A sensitive radiochemical assay for angiotensin-converting enzyme (kinase II).
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ABSTRACT:
SUBMITTER: Chiu AT
PROVIDER: S-EPMC1165618 | biostudies-other | 1975 Jul
REPOSITORIES: biostudies-other
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Project description:Angiotensin converting enzyme (ACE) is well known for its dual actions to convert inactive Ang I to active Ang II, and degrades active bradykinin (BK), which plays an important role in controlling blood pressure. Because it is the bottleneck step for the production of pressor Ang II, it was targeted pharmacologically in the 1970s. Successful ACE inhibitors such as captopril were produced to treat hypertension. Studies on domain-specific ACE inhibitors are continuing to produce effective hypertension-controlling drugs with fewer side effects. ACE2 was discovered in 2000 and it converts Ang II into Ang(1–7), thereby reducing the concentration of Ang II as well as increasing that of Ang(1–7), an important enzyme for Ang(1–7)/Mas receptor signaling. ACE2 also acts as the receptor in the lung for the coronavirus, causing the infamous severe acute respiratory syndrome (SARS) in 2003.
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Project description:Angiotensin (Ang)-converting enzyme 2 (ACE2) cleaves Ang II to form Ang-(1-7). Here we examined whether soluble human recombinant ACE2 (rACE2) can efficiently lower Ang II and increase Ang-(1-7) and whether rACE2 can prevent hypertension caused by Ang II infusion as a result of systemic versus local mechanisms of ACE2 activity amplification. rACE2 was infused via osmotic minipumps for 3 days in conscious mice or acutely in anesthetized mice. rACE2 caused a dose-dependent increase in serum ACE2 activity but had no effect on kidney or cardiac ACE2 activity. After Ang II infusion (40 pmol/min), rACE2 (1 mg/kg per day) resulted in normalization of systolic blood pressure and plasma Ang II. In acute studies, rACE2 (1 mg/kg) prevented the rapid hypertensive effect of Ang II (0.2 mg/kg), and this was associated with both a decrease in Ang II and an increase in Ang-(1-7) in plasma. Moreover, during infusion of Ang II, the effect of rACE2 on blood pressure was unaffected by a specific Ang-(1-7) receptor blocker, A779 (0.2 mg/kg), and infusing supraphysiologic levels of Ang-(1-7) (0.2 mg/kg) had no effect on blood pressure. We conclude that, during Ang II infusion, rACE2 effectively degrades Ang II and, in the process, normalizes blood pressure. The mechanism of rACE2 action results from an increase in systemic, not tissue, ACE2 activity and the lowering of plasma Ang II rather than the attendant increase in Ang-(1-7). Increasing ACE2 activity may provide a new therapeutic target in states of Ang II overactivity by enhancing its degradation, an approach that differs from the current focus on blocking Ang II formation and action.
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Project description:Aerobic exercise training leads to a physiological, nonpathological left ventricular hypertrophy; however, the underlying biochemical and molecular mechanisms of physiological left ventricular hypertrophy are unknown. The role of microRNAs regulating the classic and the novel cardiac renin-angiotensin (Ang) system was studied in trained rats assigned to 3 groups: (1) sedentary; (2) swimming trained with protocol 1 (T1, moderate-volume training); and (3) protocol 2 (T2, high-volume training). Cardiac Ang I levels, Ang-converting enzyme (ACE) activity, and protein expression, as well as Ang II levels, were lower in T1 and T2; however, Ang II type 1 receptor mRNA levels (69% in T1 and 99% in T2) and protein expression (240% in T1 and 300% in T2) increased after training. Ang II type 2 receptor mRNA levels (220%) and protein expression (332%) were shown to be increased in T2. In addition, T1 and T2 were shown to increase ACE2 activity and protein expression and Ang (1-7) levels in the heart. Exercise increased microRNA-27a and 27b, targeting ACE and decreasing microRNA-143 targeting ACE2 in the heart. Left ventricular hypertrophy induced by aerobic training involves microRNA regulation and an increase in cardiac Ang II type 1 receptor without the participation of Ang II. Parallel to this, an increase in ACE2, Ang (1-7), and Ang II type 2 receptor in the heart by exercise suggests that this nonclassic cardiac renin-angiotensin system counteracts the classic cardiac renin-angiotensin system. These findings are consistent with a model in which exercise may induce left ventricular hypertrophy, at least in part, altering the expression of specific microRNAs targeting renin-angiotensin system genes. Together these effects might provide the additional aerobic capacity required by the exercised heart.
