate of Prorenin. The late rise in Prorenin is probably an indication of enhanced synthesis in the kidney, so that more Prorenin is available for conversion. The data suggest that Prorenin is indeed a biosynthetic precurso
-
new renin inhibitor vtp 27999 alters renin immunoreactivity and does not unfold Prorenin
Hypertension, 2013Co-Authors: Manne Krop, Maarten A D H Schalekamp, Jeanette M G Van Gool, Koen Verdonk, Brian M Mckeever, Richard Gregg, A Jan H DanserAbstract:Renin inhibitors like aliskiren not only block renin but also bind Prorenin, thereby inducing a conformational change (like the change induced by acid) allowing its recognition in a renin-specific assay. Consequently, aliskiren can be used to measure Prorenin. VTP-27999 is a new renin inhibitor with an aliskiren-like IC 50 and t 1/2 , and a much higher bioavailability. This study addressed (pro)renin changes during treatment of volunteers with VTP-27999 or aliskiren. Both drugs increased renin immunoreactivity. Treatment of plasma samples from aliskiren-treated subjects with excess aliskiren yielded higher renin immunoreactivity levels, confirming the presence of Prorenin. Unexpectedly, this approach did not work in VTP-27999–treated subjects, although an assay detecting the prosegment revealed that their blood still contained Prorenin. Subsequent in vitro analysis showed that VTP-27999 increased renin immunoreactivity for a given amount of renin by ≥30% but did not unfold Prorenin. Yet, it did bind to acid-activated, intact Prorenin and then again increased immunoreactivity in a renin assay. However, no such increase in immunoreactivity was seen when measuring acid-activated Prorenin bound to VTP-27999 with a prosegment-directed assay. The VTP-27999–induced rises in renin immunoreactivity could be competitively prevented by aliskiren, and antibody displacement studies revealed a higher affinity of the active site-directed antibodies in the presence of VTP-27999. In conclusion, VTP-27999 increases renin immunoreactivity in renin immunoassays because it affects the affinity of the active site-directed antibody. Combined with its lack of effect on Prorenin, these data show that VTP-27999 differs from aliskiren. The clinical relevance of these results needs to be established.
-
newly developed renin and Prorenin assays and the clinical evaluation of renin inhibitors
Journal of Hypertension, 2008Co-Authors: Maarten A D H Schalekamp, F H M Derkx, Jaap Deinum, Alexander H. J. DanserAbstract:BACKGROUND: The last decade has seen the introduction of renin inhibitors and new plasma renin and Prorenin assays, which has led to a better understanding of the tissue renin-angiotensin system. AIM OF THE STUDY: To clarify the consequences of these developments for the methodology and interpretation of measurements of renin and Prorenin. METHODS: The principles and application of the newly developed immunosorbent assays (ISAs) are surveyed and the results are compared with those of enzyme-kinetic assays (EKAs). RESULTS AND CONCLUSIONS: Angiotensin (Ang) II in cardiac, renal and adrenal tissue is known to originate mainly from locally produced Ang I. Experimental evidence and theoretical considerations show that a simple relation between Ang II receptor occupancy, in tissue micromilieu, and the circulating levels of Ang II or renin may not exist. This supports the clinicians' view that the plasma level of renin tells more about the mechanisms regulating its release into the circulation than about the Ang II-dependency of hypertension. ISAs are a welcome addition to clinical studies of renin inhibitors. By comparing the results of ISAs with those of EKAs, the inhibitor-bound forms of renin and Prorenin can be distinguished from the unbound forms. ISAs also provide important information on the molecular basis of Prorenin activation. We propose a single kinetic model to incorporate the conformational changes of Prorenin induced by cryo-activation and acid-activation, and by binding to renin inhibitors. It explains why renin ISAs can overestimate the rise of renin in response to these drugs, and shows how to deal with this artefact.
