Male fertility is dependent on dipeptidase activity of testis ACE.
Explore the source record for details and available documents.
Amino Acid Motifs↗
Biomedical subjects
Pierre Corvol
Publications and source records attributed to Pierre Corvol.
Role of the renin-angiotensin system in primitive erythropoiesis in the chick embryo.
Inactivation of the gene encoding mouse angiotensin I-converting enzyme (ACE), which converts angiotensin I into angiotensin II, results in anemia in adult animals. This anemia is corrected by angiotensin II, demonstrating the involvement of angiotensin II in adult (definitive) erythropoiesis. We investigated the possible role of the renin-angiotensin system (RAS) in primitive erythropoiesis in the yolk sac of the chicken embryo. Enzymatically active ACE was detected in the yolk sac endoderm, concomitantly with the differentiation of blood islands in the adjacent yolk sac mesoderm. The simultaneous presence of all the other components of the RAS (renin, angiotensinogen, angiotensin II receptor) in the vicinity of the blood islands suggests that this system is involved in erythropoiesis. This role was confirmed by in vivo blockade of the RAS with fosinoprilate, a specific inhibitor of chicken ACE, which decreased hematocrit by 15%. A similar decrease in hematocrit was observed following treatment with the angiotensin II receptor antagonist Sar1-Ile8-Angiotensin II, suggesting that this effect was mediated by angiotensin II. Both treatments affected hematocrit by decreasing erythroblast proliferation. Thus, the RAS, and its effector peptide angiotensin II in particular, modulates primitive erythropoiesis.
Angiotensin-Converting Enzyme Inhibitors↗
Characterization of the first non-insect invertebrate functional angiotensin-converting enzyme (ACE): leech TtACE resembles the N-domain of mammalian ACE.
Angiotensin-converting enzyme (ACE) is a zinc metallopeptidase that plays a major role in blood homoeostasis and reproduction in mammals. In vertebrates, both transmembrane and soluble ACE, containing one or two homologous active sites, have been characterized. So far, several ACEs from invertebrates have been cloned, but only in insects. They are soluble and display a single active site. Using biochemical procedures, an ACE-like activity was detected in our model, the leech, Theromyzon tessulatum. Annelida is the most distant phylum in which an ACE activity has been observed. To gain more insight into the leech enzyme, we have developed a PCR approach to characterize its mRNA. The approx. 2 kb cDNA has been predicted to encode a 616-amino-acid soluble enzyme containing a single active site, named TtACE (T. tessulatum ACE). Surprisingly, its primary sequence shows greater similarity to vertebrates than to invertebrates. Stable in vitro expression of TtACE in transfected Chinese-hamster ovary cells revealed that the leech enzyme is a functional metalloprotease. As in mammals, this 79 kDa glycosylated enzyme functions as a dipeptidyl carboxypeptidase capable of hydrolysing angiotensin I to angiotensin II. However, a weak chloride inhibitory effect and acetylated N-acetyl-SDKP (Ac SDAcKP) hydrolysis reveal that TtACE activity resembles that of the N-domain of mammalian ACE. In situ hybridization shows that its cellular distribution is restricted to epithelial midgut cells. Although the precise roles and endogenous substrates of TtACE remain to be identified, characterization of this ancestral peptidase will help to clarify its physiological roles in non-insect invertebrate species.
Amino Acid Sequence↗
Brain renin-angiotensin system blockade by systemically active aminopeptidase A inhibitors: a potential treatment of salt-dependent hypertension.
The hyperactivity of the brain renin-angiotensin system (RAS) has been implicated in the development and maintenance of hypertension in several types of experimental and genetic hypertension animal models. We previously reported that in the murine brain, aminopeptidase A (APA) is involved in the conversion of angiotensin II (AngII) to AngIII and that AngIII is one of the main effector peptides of the brain RAS in the control of vasopressin release. Here we report that brain AngIII exerts a tonic stimulatory effect on blood pressure in a model of salt-dependent hypertension, the DOCA-salt rat, characterized by a depressed systemic but a hyperactive brain RAS. Similar high blood pressure accompanied by a low systemic renin state was described in some patients, especially in hypertensive African Americans who are resistant to treatment by blockers of the systemic RAS. We developed RB150, a prodrug of the specific and selective APA inhibitor, EC33. RB150 given i.v. is able to cross the blood-brain barrier, to inhibit brain APA, and to block the formation of central AngIII. A single dose of systemic RB150 (15 mg/kg, i.v.) in conscious DOCA-salt rats inhibited brain APA activity and markedly reduced blood pressure for up to 24 h. These results demonstrate the crucial role of brain APA as a candidate target for the treatment of hypertension and suggest that RB150, a potent systemically active APA inhibitor, could be the prototype of a new class of antihypertensive agents for the treatment of certain forms of hypertension.