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Project description:The third edition of the Handbook of Proteolytic Enzymes aims to be a comprehensive reference work for the enzymes that cleave proteins and peptides, and contains over 850 chapters. Each chapter is organized into sections describing the name and history, activity and specificity, structural chemistry, preparation, biological aspects, and distinguishing features for a specific peptidase. The subject of Chapter 100 is Angiotensin-Converting Enzyme-2. Keywords: Angiotensin, angiotensin-converting enzyme 2 (ACE2), apelin, bradykinin, carboxypeptidase, cardiovascular, collectrin, renin-angiotensin system, SARS virus, shedding, transmembrane, vasoactive, zinc-binding motif.
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Project description:BACKGROUND:Emerging evidence suggests a possible role of the renin angiotensin system in the pathophysiologic process of Alzheimer's disease, of which angiotensin converting enzyme-1 (ACE-1) and angiotensin II (ANGII) are important proteins. Few studies evaluated associations between blood ACE-1 and none between ANGII levels, and cognition. OBJECTIVE:Our pilot study was aimed to examine associations between blood ACE-1 and ANG II levels and cognitive function in non-demented participants at baseline and over a 1-year period. METHODS:56 participants were included from the Brain Health Substudy of the Baltimore Experience Corps Study. Linear regression analysis, adjusting for confounders, was used to determine associations between baseline ACE-1 and ANGII, and baseline and 1-year follow-up measures of psychomotor and processing speed, executive function, verbal learning memory and working memory, and whether these associations were mediated by blood pressure. RESULTS:Participants were predominantly female (75%), African-American (93%), with mean age of 67.8 years and education of 14.3 years. There were no associations between baseline ACE-1 or ANGII levels and cognitive function; however, there were significant association between baseline ACE-1 levels and 1-year follow-up Trail Making Test, Part A (β= 0.003, p = 0.04) and Digit Span (β= -0.001, p = 0.02). CONCLUSIONS:In this cognitively intact sample, elevated ACE-1 levels were associated with worse processing speed and working memory after 1 year. Findings from this pilot study suggest that changes in the RAS are associated with alterations in cognitive function warranting further assessment of the role of RAS in neurodegenerative disorders.
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Project description:Antigen processing and presentation through the MHC class II pathway is critical for activating T helper cells. Angiotensin-converting enzyme (ACE) is a carboxyl peptidase expressed by antigen-presenting cells. By analysis of ACE null (knockout), wild-type, and ACE-overexpressing (ACE10) mice and the antigen-presenting cells derived from these mice, we found that ACE has a physiological role in the processing of peptides for MHC class II presentation. The efficiency of presenting MHC class II epitopes from ovalbumin (OVA) and hen egg lysosome is markedly affected by cellular ACE levels. Mice overexpressing ACE in myeloid cells have a much more vigorous CD4+ T-cell and antibody response when immunized with OVA. ACE is present in the endosomal pathway where MHC class II peptide processing and loading occur. The efficiency of MHC class II antigen presentation can be altered by ACE overexpression or ACE pharmacological inhibition. Thus, ACE is a dynamic participant in processing MHC class II peptides. Manipulation of ACE expression by antigen-presenting cells may prove to be a novel strategy to alter the immune response.
| S-EPMC5493495 | biostudies-literature
Project description:Angiotensin-converting enzyme type 2 (ACE2) is a pivotal component of the renin-angiotensin system, promoting the conversion of angiotensin II (Ang-II) to Ang-(1-7). We previously reported that decreased ACE2 expression and activity contributes to the development of Ang-II-mediated hypertension in mice. The present study aimed to investigate the mechanisms involved in ACE2 downregulation during neurogenic hypertension. In ACE2-transfected Neuro-2A cells, Ang-II treatment resulted in a significant attenuation of ACE2 enzymatic activity. Examination of the subcellular localization of ACE2 revealed that Ang-II treatment leads to ACE2 internalization and degradation into lysosomes. These effects were prevented by both the Ang-II type 1 receptor (AT1R) blocker losartan and the lysosomal inhibitor leupeptin. In contrast, in HEK293T cells, which lack endogenous AT1R, Ang-II failed to promote ACE2 internalization. Moreover, this effect could be induced after AT1R transfection. Furthermore, coimmunoprecipitation experiments demonstrated that AT1R and ACE2 form complexes, and these interactions were decreased by Ang-II treatment, which also enhanced ACE2 ubiquitination. In contrast, ACE2 activity was not changed by transfection of AT2 or Mas receptors. In vivo, Ang-II-mediated hypertension was blunted by chronic infusion of leupeptin in wildtype C57Bl/6, but not in ACE2 knockout mice. Overall, this is the first demonstration that elevated Ang-II levels reduce ACE2 expression and activity by stimulation of lysosomal degradation through an AT1R-dependent mechanism.