-
Prorenin induced myocyte proliferation no role for intracellular angiotensin ii
Hypertension, 2002Co-Authors: Jasper J Saris, Jos M J Lamers, Pramod R Saxena, Maarten A D H Schalekamp, Mark M E D Van Den Eijnden, A Jan H DanserAbstract:Cardiomyocytes bind, internalize, and activate Prorenin, the inactive precursor of renin, via a mannose 6-phosphate receptor (M6PR)--dependent mechanism. M6PRs couple directly to G-proteins. To investigate whether Prorenin binding to cardiomyocytes elicits a response, and if so, whether this response depends on angiotensin (Ang) II, we incubated neonatal rat cardiomyocytes with 2 nmol/L Prorenin and/or 150 nmol/L angiotensinogen, with or without 10 mmol/L M6P, 1 micromol/L eprosartan, or 1 micromol/L PD123319 to block M6P and AT(1) and AT(2) receptors, respectively. Protein and DNA synthesis were studied by quantifying [(3)H]-leucine and [(3)H]-thymidine incorporation. For comparison, studies with 100 nmol/L Ang II were also performed. Neither Prorenin alone, nor angiotensinogen alone, affected protein or DNA synthesis. Prorenin plus angiotensinogen increased [(3)H]-leucine incorporation (+21 +/- 5%, mean +/- SEM, P<0.01), [(3)H]-thymidine incorporation (+29 +/- 6%, P<0.01), and total cellular protein (+14 +/- 3%, P<0.01), whereas Ang II increased DNA synthesis only (+34 +/- 7%, P<0.01). Eprosartan, but not PD123319 or M6P, blocked the effects of Prorenin plus angiotensinogen as well as the effects of Ang II. Medium Ang II levels during Prorenin and angiotensinogen incubation were <1 nmol/L. In conclusion, Prorenin binding to M6PRs on cardiomyocytes per se does not result in enhanced protein or DNA synthesis. However, through Ang II generation, Prorenin is capable of inducing myocyte hypertrophy and proliferation. Because this generation occurs independently of M6PRs, it most likely depends on the catalytic activity of intact Prorenin in the medium (because of temporal prosegment unfolding) rather than its intracellular activation. Taken together, our results do not support the concept of Ang II generation in cardiomyocytes following intracellular Prorenin activation.
-
Prorenin accumulation and activation in human endothelial cells importance of mannose 6 phosphate receptors
Arteriosclerosis Thrombosis and Vascular Biology, 2001Co-Authors: Mark M E D Van Den Eijnden, Timothy L. Reudelhuber, F H M Derkx, Maarten A D H Schalekamp, Rene J A De Bruin, Jasper J Saris, Elly De Wit, Wim Sluiter, A Jan H DanserAbstract:ACE inhibitors improve endothelial dysfunction, possibly by blocking endothelial angiotensin production. Prorenin, through its binding and activation by endothelial mannose 6-phosphate (M6P) receptors, may contribute to this production. Here, we investigated this possibility as well as Prorenin activation kinetics, the nature of the Prorenin-activating enzyme, and M6P receptor-independent Prorenin binding. Human umbilical vein endothelial cells (HUVECs) were incubated with wild-type Prorenin, K/A-2 Prorenin (in which Lys42 is mutated to Ala, thereby preventing cleavage by known proteases), M6P-free Prorenin, and nonglycosylated Prorenin, with or without M6P, protease inhibitors, or angiotensinogen. HUVECs bound only M6P-containing Prorenin (K(d) 0.9+/-0.1 nmol/L, maximum number of binding sites [B(max)] 1010+/-50 receptors/cell). At 37 degrees C, because of M6P receptor recycling, the amount of Prorenin internalized via M6P receptors was >25 times B(max). Inside the cells, wild-type and K/A-2 Prorenin were proteolytically activated to renin. Renin was subsequently degraded. Protease inhibitors interfered with the latter but not with Prorenin activation, thereby indicating that the activating enzyme is different from any of the known Prorenin-activating enzymes. Incubation with angiotensinogen did not lead to endothelial angiotensin generation, inasmuch as HUVECs were unable to internalize angiotensinogen. Most likely, therefore, in the absence of angiotensinogen synthesis or endocytosis, M6P receptor-mediated Prorenin internalization by endothelial cells represents Prorenin clearance.
Atsuhiro Ichihara - One of the best experts on this subject based on the ideXlab platform.