Animals↗
Inhibition of angiotensin I-converting enzyme induces radioprotection by preserving murine hematopoietic short-term reconstituting cells.
Angiotensin I-converting enzyme (ACE) inhibitors can affect hematopoiesis by several mechanisms including inhibition of angiotensin II formation and increasing plasma concentrations of AcSDKP (acetyl-N-Ser-Asp-Lys-Pro), an ACE substrate and a negative regulator of hematopoiesis. We tested whether ACE inhibition could decrease the hematopoietic toxicity of lethal or sublethal irradiation protocols. In all cases, short treatment with the ACE inhibitor perindopril protected against irradiation-induced death. ACE inhibition accelerated hematopoietic recovery and led to a significant increase in platelet and red cell counts. Pretreatment with perindopril increased bone marrow cellularity and the number of hematopoietic progenitors (granulocyte macrophage colony-forming unit [CFU-GM], erythroid burst-forming unit [BFU-E], and megakaryocyte colony-forming unit [CFU-MK]) from day 7 to 28 after irradiation. Perindopril also increased the number of hematopoietic stem cells with at least a short-term reconstitutive activity in animals that recovered from irradiation. To determine the mechanism of action involved, we evaluated the effects of increasing AcSDKP plasma concentrations and of an angiotensin II type 1 (AT1) receptor antagonist (telmisartan) on radioprotection. We found that the AT1-receptor antagonism mediated similar radioprotection as the ACE inhibitor. These results suggest that ACE inhibitors and AT1-receptor antagonists could be used to decrease the hematopoietic toxicity of irradiation.
Angiotensin-Converting Enzyme Inhibitors↗
Effect of reduced angiotensin-converting enzyme gene expression and angiotensin-converting enzyme inhibition on angiotensin and bradykinin peptide levels in mice.
There is uncertainty about the contribution of angiotensin-converting enzyme (ACE) to angiotensin II formation, with recent studies suggesting that non-ACE enzymes may be the predominant pathway of angiotensin II formation in kidney, heart, and lung. To investigate the role of ACE in angiotensin II formation, we measured angiotensin I and II levels in blood, kidney, and heart of 2 mouse genetic models (ACE.1 and ACE.4) of reduced somatic ACE gene expression and in blood, kidney, heart, lung, adrenal, and brain of mice administered the ACE inhibitor lisinopril. We also measured the levels of bradykinin (1-9) and its ACE metabolite bradykinin (1-7). Reduced ACE gene expression and ACE inhibition had similar effects on angiotensin and bradykinin peptide levels. Angiotensin II levels were reduced by 70% to 97% in blood, 92% to 99% in kidney, 93% to 99% in heart, 97% in lung, and 85% in adrenal and brain. The marked reductions in angiotensin II/angiotensin I ratio indicated that ACE was responsible for at least 90% of angiotensin I conversion to angiotensin II in blood, kidney, heart, lung, and brain, and at least 77% in adrenal. Blood bradykinin (1-9) levels were increased 6.4-fold to 8.4-fold. Heart bradykinin (1-9) levels were increased in ACE.4 mice and the bradykinin (1-7)/bradykinin (1-9) ratio was reduced in kidney and heart of ACE.4 mice and heart of lisinopril-treated mice. These studies demonstrate that ACE is the predominant pathway of angiotensin II formation in blood and tissues of mice and plays a major role in bradykinin (1-9) metabolism in blood and, to a lesser extent, in kidney and heart.
Adrenal Glands↗
Role of the N-terminal catalytic domain of angiotensin-converting enzyme investigated by targeted inactivation in mice.
Angiotensin-converting enzyme (ACE) produces the vasoconstrictor angiotensin II. The ACE protein is composed of two homologous domains, each binding zinc and each independently catalytic. To assess the physiologic significance of the two ACE catalytic domains, we used gene targeting in mice to introduce two point mutations (H395K and H399K) that selectively inactivated the ACE N-terminal catalytic site. This modification does not affect C-terminal enzymatic activity or ACE protein expression. In addition, the testis ACE isozyme is not affected by the mutations. Analysis of homozygous mutant mice (termed ACE 7/7) showed normal plasma levels of angiotensin II but an elevation of plasma and urine N-acetyl-Ser-Asp-Lys-Pro, a peptide suggested to inhibit bone marrow maturation. Despite this, ACE 7/7 mice had blood pressure, renal function, and hematocrit that were indistinguishable from wild-type mice. We also studied compound heterozygous mice in which one ACE allele was null (no ACE expression) and the second allele encoded the mutations selectively inactivating the N-terminal catalytic domain. These mice produced approximately half the normal levels of ACE, with the ACE protein lacking N-terminal catalytic activity. Despite this, the mice have a phenotype indistinguishable from wild-type animals. This study shows that, in vivo, the presence of the C-terminal ACE catalytic domain is sufficient to maintain a functional renin-angiotensin system. It also strongly suggests that the anemia present in ACE null mice is not due to the accumulation of the peptide N-acetyl-Ser-Asp-Lys-Pro.