| S-EPMC4231883 | biostudies-literature
Project description:Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, is being defined as the worst pandemic disease of modern times. Several professional health organizations have published position papers stating that there is no evidence to change the use of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) in the management of elevated blood pressure in the context of avoiding or treating COVID-19 infection. In this article, we review the evidence on the relationship between the renin-angiotensin-aldosterone system and COVID-19 infection. In agreement with current guidelines, patients with hypertension should continue taking antihypertensive medications as prescribed without interruption. Because ACEIs and ARBs are also used to retard the progression of chronic kidney disease, we suggest that these recommendations also apply to the use of these agents in chronic kidney disease. No differences generally exist between ARBs and ACEIs in terms of efficacy in decreasing blood pressure and improving other outcomes, such as all-cause mortality, cardiovascular mortality, myocardial infarction, heart failure, stroke, and end-stage renal disease. The ACEIs are associated with cough secondary to accumulation of bradykinin and angioedema, and withdrawal rates due to adverse events are lower with ARBs. Given their equal efficacy but fewer adverse events, ARBs could potentially be a more favorable treatment option in patients with COVID-19 at higher risk for severe forms of disease.
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Project description:Angiotensin-converting enzyme 2 (ACE2) cleaves angiotensin II (AngII) to form angiotensin-(1-7) (Ang-(1-7)), which generally opposes effects of AngII. AngII infusion into hypercholesterolemic male mice induces formation of abdominal aortic aneurysms (AAAs). This study tests the hypothesis that deficiency of ACE2 promotes AngII-induced AAAs, whereas ACE2 activation suppresses aneurysm formation.ACE2 protein was detectable by immunostaining in mice and human AAAs. Whole-body deficiency of ACE2 significantly increased aortic lumen diameters and external diameters of suprarenal aortas from AngII-infused mice. Conversely, ACE2 deficiency in bone marrow-derived cells had no effect on AngII-induced AAAs. In contrast to AngII-induced AAAs, ACE2 deficiency had no significant effect on external aortic diameters of elastase-induced AAAs. Because ACE2 deficiency promoted AAA formation in AngII-infused mice, we determined whether ACE2 activation suppressed AAAs. ACE2 activation by administration of diminazene aceturate (30 mg/kg per day) to Ldlr(-/-) mice increased kidney ACE2 mRNA abundance and activity and elevated plasma Ang-(1-7) concentrations. Unexpectedly, administration of diminazene aceturate significantly reduced total sera cholesterol and very low-density lipoprotein-cholesterol concentrations. Notably, diminazene aceturate significantly decreased aortic lumen diameters and aortic external diameters of AngII-infused mice resulting in a marked reduction in AAA incidence (from 73% to 29%). None of these effects of diminazene aceturate were observed in the Ace2(-/y) mice.These results demonstrate that ACE2 exerts a modulatory role in AngII-induced AAA formation, and that therapeutic stimulation of ACE2 could be a benefit to reduce AAA expansion and rupture in patients with an activated renin-angiotensin system.
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Project description:Coronavirus disease 2019 (COVID-19) is a viral pandemic precipitated by the severe acute respiratory syndrome coronavirus 2. Since previous reports suggested that viral entry into cells may involve angiotensin converting enzyme 2, there has been growing concern that angiotensin converting enzyme inhibitor (ACEI) and angiotensin II receptor blocker (ARB) use may exacerbate the disease severity. In this retrospective, single-center US study of adult patients diagnosed with COVID-19, we evaluated the association of ACEI/ARB use with hospital admission. Secondary outcomes included: ICU admission, mechanical ventilation, length of hospital stay, use of inotropes, and all-cause mortality. Propensity score matching was performed to account for potential confounders. Among 590 unmatched patients diagnosed with COVID-19, 78 patients were receiving ACEI/ARB (median age 63 years and 59.7% male) and 512 patients were non-users (median age 42 years and 47.1% male). In the propensity matched population, multivariate logistic regression analysis adjusting for age, gender and comorbidities demonstrated that ACEI/ARB use was not associated with hospital admission (OR 1.2, 95%CI 0.5 to 2.7, p = 0.652). CAD and CKD/end stage renal disease [ESRD] remained independently associated with admission to hospital. All-cause mortality, ICU stay, need for ventilation, and inotrope use was not significantly different between the 2 study groups. In conclusion, among patients who were diagnosed with COVID-19, ACEI/ARB use was not associated with increased risk of hospital admission.
| S-EPMC7354276 | biostudies-literature