-
enhanced intrarenal receptor mediated Prorenin activation in chronic progressive anti thymocyte serum nephritis rats on high salt intake
American Journal of Physiology-renal Physiology, 2012Co-Authors: Yanjie Huang, Atsuhiro Ichihara, Tatsuo Yamamoto, Taro Misaki, Hiroyuki Suzuki, Akashi Togawa, Naro Ohashi, Hirotaka Fukasawa, Yoshihide Fujigaki, Akira NishiyamaAbstract:Despite suppression of the circulating renin-angiotensin system (RAS), high salt intake (HSI) aggravates kidney injury in chronic kidney disease. To elucidate the effect of HSI on intrarenal RAS, we investigated the levels of intrarenal Prorenin, renin, (pro)renin receptor (PRR), receptor-mediated Prorenin activation, and ANG II in chronic anti-thymocyte serum (ATS) nephritic rats on HSI. Kidney fibrosis grew more severe in the nephritic rats on HSI than normal salt intake. Despite suppression of plasma renin and ANG II, marked increases in tubular Prorenin and renin proteins without concomitant rises in renin mRNA, non-proteolytically activated Prorenin, and ANG II were noted in the nephritic rats on HSI. Redistribution of PRR from the cytoplasm to the apical membrane, along with elevated non-proteolytically activated Prorenin and ANG II, was observed in the collecting ducts and connecting tubules in the nephritic rats on HSI. Olmesartan decreased cortical Prorenin, non-proteolytically activated Prorenin and ANG II, and apical membranous PRR in the collecting ducts and connecting tubules, and attenuated the renal lesions. Cell surface trafficking of PRR was enhanced by ANG II and was suppressed by olmesartan in Madin-Darby canine kidney cells. These data suggest the involvement of the ANG II-dependent increase in apical membrane PRR in the augmentation of intrarenal binding of Prorenin and renin, followed by nonproteolytic activation of Prorenin, enhancement of renin catalytic activity, ANG II generation, and progression of kidney fibrosis in the nephritic rat kidneys on HSI. The origin of the increased tubular Prorenin and renin remains to be clarified. Further studies measuring the urinary Prorenin and renin are needed.
-
Prorenin receptor is essential for normal podocyte structure and function
Journal of The American Society of Nephrology, 2011Co-Authors: Yoichi Oshima, Atsuhiro Ichihara, Mariyo Sakoda, Kenichiro Kinouchi, Asako Kurauchimito, Kanako Bokuda, Tatsuya Narita, Hideaki Kurosawa, Gehong Sunwada, Yoh WadaAbstract:The Prorenin receptor is an accessory subunit of the vacuolar H+-ATPase, suggesting that it has fundamental functions beyond activation of the local renin-angiotensin system. Podocytes express the Prorenin receptor, but its function in these cells is unknown. Here, podocyte-specific, conditional, Prorenin receptor-knockout mice died of kidney failure and severe proteinuria within 4 weeks of birth. The podocytes of these mice exhibited foot process effacement with reduced and altered localization of the slit-diaphragm proteins nephrin and podocin. Furthermore, the podocytes contained numerous autophagic vacuoles, confirmed by enhanced accumulation of microtubule-associated protein 1 light chain 3-positive intracellular vesicles. Ablation of the Prorenin receptor selectively suppressed expression of the V0 c-subunit of the vacuolar H+-ATPase in podocytes, resulting in deacidification of intracellular vesicles. In conclusion, the Prorenin receptor is important for the maintenance of normal podocyte structure and function.
-
Prorenin induces vascular smooth muscle cell proliferation and hypertrophy via epidermal growth factor receptor mediated extracellular signal regulated kinase and akt activation pathway
Journal of Hypertension, 2011Co-Authors: Daisuke Nakano, Hirofumi Hitomi, Naohisa Hosomi, Hideyasu Kiyomoto, Masakazu Kohno, Gang Liu, Yuki Shibayama, Yasuyoshi Yamaji, Atsuhiro IchiharaAbstract:BACKGROUND It is widely acknowledged that the (pro)renin receptor mediates angiotensin (Ang) II-dependent and Ang II-independent effects of Prorenin. METHOD We examined the effect of Prorenin on vascular smooth muscle cell (VSMC) signal transduction, proliferation, and hypertrophy. RESULTS Recombinant rat Prorenin dose-dependently increased extracellular signal-regulated kinase (ERK) 1/2 and Akt phosphorylation in rat VSMCs. Prorenin also significantly increased cell number, and [H]-thymidine and [H]-leucine incorporation, which were attenuated by pretreatment with inhibitors for ERK kinase and phosphatidylinositol 3 kinase. Prorenin was also found to stimulate epidermal growth factor (EGF) receptor and Src phosphorylation. Pretreatment of VSMCs with an EGF receptor tyrosine kinase inhibitor and a Src inhibitor significantly attenuated the Prorenin-induced increase in ERK 1/2 and Akt phosphorylation, as well as DNA and protein synthesis. Prorenin-induced phosphorylation of the EGF receptor, ERK 1/2, and Akt, as well as DNA and protein synthesis were all blocked by (pro)renin receptor siRNA, but not by an Ang II type 1 receptor blocker, candesartan, nor an Ang-converting enzyme inhibitor, captopril. CONCLUSION These results reveal that Prorenin directly stimulates VSMC proliferative and hypertrophic changes, dependent on the (pro)renin receptor, independent of Ang II. Furthermore, EGF receptor-mediated ERK 1/2 and Akt activation contributes to Prorenin-dependent proliferative and hypertrophic effects in VSMCs.