Anemia↗
Troponin T as a marker of differentiation revealed by proteomic analysis in renal arterioles.
Renovascular hypertension is characterized by stenosis of the renal artery and high plasma renin levels. The renal phenotype is characterized by high levels of renin in the hypoperfused kidney due to the recruitment of renin-producing cells along the afferent arterioles. This increase in myoepithelioïd cells is due mainly to the differentiation of existing smooth muscle cells with acquisition of a secretory phenotype. To understand the molecular mechanisms involved in this recruitment, we used the established rat model of renovascular hypertension known as the two-kidney, one-clip model in the Lewis rat. Renal arterioles were isolated using magnetized iron suspension. Differential proteomic analysis was performed using 2-D polyacrylamide gel electrophoresis followed by mass spectrometry. Comparative analysis of soluble proteins extracted from afferent arterioles of clipped and contralateral kidneys showed 14 proteins significantly differentially expressed by at least a factor of 2. These proteins were identified by mass spectrometry. The most striking protein revealed by proteomics is troponin T, which is down-regulated in the afferent arterioles of the clipped kidney. Confocal microscopy showed that troponin T is specific of the smooth muscle phenotype and absent in the myoepithelioïd phenotype. Our data suggest that troponin T is only present in renal smooth muscle cells.
Animals↗
Hyperglycemia-induced defects in angiogenesis in the chicken chorioallantoic membrane model.
Diabetes is associated with abnormal angiogenesis. Increased angiogenesis contributes to severe forms of diabetic retinopathy, but angiogenesis is decreased in response to myocardial ischemia in diabetic patients. We evaluated the direct effect of hyperglycemia on angiogenesis in the chicken chorioallantoic membrane assay, a model of active neoangiogenesis. Hyperglycemia, lasting up to 7 days, was induced in 7-day-old chick embryos by a single intravitellus glucose injection. Control embryos received either water (volumic control) or mannitol (osmotic control). Hyperglycemia decreased angiogenesis in this model from the 5th day on. The pattern and expression level of the main vascular growth factors' genes were not altered by hyperglycemia, as assessed by in situ hybridization and semiquantitative RT-PCR. As early as 2 days after hyperglycemia was induced, an increased apoptosis of endothelial cells and pericytes was detected by transferase-mediated deoxyuridine triphosphate nick-end labeling assay and electron microscopy. In the meantime, endothelial cell proliferation was decreased, as assessed by incorporation of bromo-deoxyuridine. Hyperglycemia can therefore impair angiogenesis without altering the expression level of vascular growth factors through induction of apoptosis and decreased proliferation of endothelial cells.
Allantois↗
[Ontogenesis of the renin system. Implication of this system in hematopoiesis].
The role of the renin-angiotensin system was previously thought to be restricted to the cardiovascular system. It now appears that this system also plays an important role during development, and especially in hematopoiesis. The different elements of the renin-angiotensin system are expressed early during embryogenesis. The renin system plays a role at different steps of hematopoiesis, notably during the first wave of hematopoiesis in the chick embryo system (primitive hematopoiesis), and during the adult phase of hematopoiesis in the fetus (definitive hematopoiesis). In addition, this system is involved in hematopoiesis following experimental irradiation of mice: renin system antagonists improve hematopoiesis in this situation.
Angiotensin II↗
[The renin-angiotensin system in human brain and brain tumors: a function unrelated to blood pressure control?].
The renin-angiotensin system (RAS), in addition to controlling blood pressure and the sodium-water balance, may be involved in cell growth and/or death in the brain. In order to address this issue, we compared the expression of RAS components in surgical specimens of human brain tumors and adjacent tissue. Human brain tumor cells and rat brain cells in culture were used to evaluate RAS functions. We found evidence that the RAS may be involved in maintaining the functions of the cerebral vasculature (the blood-brain-barrier) by controlling the ratio between angiotensin II and angiotensin III production, and by playing a more direct role in the survival of astroglial cells.