-
Aliskiren binds to renin and Prorenin bound to (pro)renin receptor in vitro.
Hypertension Research, 2010Co-Authors: Kazal Boron Biswas, Tsutomu Nakagawa, Atsuhiro Ichihara, Tadashi Inagami, A.h.m. Nurun Nabi, Yoshie Arai, Akio Ebihara, Toshifumi Watanabe, Fumiaki SuzukiAbstract:Human (pro)renin receptor ((P)RR) has been implicated in the augmentation of many biological and cellular processes through bindings to its ligands, renin and Prorenin. In this study, we investigated the effects of aliskiren, a direct oral renin inhibitor, on the activities of free and (P)RR-bound forms of human mature renin. We also elucidated the effect of aliskiren on the 'renin activity' of the receptor-bound form of Prorenin. Aliskiren had an IC(50) of 0.72 nmol l(-1) against renin. The compound competitively inhibited renin activity with an inhibitory constant (K(i)) of 0.18 nmol l(-1). Furthermore, the dissociation constants (K(D)) for aliskiren from renin and Prorenin bound to (P)RR were determined using surface plasmon resonance in a BIAcore assay system (Uppsala, Sweden). These values were estimated to be 0.46 ± 0.03 and 0.25 ± 0.01 nmol l(-1), respectively. The compound competitively inhibited the renin activities of (P)RR-bound forms of both renin and Prorenin with a K(i) of 0.14 and 0.15 nmol l(-1), respectively. These results indicate that aliskiren could be a potent inhibitor of the free forms of mature renin and of the receptor-bound forms of renin and Prorenin.
-
Prorenin has high affinity multiple binding sites for pro renin receptor
Biochimica et Biophysica Acta, 2009Co-Authors: A Nurun H M Nabi, Tsutomu Nakagawa, Atsuhiro Ichihara, Tadashi Inagami, Kazal Boron Biswas, Fumiaki SuzukiAbstract:An important role of the decoy peptide sequence has recently been suggested in vitro for the binding of Prorenin to the (pro)renin receptor [PRR]. In this study, other prospective crucial regions in renin and Prorenin responsible for their interaction with PRR were investigated using various kinds of peptides, e.g., the "hinge" S149QGVLKEDVF158 designed from the structure of renin also common to Prorenin, L1PPTDTTTF8P, L1PPTDTTTFKRIFLKR15P and the decoy (R10PIFLKRMPSI19P) designed from the predicted structure of Prorenin. For the kinetic analysis, the recombinant hPRR was immobilized on the biosensor surface through a specific anti-PRR antibody. In case of the equilibrium state analysis, the PRR was directly adsorbed on plastic wells for observing the bindings of renin/Prorenin. The dissociation constants (KD) for the bindings of renin and Prorenin to the pre-adsorbed receptors were 4.5 and 1.0 nM, respectively, similar to those stated in the kinetic study by BIAcore assay. The "hinge" region peptide bound to PRR in a dose-dependent manner with a KD estimated 17.0 nM which was five times higher than that of the decoy. The KD values for L1PPTDTTTF8P and L1PPTDTTTFKRIFLKR15P were 52 and 7.6 nM, respectively. The "hinge" peptide, as the decoy, inhibited the bindings of renin and Prorenin to PRR. The inhibition constant (Ki) for the binding of renin and Prorenin by the decoy and "hinge" were 16.7 and 15.1, and 37.1 and 30.7 nM, respectively. These in vitro studies suggest that renin has a single and Prorenin has at least two high affinity binding sites for the PRR.
Fumiaki Suzuki - One of the best experts on this subject based on the ideXlab platform.
-
Aliskiren binds to renin and Prorenin bound to (pro)renin receptor in vitro.
Hypertension Research, 2010Co-Authors: Kazal Boron Biswas, Tsutomu Nakagawa, Atsuhiro Ichihara, Tadashi Inagami, A.h.m. Nurun Nabi, Yoshie Arai, Akio Ebihara, Toshifumi Watanabe, Fumiaki SuzukiAbstract:Human (pro)renin receptor ((P)RR) has been implicated in the augmentation of many biological and cellular processes through bindings to its ligands, renin and Prorenin. In this study, we investigated the effects of aliskiren, a direct oral renin inhibitor, on the activities of free and (P)RR-bound forms of human mature renin. We also elucidated the effect of aliskiren on the 'renin activity' of the receptor-bound form of Prorenin. Aliskiren had an IC(50) of 0.72 nmol l(-1) against renin. The compound competitively inhibited renin activity with an inhibitory constant (K(i)) of 0.18 nmol l(-1). Furthermore, the dissociation constants (K(D)) for aliskiren from renin and Prorenin bound to (P)RR were determined using surface plasmon resonance in a BIAcore assay system (Uppsala, Sweden). These values were estimated to be 0.46 ± 0.03 and 0.25 ± 0.01 nmol l(-1), respectively. The compound competitively inhibited the renin activities of (P)RR-bound forms of both renin and Prorenin with a K(i) of 0.14 and 0.15 nmol l(-1), respectively. These results indicate that aliskiren could be a potent inhibitor of the free forms of mature renin and of the receptor-bound forms of renin and Prorenin.
-
Prorenin has high affinity multiple binding sites for pro renin receptor
Biochimica et Biophysica Acta, 2009Co-Authors: A Nurun H M Nabi, Tsutomu Nakagawa, Atsuhiro Ichihara, Tadashi Inagami, Kazal Boron Biswas, Fumiaki SuzukiAbstract:An important role of the decoy peptide sequence has recently been suggested in vitro for the binding of Prorenin to the (pro)renin receptor [PRR]. In this study, other prospective crucial regions in renin and Prorenin responsible for their interaction with PRR were investigated using various kinds of peptides, e.g., the "hinge" S149QGVLKEDVF158 designed from the structure of renin also common to Prorenin, L1PPTDTTTF8P, L1PPTDTTTFKRIFLKR15P and the decoy (R10PIFLKRMPSI19P) designed from the predicted structure of Prorenin. For the kinetic analysis, the recombinant hPRR was immobilized on the biosensor surface through a specific anti-PRR antibody. In case of the equilibrium state analysis, the PRR was directly adsorbed on plastic wells for observing the bindings of renin/Prorenin. The dissociation constants (KD) for the bindings of renin and Prorenin to the pre-adsorbed receptors were 4.5 and 1.0 nM, respectively, similar to those stated in the kinetic study by BIAcore assay. The "hinge" region peptide bound to PRR in a dose-dependent manner with a KD estimated 17.0 nM which was five times higher than that of the decoy. The KD values for L1PPTDTTTF8P and L1PPTDTTTFKRIFLKR15P were 52 and 7.6 nM, respectively. The "hinge" peptide, as the decoy, inhibited the bindings of renin and Prorenin to PRR. The inhibition constant (Ki) for the binding of renin and Prorenin by the decoy and "hinge" were 16.7 and 15.1, and 37.1 and 30.7 nM, respectively. These in vitro studies suggest that renin has a single and Prorenin has at least two high affinity binding sites for the PRR.
-
'Decoy peptide' region (RIFLKRMPSI) of Prorenin prosegment plays a crucial role in Prorenin binding to the (pro)renin receptor
International Journal of Molecular Medicine, 2009Co-Authors: A.h.m. Nurun Nabi, Tsutomu Nakagawa, Atsuhiro Ichihara, Tadashi Inagami, Kazal Boron Biswas, Fumiaki SuzukiAbstract:This study investigated a role of decoy peptide region (R 10P IFLKRMPSI 19P ) in Prorenin prosegment for Prorenin binding to the (pro)renin receptor using the surface plasmon resonance technique. Three kinds of anti-receptor antibodies labeled as anti-107/121, anti-221/235 and anti-His tag antibody were prepared. The respective antigens D 107 SVANSIHSLFSEET 121 (close to the N-terminal side of receptor), E 221 IGKRYGEDSEQFRD 235 (N-terminal side of the transmembrane part of receptor) and 10xHis sequence (C- terminus) were designed based on the sequence of the receptor. These antibodies were immobilized on the CM5 sensor chip by amine coupling and allowed to bind to the receptor. Human Prorenin, renin and the decoy bound to the receptor associated with antibodies. Their association (ka) and dissociation (kd) rate constants were measured and the dissociation constants (KD) were determined using Langmuir 1:1 kinetic binding model. The KD for interaction of Prorenin and receptor associated to anti-107/121, anti-221/235 and anti-His tag antibodies were 2.9, 1.2 and 7.8 nM, respectively and for renin they were 9.3, 4.4 and 7.1 nM. The decoy bound to the respective immobilized receptor-antibody complexes at KD's of 6.2, 3.5 and 15.2 nM. Prorenin, renin and decoy had lower KD at the nanomolar ranges compared to those of L 1P PTD 4P in the Prorenin prosegment and A 248 KKRLFDYVV 257 in the C-domain of mature renin. The decoy reduced the binding of not only Prorenin but also renin to (P)RR. These data are direct evidence that Prorenin, renin and the peptides bind to (P)RR and the decoy reduces Prorenin binding, supporting our hypothesis that decoy peptide region has a crucial role in Prorenin binding.