Angiotensin II↗
Genetic determinants of nonmodulating hypertension.
We sought to determine whether genes of the renin-angiotensin-aldosterone system can predict the nonmodulating intermediate phenotype in essential hypertension. Aldosterone responses to angiotensin II were assessed in 298 subjects with hypertension. Subjects were genotyped at the angiotensinogen M235T, angiotensin-converting enzyme I/D, aldosterone synthase C-344 T, renin, angiotensin II type 1 receptor, and adducin loci. The data were analyzed by Student t test, ANOVA, stepwise linear regression and general linear model or GENMOD regression techniques, and chi2 analysis odds ratios (ORs). Aldosterone response varied by genotype for angiotensin and aldosterone synthase but not for the other loci. The combination of angiotensinogen 235 TT and angiotensin-converting enzyme DD showed further reduction (P=0.0377) when compared with angiotensinogen 235 TT alone, an example of genetic epistasis. When the subject was required also to possess the CYP11B2 -344 TT genotype, there was a further substantial reduction. Of these 3 loci, only angiotensinogen 235 TT significantly increased the OR of predicting the nonmodulating hypertensive phenotype (OR, 2.00; 95% confidence interval, 1.152 to 3.51). However, when angiotensin-converting enzyme DD was combined with angiotensinogen 235 TT, the OR nearly doubled to 3.74, with a further increase to 5.36-fold when the subject possessed all 3 genotypes. Thus, the angiotensinogen, angiotensin-converting enzyme, and aldosterone synthase genotypes identified individuals with the nonmodulating phenotype with an increasing degree of fidelity. For this subclass of essential hypertension, it is likely that genotyping can be substituted for complex phenotyping for therapeutic and preventive decision making.
Age Factors↗
Mutations in the SDHB gene are associated with extra-adrenal and/or malignant phaeochromocytomas.
Germ-line mutations in the genes encoding succinate dehydrogenase complex subunits B (SDHB) and D (SDHD) have been reported in familial paragangliomas and apparently sporadic phaeochromocytomas (ASP), but the genotype-phenotype relationships of these mutations are unknown. Eighty-four patients (all but 2 followed up for 8.8 +/- 5.7 years) with ASP (57 with adrenal tumors, 27 with extra-adrenal, multiple, malignant, or recurrent tumors) were screened for the major susceptibility genes for phaeochromocytoma (RET, VHL, SDHD, and SDHB). Thirty-three tumors were available for molecular analysis, enzyme assays, and immunohistochemistry. No (0%) RET and 2 (2.4%) VHL mutations were detected. Only two coding single nucleotide polymorphisms in the SDHD gene (G12S and H50R) were found in 6 patients (7%). Conversely, six deleterious mutations in the SDHB gene were identified in 8 patients (9.5%). Ectopic site and recurrence or malignancy were strongly associated with SDHB mutations (7 of 8, 87%, versus 20 of 76, 26%; P = 0.001). Somatic DNA analysis indicated a loss of heterozygosity at chromosome 1p36 (SDHB locus) in 16 of 33 cases (48%). A loss of heterozygosity at the SDHB locus was found in all tumors with SDHB mutation, and assays of respiratory chain enzymes showed a complete loss of complex II catalytic activity. The vascular architecture of tumors with SDHB mutations displayed features typical of malignancy. These data strongly suggest that SDHB gene is a tumor suppressor gene and that the identification of germ-line mutations in SDHB gene in patients with ASPs should be considered as a high-risk factor for malignancy or recurrence.
Adrenal Gland Neoplasms↗
Vascular smooth muscle cells efficiently activate a new proteinase cascade involving plasminogen and fibronectin.
The plasminogen/plasmin system is involved in vascular wall remodeling after injury, through extracellular matrix (ECM) degradation and proteinase activation. Vascular smooth muscle cells (VSMCs) synthesize various components of the plasminogen/plasmin system. We investigated the conversion of plasminogen into plasmin in primary cultured rat VSMCs. VSMCs efficiently converted exogenous plasminogen into plasmin in a time- and dose-dependent manner. We measured plasmin activity by monitoring the hydrolysis of Tosyl-G-P-R-Mca, a fluorogenic substrate of plasmin. Cell-mediated plasmin activation was associated with the degradation of ECM, as revealed by fibronectin proteolysis. Plasmin also activated a proteinase able to hydrolyze Mca-P-L-G-L-Dpa-A-R-NH(2), a fluorogenic substrate of matrix metalloproteinases (MMPs). However, this proteinase was not inhibited by an MMP inhibitor. Furthermore, this proteinase displayed similar biochemical and pharmacological properties to fibronectin-proteinase, a recently identified zinc-dependent metalloproteinase located in the gelatin-binding domain of fibronectin. These results show that VSMCs convert exogenous plasminogen into plasmin in their pericellular environment. By hydrolyzing matrix protein plasmin activates a latent metalloproteinase that differs from MMP, fibronectin-proteinase. This metalloproteinase may participate to vascular wall remodeling, in concert with other proteinases.