-
Non-proteolytic activation of Prorenin: activation by (pro)renin receptor and its inhibition by a Prorenin prosegment, "decoy peptide".
Frontiers in bioscience : a journal and virtual library, 2008Co-Authors: A. H.m.n. Nabi, Tsutomu Nakagawa, Atsuhiro Ichihara, Tadashi Inagami, Fumiaki SuzukiAbstract:Prorenin is the enzymatically inactive precursor of renin. Recent interest has focused on the nonproteolytic activation of Prorenin by antibodies and renin/Prorenin receptors since markedly increased levels of circulating Prorenin have been associated with both physiological and pathological changes. Prorenin has been considered to be activated in vivo proteolytically and/or non-proteolytically. It has been demonstrated in vitro the "gate" and "handle" regions in the Prorenin molecule is crucial for its non-proteolytic activation by a protein-protein interaction. Prorenin was also activated by the renin/Prorenin receptors. Decapeptides (10P-19P) known as "decoy" peptide and pentapeptides (11P-15P) named as "handle" region peptide, were observed to inhibit the binding of both Prorenins to receptors. The "handle" region plays an important role in Prorenin binding to the receptor and its enzymatic activity by non-proteolytic activation. Prorenin receptors so far revealed by animal experiments have indicated that the decoy peptide prevented diabetes nephropathy and retinopathy. It was postulated the existence of novel regulative system that stimulated signal transduction as well as that of renin-angiotensin system. These findings help to find out the clue to design useful drug with greater benefit on the end-organ damage in diabetes and hypertension than those of conventional renin-angiotensin system inhibitors.
-
Role of "handle" region of Prorenin prosegment in the non-proteolytic activation of Prorenin by binding to membrane anchored (pro)renin receptor.
Frontiers in bioscience : a journal and virtual library, 2007Co-Authors: Nabi A H M Nurun, Tsutomu Nakagawa, Atsuhiro Ichihara, Tadashi Inagami, Nasir M Uddin, Hideyuki Iwata, Fumiaki SuzukiAbstract:A role of the "handle" region in the Prorenin prosegment sequence was investigated to demonstrate the crucial non-proteolytic activation of Prorenin by binding to the recombinant (pro)renin receptor on the COS-7 cell membrane. The plasmid DNA containing either rat or human (pro)renin receptor was transfected into the COS-7 cells. The highest amount of receptor was observed on the COS-7 cell membrane after 18 h transfection. Of the total rat and human Prorenin, 90% and 50% were bound to each of the respective receptors, respectively. The Kd values were 0.89 and 1.8 nM, respectively. Rat Prorenin was activated non-proteolytically by the receptor. The Km was determined 1.0 microM when sheep angiotensinogen was used as the substrate. Human Prorenin was also activated by the receptor. The Km was 0.71 microM. Additionally, decapeptides (10P-19P) known as "decoy" peptide and pentapeptides (11P-15P) named "handle" region peptide, were observed to inhibit the binding of both Prorenins to receptors, respectively. The Ki were similar around 7 nM for both the peptides. Other two region peptides in the prosegment did not interfere the binding. These results show that the "handle" region probably plays a crucial role in Prorenin binding to the receptor and in its enzymic activity by non-proteolytic activation.
F H M Derkx - One of the best experts on this subject based on the ideXlab platform.