Animals↗
Familial hyperkalemic hypertension: phenotypic analysis in a large family with the WNK1 deletion mutation.
Explore the source record for details and available documents.
Adolescent↗
Akt is a major downstream target of PI3-kinase involved in angiotensin II-induced proliferation.
Different signal transduction cascades have been implicated in angiotensin II (Ang II)-mediated cell growth, such as the extracellular signal-regulated kinase 1/2 (ERK1/2) and the phosphatidylinositol 3-kinase (PI3K) pathways. To identify the downstream targets of PI3K involved in Ang II-induced proliferation, we used both rat aortic smooth muscle (RASM) cells and a CHO cell line stably expressing the rat AT1A receptor. The ERK1/2 and PI3K pathways are independently activated and implicated in Ang II-mediated DNA synthesis and cell number increase in these 2 cell lines. In addition, a specific inhibitor of Akt inhibited Ang II-induced Akt phosphorylation, DNA synthesis and proliferation in CHO-AT1A or RASM cells. A dominant-negative mutant of Akt was also found to selectively block Ang II-induced proliferation of CHO-AT1A cells. To further elucidate the signaling events leading to Akt activation, we used an AT1 receptor mutant (AT1AD74E), deficient for Gq protein coupling, and the intracellular calcium chelator BAPTA-AM. Although altered Akt and ERK1/2 activation was observed in the CHO-AT1AD74E cell line, blockade of intracellular calcium elevation did not affect phosphorylation of these kinases. These results provide the first evidence of a specific and necessary role of Akt in Ang II-induced proliferation through a Gq protein-dependent calcium-independent pathway.
Angiotensin II↗
Inhibition of angiogenesis: a new function for angiotensinogen and des(angiotensin I)angiotensinogen.
Angiotensinogen (AGT) can be schematically considered to consist of a combination of an angiotensin I (Ang I) function, located at the N-terminal end, and the presence of a serpin (serine protease inhibitor) structure at the opposite end. des(Ang I)AGT, which accounts for more than 97% of the molecule, apparently has no function. Several serpins (antithrombin, maspin, pigment epithelial-derived factor, and kallistatin) have been recently shown to exert an antiangiogenic activity, suggesting a common mechanism of endothelial cell proliferation and migration. AGT and its renin-cleaved product, des(Ang I)AGT, are also angiogenesis inhibitors, both in vitro and in vivo at concentrations within the range of those observed in plasma. This property most likely results from the structure analogy of AGT with serpins. The pathologic relevance of this new function is still not known, but AGT produced by glial cells may play a role in the stabilization of the blood-brain barrier. These new data must be considered in light of the overall action of the renin-angiotensin system in angiogenesis.
Angiogenesis Inhibitors↗
Angiopoietin-like 4 is a proangiogenic factor produced during ischemia and in conventional renal cell carcinoma.
Ischemic and solid tumor tissues are less well perfused than normal tissue, leading to metabolic changes and chronic hypoxia, which in turn promotes angiogenesis. We identified human angiopoietin-like 4 (angptl4) as a gene with hypoxia-induced expression in endothelial cells. We showed that the levels of both mRNA and protein for ANGPTL4 increased in response to hypoxia. When tested in the chicken chorioallantoic membrane assay, ANGPTL4 induced a strong proangiogenic response, independently of vascular endothelial growth factor. In human pathology, ANGPTL4 mRNA is produced in ischemic tissues, in conditions such as critical leg ischemia. In tumors, ANGPTL4 is produced in the hypoxic areas surrounding necrotic regions. We observed particularly high levels of ANGPTL4 mRNA in tumor cells of conventional renal cell carcinoma. Other benign and malignant renal tumor cells do not produce ANGPTL4 mRNA. This molecule therefore seems to be a marker of conventional renal cell carcinoma. ANGPTL4, originally identified as a peroxisome proliferator-activated receptor alpha and gamma target gene, has potential for use as a new diagnostic tool and a potential therapeutic target, modulating angiogenesis both in tumors and in ischemic tissues. This study also suggests that ANGPTL4 may provide a link between metabolic disorders and hypoxia-induced angiogenesis.
Angiopoietin-Like Protein 4↗