-
newly developed renin and Prorenin assays and the clinical evaluation of renin inhibitors
Journal of Hypertension, 2008Co-Authors: Maarten A D H Schalekamp, F H M Derkx, Jaap Deinum, Alexander H. J. DanserAbstract:BACKGROUND: The last decade has seen the introduction of renin inhibitors and new plasma renin and Prorenin assays, which has led to a better understanding of the tissue renin-angiotensin system. AIM OF THE STUDY: To clarify the consequences of these developments for the methodology and interpretation of measurements of renin and Prorenin. METHODS: The principles and application of the newly developed immunosorbent assays (ISAs) are surveyed and the results are compared with those of enzyme-kinetic assays (EKAs). RESULTS AND CONCLUSIONS: Angiotensin (Ang) II in cardiac, renal and adrenal tissue is known to originate mainly from locally produced Ang I. Experimental evidence and theoretical considerations show that a simple relation between Ang II receptor occupancy, in tissue micromilieu, and the circulating levels of Ang II or renin may not exist. This supports the clinicians' view that the plasma level of renin tells more about the mechanisms regulating its release into the circulation than about the Ang II-dependency of hypertension. ISAs are a welcome addition to clinical studies of renin inhibitors. By comparing the results of ISAs with those of EKAs, the inhibitor-bound forms of renin and Prorenin can be distinguished from the unbound forms. ISAs also provide important information on the molecular basis of Prorenin activation. We propose a single kinetic model to incorporate the conformational changes of Prorenin induced by cryo-activation and acid-activation, and by binding to renin inhibitors. It explains why renin ISAs can overestimate the rise of renin in response to these drugs, and shows how to deal with this artefact.
-
Prorenin accumulation and activation in human endothelial cells importance of mannose 6 phosphate receptors
Arteriosclerosis Thrombosis and Vascular Biology, 2001Co-Authors: Mark M E D Van Den Eijnden, Timothy L. Reudelhuber, F H M Derkx, Maarten A D H Schalekamp, Rene J A De Bruin, Jasper J Saris, Elly De Wit, Wim Sluiter, A Jan H DanserAbstract:ACE inhibitors improve endothelial dysfunction, possibly by blocking endothelial angiotensin production. Prorenin, through its binding and activation by endothelial mannose 6-phosphate (M6P) receptors, may contribute to this production. Here, we investigated this possibility as well as Prorenin activation kinetics, the nature of the Prorenin-activating enzyme, and M6P receptor-independent Prorenin binding. Human umbilical vein endothelial cells (HUVECs) were incubated with wild-type Prorenin, K/A-2 Prorenin (in which Lys42 is mutated to Ala, thereby preventing cleavage by known proteases), M6P-free Prorenin, and nonglycosylated Prorenin, with or without M6P, protease inhibitors, or angiotensinogen. HUVECs bound only M6P-containing Prorenin (K(d) 0.9+/-0.1 nmol/L, maximum number of binding sites [B(max)] 1010+/-50 receptors/cell). At 37 degrees C, because of M6P receptor recycling, the amount of Prorenin internalized via M6P receptors was >25 times B(max). Inside the cells, wild-type and K/A-2 Prorenin were proteolytically activated to renin. Renin was subsequently degraded. Protease inhibitors interfered with the latter but not with Prorenin activation, thereby indicating that the activating enzyme is different from any of the known Prorenin-activating enzymes. Incubation with angiotensinogen did not lead to endothelial angiotensin generation, inasmuch as HUVECs were unable to internalize angiotensinogen. Most likely, therefore, in the absence of angiotensinogen synthesis or endocytosis, M6P receptor-mediated Prorenin internalization by endothelial cells represents Prorenin clearance.
-
cardiomyocytes bind and activate native human Prorenin role of soluble mannose 6 phosphate receptors
Hypertension, 2001Co-Authors: Jasper J Saris, F H M Derkx, Jos M J Lamers, Pramod R Saxena, Maarten A D H Schalekamp, A Jan H DanserAbstract:Cardiomyocytes bind, internalize, and activate recombinant human Prorenin through mannose 6-phosphate/insulin-like growth factor II (M6P/IGFII) receptors. To investigate whether this also applies to native human Prorenin, neonatal rat myocytes were incubated for 4 hours at 37 degrees C with various Prorenin-containing human body fluids. Uptake and activation by M6P/IGFII receptors were observed for plasma Prorenin from subjects with renal artery stenosis and/or hypertension and for follicular fluid Prorenin. The total amount of cellular renin and Prorenin (expressed as percentage of the levels of renin and Prorenin in the medium) after 4 hours of incubation was 4 to 10 times lower than after incubation with recombinant human Prorenin. Although plasma contains alkaline phosphatases capable of inactivating the M6P label as well as soluble M6P/IGFII receptors that block Prorenin binding in a competitive manner and proteins (eg, insulin, IGFII) that increase the number of cell-surface M6P/IGFII receptors, these factors were not responsible for the modest uptake of native human Prorenin. Uptake did not occur during incubation of myocytes with plasma Prorenin from anephric subjects or with amniotic fluid Prorenin, and this was not due to the presence of excessively high levels of M6P/IGFII receptors and/or phosphatase activity in these fluids. In conclusion, myocytes are capable of binding, internalizing, and activating native human Prorenin of renal and ovarian origin through M6P/IGFII receptors. Differences in Prorenin glycosylation and/or phosphorylation as well as the concentration of soluble M6P/IGFII receptors and growth factors affecting cell-surface M6P/IGFII receptor density determine the amount of Prorenin entering the heart and thus cardiac angiotensin II production.
-
increase in serum Prorenin precedes onset of microalbuminuria in patients with insulin dependent diabetes mellitus
Diabetologia, 1999Co-Authors: Jacob Deinum, F H M Derkx, B Ronn, E Mathiesen, Wim C J Hop, Maarten A D H SchalekampAbstract:Aims/hypothesis. The renin-angiotensin system is possibly involved in the pathogenesis of diabetic nephropathy. The most striking change in renin-angiotensin system components in blood of patients with diabetic nephropathy is an increased Prorenin concentration. We investigated prospectively serum concentrations of renin-angiotensin system components and the time course of Prorenin increase in normoalbuminuric diabetic patients developing microalbuminuria. Methods. Patients (n = 199) with Type I (insulin-dependent) diabetes mellitus and normoalbuminuria at baseline were prospectively followed for 10 years. The Prorenin concentrations and other variables possibly associated with the occurrence of microalbuminuria, were investigated by Cox-regression analysis. Results. Of the patients 29 developed microalbuminuria. Glycated haemoglobin values were higher at baseline in these patients. Serum Prorenin was similar at baseline but rose in the 29 patients before the development of microalbuminuria and was stable in patients with stable albumin excretion. Renin, angiotensinogen and angiotensin converting enzyme serum concentrations were stable in both groups. Prorenin and glycated haemoglobin were independent prognostic factors for the development of microalbuminuria. A prognostic index, based on these variables, was constructed to estimate the relative risk of developing microalbuminuria. Conclusions/interpretation. Increase in serum Prorenin precedes onset of microalbuminuria in normotensive patients with insulin-dependent diabetes mellitus. High concentrations of Prorenin in combination with high values of glycated haemoglobin can be used as a predictor of development of microalbuminuria. [Diabetologia (1999) 42: 1006–1010]
-
uptake and proteolytic activation of Prorenin by cultured human endothelial cells
Journal of Hypertension, 1999Co-Authors: P J J Admiraal, A Jan H Danser, F H M Derkx, Wim Sluiter, C A M Van Kesteren, Maarten A D H SchalekampAbstract:Objective To investigate the mechanisms of vascular uptake of Prorenin and renin and to explore the possibility of vascular activation of Prorenin. Design and methods Human umbilical vein endothelial cells (HUVECs) cultured in a chemically defined medium were incubated with recombinant human Prorenin or renin in the presence or absence of putative inhibitors of renin internalization. Cell surface-bound and internalized Prorenin or renin were separated by the acid-wash method and were quantified by enzyme-kinetic assays. The activation of Prorenin was also monitored by a direct immunoradiometric assay (IRMA) with use of a monoclonal antibody directed against the -p24-Arg to -1p-Arg C-terminal propeptide sequence of Prorenin. Results Prorenin and renin were internalized at 37 degrees C in a dose-dependent manner; with 1000 microU Prorenin/ml medium, the quantity of cell-associated Prorenin after 3 h of incubation was 9.3 +/- 1.0 microU/4 x 10(5) cells, and with 75,000 microU/ml medium it was 670 +/- 75 microU/4 x 10(5) cells (mean +/- SD; n = 5). Results for renin were similar. Prorenin that had been treated with endoglycosidase H to remove N-linked oligosaccharides was not internalized. Addition of mannose 6-phosphate (M-6-P) to the medium caused a dose-dependent inhibition of renin and Prorenin internalization. Fifty per cent inhibition was observed at 70 micromol/M-6-P, whereas mannose 1-phosphate, glucose 6-phosphate and alpha-methylmannoside at this concentration had no effect Ammonium chloride (50 mmol/l) and monensin (10 micromol/l) also inhibited internalization. Prorenin was activated by HUVECs, and cell-activated Prorenin was only found in the internalized fraction, whereas the surface-bound Prorenin remained inactive. Thus, it appears that the activation of Prorenin took place at the time of its internalization or thereafter. The results of the Prorenin IRMA indicated that activation was associated with proteolytic cleavage of the propeptide. Conclusions Our findings provide evidence for M-6-P receptor-dependent endocytosis of (pro)renin and proteolytic Prorenin activation by vascular endothelial cells.
